Enhanced activation of peroxymonosulfate with cobalt-doped manganese-iron oxides for contaminant degradation: Regulation of oxygen vacancy defects

Abstract

Peroxymonosulfate (PMS) based on heterogeneous catalytic reaction was a promising advanced oxidation process (AOP) to remove refractory contaminants. However, the contaminant degradation efficiency was challenged by the limited number of catalytic active site and low capacity for durable electron transfer. In this study, cobalt-doped manganese-iron oxides (CoxMn1-xFe2O4) rich in oxygen vacancy (Ov) were synthesized using a microwaved hydrothermal method and applied to activate PMS for bisphenol A (BPA) degradation, which achieved the complete removal of BPA within 30 min. In all samples, Co0.5Mn0.5Fe2O4 exhibited good catalytic activity for PMS, which was approximately 21.10 times higher than that of MnFe2O4. The results of density functional theory calculations and in-situ characterization demonstrated that the enhanced performance was ascribed to the generation of Ov and the enrichment of active site, which significantly accelerated the cycling of redox pairs and improved the PMS adsorption, which was more favorable to the formation of active specie in the electron transport process. The oxidation process involved both free radical and non-radical mechanisms, with main reactive species of O2−, and 1O2 being responsible for BPA degradation. In addition, the effects of different aqueous matrices, the results of reusability experiments, and ecotoxicity assessment experiments demonstrated the viability of the Co0.5Mn0.5Fe2O4/PMS system for real sewage purification. This research revealed a structural regulation method to enhance the catalytic activity of the material and offered new perspectives on the engineering of rich Ov.