ANION EXCHANGE EXTRACTION AND ENRICHMENT FROM AQUEOUS SOLUTIONS BY QUARTERNARY AMMONIUM REAGENTS

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Abstract
The problems of solvent extraction and ion-exchange-based quantitative enrichment of anions having high hydration energies in aqueous solutions using water-insoluble quaternary ammonium salts are discussed. A new approach to anion exchange extraction of such anions by water-soluble polymeric quarternary ammonium salts is suggested in conjunction with membrane filtration. The retention of oxo anions of arsenic(V)r phosphorus(V), chromium(VI), selenium(IV) and of the fluoride ion with the permethylated derivative of poly-(ethyleneimine) and the influence of different salts on the retention of the anions have been studied and the possibility of quantitative retention of these anions has been demonstrated. For example, the retention for arsenic(V) was found to be 92% and 89% for fluoride with 2% polymer and a filtration factor of seven. After extraction the oxo anions can be stripped off easily in the cell solution up to 99% by 0.1 M HCl or a 0.15 M solution of sodium salts.