JP2600103B2 - Photocatalytic filter and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst filter used as an environmental purification material for removing bad smells and harmful substances in the air, or for treating wastewater or water, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, odors in living and working spaces and pollution by harmful substances such as exhaust gas from automobiles have become serious problems. Water pollution from domestic wastewater and industrial wastewater, especially water pollution from organic chlorine-based solvents and pesticides at golf courses, etc., which are difficult to treat with the current water treatment methods such as activated sludge, is widespread. Environmental pollution is becoming a serious social problem.

Hitherto, as a method of preventing odors or a method of removing harmful substances in the air, a method of absorbing or adsorbing to an absorbing solution such as an acid or an alkali, an adsorbent, soil, etc. is often performed. Treatment of waste liquor, used adsorbents and soil can cause secondary pollution. Also,
There are methods to mask odors by using fragrances and methods to decompose with activated sludge.However, in the case of fragrances, the odor of the fragrance itself may be damaged, and in the case of activated sludge, the processing capacity However, it has the disadvantage that the emission of sludge is unavoidable (for example, Konosuke Nishida, Heibonsha, encyclopedia, Volume 1, p136 (1984)).

When a semiconductor is irradiated with light, electrons having a strong reducing action and holes having a strong oxidizing action are generated, and molecular species in contact with the semiconductor are decomposed by the redox action. By utilizing such an action of a semiconductor, that is, a photocatalytic action, it is possible to decompose and remove environmental pollutants such as organic solvents, pesticides, and surfactants dissolved in water and harmful substances in the air. This method only utilizes semiconductors and light, and has less restrictions on reaction conditions such as temperature, pH, gas atmosphere, toxicity, and the like, and is difficult to process using a biological treatment method, as compared to methods such as biological treatment using microorganisms. It has the advantage of being able to easily decompose and remove even compounds such as organic halogen compounds and organic phosphorus compounds. However, semiconductor powders have been used as a photocatalyst in research on decomposition and removal of organic substances by a photocatalyst (for example, see AL Pruden and DF Ollis, Journal of Cat.
alysis, Vol. 82, 404 (1983), H. Hidaka, H. Jou, K.
Nohara, J. Zhao, Chemosphere, Vol. 25, 1589 (199
2), Kusunaga Teruaki, Harada Kenji, Tanaka Keiichi, Industrial Water, No. 379
No. 12, (1990)). Therefore, it is difficult to handle and use as a photocatalyst.In the case of water treatment, the treated water must be filtered to recover the photocatalyst powder.However, since the photocatalyst is a fine powder, clogging may occur. However, there is a problem that it is difficult to separate and recover the treated product and the photocatalyst, and it is not possible to continuously treat water.

[0005]

SUMMARY OF THE INVENTION In view of the above, the present invention enables continuous and efficient removal of offensive odors and harmful substances in the air, wastewater treatment, water purification treatment, and the like. It is an object of the present invention to provide a photocatalyst filter having excellent characteristics in terms of water resistance, heat resistance, light resistance, weather resistance, stability and the like, and a method for producing the same.

[0006]

Means for Solving the Problems To achieve the above object, the present inventors have conducted intensive studies, and as a result, coated a titania sol on a glass filter formed by fusing heat-resistant glass pellets, followed by heating and firing. The photocatalyst filter produced by this process contaminates the environment such as odors, harmful substances in the air, organic solvents dissolved in water, pesticides, etc. due to the redox effect of electrons and holes generated by light irradiation. Organic compounds can be easily decomposed and removed, and the effect can be maintained without maintenance.In addition, when using titania sol to which polyethylene glycol or polyethylene oxide is added, the titanium oxide film on the surface of the photocatalytic filter has a pore size on the surface. With uniform pores, it can adsorb environmental pollutants and be quickly decomposed and removed It found, leading to the completion of the present invention.

The heat-resistant glass used in the present invention includes quartz glass, silicate glass, alumina silicate glass, borosilicate glass and the like. The heat-resistant glass pellets used in the present invention are preferably transparent, and the shape may be a lump or cylinder, a prism, a cone, a gourd, a rugby ball, a circular tube, a square tube, a filament, or the like. In particular, a spherical shape is preferable from the viewpoint of the surface area. In addition, the size is preferably several mm to several cm in diameter, but should be small in the case of removing odors and harmful substances in the air, and large in the case of treating organic solvents or pesticides dissolved in water. For example, an appropriate size can be selected depending on the type of the harmful substance to be treated, the treatment amount, the treatment speed, and the like. A glass filter can be manufactured by putting this in a mold made of heat-resistant glass, metal, carbon, or the like, and raising the temperature to a temperature higher than the softening point. The size, shape, thickness, etc. of the glass filter can be appropriately selected according to the type of harmful substance to be treated, the treatment amount, the treatment speed, and the like.

