Removal of persistent organic contaminants by electrochemically activated sulfate

Farhat, Ali, Keller, Jurg, Tait, Stephan and Radjenovic, Jelena (2015) Removal of persistent organic contaminants by electrochemically activated sulfate. Environmental Science and Technology, 49 24: 14326-14333. doi:10.1021/acs.est.5b02705


Author Farhat, Ali
Keller, Jurg
Tait, Stephan
Radjenovic, Jelena
Title Removal of persistent organic contaminants by electrochemically activated sulfate
Journal name Environmental Science and Technology   Check publisher's open access policy
ISSN 0013-936X
1520-5851
Publication date 2015-11-17
Year available 2015
Sub-type Article (original research)
DOI 10.1021/acs.est.5b02705
Open Access Status Not Open Access
Volume 49
Issue 24
Start page 14326
End page 14333
Total pages 8
Place of publication Dordrecht, Netherlands
Publisher Springer
Language eng
Subject 1600 Chemistry
2304 Environmental Chemistry
Abstract Solutions of sulfate have often been used as background electrolytes in the electrochemical degradation of contaminants and have been generally considered inert even when high-oxidation-power anodes such as boron-doped diamond (BDD) were employed. This study examines the role of sulfate by comparing electro-oxidation rates for seven persistent organic contaminants at BDD anodes in sulfate and inert nitrate anolytes. Sulfate yielded electro-oxidation rates 10-15 times higher for all target contaminants compared to the rates of nitrate anolyte. This electrochemical activation of sulfate was also observed at concentrations as low as 1.6 mM, which is relevant for many wastewaters. Electrolysis of diatrizoate in the presence of specific radical quenchers (tert-butanol and methanol) had a similar effect on electro-oxidation rates, illustrating a possible role of the hydroxyl radical (OH) in the anodic formation of sulfate radical (SO ) species. The addition of 0.55 mM persulfate increased the electro-oxidation rate of diatrizoate in nitrate from 0.94 to 9.97 h, suggesting a nonradical activation of persulfate. Overall findings indicate the formation of strong sulfate-derived oxidant species at BDD anodes when polarized at high potentials. This may have positive implications in the electro-oxidation of wastewaters containing sulfate. For example, the energy required for the 10-fold removal of diatrizoate was decreased from 45.6 to 2.44 kWh m by switching from nitrate to sulfate anolyte.
Formatted abstract
Solutions of sulfate have often been used as background electrolytes in the electrochemical degradation of contaminants and have been generally considered inert even when high-oxidation-power anodes such as boron-doped diamond (BDD) were employed. This study examines the role of sulfate by comparing electro-oxidation rates for seven persistent organic contaminants at BDD anodes in sulfate and inert nitrate anolytes. Sulfate yielded electro-oxidation rates 10-15 times higher for all target contaminants compared to the rates of nitrate anolyte. This electrochemical activation of sulfate was also observed at concentrations as low as 1.6 mM, which is relevant for many wastewaters. Electrolysis of diatrizoate in the presence of specific radical quenchers (tert-butanol and methanol) had a similar effect on electro-oxidation rates, illustrating a possible role of the hydroxyl radical (•OH) in the anodic formation of sulfate radical (SO4 •-) species. The addition of 0.55 mM persulfate increased the electro-oxidation rate of diatrizoate in nitrate from 0.94 to 9.97 h-1, suggesting a nonradical activation of persulfate. Overall findings indicate the formation of strong sulfate-derived oxidant species at BDD anodes when polarized at high potentials. This may have positive implications in the electro-oxidation of wastewaters containing sulfate. For example, the energy required for the 10-fold removal of diatrizoate was decreased from 45.6 to 2.44 kWh m-3 by switching from nitrate to sulfate anolyte.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
Advanced Water Management Centre Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 17 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 03 Dec 2015, 07:17:27 EST by Ali Farhat on behalf of School of Chemical Engineering