JP2003024464A - Decomposition method of hardly decomposable compound and decomposition device of hardly decomposable compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decomposition device of hardly decomposable compound and decomposition method of hardly decomposable compound capable of performing the treatment of a hardly decomposable compound in a perfectly closed system without requiring high temperature and high pressure, and being miniaturized so as to be movable and portable. SOLUTION: This decomposing method of hardly decomposable compound comprises bringing the hardly decomposable compound into contact with ozone water. In this method, the ozone water is obtained by dissolving ozone gas to water through a nonporous gas dissolving film, the ozone water is circulated in a reaction system, and the decomposition of the hardly decomposable compound is performed in a closed system.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the decomposition of a hardly-decomposable compound which can be processed in a completely closed system, does not require high temperature and high pressure, and can be miniaturized so as to be portable. The present invention relates to a device and a method for decomposing a hardly decomposable compound.

[0002]

2. Description of the Related Art Persistent compounds such as dioxins, which are well known as harmful substances to the human body, are discharged to the natural world from incineration facilities for municipal waste and industrial waste, various combustion facilities, equipment, etc. In addition, various organic compounds that have an adverse effect on the environment are emitted in the manufacturing process of chemical substances, which is a big social problem.

Generally, polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF)
Are collectively referred to as dioxins, and substances having the same toxicity as dioxins such as coplanar polychlorinated biphenyl (coplanar PCB) are called dioxin-like compounds. In the "Act on Special Measures Against Dioxins" promulgated on July 16, 1999, PCD
D and PCDF including coplanar PCB were defined as "dioxins".

Of these, the most representative compounds are
It is 2,3,7,8-tetrachlorodibenzo-p-dioxin. It is known that these dioxins and the like are difficult to be decomposed by living organisms, and are absorbed into the bodies of many living organisms, and finally accumulated and concentrated in the animal body by the food chain, and are known to show teratogenicity. There is.

As a processing method of PCB, pressure 25MP
a. A supercritical water-oxidation decomposition method that decomposes at a reaction temperature of 500 to 600 ° C. and an ultrahigh pressure and high temperature has been developed, but it has not come into widespread use because it requires large-scale and expensive equipment. Combustion method and dechlorination method are known as other PCB treatment methods, but the safety of the combustion method has not been verified and it is difficult to obtain the consent of the surrounding residents.
Due to the need for large-scale equipment, it has not reached widespread use.
Although it is a method of treating at a reaction temperature of 0 to 300 ° C., it is not widely used because metal sodium is used, so that the running cost is high and the treatment of generated biphenyl is required.

Although each company is responsible for processing PCBs, each company owns only a small amount, so purchasing and processing the processing equipment is not cost-effective, and each company stores it individually for permanent storage. There are many cases. PCBs are currently designated as specified chemical substances by the "Law concerning the examination and regulation of chemical substances", and their production, import and use are severely restricted. If you own a PCB, you need to report it, but with the deterioration of the economic situation in recent years,
The number of registrations is gradually decreasing due to bankruptcy, etc., and it is unknown how PCBs that disappeared in the record were disposed of.

[0007] Phenols are adsorbed and separated by activated carbon and decomposed by activated sludge, but halogenated phenols, alkylphenols, bisphenols, phthalates and the like are biological compounds due to their chemical structure. There is a problem that they are not easily decomposed and are easily accumulated in the environment, and these compounds are bioconcentrated by the food chain, causing various damages to humans and environmental organisms.

On the other hand, ozone water obtained by dissolving ozone gas in water exerts excellent effects on sterilization, deodorization, bleaching, etc. due to the strong oxidizing power of ozone, and ozone gas is harmless oxygen (gas) over time. Since it self-decomposes and has no persistence, it has been attracting attention as an environmentally friendly sterilizing / cleaning / bleaching agent.

