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 supercri tical fluid extraction (SFE) of essential oil from orange peel is analyzed in this article. Peel of dehydrated oranges of the satsuma and naveline cul tivars was used. A series of experiments were designed wherein, for the sam e conditions, particle height varied widely. These experiments were also ca rried out on different scales with extraction volumes of 0.5 and 5 1. The r esults of the experiments were interpreted using Sovova's extended flow mod el 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 part icles 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 situatio n can cause a lack of homogeneity in the fluid, further reducing the effect iveness of the process. In the experiments with the satsuma cultivar, where the bed-height range was broader, a base of diatomaceous earth was added i n the extractor in order to reduce the lack of homogeneity in the fluid flo w. Very similar behavior was found in all the experiments and we can, there fore, conclude that where there is homogeneous flow the height of the bed h as very little effect, at least on the same scale of operation. (C) 2000 El sevier Science B.V. All rights reserved.