Strategies for Effective Degradation of Methyl Orange Dye in Aqueous Solution via Electrochemical Treatment with Copper/Graphite Electrodes

Abstract

This study investigated the electrochemical degradation of methyl orange dye (MO) in aqueous solution using copper/graphite electrodes as anode and cathode respectively. The process parameters such as electrolyte concentrations, current density, pH and temperature were analyzed. The results proved that copper/graphite electrodes were effective for MO degradation and the reaction followed the first-order kinetic model. The degradation efficiency decreased with increasing MO concentration and increased steadily with current density. The pH trend with degradation efficiency was pH 9 (98%) > pH 7 (96%) > pH 3 (77%) after 70 min of electrolysis time, which shows that the alkaline conditions favoured the degradation process. Fourier transform infrared spectroscopy (FTIR) and UV–Vis absorption spectroscopy confirmed the dye degradation process, with the formation of degradation intermediates. The FTIR results revealed that the oxidative degradation of MO may be initiated at the N=N azo bond, which was confirmed by quantum chemical modelling of the electronic structure parameters of MO.