Calculation of the solid solubilities in supercritical carbon dioxide using a modified mixing model

The Peng-Robinson equation of state and a modified Huron-Vidal type mixing model with a volume correction term are applied in this study to calculate the solid solubilities of aromatic, fatty acid and heavy alcohol compounds in supercritical carbon dioxide. The UNIFAC activity coefficient model with its optimally fitted binary interaction parameters is used in this study. A volume correction term is employed, and its parameters are correlated as functions of the solid molar volume for both non-polar and polar systems. The effect of the sublimation vapor pressure on the calculation of solid solubilities in supercritical carbon dioxide is examined. The sublimation vapor pressures for heavy compounds are fitted in this study to yield the optimally calculated results of the solid solubility. Reasonable sublimation vapor pressures are obtained and their values are well correlated by the Antoine equation. A generalized calculation model is proposed in this study which gives satisfactory results of the solid solubility in supercritical carbon dioxide for both the binary and ternary systems. (C) 2001 Elsevier Science B.V. All rights reserved.