JP2000210570A - Photocatalyst device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalytic apparatus whose photocatalyst efficiency is improved and whose handling convenience is improved. SOLUTION: A glass tube 12 bearing a photocatalyst film 11 on the outer face is installed in the circumference of a light source 14 capable of emitting ultraviolet rays with 400 nm or shorter wavelength. Photocatalytic reactions such as organic matter decomposition, malodorous component deodorization, and germ disinfection, are carried out on the photocatalyst surface 11. In the case the refractive index of the photocatalyst film 11 is higher than that of the glass 12, the optical path length in the photocatalyst film is long and the ultraviolet rays from the light source can effectively be utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst device that decomposes organic substances, deodorizes malodorous components, sterilizes fungi, and the like using a photocatalyst.

[0002]

2. Description of the Related Art Along with an increase in social awareness of environmental issues, a new technology for purifying a living environment has been receiving attention. Amid the urgent need to take measures to control the emergence and proliferation of food-borne pathogens, a new environmental regulation bill for fungi is being formulated. For example, 199
The US Food Sanitation Management System HACCP (Haza
With the introduction of the rd Analysis Critical Control Point, measurement and inspection of fungi will be performed at food production sites throughout Japan, and new measures to remove fungi will be required. On the other hand, in daily life, more favorable measures are required to improve the quality of air and water, that is, to maintain a safer and healthier human body.

[0003] In general, a phenomenon in which many fungi accumulate and spread occurs in an enclosed space where circulation with outside air is poor. For example, contamination of air in a living room or food in a refrigerator. The concentration of these fungi depends on the ppt, ppb, p
It is present at concentrations much lower than the pm order. However, the effect on the human body is great, and fungi cause allergic symptoms, various diseases, and infection. It is conceivable that antibacterial technology in a living environment that requires clean air and water will be widely spread in the future, by decomposing live bacteria to make them harmless.

With respect to odors, a wide range of measures are required especially for unpleasant components. There is a need for the development of new technologies that can diffuse into the air in rooms and refrigerators and enter the body by respiration as it is, or that refrigerators can easily and efficiently remove odor components attached to food. In addition, since the diffusion of the odor component and the diffusion of the fungus are linked, the purification technology eventually becomes a countermeasure for both.

[0005] Regarding the purification of air in a room or in a closed space, many techniques have been proposed for the purpose of deodorizing. The easiest method is to use adsorbents and filters, but this is a physical capture separation, so if they are saturated with adsorbate, they need to be replaced or washed, and the recovery and regeneration problems are reduced. Come out. There is a method of using an adsorbent and a filter together with a fan and an air conditioner, but the problem remains the same.
Even when the surface area or capacity has a sufficiently long period, the initial removal ability cannot be maintained for a long period of time because the surface gradually saturates. In addition, adsorbents and filters provide a place to concentrate and store odor components.Furthermore, when a substance such as activated carbon is used as an adsorbent, it is rather fundamental that bacteria proliferate in the adsorbent. There are also problems.

For both deodorization and sterilization, chemical detoxification is one desirable method. However, for example, there is a method of sterilizing and deodorizing by generating ozone, and a sterilizing method using an ultraviolet lamp having a short wavelength. However, all of these methods have problems in safety and management, and require careful handling for business use. It is more difficult to handle for home use. Although deodorization can be performed by a system using a general catalytic reaction that functions with the assistance of thermal energy, there are problems with all measures and costs. Thus, a new method that is simple, safe, energy-saving, and can simultaneously perform both deodorization and sterilization is desired.

[0007] Under such circumstances, many deodorizing and antibacterial techniques using a photocatalyst have been recently proposed. A photocatalyst is a type of semiconductor.When a photon with energy exceeding the band gap collides with the photocatalyst, it excites electrons in the valence band to the conduction band to create activated electron-hole pairs, where the air When oxygen and water molecules come into contact, active species such as various active oxygens, hydroxyl radicals and ions are generated on the photocatalyst surface, and oxidatively decompose various organic substances, malodorous components, and fungi.

