Solids in supercritical fluids

The so-called subcooled liquid approach was also suggested in the literature in order to overcome the difficulties connected with the pure component properties of the solid compound. This approach is commonly used for the calculation of the liquid-solid equilibria, and for solubility calculation of solids in supercritical fluids was already suggested [2] and subsequently extensively applied to different supercritical fluid processes [63]. The solubility y>2 is then expressed as ... 

General overview of several studies of transport and intermolecular interactions in compressed supercritical fluids is presented. The unique aspects of the instrumentation used in these studies are emphasized. First, the results of NMR studies of self-diffusion in supercritical ethylene and toluene are discussed. These experiments used the fixed field gradient NMR spin-echo technique. Second, the novel NMR technique for the determination of solubility of solids in supercritical fluids is described. 

A serious test of mixture equations of state is shown to be their application for prediction of solubility of solutes in supercritical fluids (JJ. ). In the present report, we apply the Redl ich-Kwong and the Peng-Robinson equations of state for supercritical fluid extraction of solids and study the effect of choosing different mixing rules on prediction of solubility of solids in supercritical fluids -Figures 1-5. 

The phase behavior of solids in supercritical fluids has practical significance as well as academic interest. Since the mid-1970 s, it has been recognized that supercritical fluids can be useful as solvents for commercial-scale extractions. While a variety of applications are documented in the literature (2,6), supercritical-fluid (SCF) extraction has been particularly useful in upgrading petroleum fractions (7), extracting volatile components from coal (8), and deashing oil shale (9) and coal liquids (10). The... 

Solubility of solids in supercritical fluids using equations of state - excess Gibbs free energy models. 

Kwiatkowski, J., Lisicki, Z., and Majewski, W., An Experimental Method for Measuring Solubilities of Solids in Supercritical Fluids, Ber. Bunsenges. Phys. Chem. 88 865-869 (1984)... 

Anitescu, G. Tavlarides, L. L. Solubihties of solids in supercritical fluids. 2. Polycyclic aromatic hydrocarbons (PAHs) plus C02/cosolvent. J. Supercrit. Fluids 1997, 11, 37-51. 

The solubility of solids in supercritical fluids is a very sensitive function of temperature and pressure. Unlike liquids, supercritical fluids are highly compressible and minor temperature or pressure changes lead to large changes in density and, therefore, solvent power QJ. The expansion of supercritical solutions, therefore, results in a substantial solubility decrease. The solubility of Naphthalene in carbon dioxide at 45 C, for example, decreases by about two orders of magnitude upon reducing the pressure from 127 to 62 bars (21. If this... 

Johnston KP, Eckert CA. An analytical carnahan-starling van der Waals model for solubility of hydrocarbon solids in supercritical fluids. AIChE J 1981 27 773. 

Johnston, K. P., D. H. Ziger, and C. A. Eckert. 1982. Solubilities of hydrocarbon solids in supercritical fluids The augmented van der Waals treatment. Ind. Eng. Chem. Fundam. 21 191. 

In the last one and a half to two decades, the KB theory of solutions was successfully used to predict the solubility in numerous systems. Indeed, it is quite impressive that one method was successful for such different systems as those examined in this chapter the solubility of gases and drugs and hydrophobic organic pollutants in binary and multicomponent mixed solvents and the solubility of protein. In addition, this method was successfully applied to the solubility of solids in supercritical fluids, to the solubility of mixed gases in individual solvents, to the explanation of salting-out phenomena (Ruckenstein and Shulgin 2009). In some cases (multicomponent mixtures) the KB theory of solutions constitutes the most powerful theoretical method for investigating the thermodynamic properties. 

Kumar, S. K. and K. P. Johnston. 1988. Modelling the solubility of solids in supercritical fluids with density as the independent variable. Journal of Supercritical Fluids. 1, 15. 

Kwiatkowski, J., Z. Lisicki, and W. Majewski. 1984. An experimental-method for measuring solubilities of solids in supercritical fluids. Berichte der Bunsen-Gesellschc -Physical Chemistry Chemical Physics. 88, 865. 

Using SFC facilities, solubilities of sparsely soluble solids in supercritical fluid solvents can also be measured as a function of pressure and temperature. 

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