JPH08304378A - Ozone decomposing equipment, and ultraviolet ray absorbing type ozone gauge - Google Patents

Abstract

PURPOSE: To provide an ozone decomposing unit capable of supplying a sample gas in which ozone is specifically decomposed by arranging a metal compound having reduction type optical responding semiconductor characteristic in the state where the sample gas can make contact. CONSTITUTION: A member 12 containing a metal compound having reduction type optical responding semiconductor characteristic is filled in the hollow member 11 of an ozone decomposing unit 10. The hollow member 11 is filled with a sample gas introduced from a sample gas inlet port 13. The exciting light for the metal compound having reduction type optical responding semiconductor characteristic of the member 12 is emitted from an exciting light source 14 toward the member 12. The ozone in the sample gas is reduced and decomposed by free electrons generated by the excitation of the metal compound by the emission of the exciting light. After reduction and decomposition, the sample gas in which the ozone was decomposed is collected from a sample gas outlet port 13'. The material of the hollow member 11 is not particularly limited, if it has such an airtightness that the replacement of the internal and external materials can be prevented, and transmits the exciting light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone decomposing unit using a photocatalyst, an ozone decomposing unit, and an ultraviolet absorption type ozone meter using this ozone decomposing unit. More specifically, this UV absorption type ozone meter is based on the difference in UV absorbance between the sample gas ozone decomposed by the ozone decomposer including the ozone decomposition unit using a photocatalyst and the sample gas not ozone decomposed. The present invention relates to an ultraviolet absorption type ozone meter for obtaining the ozone concentration in this sample gas.

[0002]

Background Art Ozone in the environment plays a very important role in the high-altitude ozone layer to protect organisms on the surface of the earth from strong UV exposure from the sun, while it is the main cause of photochemical oxidants that cause photochemical smog. It has the aspect of being a component. Further, it is known that ozone generated from a high energy-using device such as an accelerator, an ultraviolet spectroscope, an X-ray device and an arc welding has a harmful effect on the health of a worker working around the device. From such a point of view, it is extremely important to accurately measure the ozone concentration in the environment, and at present, the ozone concentration is measured by various methods.

Among them, the measurement of the ozone concentration in the sample gas of the ultraviolet absorption method is one of the most popular measurement methods. The measurement of ozone concentration in sample gas by this ultraviolet absorption method is based on the fact that ultraviolet rays of a specific wavelength are absorbed by ozone and the absorption rate is proportional to the ozone concentration. NO _X , SO
_There are many gas components having an absorption band for ultraviolet rays such as _X and hydrocarbons, and the effect of these coexisting gases on the ozone concentration has respective characteristics depending on the source and origin of the gas. Further, when moisture in the atmosphere of the sample gas adheres to the surface of the ultraviolet absorbing cell, the refractive index of the cell changes, and substantially the same action as that in which this moisture absorbs ultraviolet rays appears.

An ozone meter for measuring ozone concentration by the above-mentioned ultraviolet absorption method usually comprises an ozone decomposer and an ultraviolet absorption measuring section, and the ultraviolet absorption of the sample gas passing through this ozone decomposer and this ozone. The ultraviolet absorption of the sample gas that does not pass through the decomposer is measured by the ultraviolet absorption measuring section, and the ozone concentration in the sample gas is determined from the difference between these two ultraviolet absorptions.
The shorter the switching time from the state where the sample gas is passing through the ozone decomposing unit to the state where it is not passing, the better, but if it is too short, the inside of the UV absorbance measurement unit will be changed depending on the flow rate when the sample gas is introduced at a constant flow rate by the pump. After the change to the sample gas before the sample gas is not full, the next sample gas will flow in and cause a measurement error, and the number of times the sample gas inflow direction switching unit operates per unit time increases, resulting in an ozone meter. The actual life is 10
It is common to switch every 12 seconds.

As described above, since the ozone meter uses a single ultraviolet ray absorbance measuring section, the cell and the mirror are dirty, the power source voltage of the ultraviolet ray lamp is changed, the light quantity is changed with time, and the ambient temperature is changed. It is possible to always perform measurement under the same conditions regardless of changes in the performance of the device due to factors such as the above, and it is also possible to perform highly sensitive measurement. The performance of the ozone decomposer is extremely important for strictly measuring the ozone concentration by the ultraviolet absorption method. And this ozone decomposer surely decomposes only ozone contained in the sample gas,
Ideally, other coexisting components having absorption of ultraviolet rays and moisture should not be changed at all.

[0006]

If the ozone decomposing unit is ideal, a compound having an absorption wavelength band for ultraviolet rays having the same wavelength coexisting in the atmosphere, such as toluene or xylene, is derived from automobile exhaust gas. The ozone decomposer does not decompose these aromatic hydrocarbons even if they exist. Therefore, according to the principle of the ultraviolet absorption type ozone meter described above, there should be no influence on the measurement. Aiming at the development of such an ideal ozonolysis device, various ozonolysis devices have been devised and used, focusing on the function of manganese dioxide as an ozone decomposition catalyst.

However, this manganese dioxide contains
It cannot be denied that there are many problems in using it as an ozone decomposition catalyst. The problems are listed below. (1) Short lifespan Manganese dioxide is easy to use because it can be supported on a carrier by an electrolytic method or the like, but it gradually deteriorates due to long-term contact with ozone, and the decomposition rate of ozone decreases over time. There is a problem of going. That is, the reaction between ozone and manganese dioxide is a chemical reaction accompanied by modification of the crystal structure itself of manganese dioxide.

(2) Influence of moisture, hydrocarbons, or dust In order to improve the ozone decomposability of manganese dioxide,
It is necessary to support fine particles of manganese dioxide on a porous material or a reticulated material having a large surface area by a chemical conversion method or an electrolytic method, and stack them to form a catalyst probe. In this case, in order to prevent manganese dioxide from decomposing xylene and toluene coexisting in the atmosphere to give a positive interference, the amount of catalyst supported and the structure of the probe are devised. However, nevertheless, when a high concentration of hydrocarbon gas coexists with ozone, it still has not escaped its strong positive interference.

