Catalytic ozonation by Si-doped α-Fe2O3 for the removal of nitrobenzene in aqueous solution

Abstract

Si-doped α-Fe2O3 by controlling the atom ratio of Si/Fe was synthesized for catalytic ozonation of nitrobenzene in aqueous solution. Basing on the results of batch oxidation experiments, the catalysts in Si/Fe ratios of 0.1, 0.5, 1.0, and 2.0 showed various activities for ozone decomposition into hydroxyl radical (OH), which obviously enhanced the removal efficiency of nitrobenzene in aqueous solution compared with sole ozonation. The best Si/Fe ratio was 0.5 in present study. The dose of the catalyst, solution pH and reaction temperature can significantly affect the removal efficiency of nitrobenzene. Moreover, the catalyst was composed of Si–Fe binary oxides and α-Fe2O3. With the increase of Si/Fe ratio, the surface relative content of Si-Fe binary oxides increases and the relative content of α-Fe2O3 decreases, which promotes the ozone adsorption-desorption on the surface of the catalyst. The generation of hydroxyl radical in catalytic ozonation was dependent on the synergy of ozone adsorption-desorption by Si–Fe binary oxides and ozone decomposition by α-Fe2O3 on the surface of the catalyst.