Synergistic extraction of cobalt (II) and nickel (II) with a mixture of D2EHPA and 1-octanol

The solvent extraction of cobalt (II) and nickel (II) from a sulfate medium using di (2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in chloroform was studied in the absence and presence of the synergic agent 1-octanol according to the following parameters: pH, concentrations of the extractant and 1-octanol. The extraction reaction of cobalt (II) and nickel (II) with the synergistic mixture was determined using slope analysis in the presence of 1-octanol. The extraction curves show several species of complexes that depend on the concentration of 1-octanol. For very weak concentrations, the extracted complexes are ML2(org). For high concentrations, the extracted complexes are ML2(org)(1-octanol)(org) and ML2(org) (1-octanol)3(org) (M = Co, Ni). A mechanism and structure for the metal-extractant complex formed during the synergistic extraction were suggested.