SOLVENT-EXTRACTION OF COBALT AND SODIUM W ITH VERSATIC-ACID-10

Extraction behavior of cobalt and sodium (abbreviated to Co(II) and Na , respectively) with Versatic Acid 10 (abbreviated to VA10 and its che mical formula is abbreviated to RH) was investigated by experimentally obtaining phase equilibria in the VA10-Co(NO3)(2-)NaOH-H2O system and in the VA10-Co(NO3)(2-)H2O system at 298 K. The results obtained are as follows. The distribution ratio of Co(II) is very small in the case of VA10-Co(NO3)(2-)H2O system. In the case of the VA10-Co(NO3)(2-)NaO H-H2O system, on the other hand, Co(II) is preferentially extracted to Na in the narrow pH region. After the extraction of Co(II) is complet ed, Na starts to be extracted as pH value becomes higher. Extracted sp ecies of Na can be identified as RNa and that of Co(II) is inferred to be either in the form of monomer or dimer. The extractant, RH is hard ly dissolved in the aqueous phase in the pH region in which the extrac tion of Co(II) is dominant. On the contrary, in the pH region in which the extraction of Na becomes dominant, the RH concentration in the aq ueous phase rapidly increases. Based on the results thus obtained, the solubility surface and tie lines between organic and aqueous phases w ere constructed on a composition tetrahedron of the RH-Co(ll)-Na-H2O s implified system. It is shown that an overview of extraction behavior of Co(II) and Na with RH can synthetically be understood from this com position tetrahedron.