Cobalt Nanoparticles Enabled Nonradical Light-Assisted Peroxymonosulfate Activation for Rapid Antibiotic Removal

Nonradical routes with high selectivity, stability, and strong resistance to anion interference for wastewater treatment have attracted increasing interest. Herein, a cobalt-loaded graphitic carbon nitride (CoCN) photocatalyst was synthesized to activate peroxymonosulfate (PMS) under simulated sunlight for degradation of ciprofloxacin hydrochloride. The optimized 15CoCN/light/PMS catalyst achieved an exceptional degradation efficiency of 96.67% within 9 min, with a pseudo-first-order rate constant of 0.384 min^-1, which is 2.6 and 4.5 times higher than that of standalone photocatalysis (0.146 min^-1) and PMS activation (0.086 min^-1). Mechanistic investigations, supported by radical scavenging and EPR analyses, reveal a predominantly nonradical reaction pathway in which singlet oxygen (¹O₂) serves as the primary reactive oxygen species, accompanied by a minor contribution from O₂^·- and photogenerated holes. In addition, the 15CoCN/light/PMS system exhibits excellent environmental robustness, including broad pH adaptability and strong resistance to common inorganic anions, and maintains high performance in real water matrices. These results highlight the great potential of Co-modified graphitic carbon nitride as an efficient and sustainable platform for the light-assisted remediation of antibiotic contaminants in aquatic environments.