abstract
The photocatalytic behaviour of several commercial titania powders (in aqueous suspension) was evaluated through the decolouration of Orange II aqueous solutions. The performance was correlated with relevant characteristics of the powders, such as crystalline phases, particle size and morphology. The highest efficiency TiO(2) powders were those deposited by jet spray on ceramic tiles, and then fired to stabilise the layers. The obtained products were characterised and tested for the photocatalytic degradation of the Orange II dye, in a batch photoreactor under visible light irradiation. Values were compared with those achieved by TiO(2) suspensions. The following experimental variables were tested: (i) the amount of deposited titania; (ii) powder manufacturer/source; (iii) firing temperature of deposited layers; and (iv) operation time. Optimal processed layers showed an interesting decolouration performance, as denoted by an attenuation degree of 96% and decolouration rate, assuming an apparent first order reaction, reaching 5.9 x 10(-3) min(-1). Thus, these layered ceramic tiles can be considered as an alternative to photocatalytic suspensions of the oxide, with the advantage of avoiding the need to remove any photocatalyst particles at the end of the process. Besides the good photocatalytic performance, the optimized ceramic tiles have an aesthetically pleasing surface, a good adhesion to the substrate, and are easy to clean, thus fulfilling industrial/commercial requirements. (C) 2011 Elsevier B.V. All rights reserved.
keywords
NANOSTRUCTURED THIN-FILMS; MODIFIED SOL-GEL; PHOTOCATALYTIC DEGRADATION; IMMOBILIZED TIO2; STAINLESS-STEEL; SUPPORTED TIO2; TITANIA; DYES; COATINGS; DECOMPOSITION
subject category
Engineering
authors
Seabra, MP; Pires, RR; Labrincha, JA
our authors
João António Labrincha Baptista
Full professor