CuFe2O4 supported on montmorillonite to activate peroxymonosulfate for efficient ofloxacin degradation

Abstract

Copper ferrite embedded in montmorillonite (CuFe2O4-montmorillonite, CF-Mt) was designed and employed as a composite catalyst for peroxymonosulfate (PMS) activation to degrade ofloxacin (OFL). CuFe2O4 characterization confirmed that this compound successfully dispersed on the surface of the montmorillonite. CF-Mt loaded with 40% CuFe2O4 (0.4CF-Mt) possessed favorable magnetic properties, excellent pore structure, and abundant catalytic sites, obtaining the highest OFL degradation efficiency (85.2%) in the presence of PMS compared to other CF-Mt composites with different CuFe2O4 loads. Influencing parameters including catalyst dosage, PMS concentration, initial pH, and co-existing anions were also investigated. High catalyst dosage and PMS concentrations were found to favor OFL degradation. The optimum pH in the 0.4CF-Mt/PMS system for OFL removal was 6.8 (neutral pH). Additionally, Cl− promoted OFL degradation performance, whereas H2PO4− and HCO3− had the opposite effect. Radical quenching experiments and electron paramagnetic resonance demonstrated that the OFL degradation in the 0.4CF-Mt/PMS system was largely attributed to free radical pathways dominated by SO4·- and ·OH. OFL mineralization increased with reaction time, finally reaching a mineralization rate of 54.8%. Furthermore, 0.4CF-Mt maintained excellent catalytic activity after repeated use. Taken together, this study provides a basis for the development of strategies to design bimetallic oxide catalysts for the efficient treatment of antibiotic-contaminated wastewater with PMS.