Transport Phenomena Associated to Supercritical Extraction

Abstract

Supercritical fluid extraction is one of the most attractive technologies for extracting valuable compounds from vegetables matrices due to several reasons such as higher yields, extracts free of solvents and because it is an ecological alternative. A supercritical fluid presents favorable transport properties for extracting valuable compounds. For instance, the density of a supercritical fluid is very closer to a liquid and thus, high solvation power is gained for extracting valuable compounds. Low viscosity and high diffusion coefficients are other characteristics of a supercritical fluid that confer an excellent solvent penetration in the solid matrix and thus, large extraction yields. However, many factors can affect the mass transfer from solid matrix to the solvent at supercritical conditions such as particle size of the solid matrix, pressure, temperature, solvent flow and time of extraction among others. For a best understanding of transport phenomena in the supercritical extraction issues such as bed porosity, axial dispersion and gradients of temperature and pressure can be attended and modeled for describing the extraction yield as well as other important parameters related with mass and energy transfer.