JPH10137547A - Method for removing harmful gas and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-performance, compact and inexpensive device for removing harmful gases and to provide its method. SOLUTION: This device for removing harmful gases from a gas contg. the harmful gases has a photocatalyst and a light source 10 for irradiating the photocatalyst with light. Electric field forming electrodes 8 and 9 are provided in the device, the photocatalyst is arranged on at least a part of the positive electrode 8, the intensity of the electric field is preferably controlled to 10V/cm to 5kV/cm, and the positive electorode between the electric field forming electrodes is preferably formed by coating many rod-shaped or fiber- shaped carriers consisting of quartz glass with the surface roughened or a comblike carrier consisting of ceramic with a transparent conductive material and a photocatalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing harmful gases from gases, and more particularly to NOx, SOx, hydrocarbons, NH ₃ , tobacco odor, etc. present in the atmosphere and various gases. The present invention relates to a method and an apparatus for removing harmful gases.

[0002]

2. Description of the Related Art Conventional techniques will be described by taking toxic gases such as NOx, SOx and tobacco odor in various industries and industries. First, regarding the emission of exhaust gas from various industries and industries and the exhaust gas from automobiles into the atmosphere, legal and other regulatory measures are taken from the viewpoint of pollution prevention. In particular, for nitrogen oxides and sulfur oxides, Its emission as a causative agent of acid rain and photochemical smog is severely restricted. Although many methods of treating nitrogen oxides (NOx) and sulfur oxides (SOx) in exhaust gas subject to emission control have been proposed in the past, there are various problems in practice. For example, as a conventional exhaust gas denitration technology,
Reduction method using ammonia, reduction method using catalyst,
A radiation irradiation method and the like have been proposed.

[0003] Each of these conventional methods has the following problems. Reduction method by adding ammonia: Denitration effect is low. Reduction method using a catalyst: When used continuously, catalyst performance is reduced. Since metals and precious metals are used as catalysts, they need to be reviewed from the viewpoint of resource saving. Susceptible to acidic substances in dust. Irradiation method: Since secondary products such as ammonium nitrate and ammonium sulfate are generated in large quantities, it is necessary to separately treat by-products. In addition, since any of these methods adds ammonia, ammonia not consumed in the denitration reaction is discharged as leak ammonia,
Secondary pollution. In addition, it is necessary to review the use of ammonia and resource saving. Further, once these harmful gases are released into the atmosphere, it is difficult to remove them, and a new method and apparatus capable of removing them in the atmosphere are expected.

Next, harmful gases (including odorous gases) containing NOx generated by smoking in homes and offices will be described. These substances are generally regarded as a so-called tobacco odor, and their harmfulness (eg, carcinogenicity) as well as the odor have increased the demand for collection and removal in recent years. For collecting and removing these, there are proposed methods and apparatuses using various removing materials such as those using activated carbon or vegetable essential oil, but all of these removing materials have insufficient performance. The present inventors have previously proposed a method using a photocatalyst (Japanese Patent Application No. 6-48201, Japanese Unexamined Patent Application Publication No.
-10576 publication). Although these methods are effective depending on the application field, there is room for improvement or optimization for improving practicality.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and the prior art, and to provide a high-performance, compact and inexpensive method and apparatus for removing harmful gases. I do.

[0006]

According to the present invention, there is provided a method for removing harmful gas from a gas containing a harmful gas by irradiating the photocatalyst with light. And at least a part of the positive electrode for forming an electric field is made to be a photocatalyst. In the method for removing harmful gas, the electric field strength is 10 V
/ Cm to 5 kV / cm. Further, according to the present invention, in a device for removing a harmful gas from a gas containing a harmful gas having a photocatalyst and a light source for irradiating the photocatalyst, an electrode for forming an electric field is provided, and at least a part of a positive electrode of the electrode is provided. A photocatalyst is arranged in the second. In the removal device, the positive electrode of the electrode for forming an electric field, rod-shaped, cylindrical, fibrous, net-like, it is preferable to use one coated with a photocatalyst on any one or more of the carrier of the fiber, For the negative electrode, for example, a rod-shaped or net-shaped SUS material is preferably used.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is based on the finding that when a photocatalyst is arranged on the positive electrode of an electrode for forming an electric field to form an electric field and the photocatalyst is irradiated with light, the photocatalytic action of the photocatalyst becomes remarkable. Next, each configuration of the present invention will be described in detail.
The photocatalyst may be any as long as it can be used as an electrode (positive electrode) for an electric field and has a photocatalytic action by the photocatalyst. As the photocatalyst, any of those conventionally known as photocatalysts can be used. Generally, semiconductor materials are preferable because they are effective, easily available, and have good workability. In terms of effects and economy, Se, Ge, Si, Ti,
Zn, Cu, Al, Sn, Ga, In, P, As, S
b, C, Cd, S, Te, Ni, Fe, Co, Ag, M
Any of o, Sr, W, Cr, Ba, and Pb, or a compound, an alloy, or an oxide thereof is preferable, and these are used alone or in combination of two or more.

