[Spectral analysis of FeOOH prepared through hydrolysis and neutralization of ferric solutions under different conditions].

In the present work, the iron oxyhydroxides were prepared by hydrolysis and neutralization of ferric ion from FeCl3, Fe(NO3)3 and Fe2 (SO4)3 salts, under the conditions of various pH values and aging for about 6 days at 60 degrees C. These iron minerals were identified and characterized using X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). In addition, particle size distributions of FeOOH suspension were also determined by LS-230 model laser grainsize analyzer. Results showed that ferrihydrite formed in the ferric solutions containing Cl-, NO3- and SO4(2-) at pH values of 8 and 10. It was testified that the presence of Cl- was favorable for the formation of akaganéite. Meanwhile, the poor crystalline goethite phase was observed to be formed in FeCl3 or Fe(NO3)3 solution, but not be formed in Fe2 (SO4)3 solution at pH 12. It indicated that the presence of SO4(2-) obviously inhibited the formation of goethite. However, the goethite phase formed in Fe2 (SO4)3 solution with addition of ferrous ion, indicating that ferrous ion could promote the formation of goethite in SO4(2-) -rich solution. In addition, it was usually easy for the crystalline goethite to be transformed from the above generated ferrihydrite precipitates by aging at 60 degrees C. Furthermore, the phase of akaganéite also was obtained in the Cl(-) -rich acid (pH < or = 5) solution by aging at 60 degrees C. In conclusion, the prepared FeOOH samples show some differences in their properties such as the phase, surface properties, morphology structures and particle size.