As described above, generally, in the ultraviolet absorption type ozone meter, the ultraviolet rays when the sample gas passes through the path that passes through the ozone decomposing section and when the sample gas passes through the path that does not pass through the ozone decomposing section. Measure the difference in absorbance. At this time, moisture or dust mixed in the sample gas is trapped in some form in the route while reaching the ultraviolet absorption measuring section, and the route passing through the ozone decomposing section at the time when reaching the ultraviolet absorbing measurement section is passed through the sample gas. When the sample gas passes through the path that does not pass through the ozone decomposing section and the dust concentration is different, there is a difference in the degree of UV absorption in the UV absorbance measuring section, which may interfere with ozone measurement. Is not preferable. And this interference becomes large, so that the structure of the ozone decomposition unit used is complicated.
The effect of moisture can be removed to some extent by heating the ozone decomposition probe, but it is extremely difficult to take measures against the effect of dust.

[0010]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems. As a result, in principle, the photocatalyst, which is a catalyst that uses the light energy from the outside as a driving force, has almost no fluctuation in its catalytic effect as long as the light energy from the outside is continuously given. It was found that the above problems can be solved by making the most of the excellent photocatalyst characteristics in the ultraviolet absorption type ozone meter. That is, the present inventor provides the following inventions.

In claim 1, a sample gas inflow port is provided at one end of the airtight hollow member, and a sample gas outflow port is provided at the other end, and the sample gas inflow port is introduced into the inside of the hollow member. An ozone decomposing unit is characterized in that a metal compound having reduced photoresponsive semiconductor characteristics is arranged in such a manner that the sample gas can come into contact therewith.

According to a second aspect of the present invention, the fine particles of a metal compound having a reduced photoresponsive semiconductor property are arranged inside an airtight hollow member dispersed in an ion exchanger. An ozonolysis unit according to item 1 is provided.

According to a third aspect of the present invention, the material of the airtight hollow member is an ion exchanger, and fine particles of a metal compound having reduced photoresponsive semiconductor properties are dispersed on the inner wall of the hollow member. An ozonolysis unit according to claim 1 is provided.

According to a fourth aspect of the present invention, there is provided the ozone decomposing unit according to any one of the first to third aspects, wherein the metal compound having reduced photoresponsive semiconductor characteristics is titanium oxide.

The invention according to claim 5 is characterized in that a metal ion or a metal is supported in the vicinity of a metal compound having a reduced photoresponsive semiconductor property. Provided is the described ozonolysis unit.

In claim 6, claim 1 to claim 5
A combination of the ozone decomposing unit according to any one of claims 1 to 5 and a light source for irradiating excitation light toward a metal compound having reduced photoresponsive semiconductor characteristics, which is arranged in the ozone decomposing unit. Provide an ozonolysis device that does.

In claim 7, an ozone decomposing unit and an ultraviolet absorption measuring unit are provided, and the ultraviolet absorption of the sample gas that has passed through the ozone decomposing unit and the ultraviolet absorption of the sample gas that does not pass through the ozone decomposing unit are set. In the ultraviolet absorption type ozone meter for measuring the ozone concentration in the sample gas from the difference between the two UV absorbances, the ozone decomposer is the ozone decomposer according to claim 6. An ultraviolet absorption type ozone meter is provided.

In the ultraviolet absorption ozonometer according to claim 8, which comprises an ozone decomposer and an ultraviolet absorption measuring section, the ozone decomposer is the ozone decomposer according to claim 6, and the ozone decomposer is the ozone decomposer. The UV absorbance of the sample gas that has passed is measured by the UV absorbance measuring unit in each of the cases where the metal compound according to claim 6 is irradiated with excitation light and the case where the metal compound is not irradiated with excitation light. Provided is an ultraviolet absorption type ozone meter, which is characterized in that the ozone concentration in gas is obtained.

The present invention will be described in detail below. One of the major features of the present invention is to use a so-called photocatalyst using a metal compound having a reduced photoresponsive semiconductor property as a means for decomposing ozone in a sample gas. Therefore, the photocatalyst used in the present invention will be described first, and then the ozone decomposing unit, the ozone decomposing unit, and the ultraviolet absorption type ozone meter of the present invention using the photocatalyst will be described.

The term "photocatalyst" generally means a substance which, when irradiated with excitation light, is excited by its light energy to exert a catalytic action or promote this catalytic action. A “metal compound having photoresponsive semiconductor properties” is, for example, an n-type compound such as titanium oxide when it absorbs light having an energy equal to or more than a “forbidden band” which is an energy gap between a valence band and a conduction band in its crystal molecule. In a metal compound having semiconductor characteristics, electrons in the valence band are excited in the conduction band, and the electrons involved in the bond in the crystal gain energy to move in the crystal as free electrons not involved in the bond. On the other hand, at the place where this electron escapes, the valence electrons involved in the bond are insufficient, and positively charged holes are generated. Then, these free electrons and / or holes mediate various catalytic actions on the reaction target.

In the present invention, among the above metal compounds, "a metal compound having a reduced photoresponsive semiconductor property" which exhibits an action of promoting ozone decomposition by photoexcitation, that is, an action of promoting reduction of ozone is used. It is characterized by using a photocatalyst as an ozone decomposing means. Specifically, the metal compound used in the present invention is highly preferable as a means for supporting the metal compound on a carrier,
So-called "sol-gel method" (mainly in the form of a solution, a metal alkoxide is hydrolyzed and polycondensed in the solution to cause the sol to gel and solidify to form an oxide solid of the metal. The method for preparing: A metal oxide to which a specific method will be applied) is preferably selected. Specific examples include titanium oxide, tin dioxide, tungsten oxide, strontium titanium oxide, and ferric trioxide. Among these metal oxides, titanium oxide has a property that the forbidden band value is relatively low, about 3 eV, and it has a characteristic that free electrons can be generated even by irradiation with relatively mild near-ultraviolet rays of about 400 nm or less. It is particularly preferable in terms of points.

Further, in the present invention, the photocatalyst in which the above metal compound is dispersed in an ion exchanger has photoresponsive semiconductor characteristics by using an ion exchange group highly dispersed in the ion exchanger as an active site. It is possible to generate fine particles of a metal compound by a chemical method, and a metal ion for producing a so-called combined effect, or at the time of supporting a metal, the metal ion due to the presence of an ion exchange group in the ion exchanger, or It is possible to support the metal in a highly dispersed state;

The ion exchanger selected in consideration of these purposes is a strong acidic cation in consideration of improvement of metal compound, metal ion, and / or metal loading efficiency having reduced photoresponsive semiconductor characteristics. It is preferable to select an exchanger or a strongly basic anion exchanger as the ion exchanger.

