A novel Zr-MOF modified by 4,6-Diamino-2-mercaptopyrimidine for exceptional Hg (II) removal

Due to natural and production activities, mercury contamination has become one of the major environmental problems in the world. Adsorption is one of the important means to solve this problem. However, most of the commercially available adsorbents exhibit relatively low adsorption capacity and slow kinetics. Therefore, a novel 4,6-diamino-2-mercaptopyrimidine-functionalised Zr-based metal-organic framework (UiO-66-DMP) was synthesised in this study. The UiO-66-DMP was characterised through X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, X-ray photoelectron spectroscopy, Fourier-transform infrared spectrometry, and thermogravimetric analysis. The potential of the UiO-66-DMP as a superior adsorbent for Hg(II) removal and the corresponding mechanisms were evaluated through batch experiments under different conditions and density functional theory calculations. Benefitting from its high specific surface area and multiple adsorption sites, the maximum Hg(II) adsorption capacity achieved in this study was 822.00 mg·g-1, which is the highest Hg(II) adsorption capacity reported to date. In addition, under the interference of Ca(II), Cd(II), Co(II), Mg(II), Mn(II), Ni(II), Cr(III), Cu(II), Zn(II) and other coexisting ions, the UiO-66-DMP could still maintain the high selective adsorption capacity for Hg(II). According to the characterization analysis and DFT calculation results, the adsorption of Hg(II) onto the UiO-66-DMP was dependent on electrostatic and covalent interactions between metal ions and abundant functional groups on the UiO-66-DMP surface. [Display omitted] •A novel adsorption material of Hg(II) modified by 4,6-Diamino-2-mercaptopyrimidine has been successfully constructed.•Uio-66-DMP has a high adsorption capacity of 822 mg·g−1 for Hg(II).•The multiple N groups and S groups are beneficial to improve the adsorption performance and selectivity of Hg(II).