Density, Viscosity, and Electrical Conductivity of (Choline Chloride + Ethylene Glycol) Mixtures Covering Concentrations from Neat Molecular Solvent to Supersaturated Solutions

Abstract

This contribution provides data for density, ρ, viscosity, η, and electrical conductivity, κ, of [choline chloride (ChCl, component 1) + ethylene glycol (EG, 2)] mixtures. ChCl concentrations from neat EG to x₁ = 0.333 (ChCl:2EG) were covered for ρ and η. For κ, additionally, x₁ = 0.352 was studied. Temperature ranges covered are T = 278.15–363.15 K for ρ and η, and T = 278.15–338.15 K for κ. The observed temperature dependence at a given x₁ could be empirically described by a quadratic function for ρ and the Vogel–Fulcher–Tammann equation for η and κ. Properties obtained for ChCl:2EG were compared to the data published so far. It turned out that sample purity, including moderate water content, does not greatly influence ChCl:2EG density. However, η(T) decreases substantially with rising water content. With some exceptions, most of the published η(T) and κ(T) data strongly disagree with the present fits. The properties derived from the measured data allowed some conclusions on interspecies interactions: apparent molar volumes obtained for the solute suggest its structure-breaking effect on the inherent EG structure, with solute–solute contacts playing the dominant role here. Despite the rather high conductivity, {ChCl + EG} mixtures show low ionicity, indicating pronounced ChCl self-aggregation.