INFLUENCE OF SORPTION AND DIFFUSION OF AROMA COMPOUNDS IN SILICONE-RUBBER ON THEIR EXTRACTION BY PERVAPORATION

Pervaporation was used to extract aroma compounds from dilute aqueous solutions. The use of a stirred cell allowed the reduction of the boun dary layer effect which can be estimated using a mass transfer correla tion. A resistance-in-series model was used to describe the flux of or ganic compounds through a silicone membrane. Calculation of the membra ne resistance required the determination of the solubility and diffusi on coefficients of the aroma substances in the polymer. These two char acteristics were obtained by measuring the quantities of the aroma sor bed on the silicone at equilibrium and by studying the kinetics of sor ption. At low concentration ranges, both characteristics were constant . They can be related to the hydrophobicity, the molar volume and the flux of the substances through the silicone membrane during pervaporat ion.