Oxygen permeation through perfluorinated carboxylate ion exchange membranes

Abstract

Permeation of oxygen through perfluorinated carboxylate membranes (Flemion ®) of different counterions and equivalent weights (EW = 700 and 800) was investigated. Solubilities and diffusion coefficients of oxygen in the membranes were determined by an electrochemical monitoring technique using solid polymer electrolyte composite electrodes. The solubilities were close to the values in perfluorocarbon media rather than to the value in water. The solubility decreased with increasing water content of the membranes. The diffusion coefficient in 700 EW membranes increased with increasing water content, while that in 800 EW membranes decreased slightly. On the basis of these results, the diffusion path of oxygen through the membranes was discussed in terms of morphological properties of perfluorinated ion exchange membranes.