JP7218841B2 - Deodorizing method and deodorizing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a deodorizing method and a deodorizing apparatus for deodorizing a target space or an object.

Conventionally, a method using ozone is known as a method for deodorizing spaces such as inside a house or an automobile and objects provided in these spaces. This method is superior in that it can decompose the odorous substance itself, which is the cause of the odor, by the oxidizing power of ozone, unlike the method of masking the odor with a perfume or the like.

A method of deodorizing using both ozone and a photocatalyst has also been proposed. For example, Patent Literature 1 and Patent Literature 2 describe an apparatus for decomposing organic matter in the air, which includes an ozone generating section and a carrier on which a photocatalyst is supported. ing. The ozone generator in Patent Document 1 is the lamp 50 in FIG. 1 of the same document, and the carrier is the photocatalyst filter 40 in the same figure. The ozone generator in Patent Document 2 is the ozone generator 1 in FIG. 1 of the same document, and the carrier is the catalyst carrier 9 in the same figure. Further, Patent Document 3 describes a deodorization method in which ozone is supplied into a room using a small ozone generator and a suspension of titanium oxide powder, which is a photocatalyst, is sprayed into the room.

Japanese Patent Application Laid-Open No. 2001-070416 JP 2006-026194 A JP-A-2005-329101

The method using ozone alone as described above may not be able to decompose a wide range of odorants. As a means for solving this problem, it is conceivable to supply ozone at a very high concentration for a long period of time. However, there is a possibility that it may have an adverse effect on the human body, or that indoor fixtures may easily rust.

Further, when the deodorizing devices described in Patent Document 1 and Patent Document 2 are used, the effect of the photocatalyst can be obtained only when the gas to be treated passes through the photocatalyst carrier. Even if a method using a photocatalyst is used in combination, it is not always possible to efficiently decompose a wide range of odorants. On the other hand, when the method described in Patent Document 3 is used, titanium oxide powder is sprayed into the room, so it is thought that the effect of the photocatalyst can be obtained everywhere in the room. However, according to a study by the inventors of the present invention, the method using ozone and titanium oxide described in Patent Document 3 could not decompose persistent odorous substances.

The present invention has been made to solve the above problems, and provides a deodorizing method capable of efficiently decomposing a wide range of odorants. Another object of the present invention is to provide a deodorizing apparatus capable of realizing such a deodorizing method.

The above problem is solved by a deodorizing method for deodorizing a target space or an object by supplying a gas containing ozone and a mist of a dispersion liquid of photocatalyst particles containing tungsten oxide to the target space or the object. solve.

As a result, a wide range of odorants can be efficiently decomposed. That is, although the details will be described later, by coexisting ozone and photocatalyst particles containing tungsten oxide, odorous substances that cannot be decomposed or can be decomposed only with low efficiency by ozone alone or photocatalyst particles alone can be efficiently decomposed. be able to

In the deodorizing method described above, the gas containing ozone and the mist of the dispersion liquid of the photocatalyst particles may be supplied separately. can also be supplied in a mixed state. As a result, the ozone and the photocatalyst particles can be supplied to the target space or object in a mixed state, so that the synergistic effect of the ozone and the photocatalyst particles described above can be easily obtained, and the deodorization can be performed evenly. can.

On the other hand, in the above-described deodorizing method, when the ozone-containing gas and the mist of the photocatalyst particle dispersion liquid are separately supplied, the photocatalyst particles are supplied before the ozone-containing gas is supplied. It is preferred to supply a mist of the dispersion. As a result, it is possible to efficiently deodorize while ensuring the safety of the operator. For example, for areas where odorous substances tend to adhere, such as the curtains in a room or the seat of a car, an operator enters the room or car and intensively supplies mist of the photocatalyst particle dispersion liquid. , more effective deodorization. However, since ozone is harmful to the human body, if the photocatalyst particles are supplied after the ozone-containing gas is supplied, the operator may not be able to safely supply the photocatalyst particles.

