In the course of the joint project "Photocatalytic paving stones Niestetal", funded by the Hessen Agentur, an acute problem of our time, the pollution of the air with nitrogen oxides, is to be tackled. These regularly exceed the valid limit values and are a burden on health. Since the municipalities are responsible for compliance with the limit values, they derive particular benefit from this project. Photocatalytic building material surfaces, which are able to break down the pollutants with the help of the UV component of sunlight and thus convert them into harmless end products, can contribute to reducing the concentration of nitrogen oxides. This happens particularly effectively close to the point of origin, i.e. on roads. Therefore, a large area in the industrial area of Niestetal, which has already been equipped with photocatalytic paving stones, is to be monitored using measurement technology. The aim is to scientifically confirm the effectiveness of the pollutant decomposition not only in the laboratory but also in practice. This should help later users to make decisions on the basis of well-founded data and thus to comply with the limit values. Various investigations of the degradation of nitrogen oxides are carried out in the laboratory, both according to ISO 22197-1 and according to modified methods that allow the investigation of entire bricks non-destructively in special reactors. Degradation tests, which take place on site, and on-site analysis of the degradation products allow conclusions to be drawn about effectiveness. Tests on durability against freeze and thaw cycles, de-icing salts and mechanical stress are carried out in addition. The measured values obtained are entered into a specially developed simulation for the degradation of nitrogen oxides, which allows conclusions and predictions to be drawn about the effectiveness of the photocatalytic pavers under different conditions. This, in turn, can be used to benefit the construction of new photocatalytic building material surfaces that aim to reduce nitrogen oxide concentrations. If only low efficiencies are predicted at the project site, construction elsewhere may be more worthwhile and can thus relieve the financial burden on municipalities. At the same time, this strengthens the research and business location Hessen by involving partners from the entire process chain of production, application and investigation in the field of photocatalysis.

This project will continue to be supported by Kai Amrhein and Sameena Kamaruddin (who moved from the University of Kassel to the TU Berlin in November 2012).

Funding line 3: LOEWE-KMU joint project

HA project no.: 303/11-48