A conventional ozone water generator is generally an aeration type (bubbling type) or an ejector type using a mixer (ejector).
The aeration method is a method of injecting bubbles of ozone gas into water to dissolve ozone in water. In this method, if the obtained ozone water contains bubbles, the oxidizing effect of ozone is not sufficiently exerted, so it is necessary to remove the bubbles in the gas-liquid separation layer, and also to increase the dissolution rate of ozone. Therefore, if the bubbles of aeration are made fine, there is a problem that it takes time to separate gas and liquid.

The module type is a system in which ozone gas is brought into contact with water through a gas dissolving film to dissolve ozone in water. As a module type, JP-A-7-
Japanese Patent No. 213880 discloses an apparatus using a porous hollow tubular ozone gas permeable membrane. However, the porous ozone gas permeable membrane is apt to clog pores, and
In a porous ozone gas permeable membrane, the ozone gas diffuses into the water through the water that has penetrated into the pores.Therefore, the ozone gas pressure must be adjusted to be slightly lower than the water pressure in order to penetrate the water into the pores. is necessary. Further, when the aeration method is used or a porous hollow tubular ozone gas permeable membrane is used, the treatment in a closed system is difficult.

[0011]

In view of the above situation, the present invention can treat a hardly decomposable compound in a completely closed system, does not require high temperature and high pressure, and can be miniaturized so as to be portable. An object of the present invention is to provide an apparatus for decomposing a hardly decomposable compound and a method for decomposing a hardly decomposable compound.

[0012]

The present invention is a method for decomposing a hardly decomposable compound by bringing the hardly decomposable compound into contact with ozone water, wherein the ozone water comprises a non-porous gas-soluble film. It is obtained by dissolving ozone gas in water through the ozone gas, the ozone water circulates in the reaction system, and the method for decomposing the hardly decomposable compound is a method for decomposing the hardly decomposable compound performed in a closed system. A device for decomposing a persistent compound, comprising at least an ozone dissolving module in which a process of dissolving ozone gas in water is performed, and a reaction tank in which a process of decomposing a persistent compound in ozone water is performed. A non-decomposable compound decomposing device in which a non-porous gas dissolving film is housed therein and ozone water circulates between the reaction tank and the ozone dissolving module is also one aspect of the present invention. The present invention is described in detail below.

One embodiment of the method for decomposing a hardly decomposable compound of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing one form of a persistent compound decomposing apparatus for carrying out the method for degrading a persistent compound according to the present invention. The apparatus for decomposing persistent compounds shown in FIG. 1 comprises an ozone generator 1, an ozone gas detector 2, an ozone dissolution module 3, an ozone water detector 4, a reaction tank 5, and a water pump 6.

In the ozone generator 1, ozone gas for dissolving in water is generated. The ozone generator 1 is not particularly limited, and a known ozone generator can be used. The ozone gas concentration generated by the ozone generator 1 is measured and monitored by the ozone gas detector 2. The value of the ozone gas concentration measured by the ozone gas detector 2 is fed back to the ozone generator 1, and the concentration of the ozone gas generated by the ozone generator 1 is adjusted at any time.

The ozone gas generated by the ozone generator 1 is
It is dissolved in water in the ozone dissolution module 3. As the ozone dissolving module 3, for example, one having a structure as shown in FIG. 2 can be used. Inside the ozone dissolution module 3, a non-porous hollow fiber (tubular)
A gas dissolving film 7 made of
Penetrates between the molecular chains of the resin forming the gas-dissolved film, and then diffuses into water.

