Experimental and molecular simulation studies on adsorption and diffusion of elemental mercury in flexible UiO-66

Abstract

• Adsorption and diffusion of Hg 0 in UiO-66 was investigated by molecular simulations combined with experiments. • A good agreement was obtained between experimental data and molecular simulations. • The dynamical and structural properties of Hg 0 in UiO-66 were used to interpret the adsorption mechanism. Adsorption of elemental mercury (Hg 0 ) in flue gas using the porous materials is a promising technology. We conducted the molecular simulations and experiments of the adsorption and diffusion of Hg 0 in UiO-66 at 393 K. The calculated adsorption isotherms using GCMC simulation are in good agreement with the experimental data. The flexible force field for UiO-66 is reasonable for the study of the thermodynamic and dynamic properties of Hg 0 in this structure. The free energy and density distribution of Hg 0 were performed, and showed that Hg 0 was preferentially located in the tetrahedral cages in UiO-66. The dynamic properties of the Hg 0 in the flexible UiO-66 were studied by molecular dynamics. The diffusion mechanism can be explained by the inter-cage hopping events. A lower decay of the VACFs for Hg 0 in the flexible UiO-66 was observed at the higher loading. Further analysis of the radial distribution functions, Hg 0 molecules are found with higher probability near the O1 atoms of the tetrahedral cage in the framework. Based on structural and dynamics properties, we achieve a fundamental insight into adsorption mechanism. We anticipate these results could provide insights into the adsorption and diffusion of Hg 0 for the development of new porous materials.