A Confined-Pyrolysis Strategy to Construct Magnetic Co@N‑C Nanoreactors with Enhanced Peroxymonosulfate-Activated Metronidazole Degradation

In this study, a novel Co-MOF (metal–organic framework), CUST-587, was successfully synthesized via a solvothermal method. A composite material of CUST-587 encapsulated by chitosan (CS), namely, CUST-587@CS, was prepared by a one-pot method. Further calcination resulted in the formation of magnetic nanomaterial Co@N-C-600. The experimental results demonstrated that this catalyst exhibited outstanding performance in activating peroxymonosulfate (PMS) for the degradation of the pollutant metronidazole (MNZ). Catalyst Co@N-C-600 achieved complete removal of MNZ within 18 min, with a degradation rate constant of 0.553 min–1, which was 9.70 times that of Co@C-600 (0.057 min–1), 14.95 times that of CUST-587@CS (0.036 min–1), and 27.65 times that of CUST-587 (0.020 min–1). In addition, electron paramagnetic resonance (EPR) studies confirmed the presence of both radical and nonradical degradation routes in the Co@N-C-600/PMS system, and catalytic reaction mechanisms were proposed. In addition, a potential degradation pathway for MNZ was proposed in the Co@N-C-600/PMS system. Based on pea seedling cultivation trials, the catalyst was found to be environmentally friendly. This paper describes a unique synthesis technique that offers a new approach to the creation of MOF-derived ecologically useful materials.