In the deodorizing method described above, the odorant to be deodorized is not particularly limited. However, when the odorant in the target space or object contains an aromatic compound, it is preferable to deodorize the target space or object by decomposing the aromatic compound. Among various malodorous substances, aromatic compounds are often persistent, although they are the cause of many malodors. By using the deodorizing method of the present invention, aromatic compounds can also be decomposed as described later.

The deodorizing method of the present invention includes, for example, an ozone generating unit that supplies an ozone-containing gas by generating ozone from oxygen molecules, and an ultrasonic atomization of a dispersion of photocatalyst particles to produce a dispersion of photocatalyst particles. It can be realized by a deodorizing device that includes an atomizing part that supplies mist, and that can mix and supply gas containing ozone and mist of the dispersion liquid of photocatalyst particles. Thereby, it is possible to deodorize the room more efficiently. This is because, by using the deodorizing device, ozone and photocatalyst particles can be supplied to the target space or object in a mixed state, so that a wide range of odorous substances can be uniformly decomposed. be.

As described above, the present invention makes it possible to provide a deodorizing method capable of efficiently decomposing a wide range of malodorous substances. Moreover, it is also possible to provide a deodorizing device capable of realizing such a deodorizing method.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a deodorizing device capable of implementing the deodorizing method of the present invention;

The deodorizing method of the present invention deodorizes a target space or an object by supplying a gas containing ozone and a mist of a dispersion liquid of photocatalyst particles containing tungsten oxide to the target space or the object. It is.

As a result, a wide range of odorants can be efficiently decomposed. That is, it is possible to efficiently decompose odorous substances that cannot be decomposed or can be decomposed only with low efficiency by ozone alone or photocatalyst particles alone. For example, when ozone alone is used for deodorization, aldehydes and substances contained in cigarette tar among the odorous substances are oxidized to produce carboxylic acid, but this carboxylic acid is resistant to oxidative decomposition by ozone. Therefore, it causes an acidic odor. Moreover, among odorous substances, many aromatic compounds are difficult to decompose. In this regard, the deodorizing method of the present invention is capable of decomposing a wide range of odorants including carboxylic acids and aromatic compounds through interaction between ozone and photocatalyst particles containing tungsten oxide.

The target space in the above deodorizing method means a space having a certain volume partitioned by walls or the like. Such spaces include, for example, the interiors of houses and vehicles. The deodorizing method described above can be suitably used to deodorize the interior of a hotel room, the interior of an automobile, or the like. In addition, the target object in the above deodorizing method refers to an article in the target space. Examples of these articles include interior goods such as wallpaper and car seats, and movable objects such as furniture and bedding. Although the material of the object is not particularly limited, the above-described deodorizing method can be preferably used when deodorizing the object formed of a material such as a fiber to which an odorant easily adheres. Examples of such objects include curtains and carpets. In the case of performing deodorizing treatment using the above deodorizing method, for example, a light source such as a fluorescent lamp, an LED lamp, or an incandescent lamp is used to illuminate the target space, or natural light is emitted from a window or the like to the target space. It is preferable that the light is incident on the target space or the target object, for example, because the effect of the photocatalyst can be promoted.

In the deodorizing method described above, the specific composition of the ozone-containing gas is not particularly limited as long as it is a gas containing ozone molecules in a gaseous state. The ozone-containing gas may be a gas composed almost exclusively of ozone, but is usually air containing ozone.

In the above deodorizing method, the supply method of the fog of the dispersion liquid of the photocatalyst particles containing tungsten oxide (hereinafter sometimes simply referred to as "photocatalyst particles") is not particularly limited. The mist of the dispersion of photocatalyst particles can also be supplied, for example, by atomizing the dispersion of photocatalyst particles using ultrasonic waves. In this case, the mist of the dispersion liquid of the photocatalyst particles can be evenly supplied to the target space, so that efficient and uniform deodorization can be performed. The mist of the photocatalyst particle dispersion can also be supplied by spraying the photocatalyst particle dispersion using a manual or electric spray device. In this case, since the mist of the dispersion liquid of the photocatalyst particles can be sprayed locally, it is possible to intensively deodorize the part of the object space or object where the odor is particularly noticeable.