For example, as elements, Si, Ge, Se,
Compounds include AlP, AlAs, GaP, AlSb,
GaAs, InP, GaSb, InAs, InSb, C
dS, CdSe, ZnS, MoS ₂ , WTe ₂ , Cr ₂
Te ₃ , MoTe, Cu ₂ S, WS ₂ , and oxides such as TiO ₂ , Bi ₂ O ₃ , CuO, Cu ₂ O, ZnO, M
oO ₃ , InO ₃ , Ag ₂ O, PbO, SrTiO ₃ ,
BaTiO ₃ , Co ₃ O ₄ , Fe ₂ O ₃ , NiO and the like are available. Currently, the most widely used photocatalyst is TiO ₂
Which can be suitably used in the present invention. However, the photocatalyst used in the present invention is not limited to this.

The photocatalyst has a plate shape, a comb shape,
It can be used by being added on a suitable base material (support material) such as a sheet, a curved surface, a cylinder, a column, a fiber, a bar, a line, a rod, a net, a lattice, and a fiber. Among them, a rod, a cylinder, a fiber, a net, and a fiber are preferable in terms of surface area, workability, and effects. A well-known material can be suitably used for the base material. For example, there are SUS material, glass, ceramic, and fluororesin. The present inventors have already proposed a light-transmitting base material (support) having a roughened surface, which can be suitably used depending on the field of use and the type of device (Japanese Patent Application No. 6-48201, Japanese Patent Application Laid-Open No. 8-10576). No.). As a method for adding the photocatalyst to the base material, a known method can be appropriately used. For example, sol-gel method, sintering method, evaporation method,
There is a sputtering method.

The thickness of the photocatalyst added to the base material can be determined by conducting a preliminary test as appropriate according to the type of the base material and the photocatalyst, the method of irradiating light from a light source, the required performance, and the like. For example, when a photocatalyst is added to the surface and light irradiation is performed from the back, it is effective to carry a photocatalyst having a thickness of 20 to 200 nm on the surface of the glass material (Japanese Patent Application No. 8-46887).
issue). In order to improve the photocatalytic action, Pt, A
A co-catalyst such as g, Pd, Co ₃ O ₄ , or RuO ₂ can be used. A well-known method can be appropriately used for carrying. For example, there are an impregnation method, a precipitation method, an ion exchange method, a photoelectric deposition method, and a kneading method.
It is effective if used in the range of 0% by weight.

In order to use the photocatalyst as a positive electrode, a conductive material can be appropriately added to the base (between the base material and the photocatalyst). For example, when the base material is glass, ceramic, or fluororesin, there is a thin film of indium oxide (In ₂ O ₃ ) or tin oxide (SnO ₂ ), and an In ₂ O ₃ film (ITO) doped with Sn. , Sb-doped SnO ₂ film. In particular, it is effective when glass is used as a base material, a photocatalyst is added to the front surface, and light is irradiated from the back surface. The coating of the conductive material ensures the formation of the electric field using the photocatalyst. The photocatalyst is used under an electric field in which the photocatalyst is used as a positive electrode. As the negative electrode material in the electric field formation, a material in a known charging device can be appropriately used. Examples of the shape include a plate shape, a comb shape, a curved surface shape, a cylindrical shape, a rod shape, a line shape, a rod shape, a net shape, and a lattice shape. Among them, a rod shape and a net shape are preferable in terms of simplicity and effect. C as an example of a material
u, Zn, SUS, and W.

A voltage is applied between the photocatalyst and the electrode material as a positive electrode and a negative electrode, respectively, and an electric field is formed. The electric field strength is effective in the range of 1 V / cm to 10 kV / cm, usually 10 V / cm to 5 kV / cm. By the formation of the electric field of the present invention, the removal reaction of the harmful gas by the photocatalyst occurs quickly (removal speed is high), so that efficient treatment can be performed with a compact apparatus. Although the details of the effect of the electric field of the present invention are unknown, the present inventors' research suggests that the electric field setting increases the potential gradient in the photocatalyst and suppresses the recombination of photocarriers. Is done. With respect to the above, a photocatalyst that has already been proposed by the present inventors to support a photocatalyst on the surface of a light-transmissive support whose surface has an uneven shape and introduces light into the center of the light-transmissive support (Japanese Patent Laid-Open No. 6-4820).
No. 1) will be described as an example.

