Kimiyasu Shiraki,1* Hiroshi Yamada,1 Yoshihiro Yoshida,1 Ayumu Ohno,1 Teruo Watanabe,2 Takafumi Watanabe,2 Hiroyuki Watanabe,2 Hidemitsu Watanabe,2 Masao Yamaguchi,2 Fumio Tokuoka,3 Shigeatsu Hashimoto,4 Masakazu Kawamura,5 Norihisa Adachi5
1Department of Virology, University of Toyama
2APS Japan Co., Ltd.
3Shonan Ceramics Corporation
4Department of Metabolism, Diabetes and Nephrology. Fukushima Medical University Aizu Medical Center
5TechnoPLAS Japan Co., Ltd. Japan
Nano-Micro Conference, 2017, 1, 01043
Published Online: 26 October 2017 (Abstract)
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The efficiency of photocatalysis depends on the surface area and materials, and we have prepared a nanosized-titanium dioxide (TiO2)-coated ceramic irradiated by UV- LED lamps as a photocatalytic air cleaner. Ceramic filter system decomposed 80% of acetaldehyde and Particulate dioxins (40 pg/m3) and gaseous dioxins (16 pg/m3) were removed by 7.5 and 2.8 pg/m3 by passing through four TiO2-coated ceramic (30 × 30 × 2 cm) under black-light, indicating about 80% of dioxin was decomposed by the photocatalysis. Ceramic was changed to aluminum plate and the efficiency was improved. The 90% of 5 ppm acetaldehyde (12.4 μmol/h) was decomposed and generated carbon dioxide (25.43 μmol/h; RC: 92.5% carbon dioxide conversion rate) efficiently and continuously for 200 min with the ratio of one acetaldehyde (12.40 μmol/h) to two carbon dioxide (25.43 μmol/h) at their molar ratios by being passed through the TiO2-coated aluminum plate (5 × 10 × 1 cm) under black light, indicating complete decomposition of acetaldehyde with high efficiency. This photocatalysis system was applied for elimination of acetaldehyde and inactivation of influenza aerosol in a closed cubic space using aluminum plates. Acetaldehyde at 20 ppm in a cubic 1 mspace was eliminated by 60 min at a half-life of 8 min. The aerosol-associated infectivity and the RNA genome of influenza virus produced by a nebulizer in a 779 liter cubic space were eliminated within 7 minutes but were detectable up to 28 minutes without the function of a photocatalytic air cleaner. Influenza virus was broken down by photocatalysis rather than being trapped by Hepafilter as intermediate breakdown products of influenza virus were observed. Thus, a photocatalytic air cleaner efficiently decomposed and eliminated organic chemicals, acetaldehyde, and aerosol-associated influenza virus infectivity and viral RNA, indicating a photocatalytic air cleaner functioned in the cleaning and detoxification of the air in the closed space for maintaining a safer environment.

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