A Modified NRTL Equation for the Solubility of Sterols in Supercritical Carbon Dioxide

The evaluation of the solubility of solid solutes in supercritical carbon dioxide is of paramount interest for the optimization of different supercritical based technologies. Most of the proposed approaches, at the end, give a method for the correlation only of the solubility and not a tool for the prediction. In this study, a modified NRTL equation, that includes the ratio of molar volumes of the two components, is used for the evaluation of the activity in the supercritical phase. Furthermore, the model is applied in the one parameter form according to the method already proposed by Tassios. The remaining cross interaction parameter is correlated to the difference of well know properties of pure compounds. The method is applied with satisfactory results to the description of the solubility of sterols in supercritical carbon dioxide in a wide range of temperature and pressure