Extraction of Lithium from Simulated Brine with a High Mg/Li Ratio Using NaNTf<sub>2</sub>· TBP System

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.