The NADES glyceline as a potential Green Solvent: A comprehensive study of its thermophysical properties and effect of water inclusion

In this paper, two Natural Deep Eutectic Solvents, glyceline (Gly) and glyceline-water (GlyW), containing choline chloride as acceptor H-bond compound and glycerol as donor H-bond group are studied. For glyceline the mole relation is 1 (choline chloride): 2 (glycerol) and for glyceline-water the mole relation is 1 (choline chloride): 1.99 (glycerol): 1.02 water. The ternary NADES has been synthetized and characterized chemically by NMR techniques for this work. Several thermophysical properties in a wide range of temperature (278.15-338.15) K and at atmospheric pressure (0.1 MPa) have been measured for both compounds: density, ρ, speed of sound, u, refractive index, nD, surface tension,σ, isobaric molar heat capacity, Cp,m, kinematic viscosity, ν, and electric conductivity,κ. Furthermore, some related properties have been also calculated: isobaric expansibility, αp, isentropic compressibility, κS, molar refraction, Rm, entropy and enthalpy of surface formationper unit surface area (ΔSs and ΔHs), and dynamic viscosity, η, and viscous flow and electrical conductivity activation energies. The results have been discussed in terms of the effect of temperature and the inclusion of water. We conclude that the compound containing water into the structure has a higher molar volume and a higher fluidity. The binary NADES (Gly) is a more structured liquid than ternary one (GlyW).