Effect of nickel ion doping in MnO(2)/reduced graphene oxide nanocomposites for lithium adsorption and recovery from aqueous media

Novel and effective reduced graphene oxide–nickel (Ni) doped manganese oxide (RGO/Ni-MnO(2)) adsorbents were fabricated via a hydrothermal approach. The reduction of graphite to graphene oxide (GO), formation of α-MnO(2), and decoration of Ni-MnO(2) onto the surface of reduced graphene oxide (RGO) were independently carried out by a hydrothermal technique. The physical and morphological properties of the as-synthesized adsorbents were analyzed. Batch adsorption experiments were performed to identify the lithium uptake capacities of adsorbents. The optimized parameters for Li(+) adsorption investigated were pH = 12, dose loading = 0.1 g, Li(+) initial concentration = 50 mg L(−1), in 10 h at 25 °C. It is noticeable that the highest adsorption of Li(+) at optimized parameters are in the following order: RGO/Ni3-MnO(2) (63 mg g(−1)) > RGO/Ni2-MnO(2) (56 mg g(−1)) > RGO/Ni1-MnO(2) (52 mg g(−1)). A Kinetic study revealed that the experimental data were best designated pseudo-second order for each adsorbent. Li(+) desorption experiments were performed using HCl as an extracting agent. Furthermore, all adsorbents exhibit efficient regeneration ability and to some extent satisfying selectivity for Li(+) recovery. Briefly, it can be concluded that among the fabricated adsorbents, the RGO/Ni3-MnO(2) exhibited the greatest potential for Li(+) uptake from aqueous solutions as compared to others.