Catalytic ozonation of trace nitrobenzene in water with synthetic goethite

This paper aims to reveal the effectiveness and the mechanism of catalytic ozonation with synthetic goethite (FeOOH) for the degradation of recalcitrant pollutants that cannot form surface complexes with surface metal sites of the catalyst in water. Nitrobenzene (NB) was used as the target pollutant. Results show that catalytic ozonation with FeOOH can substantially enhance NB degradation compared with ozonation alone. Scavenging test and quantification of the oxidation intermediates of NB reveal that the improved NB degradation is due to the enhanced hydroxyl radical generation. The activity of the FeOOH in water is related to its highly hydroxylated surfaces. The surface hydroxyl groups on the FeOOH in water are active sites in the catalytic ozonation. Moreover, the properties of the surface hydroxyl groups such as their quantity and charge states seem to have close relationship with the activity of the FeOOH in the catalytic ozonation of NB. We finally proposed a pathway that the uncharged surface hydroxyl groups on the FeOOH in water can induce aqueous ozone decomposition to generate hydroxyl radicals.