STUDY OF MASS-TRANSFER LIMITATIONS IN THE DETERPENATION OF WASTE-WATERS BY PERVAPORATION

Waste waters from the essential oils industry contain terpenes which h ave to be recovered, and pervaporation proved to be an efficient metho d for that purpose. In order to identify the mass transfer limitations during the pervaporation of two particular solutes, linalool and euca lyptol, experiments were performed with different thicknesses of polyd imethylsiloxane membranes under isothermal conditions. Mathematical tr eatment based on a resistances-in-series model shows a good agreement between experimental data and theory. Moreover it can be shown also th at under certain conditions, the limiting step can result from the tra nsfer in the liquid phase, even though in most cases of pervaporation, the limitation lies on the transfer within the polymeric material. Es timation of the diffusivities of the two terpenes in the polymer can b e done from this treatment.