UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Modification and utilization of sewage sludge-based activated carbon as metal adsorbents Gong, XuDong 2013

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
24-ubc_2013_fall_gong_xudong.pdf [ 3.9MB ]
Metadata
JSON: 24-1.0074198.json
JSON-LD: 24-1.0074198-ld.json
RDF/XML (Pretty): 24-1.0074198-rdf.xml
RDF/JSON: 24-1.0074198-rdf.json
Turtle: 24-1.0074198-turtle.txt
N-Triples: 24-1.0074198-rdf-ntriples.txt
Original Record: 24-1.0074198-source.json
Full Text
24-1.0074198-fulltext.txt
Citation
24-1.0074198.ris

Full Text

  MODIFICATION AND UTILIZATION OF SEWAGE SLUDGE-BASED ACTIVATED CARBON AS METAL ADSORBENTS  by XuDong Gong  B.A.Sc., The University of British Columbia, 2011  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF  MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Civil Engineering)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  August 2013  ? XuDong Gong, 2013 ii  Abstract Sewage sludge is the by-product of the wastewater treatment process. Its conventional disposal methods include incineration, landfill, and agricultural land application. As populations grow, the volume of sewage sludge likewise increases. The conventional disposal methods including incineration, landfill and application to agricultural land are unsustainable and have major limitations. Therefore, a more sustainable and economical alternative is needed by converting this waste material into the resource that can enhance environmental sustainability. Due to the carbonaceous nature of sewage sludge, the aims of this research are to convert a sewage sludge sample into activated carbon, to further explore the modification of sewage sludge based activated carbon (SBAC) to improve metal sorption capacity, and to investigate the effectiveness of the modified SBACs (MSBACs) by selecting the MSBAC with best adsorption performance to compare with other adsorbents. The SBAC was prepared through the chemical activation of ZnCl2, followed by pyrolysis in an electric furance, and it was further modified by nitric acid. Batch sorption tests were conducted in which the SBAC and MSBACs were contacted with distilled water spiked with lead ions (Pb2+) to measure their adsorptivity for Pb2+. The Pb2+ sorption capacity of MSBACs was further compared with zeolite, grundite, kaolinite, and commercial activated carbon. Batch sorption tests were conducted in which MSBAC10 was contacted with natural acid rock drainage (ARD) and the ARD solution spiked with Al3+, Fe2+, Cu2+ and Zn2+ to further demonstrate its application of removing multiple-metal components. The batch sorption tests showed the great improvement of Pb2+ uptake capacity of the SBAC after modification. Compared with other MSBACs and adsorbents, MSBAC10 exhibited the strongest and fastest sorption behavior. The adsorptivity for lead ions in five minutes was iii  ranked as: MSBAC10 > illite (grundite) > zeolite > commercial activated carbon (CAC) > kaolinite > perlite, and grundite ? zeolite ? MSBAC10 ? CAC > kaolinite > perlite over a 24-hour period, whereas, MSBAC?s application on the natural ARD solution, removed 98.88% of Cu, 42.60% of Zn and 34.63% of Al.    iv  Preface  This thesis is original, unpublished, independent work by the author, XuDong Gong.    v  Table of Contents  Abstract  ........................................................................................................................................ ii Preface  ....................................................................................................................................... iv Table of Contents .......................................................................................................................... v List of Tables ............................................................................................................................... xii List of Figures ............................................................................................................................. xiv List of Abbreviations ............................................................................................................... xviii Acknowledgements .................................................................................................................... xix Chapter 1: INTRODUCTION ................................................................................................... 1 1.1 Problem Statement ............................................................................................................... 1 1.2 Research Objectives ............................................................................................................. 4 1.3 Research Plan ....................................................................................................................... 5 1.4 Thesis Outline ...................................................................................................................... 5 1.5 Research Contributions and Novelty ................................................................................... 7 Chapter 2: BACKGROUND AND LITERATURE REVIEW ............................................... 8 2.1 Introduction of Sewage Sludge ............................................................................................ 8 2.2 Production of Activated Carbon .......................................................................................... 9 2.2.1 Carbonization ................................................................................................................. 9 2.2.2 Activation ..................................................................................................................... 10 2.2.2.1 Physical Activation .......................................................................................... 10 2.2.2.2 Chemical Activation ........................................................................................ 11 2.3 The Chemical Activation of Sludge Based Activated Carbons ......................................... 12 vi  2.3.1 Potassium Hydroxide (KOH) ....................................................................................... 16 2.3.2 Zinc Chloride (ZnCl2) ................................................................................................... 17 2.4 The Modification of Activated Carbons ............................................................................ 18 2.5 The Stability of SBACs ..................................................................................................... 22 2.6 Heavy Metals and SBACs Interactions ............................................................................. 23 2.6.1 Sorption ........................................................................................................................ 23 2.6.2 Ion Exchange ................................................................................................................ 24 2.6.3 Precipitation.................................................................................................................. 24 Chapter 3: MATERIALS AND METHODOLOGIES .......................................................... 25 3.1 Introduction ........................................................................................................................ 25 3.2 Material Origins and Descriptions ..................................................................................... 26 3.2.1 Raw Sludge (RS) .......................................................................................................... 26 3.2.2 Adsorbents Converted from Raw Sludge ..................................................................... 26 3.2.3 Other Adsorbents .......................................................................................................... 27 3.2.4 Collected Contaminated Solution ................................................................................. 27 3.3 Physical and Chemical Characterizations .......................................................................... 29 3.3.1 Physical Properties ....................................................................................................... 29 3.3.2 Chemical Properties ..................................................................................................... 30 3.3.3 The Mineralogical Characteristics of CS and SBAC ................................................... 31 3.4 Chemical Solutions ............................................................................................................ 32 3.5 The Preparation of Carbonized Sludge (CS) and Sludge Based Activated Carbon (SBAC)34 3.5.1 Experimental Apparatus ............................................................................................... 34 3.5.2 The Conversion of Sewage Sludge to Carbonized Sludge (CS) .................................. 36 vii  3.5.3 The Conversion of Sewage Sludge into Sludge Based Activated Carbon (SBAC) ..... 36 3.6 Modification of SBAC ....................................................................................................... 37 3.7 Batch Sorption and Desorption Tests ................................................................................ 37 3.7.1 Stability Tests for Dissolved Metals ............................................................................ 37 3.7.2 The Batch Sorption Test Programs .............................................................................. 38 3.7.3 The Leachability of Adsorbents after Metal Sorption .................................................. 40 3.7.4 Adsorptivity Calculation and Curve Plotting ............................................................... 40 3.7.5 Kinetics and Sorption Isotherm Models ....................................................................... 41 3.7.6 Repeated Batch Sorption Tests..................................................................................... 42 3.7.7 Batch Sorption Test for Different Adsorbents ............................................................. 42 3.7.8 The Application of the MSBAC10 to Acid Rock Drainage (ARD) Solution .............. 43 3.8 Cost Estimation .................................................................................................................. 43 3.9 Quality Assurance and Quality Control ............................................................................. 43 Chapter 4: RESULTS AND DISCUSSION ............................................................................ 45 4.1 Material Characterizations ................................................................................................. 45 4.1.1 The Characterization of Raw Sludge (RS) ................................................................... 45 4.1.2 The Physicochemical Properties of Sludge Based Adsorbents .................................... 48 4.1.3 Dissolved metals in CS, SBAC, MSBACs................................................................... 48 4.1.4 X-Ray Diffractograms for CS and SBAC .................................................................... 50 4.1.5 Surface Functional Groups on Activated Carbons - Fourier Transform Infrared (FTIR) Spectroscopy ................................................................................................................ 53 4.2 Preliminary Batch Sorption Tests on Carbonized Sludge (CS) ......................................... 56 4.2.1 The Sorption Kinetics ................................................................................................... 56 viii  4.2.2 pH Effect ...................................................................................................................... 56 4.3 Lead Sorption Capacities onto CS and SBAC ................................................................... 58 4.3.1 Sorption Kinetics of SBAC .......................................................................................... 58 4.3.2 Concentration effect on Sorption of CS and SBAC ..................................................... 59 4.3.3 A Comparison of CS and SBAC, and their Lead Sorption Capacities ......................... 60 4.4 The Capacity of Lead Sorption onto Modified SBACs ..................................................... 63 4.4.1 Sorption Kinetics for MSBAC0, MSBAC4 and MSBAC 10 ...................................... 63 4.4.1.1 MSBAC0 ......................................................................................................... 63 4.4.1.2 MSBAC4 and MSBAC10 ............................................................................... 64 4.4.2 Sorption Isotherms of MSBAC0, MSBAC4 and MSBAC 10 ..................................... 64 4.4.3 A Comparison of Lead Sorption of MSBACs with CS and SBAC ............................. 66 4.4.4 Leachability Tests for CS, SBAC, MSBACs after Lead Sorption ............................... 70 4.4.5 Repeated Sorption Tests for MSBAC10 ...................................................................... 71 4.5 Modification and Sorption Mechanisms ............................................................................ 73 4.5.1 Modification Mechanism ............................................................................................. 73 4.5.2 The Sorption Mechanisms ............................................................................................ 75 4.6 The Effectiveness of MSBAC10 ....................................................................................... 78 4.6.1 A Comparison of MSBAC10 with Selected Adsorbents ............................................. 78 4.6.2 Applications of MSBAC10 for the ARD ..................................................................... 80 4.7 Cost Estimation .................................................................................................................. 83 Chapter 5: CONCLUSIONS AND RECOMMENDATIONS .............................................. 85 5.1 Conclusions ........................................................................................................................ 85 5.1.1 The Characteristics of Converted and Modified Activated Carbon ............................. 85 ix  5.1.2 Heavy Metal Sorption Characteristics of the Sludge Based-Adsorbents ..................... 86 5.2 Recommendations and Further Experiments ..................................................................... 87 REFERENCES ............................................................................................................................ 88 APPENDICES ............................................................................................................................. 92 Appendix A Detail Experimental Procedures .......................................................................... 92 A.1 Sludge Characterization ..................................................................................................... 93 A.1.1 Sludge Sampling and Preparation ................................................................................ 93 A.1.2 Total Solids and Volatile Solids of Sludge (TS/VS) ................................................... 93 A.1.3 Stability Test for Dissolved Metals and Total Metals by Acid Digestion ................... 94 A.2 Preparation and Characterization of Carbonized Sludge ................................................... 95 A.2.1 Preparation of Carbonized Sludge ............................................................................... 95 A.2.2 Characterization of Carbonized Sludge (CS) ............................................................... 95 A.3 Preparation and Characterization of SBAC ....................................................................... 97 A.3.1 Preparation of SBAC ................................................................................................... 97 A.3.2 Characterization of SBAC ........................................................................................... 98 A.4 Modification of SBAC and Characterization of MSBACs ................................................ 99 A.4.1 Modification of SBAC ................................................................................................. 99 A.4.2 Characterizations of MSBAC0, MSBAC4 and MSBAC10 ...................................... 100 Appendix B Batch Sorption Tests and Methods Supplement ............................................... 101 B.1 Batch Sorption Test of CS ................................................................................................ 102 B.1.1 Sorption Kinetics ........................................................................................................ 102 B.1.2 Metal Sorption Isotherm ............................................................................................ 102 B.2 Batch Sorption Test of SBAC for Lead ........................................................................... 104 B.2.1 Sorption Kinetics ........................................................................................................ 104 x  B.2.2 Metal Sorption Isotherm ............................................................................................ 104 B.3 Batch Sorption Test of MSBACs (MSBAC0, MSBAC4 and MSBAC10)...................... 104 B.3.1 Sorption Kinetics ........................................................................................................ 104 B.3.2 Metal Sorption Isotherm ............................................................................................ 105 B.3.3 Repeated Batch Sorption Test for MSBAC10 ........................................................... 105 B.4 Sorption Tests for Pb2+ with Selected Adsorbents ........................................................... 106 B.5 Cation Exchange Capacity for Different Adsorbents Materials ....................................... 107 B.5.1 Apparatus and Reagents Lists .................................................................................... 107 B.5.2 Procedures .................................................................................................................. 107 B.5.3 Sample Calculations ................................................................................................... 108 Appendix C Experimental Data and Figures ......................................................................... 109 C.1 Material Characterizations ............................................................................................... 110 C.1.1 Total Solids and Volatile Solids of Sludge ................................................................ 110 C.1.2 Total Carbon, Nitrogen and Hydrogen Content of the Materials ............................... 110 C.1.3 Specific Surface Area BET Date and Calculation ..................................................... 111 C.1.4 Cation Exchange Capacity for Adsorbents ................................................................ 112 C.1.5 Total Metal Digestion for Raw Sludge (RS) and Dissolved Metal Concentrations of RS, CS and SBAC ...................................................................................................... 113 C.1.6 X-Ray Diffractograms of CS and SBAC from Semi-quantitative Analysis .............. 115 C.1.7 Surface Function Group for Adsorbents .................................................................... 117 C.1.8 Pourbaix Diagram of Pb2+ .......................................................................................... 120 C.2 Batch Sorption and Leachability Tests Data .................................................................... 121 C.2.1 Preliminary Batch Sorption Tests for Carbonized Sludge (CS)................................. 121 C.2.2 Data of Sorption Kinetics for SBAC, MSBAC0, MSBAC4 and MSBAC10 ............ 123 xi  C.2.3 Data of Sorption Isotherms for CS SBAC, MSBAC0, MSBAC4 and MSBAC10 ... 125 C.2.4 Data for Stability Tests of the Adsorbents after Sorption .......................................... 127 C.2.5 Repeated Single Sorption Tests for MSBAC10 ......................................................... 128 C.2.6 Experimental Data for Comparison of MSBAC10 with Different Adsorbents ......... 129 C.3 Supplementary Lab Data .................................................................................................. 130 C.3.1 Batch Sorption with ARD Solution by MSBAC10.................................................... 130   xii  List of Tables Table 2.1 The Percentage of Trace Elements in Sewage Sludge (or Biosolids) from Annacis Island WWTP Vancouver, Canada (Metro Vancouver, 2005) ...................................... 9 Table 2.2 A Summary of the Literature Review of SBACs Conversion from Sewage Sludge .... 14 Table 2.3 Assignments of Functional Groups on Carbon Surfaces (Shen et al., 2008) ................ 21 Table 3.1 The characteristics of Commercial Adsorbents ............................................................ 28 Table 3.2  A List of Analyzed Metals and the Associated Detection Limits of the ICP-MS Optical Emission Spectrometer Optimal 7300 DV ...................................................... 33 Table 3.3 The Batch Sorption Test Program for CS ..................................................................... 38 Table 3.4 The Batch Sorption Test Program for SBAC ............................................................... 39 Table 3.5 The Experimental Program for Optimizing the SBAC Modification ........................... 39 Table 3.6 Batch Sorption Test Program for MSBAC0, MSBAC4 and MSBAC10 ..................... 40 Table 4.1 The Characteristics of Raw Sludge ............................................................................... 46 Table 4.2 Metal Concentrations of Raw Sludge and Its Leachate ................................................ 47 Table 4.3 Physicochemical Properties of Sludge Based Adsorbents ............................................ 48 Table 4.4 Dissolved Metal Concentration from the Leachate of the CS and SBAC Following 24 Hours in Distilled Water at pH of 3 with 1 g to 40 mL Ratio ...................................... 49 Table 4.5 The Mineral Composition of CS and SBAC from Semi-Quantitative X- Ray Diffraction Analysis ..................................................................................................... 51 Table 4.6 Calculated Parameters of the Pseudo-second-order, Langmuir and Freundlich Models for CS and SBAC ......................................................................................................... 61 Table 4.7 Calculated Equilibrium Concentrations and Pseudo-second-order Rate Constants for Lead .............................................................................................................................. 