Synthesis of TiO_{2鈭?span style='font-style: italic'>x} visible-light photocatalyst using N₂/Ar/He thermal plasma for low-concentration elemental mercury removal

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• 作者：Hsing-Cheng Hsi^a ; ^{hchsi@ntut.edu.tw} ; Cheng-Yen Tsai^b
• 关键词：Oxygen vacancy ; Titanium dioxide ; Plasma torch ; Elemental mercury
• 刊名：Chemical Engineering Journal
• 出版年：2012
• 期刊代码：16_13858947
• 类别：ce
• 出版时间：15 May, 2012
• 卷：191
• 期：Complete
• 页码：378-385
• 文件大小：1128 K

摘要

Oxygen-vacant titanium dioxide (TiO_2鈭?em>x) nanoparticles possessing a narrower band gap were synthesized with a single-step process using N₂/Ar/He thermal plasma as a heating source. Sample characterization showed that the formed TiO_2鈭?em>x nanoparticles had a size within 5-40 nm and were in a mixing form of anatase and rutile. An evident absorption red shift to 470 nm wavelength was observed. The deconvolution results of XPS spectra supported the formation of TiO_2鈭?em>x due to the presence of Ti³⁺2p peaks. The Hg removal efficiency of TiO_2鈭?em>x nanoparticles increased with increasing O₂ concentration and in the presence of light irradiation, suggesting an enhancement in Hg⁰ oxidation. H₂O molecules, however, greatly reduced the Hg removal of TiO_2鈭?em>x under visible-light (VL) irradiation. The photoinduced hydrophilicity of TiO_2鈭?em>x under VL irradiation was suspected to amplify the competitive adsorption of H₂O that decreased Hg capture. Hg removal performances at 50 掳C were better than those at 25 and 100 掳C, suggesting that both adsorption and catalytic oxidation limit the Hg removal. These observations also implicate that the bonding between TiO_2鈭?em>x and adsorbed Hg was weak and adsorption reaction may be reversible.