Synergistic solvent extraction of lanthanide ions with mixtures of D2EHPA and MIDPA in phosphonium-based ionic liquids

D2EHPAとMIDPAを用いる希土類元素のイオン液体中への協同抽出

松宮 正彦*; 野水 大輝*; 土田 裕介*; 佐々木 祐二  

Matsumiya, Masahiko*; Nomizu, Daiki*; Tsuchida, Yusuke*; Sasaki, Yuji

D2EHPA(A)とMIDPA(B)を用いる希土類元素のイオン液体中へ協同抽出が検討された。D2EHPAまたはMIDPAを単独で抽出に用いる際には、その抽出種は[LnAHA]か[LnBHB]であった。錯形成定数から、協同抽出錯体である[TbHAB]や[DyHAB]は単独抽出剤による[LnAHA],[LnBHB]等の錯体種より安定であることが確認された。分離係数を考慮すると、協同効果を用いてDyをPrやNdからの分離が可能であることを確認した。

The synergistic solvent extraction of lanthanide(III) with mixtures of di-(2-ethylhexyl)phosphoric acid (D2EHPA, A) and monoisodecyl phosphoric acid (MIDPA, B) in phosphonium-based ionic liquid was investigated. In the case of D2EHPA or MIDPA single extractant system, Ln(III) (Ln = Pr and Nd) was extracted as [LnAHA] or [LnBHB], respectively, the extracted species of Tb(III) or Dy(III) were determined by slope analysis. According to the equilibrium constants (, and ) and the formation constants (, and ), it was found that the extracted complex [TbHAB or [DyHAB] was more stable than [LnAHA] or [LnBHB]. The synergistic extraction effects were investigated to study the possibility of separating Dy(III) from Pr(III) and Nd(III) according to their separation factors.