Heterogeneous catalytic oxidation degradation of BPAF by peroxymonosulfate active with manganic manganous oxide: Mineralization, mechanism and degradation pathways

Abstract In this study, the catalytic ability and mechanisms involved in activating peroxymonosulfate (PMS) with Mn3O4 and the degradation pathways of bisphenol-AF (BPAF) removal was investigated. SO4−• and ·OH which were explored by and scavenging tests were the major reactive radicals in the Mn3O4/PMS system. A simple simulation algorithm was also used to calculate the relative concentrations of SO4−• ([SO4−•]) and ·OH ([·OH]) which were 8.39 × 10 −15 M and 6.96 × 10 −13 M, respectively. The mechanism for the electron transfer between the Mn (II) and Mn (III) species was discussed. Three degradation pathways of BPAF were determined by the GC/MS and LC/MS technology, including chemical mechanism of oxidation, hydroxylation, electron transfer, polymerization, and ring-cleavage. In addition, the results suggested that the Mn3O4/PMS system had an efficient total organic carbon (TOC) removal rate and excellent environmental adaptability, the removal rate of TOC being as high as 73.2% in the control condition. Furthermore, the reuse experiments and the comparison on the structural and componential changes of Mn3O4 powder before and after reaction demonstrated that the Mn3O4 catalyst possessed excellent stability and reusability. Finally, a maximum BPAF degradation of approximately 90.0% was achieved on the optimal conditions for 500 mg/L Mn3O4 dosage, 4 mM PMS concentration, 7.0 ± 0.2 initial pH, and 5 mg/L BPAF concentration respectively. And the effect of the coexisting anions and natural environmental water quality were also considered. This study demonstrated the Mn3O4/PMS system can be considered as a green approach for the removal of environmental reluctant pollutants.