Effect of temperature and pH on the phase formation in system FeSO 4-H 2O-NaOH-H 2O 2

It was explored solid phase formation processes during oxidation of FeSO 4 solutions and (or) Fe(OH) 2 suspensions with hydrogen peroxide under quasistationary base condition (initial NaOH additions until fixed pH value for every run). On pH-temperature diagram experimentally described fields of formation of “ferrihydrite”, Fe 3O 4, α-, γ- and δ-FeOOH. Phase and particle size dependence on pH and temperature are discussed.