JPH11179195A - Organic compound decomposition method, apparatus to be employed therefor, waste gas purification method, and apparatus to be employed therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the possibility of causing new environmental pollution by compounds produced by decomposition and make complicated control for the decomposition unnecessary by brining an organic compound into contact with functional water having pH value, redox potential, and chlorine concentration within respectively specified ranges. SOLUTION: An organic compound to be decomposed is brought into contact with functional neutral water practically having pH about higher than 4 and not higher than 10, redox potential not lower than 300 mV and lower than 800 mV measured by using a platinum electrode as a work electrode and a silver-silver chloride electrode as a reference electrode, and the remaining chlorine concentration not lower than 2 mg/l and not higher than 70 mg/1. Then, when a water tank 101 is filled with water in which an electrolytic substance is dissolved and electricity is supplied to electrodes 103 and 105 from an electric power source 109, acidic water is produced in the positive electrode 105 side. When the organic compound is supplied to the positive electrode 105 side of the water tank 101 from a pipe 115 and brought into contact with the functional water, the organic compound is decomposed. The deactivated functional water is discharged to a tank 119.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing an organic compound, an apparatus used therefor, a method for purifying exhaust gas, and a device for purifying exhaust gas.

[0002]

2. Description of the Related Art With the development of industrial technology up to recent years, various organic compounds such as aromatic compounds and halogenated aliphatic hydrocarbons have been used enormously, and disposal thereof has become a serious problem. In addition, various halogenated aliphatic hydrocarbons used have caused environmental problems such as pollution of the natural environment, and great efforts have been made to solve them. For example, chlorofluorocarbon, which is one of halogenated aliphatic hydrocarbons, is used in a large amount as a spray or a refrigerant, and is a global problem as a cause of ozone holes. Chlorinated aliphatic hydrocarbons such as trichloroethylene (TCE) and tetrachloroethylene (PCE) have been widely and widely used in various industries as cleaning solvents and reaction solvents for metal parts, semiconductor parts, clothing and the like. However, since the toxicity of these compounds to living organisms, such as mutagenicity and carcinogenicity, was pointed out, it has been required to eliminate the use of these compounds and to treat the solvents used so far to render them harmless. Further, these compounds which have already leaked into the natural environment cause pollution of rivers, groundwater and soil, and a technique for economically and efficiently purifying these pollutants diffused into the natural environment is desired. Various element technologies for that purpose have been proposed.

[0003] For example, as an example of a method for decomposing chlorinated aliphatic hydrocarbon compounds, there is a method of burning activated carbon or the like to which chlorinated aliphatic hydrocarbons are adsorbed. This method is relatively simple, but during the combustion process, the decomposition products of chlorinated aliphatic hydrocarbons, such as hydrogen chloride and chlorine, react with other organic substances, resulting in more toxic substances such as polychlorinated biphenyls and dioxins. There is a concern about the possibility of emissions. High temperature treatment is a disadvantage even in terms of energy.

As another example of the method for decomposing chlorinated aliphatic hydrocarbon compounds, there is a method using an oxidizing agent or a catalyst. Specifically, for example, a method for decomposing with ozone (JP-A-3-3829)
7), a method of performing wet oxidative decomposition under high temperature and high pressure, and a method of performing oxidative decomposition with hydrogen peroxide or an iron salt (JP-A-60-261590) are known. However, in the oxidation treatment with ozone, the decomposition efficiency of chlorinated aliphatic hydrocarbons is low, and it cannot be said that it is still at a practical level. In addition, wet oxidative decomposition requires processing under high temperature and high pressure, and has a problem that the apparatus becomes large.

A method using sodium hypochlorite as an oxidizing agent has also been proposed (US Pat. No. 5,561,561).
No. 1642), it is generally considered that a large amount of chlorine is required since the oxidizing action of chlorine is weak. Therefore, a method of combining sodium hypochlorite with ultraviolet irradiation has been proposed (US Pat. No. 5,582,741), but has not been put to practical use. A method is also known in which a photocatalyst composed of oxide semiconductor fine particles such as titanium oxide and a liquid chlorinated aliphatic hydrocarbon are suspended under alkaline conditions and decomposed by light irradiation (Japanese Patent Publication No. 144137/1995). In addition to the suspension treatment and the light irradiation treatment, a regeneration treatment of the photocatalyst is required. Also, a catalytic method of performing oxidative decomposition using an oxide such as a platinum-based, alumina-based, or zirconia-based oxide is known (Hiroshi Ichimura et al .: same as above; JP-A-6-31135). There is a problem that a high temperature of about 300 ° C. or more is required and the processing efficiency is insufficient.

Further, as a method for decomposing chlorinated aliphatic compounds, a photodecomposition method of irradiating ultraviolet rays in the gas phase without using an oxidizing agent has already been attempted (Sekihiro et al .: "Present state and countermeasures of groundwater and soil pollution"). Japan Society on Water Environment, Kansai Chapter, Environmental Technology Research Association, 1995; Japanese Patent Application Laid-Open No. 8-243351). However, in this method, harmful by-products such as phosgene and dichloroacetyl chloride may be generated, and the processing cost and processing efficiency are problematic.

[0007] It is known that chlorinated aliphatic hydrocarbons such as TCE and PCE are decomposed aerobically or anaerobically by microorganisms, and it has been attempted to decompose or purify using such a process. Have been. Microbial treatment is performed by oxidation or dechlorination at normal temperature and pressure, and has the advantage that a large-scale device is not necessarily required. It also has disadvantages such as troublesome management.

As an example of decomposing a fluorinated aliphatic hydrocarbon compound with a catalyst, for example, Japanese Patent Publication No.
No. 54 and U.S. Pat. No. 5,340,555. These methods do not require very large equipment, but require a heating device that consumes a huge amount of energy. In addition, replacement and reactivation of the catalyst are indispensable because the catalyst deteriorates. Further, although it is suitable for treating low-concentration Freon gas, it is difficult to completely decompose it with high-concentration gas treatment, and it may be necessary to reprocess Freon gas remaining in the waste gas.

