Effect of nickel ion doping in MnO2/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-MnO2) adsorbents were fabricated via a hydrothermal approach. The reduction of graphite to graphene oxide (GO), formation of α-MnO2, and decoration of Ni-MnO2 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-MnO2 (63 mg g-1) > RGO/Ni2-MnO2 (56 mg g-1) > RGO/Ni1-MnO2 (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-MnO2 exhibited the greatest potential for Li+ uptake from aqueous solutions as compared to others.

Synthesis and electroluminescent properties of new conjugated bithiazole-containing polymers.

Three new bithiazole-based conjugated copolymers were synthesized and characterized. The EL device using PNBTV as the emitting layer showed red electroluminescence at 641 nm with a peak luminance of ca. 160 cd/m2 (0.008 cd/A). The red electroluminescence was attributed to the formation of excimers between the polymer chains. An EL device using PNBTV6 as the emitting material, which had two n-hexyl groups introduced to the phenylene in the main chain of PNBTV, showed a reddish orange emission that was blue shifted by approximately 52 nm compared with that observed with PNBTV. This observation was attributed to the significant decrease in interactions between the chains of the polymers due to the two bulky n-hexyl groups. On the other hand, PNBTV6 was found to have superior hole transporting ability compared with its electron transporting ability.