Supercritical fluid extraction of vegetable oils: Different approaches to modeling the mass transfer kinetics

Supercritical fluid extraction (SFE) of vegetable oils is an alternative method to organic solvent (namely hexane) and mechanical extraction. To exploit the SFE technology at industrial scale, the process has to be optimized. An effective way to perform optimization is to resort to models that are capable to describe and simulate the SFE process. Plenty of models are available in the literature concerning the SFE of vegetable oils. Modeling the process in a semi-continuous extraction column (the bed of matrix to be extracted is stationary, the supercritical fluid moves continuously through it) requires an equipment model, the column model, and a particle model accounting for mass transfer mechanisms. Column models are quite established. Thus, to achieve a satisfactory description of the process, having a very effective particle model seems the key-point. In this work the SFE kinetics of seed oil (namely: grape seed oil) was modeled using different particle models: the broken and intact cells (BIC) and the shrinking core (SC) models, and the results were compared with literature values obtained utilizing the combined BIC-SC model. The three models not only allowed to fit satisfactorily the experimental data, but also resemble the real physical structure of the vegetable matrix and the actual elementary steps (mass transfer phenomena) which are expected to occur at the microscale level. As a whole, the present analysis provides an insight of interest for the audience concerned with modeling the SFE process.