Ion penetration through tubular ion exchange membranes

Permitted and Donnan forbidden ion penetration rates through small diameter ion membrane tubes have been studied for a number of ions and membrane types. Membranes include radiation grafted poly(tetrafluroethylene) and poly(ethyl vinylacetate) cation and anion exchangers and perfluorosulfonate (Naflon 811x and 815x) cation exchanger tubes. For cation exchangers, Cu2+ was the model permitted cation, and sulfate, dodecylbenzenesulfonate, naphthalenedisulfonate, naphthalenetrisulfonate and poly(styrenesulfonate) were the anions (tested as the corresponding acids) for which penetration rates were determined. For anion exchangers, nitrate was the model permitted anion and Li+, Na+, NMe4+, NEt4+, NPr4+, and poly(diallyidimethylammonium)/sup n/+ were the cations (tested as the corresponding hydroxides) studied. Forbidden ion penetration decreases with increasing size and charge of the ion and is effectively elminated with large, multiply charged polymeric or micellar ions. For a given ion, the concentration dependence of the penetration rate is accurately predicted by a second-order equation. 11 references, 1 figure, 5 tables