Effects of feed-side solute polarization on pervaporative stripping of volatile organic solutes from dilute aqueous solution: a generalized analytical treatment

• Published in: Journal of membrane science 1995-05, Vol.101 (1), p.117-126
• Main Author: Michaels, Alan S.
• Format: Article
• Language: English
• Subjects: Analytical treatment; Feed-side solute polarization; Pervaporative stripping
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/0376-7388(94)00288-A

A simplified analytical model of solute and solvent transport for a dilute solution of a sparingly soluble volatile organic compound in aqueous solution during pervaporation through a solute-permselective membrane graphically demonstrates the importance of feed-side boundary layer resistance on the overall selectivity and capacity of the separation process. Nomographs allowing prediction of operating performance characteristics for pervaporation (e.g., enrichment ratio, process selectivity, and solute permeation flux) from a knowledge of a small number of readily-accessible thermodynamic and physicochemical properties of the liquid-phase components and membrane, and of feed-side hydrodynamic parameters, are presented. The analysis reveals that, even under the most favorable conditions for minimizing feed-side polarization, pervaporative separation of components in such systems is severely compromised by feed-side boundary layer transport resistance. Operating conditions needed to optimize pervaporative performance are proposed. It is suggested that, for such systems, a hybrid process comprising staged liquid/liquid extraction in combination with liquid/liquid separation by crossflow microfitration may be a more practical and economic approach to this important problem.