Improving water stability and photocatalytic activity of MIL-101(Fe) via in-situ modification strategy

Abstract

Iron-based metal-organic frameworks (MOFs) represent a potentially important tool for controlling organic pollutants. However, the structural stability of most iron-based MOFs in the aqueous environment is limited. Therefore, this study sought to improve the aqueous stability and photocatalytic activity of MIL-101(Fe) using an in-situ modification strategy. A novel and highly water-stable MIL-101(Fe)@IPA4 was prepared using ligand regulation. Owing to the in-situ modification effect, MIL-101(Fe)@IPA4 exhibited remarkable hydrophobicity with a water contact angle at 102.4° while maintaining minimal leaching of iron ions (0.46 mg/L), even after five cycles of photocatalysis. Under MIL-101(Fe)@IPA4/UV/H2O2 conditions, the removal rates of ciprofloxacin and total organic carbon reached 100% and 49.16%, respectively, within 60 min. These researches suggest that introducing IPA improves the light absorption properties of MIL-101(Fe)@IPA4 and facilitates electron-hole separation, thereby promoting the generation of active species. The ecotoxicity assessment of major degradation intermediates of ciprofloxacin was conducted using the ECOSAR system. Our findings provide novel insights for enhancing the water stability of iron-based MOFs through an in-situ modification strategy, which is crucial for pollution control efforts.