Selective recovery of lithium from aqueous solution with hydrophobic deep eutectic solvent based on quantum chemical calculations and experimental investigation

Abstract

Developing green and efficient extractants for selectively recovering lithium from salt lake brine is beneficial for alleviating the increasingly growing demand for lithium resources. This study developed a novel hydrophobic deep eutectic solvent (HDES) for selective recovery of Li+ from simulated salt lake brine solutions. Under the optimal experimental parameters, the single extraction efficiency of Li+ was 70.18 %, β (Li+/ Na+) and β (Li+/Mg2+) were 22.32 and 947.58, respectively. Cycle experiments verified the high stability and good cycle performance of HDES. The conditions affecting the extraction efficiency of Li⁺ were optimized through experiments, and the high stability and good cyclic performance of HDES were verified. The extraction ability and mechanism of HDES for different metal ions were studied based on FTIR spectra combined with density functional theory. The calculation results showed that the order of extraction capacity of HDES for metal ions was: Li+>Na+>Mg2+. This calculation results were identical to the experimental results. This research will help develop HDES for the selective recovery of lithium from aqueous solutions containing high concentrations of Mg2+, helping to address the urgent global demand for lithium resources.