JPH0796202A - Photocatalyst for treating harmful substance contained in liquid, and treating device therefor - Google Patents

Abstract

PURPOSE:To treat harmful substance contained in liquid with high efficiency and maintain high efficiency over a long period without peeling off and falling of titanium oxide by forming the film of titanium oxide on each heat resistant fiber itself of woven fabric constituted of heat resistant fiber having light transmission properties. CONSTITUTION:In a photocatalyst 2 for treating harmful substance contained in liquid, the film of titanium oxide is formed on each heat resistant fiber itself of woven fabric constituted of heat resistant fiber having light transmission properties. The photocatalyst 2 for treating harmful substance contained in liquid is arranged in a vessel 1 made of a transparent quartz tube. A solution containing harmful substance is circulated and passed into the vessel 1 through a pump 3. Harmful substance is treated by applying light from a light source 4 provided in the vicinity of the vessel 1. Thereby, since the specific surface area of the film on woven fabric is larger in the several degrees in comparison with the case for covering the rod and the sphere of glass with the film, contact area with water is increased. Further light is sufficiently transmitted to the inside and treatment efficiency is drastically enhanced because of material in which woven fabric having light transmission properties is covered with titanium oxide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to trichloroethylene, chloroform, which is present in a liquid when irradiated with light,
In a liquid that can treat harmful substances in the liquid by efficiently decomposing and removing organic halogen compounds such as dioxins, and harmful substances such as cyanide and pesticide components, or by sterilizing and reducing bacteria present in the liquid. The present invention relates to a photocatalyst for treating harmful substances and an apparatus for treating harmful substances in liquids using the photocatalyst.

[0002]

2. Description of the Related Art Conventionally, as a method of treating harmful substances in a liquid by using a photocatalyst, titanium oxide powder is dispersed in the liquid and a solution containing the harmful substances is poured into the liquid and irradiated with light. There are known methods of decomposing and arranging glass rods or glass spheres coated with titanium oxide film in a liquid, pouring a solution containing harmful substances into this, and irradiating light to decompose. .

[0003]

However, in the conventional method of dispersing the titanium oxide powder in the liquid, it is necessary to provide a filtration membrane on the downstream side in order to separate the powder and the liquid. It has the disadvantage of high losses. Further, when the powder is dispersed in the liquid, the light is absorbed only in the outermost layer, and it becomes difficult for the irradiation light to penetrate to the inside, resulting in a drawback that the processing efficiency is reduced. Further, the conventional method using a glass rod or a glass sphere coated with a titanium oxide film does not require the installation of a filtration film for recovering powder and allows light to pass through, but the contact interface with water is reduced and the treatment is performed. It has the drawback of being inefficient. It is an object of the present invention to provide a photocatalyst for treating harmful substances in liquid and a device for treating harmful substances in liquid using the photocatalyst capable of eliminating the above-mentioned drawbacks.

[0004]

In order to achieve the above object, the photocatalyst for treating harmful substances in a liquid of the present invention comprises titanium oxide on each heat-resistant fiber itself of a woven fabric made of heat-resistant fiber having light transmittance. Is formed.

The titanium oxide film is obtained by holding a solution obtained by dissolving a photocurable resin and a precursor which becomes titanium oxide by heating in a compatible solvent in the woven fabric, and holding the solution in the retained solution. It is preferably formed by photocuring a photocurable resin, then drying and firing the woven fabric.

As the woven cloth made of the heat-resistant fiber having light transmittance, a woven cloth made of glass fiber is preferable, and its basis weight (g / m ² ) is not particularly limited, but it is easy to handle or From the viewpoint of decomposition efficiency, generally 100
The thing of about 900 g / m ² is used. The type of glass fiber may be any composition that transmits light, such as quartz glass, high quartz glass, E glass, C glass, S glass, and A glass, but from the viewpoint of economy. E glass fibers are preferred. Further, as long as it is a heat-resistant fiber having a light-transmitting property such as an alumina fiber, the kind of fiber constituting the woven fabric is not limited at all. Also,
The average fiber diameter of the heat resistant fiber is not particularly limited, but is preferably 5 to 15 microns in order to be manufacturable and to secure the contact area with the liquid to obtain efficiency. The weave may be any weave, such as plain weave, twill weave and satin weave, but plain weave is preferred from the viewpoint of light transmission.
Further, the implantation density, thickness, and tensile strength are not particularly limited, but from the viewpoint of strength against liquid, both vertical and horizontal are 10 to 80 pieces / 25 mm, 0.01 to 2.
A width of 0 mm, 5 kgf / 25 mm or more is preferable.

