Activation of peroxymonosulfate by novel Pt/Al2O3 membranes via a nonradical mechanism for efficient degradation of electron-rich aromatic pollutants

Abstract

Novel flexible Pt/Al2O3 membranes were prepared and applied as catalysts for the degradation of organic pollutants in the presence of peroxymonosulfate (PMS). 100% of bisphenol A (BPA) could be removed within 20 min by using fresh Pt/Al2O3-membrane-activated PMS, which represents outstanding performance compared to catalysts reported in recent years. The influence of the PMS dosage, initial BPA concentration, and initial pH on BPA degradation were studied. The mechanism of BPA degradation in this system was investigated in depth. The BPA degradation process was not inhibited by the addition of radical scavengers to the system, and no free radicals were detected using ESR analysis. Additionally, the PMS molecules were only decomposed in the presence of both the catalysts and BPA. The results also demonstrated that only electron-rich aromatics could be degraded by this system. Furthermore, in contrast to typical degradation pathways involving the generation of free radicals, no intermediates formed via OH addition reaction were detected. Based on these findings, a nonradical pathway was suggested rather than a conventional OH/SO4− radical-based advanced oxidation process (AOP) mechanism. BPA is efficiently degraded by the transfer of electrons from its π-π aromatic ring to PMS via the noble metal Pt as transfer medium in this reaction. The findings in this work broaden the understanding of the use of activated PMS for the degradation of organic pollutants, and extend the application of flexible inorganic membranes in wastewater treatment.