MUNICH, Germany - Researchers at the Fraunhofer Institute are studying how coatings with photocatalytic characteristics behave during long-term tests.
In the 70s, the solution to air pollution in the Ruhr area of Germany was filter systems for the smokestacks. Today, people in urban areas are suffering from high levels of pollution that are caused by, among other things, automotive traffic, particularly nitrogen oxides (NOx). The European Union has continued to tighten pollutant limit values, and in many communities they are being exceeded. Michael Hüben of the Fraunhofer Institute for Molecular Biology and Applied Ecology IME in Schmallenberg, Germany, knows that “on stretches with heavy traffic there is a particular need for action.” During the next two years, Fraunhofer researchers will study the effectiveness of photocatalytic removal of NOx using coated building test panels. They will study how photocatalytic surfaces contribute to the removal of NOx and how the coatings prove themselves during long-term operation.
”Coatings that are photocatalytically active can help to reduce nitrogen oxides,“ explains Dr. Michael Hüben. “There are already a number of products available for the photocatalytic coating of surfaces, but the measurement method standardized according to ISO 22197-1 cannot be applied to all problems. At the IME, we have now developed a special measurement cell, which we are using in our project.” At the A 4 interstate at Bergisch Gladbach, researchers will place weathering noise barrier samples coated with reactive material. Prepared test samples will be measured at predetermined intervals in the measuring cell. Hüben explains, “The surface of the test sample must be photocatalytically active, meaning it removes NOx when exposed to light.” The surfaces contain titanium dioxide catalysts, a material that is affordable and available in large quantities. Then, exposed to daylight, titanium dioxide catalyzes the nitrogen oxide into nitrate. “The photocatalytic activities of the samples are determined using a flow-through process,” said Hüben.
During the next two years, scientists will monitor how much nitrous oxide is being removed, determining the long-term effects of the coatings.