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Synthesis and characterization of co-modified titania solids used in the photocatalytic degrdation of phenol

Abstract:

Phenol was used as probe molecule for the photo-activity evaluation of reduced and iron doped anatase (TiO2). The iron catalyst was prepared by wet impregnation of anatase with Fe(NO3)3 and a subsequent calcination at 500°C. In other hand, reduced TiO2 was obtained by HNO3 pre-treatment and reduction under hydrogen flow at 500°C. Co-modified catalysts were synthetized by three procedures: 1) mechanical mixture of solids, 2) impregnation of the iron salt to the reduced TiO2 and, 3) reducing the iron doped anatase. The photocatalysts were characterized by FT-IR, Mössbauer spectroscopy, XRD and UV-Vis absorption of aqueous dispersion. It was found that iron do not change crystalline structure of TiO2, although the UV-Vis absorption showed a little batochromic shift. Phenol degradation was 1.8 times higher than pure anatase. The reductive treatment, provoke certain chemical surface changes beneficial to the TiO2 activity, making TiO2 1.6 times more active. The co-modified solid synthesized by mechanical mixture reached an activity three-fold higher than the original semiconductor, being this co-modification method the most advantageous, suggesting also an electron transfer mechanism between semiconductors.