Reductive dehalogenation of aqueous-phase chlorinated hydrocarbons in an electrochemical reactor

This work describes the reductive dehalogenation of carbon tetrachloride (CT) in a novel liquid-phase electrochemical reactor. The reactor consists of a cylindrical porous copper cathode with a concentric carbon-cloth anode wrapped around the cathode. The results show that CT destruction can be achieved, even in low conductivity solutions (i.e., deionized water), reaching 80% conversion of CT with a residence time of 10 min when a cathode potential of -0.4 V (versus a standard hydrogen electrode) is used. A mathematical model was formulated to simulate reactor performance. The model accounted for CT reductive dechlorination, hydrogen evolution on the cathode surface, and CT mass-transfer limitations. The equilibrium potential for CT reduction on the cathode surface was the only adjustable parameter. The model adequately represented experimental data under high-conductivity (2.2 S/m) and low-conductivity (0.05 S/m) conditions. The model results and experimental observations suggest that the entire cathode was active during CT reduction experiments, i.e., solution potential did not render portions of the cathode nonreactive, even in the low-conductivity experiments.