Photocatalytic Degradation Mechanism of Oxytetracyclines Using Fe2O3–TiO2 Nanopowders

Photocatalytic degradation performance of oxytetracycline (OTC) was investigated in aqueous solution using Fe2O3–TiO2 nanopowders under UV and visible light, respectively. Compare with pure TiO2, the Fe2O3–TiO2 nanopowder had improved photocatalytic activity under visible light, while had a bit decrease under UV light. Photoluminescence (PL) spectrum measurement, ·OH radical test and trapping experiments were carried out to investigate the photocatalytic mechanism. Under UV light, photogenerated electrons–holes can transfer from TiO2 to the conduction band and valence band of Fe2O3, respectively, and further participated in the degradation of OTC, thus both O2·− and holes are the main active species in this case. Under visible light, Fe2O3 was activated and yield charge carriers, then the photogenerated electrons immigrated to the trapping site of TiO2, the photogenerated holes accumulate in the valence band (VB) of Fe2O3 was the major active species reacted with OTC.