Peculiar shuttle-like nano-sized TiO(OH)2/C lithium ion sieve with improved adsorption rate and cycling reliability: Preparation and kinetics

Abstract

The novel layered TiO(OH)2/C lithium ion sieve (LIS) with a higher adsorption rate, separation efficiency and excellent selective adsorption performance is prepared by loading shuttle-like nano-sized TiO(OH)2 grains onto the porous carbon membrane. It is shown that the layered TiO(OH)2/C LIS has rich pore structure, and the shuttle-like nano-sized TiO(OH)2 grains are evenly distributed onto the carbon membrane, resulting in the perfect exposure of the adsorption sites of the grain surface, and hence enhancing the solution mobility to facilitate the exchange of H+ and Li+. The kinetic studies show that the adsorption capacity of TiO(OH)2/C LIS can reach 80% of the equilibrium loading within initial ~2 h at varied process parameters. The adsorption follows pseudo-second order kinetic model, with a three-fold increase in rate from 6.7 × 10−2 g mg−1 h−1 to 1.8 × 10−1 g mg−1 h−1. At lower Li+ concentration, the adsorption rate increases significantly and the adsorption capacity can be improved by increasing the initial pH, the concentration of the lithium solution and the liquid-solid ratio. After 20 pickling-adsorption cycles, the adsorption capacity only loses 2%, indicating a better stability and recyclability.