When a porous gas-dissolving film is used, ozone gas is first dissolved in water that has penetrated into the pores of the gas-dissolving film, and then ozone diffuses into water according to a concentration gradient, so that impurities are mixed. When ozone water circulates, the pores become clogged and the ozone gas cannot be dissolved in water. However, in the present invention, since the gas dissolution film made of a non-porous gas dissolution film without pores is used, the gas dissolution film is Ozone water can be circulated and used without clogging. Also, when a gas dissolving film made of a porous material is used, ozone gas dissolves in water through the water that has penetrated into the pores, so the ozone gas pressure should be lower than the water pressure to allow the water to soak into the pores. Although strict adjustment is necessary, in the present invention, since a gas dissolving film made of a non-porous gas dissolving film is used, it is not necessary to adjust the ozone gas pressure and the ozone gas is made to have a high pressure. be able to. Furthermore, when a gas-dissolving film made of a porous material is used, there is a risk that bubbles that reduce the decomposition efficiency are mixed in the obtained ozone water, but in the present invention, a non-porous gas-dissolving film without pores is used. Since a gas-dissolving film consisting of is used, bubbles do not mix. Furthermore,
In the method using the porous gas dissolving membrane which is an open system and the aeration method, the ozone gas discharge line may be contaminated with the persistent compound, but in this method which is a completely closed system,
Persistent compounds do not flow out of the processing line.

The non-porous gas dissolving film is preferably formed by molding a silicone resin or a fluorine resin. A non-porous gas-soluble film made of a silicone-based resin or a fluorine-based resin has excellent corrosion resistance and deterioration resistance, and has a property of efficiently transmitting ozone gas.

Examples of the fluorine-based resin include tetrafluoroethylene copolymer (PTFE), perfluoroalkoxy resin (PFA), fluorinated ethylene-propylene resin (FEP), and other tetrafluoroethylene-based resin polymers; fluorine Examples of the silicone-based resin include polydimethylsiloxane and methylsilicone rubber. If it is a perfluorinated resin,
Any resin can be used as a raw material for a non-porous gas-soluble film.

The gas dissolving film used in the present invention includes:
Although a flat membrane may be used, as a more efficient membrane, it is preferable to make such a membrane material into a non-porous hollow tube (tube shape) molded into a required inner diameter and length, Both ends of a plurality of these bundled are heat-sealed or adhered to each other to be bundled and housed in the outer jacket of the ozone dissolution module 3.

The outer cover of the ozone dissolving module 3 is not particularly limited as long as it has excellent ozone resistance and airtightness, and is made of, for example, PFA, PTFE, vinylidene fluoride resin, stainless steel material or the like. There is something like.

Water for dissolving ozone gas may flow on either the inner side (inside of the tube) or the outer side of the non-porous hollow fiber, but the water flows on the outer side of the non-porous hollow fiber and the inner side of the non-porous hollow fiber. Ozone gas is preferably passed through. If water flows inside the non-porous hollow fiber, the hollow fiber may be clogged with foreign matter.

The dissolved ozone gas concentration of the ozone water generated in the ozone dissolution module 3 is monitored and controlled by the ozone water detector 4. Although the saturated dissolution concentration of ozone in water at atmospheric pressure and room temperature is 50 to 60 ppm, the concentration of dissolved ozone gas in ozone water used for decomposing persistent compounds is better than that of decomposing compounds that are difficult to decompose. Higher is preferable. Therefore, it is preferable that the apparatus for decomposing a persistent compound according to the present invention has a means for pressurizing ozone gas and a means for pressurizing the inside of the reaction system. The means for pressurizing the ozone gas and the reaction system is not particularly limited as long as it can pressurize the ozone gas generated by the ozone generator 1 and the reaction tank to a pressure higher than normal pressure, but an ozone resistant gas material is used. A pressure pump is preferably used. By pressurizing the ozone gas or the inside of the reaction tank, the concentration of dissolved ozone gas in ozone water can be increased to about 200 ppm.

The obtained ozone water is used in the reaction tank 5 for decomposing the hardly decomposable compound. The hardly decomposable compound is not particularly limited, and examples thereof include dioxins, PCBs, bisphenols, alkylphenols, halogenated phenols, phthalic acid esters,
Examples include estradiol, benzophenone, trichlorethylene and the like.

