Exploring degradation mechanism of tetracycline via high-effective peroxymonosulfate catalysts of montmorillonite hybridized CoFe composites and safety assessment

High-effective catalyst for activating peroxymonosulfate (PMS) to degrade pollutant in wastewater and minimize its toxicity is crucial. Herein, CoFe2O4/montmorillonite composites (CF/MO) were synthesized and used as high-effective PMS catalysts for the degradation of tetracycline (TC). The CoFe2O4 nanoparticles were firmly loaded on the surface of MO with FeOAl bonds, preventing the leaching of metal ions and bringing superior reusability and stability. It was optimized that the 20%-CF/MO showed superior catalytic activity to activate PMS for TC degradation, and SO4− was the dominant active species for TC complete degradation within 30 min and achieved high kinetic rate of 0.178 min−1. The ultrahigh catalytic performance toward TC degradation was ascribed to the cycles and regeneration of Co(III)/Co(II) and Fe(III)/Fe(II) synthergetic surface redox couples in the catalysts. The TC degradation pathway and reaction mechanism in the 20%-CF/MO/PMS system were also proposed based on DFT calculation. The ecotoxicity of degradation products was assessed using proteomics, and the toxicity of TC was found to decrease significantly as the reaction progressed.