Structure–activity relationship in periodate activation by Fe–MOFs: Why MIL-101(Fe) outperforms other MIL-series in antibiotic degradation
Ning Liu, Jingwen Xu, Yixuan Zhai, Ziyi Zhang, Yi Dang, Yusong Cao, Yiran Li, Wenyuan Huang, Xiaodong Zhang, Liang Tang
Abstract
Antibiotics are emerging pollutants that pose significant risks to environmental and human health. Periodate (PI)-based advanced oxidation processes have shown promise for their effective degradation. In this study, we systematically investigate the structure–activity relationship of four representative Fe-based metal-organic frameworks (Fe-MOFs)—MIL-101(Fe), MIL-88B(Fe), MIL-88A(Fe), and MIL-53(Fe)—as PI activators for tetracycline (TC) degradation. Among them, MIL-101(Fe) exhibited the highest catalytic performance, owing to its unique Fe 3 O-OH nodes and mesoporous architecture. The MIL-101(Fe)/PI system achieved 93.3% TC degradation and 55.9% mineralization rate within 60 minutes. Mechanistic studies combining scavenger quenching, sulfoxide probe transformation, X-ray photoelectron spectroscopy, and X-ray absorption fine structure confirmed the generation of multiple reactive oxygen species, and high-valent Fe(IV)=O and O 2 ·- played major roles in the tetracycline degradation process. Density functional theory calculations further revealed that MIL-101(Fe) and MIL-88B(Fe) effectively interact with PI to form Fe(III)-superoxide (Fe(III)-O-O ·- ), a key intermediate in Fe(IV)=O generation. In contrast, the adsorption energy of MIL-53 (Fe) and MIL-88A (Fe) was relatively weak, with fewer binding sites, resulting in poor performance. The synergy between Fe(III)-O-O ·- formation and the pore accessibility of MIL-101(Fe) accounted for its superior catalytic efficiency. This work not only clarifies the structural factors governing PI activation in Fe-MOFs, but also proposes a mechanistically informed strategy for designing high-performance catalysts for antibiotic degradation. MIL-101 (Fe) can effectively interact with PI to form Fe(III)-O-O · ⁻ due to its unique Fe 3 O-OH nodes. The synergy between Fe(III)-O-O · ⁻ formation and the pore accessibility of MIL-101(Fe) accounts for its superior tetracycline degradation rate. • The unique Fe 3 O-OH in MIL-101(Fe) interacts with periodate to form Fe(III)-O-O˙ - . • Fe(III)-O-O˙ - and pore structure of MIL-101(Fe) contribute to its best catalytic activity. • Fe(IV)=O is identified as a new reactive species in MIL-101 (Fe)/PI system. • Fe(III)-O-O˙ - is the key species for generating Fe(IV)=O, ·OH and O 2 · - .