Studies of Viscosity Coefficient and Density Properties of Imidazolium Based Ionic Liquids in Aqueous Solutions at Different Temperatures

The densities and viscosity coefficients for binary aqueous solutions of imidazolium based ionic liquids (IL's), namely 1-Butyl-3-Methylimidazolium Bromide (0.02281 to 0.17232 mol.kg(-1)) and 1-Butyl-3-Methylimidazolium Chloride (0.01948 to 0.19816 mol.kg(-1)) have been measured at 293.15, 298.15, and 303.15 K, and at atmospheric pressure, respectively. Using the density data, the apparent molar volumes (V-phi) and partial molar volumes ((V) over bar (2)) of solutes at finite concentrations and at infinitely dilute solutions (V-phi(0)=(V) over bar (0)(2)) were estimated. The limiting partial molar volumes of the constituent ions are also reported. The viscosity A, B and D coefficients of Jones-Dole equation for the studied IL's are obtained by using viscosity coefficient data. It is observed that viscosity A and B coefficients are positive in magnitude for studied IL's while the temperature coefficient of B (dB/dT) is of negative, signifying that cations are water structure making ions. The application of Vand's equation to viscosity data and estimation of volume fractions of the solute enabled us to obtain Einstein-Simha factor and particle interaction coefficient for the ion-pairs. The analysis of the results indicates that imidazolium cations act as electrostrictive water structure making ions.