Further, considering that the properties of the photocatalyst to be produced may be influenced by the shape of the ion exchanger as the carrier, it is preferable to select an ion exchanger which can be easily molded into various shapes. In particular, an ion exchanger having a light-transmitting property when formed into a film shape is used for manufacturing an ozone decomposer in which an ozone decomposition unit using a hollow tubular ion exchanger described later and an excitation light source are integrated. It is an essential material.

Of course, the above-mentioned ion exchanger can take the form of, for example, an ion exchange resin in addition to the form of the ion exchange membrane. Further, their shape is not particularly limited, and in the case of an ion exchange membrane, in addition to the above hollow tube, a sheet shape, a bag shape, etc., and in the case of an ion exchange resin, a bead shape, a column shape, etc. The form can be appropriately selected according to the mode of the ozone decomposition unit of the present invention.

In general, the larger the surface area of the ion exchanger serving as a carrier, the larger the amount of the metal compound having photoresponsive semiconductor characteristics to be carried per the amount of the ion exchanger, which can improve the catalytic efficiency. Therefore, it is presumed that it is preferable to select a porous ion exchanger having small pores even in a dry state, or a high porous ion exchanger having a particularly large number of small pores, rather than an ion exchanger having no small pores. It

Considering the properties that the ion exchanger should have in the present invention, as a specific example of the ion exchanger that is preferably selected in the present invention, for example, a styrene-vinylbenzene copolymer is used as a base material in the third dimension. Specific examples thereof include an ion exchanger having an ion exchange group such as a sulfonic acid group and an ion exchanger containing a fluoropolymer as a base material. However, these ion exchangers are merely examples, and it goes without saying that the ion exchanger applicable in the present invention is not limited thereto.

Among the above-exemplified ion exchangers, a particularly preferable ion exchanger to be selected in the present invention is a strongly acidic cation exchanger containing a fluoropolymer as a base material (specific example is perfluoro). Nafion (DuPont: registered trademark), which is a cation exchanger having an alkane sulfone residue, or a strongly basic anion exchanger (a anion having a quaternary ammonium salt group) containing a fluoropolymer as a base material. IE-SA48-5, which is an exchanger
(Manufactured by Tosoh Corporation)) and the like.

That is, since these ion exchangers are strongly acidic cation exchangers or strongly basic anion exchangers, it is of course easy to support metal ions or metals, and of course fluorine Like a polymer, it can be freely formed into a film or a hollow film. Furthermore, the materials of these ion exchangers are almost transparent and have excellent light transmittance.
That is, when the above ion exchanger is applied to an ozone decomposing unit molded into a hollow tube, it is excellent in reaching efficiency of excitation light to a metal compound having reduced photoresponsive semiconductor characteristics dispersed on the inner wall of the hollow tube. , Which is preferable.

Further, as described above, in the present invention, a photocatalyst in which a metal ion is supported on an ion exchanger can be preferably applied. That is, by supporting a metal ion in the vicinity of the above-mentioned metal compound having photoresponsive semiconductor properties, a photocatalyst having further improved reducing properties can be produced and applied to the present invention.

The metal ion that can be supported can be appropriately selected according to the type of metal compound having photoresponsive semiconductor characteristics used as the main body of the photocatalyst, and is not particularly limited. Specifically, a metal ion such as copper ion, iron ion, cobalt ion, silver ion, nickel ion, gold ion, platinum ion, palladium ion, or rhodium ion, or a combination of two or more of these metal ions is used. It can be supported.

The above metal ions are
It is not always one type, but for example, if it is iron ion, iron (I
It means both I) ions and iron (III) ions. Further, the metal ion in the present invention is not necessarily limited to the ion of a simple metal, but also includes an ion in the form of a metal-containing ionic compound having various forms of charge.

In particular, in the case of supporting a metal ion on an anion exchange resin, it is easy and preferable to support a metal ion anion instead of a carrier metal ion which is usually in the form of a cation. For example, if it is a gold ion, a chloro gold ion etc. can be mentioned as said metal ion anion.

As a method for supporting these metal ions, a generally known method can be used. For example, a supporting method in which the compound containing the metal ion is brought into direct contact with the ion exchange resin is easy and preferable. In this supporting method, for example, in the case of supporting a metal ion on a cation exchange resin, an aqueous solution of this cation salt can be used.

Specifically, copper ions are copper sulfate or the like; silver ions are silver nitrate or the like; gold ions are gold (I) chloride or the like; platinum ions are platinum chloride. An aqueous solution of a metal salt such as can be used. In addition, for example, when a metal ion is supported on an anion exchange resin, a compound containing a supported metal anion can be used. For example, as long as it is a gold ion, a compound containing a metal anion such as gold (III) chloride acid can be used.

The amount of the compound containing the metal ion, that is, the concentration of the aqueous solution of the metal salt or the like can be appropriately adjusted as desired and is not particularly limited, but it is not limited to all ion-exchange groups of the ion-exchanger used. It is preferable to use an amount sufficient to support the metal ions. In particular,
It is preferable to use an aqueous solution containing a metal salt or the like at a concentration of about 1% by weight or more and about 10% by weight or less with respect to the total amount of the aqueous solution. By thus supporting the metal ions on the ion exchanger, the reduction-type photocatalytic reaction can be further improved.

Furthermore, as described above, in the present invention, a photocatalyst in which a metal is supported on an ion exchanger can be preferably applied. The metal that can be supported is based on the above metal ions. As a method for supporting this metal in the photocatalyst of the present invention, a generally known method can be used. In particular, it is preferable to adopt a method of oxidizing or reducing the metal ion of the metal ion-supporting photocatalyst produced according to the above description to a metal form, because the stability of supporting the finely divided metal is excellent. However, it is also possible to support the desired metal on the ion exchanger by other commonly known methods such as a mixing method and an impregnation method.

The present invention provides the ozone decomposing unit in which the above-mentioned "metal compound having a reducing photoresponsive semiconductor property to be arranged in a hollow member having airtightness" is arranged.
The present invention also provides an ozone decomposing device in which this is combined with an excitation light source, and an ultraviolet absorption type ozone meter using this ozone decomposing device. Hereinafter, the operation of the ozone decomposing unit, the ozone decomposing device, and the ultraviolet absorption type ozone meter will be described, and specific embodiments thereof will be disclosed in Examples described later.

[0039]

[Action]

<Operation of Ozone Decomposing Unit> In the ozone decomposing unit according to claim 1, the sample gas flows from the sample gas inlet provided at one end of the airtight hollow member and the sample gas flowing at the other end. Outflow from the exit. During this period, the sample gas comes into contact with the metal compound having a reduced photoresponsive semiconductor property disposed inside the hollow member, so that when the metal compound is excited by light, the catalytic action of the metal compound is generated. This decomposes ozone in the sample gas.