The dispersion of photocatalyst particles is prepared by dispersing the photocatalyst particles in a liquid-phase dispersion medium. Although the composition of the dispersion medium is not particularly limited, it is preferably a solution mainly composed of water, alcohol, or a mixture thereof. Additives such as a dispersant and a preservative may be added to the dispersion medium. Examples of dispersants include various surfactants, salts, solvents, polymer compounds, and the like.

The amount of photocatalyst particles contained in the dispersion of photocatalyst particles is not particularly limited. However, if the amount of photocatalyst particles is too small, the deodorizing effect tends to be small. Therefore, the amount of photocatalyst particles contained in the dispersion liquid is preferably 0.001% (mass volume percent, hereinafter referred to as "w/v") or more, and is preferably 0.01% (w/v) or more. and more preferably 0.05% (w/v) or more. On the other hand, if the amount of photocatalyst particles contained in the dispersion is too large, the photocatalyst particles tend to precipitate in the dispersion. Therefore, the amount of photocatalyst particles contained in the dispersion is preferably 20% (w/v) or less, more preferably 10% (w/v) or less, and further preferably 5% (w/v) or less. preferable.

The specific composition of the photocatalyst particles containing tungsten oxide is not particularly limited as long as it is a particle group containing tungsten oxide particles. Tungsten oxide forming tungsten oxide particles is not particularly limited in terms of its oxidation _number and composition as long as it is a compound containing tungsten and oxygen as constituent elements. ₃ ). The tungsten oxide particles may be a mixture of two or more types of tungsten oxide particles having different oxidation numbers and compositions. The crystal structure of tungsten oxide is also not particularly limited.

Photocatalyst particles containing tungsten oxide may contain other photocatalyst particles in addition to tungsten oxide particles. Other photocatalyst particles include particles of titanium oxide, zinc oxide, zinc sulfide, cadmium sulfide, and the like. When titanium oxide particles are used, any of an anatase type, rutile type, and brookite type may be used, but the use of the anatase type is preferable because higher photocatalytic activity can be obtained. Tungsten oxide particles and other photocatalyst particles may carry a metal compound. Examples of such metal compounds include one or more metal compounds selected from the group consisting of titanium, platinum, iron, silver, copper, lead, nickel, rhodium, ruthenium and palladium.

The particle size of the tungsten oxide particles and other photocatalyst particles contained in the dispersion of photocatalyst particles is not particularly limited, but smaller ones are preferable. This is because if the particle diameter of the photocatalyst particles is made smaller, the residence time of the photocatalyst particles can be lengthened when the fog of the dispersion liquid of the photocatalyst particles is supplied to the target space. This is because it is possible to deodorize the In addition, since the specific surface area of the photocatalyst particles can be increased, it is also possible to effectively deodorize the target space and objects.

Therefore, the particle diameter of the photocatalyst particles is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. Although the lower limit of the particle size of the photocatalyst particles is not particularly limited, it is usually about 1 nm. The particle diameter of the photocatalyst particles is more preferably 3 nm or more, more preferably 5 nm or more. In Examples described later, photocatalyst particles having a particle diameter of about 7 nm are used.

In the above deodorizing method, the ozone-containing gas and the mist of the dispersion of the photocatalyst particles can be mixed and supplied to the target space or object. Examples of such a method include a method using a deodorizing device, which will be described later.

In the deodorizing method described above, the gas containing ozone and the mist of the photocatalyst particle dispersion can be separately supplied to the target space or object. In this case, there is no particular limitation as to which of the gas containing ozone and the fog of the dispersion liquid of the photocatalyst particles is supplied first, and they may be supplied at the same time. It is preferable from the safety point of view of the operator to supply the mist of the photocatalyst particle dispersion before supplying the .

The deodorizing method described above can decompose various odorous substances that cause odors. Such odorous substances include one or more organic compounds selected from the group consisting of various aromatic compounds, carboxylic acids, aldehydes, alcohols, esters, ethers, ketones, lactones, nitrogen compounds, sulfur compounds, chlorine compounds, and bromine compounds. Compounds and the like are exemplified. The deodorizing method described above is particularly capable of effectively decomposing aromatic compounds. Examples of such aromatic compounds include one or more compounds selected from the group consisting of benzene, styrene, toluene, xylene, phenol, cresol, naphthalene, indole, skatole, pyridine and derivatives thereof.

