MODELING AND SIMULATION OF THE SUPERCRITICAL ADSORPTION OF COMPLEX TERPENE MIXTURES

Thirteen terpenes forming a mixture that is characteristic of peel ess ential oils have been simultaneously adsorbed on silica gel from super critical CO2. They have been divided into four pseudo-components accor ding to the similarity of their behavior during the adsorption process . An equilibrium model based on differential mass balances written for the fluid and the solid phase was proposed. The numerical integration of the four partial differential equations resulting from the model w as performed using the Wendroff method. The computational molecule was modified with respect to the original method. A molecule of variable geometry was adopted to avoid numerical oscillatins in the solution of the problem. The breakthrough time and the maximum concentration of t he four pseudo-components were fairly well modelled. The consecutive d isplacement of the various pseudo-components by those more strongly ad sorbed was also well described by the proposed model when compared to the experimental data. The simulation of the concentration profiles of the pseudo-components along the adsorption bed at increasing processi ng times was also proposed. It was possible to describe the onset and the evolution of displacement waves of the pseudo-components along the bed. (C) 1998 Elsevier Science Ltd. All rights reserved.