The Electrochemical Hydrodechlorination of 2, 4-Dichlorophenol in Water and Its Improvement by Combination with Chemical Catalytic Reduction

The performance of electrochemical hydrodechlorination of 2, 4-dichlorophenol (2, 4-DCP) in water using Pd-modified Cu electrode (Pd/Cu) was evaluated in a batch experiment. The results showed that, at an applied current density of 1.5 mA/cm², 2, 4-DCP concentration decayed rapidly from 49.99 mg/L to 0.40 mg/L after 120 min with consecutive change of intermediate 2-CP. Phenol was formed as the main final product. Base on the above results, a combined electrochemical with chemical catalytic reduction process for 2, 4- DCP was put forward and improved. In this combined process, 2, 4-DCP was reduced on the surface of both cathode (Pd/Cu) and catalyst (hydrotalcite-supported Pd-Cu catalyst) without addition of a reducing agent, which may further enhance removal efficiency for 2, 4-DCP and intermediate 2-CP. Dissolved oxygen in water decreased 2, 4-DCP reduction efficiency, which was attributed to the competitive reduction of O₂ with 2, 4-DCP. The combined process exhibited excellent stability for hydrodechlorination of 2, 4-DCP.