Synthesis of core–shell magnetic metal organic framework composite for the efficient removal of uranium(vi)

Abstract

The combination of magnetic nanoparticles and metal–organic frameworks (MOFs) has demonstrated their potential for pollutant sequestration. In this work, Fe₃O₄@SiO₂@UiO-66 core–shell magnetic microspheres were synthesized and used for the removal of U(VI) from an aqueous environment. The characterization via transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA) and nitrogen adsorption porosimetry proved that the Fe₃O₄@SiO₂@UiO-66 core–shell nanocomposite was successfully prepared. Batch experiments were conducted to study the effects of initial pH, shaking time and temperature on the uranium sorption efficiency. The isotherm and kinetic data were accurately described by the Langmuir and pseudo-second-order models. The maximum adsorption capacity was calculated to be 616.5 mg g⁻¹ for U(VI) by fitting the equilibrium data to the Langmuir model. Various thermodynamic parameters were evaluated, which indicated the endothermic and spontaneous nature of adsorption. Thus, the excellent adsorption capacity and sensitive response of the Fe₃O₄@SiO₂@UiO-66 core–shell magnetic microspheres to a magnetic field make them a promising candidate for the removal of uranium(VI) from aqueous solutions.