Japanese Patent Application Laid-Open No. 1996-14167 discloses a decomposition method in which a fuel such as alcohol or ether is mixed with Freon gas and burned in the presence of a catalyst. These methods use an exothermic reaction during combustion to decompose chlorofluorocarbons into atoms, but the equipment becomes larger and requires a large amount of fuel for the processing operation, resulting in a relatively high processing cost. . Further, there is a concern that during the combustion process, hydrogen chloride, chlorine, and the like, which are decomposition products of halogenated aliphatic hydrocarbons, react with other organic substances, and emit more toxic substances such as polychlorinated biphenyls and dioxins.

US Pat. No. 5,393,394 discloses a method of decomposing fluorocarbon gas directly or by dissolving it in a solvent and irradiating it with ultraviolet rays. Although this is a clean decomposition method using a photoreaction, the quantum yield of the photoreaction of halogen dissociation is low, so it is necessary to extend the UV irradiation time or increase the UV output to obtain a sufficient decomposition rate. is there. Also, it is not suitable for high-concentration fluorocarbon decomposition treatment. Furthermore, since the photolysis treatment does not proceed up to 100%,
It has drawbacks such as the necessity of reprocessing waste gas and liquid after treatment. Since the method for decomposing CFCs under the condition of large energy consumption as described above cannot avoid the enlargement of the apparatus and the high processing cost, a method for decomposing CFCs under a milder environment at normal temperature and normal pressure has been proposed. For example, Japanese Patent Publication No. 073507 discloses a method in which chlorofluorocarbon is brought into contact with an electrode of an electrolytic cell to reductively decompose it. In the case of liquid Freon, it can be directly put into an electrolytic cell, and in the case of gaseous Freon, it can be dissolved in an electrolytic solution and subjected to electrolytic reduction on the cathode side for decomposition.
Although it has the advantage that it can be decomposed under mild conditions, it is necessary to increase the amount of electricity and increase the residence time of CFCs in order to obtain a sufficient decomposition effect. At present, a satisfactory decomposition rate cannot be obtained. It is also considered possible to decompose chlorofluorocarbons in a manner similar to the decomposition of chlorinated aliphatic hydrocarbons by microorganisms. However, at present, there are few reports on microbial decomposition of chlorofluorocarbons.

In order to decompose another organic compound, for example, a hardly decomposable aromatic compound, specifically a compound having a biphenyl bond or a biphenyl skeleton (for example, polychlorinated biphenyl), (1) combustion, (2) (3) Decomposition by irradiation with ultraviolet light or radiation, (3) Microbial decomposition method, and the like have been proposed. However, in Japan, it is only implemented by the method (1). Since the biphenyl bond of the biphenyl skeleton is stable, its decomposition usually requires high energy such as pressurization and combustion, so it must be burned at 1400 ° C or more in an incinerator. It produces harmful substances such as highly toxic dioxins. The method using combustion at high temperature does not require much equipment, but requires a heating device that consumes a huge amount of energy. Since the decomposition method of the biphenyl compound under the conditions of large energy consumption such as high temperature and high pressure as described above cannot avoid the enlargement of the equipment and the high processing cost, the decomposition method of the biphenyl compound under a milder environment of normal temperature and normal pressure is required. Proposed. A method of decomposing a biphenyl compound directly or by dissolving it in a solvent and irradiating it with ultraviolet light is disclosed. For example, a method of dissolving polychlorinated biphenyl in an alkaline alcohol, removing oxygen from the solution, and irradiating the solution with ionizing radiation or ultraviolet light to convert the polychlorinated biphenyl into a harmless substance is disclosed in, for example, Japanese Patent Publication No. 47457/1982. Issue. In addition to this, PCB detoxification technology using light is disclosed in, for example, Japanese Patent No. 919505, Japanese Patent Publication No. 45027/1979, and Japanese Patent Publication No. 166175/1982.

A method for removing polychlorinated biphenyl and the like by utilizing the photocatalytic function of a titanium oxide catalyst is disclosed, for example, in Japanese Patent Publication No. 1995-000819. Japanese Patent Publication No. 000759/1996 describes an apparatus and a method for photodecomposing polychlorinated biphenyl. Here, for the purpose of removing the factors that inhibit photodecomposition, the factors that inhibit photodecomposition are limited to water and alkali metals, and an electrode is provided in the reaction tank as a mechanism for removing them, and a DC voltage is applied to the electrodes to inhibit the photodecomposition. The photodecomposition of polychlorinated biphenyls is performed while removing the factors that cause this. Although it has the advantage of being able to be decomposed under mild conditions, it is basically a photodecomposition and has not been able to overcome the conventional problems of photodecomposition. A method for decomposing a compound having a biphenyl skeleton by a microorganism is disclosed, for example, in Japanese Patent Publication No. Hei. However, the compounds which can be decomposed are limited depending on the assimilation ability of the microorganism used, and there are problems that must be solved, such as that the decomposition takes a relatively long time.

[0013]

SUMMARY OF THE INVENTION The inventors of the present invention have studied various methods for decomposing organic compounds as described above, and as a result, all of them have problems or are expected to have problems. From the above, it was concluded that a technique for decomposing organic compounds, which had fewer problems and was environmentally friendly, was necessary.

Further studies were conducted with the aim of achieving such a problem. As a result, a disinfection effect (Japanese Patent Publication No. Hei 1-180293) and a cleaning effect of contaminants on a semiconductor wafer (Japanese Patent Publication Hei 7-1995) were obtained. No. 51675))
It has been newly found that functional water obtained by electrolysis of water, for example, acidic water, which has been reported to have an organic compound, has excellent organic compound resolution.

The present invention has been made based on such new findings by the present inventors, and the object thereof is to be more environmentally friendly and to reduce the possibility that compounds produced by decomposition will cause new environmental pollution. It is another object of the present invention to provide a method for decomposing an organic compound which does not require various complicated controls accompanying the decomposition, and an apparatus used for the method.

