Oxidation of bisphenol A by persulfate via Fe3O4-α-MnO2 nanoflower-like catalyst: Mechanism and efficiency

A novel and high-efficiency Fe3O4-α-MnO2 nanoflower-like catalyst was synthesized using a two-step hydrothermal method. The catalyst was used to activate persulfate (PS) to degrade bisphenol A (BPA) in aqueous phase. The mechanism of the Fe3O4-α-MnO2/PS system was investigated. X-ray photoelectron spectra and cyclic voltammograms showed that the mixed valence of Fe3O4-α-MnO2 was favorable to electron transfer between Fe and Mn elements. Apparently, this process promoted the circulation of Fe2+/Fe3+ and Mn3+/Mn4+, increasing the effectiveness of the catalyst to activate the PS. In addition, with ATR-FTIR analysis, the influence of phosphate confirmed the presence of OH groups on the Fe3O4-α-MnO2 surface. Thus, these groups played crucial roles in the PS activation. Sulfate radicals were reacting species of great importance in BPA degradation. The degradation intermediates were also detected via GC–MS analysis, and the possible BPA degradation pathway was proposed.