Supercritical Fluid Drying: Classification and Applications

In the last two decades, supercritical fluid drying or supercritical drying has attracted growing interests for its increasing applications in various fields. The purpose of this review is to summarize the recent patents in literature about supercritical drying with the introduction of different technologies and applications. To avoid confusion, supercritical drying is conveniently classified into five types, namely, they are supercritical organic solvent drying, supercritical gas drying, supercritical mixture solvent drying, supercritical gas extraction-drying, and supercritical fluid-assisted spray drying of aqueous solution for preparing fine particles. The former four techniques are classified according to the applied supercritical solvent, and can be particularly applied to drying porous materials. Supercritical fluid-assisted spray drying uses supercritical fluid as the atomizing gas and the carrier of moisture. The applications of supercritical drying in the production of aerogel and other porous materials, drying of pharmaceuticals and foods, and the production of microelectromechanical systems are summarized.