66 xiii  Table 4.8 Values of the Parameters for the Langmuir and Freundlich Model ............................. 69 Table 4.9 The Adsorptivity Comparisons of Different Adsorbents .............................................. 79 Table 4.10 Metal Concentrations in Untreated ARD and Treated ARD Solution........................ 81 Table 4.11 Labour Hours for Preparing MSBAC10 Based on 10 Batch Tests ............................ 83 Table 4.12 Cost Estimations for the Preparation of MSBAC10 ................................................... 84    xiv  List of Figures  Figure 1.1 An Overview of Sludge Disposal Methods ................................................................... 2 Figure 1.2  Flowchart for the Research Plan ................................................................................... 6 Figure 2.1 A Schematic Representation of the Proposed Structure of Activated Carbon (McDougall, 1991) ....................................................................................................... 10 Figure 2.2 A Simplified Schematic of Some Acidic Surface Groups on Activated Carbon (Shen et al., 2008) ................................................................................................................... 19 Figure 2.3 The Formation of the Acidic Functional Group by Nitric Acid (Shen et al., 2008) ... 19 Figure 2.4 Possible Nitrogen Functional Groups Present in Activated Carbons (Shen et al., 2008) ...................................................................................................................................... 20 Figure 2.5 A Simplified Schematic of Some Basic Surface Groups Bonded to Aromatic Rings on Activated Carbons (Shafeeyan et al., 2010) ................................................................. 20 Figure 2.6 Pictorial Definition of Sorption Process ...................................................................... 23 Figure 2.7 Pictorial Definition of Ion Exchange Process ............................................................. 24 Figure 3.1 An Overall Flowchart for the Preparation and Utilization of Materials ...................... 25 Figure 3.2  A Schematic Diagram of the Experimental Apparatus Used to Prepare CS and SBACs (Not to Scale)................................................................................................... 35 Figure 4.1 Color of Sludge (a) Dry Sludge before Conversion; (b) Carbonized Sludge .............. 46 Figure 4.2 Non-quantitative X-Ray Diffraction Spectra for CS and SBAC ................................. 52 Figure 4.3 The FTIR Spectrum of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 (wavenumbers in the 600 to 4000 cm-1 range) ............................................................. 54 Figure 4.4 The FTIR Spectrum of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 (wavenumbers in the 1000 to 2000 cm-1 range) ........................................................... 55 xv  Figure 4.5 The Sorption Kinetics of CS in 92.5 ppm of Pb2+ Solution at pH = 3, Solid-to-solution Ratio = 1 g: 40 mL, Data in Duplicate ........................................................... 56 Figure 4.6 The Sorption Isotherms of CS for Pb2+in 80 minutes with Solutions of pH =3, 5, 7, and the Solid-to-liquid Ratio = 1 g: 40 mL, Data in Duplicate .................................... 57 Figure 4.7 The Sorption Kinetics of SBAC in 102.5 ppm of Pb2+ Solution at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL, Data in Duplicate ............................................................... 58 Figure 4.8 The Sorption Isotherm of CS for the Pb Solution at pH = 3, Solid-to-solution Ratio = 1g: 40 mL in 80 min and SBAC in 5 min: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity; Data in Duplicate 59 Figure 4.9 Plots of Pseudo-second-order Models for the Sorption Kinetics of CS and SBAC .... 60 Figure 4.10 Linear Models for Pb2+ Sorption onto CS and SBAC: a) The Langmuir Isotherm Model; b). The Freundlich Isotherm Model ................................................................. 62 Figure 4.11 Sorption Kinetics of MSBAC0, MSBAC4 and MSBAC10 with 100 ppm Pb2+ at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL, Date in Duplicate ......................................... 63 Figure 4.12 The Sorption Isotherm of MSBAC0 for Pb2+ at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL in 5 min and Final pH Values: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity;  Date in Duplicate ........... 65 Figure 4.13  The Sorption Isotherm of MSBAC4 lead at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL in 5 min and Final pH Value: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity; Date in Duplicate ................ 65 Figure 4.14 The Sorption Isotherm of MSBAC10 lead at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL in 5 min and Final pH Value: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity; Date in Duplicate ................ 66 xvi  Figure 4.15 Plots of Pseudo-second-order Model for the Sorption Kinetics of MSBAC0, MSBAC4 and MSBAC10 ............................................................................................ 67 Figure 4.16 A Linear Model of the Langmuir Isotherm for Pb2+ Sorption onto MSBAC0, MSBAC4 and MSBAC10, Date in Duplicate .............................................................. 68 Figure 4.17 A Linear Model of the Freundlich Isotherm for Pb2+ Sorption onto MSBAC0, MSBAC4 and MSBAC10, Date in Duplicate .............................................................. 68 Figure 4.18 The Desorption Tests of CS, SBAC, MSBAC0, MSBAC4, MSBAC10 by Distilled Water at pH=3 with 1 g: 40 mL Ratio after Spiked with 1000 ppm Pb2+ Solution, n=2: a) Leached Pb2+ Concentration from Adsorbents in Solution; b) Adsorptivity and Desorptivity of Adsorbents; Data in Duplicate ............................................................ 71 Figure 4.19 Repeated Sorption Tests for MSBAC10 with 102.5 ppm Pb2+ Solid-to liquid Ratio of 1 g to 40 mL at pH =3 in 5 min, Data in Duplicate: a) Remaining Concentration in Solution after Adsorption; b) Accumulated Adsorptivity by MSBAC10; c) Adsorptivity and Solution pH for Each Repeated Test ................................................ 72 Figure 4.20 The Sorption Isotherm of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 for Pb2+ at pH =3; the Sorption Time is 80 mins for CS, and 5 mins for Other Adsorbents; Data in Duplicate .................................................................................................................. 75 Figure 4.21 Comparison of FTIR Spectra for Unused MSBAC10 and Adsorbed MSBAC10 .... 77 Figure 4.22 A Comparison of the Adsorptivity of Different Adsorbents at pH = 3.6, initial conc. = 487 ppm with 1 g: 10 mL solid-to-liquid ratio, n = 2: (a) 24 hours; (b) 5 min; Date in Duplicate ...................................................................................................................... 79 xvii  Figure 4.23 The Adsorptivity Comparison of the MSBAC10 with Lai?s Results, Data in Duplicate (2005) Using Natural ARD (pH 3.28) as Background Solution in 5 Minutes, n=2, (a) for Al, (b) for Fe, (c) for Cu and (d) for Zn .................................................... 82   xviii  List of Abbreviations AAS  Atomic Sorption Spectrometer ARD  Acid Rock Drainage ASTM   American Society for Testing and Materials BC British Columbia BET  Brunauer ? Emmett ? Teller  CAC Commercial Activated Carbon CEC  Cation Exchange Capacity CS Carbonized Sludge FTIR  Fourier Transform Infrared Spectroscopy GVS&DD Greater Vancouver Sewerage and Drainage District ICP-MS Inductively Coupled Plasma ? Mass Spectrometry MSBAC Modified Sewage Sludge Based Activated Carbon SBAC  Sewage Sludge Based Activated Carbon TC  Total Carbon TOC Total Organic Carbon TS Total Solid USEPA  United States Environmental Protection Agency VOC Volatile Organic Compound VS Volatile Solid  WWTP Wastewater Treatment Plant XRD  X-Ray Diffraction    xix  Acknowledgements  I would like to express my sincerest gratitude to ? ? Dr. Loretta Li for your great guidance to develop my critical and logical thinking, patience for my endless questions, and encouragement throughout the course of this project. Thank you for giving the opportunity of doing the research that I want to, and trusting me with all your support. I greatly appreciate your time for reviewing my countless pages of writing when you were traveling and ill at home, and giving me valuable advice on the thesis.  ? Dr. Victor Lo for being the second reader for my thesis, and providing me with professional opinions.  ? Ms. Paula Parkinson, Mr. Timothy Ma, the staff of the UBC Chemical and Biological Engineering Lab for providing me with training and assistance with my lab work. Especially Ms. Paula Parkinson? innovation of using the electrical furnace plays a significant role on my successful experiments. All the practical knowledge I learn from all of you is invaluable.  ? Xiaojie Chen and Cheng Deng for proofreading my writing despite the fact that my boring thesis makes no sense to you.  ? Shugen Liu for helping me with the sampling from the UBC pilot plant and providing the guidance on the preliminary tests.  I would like to thank my girlfriend Yuanyuan Chen for her understanding and taking care of me so that I can focus on my thesis writing. I could not tell you how lucky I am to have you being me side.  xx  I also would like to thank all my friends for giving me all kinds of help both in my thesis and my life. Without your help, I could not finish the degree so quickly.  Special thanks are owed to my parents, who have supported me throughout my UBC education morally and financially, for their incredible encouragement and love.      1  Chapter 1: INTRODUCTION 1.1  Problem Statement Sewage sludge is an unavoidable residual of the wastewater treatment process. The volume of sewage sludge increases as populations grow.  The sewage sludge production in the European Union (EU) has amounted to 11.2 million tonnes of dry solids/year by 2005 (Ma et al., 2006). China produced 11 million metric tons of dewater sludge cake with a 20% solid content in 2005, and with a projected 35 million metric tonnes for 2015 (Ye and Li, 2010). In the United State (US), over 6.2 million metric tons of dry sludge was generated annually by wastewater treatment plants (Kargbo, 2010). As for the Metro Vancouver area, ~17,000 dry tonnes of sewage sludge (30% of total solid) was generated in 2006. The treatment and disposal of sludge usually accounts for 25-65% of the total operating costs of a secondary treatment plant (Wang et al., 2007). In Canada, $12-15 billion was spent on infrastructure related to sewage sludge treatment (Buberoglu and Duguay, 2004). Consequently, the increasing volume, and high cost of sludge handling and disposal are becoming problematic. Conventional disposal methods include landfill, the application to agricultural land, and incineration (See Figure 1.1). However, these methods are unsustainable and have major limitations. The disposal of sludge through landfills is restricted by the availability of suitable landfill sites, in addition to the growing cost of landfill maintenance. The application to agricultural land is regulated by legislation due to the potential risk of leaching hazardous compounds, such as heavy metals and emerging contaminants, from sewage sludge. Incineration is often rejected owing to the potential hazardous ash during the operation process (Smith et al., 2009).  Therefore, a more cost effective and environmentally sustainable alternative is essential for handling sewage sludge.   2    Figure 1.1 An Overview of Sludge Disposal Methods Activated carbon is a term that defines a broad range of amorphous carbonaceous material. Due to its high degree of porosity and large surface area, activated carbon has been widely used for the removal of undesirable odours, colours, taste, and other organic and inorganic pollutants from both domestic and industrial wastewater. Sorption by activated carbon is considered as a ?best broad-spectrum? alternative for removing organic and inorganic contaminants from wastewater (Bansal and Goyal, 2005). Although the major sorption mechanism is dependent on the size of the sorption surface area, surface chemistry also plays an important role in the removal of inorganic contaminants, especially heavy metals. Activated carbon with surface modifications has been considered an effective method to remove heavy metals from wastewater due to their ability to form complexes with different surface functional groups (Yang et al., 2007). Previous studies have shown that the special modification of 3  activated carbons could significantly improve the sorption capacity for specific heavy metals such as mercury (Fang et al., 2010) and copper (Chen et al., 2003). However, the utilization of commercial activated carbons as precursors is costly. An alternative for preparing activated carbons by using waste materials and further modifying them to remove heavy metals from the wastewater could be both economical and sustainable.   The carbonaceous nature of sewage sludge has the potential first recognized by Razouk et al. (1960) of becoming converted to activated carbon. Since then, various researches have been conducted focusing on preparing activated carbons from sewage sludge. Smith et al. (2009) published a review of sludge-based sorbents (SBAs) and their application, reporting that sewage sludge based activated carbons (SBACs) can be employed to remove metal ions, dyes, phenol, and phenolic compounds from water. Other studies have also indicated that SBACs exhibit a good sorption performance for such organic matters as gaseous formaldehyde (Wen et al., 2011), volatile organic compounds (VOCs) (Anfruns et al., 2011), gaseous formaldehyde, Acid Brilliant Scarlet GR a dye material (Wang et al., 2007), and for heavy metals such as Cu2+ (Seredych et al., 2006), Hg0 (Fang et al., 2010) and arsenic (Tavares et al., 2012). Therefore, converting sewage sludge to activated carbons could be a promising alternative to reduce the large volume of sewage sludge and to achieve environmental sustainability by converting waste material to a useful adsorbent.    4  1.2  Research Objectives  The main objectives of this study were to convert sewage sludge into activated carbons and to further modify this sewage sludge based activated carbon (SBAC) to enhance the uptake capacity of heavy metal ions from wastewater. The adsorption effectiveness and the application of modified SBACs (MSBACs) were also investigated. The specific objectives of this research were:  ? To characterize the raw sewage sludge and all the adsorbents made from this sludge in terms of its physical and chemical properties.  ? To convert the sewage sludge to SBAC by a selected chemical reagent based on the literature review and to further modify the SBAC to enhance the metal sorption capacity by adopting the method for modifying commercial activated carbon o To conduct batch sorption tests for the kinetics and sorption isotherm of the concerted activated carbons and modified SBACs. o To determine the stability of the SBAC, and the metal leachability of the SBAC and modified SBACs after the metal sorption. ? To compare the metal sorption capacity of the modified SBACs with that of other commercial adsorbents.  ? To test the sorption capacity of the modified SBACs employing acid rock drainage (ARD) spiked with multiple metals.    5  1.3  Research Plan The research plan and scopes were summarized in Figure 1.2. The experiments were conducted on two levels: as preliminary tests and final tests. The preliminary tests included the verification of the conversion method by testing the equipment and practicing the techniques, and the selection of the parameters for the batch sorption tests. The final tests included the conversion and modification of the SBACs, the batch sorption and desorption tests of the adsorbents, and the application of the modified SBACs.  In the preliminary study, lead ion (Pb2+) was chosen as the target contaminant for the sorption tests.  1.4  Thesis Outline Chapter 1 introduces the problems and objectives of this research. Chapter 2 provides a review of the sewage sludge composition, the mechanisms for preparing and modifying SBACs, and the heavy metal removal mechanism using adsorbents in the solution. Chapter 3 outlines the materials and methods. The experimental results and discussion are presented in Chapter 4, and conclusion and recommendations are included in Chapter 5. 6   Figure 1.2  Flowchart for the Research Plan 7  1.5  Research Contributions and Novelty   This is the first time that sewage sludge based activated carbon (SBAC) has been employed as a precursor for further modification to enhance its metal adsorption capacity. Furthermore, a comprehensive investigation was conducted to study the sorption mechanisms of modified SBACs and their sorption effectiveness by comparing with that of other adsorbents. In addition, the leachability of SBAC after metal sorption has not so far been investigated by previous studies but has been studied in this research.  The results of this study will contribute to the reduction of the large volume of sewage sludge by converting it into useful material in terms of environmental sustainability. The converted material can potentially be applied to remove the heavy metals in wastewater to meet the discharge criteria. In addition, the SBAC can be further modified to enhance the sorption capacity of specific heavy metals. In terms of its economic impact, the cost of the sludge?s conversion and following modification can be compensated by the monetary savings incurred from the sludge disposal costs and also the revenue generated by activated carbon sales.     8  Chapter 2: BACKGROUND AND LITERATURE REVIEW  2.1  Introduction of Sewage Sludge  The main components of sewage sludge are mostly water, organic matter (6.5% to 48%) (Dowdy et al., 1976), silt/sand, and trace elements including: nitrogen, phosphorous and heavy metals. Table 2.1 summaries a typical list of percentages for trace elements found in the sewage sludge from the Annacis Island wastewater treatment plant (WWTP) in Vancouver, British Columbia, Canada. Its consistency, ranging from slurry to dry solids and composition are dependent on the source material (the inputs to the WWTP) and the type of sludge treatment employed.  The term ?sewage sludge? is not the same as the term ?biosolids?. The latter generally refers to the sludge that is further treated by aerobic composting employed for example, to reduce human pathogens. The operating cost of converting raw sludge to biosolids, including the labour, consumption of lime and polymers, power, and maintenance utilized, was estimated to be $105.64 Canadian dollars per dry metric tonne in 2002 (LeBlanc et al., 2004). Hence, the sewage sludge was used in this study instead of biosolids for the activated carbon conversion, thus reducing cost by-passing the ?sludge to biosolids? step.   9  Table 2.1 The Percentage of Trace Elements in the Sewage Sludge (or Biosolids) from Annacis Island WWTP Vancouver, Canada (Metro Vancouver, 2005) Element Percentage (%) Nitrogen 4.32 Iron 3.86 Phosphorous 2.88 Aluminum 1.56 Magnesium 0.54 Copper 0.11 Potassium 0.15 Zinc 0.10 Sodium 0.09 Manganese 0.04 Other Trace Elements Less than 0.03  2.2  Production of Activated Carbon Activated carbon is usually produced by thermal decomposition of carbonaceous material followed by activation with steam or carbon dioxide at an elevated temperature. The process involves two steps: carbonization and activation. 2.2.1 Carbonization Carbonization is performed by heating carbonaceous material to high temperatures usually at around 500-800?C with an inert atmosphere (Smith et al., 2009). During carbonization, most of the non-carbon elements such as oxygen, hydrogen, nitrogen and sulphur, are eliminated, and a fixed carbon mass with a rudimentary pore structure is produced. The residual carbon atoms form aromatic sheets cross-linked in a random manner. The structure of activated carbon as shown in Figure 2.1 is similar to that of graphite. The free interstices between those sheets 10  may be filled or blocked with the internal carbon mass (or tar) from the decomposition, which has developed a less porous structure.   Figure 2.1 A Schematic Representation of the Proposed Structure of Activated Carbon (McDougall, 1991) 2.2.2 Activation The activation process essentially removes the tarry products formed during carbonization to clear the char between the aromatic sheets, and also enhances the formation of the structure with a large number of pores of various shapes and sizes (Bansal and Goyal, 2005). The activation process eliminates disorganized carbon, exposing the aromatic sheets to the activation agents, and contributes toward the formation of a microporous structure. There are two types of activation: physical and chemical. 2.2.2.1 Physical Activation  Physical activation is a two-step process. Carbonization is followed by the activation with the presence of oxidizing gases such as CO2, steam or oxygen to provide a selective oxidation of atoms by controlled gasification. The process is usually carried out at the temperatures between 800 and 1100oC (Bansal et al., 1988). The formation of the porous structure within the activated carbon is achieved by the elimination of a large amount of internal carbon mass (Hsu & Teng, 11  2000). The activation first involves the carbon disorganization by thermally decomposition while the burn-off occurs within a 10% range, resulting in the opening of the blocked pores. After that, the aromatic ring begins to burn, producing active sites and larger pores. The presence of oxidizing gases promotes internal and external oxidation, and the development of larger pores (Bansal et al., 1988).  