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Ultrasonic velocities have been measured for different binary mixtures of common choline chloride-based deep eutectic solvents (DESs), namely, reline, glyceline and ethaline with water, in the range of temperature: 303.15-353.15 K. The experimental data measurements with different mole fractions of DES-water solutions were utilised in fitting four different models for speed of sound. These models correlate the speed of sound with some physical properties such as molar volumes, molar components sound velocity, densities, molecular weights, collision factors etc. A close match was obtained with these models with an average relative error of less than 4% for all data points used. It was observed that the ultrasonic velocity increases with the concentration of DES solvent and decreases with temperature. Moreover, this study roughly indicated that the intermolecular interactions in reline and ethaline aqueous mixtures exist in the form of disruption of dipole-dipole interactions (that varies considerably as a function of DES mixture composition and solution temperature). On the other hand, the interactions on the molecular level in glyceline aqueous solution are mainly due to dipole-dipole intermolecular forces. [ABSTRACT FROM AUTHOR]

Despite the surge in publications related to the characterization of deep eutectic solvents (DESs), the speed of sound of these liquids was not considered. This work represents the first study to report the acoustic properties of choline chloride-based DESs (Type III). Five different hydrogen bond donors were used to synthesize the DESs and the speed of sound was measured as a function of temperature within the range: 293.15–353.15 K. In general the speed of sound was affected by the nature and molecular structure of the DES considered. A general decrease in the speed of sound with temperature was noticed for all studied DESs. Three different models were attempted to correlate the speed of sound with some basic physical properties of these DESs as well as the temperature. The Gorbachev's model was able to correlate the speed of sound for the examined DESs with an overall relative error of 0.273%. Further work needs to be done on characterizing other types of DESs (Types I, II and IV) as well as relating the speed of sound data to other physical and thermodynamic parameters. [ABSTRACT FROM AUTHOR]