Thermophysical characterization of choline chloride: Resorcinol and its mixtures with water

Abstract

The study of deep eutectic solvents has increased in recent years. This is because of their great solu- bility ability and lower toxicity than usual organic solvents. In this work, deep eutectic solvents formed by choline chloride and resorcinol in the mole ratio 1:2 and its mixtures with water, e.g., choline chlo- ride:resorcinol:water 1:2:1.05 (water mass fraction = 0.05) and choline chloride:resorcinol:water 1:2:2.22 (water mass fraction = 0.1), have been studied. Several physicochemical properties (density, speed of sound, isentropic compressibility, refractive index, surface tension, isobaric molar heat capacity, viscos- ity, and electrical conductivity) have been obtained and analysed at atmospheric pressure in the range of 283.15–338.15 K. The starting temperature for the speed of sound measurements was 308.15 K. The effects of tem perature and water inclusion have been evaluated. The obtained results have shown a lin- ear correlation between density, speed of sound, refractive index, surface tension and isobaric molar heat capacity and temperature. Additionally, the viscosity and electrical conductivity data can be adjusted us- ing the Vogel-Fulcher-Tammann equation. Finally, the inclusion of water was analysed to check how the thermophysical properties were modified. These modifications had greater effects on transport properties, viscosity and electrical conductivity.