Electrochemical degradation of bisphenol A on different anodes

Laboratory experiments were carried out on the kinetics, pathways and mechanisms of electrochemical (EC) degradation of bisphenol A (BPA) on four types of anodes, Ti/boron-doped diamond (BDD), Ti/Sb-SnO2, Ti/RuO2 and Pt. There were considerable differences among the anodes in their effectiveness and performance of BPA electrolysis. BPA was readily destructed at the Ti/Sb-SnO2 and Ti/BDD anodes, the Pt anode had a moderate ability to remove BPA, and the Ti/RuO2 anode was incapable of effectively oxidising BPA. The intermediate products of EC degradation of BPA were detected and quantified by high-performance liquid chromatography (HPLC), and a general BPA degradation pathway was proposed based on the analytical results. It was suggested that (OH)-O-center dot radicals produced by water electrolysis attacked BPA to form hydroxylated BPA derivatives that were then transformed into one-ring aromatic compounds. These compounds underwent ring breakage, which led to the formation of aliphatic acids that were eventually mineralised by electrolysis to CO2. Compared to the Pt and Ti/RuO2 anodes, the Ti/Sb-SnO2 and Ti/BDD anodes were found to have higher oxygen evolution potentials and higher anodic potentials for BPA electrolysis under the same current condition. However, the stability and durability of the Ti/Sb-SnO2 anode still needs to be greatly improved for actual application. In comparison, with its high durability and good reactivity for organic oxidation, the TV BDD anode appears to be the more promising one for the effective EC treatment of BPA and similar endocrine disrupting chemical (EDC) pollutants. (C) 2009 Elsevier Ltd. All rights reserved.