FIG. 5 is an explanatory diagram showing the operation of the photocatalyst of the present invention. The photocatalyst film 3 is provided on the surface of the light-transmitting support 30.
2 are carried. The light 33 introduced from the light transmissive support 30 is effectively absorbed by the photocatalytic film 32 by the action of the uneven surface of the support 30. When the photocatalytic film 32 absorbs light having energy equal to or greater than the width of the forbidden band, electrons are excited by the conduction band 34 and holes 37 are formed in the valence band 35. Thus, the holes 37 in the valence band 35 have oxidizing power, and the excited electrons 36 in the conduction band 34 have reducing power. Numeral 38 denotes a harmful gas adsorbed on the photocatalyst film as an object to be treated, and the object to be treated is decomposed by the above-mentioned action. The thickness of the coated TiO ₂ is 100 nm. The light source is a high pressure mercury lamp. Here, the gradient between the valence band 35 and the conduction band 34 is increased by setting the electric field according to the present invention, and recombination of photocarriers is suppressed. Thereby, the oxidizing power of the valence band 35 due to the holes 37 increases and stabilizes, and becomes effective. That is, the oxidizing / decomposing action of the harmful gas is efficiently performed by setting the electric field.

The type of the photocatalyst, the type and shape of the base material, the shape and type of the electrode material for forming an electric field with the photocatalyst, and the intensity of the electric field are determined by the field of application, the shape and structure of the device, the size, and the type of the light source described later. Preliminary tests are performed as needed according to the required performance, economy, etc.
You can decide. In the present invention, ultraviolet light and / or visible light can be used as irradiation light, and sunlight or artificial light may be used. The position of the light source can be appropriately selected depending on the application field, the type of the light source, and the shape of the device. Usually, it is preferable to install a light source at the center or inside the reactor because all the light radially emitted from the light source is effectively used. A light source may be provided on the side surface of the reactor, and light may be emitted from the reflection surface. Further, depending on the place of use, it can be used in combination with known harmful gas removing means as appropriate. Well-known harmful gas removing means include activated carbon, activated carbon fiber, zeolite,
There are ion exchange filters (fibers), organic polymer (organic polymer beads), and electret materials.

Further, means using a composite oxide catalyst already proposed by the present inventors (eg, JP-A-6-190236)
And JP-A-6-205930) can be appropriately used depending on the field of use. As a method of using them, usually, when the harmful gas to be treated is relatively high or when there are many kinds of treatment gases, the harmful gas is removed to some extent by these means in advance and then removed by the means of the present invention. As a result, a gas to be treated having a high concentration or a complex harmful gas of a multi-component system can be treated with high efficiency, and an ultra-clean gas or space can be effectively obtained. The present invention relates to NOx, hydrocarbon (particularly, non-methane hydrocarbon), organic Cl compound,
It is effective in detoxifying harmful gases (gaseous pollutants) that are difficult to treat by known means such as mold odor, and is characterized in that harmful gases having extremely low concentrations can be effectively treated.

[0016]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. Embodiment 1 FIG. 1 shows a basic configuration diagram of a harmful gas removing device of the present invention,
This will be used to explain air purification in a hospital.
In FIG. 1, fine particles (particulate matter) and harmful gases (including odorous gases, for example, aldehydes, ketones, pyridines, pyrroles, nitriles, nitrogen oxides, ammonia, etc.) resulting from smoking 2 and the like. 3 has occurred.

For air cleaning, a pretreatment filter 4, an electrostatic filter 5, an activated carbon 6, an ion exchange filter 7, and an electrode (positive electrode) for forming an electric field according to the present invention are installed at the center of the side of the chamber.
This is carried out by a photocatalyst carrier 8 carrying a photocatalyst, which is disposed in the air cleaner, an electrode material (negative electrode) 9 for setting the electric field, an ultraviolet lamp 10, and a fan 11. The photocatalyst carrier 8 is obtained by coating a number of rod-shaped (rod) quartz glasses having irregularities on the surface with ITO as a transparent conductive material and then coating TiO ₂ thereon as a photocatalyst. UV light passes through the rod-shaped quartz glass to excite TiO ₂ on the surface of the quartz glass,
Activates as a photocatalyst.