2.2.2.2 Chemical Activation  Chemical activation is a single step process in which the carbonization and activation steps proceed simultaneously by carbonizing the carbonaceous material that has been previously impregnated with chemical activating reagents (Smith et al., 2009; Bansal et al., 1988). Chemical activation is generally conducted at the temperatures between 400 and 800oC. Phosphoric acid (H3PO4) is commonly used as an activating agent in the activated carbon manufacture industry. Besides that, zinc chloride (ZnCl2), sulphuric acid (H2SO4), sodium hydroxide (NaOH), potassium hydroxide (KOH) and some other chloride salts of magnesium, calcium, ferric and aluminum are also used. These chemicals act as dehydrating agents but have different dehydration strengths with precursor materials. For example, ZnCl2 can release hydrogen and oxygen gas within the material by the formation of water molecules rather than hydrocarbons. Consequently, it increases the percentage yield of activated carbon through retaining more carbons in the carbonaceous material. ZnCl2 also acts as a tar formation suppressant, and producing a carbon skeleton and creating a porous structure (Caturla et al., 1991). Chemical activation which requires less energy (400-800oC versus 800-1100oC) is advantageous to physical activation. This energy conservation is caused by high-porosity carbons being formed during physical activation, and can only be obtained at high extent char burn-offs, 12  which often consumes more energy than chemical activations and results in a lower specific surface area (Smith et al., 2009). Chemical activation is a one-step process, much simpler to operate than physical activation. Safely injecting oxidizing gases during the physical activation is also a concern due to the equipment limitation in the lab. As a result, this study prefers the chemical activation process for preparing activated carbons from sewage sludge. 2.3  The Chemical Activation of Sludge Based Activated Carbons Sewage sludge as a precursor to produce activated carbons was first tested by Razouk et al. (1960). Kemmer et al. (1971) then patented a process for producing activated carbon through the chemical activation of dried sewage sludge. Beeckmans et al. (1971) carried out a study on the production of activated carbon from sewage sludge by carbonization. Subsequent to these studies, a variety of research has been conducted to investigate the feasibility and improvement of the conversion of sludge based activated carbons (SBACs) for sorption of trace metals and organic contaminants.  Regardless of the source of the sewage sludge, the sorption capacity of SBACs is usually evaluated by the number of available sorption sites onto the carbons. Larger specific surface areas possess more sorption sites for sorption onto materials. Therefore, the surface area of the SBACs is an important aspect for investigating the sorption capacity of SBACs and evaluating effectiveness of corresponding activation reagents.  Recent studies on converting sewage sludge to activated carbons by chemical activation were summarized in Table 2.2. The common chemical reagents for activating sewage sludge are zinc chloride (ZnCl2), potassium hydroxide (KOH), phosphoric acid (H3PO4) and sulfuric acid (H2SO4). The SBACs produced through chemical activation were found to be effective on cation uptake. Martin et al. (2002) found that the absorptivity of SBACs for Cd2+, Ni2+, and Cu2+ were 13  in excess of those exhibited by commercial activated carbons.  In addition, Zhang et al. (2005) reported that the SBACs activated by ZnCl2, H2SO4 and H3PO4 were more effective for the removal of mercury (Hg (II)) than the SBACs without chemical activation. Although phosphoric acid is a popular activation reagent in industries involving activated carbon manufacture (McDougall, 1991), it is an inadequate reagent for activating sewage sludge only with the maximum BET (Brunauer-Emmett-Teller) (Brunauer et al., 1938) surface area of 289 m2/g (Zhang et al., 2005). Zhang et al. (2005) also demonstrated that the activated carbon with ZnCl2 had a better sorption capacity for mercury than those of activated carbon activated with H2SO4 and H3PO4. As a result, this study does not consider H2SO4 and H3PO4 to be the preferred reagents for the chemical activation. 14  Table 2.2 A Summary of the Literature Review of SBACs Conversion from Sewage Sludge Sewage Sludge Properties Chemical Activating Agent Sludge to Agent Ratio Heating Rate ?C/min Pyrosis Temperature ?C Holding Time at Pyrosis Temperature (Hour) Surface Area m2/g Sorption Test Reference TS: 6 g/L, VS: 4.2 g/L H2SO4, ZnCl2 with weight ratio 1:1 1 g: 1g Not provided 500 1 257 Not tested Martin et al., 1996 Anaerobically digested sewage sludge 5 M ZnCl2 with Nitrogen Gas 1 g: 2.5mL 10 500 2 650 58 mg/g of Phenol removal Tay et al., 2001 20.5% of TS 5 M ZnCl2   Nitrogen Gas 1 g: 2.5mL 15 500 2 647.4 46.95 mg/g for phenol; 7.73 mg/g for CCl4 Chen et al., 2002 40% of carbon 5 M ZnCl2, 3M H2SO4, 3M H3PO4 1 g: 2.5mL 10 650 1 555, 408, 389 AC with ZnCl2 is the best with 50 mg/g mercury removal Zhang et al., 2005 Biochemical and surplus sludge Mixture of ZnCl2 and H2SO4 1 g: 2.5mL 5 550 2 114 87.5% of chromaticity color removal rate Yu and Zhong, 2006 31.4% - 37.2% of carbon KOH and NaOH 1 g: 1g 5 700 1 1686 Not tested Ros et al., 2006 VSS/TSS: 71.6%, VSS: 11.4 g/L 3M KOH with steam gas 1 g: 2.5mL 40 600 1 381.62 14.73 mg/g of Acid Brilliant Scarlet GR removal Wang et al., 2007    15  Table 2.2 A Summary of the Literature Review on Converting SBACs (Continued) Sewage Sludge Properties Chemical Activating Agent Sludge to Agent Ratio Heating Rate ?C/min Pyrosis Temperature ?C Holding Time at Pyrosis Temperature (Hour) Surface Area m2/g Sorption Test Reference Biological sludge KOH 1 g: 1 g 5 700 1 1882 N/A Lillo-Rodenas et al., 2008 C: 37.35%, N: 2.9%, H: 5.84%, S: 1.32%, 3.1 M ZnCl2 1 g: 1 mL 10 500 1 375 10.84 mg/g of Pb2+ removal Jiang et al., 2010 Dewatered sewage sludge 6 M ZnCl2 1 g: 1 mL 10 750 2 509.88 74.27 mg/g of gaseous formaldehyde removal Wen et al., 2011 Aerobic granular sludge (48.7 % of carbon) KOH 1 g: 1 g; 1 g: 3 g Not provided 750 0.5 1832 330 mg/g of 4-chlorophenol Monsalvo et al., 2011  16  2.3.1 Potassium Hydroxide (KOH) The KOH is an effective activation reagent since it results in a high BET surface area of 1882 m2/g for SBACs with a maximum temperature of 700?C being held for 30 minutes and a heating rate of 15?C /min (Lillo-Rodenas et al., 2008). Sewage sludge was converted through a two-stage method: the carbonisation of the material followed by its activation using KOH.  A high BET surface area of 1686m2/g was also obtained by Ros, et al. (2006), who employed KOH for chemical activation using a slow heating rate of 5?C/min until 700?C with a one-hour holding time at the maximum temperature. Both studies employed biologically treated sludge and inert atmospheres provided by nitrogen gas. KOH was also used as a chemical reagent but was combined with steam gas instead of N2 gas in order to provide oxidant reaction during activation (Wang et al., 2007), but a low BET surface area of 381.62 m2/g was attained, which might be due to lack of carbonization prior to the sludge being impregnated with the KOH solution. The benefits of this two-stage method are obtained when the pores are formed during the carbonization step, which provides better pore development during activation (Hu and Vansant, 1995). Furthermore, base reagent such as KOH or NaOH can react directly with carbon atoms (Hsu and Teng, 2000) and the dehydration that occurs during carbonization may allow the carbon atoms to be more accessible to the impregnated KOH (Smith et al., 2009), unlike that which occurs with acidic reagents (e.g. ZnCl2, H2SO4 and H3PO4) that generate pores by reacting with the oxygen functional groups on the carbons. Although sewage sludge activated by KOH can generate high BET surface area activated carbons, this requires high temperature up to 700oC and the occurrence of carbonization prior to the activation. Based on these considerations, KOH was not first choice of a chemical reagent for activation in this study. 17  2.3.2 Zinc Chloride (ZnCl2) The feasibility of converting sewage sludge into activated carbons employing ZnCl2 and H2SO4 has been investigated by Martin et al. (1996). When utilizing ZnCl2 alone, the activated carbons exhibited only14% yield of carbon and a low specific surface area of 57 m2/g. The relative heating time of 0.5 hour at a maximum temperature of 500?C may not provide sufficient time for the pores to be formed. Yu and Zhong (2006) found that a mixture of ZnCl2 and H2SO4 could produce higher BET surface area than using either ZnCl2 or H2SO4 alone, and that ideal ratio was 2:1 (ZnCl2 vs. H2SO4). Nevertheless, the highest BET surface area was only 144.5 m2/g, which might be due to the nature of the biochemical sludge and surplus sludge possessing a low percentage of fixed carbons (15.1 to 17.0%) and a slow heating rate of 5?C during conversion. Chen et al. (2002) reported that SBACs with ZnCl2 activation had a high BET surface area of 647.4 m2/g with 15?C /min heating rate and 2 hours at a maximum temperature of 500?C, leading to better activated carbon properties comparing with the results obtained by Martin et al. (1996) and Yu and Zhong (2006). Tay et al. (2001) investigated the optimising preparation conditions of activated carbon using ZnCl2 as their chemical reagent. The heating rate, maximum conversion temperature, holding time at the maximum temperature and impregnated ZnCl2 concentrations were all investigated in terms of the surface area of the activated carbon. The maximum surface area of 650 m2/g was attained with the optimum conditions of a 10?C/min heating rate, 2 hour dwelling time at 500?C with 5 M of ZnCl2 at a ratio of 2.5 mL to1 gram of dry sludge. Chemical activation with ZnCl2 generally requires a lower temperature and its optimum activation conditions have already been studied by Tay et al. (2001) who provided it with more comprehensive background than that of KOH. Therefore, ZnCl2 was deemed preferable than KOH as the chemical activating agent of choice for this research.  18  2.4  The Modification of Activated Carbons Although a large BET surface area is an important factor for activated carbon possessing a high pollutant uptake capacity, if the activated carbon?s internal and external surfaces do not have affinity for the targeted contaminants, the contaminants will not be removed (Smith et al., 2009). Therefore, the surface chemistry of the activated carbons can play a more important role than high porosity (~ high specific surface area). Activated carbons are generally non-polar adsorbents. They adsorb organic chemicals prior to polar inorganic species. The sorption mechanisms for organic compounds are generally the balance between hydrogen-bonding forces in solution and Van der Waals forces between the activated carbon and organic compounds. In order to adsorb inorganic compounds, which in this study are mainly heavy metals, surface modification of the activated carbon is required to improve the polarity of the activated carbon.  The main adsorbing surface or the edges of activated carbon are incorporated with such surface groups as carbon-oxygen, carbon-hydrogen, carbon-nitrogen, carbon-sulfur, and carbon-halogen compounds (Bansal and Goyal, 2005).   Carbon-oxygen surface groups are the major compounds that affect such surface characteristics as the wettability, polarity and acidity of the activated carbon. There are three types of carbon-oxygen surface groups, acidic, basic, and neutral, and the concentration of each group can be increased or decreased using different post-activation treatments such as oxidation, or ammonization (Shen et al., 2008).   The acidic surface groups are formed when carbons react with oxygen, air, carbon dioxide or steam at temperatures of up to 400?C or with such aqueous oxidants as nitric acid, sulfuric acid or phosphoric acid at room temperature.  During these processes, low temperature oxidations tend to form such strong acidic groups as carboxylics, while high temperature 19  oxidations can produce weak acid groups such as phenol (Shafeeyan et al., 2010). Acidic surface groups improve the hydrophilic properties and polarity of the carbon surface; some common acidic groups are illustrated in Figure 2.2. Chen et al (2003) modified the activated carbon by reacting it with 1 M citric acid. The sorption capacity of copper ion was significantly improved from 6.14 mg of Cu/g of adsorbents to 14.92 mg/g. Song et al. (2010) studied the effect of liquid phase oxidation on the Pb2+ sorption capacities of the activated carbon modified by nitric acid (HNO3) (the possible reactions during the modification are shown in Figure 2.3), and stated that the sorption capacity of activated carbon oxidized with HNO3 was increased significantly compared with that of the original activated carbon.   Figure 2.2 A Simplified Schematic of Some Acidic Surface Groups on Activated Carbon (Shen et al., 2008)  Figure 2.3 The Formation of the Acidic Functional Group by Nitric Acid (Shen et al., 2008) 20  The basic groups usually involve attraction protons that include nitrogen containing groups (shown in Figure 2.4), and certain oxygen containing surface groups such as chromene, ketone, and pyrone (shown in Figure 2.5). The nitrogen containing groups can be obtained through ammonia treatment (Shafeeyan et al., 2010). The oxygen containing surface functionalities are formed by heat treatment in vacuum or in an inert atmosphere at 1000 ?C, and contact with oxygen gas after cooling it to room temperature (Bansal and Goyal, 2005).  Figure 2.4 Possible Nitrogen Functional Groups Present in Activated Carbons (Shen et al., 2008)  Figure 2.5 A Simplified Schematic of Some Basic Surface Groups Bonded to Aromatic Rings on Activated Carbons (Shafeeyan et al., 2010) The neutral surface groups are mainly oxygen groups formed by the chemisorption of oxygen at ethylene type unsaturated sites present on the carbon surface (Bansal and Goyal, 2005).   21  Table 2.3 summarizes the major functional groups of activated carbon based on the assigned wavenumbers from the Fourier transform infrared spectroscopy (FTIR) analysis.  Table 2.3 Assignments of Functional Groups on Carbon Surfaces (Shen et al., 2008) Functional Groups Assignment Regions (cm-1) Functional Groups Assignment Regions (cm-1) C-O in ethers (Stretching)  1000 - 1300 C=N  1480-1660 Alcohols 1049-1276, 3200-3640 Cyclic amides 646,1461.1546, 1685 -C-OH (stretching)  1000-1220 C-N 1190 O-H 1160-1200, 2500-3620 C=C=N 2070-2040 Carboxylic acid 1120-1200, 1665-1760, 2500-3300 N-O- 1300-1000 Carboxylic anhydride  980-1300,1740-1880   1500-1600 Lactones 1160-1370, 675-1790   Carboxyl (R-COO-)  1560 - 1650   C-H (stretching) 2600-3000     22  2.5  The Stability of SBACs A major concern with SBACs is the possible leaching of trace metals (see Table 2.1) during the application of the SBACs to wastewater. Therefore, it is necessary to discover whether the SBACs will contaminate the wastewater through the leaching of their own inorganic elements. A study conducted by Chen et al. (2002) addressed this heavy metal leaching problem of SBACs. The amount of Cr, Cd, Cu, Zn, Pb and Ni released was measured, and the levels of the leached metals except Zn were found to be within the reasonable ranges of the most industrial effluent treatment applications. The high level of the zinc leached from the SBACs was due to the inadequate washing of the ZnCl2 after conversion. The leaching tests were conducted in a solution of pH 4.  In the study of Fitzmorris et al. (2006), the leachability of SBACs activated by steam was tested through the different inorganic components of As, Cd, Cr, Cu, Ni, Pb, Se and Zn in aqueous solutions with of different pHs (1, 5, 7). At pH = 1, all metals were leached out, with the Cu (1.6 mg/g) and Zn (1.8mg/g) being detected at the highest quantities. At the higher pH of 5, only Zn (0.3 mg/g) was leached into the solution, alone with trace amounts of Ni and Cu being leached out together. When the solution was maintained at the neutral pH of 7, only Zn (0.2 mg/g) was leached out. The results of this experiment suggest that it is necessary to control the pH of the wastewater if the SBACs are being applied to treat it.    23  2.6  Heavy Metals and SBACs Interactions Since the main concern of this study is to examine aqueous inorganic pollutants and particularly heavy metals, it is necessary to have some insight into the interaction between heavy metals and SBACs. Three major mechanisms are utilized to remove heavy metals from aqueous solutions: sorption, ion exchange and precipitation. The effectiveness of these mechanisms is strongly influenced by the solution pH  2.6.1 Sorption  Sorption is the phenomenon by which a foreign species is fixed to the surface of a solid (see Figure 2.6). There are two types of sorption based on the different forces involved in the sorption process: physical and chemical sorption. The forces involved in physical sorption are van der Waals, ion-dipole, and hydrogen bonding; these processes are generally reversible. Chemical sorption involves stronger forces in ionic or covalent bonds, which make the process are irreversible (Fyfe, 1964).   Figure 2.6 Pictorial Definition of Sorption Process   24  2.6.2 Ion Exchange  Ion exchange, which is one of the common sorption mechanisms involving physical sorption, refers to the reversible stoichiometric process of the exchange of ions between two different phases in contact; it occurs more commonly between the solid and liquid phases (see Figure 2.7). The exchange reaction between two ions can be expressed as (Orlov, 1992):  Solid ? (M1n+) m + nM2m+ ? Solid ? (M2m+) n + mM1n+                                    [2.1]  This expression demonstrates that the metal ions in the solution are exchanged with the ions in the solids (or activated carbons) for an equivalent quantity of cations. Figure 2.7 Pictorial Definition of Ion Exchange Process 2.6.3 Precipitation  Precipitation is controlled by the solubility of the elements in a solution. Most heavy metals such as Al3+, Cu2+, Zn2+, Cd2+, Pb2+, and Fe2+, are expected to precipitate as hydroxides due to the hydrolysis reaction in the solution which is expressed as: H ? OH + Mn+ ? H ? O ? M (n ? 1) + + H+                                                      [2.2] According to this reaction, the pH (concentration of H+) dominates the direction of the reaction, which indicates that metal precipitation is sensitive to the pH of the solution.   25  Chapter 3: MATERIALS AND METHODOLOGIES 3.1  Introduction This chapter describes the materials, experimental equipment, procedures, and analyses used for this research. Figure 3.1 provides an overall flowchart of the materials preparation and application of in this study, including carbonized sludge (CS), sludge based activated carbon (SBAC) and modified SBACs (MSBAC0, MSBAC4 and MSBAC10). The information of these adsorbents was provided in section 3.2. All adsorbents were tested for the sorption of lead ions (Pb2+), and detailed experimental program were summarized in section 3.3 to 3.7.   Figure 3.1 An Overall Flowchart for the Preparation and Utilization of Materials 26  3.2  Material Origins and Descriptions  3.2.1 Raw Sludge (RS)  The raw sludge used was taken from the aerobic zone of the bioreactors of the Wastewater Treatment Pilot Plant at the University of British Columbia (UBC).  80 L of raw sludge was collected in three trips between May 8 and 10, 2011, with total 240 L. The pH of the sludge was measured and recorded at the sampling site. All of the sludge was collected in plastic containers, immediately transported by vehicle to the UBC environmental lab, and stored at 4?C. Raw sludge was dewatered at the same day by centrifuging with 3000 rpm for 3 minutes, and dried in a 105?C oven for 48 hours. The dry sludge were then mixed thoroughly and ground into powders by an electrical blender to ensure the uniformity, and stored in an amber glass bottle for further conversion. A full description of the sampling and preparation were included in Appendix 1.1.  3.2.2 Adsorbents Converted from Raw Sludge The dry sludge was converted into two different materials: carbonized sludge (CS) and sludge based activated carbons (SBACs). The SBACs were then further modified to three different SBACs: MSBAC0, MSBAC4 and MSBAC10 (see Figure 3.1). The experimental procedures of converting RS into CS and SBAC were included in section 3.5, and section 3.6 for modification of SBACs.  Carbonized Sludge (CS): the CS was prepared by pyrolysis of the dry sludge without any chemical pre-treatment at 10?C/min up to 500?C and then held at this temperature for two hours.  Sludge Based Activated Carbon (SBAC): the SBAC was prepared by using the same experimental conditions for the preparation of the CS, but the dried sludge was soaked in ZnCl2 solution before carbonization.   27  Modified SBACs: the SBAC was employed as a precursor for the modification by being immersed in a 10 M nitric acid (HNO3) solution. The reaction temperature and employed nitric acid dosage were studied to find out the optimal modification condition in terms of highest metal sorption capacity. Three different modified activated carbons: MSBAC0, MSBAC4 and MSBAC10 were prepared, and the preparation conditions were described in section 3.6.  3.2.3 Other Adsorbents  The characteristics of other adsorbents: kaolinite, grundite, perlite, zeolite and commercial activated carbon used for metal sorption tests were summarized in Table 3.1.   3.2.4 Collected Contaminated Solution Acid rock drainage (ARD): 40 liters of ARD was collected from a commercial wastewater treatment plant at the Britannia Mine Site located to the north of Vancouver on March 15, 2013. The ARD was then transported on the same day by vehicle to the UBC environmental lab and stored in a cold storage room with 4?C. The ARD solution was spiked to the same metal concentrations used in Lai?s research (2005), which employed the same source for its ARD solution but used clinoptilolite as the adsorbent. Details of this batch sorption tests were reported in the section 3.7.7.     28  Table 3.1 The characteristics of Commercial Adsorbents Adsorbents Origins Mineral Compositions1 Particle Size2 (mm) pH Surface Area (m2/g) CEC (cmol/kg) Kaolinite A soil mineral from the Georgia Kaolin Company of Elizabeth, N.J. Kaolinite dominated < 1 4.5 12 8 Grundite An illite dominated soil from the Illinois Clay products Company, Joliet, Ill. Mostly illite, traces of chlorite, quartz, and feldspar < 1 3.9 197 55 Perlite Obtained from Perlite Canada, Inc. 74% of silice, 12- 15% of Al2O < 1 3.9 N/A N/A Zeolite A soil mineral with a sieve structure called Bear River Zeolite from the United States Antimony Corporation was used. This zeolite is mined in southern Idaho 85% Clinoptilolite; balance opaline  silica < 1 5 26.5 72.98 Commercial Activated carbon (CAC) A commercial product named Nuchar Granular Activated Carbons, which is a wood-based activated carbon. Mostly Carbon 0.8-1.1 1 86.1 1.51 Note: 1 Provided by the suppler                 2 Sieved by the author   29   3.3  Physical and Chemical Characterizations All physical and chemical characterizations were performed at the University of British Columbia (UBC) Vancouver, BC. The Civil Environmental Engineering Laboratory provided analytical services for the metals. The Chemical and Biological Engineering Laboratory provided the analytical equipment and training for measuring the specific surface area. The Chemistry Lab provided the equipment and training for the Fourier Transform Infrared Spectroscopy (FTIR) analysis. Also, the X-Ray Crystallography Facility in the Department of Chemistry provided the X-Ray diffraction analysis. Determination of the pHs, total solids (TS), volatile solids (VS), metal concentrations, specific surface areas, cation exchange capacity (CEC) and surface functional groups were performed by the author.  