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 Co ²⁺-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⁺-H₂O ₂ 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.