The above deodorizing method can be realized, for example, by using the deodorizing device 10 shown in FIG. This deodorizing device 10 includes an ozone generator 20 that supplies an ozone-containing gas by generating ozone from oxygen molecules, and an ozone generator 20 that atomizes a dispersion D of photocatalyst particles with ultrasonic waves to mist the dispersion of photocatalyst particles. and an atomizing section 30 for supplying the By using this deodorizing device 10, ozone and photocatalyst particles can be evenly supplied into the target space, and efficient and uniform deodorization can be performed. In addition, for example, the deodorizing process can be performed in an unattended state, which saves labor and prevents workers from being exposed to harmful ozone.

As long as the deodorizing device 10 includes the ozone generating section 20 and the atomizing section 30, there are no particular limitations on how these are combined. For example, the ozone generating unit 20 and the atomizing unit 30 are arranged in separate channels, and each channel is provided with an outlet leading to the outside of the apparatus, so that the ozone-containing gas and the mist of the photocatalyst particle dispersion are separated. You may make it supply separately. However, in the deodorizing device 10 shown in FIG. 1, the ozone generating section 20 and the atomizing section 30 are arranged in one flow path, and the ozone-containing gas and the mist of the photocatalyst particle dispersion liquid are mixed. I try to supply it in a state. That is, the air sucked from the air inlet 50 by the blower fan 40 passes through both the ozone generating section 20 and the atomizing section 30, and is released while containing both the ozone and the mist of the dispersion liquid of the photocatalyst particles. It is adapted to be discharged from the outlet 60 . As a result, the ozone and the photocatalyst particles can be supplied in a pre-mixed state, so that the interaction between the ozone and the photocatalyst particles can occur more easily, and a wide range of odorants can be uniformly decomposed. .

When the ozone generating section 20 and the atomizing section 30 are arranged in one flow path, there is no limitation on which of the ozone generating section 20 and the atomizing section 30 is arranged on the upstream side, but as shown in FIG. Moreover, it is preferable to arrange the ozone generating section 20 on the upstream side of the atomizing section 30 . This is because the gas flowing downstream of the atomizing section 30 may contain a large amount of water vapor generated by atomization of the dispersion D of photocatalyst particles, and ozone is generated in the gas containing a large amount of water vapor. If this is attempted, not only ozone but also OH radicals derived from water molecules will be generated, and the ozone generation efficiency will decrease.

The specific configuration of the ozone generator 20 is not particularly limited as long as it can generate ozone from oxygen molecules. Alternatively, the ozone generator 20 in the deodorizing apparatus 10 shown in FIG. 1 generates ozone by silent discharge, although it may be of a plasma type. Further, the supply method of oxygen molecules, which is the raw material of ozone, is not particularly limited, and concentrated oxygen supplied from a cylinder or the like may be used. In this case, ozone can be generated at a high concentration, so a higher deodorizing effect can be obtained. The ozone generator 20 in the deodorizing apparatus 10 shown in FIG. 1 generates ozone using oxygen molecules contained in the air sucked from the intake port 50 as a raw material. In this case, the device can be simplified and the cost can be kept low.

The specific configuration of the atomizing unit 30 is not particularly limited as long as it can atomize the dispersion D of photocatalyst particles by ultrasonic waves. In the deodorizing device 10 shown in FIG. 1, the atomizing section 30 is provided with an ultrasonic vibrator 31 at its bottom.

In addition to the above configuration, the deodorizing device 10 shown in FIG. 1 also includes a photocatalyst filter 70 formed by supporting a photocatalyst on a carrier. Thereby, deodorizing treatment can be performed more effectively. In the deodorizing device 10 shown in FIG. 1, the photocatalyst filter 70 is installed on the upstream side of the blower fan 40, that is, immediately after the intake port 50. As shown in FIG. However, there is no particular limitation as to where the photocatalyst filter 70 is installed in the flow path of the deodorizing device 10. Alternatively, it may be installed downstream of the atomizing section 30 .

