Temperature and composition dependence of the density and viscosity of binary mixtures of water plus ionic liquid

Density and viscosity were determined for binary mixtures of water and three ionic liquids: 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium trifluoroacetate, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate. The experimental measurements of these properties were carried out at atmospheric pressure and temperatures from (278.15 to 348.15) K. The temperature dependence of density and viscosity for these systems can be described by an empirical second-order polynomial and by the Vogel-Fulcher-Tammann equation, respectively. Excess molar volumes and viscosity deviations were calculated and correlated by Redlich-Kister polynomial expansions. The latter correlations describe the variation of density and viscosity with composition. Comparison of the results for the three binary systems elucidates the influence of the anion on these physical properties.