Electrochemical degradation of bromopyrogallol red in presence of cobalt ions

This paper summarizes the results of a degradation test of bromopyrogallol red (BPR) and textile dye wastewater (TDW) with a conventional three-electrode potentiostatic system in the presence of cobalt ions (electro Co2+–H2O2 system). H2O2, produced by the two-electron reduction of O2 at the cathode, would react with Co2+ ions, leading to the generation of hydroxyl radicals (√OH), which caused the degradation of the organic pollutants. With BPR degradation process as the reference point, the optimal conditions (pH=4.0 and the concentration of Co2+ is 0.1 mM) and the treating capacity of the system were both studied and compared with electro-Fenton’s reagent. Many benefits were shown by the electro Co2+–H2O2 system, such as less metal ions consumption, more moderate conditions and faster reaction process. Treated with the system for 0.5 h, chemical oxygen demand and biological oxygen demand of TDW (pH=5.2), without pH adjustment, were reduced by 95.7% and 92.7%, respectively. These characteristics make the method another appropriate solution for wastewater treatment, especially for those contaminated by organic pollutants.