Degradation of bisphenol A by activating peroxymonosulfate with Mn0.6Zn0.4Fe2O4 fabricated from spent Zn-Mn alkaline batteries

Spinel ferrites have shown great potential to activate peroxides for environmental remediation. In this work, a Mn-Zn ferrite catalyst was fabricated by the citrate combustion method from spent Zn-Mn alkaline batteries. The synthesized Mn0.6Zn0.4Fe2O4 catalysts were applied to activate peroxomonosulfate (PMS) and degrade bisphenol A (BPA) in water. A 95.8% BPA (0.1 mM) removal was achieved at initial pH of 6.2, Mn0.6Zn0.4Fe2O4 dosage of 0.2 g/L, PMS concentration of 0.5 mM, and reaction time of 60 min. The concentration of metal leaching and radical identification experiments suggested that BPA is mainly degraded by surface-adsorbed reactive radicals. Metals at A site of the spinel (AFe2O4, A = Mn and Zn) were responsible for PMS activation and Fe(III) acted as the reservoir for the surface hydroxyl groups, which substantially accelerated the degradation of BPA. The addition of Cl− improved the destruction of BPA and a NaHCO3 concentration below 5 mM had a negligible effect on the BPA removal. When the PMS/Mn0.6Zn0.4Fe2O4 process was used to treat real river water spiked with BPA, the removal of BPA was much faster than that in deionized water. This implied that the PMS/Mn0.6Zn0.4Fe2O4 process may provide some new insights not only for the recycling of spent batteries, but also for removal of contaminants from wastewater.