Ecoactive porcelain gres tiles: a new challenge for environmental sustainability

At the beginning of the industrial productions, porcelain gres tiles were considered as just a technical material characterized by strong resistance to both abrasion and acid attack, almost lack of porosity, but aesthetically not very beautiful. Today thanks to new industrial production methods, both properties and beauty of these materials completely fit the market requests. In particular, the possibility to prepare slabs of large sizes [1] is the new frontier of building materials. Slabs are generally manufactured under high pressure by dry-pressing fine processed ceramic raw materials with large proportions of quartz, feldspar, and other fluxes. Afterwards, the body of these materials is fired at very high temperatures (1200–1300°C) in kilns. The final material is thus characterized by lack of porosity, complete water-proofing, durability, hardness, wear resistance properties, and a complete frost resistance. Beside these noteworthy features, new surface properties have been introduced in the last generation of these materials. The present work deals with the characterization and photocatalytic activity of commercially available tiles, named ActiveTM, prepared with a surface application of a commercial photoactive micro-sized TiO2 [2] stabilized by a sort of inorganic glue (Si-based) heated at 680°C [3]. Industrially prepared tiles were fully characterized (HR-SEM in Fig.1) and the photocatalytic properties of these materials have been verified through depollution and discoloration tests. In details, the pollution degradation of both NOx [4] and VOCs (acetone and acetaldehyde) in the gas phase and two different organic dyes directly put at the tiles surfaces (Rhodamine B and Metanil yellow) have been investigated. Dyes degradation was monitored by Vis-spectrometer equipped with an integrated sphere (OceanOptics, USB4000-VIS-NIR-ES). The color analysis was performed using the CIEXYZ (Fig.2) and CIELAB models. Moreover ISO 27448-1 self-cleaning test performed by means of contact angle measurement were also shown [5].