Comparative Electrochemical Oxidation of Bisphenol A Using BDD, PbO2, and IrO2 Anodes: Identification of Active Free Radicals

The comparative electrochemical oxidation efficiency of bisphenol A (BPA) was explored using boron doped diamond (BDD), PbO2, and IrO2 anodes. Several parameters were optimized using the BDD anode. The optimal conditions were a current density of 60 mA center dot cm(-2), Na2SO4 concentration of 4 g center dot L-1, agitation rate of 600 rpm, and BPA concentration of 50 mg center dot L-1. The BPA removal efficiencies for the BDD, PbO2, and IrO2 anodes were 100%, 79.9%, and 19.5%, respectively; only the BDD anode showed complete BPA removal. Similarly, the COD removal efficiencies with the BDD, PbO2, and IrO2 anodes were 81.8%, 37.0%, and 6.73%, respectively. Oxidation with the BDD anode was realized mainly by center dot OH, accounting for approximately 85.6%. In addition, SO4 center dot- oxidation and direct oxidation accounted for approximately 7.7% and 6.7%, respectively. In the PbO2 anode, center dot OH oxidation, SO4 center dot- oxidation, and direct oxidation accounted for approximately 51.0%, 8.2%, and 40.8%, respectively. In the IrO2 anode, oxidation was dependent mainly on direct oxidation, and no center dot OH and SO4 center dot- were generated.