JP2000084361A - Prevention of environmental pollution and material having function for preventing environmental pollution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively decompose an org. material having possibility of causing environmental pollution. SOLUTION: The org. material having possibility of causing the environmental pollution is decomposed by a photocatalyst. Especially, the decomposition of the org. material remaining after incineration is possible without using a special equipment by previously adding a photocatalyst precursor in the material. Then titanium oxide is used as the photocatalyst, a hardly decomposable org. material such as dioxins is adsorbed and decomposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing environmental pollution by organic substances and a material having a function for preventing environmental pollution.

[0002]

2. Description of the Related Art Environmental pollution of substances harmful to the human body has become serious, and in recent years, the diffusion of hormone-like chemical substances (endocrine disrupting substances), which affect various functions of ecology even in very small amounts, into the environment has been increasing. Is in question. Hormones are naturally secreted in the ecology, but some chemicals have a similar effect to hormones, and are suspected to cause reproductive abnormalities in birds, mammals, shellfish, and other wildlife. . Examples of such studies are the genitalization of the genitalia found in the snail, Ibonyshi, the morphological and behavioral femaleization of male seagulls, and the inhabitants of Lake Apopka, Florida Crocodiles' reproductive organs have also been reported to be due to pesticide contamination. Regarding the effect on humans, the decrease in sperm count (from 1938 to 1990)
There are reports that it has halved over the years. ) And malformations have been remarkably increased in recent years, suggesting a relationship with hormone-like chemicals.

[0003] Compounds currently suspected of being hormone-like chemicals include pesticides such as atrazine, DDT, and dicophor, phenols used in resins, and dioxins discharged in the process of treating waste. .
In particular, dioxins generated during incineration of chlorine-containing resins such as vinyl chloride are not only their hormone-like activity,
Because of its high toxicity such as carcinogenicity and teratogenicity, it is one of the pollutants for which measures are urgently required. Dioxins include dioxin (PCDD), polychlorinated dibenzofuran (PCDF) and coplanar PCB (Co-PC
A compound such as 2,7-dichloro-dibenzodioxin (2,7-dichloro-p-dibenzodioxin) is a general term for compounds including B). Since dioxins are always generated when burning incinerated products containing chlorine, fundamental measures are difficult and have become a serious problem in recent years. Dioxins remain in the exhaust gas discharged from the incinerator and in the ash (incinerated ash) remaining after incineration. Incinerated ash is landfilled at a final disposal site, but dioxin contamination due to scattered incinerated ash has been detected above this disposal site.

[0004] Many of these environmental pollutants are relatively stable and cannot be expected to degrade microorganisms in the environment, and once discharged into the environment, it is difficult to remove them. For example, dioxins are relatively stable to heat, acids, and alkalis, are hardly soluble in water, and have high persistence. Since dioxins are often generated during the incineration process of wastes, there is a possibility that emission to the environment can be reduced by devising, for example, attaching an adsorption filter for dioxins to an incinerator. In practice, however, equipping all incineration facilities with such equipment involves significant technical and economic difficulties. In addition to general waste, many products are burnt in the mountains, such as agricultural materials, and measures for dioxins generated during incineration were not perfect. Even better, products sprayed into the environment, such as pesticides and pesticides, had no means of preventing environmental pollution by these products.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for decomposing an organic substance causing environmental pollution in an environment to prevent the pollution, and to provide a material therefor.

[0006]

