Investigation of co-precipitation of Fe(II) and Ni(II) hydroxides

The process of co-precipitation of ferrous and nickel hydroxides is considered. The results of thermodynamic calculation showed that the pH of nickel and ferrous hydroxides precipitation is slightly different. However, the rate of [NiOH]+ and [FeOH]+ cations formation in a solution is the same, which determines the possibility of co-precipitation of hydroxides. Using potentiometric titration, cyclic voltammetry (CVA), successive stages of polyhydroxide complexes formation were established. It has been shown that the co-precipitation process occurs in several stages. The first stage is the formation of mono- or binuclear polyhydroxocomplexes. With increasing pH, intermediates are formed that isomorphic to the ferrite structure.