Enhanced Hg(II) efficient and selective removal by post-functional Ti-MOF with 2，5 thiophene dicarboxylic acid

Abstract

Toxic mercury ions in wastewater from industrial activities can wreak havoc on the natural environment and ecosystems. Adsorption treatment has been proved to be an effective measure to reduce mercury load in wastewater, but conventional adsorbents have lower adsorption performance. In this study, titanium-metal organic framework (Ti-MOF) was synthesized by solvothermal method, and then further modified by 2,5-thiophene dicarboxylic acid. In order to explore the morphology of the resulting material (OB-MIL-125 (Ti)) and the differences before and after modification, different characterization instruments have been employed. Meanwhile, the properties of materials at different pH were explored, and the adsorption capacity was deeply studied through thermodynamics, kinetics, and adsorption isotherms. The surface of OB-MIL-125 (Ti) had a rich pore structure, so the specific surface area is large, reaching 328.7 m2/g. At room temperature and pH= 5, the maximum removal rate of a 100 ppm solution reached 93.66%. The actual measured maximum adsorption capacity was 1435.98 mg/g. According to isotherm, kinetic and thermodynamic analysis, the process of removing Hg2+ was a multi-layer heterogeneous process, relying on chemical action for adsorption, and it was also a spontaneous exothermic process. The adsorbent presented excellent affinity for mercury and good regeneration ability. To sum up, the OB-MIL-125 (Ti) has great potential for remediation mercury-containing wastewater.