Predictive correlation between surface tension, density, and speed of sound of ionic liquids: Auerbach model revisited

In the current study, following the pioneering work of Auerbach a novel interrelationship has been presented between surface tension (sigma), density (rho), and speed of sound (u) of ILs. 2314 strictly experimental data points pertaining to 48 ILs over an extended temperature range have been employed for the development and validation of this globally applicable predictive model. With AARD values of 1.11% and 1.62% for the training and test datasets, respectively, the new model addresses the systematic deviation of the original Auerbach model and also demonstrates more than a twofold increase in accuracy compared to two previously published models. By solely incorporating the readily available molecular weight of ILs it can be conveniently used for estimation of the speed of sound using surface tension and liquid density values at the temperature of interest. Additionally, the speed of sound is used to develop a semi-empirical relation for prediction of the thermal conductivity (lambda) of ILs based on the Bridgman theory. The predicted values exhibit a satisfactory agreement with the experimental data with an AARD value of 1.32% for 75 data points corresponding to 11 ILs compared with a value of 5.45% for a similar previously published closed-form expression. (C) 2018 Elsevier B.V. All rights reserved.