THE INFLUENCE OF CONCENTRATION ON THE OXIDATION OF FERROUS HYDROXIDE IN BASIC SULFATED MEDIUM - PARTICLE-SIZE ANALYSIS OF GOETHITE AND DELTA-FEOOH

The evolution of the oxidation end product of ferrous hydroxide in the basic sulphated aqueous medium at R = {[FeSO4]/[NaOH]}initial = 0.2 is investigated at various initial concentrations. The end product is essentially well crystallized goethite at relatively high initial concentrations of the reacting chemicals. The crystal structure of goethite is modified as the initial concentration is decreased; at a critical low concentration, the orthorhombic structure is no longer observed. Inactive alpha' -FeOOH, which has a similar X-ray diffraction pattern to delta-FeOOH, is obtained. All these compounds are crystallographically related.