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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• 作者：Songhu Yuan ; Mingjie Chen ; Xuhui Mao ; Akram N. Alshawabkeh
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：September 17, 2013
• 年：2013
• 卷：47
• 期：18
• 页码：10502-10509
• 全文大小：377K
• 年卷期：v.47,no.18(September 17, 2013)
• ISSN：1520-5851

文摘

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. The presence of sulfide at concentrations less than 93.8 渭M moderately inhibits TCE hydrodechlorination and H₂O₂ production. The presence of sulfite at low concentrations (鈮? mM) significantly enhances TCE decay, while at high concentration (3 mM) inhibits initially and enhances afterward when sulfite concentration declines to less than 1 mM. Using radical scavenging experiments and an electron spin resonance assay, SO₃^{鈥⑩€?/sup>, 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.}