[0008]

In order to maximize the effect of the photocatalyst, it is important to enhance the performance of the photocatalyst material itself, but thereafter, it depends on how to use light effectively. Titanium oxide, which is currently regarded as the most influential photocatalytic material, is excited by light in the ultraviolet wavelength region of 400 nm or less. Therefore, how effectively the wavelength in the ultraviolet region can be effectively used greatly affects the photocatalytic effect. On the other hand, in a system in which a light source lamp and a photocatalyst are integrated as described in JP-A-10-116587, a photocatalyst film that can be used semi-permanently is formed on the outer surface of a glass tube constituting a part of the light source. Is filmed. Since the life of the light source lamp is shorter than the life of the photocatalyst, when the life of the light source lamp comes, the light source lamp and the photocatalyst are discarded or at least collected.

The present invention has been made in view of the present situation of a system for simultaneously performing deodorization, sterilization, and antifouling using such a photocatalyst.
An object of the present invention is to provide a photocatalyst device in which the effect of the photocatalyst is improved and the usability is improved.

[0010]

According to the present invention, a structure in which a light source and a photocatalytic film are separated from each other is employed. And a wavelength of 400
The object is achieved by increasing the efficiency of use of ultraviolet light by utilizing the refraction or reflection of light generated when ultraviolet light of nm or less enters a medium having a low refractive index from a medium having a low refractive index. That is, a photocatalyst device according to the present invention includes a light source that emits ultraviolet light having a wavelength of 400 nm or less, and a glass tube that is disposed around the light source and has a photocatalytic film formed on an outer surface thereof. Decomposition of organic substances on the photocatalyst surface, deodorization of malodorous components,
Photocatalytic reaction such as sterilization of fungi is performed. When the refractive index of the photocatalyst film is larger than the refractive index of glass, the optical path length in the photocatalyst film becomes longer, and ultraviolet light can be used effectively.

[0011] The photocatalytic device according to the present invention also includes a black light source and a glass tube disposed around the black light source and having a photocatalytic film made of titanium oxide having an anatase crystal structure formed on an outer surface thereof. It is characterized by the following. In the photocatalytic device of the present invention, air may be sealed between the light source and the glass tube arranged outside the light source.

The photocatalyst device according to the present invention also has a wavelength of 4
A light source that emits ultraviolet light of 00 nm or less, a glass tube disposed around the light source and having a photocatalytic film formed on the outer surface, and an ultraviolet reflecting tube disposed around the glass tube and formed with a photocatalytic film on the inner surface Wherein a fluid can flow between the glass tube and the ultraviolet reflecting tube. The photocatalytic device according to the present invention also includes a light source that emits ultraviolet light having a wavelength of 400 nm or less, a glass tube that is disposed around the light source and has a photocatalytic film formed on the outer surface, and a photocatalyst that is disposed around the glass tube and is disposed around the inner surface. And a metal tube on which a film is formed.

The photocatalyst device according to the present invention also has a wavelength of 4
A light source that emits ultraviolet light of 00 nm or less, a glass tube disposed around the light source and having a photocatalytic film formed on the outer surface, and a gas permeable member disposed around the glass tube and having a photocatalytic film formed on the inner surface. And a tubular metal mesh. The photocatalytic device according to the invention also has a wavelength of 400 nm.
It is characterized by including a light source that emits the following ultraviolet light, and a plurality of glass tubes arranged around the light source and having different diameters on which a photocatalytic film is formed on the surface. By arranging a plurality of glass tubes on which a photocatalytic film is formed around a light source that emits ultraviolet light to form a multi-tube structure, the photocatalytic film can fully utilize photons in the ultraviolet wavelength region to improve the photocatalytic reaction effect. Can increase.