The photocurable resin may be a resin curable by light energy, such as an ultraviolet curable resin or a radiation curable resin.

Titanium alkoxide, titanium chloride, titanium sulfide, titanium metal acetate, etc. can be used as the precursor which becomes titanium oxide when heated, but alcohols are used because of their compatibility with the photocurable resin. It is preferable to select titanium alkoxide when using as a compatible solvent and titanium chloride when using water as a compatible solvent. However, when the precursor and the photocurable resin are compatible with each other, any combination may be selected.

After the woven cloth is held in the woven cloth by soaking the woven cloth in the solution containing the photocurable resin and the titanium oxide precursor thus obtained, the photocurable resin is photocured. The solution containing the titanium oxide precursor is cured by irradiating light having the energy required to cure the solution.

Then, the woven cloth is dried by a dryer or the like.
The drying temperature at this time is preferably in the range of 40 to 80 ° C.

Next, the dried woven fabric is fired to remove the organic residues constituting the photocurable resin and the precursor of titanium oxide. By this firing, the titanium oxide precursor is changed to titanium oxide, and a woven fabric in which the fibers constituting the woven fabric are coated with titanium oxide is obtained.

The thickness of the titanium oxide coating is preferably 1 micron or less in view of the adhesiveness and light transmittance of the film. If it exceeds 1 micron, peeling of the film occurs, resulting in turbidity of water and deterioration of treatment efficiency. In addition, the light transmittance also deteriorates, and it becomes difficult for light to reach the inside of the woven fabric, which is not preferable in terms of decomposition efficiency. Also,
Considering the woven fabric as a whole, the coating amount of the coated titanium oxide is preferably 40% by weight or less with respect to the entire woven fabric. Also in this case, if it exceeds 40% by weight, the light transmittance is deteriorated and the titanium oxide is also peeled off, which is not preferable. The thickness of titanium oxide can be changed by adjusting the concentration of the titanium oxide precursor in the solution or by repeating the film forming step.

Further, it is preferable to support precious metals on titanium oxide. In this case, the precious metals are preferably metals such as platinum, palladium, rhodium, gold, silver and ruthenium and metal oxides thereof. The supporting method is easy if a photodeposition method is used.

In the apparatus for treating harmful substances in liquid of the present invention, the photocatalyst for treating harmful substances in liquid is placed in a container through which a solution containing a harmful substance is passed and the photocatalyst for treating harmful substances in liquid is irradiated with light. It is equipped with a light source of.
In the above apparatus, for example, the container may be configured as a transparent container made of plastics, borosilicate glass, quartz glass or the like, and light may be irradiated from the outside of the container,
Alternatively, the light source may be arranged in the container without forming the container as a transparent container. Further, the light source may be any one such as a low pressure mercury lamp or a black light fluorescent lamp as long as it has energy for photo-curing the photo-curing resin.

[0015]

[Function] A woven fabric having a titanium oxide coating formed on the heat-resistant fibers themselves having various light-transmitting properties, which forms the woven fabric, has a specific surface area several times larger than that when coated on a glass rod or glass sphere. Therefore, the contact area with water becomes large. In addition, since the woven cloth having light transmittance is coated with a titanium oxide film,
Light is hardly absorbed as if the particles were dispersed, and the light is sufficiently transmitted to the inside of the woven cloth. Therefore, the processing efficiency such as decomposition of harmful substances in the liquid is significantly increased. Further, since the titanium oxide film is uniformly and firmly coated on each heat-resistant fiber as described above, there is no peeling of titanium oxide despite the high efficiency, and therefore no turbidity of water,
There is no need to recover particulate matter.

