Selective Separation of Organic Electrolytes by Neutralization Dialysis with Grafted Polyethylene Films

The selective separation of organic electrolytes by neutralization dialysis was investigated with two kinds of grafted polyethylene (PE) films prepared through the photografting of 2-(dimethylamino) ethyl methacrylate (DMAEMA) onto the PE films and the subsequent quaternization and through the photografting of glycidyl methacrylate (GMA) and the subsequent sulfonation. The permeation flux of benzoic acid (BA) for the quarternized DMAEMA-grafted PE (PE-g-QPDMAEMA) films increased with an increase in the degree of quaternization, and the BA permeability had the maximum at the initial pH value of the permeate solution of 12.0. On the other hand, the sulfonation offered the phenylalaninol (Phl) permeability of the GMA-grafted PE (PE-g-PGMA) films. The selective separation for the binary BA/Phl or 2,5-dichlorobenzoic acid/Phl systems was successfully achieved by use of a pH difference between the feed and permeate solutions through the PE-g-QPDMAEMA and sulfonated PE-g-PGMA (PE-g-SPGMA) films. The maximum selective separation was obtained under the conditions that the initial pH values of the permeate solutions through the PE-g-QPDMAEMA and PE-g-SPGMA films were adjusted to 12.0 and 2.0, respectively. This procedure will be applied to separation and concentration of organic electrolytes and water purification.