3.3.1 Physical Properties  Total Solid (TS) and Volatile Solid (VS) The total and volatile solids of the raw sludge were determined according to the standard methods 2540B and 2540E described in APHA et al., (2005). A total of four replicated were prepared to calculate the sludge?s TS and VS. The full descriptions are included in Appendix A.1.2.  Specific Surface Area  The specific surface areas of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 were determined using the BET (Brunauer-Emmett -Teller) nitrogen sorption method. The full method descriptions are included in Appendix A.2.2.4.    30  Yield Percentage  The percentage yield of the CS and SBAC from dry sludge were measured based on the weight difference between the sludge before and after conversion. Full descriptions of this method are outlined in Appendices A.2.2.1 for CS and A.3.2.1 for SBAC.   3.3.2 Chemical Properties  pH The pH of the raw sludge was measured at the sampling site using a portable Oakton pH meter. The pHs of the acid rock drainage was measured in the laboratory using a calibrated Beckman ? 44 pH meter.   The pHs of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 were measured by mixing them with 0.01 M calcium chloride (CaCl2) based on a method adapted from USEPA method 9045D. See Appendix A.2.2.2 for full descriptions of the method. Elemental Analysis for C, H and N  The total carbon, hydrogen and nitrogen present in the RS, CS, SBAC and MSBACs were analysed by Department of Chemistry. 5 mg of each grinded sample was combusted by Carlo Erba elemental analyzer EA 1108 with 0.3% accuracy.   Cation Exchange Capacity  The cation exchange capacities of all the used material were determined using the ammonium acetate (NH4AOc) method 84-005 adapted from Agriculture Canada Analytical Methods Manuals (1984). The concentrations of extractable Ca2+, Mg2+, K+, and Na+ were determined by the inductively coupled plasma-mass spectrometry (ICP-MS), Optical Emission Spectrometer Optimal 7300 DV manufactured by PerkinElmer. See Appendix B.5 for a full description of the method.  31  Total Metal Digestion The raw sludge was fully digested in a 50 mL flask on a hot-plate with HNO3, as described in Method 3030E (APHA et al., 2005). Samples were concentrated by evaporation (~ten minutes) during the digestion process. Digested and concentrated samples were diluted with 50 mL of distilled and filtered through 0.45 ?m filtering paper. The filtrate was stored at 4?C for further analysis. The analyzed metal concentrations (see Table 3.2) were measured by ICP-MS, and were reported as milligrams of metal elements per gram of the sludge. Full descriptions were provided in Appendix A.1.3. Surface Functional Groups  The surface function groups of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 were measured at room temperature using Fourier Transform Infrared Spectroscopy (FTIR) PerkinElmer Spectrum 100 FT-IR Spectrometer provided by Chemistry Lab (Vancouver, BC).  3.3.3 The Mineralogical Characteristics of CS and SBAC  Preliminary X-Ray diffraction (XRD) analysis was conducted to identify the presence of carbon minerals in CS and SBAC. Semi-quantitative XRD analysis was also performed to ascertain the approximate percentage of the mineral compositions in CS and SBAC.   The preliminary XRD analysis was conducted over a range of 5-75? 2? with CuK? radiation by using powder X-ray diffractometers (the Bruker D8 Discover equipped with a GADDS detector).   The semi-quantitative XRD analyzed were performed by the Department of Earth, Ocean and Atmospheric Sciences. 5 grams of each material (CS and SBAC) were reduced to the optimum grain-size range (<10 ?m) by grinding it in ethanol for seven minutes in a vibratory McCrone Micronising Mill. Continuous-scan X-ray powder-diffraction data were collected over 32  a range 3-80? 2? with CoKa radiation on a Bruker D8 Focus Bragg-Brentano diffractometer equipped with an Fe monochromator foil, 0.6 mm (0.3?) divergence slit, incident- and diffracted-beam Soller slits and a LynxEye detector. The long fine-focus Co X-ray tube was operated at 35 kV and 40 mA, using a take-off angle of 6?. The X-ray diffractogram was analyzed using the International Centre for Diffraction Database PDF-4 and Search-Match software by Bruker. X-ray powder-diffraction data of the samples were refined with the Rietveld program Topas 4.2 (Bruker AXS). 3.4  Chemical Solutions The employed activation reagent zinc chloride (ZnCl2) was bought from Fisher Scientific (technical grade). For sorption tests, the solutions with various lead concentration were prepared by dissolving solid crystal of Pb (NO3)2 from Fisher Scientific (ACS Reagent Grade) into distilled water. The pH of the solution was adjusted to 3.0, 5.0 and 7.0 by nitric acid (HNO3). The HNO3 used for the modification of the SBACs was purchased from Fisherbrand? (ACS Certified Grade). The spiked concentration of lead is described in section 3.7 for individual sorption tests. All Pb2+ in the solutions from sorption tests were analyzed by the Thermo Jarrel Ash Video 22 Atomic Sorption Spectrometer (AAS). The standard solutions used for the AAS tests were prepared from the 1000 ppm lead nitrite certified standard stock solution from SPEX CertiPrep.  Metals of environmental concern (listed in Table 3.2) in the ARD as well as leachate solutions from RS, CS and SBAC were measured by ICP-MS.  Calibration standards were made up in the same background matrix as the samples were analyzed to minimize any discrepancies caused by matrix interference.   33  Table 3.2 A List of Analyzed Metals and the Associated Detection Limits of the ICP-MS Optical Emission Spectrometer Optimal 7300 DV Metal Detection Limit (mg/L) Aluminum (Al) 0.015 Arsenic (As) 0.01 Cadmium (Cd) 0.001 Chromium (Cr) 0.001 Copper (Cu) 0.01 Iron (Fe) 0.01 Lead (Pb) 0.02 Manganese (Mn) 0.001 Nickel (Ni) 0.005 Zinc (Zn) 0.02    34  3.5  The Preparation of Carbonized Sludge (CS) and Sludge Based Activated Carbon (SBAC) 3.5.1 Experimental Apparatus  The CS and SBACs were prepared with the same experimental set-up shown in Figure 3.2. The employed electric furnace was a part of the combustion analyzer TEKMAR DOHRMANN Apollo 9000 manufactured by Folio Instrument Inc. The combustion tube was made of Pyrex glass (cheaper than quartz) since the maximum experimental temperature was 500?C, while the melting point for the employed Pyrex glass was 550?C. The upper portion of the tube has a length of 240 mm with an inner diameter of 19 mm and a thickness of 1.5 mm. The lower part has a length of 110 mm with an inner diameter of 9 mm and a 1 mm thickness. The raw sludge, or the raw sludge treated with ZnCl2, was placed inside the tube with the injection of N2 gas from the bottom of the tube. The electric furnace was used to heat up the material inside the tube. The generated gas and steam during the pyrolysis were collected at the end of the outlet by an amber glass sealed with a rubber cap. The test conditions for preparing the CS and SBACs were adopted from the method used by Tay, et al (2001). They studied the parameters of preparing activated carbon from sewage sludge, and optimized the preparation processes including the concentration of ZnCl2 (5 M), maximum heating temperature (500?C), dwelling time (2 hours) and heating rate (10?C/min).  35    Figure 3.2  A Schematic Diagram of the Experimental Apparatus Used to Prepare CS and SBACs (Not to Scale) 36  3.5.2 The Conversion of Sewage Sludge to Carbonized Sludge (CS) Approximately 10 g of dried sludge powder was used for each conversion. The furnace tube was cleaned by using distilled water and dried in an oven at 105?C. After that, quartz wool was placed to the bottom of the tube (smaller diameter) to block the sample while allow the nitrogen gas to go through during the conversion. The dried sludge was then poured into the tube with the injection of N2 gas from the bottom for at least 10 minutes at 10 mL/min to ensure an inert atmosphere inside the tube.  The furnace temperature was then first set at 100?C. After reaching 100?C, the temperature was further increased manually to 500?C with the rate of 10?C/min, and maintained at 500?C for two hours. After the sample was cooled to room temperature, it was ground into 250 ?m powders and stored in a capped amber glass for further batch sorption tests. The CS from each conversion was stored in the same bottle and homogenized by mixing before sorption tests. 3.5.3  The Conversion of Sewage Sludge into Sludge Based Activated Carbon (SBAC)  The dried sludge powder was soaked with 5M ZnCl2 at a 1 g to 1 mL solid-to-liquid ratio for 24 hours, followed by drying it in an oven at 105?C for another 24 hours before carbonization.  The carbonization procedure was the same as the procedures in section 3.5.2. After carbonization, SBAC was washed three times with 5 M HCl for with a ratio of 1 g: 2 mL and six times with distilled water at 1 g: 20 mL. After each washing, the solution was filtered through a 0.45 ?m filter paper, and all the filtrates were collected for measuring Zn2+ concentration. The washed SBAC was then dried in an oven at 105?C and stored in a capped amber glass bottle. The full descriptions were reported in Appendix A.3.1 37  3.6  Modification of SBAC  The SBAC is further modified in an attempt to enhance the metal sorption capacity (see Figure 3.1 and section 3.7.2, Table 3.5). 10 M nitric acid (HNO3) was used as a modification agent. This method was adapted from Song, et al. (2010) who used the same method to modify a commercial activated carbon to enhance its metal sorption capacity. The modification conditions for different MSBACs are summarized as follows:   ? MSBAC0: SBAC impregnated with 10M HNO3 (1 g to 4 mL) at 20?C for 4 hours ? MSBAC4: SBAC impregnated with 10M HNO3 (1 g to 4 mL) at 90?C for 4 hours ? MSBAC10: SBAC impregnated with 10M HNO3 (1 g to 10 mL) at 90?C for 4 hours An electric water bath was used to provide a constant temperature during the four-hour modification. See Appendix A.4.1 for the full method descriptions.  3.7   Batch Sorption and Desorption Tests  3.7.1 Stability Tests for Dissolved Metals  The stability tests were conducted to investigate the metal leaching of the adsorbents. Since MSBAC0, MSBAC4, and MSBAC10 were originated from SBAC without adding any metal elements, only the CS and SBAC were tested. The CS and SBAC were mixed with distilled water at pH 3 for 24 hours in a ratio of 1 g to 40 mL. The results from the leachate solution were reported as milligrams of metal per liter of distilled water. Appendix A.2.2.3 and A.3.2.3 provide the full descriptions of the method.   38  3.7.2 The Batch Sorption Test Programs The batch sorption tests were performed at room temperature to investigate the lead ion sorption isotherms of the CS, SBAC and MSBACs. In order to ascertain the adsorptivity and sorption efficiency, different sorption test programs were developed. The sorption capacity of CS for Pb2+ was first studied as a preliminary test to determine the sorption conditions and solution pH for the sorption tests of following materials (SBAC, MSBAC0, MSBAC4 and MSBAC10) (see Table 3.3). Three different pHs, 3, 5, 7, were applied to the lead solutions to study the pH effects on the sorption. The pH effect was studied only for the CS. The pH value that resulted the weakest adsorptivity was selected for the following batch sorption tests for the SBAC and MSBACs. The solid-to-liquid ratio of 1 g to 40 mL was used for all the sorption tests except the comparison with commercial adsorbents (1 g to 10 mL). The full descriptions of the method are reported in Appendix B.1.  Based on the preliminary tests outlined in Table 3.3, pH 3 was selected for sorption kinetics and isotherm tests as given in Tables 3.4 and 3.6. The sorption kinetics and isotherm tests for the SBAC were shown in Table 3.5. The full descriptions of the procedures are reported in Appendix B.2.  Table 3.3 The Batch Sorption Test Program for CS Objectives Material Time (min) pH Conc. (ppm) Solid-to-liquid Ratio (g : mL) Sorption Kinetics Carbonized Sludge 5, 10, 20, 40, 80, 160,720, 1440 3 95 1: 40 pH effect Carbonized Sludge 80 3,5,7 100 1: 40 Conc. Effect Carbonized Sludge 80 3 5, 10, 20, 50, 100 1: 40  39  Table 3.4 The Batch Sorption Test Program for SBAC Objectives Material Time (min) pH Conc. (ppm) Solid-to-liquid Ratio (g : mL) Sorption Kinetic SBAC (ZnCl2-AC) 5, 10, 360, 720, and 1440 3 100 1: 40 Conc. Effect SBAC (ZnCl2-AC) 5 3 100, 200,500,800, 1000 1: 40  Tables 3.5 and 3.6 summarize the experimental program for the modified SBAC (MSBAC). Different modification temperatures and acid soaking ratios were investigated to discover the optimum modification results in terms of lead adsorptivity.  The sorption kinetics and isotherms were plotted for MSBAC0, MSBAC4 and MSBAC10. The full descriptions of the procedures are reported in Appendix B.3 Table 3.5 The Experimental Program for Optimizing the SBAC Modification Objectives Material Modification Temperature (?C) Soaking Ratio with HNO3 (g: mL) Drying Temperature (?C) Temperature Effect SBAC (ZnCl2-AC) 20 1: 4 105 90 1: 4 Dosage Effect SBAC (ZnCl2-AC) 90 1: 4 105 90 1: 10      40  Table 3.6 Batch Sorption Test Program for MSBAC0, MSBAC4 and MSBAC10 Objectives Material Time (mins) pH Conc. (ppm) Solid-to-liquid Ratio (g: mL) Sorption Kinetic MSBAC0, MSBAC4 and MSBAC10 1,5,720,1440 3 100 1: 40  Conc. Effect MSBAC0, MSBAC4 and MSBAC10 5 3 100,200,500,800, 1000 1: 40  3.7.3 The Leachability of Adsorbents after Metal Sorption Batch desorption tests were conducted for used CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 to study the metal leachability of the material. After contacting them with 1000 ppm lead solutions for 5 minutes, the adsorbents were collected and dried for 24 hours in a 105?C oven. The dried adsorbents were mixed with distilled water at pH 3 at a 1 g to 40 mL solid-to-liquid ratio and placed in an end-to-end rotator for 24 hours. After filtering through a 45 ?m filter, the filtrate was measured by AAS for dissolved metals. The precision and accuracy of the method was determined by performing duplicate samples.  3.7.4 Adsorptivity Calculation and Curve Plotting  The heavy metal sorption concentration for the different adsorbents was calculated using the following equation:                (      )                                                          [3.1] Where q is the heavy metal adsorptivity (mg g-1), Ci is the initial concentration of the solution (mg L-1), Cf  is the equilibrated (final) concentration (mg L-1), V is the volume of the solution (L), and M is the mass of the adsorbent (g). The sorption isotherms were constructed by plotting q (mg/g) versus the equilibrated concentration Cf. 41  3.7.5 Kinetics and Sorption Isotherm Models  Sorption Kinetics Models  The sorption kinetics was evaluated by the pseudo-second order sorption kinetic model that was expressed as the following differential equation:          (      )                                                    [3.2] Where: k is the rate constant of the pseudo-second order sorption (g/mg min),  qc is the amount of adsorbed metal at equilibrium (mg/g) qt is amount of adsorbed metal on the surface of the sorbent at any time t (mg/g) By integrating the equation above for the boundary conditions t = 0 to t = t and qt = 0 to qt = qt and after its being rearranged to obtain:                                                                             [3.3] the constant k was determined by plotting t/qt against t.   Sorption Isotherm Models The Langmuir and Freundlich sorption models were employed to study the sorption isotherms of the activated carbons in this research. These two isotherms are mathematically expresses as the:  Langmuir Isotherm:                                                                [3.4] Freundlich Isotherm:          ?                                               [3.5] The linearized form of the Langmuir equation after rearrangement is                                                                                 [3.6] 42  While the linearized form of the Freundlich is represented as:                                                                            [3.7] Where     (mg g-1) is the adsorptivity of the material (amount of adsorbed Pb2+ / amount of consumed material).     (mg g-1) is the monolayer sorption capacity of the material.    (L mg-1) is the Langmuir constant related to the free energy of sorption.  Ce (mg ml-1) is the equilibrium concentration of the adsorbates. KF (mg g-1 (L g-1) 1/n) is the Freundlich constant related to the sorption capacity  1/n is the Freundlich constant related to the intensity (Song et al., 2010).  3.7.6 Repeated Batch Sorption Tests  The repeated batch sorption test was only conducted for the adsorbent possessing the highest sorption capacity among the CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 to investigate the reusability of the adsorbents. 1 gram of the adsorbent was contacted 10 times with 100 ppm Pb2+ solution at a pH of 3. The 1 g to 40 mL ratio was the same for all ten sorption tests. The sorption time was chosen based on the corresponding kinetics results of the selected MSBACs. A detail description of the method was summarized in the Appendix.B.3.3. 3.7.7 Batch Sorption Test for Different Adsorbents In order to have a better sense of the adsorptivity of the MSBAC10 in relation to other adsorbents, different adsorbents are selected and listed in the Table 3.1. Two sorption durations of five minutes and 24 hours were employed with 500 ppm designed lead concentration. The 43  dosage was 1 g to 10 mL of the spiked solution with a pH of 3.6 selected based on the Li and Li (2000)?s research. The full descriptions of the method were reported in the Appendix B.4.  3.7.8 The Application of the MSBAC10 to Acid Rock Drainage (ARD) Solution  MSBAC10 was applied to the natural Britannia Mine ARD solution without additional spiking. 40 mL of the ARD solution at pH 4.23 was contacted with 1 g of MSBAC10 for five minutes for two continuous sorption tests. Furthermore the sorption isotherms of copper, iron, aluminum and zinc on MSBAC10 were obtained in multiple-metal solutions with the background matrix of natural Britannia Mine ARD. The solutions were spiked to the concentrations from 0 to 1000 ppm for each metal, but the actual concentration varied according to the concentrations used in Lai (2005)?s paper for the comparison purpose. The sorption dosage was 1 g of MSBAC10 to 10 mL of spiked solution with pH of 3.28 in a 24-hour period. Lai (2005)?s results were given in Appendix C.3.1.  3.8  Cost Estimation  The cost of converting sludge to SBAC is mainly constituted by the cost of the energy required for the sludge and together with that of the chemicals used during the conversion. The cost estimation is as follows:   Total cost = cost of the electricity + cost of chemicals (nitrogen gas, ZnCl2, nitric acid + distilled water) + cost of labour + transportation costs ? the cost of the sludge disposal 3.9  Quality Assurance and Quality Control Since the CS, SBAC, MSBACs were prepared through different batches of conversions and modifications, the same material from each batch was collected and mixed together thoroughly to ensure uniformity before conducting batch sorption tests.   44  All the glassware (the amber glasses, tubes, volumetric flasks and beakers) and polypropylene test tubes for sorption testing were washed with 0.5% nitric acid, then rinsed three times with each of tap water and distilled water to eliminate the potential for residual metals.  Four replicates were prepared to measure the total and volatile solids (TS and VS) of sludge with the standard deviation of 0.005% and 0.016% respectively. Ten batches of conversion tests were employed to calculate the individual percentage yield for CS with the standard deviation of 1.43%. Duplicate samples were prepared for all batch sorption tests for CS, SBAC, MSBAC0, MSBAC4, MSBAC10 and other adsorbents to verify the reproducibility. Ranges of the adsorption errors were shown in the corresponding result sections and varied from 0.02 to 5.44%.  Prior to the use of the atomic sorption spectrometer (AAS), the equipment was warmed up for at least 15 minutes to maximize the signal sensitivity. During lead concentration measurements, one check standard was measured for every 10 samples employed to verify the offset of measurement.  45  Chapter 4: RESULTS AND DISCUSSION Section 4.1 discusses the characteristics of the adsorbents. Section 4.2 summarizes the preliminary sorption test results for carbonized sludge (CS). Sections 4.3 and 4.4 provide the main results for the batch sorption and desorption tests. The discussion of modification and sorption mechanisms is provided section 4.5. Section 4.6 reports the results of the applications on the real contaminated solution to investigate the effectiveness of the adsorbents. The last section summarizes the cost estimation for converting sewage sludge to activated carbon. 4.1  Material Characterizations  4.1.1 The Characterization of Raw Sludge (RS) The characteristics of raw sludge were summarized in Table 4.1. RS had nearly neutral pH of 6.91 and a specific surface area of 19.84 m2/g. The average value of the four replicates for total solids in the sludge was 0.464% ? 0.005%, whereas volatile solids were 0.391% ? 0.016%. The VS/TS ratio was high of 0.84, indicating most solids were volatile solids. The total carbon content of the sludge, which was an important factor for a feasible conversion of the activated carbon from the dry sludge, was 38.65% based on the elemental analyses. In addition, the CS percentage yield (i.e. the percentage between the final weight of CS and total weight of RS) ranged from 34.2% to 38.5% based on 10 sets of conversion test measurement, and the weight loss was due to the decomposition as volatile gas and steam.        46  Table 4.1 The Characteristics of Raw Sludge Parameters Value pH 6.91 Total Solid (TS) 0.464% ? 0.005%1 Volatile Solid (VS) 0.391% ? 0.016%2 VS/TS 84.1% Total Carbon 38.65% Yield Percentage of CS: final weight/total weight 34.2% - 38.5%3 BET Surface Area (Dry Sludge) 19.84 m2/g4 1&2 4 replicates; ??? is the highest and lowest difference from the average value.   3 10 replicates; ??? is the highest and lowest difference from the average value.  