It is another object of the present invention to provide a method for efficiently purifying exhaust gas containing an organic compound and an apparatus used for the method.

[0017]

According to an embodiment of the present invention, there is provided a method for decomposing an organic compound, wherein the hydrogen ion concentration (pH value) is more than 4 and less than or equal to 10 and an oxidation-reduction potential (action). (Electrode: platinum electrode, reference electrode: silver-silver chloride electrode) 300 mV or more and less than 800 mV, and chlorine concentration of 2
a step of contacting functional water of not less than 70 mg / liter and not more than 70 mg / liter with an organic compound.

An apparatus for decomposing an organic compound according to one embodiment of the present invention comprises a decomposition tank, a means for supplying functional water to the decomposition tank, and an organic compound to be decomposed to the decomposition tank. The functional water has a hydrogen ion concentration (pH value) of more than 4 and 10 or less and an oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) of 30
It is characterized by having a chlorine concentration of 0 to less than 800 mV and a chlorine concentration of 2 to 70 mg / liter.

In the exhaust gas purifying method according to one embodiment of the present invention, the exhaust gas containing an organic compound has a hydrogen ion concentration (pH value) of more than 4 and not more than 10 and an oxidation-reduction potential (working electrode: platinum electrode; see FIG. Electrode: silver-silver chloride electrode) is 30
The organic compound is characterized in that it has means for decomposing the organic compound by contacting it with functional water having a chlorine concentration of 0 to less than 800 mV and a chlorine concentration of 2 to 70 mg / liter.

An exhaust gas purifying apparatus according to one embodiment of the present invention is an exhaust gas purifying apparatus containing an organic compound, comprising an inlet and an outlet for exhaust gas and functional water, the inlet and the outlet. A reaction vessel filled with filler between
Means for introducing the exhaust gas into the reaction vessel and means for introducing the functional water into the reaction vessel, wherein the functional water has a hydrogen ion concentration (pH value) of more than 4 and not more than 10 and an oxidation-reduction potential (Working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) 300 mV or more and less than 800 mV, and chlorine concentration of 2
It is characterized in that it is not less than mg / liter and not more than 70 mg / liter.

(Operation of the Present Invention) The reason why various organic compounds are decomposed by the functional water as described above is not clear. However, for example, acidic water generated near the anode by electrolysis of water containing an electrolyte such as sodium chloride contains hypochlorous acid, or hypochlorite ion, and alkaline water generated near the cathode is Contains large amounts of sodium hydroxide or hydroxide ions. By appropriately mixing both, sodium hypochlorite is generated under mild pH conditions. It is considered that the organic compound is decomposed by the oxidizing power of sodium hypochlorite.

Japanese Patent Application Laid-Open No. 8-281271 discloses a technique for decomposing a dye in a dyeing wastewater in an electrolytic cell by hypochlorous acid and / or hypochlorite ions generated by electrolysis. In addition, magazine "Water Treatment Technology" Vol.37, N
o.5 (1996), page 33, describes the treatment of dyeing wastewater using an electrochemical reaction. In the indirect electrolysis method as a method of decomposing coloring component molecules of a dye by electrolysis, an oxidizing agent is generated by electrolysis, Its oxidizing power indirectly decomposes the dye, and most of the oxidizing agent used is hypochlorous acid, which is generated at the anode when sodium chloride is added to wastewater and electrolyzed It is described that chlorine gas is generated by a reaction with hydroxyl ions generated at a cathode. However, there is no description in these patent publications and magazines suggesting that halogenated aliphatic hydrocarbon compounds or aromatic compounds can be decomposed by these methods.

[0023]

DETAILED DESCRIPTION OF THE INVENTION The method for decomposing an organic compound according to one embodiment of the present invention is described in the following.
Hereinafter, the oxidation-reduction potential when the platinum electrode is the working electrode and the silver-silver chloride electrode is the reference electrode is 300 mV or more and 800 m or more.
Less than V and residual chlorine concentration is 2 mg / liter or more and 70 mg
A step of contacting the functional water to be decomposed with not more than / liter of functional water.

The organic compounds to be decomposed include, for example, halogenated aliphatic hydrocarbon compounds and aromatic compounds. Examples of the halogenated aliphatic hydrocarbon compound include an aliphatic hydrocarbon compound substituted with at least one of a chlorine atom and a fluorine atom. Specifically, for example, 1 to 4 chlorine substituted methane, 1 to 6 chlorine substituted ethane, 1 to 4 chlorine substituted ethylene, 1 to 2 chlorine substituted acetylene, 1 to 8 chlorine substituted propane , 1-6 chlorine-substituted propylene, 1-4 chlorine-substituted allene (propadiene), 1-4 chlorine-substituted arylene (methylacetylene), 1-10 chlorine-substituted butane, 1-,
2- or iso-butene substituted with 1 to 8 chlorine, 1,3-butadiene substituted with 1 to 6 chlorine, etc.), trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-
12), chlorotrifluoromethane (CFC-13), bromotrifluoromethane (CFC-13B1), carbon tetrafluoride (CFC-14), dichlorofluoromethane (CFC-21), chlorodifluoromethane (CFC-2)
2), trifluoromethane (CFC-23), 1,2-difluoro-1,1,2,2-tetrachloroethane, 1,1,2-trichloro-1,
2,2-trifluoroethane (CFC-113), 1,2-dibromo
-1-chloro-1,2,2-trifluoroethane (CFC-113B
2), 1,2-dichloro-1,1,2,2-tetrafluoroethane (CFC-114), 1,2-dibromo-1,1,2,2-tetrafluoroethane (CFC-114B2), 2 , 2-Dichloro-1,1,1-trifluoroethane (CFC-123), chlorodifluoroethane (CFC-142), 1,1-difluoroethane (CFC-15)
2), tetrafluoroethane, chloropentafluoroethane, hexafluoroethane (Flon-116) and the like. Furthermore, azeotropic mixtures of the above-mentioned compounds (for example, Freon-500, Freon-502), vinyl fluoride, vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, chlorotrifluoroethylene, propylene hexafluoride and the like can be mentioned. Other than the above, halogenated aliphatic hydrocarbons in which the carbon atom other than the above is an aliphatic hydrocarbon having up to three carbon atoms and the hydrogen atom is substituted with at least one halogen atom selected from a fluorine atom, a chlorine atom, a bromine atom and the like. .

