A novel BiOCl/GO/CoO Z-type heterojunction photocatalyst with ZIF-67 derivative modified for highly efficient degradation of antibiotics under visible light.

Levofloxacin (LVX) is difficult to be naturally degraded by microorganisms in water, and its residues in water will pose significant risks to human health and ecological environment. In this study, BiOCl was used as the main body, BiOCl/GO/CoO composite photocatalyst was prepared by pyrolysis of zeolitic imidazolate framework-67 (ZIF-67) combined with in-situ precipitation method and used to degrade LVX. A sequence of characterizations shows that addition of CoO and graphene oxide (GO) increases the visible light response range, improves the separation efficiency of photogenerated electrons and holes (e-h) of photocatalyst, and thus improves the degradation efficiency of LVX. Under the optimal reaction conditions, the LVX degradation rate of BiOCl/1.5GO/7.5CoO can reach 91.2 % at 120 min, and its reaction rate constant is the largest (0.0151 min), which is 2.17, 13.14 and 1.53 times that of BiOCl, CoO and BiOCl/7.5CoO, respectively, showing better photocatalytic performance. Simultaneously, the recycling stability of BiOCl/1.5GO/7.5CoO was also verified. The capture experiments and electron EPR test results showed that superoxide radicals (•O) and photogenerated holes (h) were the primary active substances in the reaction process. Finally, combined with HPLC-MS results, the photocatalytic degradation pathway of LVX was derived. This work will provide a theoretical basis for the design of Metal Organic Frameworks (MOFs)-derivative modified BiOCl-based photocatalysts.