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Separation of liquid mixtures by using polymer membranes. II. Permeation of aqueous alcohol solutions through cellophane and poly(vinyl alcohol)
Author(s) -
Huang Robert Y. M.,
Jarvis Neil R.
Publication year - 1970
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1970.070140914
Subject(s) - permeation , cellophane , vinyl alcohol , membrane , alcohol , polymer , polymer chemistry , chemistry , chemical engineering , aqueous solution , materials science , organic chemistry , biochemistry , engineering
The permeation and separation characteristics of four different alcohol—water systems through cellophane and poly(vinyl alcohol) membranes were investigated. The homologous series of linear alcohols n ‐propanol, ethanol, and methanol as well as isopropanol were studied. A specially designed permeation cell was used to study permeation rates at temperatures ranging from 30° to 50°C. The dependency of both permeation and separation on the molecular size and shape of the permeating species was discussed qualitatively. The temperature dependence of the permeation rate for both pure compounds and binary mixtures was expressed by Arrhenius‐type relationships. The rate was found to increase with increasing temperature while the separation decreased. Activation energies of 4–9 kcal/mole were calculated for alcohol—water solutions through cellophane, and of 8–15 kcal/through poly(vinyl alcohol). Departure of permeation rates from the ideal rates were discussed in terms of permeation “enhancement” or “depression.” These phenomena were explained in terms of both the plasticizing action of water and the “clustering” of water molecules within the polymer network.