New fractionation process for citrus oil by pressure swing adsorption in supercritical carbon dioxide

A new technique for fractionation of citrus oil was proposed. A pressure sw ing adsorption process in supercritical carbon dioxide (SC-CO2) was develop ed with silica gel as adsorbent. Adsorption equilibrium properties and adso rption-desorption dynamics were measured. Adsorption isotherms were represe nted by a multicomponent Langmuir equation. Desorption curve after the equi librium saturation indicated that the rinse step to elute the solutes in th e void space of the adsorber is required in order to achieve a higher conce ntration factor. Based on these results, continuous pressure swing operatio n between the adsorption step at 8.8 MPa and 313 K and the desorption step at 19.4 MPa and 313 K, including the rinse step, was demonstrated. Effects of feed concentration, half cycle time, and CO2 flow ratio were studied. Hi ghly concentrated fraction of oxygenated compounds was continuously obtaine d for the desorption step and the blowdown step (depressurization). A mathe matical model simulated well the behavior of the pressure swing adsorption. (C) 1998 Elsevier Science Ltd. All rights reserved.