Means for Solving the Problems The present inventors have thought that organic substances which diffuse into the environment and cause pollution can be decomposed by the action of a photocatalyst. That is, an organic substance is adsorbed on a photocatalyst having adsorptive power, and is further decomposed by irradiation with light such as sunlight. The present inventors have found that the organic substance can be particularly effectively decomposed by bringing the organic substance to be decomposed into contact with the photocatalyst before diffusing into the environment. Furthermore, the present inventors have found that by premixing a product with a photocatalyst having the ability to adsorb organic substances to be decomposed, the photocatalyst can be effectively decomposed even after the product has diffused into the environment. Was found. In addition, by using this photocatalyst as a precursor with low catalytic activity in the product and a compound that exhibits high catalytic activity through incineration and other treatments, the decomposition activity of organic substances at the stage of release into the environment is enhanced. Was found to be possible. The present invention has been completed based on these findings. That is, the present invention relates to the following methods for preventing environmental pollution and materials therefor. [1] A method for preventing environmental pollution by decomposing organic substances that cause environmental pollution by the action of a photocatalyst. [2] The method of [1], wherein the photocatalyst is titanium oxide. [3] The method of [1], wherein the organic substance is contained in the incinerated ash. [4] The method of [3], wherein the photocatalyst has been previously added to the substance to be incinerated. [5] The method of [4], wherein the photocatalyst is added to the substance to be incinerated as a photocatalyst precursor whose catalytic activity is enhanced by heating. [6] The method of [5], wherein the photocatalyst precursor is an amorphous photocatalyst precursor. [7] The method of [3], wherein the photocatalyst is mixed into the incinerated material before and / or after incineration. [8] The method of [1], wherein a photocatalyst is additionally acted on together with the transition metal oxide.

[9] The method of [8], wherein the transition metal oxide is vanadium oxide. [10] The method of [1], wherein the organic substance is artificially released into the environment. [11] The organic substance is an agricultural chemical, a surfactant, a polymer material,
[10] The method of [10], which is selected from the group consisting of manure and endocrine disruptors. [12] Environmental pollution caused by adding a photocatalyst and / or a photocatalyst precursor to a material that contains an organic substance that causes environmental pollution or that may generate an organic substance that causes environmental pollution in the process of disposal A material that has the function of preventing. [13] The material of [12], wherein the material is an organic chlorine compound. [14] The material of [12], wherein the material is a pesticide. [15] A method for adsorbing an organic substance causing environmental pollution, comprising a step of bringing an organic substance causing environmental pollution into contact with a transition metal oxide.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The photocatalyst usable in the present invention is:
A compound capable of adsorbing an organic substance on its surface or adsorbing on the surface of the organic substance and catalyzing the decomposition of the adsorbed organic substance by being irradiated with light. Decomposition of organic substances is generally oxidative decomposition, but the mode of reaction is not limited. As the photocatalyst, specifically, titanium oxide, zinc oxide, tin oxide, strontium titanate,
Examples include tungsten oxide, bismuth oxide, and iron oxide. Among them, titanium oxide is a desirable photocatalyst because it has the highest decomposition ability for organic substances among these photocatalysts and is stable and safe for living organisms. Regarding the decomposition ability of titanium oxide, it can be applied to almost all organic substances and can be mineralized by changing it to inorganic substances such as water, carbon dioxide, and hydrochloric acid. The photocatalyst used in the present invention needs to have a property of adsorbing and holding harmful substances so that it does not escape. As such a photocatalyst, colloidal titanium oxide (titanium oxide sol) dispersed in a solvent or water or fine powder is desirable. In order to enhance the adsorptivity, it is effective to mix activated carbon, zeolite, activated alumina and the like with a photocatalyst or to coat photocatalyst particles.

In the present invention, the photocatalyst is brought into contact with an organic substance to be decomposed, and then illuminated with sunlight or artificial light to exert an action of decomposing an organic substance causing environmental pollution. Therefore, how to make contact with the organic substance is not particularly limited. However, the following method can be adopted so that the decomposing action can be expected as reliably as possible with a simpler operation. First,
One of the simplest and most reliable methods is to manufacture organic substances that cause environmental pollution or materials that can generate organic substances that cause environmental pollution during distribution and disposal. At this stage, the photocatalyst or the precursor of the photocatalyst is mixed. For example, a precursor of a photocatalyst can be mixed in the process of producing vinyl chloride or the like, which is one of the sources of dioxins involved in incineration. Even if the material in which the photocatalyst precursor is mixed in advance is incinerated in an incineration facility having no special facilities, it has a decomposing action on organic substances remaining after incineration, and effectively prevents environmental pollution. In addition, the effect of decomposing organic substances extends not only to organic substances derived from the material itself mixed with the photocatalytically active substance, but also to substances derived from other wastes incinerated together. If the photocatalyst is directly mixed, the vinyl chloride product is deteriorated by light, but if the precursor is mixed, the deterioration at the time of use can be minimized.
If a compound that acquires photocatalytic activity by heat treatment is used as a photocatalyst precursor, it acquires photocatalytic activity by incineration, adsorbs various organic substances such as dioxins generated by incineration, and releases them into exhaust gas Suppress. After incineration, various organic substances such as dioxins remaining in the incinerated ash after being irradiated with light are decomposed. The following compounds can be shown as such a photocatalyst precursor.

