Electrochemical degradation of Acid Red G by titanium-based PbO₂ anode

In this research, a PbO₂ electrode was adopted as the anode for the electrocatalytic oxidative degradation of acid red G (ARG). The main purpose was to study the variations in the ultraviolet-visible spectrum and degradation mechanisms of ARG on the PbO₂ anode. Influences of different factors on the degradation and energy consumption were considered. The results indicated that ARG was oxidized by hydroxyl radicals produced on the electrode surface through indirect oxidation mechanisms. The breaking rate of azo bonds was conspicuously higher than those of benzene rings and naphthalene rings. The ARG removal rate was clearly higher than the total organic carbon (TOC) removal rate. Although prolonging electrolytic time gave rise to the removal of organics, the energy consumption increased and the unit energy consumption of TOC removal was significantly higher than that of ARG. The increase in current densities promoted ARG degradation and TOC removal, but could also lead to the apparent increase in the unit energy consumption and the decrease in the mineralization current efficiency. The removal efficiencies of ARG and TOC could be reduced by increasing the dye concentration, but the unit energy consumption decreased accordingly, which indicated that a high concentration of organics led to the decrease in the unit energy consumption in electrocatalytic reactions. The temperature increase favored the degradation and removal of organics.