The photocatalyst device of the present invention can efficiently deodorize and sterilize odors, fungi, and the like that come into contact with the photocatalyst at room temperature by a chemical reaction. This photocatalytic device enables deodorization and sterilization indoors, in a water environment, in a refrigerator, and the like. In the refrigerator, the food itself, which is stored cold regardless of odor components or fungi, is a deodorant and a fungal capture agent. According to the present invention, these undesired suspended substances in the refrigerator can be treated chemically to render them harmless.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 is a view for explaining an example of a photocatalyst device according to the present invention. FIG. 1 (a) is a sectional view of the device perpendicular to the tube axis, and FIG. FIG. FIG.
As shown in (1), for example, a glass tube 12 having a photocatalytic film 11 formed on its outer surface is installed around a glass tube 14 constituting a part of a fluorescent lamp as a light source. At this time, a space is provided between the two glass tubes 12 and 14 so that the space 13 is sealed, for example, with air. The space 13 may be filled with a medium other than air and having a different refractive index from glass, or the space 13 may be a vacuum. In order to make the two glass tubes 12 and 14 concentric as much as possible, and to make the spatial distance between them uniform, for example, O-rings 15 are provided at both ends of the glass tubes to integrate them. However, since the two glass tubes can be easily separated from each other, the life of the light source lamp is over, and when it is broken, only the light source lamp needs to be replaced. Glass tube 12 on which photocatalytic film 11 is formed
Can be used for a long time without being affected by the life of the light source lamp.

The photocatalyst device shown in FIG. 1 is designed to make effective use of light in the ultraviolet region by utilizing the properties of light passing through media having different refractive indexes. Generally, the reflection R of light passing through two different media is represented by the following equation. Here, n ₁ = the refractive index of the medium 1 and n ₂ = the refractive index of the medium 2. R = [(n ₂ −n ₁ ) / (n ₂ + n ₁ )] ² Rewriting this gives the following equation.

R = [(n ₂ / n ₁ -1) / (n ₂ / n ₁ +1)] ² Therefore, when the refractive index n ₁ is close to the refractive index n ₂ , the reflection R of light is zero. , And the reflection hardly occurs. On the other hand, the refractive index n ₂ is sufficiently larger than the refractive index n ₁ , and n ₂ / n ₁ ≫
When it is 1, the reflection R of the light is close to 1, that is, the reflectance is almost 100%.

FIG. 2A shows an optical path of light passing through different media. Light 16 transmitted through the glass tube 14 from the inside of the glass tube 14 constituting a part of the light source passes through the air in the space 13, further transmits through the glass tube 12 on the outside, and removes the photocatalytic film 11 on the surface. To Penetrate. When the photocatalytic film is titanium oxide, light in the ultraviolet region is absorbed during transmission through the titanium oxide, and the energy of the photons is used to generate activated electrons. A hall is also created at the same time. The number of electron and hole pairs generated is proportional to the number of transmitted photons. These pairs move to the surface of the photocatalytic film 11 and produce active species together with oxygen and moisture in the air in contact with the photocatalytic film 11. The longer the light path of the light passing through the photocatalytic film 11 is, and the more the light transmitted without absorption is transmitted and absorbed sufficiently to generate as many electron / hole pairs as possible, the higher the light utilization efficiency becomes. The photocatalytic reaction effect per unit surface area is improved.

FIG. 2B shows a light 16 particularly effective for a photocatalyst.
Of the optical path. At the interface between media having different refractive indexes, for example, glass 12 and titanium oxide photocatalytic film 11, glass 1
A part of the light 16 transmitted through 2 is absorbed by the photocatalytic film 11 (accordingly, contributes to the generation of active electrons and holes), and the remaining light is reflected, changes its course, and transmits through the glass 12 again,
The air further passes through the air in the space 13 and reaches the glass 14 constituting a part of the light source. The light 16 incident on the glass 14 is partially reflected on the surface of the glass 14, reaches the photocatalytic film 11 again, and is absorbed. In this way, the system is structured so that light of a wavelength that can be used for activating the photocatalyst can be used as much as possible.

If the photocatalyst film 11 is continuous, that is, if it is a crystallographically and electrically continuous film in which electrons and holes can move throughout the film, the above phenomenon is particularly effective and the photocatalytic reaction is Promoted [Reference: Shinichi Ichik
awa and Ryota Doi, ”Photoelectrocatalytic Producti
on of Hydrogen from Water on Transparent Thin Film
Titania of Different Crystal Structures and Quant
um Efficiency Characteristics ”, Thin Solid Films,
292, 130 (1997)].

