ABSTRACT
Carbon dioxide has many properties that make it an attractive solvent, including low toxicity, nonflammability, and an environmentally benign nature. It has been proposed as a “green” alternative to traditional organic solvents because it is neither regulated as a volatile organic chemical (VOC) nor restricted in food or pharmaceutical applications. Both liquid and supercritical CO2 have been exploited as solvents; however, it has been suggested that supercritical fluids have the additional benefit of “solvent tunability” (1). Small changes in pressure in the supercritical region lead to considerable changes in fluid density, which in turn, lead to changes in solvent properties. Under supercritical conditions, CO2 like all supercritical fluids, offers mass transfer advantages over conventional organic solvents owing to its gaslike diffusivities, low viscosity, and vanishing interfacial tension.
