Physical and transport properties of ionic liquids using the geometric similitude concept and a cubic equation of state. Part 1: Thermal conductivity and speed of sound of pure substances

A model based on the geometric similitude concept recently proposed by the authors is extended to calculate the thermal conductivity and the speed of sound of ionic liquids. Experimental data for these properties are employed to determine the constants and the parameters of the proposed general model. The experimental data are taken from ionic liquid database provided by the National Institute of Standards and Technology (NIST). In total, 320 thermal conductivity data (40 ionic liquids) and 2572 speed of sound data (61 ionic liquids), at the temperature range of 263.15 K to 390.15 K and pressure from 0.86 up to 2000 bar have been considered. The proposed empirical equation of state model contains only one adjustable parameter for each ionic liquid, parameter that can be determined using a single experimental data or can be generalized in terms of other available properties, as proposed in this work. The results show that the equation of state model provides acceptable results for the correlation and prediction of the thermal conductivity and the speed of sound for the studied pure ionic liquids.