Increasing Lewis acidic sites and promoting electron transfer of Mn2O3 by C-hybridization to improve the peroxymonosulfate activation for Bisphenol A degradation

Abstract

The surface acidity and electron transfer performance of manganese oxide catalysts significantly affected its performance of peroxymonosulfate (PMS) activation. In this work, Mn₂O₃ catalyst was prepared by the precipitation method. The C-hybridization Mn₂O₃ (Mn₂O₃-D) catalyst prepared with disodium oxalate as a precipitant had more Mn³⁺ and Lewis acid sites on the surface, promoting the binding of PMS on the catalyst surface, which exhibited the best performance in inducing PMS activation to degrade bisphenol A (BPA). Quenching experiments and in situ electron spin resonance (ESR) results indicated that radicals and singlet oxygen were not the main reactive oxygen species (ROSs) in the advanced oxidation process. The chemical probe experiment of phenylmethylsulfone (PMSO) showed that the ≡ Mn-OOSO₃^- metastable intermediate formed by the binding of PMS with Mn sites on the catalyst surface was important active species for contaminants degradation. Contaminants combined with intermediates on the catalyst surface to form the electron transfer channels, which were directly degraded through oxygen-atom-transfer pathway and single-electron-transfer pathway. And the hybridization of C promoted the electron transfer during this process. This work further elucidated the reaction mechanism of PMS activation by manganese oxides, and proposed new ideas for the design of MnO_x catalysts for efficient activation of PMS.