LaCo0.95Mo0.05O3/CeO2 composite can promote the effective activation of peroxymonosulfate via Co3+/Co2+ cycle and realize the efficient degradation of hydroxychloroquine sulfate.

Hydroxychloroquine sulfate (HCQ) is extensively utilized due to its numerous therapeutic effects. Because of its properties of high solubility, persistence, bioaccumulation, and biotoxicity, HCQ can potentially affect water bodies and human health. In this study, the LaCo_0.95Mo_0.05O₃-CeO₂ material was successfully prepared by the sol-gel process, and it was applied to the experiment of degrading HCQ by activating peroxymonosulfate (PMS). The results of characterization analysis showed that LaCo_0.95Mo_0.05O₃-CeO₂ material had good stability, and the problem of particle agglomeration had been solved to some extent. Compared with LaCo_0.95Mo_0.05O₃ material, it had a larger specific surface area and more oxygen vacancies, which was helpful to improve the catalytic activity for PMS. Under optimal conditions, the LaCo_0.95Mo_0.05O₃-CeO₂/PMS system degraded 95.5 % of HCQ in 10 min. The singlet oxygen, superoxide radicals, and sulfate radicals were the main radicals for HCQ degradation. The addition of Mo⁶⁺/Mo⁴⁺ and Ce⁴⁺/Ce³⁺ promoted the redox cycle of Co³⁺/Co²⁺ and enhanced the degradation rate of HCQ. Based on density functional theory and experimental analysis, three HCQ degradation pathways were proposed. The analysis of T.E.S.T software showed that the toxicity of HCQ was obviously reduced after degradation. The LaCo_0.95Mo_0.05O₃-CeO₂/PMS system displayed excellent reusability and the ability to remove pollutants in a wide range of real-world aqueous environments, with the ability to treat a wide range of pharmaceutical wastewater. In summary, this study provides some ideas for developing heterogeneous catalysts for advanced oxidation systems and provide an efficient, simple, and low-cost method for treating pharmaceutical wastewater that has good practical application potential.