Also in the ozone decomposing unit according to claim 2, the sample gas flows in from the sample gas inlet provided at one end of the airtight hollow member and flows out from the sample gas outlet provided at the other end. To do. During this period, the sample gas is an ion exchanger in which a metal compound having reduced-type photo-semiconductor properties disposed inside the hollow member is dispersed (the significance of dispersing the metal compound in the ion exchanger is described above).
When the metal compound is excited by light, ozone in the sample gas is decomposed by the catalytic action of the metal compound.

In the ozonolysis unit according to claim 3,
A sample gas flows in from a sample gas inlet provided at one end of a hollow member made of an ion exchanger and flows out from a sample gas outlet provided at the other end. During this period, the sample gas comes into contact with the metal compound having the reduced photoresponsive semiconductor characteristics dispersed in the inner wall of the ion exchanger forming the hollow member, and therefore, when the metal compound is excited by light, The ozone in the sample gas is decomposed by the catalytic action of this metal compound.

Also in the ozone decomposing unit according to claim 4, the sample gas flows in from the sample gas inlet provided at one end of the airtight hollow member and flows out from the sample gas outlet provided at the other end. To do. During this time, since the sample gas comes into contact with titanium oxide, which is a metal compound having reduced photoresponsive semiconductor properties, which is disposed inside the hollow member,
When the titanium oxide is excited by light, ozone in the sample gas is decomposed by the catalytic action of the titanium oxide.

Also in the ozone decomposing unit according to claim 5, the sample gas flows in from the sample gas inlet provided at one end of the airtight hollow member and flows out from the sample gas outlet provided at the other end. To do. During this period, the sample gas comes into contact with the metal compound having a reduced photoresponsive semiconductor property disposed inside the hollow member, and therefore, when the metal compound is excited by light, the sample gas is generated in the vicinity of the metal compound. Ozone in the sample gas is decomposed by the supported metal ion or the catalytic action of the metal compound improved by the metal (the significance of supporting the metal ion or the metal has been described above).

<Operation of Ozone Decomposing Device> An ozone decomposing device according to a sixth aspect is directed to the metal compound having a reduced photoresponsive semiconductor property according to any one of the first to fifth aspects. By irradiating excitation light from the combined excitation light source, the metal compound is excited and ozone in the sample gas is decomposed.

<Operation of UV Absorption Ozone Meter> Claim 7
In the ultraviolet absorptive ozone meter described above, when the sample gas passes through the ozone decomposer according to claim 6, the ozone gas is decomposed by the action of the ozone decomposer and the sample gas disappears into the ultraviolet absorptiometer. The sample is provided for measurement of the ultraviolet absorption of the sample gas. Then, the ozone concentration in the sample gas can be specified by obtaining the difference between the ultraviolet absorbance of the sample gas that does not pass through the ozone decomposer and the ultraviolet absorbance.

In the ultraviolet absorption type ozone meter according to the eighth aspect, the sample gas is passed through the ozone decomposer according to the sixth aspect, in which the excitation light is irradiated toward the metal compound having the reduced photoresponsive semiconductor characteristics. By doing so, the sample gas in which only ozone is decomposed and disappeared by the action of the ozone decomposer is provided to the ultraviolet absorption measuring instrument. Then, when the sample gas is passed through the ozone decomposing device according to claim 6 which is not irradiated with the excitation light, the ozone is not decomposed and the sample gas is directly provided to the ultraviolet absorption measuring device. The ozone concentration in the sample gas can be specified by measuring the ultraviolet absorbance of each of these with an ultraviolet absorbance measuring device and determining the difference between the ultraviolet absorbances of the two.

[0047]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the technical scope of the present invention should not be limitedly interpreted by these examples. [Example 1] Ozone decomposition unit and ozone decomposer 1. FIG. 1A shows an embodiment 1 of the ozonolysis device of the present invention.
FIG. In FIG. 1 (A), 11 is an airtight hollow member. Reference numeral 12 is a member containing a metal compound having reduced photoresponsive semiconductor characteristics. Reference numeral 13 is a sample gas inflow port, and 13 'is a sample gas outflow port. Reference numeral 14 is a light source for exciting a metal compound having reduced photoresponsive semiconductor characteristics.

A member 12 containing a metal compound having reduced photoresponsive semiconductor properties in a hollow member 11 having airtightness.
Is provided, a sample gas inlet 13 is provided at one end of the hollow member 11, and a sample gas outlet 13 ′ is provided at the other end, which constitutes an embodiment of the ozone decomposing unit of the present invention. Then, the light source 14 for exciting a metal compound having a reduced photoresponsive semiconductor property is separately and independently combined with the ozone decomposing unit of the present invention to form an embodiment 10 of the ozone decomposing device of the present invention.

First, the inside of the airtight hollow member 11 is filled with the sample gas flowing from the sample gas inlet 13. At this time, the excitation light of the metal compound having the reduced photoresponsive semiconductor characteristic in the member 12 is irradiated from the excitation light source 14 toward the member 12. By this excitation light irradiation, ozone in the sample gas is reductively decomposed by free electrons generated as a result of the excitation of the metal compound. After such reductive decomposition, the ozone decomposed sample gas can be collected from the sample gas outlet.

Here, the material of the airtight hollow member 11 has such airtightness that the exchange of the substance inside and outside the member can be cut off, and the excitation light of the metal compound is transmitted. There is no particular limitation as long as it is a material that can be used. For example, glass, quartz, an ion exchanger having a light-transmitting property in the form of a film, or the like can be used as the above-mentioned material (as well as the material of the light-transmitting container 21 of another embodiment 20 of the ion exchanger of the present invention described later). The same).

The material, shape and the like are not particularly limited as long as the member 12 containing a metal compound having reduced photoresponsive semiconductor properties and the embodiment in which the metal compound should exhibit the properties as a photocatalyst. For example, it is possible to use a piece of paper carrying this metal compound, it is also possible to use a porous member such as porous glass as a carrier for this metal compound, and it is also possible to use an ion exchanger as a carrier. It is possible. However, it is particularly preferable to use the member 12 in which an ion exchanger is prepared as a carrier for the metal compound (the reason for this is described above). Note that, in addition to the ion exchanger of the present invention described later, the material, shape, and other aspects of the member 24 of Embodiment 20 are the same as those of the member 12.