Specific examples of the aromatic compound include cyclic or aromatic halogenated hydrocarbons such as benzene, phenol, benzotrifluoride, perfluorobenzene, and perfluoromethyldecalin.
Further, a compound having a biphenyl structure may be mentioned. Specific examples of the compound having a biphenyl structure include biphenyl, dehydrodivanillic acid, 2-chlorobiphenyl, 3-chlorobiphenyl, 4-chlorobiphenyl, 2,2'-dichlorobiphenyl, 3,3'-dichlorobiphenyl, 4'-dichlorobiphenyl, 2,4'-dichlorobiphenyl, 2,3-dichlorobiphenyl, 2,4-dichlorobiphenyl, 2,5-dichlorobiphenyl, 2,6-dichlorobiphenyl, 3,4-dichlorobiphenyl , 3,5-dichlorobiphenyl, 2,4,4'-trichlorobiphenyl, 2,2 ', 5-trichlorobiphenyl, 2,3', 5-
Trichlorobiphenyl, 2,4 ', 5-trichlorobiphenyl, 2', 3,4-trichlorobiphenyl, 2,3,4-trichlorobiphenyl, 2,3,6-trichlorobiphenyl, 2,4,5-trichlorobiphenyl, Examples thereof include 2,4,6-trichlorobiphenyl and the like. Further, a biphenyl-based compound in which a chlorine atom bonded to the above-mentioned compound is substituted with a fluorine atom or a bromine atom can also be decomposed.

In the functional water after the decomposition of the above-mentioned various compounds, no new generation of organic compounds which is considered to have an adverse effect on the environment at present is not observed at all even by, for example, an absorption spectrum.

The functional water is, for example, a hydrogen ion concentration (pH
Value is more than 4 and 10 or less, and the oxidation-reduction potential when the working electrode is a platinum electrode and the reference electrode is silver-silver chloride is 300.
Water with properties of not less than 800 mV and less than 800 mV and having a chlorine concentration of 2 mg / liter to 70 mg / liter. Such functional water can be obtained as an acidic water at the anode side by electrolyzing an aqueous solution in which a water-soluble electrolyte substance (eg, sodium chloride, potassium chloride, etc.) is dissolved through an ion exchange membrane or the like. On the side can be obtained as alkaline water. Functional water can also be obtained by mixing acidic water obtained on the anode side and alkaline water obtained on the cathode side. When acidic water and alkaline water are mixed to obtain functional water, the mixing ratio of acidic water and alkaline water is preferably, for example, 1: 0 to 1: 1 by volume ratio, but functional water having the above properties can be obtained. However, the mixing ratio is not necessarily required.

Here, the concentration of the electrolyte in the raw water before electrolysis is desirably 20 mg / l to 2000 mg / l for sodium chloride, for example, and the electrolytic current value at that time is desirably 2 A to 20 A. Also, at this time, when a diaphragm is arranged between the pair of electrodes,
Mixing of acidic water generated in the vicinity of the anode and alkaline water generated in the vicinity of the cathode can be prevented, and acidic water capable of decomposing organic compounds more efficiently can be obtained. As the diaphragm, for example, an ion exchange membrane is preferably used. As a means for obtaining such functional water, a commercially available strongly acidic electrolyzed water generator (for example, trade name: Oasis Bio Half; manufactured by Asahi Glass Engineering Co., Ltd.) can be used.

The functional water having the above properties can be prepared not only by electrolysis but also by dissolving various reagents in raw water. For example, it can be obtained by using 0.001 N to 0.1 N hydrochloric acid, 0.001 N to 0.1 N sodium hydroxide, and 0.0005 M to 0.01 M sodium hypochlorite. Here, the raw water includes pure water, tap water, river water, seawater, and the like. The pH of these waters is usually 6 to 8, the oxidation-reduction potential is -200 mV to 300 mV, and the chlorine concentration is at most about 1 mg / l. Such raw water naturally has the resolution of organic compounds as described above. I do not have.

An organic compound decomposer which can be used for decomposing an organic compound using functional water will be described below. In the present embodiment, the contact between the functional water and the organic compound may be performed at normal temperature and normal pressure, and no special equipment or environment is required.
For example, it is only necessary to introduce an organic compound or a medium containing an organic compound into a container storing functional water, or it is only necessary to introduce an organic compound or a medium containing an organic compound into a water tank in which functional water is produced. Examples of the configuration of the organic compound decomposition apparatus include the following 1) and 2).

1) Organic to be decomposed into an electrolyzed water generator
Organic compounds and acidic water
Configuration was set to contacting the door; Figure 1 is a schematic view of one embodiment of apparatus for decomposing organic compounds according to the present invention. In FIG. 1, reference numeral 101 denotes a water tank. And the water tank is a cathode 103
And a membrane 107 composed of an anode 105, an ion exchange membrane and the like,
A power supply 109 connected to the electrodes, a pipe 111 and a pump 113 for supplying water containing an electrolyte into the water tank, a pipe 115 and a pump 117 for supplying an organic compound to be decomposed or a medium containing the same to the water tank. With
Reference numeral 119 denotes a tank for storing functional water that has lost activity due to the reaction with the organic compound in the water tank 101. And water tank 10
The water having the electrolyte dissolved therein is supplied through a pipe 111 to fill the water tank 101 with the water having the electrolyte dissolved therein. When power is supplied from the power supply 109 to the electrodes 103 and 105 for electrolysis, acidic water is generated on the anode 105 side. The organic compound is continuously supplied from the pipe 115 at a desired flow rate to the water tank 10.
1 is supplied to the anode 105 side. Here, the organic compound comes into contact with functional water and is decomposed. The functional water deactivated by the reaction with the organic compound is discharged from the water tank 101 to the tank 119 through the drain pipe 118. The organic compound is contained as a gas in air or the like,
5, the purified air is discharged from the exhaust port 121. The water discharged into the tank 119 may be configured to dissolve the electrolyte again and supply the dissolved electrolyte to the water tank 101.