In the above equation representing the reflection of light, in the case of titanium oxide, the refractive index n ₂ of the light wavelength in the ultraviolet region is relatively large. For example, in the case of ultraviolet light having a wavelength of 360 nm, about 20% is reflected because n ₁ = 1.5 for glass with respect to n ₂ = 3.9 for titanium oxide (reference book on refractive index: “Handbook of Optical Constants”). of Solids ”, e
dited by Edward D. Palk, Academic Press Incorporat
ed, London, 1985). Similarly, reflection occurs at the interface between air and glass. Accordingly, light having a wavelength of 360 nm is effectively used as shown in FIGS. In the case of titanium oxide, the wavelength dependence of the refractive index is large, and the shorter the wavelength, the higher the refractive index. Therefore, light containing more ultraviolet regions has a higher reflectance at the interface with glass.

Further, as shown in FIGS. 2 (a) and 2 (b),
When light enters the photocatalytic film 11 from the glass 12, the light travels from the glass having a low refractive index to the titanium oxide having a high refractive index, so that the transmitted light is bent at the interface between the glass 12 and the titanium oxide photocatalytic film 11, The optical path of the ultraviolet light passing through the film 11 becomes longer due to refraction. A longer optical path means that the number of electrons and holes generated by absorbing photons of ultraviolet light increases, and thus the photocatalytic effect increases. As described above, the photocatalytic device of the present invention can increase the photocatalytic reaction effect by utilizing the properties of light emitted from the light source.

The physical properties and optical characteristics of the photocatalyst will be described below, including experimental findings. The experiment was conducted by assembling the double-tube photocatalyst device shown in FIG. 1 using a 6 W general fluorescent lamp and a 6 W black light emitting mainly 365 nm ultraviolet light as a light source. The glass tube constituting a part of the light source is soda glass. Soda glass is also used for the glass tube 12 outside the light source, and titanium oxide is formed on the outer surface of the glass tube 12 by the sol-gel method as follows.
And

A titanium sol solution was prepared by dissolving titanium tetraisopropoxide as a raw material in ethanol as a solvent and adding an aqueous hydrochloric acid solution as a hydrolyzing solution to ripen it. Apply this titanium sol solution to its inner surface (inner wall)
Only the outer surface (outer wall) of the glass tube 2 was coated so that the titanium sol solution did not adhere to the film, and then fired to form a film. Titanium oxide deposited by this method has been reported to be crystallographically and electrically continuous, has an anatase crystal structure, and exhibits high quantum efficiency and high photocurrent in the water splitting reaction [ Shinichi Ichikawa and Ryota Doi,
Catalysis Today, 27, 271 (1996); Shinichi Ichikaw
a and Ryota Doi, Thin Solid Films, 292, 130 (199
7)]. This indicates that the electron transfer continuous thin film photocatalyst has a high density of active electrons and holes per unit light irradiation area, and therefore has a high activity in reactions such as decomposition of organic substances, deodorization, and sterilization. It represents.

A simple experiment was conducted to determine the angle at which transmitted light was emitted to the outside from the surface of the glass tube and the surface of the photocatalytic film formed on the glass tube. The light emitted perpendicularly from the surface of the glass tube and the light emitted at an angle of 45 degrees were measured with the illuminance at a wavelength of 365 nm as light energy per unit area through a pinhole of about 1 mm. First, while the 45-degree light from the 6 W black light glass tube 14 was 27.5% of the vertical light, the above photocatalytic film was formed directly on the surface of the black light glass tube 14. Is 45 degrees light and vertical light is 34.
8%. This is the case of the single tube system.

Next, as shown in FIGS. 1 and 2, another glass tube 12 is disposed outside the glass tube 14 constituting a part of the light source, and a photocatalyst is placed on the outer surface of the glass tube 12. The same measurement was performed using an apparatus having a double tube structure on which the film 11 was formed. First, the 45 degree light from another glass tube 12 provided on the outer periphery of the 6 W black light glass tube 14 was 29.9% of the vertical light. On the other hand, when the photocatalytic film 11 was formed on the surface of the other glass tube 12, the 45-degree light was 36.6% of the vertical light.

