Mechanochemically synthesized Mn3O4@β-cyclodextrin mediates efficient electron transfer process for peroxymonosulfate activation

Abstract

The rational surface engineering of heterogeneous catalysts is of great significance in advanced oxidation processes (AOPs) for eliminating refractory contaminants but remains challenging. In this study, β-cyclodextrin modified Mn3O4 (Mn3O4@β-CD) was prepared through a mechanochemical approach for peroxymonosulfate (PMS) activation, which achieved efficient bisphenol A (BPA) removal via electron transfer process (ETP). The reactive PMS* complex with elevated potential was identified to dominate the ETP by withdrawing electrons from BPA with Mn3O4@β-CD working as electron shuttle, as evidenced by spectroscopy and electrochemical techniques. Experimental results and density functional theory (DFT) calculations showed that the β-CD modification enhanced the interfacial accumulation of pollutants and shortened the migration distance between pollutants (electron donor) and catalysts (electron shuttle) to mediate electron transfer more effectively. Benefitting from the improved ETP, the Mn3O4@β-CD/PMS system showed efficient PMS utilization and practical adaptability in actual waterbodies. This study provides a rational approach for modulating the surface structure of heterogeneous catalysts in PMS-based AOPs for environmental remediation.