Grad Students/Postdocs

Publications

Alexandre Chapeaux, Luke D. Simoni, Mark A. Stadtherr, Joan F. Brennecke. Liquid-liquid behavior of Ionic Liquids with Water and 1-Octanol and modeling of 1-Octanol/Water Partition Coefficients. Journal of Chemical and Engineering Data, 52:2462-2467, 2007. view abstract This study examines the effect of structural components of an ionic liquid (IL), including the choice of the anion, alkyl chain length on the cation, and substitution on the cation, on the mutual solubility with water and with 1-octanol. This is important because ionic liquids have been shown to be good replacements for organic extraction solvents in some liquid separations. In addition, we use the measured data to predict 1-octanol/water partition coefficients for the ionic liquids using the non-random two liquid (NRTL) and electrolyte non-random two liquid (eNRTL) excess Gibbs energy models. Specifically, the mutual solubilities of fifteen different imidazolium, pyridinium and quaternary ammonium ionic liquids with water were measured at (23.5 ± 1 ºC). An increase in the alkyl chain length or the substitution decreases the mutual solubility with water. The [BF4]¯and [B(CN)4]¯anions are significantly more hydrophilic than [PF6]¯, [(CF3SO2)2N]¯, and [(CF3SO2)3C]¯. The mutual solubilities of ten ILs with 1-octanol were measured at (23.5 ± 1 ºC). For these systems, the longer the alkyl chain, the more soluble the IL was in the alcohol, while ring substitution has little effect. From this data, 1-octanol/water partition coefficients of ten ionic liquids were predicted using the NRTL and eNRTL models.

Alexandre Chapeaux, Luke D. Simoni, Thomas S. Ronan, Mark A. Stadtherr, Joan F. Brennecke. Extraction of alcohols from water with 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Green Chemistry, view abstract Ethanol production in the U. S. has increased 36 % between 2006 and 20071 in response to a growing demand for its use as a commercial transportation fuel. 1-Butanol also shows potential as a liquid fuel but both alcohols require high energy consumption in separating them from water. 1-Butanol, in particular, is considered an excellent intermediate for making other chemical compounds from renewable resources, as well as being widely used as a solvent in the pharmaceutical industry. These alcohols can be synthesized from bio-feedstocks by fermentation, which results in low concentrations of the alcohol in water. To separate alcohol from water, conventional distillation is used, which is energetically intensive.
The goal of this study is to show that, using an ionic liquid, extraction of the alcohol from water is possible. Through the development of ternary diagrams, separation coefficients are determined. The systems studied are 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/ethanol/water, which exhibits Type 1 liquid-liquid equilibrium (LLE) behavior, and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/1-butanol/water, which exhibits Type 2 LLE behavior. This ionic liquid (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) can easily separate 1-butanol, but not ethanol, from water.
In addition, we use four excess Gibbs free energy (gE) models (NRTL, eNRTL, UNIQUAC and UNIFAC), with parameters estimated solely using binary data and/or pure component properties, to predict the behavior of the ternary LLE systems. None of the models adequately predicts the Type 1 system, but both UNIQUAC and eNRTL aptly predict the Type 2 system.

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