Enhanced performance of functionalized MOF adsorbents for efficient removal of anthropogenic Hg(II) from water

Heavy metal pollution in water has been an increasing global environmental problem in recent years. At present, Zr-MOF-NAC has been successfully synthesized and used to efficiently capture mercury ions from wastewater. FESEM, XRD, FTIR and BET were applied for routine characterization. The best adsorption effect of Zr-MOF-NAC was obtained at pH = 5.0, and the maximum adsorption capacity was up to 644 mg/g. The adsorption kinetics and isotherms showed that the adsorption process was consistent with Elovich kinetic model and Temkin isotherm model. Chemisorption is the main adsorption behavior in the reaction process, and film diffusion is the limiting step of reaction rate. In addition, the adsorbent has excellent selectivity and reusability, and can selectively adsorb mercury ions in the solution containing interference ions. At the same time, after four adsorption-desorption experiments, the removal rate only decreased by 5%. The adsorption mechanism was revealed by XPS and other characterization methods, which mainly depended on electrostatic interaction and chelation, in which chemisorption was dominant, namely the interaction between the functional groups containing S, N and Hg(Ⅱ).