1) amorphous titanium oxide 2) various titanium salts titanyl sulfate titanium chloride (titanium tetrachloride, titanium trichloride) titanium fluoride (titanium powder) titanium ammonium peroxocitrate tetrahydrate 3) organic titanate titanium Isopropoxide Titanium ethoxide Titanium methoxide Titanium 2-ethyl-1-hexanolate Titanium oxide Acetylacetonate Titanium tetrabutoxide Titanium tetraisopropoxide Titanium dichloride diethoxide Titanium diisopropoxide (bis-2,4-pentanedionate 4) Titanium methoxypropoxide Titanium methylphenoxide 4) Crystalline titanium oxide (anatase type, rutile type) treated with amorphous titanium oxide

The above-mentioned photocatalyst precursor itself shows only low photocatalytic activity, but generates titanium oxide having high photocatalytic activity through heat treatment. In particular, amorphous titanium oxide is a desirable precursor that can reliably produce titanium oxide even at relatively low temperatures due to incomplete combustion. Incomplete combustion has a combustion temperature of 100 ° C. to 800 ° C., particularly 3 ° C., which is considered to easily generate dioxins.
Precursors that achieve a reliable photocatalytic activity under these conditions, as they provide a temperature between 00 ° C. (the melting point of the dioxins) and 800 ° C. (the temperature at which the decomposition of the dioxins begins) are particularly desirable compounds in the present invention. In the present invention, the photocatalyst precursor refers to a photocatalyst substance which is smaller than a photocatalyst substance finally produced. The catalytic activity of the photocatalyst precursor is desirably 1/10 or less as compared with the photocatalyst produced therefrom. For example, the amorphous titanium oxide exemplified here obtains a photocatalytic activity of 10 times or more through a desired heat treatment. The term “amorphous” as used herein means a solid compound in a state where a diffraction pattern unique to a crystal is not observed in X-ray structural diffraction.

The amorphous photocatalyst precursor used in the present invention is:
It can be obtained by hydrolysis of an organometallic compound (metal organic compound). For example, to obtain a precursor that provides titanium oxide as a photocatalyst, a homogeneous amorphous titanium oxide that can be crystallized at a low temperature can be obtained by hydrolyzing alkoxide of titanium. As a factor for lowering the crystallization temperature, it is important to crystallize in a uniform state as much as possible.However, even when mixing amorphous titanium oxide with a polymer or the like, it is important to mix as uniformly as possible. . In addition, the amorphous photocatalyst precursor generally becomes fine powder, and it may be difficult to mix the precursor with the resin material. In such a case,
By coating a large crystal such as crystalline titanium oxide with an amorphous powder, a material that can be easily mixed can be obtained. At this time, since the crystalline titanium oxide serving as a nucleus is inactivated by the coating, it does not cause deterioration of the resin material as the base material.

