Application of Supercritical Fluids

Many advantages of supercritical fluids come from their interesting or unusual properties which liquid solvents and gas carriers do not possess. Such properties and possible applications of supercritical fluids are reviewed. As these fluids never condense at above their critical temperatures, supercritical drying is useful to prepare dry-gel. The solubility and other important parameters as a solvent can be adjusted continuously. Supercritical fluids show advantages as solvents for extraction, coating or chemical reactions thanks to these properties. Supercritical water shows a high organic matter solubility and a strong hydrolyzing ability. Supercritical water is expected to be useful in waste treatment. Although they show high solubility solutes and molecular catalyses, solvent molecules under supercritical conditions gently solvate solute molecules and have little influence on the activities of the solutes and catalysts. This property would be attributed to the local density fluctuations around each molecule due to high molecular mobility. The fluctuations in the supercritical fluids would produce heterogeneity that would provide novel chemical reactions with molecular catalyses, heterogenous solid catalyses, enzymes or solid adsorbents.