title: Effects of peptizing conditions on nanometer properties and photocatalytic activity of TiO2 hydrosols prepared by H2TiO3.
abstract: TiO2 hydrosols were prepared from metatitanic acid (H2TiO3) by chemical precipitation-peptization method under various peptizing conditions. The effects of peptizing conditions on nanosized properties and photocatalytic activity of TiO2 hydrosols were investigated. The crystal structure, crystallinity, particle size distribution, and transparency (T%) of as-obtained hydrosols were characterized by means of X-ray diffraction, transmission electron microscopy, light-scattering size analyzer, and UV-vis transmittance spectra. The results showed that the properties of hydrosols depended on peptizing conditions including a molar ratio of H+/Ti, temperature, and solid content. The photoactivity of TiO2 hydrosols was evaluated in terms of the degradation of rhodamine B (RhB) in aqueous solution, and formaldehyde (HCHO) and methyl mercaptan (CH3SH) in gaseous phase. The results showed that increase in H+/Ti ranging 0.19-0.75 led to the decrease in particle size and the increase in transparency. With increasing of temperature, particle sizes increased while the transparency and photoactivity decreased steadily when the temperature was higher than 65 degrees C. The particle size, transparency and photoactivity of the hydrosols hardly depended on solid content when it was not less than 2%. It should be confirmed that the hydrosols with higher crystallinity, smaller particle size and higher transparency could have the higher photoactivity for the degradation of RhB, CH3SH, and HCHO. In this study, the optimal peptizing conditions were determined to be H+/Ti=0.75, temperature=65 degrees C and solid content=2-6%.
authors.affiliation: Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environment and Soil Sciences, Guangzhou 510650, PR China.
authors.forename: Tong-xu
authors.initials: TX
authors.lastname: Liu
authors.forename: Fang-bai
authors.initials: FB
authors.lastname: Li
authors.forename: Xiang-zhong
authors.initials: XZ
authors.lastname: Li
mesh_terms: D000393:Air Pollutants / Q000737:chemistry / Q000528:radiation effects; D002384:Catalysis; D011232:Chemical Precipitation; D004396:Coloring Agents / Q000737:chemistry / Q000528:radiation effects; D005557:Formaldehyde / Q000737:chemistry / Q000528:radiation effects; D049329:Nanostructures / Q000737:chemistry; D010777:Photochemistry; D012235:Rhodamines / Q000737:chemistry / Q000528:radiation effects; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000528:radiation effects; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D018505:Waste Management / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects
chemical_list: D000393:Air Pollutants; D004396:Coloring Agents; D012235:Rhodamines; D013438:Sulfhydryl Compounds; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D005557:Formaldehyde; C005231:methylmercaptan; D014025:Titanium; C029773:rhodamine B