Chlorinated ethene contaminations are a widespread environmental hazard and a threat to drinking water supplies. Electrochemical methods for in situ degradation of the chlorinated ethenes in the plume are under development. In laboratory, complete electrochemical removal of chlorinated ethenes in undivided flow-through reactors is reported when using palladized iron (Fe) cathodes (C) and cast Fe anodes (A). The cost of the electrodes depends on the Fe purity. In this study, 99.95%, 99.8% and 98+% palladized Fe cathodes, and 99.8% Fe and cast Fe anodes were investigated. The surfaces of the palladized Fe electrodes were examined by scanning electron microscopy. Deposition of palladium by electroless plating onto the Fe surfaces was uneven and disconnected. The less pure the Fe material, the higher the degree of oxide coverage of the cathode’s surface during electroless plating. Electrochemical application via Fe electrodes installed in a flow-through reactor of field-extracted groundwater and sandy sediment was studied for three-electrode configurations of A–A–C and C–C–A. The anodes of 99.8% Fe and cast Fe demonstrated different corrosion patterns; uniform corrosion and graphitization, respectively. Corrosion products clogged the sandy matrix. The corrosion product compositions differed between the A–A–C and C–C–A electrode configurations. The groundwater pH of 7.35 ± 0.05 changed downgradient to the electrochemical zone to 9.5 and 6.2 for the A–A–C and C–C–A reactors, respectively. The response of the hydrogeochemical settings to the established redox zones showed that the C–C–A electrode configuration was less intrusive to the surrounding environment.

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中文翻译：

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去除地下水中氯化乙烯的电极材料选择和顺序

氯化乙烯污染是一种广泛的环境危害，是对饮用水供应的威胁。用于烟羽中氯化乙烯的原位降解的电化学方法正在开发中。在实验室中，当使用钯铁（Fe）阴极（C）和铸铁阳极（A）时，据报道在未分开的流通式反应器中可以完全电化学去除氯化乙烯。电极的成本取决于铁的纯度。在这项研究中，研究了99.95％，99.8％和98 +％的钯酸阴极，以及99.8％的Fe和铸造Fe阳极。通过扫描电子显微镜检查被钯化的Fe电极的表面。通过化学镀到Fe表面上的钯沉积是不均匀的并且不连续。铁材料纯度越低，化学镀期间阴极表面的氧化物覆盖度越高。通过在田间抽取的地下水和沙质沉积物的流通反应器中安装的Fe电极的电化学应用，研究了A–A–C和C–C–A的三电极配置。99.8％Fe和铸造Fe的阳极表现出不同的腐蚀方式。均匀腐蚀和石墨化。腐蚀产物堵塞了沙质基质。在A–A–C和C–C–A电极配置之间，腐蚀产物的成分有所不同。在A–A–C和C–C–A反应器中，地下水的pH值为7.35±0.05下降到电化学区，分别下降到9.5和6.2。

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