Enhanced adsorption of uranium (VI) using a three-dimensional layered double hydroxide/graphene hybrid material

This study presents a facile route for the fabrication of a hierarchical three-dimensional composite (layered double hydroxide/graphene). The composite was obtained via in situ growth of layered double hydroxide (LDH) nanosheet arrays onto graphene sheets. The materials were characterized by transmission electron microscopy, scanning electron microscope, Fourier-transform infrared spectroscopy, X-ray diffraction and Brunauer–Emmett–Teller surface area measurement. This particularly structured composite has a large specific surface area and typical mesoporous characteristics, which are favorable for achieving high adsorption performance. The influence of conditions for uranium adsorption, including pH of aqueous solution, adsorbent dose, shaking time, and temperature were investigated. The results reveal that the maximum adsorption capacity of the layered double hydroxide/graphene toward uranium (VI) is 277.80 mg g−1, displaying a high efficiency for the removal of uranium (VI) from aqueous solution. The thermodynamic parameters, such as ΔH°, ΔS°, and ΔG° show that the process is endothermic and spontaneous. The kinetic adsorption can be described by a pseudo-second-order rate equation. This work describes an efficient, fast, and convenient approach for the removal of uranium (VI) from aqueous solutions.