The above dioxins are dioxins having one or more chlorine atoms, and are compounds in which hydrogen atoms in two benzene rings of dibenzo-p-dioxin or dibenzofuran are replaced by chlorine atoms. A wide variety of compounds are included depending on the number of substitutions of the chlorine atom and the substitution position on the benzene ring. Among these dioxins, polychlorinated compounds having 4 or more chlorine atoms in one molecule are particularly highly toxic to the human body, and examples of such compounds include 2,3,7,8-tetrachlorodibenzo- p-dioxin, 1,2,3,7,8
-Pentachlorodibenzo-p-dioxin, 1,2,
3,4,7,8-hexachlorodibenzo-p-dioxin, 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin, 1,2,3,4,6,7,8 , 9
Polychlorinated dibenzo-p-dioxins such as -octachlorodibenzo-p-dioxin; 2,3,7,8-tetrachlorodibenzofuran, 1,2,3,7,8-pentachlorodibenzofuran, 2,3,3 4,7,8-Pentachlorodibenzofuran, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,6,7,8-hexachlorodibenzofuran, 1,2,3,7,8, 9-
Hexachlorodibenzofuran, 2,3,4,6,7,8
-Hexachlorodibenzofuran, 1,2,3,4,6,6
7,8-Heptachlorodibenzofuran, 1,2,3
Examples include polychlorinated compounds of dibenzofuran such as 4,6,7,8,9-octachlorodibenzofuran.

The above-mentioned PCBs are not particularly limited as long as two or more hydrogens of biphenyl are replaced by chlorine, but among them, 3,3 ', 4,4'-tetrachlorobiphenol, 3 , 3 ', 4,4', 5-pentachlorobiphenol, 3,3 ', 4,4', 5,5'-
Coplanar such as hexachlorobiphenol
nar) PCBs are particularly toxic. The above-mentioned bisphenols include 2,2-bis (4-hydroxyphenyl)
Examples include compounds such as propane and 1,1-bis (4-hydroxyphenyl) cyclohexane. Examples of the alkylphenols include compounds such as nonylphenol, pentylphenol and tertiary butylphenol.

Examples of the halogenated phenols include compounds such as dichlorophenol, trichlorophenol, tetrachlorophenol and pentachlorophenol. Examples of the phthalic acid esters include compounds such as dibutyl phthalate, butylbenzyl phthalate and di-2-ethylhexyl phthalate.

These hardly-decomposable compounds which are decomposed in the present invention may be in the extracted state, but may be in the state of being adhered to the member or impregnated in the member.
In the present invention, since it is possible to treat the entire member contaminated with the hardly decomposable compound, it is possible to treat the transformer / capacitor impregnated with PCB as it is.

The treatment method in the reaction tank 5 is not particularly limited, and examples thereof include batch treatment (dip) and continuous treatment. Of these, batch processing, which is a closed processing method, is preferable.

A means for irradiating ultraviolet rays may be added to the reaction tank 5. By irradiating with ultraviolet rays, the decomposition rate of ozone is accelerated, and accordingly, the decomposition effect of the hardly decomposable compound can be enhanced. Therefore, a higher decomposition effect can be obtained by using high-concentration ozone water and ultraviolet irradiation together. The means for irradiating the ultraviolet rays is not particularly limited, and examples thereof include a UV lamp and the like. The wavelength of the ultraviolet light emitted is 25, which is absorbed by ozone.
It is preferably around 4 nm.

The apparatus for decomposing hardly-decomposable compounds of the present invention preferably has a means for adding hydrogen peroxide and / or an organic solvent to ozone water. By adding hydrogen peroxide and / or an organic solvent to ozone water, the decomposition effect of the hardly decomposable compound can be improved. Further, as shown in Example 4, it was also clarified that the solubility of ozone gas in water was increased when an organic solvent was added. This is also considered to be one of the reasons why the addition of the organic solvent improves the decomposition of the hardly decomposable compound. Further, by adding an organic solvent, the hardly decomposable compound impregnated in the member can be extracted and decomposed at the same time, so that the decomposition can be efficiently performed. The organic solvent is not particularly limited, and examples thereof include acetic acid, acetone, acetonitrile and the like.

