Synthesis of rod-like metal-organic framework (MOF-5) nanomaterial for efficient removal of U(VI): batch experiments and spectroscopy study

With the widespread application of radionuclide U-235(VI), it is inevitable that part of U(VI) is released into the natural environment. The potential toxicity and irreversibility impact on the natural environment has become one of the most forefront pollution problems in nuclear energy utilization. In this work, rod-like metal-organic framework (MOF-5) nanomaterial was synthesized by a solvothermal method and applied to efficiently adsorb U(VI) from aqueous solutions. The batch experimental results showed that the sorption of U(VI) on MOF-5 was strongly dependent on pH and independent of ionic strength, indicating that the dominant interaction mechanism was inner-sphere surface complexation and electrostatic interaction. The maximum sorption capacity of U(VI) on MOF-5 was 237.0 mg/g at pH 5.0 and T = 298 K, and the sorption equilibrium reached within 5 min. The thermodynamic parameters indicated that the removal of U(VI) on MOF-5 was a spontaneous and endothermic process. Additionally, the FT-IR and XPS analyses implied that the high sorption capacity of U(VI) on MOF-5 was mainly attributed to the abundant oxygen-containing functional groups (i.e., C-O and C=O). Such a facile preparation method and efficient removal performance highlighted the application of MOF-5 as a candidate for rapid and efficient radionuclide contamination's elimination in practical applications. (C) 2018 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.