PRECIPITATION OF IRON-OXIDES FROM AMMONIA-AMMONIUM SULFATE-SOLUTIONS

The precipitation studies for Fe(II) in the NH3-NH4)(2)SO-O-2 system were carried out using a factorial design of experiments. The three variables chosen were: temperature, [NH3 + NH4+] and Fe(II) concentrations. Regression equations were determined for 10, 20, 30 and 45 min reaction times. It was found that only linear co-efficients for the parameters chosen were significant. At 30 and 45 min retention times, precipitation of iron showed negative dependence only for Fe(II) concentration, The precipitates obtained under various conditions were characterized using XRD, TG and TEM techniques. Depending on the experimental conditions, the nature of iron precipitate varied from amorphous to crystalline hematite, goethite or magnetite. The conditions have been defined for obtaining crystalline hematite or magnetite.