Effect of nickel ion doping in MnO/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) adsorbents were fabricated a hydrothermal approach. The reduction of graphite to graphene oxide (GO), formation of α-MnO, and decoration of Ni-MnO 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, 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 (63 mg g) > RGO/Ni2-MnO (56 mg g) > RGO/Ni1-MnO (52 mg g). 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 exhibited the greatest potential for Li uptake from aqueous solutions as compared to others.