Effect of anions on the extraction of lanthanides (III) by N,N′-dimethyl-N,N′-diphenyl-3-oxapentanediamide

The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y by N,N '-dimethyl-N,N '-diphenyl-3-oxapentanediamide (DMDPhOPDA) in 1,2-dichloroethane from aqueous media containing ClO4-, PF6-, (CF3SO2)(2)N- anions or by DMDPhOPDA in 1,2-dichloroethane in the presence of 1-butyl-3-methylimidazolium bis[(trifluoremethyl)sulfonyl]imide ([C(4)mim][Tf2N]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]) from HNO3 solutions has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. The addition of HPF6 and (CF3SO2)(2)NH or their salts to the aqueous HNO3 or HCl solutions leads to an enchancement of lanthanides (III) extraction by DMDPhOPDA. A considerable synergistic effect was observed in the presence of ionic liquids (IL) in the organic phase containing DMDPhOPDA. This effect is connected with the hydrophobic nature of the IL anion. The distribution of ILs between the equilibrium organic and aqueous phases can govern the extractability of lanthanides (III) in DMDPhOPDA-IL systems.