Abstract
The surface of gel-type anion exchange resin was modified by the adsorption of an anionic polyelectrorite: polycondensation product of sodium naphthalene sulfonate and formaldehyde (trade name, Demol N). After the adsorption of the polymer, ion exchange capacity decreased and the rate of ion exchange reaction became slow though ion exchange equilibrium constants between two anions did not changed. Especially, the ion exchange rate of divalent anions was slower than that of the monovalent anions. Because an anionic polyelectrorite layer was formed on the resin particle, the ion exchange of anions with anion exchange site was retarded by sieving effect with the layer and the divalent anions were difficult to ion exchange compared with the monovalent anion due to existence of the opposite charged layer to ion exchange groups. Using the modified anion exchange resin in the hydroxide ion form, separation of nitrate ion from sulfate ion was attempted. The modified resin was immersed in the mixture solution of nitrate and sulfate ions, and the solution was shaken for definite time. The nitrate ion was preferentially adsorbed on the resin. The resin was separated and introduced in the potassium perchlorate solution. After shaking for 90minutes, the nitrate ion in the solution was determined by use of ion-chromatography. The separation and enrichment of nitrate ion from 50-fold amount of sulfate ions was accomplished.
