PREDICTION OF PERVAPORATION SEPARATION CHARACTERISTICS FOR THE ETHANOL-WATER-NYLON-4 MEMBRANE SYSTEM

The modified Fels and Huang model has been extended to predict the separation factors and permeabilities more accurately for the system of ethanol-water-nylon-4 membranes. In this system, the binary interaction parameters, g13 and g23, are assumed to be concentration dependent. In order to evaluate these binary interaction parameters, the relationship of the prediction of sorption capability for a given binary mixture into the membrane is developed with and without the consideration of osmotic equilibrium between the polymeric membrane and the binary mixture. The permeabilities of each component for the entire range of the feed mixture at various operating temperatures are then calculated using the predicted sorption capabilities. The experimentally determined diffusion coefficient at zero concentration and the solubility of the pure component are compared with the actual experimental permeabilities. When the osmotic pressure term was taken into consideration, it was found that the calculated individual permeabilities are fairly close to the experimental permeabilities.