Comparative Studies on The Extraction of Cobalt from Chloride Medium using Different ExtractantsS. A. El-reefya, A. S. Shalabib, N. H. M. Kamelc, Ahmed T. El-senbawyc*
a Analytical Chemistry Dep., Hot Laboratories Center, AEA, Egypt b Chemistry Dep., Faculty of Science, Benha Univ. c Radiation Protection Department, Nuclear Research Center, AE
The extraction of cobalt from chloride medium using two organophorous extractants: bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) and di-(2-ethyl-hexyl) phosphoric acid (D2EHPA) was studied. The important parameters governing the extraction of cobalt have been studied. These parameters are the aqueous phase pH, the extractant concentration and the stripping phase type and concentration. A comparison between Cyanex 272 and D2EHPA has been established. The distribution of cobalt (II) 100 ppm between aqueous chloride medium and kerosene solutions of Cyanex 242 or D2EHPA has been studied. The extraction equilibrium is influenced by the extractant concentration and the equilibrium pH value of the aqueous medium. The distribution data have been graphically analysed. The results show that the species extracted into the organic phase have the composition of CoA2.3HA for cyanex 272.CoA2.HA was also observed. As for D2EHPA, CoA2 was observed and the polymerized tetrahedral complex. The extraction constant with Cyanex 272 was higher than D2EHPA. The stripping was studied for both extractants using H2SO4 and HCl. Cobalt (II) of the extracted Co (II) was stripped from Cyanex 272 at lower acid concentration than D2EHPA.
Cyanex 272/D2EHPA/Cobalt extraction/chloride medium