B. Helfgen et al., Theoretical and experimental investigations of the micronization of organic solids by rapid expansion of supercritical solutions, POWD TECH, 110(1-2), 2000, pp. 22-28
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.