Magnetic Fe3O4-C@MoS2 composites coordinated with peroxymonosulfate catalysis for enhanced tetracycline degradation

Abstract

Tetracycline is an organic compound that poses a significant threat to both the ecological environment and human health during its long-term production and use. Advanced oxidation processes based on sulfate radicals (SR-AOP) have been recognized as effective techniques for treating antibiotic contamination. However, The urgent demand for a green, efficient, and recyclable catalyst to effectively facilitate persulfate treatment of tetracycline pollution is evident. Magnetic Fe3O4-C@MoS2 composite were synthesized using hydrothermal and pyrolysis methods. Degradation experiments, free radical quenching experiments, EPR analysis were carried out to investigate the degradation performance and mechanisms of Fe3O4-C@MoS2 composite. Results showed that the degradation efficiency of 100 mL of 20 mg/L tetracycline solution reached up to 97% within 40 mins with the dosage of 20 mg Fe3O4-C@MoS2 and 30.7 mg peroxmonosulfate. Furthermore, this degradation system exhibited excellent efficiency even over a wide pH range of 3–9. The transformation of Mo (IV) and S2-/Sn2- species valence states facilitated the conversion between Fe(III)/Fe(II). Both free radical (SO4⋅−,⋅OHandO2⋅−) as well as non-free radical species (O21) were found to accelerate the catalytic reaction during the tetracycline degradation. The possible pathways of tetracycline degradation were proposed, and the toxicity of the intermediate products were proved to be lower than that of tetracycline. Finally, magnetic Fe3O4-C@MoS2 composites possessed good reusability and stability after 4 cycles of degradation.