JP2001334262A - Organic compound decomposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for decomposing organic compounds which can decompose/detoxify the compounds in a solution without isolating/removing them. SOLUTION: In the method, the organic compounds in the aqueous solution are decomposed by being irradiated with radiation in the presence of a solid material. The solid material emits secondary electrons and/or light by being irradiated with the radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for decomposing an organic compound, and more particularly, to a method for decomposing an organic compound using radiation.

[0002]

2. Description of the Related Art In recent years, endocrine disruptors (environmental hormones)
The influence of organic compounds on living organisms has become a major problem. For this reason, decomposition and detoxification of organic compounds have been studied to reduce the effects on living organisms. For example, decomposition of harmful substances in wastewater using a photocatalyst such as TiO ₂ (titanium dioxide) is known.

[0003]

However, since the effects of environmental hormones are remarkable even in a very small amount, an extremely small amount in the environment must be treated. Various attempts have been made, such as adsorption removal using an adsorbent and adsorption decomposition using a catalyst, but a definitive method for decomposing organic compounds has not yet been known.

In addition, in the method of decomposing an organic compound using TiO ₂ (titanium dioxide), it is difficult to treat an opaque solution such as a suspension because irradiation with ultraviolet light or visible light is required. In addition, there is a problem that the dissolution of the catalyst in the wastewater proceeds with the decomposition of the harmful substance, and the catalyst is deteriorated. In order to further improve the decomposition efficiency, the conventional photocatalyst often uses a solid powder having a large surface area or a sintered body thereof. For this reason, it was almost impossible to recover or reuse the catalyst from the wastewater after the decomposition reaction. Therefore, it has been desired to remove the organic compound or decompose the organic compound by another method without using such a catalyst. However, a method for decomposing such an organic compound has not been known so far.

Accordingly, an object of the present invention is to provide a method for decomposing an organic compound which can decompose and detoxify an organic compound in a solution without separating and removing the organic compound.

[0006]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have made effective use of radiation energy to produce endocrine disrupting substances (environmental hormones) present in an aqueous solution in the presence of a solid material. It has been found that harmful organic compounds can be decomposed and made harmless without separation and removal from the solution.

The method for decomposing an organic compound according to the present invention is characterized in that an organic compound dissolved in an aqueous solution is decomposed by irradiating radiation in the presence of a solid material containing a metal.

In a preferred embodiment of the present invention, the metal-containing solid material is a material that emits secondary electrons and / or light.

In a preferred embodiment of the present invention, the organic compound is decomposed by secondary electrons and / or light obtained by irradiating a solid material containing a metal with radiation.

In a preferred embodiment of the present invention, the metal is at least one selected from the group consisting of iron, copper, aluminum, nickel, lead, molybdenum, tungsten, platinum, gold and rare earth elements. It is characterized by the following.

In a preferred embodiment of the present invention, the radiation is at least one selected from the group consisting of X-rays, α-rays, β-rays, γ-rays, electron beams, neutron beams, and particle beams.
It is characterized by one kind.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The method for decomposing an organic compound according to the present invention decomposes an organic compound present in an aqueous solution, particularly in a drainage or drainage solution, by irradiating radiation in the presence of a solid material. The drainage or drainage solution may be transparent or opaque. This is because γ-rays, electron beams, or various types of radiation from radioactive waste have a significantly higher transmittance than ultraviolet and visible light, so that opaque solutions can be treated. The organic compound is preferably dissolved in an aqueous solution such as wastewater, but may be in a suspended state.

In general, the organic compound means a carbon compound excluding a small number of simple compounds such as carbon monoxide and carbon dioxide. However, the organic compound to be decomposed in the present invention includes all of these organic compounds. Compounds are included and are not particularly limited. According to the present invention, the compound effectively decomposes and acts particularly on an organic compound having a benzene ring. Here, a description will be given of harmful organic compounds that have a bad influence on the environment, but the present invention is not intended to be limited to these organic compounds.

Specifically, for example, as the organic compound,
Examples include organic compounds such as phthalates, dioxins, PCBs, DDT, phenols, and environmental hormones such as organic halogen compounds.

In general, as radiolysis, conversion of para-hydrogen into ortho-hydrogen by α-rays (H ·> + pH → oH ₂ +
H), there are decomposition reactions of O ₃ , N ₂ O, NO, CO and CO ₂ by α rays and γ rays. In addition, CH bond of hydrocarbon by radiation, CC
Breaking bonds is known. Since direct decomposition by these radiations is inefficient as it is, in the present invention,
The following points were tried to decompose efficiently.

That is, (1) to convert radiation into secondary electrons or light having a strong chemical effect, and (2) to efficiently decompose the organic compound after increasing the concentration of the organic compound using an adsorbent. It is. In order to perform these two points simultaneously, a solid material that emits secondary electrons or light by irradiating radiation is immersed or dispersed in water, an organic compound is adsorbed on the surface of the solid material, and the solid material is generated by irradiation. It is decomposed and rendered harmless using secondary electrons.

