Solvent extraction of lithium from aqueous solution using an ammonium ionic liquid

A new functionalized ionic liquid (FIL), tetrabutylammonium 2-ethylhexyl hydrogen-2-ethylhexylphosphonate ([N4444][EHEHP]), was prepared and used in the extraction of lithium ion from aqueous solution. The factors affecting the extraction efficiencies, such as aqueous acidity, extractant concentration and temperature, were optimized. The mechanism involved in the extraction system was analyzed by slope analysis and FT-IR data. According to the Van't Hoff equation, the thermodynamic functions of the extraction reaction in ionic liquid system were obtained. Liquid/liquid extraction tests indicated that the ionic liquid system exhibited better selectivity towards lithium ions in the solution containing alkali metal ions. In addition, the quantitative stripping of lithium ions from the loaded ionic liquid phase was carried out and the effect of hydrochloric acid concentration on stripping rate was investigated in detail. •A new functionalized ionic liquid was successfully synthesized and used for lithium extraction.•Nature of extracted species was found out to be 1:1.•The ionic liquid system exhibited better selectivity towards lithium ions in the solution containing alkali metal ions.