Clay bricks modified by implementing of N- and/or C-TiO2: insight into self-cleaning properties toward fatty contaminant

Clay bricks containing different kinds of titanium dioxide (TiO2) photocatalysts were obtained. The samples have shown high photocatalytic activity during thin layers of oleic acid deposited on their surface decomposition. The self-cleaning effectiveness of the bricks was evaluated on the basis of the water contact angle measurements, or more precisely, wettability rate (WR) changes on the greasy surface layers. It appeared that despite the high-temperature clay firing process (950°C), the presence of quartz and aluminosilicates in clay have caused the inhibition of anatase–rutile transformation. The highest photocatalytic efficiency, determined on the basis of the WR measurements, was observed for TiO2/nitrogen (N) and TiO2/N, carbon (C)-loaded bricks. It should be noted that in the case of the bricks loaded with the TiO2/N,C photocatalyst, the carbon dopant present in the material was burnt out during the high-temperature kiln firing. The N content in latter samples show closely the same results (∼0.03 and ∼0.04 wt% of N for brick loaded with TiO2/N and TiO2/N,C, respectively). In the context of the photocatalytic activity of studied materials, the N presence was found to be one of the most important feature.