Supercritical Fluid Particle Designs SAS and RESS
Supercritical Anti Solvents: SAS
Polar materials do not dissolve in supercritical carbon dioxide. Current processes involve mechanical grinding, which usually produces enough heat to convert these products into a paste. Typically in an SAS process, the material is dissolved in a solvent and then sprayed into a high pressure chamber filled with supercritical carbon dioxide. As each droplet is formed in the high pressure vessel, the carbon dioxide extracts the solvent leaving behind a powder with low bulk density. This technique is useful for pharmaceutical materials such as insulin, antibiotics, asthma medicine, steroids, and controlled release drugs. By manipulating the pressure, temperature and concentration, one can produce a variety of powder sizes.
Rapid Expansion of Supercritical Solutions: RESS
Until now, there was no easy way to produce micron size powders of thermally labile materials. Current processes involve mechanical grinding that often produces enough heat to convert these products into a paste. However, dissolving the material in supercritical fluids and then spraying it through a nozzle eliminates this problem. Typically, non–polar materials can be dissolved in supercritical carbon dioxide and sprayed, as in spray drying. This technique is called RESS, and its applications include pharmaceutical materials such as steroids, asthma medicine, and controlled release drugs.
The RESS system allows the user to spray non-polar compounds through a nozzle from a supercritical solution. By manipulating the pressure, temperature and concentration, the user can manipulate powder sizes.