2. In one embodiment of the ozone decomposing unit of the present invention, the ozone decomposing unit and the excitation light source 14 are configured separately, but the metal compound in the ozone decomposing unit can be excited by this exciting light. In this mode, the ozone decomposition unit and the excitation light source are attached to each other,
Alternatively, they may be combined in a detachable manner.

FIG. 1B is a schematic view showing an embodiment 20 of the ozonolysis device of this embodiment. In FIG. 1 (B), a light source 25 for excitation is fitted into a through-hole 22 which is oriented in the length direction of a hollow light-transmissive container 21 having a sealed double structure. Further, the sample gas inflow port 2 is provided at both ends in the length direction of the hollow light-transmitting container 21.
3 and the same outlet 23 'are provided, and this container 2
1 is filled with a member 24 carrying a metal compound having a reduced photoresponsive semiconductor activity, and the above-mentioned 2. One embodiment of the ozone decomposer corresponding to the above is constructed.

When the excitation light source 25 is removed from the through hole, another embodiment of the ozone decomposing unit corresponding to the ozone decomposing device 10 is constructed. In the ozone decomposer 20, the hollow light-transmissive container 21 is filled with the sample gas introduced through the sample gas inlet 23. At this time, the excitation light of the metal compound having the reduced photoresponsive semiconductor characteristics in the member 24 is emitted from the excitation light source 25 to the member 2.
Irradiate toward 5. By this excitation light irradiation, ozone in the sample gas is reductively decomposed by free electrons generated as a result of the excitation of the metal compound. After this reductive decomposition, the ozone decomposed sample gas can be collected from the sample gas outlet 23 '.

In this embodiment, the excitation light source 25 and the hollow light-transmitting container 21 and the like are integrally combined to form the ozone decomposer 20, and therefore the excitation light source 25 and the member 24. The positional relationship can be easily made constant, and the setting for making the excitation light from the excitation light source 25 stably reach the metal compound having the reduced photoresponsive semiconductor characteristics in the member 24 is simple. That is advantageous. In addition, a hollow transparent container 2
When selecting a material that is durable against corrosion such as quartz or glass as the material of 1, the ozone decomposing unit 20
Is particularly advantageous when used for a long period of time.

3. FIG. 1C is a schematic view showing another embodiment of the ozone decomposition unit of the present invention. Figure 1 (C)
In the ozone decomposing unit 30, a hollow tubular ozone decomposing unit 32 made of an ion exchanger having a light transmissive property in a film form is wound around the excitation light source 31.

In the present embodiment, the sample gas is passed through the hollow tubular ozone decomposition unit 32 from the upstream side, and the excitation light is emitted from the excitation light source 31.
The metal compound having reduced photoresponsive semiconductor properties, which is dispersed on the inner wall of the hollow tube itself, is excited, and as a result, free electrons are generated, and ozone in the sample gas is decomposed to generate the ozone decomposition unit 32. The ozone-decomposed sample gas can be collected downstream of the.

This embodiment has the same advantages as the above-mentioned embodiment 20 with respect to the ease of setting.
Further, as compared with the other embodiments, the structure of the ozone decomposing unit serving as a movement path of the sample gas has a structure in which a reduction type photo-semiconductor is formed on the inner wall of a hollow tube made of an ion exchanger having a light-transmitting property in a film form. The metal compound having the characteristics is dispersed, and the desired effect can be sufficiently exerted without separately disposing a member in which the metal compound is dispersed in the hollow tube, and therefore, it is relatively simple. Therefore, when the sample gas passes through the inner wall of the ozone decomposing unit, it is possible to easily keep the frequency of capturing dust and the like low and constant. That is, it is possible to minimize the influence of dust and the like when measuring the ozone concentration in the ultraviolet absorption ozone meter of the present invention described later, and it is possible to realize highly accurate ozone concentration measurement.

Further, in this embodiment, by selecting an ion exchanger having excellent light transmittance as a material for the ozone decomposing unit 32, a metal having a reducing photoresponsive semiconductor characteristic dispersed on the inner wall of the ozone decomposing unit. It is possible to improve the efficiency with which the excitation light reaches the compound. The ozone decomposing unit 30 has the ozone decomposing unit 32 wound around the excitation light source 31, but in another mode, for example, the ozone decomposing unit is attached along the longitudinal direction of the excitation light source 31. Aspects are also possible (not shown).

[Test Example 1-1] (1) A piece of Toyo filter paper 5A was cut into a band-like shape with a width of about 5 mm (maximum effective area of about 95 cm ² ), and this was impregnated with a 10% copper sulfate solution and the temperature was increased. It was dried at 60 ° C. for 1 hour. Next, this paper piece was brought into contact with titanium tetraisoproxide (manufactured by Wako Pure Chemical Industries, Ltd.), an aqueous dispersion of titanium alkoxide. Then, the filter paper was left at room temperature to deposit a titanium oxide gel on the surface of the filter paper. As a result, fine particles of titanium oxide were deposited and deposited on the surface of this filter paper (which is a typical embodiment of the sol-gel method described above).

This filter paper was used as the member 12 of the ozone decomposer 10 of the present invention according to FIG. 1 (A). As the hollow member 11, a glass tube having an inner diameter of 10Φ and a length of 100 mm was used. And as the excitation light source 14, 10 W
A black light (Matsushita Electric Co., Ltd.) was used.

(2) In FIG. 2, the purified air that has passed through the air purifying device 41 is passed through the non-actuated ultraviolet irradiation type ozone generator 42 to the ozone decomposer 10 of (1) above, The exhaust gas was connected to an ultraviolet absorption type ozone measuring device 43 (manufactured by GUX-32 Denki Kagaku Keiki Co., Ltd.) to determine the ozone concentration in the exhaust gas. In addition, the ozone generator 42 (manufactured by Denki Kagaku Keiki Co., Ltd.)
Was operated to test how much ozone generated from the ozone generator 42 was decomposed in the ozone decomposer 10 (about 1 ppm of ozone was continuously supplied to the ozone decomposer 10 for one week).

As a result, the ozone decomposing unit using the control member having the same area as that of the member 12 in which only titanium oxide was deposited without being impregnated with copper sulfate in advance was about 1 above.
Although it decomposed ppm ozone, ozone decomposed in just a few hours, and after 3 days, it showed a demolition rate of about 50%, indicating that the decomposition rate of ozone was extremely incomplete. .

