Papers by Author: Fumio Saito

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Authors: Kornkanok Ubonchonlakate, Lek Sikong, Tienchai Tontai, Fumio Saito
Abstract: The photocatalytic Ag and Ni doped TiO2 films were prepared by sol-gel method and coated on glass fiber roving. The films were calcined at 500 °C for 1 hour with a heating rate of 10°C/min. The surface morphology and properties of synthesized TiO2 films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and UV-vis diffuse reflectance spectroscopy (DRS). The results show that TiO2-1Ag and TiO2-1Ag-1Ni films give rapidly kill P.aeruginosa bacteria under UV irradiation and TiO2-1Ni films give well kill P.aeruginosa bacteria under visible light.
Authors: Mahamasuhaimi Masae, Lek Sikong, Kalayanee Kooptarnond, Wirach Taweepreeda, Fumio Saito
Abstract: The objective of this study is to explore a method to improve hydrophilicity of the surface of formers that could be more easily dipped to produce high quality dipped rubber products. Photocatalytic TiO2 composite films were prepared by sol-gel method. Glass formers were coated with the Ni/B/N/TiO2 nanocomposite film by dipping method and annealed at 400°C for 1 h. Phase formation of TiO2 was characterized by XRD. Morphology of the TiO2 films was observed by using atomic force microscopy (AFM). Optical absorption of the films and degradation concentration of methylene blue had been measured employing UV-Vis spectrophotometer. The hydrophilicity of the thin films was determined in terms of the contact angles of water and NR rubber latex droplets on the coated TiO2 composite films under visible light irradiation. It was found from the experimentally study that the Ni/B/N/TiO2 nanocomposite film can improve wet-ability of the coated former surfaces.
Authors: Guo Min Mi, Fumio Saito
Abstract: Some dry and wet grinding experiments have been respectively conducted on titanium dioxide which is a noble photocatalyst material in a mortar, a tumbling mill and a planetary mill. Anatase is apt to transform to rutile via a metastable phase brookite in every kind of mills in the case of dry grinding. And it hardly takes place for phase transformation from rutile to other forms. It is shown that the kind of mill has not decisive effect on the mechanochemical polymorphic transformation of titanium dioxide, which merely influences the rate of phase transformation. On the other hand, the addition of other liquid media, such as water and acetone, is helpless for phase transformation of anatase. Only anatase can transform to metastable phase brookite by wet grinding. When ground titanium dioxide is heated, the amorphous phase is easier to transform to rutile than metastable phase brookite at lower temperature.
Authors: Hyung Kyung Yu, Seong-Geun Oh, Byun Gil Lee, Fumio Saito, Ho Jin Ryu
Authors: Qi Wu Zhang, Fumio Saito
Abstract: As the extension of mineral processing, recycling metals from wastes is very important for a sustainable society. We have been working on mechanochemistry and its engineering applications. One of the applications is to recover and separate useful components from different kinds of wastes emitted in our society. When a waste sample is subjected to grinding in air so called mechanical treatment, it changes its structure to disordered system, resulting in chemical reactions with other substances when it takes over the certain level of energy. Depending on the existing states of target elements in the wastes, mechanical activation and mechanochemical (MC) reaction can be applied for the recycling of useful compositions and a process based on MC treatment has been developed. We will report several examples from our research experiences at the conference. The first example is to recover rare earths from fluorescent powders in waste lamps. The waste is firstly subjected to dry grinding to cause amorphization of their structures. This amorphization makes it possible to dissolve the rare earths from the waste at high yield by leaching with mild acid solution at room temperature. Similar phenomenon can be seen in the case of ITO (indium tin oxide) scrap when it is ground, followed by leaching with acid solution. In this case, dry grinding the scrap induces disordering the In2O3 in the scrap, leading to high dissolution of In2O3 by leaching with weak acid solution at room temperature. The presence of alumina (α-Al2O3) in the scrap plays a significant role to the amorphization. Another advanced waste processing is to recover molybdenum (Mo), vanadium (V) and nickel (Ni) sulphide in catalysts in oil refineries. The processing is based on MC reactions between the sulphides and additives. That is, the sulphides are subjected to dry grinding with additives such as CaO, MnO2 and Na2CO3 to transform them into molybdate and vanadate. Subsequent water leaching allows us to recover Mo and V from the ground product. Other successful example is dry grinding metals or their oxides with polyvinyl chloride (PVC) to transform into chlorides, which dissolve easily in water at ambient condition. The waste processing described above is now in the investigation on industrial applications, and this is a great expectation in the field of industries which emit such waste materials.
