Effect of perfluoroalkyl chain length of an ionic liquid anion in the ionic liquid chelate extraction of trivalent lanthanoids

Eguchi, Ayano ; Okamura, Hiroyuki   ; Sugita, Tsuyoshi   ; Ueda, Yuki   ; Morita, Kotaro*; Shimojo, Kojiro   ; Naganawa, Hirochika  ; Hirayama, Naoki*

In this study, the effect of the perfluoroalkyl (Rf) chain length of the ionic liquid (IL) anion on the extraction of trivalent lanthanoid ions (Ln(III) = La, Nd, Eu, Dy, Lu) using 2-thenoyltrifluoroacetone was investigated. Four 1-butyl-3-methylimidazolium bis(perfluoroalkanesulfonyl)imides with different Rf chain length (n = 1-4) were synthesized and used as the extraction solvent. There was no significant difference in the extractability among ILs. The extracted species of each Ln(III) in these IL systems were investigated based on the slope of the plots of the logarithmic distribution ratio of Ln(III) as a function of aqueous phase pH. It was revealed that the extracted complex depends on even or odd number of the Rf chain length n.