Density Prediction of Ionic Liquids at Different Temperatures Using the Average Free Volume Model.

In this work, based on the average free volume model, the correlation between the molar volume and the van der Waals volume V (w) for the ionic liquids (ILs) was derived. With this model, the density of pure ILs and binary and ternary mixtures of ILs over a wide range of temperature (278-473.15 K) can be calculated with good accuracy only with the information of the chemical components. A total number of 1859 data points of 41 pure ILs and IL mixtures based on imidazolium, pyridinium, pyrrolidinium, phosphonium, and ammonium cations were used to verify the model. For pure ILs and IL mixtures, the average absolute relative deviations (ARDs) are 1.04 and 1.19%, respectively. The overall discrepancies are less than 4%.