Ilmenite (FeTiO3) as low cost catalyst for advanced oxidation processes

The role of ilmenite mineral (FeTiO3) in different AOPs processes (photocatalysis, catalytic wet peroxide oxidation (CWPO) and CWPO-Photoassisted processes) was evaluated using phenol as target compound. Our results endorse its role as solar photoassisted catalyst for H2O2 decomposing into HO radicals. In photocatalytic process, despite both the higher TiO2 content and a band-gap lower than titanium dioxide P25, ilmenite showed a scarce activity. On the other hand, ilmenite results a feasible catalyst in CWPO process, although it requires high induction periods, around 200 min. This drawback can be overcome by combining CWPO with solar light irradiation, since the latest provokes a faster Fe(III) reduction into Fe(II) that decomposes H2O2 into HO radicals. Working at pH0 = 3, T0 = 25 °C, an almost complete phenol (100 mg L−1) mineralization (XTOC > 95%) was obtained after 480 min reaction time using the stoichiometric H2O2 dose (500 mg L−1), ilmenite (450 mg L−1) and 550 W m−2. Besides, Ilmenite showed a high stability after five consecutives CWPO-Photoassisted runs, where TOC reduction, above 90%, was maintained working at the previous experimental conditions. The total Fe leaching from ilmenite was around 2% of the initial load.

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