Adsorption of ferrocyanide and ferricyanide ions at the aluminum oxide‐solution interface

The adsorption of complex ions (ferrocyanide (Fe(CN)4‐ 6) and ferricyanide (Fe(CN)3‐ 6) by aluminum oxide has been investigated at three initial concentrations of complex ions with varying both concentration of background electrolyte and solution pH. In this study, the triple‐layer model has been sucessfully used to simulate ferrocyanide and ferricyanide adsorption on aluminum oxide surface. Evidence for direct coordination of complex ion to the aluminum oxide has been obtained by IR investigation. The results indicate that ferrocyanide is in association with aluminum oxide surface through the outer‐sphere complexation. The ferricyanide, at neutral and alkaline condition (pH > 5), is favor to the outer‐sphere complexation with that surface, but inner‐sphere reaction plays a major role in this interfacial interation at acidic conditions (pH < 5).