Manufacture of submicron particles via expansion of supercritical fluids

A pilot plant is presented which has been built to prepare fine particles b y rapid expansion of supercritical solutions (RESS process). This technique offers interesting applications for products that are produced in small am ounts, such as certain pharmaceuticals or energetic materials. For the pres ented research, cholesterol was used as a model substance for pharmaceutica ls. Our measurements were carried out with two different Laval nozzles with a 100 and 150 mu m diameter, respectively In contrast to investigations of other groups the scale of the plant is larger which results in a higher fl ow and production rate. The mean size of the particles measured by photon c orrelation spectroscopy (PCS) was about 400 nm. The influence of the extrac tion temperature, pre-expansion pressure and nozzle diameter on the particl e size is not very marked and systematic.