By mixing the photocatalyst in advance,
As a material that can be expected to decompose organic substances generated during incineration, there can be mentioned many thermoplastic resin materials which are softened by heating, in addition to vinyl chloride. Hereinafter, resin materials to which the present invention can be applied and typical uses thereof will be described. ● Soft vinyl chloride resin: Film, packaging (fiber, food), adhesive tape, plywood and copper plate lamination, covers, temporary materials for building and civil engineering, agriculture (for heat insulation coating), leather, hose, For daily necessities, miscellaneous goods, and electric wires ● Rigid polyvinyl chloride resin: pipes, films and sheets-for food container packaging, fittings, corrugated plates, flat plates, molded products, profiled products ● Polyvinylidene chloride: fibers, films, processed meat materials,
Packaging for fresh meat, packaging for processed agricultural and marine products, packaging for preserved food, molded product ● Polyethylene: Low-density polyethylene, film, food packaging, carry bag, heavy packaging, agriculture, civil engineering, laminate, injection molding Products, wire coating, hollow molding, pipes ● High-density polyethylene: film, food and sundries packaging, shopping bags for supermarkets, hollow molded products, injection molding, stretch tape (for binding), pipes, fibers, fertilizer, rice and wheat bags, Simple tent sheet ● Polystyrene: Electric / Industrial-Electric materials, Packaging-Shrink wrap (food), miscellaneous goods ● AS resin (Styrene-acrylonitrile copolymer): Electric / mechanical parts, automobile parts, stationery, miscellaneous goods, etc. ● ABS Resin (styrene-acrylonitrile-butadiene resin): electronic / electric parts, general equipment, vehicles, miscellaneous goods (building materials, furniture, toys, etc.) Goods packaging containers, general construction materials, cold stores for insulation, agricultural products containers, cushioning packaging materials ● polypropylene: injection molding, films, food packaging, fiber packaging, laminate building materials, stretched tape, agricultural bags,
Sandbag, binding rope, fiber, hollow molding, extrusion molding ● Polycarbonate: for electronic / electric / OA / insulation, automobile / machinery, film / sheet, food packaging, building materials, agricultural materials, medical / security

In addition, by mixing a photocatalytically active substance into incineration ash, the desired activity of decomposing organic substances can be expected. Alternatively, a method in which a photocatalyst precursor is mixed into waste to be incinerated (incinerated material) before incineration is also effective. The former has the advantage that the photocatalyst can be mixed uniformly throughout. When mixing the photocatalyst (or photocatalyst precursor) before incineration, it is advantageous to use a mill so that the mixing can be as uniform as possible. On the other hand, in the latter, an organic substance generated during incineration is adsorbed in situ, and an effect of suppressing the amount of emission into the exhaust gas can be expected.

In any case, the incinerated ash containing the photocatalyst receives light irradiation in the process of final disposal such as landfill as in the past, and the decomposition of organic substances proceeds. Alternatively, the decomposition of the organic substance can be progressed more actively by artificially irradiating light suitable for expressing the activity of the photocatalyst after incineration. For example, in the case of titanium oxide, a high degree of catalytic action is exhibited by irradiation with light having a wavelength of 400 nm or less.

When the purpose is to decompose organic substances such as dioxins in incinerated ash or the like, titanium oxide is used in an amount of about 0.01% (hereinafter, unless otherwise specified,% is weight%) based on the added material. ), Sufficient decomposition action can be expected. When it is suspected that dioxins are present in a particularly large amount, the decomposition rate can be increased by mixing a larger amount of titanium oxide. On the other hand, since an unnecessarily large amount is not rational, it is usually 50% or less, preferably 3% or less.
By mixing so as to be 0% or less, more desirably 5% or less, effective decomposition can be expected. When the photocatalyst precursor is added in advance to the material, the amount of incinerated ash generated under general incineration conditions and the amount of organic substances to be decomposed,
In consideration of the yield of the photocatalyst generated from the precursor through incineration, it is possible to finally supply a required amount of the photocatalyst. Specifically, for example, in the case of vinyl chloride, 0.1-5 wt%, more preferably 0.1-1 w
It can be added to become t%. 0.1 wt% is
This is a desirable addition amount necessary for securely adsorbing organic substances generated through incineration and promoting decomposition. The more the photocatalyst (or a precursor thereof) is added, the more reliable the adsorption and decomposition of the organic substance can be expected. However, when the photocatalyst (or its precursor) is added to the resin material in advance, it is preferable to use the photocatalyst within a range that does not impair the characteristics. In a typical polymer, 5
Addition of an inorganic material in excess of wt% may impair the inherent properties of the resin material. To a resin material such as vinyl chloride, an inorganic material usually called a filler is added to adjust physical properties such as strength. Inorganic materials added as fillers are generally 1 wt.
%, The photocatalyst (or a precursor thereof) in the present invention does not impair the inherent properties of the resin material when used in this range. Furthermore, if the photocatalyst (or a precursor thereof) according to the present invention is added as a filler, a sufficient amount can be added without impairing the properties of the resin material. Needless to say, the allowable amount varies depending on the combination of the resin material and the photocatalyst (or a precursor thereof). Those skilled in the art can empirically set the amount that can be added within a range that does not impair the properties of the material.

