abstract
In this work, active TiO2 layers have been immobilized, on aluminium sheets, by a common and cheap deposition technique: jet spray. The layers' adhesion to the substrate was achieved by mixing the titania with a commercial thermally adherent polyester ink, which is industrially used for aluminium surface treatment (lacquering). The layers' photocatalytic performance was tested in the degradation of the organic dye Orange II in aqueous solutions, in a batch photoreactor under visible and solar light, and compared with TiO2 (anatase) suspensions. The layers' photocatalytic behaviour was evaluated taking into account different experimental variables, such as: (i) layer thickness: (ii) operation time: (iii) TiO2/polyester ink weight ratio and (iii) dye solution concentration and pH. A better performance was attained for layers having a 1:1 weight ratio of TiO2 and polyester ink and a thickness of 60 mu m (100 g/m(2)). These layers showed an interesting discolouration performance: an attenuation degree of 95% and discolouration rate, assuming an apparent first order reaction, reaching 2.2 x 10(-3) min(-1). These results were attained for the naturally resulting dye solution pH of approximate to 7, and for the lowest dye concentration of 20 mg/L. Therefore, neither alkalinisation or acidification of the dye solution nor the utilization of high-concentration solutions is recommended. Despite the slower kinetics, the dye degradation level achieved is similar to that obtained for TiO2 powder suspensions. Thus, these treated layered aluminium pieces can be considered as a serious alternative to photocatalytic suspensions of the oxide, with the advantage of excluding the removal of the photocatalyst at the end of the process. (C) 2011 Elsevier B.V. All rights reserved.
keywords
ZINC-OXIDE POWDER; PHOTOCATALYTIC DEGRADATION; IMMOBILIZED TIO2; ORGANIC POLLUTANTS; SUPPORTED TIO2; CERAMIC TILES; AZO-DYE; ZNO; LIGHT; WATER
subject category
Engineering
authors
Seabra, MP; Rego, E; Ribeiro, A; Labrincha, JA
our authors
João António Labrincha Baptista
Full professor
Maria Paula Seabra
Assistant Professoracknowledgements
Thanks to Dr. R.C. Pullar for comments and corrections to the English. The support of Extrusal should also be emphasized.