Tungsten-Doped TiO₂ vs Pure TiO₂ Photocatalysts:  Effects on Photobleaching Kinetics and\nMechanism

Abstract

Sol gel prepared tungsten (VI) doped TiO₂ powders were evaluated as photocatalysts for crystal violet (CV)\nbleaching under UV irradiation, in the presence of oxygen. The incorporation of the hexavalent cation affects\nboth surface and bulk properties. The optimum activity observed results from the competition between higher\nsurface areas and lower specific activities per adsorption site. At pH 4.0, doped particles share a common\nphotodegradation mechanism, where the relative contribution of the aromatic structure rupture over the loss\nof terminal methyl groups (N-demethylation) is more relevant than in the case of non-doped titania. This\nbehavior can be minimized shifting the pH into basic condition.