Surface tensions of imidazolium based ionic liquids: Anion, cation, temperature and water effect

Freire, Mara G.; Carvalho, Pedro J.; Fernandes, Ana M.; Marrucho, Isabel M.; Queimada, António J.; Coutinho, João A. P.

doi:10.1016/j.jcis.2007.06.003

Cited by 406 publications

(476 citation statements)

References 56 publications

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“…2 Despite the fact that some investigators 111 have indicated that water has a negligible effect on the surface tension, it is important, in all cases, but especially with hydrophilic ILs to report the water content, since most of the thermophysical properties are affected by the presence of water. 2,112,113 In our previous study, 2 it has been shown that water disrupts the anion-cation interactions through the formation of hydrogen bonds between water and the [TCM]…”

Section: Surface Tensionmentioning

confidence: 99%

“…density and viscosity). 114 Freire et al 113 have studied the effect of water on the surface tension and observed a decrease for low water content, which was more pronounced for the more hydrophilic ILs. At higher water contents, when complete solvation of the ions has been reached, further hydrogen bonding is not possible, leading to a new structural rearrangement, which results in an increase in the physical properties such as the surface tension.…”

Section: Surface Tensionmentioning

confidence: 99%

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Thermophysical properties of imidazolium tricyanomethanide ionic liquids: experiments and molecular simulation

Zubeir

Rocha

Vergadou

et al. 2016

Phys. Chem. Chem. Phys.

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The low-viscous tricyanomethanide ([TCM]À )-based ionic liquids (ILs) are gaining increasing interest as attractive fluids for a variety of industrial applications. The thermophysical properties (density, viscosity, surface tension, electrical conductivity and self-diffusion coefficient) of the 1-alkyl-3-methylimidazolium tricyanomethanide [C n mim][TCM] (n = 2, 4 and 6-8) IL series were experimentally measured over the temperature range from 288 to 363 K. Moreover, a classical force field optimized for the imidazolium-based[TCM] À ILs was used to calculate their thermodynamic, structural and transport properties (density, surface tension, self-diffusion coefficients, viscosity) in the temperature range from 300 to 366 K. The predictions were directly compared against the experimental measurements. The effects of anion and alkyl chain length on the structure and thermophysical properties have been evaluated. In cyano-based ILs, the density decreases with increasing molar mass, in contrast to the behavior of the fluorinated anions, being in agreement with the literature. The contribution per -CH 2 -group to the increase of the viscosity presents the following sequence: The experimentally determined self-diffusion coefficients of the cations are in good agreement with the molecular simulation predictions, in which a decrease of the self-diffusion of the cations with increasing alkyl chain length is observed with a simultaneous increase in viscosity and for the longer alkyl lengths the anion becomes more mobile than the cation.

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Section: Surface Tensionmentioning

confidence: 99%

Section: Surface Tensionmentioning

confidence: 99%

Thermophysical properties of imidazolium tricyanomethanide ionic liquids: experiments and molecular simulation

Zubeir

Rocha

Vergadou

et al. 2016

Phys. Chem. Chem. Phys.

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“…[14][15][16] Water may also act as a cosolvent, for example, increasing the mutual solubilities between alcohols and ILs, or as an antisolvent, reducing the solubility of gases in ILs. [17][18][19][20] The presence of water can also affect the rates and selectivity of reactions involving or carried in ILs.…”

Section: Introductionmentioning

confidence: 99%

Mutual Solubilities of Water and Hydrophobic Ionic Liquids

et al. 2007

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The ionic nature of ionic liquids (ILs) results in a unique combination of intrinsic properties that produces increasing interest in the research of these fluids as environmentally friendly "neoteric" solvents. One of the main research fields is their exploitation as solvents for liquid-liquid extractions, but although ILs cannot vaporize leading to air pollution, they present non-negligible miscibility with water that may be the cause of some environmental aquatic risks. It is thus important to know the mutual solubilities between ILs and water before their industrial applications. In this work, the mutual solubilities of hydrophobic yet hygroscopic imidazolium-, pyridinium-, pyrrolidinium-, and piperidinium-based ILs in combination with the anions bis-(trifluoromethylsulfonyl)imide, hexafluorophosphate, and tricyanomethane with water were measured between 288.15 and 318.15 K. The effect of the ILs structural combinations, as well as the influence of several factors, namely cation side alkyl chain length, the number of cation substitutions, the cation family, and the anion identity in these mutual solubilities are analyzed and discussed. The hydrophobicity of the anions increases in the order [C(CN) 3 ] < [PF 6 ] < [Tf 2 N] while the hydrophobicity of the cations increases from [C n mim] < [C n mpy] e [C n mpyr] < [C n mpip] and with the alkyl chain length increase. From experimental measurements of the temperature dependence of ionic liquid solubilities in water, the thermodynamic molar functions of solution, such as Gibbs energy, enthalpy, and entropy at infinite dilution were determined, showing that the solubility of these ILs in water is entropically driven and that the anion solvation at the IL-rich phase controls their solubilities in water. The COSMO-RS, a predictive method based on unimolecular quantum chemistry calculations, was also evaluated for the description of the water-IL binary systems studied, where it showed to be capable of providing an acceptable qualitative agreement with the experimental data.

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“…Therefore, it is important to measure these properties in order to improve their characterization, not only for designing but also for developing correlations either between these properties or with performance parameters. 8 One of the main advantages of working with ILs is the possibility of easily adapting their properties with small variations in the chemical composition, thus having a huge potential for engineering applications. 2 This fact may be used as a tool for self-tuning the ILs with multiple and useful application possibilities by changing physicochemical properties, such as density, melting point, viscosity, conductivity, or surface tension.…”

Section: Introductionmentioning

confidence: 99%