The Preparation of a Robust Pyrazolate-based Metal-Organic Framework by γ-irradiation for Efficient Uranium Adsorption

The research for highly removal of uranium from nuclear waste is of significance for radionuclide remediation and environment. Herein, a robust pyrazolate-based metal-organic framework (NiBTP) is prepared by γ-irradiation through complexation between 1,3,5-tris(1H-pyrazol-4-yl) benzene (H 3 BTP) and Nickel (II) and presents efficient U(VI) adsorption performance. The synthesized NiBTP is characterized by XRD, FTIR, SEM, TEM, XPS and N 2 adsorption–desorption isotherm analysis. Structural characterizations demonstrate that NiBTP prepared by γ-irradiation possesses decreased BET surface area with hierarchical pore structure, but also has excellent crystallinity and high chemical stability. Batch experiments reveal that NiBTP adsorbent displays high adsorption capacity of uranium and excellent selectivity for UO 2 2+ ion in the presence of competing K + , Cs + , Sr + , Co 2+ , Mg 2+ , Ca 2+ , La 3+ and Eu 3+ ions. Thermodynamic investigation shows the adsorption process is endothermic and spontaneous. In addition, the adsorption mechanism of UO 2 2+ ion onto NiBTP is attributed to the hierarchical pore architecture as well as complexation. This study presents a simpler and more efficient alternative method for the preparation of pyrazolate MOFs and highlights the power of robust pyrazolate MOFs in sequestrations of radioactive pollutants from water environment.