Synthesis of core–shell structure UiO-66-NH2@Ni-MOF composite for the effective removal of uranium (VI)

The core–shell structure UiO-66-NH2@Ni-MOF was prepared by in-diffusion growth of 2D Ni-MOF on UiO-66-NH2 using PVP (polyvinylpyrrolidone) as a structural guide. It was applied to the adsorption of U(VI) in aqueous solution. The materials were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectrometer (EDS). The UiO-66-NH2@Ni-MOF adsorption to U(VI) was investigated experimentally. The study showed that the adsorption of U(VI) onto UiO-66-NH2@Ni-MOF was endothermic and spontaneous. At pH 5.00 and 308 K, the adsorption capacity was 581.40 mg/g according to Langmuir model. In addition, the adsorption process can be described by the pseudo-second-order kinetic model. The adsorption capacity was kept at 83.83% of its original one after five sorption–desorption cycles, a promising indication for repetitive usage.