On the other hand, in the case where titanium oxide and copper ions coexist, the above-mentioned about 1 ppm ozone is completely decomposed for one week. Even if the concentration of ozone flowing is increased to 2 ppm, it will be 95% over one month.
Decomposition rate of ozone of over% was continuously shown, and deterioration of its reducing ability was not observed. Thus, it was shown that coexistence of copper ions dramatically improves the ozone reducing ability of the ozone decomposing unit.

Test Example 1-2 (1) A 10% copper sulfate solution was introduced into the inner wall of a Nafion tube (registered trademark of DuPont) having a length of 1 m by a pump,
After being left for 4 hours, the ions of the ion exchange group were replaced with copper ions. Next, titanium oxide fine particles were introduced into the inner wall of the Nafion tube by the same method as shown in Test Example 1-1 (1). The ozone decomposing unit thus prepared was used as an ozone decomposing unit having a form similar to that of the ozone decomposing unit 30 shown in FIG.

(2) An experiment was conducted by using this ozone decomposer 30 in the experimental apparatus shown in FIG. 2 instead of the ozone decomposer 10. 2.5ppm with ozone generator 42
When the 10W black light was turned on after the ozone was generated and the indicated value was confirmed by the ozone concentration measuring device 43, the ozone was decomposed by 100%.

Although 2.5 ppm of ozone was passed through this experimental system for 40 days, no decrease in ozonolysis activity was observed (FIG. 3). The surface area of this Nafion tube is only 10 cm ² or less.
It was found that the ozone decomposability was significantly improved as compared with. As described above, it is clear that the ozone decomposing unit including the ozone decomposing unit configured by selecting the ion exchanger as the carrier of titanium oxide is very excellent in the ozone decomposing property in terms of both effectiveness and durability. became.

Example 2 Ultraviolet Absorption Ozone Meter of the Present Invention FIG. 4 shows an embodiment of an ultraviolet absorption ozone meter of the present invention (5
It is the schematic which showed 0). That is, in FIG.
51 is a sample gas inlet; 52 is a sample gas flow pipe connected to the sample gas inlet 51; 53 is a three-way switching valve interposed in the sample gas flow pipe 52; 54 is a three-way switching valve 5 at one end
A bypass pipe connected to the passage port 3 and the other end connected to the sample gas flow pipe 52 downstream of the three-way switching valve 53;
5 is an ozone decomposer; 56 is an ultraviolet absorption measuring unit,
An ultraviolet absorption cell 57 interposed in the sample gas flow pipe 52,
It includes an ultraviolet lamp 58 disposed in the ultraviolet absorption cell, a detector 59 attached to the ultraviolet absorption cell 57, and a comparison calculation circuit 60 connected to the detector 59. 61,6
Reference numerals 2 and 63 are flowmeters, pumps, and pipes respectively inserted in the sample gas flow pipe 52; and 64 is the sample gas flow pipe 52.
2 shows a sample gas outlet to which the outflow end of is connected. Reference numeral 65 denotes the ozone decomposing unit 55 which has an influence on the dust and the like in the sample gas to be passed, which is interposed in the sample gas flow pipe 52 on the downstream side of the three-way switching valve 53 and on the upstream side of the cell 57.
Is a dummy tube designed to be as equal as possible to the ozone decomposing unit 55 '(for example, having the same structure as the ozone decomposing unit), and 66 is a light source for excitation provided in the vicinity of the ozone decomposing unit of the present invention. is there.

When the ozone concentration in the sample gas is measured by the ultraviolet absorption type ozone meter 50 of the present invention, the sample gas inlet 51 is first operated by operating the pump 62.
The sample gas is sucked into the sample gas flow pipe 52 at a constant flow rate, and the sample gas is directly introduced into the ultraviolet absorption cell 57 by the operation of the three-way switching valve 53 without passing through the bypass pipe 54. Then, when the sample gas is irradiated with ultraviolet rays having a specific wavelength from the ultraviolet lamp 58 in the ultraviolet absorption cell 57, the ultraviolet rays proportional to the concentrations of ozone and other coexisting components in the gas are absorbed in the sample gas, and thus are absorbed. Ultraviolet rays are detected by the detector 59, converted into an electric signal corresponding to the intensity, and stored in the comparison operation circuit 60. The sample gas flowing out of the ultraviolet absorption cell 57 is discharged from the discharge port 64 via the flow meter 61, the pump 62, and the pipe 63. Next, the three-way switching valve 53 is switched, the sample gas is introduced into the ultraviolet absorption cell 57 through the bypass pipe 54, and the measurement is performed in the same manner as above.

At this time, the excitation light emitted from the excitation light source 66 excites the metal compound having the reduced photoresponsive semiconductor characteristics in the ozone decomposition unit 55 'of the present invention to generate free electrons in the sample gas. Since the ozone in the sample is reductively decomposed, ultraviolet rays proportional to the concentration of only coexisting components other than ozone are absorbed, and the intensity of the ultraviolet rays increased by the ozone concentration in the sample gas before ozone decomposition is converted into an electric signal by the detector 59. To be converted. Then, based on the value obtained by subtracting the former ultraviolet intensity from the latter ultraviolet intensity, the ozone concentration in the sample gas is specified, and the ozone concentration in the sample gas is intermittently measured by repeating the above operation. It

By the presence of the ozone decomposing unit 55 'and the dummy tube 65 designed to have the same effect on the dust and the like in the sample gas, the state of the dust and the like in the sample in both is made equal, It is possible to avoid a measurement error caused by the presence of dust or the like.

Further, the mode of the ozone decomposing unit 55 used here is not particularly limited, and any of the above-described ozone decomposing units 10, 20, or 30 of the present invention is the ozone decomposing unit 5.
As a matter of course, it can be used in the ultraviolet absorption type ozone meter of the present invention.

[Test Example 2-1] (1) Regarding the above-mentioned ultraviolet absorption type ozone meter 50 of the present invention using the ozone decomposing unit 30 of the present invention manufactured in Test Example 1-2 (1) as an ozone decomposing unit 55. Various studies were conducted. Comparison of the indicated values with the conventional ultraviolet absorption type ozone meter (using manganese dioxide as an ozone decomposing agent): The ultraviolet absorption type ozone meter (the ozone decomposition of the embodiment shown in FIG. 4 above described in the prior art section. In place of the device 55, an ozone decomposing device containing manganese dioxide as an ozone decomposing material is interposed) and the indicated values of the ultraviolet absorption type ozone meter 50 of the present invention were compared and examined. That is, ozone having a constant concentration was generated using an ozone generator, and it was examined whether or not the indicated values of the ozone meters of both were substantially the same.

