Fujico Corporation

Kitakyūshū, Japan

Fujico Corporation

Kitakyūshū, Japan
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Ishikawa S.,University of Kitakyushu | Li S.,University of Kitakyushu | Huang C.,University of Kitakyushu | Tanizaki T.,Environmental Bureau | And 3 more authors.
Sustainable Environment Research | Year: 2015

Water for cleaning wafers intended for integrated circuit (IC) fabrication was produced using a combination of ozone (O3), ultra-violet ray (UVR), super-sonic wave (SSW) and a TiO2 photocatalyst deposited on quartz glass by low-temperature spraying. Using both UVR and SSW led to a decrease in the concentration of oxidants in the treated water compared to the case for UVR alone. However, the oxidant concentration increased in the presence of the photocatalyst. Although the O3concentration was reduced by SSW irradiation, in the presence of the photocatalyst over half of the oxidants were species other than O3. Following UVR, no O3 was detected and only a small amount of other oxidants was present. Using both SSW and UVR irradiation led to an increase in the concentration of other oxidants. The concentration was further increased in the presence of the photocatalyst. Following SSW and UVR irradiation, the oxidants continued to exist for 5 min. The results of a chemiluminescense analysis indicated that the treated water contained mainly OH radicals associated with the ionization of metals. This water is expected to be effective for cleaning wafers prior to IC fabrication, in addition to other applications. © 2015, Chinese Institute of Environmental Engineering. All Rights Reserved.


Li S.,University of Kitakyushu | Ishikawa S.,University of Kitakyushu | Huang C.,University of Kitakyushu | Zhang W.,University of Kitakyushu | And 3 more authors.
Sustainable Environment Research | Year: 2015

The production and behaviors of active intermediates formed during ultraviolet ray (UVR)/ supersonic wave (SSW) reactions in water were investigated using a nano-reaction field separation TiO2 photocatalyst sprayed at low temperature. The oxidizing substances were radicals, which were detected during SSW application, because they could exist for several minutes via a micro- or nano-bubble effect. However, they were not detected during UVR irradiation alone because they immediately disappeared under these conditions. A large amount of the radicals were produced and acted as strong oxidative decomposition agents. The amount of the oxidizing substances increased with the photocatalyst. For methanol (CH3OH), about 4.1% was converted to CO2 after 4-h reaction. Five intermediates containing formic acid were detected. For dimethylsulfoxide (DMSO), an 18.7 mol% reduction occurred after 4-h reaction and methanesulfinic acid and methanesulfonic acid were detected. DMSO was not converted to volatile C-containing compounds. © 2015, Chinese Institute of Environmental Engineering. All rights reserved.


Ishikawa S.,University of Kitakyushu | Li S.,University of Kitakyushu | Zhang W.,University of Kitakyushu | Tanizaki T.,Environment Bureau | And 2 more authors.
Sustainable Environment Research | Year: 2014

The photo-decomposition of 24 volatile organic compounds produced by chlorination at a water purification plant was investigated using a nano-reaction field separation TiO2 photocatalyst. Using a black light with a major wavelength of 365 nm, the compounds, with the exception of tert-butyl methyl ether, benzene, cis-1,3-dichloropropene, and tetrachloroethylene, were slightly decomposed after 4-h irradiation. In contrast, most of the compounds were decomposed using a fluvial type of sterilizeing lamp with a wavelength of 254 nm. Greater than 40% of 1,1-dichloroethylene, benzene, trichloroethylene, bromodichloromethane, toluene, tetrachloroethylene, dibromochloromethane, o,m,p-xylene, and bromoform were decomposed after 4-h irradiation. However, similar decompensation of these compounds occurred without the photocatalyst. While compounds containing a C-Cl, C-Br, or C=C bond or a benzene ring were easily decomposed, ether and the benzene compounds containing an alkyl base or C-Cl bond were minimally decomposed. No correlation was found between decomposition ratio and boiling points, water solubilities, or dielectric constants.

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