Separation and enrichment of nitrate ion from sulfate ion by the use of a modified anion-exchange resin

摘要

The surface of a gel-type anion exchange resin in the hydroxide form was modified by the adsorption of an anionic polyelectrolyte: a polycondensation product of sodium naphthalene sulfate and formaldehyde. Afer adsorption of the polymer, the rate of the ion-exchange reaction became slow. Especially, the ion-exchange rate of the sulfate ion was slower than that of the nitrate ion. Using the modified resin, in spite of the pres- ence of the sulfate ion, the nitrate ion was preferentially adsorbed from the mixture solu- tion of the nitrate and sulfate ions. The adsorbed ions were desorbed from the resin by use of potassium perchlorate or perchloric acid solutions. With these procedures, it was possible that the nitrate ion in the sulfate ion, the amount of which was 200-fOld that of the nitrate ion, was separated and determined by ion-chromatography. The enrichment of nitrate ions to 50-fOld its original concentration was also possible.