Eco-Materials Processing & Design VII

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Authors: Jong Oh Kim, Won Youl Choi, Byung Kyu Choi, Jong Tae Jeong
Abstract: This research investigated the water purification performance of thin film with anatase phase TiO2 powder having good photocatalytic property using an innovative aerosol deposition method at the normal room temperature. Fresh raw powder was dehydrated for good dispersion of TiO2 powder. To suppress the formation of second particle, the powder was dispersed for 90 minutes in alcohol bath with ultrasonic treatment and then desiccated. The average grain size of particle was identified to be 1µm in TiO2 thin film deposited on stainless steel mesh by scanning electron microscopy (SEM). The anatase phase of TiO2 thin film was investigated by X-ray diffraction (XRD). The anatase phase of fresh raw powder was favorably maintained after aerosol deposition treatment.
Authors: Koichiro Tsujimaru, Masakazu Anpo
Abstract: Advanced ion-beam techniques such as metal ion-implantation and RF magnetron sputtering deposition were successfully applied in the development of titanium oxide photocatalysts capable of absorbing and working under both UV and visible light irradiation. This advanced physical method was found to be one of the most promising approaches to preparation of highly functional second-generation titanium oxide-based photocatalytic materials, TiO2 nano-powders, highly dispersed titanium oxide species within zeolite frameworks, and TiO2 thin film systems with efficient solar beam utilization of up to 20-30 %.
Authors: Hiromi Yamashita, Yoshikatsu Nishida, Osamu Chiyoda, Hiroyuki Nose, Masaki Narisawa, Tesutaro Ohmichi, Iwao Katayama
Abstract: TiO2/SiC was prepared by oxidizing the TiC-SiC precursor obtained by carbothermic reduction process of TiO2-SiO2 binary oxide. An XRD analysis indicated the formation of the mixture of anatase and rutile phases of TiO2 crystalline after the oxidation of TiC-SiC sample. TiO2/SiC photocatalyst exhibited a higher photocatalytic reactivity than TiO2-SiO2 binary oxide prepared by the conventional sol-gel method. These results indicate the advantages of SiC nano powders as catalyst support of the TiO2 photocatalysts, and TiO2/SiC photocatalyst is effective for the degradation of organic compounds diluted in water.
Authors: Xiao Bing Zhao, Xuan Yong Liu, Chuan Xian Ding
Abstract: TiO2 coatings on titanium alloy substrates were prepared by atmospheric plasma spraying using commercial nano-powders. Then, as-sprayed coatings were treated using 10% hydrofluoric acid (HF) at room temperature for 30 seconds. As-sprayed and HF-treated titania coatings were soaked in simulated body fluid to investigate the formation of apatite on their surface. Field-emission scanning electron microscopy was used to observe the surface morphologies, and the phase composition of the as-sprayed coating and apatite were analyzed by X-ray diffraction and energy-dispersive X-ray spectrometry. As-sprayed titania coating is composed of rutile, anatase, and a small quantity of Ti3O5. It exhibited excellent adhesion between the TiO2 coatings and titanium alloy substrates, and the bonding strength was about 38 MPa. After in vitro experiment, a new substance containing calcium and phosphate was formed on the surface of HF-treated TiO2 coatings after being soaked in SBF, while the new substance was not formed on the surface of as-sprayed TiO2 coatings. The results indicated that the bioactivity can be induced to the surface of plasma sprayed TiO2 coatings by hydrofluoric acid treatment.
Authors: X.P. Zhu, Tsuneo Suzuki, Hisayuki Suematsu, Wei Hua Jiang, Koichi Niihara
Abstract: Nitriding of titanium was achieved in a vacuum of ~2×10-2 Pa by applying intense pulsed ion beam (IPIB) irradiation. Various phases including ‘pure’ nitrides (e.g. Ti2N, TiN) as well as carbonitrides (e.g. TiC0.3N0.7) were found on the IPIB-irradiated surfaces that depended on the ion beam intensity, shot number, and sample position with respect to the ion beam axis. It was found that the nitrides were preferably produced at moderate beam intensity by which the nitriding depth increased greatly with multi-shot irradiation. No or less nitrides were produced under irradiation of very high intensity or less number of shots. It is demonstrated that the IPIB nitriding process is very efficient even in vacuum where the residual N2 can readily react with melted Ti surfaces under IPIB irradiation. The origin of incorporated C in the nitrides is mainly attributed to the anode material of ion diode used in the IPIB apparatus.
