Enhancing degradation of norfloxacin using chrysanthemum-shaped bimetallic NH₂-MIL-53(Fe/Ti) photocatalysts under visible light irradiation

The presence of elevated levels of norfloxacin (NOR) in the aquatic environment presents a serious risk to both human health and environmental organisms due to its extremely toxic and persistent characteristics. Herein, a series of Fe/Ti bimetallic composites (NH2-MIL-53(Fe/Ti)) were prepared using a one-step hydrothermal method to assess their capability for NOR degradation and investigate degradation mechanisms. It was observed that the well-organized nanosheets interconnected to form chrysanthemum clusters contained a significant number of exposed edges and open pores, which facilitated the enrichment of NOR. Notably, the optimum NH2-MIL-53(Fe/Ti) (1.5:1) demonstrated excellent degradation performance for NOR under visible light, owing to an electronic interaction between Fe3+ and Ti4+ metal centers. Efficient NOR degradation by NH2-MIL-53(Fe/Ti) (1.5:1) was achieved at 84.6% after 120 min of irradiation. Furthermore, the NH2-MIL-53(Fe/Ti) (1.5:1) maintained excellent reusability and stability even after five cycles tests. Active species trapping experiments confirmed that the pivotal role of center dot O-2(-) and h(+) in photodegradation of NOR pollutants. A plausible photocatalytic mechanism was suggested according to various performance characterization and experimental results. Defluorination and ring opening were the main degradation pathways. This work advanced our understanding of photogenerated carriers transfer and energy conversion in bimetallic MOFs. Additionally, a novel strategy was presented for visible light catalytic degradation of NOR, which were highly relevant for the field of environmental treatment.