Attenuation of BPA degradation by SO₄^[rad]− in a system of peroxymonosulfate coupled with Mn/Fe MOF-templated catalysts and its synergism with Cl⁻ and bicarbonate

Mn_0.8Fe_2.2O₄ magnetic nanocrystals (Mn_0.8Fe_2.2O₄ MNCs) are synthesized by thermal treatment of a metal-organic framework (MOF) template, and their physicochemical properties are characterized in detail. The Mn_0.8Fe_2.2O₄ MNCs exhibited highly efficient performance for the catalytic degradation of Bisphenol A (BPA) by peroxymonosulfate (PMS) activation at various initial pH, catalyst dosage, and PMS concentration. A leaching solution experiment evidenced that PMS activation by the Mn_0.8Fe_2.2O₄ MNCs is a heterogeneous process. Interestingly, scavenging experiments and electron paramagnetic resonance (EPR) analysis demonstrated that HO[rad] is the dominant radical for BPA degradation, rather than SO₄^[rad]−. The scavenger experiment indicated that the surface-bound radicals may play the crucial role for BPA degradation. Increasing Cl⁻ or decreasing bicarbonate concentrations in solution enhanced the catalytic degradation process significantly through non-radical pathways. The Mn_0.8Fe_2.2O₄ MNCs exhibited desirable stability and reusability, that the spent Mn_0.8Fe_2.2O₄ MNCs could be significantly regenerated by thermal treatment at 450 °C in open air. Findings from this study would expand the applications of MOFs and also provide new insights into the enhancement of degradation efficiency during PMS activation processes.