NH2-MIL-53(Al) Metal-Organic Framework as the Smart Platform for Simultaneous High-Performance Detection and Removal of Hg2.

The worsening pollution due to mercury species makes it inevitable to explore prospective versatile materials, which not only can detect mercury ions (Hg2+) with high sensitivity but also possesses efficient capture and removal ability. In this study, a series of classic organic ligand-based luminescence MOFs materials with high oxidation state central metals (Al3+, Zr4+, Cr3+, Fe3+, and Ti4+) were synthesized and were screened to achieve simultaneously Hg2+ detection and removal through the strong coordination of amino groups or nitrogen centers with Hg2+ and the intrinsic fluorescence intensity of MOFs regulated by the ligand-to-metal charge transfer (LMCT) effect. Among these checked materials, NH2-MIL-53(Al) exhibited the excellent ability for Hg2+ detection with wide response interval (1-17.3 μM), low detection limit (0.15 μM), good selectivity, wide pH adaptation (4.0-10.0), and strong anti-interference ability. Meanwhile, the resultant NH2-MIL-53(Al) possessed an efficient removal capability toward Hg2+, accompanied by a fast uptake kinetics (within 60 min) and large loading capacity (153.85 mg g-1). Furthermore, NH2-MIL-53(Al) also displayed satisfactory stability before and after Hg2+ treatment because of the formation of strong coordination bonds between high oxidation state aluminum (Al3+) and organic carboxylate ligands. Notably, the prepared NH2-MIL-53(Al) had no significant loss of adsorption performance even after being reused four times. All of these superior properties render the smart NH2-MIL-53(Al) nanohexahedron a great potential for simultaneous Hg2+ detection and removal from water.