Study on adsorption extraction process of lithium ion from West Taijinar brine by shaped titanium-based lithium ion sieves

The demand for metal lithium and its compounds has increased in recent years especially in green energy technology. In this paper, adsorption equilibrium and kinetic performance of shaped titanium-based lithium ion sieve (HTO-P) for lithium ion (Li+) in Qinghai West Taijinar Salt Lake brine (abbreviated as West Taijinar brine) before and after ammonia (1 mol/L) were investigated. The results show that the equilibrium adsorption capacity of Li+ from West Taijinar brine after the adjustment of ammonia (abbreviated as West Taijinar brine-ammonia) by HTO-P is 19.22 mg/g at 30 °C with the solid/liquid ratio of 5 g/L for 24 h, which is 86.60% higher than that of West Taijinar brine. The separation factor α of HTO-P for Li+/Mg2+ in West Taijinar brine-ammonia is 1266.41. The equilibrium adsorption behavior of Li+ on HTO-P in West Taijinar brine and West Taijinar brine-ammonia can be described by the Freundlich model (the correlation coefficient R2 greater than 0.998). The adsorption kinetic performance of Li+ conforms to the Mixed Order kinetic model (MO) with R2 over 0.995. The adsorption mass transfer rate at the active site (h2′) greatly accelerated after adding NH3·H2O, which proves that the number of active sites raise after the increase of pH in West Taijinar brine. The H+ exchanged from HTO-P can be directly consumed by NH3·H2O, thus improving the mass transfer rate of Li+ and promoting the occurrence of ion exchange adsorption. This work provides basic data on the adsorption extraction process of lithium ion from brine with high Mg2+/Li+ ratio by the shaped titanium-based lithium ion sieve.