Structure–Activity Relationships of Fe-Based MIL Metal–Organic Frameworks in a Visible-Light-Driven Photo-Fenton System for Gatifloxacin Degradation and Detoxification

This study develops a visible-light-driven heterogeneous Fenton-like system for the efficient degradation and detoxification of the persistent fluoroquinolone antibiotic gatifloxacin (GAT) in water. Three Fe-based metal–organic frameworks (MIL-53(Fe), MIL-88A(Fe), and MIL-101(Fe)) were synthesized and systematically evaluated as catalysts in a visible-light/H2O2process. The three MOFs were systematically characterized, and a comparative analysis was conducted to elucidate how their structural differences influence catalytic performance. Among three MOFs, MIL-88A(Fe) exhibited superior photocatalytic activity, stability, recyclability, and low energy consumption in the visible-light-driven photo-Fenton process, which was attributed to its favorable structural and photo-induced redox properties. Under the optimal conditions (pH 7.2, H2O2dosage of 1.2 mL·L−1, and catalyst loading of 0.1 g·L−1), 95.6% of GAT was degraded within 90 min. Radical scavenging experiments demonstrated that hydroxyl radicals (•OH) dominated the oxidation process. Based on intermediate identification, plausible degradation pathways were proposed, accompanied by a pronounced reduction in the ecological risks of transformation products. Furthermore, toxicity assays revealed that both the antibacterial activity and acute toxicity of the treated solutions were significantly alleviated. Overall, the Light/MIL-88A(Fe)/H2O2system offers an effective and sustainable strategy for the removal and detoxification of fluoroquinolone antibiotics from aquatic environments.