Preparation of metal organic framework materials and their adsorption performance for heavy metal Cr6+ ions in wastewater treatment process

Abstract

The heavy metal containing wastewater discharged from industries such as leather and smelting is toxic and difficult to degrade, which not only endangers human health but also causes serious damage to the ecological environment. The use of simple, efficient, and low-cost technologies to treat pollutants in such wastewater has gradually become a research focus both domestically and internationally. MOFs are cutting-edge porous solids that marry ultra-high surface areas and tunable porosity with architecturally adjustable frameworks and a wealth of open metal centers. They have broad development prospects in adsorption, separation, energy storage, catalysis, and other fields. Indium based MOF materials are composed of octahedral units formed by In3+ions connected to organic ligands, and have good structural and thermal stability. However, there is currently limited research on the preparation of In MOF series materials and their application in industrial wastewater pollutant treatment. Using sodium citrate as a modifier, the synthesized MIL-68 (In) was modified to obtain indium based material MIL-68 (In) - SC. The structural parameters of the modified material were measured to determine the appropriate concentration and dosage of the modifier. Introducing the modifier markedly expanded the scaffold’s surface; after dosing 0.2 mL of 0.5 M sodium citrate, MIL-68(In)-SC delivered a BET area of 1164.91 m² g⁻¹—56.6 % larger than its unmodified parent. The same trio of frameworks was then benchmarked for Cr(vi) sequestration from aqueous media.The results showed that all three materials had adsorption effects on heavy metal Cr6+ions, with adsorption rates and capacities of 30.05% and 24.04mg/g, respectively.