That is, the method for decomposing an organic compound according to the present invention comprises the following steps: 1) radiation itself cleaves a CH bond or a CC bond of a hydrocarbon; 2) radiation is converted into electrons or light by a solid material; 3) Radiation, or electrons or light generated by the interaction of radiation and solids, transforms water into OH radicals, and the OH radicals convert CH bonds and CC bonds. , And the decomposition is promoted by a synergistic effect of any one of the above (1) to (3). In addition, the adsorption is based on physical adsorption and chemical adsorption, and in the present invention, by the action of these adsorptions, the organic compound is concentrated on the solid material,
The organic compound can be efficiently decomposed.

The solid material used in the present invention is not particularly limited. The form of the solid material is not particularly limited, such as a powder form, a plate form, and a bulk form. From the viewpoint of facilitating the adsorption of the organic compound, a solid material having a large surface area is preferable.
Also preferably, the solid material is a material that emits secondary electrons and / or light. Secondary electrons generally mean electrons that are emitted from a solid by receiving the kinetic energy of incident electrons when electrons are injected into the solid from the outside.
Here, it means a broad concept including electrons emitted from a substance by irradiation of radiation or particle beams.

Light emitted by irradiation with radiation includes ultraviolet light, visible light, and the like. The emitted light can promote the decomposition of the organic compound as well as the secondary electrons.

The metals contained in the solid material include:
It may be in any state of a simple substance or an alloy, and includes a metal oxide and the like. Alkali metals,
All metals such as alkaline earth metals, metals of Groups 3 to 5, transition metals and the like can be mentioned. From the viewpoint of a high emission rate of secondary electrons (including Compton electrons) or light, an element having a large mass number is preferable as the metal.

From the viewpoint of availability and stability in water, the metal is preferably selected from the group consisting of iron, copper, aluminum, nickel, lead, tungsten, molybdenum, platinum, gold and rare earth elements. At least one of them. These metals can be used alone or in combination as a solid material.

As the radiation, at least one selected from the group consisting of X-rays, α-rays, β-rays, γ-rays, electron beams, neutron beams, and particle beams can be used. From the viewpoint of efficiently emitting secondary electrons from the solid material, the radiation preferably includes X-rays and γ-rays.

The absorbed dose of radiation varies depending on the type and size of the organic compound to be decomposed, and is not particularly limited. The radiation amount can be appropriately set according to the degree of water pollution. When the degree of contamination is light, the decomposition of the benzene ring is confirmed by radiation of several Gy, so that even a few Gy is effective. At a radiation dose of 10 Gy to 50 kGy, most organic compounds can usually be decomposed and rendered harmless. However, depending on the degree of water pollution,
It is also possible to increase this radiation dose.

In irradiating the organic compound with radiation, the container for containing the aqueous solution containing the organic compound is not particularly limited. This is due to the fact that radiation is significantly more transparent than ultraviolet and visible light. For example, it is not limited to a transparent container made of glass, and an opaque container made of metal can also be used.

[0025]

Here, one embodiment of the present invention will be described. However, the present invention is not construed as being limited to the following embodiment.

Example 1 Dibutyl 17 phthalate, one of the representative examples of environmental hormones
10 ml of water in which ppm was dissolved was sealed in a Pyrex (registered trademark) glass container or a stainless steel container, and γ-ray irradiation was performed at room temperature using a cobalt 60 irradiation device.
Decomposition by γ-rays was confirmed by gas chromatography, and disappearance and decomposition of benzene ring and carbonyl group which function as environmental hormones were confirmed by ultraviolet absorption spectroscopy. As a result, within 5 minutes (0.75 kGy) after the start of irradiation, 44% of the Pyrex glass container and 97% of the stainless steel container decomposed dibutyl phthalate. In contrast, no degradation of dibutyl butyrate occurred without irradiation. Thus, it was also found that the decomposition of dibutyl butyrate by radiation was very effective, and the effect was higher in the case of a metal container.

Example 2 The same 17 ppm aqueous solution of dibutyl phthalate as in Example 1 was used.
ml was sealed in a stainless steel container and irradiated with γ rays under the same conditions. About 5 minutes after the start of irradiation, decomposition of the benzene ring, which is a characteristic of environmental hormones, occurred. When irradiation was continued for several hours, dibutyl phthalate was decomposed into small molecules having a small number of carbon atoms.

Example 3 Next, in order to confirm the promotion of adsorption and decomposition by secondary electrons, materials having different masses (stainless steel) (S
S), aluminum (Al), nickel (Ni), molybdenum (Mo), tungsten (W), lead (Pb))
Was immersed in water in which environmental hormones were dissolved, and the effects were compared. 10 ml of the same 17 ppm aqueous solution of dibutyl phthalate as in Example 1 and 50 × 10 × 0.2 m of various metal pieces
m6 sheets were placed in a Pyrex glass container, sealed, and γ-irradiated. With respect to the aqueous solution after irradiation, the decomposition rate was measured by gas chromatography, and the ultraviolet absorption (UV) spectrum was measured to obtain information on decomposition products.

