Extraction of Lithium from Simulated Brine with a High Mg/Li Ratio Using NaNTf₂· TBP System

Abstract

NTf₂^--based ionic liquids (ILs)/tri-n-butyl phosphate (TBP) systems can be used for extraction of Li⁺, but ILs are very expensive and their cations can cause the contamination of the aqueous phase in the extraction process. In this study, an inexpensive raw material lithium bis(trifluoromethanesulphonyl)imide (LiNTf₂) is used to prepare extraction organic phase NaNTf₂·TBP, which can avoid the contamination of the aqueous phase in the extraction process. The preparation conditions of extraction organic phase NaNTf₂·TBP were investigated. The extraction conditions of NaNTf₂·TBP system were also studied, and under the optimal extraction condition, the single extraction efficiency of Li⁺ is 91.7%. The extraction system is stable after seven extraction cycles, and it has good prospects for application in extraction of Li⁺ from brine with a high Mg/Li ratio.