Efficient degradation of chloroquine phosphate by peroxymonosulfate activated using reusable lanthanide cobalt-copper perovskite-cerium dioxide composite catalyst: Performance, mechanism and degradation pathway

In recent years, chloroquine phosphate (CQP) has been widely used as a specific drug for treating COVID-19. Because of its biological toxicity, the release of CQP into water is bound to have a potential impact on human health. It is urgent to find a reusable and efficient catalyst to treat a large number of CQP wastewater. Currently, perovskite-type catalysts are gradually entering the field of advanced oxidation process, but there are still some problems such as high particle aggregation and limited reaction contact. Here, LaCo0.5Cu0.5O3-CeO2 was prepared by sol-gel method and used to activate peroxymonosulfate (PMS) to degrade CQP for the first time. The LaCo0.5Cu0.5O3-CeO2 material has better stability, larger specific surface area and more uniform pore structure. Under the conditions of 0.2 g/L catalyst and 1.0 mM PMS, 20 mg/L CQP can be completely degraded within 8 min and is suitable for a wide pH range and complex water quality. Superoxide free radical (·O2-) and the singlet oxygen (1O2) are the main free radicals to degrade CQP. The addition of CeO2 makes Ce4+/Ce3+ participate in the redox cycles between Co3+/Co2+ and Cu2+/Cu+, realizing the multipath electron transfer. In addition, LaCo0.5Cu0.5O3-CeO2/PMS system can degrade CQP into low toxicity products through different pathways, ultimately mineralizing it into inorganic small molecules. In general, LaCo0.5Cu0.5O3-CeO2 has more reasonable structure, efficient and durable catalytic performance, anti-interference ability and low ion leaching level, which provides a new idea for preparing heterogeneous catalyst to activate PMS to treat pharmaceutical wastewater, and has broad practical application prospects.