Construction of MOFs-derived magnetic Co/Co3C encapsulated in CNTs for efficient degradation of antibiotics via peroxymonosulfate activation: Performance, mechanism and toxicity evolution

The extensive use of antibiotics has impacted human health and the ecological environment. This study focuses on synthesizing efficient and stable Co/Co3C/C magnetic composites derived from Co-MOFs for catalyzing antibiotic degradation. The influence of zinc (Zn) and potassium nitrate (KNO3) as an assistant on the structure and catalytic degradation of Co@N-CZn,K were thoroughly investigated. Remarkably, within 30 min, Co@N-CZn,K exhibited outstanding efficiency in degrading tetracycline (TC), while maintaining high catalytic activity across various anions and pH values. Even after three cycles of degradation, TC still experienced a remarkable degradation rate as high as 96 %. Notably, cobalt nanoparticles are confined in carbon nanotubes, resulting in the formation of core–shell structures enveloped by carbon layers. Consequently, only a negligible amount (0.54 mg/L) of leached Co2+ was observed. Furthermore, free radical quenching experiments revealed that OH•, SO4•−, O2•− and 1O2 species simultaneously participated in the oxidation process within the Co@N-CZn,K/PMS system, with 1O2 playing a dominant role. The activation mechanism and potential degradation pathways in the decomposition of TC were systematically investigated and proposed, while concurrently assessing the toxicity of degradation intermediates generated during this process.