Issue 12, 2013

Release of TiO2 from paints containing pigment-TiO2 or nano-TiO2 by weathering


The release of nanomaterials from products and applications that are used by industry and consumers has only been studied to a very limited extent. The amount and the characteristics of the released particles determine the potential environmental exposure. In this work we investigated the release of Ti from paints containing pigment-TiO2 and nano-TiO2. Panels covered with paint with and without nano-TiO2 were exposed to simulated weathering by sunlight and rain in climate chambers. The same paints were also studied in small-scale leaching tests to elucidate the influence of various parameters on the release such as composition of water, type of support and UV-light. Under all conditions we only observed a very low release close to background values, less than 1.5 μg l−1 in the climate chamber over 113 irrigations per drying cycle and between 0.5 and 14 μg l−1 in the leaching tests, with the highest concentrations observed after prolonged UV-exposure. The actual release of Ti over the 113 weathering cycles was only 0.007% of the total Ti, indicating that TiO2 was strongly bound in the paint. Extraction of UV-exposed and then milled paint resulted in about 100-times larger release of Ti from the nano-TiO2 containing paint whereas the paint with only pigment-TiO2 did not show this increase. This indicated that the release of Ti from the paints is an effect of the addition of nano-TiO2, either by photocatalytic degradation of the organic paint matrix (observed by electron microscopic imaging of the paint surface) or by direct release of nano-TiO2. Our work suggests that paints containing nano-TiO2 may release only very limited amounts of materials into the environment, at least over the time-scales investigated in this work.

Graphical abstract: Release of TiO2 from paints containing pigment-TiO2 or nano-TiO2 by weathering

Article information

Article type
26 Jun 2013
29 Aug 2013
First published
30 Aug 2013
This article is Open Access
Creative Commons BY license

Environ. Sci.: Processes Impacts, 2013,15, 2186-2193

Release of TiO2 from paints containing pigment-TiO2 or nano-TiO2 by weathering

A. Al-Kattan, A. Wichser, R. Vonbank, S. Brunner, A. Ulrich, S. Zuin and B. Nowack, Environ. Sci.: Processes Impacts, 2013, 15, 2186 DOI: 10.1039/C3EM00331K

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