Activation of peroxymonosulfate by a stable Co-Mg-Al LDO heterogeneous catalyst for the efficient degradation of ofloxacin

A Co–Mg–Al layered double oxides (LDO) was successfully prepared via a simple one-step hydrothermal method and characterized to investigate its physicochemical properties, such as crystal structure, functional group types, specific surface area, microscopic morphology, surface composition, and valence. The catalyst exhibited efficient catalytic performance in a Co–Mg–Al LDO/peroxymonosulfate (PMS) system. Under the conditions of pH = 6.72, 0.8 mM PMS, and 0.1 g/L catalyst dosage, 98.2% of the antibiotic ofloxacin (OFL) with an initial concentration of 30 mg/L was degraded within 40 min. The results of free radical quenching experiments and the electron paramagnetic resonance results indicated that there were mainly four types of active species generated in the Co–Mg–Al LDO/PMS system, including hydroxyl, sulfate, singlet oxygen and superoxide radicals. The oxygen vacancies and redox cycles of Co2+/Co3+ on the surface of Co–Mg–Al LDO were found to be crucial for PMS activation. In addition, a reasonable reaction mechanism and possible degradation pathway for OFL were proposed for this system. The Co–Mg–Al LDO catalyst exhibited outstanding performance in terms of its chemical stability after metal ion leaching experiments and recyclability during cycling experiments. The Co–Mg–Al LDO/PMS system, as expected, holds great potential for use in the efficient catalytic treatment of wastewater.