title: Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents.
abstract: The extraction of both UO2(2+) 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.
authors.affiliation: Department of Chemistry, University of Alabana, Tuscaloosa, AL 35487, USA.
authors.forename: Violina A
authors.initials: VA
authors.lastname: Cocalia
authors.forename: Mark P
authors.initials: MP
authors.lastname: Jensen
authors.forename: John D
authors.initials: JD
authors.lastname: Holbrey
authors.forename: Scott K
authors.initials: SK
authors.lastname: Spear
authors.forename: Dominique C
authors.initials: DC
authors.lastname: Stepinski
authors.forename: Robin D
authors.initials: RD
authors.lastname: Rogers