It is preferable to support the noble metal on the surface of the titanium oxide, because the decomposition reaction of harmful substances is electrochemically promoted.

A conventionally known method of immersing a film-forming object in a solution to form a film is to form a titanium oxide film on a single substance such as a glass rod, a glass ball or a glass plate. Suitable for When coating a titanium oxide film at once on a woven fabric composed of many fibers by this method,
The woven cloth is dipped in a titanium oxide precursor solution, and the woven cloth holding the solution is dried and fired. In this case, the solvent is dried and the titanium oxide precursor also migrates to the surface, so-called migration occurs. As it occurs, the titanium oxide precursor forms on the surface of the woven fabric and does not cover the fibers inside the woven fabric. However, when the solution containing the titanium oxide precursor and the compatibilizer is fixed together with the photocurable resin by light irradiation after the solution is held on the woven fabric and before the solution is dried, only the compatibilizer is used in the next drying step. As a result, unlike the conventional method, the titanium oxide precursor does not migrate to the surface at the same time as the drying of the compatibilizer, and remains on the surface of the fiber inside the woven fabric as it is. By this drying, the coating causes cracks between single fibers from the state where all the fibers constituting the woven fabric are fixed, and the titanium oxide precursor and the photocurable resin are coated around each fiber. And the fibers separate. By firing the woven fabric in this state, the photocurable resin is removed, the gel of the titanium oxide precursor is contracted, the titanium oxide precursor is converted to titanium oxide, and the fibers are contracted in the vertical direction of the fiber. Titanium oxide is uniformly and strongly coated on each one. Further, the photocatalyst is flexible and can be installed in a container of any shape.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the apparatus for treating harmful substances in liquid of the present invention. In the figure, reference numeral 1 denotes a container made of a transparent quartz tube, in which a photocatalyst 2 for treating harmful substances in liquid is arranged. ,
A solution containing a harmful substance is circulated in the container 1 via a pump 3, and light is emitted from a light source 4 provided in the vicinity of the container 1 to treat the harmful substance. In the figure, 5 is a light collecting mirror, and 6 is an inlet / outlet for taking out a solution treated with a harmful substance or supplying a solution containing a new harmful substance.

Next, a concrete embodiment will be described together with a comparative example in accordance with a usage example of the apparatus. (Example 1) A plain weave having a mean fiber diameter of 7 microns and a yarn made of about 1000 E-glass monofilaments (single fiber) having a basis weight of 500 g / m ² , a shot density vertical 20/25 mm, and a horizontal 25/25 mm. , Thickness 0.5
A glass woven fabric (glass cloth) having a tensile strength of 100 kgf / 25 mm and a tensile strength of 100 kgf / 25 mm was immersed in a solution prepared by dissolving 76 g of titanium isopropoxide as a titanium oxide precursor, 40 g of an ultraviolet curable resin, and 1 g of concentrated hydrochloric acid in 83 g of ethyl alcohol. Remove the woven fabric holding this solution from the solution,
The woven cloth was irradiated with ultraviolet rays using a mercury lamp to cure the photocurable resin. Then dry at 60 ° C for 1 hour, then
The photo-curing resin was completely removed by raising the temperature to 400 ° C. at a temperature rising rate of 1 ° C./min and holding at 400 ° C. for 1 hour.
Further, it was baked at 500 ° C. for 5 hours. By this treatment, titanium isopropoxide changes to titanium oxide mainly composed of anatase type, and evenly on each fiber constituting the woven fabric,
Moreover, the titanium oxide could be firmly coated. In this case, the film thickness of titanium oxide was about 0.3 μm, and the ratio of the coated titanium oxide film to the entire woven fabric was 18% by weight.
Met. This woven cloth (catalyst) has a diameter of 12 mm and a length of 50.
The reaction solution was passed through a 0 mm transparent quartz tube and circulated by a pump. The reaction solution was an aqueous solution in which 200 mg / liter of chloroform was dissolved in double-distilled water, and light irradiation was performed with a low-pressure mercury lamp at a solution temperature of 40 ° C. After irradiation with light for about 5 hours, 95% of chloroform was decomposed. In this case, there was no turbidity in the water. Next, the reaction solution was replaced, and the same test was performed with an aqueous solution in which the same amount of chloroform was dissolved. 50 this test
Repeated times, there was no turbidity in water, and the decomposition efficiency of chloroform did not decrease from the initial value, maintaining high efficiency.