The results are shown in Table 1. In the table, the rate of change is shown per metal atom. As shown in Table 1, the decomposition of dibutyl phthalate was accelerated especially when a metal piece having a large atomic number was inserted. For example, when comparing the case of putting a piece of stainless steel and the case of putting a metal such as molybdenum, tungsten, lead, etc., the decomposition rate per metal atom of the latter,
It improved about 2.5 to 5 times of the former. As a conventional example, when a typical photocatalyst, TiO ₂ , was applied to the present system, no improvement in the decomposition rate was observed, which was almost the same as when only a Pyrex glass container was used.

[0030]

[Table 1]

Further, since the decomposition is faster as the heavy metal is immersed, it is suggested that the effect by secondary electrons and the like is stronger than the direct decomposition by γ-ray. The relative decomposition rate indicates a value obtained by subtracting the decomposition rate of the glass container from the decomposition rate of various metal pieces. Although the decomposition of dibutyl phthalate is very rapid, it does not mean that it is immediately rendered harmless. Simply disassembly using radiation is not acceptable and detoxification is essential. Therefore, the degradation of the benzene ring, one of the characteristics of environmental hormones, was confirmed. The decomposition of the benzene ring was confirmed by measuring the UV spectrum of the aqueous solution after γ-ray irradiation.

FIG. 1 shows a change in UV spectrum due to irradiation when a stainless steel container is used as an example. The spectrum attributable to the benzene ring clearly appears at around 200 nm and 225 nm in dibutyl phthalate before irradiation, but these peaks become weaker with irradiation, and become 44 kGy.
Almost disappeared by irradiation. However, it can also be seen that a new peak appears around 190 nm during the irradiation, and this peak gradually disappears with further irradiation.

This means that the environmental hormone itself is very easily decomposed, but at a stretch H ₂ O, CO ₂ or CH ₂
Instead of breaking down into small molecules such as ₄ , 190
It is understood that a reaction intermediate is formed once by decomposition as seen in the nm peak, and then decomposed into small molecules and rendered harmless by further irradiation. This was the same when any metal pieces were inserted. In the case of Mo and W, it was found from the UV spectrum that the dissolution of metal atoms in water occurred along with the formation of the reaction intermediate, and this dissolution was accelerated by Mo and W in Table 1 more than by Pb. It was suggested that this was one of the reasons.

[0034]

According to the method for decomposing an organic compound of the present invention, since γ-rays, electron beams or various radiations from radioactive wastes are significantly more transparent than ultraviolet / visible light, treatment of opaque solutions Is also possible. Further, according to the method for decomposing an organic compound of the present invention, there is an advantageous effect that not only a transparent container such as a glass but also an opaque container such as a metal can be used as a container for containing drainage / discharge solution. Further, according to the method for decomposing an organic compound of the present invention, by coexisting a high atomic number material in drainage / drainage solution or by using these in a container, the radiation can be converted into secondary electrons or ultraviolet rays having a high chemical effect. -It has an advantageous effect that it can be converted into visible light to accelerate the decomposition of harmful organic compounds. Further, according to the method of the present invention, since the radiation used in the present invention is not particularly limited, it is possible to effectively utilize the radioactivity of the radioactive waste that needs to be stored or monitored for a long period of time. Effect.

[Brief description of the drawings]

[Figure 1] UV by irradiation when using a stainless steel container
It is a figure showing a change of a spectrum.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Yoshida 1-23-1 Yamate-dori, Showa-ku, Nagoya-shi, Aichi 1402-Nomura States Yamanote-dori, Room 1402 (72) Inventor Tadashi Hattori 2-2 Wakamizu, Chigusa-ku, Nagoya-shi, Aichi Prefecture -8-16 F term (reference) 4D037 AA11 AB11 AB14 AB16 BA16 4G075 AA15 AA37 BA05 BD16 CA38 CA39 CA51

Claims (5)

[Claims] 1. A method for decomposing an organic compound, comprising decomposing an organic compound dissolved in an aqueous solution by irradiating radiation in the presence of a solid material containing a metal. 2. The method according to claim 1, wherein the metal-containing solid material is a material that emits secondary electrons and / or light when irradiated with radiation. 3. The method according to claim 1, wherein the organic compound is decomposed by secondary electrons or light obtained by irradiating a solid material containing a metal with radiation. 4. The method according to claim 1, wherein the metal is at least one selected from the group consisting of iron, copper, aluminum, nickel, molybdenum, tungsten, lead, platinum, gold, and other rare earth elements.
The method according to any one of claims 1 to 3, which is one kind. 5. The radiation according to claim 1, wherein the radiation is at least one selected from the group consisting of X-rays, α-rays, β-rays, γ-rays, electron beams, neutron beams, and particle beams. The method described in the section.