Separation of lithium and nickel using ionic liquids and tributyl phosphate

With the vigorous development of the electronics industry, the consumption of lithium continues to increase, and more lithium needs to be mined to meet the development of the industry. The content of lithium in the solution is much higher than that of minerals, but the interference of impurity ions increases the difficulty of extracting lithium ions. Therefore, we prepared an imidazole-based ionic liquid (1-butyl-3-methylImidazolium bis(trifluoromethyl sulfonyl) imide) (IL) for efficient lithium extraction from aqueous solutions by solvent extraction. Using an extraction consisting of 10% IL, 85% tributyl phosphate (TBP), and 5% dichloroethane and an organic to aqueous phase ratio (O/A) of 2/1, over 64.23% of Li were extracted, and the extraction rate after five-stage extraction could reach more than 96%. The addition of ammonium ions to the solution inhibited the extraction of Ni, and the separation coefficient between lithium and nickel approached infinity, showing a very perfect separation effect. FTIR spectroscopy and slope methods were used to analyze the changes that occurred during extraction, revealing possible extraction mechanisms. In addition, the LiCl solution generated during the preparation of ionic liquids was mixed with the stripping solution, and the battery-grade lithium carbonate was prepared by Na2CO3 precipitation, with a purity of 99.74%. This study provides an efficient and sustainable strategy for recovering lithium from the solution.