Continuous electrochemical decomposition of dichloromethane in aqueous solution using various column electrodes

Abstract Dichloromethane is one of the chlorohydrocarbons that contaminate the soil and groundwater. They are conventionally removed from water by the aeration method and aeration/activated carbon adsorption. These methods only remove the compounds from water into other phases, and therefore require a secondary treatment for decomposition of the pollutants. The electrochemical method is an appropriate method for the decomposition of halocarbons in water. However, dichloromethane is one of the most persistent halocarbons for electrochemical treatment. In this paper, we optimized the conditions for electrochemical decomposition of dichloromethane in water and attempted to continuously treat the dichloromethane solution using a flow cell. During batch electrolysis, a Cu wire electrode showed high electrocatalytic activity for the decomposition of dichloromethane and the optimum potential for the decomposition was −1.3 V vs. Ag/AgCl. During flow electrolysis, the conversion of dichloromethane was largely dependent on the packing material of the column electrodes. A Cu metal-powder column electrode showed higher activity than a Cu particle-impregnated carbon fiber electrode and activated carbon electrode. The Cu metal-powder column electrode decomposed 20 ppm dichloromethane in an aqueous solution with 100% conversion at a low flow rate. This result suggests that the structure of the Cu surface affects the adsorption of dichloromethane on the Cu electrodes.

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