FIG. 1B is a sectional view taken along the line AA 'of FIG. 1A. 13 is a flow of contaminated air, 14 is an air purifier 12
Shows the clean air purified by. This air purifier 1
In 2, coarse particles that are caused by smoking or the like are first removed by the pretreatment filter 4, and then the remaining particles are removed by the electrostatic filter 5. On the other hand, the harmful gas resulting from smoking is mainly activated carbon 6 to remove mainly neutral substances and acidic substances such as aldehydes and ketones. Next, an alkaline substance such as ammonia is mainly removed by an ion exchange filter (cation type) 7.
As the ion exchange filter, those already proposed by the present inventors can be appropriately used (Japanese Patent Publication No. 5-43422).
No., Tokuhei 5-67325, Tokuhei 6-87995
No., JP-A-5-277336).

Next, NOx and the leaked harmful gas which cannot be removed by these filters are removed by a photocatalyst. Here, the photocatalyst carrier 8 is a feature of the present invention and forms a positive electrode, and an electric field is formed between the photocatalyst carrier 8 and a mesh electrode (negative electrode) 9. The strength of the electric field here is 500 V / cm
It is. The photocatalyst carrier 8 receives the ultraviolet irradiation from the ultraviolet lamp 10 to the photocatalyst serving as the positive electrode, and the photocatalyst function effectively occurs, so that the NOx and the harmful gas are efficiently treated. An example of the reaction by the photocatalyst here is shown below. Hydrocarbons (non-methane hydrocarbons) such as aldehydes and ketones are oxidized and decomposed to harmless substances such as carbon dioxide and light. NOx is removed by being converted to nitric acid and fixed.

The nitric acid converted from NOx on the photocatalyst of the photocatalyst carrier 8 deteriorates the performance of the photocatalyst when operated for a long time, and may be scattered backward by the long-time operation. If a filter for collecting nitric acid as a product (collecting material), for example, an ion exchange fiber (anion type), activated carbon, activated carbon fiber, or glass fiber is appropriately installed, and / or the back thereof, the effect of the photocatalyst is maintained, And,
It can be collected even if it flows backward, so it is preferable depending on the type of equipment, the concentration of the harmful gas to be treated, the type of material for removing other harmful components used, the required performance, and the like. The installation of the collection filter can be determined by conducting a preliminary test as appropriate. The photocatalyst is suitable for treating a low-concentration harmful gas to an extremely low concentration or below the detection limit concentration. Therefore, if the treatment is carried out to a low concentration in advance by a known method as in this example and the final treatment is carried out with a photocatalyst, the treatment can be practically and effectively performed. Odor concentration (value of sensory test) by air cleaner 12
Air 13 containing the tobacco odor 50 to 1,000, the odor concentration of 5 or less, and NOx as a harmful gas 1ppb or less, NH ₃ becomes less 1ppb, clean air 14 is obtained.

Embodiment 2 FIG. 2 shows a schematic configuration diagram of an air purifier using a removing apparatus of the present invention for removing a trace amount of harmful gas in a clean room in a semiconductor factory. In FIG. 2, the class 1,000
In the clean room 20 (number of particles of 0.1 μm or more), NOx, NH ₃ , non-methane hydrocarbons, and fine particles 22 are generated as harmful gases by operation 21, and hydrocarbons (non-methane carbon) are contained in the clean room air. Hydrogen) is present at 1.0-1.5 ppm. These contaminants (the gaseous contaminants and fine particles) contaminate the raw materials, products, and semi-finished products of the semiconductor factory. Therefore, an air purifier 12 is installed to collect and remove the harmful gases and fine particles. Have been done. The device 12 mainly includes a pre-processing filter 4 and a fan 1
1, an ion-exchange filter (cationic form) 7, ULPA filter 5 _-1, 5 _-2, electrodes for electric field formation of the present invention (positive electrode)
And a photocatalyst carrier 8 carrying a photocatalyst disposed in the above, an electrode material (negative electrode) 9 for setting the electric field, and an ultraviolet lamp 10.

