The Extraction Of Cobalt And Nickel Used Micromemulsion

Microemulsion consists of water, organic solvent, surfactant, occasionally including alcohol as cosurfactant. It is defined as a system formed by the dispersion of microdroplets of two immiscible liquids, stabilized by an interfacial membrane formed by surfactant and cosurfactant. They are thermodynamically stable, homogeneous and optically isotropic solutions. Microemulsion have been applied in many fields as its excellent properties. In this paper, Microemulsion were studied as separation media.The extraction of cobalt by Winsor II microemulsion system was studied. In the bis (2-ethylhexyl) sulfosuccinate sodium salt (AOT)/n-pentanol/n-heptane/NaCl system, AOT was used as a anionic surfactant to form microemulsion in n-heptane, n-pentanol was injected in the microemulsion as a cosurfactant. Co(II) was found to be extracted into the microemulsion phase due to ion pair formation such as Co2+(R-SO3-) Cl. The influence of different parameters such as the volume ratio of aqueous phase to microemulsion, surfactant concentration, pH of the feed solutions, cosurfactant concentration as well as temperature on the extraction yield (E%) were investigated. The results showed that it was possible to extract 95% of cobalt by the AOT Winsor II microemulsion.The selective extraction of cobalt from concentrated HC1 solutions by Winsor II microemulsion system using tertiary amine N235 as carrier was studied. In the hexadecyl trimethyl ammonium Chloride (CTAC)/n-pentanol/n-heptane/HCl/N235 system, CTAC was used as a cationic surfactant to form microemulsion in n-heptane, n-pentanol was injected in the microemulsion as a cosurfactant, and N235 was a typical extractant in the system. The microemulsion system without N235 showed poor extractability and stability. However, by adding N235, the extraction yield (E%) of cobalt can be almost 92%, that of nickel was always very low. The influence of different parameters such as surfactant concentration, extractant concentration, hydrochloric acid concentration of the feed solutions, cosurfactant concentration as well as temperature on the extraction yield (E%) were investigated. The results showed 92% of cobalt was extraced by microemulsion, while the extraction yield of nickel was very low which made the separation of cobalt and nickle possible.