The Nitro-Modified NO2-MIL-53(Fe) Activating Persulfate for the Efficient Degradation of Tetracycline: Performance and Mechanism

Nitro-functionalized NO 2 -MIL-53(Fe) was synthesized by modifying MIL-53(Fe) to enhance persulfate activation for the degradation of tetracycline (TCN). Comparative studies with NH 2 -MIL-53(Fe) and pristine MIL-53(Fe), it was found that NO 2 -MIL-53(Fe) is categorized as an ideal type I isotherm, without observable hysteresis loop. The introduction of nitro-group incorporation significantly increased specific surface area clocking in at 298.3 m 2 /g and an average pore diameter of 3.3 nm, created uniform micropores, and improved adsorption capacity. Structural characterization confirmed Fe(II) generation and electron transfer in NO 2 -MIL-53(Fe), enabling 82.1% TCN removal within 30 min. Radical (SO 4 ·− , ·OH, O 2 ·⁻ ) and non-radical ( 1 O 2 , charge transfer) pathways synergistically drove degradation, as evidenced by quenching experiments and EPR analysis. ESI-Q-TOF MS identified key intermediates, proposing plausible TCN degradation pathways. This study highlights the potential of nitro-functionalized metal-organic frameworks (MOFs) in advanced oxidation processes, emphasizing their enhanced catalytic activity and performance mechanisms, and provides new ideas for the remediation of pollutants in water bodies. Graphical abstract