New Method for Calculation Mixing Rule and Modification Semi-empirical Models for Solubility Modeling in Supercritical Solvent

The critical properties of a solute are required for modeling of the solubility by the equation of state. For many compounds, the critical properties are not available. So, group contribution method is utilized as a common method to estimate these properties. But, it leads to the consecutive errors in calculations of the solubility modeling. In this study, Soave-Redlish-Kowang (SRK) and Peng-Robinson equation of states with Huran-Vidal mixing rules were used for modeling of the solubility. A new method for evaluating of C2 (Huran-Vidal mixing rule parameter) is recommended as a function of temperature and pressure. For solubility modeling by semi-empirical correlation, the new forms of Chrastil and Mendez equations were used. Finally, the modeling of solubility for 20 compounds by these methods has been investigated. Results show that the AARD% for the models with semi-empirical equations (Charstil, Aguilera, Gordillo, Mendez, modified Charstil and modified Mendez) are 12.07, 11.71, 34.89, 19.89, 11.17 and 15.70 respectively; and for SRK, PR EOS are 14, 19.85 respectively.