Photocatalytic activity of titanium dioxide coatings: Influence of the firing temperature of the chemical gel |
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| Authors: | M Fassier CS Peyratout DS Smith C Ducroquetz T Voland |
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| Affiliation: | 1. Graduate Institution of Engineering Technology-Doctoral, National Taipei University of Technology, Taipei, Taiwan;2. Chemical Engineering Division, Institute of Nuclear Energy Research, Taoyuan, Taiwan;3. Institute of Mineral Resources Engineering, National Taipei University of Technology, Taipei, Taiwan;4. Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei, Taiwan;1. Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Na Slovance 2, 182 21, Prague 8, Czech Republic;2. Institute for Problems of Materials Science, Academy of Sciences of Ukraine, 3 Krzhyzhanovsky St., 03142 Kiev, Ukraine;3. Regional Centre of Advanced Technologies and Materials, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, Faculty of Science, Palacky University, 17, Listopadu 12, 77146 Olomouc, Czech Republic;4. Regional Centre of Advanced Technologies and Materials, Department of Experimental Physics, Faculty of Science, Palacky University, 17, Listopadu 12, 77146 Olomouc, Czech Republic;1. Laboratory of Applied Chemistry and Environment, Department of Chemistry, Faculty of Science, University Ibn Zohr, 80000 Agadir, Morocco;2. Laboratory of Materials and Environment, Department of Chemistry, Faculty of Science, University Ibn Zohr, 80000 Agadir, Morocco |
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| Abstract: | Heterogeneous photocatalysis can be exploited for the decomposition of micro-organisms which have developed on the surfaces of building materials. In this work, the efficiency of titanium dioxide coatings on fired clay products is examined. The sol–gel method is used to synthesize a fine TiO2 powder with a specific surface area of 180 m2 g?1. Thermal treatment of the chemical gel at 340 °C leads to crystallisation in the anatase phase and with further temperature increase, crystallite growth. For thermal treatments in the range 580–800 °C, there is a progressive transition from anatase to rutile. However, despite a decrease in specific surface area of the powder attributed to aggregation/agglomeration, the coherent domain size deduced from X-ray diffraction measurements remains almost constant at 23 nm. Once the transition is completed, increase of thermal treatment temperature above 800 °C leads to further crystallite growth in the rutile phase. The thermally treated titania powders were then sprayed onto fired clay substrates and the photocatalytic activity was assessed by the aptitude of the coating to degrade methylene blue when exposed to ultraviolet light. These tests revealed that the crystallite size is the important controlling factor for photocatalytic activity rather than the powder specific surface area or the anatase/rutile polymorph ratio. |
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