Supercritical CO2 extraction of essential oil from orange peel;: effect of the height of the bed

The influence of the height of the particle bed on the kinetics of supercritical fluid extraction (SFE) of essential oil from orange peel is analyzed in this article. Peel of dehydrated oranges of the satsuma and naveline cultivars was used. A series of experiments were designed wherein, for the same conditions, particle height varied widely. These experiments were also carried out on different scales with extraction volumes of 0.5 and 5 1. The results of the experiments were interpreted using Sovova's extended flow model as has been done in previous studies. The bibliography indicates that a number of phenomena may distort the process. One of these phenomena is the formation of masses of particles, due to their oil content, which increases resistance to mass transfer inside the particle. However, this phenomenon was barely noticeable in our experiments. Also, some reordering of the particles may take place due to the differing densities of the two phases and a certain drag effect exercised on the particles by the fluid. This situation can cause a lack of homogeneity in the fluid, further reducing the effectiveness of the process. In the experiments with the satsuma cultivar, where the bed-height range was broader, a base of diatomaceous earth was added in the extractor in order to reduce the lack of homogeneity in the fluid flow. Very similar behavior was found in all the experiments and we can, therefore, conclude that where there is homogeneous flow the height of the bed has very little effect, at least on the same scale of operation. (C) 2000 Elsevier Science B.V. All rights reserved.