Photocatalytic Degradation of Wood Coated with a Combination of Rutile TiO₂ Nanostructures and Low-Surface Free-Energy Materials

Abstract

To test the hypothesis that wood coated with rutile TiO₂ nanostructures can undergo degradation because of the photocatalytic activity of TiO₂, three sets of wood specimens were aged at an accelerated rate. These three sets consisted ofblank wood (BW), HDTMOS/MTMOS-coated wood (WHM), and TiO₂/HDTMOS/MTMOS-coated wood (WTHM). After exposure to 155-h UV irradiation, the wettability of WTHM changed from hydrophobic to hydrophilic. This indicated that the initial low-surface free-energy materials underwent degradation because of the photocatalytic activity of TiO₂. After exposure to 960 h of UV light irradiation and water spray, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) of WTHM showed that rutile TiO₂ nanostructures had partially peeled off the wood surface. This suggested that the adjacent wood surface also suffered degradation because of the photocatalytic activity of TiO₂. Although the rutile TiO₂ coating noticeably enhanced the color stability during UV light aging, it made a relatively small contribution to the color stability of the wood during UV light and water spray weathering process. This study suggests that to derive the greatest benefit from modification of wood surfaces with rutile TiO₂ nanostructures for weathering resistance, it is necessary to take measures to inhibit the photocatalytic activity of TiO₂ or to fix the TiO₂ coating on the wood surface.

Citation

Zheng, Rongbo; Tshabalala, Mandla A.; Li, Qingyu; Wang, Hongyan. 2016. Photocatalytic degradation of wood coated with a combination of rutile TiO₂ nanostructures and low-surface free-energy materials. BioResources. 11(1): 2393-2402. https://doi.org/10.15376/biores.l1.1.2393-2402