[0008] Photocatalytic filter of the present invention is thus a glass filter obtained, the material obtained by adding polyethylene <br/> glycol or polyethylene oxide to titania sol, a dip coating method, a spin coating method, coating method, spraying method, etc. And then heating and baking.

The titania sol used in the present invention is obtained by suspending ultrafine titanium oxide in water or hydrolyzing an alkoxide of titanium obtained by reaction of alcohol with titanium tetrachloride or titanium metal. Prepared. At that time, monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N,
When alcohol amines such as N-dimethyldiaminoethanol and diisopropanolamine and glycols such as diethylene glycol are added, a uniform and transparent titania sol is obtained, and by using the same, a high-performance photocatalytic filter can be manufactured.

In order to manufacture the photocatalyst filter of the present invention, when a glass filter is coated with a titania sol to which polyethylene glycol or polyethylene oxide is added, and then heated and fired, the temperature is gradually increased from room temperature and fired. desirable. At this time, the final temperature of the temperature rise, that is, the firing temperature is from 600 ° C. to 7 ° C.
00 ° C is preferred. By this operation, the titania sol coated on the substrate is changed to a titanium oxide film having a high performance as a photocatalyst and a crystalline form of anatase. At this time, firing directly at a temperature of 600 ° C to 700 ° C,
When the sintering temperature is lower than 600 ° C. or higher than 700 ° C., only a titanium oxide film mixed with low activity rutile or amorphous can be obtained as a photocatalyst. In order to obtain a durable and high performance titanium oxide film, titania sol solution is applied thinly and uniformly, or sprayed or spin-coated, or titania sol solution with low viscosity is used for dip coating to reduce the pulling speed and pull up. After coating, air is blown off to remove excess titania sol, and then it is heated and fired to form a titanium oxide thin film, and this operation is repeated to form a multilayer film. This makes it possible to obtain a thick, strong, transparent and porous titanium oxide film having a large photocatalytic action, and to manufacture a high-performance photocatalytic filter. Otherwise, a poorly durable photocatalytic filter is obtained in which white titanium oxide is deposited on the glass filter and the titanium oxide is peeled off.

[0011] The polyethylene glycol or polyethylene oxide to be added to the titania sol used in the present invention preferably has a molecular weight of 1,000 or more.
000, 6000, 8000, 11000, 1300
Those having 0, 20,000, 100,000, 300,000, 2,000,000, and 2.5 million are preferable. If the molecular weight is less than 1,000, the resulting porous titanium oxide film is easily peeled off the substrate, and a clean and durable film cannot be obtained.

The amount of polyethylene glycol or polyethylene oxide added to the titania sol used in the present invention is preferably not more than its solubility. When added in excess of the solubility, the pores do not become uniform in size and a clean film cannot be formed.

The size of pores and the density of pore distribution on the surface of the titanium oxide film covering the surface of the photocatalytic filter of the present invention are controlled by changing the amount of polyethylene glycol or polyethylene oxide added or the molecular weight. be able to. A titanium oxide porous membrane with small pores is used when the addition amount is small or a small molecular weight is used, while a large pore is used when the addition amount is large or a large molecular weight is used. Is obtained. When the addition amount is small, a titanium oxide porous film having a sparse distribution of pores is obtained, and when the addition amount is large, a titanium oxide porous film having a dense pore distribution is obtained. When polyethylene glycol or polyethylene oxide having a wide molecular weight distribution is added, a porous titanium oxide film having pores of various pore sizes can be obtained. Further, by stacking thin films, a titanium oxide porous film having a unique three-dimensional structure can be obtained.

Since the photocatalyst filter according to the present invention thus obtained is porous, harmful substances in the air such as foul odor and NOx or organic compounds polluting the environment such as organic solvents dissolved in water and agricultural chemicals. And redox of electrons and holes generated in the titanium oxide film by irradiation of artificial light from sunlight, fluorescent lamps, incandescent lamps, black lights, UV lamps, mercury lamps, xenon lamps, halogen lamps, metal halide lamps, etc. By the action, it can be rapidly and continuously decomposed and removed. In addition, only by irradiating light, it can be used at low cost, energy saving and maintenance-free. And, when a metal film of platinum or rhodium, ruthenium, palladium, silver, copper, iron, zinc is coated on the titanium oxide film,
The catalytic action further increases the effect of decomposing and removing organic compounds.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Among the embodiments of the present invention, particularly representative ones will be described below.

