Enhanced degradation of Bisphenol A (BPA) by peroxymonosulfate with Co3O4-Bi2O3 catalyst activation: Effects of pH, inorganic anions, and water matrix

In this study, a novel Co3O4-Bi2O3 catalyst was synthesized using a microwave-assistant method, and the corresponding characteristics were studied through XRD, SEM, and N-2 adsorption. As a peroxymonosulfate (PMS) activator, the catalytic activity of the synthesized catalyst was evaluated on Bisphenol A (BPA) removal, and the result showed that Co3O4-Bi2O3 catalyst promoted BPA degradation, where 100% BPA was degraded within 15 min under the condition of [catalyst] = 0.1 g.L-1 and [PMS]/[BPA](molar) = 5. The Co3O4-Bi2O3/PMS system presented a good catalytic activity when the solution pH varied from 3.0 to 11.0. Under the different concentrations of various inorganic anions in the Co3O4-Bi2O3/PMS system, Cl- showed an inhibited effect at low concentration and a promoted effect at high concentration. CO32- showed a slight inhibited effect, while H2PO4- showed a considerable inhibited effect. Additionally, both NO3- and SO42- showed a negligible effect on BPA removal. For the real water bodies, both the drinking water and tap water showed a slight decrease in degradation efficiency of BPA but a distinctly negative effect on BPA mineralization, which might be contributed to the competition between BPA and indigenous organic matters in the two water matrices for their oxidation by radical species. The quenching experiment was enforced and it was found that both SO4 center dot- and center dot OH on the surface-bound of catalyst were the main active radicals in this system. Overall, the Co3O4-Bi2O3 catalyst as a PMS activator is a promising catalyst in PMS activation for sulfate radical-based wastewater treatment.