Mixed imidazole ligand MIL-88A for enhanced photo-Fenton decomposition of azo dye

Abstract

In this study, we fabricated MIL-88A metal–organic frameworks with excellent physicochemical properties using mixed organic ligands. In addition, we investigated the effects of different iron precursors on the physicochemical properties of the as-prepared MIL-88A samples. We determined that the difference between the dissociation rates of the metal ions of different iron precursors affected the crystallization rate of MIL-88A, which effectively decreased particle size, causing an increase in the adsorption capacity of MIL-88A and significantly improving its photocatalytic activity. Two organic ligands: 2-methylimidazole and fumaric acid, were mixed, and the formed dihydrate affected the crystallization rate of MIL-88A; moreover, the as-fabricated MIL-88A presented small particle size and high oxidation potential. The as-prepared mixed organic ligand MIL-88A removed 96.42% of AR1 dye from an AR1 dye solution with a concentration of 20 mg/L after 2 h of irradiation. Furthermore, an AR1 dye removal of 100% was achieved after only 45 min of irradiation using a 100 mg/L AR1 dye solution in the presence of trace H2O2. The decomposition efficiency of MIL-88A did not decrease after five removal cycles, and this was attributed to the excellent decomposition efficiency of MIL-88A with mixed organic ligands, which was ascribed to its remarkable adsorption capacity and high oxidation potential. Strong oxidizing hydroxyl radicals were generated via a photo-Fenton reaction to improve the oxidative power of MIL-88A, and pollutants were decomposed without generating residues. We believe that these findings can be used to significantly expand the application of MIL-88A in photocatalysis research.