FIG. 2B is a sectional view taken along the line BB 'of FIG.
Shown in The air 13 to be treated containing harmful gas is sucked by the fan 11 and the treated clean air is discharged in the direction of arrow 14. Each configuration will be described. The pretreatment filter 4 is a filter mainly composed of glass fibers having a low air resistance, and first, coarse particles (particles having a relatively large particle diameter) in the suction air 13 are removed. The ion exchange filter 7 is a filter for removing NH _{3 in} the clean room such as NH ₃ generated by the operation 21. The filter (described above) already proposed by the present inventors can be appropriately used. ₃ is usually removed to a few ppb or less. ULPA filter 5
_-1 is a filter for removing fine particles in the clean room such as fine particles generated in operation 21. Thereby, the fine particles in the clean room of class 1,000, the fine particles generated by the operation 21 and the fine particles generated by the operation of the fan 11 are removed to class 10 or less.

The photocatalyst carrying member 8 is mainly processing of the NOx generated by the work 21, the NH ₃ than the decomposition-removal and upstream of the hydrocarbon results in an increase of the contact angle to not a few ppb leakage NH ₃ when leaked In this method, a large number of fibrous quartz glass having an uneven surface is coated with ITO and TiO ₂ thereon. Ultraviolet lamp 10 irradiates the TiO ₂ coated the inside of quartz glass coated with TiO ₂ as quartz glass surface, but to act as a photocatalyst. Here, the photocatalyst carrier 8 is a feature of the present invention and serves as a positive electrode, and an electric field is formed between the photocatalyst carrier 8 and a mesh electrode (negative electrode) 9. The strength of the electric field here is 500 V / cm.

The photocatalyst carrier 8 receives irradiation of the photocatalyst serving as a positive electrode with ultraviolet rays from an ultraviolet lamp 10, so that a photocatalytic action occurs effectively. Thereby, NOx in the clean room and NOx generated by the operation 21 are removed to 1 ppb or less. Also, hydrocarbons (non-methane hydrocarbons) do not affect the increase in contact angle. Converted to stable forms like carbon dioxide and water. Also, if the collection and removal of NH ₃ does not work well upstream and leaks,
It is removed up to several ppb (or less). ULPA filter 5
_{Reference numeral -2} denotes a filter for removing fine particles generated from the photocatalyst and its vicinity, which is usually unnecessary, but is installed in an emergency. Thus, the harmful gas in the clean room and the harmful gas (gaseous pollutant) generated in the operation 21 are effectively removed.

As a result, clean air 14 having a NOx concentration of 1 ppb or less, a non-methane hydrocarbon of 0.1 ppm or less, an NH ₃ concentration of 1 ppb or less, and a particle concentration class of 10 or less can be obtained. When harmful gas is generated in the clean room, it adheres to products and semi-finished products, increases the contact angle, and lowers the yield (decreases productivity). Therefore, reducing the concentration of the harmful gas to a certain concentration or less is important for clean room management. The order of combination of the photocatalyst and the known harmful gas removing means in the embodiment is not limited at all, and can be determined as appropriate by conducting a preliminary test. Note that the contact angle is an index indicating the degree of contamination of the solid surface.If the solid surface is contaminated, the contact angle of water well reflects the state of contamination, and if the degree of contamination is large, the contact angle increases. Conversely, if the degree of contamination is small, the contact angle is small.
In FIG. 2, reference numeral 23 denotes a reflection surface, which effectively introduces ultraviolet light from the ultraviolet lamp 10 into the photocatalyst carrier 8.

Embodiment 3 FIG. 3 shows another embodiment of the air cleaning device 12 in Embodiment 2. In FIG. 3, the photocatalyst carrier 8 has a comb-like shape, and a conductive material of ITO,
Further, TiO ₂ was coated thereon as a photocatalyst.
The electric field electrode 9 is an open mesh SUS material. 3, the same symbols as those in FIG. 2 have the same meaning.

Embodiment 4 The air cleaning apparatus shown in FIG.
The following sample air was introduced into the clean room, and the metal substrate was exposed to the outlet air of the air cleaning device, and the contact angle on the substrate was examined. Size of air purifier 12; 40 liters Sample air; non-methane hydrocarbon concentration: 1.2 to 1.5 pp
m NOx concentration: 100 ppb Pretreatment filter 4, coarse filter made of glass fiber Ion exchange filter 7; cationic photocatalyst carrier 8; ITO5 on comb-shaped glass material
0 °, TiO ₂ was coated thereon as a photocatalyst to a thickness of 1,000 ° by a sol-gel method, and an electric field was formed between the electrode material for the electric field described below as a positive electrode and the following electrode material as a negative electrode between the electrodes and the following electrode material for an electric field. . Electrode material 9 for electric field; reticulated SUS ultraviolet lamp 10; germicidal lamp (254 nm) (rod shape) Metal substrate; Cr / glass (Cr on glass: 3,500
被覆 Coating by sputtering) Measurement of contact angle; water drop contact angle meter