The refractory compound decomposing apparatus of the present invention has a structure in which ozone water circulates between the reaction tank and the ozone dissolving module. The ozone water used for decomposing the hardly decomposable compound in the reaction tank 5 is returned to the ozone dissolving module 3 by the water pump 6 and the consumed ozone gas is supplied. The ozone water supplemented with ozone gas is used again in the reaction tank 5 for decomposing the hardly decomposable compound.

In the method for decomposing a hardly decomposable compound of the present invention, since the hardly decomposable compound is decomposed using ozone water, high temperature and high pressure are not required, and a non-porous gas dissolving film is used for the generation of ozone water. Since it is used, it does not clog, unlike a gas-soluble film made of a porous material, and thus ozone water can be circulated in the reaction system to treat the hardly decomposable substance in a completely closed system. Further, since the non-porous gas dissolving film is used, the ozone gas can be pressurized and the concentration of dissolved ozone gas in ozone water can be kept high, so that the decomposition effect can be enhanced. Furthermore, since a non-porous gas dissolving film is used, bubbles that deteriorate the decomposition efficiency do not mix. In the present invention, a higher decomposition effect can be obtained by using UV irradiation together. The apparatus for decomposing persistent compounds of the present invention can be miniaturized so that it can be carried around.

[0033]

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

(Example 1) An ozone gas generator (manufactured by Mitsubishi Electric Corporation: ozone generation unit OP-) was installed in an ozone dissolution module having the specifications shown in Table 1 through an ozone gas detector (manufactured by Riko Kagaku Co., Ltd .: OZR-3000). Three
5N-S) is connected to the ozone gas generator, and the oxygen flow rate is 2
L / min, nitrogen flow rate 40mL / min, feed the raw material gas,
Ozone gas is generated with a generated current of 0.8 to 1.55 A,
The ozone gas generated was pressurized to an ozone gas pressure of 0.25 MPa and sent out, and the ozone concentration of the generated ozone gas was monitored by an ozone gas detector, and the gas concentration was 170 mg /
Ozone gas having a L flow rate of 2 L / min was supplied to the ozone dissolution module to generate ozone water. At this time, the water temperature was 20 ° C. and the flow rate of water was 0.1 L / min. The dissolved ozone gas concentration of the generated ozone water was measured by an ozone water detector (OZR-3000 manufactured by Riko Kagaku Co., Ltd.). The results are shown in Table 3.
It was shown to.

[0035]

[Table 1]

Example 2 An ozone dissolution module having the specifications shown in Table 2 was used, and the flow rate of water was 0.05 L.
Ozone water was generated in the same manner as in Example 1 except that the concentration was / min, and the dissolved ozone gas concentration of the generated ozone water was measured. The results are shown in Table 3.

[0037]

[Table 2]

[0038]

[Table 3]

From the results of Examples 1 and 2, it was found that according to the ozone dissolution module used in the present invention, ultra-high concentration ozone water having extremely high reactivity can be obtained.

Example 3 Using orange 2 as a model compound of a hardly decomposable compound, the decomposition efficiency of orange 2 by ozone was measured by the reflux type decomposition device shown in FIG. First, 2 L of an orange 2 aqueous solution was prepared by dissolving orange 2 in water to a concentration of 0.03%, and this was supplied to a decomposition device. At this time, the water temperature was 20 ° C. and the flow rate of the orange 2 aqueous solution was 600 mL / min. Then, in the ozone gas generator, oxygen flow rate 2 L / min, nitrogen flow rate 40 mL
Source gas is sent at a flow rate of 0.8 / 1.55
Ozone gas was generated in A, the generated ozone gas was pressurized and sent out at an ozone gas pressure of 0.25 MPa, the ozone concentration was monitored by an ozone gas detector, and then the ozone gas was supplied to an ozone dissolution module to dissolve the ozone gas in the orange 2 aqueous solution. 546nm of orange 2 solution after ozone dissolution
Absorbance was measured and the amount of orange 2 decomposed per minute was calculated. The results are shown in Table 4.

