title: Solvent extraction of rare-earth ions based on functionalized ionic liquids.
abstract: Three functionalized ionic liquids (ILs), tetrabutylammonium di(2-ethylhexyl)phosphate ([TBA][DEHP]), trioctylmethylammonium di(2-ethylhexyl)phosphate ([TOMA][DEHP]), and trihexyl(tetradecyl)phosphonium di(2-ethylhexyl)phosphate ([THTP][DEHP]), are synthesized and characterized. These ILs are used as DEHP-based ionic extractants and are investigated for rare earth elements (REEs) separation in 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C(6)mim][NTf(2)]) and diisopropylbenzene (DIPB) along with di(2-ethylhexyl)phosphoric acid (HDEHP). Solubilities of the DEHP-based ionic extractants in [C(6)mim][NTf(2)] are much better than that of HDEHP in [C(6)mim][NTf(2)]. We herein report the achievement of enhanced extractabilities and selectivities for separation of REEs using DEHP-based ionic extractants in [C(6)mim][NTf(2)]. This work highlights the potential of developing a comprehensive ionic liquid-based extraction strategy for REEs using ionic liquids as both extractant and diluent.
authors.affiliation: Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6201, USA.
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Sun
authors.forename: Huimin
authors.initials: H
authors.lastname: Luo
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D052578:Ionic Liquids / Q000737:chemistry*; D008674:Metals, Rare Earth / Q000737:chemistry* / Q000302:isolation & purification*; D015394:Molecular Structure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*
chemical_list: D052578:Ionic Liquids; D008674:Metals, Rare Earth; D000644:Quaternary Ammonium Compounds; D012997:Solvents; C037759:trioctylmethylammonium; C009405:tetrabutylammonium