The structure of the carrier of the photocatalyst filter 70 is not particularly limited as long as it allows gas to pass through while supporting the photocatalyst, but a porous structure is preferable. Such structures include, for example, a honeycomb structure, a mesh structure, a sponge structure, a non-woven fabric-like structure, and the like. The material of the carrier of the photocatalyst filter 70 is also not particularly limited, and may be ceramics, metal, resin, glass fiber, or the like. The type of the photocatalyst supported on the photocatalyst filter 70 is not particularly limited, and may be titanium dioxide, tungsten trioxide, tungsten dioxide, zinc oxide, zinc sulfide, cadmium sulfide, or a mixture thereof. can.

When the deodorizing device 10 is provided with the photocatalytic filter 70, it is preferable to expose the photocatalytic filter 70 to light at least while the deodorizing device 10 is in use, because the effect of the photocatalyst can be promoted. Therefore, the deodorizing device 10 may further include a light source (not shown) for illuminating the photocatalyst filter 70 . As a light source, for example, a fluorescent lamp, an LED lamp, an incandescent lamp, an ultraviolet lamp, or the like can be used. As another aspect, when the photocatalyst filter 70 is arranged at the upstream end or the downstream end of the flow path of the deodorizing device 10, the photocatalyst filter 70 is exposed to the outside of the device, and the light in the target space hits the photocatalyst filter 70. You can also make

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

In this embodiment, the odorous substance to be treated (hereinafter sometimes referred to as the "target substance") is preliminarily present in the target space, and the treatment methods 1 to 8 described later are applied to the target space. The target space was deodorized by applying any deodorizing treatment. Evaluation of the deodorizing effect was carried out by examining the treatment rate of the target substance.

[Target space and target substance]
The inside of a 45 L desiccator was used as the target space. As the target substance, in Example 1, acetic acid was used as an example of a carboxylic acid, and in Example 2, benzene was used as an example of an aromatic compound. These target substances are vaporized in a separate container at room temperature to a saturated state, and the gas in this separate container is sucked with a syringe and injected into the desiccator to obtain the gaseous state in the desiccator. made to exist within.

[Deodorizing treatment]
The deodorizing treatment was performed by applying any one of the following treatment methods 1 to 8 to the target space in which the target substance was present. The treatment time was 30 minutes.
(1) Treatment method 1
0.36 ml of distilled water was sprayed into the target space using a manual spray device.
(2) Treatment method 2
A silent discharge ozone generator previously installed in the target space was started to supply ozone into the target space. The total amount of ozone supplied within the treatment time was 11.5 mg (the same applies to treatment methods 4, 6 and 8 below).
(3) Treatment method 3
0.36 ml of 1% (w/v) titanium dioxide particle dispersion was sprayed into the target space using a manual spray device.
(4) Treatment method 4
At the same time as starting a silent discharge ozone generator previously installed in the target space, 0.36 ml of a 1% (w/v) titanium dioxide particle dispersion was sprayed into the target space using a manual spray device. was sprayed on.
(5) Treatment method 5
0.45 ml of 0.1% (w/v) tungsten trioxide particle dispersion was sprayed into the target space using a manual spray device.
(6) Treatment method 6
A silent discharge ozone generator previously installed in the target space was started, and at the same time, 0.45 ml of a 0.1% (w/v) tungsten trioxide particle dispersion was sprayed using a manual spray device. Sprayed into the target space.
(7) Treatment method 7
0.45 ml of 0.1% (w/v) tungsten dioxide particle dispersion was sprayed into the target space using a manual spray device.
(8) Treatment method 8
At the same time as starting a silent discharge ozone generator previously installed in the target space, 0.45 ml of 0.1% (w / v) tungsten dioxide particle dispersion was applied to the target using a manual spray device. sprayed into the space.

[Evaluation method]
The deodorizing effect was evaluated by measuring the air concentration of the target substance in the desiccator before and after the deodorizing treatment, and calculating the treatment rate (%) of the target substance. The concentration of the target substance in air was measured by attaching a detection tube to a gas sampling device "MODEL801" manufactured by Gastech. A detector tube "#81L" manufactured by the same company was used to measure the concentration of acetic acid, and a detector tube "#121L" manufactured by the same company was used to measure the concentration of benzene. If the processing rate is less than 10%, it is judged as “×”, if it is 10% or more and less than 50%, it is judged as “△”, if it is 50% or more and less than 90%, it is judged as “○”, and if it is 90% or more, it is judged as “◎” bottom.

