Evaluating the effectiveness of photocatalysts based on titanium dioxide in the degradation of the dye Ponceau 4R

Abstract

The performance of different titanium dioxide (TiO2) catalysts and a composite based on the association between TiO2 P25 and Zinc Phthalocyanine (TiO2/ZnPc 1.6%) was evaluated in the photocatalytic degradation of the dye Ponceau 4R (C.I. 16255). The results show that the composite presents a better performance than the other, reaching about 50% mineralization of the dye in 120 min of reaction, around three times higher than that observed under the action of pure TiO2 P25, although this catalyst presents a quantum yield of hydroxyl radical generation about three times higher than that estimated for the composite. This result seems to be a consequence of the synergism between the electronically excited ZnPc aggregates and the TiO2 surface. A parallel study, based on methods from quantum mechanics also suggested the most feasible routes for the photodegradation of the dye in the absence of the catalyst.