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A novel method to tailor the porous structure of KOH-activated biochar and its application in Capacitive Deionization and energy storage Dehkhoda, Amir Mehdi; Gyenge, Előd; Ellis, Naoko
Abstract
This study reveals a novel method to tailor the micro- and meso-porous structures of activated biochar by exploiting the interaction between pre-carbonization drying conditions and carbonization temperature in KOH activation. Biochar samples were mixed with concentrated KOH and then dried under air or nitrogen for various periods of time (0 -280 h) followed by carbonization at 475, 675 or 875°C. It is confirmed that by manipulating drying conditions and carbonization temperatures, the KOH activated biochar can have a predominantly microporous, mesoporous or a combined (micro/meso) porous structure. The surface area, micropore and mesopore volumes tailored between: 488 to 2670 m ² g-¹, 0.04 to 0.72 cm³ g-¹, and 0.05 to 1.70 cm³ g-¹, respectively. The mechanism of porosity development was investigated by FTIR analysis suggesting conversion of KOH to K₂CO₃ due to different drying conditions as a major role in tailoring the structure. The application of activated biochar with tailored porosity was investigated for Electric Double Layer adsorption of NaCl/NaOH to be employed in water treatment (capacitive deionization) or energy storage (supercapacitor) processes. The majorly microporous activated biochar (N₂-dried activated at 675°C) showed promising capacitances between 220-245 F g-¹. Addition of mesoporous structure resulted in capacitances between 182-240 F g-¹ with significantly reduced electrode resistance and improved capacitive behaviour as evidenced by Impedance Spectroscopy and Galvanostatic Charge/Discharge tests.
Item Metadata
Title |
A novel method to tailor the porous structure of KOH-activated biochar and its application in Capacitive Deionization and energy storage
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Creator | |
Date Issued |
2016-04
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Description |
This study reveals a novel method to tailor the micro- and meso-porous structures of activated biochar by exploiting the interaction between pre-carbonization drying conditions and carbonization temperature in KOH activation. Biochar samples were mixed with concentrated KOH and then dried under air or nitrogen for various periods of time (0 -280 h) followed by carbonization at 475, 675 or 875°C. It is confirmed that by manipulating drying conditions and carbonization temperatures, the KOH activated biochar can have a predominantly microporous, mesoporous or a combined (micro/meso) porous structure. The surface area, micropore and mesopore volumes tailored between: 488 to 2670 m ² g-¹, 0.04 to 0.72 cm³ g-¹, and 0.05 to 1.70 cm³ g-¹, respectively. The mechanism of porosity development was investigated by FTIR analysis suggesting conversion of KOH to K₂CO₃ due to different drying conditions as a major role in tailoring the structure. The application of activated biochar with tailored porosity was investigated for Electric Double Layer adsorption of NaCl/NaOH to be employed in water treatment (capacitive deionization) or energy storage (supercapacitor) processes. The majorly microporous activated biochar (N₂-dried activated at 675°C) showed promising capacitances between 220-245 F g-¹. Addition of mesoporous structure resulted in capacitances between 182-240 F g-¹ with significantly reduced electrode resistance and improved capacitive behaviour as evidenced by Impedance Spectroscopy and Galvanostatic Charge/Discharge tests.
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Subject | |
Genre | |
Type | |
Language |
eng
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Date Available |
2018-04-01
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0340929
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URI | |
Affiliation | |
Citation |
Dehkhoda, A. M., Gyenge, E., & Ellis, N. (2016). A novel method to tailor the porous structure of KOH-activated biochar and its application in capacitive deionization and energy storage. Biomass & Bioenergy, 87, 107-121.
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Publisher DOI |
10.1016/j.biombioe.2016.02.023
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Peer Review Status |
Reviewed
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Scholarly Level |
Faculty; Postdoctoral
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Rights URI | |
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DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International