Study on metronidazole degradation using peroxymonosulfate activated by ZnO_1-x/CuO_1-x with abundant oxygen vacancy

Metronidazole (MNZ), a pollutant in water, is highly soluble and difficult to biodegrade. Therefore, advanced oxidation technology based on peroxymonosulfate (PMS) activation is a water treatment technology suitable for degrading metronidazole. CuO is a commonly used PMS activation material, but due to its low activation efficiency, its activation effect can be improved by constructing a high-concentration oxygen vacancy (OV). The phenomenon of lattice mismatch at heterogeneous interfaces can elevate the OV content in materials. This study synthesized OV-rich ZnO_1-x/CuO_1-x using homogeneous precipitation, air calcination, and vacuum calcination. Experimental findings demonstrate that ZnO_1-x/CuO_1-x can completely degrade metronidazole (MNZ) within 14 minutes. XPS and EPR results corroborate the increase in OV content. Analysis of active species reveals that the degradation mechanism primarily follows a non-radical pathway, with singlet oxygen (¹O₂) playing a dominant role. This research presents a novel strategy for producing a cost-effective and straightforward catalyst that enhances the non-radical activation process of PMS through defect engineering.