Thermophysical Properties of Pure Ionic Liquids: Review of Present Situation

The large collection of thermophysical properties data for liquids available in the open literature is analyzed, describing its importance for industrial purposes. Although there has been a boom of thermophysical properties measurements for these fluids in the past decade, the reported analysis shows that studies have been centered on a limited number of fluids, whereas data collection for the new family ionic liquids is lacking. Measurements have been performed for limited temperature ranges, and pressure effects on the properties are extremely scarce in the literature; remarkable differences among data from different literature sources are reported. The need of sample purity quantification is analyzed together with the strong effect of these impurities on thermophysical properties. Available predictive models for the studied properties are analyzed together with the quality of their predictions. The main conclusion of this review is to point out the need of further systematic thermophysical studies, including for new environmentally friendly ionic liquids, carried out with interlaboratory comparisons, which allow the development of reference data sets.