Efficient extraction of Uranium (VI) from aqueous solution by LDH/MOF composites

Abstract

Study on uranium adsorption materials is crucial in addressing uranium pollution and safeguarding water resources. In this paper, a novel Ni/Co-LDH@ZIF-67/8-MOF (LDH/MOF) composite was fabricated by loading ZIF-67/8-MOF on the surface of Ni/Co-LDH with silane coupling group as bonding agent. The LDH/MOF composite was tested by XRD, FT-IR, SEM, TGA, and XPS methods. The LDH/MOF composite exhibited exceptional uranium (U (VI)) adsorption capacity, with the Langmuir isotherm model estimating a maximum adsorption capacity of 617.33 mg/g, and the adsorption process followed quasi-second-order kinetics. Notably, ultrasonic mixing achieved equilibrium in a mere 5 minutes, outperforming traditional oscillation mixing by a considerable margin, offering new possibilities for enhancing uranium removal efficiency. Furthermore, thermodynamic analysis revealed the spontaneous and endothermic nature of U (VI) adsorption onto LDH/MOF. In addition, XPS investigations provided valuable insights into the adsorption mechanisms, primarily involving surface complexation, chelation, and ion exchange. These innovative findings open new avenues for the development of highly selective and efficient uranium separation methods, highlighting the promising potential of LDH/MOF as a highly prospective material for uranium separation in diverse applications, including environmental remediation and nuclear waste management.