Authors: Hiroshi Taoda, Mitsuharu Fukaya, Eiji Watanabe, Kazuhiko Tanaka
Abstract: Sick house syndrome caused by volatile organic compound (VOC) in the room is a serious problem in Japan. A photocatalytic wall paper was developed which is a wall paper coated with a visible light type of photocatalyst. When irradiated by light, the photocatalyst generates strong oxidative potential and decomposes almost all organic substances to water, carbon dioxide, and others. As a result of our experiment using the photocatalytic wall paper, toluene and acetaldehyde were decomposed efficiently even under a fluorescent lamp, and the photocatalytic wall paper had also strong anti-bacterial effect under the fluorescent lamp.
Authors: Zeng Yi, Wei Wu, Jun Tao Liu, Jian Hua Gao, Chuan Xian Ding
Abstract: TiO2 is a promising photocatalyst due to its excellent photocatalytic activity, physical and chemical stabilities. Plasma spraying technology is good way to prepare for TiO2 coating. The effect of spraying parameters on photocatalytic performance was studied. The results showed that both the amount of unmelted particles and the porosity of as-sprayed TiO2 coatings increased with the increasing of Ar gas flow rate. And the external bias could improve TiO2 coating’s photocatalytical performance. The improvement degree is closed related its grain size and porosity.
Authors: Ling Han, Tae Ki Lim, Young Jun Kim, Hyun Sik Hahm, Myung Soo Kim
Abstract: Catalytic decomposition of methane is an environmentally attractive approach to CO2-free hydrogen production. The decomposition of methane over carbon nanofibers was carried out in a fixed bed flow reactor. The objectives of this study are to demonstrate the activity of carbon nanofibers for methane decomposition in comparison with that of carbon black and to investigate the nature of active sites in the carbon catalysts. The catalytic activities of different carbon catalysts were found in the following order: carbon nanofiber > HI-900L carbon black > N330 carbon black > non-catalyst. After investigating the surface area and mass of the carbon catalysts after methane decomposition, the nature of active sites was discused.
Authors: Ji Hwan Park, Sung Gab Kim, Seong Soo Park, Seong Soo Hong, Gun Dae Lee
Abstract: Transient reaction of adsorbed monolayer of acetic acid was used to compare the photocatalytic properties of TiO2 (Degussa P-25), titanium silicalite (TS-1) and Ti-MCM-41. TS-1 and Ti-MCM-41 catalysts with Si/Ti ratio of 50 were prepared by in-situ crystallization. The catalysts were characterized using XRD and UV-DRS. During photocatalytic oxidation (PCO), CO2 and HCHO were formed on P-25 TiO2, whereas CO2 and CH4 formed on TS-1 and Ti-MCM-41. Acetic acid decomposed photocatalytically on P-25 TiO2 to form CO2, CH4 and C2H6. On the contrary, CO2 and CH4 were formed on TS-1 and Ti-MCM-41 during photocatalytic decomposition (PCD). The rates of product formation during PCD were lower than PCO. The TS-1 and Ti- MCM-41 catalysts were less active per gram of catalyst. However, the TS-1 and Ti-MCM-41 catalysts had much higher adsorption capacities for organics. Therefore, it seems that the TS-1 and Ti-MCM-41 catalysts have some advantages in applications to PCO of organic comtaminants under conditions where the organic concentrations vary widely.
Authors: Eiji Watanabe, Mitsuharu Fukaya, Hiroshi Taoda
Abstract: The establishment of evaluation test method of the titania photocatalyst fine particle impact to human body skin was attempted. In this method, the amount of emergence of carbon dioxide, which was expected one of the generation products from the artificial skin according to the titania photocatalyst fine particles activity, was identified and measured by the gas analyzer. It was found that the amount of the carbon dioxide evolution from the artificial skin was different according to the difference of the particle size of the titania photocatalyst fine particle.

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