The results are shown in FIG. As is clear from the results shown in FIG. 5, the indicated values of the two ozone meters are almost the same, and it has been revealed that the ultraviolet absorption type ozone meter 50 of the present invention can be sufficiently used as an ozone meter. In addition,
In the ultraviolet absorption type ozone meter 50, the Nafion tube which is an ion exchanger which is very preferably used as a carrier of a metal compound having a reduced photoresponsive semiconductor property is used as a carrier in the ozone decomposing unit 55 '. However, since this Nafion tube is rich in water adsorption, it tends to give a positive interference due to water in the sample gas. However, the UV absorption type ozone meter 50
Then, since the dummy tube 65 is provided, the occurrence of the experimental error due to the positive interference can be avoided even if the moisture exists in the sample gas.

Examination of the influence of hydrocarbons such as xylene on the ultraviolet absorption type ozone meter in the prior art: The ultraviolet absorption type ozone meter in the above-mentioned conventional technology and the ultraviolet absorption type ozone meter 50 of the present invention were tested by an experimental apparatus shown in FIG. , The influence of the presence of xylene on the measured values was examined. In FIG. 6, 71 is an air purifying device, 72 is a gas generation bottle with a diffusion tube containing a xylene solution 74 by a vapor pressure gas generation method, and 72 'is a gas generation bottle without a diffusion tube containing a xylene solution, Reference numeral 73 denotes the ultraviolet absorption type ozone meter in the above-mentioned conventional technique.

In FIG. 6A, the air cleaning device 7
Gas generator bottle 72 with diffusion tube for clean air generated in 1
The relatively dilute xylene gas generated from the xylene gas is mixed, and this xylene mixed air is mixed with the conventional ultraviolet absorption type ozone meter 7
3, and the influence on the presence of xylene gas when measured by the ultraviolet absorption type ozone meter 50 of the present invention was examined. Figure 6
In (B), the effect of mixing a rich xylene gas generated from a gas generation bottle without a diffusion tube in the same manner as in FIG. 6 (A) was examined.

The results are shown in FIG. In FIG. 7A corresponding to FIG. 6A, an ultraviolet absorption type ozone meter 7
In both cases 3 and 50, the effect of xylene gas is not so noticeable (although the ultraviolet absorption type ozone meter 73 is considerably affected), but FIG. 7 corresponding to FIG.
It is clear that there is a significant difference between the two in (b). That is, the conventional ultraviolet absorption type ozone meter 73
In the above, the indication violently fluctuates positively and negatively, and the influence is large, but the ultraviolet absorption type ozone meter 50 of the present invention has a small indication fluctuation and has an epoch-making effect in that the measurement error due to the presence of xylene gas is improved. It became clear that he was playing.

The cause of such a remarkable difference is that the inner surface of the Nafion tube used as the carrier of the metal compound having the reduced photoresponsive semiconductor property is very strong due to the irradiation of the excitation light. It is a reducing field, and it is assumed that it did not act on hydrocarbons such as xylene, which have strong ultraviolet absorption. Judging from this point, it is clear that the tendency shown in this test example is the same for other hydrocarbons such as toluene and naphthalene.
Therefore, it was proved that the ultraviolet absorptive ozone meter of the present invention is an epoch-making ultraviolet absorptive ozone meter of the present invention, which has very little influence on the measured value due to the presence of contaminants such as hydrocarbons other than ozone.

[Embodiment 3] FIG. 8 is a schematic view showing another embodiment (80) of the ultraviolet absorption type ozone meter of the present invention.
That is, the meanings of the reference numerals 51, 52, 56 to 64 in FIG. 8 are the same as those in FIG. And
Reference numeral 85 is an ozone decomposing unit of the present invention interposed in the sample gas flow pipe 52, 85 'is an ozone decomposing unit of the present invention corresponding to the ozone decomposing unit 85 of the present invention, 96 is a light source for excitation, and 97 is It is a light source control unit that controls the intensity and the like of the excitation light source 96.

When the ozone concentration in the sample gas is measured by the ultraviolet absorption type ozone meter 80 of the present invention, first, the pump 62 is used.
The sample gas is sucked into the sample gas flow pipe 52 from the sample gas inlet 51 at a constant flow rate by operating the sample gas introduction port 51, and the sample gas is passed through the ozone decomposing unit 85 of the present invention in a state where the excitation light from the excitation light source 96 is cut off Is introduced into the ultraviolet absorption cell 57. When the sample gas is irradiated with ultraviolet rays of a specific wavelength from the ultraviolet ray absorbing cell 57, the sample gas absorbs ultraviolet rays proportional to the concentrations of ozone and other coexisting components in the gas. Ultraviolet rays that have passed through 57 are detected by a detector 59 and converted into an electric signal corresponding to the intensity thereof, and a comparison calculation circuit 60
Memory. The sample gas flowing out of the ultraviolet absorption cell 57 is discharged from the discharge port 64 via the flow meter 61, the pump 62, and the pipe 63.

Next, a process similar to the above is carried out by the excitation light source 9
The sample gas is passed through the ozone decomposer 85 of the present invention in the state where the excitation light from 6 is irradiated. At this time, the excitation light source 9
The ozone in the sample gas is reductively decomposed by the free electrons generated by exciting the metal compound having the reduced photoresponsive semiconductor property in the ozone decomposing unit 85 'of the present invention by the exciting light irradiated by 6 The intensity of ultraviolet rays increased by the ozone concentration in the sample gas before decomposition is converted into an electric signal by the detector 59. Then, the ozone concentration in the sample gas is specified based on the value obtained by subtracting the former ultraviolet intensity from the latter ultraviolet intensity, and the operation of cutting off the excitation light of the excitation light source 96 and the operation of irradiating it are repeated. Thereby, the ozone concentration in the sample gas is intermittently measured.

Here, not only the operation of turning on / off the power source of the excitation light source 96 but also the operation of turning off the power source of the excitation light source 96 is performed as the operation of cutting off the excitation light, that is, the operation of irradiating the metal compound with the excitation light. It is also possible to use a physical means such as blocking the excitation light by using a barrier while keeping the power source of the ON state.