[Example 1]
Each of the treatment methods 1 to 8 was applied to the inner space of the desiccator containing about 3.77 to 9.00 ppm of acetic acid, and the deodorizing effect was evaluated. Table 1 shows the results obtained. When ozone was supplied to the target space (Test Example 2), acetic acid was hardly decomposed, whereas when mist of the photocatalyst particle dispersion was supplied to the target space (Test Examples 3, 5, and 7). , and when the fog of the photocatalyst particle dispersion and ozone were supplied (Test Examples 4, 6, and 8), acetic acid was almost completely decomposed. In addition, when distilled water was supplied to the target space (Test Example 1), a decrease in the acetic acid concentration was also observed. This is probably because the concentration of acetic acid in the air decreased due to partial dissolution in the acetic acid.

From this, it was shown that [1] it is difficult to decompose carboxylic acid by treatment with ozone alone, and [2] carboxylic acid can be efficiently decomposed by treatment with photocatalyst particles regardless of the presence or absence of ozone.

[Example 2]
Each of the treatment methods 1 to 8 was applied to the inner space of the desiccator containing about 2.50 to 3.67 ppm of benzene, and the deodorizing effect was evaluated. Table 2 shows the results obtained. When distilled water (Test Example 9) or ozone (Test Example 10) was supplied to the target space, benzene was hardly decomposed. In addition, the decomposition of benzene was confirmed in the case of supplying the mist of the titanium dioxide particle dispersion to the target space (Test Example 11), and also in the case of supplying the mist of the titanium dioxide particle dispersion and ozone (Test Example 12). it wasn't. On the other hand, when mist of the tungsten trioxide particle dispersion was supplied to the target space (Test Example 13), benzene was hardly decomposed, but the mist of the tungsten trioxide particle dispersion and ozone were supplied to the target space. In the case (test example 14), about 57% of benzene was decomposed. Further, when fog of tungsten dioxide particle dispersion was supplied to the target space (Test Example 15), about 28% of benzene was decomposed, and when fog of tungsten dioxide particle dispersion and ozone were supplied to the target space, In (Test Example 16), about 67% of benzene was decomposed.

From this, [1] it is difficult to decompose aromatic compounds by treatment with ozone alone, [2] it is difficult to decompose aromatic compounds by treatment with titanium dioxide particles regardless of the presence or absence of ozone, [3] It is difficult for tungsten oxide particles to decompose aromatic compounds by themselves, but they can decompose aromatic compounds by coexisting with ozone. [4] Tungsten dioxide particles can decompose aromatic compounds by themselves. It was shown that aromatic compounds can be decomposed more efficiently by coexisting with ozone.

[Example 3]
Using the deodorizing apparatus shown in FIG. 1, the same deodorizing experiments as in Test Examples 6, 8, 14, and 16 were carried out with the target space being the room of a house (volume of about 30 m ³ ). As a result, ozone and photocatalyst particles were evenly supplied into the room, and odorous substances including carboxylic acid and aromatic compounds could be decomposed.

REFERENCE SIGNS LIST 10 deodorizing device 20 ozone generating section 30 atomizing section 31 ultrasonic transducer 40 blower fan 50 intake port 60 discharge port 70 photocatalyst filter D dispersion of photocatalyst particles

Claims (1)

A deodorizing method for deodorizing a target space or an object by supplying a gas containing ozone and a mist of a dispersion liquid of photocatalyst particles containing tungsten oxide to the target space or the object,
For locations in the target space where odorous substances tend to adhere, an operator enters the target space and supplies mist of the photocatalyst particle dispersion liquid to the location , and then sprays the ozone-containing gas into the target space. supply to
The deodorizing method, wherein the odorant in the target space or object contains an aromatic compound, and the target space or object is deodorized by decomposing the aromatic compound .

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