These data indicate that, due to the difference in the refractive index between the photocatalytic film of titanium oxide having an anatase crystal structure and that of glass, 365-nm ultraviolet light transmitted through the photocatalytic film is transmitted at different angles. I have. As a result of this angle change, the optical path of the ultraviolet light in the photocatalyst film is lengthened, so that the number of activated electrons and holes is increased, the surface active species are increased, and the activity per unit photocatalyst surface area is improved. Furthermore, this data shows that when a photocatalytic film is formed on the outer surface of a glass tube placed around a light source as a double tube structure, ultraviolet light with a wavelength of 365 nm is transmitted from a single glass tube to the double tube via air. This shows that the light is further refracted and transmitted before passing through the glass tube as compared with the case of only a single tube. The greater the refraction, the longer the optical path.

The above phenomenon is obtained as a result of measuring a part of a limited light beam. However, since the number of transmitted photons is large, the overall effect is large. Wavelength 365
nm photons from 10 ¹⁴ photon / cm ² s to 10 ¹⁶ photon
Since it is constantly generated at a rate of n / cm ² · s, a corresponding number of electrons and holes are generated while passing through the photocatalytic film, and a number of surface active species corresponding to those electrons and holes are generated. It is made and causes a photocatalytic reaction.

Next, the results of measuring the optical characteristics of the glass tube itself by various experiments will be described. Therefore, in this experiment, no photocatalytic film was formed on the surface of the glass tube. First, light energy at a wavelength of 365 nm on the outer surface of the glass tube of a 6 W general-purpose fluorescent lamp was measured. The value varies depending on the location in the tube axis direction, but is 0.093 mW / cm on average.
^{Was 2} . When another glass tube is provided on the outer periphery of the glass tube of this lamp, the light energy at a wavelength of 365 nm on the outer surface of the outer glass tube is 0.07 on average.
It was 7 mW / cm ² . The light from the light source is partially absorbed and reflected by the second glass tube, so that the energy has a low value. Further, the light energy of the outer surface of the glass tube constituting the black light that emits ultraviolet light having a wavelength of 365 nm, which is mainly 365 nm, averages 4.22 mW / cm ² , and the outer surface of another glass tube provided therearound. Had an average light energy of 3.53 mW / cm ² . Calculating from these measurements, the light energy at a wavelength of 365 nm emitted from the outer surface of the outer glass tube in the double tube system is compared with the light energy at the outer surface of the glass tube forming part of the light source. Therefore, it is 83% for a general fluorescent lamp and 84% for a black light. Thus, regardless of the value of the light energy from the light source, the wavelength 365n after transmission through the double tube is obtained.
The ratio of the light energy of m is almost constant and does not change. This ratio is determined by the physical properties of the glass itself, and indicates that it does not depend on the number of photons per unit cross-sectional area or per unit time, and can be understood theoretically. Therefore, even if various types of light sources are used, the above basic principle is the same.

The same light energy measurement as described above was also performed on a Pyrex (Pyrex borosilicate Corning 7740) glass tube. Pyrex has a slightly lower refractive index than soda glass, but almost the same (wavelength 5).
Pyrex has a refractive index of 1.47 at 89 nm compared to a refractive index of 1.52 of soda glass). On the other hand, the transmittance of UV light is higher in Pyrex than in soda glass. As described above, in comparison between the Pyrex tube and the soda glass tube from the light energy measurement at the wavelength of 365 nm, the Pyrex tube had higher transmittance.

Next, the double-tube photocatalyst device (the space 13 is air) shown in FIG. 1 is installed in a closed-circulation-system reaction vessel equipped with vacuum evacuation, an oil-free circulation pump, and the like. An experiment was conducted in which 10 ppm of acetaldehyde, which is a malodorous component, was introduced, and after waiting until the concentration became constant, the light source was turned on to start the reaction. The change in concentration was measured by gas chromatography by sequential gas phase sampling. The reaction vessel was at room temperature.

