(275e) Recovery of Lithium Ion from Salt-Lake Brines Via Solvent Extraction with [Emim][Fsi] As Coextractant

Recovery of lithium ion from salt-lake brines was explored by solvent extraction with tributyl phosphate (TBP) as extractant, dimethyl phthalate as diluent and ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([Emim][FSI]) as coextractant. Effects of volume concentrations of TBP, molar ratios of [Emim][FSI] to Li, and volume ratios of the organic phase to the aqueous phase on extraction performances of lithium ion were investigated. The extraction efficiency and distribution coefficient of lithium ion reached to 81.3% and 4.37 under the optimal conditions (volume concentration of TBP = 60%, molar ratio of [Emim][FSI] to Li = 3:1, volume ratio of the organic phase to the aqueous phase = 1:1). Meanwhile, the separation factors of Li/Mg, Li/Na and Li/K were 199, 44 and 301, respectively. In addition, the extraction efficiency of lithium ion could reach to 99.7% after four stages cross current solvent extraction. Moreover, the reusability of extraction system (TBP+[Emim][FSI]+dimethyl phthalate) was studied too. The results showed that the ionic liquid [Emim][FSI] was a suitable and stable coextractant for replacing FeCl₃ in recovery of lithium ion from salt-lake brine via solvent extraction.