Reductive electrochemical remediation of emerging and regulated disinfection byproducts

Radjenović, Jelena, Farré, Maria José, Mu, Yang, Gernjak, Wolfgang and Keller, Jurg (2012) Reductive electrochemical remediation of emerging and regulated disinfection byproducts. Water Research, 46 6: 1705-1714. doi:10.1016/j.watres.2011.12.042


Author Radjenović, Jelena
Farré, Maria José
Mu, Yang
Gernjak, Wolfgang
Keller, Jurg
Title Reductive electrochemical remediation of emerging and regulated disinfection byproducts
Journal name Water Research   Check publisher's open access policy
ISSN 0043-1354
1879-2448
Publication date 2012-04-15
Sub-type Article (original research)
DOI 10.1016/j.watres.2011.12.042
Volume 46
Issue 6
Start page 1705
End page 1714
Total pages 10
Place of publication London, United Kingdom
Publisher IWA Publishing
Collection year 2013
Language eng
Formatted abstract
Long-term exposure to low concentrations of disinfection byproducts (DBPs) in drinking water has been associated with increased human-health risks of bladder cancer and adverse reproductive outcomes. In this study, we investigated electrochemical reduction utilizing a resin-impregnated graphite cathode for the degradation of 17 DBPs (i.e. halomethanes, haloacetonitriles, halopropanones, chloral hydrate and trichloronitromethane) at low μg L−1 concentration levels. The reduction experiments were potentiostatically controlled at cathode potentials −700, −800 and −900 mV vs Standard Hydrogen Electrode (SHE) during 24 h. At the lowest potential applied (i.e. −900 mV vs SHE), the disappearance of DBPs from the solution after 24 h of reduction was >70%, except for chloroform (32%), 1,1-dichloropropanone (48%), and chloral hydrate (31%). Due to the participation of several removal mechanisms (e.g. electrochemical reduction, adsorption, volatilization and/or hydrolysis) it was not possible to distinguish the removal efficiencies of electrochemical reduction of individual compounds. Adsorption of the more hydrophilic DBPs (i.e. haloacetonitriles, chloral hydrate, and 1,1-dichloropropanone) onto the electrode seems to be affected by the cathode polarization, as the removals observed in the open circuit experiments were significantly higher than the ones obtained in electrochemical reduction under the same conditions. The overall efficiency of reduction was estimated based on the analyses of the released Cl, Brand I ions. Nearly complete C–I bond cleavage was achieved at all three potentials applied, and from the theoretically predicted release of I ions, calculated based on the removed DBPs, 86 ± 9 to 92 ± 1% was measured in the catholyte solution at −700 to −900 mV vs SHE. Debromination efficiencies obtained were 74 ± 3, 79 ± 6 and 68 ± 4% at −700, −800 and −900 mV vs SHE, while for C–Cl bond cleavage the obtained values were 69 ± 1, 72 ± 1 and 76 ± 4%, respectively. Nevertheless, dechlorination efficiencies are to be considered as approximate, since an increase in Cl concentration was observed in the open circuit experiments due to the hydrolysis of some of the chlorine-containing DBPs. Although the Coulombic efficiencies for DPBs dehalogenation were only 1.9 ± 0.3 (−900 mV vs SHE) –4.1 ± 0.2% (−700 mV vs SHE), relatively low energy consumption of the process was observed, estimated at 72 ± 2 Wh m−3 at −900 mV vs SHE for the concentration range of DBPs in this study (i.e. 65.3–129.7 μg L−1). The study demonstrated that reductive electrochemical treatment has the potential to be a modern remediation technology for the removal of low concentrations of halogenated DBPs in water.
Keyword Electrochemical reduction
Dehalogenation
Disinfection byproducts
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2013 Collection
Advanced Water Management Centre Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 28 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 07 Mar 2012, 15:03:55 EST by Dr Maria Farre Olalla on behalf of School of Chemical Engineering