Compatibility of sustainable solvents ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate in some choline chloride based deep eutectic solvents: thermodynamics study

Abstract

Nowadays, green neteric solvents are replaced the conventional organic solvents. In this regard, deep eutectic solvents (DESs) have evolved as neoteric solvents similar to ionic liquids (ILs) with various applications in different fields. This paper reports the density, and speed of sound data of the ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][ES] in the some DESs, choline chloride/urea, choline chloride/ethylene glycol, choline chloride/glycerol and choline chloride/oxalic acid in dilute region concentration of the IL at temperature ranges T = (298.15 to 318.15) K and at atmospheric pressure. On the basis of these data, the apparent molar volume Vφ and apparent molar isentropic compressibility κφ were calculated. From these quantities and with help of Redlich-Mayer equation, the standard partial molar volumes and partial molar isentropic compressibility were obtained. The structure making or breaking behaviour of the [EMIM][ES] in the DESs studied has been described with the help of standard partial molar isobaric expansions Eφ0 and Hepler constant. The obtained parameters show that solute-solvent interactions between the IL and the DES are stronger for the choline chloride/urea solutions than the other investigated DESs. Finally, the Pitzer model have been used to correlate the values of Vφ and κφ, which indicates the Pitzer model has a good compatibility than the other models.