The photocatalyst (or its precursor) in the present invention can be uniformly dispersed by softening a resin material such as vinyl chloride by heating and kneading the two. By uniformly dispersing the photocatalyst (or a precursor thereof) in the resin material, adsorption and decomposition of the organic substance can be efficiently performed.

The method for preventing environmental pollution according to the present invention can be applied not only to dioxins accompanying incineration of synthetic resins, but also to all organic substances which may diffuse into the environment and cause pollution. Products (or wastes) that provide such organic substances include pesticides, surfactants, polymeric materials, manure, endocrine disruptors, and the like. If a photocatalytically active substance is previously mixed with an agricultural chemical sprayed in the environment as an insecticide, a herbicide, a bactericide, etc., irradiation with light promptly after spraying will accelerate the decomposition of the agricultural chemical. Some pesticides achieve the desired effect by remaining in the environment for a period of time rather than being immediate. For this type of drug, the activity of the pesticide can be maintained for a required period of time by adsorbing the active ingredient of the pesticide on the photocatalyst surface together with the easily decomposable inert carrier. As the carrier is decomposed, the active ingredient of the pesticide is adsorbed on the surface of the photocatalytic substance and undergoes decomposition. For example, a water-soluble carrier such as a saccharide is degraded with time due to moisture, and the photocatalytic component is completely exposed before coming into direct contact with the active ingredient of the agricultural chemical. Agrochemicals, surfactants, and the like can be stored in a light-shielded state until use, so that each material does not deteriorate during storage, and therefore, it is only necessary to mix a photocatalyst. In addition, the organic substances constituting the manure of livestock and pets can be promptly decomposed after excretion by giving a feed mixed with titanium oxide in advance. Petroleum materials include various petroleum products and their waste.
A photocatalyst can be added to these products and wastes in advance unless they come into contact with light. Alternatively, a photocatalyst may be added at the disposal stage. There are the following reports on the activity of titanium oxide for decomposing organic substances. Therefore, the present invention can be applied not only to the above organic substances but also to these organic substances.

1) Organohalogen compounds: trichloroethylene, tetrachloroethylene AL Pruden and DF Ollis, J. Catal., 81, 404 (1
983) ・ Chlorine-containing aromatic compounds (chlorophenols, chlorobenzenes, dioxins) M. Barbeni, et al., Chemosphere, 15, 1913 (1986) 2) Surfactants ・ Dodecylbenzenesulfonic acid, its sodium salt H Hidaka, et al. Nouv. J. Chim., 9, 67 (1985) H. Hidaka, et al. J. Photochem., 35, 219 (1986) ・ Benzyl dodecyl dimethyl ammonium chloride H. hidaka, et al. , Yukagaku (J. Jpn. Oil Chem. So
c.), 36, 386 (1987) 3) Pesticides • 2,4-D P. Pichat, et al., "The First International Conferre
nce on TiO ₂ Photocatalytic Purification and Treatm
ent of Water and Air "p.206 (1992) ・ Simazine E. Perizzetti, et al., Environ. Sci. Technol., 24,
1559 (1990) ・ Dimethyl 2,2,2-trichloro-1-hydroxyethyl phosphate K. Harada, et al., Wat. Res., 24, 1415 (1990)

