Solar-assisted electrooxidation process for enhanced degradation of bisphenol A: Performance and mechanism

Comparisons of solar-assisted electrooxidation process (SEOP), electrooxidation (EO), and solar photolysis have been addressed to evaluate the performance of bisphenol A (BPA) removal and mineralization. The results presented the BPA removal efficiency of 100% in SEOP was higher than that of 2.8% and 88% at 90 min in direct photolysis and EO process, respectively, indicating the synergistic effect of EO and solar light in SEOP. The investigation of corresponding active species indicated that center dot OH and O-1(2) played the predominant role in SEOP. The introduction of solar light in the EO process could promote the generation of center dot OH, O-1(2), and SO4 center dot- and enhance the degradation performance, explaining the synergistic removal mechanism. The density functional theory (DFT) results pointed out the main active sites of BPA attacked by electrophilic reagent based on the calculation of the energy barrier, Fukui index, and molecular orbitals, etc. Taking into account of the identification of intermediates, the possible degradation pathways of BPA mainly included C-C bond cleavage, ring hydroxylation, and ketonization process. The effects of anode materials, illumination intensity, current density, and electrolyte for the degradation efficiency in SEOP were explored. These results exhibited that the efficient removal of BPA in SEOP was achieved with a relatively lower electricity consumption of 1.21 kWh.(m(3).order)(-1), which provided new insights into the synergistic mechanism and enhanced removal of contaminants.