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Hyun Ook Seo, Chae Won Sim, Kwang-Dae Kim, Young Dok Kim, Dong Chan Lim
Chemical Engineering Journal, Volume 183, February 2012
Abstract
TiO2 films supported by porous SiO2 with high surface area were synthesized by atomic layer deposition (ALD). Porous structure of SiO2 could be maintained even after deposition of TiO2 using 500 ALD cycles. All the TiO2-covered SiO2 samples showed comparable methylene blue (MB) adsorption abilities to that of bare ones. Moreover, MB adsorption capability of TiO2/SiO2 was almost fully recovered by simple re-annealing process, whereas MB adsorption capacity of bare SiO2 was not fully recovered by the same treatment. FT-IR study demonstrated that thermal decomposition of adsorbed MB molecules was much facilitated in the presence of TiO2 films, hence preventing deposition of surface-bound species created on the adsorbents surface during the thermal treatment process. Photocatalytic activity of TiO2/SiO2 samples was also investigated as a function of TiO2 film thickness, and the result will be discussed.
Nanoporous TiO2/SiO2 prepared by atomic layer deposition as adsorbents of methylene blue in aqueous solutions
Hyun Ook Seo, Chae Won Sim, Kwang-Dae Kim, Young Dok Kim, Dong Chan Lim
Department of Chemistry, Sungkyunkwan University
Suwon 440-746, Republic of Korea
Materials Processing Division, Korea Institute of Materials Science,
Changwon 641-010, Republic of Korea
Water purification is one of the most important issues in environmental science and synthetic dyes are the main pollutant groups of wastewater. Even in low quantities, presence of dyes can cause serious environmental problems, for instance, growth of aquatic bacteria can be inhibited by interference of penetration of sunlight into water by organic dye molecules. In this study, TiO2/SiO2 was used as adsorbents for removing organic dyes from water. TiO2 films supported by porous SiO2 with high surface area were synthesized by atomic layer deposition (ALD). ALD is a technique widely used in semiconductor industry and recently its application has been extended to environmental science technology. Using ALD, thin film thickness can be controlled on atomic scale. Porous structure of SiO2 could be maintained even after deposition of TiO2 using 500 ALD cycles. All the TiO2-covered SiO2 samples showed comparable methylene blue (MB) adsorption abilities to that of bare ones. Moreover, MB adsorption capability of TiO2/SiO2 was almost fully recovered by simple re-annealing process, whereas MB adsorption capacity of bare SiO2 was not fully recovered by the same treatment. Using FT-IR study, it was demonstrated that thermal decomposition of adsorbed MB molecules was much facilitated in the presence of TiO 2 films, hence preventing deposition of surface-bound species created on the adsorbents surface during the thermal treatment process. TiO 2/SiO2 sample was also showed photocatalytic activity, i.e. the TiO2/SiO2 can be dual-functional for removing organic dyes, i.e. adsorption and photocatalytic decomposition both can take place.
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