Linker regulation of iron-based MOFs for highly effective Fenton-like degradation of refractory organic contaminants

Abstract

Iron-based MOFs with tunable structure, large surface area along with attractive diversity have been often used in heterogeneous Fenton-like reactions to generate hydroxyl groups for the degradation of new pollutants. It is unclear how linker substituents of MIL-101 with MTN-typed topology influence the heterogeneous Fenton. Solvothermal methods were used to successfully synthesize a series of MIL-101-X(Fe) with various substituents (X = -H, –NH₂, –OH and –OCH₃) in the side chains of organic ligands. Their physicochemical properties are fully investigated by various characterizations, which confirmed that changes in the substituents affected crystal morphology and thus catalytic efficiency. In the Fenton system, MIL-101-X showed significant differences in antibiotics removal. Particularly, the MIL-101-NH₂ exhibited 100 % removal of SMX within 70 mins, with a rate of 30.06 times faster than MIL-101-H. This was related to the change in the active surface, following ligand functionalization, which greatly facilitates the dissociation of H₂O₂ and accelerates the iron cycling process. Therefore, this study provides the first mechanistic foresight on the regulation of Fenton-like reactions through modifying the substituents in the side chain of MOFs to alter their particle morphology and active surface.