A simple thermodynamic model for the solubility of thermolabile solids in supercritical fluids (original) (raw)
Process Technology Proceedings, 1996
Solubilities of several organic solids in four supercritical fluids are calculated with Soave and Peng-Robinson equations of state, incorporating excess Gibbs free energy into the mixing rules, with Heidemann-Kokal, Wong-Sandler and MHV2 procedures. Three excess Gibbs free energy models are used in the mixing rules: NRTL, UNIQUAC and UNIFAC. Furthermore, a comparison between these mixing rules and conventional two-binary-parameter form and modification of the excluded volume parameter in the MHV2 procedure is also presented. The best result were obtained with NRTL model and the Wong-Sandler mixing rule.
Brazilian Journal of Chemical Engineering
Due to the importance of supercritical fluid technology (SFT) in different industries, it has been the subject of intense research in recent decades. Solubility is a key concept in SFT. In fact, obtaining knowledge about the theoretical concepts of solubility and related experimental measurement methods can be useful in developing and improving the quality of research in this field. This study reviews the fundamental knowledge of solubility in supercritical fluids and investigates the significant topics in this field, including high-pressure phase behavior, experimental measurement methods, modeling, and molecular simulation of solubility.
A Density-Dependent Solute Solubility Parameter for Correlating Solubilities in Supercritical Fluids
Industrial & Engineering Chemistry Research, 1998
A density-dependent solute solubility parameter has successfully correlated solubilities in supercritical fluids (SCFs). Fifteen solutes, including polar and nonpolar compounds, have been studied in up to four SCFs. A two-parameter, linear fit resulted in a median average absolute relative deviation (AARD) of 20%, ranging from 6.1% to 42%, for the 34 systems studied. A three-parameter power fit provided a median AARD of 12%, ranging from 2.3% to 38%.
Modeling of the Solubility of Solid High-Molecular-Weight Organic Substances in Supercritical Fluids
2003
A method is proposed to calculate the solubility of solid high-molecular-weight substances in organic supercritical fluids on the basis of the Soave and Peng-Robinson equations of state. The mixing rules are modified taking into account the Gibbs energy of mixing calculated for a particular equation of state. The accuracy of calculation of the concentration of the substance dissolved in supercritical fluids is analyzed for different mixing rules. The modeling results are compared with observed data.
Solubility Measurement Method and Mathematical Modeling in Supercritical Fluids
Engineering Journal, 2013
Supercritical fluids technology (SFT) is gaining significance application in the field of food and drug processing. Since supercritical fluid possess dual characteristic of gas and liquid, it exhibits outstanding extraction features such as high penetration ability and able to dissolve materials. To aid the design of processes including extraction, separation, purification, and synthesis, solubility data of compound of interest is required. In addition, with the solubility data, a more environmental friendly and productive operating condition can be resulted. However, there is lack of review that summarizes the method and correlation to gain this data. Thus, the review is accomplished to give concise discussion on the fundamental knowledge of solubility. This review will discuss the solubility measurement method, quantification method and mathematical correlation models for explaining the thermodynamic relationship of solubility.
Solid Solubilities in Supercritical Phases : New Apparatus, Measurements and Modeling
HAL (Le Centre pour la Communication Scientifique Directe), 2000
A new apparatus for the measurement of solid solubilities in supercritical fluids is described in detail. It is based on an analytical (the composition of the phase is obtained by analyses) open flow method (the solvent flows continuously through the solid solute). Solubilities of naphthalene in supercritical CO 2 in the pressure range 8-30 MPa are reported along the isotherm 308.15 K. The solubility data are correlated using the Chrastil model.
Modelling solubility of solids in supercritical fluids using fusion properties
Fluid Phase Equilibria, 1999
The modelling of solid solubilities in supercritical fluids is usually performed by means of thermodynamic models based on cubic equations of state together with the use of correlations for estimating the solid properties. However, it was shown in the literature, that the error in sublimation pressure, which is very low for high molecular weight compounds, is in many cases responsible for large deviations between experimental and calculated solubilities. In this work, the sublimation pressure of solids is estimated by using experimental fusion Ž . data and liquid-vapour equilibrium properties obtained from an equation of state EOS . The results provided by this method are compared with those obtained using sublimation pressures from literature. It is shown that this method allows satisfactory solubility predictions when using a reliable EOS. q 1999 Elsevier Science B.V. All rights reserved.
Predicting Solubilities in Supercritical Fluids
The Journal of Physical Chemistry, 1996
We present a simple treatment of supercritical fluid extraction, including entrainer effects. Solubility predictions are made using the Redlich-Kwong equation of state: parameters for this equation are calculated directly from intermolecular potentials. We have tested our approach in the low-solubility limit by comparing with computer simulations. Good agreement is found for realistic values of the potential parameters describing solute-solvent and solvent-solvent interactions.
Solubility of supercritical gases in organic liquids
Journal of Supercritical Fluids, 2009
a b s t r a c t [6] demonstrated that the solubility of a substance in a supercritical fluid (SCF) can be correlated with the density of the pure supercritical gas. Therefore, Chrastil's equation permits calculation of the supercritical phase composition of binary SCF + substance mixture based on the knowledge of the supercritical gas density and avoiding the use of equation of state based models.