Electrochemical Oxidation of 1,4-Dichlorobenzene on Platinum Electrodes in Acetonitrile-Water Solution: Evidence for Direct and Indirect Electrochemical Oxidation Pathways

Abstract

The degradation of 1,4-dichlorobenzene (p-DCB) in acetonitrile-water solution was investigated under electrochemical oxidation on a platinum electrode. The related mechanism was proposed through the organic analysis and electrochemical measurements such as chronoamperometric and cyclic voltammetric measurements. The cyclic voltammogram curves of p-DCB, parachlorophenol, parahydroquinone, 2,5-dichlorophenol, and 2,5-dichlorohydroquinone showed two oxidation peaks (1.8, 2.3 V (vs SCE)), (1.1, 1.9 V (vs SCE)), (0.7, 1.8 V (vs SCE)), (1.1, 2.2 V (vs SCE)), and (0.7, 1.8 V (vs SCE)), respectively. The oxidation peaks of 1,4-benzoquinone and 2,5-dichloro-p-benzoquinone were found at the potential of 1.8 (vs SCE), coinciding with the oxidation potential of platinum. The results of cyclic voltammetric and chronoamporometric experiments suggested that both direct and indirect electrochemical oxidation processes involved the degradation of p-DCB. For the intermediates, 1,4-benzoquinone and 2,5-dichloro-p-benzoquinone underwent indirect oxidation, parahydroquinone and 2,5-dichlorohydroquinone degraded mainly by direct oxidation, and parachlorophenol and 2,5-dichlorophenol removed by both direct and indirect oxidation. Furthermore, a possible degradation scheme for the oxidation of p-DCB in acetonitrile-water solution was proposed.