Mass transfer in Nation membrane systems: Effects of ionic size and charge on selectivity

T. Xue, R. B. Longwell, K. Osseo-Asare

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The interdiffusion of metal ion-hydrogen ion couples in Nation membrane systems has been measured by a rotating diffusion cell (RDC) technique. At low metal concentrations, the transport rate is controlled by boundary layer diffusion and the metal flux follows the order Li+ < Na+ < K+ < Rb+ < Cs+ for alkali metals, and Ca2+ < Sr2+< Ba2+ for alkaline earth metals. At high metal concentrations, the transport process is controlled by membrane diffusion and the order of the flux is Li+ <Cs+ <Rb+ <Na+ <K+ for alkali metals, Ca2+<Ba2+<Sr2+ for alkali earth metals, and Y+ <Ca2+ < Na+ for ions of similar ionic size (0.93-0.99 Å) but different charge. The results are interpreted in terms of ionic hydration coupled with charge and size effects.

Original languageEnglish (US)
Pages (from-to)175-189
Number of pages15
JournalJournal of Membrane Science
Issue number2
Publication statusPublished - May 15 1991


All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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