Highly Selective Extraction and Separation of Rare Earths(III) Using Bifunctional Ionic Liquid Extractant

The extraction and separation of rare earths (REs) from nitrate medium or chloride medium using bifunctional ionic liquid extractants (Bif-ILEs) [trialkylmethylammonium][di(2-ethylhexyl)orthophosphinate] ([A336][P507]) and [trialkylmethylammonium][di-2-ethylhexylphosphate] ([A336][P204]) in n -heptane were investigated in this report. The separation factor (β) values indicated that [A336][P507] and [A336][P204] could be suitable for the separation of heavy REs(III) in nitrate medium and suitable for the separation of light REs(III) in chloride medium. Especially, in nitrate medium, the β values using [A336][P204] as the extractant were Tm/Er (3.36), Yb/Tm (7.92), and Lu/Yb (8.55), respectively, and in chloride medium, the β values using [A336][P507] as the extractant were Nd/Pr (9.52) and Sm/Nd (4.70), respectively. The β̅ z +1/ z values of REs(III) extracted by [A336][P507] and [A336][P204] in nitrate medium were 3.61 and 3.67, respectively, and in chloride medium, they were 2.75 and 2.59, respectively.