Photocatalytic Coatings - Promising Way to Improve a Quality of Urban Building Surfaces

Abstract With the increasing air pollutants particularly in the cities the deteriorating conditions of the buildings accelerate. One of the non-invasive and cheap promising ways how to prevent the buildings against the aged processes caused by biological pollutants or smog exhalation is the innovation of suitable photocatalytic coatings. This work focuses on the characterization of prepared photocatalytic nanocomposite TiO2-SiO2 system to be applied on the building objects in order to improve a quality of their surfaces. The structure and the texture characterization of prepared nanocomposite were determined by electron microscopy (SEM, TEM + EDS). The photocatalytic activity of the composite was determined considering the self-cleaning ability and the antibacterial activity. For self-cleaning characterization the methylene blue degradation was measured. These self-cleaning properties were tested on the various types of supports, which are commonly used in the building facades. To estimate antibacterial and biocidal activity the Gram-negative bacterium Escherichia coli and the gram-positive bacteria Staphylococcus aureus were used. Both methods were done according to standard ISO tests. Next to the laboratory testing the application of the composite under the real condition was implemented. There were treated parts of the concrete outside wall with the composite and after more than one year the colour changed analysis of the wall surface was characterized.