[0041]

[Table 4]

Example 4 Example 2 was repeated except that a 10% aqueous solution of acetic acid was used as water for dissolving ozone gas.
Ozone water was produced in the same manner as above, and the dissolved ozone gas concentration was measured. The results are shown in Table 5.

[0043]

[Table 5]

From the results of Example 4, it was found that the solubility of ozone gas is increased by adding an organic solvent to water in which ozone gas is dissolved.

(Example 5) Example 4 was repeated except that a 10% aqueous solution of acetic acid was used as water for dissolving Orange 2.
The decomposition rate of Orange 2 was measured in the same manner as in the reflux method of. The decomposition rate of Orange 2 at this time was 0.37 (ΔA
bs / min), which was 2.2 times that in the case where acetic acid was not added.

[0046]

EFFECTS OF THE INVENTION According to the present invention, it is possible to treat a hardly decomposable compound in a completely closed system, and it is possible to reduce the size of the compound so that it can be moved and carried without requiring high temperature and high pressure. An apparatus and a method for decomposing a hardly decomposable compound can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view showing one embodiment of the apparatus for decomposing a hardly decomposable compound of the present invention.

FIG. 2 is a schematic diagram showing an ozone dissolution module.

FIG. 3 is a schematic view showing a decomposing device that decomposes orange 2 in an example.

[Explanation of symbols]

1 Ozone generator 2 Ozone gas detector 3 Ozone dissolution module 4 Ozone water detector 5 reaction tanks 6 water pump 7 Gas-soluble membrane consisting of non-porous hollow fiber 8 ozone molecules

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C07B 37/06 C07B 37/06 C07C 25/18 C07C 25/18 39/06 39/06 39/27 39/27 39 / 367 39/367 69/80 69/80 A C07D 307/91 C07D 307/91 319/24 319/24 F term (reference) 2E191 BA11 BA13 BA15 BC01 BD11 BD17 4C037 SA03 4G035 AA01 AC01 4G075 AA37 BA04 BA05 BA06 CA33 CA57 4H006 AA04 AA05 BA95 BB31 BC11 BE31 BE32

Claims (7)

[Claims] 1. A method for decomposing the hardly decomposable compound by contacting the hardly decomposable compound with ozone water, wherein the ozone water dissolves ozone gas in water through a non-porous gas dissolving film. A method for decomposing a hardly decomposable compound, wherein the ozone water is circulated in the reaction system, and the decomposition of the hardly decomposable compound is performed in a closed system. 2. The method for decomposing a hardly decomposable compound according to claim 1, wherein the non-porous gas dissolving membrane is made of a non-porous hollow fiber. 3. The non-porous gas dissolving film is made of a fluororesin or a silicone resin.
Or the method for decomposing a hardly decomposable compound according to 2. 4. The method for decomposing a hardly decomposable compound according to claim 1, wherein the ozone gas and the reaction system are pressurized. 5. The method according to claim 1, wherein at least one means selected from the group consisting of irradiation of ultraviolet rays, addition of hydrogen peroxide, and addition of an organic solvent is applied. A method for decomposing a decomposable compound. 6. The hardly decomposable compound is dioxins, P
4. At least one selected from the group consisting of CBs, bisphenols, alkylphenols, halogenated phenols, phthalates, estradiol, benzophenone, and trichloroethylene, claim 1, 2, 3, 4. The method for decomposing the hardly decomposable compound according to 4 or 5. 7. A device for decomposing a persistent compound, comprising at least an ozone dissolving module in which a process of dissolving ozone gas in water is performed, and a reaction tank in which a process of decomposing a persistent compound in ozone water is performed. The ozone-dissolving module contains a non-porous gas-dissolving film, and ozone water circulates between the reaction tank and the ozone-dissolving module.