Ammonia permeabilities of perfluorosulfonic membranes in various ionic forms

Yuankang He, E. L. Cussler

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Perfluorosulfonic membranes like Nafion are much more permeable to ammonia than to hydrogen or nitrogen. This permeability is a strong, complex function of temperature. At room temperature, this membrane has a selectivity about three thousand and an ammonia flux about five times greater than that through polyvinylammonium thiocyanate, the other known highly ammonia-selective membrane. This flux depends on the membrane's counterion in the following order: H+ > Na+ > Ag+ NH+4 > Zn2+ > Li+ > Cu2+ > K+. As the temperature rises, the ammonia flux and selectivity both decrease, much as they do in the thiocyanate-based membrane. Flux and selctivity pass through a minimum around 150°C. At higher temperatures, the ammonia flux rises and the membrane remains up to sixty times more permeable to ammonia than to nitrogen. The flux now depends on the membrane's counterion in a different order: Ag+ > H+ > Na+ > Li+ > Cu2+ > NH+4. The variation of flux with ammonia pressure implies that the transport mechanism is different at lower and at higher temperatures.

Original languageEnglish (US)
Pages (from-to)43-52
Number of pages10
JournalJournal of Membrane Science
Volume68
Issue number1-2
DOIs
StatePublished - Apr 10 1992

Keywords

  • gas separations
  • ion exchange membranes
  • transport

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