Synthesis of mixed oxide Ti/Fe2O3 as solar light-induced photocatalyst for heterogeneous photo-Fenton like process

Abstract

Ti/Fe2O3 (Ti/Fe mass ratio ∼ 0.22) magnetic catalysts were prepared by a modified Pechini method and evaluated for heterogeneous photo-Fenton-like process for degradation of Reactive Black 5 (RB5) textile dye under artificial solar light irradiation. Catalysts were calcined at temperatures of 500–700 °C, and were characterized by TGA, XRD, N2 adsorption/desorption, FTIR, SEM, EDX and UV/Vis DRS analyses. The photo-Fenton experiments were conducted at pH 2.5, H2O2 initial concentration of 12 mmol L−1 and 0.40 g L−1 of catalyst. Results showed that catalyst calcined at 500 °C (TiFeO-500) achieved 100 % degradation of textile dye, the highest photoactivity, when compared with the materials calcined at either 600 or 700 °C and to the pure oxides α−Fe2O3 or TiO2, under the same conditions. Kinetic data related to RB5 dye degradation with TiFeO-500 catalyst was well fitted to the pseudo-first order model with initial reaction rate of 0.28 mg L−1 min−1. The high catalytic activity of this material was favored by its multiple bandgap from UV to visible range, as well as to its nanometric particle size and low agglomeration. Photoreduction efficiency of the Fe3+ to Fe2+ was favored by the synergy with Ti4+ and possible amorphous Fe and Ti oxysulfate species in the photo-Fenton like process for the production of hydroxyl radical (•OH) and dye degradation.