Supercritical CO2 extraction of grape seed oil: Effect of process parameters on the extraction kinetics

The effect of the main process variables affecting the supercritical CO2 extraction of oil from seeds (namely grape seeds) was investigated, both experimentally and through modeling. The dependency of the extraction kinetics on the variables more tested in the literature (pressure, temperature, particle size and solvent flow rate) was confirmed, and original trends were obtained for the less investigated variables, such as the bed porosity ɛ and the extractor diameter to length ratio (D/L). The extraction kinetics did not depend on ɛ for 0.23 ≤ ɛ ≤ 0.41, while a further decrease in ɛ lowered the extraction rate, likely due to the occurrence of channeling. The effect of a variable D/L ratio was studied letting constant the ratio of substrate mass to CO2 mass flow rate: the lower was D/L, the lower the specific CO2 consumption. Through modeling, the values of internal and external mass transfer parameters were calculated and critically discussed on the basis of well-known literature correlations.