In the present invention, in order to enhance the effect of reducing the production of organic compounds by the photocatalyst, auxiliary components can be combined. As the subcomponent, for example, a transition metal oxide can be shown. Specific examples include transition metal oxides such as iron oxide, copper oxide, vanadium oxide, manganese oxide, copper oxide, nickel oxide, and chromium oxide.
These subcomponents may be mixed with titanium oxide, or may be coated on the surface of titanium oxide and carried. The mechanism by which such transition metal oxides suppress the production of organic substances that cause environmental pollution is not currently known, but organic substances that cause environmental pollution such as dioxins are not soluble in water. It is a hydrophobic (oil-based) compound and may be selectively adsorbed to a hydrophobic (oil-based) surface. Titanium oxide alone is a slightly hydrophilic oxide, and is known to become amphiphilic by light irradiation.However, when dioxins are generated during combustion, the light irradiation history It seems to be hydrophilic because there is no. On the other hand, the transition metal oxide surface is considered to be more hydrophobic (lipophilic) than immediately after combustion, depending on the oxidation state when exposed to a high temperature. In general, transition metal oxides easily lose oxygen, and it is expected that incomplete combustion at a low temperature will result in a more oxygen-deficient state and a reduced state due to loss of a constant ratio of oxygen. For this reason, after combustion, it can be predicted that dioxins and the like are more easily adsorbed. In addition, dioxins have a high decomposition temperature and are likely to be precipitated in a solid phase during combustion or cooling. In such a case, the lipophilicity of the catalyst surface will be required as compared with the case where the catalyst is adsorbed in the gas phase. As another effect, it is conceivable that the transition metal oxide promotes combustion. In fact, when an oxide such as titanium oxide is added to polystyrene, the amount of unburned substances is smaller than that of the non-added one and tends to burn well even under the same combustion conditions. All transition metal oxides have a similar tendency, and it is currently considered that the effect of the transition metal is a combination of such effects. An adsorbent such as zeolite or activated carbon may be further added to such a mixed catalyst. Activated carbon is a lipophilic adsorbent and is suitable for this application.

In the present invention, a co-catalyst component can be further added in addition to the auxiliary component. The co-catalyst component is a compound that exhibits a catalytic action such as a cleavage reaction or an oxidative decomposition reaction on an aromatic compound, such as vanadium oxide, cobalt-molybdenum sulfide, and a nickel-tungsten transition metal compound. Or an acid type catalyst exhibiting solid acidity such as aluminum chloride, silica-alumina, silica-magnesia, silica-zirconia, and alumina-boron oxide. Hereinafter, the present invention will be described more specifically based on examples.

[0021]

[Embodiment 1] Photocatalytic titanium oxide sol (6wt%,
(Alkali deflocculation type, manufactured by Taki Kagaku Co., Ltd.) was spray-coated on an alumina substrate to form a thin film having a thickness of about 1 μm. After heat treatment at various temperatures, the decomposition activity of toxic gas methyl mercaptan was evaluated. First 3ppm in the dark
Of methyl mercaptan gas containing the sample
Then, the mixture was introduced into a glass container of 1 l and irradiated with a 4 W BLB lamp at a distance of 8 cm to evaluate the gas decomposition rate. After 30 minutes, the concentration reduction rate is plotted on a graph as R30, as shown in FIG. 1. At the beginning, the photocatalytic activity is not so large, but the activity increases as the temperature rises, and the activity decreases when the temperature exceeds 800 ° C. As a result of evaluating the decomposition activity of dioxins (DCDD: 2,7-dichloro-p-dibenzodioxin) by gas chromatograph on a titanium oxide sol heat-treated at 700 ° C assuming incineration disposal, It was shown to be degradable.

Embodiment 2 FIG. Tetraisopropoxide (TiOC ₃ H ₇ ), which is an alkoxide of titanium, was dropped into a solution obtained by adding water to isopropyl alcohol, and then stirred for 30 minutes to hydrolyze to obtain a white suspension. This was centrifuged, dried in a dryer for 12 hours at 80 ° C., and pulverized to obtain an amorphous titanium oxide powder. By the powder X-ray diffraction method, the powder dried at room temperature showed no diffraction line,
Although it was shown to be amorphous, crystallization of anatase was observed above 300 ° C. When PVA was mixed as a pseudopolymer with the amorphous titanium oxide and calcined, anatase crystallization was also observed at 300 ° C.

The photocatalytic activity before and after calcination was measured using hydrogen sulfide (H
₂ S) was evaluated by decomposition. Initial H ₂ S concentration is 2
00 ppm and an ultraviolet intensity of 2.2 mW / cm ² . The unfired amorphous titanium oxide did not show any decomposition activity, but showed remarkable decomposition activity when fired at 300 ° C. or higher. The same result was obtained when the mixture was ignited and burned after mixing with PVA.

