Prediction of deep eutectic solvents densities at different temperatures

Predicting densities of nonconventional solvents like deep eutectic solvents (DESs) as a function of temperature is of considerable importance in the development and design of new processes utilizing these solvents. Because of the nature of bonding existing between the salt and the hydrogen bond donor, conventional methods result in very large deviations. In this study, the density of DESs based on three different salts was estimated using empirical method. Nine different salts:hydrogen bond donor combinations were selected to test this method. The densities of all DESs were measured at a temperature range (298.15–368.1 K). The critical properties of salt and hydrogen bond donor were estimated using the Modified Lydersen–Joback–Reid method, while that of the mixture were calculated using Lee–Kesler equation. The Rackett equation modified by Spencer and Danner was employed to predict the DES density. The values of measured and predicted densities were compared and the average of absolute relative error percentage (ARPE) for all DESs was found to be 1.9%. The effect of salt to HBD molar ratio on ARPE in predicted DESs densities was also investigated.

Research highlights▶ An empirical method is introduced to predict deep eutectic solvents densities as function of temperature. ▶ The correlation showed high prediction quality for all tested DESs. ▶ The density of the DESs lies between the densities of the corresponding salt and HBD used in their synthesis. ▶ The relative difference of densities between the DES and the HBD directly affects the quality of density prediction.