Reductive electrochemical remediation of emerging and regulated disinfection byproducts

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• 作者：Jelena Radjenovi? ; ^{j.radjenovic@awmc.uq.edu.au} ; Maria José ; Farré ; Yang Mu ; Wolfgang Gernjak ; Jurg Keller
• 关键词：Electrochemical reduction ; Dehalogenation ; Disinfection byproducts
• 刊名：Water Research
• 出版年：2012
• 出版时间：15 April, 2012
• 年：2012
• 卷：46
• 期：6
• 页码：1705-1714
• 全文大小：513 K

文摘

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 ¦Ìg?L^? concentration levels. The reduction experiments were potentiostatically controlled at cathode potentials ?00, ?00 and ?00?mV vs Standard Hydrogen Electrode (SHE) during 24?h. At the lowest potential applied (i.e. ?00?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^{?/sup>, Br?/sup> and I?/sup> ions. Nearly complete C-I bond cleavage was achieved at all three potentials applied, and from the theoretically predicted release of I?/sup> ions, calculated based on the removed DBPs, 86?¡À?9 to 92?¡À?1 % was measured in the catholyte solution at ?00 to ?00?mV vs SHE. Debromination efficiencies obtained were 74?¡À?3, 79?¡À?6 and 68?¡À?4 % at ?00, ?00 and ?00?mV vs SHE, while for C-Cl bond cleavage the obtained values were 69?¡À?1, 72?¡À?1 and 76?¡À?4 % , respectively. Nevertheless, dechlorination efficiencies are to be considered as approximate, since an increase in Cl?/sup> 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?¡À?0.3 (?00?mV vs SHE) -4.1?¡À?0.2 % (?00?mV vs SHE), relatively low energy consumption of the process was observed, estimated at 72?¡À?2?Wh?m? at ?00?mV vs SHE for the concentration range of DBPs in this study (i.e. 65.3-129.7?¦Ìg?L?). 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.}