Characteristic of hydrous iron (III) oxides prepared by homogeneous precipitation of iron (III) sulphate with urea

Hydrous iron (III) oxides agglomerated into uniform porous spherical clusters with submicrometre size and high specific surface area were obtained. Homogeneous precipitation of iron (III) sulphate was carried out in boiling aqueous solution that contained excess of urea. The prepared precursor precipitates were heated for 2 h at various temperature (from 200 to 800 °C) to yield fine iron oxides powders. The structure evolution during heating of powders was investigated by X-ray diffraction (XRD). The morphology and microstructure characteristics were also obtained by means of scanning electron microscopy (SEM), (BET) and (BJH). In order to see the phase transition temperature thermogravimetric analysis/differential thermal analysis studies were performed. It was found that formation of different hydrous iron (III) oxides was affected by experimental conditions: aging time, mixing procedure, pH and temperature.