Kinetic Research for Separation Function of Lonic Polymer Gel

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The dependence of gel swelling behavior and ionic behavior on external conditions (salt concentrations, pH, electric field) were investigated experimentally and theoretically. The results are as follows :1. The effects of electrolytes and pH on the swelling behavior of acrylamide gel containing both acrylic acid and trimethyl-N-acryloyl-3-aminopropyl ammonium chloride were investigated. It was found that swelling behavior could be explained to consider the dissociation of charged groups and ion exchange between the gel and the outer solution. The model based on Donnan equilibrium theory was found to describe the swelling behavior of the gel and the concentrations of freely mobile ions in the gel after ion exchange.2. The mechanism of shrinkage and dehydration of ionic hydrogels packed in an electric cell were investigated on the basis of the distribution of pH around the gel, the Na^+ ion concentration within the gels packed in the cell and the dehydration rate. It was found that shrinkage and dehydration of the ionic gels take place through the following processes :(1) generation of H^+ and OH^- ions by electrolysis ; (2) ion exchange between H^+ ions generated on the anode and Na^+ ions dissociated originally within the gels ; (3) accumulation of Na^+ ions near the cathode by electrophoresis ; and (4) increase in ionic strength near the cathode caused by process (3). Therefore, the shrinkage and dehydration of ionic gels depend on the generation of H^+ ions by electrolysis and electrophoresis of Na^+ ions.