Developing models for correlating ionic liquids density: Part 1 – Density at 0.1 MPa

Abstract

In this work, the experimental data of ionic liquids density at 0.1MPa were correlated with three models. Rackett equation which is a well known equation for calculating liquid density, has been considered as the first approach to calculate ionic liquids density. As Rackett equation could not reproduce well experimental data, the first model was developed to give a simple modification to Rackett equation. The basis of the first model was similar to Rackett equation which is an observed linear relation between logarithm of reduced volume and reduced temperature. The second model is obtained by expanding ionic liquid volume as a function of reduced temperature in the form of Taylor series. The third model was similar to Bhirud's model and logarithm of reduced density was expressed as function of logarithm of reduced temperature. All proposed models involve adjustable parameters in terms of ionic liquids thermodynamic properties which are obtained by correlating experimental data. As results show, these correlations are accurate enough to calculate ionic liquids density and the average absolute percent deviation was 0.83%, 1.10% and 2.04% for first, second and third model. The calculation of ionic liquids density at high pressures by aid of developed models is the subject of upcoming paper.