Photocatalytic air treatment process under room light
First Claim
1. A process for photocatalytically sterilizing a room having an interior defined by enclosing surfaces including vertical walls and a ceiling, comprising:
- covering at least a part of the enclosing surfaces of the room with a thin film of photocatalytic semiconductor material having a band gap energy;
disposing in the room an electric lamp for emitting visible light with sufficient intensity to illuminate the room with said visible light, said lamp emitting substantially no wavelength component of less than 300 nm and emitting ultraviolet radiation having an energy higher than the band gap energy of said semiconductor material in an amount effective to photoexcite said thin film; and
energizing said lamp to illuminate said room with visible light and to simultaneously impinge said ultraviolet radiation upon said thin film with an intensity of 0.001-0.1 mW/cm2, to thereby photoexcite said thin film with said ultraviolet radiation whereby bacteria brought into contact with said thin film are photocatalytically destroyed upon illumination of said room.
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Accused Products
Abstract
A process for photocatalytically treating a hospital room contaminated by bacteria or an interior environment bearing airborne malodorous substances. A thin film of photocatalyst made of a semiconductor such as titanium dioxide is disposed on the inner wall of the hospital room or living space. The photocatalytic thin film is irradiated by a light source suitable for general lighting applications, such as a fluorescent lamp, and is photoexcited by the small amount of ultraviolet radiation included in the light of fluorescent lamp. The wattage of the fluorescent lamp as well as the distance between the photocatalytic thin film and the lamp are selected such that the intensity of those UV wavelengths which have a higher energy than the band gap energy of the photo-catalyst is 0.001-1 mW/cm2, preferably, 0.01-0.1 mW/cm2. The bacteria and chemical compounds deposited on the photoexcited thin film are photodecomposed.
101 Citations
24 Claims
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1. A process for photocatalytically sterilizing a room having an interior defined by enclosing surfaces including vertical walls and a ceiling, comprising:
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covering at least a part of the enclosing surfaces of the room with a thin film of photocatalytic semiconductor material having a band gap energy; disposing in the room an electric lamp for emitting visible light with sufficient intensity to illuminate the room with said visible light, said lamp emitting substantially no wavelength component of less than 300 nm and emitting ultraviolet radiation having an energy higher than the band gap energy of said semiconductor material in an amount effective to photoexcite said thin film; and energizing said lamp to illuminate said room with visible light and to simultaneously impinge said ultraviolet radiation upon said thin film with an intensity of 0.001-0.1 mW/cm2, to thereby photoexcite said thin film with said ultraviolet radiation whereby bacteria brought into contact with said thin film are photocatalytically destroyed upon illumination of said room. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A process for photocatalytically decontaminating a room having an interior defined by enclosing surfaces including vertical walls and a ceiling, comprising:
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covering at least a part of the enclosing surfaces of said room with a thin film of photocatalytic semiconductor material having a band gap energy; disposing in the room an electric lamp for emitting visible light with sufficient intensity to illuminate the room with said visible light, said lamp emitting substantially no wavelength component of less than 300 nm and emitting ultraviolet radiation having an energy higher than the band gap energy of said semiconductor material in an amount effective to photoexcite said thin film; and energizing said lamp to illuminate said room and to simultaneously impinge said ultraviolet radiation upon said thin film with an intensity of 0.001-1 mW/cm2, to thereby photoexcite said thin film with said ultraviolet radiation whereby contaminants brought into contact with said thin film are photodecomposed upon illumination of said room. - View Dependent Claims (17, 18, 19, 20)
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21. A process for photocatalytically cleaning a surface of a fixture located in a toilet room, said toilet room having an interior defined by enclosing surfaces including vertical walls and a ceiling, said process comprising:
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covering at least a part of the surface of said fixture with a thin film of photocatalytic semiconductor material; disposing an electric lamp in the toilet room for emitting visible light with sufficient intensity to illuminate the toilet room with visible light, for emitting substantially no wavelength component of less than 300 nm and for emitting ultraviolet radiation having an energy higher than the band gap energy of said semiconductor materials in an amount effective to photoexcite said thin film; and energizing said lamp to illuminate the toilet room with visible light and to simultaneously impinge said ultraviolet radiation upon said thin film with an intensity of 0.001-1 mW/cm2, to thereby photoexcite said thin film with said ultraviolet radiation whereby contaminants deposited onto said fixture are photodecomposed as said lamp is energized. - View Dependent Claims (22)
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23. A process for photocatalytically sterilizing a room having an interior defined by enclosing surfaces including vertical walls and a ceiling, said room being equipped with an electric lighting fixture, said lighting fixture being adapted to emit visible light rays for illuminating the room, and to emit ultraviolet radiation having a wavelength not less than 300 nm, said process comprising:
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covering a part of the inner wall of said room with a thin film of photocatalytic semiconductor material; and operating said lighting fixture to illuminate said room and to simultaneously impinge said ultraviolet radiation upon said thin film with an intensity of 0.001-1 mW/cm2, to photoexcite said thin film with said ultraviolet radiation and to thereby photocatalytically destroy bacteria deposited on said thin film. - View Dependent Claims (24)
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Specification