Supercritical desorption of limonene and linalool from silica gel: experiments and modelling

Abstract

Supercritical CO2 was used to desorb limonene, linalool and their mixtures from silica gel to simulate the deterpenation of citrus peel oils. The influence of pressure, temperature, CO2 flow rate and solute loading on the desorption process was studied. The maximum selectivity was obtained by operating at 40°C, 0.1 kg/kg loading and in two successive pressure steps. The first step was performed at 75 bar and produced the selective desorption of limonene; the second one was performed at 200 bar and assured the fast desorption of linalool. Desorption isotherms were also obtained from the desorption data. A Langmuir-like equation provided the best representation of the experimental data for single compounds and for their mixtures. The supercritical desorption process was successfully modelled using an equilibrium model based on the integration of differential mass balances. The desorption of single compounds and of limonene-linalool mixtures was fairly well fitted.