PERMEATION RATES IN THE PERVAPORATION OF WATER-ETHANOL MIXTURES USING NAFION MEMBRANE

Sorption-diffusion model was used to study permeation rates of water and ethanol using Nafion membrane. The ratio of bulk flow to permeation flux was quite large when the permeation flux of a key permeate was much lower than that of the other permeate, which means that bulk flows are not always negligible. Diffusion equations were expressed with the concentration gradient of the key permeate alone, and a concentration-dependent diffusion coefficient which includes a parameter was used. The one-parameter equation excellently correlated measured permeation rates. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.