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

In this study, the catalytic ability and mechanisms involved in activating peroxymonosulfate (PMS) with Mn 3 O 4 and the degradation pathways of bisphenol-AF (BPAF) removal was investigated. SO 4 −• and · OH which were explored by and scavenging tests were the major reactive radicals in the Mn 3 O 4 /PMS system. A simple simulation algorithm was also used to calculate the relative concentrations of SO 4 −• ([SO 4 −• ]) 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 Mn 3 O 4 /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 Mn 3 O 4 powder before and after reaction demonstrated that the Mn 3 O 4 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 Mn 3 O 4 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 Mn 3 O 4 /PMS system can be considered as a green approach for the removal of environmental reluctant pollutants.