FIG. 6 shows the results. C represents the concentration of acetaldehyde in ppm, and its logarithmic value is plotted against the reaction time. Here, a case where a continuous thin film of titanium oxide having an anatase type crystal structure is directly formed on the outer surface of the glass tube of various 6W lamps of a light source is referred to as a single tube structure. As shown in FIG. The case where a continuous thin film of titanium oxide having an anatase type crystal structure is formed on the outer surface of the placed glass tube 2 is called a double tube structure. In FIG. 6, (1) shows a single tube structure and 6 W as a light source.
A device using a general fluorescent lamp, (2) a device using a 6W general fluorescent lamp as a light source with a double tube structure,
(3) shows the deodorizing activity of an apparatus using a 6 W black light as a light source in a single tube structure and (4) an apparatus using a 6 W black light as a light source in a double tube structure.

As shown in FIG. 6, in any of the apparatuses, after the reaction time has elapsed, the decomposition reaction of acetaldehyde proceeds and the concentration decreases. In each case, since the measurement points are almost linear, it can be regarded as a first-order reaction, and the magnitude of the gradient of the straight line represents the reaction constant. In other words, the slope of the log C vs. time line indicates the magnitude of the reaction rate. In this case, the larger the slope, the higher the reaction rate and the higher the activity. When a general fluorescent lamp is used as the light source, the double tube structure (2) has an activity of about 3 compared to the single tube structure (1).
Twice as high. In comparison with the case where a black light is used as a light source, the activity of the double tube structure (4) is about three times higher than that of the single tube structure (3).

That is, in any case, the double tube has higher deodorizing activity than the single tube. Moreover, since light is transmitted by an extra glass in the double tube compared to the single tube, the light energy is higher in the double tube than in the single tube as shown in the above measurement results. Is running low. Deodorizing activity is high despite low light energy. This is an important point of this system. Light energy can be used effectively by the double tube system.

Next, the above-mentioned various photocatalyst devices were installed in a household refrigerator, and the same measurement was carried out for trimethylamine and methyl mercaptan, which are malodor components peculiar to the refrigerator. The initial concentration of each was 10 ppm. The temperature was between 3C and 5C. In each case, the activity order was the same as in FIG. 6, and the superiority of the double tube as compared with the single tube was confirmed even at a low temperature. The deodorizing activity of trimethylamine was higher than that of methyl mercaptan.

The glass tube outside the double tube was a Pyrex tube, and an anatase-type titanium oxide film was formed on the outer surface of the glass tube. As a result, the performance was higher than that of the soda glass tube in any of the odors. This is thought to be due to the high UV transmittance of the Pyrex tube.

[Embodiment 2] In the photocatalytic device having a double tube structure shown in FIG. 1, ultraviolet rays having a wavelength of 400 nm or less which cannot be absorbed by the photocatalytic film are emitted to the outside. Then, in order to utilize it more effectively, a photocatalyst device having a multi-tube structure as shown in FIG. 3 was manufactured. FIG. 3A is a sectional view of the device perpendicular to the tube axis, and FIG. 3B is a sectional view of the device parallel to the tube axis.

The photocatalyst device shown in FIG. 3 has a quadruple tube structure. Glass tubes 22a, 22b, and 22c having different tube diameters are provided outside spaces 23a, 23b, and 23c, respectively, outside a glass tube 24 constituting a part of the light source. 23c.
The inner glass tube 22a has a photocatalytic film 21a on the outer surface. The middle glass tube 22b has photocatalytic films 21b and 21c on the inner surface and the outer surface, and the outer glass tube 22c has photocatalytic films 21d and 21e on the inner surface and the outer surface. The inner glass tube 22a is connected to the glass tube 24 constituting a part of the light source by O.
Fixed through the ring 25, the space 23a is an air-tight space, but the space 23b between the inner glass tube 22a and the middle glass tube 22b, and the middle glass tube 22b and the outer glass The space 23c between the tubes 22c has an open end so that outside air can freely flow.

