Physicochemical properties of binary mixtures of 1,1,3,3-tetramethylguanidine imidazolide ionic liquid with water and alcohols

In this work, densities and viscosities of aqueous solution of 1,1,3,3-tetramethylguanidine imidazolide ([TMG]IM) ionic liquid were measured at temperatures from T = (293.15 to 313.15) K. Volumetric properties including excess molar volumes VE, apparent molar volumes, partial molar volumes, and excess partial molar volumes were calculated from the experimental density. Viscosity deviations Δη, Gibbs energy and excess Gibbs energy of activation for viscous flow were deduced from the viscosity. Moreover, electrical conductivities κ and refractive indices of binary mixtures of [TMG]IM with water and alcohols were determined at 298.15 K. The results show that VE values of {[TMG]IM (1) + water (2)} mixture are negative over the whole composition range, while Δη and refractive index deviations ΔnD values exhibit positive deviations, indicating that the hydrogen bonding interaction between [TMG]IM and water is dominant. The absolute values of VE and Δη of the mixture decrease with the increasing temperature. The VE, Δη, and ΔnD can be fitted by the Redlich-Kister equation with satisfactory results. The concentration-dependent κ of the studied systems are fitted to Casteel-Amis equation, showing that the κ values of {[TMG]IM (1) + water (2)} mixture are much higher than those of {[TMG]IM (1) + ethanol (2)} mixture.