Electrochemical degradation of bisphenol A at boron-doped diamond electrodes

To solve the pollution of bisphenol A (BPA) which was considered as an environmental endocrine, boron-doped diamond (BDD) electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) system. Mechanisms and reaction pathways of electrochemical degradation of bisphenol A (BPA) at BDD electrode was investigated by high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometer (LC-MS). The results showed that BPA with different initial concentrations were completely mineralized to CO₂ at BDD electrode, following the pseudo-first-order rate kinetics. The apparent reaction rate constant for BPA with initial concentrations of 100 and 10 mg·L^-1 were 0.494 and 0.700 h^-1, respectively. When the current density was increased from 10 to 40 mA·cm^-2, the apparent reaction rate constant and the removal rate were increased by 50.61% and 11.26%, respectively. Seven intermediate products were detected in the degradation process, and two different degradation pathways were discovered. One pathway was that BPA was decomposed readily into one-ring aromatic compounds first and eventually mineralized by electrolysis to CO₂, another was that both of the aromatic rings in BPA molecular structure underwent ring breakage simultaneously and then continuously oxidized to CO₂ till the end of the reaction.