The deodorizing activity of acetaldehyde was measured using a photocatalyst having a multi-tube structure shown in FIG. In this case, not only does the air containing the malodorous component come into contact with the photocatalytic film 21e formed on the outer surface of the outer glass tube 22c, but also the air containing the malodorous component passes through the spaces 23b and 23c between the glass tubes. The measurement was performed in a closed circulation system. When the results were compared with the photocatalyst devices of the triple tube structure and the double tube structure, the activity order was higher as the number of tubes was larger, indicating the effect of the multi-tube structure. In this case as well, in all the devices, the activity was higher when Pyrex glass was used than when soda glass was used for the glass tubes 22a, 22b, and 22c.

Embodiment 3 A photocatalyst device shown in FIG. 4 was manufactured. FIG. 4A is a sectional view of the apparatus perpendicular to the tube axis, and FIG.
(B) is an apparatus sectional view parallel to the tube axis. This photocatalyst device is provided outside the double-tube photocatalyst device shown in FIG.
This corresponds to the arrangement of the metal mesh 36 with a photocatalytic film. A glass tube 32 having a photocatalytic film 31 formed on the outer surface around a glass tube 34 constituting a part of a light source is an O-ring 3.
5, and a metal mesh 36 with a photocatalytic film is further disposed outside. Air is sealed in a space 33a between the glass tube 34 and the glass tube 32. The fluid around the photocatalytic device flows into the space 33b between the glass tube 32 provided with the photocatalytic film 31 and the metal mesh 36 with the photocatalytic film through the open opening at the end of the device, and also flows into the space 3b through the metal mesh 6. be able to.

The photocatalyst device of the present embodiment was compared with the photocatalyst device of the double tube structure shown in FIG. 1 in terms of the acetaldehyde deodorizing activity. As a result, in the photocatalyst device of the present embodiment, light almost entirely hits the surface of the metal mesh 36 on the light source side, but showed a deodorizing activity higher than that of the photocatalyst device having only the double tube structure.

Embodiment 4 The photocatalyst device shown in FIG. 5 was manufactured. FIG. 5A is a sectional view of the device perpendicular to the tube axis, and FIG. 5B is a sectional view of the device parallel to the tube axis. This photocatalyst device corresponds to a photocatalyst device having a double-tube structure shown in FIG. 1 in which a metal tube 46 having a photocatalyst film 41b formed on the inner surface is disposed outside. The metal tube 46 is made of aluminum or the like and reflects ultraviolet light. A glass tube 42 having a photocatalyst film 41a formed on the outer surface around a glass tube 44 constituting a part of a light source is disposed via an O-ring 45, and a metal having a photocatalyst film 41b formed on the inner surface outside the glass tube 42. A tube 46 is arranged. Air is sealed in a space 43a between the glass tubes 44 and 42. Fluid around the photocatalyst device passes through the open opening at the end of the photocatalyst film and the photocatalytic film
1a flows into a space 43b between a glass tube 42 provided with 1a and a metal tube 46 having a photocatalytic film 41b formed on the inner surface.

The photocatalyst device of the present embodiment was compared with the photocatalyst device having a double tube structure shown in FIG. 1 in terms of acetaldehyde deodorizing activity. As a result, it was found that arranging the metal tube 46 with the photocatalyst film 41b outside the double tube contributes to the improvement of the deodorizing activity. This is because light passes through the photocatalyst film 41b on the surface of the metal tube 46 and is reflected at the interface between the photocatalyst film 41b and the metal tube 46, and the reflected light hits the photocatalyst film 41a on the surface of the inner glass tube 42. It is considered that light is effectively used.

[Embodiment 5] A single-tube photocatalyst device (soda glass tube) or a double-tube photocatalyst device (soda glass tube) is placed in a closed-circulation reaction vessel for performing an antibacterial test.
Was set up, and the experiment was carried out at room temperature by confining room air. In the reaction vessel, a filter of an airborne bacteria sampler is attached to a bypass flow path of a circulation pump, so that bacteria can be periodically captured for a certain period of time. After capture, add the culture solution to the filter and keep at 30 ° C for 72 hours.
, And the number of bacterial colonies was counted to determine the increase or decrease of the bacteria. In this case, it is the total viable count.