As the diaphragm 107, for example, the cathode 10
The electrolyte solutions on the 3rd side and the anode 105 side are not moved to the opposite sides, respectively, and the cations (for example, Na ⁺ ,
Ca ²⁺ , Mg ²⁺ , K ^+, etc., allow irreversible movement to the cathode side, and anions (eg, C 2
An ion exchange membrane that allows irreversible movement of l ⁻ , SO ₄ ²⁻ , HCO ₃ ^{− and the} like to the anode side is preferably used. That is, by using the ion exchange membrane, it is possible to efficiently generate functional water having the above-described characteristics near the anode.

When the medium containing an organic compound is water or the like,
By controlling the amount of water in which the electrolyte is dissolved or the concentration of the electrolyte and the amount of the solution containing the organic compound, etc., so that the electrolyte solution in the water tank 101 is not excessively diluted by this solution, the characteristic of the acidic water generated by the electrolysis is controlled. Is preferably controlled to fall within the above range. For this reason, if the organic compound to be decomposed is easily vaporized (specifically, for example, trichloroethylene or tetrachloroethylene), and if it is contained in an aqueous medium such as water, this medium It is preferable to vaporize the organic compound by aeration or the like in advance and to introduce the vaporized organic compound into the water tank, instead of directly introducing the compound into the water tank. If the vaporized organic compound is bubbled in functional water, chlorine in the functional water may be released as chlorine gas and the properties of the functional water may change. It is preferable to adopt a configuration in which functional water is continuously generated, or a configuration in which functional water is continuously supplied.

FIG. 2 is a schematic view of one embodiment of a decomposition apparatus in which the decomposition target is a gaseous organic compound. In FIG. 2, 123 is a functional water generator, 125 is an introduction pipe for introducing an organic compound into the functional water generator 123, 1
27 is a standard gas generator for supplying air containing an organic compound, 129 is a tank for storing an aqueous electrolyte solution, 131 and 133 are tubes and pumps for supplying an aqueous electrolyte solution from the tank 129 to the functional water generator 123, 121 is An exhaust port for purified gas.

FIG. 3 is a schematic view of an embodiment of the decomposition apparatus when the organic compound is dissolved in a liquid or liquid medium. In FIG. 3, reference numeral 137 denotes a tank for storing a liquid organic compound or a liquid medium in which the organic compound is dissolved, and 139 and 141 denote pipes and pumps for supplying the liquid stored in 137 to the functional water generator 123.

2) The functional water created by the electrolyzed water generator is separated
The organic compound is introduced into the decomposition tank,
Configuration was set to contacting the person; Figure 4 is a schematic view of another embodiment of apparatus for decomposing organic compounds. Functional water generator 1
The functional water generated by 23 is continuously supplied at a desired flow rate to the decomposition tank 143 via the pump 145 and the pipe 147. The organic compound, for example, gasified chlorinated aliphatic hydrocarbon is continuously supplied to the decomposition treatment tank 143 at a desired flow rate through the supply pipe 115 and the pump 117. The chlorinated aliphatic hydrocarbon compound comes into contact with the functional water in the decomposition treatment tank 143, and the decomposition treatment proceeds. The functional water used in the treatment is discharged from the decomposition treatment tank 143 to the tank 119.
The purified gas is discharged from the discharge pipe 121. After the functional water is generated by the functional water generator 123, the decomposition tank 143 is generated.
In this configuration in which the functional water and the organic compound are brought into contact with each other, the organic compound is not introduced into the functional water generator, so that contamination of the functional water generator can be prevented. Although not shown, tank 1
A part or all of the functional water used in the treatment, which is discharged to 19, may be supplied to the functional water generator 123 to be reused for generating new functional water.

FIG. 5 is a schematic view of still another embodiment of the organic compound decomposing device, in which functional water generated by the functional water generating device 123 is supplied to a decomposing tank 143 via a pump 145 and a pipe 139. . On the other hand, a pump 131 and a pipe 133 are provided from a tank 137 storing a liquid organic compound or a liquid medium in which the organic compound is dissolved.
The organic compound is supplied to the decomposition treatment tank 143 via.
Then, the inside of the decomposition treatment tank is stirred by the stirrer 149, and the organic compound comes into contact with the functional water to decompose the organic compound. By providing the stirring means related to the decomposition treatment tank 143, the contact efficiency between the organic compound and the functional water can be improved, and the decomposition efficiency of the organic compound can be further improved.

FIG. 6 is a schematic view of another embodiment of the organic compound decomposing device, which is a device assuming that the organic compound to be decomposed is easily vaporized such as trichloroethylene. 6, reference numeral 123 denotes a functional water generator, 151
-1 to 151-5 are column-shaped organic compound decomposition tanks (reaction columns), 139 and 145 are functional water generators 12 respectively.
3 shows a pipe and a pump for supplying the functional water generated in 3 to the decomposition vessel 151-1. In FIG. 6, the five decomposition tanks 151 are connected in series so that the organic compound and the functional water are in contact for a longer time, and the first to fourth decomposition tanks 1 are connected.
Organic compounds that have not been decomposed in 51-1 to 151-4 can be more completely decomposed by successively contacting them with acidic water in a downstream decomposition tank. The number of decomposition tanks to be connected can be appropriately selected depending on the concentration of the organic compound, ease of decomposition, and the like.

