Defect modulation of MIL-53(Fe) by Ce doping for PMS activation on the degradation of tetracycline: Singlet oxygen and electron transfer

Abstract

Removal of organic pollutants through the activation of peroxymonosulfate (PMS) using metal-organic frameworks (MOFs) has exhibited great potential in wastewater treatment. In this study, a one-step solvothermal method was employed to synthesize Ce-doped MIL-53(Fe) which was subsequently utilized to activate PMS for the degradation of tetracycline (TC). Morphology, crystal structure, and chemical valence of MIL-53 (Fe/Ce) were characterized in scientific detail. Fe/Ce molar ratio revealed that 5% Ce-doped MIL-53(Fe) effectively activated PMS, achieving a remarkable 94% TC removal within 7 min. The introduction of Ce not only distorted the MIL-53(Fe) crystals and induced a greater number of oxygen vacancy defects, but also improved the electron transfer capacity, which facilitated active site exposure and PMS activation. MIL-53(Fe0.95Ce0.05) maintained high catalytic activity under various pH levels and coexisting substance conditions. The degradation mechanism within the MIL-53(Fe0.95Ce0.05)/PMS system was a synergistic interaction of radicals and non-radicals, with the non-radical action of 1O2 and electron transfer dominating. Additionally, toxicity predictions were made in conjunction with possible degradation pathways and the reacted solutions were used for practical biotoxicity assessments. This work offers a new perspective for promoting the application of Fe-MOFs materials in environmental pollution remediation.