Degradation of Bisphenol A by Peroxymonosulfate Catalytically Activated with Mn1.8Fe1.2O4 Nanospheres: Synergism between Mn and Fe.

A high-efficient, low-cost, and eco-friendly catalyst is highly desired to activate peroxides for environmental remediation. Due to the potential synergistic effect between bimetallic oxides' two different metal cations, these oxides exhibit superior performance in the catalytic activation of peroxymonosulfate (PMS). In this work, novel Mn1.8Fe1.2O4 nanospheres were synthesized and used to activate PMS for the degradation of bisphenol A (BPA), a typical refractory pollutant. The catalytic performance of the Mn1.8Fe1.2O4 nanospheres was substantially greater than that of the Mn/Fe monometallic oxides and remained efficient in a wide pH range from 4 to 10. More importantly, a synergistic effect between solid-state Mn and Fe was identified in control experiments with Mn3O4 and Fe3O4. Mn was inferred to be the primary active site in the surface of the Mn1.8Fe1.2O4 nanospheres, while Fe(III) was found to play a key role in the synergism with Mn by acting as the main adsorption site for the reaction substrates. Both sulfate and hydroxyl radicals were generated in the PMS activation process. The intermediates of BPA degradation were identified and the degradation pathways were proposed. This work is expected to help to elucidate the rational design and efficient synthesis of bimetallic materials for PMS activation.