Electrochemical Continuous Decomposition of Chloroform and Other Volatile Chlorinated Hydrocarbons in Water Using a Column Type Metal Impregnated Carbon Fiber Electrode

Abstract

Trihalomethane and other chlorinated hydrocarbons are known to be toxic to human health. However, removal of these compounds from water is not easy. We attempted continuous electrochemical decomposition of chloroform that is the main compound of trihalomethanes and some toxic chlorinated hydrocarbons in water using a metal-impregnated carbon fiber electrode (CFE). At Ag- and Zn-impregnated CFE, concentration of chloroform in 0.5 M K2SO4 (the supporting electrolyte) solution was decreased from 0.25 m mol/L to below the limit of detection of our analysis system (1 ppm) at a flow rate of 1 mL/min. The main product of electrolysis was methane. This high efficiency, determined by the chemical yield, hardly changed at a flow rate of 20 mL/min at a Ag-impregnated CFE. At a flow rate of 1 mL/min, chloroform was degraded with a decomposition efficiency of almost 100% even in the solution without the supporting electrolyte, whereas at a higher flow rate, the efficiency for the decomposition of chloroform decreased with a decrease in the concentration of the supporting electrolyte. Tetrachloroethylene, 1,1,1-trichloroethane, and 1,1,2-trichloroethane were also decomposed at a Ag-impregnated CFE with an efficiency of almost 100%.