4 single sample Figure 4.1(a) shows the dry sludge as being brown before its conversion and Figure 4.1(b) shows the carbonized sludge as being dark in colour, indicating the occurrence of carbonization.      Figure 4.1 Color of Sludge (a) Dry Sludge before Conversion; (b) Carbonized SludgeThe total metals in the raw sludge and its leachate after 24 hours rotating with distilled water were summarized in Table 4.2. The raw sludge had a relatively high content of iron (Fe, 13.51 mg/g), coinciding with the brown colour of the dry sludge shown in Figure 4.1(a) which also indicated the existence of iron compounds. However, the concentration of Fe from its leaching solution was low at 0.96 ppm, suggesting that most of the iron in the sludge was stable in a solution. There was trace amount of lead (Pb2+)  0.05 mg/g, and only 0.49 ppm of Pb2+ in its (b) (a) 47  leachate (equivalent to 0.02 mg/g of the RS will be leached) (see Table 4.2). Even if all the lead were leached out, the amount would be insignificant comparing to the employed lead concentration to influence the sorption tests in this study.   Table 4.2 Metal Concentrations of Raw Sludge and Its Leachate  Raw Sludge1,3  Raw Sludge Leachate2,3 Metal Concentration (mg/g)  Concentration (ppm) Aluminum (Al) 4.68  0.34 Arsenic (As) ND  ND Cadmium (Cd) ND  0.007 Chromium (Cr) 0.40  0.023 Copper (Cu) 1.42  2.00 Iron (Fe) 13.51  0.96 Lead (Pb) 0.05  0.52 Manganese (Mn) 0.34  0.15 Nickel (Ni) 0.03  0.21 Zinc (Zn) 1.63  0.88 1 Metal concentrations of raw sludge by total digestion with nitric acid  2 Leachate metal concentration of RS after 24 hours in a rotating column with 1 g of RS to 40 mL of distilled water at pH =3 3 Other metal concentrations are given in Appendix C.1.5.   ND = below the detection limit    48  4.1.2 The Physicochemical Properties of Sludge Based Adsorbents  The physicochemical properties of all the sludge-based adsorbents produced in this research were summarized in Table 4.3. The detailed data for specific surface areas were summarized in Appendix C.1.3 and for cation exchange capacities (CEC) in Appendix C.1.4. Table 4.3 Physicochemical Properties of Sludge Based Adsorbents  Materials  Physicochemical Properties CS1 SBAC2 MSBAC03 MSBAC43 MSBAC103 Total Carbon % 44.29 61.68 62.05 60.51 52.29 Total Nitrogen % 6.01 6.38 7.65 7.73 7.68 Total Hydrogen % 1.98 3.54 2.9 2.28 2.46 Initial pH (in CaCl2)  5.31  3.83 2.42 2.06 1.04 Specific Surface Area (m2/g)  202.1  721.2 674.7 214.6 86.1 CEC (meq/100g)  4.94  2.26 1.62 1.52 1.40 1CS= carbonized sludge 2SBAC= sludge based activated carbon (with activation of ZnCl2) 3MSBAC0= SBAC impregnated with 10M HNO3 (1 g to 4 mL) at 20?C for 4 hours   MSBAC4= SBAC impregnated with 10M HNO3 (1 g to 4 mL) at 90?C for 4 hours   MSBAC10= SBAC impregnated with 10M HNO3 (1 g to 10 mL) at 90?C for 4 hours  4.1.3 Dissolved metals in CS, SBAC, MSBACs Table 4.4 summarizes the major metals? concentrations in the leachate solution of CS and SBAC from the stability tests. The leachate solution from the CS and SBAC met the legal requirement for GVR&DD sewer use except for the concentration of iron leachate from CS was in exceedance, which could be due to the high level of the iron concentration in the raw sludge 49  (see Table 4.2). Since only Pb2+ was spiked to the following sorption tests, all the other metals from the SBAC leachate would meet the discharge criteria.  Table 4.4 Dissolved Metal Concentration from the Leachate of the CS and SBAC Following 24 Hours in Distilled Water at pH of 3 with 1 g to 40 mL Ratio  CS1,4  SBAC2,4  GVS&DD Sewer Use Bylaw 3 Metal Concentration (ppm)  Concentration (ppm)  Maximum Concentration (ppm) Aluminum 3.00  1.65  50 Arsenic ND  0.01  1 Cadmium 0.01  ND  0.2 Chromium 0.02  0.01  4 Copper 0.13  0.31  2 Iron 13.19  0.08  10 Lead 0.31  0.61  1 Manganese 0.19  0.01  5 Nickel 0.02  0.04  2 Zinc 28.37  ND4  3 1 Leachate metal concentration of carbonized sludge (CS) following  24 hours with 1 g of CS to 40 mL of distilled water at pH =3  2 Leachate metal concentration of sewage sludge based activated  carbon (SBAC) following 24 hours with 1 g of SBAC to 40 mL of distilled water at pH =3  3 The standards from the Great Vancouver Sewerage and Drainage District (GVS&DD) Sewer Use Bylaw No. 299 restrict the maximum lead concentration that can be dumped into the sewer is 1.0 ppm. Any cumulative discharge of non-domestic waste into a sewer in excess of 300 cubic meters over any consecutive 30 days period or any instantaneous discharge of non-domestic waste in excess of 30 liter per minutes   4 Other metal concentrations are given in Appendix C.1.5. ND = the concentration value is below detection limit   50  4.1.4 X-Ray Diffractograms for CS and SBAC The non-quantitative XRD spectra for the CS and SBAC were shown in the Figure 4.2. The sharp peaks between angles 26? and 27? indicated the presence of graphite-like structure in the CS and SBAC, but the sharper peak was observed in SBAC. In addition, the semi-quantitative XRD spectra (see Appendix C.1.6) also showed the similar peaks between angles 26? and 27?. 90% of both materials were amorphous indicating that small crystallinity was occurred during the carbonization and activation, and the mineral percentages for CS and SBAC are reported in Table 4.5. The percentage of graphite was not provided because its signal was obscured by the signal of quartz. SBAC had a higher percentage of quartz comparing to CS, which could probably due to the formation of graphite by ZnCl2 activation that could provide more carbon skeleton and created the pore-structure during the activation. The complete results of the semi-quantitative analyses were shown in Appendix C.1.6.   51  Table 4.5 The Mineral Composition of CS and SBAC from Semi-Quantitative X- Ray Diffraction Analysis Mineral Ideal Formula % in the CS % in the SBAC Actinolite Ca2(Mg,Fe2+)5Si8O22(OH)2   Albite low NaAlSi3O8 23.7 37.6 Anatase TiO2  6.2 Biotite 1M K(Mg,Fe)3AlSi3O10(OH)2   Calcite CaCO3 4.6  Calcite, magnesian (Ca,Mg)CO3 4.9  Clinochlore II (Mg,Fe2+)5Al(Si3Al)O10(OH)8   Crandallite CaAl3(PO4)2(OH)5?H2O 11.1  Gehlenite Ca2Al(Al,Si)O7 29.4  Goethite FeO(OH)   Gypsum CaSO4?2H2O   Illite-Muscovite 2M1 K0.65Al2.0Al0.65Si3.35O10(OH)2   Laumontite CaAl2Si4O12?4H2O   Magnesite MgCO3 4.1  Magnetite Fe3O4   Microcline ordered KAlSi3O8   Monetite CaHPO4 9.9  Quartz low SiO2 12.3 27.0 Rutile TiO2  21.8 Talc Mg3Si4O10(OH)2  7.5 Total  100.0 100.0 Note: These amounts represent the relative amounts of crystalline phases normalized to 100% amorphous-free, and CS and SBAC are 90 % amorphous 52    Figure 4.2 Non-quantitative X-Ray Diffraction Spectra for CS and SBAC01-075-2078 (C) - Graphite - C - WL: 1.5406 - Rhombo.R.axes - a 3.63500 - b 3.63500 - c 3.63500 - alpha 39.490 - beta 39.490 - gamma 39.490 - Primitive - R-3m (166) - 2 - 17.4850 - I/Ic PDF 2.3 - S-Q 100.0 % - F1File: carbonized sludge.raw - Start: 5.000 ? - End: 75.001 ? - Step: 0.039 ? - Step time: 181. s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mAFile: ZnCl2-AC c washed.raw - Start: 5.000 ? - End: 75.001 ? - Step: 0.039 ? - Step time: 181. s - Anode: Cu - WL1: 1.5406 - WL2: 1.54439 - kA2 Ratio: 0.5 - Generator kV: 40 kV - Generator mA: 40 mALin (Cps)01020304050607080901001101201301401502-Theta - Scale5 10 20 30 40 50 60 70SBAC CS 53  4.1.5 Surface Functional Groups on Activated Carbons - Fourier Transform Infrared (FTIR) Spectroscopy  The FTIR spectra of the CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 with full ranges of wavenumber (600 to 4000 cm-1) were presented in Figure 4.3, which provided the information about the surface chemistry of the sludge-based adsorbents.  The interpretations of corresponding functional groups were assigned based on the Table 2.3. The peaks between 650 and 700cm-1 for all the adsorbents could be assigned to out-of-plane deformation vibrations of C-H groups on the edges of aromatic planes (Song et al., 2010). CS exhibited a narrow band between 1100 and1200 cm-1with a peak that might be ascribed to -C-OH (stretching) at 1106.60cm-1. SBAC, MSBAC0, MSBAC4 and MSBAC10 also presented similar peaks within that range, but with sharper peaks which could contribute to the lower pH value: SBAC = 3.83, MSBAC0 = 2.42, MSBAC4 = 2.06 and MSBAC10 = 1.05 (Table 4.3). The intensities of the peaks at 1106.60 and 2918.37 cm-1 were relatively small and no large peaks were detected between 1200 and 2500 cm-1, which indicated that the CS was lacking in the functional groups on its surface and had fewer sorption sites available in its edge Comparing to CS, SBAC and MSBACs (i.e. MSBAC0, MSBAC4 and MSBAC10) presented more peaks within the range from 1000 to 2000 cm-1. The SBAC and MSBACs showed similar FTIR spectra over the entire region, but new peaks were detected in three MSBACs? spectra. Those new peaks were observed at 1216 and 1531 cm-1, which could be assigned to the carboxylic anhydride or C=O groups (C-O in ethers stretching), and C=N or C-N=O groups respectively.  54   Figure 4.3 The FTIR Spectrum of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 (wavenumbers in the 600 to 4000 cm-1 range) Figure 4.4 compares the spectra between 1000 and 2000 cm-1 for SBACs and MSBACs. A new band at 1531 cm-1 assigned to C=N or C-N=O groups, and 1216 cm-1 appeared for MSBAC10 which might also be assigned to N-O- (Table 2.3) demonstrated the introduction of nitrogen to the activated carbon during modification.  Also, comparing to SBAC, the increased intensities at 1585 cm-1 were observed for three MSBACs and the MSBAC10?s peak was the 1106.6 1216 CS SBAC MSBAC0 MSBAC4 MSBAC10   See Figure 4.4 55  sharpest, which suggested that more carboxyl (R-COO-) groups were produced after SBAC being modified. The variety of peak intensities at 1531 cm-1 among the MSBACs is due to the different modification condition: oxidation of SBAC with nitric acid at a higher temperature of 20?C for MSBAC0 than 90?C of MSBAC4, and with a higher dosage of nitric acid for MSBAC4 than for MSBAC10. The sharpest peak at 1531 cm-1 and 1585 cm-1 suggested that higher modification temperature and dosage could  result in more carboxyl and C-N=O groups during the modification.   Figure 4.4 The FTIR Spectrum of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 (wavenumbers in the 1000 to 2000 cm-1 range) 1531 1585 CS SBAC MSBAC0 MSBAC4 MSBAC10   56  4.2  Preliminary Batch Sorption Tests on Carbonized Sludge (CS) 4.2.1 The Sorption Kinetics   The sorption kinetics of CS with different contact time of 5, 10, 20, 40, 80, 160, 720 and 1440 minutes in a 92.5 ppm Pb solution with pH of 3 is shown in Figure 4.5. 90.1% sorption reached after 80 minutes contact time (~ 2.0 mg/g Pb adsorbed onto CS). It reached equilibrium in 24 hours with the maximum adsorptivity of 2.15 mg/g. Therefore, 80 minutes was selected for the further batch sorption tests of the carbonized sludge  Figure 4.5 The Sorption Kinetics of CS in 92.5 ppm of Pb2+ Solution at pH = 3, Solid-to-solution Ratio = 1 g: 40 mL, Data in Duplicate  4.2.2 pH Effect  The pH effects on sorption of Pb at different concentrations (5, 10, 20, 50 and 100 ppm) were shown in Figure 4.6. (See section 3.7.2 Table 3.3 for experimental program). The highest lead removal of 2.7 mg/g was obtained with the solution which has the initial lead concentration of 82.8 mg/L at pH =7. The lowest lead removal was 1.99 mg/g at pH of 3, which was close to the lead removal (2.01 mg/g) measured for an 80-minute contact time from the previous CS 00.511.522.510 100 1000Adsorptivity (mg/g)  Adsorption Time (min) in log Scale 57  sorption kinetics test, indicating a good quality control between the two different batch sorption tests, and the consistency of the adsorbent.  The pH of an adsorbate is considered to be an influential parameter governing the sorption process. An increase in the solution?s pH led to a rising in the adsorptivity of the lead ions (see Figure 4.6). According to the Pourbaix Diagram of Lead (see Appendix C.1.8), Pb (II) predominantly exists as the divalent free ion Lead (II) (Pb2+) at pHs below 6.7, and precipitates as Pb(OH)2 at pH values greater than 6.7, which is not involved in the sorption process. The high removal of Pb2+ by CS at pH =7 can be due to both precipitation and sorption. The different sorption behaviours at pHs of 3 and 5 is likely due to the competition of the hydrogen ions (H+) and Pb2+ for the negative sorption sites on the CS. A higher solution pH (with fewer H+ ions) causes less competition between H+ ions and Pb2+, which consequently enhances the uptake capacity of adsorbents for Pb2+. Therefore, in order to guarantee Pb2+ removal only by the sorption process instead of co-precipitation, and to create more H+ competition for the adsorption sites, the pH of 3 was used for the solutions in the all following batch experiments.   Figure 4.6 The Sorption Isotherms of CS for Pb2+in 80 minutes with Solutions of pH =3, 5, 7, and the Solid-to-liquid Ratio = 1 g: 40 mL, Data in Duplicate   00.511.522.530 10 20 30 40 50Lead Removal by CS (mg/g) Equilibated Pb Conc. (ppm) pH=3pH =5pH =758  4.3  Lead Sorption Capacities onto CS and SBAC  4.3.1 Sorption Kinetics of SBAC The sorption kinetics of SBAC with different contact time of 1, 5, 10, 360,720 and 1440 min in the 102.5 ppm Pb solution with pH of 3 is shown in Figure 4.7. The adsorptivity at equilibrated condition after 24 hours was 1.25 mg/g, whereas the adsorptivity of 1.07 mg/g was attained after five minutes which was 83% of the equilibrated adsorptivity. Therefore, five minutes was decided for the time of SBAC?s sorption isotherm tests (section 4.3.2).    Figure 4.7 The Sorption Kinetics of SBAC in 102.5 ppm of Pb2+ Solution at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL, Data in Duplicate     00.20.40.60.811.21.41 10 100 1000 10000Adsorptivity (mg/g) Adsorption Time (min) in log Scale 59  4.3.2 Concentration effect on Sorption of CS and SBAC 80 min contact time was set for CS and 5 min for SBACs based on the previous kinetics tests. The results of concentration effects ranging from 100 to 1000 ppm on Pb2+ sorption were shown in in the Figure 4.8(b). CS reached its maximum sorption capacity of 4.52 mg/g in 1000 ppm Pb2+ solution with 920 ppm left (Figure 4.8(a)). A more linear trend of SBAC isotherm curve indicated that the maximum adsorptivity was not reached, and its adsorptivity at 1000 ppm was 16.93 mg/g with 608 ppm remaining in the solution. The pHs of the solution after sorption with CS and SBAC were also plotted, and small changes of the pH were observed with ?pH < 0.1 for CS and SBAC indicating only a little competition for the adsorption sites between Pb2+ and H+ ions.  Figure 4.8 The Sorption Isotherm of CS for the Pb Solution at pH = 3, Solid-to-solution Ratio = 1g: 40 mL in 80 min and SBAC in 5 min: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity; Data in Duplicate   02004006008001000110 200 495 802 1033Conc. Remaining in Solution (ppm) Intial Solution Conc. (ppm) CSSBAC(a) y = 0.1525x0.4961 R? = 0.9404 y = 0.0019x1.4199 R? = 0.9954 11.522.530246810121416180 500 1000Final pH Adsorptivity (mg/g) Equlibrated Conc. (ppm) CSSBACpH datafor CSpH datafor SBAC(b) 60  4.3.3 A Comparison of CS and SBAC, and their Lead Sorption Capacities  The sorption kinetics of CS and SBAC were evaluated using a pseudo-second-order kinetics model (see Eqn. 3.2) shown in Figure 4.9. Both kinetics curves presented the data having a good fit with this model with correlation values R2 close to 1. The values of the rate constant k and equilibrated adsorptivities were summarized in Table 4.6. This model implies that chemisorption is the predominant process for CS and SBAC, which is usually restricted to one layer of molecules on the adsorbent surface. CS showed a stronger sorption capacity but a slower sorption rate than that of SBAC at the low concentration range (0-100 ppm). However, as the initial concentration increased to 1000 ppm, the sorption capacity of SBAC surpassed the CS (see Figure 4.9), which was likely due to the larger BET surface area (Table 4.3).   Figure 4.9 Plots of Pseudo-second-order Models for the Sorption Kinetics of CS and SBAC   y = 0.4647x + 5.3075 R? = 0.9996 y = 0.8006x + 2.7309 R? = 0.9999 02004006008001000120014000 500 1000 1500 2000t/qt (min g/mg) Time (mins) CSSBAC61  Table 4.6 Calculated Parameters of the Pseudo-second-order, Langmuir and Freundlich Models for CS and SBAC Models Parameters CS SBAC Pseudo-second-order Kinetics Model Equilibrium Adsorptivity (mg g-1) a 2.15 1.25 Pseudo-second - order rate constant k b (g mg-1 min -1) 0.041 0.23 Correlation Coefficient R2 0.9996 0.9999     Langmuir Q0 (mg g-1 ) 6.08 -11.89 KL (L mg-1) 0.003 -0.001 Correlation Coefficient R2 0.913 0.865     Freundlich KF (mg g-1 (L g-1 )1/n) 0.150 0.002 1/n 0.496 1.420 Correlation Coefficient R2 0.940 0.995 a Calculated from the measured date obtained by atomic sorption spectroscopy b Calculated from the kinetic model A regression analysis of the equilibrated isotherm data for CS and SBAC was also evaluated using the Langmuir (Figure 4.10 (a)) and Freundlich (Figure (4.10 (b)) sorption models. Table 4.6 summarizes the values of the characteristic parameters (Q0, KL, 1/ n and KF) calculated from the intercept and slope of the linear trend lines, and the correlation coefficients (R2) for each model (Langmuir and Freundlich). The values of R2 indicate the Freundlich model (0.940 < R2<0.995) provides a better fit to the data than Langmuir model (0.865 < R2<0.913) for SBAC and CS. The negative value of the Langmuir isotherm constant KL for the SBAC indicates the inadequacy of the Langmuir model to interpret the sorption process. Therefore, the Freundlich model was adopted to explain the sorption process.  62    Figure 4.10 Linear Models for Pb2+ Sorption onto CS and SBAC: a) The Langmuir Isotherm Model; b). The Freundlich Isotherm Model Overall, ZnCl2 activation was effective on retaining more carbon and creating a porous structure during the conversion of sludge to SBAC. The SBAC had a higher total carbon content of 61.68% than that of CS with 44.29% and also presented a larger BET surface area of 721 m2/g comparing to CS with 202.1 m2/g (see Table 4.3), both of which demonstrated that Also the SBAC leachate had lower metal concentration than CS (see Table 4.4).  Based on these characteristics along with the results of sorption kinetics and capacity, SBAC was preferred as the precursor to be further modified to enhance the lead sorption capacity. y = 0.4961x - 0.8168 R? = 0.9404 y = 1.4199x - 2.7246 R? = 0.9954 00.20.40.60.811.21.40 1 2 3 4Lg(Adsorptivity) lg (Equlibrated Conc.) CSSBAC(a) y = 0.1661x + 56.44 R? = 0.913 y = -0.0841x + 81.893 R? = 0.865 0501001502002500 500 1000Equilirated Conc. /Adsorptivity (g/L) Equilibrated Conc. (ppm) CSSBAC(b) 63  4.4  The Capacity of Lead Sorption onto Modified SBACs  4.4.1 Sorption Kinetics for MSBAC0, MSBAC4 and MSBAC 10 The sorption kinetics of MSBAC0, MSBAC4 and MSBAC10 with different sorption periods of 1, 5, 10, 720, and 1440 minutes were shown in Figure 4.11.  Figure 4.11 Sorption Kinetics of MSBAC0, MSBAC4 and MSBAC10 with 100 ppm Pb2+ at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL, Date in Duplicate  4.4.1.1 MSBAC0 The equilibrated adsorption occurred after 24 hours with the adsorptivity of 3.04 mg/g. It had a fast sorption process, and its adsorptivity was 1.1 mg/g after one minute. The breakthrough point took place after five- minute of contact, and the adsorptivity increased to 2.64 mg/g (~ 95% of the equilibrated adsorptivity). Therefore, five-minute was employed as the sorption time for the following sorption isotherm tests.     00.511.522.533.544.51 10 100 1000Adsorptivity (mg/g) Adsorption Duration (min)  MSBAC0MSBAC4MSBAC1064  4.4.1.2 MSBAC4 and MSBAC10 More rapid sorption process was observed with MSBAC4. The adsorptivity was 3.4 mg/g at one minute and 3.48 mg/g at five minutes, both of which were over 95% of the equilibrated adsorptivity 3.57 mg/g after 720 minutes.  Similar to MSBAC4, 94.7% of the total lead (3.88 mg/g) was removed by the MSBAC10 after one minute of contact time and 4.03 mg/g at five minutes. The equilibrated adsorptivity of 4.05 mg/g occurred after 720 minutes only 0.02 mg/g difference after 720 minutes. To have better control of the tests and be comparable with MSBAC0, five-minute contact time was selected for determining the sorption isotherm of MSBAC4 and MSBAC10.    4.4.2 Sorption Isotherms of MSBAC0, MSBAC4 and MSBAC 10  Figures 4.12, 4.13 and 4.14 present the sorption isotherms for the MSBAC0, MSBAC4 and MSBAC10 with 5 min contact time and variable Pb2+ concentrations at pH of 3. The maximum adsorptivity was 12.44 mg/g, 23.38 mg/g and 26.55 mg/g for MSBAC0, MSBAC4 and MSBAC10, respectively. MSBAC10 showed a strongest sorption capacity among the MSBACs at all different concentrations. The MSBAC4 and MSBAC10 were effective at low concentrations (100 ppm and 200 ppm). ~ 93% of lead in the solution was removed by MSBAC4 with equilibrated concentration of 3.8 ppm and 14.13 ppm corresponding to 100 ppm and 200 ppm solutions, and ~97% removal for MSBAC10 with equilibrated concentration of 2.12 ppm and 7.50 ppm. The final pHs after each sorption corresponding to the equilibrated concentrations were also plotted in the figures.    65   Figure 4.12 The Sorption Isotherm of MSBAC0 for Pb2+ at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL in 5 min and Final pH Values: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity;  Date in Duplicate   Figure 4.13  The Sorption Isotherm of MSBAC4 lead at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL in 5 min and Final pH Value: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity; Date in Duplicate   44.0 60.1 251.5 483.4 685.2 0.0100.0200.0300.0400.0500.0600.0700.0800.0103 183 488 751 1000Conc. Remaining in Solution (ppm) Initial Solution Conc. (ppm) (a) y = 0.4238x0.5311 R? = 0.8906 2.652.72.7502468101214160 500 1000pH Adsorptivity (mg/g) Equilirated Conc. (ppm) Adsorption datepH data(b) 3.8 14.1 112.9 289.5 419.1 0.050.0100.0150.0200.0250.0300.0350.0400.0450.099 198 495 792 996Conc. Remaining in Solution (ppm) Initial Solution Conc. (ppm) (a) y = 2.5048x0.3727 R? = 0.9911 2.32.352.42.452.52.552.605101520250 200 400 600pH Adsorptivity (mg/g) Equilirated Conc. (ppm) Adsorption DatepH date(b) 66   Figure 4.14 The Sorption Isotherm of MSBAC10 lead at pH = 3, Solid-to-liquid Ratio = 1 g: 40 mL in 5 min and Final pH Value: a) the Plot of Initial Conc. vs Remaining Conc.; b) the Equilibrated (or Remaining) Conc. vs Adsorptivity; Date in Duplicate  4.4.3 A Comparison of Lead Sorption of MSBACs with CS and SBAC  The results of the kinetic analysis based on the pseudo-second order model for MSBAC, MSBAC4 and MSBAC10 were summarized on Table 4.7. The sorption time / corresponding adsorptivity (t/qt) were plotted against the sorption time for MSBAC, MSBAC4 and MSBAC10, and were illustrated in Figure 4.15. The plots were fit to the pseudo-second order model since the correlation coefficients R2 were close or equal to 1.  