When the organic compound is in a gaseous state, the contact area between the functional water and the organic compound can be reduced while adopting an apparatus configuration as shown in FIG.
It is possible to increase the contact time. That is, in FIG. 7, reference numeral 151 denotes a reaction column, the inside of which is filled with, for example, a filler 157 which increases the surface area of gas-liquid contact. 159 is a pipe provided with means for introducing the vaporized organic compound into the reaction column 151, for example, a pipe provided with a blower 128, 123 is a functional water generator, and 153 is a storage tank for the functional water obtained by the functional water generator 123. .
The functional water stored in the storage tank 153 is dropped into the reaction column 151 from above the reaction column 151 by the pump 155. In this way, the gaseous organic compounds are introduced into the reaction column 151 from the top of the reaction column 151, respectively. Functional water is supplied to reaction column 151
The organic compound is decomposed by flowing down the filler therein and coming into contact with the gaseous organic compound. As described above, the filler that can be used is not particularly limited as long as it can increase the contact area between the functional water and the organic compound. For example, a porous material formed of an inorganic material or an organic material, a hollow material, or the like can be used. And a spherical body. Various particles used in the chemical industry, pharmaceutical industry, food industry, wastewater treatment system, and the like can be used.

(Regarding Treatment of Exhaust Gas) As is clear from the above-mentioned various device configurations, according to the various embodiments of the present invention, gaseous organic compounds can be decomposed. The present invention can also be effectively applied to purification of exhaust gas discharged from a combustion furnace or a waste incinerator in a factory or the like.

Combustion gases emitted from factories and garbage incineration plants contain many organic compounds such as soot, and fine dust causes respiratory illness. Benzpyrene and dioxin have strong carcinogenic properties. Because of its mutagenic properties, purification of exhaust gas is a very important technical issue.
Conventionally, measures to remove such harmful organic substances include dust collection, denitration,
Processing operations such as desulfurization and / or desalination are performed by a method of individually and stepwise processing organic substances using, for example, an exhaust gas treatment device connected in series. For example, Japanese Patent Publication No. 115722/1993 discloses a purification method in which a ceramic such as zeolite is used as an exhaust gas filter and the mechanical strength, impact resistance, or efficiency of collecting organic substances is increased. In each case, since the purification treatment is performed only by the filtration effect, relatively large soot and the like can be collected, but molecular organic matter can hardly be removed.

On the other hand, there have been proposed many purification devices for treating organic substances in exhaust gas by bringing them into contact with a catalyst. For example, Japanese Patent Publication No. 149127/1993 discloses a method and an apparatus for detoxifying harmful organic substances such as soot and dioxin in exhaust gas by using an oxidation catalyst and a heating device therefor. The scale of the equipment depends on the amount of exhaust gas to be treated and the amount of organic matter contained in it, but extraction of contaminated gas from incinerators and soil
Since 50 to 500 m ³ / h of exhaust gas is discharged, the exhaust gas treatment facility requiring a heating device becomes considerably large-scale, and the operation cost becomes enormous. In addition, Japanese patent publication 1994
No. 33 describes a method in which corona discharge is generated in exhaust gas to thermally decompose organic substances. In any case, particles such as low-molecular to high-molecular organic substances and soot can be decomposed and made harmless. However, as in the case of the above-described catalyst decomposition, the concentration of harmful organic substances in the supplied exhaust gas changes over time, and it is necessary to maintain the heating or high-frequency irradiation or corona discharge of the catalyst even in the case of low-concentration pollution, There is a problem with energy efficiency for purification. Furthermore, it is difficult to purify a high concentration by the above-described oxidation treatment of organic substances,
It is also necessary to reduce the processing load by arranging the purification devices in parallel or in series.

As a method of purifying exhaust gas which is more economical and has less environmental load, a treatment method and apparatus using microorganisms have been proposed. For example, U.S. Pat. No. 4,090,099 describes a method of removing and purifying soot and gaseous pollutants in exhaust gas by decomposing the microorganisms with microorganisms. No. 54
No. 94574 describes a method of filling a purification reaction vessel with a microorganism-immobilized filler and circulating it in the reaction vessel, and purifying contaminated water and gas containing harmful organic substances through this reaction vessel. Have been. However, the organic matter that can be decomposed by the assimilation ability of the microorganism used is limited, and the decomposition requires a relatively long time.

In contrast to such a conventional technique, the present embodiment can efficiently decompose the organic compound only by bringing the organic compound into contact with functional water as described above. It is expected that some of the organic compounds in the exhaust gas will be surely decomposed just by contacting the gas with the functional water, and this will be a very effective technique for purifying the exhaust gas. When the technique for decomposing an organic compound according to the present embodiment is applied to the purification of exhaust gas, it is preferable to use the above-described apparatus having the configuration shown in FIG. 7 or the apparatus having the configuration shown in FIG. 8 described below. It is considered possible.

In FIG. 8, reference numeral 161 denotes a garbage incinerator;
Is a device for removing soot and dust in the exhaust gas emitted from the refuse incinerator (for example, an electrostatic precipitator), 123 is a functional water generator, and 165 is a reaction tank of functional water and exhaust gas from which dust has been removed. is there. The aqueous electrolyte solution storage means 129 stores an aqueous electrolyte solution (a solution obtained by dissolving a water-soluble electrolyte in raw water) necessary for generating functional water. The dust removing device 163 mainly removes dust contained in exhaust gas generated at the time of incineration of refuse, and the collected dust can be taken out. Reference numeral 123 denotes a functional water generating unit. Functional water obtained near the anode of the functional water generating unit 123 is configured to be supplied to the reaction tank 165.
Further, the reaction tank 165 is configured so that the exhaust gas and the functional water efficiently come into contact with each other, and the exhaust gas from which the organic compound has been removed and which has been purified is supplied to the gas discharging means 121 of the reaction tank 165.
Is provided. Next, the exhaust gas removing step having this configuration will be described. Exhaust gas from the refuse incinerator 161 is first introduced into the dust collecting device 163, and most of the soot is removed by this device. Further, the aqueous solution of the electrolyte is supplied from the tank 129 to the functional water generating means 123, and is subjected to the electrolytic treatment in the functional water generating means 123. Then, the functional water generated near the anode of the functional water generating means 123 is sent to the reaction tank 165. In the reaction tank 165, the exhaust gas and the functional water are mixed in contact with each other, so that the organic compounds in the exhaust gas are decomposed and the exhaust gas is purified. Next, the treated exhaust gas is discharged from the exhaust port 121.
The discharged functional water used for treating the organic compound is also discharged from the drain pipe 118. When the exhaust gas treatment device for a refuse incinerator according to this basic configuration was actually applied to exhaust gas treatment, 99 to 99.7% of organic chlorine compounds were decomposed and removed. From this, it is apparent that the present basic configuration has extremely excellent exhaust gas purification processing ability. 7 and 8
In the case where the apparatus having the configuration shown in (1) is used for purifying exhaust gas, part or all of the functional water used in the treatment discharged from the reaction column 151 and the reaction tank 165 is modified to be used for generating new functional water. (Not shown). That is, a configuration may be adopted in which part or all of the functional water used in the processing discharged from the reaction column 151 and the reaction tank 165 is returned to the electrolyzed water generating means 129. The functional water used for decomposing the organic compounds in the exhaust gas in the apparatus having the structure shown in FIGS. 7 and 8 is discharged as drain water from the drain pipe 118. When a substance is contained, a treatment such as filtration or precipitation may be further performed. When purifying the exhaust gas using the apparatus shown in FIG. 7, the supply rates of the functional water and the exhaust gas are adjusted so that the volume fraction of the exhaust gas in the reaction column becomes 0.5 or more, and the gas-liquid contact is performed. It is preferable to increase the area and increase the average residence time of the exhaust gas.

