Julie A. Dzielawa

Influence of solvent structural variations on the mechanism of facilitated ion transfer into room-temperature ionic liquids

The predominant mode of strontium ion transfer from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 (DCH18C6) shifts from cation exchange to strontium nitrato-crown ether complex partitioning as the hydrophobicity of the ionic liquid cation is increased.

Ion-exchange as a mode of cation transfer into room-temperature ionic liquids containing crown ethers: implications for the ‘greenness’ of ionic liquids as diluents in liquid–liquid extraction

The transfer of strontium ion from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 is shown to proceed via cation-exchange, in contrast to conventional solvents such as alkan-1-ols, in which extraction of a strontium nitrato-crown ether complex is observed.

Synergistic effects in the facilitated transfer of metal ions into room-temperature ionic liquids

Addition of tri-n-butyl phosphate (TBP) is shown to markedly increase the extraction of strontium from acidic nitrate media into certain 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imides by dicyclohexano-18-crown-6 (DCH18C6), the apparent result of the formation of a synergistic adduct between the strontium-DCH18C6 complex and TBP. The magnitude of the synergistic enhancement is shown to depend on the alkyl chain length of the ionic liquid (IL) cation, with the effect diminishing as the cation hydrophobicity increases. The effect also diminishes at high (>50% v/v) TBP concentrations, the likely result of changes in solvent polarity unfavorable to the extraction of metal-crown ether complexes.