Selective adsorption of lithium from high Mg-containing brines using HxTiO3 ion sieve

Abstract

The prepared titanium type lithium ion sieve HxTiO3 are characterized and tested as adsorbents for selective adsorption of lithium from high Mg-containing brine. The maximum adsorption capacities of Li+, Na+, K+, Ca2+ and Mg2+ ions onto HxTiO3 reached 36.34, 1.93, 1.99, 2.58 and 3.53mg/g, respectively, under the initial pH8.8 at 25°C for 24h. Adsorption isotherms and kinetic analysis indicated that the adsorption of Li+ ions and other cations onto HxTiO3 followed Langmuir isotherm model and pseudo-second order kinetic equation. A diffusion model simulation showed that the Li+ ions had the highest external diffusion coefficients (7.7×10−2cms−1) while the other cations had small effect on the adsorption rate of Li+. The Biot number was >100 signified that these ions adsorption onto HxTiO3 were controlled by the internal diffusion. The separation factors (α) of Li+ over other cations were much >1. In particular, the α value of Li+ over Mg2+ reached 4783, indicating the high selectivity for Li+. In addition, the Li+ ion adsorption capacity kept constant during the six adsorption-desorption cycles and molar ratio of Mg to Li of eluents was as low as 0.08, indicating that the HxTiO3 ion sieve could effectively extract Li+ from the enriched brine.