Authors: Mahamasuhaimi Masae, Lek Sikong, Kalayanee Kooptarnond, Wirach Taweepreda, Fumio Saito
Abstract: The effect of Ni doping in Ni and B co-doped TiO2 composite films on photocatalytic reaction and hydrophilic property were investigated. The TiO2 composite films were prepared by sol-gel and coated on glass substrates by dipping methods. These composite thin films were calcined at the temperatures of 400°C for 1 h. Phase formation of TiO2 was characterized by XRD. Morphology of TiO2 composite films were observed by using atomic force microscopy (AFM). The chemical composition and purity of the prepared films were analyzed by EDS, FTIR and FT-Raman spectrometers. The photoactivity of synthesized films was performed by means of degradation of methylene blue dye solution under UV and visible light irradiation. The hydrophilic property was measured in terms of a contact angle of water droplet on the films with and without the activation of UV irradiation. It was found that Ni doping seems to affect on TiO2 phase, crystallinity of the anatase phase, crystallite size of the composite films and band gap energy of the catalysts, resulting in their photocatalytic reaction and hydrophilic property. The crystallinity of anatase increased with an increase in Ni content varied from 0-3 mol% but decreased with an increase in Ni content above 3 mol%. It was found that 3 mol% Ni/B/TiO2 film, having highest crystallinity and smallest crystallite size shows the highest of photocatalytic reaction while 2 mol% Ni/B/TiO2 film provides the most hydrophilic effect. Only anatase phase was found at the calcination temperature of 400°C. The smooth film surfaces exhibits a high hydrophilic property. Super-hydrophilicity (contact angle equal to zero) of all B and Ni co-doped TiO2 films was found at UV irradiation for 25 minutes.
Authors: Jae-Kil Han, Sung Min Choi, Ik Hyun Oh, Fumio Saito, Byung Teak Lee
Abstract: TiO2(1-.ZrO2. (.=- 0.2, 0.4, 0.6 and 0.8) composite powders having a homogeneous distribution and nanocrystalline were successfully synthesized by sol-gel process using titanium iso-propoxide as precursor. The particle sizes of TiO2-ZrO2 powders calcined at 600°C were measured ranging from 10nm to 19nm by XRD and TEM. For the comparison of photocatalytic activity, TiO2-ZrO2 composite powders were tested in the degradation of phenol and the photoreduction of inorganic pollutants. The degradation of phenol increased with increase the content of anatase TiO2 phase.
Authors: Ryo Inoue, Junya Kano, Kaoru Shimme, Fumio Saito
Abstract: It is legally demanded that the wastes containing asbestos should be change to harmless substances completely due to the harmful effects of asbestos fiber on health. The purpose of present research was to construct a safe, reliable and facile technique by using mechano-chemical reaction, which is a non-combustion process and operated in a closed system. It was confirmed that the needle crystal of chrysotile asbestos was changed perfectly to amorphous state after grinding by using a planetary ball mill. Furthermore, these products could be remade to useful materials by addition of soil which consists of inorganic materials based on CaO and so one. After the obtained fine powders were mixed with water, pressed and held under the humid condition, the stable hydrates were found in these products after XRD analysis. These inorganic compounds were much useful as a new raw material for cement-like.
Authors: Kanatip Kumproa, Apinon Nuntiya, Qi Wu Zhang, Fumio Saito
Abstract: Mechanochemical processing of zirconium oxychloride and yttrium chloride precursors with lithium carbonate has been used to synthesis ultrafine powders of yttria-stabilized zirconia. The purposes of this work are to synthesis 8% mol yttria-stabilized zirconia powder via a mechanochemical process and to study the effect of LiCl as an inert diluent on agglomerate size of ultrafine powders. 8% mol yttria-stabilized zirconia powder was prepared from zirconium oxychloride and 8 %mol yttrium chloride precursors with lithium carbonate by using planetary ball mill and heat treatment. Chemical reaction between reactant mixtures occurs during post-milling heat treatment at low temperature to form composite powder. The products of this reaction consist of ultrafine powders embedded within LiCl as soluble salt by-product. The ultrafine powder is then recovered by removing the salt through a washing procedure. The powders were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and particle size analysis. The results indicated that 8% mol yttria-stabilized zirconia crystal structure depends on post-milling heat treatment temperatures. The structure of yttria-stabilized zirconia is transformed to a tetragonal form at 400 oC and 500 oC. Furthermore, it tends to form a cubic structure at 600 oC. However, agglomerate size of ultrafine powders also depends on the concentration of lithium chloride as an inert diluent and the washing procedure. Primary particle size of ultrafine powders is 30 nm.
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