Effect of immobilized titanium dioxide particle size on photo catalytic oxidation of bromo cresol purple

Pollution of sewage water with organic matter and aromatic compounds is a complex problem that is constantly in need of more efficient systems for its treatment. The objective of this works is to evaluate the effect of TiO₂ particle size in the photo catalytic oxidation of bromo cresol purple, used as a model of organic polluter. TiO₂ was immobilized on a borosilicate substrate through the coating by immersion technic and was characterized by atomic force microscopy to evaluate the morphology of the obtained surface. The anatase crystalline structure of TiO₂ was confirmed by X ray diffraction and its particle size was evaluated by dynamic light scattering). The effects of 25- and 300- nm TiO₂ particles on the degradation of bromo cresol purple at 5, 10, 20 and 30 ppm concentrations were evaluated. Kinetics of the bromo cresol purple degradation reaction was pseudo first order, consistent with the Langmuir model for low concentrations of this dye. The photodegradation in 25-nm TiO₂ particles was more efficient than in 300 nm, due to the greater number of grains formed on the surface, thus promoting a great number of available active sites. (author)