Visible-light-driven photocatalytic degradation of chlortetracycline over PCN-222/Zn3In2S6 heterostructure: Elucidation of degradation mechanisms and ecotoxicological evaluation

To enhance photocatalytic activity, we focused on improving the efficiency of electron transport. A series of PCN-222/Zn3In2S6 composites was synthesized via combining a zirconium metal-organic framework (PCN-222) with Zn3In2S6 nanosheets with in situ growth methods. The optimized composite, designated as PCN-222/Zn3In2S6-2 (PCN/ZIS-2), showed the superior photocatalytic activity, achieving an 89% removal efficiency of chlortetracycline hydrochloride (CTC) in 180 minutes (kobs = 0.4748 min−1). Electron paramagnetic resonance (EPR) and free radical trapping experiments verified that superoxide anion (•O2−) and holes (h+) are the primary active species involved in the degradation process. Additionally, we analyzed the plausible degradation pathways of CTC through a liquid chromatograph-tandem mass spectrometer (LC–MS). An ecotoxicological assessment of byproducts from CTC implied that these degradation pathways can lower both acute and chronic toxicity. These results offer a promising approach for reducing antibiotic pollution in water and pave the way for developing efficient photocatalytic materials for environmental cleanup.