Effects of reduced sulfur compounds on Pd-catalytic hydrodechlorination of trichloroethylene in groundwater by cathodic H2 under electrochemically induced oxidizing conditions.
Effects of reduced sulfur compounds on Pd-catalytic hydrodechlorination of trichloroethylene in groundwater by cathodic H2 under electrochemically induced oxidizing conditions.
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DOI：
10.1021/es402169d
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发表时间：
2013-09-17
影响因子：
11.4
通讯作者：
Alshawabkeh, Akram N.
中科院分区：
文献类型：
--
作者：
Yuan, Songhu;Chen, Mingjie;Mao, Xuhui;Alshawabkeh, Akram N.
还原硫化合物（RSC）使缺氧地下水中污染物的催化加氢脱氯的Pd催化剂中毒。研究了活性炭对好氧地下水中三氯乙烯（TCE）钯催化加氢脱氯反应的影响。在氧化条件下，在无隔板电解槽中电解水以产生用于TCE加氢脱氯的H2。TCE被有效地加氢脱氯为乙烷，在酸性条件下具有显著的H2O2积累。浓度低于93.8 μM的硫化物会中度抑制TCE加氢脱氯和H2O2的产生。低浓度（≤ 1 mM）亚硫酸盐的存在显著增强TCE的衰减，而高浓度（3 mM）亚硫酸盐的存在对TCE的衰减起抑制作用，当亚硫酸盐浓度降至1 mM以下时，TCE的衰减增强。通过自由基清除实验和电子自旋共振分析，验证了亚硫酸盐在氧化条件下产生的SO3·−是促进TCE衰减的新活性物种。这项研究揭示了一个独特的机制，亚硫酸盐对三氯乙烯加氢脱氯的Pd和H2在好氧地下水的影响，并提出了一种替代方法，以增加Pd的耐RSC中毒。
Reduced sulfur compounds (RSCs) poison Pd catalysts for catalytic hydrodechlorination of contaminants in anoxic groundwater. This study investigates the effects of RSCs on Pd-catalytic hydrodechlorination of trichloroethylene (TCE) in oxic groundwater. Water electrolysis in an undivided electrolytic cell is used to produce H2 for TCE hydrodechlorination under oxidizing conditions. TCE is efficiently hydrodechlorinated to ethane, with significant accumulation of H2O2 under acidic conditions. Presence of sulfide at concentrations less than 93.8 μM moderately inhibits TCE hydrodechlorination and H2O2 production. Presence of sulfite at low concentrations (≤ 1 mM) significantly enhances TCE decay, while at high concentration (3 mM) inhibits initially and enhances afterwards when sulfite concentration declines to less than 1 mM. Using radical scavenging experiments and electron spin resonance assay, SO3•− which is generated from sulfite under oxidizing conditions is validated as the new reactive species contributing to the enhancement. This study reveals a distinct mechanism of effect of sulfite on TCE hydrodechlorination by Pd and H2 in oxic groundwater and presents an alternative approach to increasing resistance of Pd to RSCs poisoning.
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