Abstract
The extraction of cobalt was studied, employing benzene as a diluent to weakly solvate the extractant. In benzene, the extractant needs to surround itself with stabilizing molecules. A simple extraction scheme is presented which assumes that the extraction of cobalt occurs via reaction with the monochloride acid-complex of the extractant, i.e., via the replacement of water and acid in the salt hydration sphere by cobalt ion. The data obtained at acid concentrations of 2-7 mol/l and loading ratios up to maximum were analysed according to the scheme. Three species of the extract were considered. The fraction of 1:1 complex, R3R''NCL·COCL2, was very close to 1 at very low loading. The fraction of monomeric 2:1 complex, (R3R''NCL)2·COCL2, was less than 0.02 over the whole range observed, while the dimeric species, {R3R''NCL·COCL2}2, increased with loading ratio of the extractant. Self-association of the extract entity seems to be needed to stabilize itself in the relatively inert diluent.
