Microwave catalytic degradation of tetracycline using Van modified Fe-MOF: regulation of defect engineering and its performance under microwave irradiation

Abstract

This study demonstrates a defect engineering approach to synthesize vanillin (Van)-modified Fe-MOF (FBV_x, where x represents the molar ratio of Van to H₂BDC) featuring a unique non-carboxylic ligand architecture for microwave (MW)-assisted degradation of tetracycline (TC). The optimized FBV_0.4 exhibits exceptional performance with which the degradation ratio of TC exceeds 98% in 10 min. Characterization and the experimental results reveal its enrichment of unsaturated Fe sites (Fe(CUS)), surface oxygen vacancies (OVs), and the presence of a multi-level pore structure. Under MW irradiation, Fe(CUS) serve as active centers, facilitating the adsorption and activation of the reactants. OVs can alter the electronic structure of the material, enhance its response to microwaves, and improve its catalytic activity. The multi-level pore structure provides a large specific surface area and abundant diffusion channels, facilitating the contact between TC molecules and the active sites. Iron quantum dots and the multi-level pore structure could induce near-field enhancement or plasmon resonance energy transfer (PRET), promoting electron transfer. Quenching experiments indicate that the primary active species are ˙OH, ˙O₂⁻, and h⁺. Notably, the required dosage of this catalyst is low, while its pH adaptation range is broad. It also exhibits strong anti-interference capabilities and can maintain good activity even after 5 cycles. This paper proposes a research approach for preparing high-performance Fe-MOF MW catalysts with abundant defect vacancies and a multi-level pore structure.