PERVAPORATION OF DILUTE ORGANIC-WATERS MIXTURES - A LITERATURE-REVIEW ON MODELING STUDIES AND APPLICATIONS TO AROMA COMPOUND RECOVERY

Pervaporation as a tool for the removal of organic substances from dilute aqueous solutions has been reviewed. During pervaporation the membrane governs the performance of the process. The removal of organics from water is accomplished with membranes made of elastomeric or hydrophobic polymer materials. The performance of these membranes, measured as fluxes and enrichment factors, differs considerably. Total fluxes vary between 24 and 2728 g/m2-hr while the enrichment factor varies between 0.6 and 372. Modelling of the process involves four successive steps, a mass transfer from the bulk of the feed to the feed-membrane interface, partition of the penetrants between the feed and the membrane, diffusion in the membrane and desorption at the membrane-permeate interface. All these steps are crucial for the overall performance of the process. Several models with different approaches and validities exist for each step. The possible use of pervaporation for aroma compound recovery has been verified in a number of studies. These studies indicate that aroma compounds, especially volatile aroma compounds, can be enriched several hundreds of times with pervaporation and that the process could be profitable.