Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents

V.A. Cocalia, M.P. Jensen, John Holbrey, S.K. Spear, D.C. Stepinski, Robin Rogers

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170 Citations (Scopus)


The extraction of both UO22+ and trivalent lanthanide and actinide ions (Am3+, Nd3+, Eu3+) by dialkylphosphoric or dialkylphosphinic acids from aqueous solutions into the ionic liquid, 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide has been studied and compared to extractions into dodecane. Radiotracer partitioning measurements show comparable patterns of distribution ratios for both the ionic liquid/aqueous and dodecane/aqueous systems, and the limiting slopes at low acidity indicate the partitioning of neutral complexes in both solvent systems. The metal ion coordination environment, elucidated from EXAFS and UV-visible spectroscopy measurements, is equivalent in the ionic liquid and dodecane solutions with coordination of the uranyl cation by two hydrogen-bonded extractant dimers, and of the trivalent cations by three extractant dimers. This is the first definitive report of a system where both the biphasic extraction equilibria and metal coordination environment are the same in an ionic liquid and a molecular organic solvent.
Original languageEnglish
Pages (from-to)1966-1971
Number of pages6
JournalDalton Transactions
Issue number11
Publication statusPublished - 07 Jun 2005


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