Density, conductivity, viscosity, and excess properties of (pyrrolidinium nitrate-based Protic Ionic Liquid + propylene carbonate) binary mixture

Abstract

Density, ρ, viscosity, η, and conductivity, σ, measurements of binary mixtures containing the pyrrolidinium nitrate Protic Ionic Liquid (PIL) and propylene carbonate (PC), are determined at the atmospheric pressure as a function of the temperature from (283.15 to 353.15)K and within the whole composition range. The temperature dependence of both the viscosity and conductivity of each mixture exhibits a non-Arrhenius behaviour, but is correctly fitted by using the Vogel–Tamman–Fulcher (VTF) equation. In each case, the best-fit parameters, such as the pseudo activation energy, Ea∗ and ideal glass transition temperature, T0 are then extracted. The excess molar volumes VE, and viscosity deviations from the ideality, Δη, of each investigated mixture were then deduced from the experimental results, as well as, their apparent molar volumes, Vϕ, thermal expansion coefficients αp, and excess Gibbs free energies (ΔG∗E) of activation of viscous flow. The VE, αpE, Δη values are negative over the whole composition range for each studied temperature therein. According to the Walden rule, the ionicity of each mixture was then evaluated as a function of the temperature from (283.15 to 353.15)K and of the composition. Results have been then discussed in terms of molecular interactions and molecular structures in this binary mixture.