Although various embodiments according to the present invention have been specifically described above, it is needless to say that the present invention is not limited to these embodiments. For example, the processing apparatus of the present invention is not limited to exhaust gas from a garbage incinerator, but can also be used for processing general exhaust gas (eg, exhaust gas from automobiles).

Hereinafter, the present invention will be described in detail with reference to Examples.
They do not limit the invention in any way.

[0048]

EXAMPLES (Example 1) Decomposition of trichlorethylene by functional water First , functional water was prepared using a strongly acidic functional water generator (trade name: Oasis Bio Half; manufactured by Asahi Glass Engineering Co., Ltd.). Note that a diaphragm is provided between the anode and the cathode. Using this device, the electrolyte concentration of the water to be electrolyzed is varied, and the pH and oxidation-reduction potential of the acidic functional water obtained on the anode side are measured with a pH meter (Toko Chemical Laboratory, TCX-90i And KP900-2
N) and conductivity meter (Toko Chemical Laboratory, TCX)
-90i and KM900-2N), and the chlorine concentration was measured with chlorine test paper (Advantech). As a result, the concentration of sodium chloride as the electrolyte (standard concentration was 1000 mg /
l) The function water p depends on electrolysis current value, electrolysis time, etc.
H varied from 1.0 to 4.0, the redox potential varied from 800 mV to 1500 mV, and the chlorine concentration varied from 5 mg / l to 150 mg / l. The pH of the alkaline functional water obtained on the cathode side is 10 to 13, the oxidation-reduction potential is -1000 to 800 mV,
The chlorine concentration was 5 mg / liter.

Therefore, in this embodiment, functional water having a pH of 5, an oxidation-reduction potential of 400 mV, and a chlorine concentration of 20 mg / liter (hereinafter referred to as “functional water 1”) is used as a functional water used in an organic compound decomposition experiment.
And functional water (hereinafter abbreviated as “functional water 2”) having a pH of 10, an oxidation-reduction potential of 620 mV, and a chlorine concentration of 20 mg / liter. The functional water 1 was obtained by mixing the functional water obtained on the anode side and the functional water obtained on the cathode side at a ratio of 1: 0.1. Functional water 2 was obtained by mixing acidic water and alkaline water at a ratio of 1: 1.

Next, a plurality of glass vials having a capacity of 27.5 ml were prepared, divided into two groups (group 1 and group 2), and 10 ml of functional water 1 was added to each glass vial of group 1; 10 ml of functional water 2 was put into each glass vial of No. 2, and all the glass vials were sealed with a butyl rubber stopper with a Teflon liner and an aluminum seal. Next, TC in the glass vial
TCE gas was added to all glass vials through a butyl rubber stopper with a gas-tight syringe so that the TCE concentration when all E was dissolved in functional water was 25 ppm. This is 15
The mixture was shaken at 120 ° C. and 120 rpm, and the change over time in the TCE concentration of the gas phase portion in the glass vial of each group was measured. The TCE concentration of the gas phase in the glass vial was measured by sampling the gas phase of the glass vial with a gas tight syringe and measuring the TCE concentration by gas chromatography (manufactured by Shimadzu Corporation, GC with FID detector). -14B and the column were measured with J & W DB-624). From this gas phase TCE concentration, the TCE concentration when all the TCE in the glass vial was completely dissolved in the functional water was determined over time. FIG. 9 shows the result.

From this, it takes several hours to several tens of hours depending on the functional water.
It was found that TCE could be completely degraded. Also different p
It was confirmed that TCE could be decomposed in functional water with H, redox potential, and residual chlorine concentration. Furthermore, in a control experiment using pure water, no decomposition of TCE was observed, and it was confirmed that decomposition occurred with functional water. Furthermore, TCE for functional water with different pH, redox potential and chlorine concentration
When the degradation was evaluated, a decrease in the concentration of TCE over time was observed in all cases, and TCE degradation by functional water was confirmed.

(Example 2) Decomposition of tetrachlorethylene by functional water Decomposition of PCE by functional water 1 and functional water 2 in the same manner as in Example 1 except that TCE was changed to tetrachloroethylene (PCE) and the initial concentration was changed to 5 ppm. The properties were evaluated. As a result, as shown in FIG. 10, a remarkable decrease in the concentration of PCE was observed. On the other hand, in a control experiment using pure water, no decomposition of PCE was observed, which confirmed that the decomposition of PCE was due to functional water. Furthermore, the functional water having different pH, oxidation-reduction potential, and chlorine concentration was evaluated for the PCE decomposition characteristics. As a result, a time-dependent decrease in the PCE concentration was observed, and the PCE decomposition by the functional water was confirmed.

