Versatic Acid 10による塩化ナトリウム水溶液からのPb<SUP>2+</SUP>, Cu<SUP>2+</SUP>およびZn<SUP>2+</SUP>の抽出特性

Abstract

The role of sodium chloride in the extraction of Pb2+, Cu2+ and Zn2+ with Versatic Acid 10 from aqueous sodium chloride solution was studied. The extracted species of these metal ions from their sodium chloride solutions were found to be the same with those extracted from perchlorate or nitrate solutions. The plots of logD versus pH for Pb2+ and Zn2+ extraction simply shift towards a higher pH side with the increase in sodium chloride concentrations, while those for Cu2+ extraction exhibit the maximum pH values at a certain sodium chloride concentration. The extraction curves still show a considerably big deviation, after removing the effect of the formation of chloro-complexes of these metal ions. This suggests that the other factors except complex formation affect the extraction reactions.The salting-out effect due to the presense of sodium chloride in an aqueous phase was examined to explain such a big deviation. The pH values at 50% extraction experimentally determined for these metal ions coincide well with those calculated by using the pH values at 50% extraction determined for the extraction of these metal ions from aqueous perchlorate or nitrate solutions and respective by-reaction coefficients, although a slight deviation is observed for Pb2+ extraction.Based on the findings obtained by the fundamental study mentioned above, the separation of Pb2+, Cu2+ and Zn2+ from a mixed solution of these metal ions containing sodium chloride was studied. It was found that the separation of Pb2+ from Cu2+ became easier by adding sodium chloride to an aqueous phase.