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UBC Theses and Dissertations
Effect of mixing on peroxymonosulfate generation Shaharuzzaman, Mohammad
Abstract
Efficient generation of pulping and bleaching chemicals is essential to economic production of pulp. In some cases the success of a proposed process will depend on whether the key chemical can be generated economically at an industrial scale. Peroxymonosulfate (PMS, Na₂S0₅) has shown to be an effective and selective TCF bleaching agent for both delignification and brightness development. The commercial production of PMS is achieved by reacting concentrated H₂SO₄ with 70% H2O2. Conversion is limited to 70% by equilibrium, and production costs are high for commercial bleaching applications. With the increase of oxygen delignification throughout the world, a cheaper method to generate alkaline PMS is desired. This is because an acidic PMS stage, if placed between two alkaline oxygen treatments, would require additional alkali to reach the required bleaching pH. The additional cost of the added alkali would significantly increase the total cost associated with use of acidic PMS. PMS can also be generated by the oxidation of sodium sulfite with oxygen or air in alkali media. This shows promise as an economic alternative for basic PMS generation. Past generation of PMS in the laboratory was limited to 20% yield and 3.8 g/L Na₂S0₅. However, the reaction is mixing-sensitive and optimization of mixing and reaction conditions allow both the yield and chemical concentration to be increased. The effects of key parameters (feed-time, energy dissipation rate, sodium sulfite concentration, reactant volume ratio, oxygen pressure and temperature) were verified in a number of different batch reactors (medium-intensity, P[sub HT], high-intensity, rotor-stator). The addition time of sodium sulfite (feed time) was found to affect both the PMS yield and concentration. For very short feed times (
Item Metadata
Title |
Effect of mixing on peroxymonosulfate generation
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1998
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Description |
Efficient generation of pulping and bleaching chemicals is essential to economic
production of pulp. In some cases the success of a proposed process will depend on
whether the key chemical can be generated economically at an industrial scale.
Peroxymonosulfate (PMS, Na₂S0₅) has shown to be an effective and selective TCF
bleaching agent for both delignification and brightness development. The commercial
production of PMS is achieved by reacting concentrated H₂SO₄ with 70% H2O2.
Conversion is limited to 70% by equilibrium, and production costs are high for
commercial bleaching applications. With the increase of oxygen delignification
throughout the world, a cheaper method to generate alkaline PMS is desired. This is
because an acidic PMS stage, if placed between two alkaline oxygen treatments, would
require additional alkali to reach the required bleaching pH. The additional cost of the
added alkali would significantly increase the total cost associated with use of acidic PMS.
PMS can also be generated by the oxidation of sodium sulfite with oxygen or air
in alkali media. This shows promise as an economic alternative for basic PMS generation.
Past generation of PMS in the laboratory was limited to 20% yield and 3.8 g/L Na₂S0₅.
However, the reaction is mixing-sensitive and optimization of mixing and reaction
conditions allow both the yield and chemical concentration to be increased. The effects of
key parameters (feed-time, energy dissipation rate, sodium sulfite concentration, reactant
volume ratio, oxygen pressure and temperature) were verified in a number of different
batch reactors (medium-intensity, P[sub HT], high-intensity, rotor-stator).
The addition time of sodium sulfite (feed time) was found to affect both the PMS
yield and concentration. For very short feed times (
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Extent |
5852827 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-06-27
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0058948
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1998-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.