Table 4.7 Calculated Equilibrium Concentrations and Pseudo-second-order Rate Constants for Lead Parameters MSBAC0 MSBAC4 MSBAC10 Equilibrium adsorptivity (mg g-1) a 3.04 3.60 4.05 Pseudo-second-order rate constant kb (g mg-1 min -1) 0.02 1.34 4.15 Correlation Coefficient R2 0.9985 1 1 Notes:  a Calculated from the measured date obtained by atomic sorption spectroscopy b Calculated from the kinetic model (also see section 3.75 eqn3.3)  2.1 7.5 68.6 225.3 339.0 0.050.0100.0150.0200.0250.0300.0350.0400.0100 208 466 810 1004Conc. Remaining in Solution (ppm) Initial Solution Conc. (ppm) (a) y = 4.4346ln(x) - 0.4828 R? = 0.972 22.12.22.32.42.52.60510152025300 200 400pH Adsorptivity (mg/g) Equilirated Conc. (ppm) Adsorption DatapH Data(b) 67   Figure 4.15 Plots of Pseudo-second-order Model for the Sorption Kinetics of MSBAC0, MSBAC4 and MSBAC10 Based on the rate constant k values, MSBAC10 had the highest value of 4.15 (See Table 4.7), indicating that MSBAC10 was the fastest in all the sludge based adsorbents (CC, SBAC and MSBACs). The difference in k values for these modified adsorbents was due to the variation of acid surface functional groups, such as carboxylic acid, generated during the modification phase.  The regression analysis of the experimental data for MSBAC0, MSBAC4, and MSBAC10 sorption isotherms was also conducted using the Langmuir (Figure 4.16) and Freundlich (Figure 4.17) sorption model. The values of the characteristic parameters (Q0, KL, n and KF) calculated from the intercept and slope of the linear trend lines, and the correlation coefficients (R2) for each model, were summarized in Table 4.8.  y = 0.3294x + 5.423 R? = 0.9985 y = 0.2779x + 0.0576 R? = 1 y = 0.2468x + 0.0147 R? = 1 01002003004005006000 200 400 600 800 1000 1200 1400 1600t/qt (min g/mg) Time (mins) MSBAC0MSBAC4MSBAC1068   Figure 4.16 A Linear Model of the Langmuir Isotherm for Pb2+ Sorption onto MSBAC0, MSBAC4 and MSBAC10, Date in Duplicate  Figure 4.17 A Linear Model of the Freundlich Isotherm for Pb2+ Sorption onto MSBAC0, MSBAC4 and MSBAC10, Date in Duplicate     y = 0.0633x + 12.168 R? = 0.9695 y = 0.0415x + 1.6152 R? = 0.9862 y = 0.0361x + 0.9904 R? = 0.9859 01020304050600 100 200 300 400 500 600 700 800Equlilbrated Conc /Adsorptivity (g/L) Equlibrated Conc. (mg/L)  MSBAC0MSBAC4MSBAC10y = 0.5311x - 0.3728 R? = 0.8906 y = 0.3727x + 0.3988 R? = 0.9911 y = 0.3661x + 0.521 R? = 0.9855 00.20.40.60.811.21.41.60 0.5 1 1.5 2 2.5 3Log (Adsorptivity) log (Equilirated Conc.) MSBAC0MSBAC4MSBAC1069  Table 4.8 Values of the Parameters for the Langmuir and Freundlich Model Models Parameters MSBAC0 MSBAC4 MSBAC10 Langmuir Q0 (mg g-1) 15.58 24.09 27.70 KL (L mg-1) 0.0053 0.0257 0.0265 Correlation Coefficient R2 0.969 0.986 0.986      Freundlich KF (mg g-1 (L g-1 ) 1/n) 0.424 2.505 3.344 1/n 0.530 0.373 0.362 Correlation Coefficient R2 0.891 0.991 0.985 Although good correlation coefficients (0.891 < R2<0.991) were also provided by the Freundlich isotherm model, Langmuir provided a better fit for the data gathered from lead?s sorption onto MSBAC0, MSBAC4 and MSBAC10  (0.969 < R2<0.986). These results indicated the occurrence of a monolayer sorption of Pb2+ onto MSBAC0, MSBAC4 and MSBAC10. Moreover, the constant 1/n from the Freundlich model of less than one indicated the sorption process by MSBACs was a favourable chemical sorption process.  This study demonstrated that modification of SBAC by nitric acid had a significant improvement on the sorption of Pb2+. The modified SBACs were faster and had better sorption capacities than both of CS and SBAC. Overall, the sorption capacity for lead followed the order of MSBAC10 > MSBAC4 > MSBAC0> SBAC > CS, except when the initial concentration was greater than 500 ppm, the adsorptivity of MSBAC0 was less than SBAC (see Figure 4.22). This was because that the MSBAC0 had a slightly lower BET surface area of 674.7 m2/g than that of SBAC with 721.2 m2/g (Table 4.3). Also insufficient reaction temperature and acid dosage at the stage of modification for MSBAC0 had small contribution to acidify its surface chemistry which did not compensate the reduction of adsorption capacity by less adsorption sites. The modification and sorption mechanisms were discussed in section 4.5.  70  4.4.4 Leachability Tests for CS, SBAC, MSBACs after Lead Sorption The adsorbents contacted with 1000 ppm Pb2+ solution were tested for lead leachability using distilled water at a pH of 3 for 24 hours, and their results for sorption and desorption were provided in Figure 4.18 (a) and (b). The leachability was ranked as MSBAC0 (23.3%)> CS (22.6%) > MSBAC4 (2.0%) > SBAC (1.3%) > MSBAC10 (0.90%) based on the mass percentage of lead ions being leached out. The MSBAC0 showed a relatively weaker adsorption and retention capacity for Pb2+, which could be likely due to the low modification temperature (20?C) required to acidify the surface of the SBAC and the weak electrostatic bonding force between MSBAC0 and the lead ions. However, the strong retention capacity of MSBAC4 and MSBAC10 suggested a different holding mechanism that could be likely due to the ion exchange between the adsorption site on the surface of the adsorbents and the lead ions, and formation of new chemical bonds after sorption. However, in terms of disposal of the used adsorbents, it could problematic to disposal in landfill due to the potential of metals leached out from the materials. The desorption tests were performed at the extreme cases in which the adsorbents were contaminated with high lead concentration (i.e. 1000 ppm) and desorbed with low pH solution (i.e. pH =3), whereas the repeated desorption tests with different solution pH were recommended along with the recovery tests of the used adsorbents.       71   Figure 4.18 The Desorption Tests of CS, SBAC, MSBAC0, MSBAC4, MSBAC10 by Distilled Water at pH=3 with 1 g: 40 mL Ratio after Spiked with 1000 ppm Pb2+ Solution, n=2: a) Leached Pb2+ Concentration from Adsorbents in Solution; b) Adsorptivity and Desorptivity of Adsorbents; Data in Duplicate 4.4.5 Repeated Sorption Tests for MSBAC10  MSBAC10 exhibited the highest sorption capacity for Pb2+ was selected for the repeated sorption tests determine the extent of its reusability. Figure 4.19 (a) shows the remaining lead concentration in solution after each adsorption tests.  Figure 4.19 (b) and (c) shows the accumulated adsorptivity and single adsorptivity with the corresponding solution pH for 10 sorption tests. MSBAC10 had the highest adsorptivity of 4.04 mg/g in the first two sorption tests, which was equivalent to a 99% Pb2+ removal efficiency. After the 10th sorption, the MSBAC10 remained a high adsorptivity with 3.66 mg/g (~91% removal). The final pHs after sorption were less than pH of 3. The final pH value presented an increasing trend through the repeated batch sorption tests, indicating that fewer H+ ions on the MSBAC10 were being exchanged with Pb2+.  6.17 11.85 73.25 5.50 4.06 01020304050607080Leached Concentration in Solution (ppm) Adsorbents  (a) 27.82 23.01 12.59 16.94 3.22 0.25 0.47 3.53 0.22 0.16 0.005.0010.0015.0020.0025.0030.00Sorptivity (mg/g) Adsorbents AdsorptivityDesorptivity(b) 72      Figure 4.19 Repeated Sorption Tests for MSBAC10 with 102.5 ppm Pb2+ Solid-to liquid Ratio of 1 g to 40 mL at pH =3 in 5 min, Data in Duplicate: a) Remaining Concentration in Solution after Adsorption; b) Accumulated Adsorptivity by MSBAC10; c) Adsorptivity and Solution pH for Each Repeated Test 1.54 1.49 1.91 2.83 4.095 4 5.5 5.69 8.465 11.065 0246810121st 2nd 3rd 4th 5th 6th 7th 8th 9th 10thConc. Remaining in Solution (ppm) No. of Adsorption Tests (a) 4.04 8.08 12.10 16.09 20.03 23.97 27.85 31.72 35.46 39.12 0.005.0010.0015.0020.0025.0030.0035.0040.0045.001st 2nd 3rd 4th 5th 6th 7th 8th 9th 10thAccumulated Adsorptivity (mg/g) No. of Adsorption (b) 4.04 4.04 4.02 3.99 3.94 3.94 3.88 3.87 3.74 3.66 2.002.102.202.302.402.502.602.702.803.603.653.703.753.803.853.903.954.004.054.101st 2nd 3rd 4th 5th 6th 7th 8th 9th 10thpH Adsorptivity (mg/g) Single Adsorptivity pH(c) 73  4.5  Modification and Sorption Mechanisms  4.5.1 Modification Mechanism   The MSBACs had a much lower pH value, varying from 1.04 to 2.42, than the original SBAC (pH = 3.83) (see Table 4.3). According to the literature review (Song et al., 2010, and Shafeeyan et al., 2010), liquid nitric acid oxidations can introduce a large amount of oxygen onto the carbon surface, which results in a decrease in the material?s pH.  The low pH of MSBACs might be due to the acidic functional groups were being introduced to the SBAC surface during the modification phase. FTIR spectra of the adsorbents (Figures 4.3 &4.4) confirm that, new surface functional groups, carboxylic anhydride and carboxyl R-COO-, were produced after modification. These could be attributed to the reactions as follows:         [4.1]   Since the modification occurred on the edge of the activated carbon such as the reaction [4.2], the edge structures of this carbon were oxidized and resulted in the collapse of the pore structure, which could also be due to the reduction on the BET specific surface area of the MSBACs (see Table 4.3).  The values of the BET surface area were in the order of SBAC > MSBAC0 > MSBAC4 > MSBAC10, which indicated that higher reaction temperatures and acid dosage levels contributed to more surface oxidation with smaller surface area. Less development of the surface area of activated carbon was also observed by EI-Hendawy (2005) and Song et al. [4.2] 74  (2010) after the modification. The MSBAC10 exhibited the lowest surface area with the highest intensity of carboxylic anhydride and carboxyl R-COO- groups which contribute toward the lowest pH values in the solution. In addition to the oxygen-containing functional groups, the nitrogen contained functional groups that were also possibly introduced. The percentage of total nitrogen (N) increasing from 6.38% up to the highest of 7.68% (see Table 4.3) demonstrated the introduction of N. This is also supported by FTIR results (section 4.1.2). Those peaks introduced at 1216 cm-1 were assigned to -N-O- after the modification, while the peaks at 1531 cm-1 could be assigned to C=N or C-N=O. Introducing the nitrogen onto the activated carbon could be explained by the reaction [4.3], which required a higher amount of energy to break down the C-H bond and to form a new bond between the carbon and nitrogen. This was verified by the sharper peaks at band 1216 cm-1 for both MSBAC4 and the MSBAC10, which were treated at higher temperature (90?C) compared to MSBAC0 (at 20?C). As a result, no peak was detected near 1216 cm-1 for MSBAC0.     [4.3] 75  4.5.2 The Sorption Mechanisms Figure 4.20 summarizes the sorption isotherms for the sludge-based adsorbents produced in this research. The liquid phase oxidized SBAC by nitric acid, demonstrated a significant improvement for the lead ions sorption capacity, especially for the MSBAC4 and MSBAC10.   Figure 4.20 The Sorption Isotherm of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 for Pb2+ at pH =3; the Sorption Time is 80 mins for CS, and 5 mins for Other Adsorbents; Data in Duplicate  The sorption behaviours and surface chemistries of the adsorbents can be explained as follows: CS and SBAC: For CS and SBAC, the possible surface structure with the adsorbed lead was proposed as:  C - C: + Pb2+ ? C - C: Pb2+ (C?- cation interactions)                                 [4.4] The C?- cation interactions were mainly due to electrostatic interactions between the ? electrons of the aromatic rings and the lead ion. The same mechanisms for activated carbons y = 0.1525x0.4961 R? = 0.9404 y = 0.0019x1.4199 R? = 0.9954 y = 0.4238x0.5311 R? = 0.8906 y = 2.5048x0.3727 R? = 0.9911 y = 3.3439x0.362 R? = 0.9857 0510152025300 200 400 600 800 1000Adsorptivity (mg/g) Equilibrated Conc. (ppm) CSSBACMSBAC0MSBAC4MSBAC1076  were also proposed by Swiatkowski et al. (2004) and Deliyanni et al. (2012). However, due to the strong metal retaining capacity of CS and SBAC, cation exchange could also be possible, which was proposed as:   R? (M1n+) m + nPb2+ ? R? (Pb2+) n + mM1n+ R? (M1n+) m + nPb2+ ? R? (Pb2+) n + mM1n+ The major exchange cations were metal ions instead of hydrogen ions due to the small peak intensity for the carboxyl acidic groups in CS and SBAC (Figure 4.3); this was in accordance with the insignificant change on the adsorbed solution pH (max. ?pH was 0.05 for CS and 0.1 for SBAC) (see Figure 4.8 (b)). Whereas, low CEC values for CS (4.94 meq/100g) and SBAC (2.96 meq/100g) indicated the weak exchange capacity of the adsorbents, so the electrostatic interaction was likely the dominant force of metal removal. MSBACs The modified SBACs (MSBAC0, MSBAC4 and MSBAC10) presented similar ion exchange behaviors between Pb2+ and H+ on their edge surfaces. Significant drops in the solution pH were observed after the sorption tests, and the ? pH was 0.3, 0.55 and 0.82 for MSBAC0, MSBAC4 and MSBAC10, respectively. Since the MSBAC10 has the highest adsorptivity of Pb2+, Figure 4.21 illustrates the variation in the peak intensity of the MSBAC10s before and after the sorption test. Smaller intensities were observed at bands 1213 and 1112 cm-1 for the MSBAC after adsorbing Pb2+, which indicated the reduction of the carboxylic acid functional groups on its edge, and this reduction could be explained by the exchange between H+ and Pb2+ shown schematically as follows:  R ? COOH + Pb2+ ? R ? C ? OOPb+ + H+                         [4.5] R ? C ? OH + Pb2+ ? R ? C ? OPb+ + H+                        [4.6]  77  Both the pH drop of the solution and the smaller peaks for carboxylic groups after lead sorption prove that the H+ from the carboxylic acid groups were replaced by Pb2+ from the solution after after the solution contacted with the MSBACs. Therefore, the ion exchange was most likely the sorption mechansim for MSBACs.   Figure 4.21 Comparison of FTIR Spectra for Unused MSBAC10 and Adsorbed MSBAC10   Adsorbed MSBAC10   Unused MSBAC10 1112 1213 78  4.6  The Effectiveness of MSBAC10  4.6.1 A Comparison of MSBAC10 with Selected Adsorbents  The sorption capacity of MSBAC10 was compared with that of other adsorbents. 24-hour and five-minute sorption periods were both employed as a basis for comparison. Within a 24-hour sorption period, the sorption capacities were very similar for illite, zeolite, commercially activated carbon (CAC) and MSBAC10 at the ranking of illite ? zeolite ? MSBAC10 ? CAC > kaolinite > perlite (Figure 4.22 (a)). However, the MSBAC10 exhibited a stronger sorption capacity for a shorter sorption period of five minutes. The sorption capacities were ranked as: MSBAC10 > illite (grundite) > zeolite > CAC > kaolinite > perlite (Figure 4.22 (b)). The interaction between mineral adsorbents and lead ions was mainly related to cation exchange mechanism due to the relative large cation exchange capacity (CEC) (see Table 4.9) and co-precipitation during the sorption. As for CAC, it had a similar sorption mechanism to MSBAC10, but CAC?s sorption rate was slower. A rapid sorption rate is important for MSBAC10 with respect to whether it might be suitable as a barrier or reactive-bed material. To summarize, MSBAC10 possesses a faster and stronger sorption capacity for lead when compared with other investigated adsorbents.   79      Figure 4.22 A Comparison of the Adsorptivity of Different Adsorbents at pH = 3.6, initial conc. = 487 ppm with 1 g: 10 mL solid-to-liquid ratio, n = 2: (a) 24 hours; (b) 5 min; Date in Duplicate  Table 4.9 The Adsorptivity Comparisons of Different Adsorbents Material Grundite (illite) Kaolinite Commercial Activated Carbon (CAC) Perlite Zeolite MSBAC10 pH 3.9 4.5 5.4 3.9 5.0 1.0 Surface Area (m2/g) 197 12 1400 - 1600 N/A 26.5 86.1 CEC  (c mol/kg) 55 8 N/A N/A 72.98 1.51 Solution pH 3.6 3.6 3.6 3.6 3.6 3.6 Conc. (ppm) 500 500 487 487 487 487 Adsorptivity in 5mina (mg/g) 4.81 2.00 2.96 0.58 4.57 4.84 Adsorptivity in 24hrs (mg/g) 4.99b 2.68b 4.91a 1.65a 4.99a 4.94a a the adsorptivity was determined by the author b the adsorptivity was determined by Li and Li (2000). 4.99 2.68 1.65 4.99 4.91 4.94 0123456Grundite Kaolinite Perlite Zeolite CAC MAC10Adsorptivity(mg/g)  Adsorbents (a) 4.81 2.00 0.58 4.57 2.96 4.84 0.001.002.003.004.005.006.00Adsorptivity (mg/g) Adsorbents  (b) 80  4.6.2 Applications of MSBAC10 for the ARD The results of two repeated batch sorption tests by MSBAC10 for acid rock drainage (ARD) from the Britannia Mine were summarized in Table 4.10. The original ARD contained a significant amount of calcium (Ca) ? 347.1 ppm, and heavy metals of aluminum (Al) ? 12.45 ppm, copper (Cu) ? 11.99 ppm and zinc (Zn) ? 16.97 ppm. Since Ca2+ is the dominant cation in the solution, most of MSBAC10 sorption sites were occupied it, which compromised the uptake of the other cations. However, MSBAC10 has a high affinity for Cu2+. After two continuous sorption tests, 98.88% of the Cu2+ was removed, whereas 42.60% removal for Zn2+ and 34.63% for Al3+.  Selectivity of MSBAC10 for multiple-metal species was performed using this ARD as a background solution to provide more realistic information than using synthetic solution with a simple background solution (such as distilled water). Al, Cu, Fe and Zn concentration were prepared in accordance with Lai (2005). The sorption isotherms were plotted and compared with Lai?s results in Figure 4.23 (a) to 4.23 (d). The selectivity of the metals was in the order of Cu2+ >Fe3+ >Zn2+ >Al3+.  The metal removal from multiple-species solutions was affected by the valance of the cations (Cu2+, Zn2+, Fe3+ and Al3+), the hydration energy (Zn2+ > Fe3+ ? Cu2+ > Al3+), the hydrated radius of the cations (6, 6, 9, 9 ? for Cu2+, Zn2+, Fe3+ and Al3+, respectively) and the electronegativity (Cu > Fe > Zn > Al). Since the main sorption mechanism of MSBAC10 was ion exchange with H+ from its surface functional groups, the metal ions with greater electronegativity were more easily attracted by the electrons, which explained MSBAC10?s high affinity for Cu2+.  In addition, comparing with Lai (2005) using clinoptilolite in 24 hours, the maximum adsorptivities in five minutes by MSBAC10 were 113.4% more for Al3+, 13.5% more for Fe3+, 81  433.12% more for Cu2+ and 262.2% less for Zn2+, which demonstrated that MSBAC10 has a stronger and faster metal retention capacity for Al3+, Fe and Cu2+ than clinoptilolite, and is a more ideal adsorbent for multiple-metal solutions. Table 4.10 Metal Concentrations in Untreated ARD and Treated ARD Solution Metals Raw ARD Solution (mg/L) 1st Sorption 2nd Sorption Duplicate #1 (mg/L) Duplicate #2 (mg/L) Average Adsorptivity (mg/g) Duplicate #1 (mg/L) Duplicate #2 (mg/L) Average Adsorptivity (mg/g) Aluminum 12.447 10.137 8.763 0.030 8.350 7.923 0.043 Arsenic N/D* N/D N/D N/D N/D N/D N/D Cadmium 0.069 0.023 0.019 0.000 0.011 0.011 0.001 Calcium 347.144 294.444 265.020 0.674 235.205 230.401 1.143 Copper 11.991 0.614 0.363 0.115 0.189 0.079 0.119 Iron 0.228 0.142 0.122 0.001 0.129 0.120 0.001 Lead 0.286 0.340 0.103 0.001 0.241 0.092 0.001 Manganese 3.471 3.031 2.684 0.006 2.483 2.417 0.010 Nickel 0.035 0.024 0.021 0.000 0.019 0.018 0.000 Zinc 16.971 12.774 10.630 0.053 9.996 9.488 0.072  * N/D = below detection limit 82     Figure 4.23 The Adsorptivity Comparison of the MSBAC10 with Lai?s Results, Data in Duplicate (2005) Using Natural ARD (pH 3.28) as Background Solution in 5 Minutes, n=2, (a) for Al, (b) for Fe, (c) for Cu and (d) for Zn   -2-1.5-1-0.500.510 1000 2000 3000Adsorptivity (mg/g)  Equilibrated Conc. (mg/L) (a) Al y = 0.1333x0.3871 R? = 0.8951 y = 1.0686x0.3732 R? = 0.962 0246810120 500 1000 1500Adsorptivity (mg/g)  Equilibrated Conc. (mg/L) (c) Cu y = 0.3202x0.5068 R? = 0.9735 y = 1.989x0.1542 R? = 0.9694 012345670 200 400 600 800Adsorptivity (mg/g)  Equilibrated Conc. (mg/L) (b) Fe y = 0.0266x0.6371 R? = 0.8393 y = 0.0006x0.9241 R? = 0.3795 00.511.522.533.50 500 1000 1500 2000Adsorptivity (mg/g)  Equilibrated Conc. (mg/L) Zn (d) 83  4.7  Cost Estimation  This cost estimation was based on the 10 batch activation tests (equivalent to 35 g of MSBAC10), the hours of labour needed were list in Table 4.11, and the cost for preparing MSBAC10 was summarized in Table 4.12.  The MSBAC10 was priced at $8.05 /g which was higher than the price of the commercial activated carbon usually priced at $0.002/g. However, in this study, labour cost was the major cost in the carbon preparation, which could have been largely reduced by using an industrial scale furnace with larger capacity to produce more SBAC within the same amount of time. Also, the savings from sludge disposal could also compensate this unit cost of MSBAC10. Since information about the industrial furnace is insufficient, industrializing the preparation of MSBAC10 requires further investigation and verification.  Table 4.11 Labour Hours for Preparing MSBAC10 Based on 10 Batch Tests Labour Required Time for Single Experiment (in hrs) Factor Time for 10 Batch Experiments (in hrs) Sludge Dewater 0.25 10 2.5 Grinding 0.5 1 0.5 Preparation before Activation 0.5 10 5 Activation (manually controlling the temperature) 0.67 10 6.7 Washing after Activation 1.75 1 1.75 Grinding after Washing 0.5 1 0.5 Modification 1 1 1 Total Labour Hours 5.17  17.95   84  Table 4.12 Cost Estimations for the Preparation of MSBAC10 Parameters Rate Time (hrs) Cost (in CAD Dollar) Total Energy Used = 1500 W (only an electronic furnace) $0.0961 per KWh1 24.2 2.33 Material Costs (nitrogen gas, ZnCl2, and nitric acid)   10.00 Labour $15/hour2 17.95 269.25 Total Cost for 35 grams of MSBAC10   281.58 Cost per Gram of MSBAC10   $8.05/g 1Based on large general service conservation rates from BC hydro 2Based on the rates of the UBC Work Learn Program85  Chapter 5: CONCLUSIONS AND RECOMMENDATIONS 5.1  Conclusions  5.1.1 The Characteristics of Converted and Modified Activated Carbon The key findings from the analyses of the carbonized sludge (CS), sewage sludge-based activated carbon (SBAC), and modified SBACs are summarized as follows:  ? The sewage sludge was successfully converted into activated carbon by pyrolysis at 500?C for 2 hours with 10?C/ min heating rate both with and without chemical activation by ZnCl2.  ? The conversion rate (percentage yield) of the CS was approximately 36.5%, similar to that of the conversion rate of SBAC.  ? The SBAC with the chemical activation of ZnCl2 exhibited a dramatic increase in specific surface area compared to that of CS. ? Total carbon content of CS and SBAC was significantly increased after conversion, but was slightly reduced after modification.   ? The modification of SBAC with nitric acid was effective in terms of Pb2+ sorption capacity.  ? Although the specific surface area was significantly reduced after modification, the effectiveness of the modification was enhanced by increasing the modification temperature and dosage (at acid to material ratio), which was highly likely due to more carboxyl groups (R-COO-) produced after modification. 86  5.1.2 Heavy Metal Sorption Characteristics of the Sludge Based-Adsorbents  ? The SBAC and MSBACs (MSBAC0, MSBAC4 and MSBAC10) had fast adsorption processes within 5 minutes comparing to 80 minutes by CS.  ? Among the prepared carbons in this study, MSBAC10 had the highest adsorptivities regardless of the solution concentration. It had over 96% removal efficiency within 5 minutes at low concentration range from 100 ppm to 200 ppm.  ? The data from the sorption isotherms of CS, SBAC, MSBAC0, MSBAC4 and MSBAC10 exhibited a good fit for the Langmuir isotherm model.  ? Compared with the other adsorbents, MSBAC10 exhibited the strongest and fastest sorption behavior, and the adsorptivity of lead in five minutes was ranked as: MSBAC10 > illite (grundite) > zeolite > CAC > kaolinite > perlite.  ? As for the application of MSBAC10 to the ARD solution, 98.88% of Cu in the natural ARD was removed by MSBAC10, followed by 42.60% of Zn and 34.63% of Al.  ? Compared with Lai (2005) using clinoptilolite for adsorbing ARD solution spiked with multiple metals in a 24-hour period, MSBAC10 had a stronger and faster metal retention capacity than clinoptilolite, and was a more ideal adsorbent. To summarize, the sewage sludge can be converted to a useful adsorbent, and the modification of the SBAC by nitric acid was effective to improve the lead sorption.    87  5.2  Recommendations and Further Experiments  ? The exhaust gas should be collected to avoid the air pollution, and the chemical compounds in it from the conversion process should be analyzed and measured for its concentration.  ? It is suggested to study the potential application for removal effectiveness of the emerging contaminants (such as PFCs, PCB, and PBDE) from the sewage sludge after the conversion steps.  ? The potential of giving off NO2 from the nitric acid treatment is undesired. More comprehensive studies are needed for the modification parameters (temperature, soaking time, acid concentration, and dosage) to minimize the NO2 pollution.  ? Acid/base titration tests are recommended for determining the amount of surface functional groups on the MSBACs to better understand the modification mechanisms.  ? Due to the large BET surface area, the effectiveness of SBAC can be tested by adsorbing other organic contaminants (i.e. VOCs and phenol), and emerging contaminants (i.e. PFCs, PCB, and PBDE).   ? The cost of the preparation was only based on very small-scale experiments. A large-scale test is recommended if larger scale test equipment is allowed (e.g. a larger furnace with a closed inert atmosphere for carbonization).    88  REFERENCES American Public health Association (APHA), American Water Works Association (AWWA), & Water Environment Federation (WEF). (2005). Standard methods for the examination of water and wastewater. Washington, DC.  Agriculture Canada, (1984). Analytical methods manual. Land Resource Research Institute, Ottawa, Ontario.   Anfruns, A., Martin, M.J., Montes-Mor?n, M.A., (2011). Removal of odorous VOCs using sludge-based adsorbents. Chemical Engineering Journal, 166, 1022-1031.   Bansal, R.C., Donnet, J., Stoeckli, F. (1988). Active carbon (pp. 8-13). New York, NY: Marcel Dekker.   Bansal, R.C., Goyal, M. (2005). Activated carbon sorption (pp. 2-10). Boca Raton, FL: Taylor & Francis Group.     Beeckmans, J.M, Ng, P.C. (1971). Pyrolyzed sewage sludge, its production and possible utility. Environmental Science & Technology, 5 (1), 69-72.   Brunauer, S., Emmett, P.H., Teller, E. (1938). Sorption of gases in multimolecular layers Journal of the American Chemical Society, 60 (2), 309-319.   Buberoglu, B., Duguay, L. (2004). Biosolids Management Program. Twentieth Conference of Canadian Association on Water Quality, Ottawa.  Catural, F., Molina-Sabio, M., Rodriguez-Reinoso, F. (1991). Preparation of activated carbon by chemical activation with ZnCl2. Carbon, 29, 999-1007.  Chen, X., Jeyaseelan, S., Graham, N. (2002). Physical and chemical properties study of the activated carbon made form sewage sludge. Waste Management, 22 (7), 755-760.   Chen, J.P., Wu, S.N., Chong, K.H. (2003). Surface modification of a granular activated carbon by citric acid for enhancement of copper sorption. Carbon, 41, 1976-1986.   Dowdy, R. H. and W. E. Larson, and Epstein, E. 1976. ?Sewage sludge and effluent use in agriculture.? in land application of waste materials, pp. 138-53. Ankeny, Iowa: Soli Conservation Society of America.   EI-Hendawy A.N.A, (2005) Surface and Adsorptive Properties of Carbons Prepared from Biomass. Applied Surface Science, 252, 287-295.   EpH ? Web. (2013). Lead speciation diagram calculated using EpH-web. Retrieved from http://www.crct.polymtl.ca/ephweb.php/ [Accessed March 19, 2013].   89  Fang, P., Cen, C., Chen, D., Tang, Z. (2010). Carbonaceous adsorbents prepared from sewage sludge and its application for Hg0 sorption in simulated flue gas. Chinese Journal of Chemical Engineering, 18 (2), 231-238.  Fitzmorris, K.B., Lima, I.M., Marshall, W.E., Reimers, R.S. (2006). Anion and cation leaching or desorption from activated carbon from municipal sludge and poultry manure as affected by pH. Water Environment Resource, 78, 2324-2329.   Fyfe, W.S. (1964). Geochemistry of solids: an introduction (pp. 189). New York, NY: McGraw-Hill.  Hsu, L., Teng, H. (2000). Influence of different chemical reagents on the preparation of activated carbons from bituminous coal. Fuel Processing Technology, 64 (1-3), 155-166.  Hu, Z.H., Vansant, E.F. (1995). Synthesis and characterization of a controlled - microspore - size carbonaceous adsorbent produced from walnut shell. Microporous Materials, 2, 603-612.   Jiang, Z.W., Kai, K., Xu, X.M., Zhang, Y.L., Wang, X.J. (2010). The preparation of sludge ? based activated carbon and its physical and chemical characteristics. Advanced Material Research, 146, 1631-1637.   Kargbo, D. M. (2010). Biodiesel production from municipal sewage sludge. Energy Fuels, 24, 2791-2794.   Kemmer, F.N., Robertson, S.R., Mattix, R.D. (1971). Sewage Treatment Process. Nalco Chemical Company. US patent Office, Patent No. 3,619,420.   Lai, R.W.M., (2005). The use of clinoptilolite as permeable reactive barrier substrate for acid rock drainage (Doctoral Thesis). Retrieved from https://circle.ubc.ca/  LeBlanc, R.J., Allain, C.J., Laughton, P.J., Henry, J.G., (2004). Integrated, long term, sustainable, cost effective biosolids management at a large Canadian wastewater treatment facility. Water Science and Technology, 49 (10), 155-162.   Lillo-Rodenas, M.A., Ros, A., Fuente, E., Montes-Moran, M.A., Martin, M.J., Linares-Solano, A. (2008). Further insights into the activation process of sewage sludge-based precursors by alkaline hydroxides, Chemical Engineering Journal, 142 (2), 168-174.  Li, L.Y., Li, R.S. (2000). The role of clay minerals and the effect of H+ ions on removal of heavy metal (pb2+) from contaminated soils. Canadian Geotechnical Journal, 37 (2), 296-307.   Ma, S. Y., Tang, J.G., Chen, B.L. (2006). Sludge disposal and utilization in EU. China Water and Wastewater, 22 (4), 102-105.   90  Martin, M.J., Balaguer, M. D., Rigola, M. (1996). Feasibility of activated carbon production from biological sludge by chemical activation with ZnCl2 and H2SO4. Environmental Technology, 17, 6, 667 ? 671.  Martin, M.J., Artola, A., Balaguer, M.D., Rigola, M. (2002). Towards waste minimisation in WWTP: activated carbon from biological sludge and its application in liquid phase sorption. Journal of Chemical Technology and Biotechnology, 77 (7), 825-833.  McDougall, G.J. (1991).The physical natural and manufacture of activated carbon. J.S. Afr. Inst. Min. Metall., 91 (4), 109-120.  Metro Vancouver. (2005). Percentage of trace elements in biosolids from the annacis island WWTP. Retrieved from http://www.metrovancouver.org/services/wastewater/biosolids/ [Accessed March 19, 2013].  Monsalvo, V.M., Mohedano, A.F., Rodriguez, J.J. (2011). Activated carbons from sewage sludge application to aqueous-phase sorption of 4-chlorophenol. Desalination, 277, 377-382.   Orlov, D.S. (1992). Soil Chemistry (pp. 90). Rotterdam, Brookfield: A.A. Balkema.  Ros, A., Lillo-Rodenas, M.A., Fuente, E., Montes-Moran, M.A., Martin, M.J., Linares-Solano, A. (2006). High surface area materials prepared from sewage sludge-based precursors. Chemosphere, 65, 132-140.  Razouk, R.I., EI-Inancy, G.A., Fahim, R.D., Mikhail, R.S. (1960). The adsorptive properties of carbonized agricultural wastes. Journal of Chemistry of the U.A.R., 1, 11-22.    Seredych, M., Bandosz, T.J. (2006). Removal of copper on composite sewage sludge/industrial sludge ? based adsorbents, the role of surface chemistry. Journal of Colloid and Interface Science, 302 (2), 379-388.  Shafeeyan, M.S., Wan Daud, W.M.A., Houshmand, A., Shamiri, A. (2010). A review on surface modification of activated carbon for carbon dioxide sorption. Journal of Analytical and Applied Pyrolysis, 89, 143-151.    Shen, W.Z., Li, Z.J., Liu, Y.H. (2008). Surface chemical functional groups modification of porous carbon. Chemical Engineering, 1, 27-40.   Smith, K.M., Fowler, G.D., Pullket, S.P., Graham, N.J.D. (2009). Sewage sludge-based adsorbents, a review of their production, properties and use in water treatment applications. Water Research, 43, 2569-2594.   Song, X., Liu, H., Cheng, L., Qu, Y. (2010). Surface modification of coconut ? based activated carbon by liquid ? phase oxidation and its effects on lead ion sorption. Desalination, 255, 78-83. 91   Tavares, D.S., Lopes, C.B., Coelho, J.P., S?nchez, M.E., Garcia, A.I., Otero, D.M., Pereira, E. (2012). Removal of arsenic from aqueous solutions by sorption onto sewage sludge-based sorbent. Water Air Soil Pollute, 223, 2311-2321.   Tay, J.H., Chen, X.G., Jeyaseelan, S., Graham, N. (2001). Optimising the preparation of activated carbon from digested sewage sludge and coconut husk. Chemosphere, 44, 45-51.  Yang, L., Wu, S.N., Chen, J.P., (2007). Modification of activated carbon by polyaniline for enhanced sorption of aqueous arsenate. Industrial & Engineering Chemistry Research, 46, 2133-2140.  Ye,F., Li, Y. (2010). Oxic-settling ?anoxic (OSA) process combined with 3, 3?, 4?5-tetrachlorosalicylanilide (TCS) to reduce excess sludge production in the activated sludge system. Biochemical Engineering Journal, 49, 229-234.  Yu, L., Zhong, Q. (2006). Preparation of adsorbents made from sewage sludge for sorption of organic materials from wastewater. Journal of Hazardous Materials, 137 (1), 359-366.   Wang, X.N., Zhu, N.W., Yin, B.K. (2007). Preparation of sludge ? based activated carbon and its application in dye wastewater treatment. Journal of Hazardous Materials, 153, 22-27.   Wen, Q., Li, C., Cai, Z., Zhang, W., Gao, H., Chen, L., Zeng, G., Shu, X., Zhao, Y. (2011). Study on activated carbon derived from sewage sludge for sorption of gaseous formaldehyde. Journal of Bioresource Technology, 942-947.  Zhang, F.S., Ntiagu, J.O., Itoh, H. (2005). Mercury removal from water using activated carbons derived from organic sewage sludge. Water Research, 39 (2-3), 389-395.   92  APPENDICES   Appendix A Detail Experimental Procedures   93  A.1 Sludge Characterization  A.1.1 Sludge Sampling and Preparation  The raw sludge was collected from aerobic zone of bioreactors at the University of British Columbia (UBC) Wastewater Treatment Pilot Plant. Total 240 L of sludge was collected in three following days since the maximum volume can be collected was 80 L each day. The pH of the sludge was measured during the sampling by pH probe, and recorded. All the sludge was collected in polypropylene test containers and immediately transported by vehicle to the UBC environmental lab.  All the sludge then was stored at 4?C, and centrifuged at 3000 rpm for 3 min to remove the most of the water at the same day. After drying in an oven with 105?C for 48 hours, all the dried sludge was blended to powders and stored in an amber glass bottle for future experiments.  A.1.2 Total Solids and Volatile Solids of Sludge (TS/VS)  Four ceramic dishes were cleaned with distilled water and dried in an oven at 105?C for 1 hr. After cooled to the room temperature in a desiccator, they were weighed at room temperature on an analytical balance, and the weight of each dish was recorded. The sludge was thoroughly mixed before being transferred into dishes and mass of the sludge with dish was measured and recorded. The sampled dishes were then dried in a 105?C oven for 24 hours, and they were placed in a desiccator to cool to the room temperature. Then the dishes were weighed again on an analytical balance, and recorded the weight.  After that they were put into a muffle furnace at a temperature of 550?C for 2 hr. The weights of the dishes were measured at the room temperature after burning.  94  A.1.3 Stability Test for Dissolved Metals and Total Metals by Acid Digestion  0.5 g of sludge was mixed with 20 mL of distilled water at pH 3 in a 50 mL polypropylene tube. The tube was put in an end-to-end rotator to make sure the fully contact of the sludge with distilled water. After 24 hours, the solution was filtered through 0.45 ?m filtering paper, and the filtrate was collected for an ICP?MS analysis to determine the metal concentration leached out from the sludge.   0.5 g of sludge was fully digested by 5 M nitric acid. After evaporating all the acid, the residuals were diluted with distilled water to 50 mL solution and filtered through 0.45 ?m filtering paper. The filtrate was analysed by Inductively Coupled Plasma-Mass Spectrometry (ICP?MS), Optical Emission Spectrometer Optimal 7300 DV manufactured by PerkinElmer to determine the concentrations of metal ions in the sludge.     95  A.2 Preparation and Characterization of Carbonized Sludge A.2.1 Preparation of Carbonized Sludge The furnace tube was cleaned by distilled water and dried in an oven at 105?C. Quartz wool was placed into the bottom of the tube (smaller diameter) to block the sample while allowing the nitrogen gas to go through during the conversion. The dried sludge was then poured into the tube with the injection of N2 gas from the bottom for at least 10 minutes at 10 mL/min to ensure an inert atmosphere inside the tube.  The furnace was then turned on and the temperature was first set to 100?C. After reaching 100?C, the temperature was further increased manually to 500?C at the rate of 10?C/min, and maintained at 500?C for two hours. After the sample was cooled to room temperature, it was ground into 250 ?m powders and stored in a capped amber glass for further batch sorption tests. The CS from each conversion was stored in the same bottle and homogenized by mixing before sorption tests. A.2.2Characterization of Carbonized Sludge (CS) A.2.2.1 Yield Percentage The weight of raw sludge was measured before being placed into the furnace tube. After the conversion was completed, carbonized sludge was removed from the tube and weighted. The yield percentage was calculated dividing the weight of raw sludge by the weight of CS. Total 10 batches were conducted to calculate this value. Sample Calculation: Yield % =  (       ?       )        X 100 % Where Wbefore is Weight of the dry sludge, Wafter is Weight of the CS after conversion.  96  A.2.2.2 pH  5 g of SBAC was weighted and added to a 10 mL beaker with 20 mL of 0.01 M CaCl2 solution. The solution was continuously stirred for 5 minutes. Let the suspension stand for 1 hour and filter off the solution for pH measurement.  A.2.2.3 Stability Test for Dissolved Metals  The leachate of CS was determined by the same procedures in A.1.3.  A.2.2.4 BET Specific Surface Area  0.05 g of CS was used for determining the specific surface area by FlowSorb II 2300 surface analyzer manufactured by Micromeritics. The degassing tube was carefully removed from the analyzer and weighed. All the CSs then were poured into the bottom of the tube, and the degassing tube was placed back to the analyzer and covered with electrical thermal conductor to heat up to 250?C for 24 hours to remove the moisture in the sample.  After 24 hours, the conductor tube was cooled to the room temperature, and removed from the analyzer to measure the weight again. After that, removed the tube in the ?Test? session, and quickly replaced it with the degased tube since the ?Test? session always need to be plugged with a tube to avoid the air going into the analyzer which may cause the change of N2 gas flow rate of the equipment. Pressed the clear button and waited until the DET reading is stable. Switched the reading to specific area (SA) and immersed the glass part of the tube with liquid nitrogen. When the reading of SA was stable, recorded the value (sorption value) and removed the liquid nitrogen from the tube. Then pressed the clear button again, switched to the DET reading and waited until the reading was zero.  97  A.3 Preparation and Characterization of SBAC A.3.1 Preparation of SBAC Approximate 10 g dried sludge was used for preparing SBAC in each batch experiment. 170.368 g of ZnCl2 powder were added to 250 mL of volumetric flask to prepare 5 M ZnCl2 solution. When the solution was diluted, the heat generated from the dissolving of ZnCl2 would make the flask expand. Therefore, the final dilution was performed after the solution went back to room temperature in order to have the correct concentration.  10 mL of ZnCl2 was used to soak 10 g of raw sludge for 24 hours and the mixture was placed in an oven at 105?C for 24 hours. The carbonization procedure was the same as the procedures in A.2.1. After carbonization, the material was grinded into 250 ?m, and with 3 times washes with 5 M HCl and 6 times with distilled water. The solid-to-solution ratios were 1 g to 2 mL and 1 g to 20 mL for HCl and distilled water respectively. Each washing period was kept at least 15 minutes, and the solution was vacuum filtered through a 0.45 ?m filter paper. The filtrates were collected and diluted for the ICP-MS test. The washed SBAC then was dried in an oven at 105?C and stored in a capped amber glass bottle.   98  A.3.2 Characterization of SBAC A.3.2.1 Yield Percentage 10 g sludge was used for each batch conversion of SBAC. The yield percentage was determined by measure the weight of SBAC after washing and drying. The value was calculated by the ratio between the weight of final SBAC and 10 g of raw sludge.  Sample Calculation: Yield % =  (       ?       )        X 100 % Where Wbefore is weight of the dry sludge before ZnCl2 treatment, and Wafter is the weight of the SBAC after washing and drying  A.3.2.2 pH  The same procedures in A.2.2.2 were used for determining the pH of the SBAC.   A.3.2.3 Stability Tests for Dissolved Metals  The metal concentration was not measured for SBAC since it was hard to be digestted by nitric acid. The metal concentration in the leachate of SBAC was determined by the same procedures in A.1.3.  A.3.2.4 BET Specific Surface Area   The same procedures in A.2.2.4 were repeated for determining specific surface area of SBAC.    99  A.4 Modification of SBAC and Characterization of MSBACs A.4.1 Modification of SBAC  10 M of nitric acid (HNO3) was prepared by adding 640 mL of concentrated nitric acid (HNO3) to 360 mL of distilled water in a 1000 mL beaker. The dilution and later modification must be done inside the fume hood due to evaporation of the nitrite and nitrate. After thoroughly mixing the acid with distilled water together and waiting for the solution to cool down to the room temperature, the solution was stored in a plastic bottle. SBAC was mixed with 10 M nitric acid at 1 g to 4 mL ratio in a flask. The flask was shaken gently to make sure all the SBAC being contacted with the acid. The reaction was carried on for 4 hours at the room temperature, and the modified SBAC was noted as MSBAC0.  Similar to MSBAC0, MSBAC4 was prepared by mixing SBAC with 10 M nitric acid at 1 g to 4 mL ratio for 4 hours but the flask was immersed in a water bath with the temperature of 90?C during the mixing. After 4 hours, the mixture was filtered through a 0.45 ?m vacuum filter, the modified SBAC was removed from the filter paper to a crucible and dried in a 105?C oven. All the procedures above were performed inside the fume hood. The filtrate was collected, and neutralized with the Na2CO3 before dumping into the sewer. After 24 hours, dry modified SBACs were cooled to the room temperature and store in an amber glass bottle for the testing. Since the SBAC to nitric acid ratio was 1 g to 4 mL, the modified SBAC was noted as MSBAC4.   As for MSBAC10, the SBAC to nitric acid ratio was changed to 1 g to 10 mL in order to look at the volume effect of the nitric acid. All the procedures for MSBAC4 were repeated for preparing the MSBAC10.   100  All the MSBACs were washed extensively with distilled water until the pH of after washing solution close to 5 (the pH of the used distilled water). The weight of each kind of MSBACs was measured after washing.  A.4.2 Characterizations of MSBAC0, MSBAC4 and MSBAC10 A.4.2.1 pH  The same procedures in A.2.2.2 were repeated for determining the pH of MSBAC0, MSBAC4 and MSBAC10.     A.4.2.2 Leachability Test and Metal Concentration  The metal concentration in the MSBACs was not measured since they were hard to be digestted by nitric acid. The metal concentrations in the leachates of MSBAC0, MSBAC4 and MSBAC10 were determined by the same procedures in A.1.4.  A.4.2.3 BET Specific Surface Area  The same procedures in A.2.2.5 were repeated for determining specific surface areas of MSBAC0, MSBAC4 and MSBAC10.     101     Appendix B Batch Sorption Tests and Methods Supplement    102  B.1 Batch Sorption Test of CS  B.1.1 Sorption Kinetics  The sorption kinetics was created by determining the adsorptivity of lead with different sorption durations: 5, 10, 20, 40, 80, 160, 720 and 1440 min. Distilled water was used as background solution and adjusted to pH 3 by nitric acid. 100 ppm lead solution was prepared by dissolving lead nitrite in an l liter volumetric flask. The solid to solution ratio was 1g of activated carbon to 40 mL of the spiked solution. Duplicate samples were employed for each sorption period.  All the polypropylene tubes with samples were put into an end-to-end rotator for sorption tests. After each sorption period, two samples were filtered through a 0.45 ?m vacuum filter, and the filtrates were stored in polypropylene test tubes. After 24 hours until all the samples were filtered, the all the filtrates were diluted 10 times with distilled water for the atomic absorption spectrometry (AAS) test. The calibration curve was created by standard lead solution with three different concentrations 10, 20, 30 ppm. The 1000 ppm lead nitrite standard solution from SPEX CertiPrep was used to prepare the lead standard solution. 