High-efficient degradation of oxytetracycline by visible photo-Fenton process using MnFe2O4/g-C3N4: Performance and mechanisms

Oxytetracycline (OTC) is a broad-spectrum antibiotic that has strong persistence, bioaccumulation, and biodegradability, and poses great harm to human health. In this study, MnFe2O4/g-C3N4 heterojunction composite was successfully synthesized and its photo-Fenton catalytic activity for OTC degradation was tested. The MnFe2O4/gC(3)N(4) catalyst exhibited excellent photo-Fenton catalytic activity; approximately 80.5 %, 42.9 %, 5 %, and 3 % of OTC was decomposed after 10 min of treatment in the presence of MnFe2O4/g-C3N4, single MnFe2O4, single g-C3N4, and single H2O2, respectively. The OTC degradation was mainly initiated by oxidation, and the roles of center dot OH and O-2(center dot-) were quite weak. Simultaneously, the Fe2+/Fe3+ and Mn2+/Mn3+ redox reactions promoted the production of reactive species. As a result, the conjugated double bond system, naphthol ring, and benzene ring in the OTC molecules were destroyed, accompanied by the removal of groups such as -OH, -NH2, -CH3, and -CONH2. Based on the analysis of degradation intermediates and characteristics of MnFe2O4 and g-C3N4, possible degradation pathways and mechanisms of OTC in the MnFe2O4/g-C3N4 photo-Fenton catalytic system were depicted. Furthermore, the stability and recycling of the MnFe2O4/g-C3N4 were evaluated.

Automated summary

In this study, MnFe2O4/g-C3N4 composite was synthesized and its photo-Fenton catalytic activity for OTC degradation was tested. The catalyst showed excellent catalytic activity, decomposing a high percentage of OTC. The degradation mechanism and pathways of OTC in the MnFe2O4/g-C3N4 system were analyzed. The composite material also exhibited stability and recyclability.