Electrodialysis Nafion membranes

CR-61 membranes supplied by Ionics Incorporated, (Watertown, MA), were the only kind used in our electrodialysis experiments. Nafione membranes were mounted on electrodialysis cell frames and in some cases tested for leaks, but we did not have the opportunity to use them in an actual electrodialysis run. 

The use of Nafion membrane as a proton conductor has been mentioned in a three-compartment electrodialysis set-up for converting sodium salicylate to salicylic acid . Use in Donnan analysis for the recovery of Cu ions from dilute solutions has been described . These metal ions are transferred through the membrane. The driving force is the proton-motive force resulting from the proton concentration difference between the two sides of the membrane. The diffusion flux of protons is coupled to a counter-transport of metal ions. 

Many of today s available membranes meet most of these requirements. In particular, the Nafion-type cation-exchange membrane has quite satisfactory properties for applications in the chlorine-alkaline electrolyses as well as in electrodialysis [6], Anion-exchange membranes often show lower stability in strong alkaline solutions than cation-exchange membranes. 

Y. Mizutani, R. Yamane, T. Sata and R. Izuo, Cation exchange membrane to selectively permeate hydrogen ions and electrodialysis method to selectively permeate hydrogen ions, Jpn. Pat. JP 47-3801 (examined application) Z. Ogumi, Y. Uchimoto, M. Tsujikawa, K. Yasuda and Z. Takehara, Modification of ion exchange membrane surface by plasma process. Part 3. Interfacial resistance of monovalent permselective membrane from Nafion, Bull. Chem. Soc. Jpn., 1990, 63, 2150. 

Despite great efforts, this has not been achieved until now. Existing types of anion-exchange membranes (used for electrodialysis) are far inferior to Nafion, both in their conductivity and in the chemical and thermal stability. Therefore, one cannot so far meaningfully discuss their potential as substitutes for the circulating or matrix electrolyte in alkaline hydrogen-oxygen fuel cells. 

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