(Example 2) The woven fabric (catalyst) prepared in Example 1 was packed in a transparent quartz tube having a diameter of 12 mm and a length of 500 mm, the reaction solution was passed through and circulated by a pump. The reaction solution was an aqueous solution in which 200 mg / liter of trichlorethylene was dissolved in double-distilled water, and light irradiation was performed with a low-pressure mercury lamp at a solution temperature of 40 ° C. Light irradiation for about 1 hour decomposed 95% of trichlorethylene. In this case, there was no turbidity in the water.
Next, the reaction solution was replaced, and the same test was performed with an aqueous solution in which the same amount of trichlorethylene was dissolved. This test was repeated 50 times, but there was no turbidity in water, and the decomposition efficiency of trichlorethylene did not decrease from the initial value, and high efficiency was maintained.

(Example 3) The woven fabric (catalyst) prepared in Example 1 was packed in a transparent quartz tube having a diameter of 12 mm and a length of 500 mm, the reaction solution was passed through and circulated by a pump. The reaction solution was an aqueous solution prepared by dissolving 10 ppm of cyanide ions in double-distilled water, and was irradiated with light by a low-pressure mercury lamp at a solution temperature of 40 ° C. About 1
After irradiation with light for 95 hours, 95% of the cyan ions were mineralized and turned into harmless substances. In this case, there was no turbidity in the water. Next, the reaction solution was replaced, and the same test was performed with an aqueous solution in which the same amount of cyan ions was dissolved. This test was repeated 50 times, but there was no turbidity in the water, and the cyan ion removal rate did not decrease from the initial value, and high efficiency was maintained.

(Example 4) The woven fabric (catalyst) prepared in Example 1 was packed in a transparent quartz tube having a diameter of 12 mm and a length of 500 mm, the reaction solution was passed through, and circulated by a pump. The reaction solution was an aqueous solution prepared by dissolving 200 mg / liter of a pesticide (BPMC) in double-distilled water, and was irradiated with light by a low-pressure mercury lamp at a solution temperature of 40 ° C. 95% of pesticide (BPMC) by light irradiation for about 2 hours
% Removed. In this case, there was no turbidity in the water. Next, the reaction solution was replaced, and the same test was conducted with an aqueous solution in which the same amount of pesticide (BPMC) was dissolved. This test was repeated 50 times, but there was no turbidity in the water, and the removal efficiency did not decrease from the initial value, maintaining high efficiency.

(Example 5) The woven fabric (catalyst) coated with titanium oxide prepared in Example 1 was immersed in an aqueous solution of chloroplatinic acid to carry 10% by weight of platinum on the titanium oxide and irradiated with light. By doing so, a woven fabric in which platinum was deposited on the surface of titanium oxide was prepared. This woven cloth (catalyst) has a diameter of 12 mm,
The reaction solution was passed through a transparent quartz tube having a length of 500 mm, which was then circulated by a pump. 200 mg of reaction liquid in double-distilled water
The solution was irradiated with light from a low pressure mercury lamp at a liquid temperature of 40 ° C. Light irradiation for about 30 minutes decomposed 95% of chloroform. In this case, there was no turbidity in the water. Next, the reaction solution was replaced, and the same test was performed with an aqueous solution in which the same amount of chloroform was dissolved. This test was repeated 50 times, but there was no turbidity of water, and the decomposition efficiency of chloroform did not decrease from the initial value.
It kept high efficiency.

