PERVAPORATION OF AROMA COMPOUNDS IN WATER ETHANOL MIXTURES - EXPERIMENTAL-ANALYSIS OF MASS-TRANSFER

In the field of biotechnology and food technology the main applications of pervaporation through hydrophobic membranes are the extraction of aroma compounds from aqueous mixtures and the production of low alcohol wines. Pervaporation results on simple synthetic aqueous mixtures of three aroma compounds (propanol, ethyl acetate and ethyl butyrate), with or without ethanol (10% weight fraction), are presented in order to feature both types of application. All pervaporation runs were performed through a dense poly-dimethyl-siloxane (PDMS) membrane in a 0.1-m2 plane module, at different feed temperatures and permeate pressures. The influence of operating conditions were more significant on permeate fluxes than on selectivities. Ethanol seemed to have an important effect on aroma fluxes. Mass transfer of esters through a pervaporation membrane is higher than that of alcohols. Yet, pervaporation selectivities were of the same magnitude or lower (for esters) than those from liquid-vapour thermodynamic equilibrium.