COBALT EXTRACTION BY HDNNS IN THE PRESENCE OF AN ALPHA-HYDROXYOXIME

• Published in: Solvent extraction and ion exchange 1983-01, Vol.1 (2), p.337-347
• Main Authors: Osseo-Asare, K., Renninger, D. R., Wagner, J. D.
• Format: Article
• Language: English
• ISSN: 0736-6299; 1532-2262
• DOI: 10.1080/07366298308918405

The method of slope analysis has been used to analyze cobalt extraction by dlnonylnapthalene sulfonic acid (HDNNS) in hexane/ aqueous nitrate systems in the absence and presence of 0·01 mol dm -3 5,8-diethy1-7-hydroxy-6-dodecanone oxime (H 2 Ox; the active extractant in the commercial reagent, LLX63, a product of Henkel Corp.). In the absence of H 2 Ox, cobalt is extracted by HDNNS micelles and the log D versus log [HDNNS] plot gives a slope of unity. In the presence of 0·01 mol-dm -3 H 2 Ox, the corresponding plot shows a maximum at 5·6×l0 -3 mol dm -3 HDNNS and a minimum at 3×l0 -2 mol dm -3 HDNNS. At low HDNNS concentrations (≤ 5·6×l0 -3 mol dm -3 ), the log D versus log [HDNNS] plot has a slope of 1·0 while at high HDNNS concentrations (≥ 3×l0 -2 mol dm -3 ) Cobalt distribution approaches that of the HDNNS-alone system. The HDNNS behavior in the presence of H 2 OX is explained in terms of the presence of a mixed oxime-sulfonate micelle whose concentration goes through a maximum as HDNNS concentration Is increased. The pH dependence of log D expected from the slope analysis (i.e. a slope of 2·0 for a log D vs pH plot) is masked by the presence of an H + /K + cation exchange between HDNNS and the aqueous KNO 3 ., supporting electrolyte.