Influence of 1-hydroxyethelydenediphosphonic acid on the kinetics of magnetite dissolution

The influence of pH value, solution composition, and complexone concentration of (1-hydroxyetheledenediphophonic acid (HL)) on magnetite (Fe3O4) dissolution is studied. A peak in the rate of oxide dissolution is shown to occur at pH 1.5, with its amplitude increasing with the acid concentration. It is demonstrated that the effect of a complexone can be explained based on the structure of the electrical double layer at the oxide-electrolyte interface and on the adsorption characteristics of the H4L- complexone ions and protonated Fe(II) anionic complexes. Various mechanisms of iron oxide dissolution in the presence of HL are discussed.