Improved Recovery of an Ester Flavor Compound by Pervaporation Coupled with a Flash Condensation

The recovery of an aroma compound, ethyl acetate, highly diluted in model aqueous feeds was carried out with a pervaporation stage coupled to a flash condensation. The permeate, at the vapor state, was selectively fractionated between two condensers in series with decreasing temperatures. A global modeling of the coupling system was proposed, taking into account the extraction step (with transmembrane mass transfer equations) as well as the recovery step (with flash vapor−liquid equilibrium curves). It was shown that the inert gases flowing in the permeate circuit (which were due to unavoidable air leakage) were inducing a dilution of the condensable permeate vapors, leading to a significant lowering of the dew point of the permeate. If compared to pervaporation with conventional total permeate condensation, the coupling of pervaporation with a flash condensation led to a significant enhancement of the selectivity for the recovery of ethyl acetate.