Results FIG. 4 shows the relationship between the residence time (reaction time) and the contact angle in the photocatalyst section (the space between the ultraviolet lamp and the photocatalyst carrier in FIG. 3) of the air cleaning device. The contact angle values in FIG. 4 are the contact angles 24 hours after exposing the metal substrate. The residence time was changed by changing the flow rate of the sample air to the air cleaning device. In FIG. 4,-■-is 1 V / c.
m,-□-is 10 V / cm,-△-is 100 V / cm,
-○-is 1 kV / cm, 5 kV / cm, and-●-is
As a comparison, the case where no electric field is applied, the case where there is no coating of TiO ₂ , and the case where only an electric field of 1 kV / cm are set are indicated by-▲-. FIG. 4 shows that at a reaction time of 10 minutes or less, about 1
When an electric field of 0 V / cm or more is set, the reaction by the photocatalyst is performed efficiently. In addition, the above 1 kV /
When the setting of the positive electrode and the negative electrode was reversed in cm (-○ -mark), the value was almost the same as the value without the electric field (-● -mark) in FIG. In the above, the concentration of non-methane hydrocarbons in the treated air was measured by the GC method and the NO concentration by the chemiluminescence method in residence times of 2 minutes and 10 minutes.

Table 1 shows the results.

[Table 1] In the case of the electric field setting of 1 kV / cm of the present invention,
When the operation was performed for a long time, the increase in the contact angle was 3 degrees or less even after the operation for 6,000 hours. On the other hand, when there was no electric field or when the photocatalyst was the negative electrode and the electrode material was the positive electrode (1 kV / cm), the contact angle increased by 3 to 5 degrees after 1,000 hours of operation.

[0030]

As described above, in the present invention, when irradiating the photocatalyst with light, the photocatalyst is set to the positive electrode of the electric field forming electrode, and the opposing electrode material is set to the negative electrode to form the electric field. The following effects are obtained. (1) Since the photocatalytic action of the photocatalyst became effective, the processing speed of harmful gases (gaseous pollutants) was improved. Thus, an effective processing method is provided. (2) A compact processing device is obtained by the above. In addition, the performance could be maintained stably for a long time without depending on the treated material and without being affected by coexisting substances. (3) As described above, the application range of the processing method using the photocatalyst is expanded, and the practicality is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air purifying room in which a harmful gas removing device of the present invention is installed.

FIG. 2 is a schematic configuration diagram of an air purifying room provided with another harmful gas removing device of the present invention.

FIG. 3 is a schematic configuration diagram of an air purifying room provided with another harmful gas removing device of the present invention.

FIG. 4 is a graph showing a relationship between a reaction time (minute) and a contact angle.

FIG. 5 is an explanatory view showing the action of a photocatalyst.

[Explanation of symbols]

1: air purifying room, 2: tobacco, 3: harmful gas, 4: pretreatment filter, 5: electrostatic filter, 5 _-1 , 5 _-2 : ULPA
Filter, 6: activated carbon, 7: ion exchange filter, 8:
Photocatalyst carrier, 9: electrode material (negative electrode), 10: ultraviolet lamp, 11: fan, 12: air purifier, 13: contaminated air, 14: clean air, 21: work, 22: harmful gas, 2
3: Reflector

Claims (5)

[Claims] 1. A method for irradiating a photocatalyst with light to remove a harmful gas from a gas containing a harmful gas, wherein the light irradiation is performed under the formation of an electric field, and at least a part of the positive electrode for forming the electric field is photocatalyzed. A method for removing harmful gases, characterized in that: 2. The electric field has a strength of 10 V / cm to 5 k.
The method for removing harmful gas according to claim 1, wherein the pressure is V / cm. 3. An apparatus for removing a harmful gas from a gas containing a harmful gas having a photocatalyst and a light source for irradiating the photocatalyst with light, wherein an electrode for forming an electric field is provided, and at least a part of a positive electrode of the electrode is provided. A harmful gas removing device provided with a photocatalyst. 4. An electrode for forming an electric field, wherein the positive electrode has a rod shape,
The harmful gas removing apparatus according to claim 3, wherein the photocatalyst is coated on at least one of a cylindrical, fibrous, net-like, and fibrous carrier. 5. The harmful gas removing apparatus according to claim 4, wherein the negative electrode of the electric field forming electrode has a rod shape or a net shape.