Example 1 First, a ball of alumina silicate glass having a diameter of 2 mm was placed in a ball having a diameter of 3 mm.
An alumina silicate glass filter was made by fully filling a glass silicate glass tube having a length of 20 cm and a thickness of 1 mm and heating to a temperature above the softening point and fusing. Next, 120 g of titanium tetraisopropoxide was diluted with 1000 ml of isopropanol, and while stirring, 40 g of diisopropanolamine and 10 g of water were added.
10 g of polyethylene glycol was added to prepare a transparent sol solution, and the surface of the alumina silicate glass filter obtained by the dip coating method was coated with a titanium oxide film. That is, a quartz glass plate was immersed in the sol solution and pulled up, and after sufficiently dropping the sol solution, dried, and heated and gradually heated from room temperature to a temperature of 680 ° C. This was repeated seven times to form a titanium oxide film on the surface of the quartz glass plate. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase. When the surface was observed with an electron microscope, it was found to be covered with pores having a size of about 10 nm. Using this photocatalytic filter, NOx was decomposed and removed. While irradiating the photocatalytic filter with a 500 W high-pressure mercury lamp, NOx 100 ppm was supplied at 30 ml / m2.
It flowed at an im flow rate, and the concentration of NOx contained in the air at the outlet was analyzed using a gas chromatograph. as a result,
The concentration of NOx was reduced to 5 ppm. When the photocatalytic filter was not used, the NOx concentration hardly decreased.

Example 2 First, a quartz glass ball having a diameter of 3 mm was placed with a diameter of 5 cm and a length of 30 mm.
A quartz glass filter was made by filling the glass tube into a 2 mm thick quartz glass tube, heating it to a temperature above the softening point and fusing it. Next, 135 g of titanium tetraisopropoxide was added to 1
Dilute with 200 ml of absolute ethanol and, with stirring,
45 g of N-ethyldiethanolamine and 12 g of water were added, and polyethylene glycol 1 having a molecular weight of 1500 was further added.
2 g was added to prepare a transparent sol solution. The sol solution was put through the opening of the obtained quartz glass filter and allowed to flow. The sol solution was sufficiently shaken off, dried, heated and gradually heated from room temperature to a temperature of 640 ° C., and fired. This is 7
This was repeated twice to form a titanium oxide film on the surface of the quartz glass filter. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase.
The surface was observed with an electron microscope.
It was covered with pores of nm size. Using this photocatalyst filter, the odorous substances were decomposed and removed. 500W
While irradiating the xenon lamp on the photocatalytic filter
50 ml of 80 ppm of trimethylamine as a malodorous substance
/ Mim, and the concentration of trimethylamine contained in the air at the outlet was analyzed using a gas chromatograph. As a result, the concentration of trimethylamine was reduced to 5 ppm. When the photocatalytic filter was not used, the concentration of trimethylamine hardly decreased.

Example 3 First, a ball of 96% silicate glass having a diameter of 5 mm was placed in a ball having a diameter of 10 mm.
A 96% silicate glass filter was prepared by fully filling a cylindrical mold having a length of 50 cm and a temperature of above the softening point and fusing. Next, 60 g of titanium tetraethoxide was added to 4 g
After diluting with 00 ml of absolute ethanol and stirring, 20 g of diethanolamine and 4 g of water were added, and 0.8 g of polyethylene glycol having a molecular weight of 20,000 was further added to prepare a transparent sol solution, which was obtained by a dip coating method. The surface of a 96% silicate glass filter was coated with a titanium oxide film. That is, 96
% Silicate glass filter is immersed and pulled up, after the sol liquid is sufficiently dropped, dried, and gradually from room temperature to 630 ° C.
And baked. Repeat this 7 times to get 9
A titanium oxide film was formed on the surface of a 6% silicate glass filter. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase. Also,
When the surface was observed with an electron microscope, it was found to be about 350 nm.
Was covered with small pores. This photocatalytic filter was used to decompose tetrachloroethylene, which is currently widely used as a solvent and cleaning agent in the high-tech industry and the cleaning industry, and has become a problem by contaminating groundwater and soil. Put a photocatalyst filter in a quartz tube with an inner diameter of 10 cm,
While irradiating light from a 500 W high-pressure mercury lamp, an aqueous solution of tetrachloroethylene having a concentration of 100 ppm and bubbling oxygen was flowed at a flow rate of 50 ml / mim, and the outlet concentration was analyzed using a gas chromatograph. As a result, the amount of tetrachloroethylene was 96%. Had decreased. When the photocatalyst filter was not used, the amount of tetrachloroethylene contained in the reaction solution hardly decreased.

