Conditions Favorable for the Formation of γ-FeOOH by Aerial Oxidation in an Acidic Suspension of Iron Metal Powder

Abstract

Abstract Dilute solutions of ferrous sulfate, sulfuric acid, hydrochloric acid, nitric acid and acetic acid in which iron powders are dispersed have been oxidized at below 80°C by blowing air into them. The resulting precipitates have been examined by means of X-ray diffraction, chemical analysis and optical and electron microscopy. When the iron powder is well dispersed, γ-FeOOH is formed with or without α-FeOOH, α-Fe2O3, or Fe3O4. The mode of formation depends on such factors as particle size, amount of iron powder, kind of anion present and temperature. Particle size greatly influences the formation of γ-FeOOH in the sulfate system, but not in the other systems.