Peroxymonosulfate activation by ZIF-67-Derived bimetallic sulfide/carbon composite (CoFeS-NC) for efficient degradation of the emerging contaminant ceftiofur sodium

Abstract

The bimetallic sulfide/carbon composite CoFeS-NC was successfully synthesized using a facile ligand exchange pathway and subsequent pyrolysis method, using Fe-doped ZIF-67 as self-templates. The prepared CoFeS-NC was used as an activator for peroxymonosulfate (PMS) to degrade ceftiofur sodium (CFS). The CoFeS-NC/PMS system demonstrated broad pH adaptability, considerable environmental stability and outstanding degradation efficiency for an array of pollutants. Notably, this system reached its optimum performance with the combination of 0.1 g/L CoFeS-NC and 0.3 g/L PMS at pH = 9. Under these optimized conditions, the CFS degradation efficiency reached 96% within 10 min and the kinetic constant reached 0.87 min−1. The reactive oxygen species (ROS) generated in the CoFeS-NC/PMS system were elucidated by conducting quenching experiments and electron paramagnetic resonance (EPR) studies. Both singlet oxygen (1O2) and sulfate radicals (SO4·-) were identified as the important ROS in CFS degradation. Moreover, various characterization methods were employed to elucidate the physicochemical properties of catalysts. Additionally, the role of Fe, Co and S species in CoFeS-NC was systematically investigated. Based on these findings, the possible catalytic mechanism was proposed. This study shows extraordinary potential for efficient removal of emerging pollutants in wastewater treatment applications.