Photocatalytic activity for exposed building materials

Photocatalysis is a very promising method to face most of the problems connected with the increasing environmental pollution. Titanium dioxide in its anatase crystallographic phase is the most investigated photocatalytic material and results to be perfectly compatible with silicate body mixes. The possibility to obtain photocatalytic heavy clays materials, to be used for outdoor applications, such as roof tiles, floor tile and outdoor covering tiles, could represent an important goal. In the present work, several titania powders and a titania nanosuspension were added to a body mix used for heavy clay products and the influence of their morphological characteristics on the photoactivity of the fired materials was studied. The titania powders, characterised by the aid of SEM, X-ray diffraction analysis and surface area measurements, BET, presented particles with different aspect ratio and size, ranging from micrometric to nanoparticles. Besides, the nanosuspension was characterised by FEG, TEM, DLS and XRD on the dried suspension. The photocatalytic activity was assessed in aqueous mixtures, by analysing the degradation of an organic dye with a spectrophotometer. The results were explained taking into account the anatase to rutile phase transformation and its possible reaction, during sintering, with the starting raw materials. (c) 2008 Elsevier Ltd. All rights reserved.