Densities and dynamic viscosities of (choline chloride + glycerol) deep eutectic solvent and its aqueous mixtures in the temperature range (283.15–363.15) K

Abstract

Deep eutectic solvents (DESs) are emerging as one of the most promising environmentally benign and cost-effective alternatives to the conventional organic solvents. Many common DESs are readily miscible with water. Aqueous mixtures of DESs have potential to afford modified properties for specific applications. Densities and dynamic viscosities of a common and popular DES composed of choline chloride and glycerol in 1:2 mole ratio, named glyceline, and its aqueous mixtures in the temperature range 283.15–363.15K are reported. Decrease in density with increasing temperature is found to follow a quadratic expression. Excess molar volumes of the aqueous mixtures of glyceline are found to be negative and significant at all temperatures and compositions. Absolute excess molar volume is found to decrease as the temperature is increased from 283.15K to 323.15K. For temperature above 323.15K, the excess molar volume does not change much with further increase in temperature till 363.15K. Temperature dependence of dynamic viscosity of aqueous mixtures of glyceline in the temperature range 283.15–363.15K at all compositions is found to be better described by a Vogel–Fulcher–Tamman (VFT) model. Excess logarithmic viscosities for aqueous mixtures of glyceline are found to be positive at all temperatures and compositions investigated. The results highlight relatively stronger interactions, preferably H-bonding type, between water and glyceline, as compared to those among water and among glyceline molecules, respectively. Facile interstitial accommodation of water within H-bonded glyceline network also appears to contribute to the experimental observations.