Boosted photo-Fenton-like process for selective degradation of emerging contaminants by dehydrated Fe-based metal–organic framework with thermodynamically-favorable center metal electron density and confinement effect

Abstract

The Heterogeneous Fenton reaction has long stood out as a highly effective technology for water purification. However, it is nowadays facing challenges such as low selectivity, sluggish Fe(III) reduction, and limited H2O2 conversion efficiency. Herein, dehydrated MIL-100(Fe)-250 was synthesized through thermal treatment, demonstrating superior efficiency in removing emerging contaminants, with a three-fold efficiency higher than undehydrated sample. The dehydrated MIL-100(Fe)-250 exhibited selective acceleration in the removal of quinolones and phenolic organics, rendering the system resistant to interference from coexisting matter. Through in-situ diffuse reflectance infrared Fourier-transform spectroscopy and density functional theory calculation, it was manifested that dehydration process regulates the steric hindrance and local electron density of Fe ions. This adjustment enhances charge transfer, thereby facilitating Fe(III) reduction and promoting the H2O2 activation and conversion efficiency. Moreover, the quasi-steady-state concentrations of hydroxyl radical in MIL-100(Fe)-250 were found to be 2.2 times higher than that those in undehydrated sample. Impressively, the dehydrated MIL-100(Fe)-250 displayed adaptability across a broad pH range of 5.0–9.0. The present study underscores the significant potential of porous MIL-100(Fe)-250 with spatial confinement, which imparts a clear size exclusion effect. As a result, this catalyst emerges as a promising candidate for eliminating contaminants in real water matrices, offering a viable strategy for water pollution control.