| This research investigated the transport properties of commercially available electrodialysis (ED) ion exchange membranes. A series of experiments were designed in order to yield a better understanding of the individual transport phenomena that occur during electrodialysis, specifically, the diffusive and pressure-driven permeation of salt and water through the ion exchange (IEX) membranes (which provides the inherent water and salt selectivity of the membranes), and finally, the electrodialysis performance of IEX membranes under an elevated applied pressure.; Pure water permeabilities of the selected IEX membranes were found to range over nearly 4 orders of magnitude, from 7.7 x 10-12 m·s -1·kPa-1 to 1.6 x 10-9 m·s -1·kPa-1. Generally, the permeability for the anion exchange (AEX) membranes was less than that of the cation exchange (CEX) membranes from the same manufacture.; NaCl diffusion coefficients, for the Selemion AEX and CEX membranes are reported to be 4.6 x 10-12 m2·s -1 and 2.3 x 10-12 m2·s -1 respectively for experiments with an initial feed concentration of 5 000 ppm NaCl. (Abstract shortened by UMI.)... |
