Photocatalytic decolorization of an azo dye employing TiO2 anatase/brookite compounds obtained by hydrothermal methods

Abstract

Titanium dioxide is a widely studied material with well-known applications for anatase and rutile phases. Moreover, brookite, another polymorph, which is more difficult to obtain, has caught scientific community interest, especially for photocatalysis applications. Among many methodologies for TiO 2 synthesis, the hydrothermal method stands out, with the possibility of controlling different parameters that lead to a specific phase composition, allowing selective polymorphic obtainment. This method was used to synthesize TiO 2 with different anatase/brookite ratios, by the use of different synthesis conditions as pH of the suspension, sodium salt concentration, and temperature, resulting in anatase-brookite photocatalyst with brookite composition ranging from 0 to 35%. The materials were characterized by X-ray diffraction, infrared spectroscopy, Raman spectroscopy, particle size measurement, and scanning electron microscopy. Photocatalysts with the highest brookite amount showed the best photocatalytic results for Remazol golden yellow (RNL) dye decolorization. Moreover, the short-range disorder also played an important role in photocatalytic behavior.

Understanding the Photocatalytic Activity of Sodium Hexatitanate Nanoparticles for Pollutants Degradation: A Spectroscopic Insight

“…It is important to mention that such a comprehensive study has not yet been performed on Na 2 Ti 6 O 13 . A previous study by our research group 19 indicated that some synthesis conditions used to prepare TiO 2 , for instance, by a microwave-assisted hydrothermal method, favor the formation of anatase and brookite phases. At the same time, other samples were amorphous after synthesis, especially those synthesized with sodium acetate trihydrate or low thermal treatment temperature.…”