Specific adsorption of barbituric acid on ferric (III) and nickel (II) oxides

The dependence of NiO and Fe2O3 ζ-potential was investigated in the barbituric acid solutions (10−4 mol/l) as a function of pH by microelectrophoresis method. Shifting of pHIEP (the isoelectric point or IER) towards the acid zone for NiO and Fe2O3 in the solutions of barbituric acid (BA) in comparison with HCl shows the presence of the specific adsorption of the anion forms of BA. The complexation process of Ni(II) and Fe(III) ions with BA in the solution and on the surface of their oxides was examined by methods of conductometry and spectrophotometry. It was determined that nickel (II) and ferric (III) ions form complexes with BA both in solution and on the surface of their oxides.