Degradation of 2,4-dichlorophenol in aqueous solution by a hybrid oxidation process

A hybrid photoelectroreaction system has been developed in this study, which consists of three functional electrodes: a TiO2/Ti sheet as the anode, a steel (Fe) sheet as another anode in parallel and a piece of graphite felt (GF) as the cathode. While an electrical current is applied between the Fe anode and GF cathode and UV light is irradiated on the surface of TiO2/Ti anode, both of E-Fenton reaction and photoelectrocatalytic (PEC) reaction are involved simultaneously. The integration of E-Fenton and PEC reactions was evaluated in terms of 2,4-dichlorophenol (2,4-DCP) degradation in aqueous solution. In the meantime, the current distribution between two anodes and pH influence on the 2,4-DCP degradation were studied and optimized. Experimental results confirmed that 2,4-DCP in aqueous solution was successfully degraded by 93% and mineralized by 78% within 60 min in such a hybrid oxidation process. When a current intensity of 3.2 mA was applied, the current efficiency for H2O2 generation on the GF cathode was determined to be 61%. Furthermore, the experiments demonstrated that combination of E-Fenton reaction with photocatalytic reaction let the process be less pH sensitive and would be more favorable to water and wastewater treatment in practice.