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Meguro-ku, Japan

Ochiai T.,Kanagawa Academy Of Science And Technology | Iizuka Y.,Kanagawa Academy Of Science And Technology | Iizuka Y.,Kanagawa University | Nakata K.,Kanagawa Academy Of Science And Technology | And 6 more authors.
Diamond and Related Materials | Year: 2011

The electrochemical decomposition of environmentally persistent perfluorooctanoic acid (PFOA) was achieved by the use of a boron-doped diamond (BDD) electrode. The PFOA decomposition follows pseudo-first-order kinetics, with an observed rate constant (k 1) of 2.4 × 10 - 2 dm 3 h - 1. Under the present reaction conditions, k 1 increased with increasing current density and saturated at values over 0.60 mA cm - 2. Therefore, the rate-limiting step for the electrochemical decomposition of PFOA was the direct electrochemical oxidation at lower current densities. In the proposed decomposition pathway, direct electrochemical oxidation cleaves the C-C bond between the C 7F 15 and COOH in PFOA and generates a C 7F 15 radical and CO 2. The C 7F 15 radical forms the thermally unstable alcohol C 7F 15OH, which undergoes F - elimination to form C 6F 13COF. This acid fluoride undergoes hydrolysis to yield another F - and the perfluorocarboxylic acid with one less CF 2 unit, C 6F 13COOH. By repeating these processes, finally, PFOA was able to be totally mineralized to CO 2 and F -. Moreover, whereas the BDD surface was easily fluorinated by the electrochemical reaction with the PFOA solution, medium pressure ultraviolet (MPUV) lamp irradiation in water was able to easily remove fluorine from the fluorinated BDD surface. © 2010 Elsevier B.V. All rights reserved. Source


Ochiai T.,Kanagawa Academy Of Science And Technology | Ochiai T.,Tokyo University of Science | Nakata K.,Kanagawa Academy Of Science And Technology | Nakata K.,Tokyo University of Science | And 6 more authors.
Nanoscience and Nanotechnology Letters | Year: 2012

Anodizing process could improve the air purification ability of TiO 2-sintered Ti-mesh filter. The surface morphology of Ti-mesh could be controlled by anodizing with suitable applying voltage. Ti-mesh which heated after anodizing at 70 V or 90 V shows purple or green color, respectively. It suggests that the presence of a specific thickness of the TiO 2 layer (about several hundred nm) fabricated by anodizing process. Moreover, Ti-mesh samples that heated after anodizing at 70 V and 90 V show rough surface. The TiO 2 particles were successfully sintered on these rough surfaces with the particle sizes of about 0.1 μm. However, TiO 2-sintered Ti-mesh sample without anodizing shows no interference color and highly aggregated TiO 2 particles on the surface. The air purification activity of these Ti-mesh filters corresponded to its surface morphology. Therefore, anodizing process could strongly affect to not only surface morphology of Ti-mesh filter, but also its air purification efficiency. These results would be attractive to develop more effective photocatalytic air purification filter. © 2012 American Scientific Publishers. Source


Slimen H.,Kanagawa Academy Of Science And Technology | Slimen H.,Gabes University | Ochiai T.,Kanagawa Academy Of Science And Technology | Ochiai T.,Tokyo University of Science | And 8 more authors.
Industrial and Engineering Chemistry Research | Year: 2012

TiO 2-impregnated titanium mesh filter (TMiP) elaborated by electrochemical anodization of the titanium mesh, followed by dip coating into TiO 2 anatase solution, was used for the removal of cigarette smoke as a principal indoor air pollutant. The TMiP catalyst revealed high activity for the removal of ammonium, nicotine, 3-ethenylpyridine, and tar, which constitute some of the volatile and nonvolatile compounds of cigarette smoke. As a practical application, an air purifier has been developed and tested for the removal of cigarette smoke. © 2011 American Chemical Society. Source


Ochiai T.,Kanagawa Academy Of Science And Technology | Ochiai T.,Tokyo University of Science | Hayashi Y.,Im PACT World Co. | Ito M.,IDEA Consultants Inc. | And 7 more authors.
Chemical Engineering Journal | Year: 2012

The novel air-cleaner with photocatalysis-plasma synergistic reactor was developed as an effective method for the separation of smoking area. The reactor consists of two essential technologies: plasma assisted catalytic technology (PACT) reactor and a TiO2 impregnated Ti-mesh filter (TMiP™). The air-cleaners were tested by the tobacco smoke deodorization tests according to both the standard test method for air cleaner and the proposed test method. In the standard test method, 80-100% decrease of the concentrations of gaseous compounds in tobacco smoke in 1m3 box has been achieved for 30min by the air-cleaner. It seems that present system which realize a better contact among the TMiP surface, the gas phase, and high-energy and reactive species generated by PACT is effective to have the benefit of plasma enhanced photocatalysis. On the other hand, more practical test method in the real-scale smoking room (2.7×3.6×2.5m) includes the analysis of a trace amount of gaseous compounds the evaluation by using a one-pass system from smoking room to non-smoking room was proposed. Almost of the compounds could be decomposed and/or removed by the practical air-cleaner with " one-pass" condition. The proposed test method would lead to establish the suitable method for the separation of smoking room. © 2012 Elsevier B.V. Source


Ochiai T.,Kanagawa Academy Of Science And Technology | Ochiai T.,Tokyo University of Science | Nanba H.,Kanagawa Academy Of Science And Technology | Nanba H.,Kanagawa University | And 15 more authors.
Catalysis Science and Technology | Year: 2012

An ozone-assisted photocatalytic water-purification unit using a TiO 2 modified titanium-mesh sheet (TMiP) was investigated. Significant decomposition of biological and chemical contaminants has been achieved by highly active intermediates formed by catalytic decomposition and photocatalysis. Source

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