Density, viscosity, and conductivity of choline chloride + ethylene glycol as a deep eutectic solvent and its binary mixtures with dimethyl sulfoxide

Abstract

Density, dynamic viscosity, and electrical conductivity of binary mixtures of ethaline (choline chloride+ethylene glycol at molar ratio 1:2) as a deep eutectic solvent (DES) with dimethyl sulfoxide were measured under atmospheric pressure at temperatures, T, from (308.15 to 363.15)K covering the entire mixture range. The mixtures exhibited negative excess molar volumes, VE, with a minimum at ethaline mole fractions of ×1≈0.4…0.5 that became more pronounced with increasing temperature. A similar minimum was found for the excess viscosity, Δη, of the mixtures. However, in contrast to VE the minimum of Δη became more shallow with increasing T. As expected, the electrical conductivity of the mixtures increased monotonically with increasing ×1 and T. The temperature dependence of viscosity and conductivity is well described by the Vogel−Fulcher−Tamman (VFT) equation.