Study on adsorption properties and DFT calculations using ethylenediamine-functionalized Zr-based MOF as adsorbent for Hg(II)

Abstract

Given the considerable toxicity of mercury and its persistent environmental presence, mercury pollution ranks among the most detrimental contaminants. In this study, thiol-functionalized zirconium-based metal-organic frameworks (MOF, UiO66-BAT-SH) were synthesized through click chemistry, and their potential for adsorbing Hg(II) ions from water was investigated. The composition, structure, and morphology of the adsorbent were characterized using scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). The adsorption performance and adsorption mechanism of the material were investigated. The best adsorption effect was obtained at pH 4, with a maximum removal efficiency of 97.2 % and an adsorption capacity of 243.1 mg/g. The adsorption obeyed the proposed two-stage kinetic model, and the Langmuir isotherm model was in good agreement with the experimental isotherm. Density functional theory (DFT) calculation revealed that the adsorption of Hg(II) on UiO66-BAT-SH depends on electron exchange, electron sharing, electrostatic, and covalent interactions between metal ions. In conclusion, UiO66-BAT-SH demonstrated stability and recyclability, highlighting its potential as an adsorbent for Hg(II) remove.