Electrochemical treatment of wastewaters containing 4-nitrocathecol using boron-doped diamond anodesA paper submitted to the Journal of Environmental Engineering and Science.

Abstract

The electrochemical oxidation of aqueous wastes polluted with 4-nitrocathecol has been studied on boron-doped diamond electrodes in an acidic medium. The voltammetric results showed that 4-nitrocathecol is oxidized in the potential region where the supporting electrolyte is stable. Galvanostatic electrolysis study showed that the oxidation of these wastes in a single-compartment electrochemical flow cell with boron-doped diamond anodes results in the complete mineralization of the organics. Cathecol, benzoquinone, 4-aminocathecol, maleic and oxalic acids have been detected as soluble organics, polymeric product as solid product at the cathode surface and NO3– as mineral product during the electrolysis of 4-nitrocathecol. The electrochemical oxidation of 4-nitrocathecol consists of a sequence of steps: release of NO2 and (or) hydroxylation of the aromatic ring; formation of quinonic compounds; oxidative opening of aromatic ring to form carboxylic acids; and oxidation of carboxylic acids to carbon dioxide. Both direct and mediated oxidation processes are involved in these stages.