Correlation and prediction of the solubilities of solid n-alkanes in supercritical carbon dioxide using the Carnahan–Starling–van der Waals model with a density-dependent parameter

In this paper, the solubilities of some solid n-alkanes in supercritical carbon dioxide were correlated and predicted using the Carnahan–Starling–van der Waals model with a density-dependent parameter of a12. It was found that the parameter values of a12 for solid n-alkanes in CO2 at different temperatures are equal at the crossover pressure of 24 MPa, and a12 can be correlated with carbon number of the corresponding solid n-alkanes. At a given temperature, the linear fit of parameters a12 versus the density of the solvent was used for solubility correlation, resulting in an average absolute average relative deviation of 11.82%, which is comparable with that of the Peng–Robinson equation of state combined with the van der Waals two-parameter mixing rule model. The regressed slope m and intercept n of the linear fit can also be correlated with the carbon number of solid n-alkanes. The solubilities of solid n-alkanes can be predicted with a12 at the crossover pressure and slope m or with intercept n and slope m.