EXTRACTION OF COBALT(II) BY CYANEX-301

The extraction equilibria of Co(II) from 1.0 M KCl medium by the comme rcial extractant Cyanex 301 dissolved in toluene has been studied. The effects of pH, extractant concentration and metal concentration on th e extraction behaviour have been examined. Experimental data have been treated graphically and numerically and can be explained by assuming the extraction of the dominant species CoL2. HL being bis(2,4,4-trimet hylpentyl)dithiophosphinic acid, the major component of Cyanex 301. Th e numerical treatment also indicated the extraction of a minor species of probable stoichiometry CoClL(HL)), but whereas the former species has been clearly identified, the latter species, probably due to the f act that its contribution to the extraction process is very little, ca n only be considered as an approximation as its stoichiometry is not d efined precisely by this numerical treatment. Conditional equilibrium constants of the extraction process are also given.