Showing papers by "Heather D. Willauer published in 2003"

Controlling the aqueous miscibility of ionic liquids: aqueous biphasic systems of water-miscible ionic liquids and water-structuring salts for recycle, metathesis, and separations.

Abstract: Hydrophilic ionic liquids can be salted-out and concentrated from aqueous solution upon addition of kosmotropic salts forming aqueous biphasic systems as illustrated by the phase behavior of mixtures of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and K3PO4.

Some Novel Liquid Partitioning Systems: Water−Ionic Liquids and Aqueous Biphasic Systems

Abstract: Partition coefficients, as values of log P, between water and two room-temperature ionic liquids and between water and an aqueous biphasic system have been correlated with Abraham's solute descriptors to yield linear free energy relationships that can be used to predict further values of log P, to ascertain the solute properties that lead to increased or decreased log P values, and to characterize the partition systems It is shown that, in all three of the systems, an increase in solute hydrogen-bond basicity leads to a decrease in log P and an increase in solute volume leads to an increase in log P For the two ionic liquid systems, an increase in solute hydrogen-bond acidity similarly decreases log P, but for the aqueous biphasic system, solute hydrogen-bond acidity has no effect on log P These effects are rather smaller than those observed in traditional water−solvent systems However, the ionic liquids appear to have an increased affinity for polyaromatic hydrocarbons as compared to traditional orga

Phase diagram data for several PEG + salt aqueous biphasic systems at 25 °C

Abstract: Phase diagrams determined by the cloud point method at 25 °C, including tie lines assigned from mass phase ratios according to the lever arm rule, are presented for several poly(ethylene glycol) (P...

Analysis of inorganic and small organic ions with the capillary electrophoresis microchip.

Abstract: Capillary electrophoresis microchip devices are receiving considerable attention due to their versatility, portability, and sample handling capabilities. This article is a comprehensive review of the analysis of inorganic and small, charged organic species on microchip platforms. The application of conductivity, amperometry, laser-induced fluorescence, absorbance, and chemiluminescence detection methods are discussed. The potential utilization of these devices for miniaturized analytical systems is described.

Room Temperature Ionic Liquids as Replacements for Traditional Organic Solvents and Their Applications Towards “Green Chemistry” in Separation Processes

Abstract: The full effect of Green Chemistry will be realized when the words “environmentally friendly” and “chemistry” can be used in the same sentence without seeming to be a contradiction. In an effort to comply with governmental regulations and to spruce up the image of the chemical industry, one of the major goals of “green” chemistry is to prevent pollution and waste production at the source. In light of the vast usage of organic solvents in industry, we have investigated the use of Room Temperature Ionic Liquids (RTIL) as solvent alternatives in liquid/liquid separations. Starting from the initial study in which we examined the partitioning of simple benzene derivatives in liquid/liquid extraction systems, we have also studied how ionisable solutes partition in these systems. The knowledge of how organic solutes partition has facilitated the use of metal ion extractants in RTIL-based liquid/liquid separations. This report discusses our current results in the utilization of RTIL for liquid/liquid extraction and also highlights recent results from the literature (e.g., chromatography, supercritical fluid extraction) in which RTIL have been used for separations. The examples chosen serve as illustrations as to how RTIL can be easily used in separations, however, further research is needed to clarify where the use of RTIL is appropriate and before RTIL can be confirmed to be “green” solvent replacements.

Peg-based aqueous biphasic systems as improvement for kraft hardwood pulping process

Abstract: Aqueous biphasic systems (ABS) represent wholly aqueous systems that are safe, nontoxic, nonflammable, and relatively environmentally benign as extraction media. We have studied detailed phase diagrams and partitioning data currently used in wholly aqueous solvent extraction or reactive extraction processes that may be applicable to the delignification of cellulosic materials at elevated temperature. The study results indicate that increasing the concentration of salt improves the degree of phase divergence. The partitioning results of different lignin species in PEG/salt ABS show that lignin prefers the polymer-rich phase of ABS. Four complete time-at-temperature (130-160°C) batch-cooking experiments were made using a Kraft pulping solution with and without PEG. The results for wood chips composed of a mixture of southern hardwood indicate that the use of PEG results in a pulp with lower Kappa number, lower lignin content, higher residual pulp yield, and reduced alkali consumption.