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

Abstract

• Equilibrium uptake of Li + in West Taijinar brine with the addition of ammonia is up to 19.22 mg/g. • NH 3 ·H 2 O-NH 4 Cl buffer system can increase the number of active sites and accelerate H + /Li + exchange rate. • Adsorption uptakes of Na + , K + and Mg 2+ on HTO-P are poor (<0.1 mg/g) and α (Li + /Mg 2+ ) reaches 1266.41. • HTO-P could be used to the recovery of Li + from the brine with high Mg 2+ /Li + ratio. 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 + /Mg 2+ 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 R 2 greater than 0.998). The adsorption kinetic performance of Li + conforms to the Mixed Order kinetic model (MO) with R 2 over 0.995. The adsorption mass transfer rate at the active site (h 2 ′) greatly accelerated after adding NH 3 ·H 2 O, 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 NH 3 ·H 2 O, 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 Mg 2+ /Li + ratio by the shaped titanium-based lithium ion sieve.