Acoustic investigation of choline chloride based ionic liquids analogs

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.