Diffusion of water and ethanol in ion-exchange membranes: limits of the geometric approach

Citation
V. Freger et al., Diffusion of water and ethanol in ion-exchange membranes: limits of the geometric approach, J MEMBR SCI, 160(2), 1999, pp. 213-224
Citations number
41
Categorie Soggetti
Chemistry,"Chemical Engineering
Journal title
JOURNAL OF MEMBRANE SCIENCE
ISSN journal
03767388 → ACNP
Volume
160
Issue
2
Year of publication
1999
Pages
213 - 224
Database
ISI
SICI code
0376-7388(19990722)160:2<213:DOWAEI>2.0.ZU;2-F
Abstract
Diffusion coefficients of water as a solvent and ethanol as a tracer in sul phonated polyethylene (SPE) were measured by the pulsed-gradient spin-echo NMR method. Comparison with the data available for a number of ionic and no n-ionic polymers and solvents shows that, except for Nafion, all the materi als exhibit a fairly universal dependence of diffusivity on the volume frac tion of the solvent. This result is explained on the basis of the geometric obstruction approach and general conditions are formulated for the observe d universal dependence. Explanations are proposed for the peculiar behaviou r of Nafion and for the low diffusivity of ethanol within the same framewor k. (C) 1999 Elsevier Science B.V. All rights reserved.