2.5, 5 and 7.5 mL of 1000 ppm lead standard solution were pipetted to three labelled 250 mL volumetric flasks, and diluted to 250 mL with distilled water.  B.1.2 Metal Sorption Isotherm  The sorption time was chose as 80 min based on the previous kinetics test. The concentrations were designed as 5, 10, 20, 50, 100 ppm of lead ion. pH effect was studied by using solutions with three different pHs of 3, 5, and 7.  Distilled water was used for preparing metal solutions and its pH was adjusted with 0.1 M nitric acid to corresponding pH value. 1.5985g of lead nitrite powder were diluted with 103  distilled water in a 100 mL volumetric flask, and its pH was adjusted by 0.1 M nitric acid. The solution was then diluted with the distilled water having the corresponding pH value in a 1 L volumetric flask. All the other concentrations were prepared from this mother solution. 0.5, 1, 2, 5 and 10 mL of the mother solutions were pipetted to five labelled 100 mL volumetric flasks, and diluted to 100mL with adjusted distilled water to get 5, 10, 20, 50, 100 ppm of lead ion solutions.  The solid-to-liquid ratio was also design to be 1 g to 40 mL of the spiked solution. Triplicate samples were used for each different concentration. Duplicate samples were used for each concentration.  After preparing all the samples, all the polypropylene tests tubes were put into an end-to-end rotator. After 80 min, all samples were filtered through 0.45 ?m filter paper, and the filtrates solution were analysed for Pb2+ concentration by AAS (SpectrAA, 220 fast sequential).    104  B.2 Batch Sorption Test of SBAC for Lead  The batch sorption tests were conducted for determining the kinetics of lead sorption by SBAC. The pH was chosen as 3.  B.2.1 Sorption Kinetics  The sorption time of SBAC was decided by the same procedures in B.1.1. B.2.2 Metal Sorption Isotherm  The sorption time was chose as 5 min based on the SBAC kinetics test. The Pb2+ concentrations were designed as 100, 200, 500, 800 and 1000 ppm. The solid-to-liquid ratio was 1 g to 40 mL. Duplicate samples were used for each different concentration.  After preparing all the samples in the polypropylene tests tubes, they were put into an end-to-end rotator for 5 minutes. After that, all samples were s filtered through 0.45 ?m vacuum filter, and the filtrates were analysed for Pb concentration by atomic absorption spectrometer (SpectrAA, 220 fast sequential).  B.3 Batch Sorption Test of MSBACs (MSBAC0, MSBAC4 and MSBAC10) The batch sorption tests were conducted to determine the adsorptivity of MSBAC0, MSBAC4 and MSBAC10 for Pb2+. The pH of the solution was adjusted to 3. Sorption kinetics and isotherms tests were also conducted to study the sorption behaviours of MSBACs. Finally the reusability of MSBAC10 for Pb2+ was determined by repeated batch sorption tests.  B.3.1 Sorption Kinetics   The same procedures in B.1.1 were repeated for determining the sorption kinetics of MSBAC0, MSBAC4 and MSBAC10.  105  B.3.2 Metal Sorption Isotherm  The contact time for determining sorption isotherm was chosen as 5 min for MSBACs based on the kinetics tests. The concentrations were designed as 100, 200, 500, 800 and 1000 ppm of Pb2+.  The solid-to-liquid ratio was also designed to be 1 g: 40 ml with duplicated samples at each concentration.  After spiking all the samples with each solution with different concentrations, all the polypropylene tests tubes were put into an end-to-end rotator for 5 minutes. All samples were then filtered through 0.45 ?m vacuum filters, and the filtrates were analysed for Pb2+ concentration by AAS (SpectrAA, 220 fast sequential).  B.3.3 Repeated Batch Sorption Test for MSBAC10  Duplicate samples were employed for determining the maximum adsorptivity of MSBAC10. 0.5 g of MSBAC10 was added into 20 mL of 100 ppm Pb2+ solution. The tubes containing the solution and sample were placed in an end-to-end rotator for 5 minutes, and the mixture was filtered through a 0.45 ?m filtering paper. The filtrate was collected and stored in a refrigerator at 4?C. The used MSBAC10 was recycled from the filter paper for a second sorption test with the same test condition and procedures in the previous one. Total 10 repeated sorption tests were performed. 10 individual filtrates were collected for single 0.5 g of CS, and 20 filtrates were performed in the end due to the duplicated samples to make sure the accuracy. The filtrate were analysed for Pb concentration by atomic absorption spectrometer to measure the adsorbed lead amount for each sorption test.   106  B.4 Sorption Tests for Pb2+ with Selected Adsorbents Two sorption durations of five minutes and 24 hours were employed with 500 ppm designed Pb2+ concentration. Kaolinite, illite, perlite, zeolite and CAC were compared with MSBAC10 by conducting batch sorption tests for lead ions. The solution pH was adjusted to 3.6 by 0.02 M nitric acid, and the solid-to-liquid was 1 g to 10 mL. Duplicated samples were used for each adsorbent.  After all the adsorbents were spiked with 500 ppm lead solution in polypropylene tests tubes, they were put into an end-to-end rotator. After 5 min or 24 hours contact time, the samples were filtered through 0.45 ?m filtering papers, and the filtrates were analysed for Pb2+ concentration by atomic absorption spectrometer (SpectrAA, 220 fast sequential).    107  B.5 Cation Exchange Capacity for Different Adsorbents Materials  B.5.1Apparatus and Reagents Lists  ? 125 mL Erlenmeyer flasks  ? Reciprocating shaker  ? Pipettes and disposable tips ? Ammonium acetate  ? Ammonium hydroxide  ? Acetic acid  ? Certified atomic absorption standards for Ca2+, K+ and Mg2+ from Fisher Scientific  ? Atomic absorption spectrometer (SpectrAA, 220 fast sequential).  B.5.2 Procedures  ? Sieved the material through a 100 ?m sieve. ? Weighed 77.1 g of ammonium acetate and diluted them to 1 liter in a volumetric flask with distilled water to make 1.0 N ammonium acetate solution. Adjusted the solution pH to 7.0 with Ammonium hydroxide or acetic acid.   ? Prepare 40,000 ppm of La3+ solution by adding 106.87 g of lanthanum chloride heptahydrate into 1 L volumetric flask and diluting with distilled water. ? Weighed 1 g of air dry material into a 50 mL polypropylene tube and added 10 mL of 1.0 N NH4OAc to the material.  ? Stopper the tube and put in an end-to-end rotator for 30 minutes.  ? Filter the extract through 0.45 ?m filter paper and save the filtrate in a polypropylene tube. ? Dilute the filtrate 40 times with distilled water containing 2000 ppm Lanthanum. 108  ? Collect the data for concentrations of extractable Ca2+, Mg2+, K+, and Na+ from AAS tests.   B.5.3 Sample Calculations  Exchangeable cations in meq/100 g =                                                                               (  )                     ( )  CEC = Exchangeable Ca + Exchangeable K + Exchangeable Mg + Exchangeable Na    109     Appendix C Experimental Data and Figures   110  C.1 Material Characterizations  C.1.1 Total Solids and Volatile Solids of Sludge Table C.1 Total Solid and Volatile Solid of Raw Sludge Sample ID Dish (g) Dish + Sludge (g) Dried Burned at (550 ?C) TS (%) VS (%) VS/TS (%) 1 63.8459 79.5798 63.9181 63.8537 0.46 0.41 89.20 2 69.3082 79.8192 69.3567 69.3152 0.46 0.39 85.57 3 48.6001 78.1975 48.7386 48.6237 0.47 0.39 82.96 4 1.0741 23.4701 1.1792 1.0962 0.47 0.37 78.97  C.1.2 Total Carbon, Nitrogen and Hydrogen Content of the Materials Table C.2 Data for Calculating Material Carbon Content Material Total Carbon % Total Nitrogen % Total Hydrogen % RS 38.6 7.6 6.05 CS 44.29 6.01 1.98 SBAC 61.68 6.38 3.54 MSBAC0 62.05 7.65 2.9 MSBAC4 60.51 7.73 2.28 MSBAC10 52.29 7.68 2.46     111  C.1.3 Specific Surface Area BET Date and Calculation  Table C.3 BET Surface Area Data for Sludge Based Adsorbents Adsorbents* Mass of Empty tube (g) Empty tube + sample (after degassing) (g) Sample Mass (g) BET Reading (m2) BET surface area (m2/g) RS 135.6349 135.8310 0.1961 3.89 19.84 CS 136.5276 136.5324 0.0048 0.97 202.08 SBAC 136.5598 136.5834 0.0236 17.02 721.19 MSBAC0 135.7507 135.7780 0.0273 18.42 674.73 MSBAC4 137.4573 137.5389 0.0816 17.51 214.58 MSBAC10 135.7507 135.7702 0.0195 1.68 86.15 *  RS = Raw Sludge   CS = Carbonized Sludge   SBAC = sludge based activated carbon   MSBAC0 = SBAC impregnated with 10M HNO3 (1 g to 4 mL) at 20?C for 4 hours   MSBAC4 = SBAC impregnated with 10M HNO3 (1 g to 4 mL) at 90?C for 4 hours   MSBAC10 = SBAC impregnated with 10M HNO3 (1 g to 10 mL) at 90?C for 4 hours  Sample Calculation: BET surface area (m2/g) = BET reading (m2) / Sample Mass (g)     112  C.1.4 Cation Exchange Capacity for Adsorbents Table C.4 Metal Concentrations from ICP Analyzer for Determining CEC of Adsrobents  Ca (ppm) K (ppm) Mg (ppm) Na (ppm) Ca (meq/100) K (meq/100) Mg  (meq/100) Na (meq/100) CEC (meq/100) RS 4.3 62.032 25.43 14.497 4.3 31.811 42.383 12.605 91.100 CS 0.909 4.450 0.694 0.686 0.909 2.282 1.157 0.596 4.944 SBAC 0.849 1.533 0.29 0.160 0.849 0.786 0.483 0.139 2.258 MSBAC0 0.553 1.308 0.12 0.222 0.553 0.671 0.200 0.193 1.617 MSBAC4 0.826 1.253 0.029 0.000 0.826 0.642 0.048 0.000 1.517 MSBAC10 0.626 1.268 0.033 0.076 0.626 0.650 0.055 0.066 1.398 Perlite 1.906 1.284 0.148 0.255 1.906 0.659 0.247 0.222 3.033 Zeolite 20.37 85.610 0.573 8.918 20.370 43.903 0.955 7.755 72.982 113  C.1.5 Total Metal Digestion for Raw Sludge (RS) and Dissolved Metal Concentrations of RS, CS and SBAC  Table C.5 Metal Concentration of RS Digestion by Nitric Acid Analysed Metals ICP Results (mg/L) Concentration (mg/g) Ag N/D1 N/D Al 18.89 4.68 As N/D N/D Ba 0.86 0.21 Be N/D N/D Ca 94.23 23.36 Cd N/D N/D Co 0.017 0.004 Cr 0.153 0.038 Cu 5.726 1.419 Fe 53.974 13.380 K 96.423 23.903 Mg 73.296 18.170 Mn 1.407 0.349 Mo 0.080 0.020 Na 24.747 6.135 Ni 0.113 0.028 Pb 0.19 0.05 Sb N/D N/D Se 0.16 0.04 Sn 0.04 0.01 Sr 0.43 0.11 Zn 6.58 1.63 ND = Below Detection Limit      114  Table C.6 Dissolved Metal Concentration in Leachates of the CS and SBAC following 24 Hours in Distilled Water at pH of 3 with 1 g to 40 mL ratio Analysed Metals RS (mg/L) CS (mg/L) SBAC (mg/L) Ag ND ND ND Al 0.339 3.001 1.645 As ND ND 0.013 Ba 0.007 0.073 0.015 Be 0.007 0.007 0.007 Ca 30.435 10.641 0.813 Cd 0.007 0.007 0.009 Co 0.018 0.008 0.015 Cr 0.023 0.017 0.014 Cu 1.998 0.145 0.331 Fe 0.958 13.193 0.183 K 241.141 63.790 1.007 Mg 73.776 15.680 0.465 Mn 0.154 0.192 0.016 Mo 0.016 0.010 0.006 Na 83.508 18.923 0.805 Ni 0.210 0.016 0.040 Pb 0.516 0.309 0.632 Sb 0.011 0.010 0.025 Se 0.045 0.011 0.026 Sn 0.024 0.042 0.015 Sr 0.042 0.051 0.011 Zn 0.908 28.370 ND ND = Below Detection Limit 115  C.1.6 X-Ray Diffractograms of CS and SBAC from Semi-quantitative Analysis    Figure C.1 Rietveld Refinement Plot of CS (blue line - observed intensity at each step; red line - calculated pattern; solid grey line below ? difference between observed and calculated intensities; vertical bars - positions of all Bragg reflections).  Note: Coloured lines are individual diffraction patterns of all phases 2Th Degrees807570656055504540353025201510Counts6,0004,0002,000014WX_CS-XuDong.raw_1 Gehlenite 29.38 %Calcite 4.62 %Calcite, magnesian 4.86 %Crandallite H 11.07 %Albite low, calcian 23.68 %Quartz low 12.32 %Monetite low 9.94 %Magnesite 4.12 %116   Figure C.2 Rietveld Refinement Plot of SBAC (blue line - observed intensity at each step; red line - calculated pattern; solid grey line below ?  difference between observed and calculated intensities; vertical bars - positions of all Bragg re reflections).  Note: Coloured lines are individual diffraction patterns of all phases 2Th Degrees807570656055504540353025201510Counts14,00012,00010,0008,0006,0004,0002,000015WX_SBAC-XuDong.raw_1 Quartz low 26.98 %Rutile 21.76 %Albite low 37.62 %Anatase 6.17 %Talc 1A? 7.47 %117  C.1.7 Surface Function Group for Adsorbents   Figure C.3 FTIR Spectrum of CS   Figure C.4 FTIR Spectrum of SBAC 118   Figure C.5 FTIR Spectrum of MSBAC0   Figure C.6 FTIR Spectrum of MSBAC4 119   Figure C.7 FTIR Spectrum of MSBAC 10   Figure C.8 FTIR Spectrum of MSBAC10 after Sorption 120  C.1.8 Pourbaix Diagram of Pb2+  Figure C.9 Pourbaix Diagram of Pb2+ (Eph ?Web (2013))    121  C.2 Batch Sorption and Leachability Tests Data  C.2.1 Preliminary Batch Sorption Tests for Carbonized Sludge (CS)  Table C.7 Sorption Kinetics Data for CS with 1 g to 40 mL of 95 ppm Pb2+ Solution at pH =3 Time (min) Actual Solution Conc. (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) 10 95 43.6 1.028 1.111 10 95 35.3 1.194  20 95 28.5 1.33 1.283 20 95 33.2 1.236  40 95 33.7 1.226 1.208 40 95 35.5 1.19  80 95 17.4 1.552 1.615 80 95 11.1 1.678  160 95 11.7 1.666 1.638 160 95 14.5 1.61  720 95 11.6 1.668 1.659 720 95 12.5 1.65  1440 95 5.6 1.788 1.792 1440 95 5.2 1.796     122  Table C.8 Data Summary of CS Sorption Test for pH effect and Lead Concentration Effect at Low Concentration Range Solution pH Actual Lead Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) 3 3.98 1.46 0.1008 0.102 3 3.98 1.4 0.1032  3 9.04 1.6 0.2976 0.3024 3 9.04 1.36 0.3072  3 17.98 0.71 0.6908 0.6904 3 17.98 0.73 0.69  3 44.5 15.21 1.1716 1.1486 3 44.5 16.36 1.1256  3 92.5 33.8 2.348 2.192 3 92.5 41.6 2.036       5 0.53 0.18 0.014 0.0116 5 0.53 0.3 0.0092  5 4.37 1.92 0.098 0.103 5 4.37 1.67 0.108  5 15.83 0.92 0.5964 0.597 5 15.83 0.89 0.5976  5 41.5 11.4 1.204 1.136 5 41.5 14.8 1.068  5 89.4 29.1 2.412 2.424 5 89.4 28.5 2.436       7 1.95 1.22 0.0292 0.0358 7 1.95 0.89 0.0424  7 4.23 2.22 0.0804 0.0902 7 4.23 1.73 0.1  7 10.5 0.29 0.4084 0.4036 7 10.5 0.53 0.3988  7 48 5.74 1.6904 1.6812 7 48 6.2 1.672  7 82.8 17.71 2.6036 2.7058 7 82.8 12.6 2.808    123  C.2.2 Data of Sorption Kinetics for SBAC, MSBAC0, MSBAC4 and MSBAC10  Table C.9 Sorption Kinetics Data for SBAC with 1 g to 40 mL of 102.5 ppm Pb2+ Solution at pH =3 Sorption Time (min) Actual Solution Conc. (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) 1 102.5 80 0.9 0.88 1 102.5 81 0.86  5 102.5 76.8 1.028 1.07 5 102.5 74.7 1.112  10 102.5 75.3 1.088 1.11 10 102.5 74.2 1.132  360 102.5 72.2 1.212 1.23 360 102.5 71.3 1.248  720 102.5 72.8 1.188 1.222 720 102.5 71.1 1.256  1440 102.5 70.6 1.276 1.252 1440 102.5 71.8 1.228   Table C.10 Sorption Kinetics Data for MSBAC0 with 1g: 40mL of 110 ppm Lead Solution at pH =3 Sorption Time (min) Actual Solution Conc. (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) 1 110 76.9 1.32 1.28 1 110 79.35 1.23  5 110 44.5 2.62 2.64 5 110 43.5 2.66  360 110 38 2.88 2.84 360 110 40.2 2.79  720 110 38 2.88 2.89 720 110 37.5 2.90  1440 110 36.8 2.93 2.94 1440 110 36 2.96       124  Table C.11 Sorption Kinetics Data for MSBAC4 with 1 g to 40 mL of Pb2+ Solution at pH =3 Sorption Time (min) Actual Solution Conc. (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) 1 95.13 8.56 3.46 3.46 1 95.13 8.54 3.46  5 92.5 5.57 3.48 3.48 5 92.5 5.66 3.47  10 92.5 4.56 3.52 3.52 10 92.5 4.52 3.52  720 92.5 2.58 3.60 3.60 720 92.5 2.63 3.59  1440 92.5 2.62 3.60 3.60 1440 92.5 2.45 3.60   Table C.12 Sorption Kinetics Data for MSBAC10 with 1g to 40mL of 102.5ppm Pb2+ Solution at pH =3 Sorption Time (min) Actual Solution Conc. (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) 1 102.5 5.41 3.88 3.88 1  5.35 3.89  5 102.5 1.87 4.03 4.03 5  1.85 4.03  10 102.5 1.56 4.04 4.04 10  1.68 4.03  720 102.5 1.22 4.05 4.05 720  1.2 4.05  1440 102.5 1.18 4.05 4.05 1440  1.19 4.05      125  C.2.3 Data of Sorption Isotherms for CS SBAC, MSBAC0, MSBAC4 and MSBAC10 Table C.13 Data of Sorption Isotherm for CS with 1 g to 40 mL Pb2+ Solution at pH =3 for 80 min Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Final Solution pH 101 69.4 1.264 1.366 3.02 101 64.3 1.468  3.03 176.8 140 1.472 1.512 3 176.8 138 1.552  3.01 500.37 415 3.4148 3.0148 2.99 500.37 435 2.6148  2.99 800 695 4.2 4.3 2.98 800 690 4.4  2.98 1033 920 4.52 4.42 2.98 1033 925 4.32  2.99  Table C.14 Data of Sorption Isotherm for SBAC with 1 g to 40 mL Pb2+ Solution at pH =3 for 5 min Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Final Solution pH 110 84.8 1.008 1.01 2.95 110 84.7 1.012  2.94 200 145.3 2.188 2.29 2.94 200 140.2 2.392  2.9 495 330.7 6.572 6.496 2.92 495 334.5 6.42  2.93 802 471.6 13.216 12.896 2.92 802 487.6 12.576  2.91 1033 608.2 16.992 16.94 2.93 1033 610.8 16.888  2.94    126  Table C.15 Data of Sorption Isotherm for MSBAC0 with 1 g to 40 mL Pb2+ Solution at pH =3 for 5 min Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Final Solution pH 102.5 44.5 2.32 2.34 2.74 102.5 43.5 2.36  2.74 183 63.2 4.792 4.916 2.74 183 57 5.040  2.74 487.7 249.6 9.524 9.448 2.74 487.7 253.4 9.372  2.74 751 483.8 10.688 10.704 2.66 751 483 10.720  2.68 1000 684.848 12.606 12.593 2.59 1000 685.52 12.579  2.61  Table C.16 Data of Sorption Isotherm for MSBAC4 with 1 g to 40 mL Pb2+ Solution at pH =3 for 5 min Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Final  Solution pH 99.10 3.46 3.826 3.812 2.57 99.10 4.17 3.797  2.58 198.23 13.58 7.386 7.364 2.52 198.23 14.69 7.342  2.52 495 113.72 15.251 15.286 2.42 495 111.99 15.320  2.43 792 287.92 20.163 20.100 2.37 792 291.06 20.038  2.36 995.58 418.66 23.077 23.060 2.35 995.58 419.48 23.044  2.36    127  Table C.17 Data of Sorption Isotherm for MSBAC10 with 1 g to 40 mL Pb2+ Solution at pH =3 for 5 min Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Final  Solution pH 99.6 2.27 3.89 3.90 2.53 99.6 1.98 3.90  2.55 208.3 7.62 8.03 8.03 2.47 208.3 7.37 8.04  2.46 466 70.6 15.82 15.90 2.4 466 66.6 15.98  2.36 810 232.8 23.09 23.39 2.27 810 217.8 23.69  2.26 1004 328.16 27.03 27.08 2.01 1004 325.8 27.13  2.04  C.2.4 Data for Stability Tests of the Adsorbents after Sorption  Table C.18 Batch Desorption Tests Data for Stability Tests of Used Adsorbents and Corresponding Sorption Data, Desorption Time = 24 hours at 1g to 40 mL Distilled Water with pH =3  Sorption Data  Corresponding Desorption Data Material Equilibrated Conc. (ppm) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Standard Deviation  Equilibrated Conc. (ppm) Desorptivity (mg/g) Average Desorptivity (mg/g) Standard Deviation CS 950 3.32 3.22 0.1  4.07 0.16 0.16 0.00 955 3.12    4.05 0.16   SBAC 608.2 17.00 16.94 0.05  5.4 0.22 0.22 0.00 610.8 16.89    5.6 0.22   MSBAC 579.2 12.58 12.59 0.02  74 2.96 2.93 0.03 578.4 12.61    72.5 2.90   MSBAC4 326.4 22.69 23.01 0.32  11.63 0.47 0.47 0.01 310.4 23.33    12.07 0.48   MSBAC10 207.2 27.46 27.82 0.36  5.65 0.23 0.25 0.021 189.2 28.18    6.68 0.27   128  C.2.5 Repeated Single Sorption Tests for MSBAC10    Table C.19 Experimental Data for Repeated Single Sorption Test with MSBAC10 for Pb2+ Solution in 5 min with 1g to 40 mL Ratio at pH =3 No. of Sorption Actual Conc. (ppm) Equilibrated Conc. (ppm) Adsorptivity (mg/g) Average Adsorptivity (mg/g) SD Final Solution pH 1st 102.5 1.57 4.04 4.04 0.00 2.52  1.51 4.04   2.47 2nd 102.5 1.63 4.03 4.04 0.01 2.66  1.35 4.05   2.64 3rd 102.5 1.98 4.02 4.02 0.00 2.7  1.84 4.03   2.67 4th 102.5 2.95 3.98 3.99 0.01 2.7  2.71 3.99   2.67 5th 102.5 4.29 3.93 3.94 0.01 2.68  3.9 3.94   2.67 6th 102.5 4.3 3.93 3.94 0.02 2.74  3.7 3.95   2.71 7th 102.5 5.4 3.88 3.88 0.01 2.72  5.6 3.88   2.71 8th 102.5 5.91 3.86 3.87 0.01 2.73  5.47 3.88   2.69 9th 102.5 8.87 3.75 3.76 0.02 2.77  8.06 3.78   2.72 10th 102.5 11.31 3.65 3.66 0.01 2.75  10.82 3.67   2.72 SD = Standard Deviation 129  C.2.6 Experimental Data for Comparison of MSBAC10 with Different Adsorbents  Table C.20 Experimental Data for Different Adsorbents at 1 g to 10 mL of Pb2+ Solution at pH = 3, and Sorption Time = 5 min Adsorbents  Actual Solution Conc. Equilibrated Conc. (ppm) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Commercial AC 487.76 167.12 3.21 2.96  215.48 2.72  Perlite 487.76 416.16 0.72 0.58  443.72 0.44  MSBAC10 487.76 3.21 4.85 4.85  3.45 4.84  Zeolite 487.76 29.72 4.58 4.57  32.6 4.55  Kaolinite 487.76 282.8 2.05 2.01  292 1.96  Illite 487.76 8.6 4.79 4.81  5.1 4.83    Table C. 21 Experimental Data for Different Adsorbents at 1g to 10 mL of Lead Solution at pH = 3 Sorption Ratio, and Sorption Time = 24 hour Adsorbents  Actual Solution Conc. Equilibrated Conc. (ppm) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Commercial AC 500 8.81 4.91 4.91  8.79 4.91  Perlite 500 378.8 1.21 1.65  291 2.09  MSBAC10 500 6.7 4.94 4.94  5.46 4.95  Zeolite 500 0.54 4.5804 4.57  0.43 4.5516  Kaolinite (Li and Li. 2000) 487.76   2.68     Illite (Li and Li. 2000) 487.76   4.99     130  C.3 Supplementary Lab Data  C.3.1 Batch Sorption with ARD Solution by MSBAC10  Table C.22 Sorption Isotherm of MSBAC10 for Multi- Metal Species ARD Solution from Britannia Mine ARD with 1 g to 10 mL Solid-to-liquid Ratio Metal Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Final  Solution pH Cu 159.29 4.74 1.55 1.55 2.95  4.22 1.55  2.94 303.47 9.94 2.94 2.94 2.94  9.28 2.94  2.90 653.89 68.23 5.86 5.86 2.92  67.41 5.86  2.93 966.14 203.50 7.63 7.58 2.92  211.98 7.54  2.91 1488.20 489.39 9.99 10.00 2.93  487.46 10.01  2.94 Zn 210.00 192.08 0.18 0.09 2.95  209.00 0.01  2.94 421.43 378.50 0.43 0.40 2.94  384.16 0.37  2.9 930.70 889.91 0.41 0.31 2.92  909.80 0.21  2.93 1101.24 1073.94 0.27 0.42 2.92  1045.00 0.56  2.91 1763.05 1730.00 0.33 0.56 2.93  1684.00 0.79  2.94      131   Table C.22 Continued Metal Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Adsorptivity (mg/g) Average Adsorptivity (mg/g) Final  Solution pH Fe 75.80 0.00 0.76 0.76 2.95  0.00 0.76  2.94 148.90 0.39 1.49 1.49 2.94  0.23 1.49  2.9 347.90 52.16 2.96 2.95 2.92  54.31 2.94  2.93 1097.40 510.71 5.87 5.76 2.92  533.04 5.64  2.91 1327.10 719.24 6.08 6.22 2.93  690.12 6.37  2.94 Al 210.00 144.35 0.66 0.65 2.95  146.42 0.64  2.94 386.61 310.48 0.76 0.71 2.94  320.49 0.66  2.90 823.72 755.06 0.69 0.62 2.92  768.84 0.55  2.93 1355.94 1312.95 0.43 0.41 2.92  1316.46 0.39  2.91 1922.00 1938.71 -0.17 -0.10 2.93  1924.85 -0.03  2.94    132  Table C.23 Sorption Isotherms Date of Lai (2005) for Cu, Zn, Fe and Al on Clinoptilolite in Natural Acid Rock Drainage background Solution Metal Actual Solution Conc. before Sorption (mg/L) Equilibrated Conc. (mg/L) Average Adsorptivity (mg/g) Final pH Cu 89.5 31.54 0.139136 3.82 142.7 79.9 0.5797 3.44 243.5 165.1 0.62846 3.04 530.8 360.7 0.78459 2.49 832.8 668.6 1.7 1.94 1217.2 1034.4 1.642575 1.89 Zn 76.1 46.7 0.2941 3.82 130.3 85.6 0.4473 3.44 260.2 181.2 0.7906 3.04 588.1 422.7 1.653 2.49 791.6 698 0.9363 1.94 1231.4 945.1 2.8615 1.89 Fe 30.43 1.05 0.2938 3.82 68.1 3.265 0.6488 3.44 113 13.3 0.9977 3.04 421.43283 39.3 2.8853 2.49 658 204 4.54136 1.94 924 360 5.6374 1.89 Al 69.03 33.276 0.357642 3.82 105.5 77.426 0.281364 3.44 187.9 201.452 -0.1355 3.04 366.89 501.128 -1.34161 2.49 613.656 780.1 -1.66502 1.94 852.588 1019.192 -1.66517 1.89  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.24.1-0074198/manifest

Comment

Related Items