Sulfur Surface-Modified Mesoporous Manganese Ferrite for Electron Transfer Driven Periodate Activation and Tetracycline Degradation

In this study, sulfur surface-modified manganese ferrite (MnFe 2 O 4 ) with enriched oxygen vacancies was synthesized using a metal-organic complex precursor strategy for periodate activation toward tetracycline degradation. The optimized catalyst achieved 97% tetracycline removal within 30 min. Sulfur surface modification enhanced oxygen vacancy formation, reduced charge transfer resistance, and promoted interfacial electron transfer. Mechanistic analyses revealed that periodate activation proceeded via an electron-transfer-mediated pathway, in which iodate radicals (IO 3 · ) played the dominant role, while superoxide radicals (O 2 ·− ), hydroxyl radicals ( · OH), singlet oxygen ( 1 O 2 ), and sulfate radicals (SO 4 ·− ) contributed secondarily. Iodine species (I 2 , I 3 − , and HOI) were observed below detection limits under the tested conditions, and periodate was ultimately converted to iodate. These findings demonstrate that sulfur surface modification is an effective strategy for improving ferrite-catalyzed periodate activation and provide insight into more environmentally safer advanced oxidation processes for antibiotic-contaminated water treatment.