http://alpha.chem.umb.edu/chemistry/Seminar/06-09%20WQE/PChem%20I.%20Qu.pdf

Recent developments in thermodynamics and thermophysics of non-aqueous mixtures containing ionic liquids. A review

https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50045

Electrolytic conductivity of four imidazolium-based room-temperature ionic liquids and the effect of a water impurity

Ionic liquids (ILs) and deep eutectic solvents (DESs) have been suggested as eco-friendly alternatives to organic solvents. A trace amount of water is often unavoidable as impurity, and water is also added on purpose to reduce their problematically high viscosity and lower their high price. Understanding the distinct effects of water on the properties of ILs/DESs is highly important. In this review, we collect published experimental and theoretical results for IL/DES–H2O systems at varied water concentrations and analyze them. Results from mechanistic studies, thermodynamic modelling and advanced experiments are collected and critically discussed. Six commonly studied IL/DES–H2O systems were selected to map experimental observations onto microscopic results obtained in mechanistic studies. A great variety of distinct contours of the excess properties can be observed over the entire compositional range, indicating that the properties of IL/DES–H2O systems are highly unpredictable. Mechanistic studies clearly demonstrate that the added H2O rapidly changes the heterogeneous 3D structures of pure ILs/DESs, leading to very different properties and behaviour. There are similarities between aqueous electrolytes and IL/DES solutions but the bulky and asymmetric organic cations in ILs/DESs do not conform to the standard salt dissolution and hydration concepts. Thermodynamic modelling previously assumes ILs/DESs to be either a neutral ion-pair or completely dissociated ions, neglecting specific ion hydration effects. A new conceptual framework is suggested for thermodynamic modelling of IL/DES–H2O binary systems to enable new technologies for their practical applications.

/pdf/the-peculiar-effect-of-water-on-ionic-liquids-and-deep-2hscgp3hx0.pdf

The peculiar effect of water on ionic liquids and deep eutectic solvents

https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=30029

The effect of dissolved water on the viscosities of hydrophobic room-temperature ionic liquids

The effect of water and several organic solvents on the density, viscosity, and conductivity of ionic liquids (ILs) 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), and 1-n-butyl-3-methylimidazolium trifluoroacetate ([bmim][CF3CO2]) was studied at 298.15 K in wide composition ranges. The density, viscosity, and conductivity of the three neat ILs were also determined at various temperatures. Upon the basis of the molar conductivity of the mixtures and that of the neat ILs of the same viscosity, the degree of dissociation of ILs in the solutions was investigated. It can be deduced that the organic solvents enhance the ionic association of the ILs, the effect depending on the solvent dielectric constant, while water promotes dissociation significantly due to its high dielectric constant and its ability to form strong hydrogen bonds with the anions of the ILs.

Effect of water and organic solvents on the ionic dissociation of ionic liquids.

The solubility of Dynol-604 (a surfactant) in supercritical (SC) CO2 and the phase behavior of the CO2/water/Dynol-604 system were studied at different temperatures and pressures. The results showed that the solubility of the surfactant in SC CO2 is high and one-phase water-in-CO2 microemulsions could be formed although Dynol-604 is a nonfluorous and nonsiloxane nonionic surfactant. The solvatochromic probe studies and the UV spectrum of lysozyme in the supercritical CO2/water/Dynol-604 system further proved the existence of a water domain in the supercritical CO2 microemulsions.

Investigation of Nonionic Surfactant Dynol-604 Based Reverse Microemulsions Formed in Supercritical Carbon Dioxide

The conductivities and viscosities of the room-temperature ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) + water + ethanol and [bmim][PF6] + water + acetone ternary mixtures were determined in the temperature range from 288.15 K to 308.15 K, and the mole fraction of the solvents in the mixtures was up to 0.48. The conductivities of the mixtures increased with increasing concentration of the solvents and temperature in the solvent concentration range studied. An increase in temperature or solvent concentration results in reduction in the viscosities of the mixtures.

and Jun He

Papers

Investigation of Nonionic Surfactant Dynol-604 Based Reverse Microemulsions Formed in Supercritical Carbon Dioxide

Conductivities and Viscosities of the Ionic Liquid [bmim][PF6] + Water + Ethanol and [bmim][PF6] + Water + Acetone Ternary Mixtures