Rapid degradation of organic pollutants by enhanced persulfate activation using CeO2-MnFe2O4 nanostructures: A polymetallic synergistic effect

Persulfate-based advanced oxidation processes (AOPs) have attracted considerable attention in the treatment of organic wastewater with high performance and long lifetime. The construction of efficient, environmentallyfriend, and stable nanocatalysts has been recognized as a promising approach to activate persulfate. Herein, magnetic CeO2-MnFe2O4 nanomaterials fabricated via a simple sol-gel method were used for the first time to enhanced activate persulfate (PS) for the removal of the organic pollutant enrofloxacin (ENR). It was demonstrated that 97.2% of ENR (10 mg L  1) was efficiently degraded. 63.3% of TOC decreased within 35 min under a neutral solution (pH 6.81) in the PS+CeO2-0.2MnFe2O4 system using a catalyst dosage of 0.25 g L  1 and 0.18 mM PS. The magnetic CeO2-MnFe2O4 nanostructures maintained excellent recovery as well as recyclability ENR removal efficiency was 90% after recycling five times. EPR and quenching tests indicated that sulfate radicals (SO4 & BULL; ) and hydroxyl radicals (& BULL;OH) significantly contributed to ENR removal. XPS analysis showed that the synergistic redox cycles of Ce3+/Ce4+, Mn2+/Mn3+, and Fe2+/Fe3+ are essential to activate PS for ENR degradation. DFT calculations also revealed that PS molecules preferred to adsorb to and dissociate on CeO2-MnFe2O4 surfaces rather than just CeO2 and MnFe2O4 surfaces. CeO2 plays a dual role in the charge transfer from CeO2MnFe2O4 to PS molecules, i.e., both electron storage and donor. This work also provides a new interpretation to explain the activation mechanism of PS. The developed CeO2-MnFe2O4 nanostructures with rapid removal efficiency, high degradation efficiency and good recyclability may provide potential guidance for the design of polymetallic oxide nanocatalysts in PS-based AOPs.