Comparative Example 1 The glass woven fabric used in Example 1 was dipped in titania sol which is a precursor of titanium oxide, dried at 60 ° C. for 1 hour, and then fired at 500 ° C. for 5 hours. By this treatment, titania sol changed to titanium oxide mainly composed of anatase type, but migration occurred, titanium oxide was often associated near the surface of the woven fabric, bridging between fibers and agglomeration of particles were generated, and powder falling was caused. there were.
In this case, the ratio of the amount of coated titanium oxide to the entire woven fabric was 50% by weight. This woven fabric (catalyst) has a diameter of 1
The reaction solution was passed through a transparent quartz tube having a length of 2 mm and a length of 500 mm, which was circulated by a pump. The reaction solution is 2 in distilled water.
It was irradiated with a low-pressure mercury lamp at a liquid temperature of 40 ° C. with an aqueous solution in which 00 mg / liter of chloroform was dissolved. After irradiating with light for about 5 hours, 85% of chloroform was decomposed, but the water was considerably turbid due to the loss of titanium oxide. Next, the reaction solution was replaced, and the same test was performed with an aqueous solution in which the same amount of chloroform was dissolved. The second time, 60% decomposes under the same conditions, and the third time 50% decomposes.Titanium oxide drops off every time the reaction solution is replaced and the test is performed, and it becomes 0% after the 20th time. It had lost its catalytic function.

[0025]

As described above, the photocatalyst for treating harmful substances in liquid according to the present invention has good light transmittance and has a large contact area with water, so that the harmful substances in liquid can be treated with high efficiency. Have. Specifically, since it is possible to decompose organic halogen compounds such as trichloroethylene, chloroform, dioxin, etc. existing in the liquid, cyanide, pesticide components, etc., it is possible to make ultrapure water using water containing organic substances. . Moreover, since the oxidizing power of the titanium oxide catalyst is very strong, it is possible to kill bacteria existing in water. As an example of this, the action of CoA, which is an enzyme of the living body, can be stopped by light-irradiated titanium oxide and sterilized. In addition, since the titanium oxide film is uniformly and firmly coated on each of the fibers constituting the woven fabric, there is no peeling or dropping of the titanium oxide, and high efficiency is maintained for a long period of time. Since it has no turbidity, it has an effect that it is not necessary to collect powder or the like. Further, since it has flexibility, it can be applied to a container having a complicated shape and can be columnized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the liquid hazardous substance treating apparatus of the present invention.

[Explanation of symbols]

 1 Container 2 Photocatalyst for Treatment of Hazardous Substances in Liquid 3 Pump 4 Light Source 5 Focusing Mirror 6 Inlet / Outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koki Ito 1-14-11-106 Takaban, Meguro-ku, Tokyo (72) Inventor Koichi Kawashima 630 Tarui-cho, Fuwa-gun, Gifu Japan Inorganic Stock Company Tarui factory (72 ) Inventor Ryuji Masuda 630 Tarui-cho, Fuwa-gun, Gifu Prefecture, Tarui Plant, Japan Inorganic Stock Company (72) Wataru Takahashi 630, Tarui-cho, Fuwa-gun, Gifu Prefecture, Tarui Plant, Japan Inorganic Stock Company

Claims (5)

[Claims] 1. A photocatalyst for treating harmful substances in a liquid, characterized in that a film of titanium oxide is formed on each heat-resistant fiber itself of a woven fabric made of heat-resistant fiber having light transmittance. 2. The photocatalyst for treating harmful substances in a liquid according to claim 1, wherein the heat resistant fiber is glass fiber. 3. The titanium oxide coating film holds a solution prepared by dissolving a photocurable resin and a precursor which becomes titanium oxide by heating in a compatible solvent in the woven fabric, and the retained solution. The photocatalyst for treating a harmful substance in a liquid according to claim 1 or 2, which is formed by photocuring the photocurable resin therein and then drying and firing the woven fabric. 4. The photocatalyst for treating a harmful substance in a liquid according to claim 1, wherein a noble metal is supported on the titanium oxide. 5. The photocatalyst for treating a harmful substance in liquid according to any one of claims 1 to 4 is arranged in a container through which a solution containing a harmful substance is passed, and the photocatalyst for treating a harmful substance in liquid is irradiated with light. An apparatus for treating harmful substances in liquid, comprising a light source for irradiating.