Even if the excitation light source 96 is once turned on and then turned off, the value of the ultraviolet absorption type ozone meter of the present invention is slightly longer than the time when the ozone concentration returns to the original ozone concentration position. It takes. This is because the free electrons photoexcited by the excitation light irradiation do not recombine with the photocatalyst immediately after the excitation light is turned off, and ozone is decomposed by being reduced by the free electrons during this period. That is, until the free electrons are recombined with the photocatalyst, the supplied ozone is still decomposed, and 100% of the supplied ozone does not reach the ultraviolet absorbance measuring section. From the viewpoint of response, there is a tendency to cause a time delay.

In order to eliminate this delay in response, by devising such that the light intensity of the excitation light to be irradiated is selected according to the ozone concentration, the response to the ozone concentration by optical switching is performed at a higher speed. It will be possible.
The mechanism that has such a function is the light source controller 97.

In the embodiment of the second embodiment, the important role for preventing the occurrence of the measurement error of the dummy tube 74 is described. However, in this embodiment, the sample can be used with or without ozone decomposition. Since the gas passes through the same route, there is interference caused in the measurement of ozone concentration due to the difference in material, structure, volume, etc. of the route that passes through the ozone decomposition unit and the route that does not pass in the past, and the difference in the amount of dust and water lost. Can be almost completely erased.

The mode of the ozone decomposer 85 used in the present embodiment is not particularly limited, and any of the ozone decomposers 10, 20 or 30 of the present invention described above is used as the ozone decomposer 85 of the ultraviolet light of the present invention. Of course, it can be used in an absorption type ozone meter.

It is of course possible to make design changes to the above-described embodiments (Examples 2 and 3) without departing from the technical scope of the present invention. For example, in the aspect of the second embodiment, instead of the three-way switching valve 53 that selectively supplies the sample gas to the bypass pipe 54 side or the dummy pipe 65 side, a sample supply means such as a sample supply pipe communicating with the bypass pipe 54. And the sample supply means communicating with the dummy pipe 65 are separately provided, and separated from the beginning to provide the bypass pipe 5.
It is also possible to supply the sample gas to the 4 or the dummy tube 65 (not shown).

Further, in the mode of the second embodiment, if the means for preparing the supplied sample gas in advance to remove the influence of dust and the like is provided, the sample gas flow pipe 52 is necessarily provided with the dummy pipe 65. No need (not shown).

In addition, in the case where the flow rate of the sample gas is large, it is possible to provide a means such as providing a bypass pipe in the main flow path of the sample gas to adjust the flow rate when the flow rate of the sample gas is large. It is possible (not shown).

[0090]

According to the first to fifth aspects of the present invention, there is provided an ozone decomposing unit capable of providing a sample gas in which ozone is specifically decomposed by using it in combination with a light source for excitation. According to the invention of claim 6,
An ozone decomposer capable of providing a sample gas in which ozone is specifically decomposed is provided. According to the invention of claim 7, it is possible to avoid the occurrence of a measurement error due to the presence of components other than ozone in the sample, and to provide an ultraviolet absorption type ozone meter having excellent durability. According to the invention of claim 8,
Provided is an ultraviolet absorption type ozone meter which has excellent durability and can avoid occurrence of measurement error to the utmost limit.

[Brief description of drawings]

FIG. 1 is a schematic view of an ozone decomposer of the present invention.

FIG. 2 is a schematic view of a test device for ozone resolution of the ozone decomposer of the present invention.

FIG. 3 is a graph for examining changes in ozone resolution with time of the ozone decomposer of the present invention.

FIG. 4 is a schematic view showing one embodiment of the ultraviolet absorption type ozone meter of the present invention.

FIG. 5 is a graph comparing the indicated values of a conventional ultraviolet absorption type ozone meter and the ultraviolet absorption type ozone meter of the present invention.

FIG. 6 is a schematic view of an apparatus for examining the influence of the presence of xylene on the ultraviolet absorption type ozone meter of the present invention.

FIG. 7 is a graph showing the results of examining the effect of the presence of xylene on the ultraviolet absorption type ozone meter of the present invention.

FIG. 8 is a schematic view showing another embodiment of the ultraviolet absorption type ozone meter of the present invention.

[Explanation of symbols]

 50,80 Inventive UV absorption type ozone meter 55,85 Ozone decomposer 55 ', 85' Ozone decomposition unit 56 UV absorbance measuring unit 66,96 Excitation light source

Claims (8)

[Claims] 1. A sample gas inflow port is provided at one end of a hollow member having airtightness, a sample gas outflow port is provided at the other end, and the sample gas is introduced into the inside of the hollow member from the sample gas inflow port. An ozone decomposing unit, in which a metal compound having reduced photoresponsive semiconductor properties is arranged in a manner that allows contact with. 2. The fine particles of a metal compound having reduced-type photoresponsive semiconductor properties are dispersed in an ion exchanger and are disposed inside an airtight hollow member. Ozone decomposition unit. 3. A material for an airtight hollow member is an ion exchanger, and fine particles of a metal compound having reduced photoresponsive semiconductor properties are dispersed on the inner wall of the hollow member. The ozone decomposition unit according to claim 1. 4. The ozone decomposing unit according to claim 1, wherein the metal compound having reduced-type photoresponsive semiconductor properties is titanium oxide. 5. The ozone according to any one of claims 1 to 4, wherein a metal ion or a metal is supported in the vicinity of a metal compound having reduced-type photoresponsive semiconductor properties. Disassembly unit. 6. An ozone decomposing unit according to any one of claims 1 to 5, and irradiation of excitation light toward a metal compound having a reduced photoresponsive semiconductor property arranged in the ozone decomposing unit. An ozone decomposer characterized by being combined with an excitation light source which is a light source for 7. An ozone decomposing unit and an ultraviolet ray absorbance measuring unit, wherein the ultraviolet ray absorbance of the sample gas that has passed through the ozone decomposing unit and the ultraviolet ray absorbance of the sample gas that does not pass through the ozone decomposing unit are respectively described above. In the ultraviolet absorption type ozone meter for measuring the ozone concentration in the sample gas from the difference between these two ultraviolet absorbances, the ozone decomposer is the ozone decomposer according to claim 6. UV absorption type ozone meter. 8. An ultraviolet absorption type ozone meter comprising an ozone decomposing unit and an ultraviolet absorption measuring section, wherein the ozone decomposing unit is the ozone decomposing unit according to claim 6, and the sample passed through the ozone decomposing unit. The UV absorbance of the gas is measured by the UV absorbance measuring unit in each of the cases where the metal compound according to claim 6 is irradiated with the excitation light and when the metal compound is not irradiated, and the difference between the UV absorbances of the two gas samples is measured. An ultraviolet absorption type ozone meter characterized by determining the ozone concentration.