Example 3 Decomposition of chloroform with functional water Chloroform was used instead of TCE, and the initial concentration was 10 p.
Except for pm, the degradation characteristics of chloroform with functional water 1 and functional water 2 were evaluated in the same manner as in Example 1. As a result, as shown in FIG. 11, a remarkable decrease in the residual concentration of chloroform was observed. In a control experiment using pure water, no decomposition of chloroform was observed, indicating that the decomposition of chloroform was due to functional water. Furthermore, when the decomposition of chloroform was evaluated for functional water having different pH, oxidation-reduction potential, and chlorine concentration, a decrease in chloroform concentration over time was observed in all cases, and the decomposition of chloroform by the functional water was confirmed.

[0054]

According to the present invention, it is possible to stably decompose organic compounds economically, safely and stably at normal temperature and normal pressure. In addition, it is easy to purify exhaust gas containing organic compounds,
In addition, it is possible to perform stably.

[Brief description of the drawings]

FIG. 1 is a schematic view of an organic compound decomposition apparatus according to one embodiment of the present invention.

FIG. 2 is a schematic view of an organic compound decomposition apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic view of an organic compound decomposing apparatus according to another embodiment of the present invention.

FIG. 4 is a schematic view of an organic compound decomposition apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic view of an organic compound decomposition apparatus according to another embodiment of the present invention.

FIG. 6 is a schematic view of an apparatus for decomposing gaseous organic compounds according to another embodiment of the present invention.

FIG. 7 is a schematic view of an apparatus for decomposing gaseous organic compounds according to another embodiment of the present invention.

FIG. 8 is a schematic diagram of an exhaust gas purifying apparatus according to an embodiment of the present invention.

FIG. 9 is a graph showing the change over time of the TCE concentration in Example 1.

FIG. 10 is a graph showing the change over time in the residual PCE concentration in Example 2.

FIG. 11 is a graph showing the change over time in the concentration of residual chloroform in Example 3.

[Explanation of symbols]

101 Water tank 103 Negative electrode 105 Positive electrode 107 Diaphragm 109 Power supply 111, 115, 133, 139, 159 Pipe 113, 117, 131, 141, 145, 155 Pump 118 Drain pipe 119 Waste liquid tank 121 Exhaust port 123 Functional water generator 125 Introduced Pipe 127 Standard gas generator 128 Blower 129 Electrolyte aqueous solution storage means 137 Organic compound-containing liquid storage tank 143 Decomposition treatment tank 149 Stirrer 151 Reaction column 153 Storage tank 157 Filler 161 Dust incinerator 163 Dust removal device 165 Reaction tank

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Sakunaga 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kinya Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor: Akira Kuriyama, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor: Etsuko Sugawa 3-2-2, Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (12)

[Claims] 1. The hydrogen ion concentration (pH value) exceeds 4 to 10
Hereinafter, functional water having an oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) of 300 mV or more and less than 800 mV and a chlorine concentration of 2 mg / liter to 70 mg / liter is defined as an organic compound. A method for decomposing an organic compound, comprising a step of contacting. 2. The decomposition method according to claim 1, wherein the organic compound is a halogenated aliphatic hydrocarbon compound. 3. The method according to claim 2, wherein the halogenated aliphatic hydrocarbon compound is a chlorinated aliphatic hydrocarbon compound. 4. The chlorinated aliphatic hydrocarbon compound is a chlorosubstituted methane of 1-4 ethane, a chlorinated ethane of 1-6 chloroethane, a chlorinated ethylene of 1-4 chloromethane or a chlorostyrene of 1-2 acetylene. , 1 to 8 chlorine substituted forms of propane, 1 to 6 chlorine substituted forms of propylene, 1 to 4 chlorine substituted forms of allene (propadiene), 1 to 4 chlorine substituted forms of allylene (methylacetylene), 1 of butane
The decomposition method according to claim 3, which is at least one of a -10 to 10 chlorinated product, a 1 to 8 chlorinated product of 1-, 2- or iso-butene, and a 1 to 6 chlorinated product of 1,3-butadiene. 5. The method according to claim 3, wherein the chlorinated aliphatic hydrocarbon compound is at least one of trichloroethylene, tetrachloroethylene and chloroform. 6. The decomposition method according to claim 1, wherein said functional water is obtained in the vicinity of a cathode when electrolyzing water to which a water-soluble electrolyte is added. 7. The method according to claim 6, wherein said electrolyte is selected from sodium chloride and potassium chloride. 8. The decomposition method according to claim 1, wherein the functional water is a mixed water obtained by mixing acidic water obtained on the anode side and alkaline water obtained on the cathode side in electrolysis. 9. The mixing ratio of said acidic water and said alkaline water is 1:
The decomposition method according to claim 8, wherein the ratio is 0 to 1: 1. 10. A decomposition treatment tank, means for supplying functional water to the decomposition treatment tank, and means for supplying an organic compound to be decomposed to the decomposition treatment tank, wherein the functional water has a hydrogen ion concentration ( pH value is more than 4 and 10 or less, and the oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) is 30.
An organic compound decomposer characterized by having a chlorine concentration of 2 mg / L or more and 70 mg / L or less, from 0 mV to less than 800 mV. 11. An exhaust gas containing an organic compound has a hydrogen ion concentration (pH value) of more than 4 and not more than 10 and an oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) of 300 mV to 800 mV. And the chlorine concentration is 2 mg /
A method for purifying exhaust gas, comprising means for contacting with functional water of not less than 1 liter and not more than 70 mg / liter to decompose the organic compound. 12. A reaction vessel for purifying an exhaust gas containing an organic compound, comprising: an inlet and an outlet for exhaust gas and functional water, wherein a space between the inlet and the outlet is filled with a filler; Means for introducing the exhaust gas into the reaction vessel, and means for introducing the functional water into the reaction vessel, wherein the functional water has a hydrogen ion concentration (pH value) of more than 4 and not more than 10;
Purification of exhaust gas characterized in that the oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) is 300 mV or more and less than 800 mV, and the chlorine concentration is 2 mg / l to 70 mg / l. apparatus.