When comparing a single tube with a double tube, it is difficult to carry out experiments with exactly the same initial number of colonies, but as a result of observing the tendency by increasing the number of experiments under almost the same conditions,
It was found that the tendency was similar to that of the deodorizing activity ranking in FIG. In addition, in the case where the bacteria-collecting filter and culture are determined only for staphylococci, and a black light is used, the difference between the single-tube photocatalyst device and the double-tube photocatalyst device is clear, The antibacterial effect of the photocatalytic device having the double tube structure was high. The fact that the antibacterial effect was seen in conjunction with the deodorizing activity in this way means that the generation rate of surface active species in the double-tube photocatalyst device was higher than that in the single-tube photocatalyst device in each case. It suggests.

[0046]

According to the present invention, the light in the ultraviolet region emitted from the light source can be efficiently utilized, and the photocatalytic activity can be enhanced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a photocatalyst device according to the present invention.

FIG. 2 is a diagram illustrating an optical path of light transmitted through different media.

FIG. 3 is a diagram illustrating another example of the photocatalyst device according to the present invention.

FIG. 4 is a diagram illustrating another example of the photocatalyst device according to the present invention.

FIG. 5 is a diagram illustrating another example of the photocatalyst device according to the present invention.

FIG. 6 is a comparison diagram of deodorizing activity.

[Explanation of symbols]

11 ... Photocatalyst film, 12 ... Glass tube, 13 ... Space, 14 ...
Glass tube constituting a part of fluorescent lamp, 15 ... O-ring, 16 ... Light, 21a-21e ... Photocatalytic film, 22a ... Inner glass tube, 22b ... Intermediate glass tube, 22c ... Outer glass tube, 23a 23c ... space, 24 ... glass tube constituting part of light source, 25 ... O-ring, 31 ... photocatalytic film, 32 ... glass tube, 33a, 33b ... space, 34 ... glass tube constituting part of light source , 35 ... O-ring, 36
... Metal mesh with photocatalyst film, 41a, 41b ... Photocatalyst film, 42 ... Glass tube, 43a, 43b ... Space, 44 ... Glass tube constituting a part of light source, 45 ... O-ring, 46
… Metal tube

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Claims (8)

[Claims] 1. A photocatalytic device comprising: a light source that emits ultraviolet light having a wavelength of 400 nm or less; and a glass tube disposed around the light source and having a photocatalytic film formed on an outer surface thereof. 2. The photocatalytic device according to claim 1, wherein a refractive index of said photocatalytic film is larger than a refractive index of glass. 3. A photocatalyst comprising: a blacklight light source; and a glass tube disposed around the blacklight light source and having a photocatalytic film made of titanium oxide having an anatase crystal structure formed on an outer surface thereof. apparatus. 4. The photocatalyst device according to claim 1, wherein air is sealed between the light source and the glass tube. 5. A light source that emits ultraviolet light having a wavelength of 400 nm or less, a glass tube disposed around the light source and having a photocatalytic film formed on an outer surface, and a photocatalytic film disposed around the glass tube and on an inner surface. And an ultraviolet reflecting tube on which a film is formed,
A photocatalyst device, wherein a fluid can flow between the glass tube and the ultraviolet reflecting tube. 6. A light source that emits ultraviolet light having a wavelength of 400 nm or less, a glass tube disposed around the light source and having a photocatalytic film formed on an outer surface thereof, and a photocatalytic film disposed around the glass tube and disposed on an inner surface. A photocatalyst device comprising: a metal tube on which a film is formed. 7. A light source that emits ultraviolet light having a wavelength of 400 nm or less, a glass tube disposed around the light source and having a photocatalytic film formed on an outer surface, and a photocatalytic film disposed around the glass tube and formed on an inner surface. And a gas permeable tubular metal mesh having a film formed thereon. 8. A photocatalyst device comprising: a light source that emits ultraviolet light having a wavelength of 400 nm or less; and a plurality of glass tubes having different diameters disposed around the light source and having a photocatalytic film formed on a surface thereof. .