Dissolution of Magnetite in Orthophosphoric Acid: Study and Modeling

The influence of a number of parameters (temperature, pH, the concentrations of orthophosphoric acid and ions in the electrolyte) on the kinetic laws of the dissolution of magnetite Fe3O4 in acidic solutions is studied. The nature of the potential-determining reaction in magnetite electrode–electrolyte solution systems is determined. The experimental results prove that the dissolution of oxide phases can be stimulated by iron, which affects the potential at the iron oxide/electrolyte solution interface. The reaction orders of the magnetite dissolution processes with respect to hydrogen cations, Fe(II) and Fe(III) ions, dihydrophosphate anions, and H3PO4 are determined.