Comparison between Pervaporation and Vapor Permeation for Separation of Water-Alcohol Mixtures Using a Polyion Complex Membrane.

The permeation fluxes for mixtures of water-ethanol at 343 K and water-2-propanol at 356 K were determined in pervaporation and vapor permeation experiments using a polyion complex membrane. The total permeation fluxes and separation factors were calculated by applying solution-diffusion theory to the data in both experiments, and separation indexes were obtained as the product of the calculated values of total permeation fluxes and separation factors. The separation indexes for water-ethanol and water-2-propanol mixtures in the pervaporation were higher than those in the vapor permeation at mole fraction of ethanol in feed solution above 0.82 and at that of 2-propanol above 0.43, respectively.