Amino-Functionalized MOF-Derived MXene Decorated with 3D Aerogel Network for Efficient Capture Capability and Separation of Mercury(II)

Mercury pollution poses a substantial threat to human health and the ecological environment, with the predominant source being the discharge of Hg 2+ from industrial wastewater. Adsorption is considered one of the most promising technologies for the removal of Hg 2+ from wastewater. In this work, a millimeter-scale bead-type composite adsorbent, denoted as MIL-101-NH 2 @MXene/SA-Ca 2+ -PAA (MNM-ACP) beads, was fabricated through the in situ synthesis of amino-functionalized MIL-101 on MXene, followed by its incorporation into the ACP 3D aerogel network. The maximum Hg 2+ adsorption capacity reached 288.8 mg g –1 at an initial Hg 2+ concentration of 300 mg L –1 under the conditions of pH 5 and 45 °C. Combining kinetic and isotherm model fitting with characterization analyses revealed that the primary mechanisms for Hg 2+ adsorption onto MNM-ACP beads involve coordination, surface complexation, electrostatic interaction, and ion exchange. Thermodynamic analysis revealed positive ΔH and negative ΔG values, indicating that the adsorption process was spontaneous and endothermic. In addition, the MNM-ACP beads exhibited high selectivity, excellent resistance to ionic interference, and maintained over 75% of their initial adsorption capacity after five adsorption–desorption cycles. The dynamic adsorption behavior in the fixed-bed column was well described by the Yoon-Nelson model. This strategy achieves efficient Hg 2+ removal while addressing the practical issues of inconvenient handling and difficult recovery associated with conventional powdered adsorbents.