A Comprehensive Study on Solvent Extraction of Lithium Ion from Aqueous Solution and Its Application in Seawater

Abstract

Solvent extraction of lithium ion using kerosene as a solvent was proposed. The extraction of lithium ion using various mixed extractants of β-diketone and neutral ligand in kerosene was performed to find the suitable extractant combination. Considering the extraction efficiency, the suitable extractant combination was 0.02 M TTA and 0.04 M TOPO. For the development of lithium extraction process from seawater, the effects of dominant ions in seawater were examined in various extraction conditions. The extraction efficiencies generally decreased with increasing the concentration of dominant metallic ions and increased with increasing the pH of the aqueous solutions, but Cl- ion showed only minor effect on the efficiency even up to its concentration in seawater. Except for Mg2+ ion, more than 70% of lithium ion could be extracted at pH 10.6 from aqueous solutions with a dominant ion at its concentration in seawater. Extraction efficiency severely influenced by stoichiometric parameters. Among the stoichiometric parameters, volume ratio [A/E] was the most influential parameter. After extraction, lithium ion could be easily stripped from the extraction solution by using acidic solutions. Stripping efficiency decreased with a pH of acidic solutions, and the kind of acid did not affect on the stripping efficiency. Extraction efficiency has maintained more than 90% even when the extraction solution recycled three times. Even though magnesium ion was precipitated by NH4OH prior to solvent extraction process, 64% of lithium ion could be extracted from seawater by this solvent extraction process.