Embodiment 3 FIG. 5 The titanium oxide prepared in Example 2 was added to polystyrene as a model substance of an aromatic polymer.
0 wt% added and burned at 300 ° C (there is a residue) was installed in the flow path, and air was introduced at a constant flow rate of 0.8 L / min, which produced polystyrene and styrene monomer and benzaldehyde. The detection amount of the substance was 0.7 wt% or less as compared with the case where no titanium oxide was contained.
The analysis was performed using a liquid chromatograph.

Embodiment 4 FIG. A solution obtained by dissolving polystyrene in benzene, Ti0 ₂ (manufactured by Ishihara Sangyo Kaisha, ST01) only _and, V 2 _{O 5} (the vanadium oxide) 1: mixed ones, respectively 1, was added about 2 wt% from 0.5 wt% The gas generated when this was burned at 300 ° C. was analyzed by liquid chromatography. Table 1 shows the results.

[0026]

[Table 1] ―――――――――――――――――――――――――― Additives (catalyst addition%) Benzaldehyde Styrene monomer ―――――――― ――――――――――――――――――― Polystyrene only 0.075 g 0.05 g TiO ₂ (1 wt%) 0.075 g 0.05 g TiO ₂ -V ₂ O ₅ (0.5 wt% ) 0.03 g 0.02 g TiO ₂ -V ₂ O ₅ 0.035 g 0.05 g TiO ₂ -V ₂ O ₅ 0.03 g 0.04 g ――――――――――――――――― ―――――――――――

It can be seen that in the system to which vanadium oxide was added, the amount of the aromatic compound-containing gas discharged even with a very small addition was suppressed. The residue containing the catalyst was in a state where a black tar-like substance had adhered thereto. However, irradiation with ultraviolet rays of 1 mW / cm ² or more for one week changed the color to white ash. From this fact, by introducing a very small amount of the catalyst into the polymer in advance, the amount of the aromatic compound discharged in gaseous form can be reduced.In addition, the compound remaining adsorbed on the residue is also oxidatively decomposed by light irradiation. I understood that.

[0028]

According to the present invention, harmful emissions can be reduced by adding a very small amount of a catalyst of 5 wt% or less to a material that may generate hormonal substances and the like and cause environmental pollution at the time of incineration disposal. The generation is suppressed, and the adsorbed harmful effluent can be decomposed by photocatalysis.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the photocatalytic activity of a titanium oxide sol and a heat treatment temperature.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Akira Fujishima 710-5 Nakamaruko, Nakahara-ku, Kawasaki City, Kanagawa Prefecture

Claims (15)

[Claims] 1. A method for preventing environmental pollution by decomposing an organic substance causing environmental pollution by the action of a photocatalyst. 2. The method of claim 1, wherein the photocatalyst is titanium oxide. 3. The method according to claim 1, wherein the organic substance is contained in the incineration ash. 4. The method of claim 3, wherein the photocatalyst is pre-added to the material to be incinerated. 5. The method according to claim 4, wherein the photocatalyst is added to the substance to be incinerated as a photocatalyst precursor whose catalytic activity is enhanced by heating. 6. The method of claim 5, wherein the photocatalyst precursor is an amorphous photocatalyst precursor. 7. The method according to claim 3, wherein the photocatalyst is incorporated into the incineration before and / or after incineration. 8. The method of claim 1, further comprising the additional step of activating a photocatalyst with the transition metal oxide. 9. The method of claim 8, wherein the transition metal oxide is vanadium oxide. 10. The method of claim 1, wherein the organic material has been artificially released into the environment. 11. The method of claim 10, wherein the organic substance is selected from the group consisting of pesticides, surfactants, polymeric materials, manure, and endocrine disruptors. 12. An environment in which a photocatalyst and / or a photocatalyst precursor is added to a material that contains an organic substance that causes environmental pollution or has a possibility of producing an organic substance that causes environmental pollution in the course of disposal. A material that has the function of preventing contamination. 13. The material according to claim 1, wherein the material is an organic chlorine compound.
2 materials. 14. The material according to claim 12, wherein the material is a pesticide. 15. A method for adsorbing an organic substance causing environmental pollution, comprising a step of bringing an organic substance causing environmental pollution into contact with a transition metal oxide.