Volumetric properties of ionic liquids from cubic equation of state: Application to pure and mixture

In this work, we developed a cubic equation of state (CEOS) for modeling the volumetric properties of various ionic liquids (ILs). Two temperature-dependent parameters presented in the CEOS, have been determined from two sets of corresponding states correlations which are based on the critical point data or the surface tension of ILs. The predicted densities of pure ILs were compared with the experimental data over a broad pressure range from 1 to 100 MPa. The total average absolute deviations (AADs) of the calculated densities of 948 data points from the experimental data are 1.82% using the critical property and 0.96% using the surface tension and liquid density as scaling parameters. Furthermore, the proposed CEOS was successfully extended to mixtures including IL + IL and IL + solvent systems. 1282 literature data points for mixtures were taken to check the reliability of the mixture version of the proposed CEOS. The AAD of the calculated densities of the mixtures using the surface tension and liquid density as scaling parameter is 0.37%. Furthermore, the excess molar volumes (VE) of the studied binary mixtures have been successfully computed by the use of the proposed CEOS.