Theoretical and experimental investigations of the micronization of organic solids by rapid expansion of supercritical solutions

The RESS-Process (Rapid Expansion of Supercritical Solutions) is an innovat ive and promising technology to produce small particles and offers interest ing applications for difficult-to-comminute species such as certain pharmac euticals. Our RESS-experiments are carried out with an apparatus suitable f or temperatures up to 600 K and pressures up to 60 MPa. Carbon dioxide (CO2 ) and trifluoromethane (CHF3) have been used as supercritical solvents and cholesterol and benzoic acid as solutes. Besides the experimental investiga tions, the RESS-Process is modelled numerically considering the three parts capillary inlet-capillary-microscale free jet. The evolution of fluid pres sure and temperature along the expansion path are used to calculate the sup ersaturation of the real mixtures CO2/cholesterol, CO2/benzoic acid and CHF /benzoic acid and the respective nucleation rates. The results of these cal culations are theoretical nucleation rates of about 10(26) cm(-3) s(-1) at residence times of 10(-7) s in the free jet. (C) 2000 Elsevier Science S.A. All rights reserved.