The Phase Equilibrium And Application Involved In SAS

Many solutes can dissolve in some organic solvents, but do not dissolve in supercritical fluid. At the same time, supercritical fluid can largely dissolve in many organic solvents, which results in a reduction of the solvency of the organic solvents and a precipitation of the dissolved solute. This process is termed as supercritical antisolvent process (SAS) based on the state of the antisolvent So far, this rising technique has been successfully applied in recrystallizing organic compounds, separating mixtures, and producing finely comminuted particles, and its applied foreground is rather widest Whereas, phase equilibrium rule changed with different factors that involved in SAS is rather lack, which is the basis of development and application of this technology. So this report investigated the phase equilibrium involved in SAS and their applications.In Chapter II, an apparatus for investigating phase equilibrium involved in SAS was designed and constructed, which has lots of characteristics such as fast equilibrium, exact precision, facile operation and easing to observe the change of phase state momentarily. In this chapter, the solubility of a-naphthol and P-naphthol in ethanol + carbon dioxide mixtures, of cholesterol in ethanol + carbon dioxide mixtures and in acetone + carbon dioxide mixtures was studied. Solubility data of these pharmaceutical compounds in organic solvents + CO2 have not been found in literature survey. As was shown, the CO2mole fraction in the liquid phase increases with pressure and decreases with temperature. The difference between the solubility of the solutes in the liquid phases influences the CO2 mole fraction in the liquid phase. The solubility of the solutes decreases with pressure and increases withtemperature. For the system of naphthols +ethanol+CO2, there were the differences in their structure that make them behave differently. It was the differences in their solubilities that should enable them to be separated and purified from a mixture by a CO2 antisolvent process. In so far as cholesterol-ethanol/acetone-CO2 system, the solubilities of cholesterol differed in diverse solvents was the basis of recrystallizing organic compounds by supercritical antisolvent process.In Chapter III, on the basis of the phase equilibrium of genistein and daidizein, we combined SC-CO2 antisolvent process with abstraction by organic solvent, which was successfully utilized to abstract soybean isoflavone. The concentrations of Genistein in the products are higher than 90%, respectively, which implies that SAS is an effective technique for using the resource of isofavone.In Chapter IV, On the basis of phase behavior, cholesterol was recrystallizated in ethanol and acetone with CO2, respectively. The morphology of particles generated in different solvent was detected by SEM. The crystallization of cholesterol was performed by changing various operating conditions: injection rate of CO2 into the crystallizing chamber, initial concentration in ethanol or acetone, and temperature and the end pressure. The result indicated that the effect of operating parameters on the size distribution and morphology was rather evident...