Example 4 First, a borosilicate glass ball having a diameter of 6 mm was placed in an 8 cm diameter.
A borosilicate glass filter was prepared by fully filling a 50 cm long cylindrical carbon mold and heating it to a temperature above the softening point to fuse it. Next, 80 g of titanium tetrabutoxide was diluted with 600 ml of t-butyl alcohol, and 28 g of triethanolamine and 6 g of water were added with stirring.
Further, 6 g of polyethylene oxide having a molecular weight of 2000 was added to prepare a transparent sol solution, and the surface of the borosilicate glass filter obtained by the dip coating method was coated with a titanium oxide film. That is, a quartz glass plate was immersed in the sol solution and pulled up, and the sol solution was sufficiently dropped, dried, heated and gradually heated from room temperature to 690 ° C. and fired. This was repeated seven times to form a titanium oxide film on the surface of the borosilicate glass filter. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase. When the surface was observed with an electron microscope, it was found to be covered with pores having a size of about 50 nm. Using the obtained photocatalytic filter, 4-nitrophenylethylphenylphosphinate, which is an organic phosphorus-based pesticide, was decomposed. Inner diameter 8
A photocatalyst filter was placed in a quartz tube having a diameter of 500 cm, and while irradiating light from a 500 W xenon lamp, an aqueous solution of 4-nitrophenylethylphenylphosphinate having a concentration of 500 ppm to which oxygen was bubbled was passed at a flow rate of 40 ml / mim, and the outlet As a result of analyzing the concentration using a gas chromatograph, the amount of 4-nitrophenylethylphenylphosphinate was reduced by 90%. When the photocatalyst filter was not used, the amount of 4-nitrophenylethylphenyl phosphinate tetrachloroethylene contained in the reaction solution hardly decreased.

[0020]

As described above, the present invention can continuously and efficiently decompose and remove environmental pollutants such as odors, harmful substances in the air, and organic compounds dissolved in water. Moreover, it is an object of the present invention to provide a photocatalyst filter having excellent characteristics in terms of economy, safety, water resistance, heat resistance, light resistance, weather resistance, stability and the like, and a method for producing the same. The titanium oxide used in the present invention is also used in paints, cosmetics, toothpastes, etc., and has many advantages such as low cost, excellent weather resistance and durability, non-toxicity and safety. The photocatalytic filter according to the present invention is capable of reducing the odor and harmful substances in the air such as NOx and SOx by the redox action of electrons and holes generated in titanium oxide on the filter surface by receiving light from the outside such as an electric lamp or sunlight. Alternatively, it decomposes organic compounds polluting the environment such as organic solvents and pesticides dissolved in water. Since the photocatalytic filter according to the present invention is formed by fusing transparent heat-resistant glass pellets, the surface area is large, and the titanium oxide covering the surface is transparent and the incident light hits the entire titanium oxide on the filter surface. Therefore, environmental pollutants can be quickly and effectively decomposed and removed by photocatalysis. Further, since the titanium oxide on the filter surface is porous, even if the concentration of the environmental pollutant is low, it can be adsorbed and quickly and efficiently decomposed and removed.
Also, compared to conventional methods such as ozone treatment, it is only necessary to irradiate light without using toxic substances such as ozone,
Since light from a lamp or natural light may be used, it can be used for a long time without any cost, energy saving, safety and maintenance free. INDUSTRIAL APPLICABILITY The photocatalyst filter according to the present invention can be used not only for deodorizing interiors of cars, living rooms, kitchens, toilets, etc., for treating wastewater, for purifying pools and stored water, but also for effectively preventing the growth of fungi and mold. Applicable to

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication B01J 21/06 B01J 35/02 ZABJ 35/02 ZAB C01G 23/053 C01G 23/053 C02F 1/30 ZAB C02F 1/30 ZAB B01D 53/36 J

Claims (8)

(57) [Claims] 1. An oxide titanium oxide having pores with uniform pore diameters on the surface.
The surface is coated with a tin film and a spherical heat-resistant glass is fused
A photocatalytic filter characterized by being made. 2. The titanium oxide film has a pore diameter of 1 nm to 2 nm.
2. The photocatalyst filter according to claim 1, wherein
Luther. 3. The crystal form of the titanium oxide film is anatase.
The photocatalyst filter according to claim 1, wherein: 4. A heat-resistant glass pellet is fused,
Contains Tylene glycol or polyethylene oxide
After coating the titania sol,
A method for producing a photocatalyst filter. 5. Polyethylene glycol or polyethylene
The molecular weight of lenoxide is 1000 or more.
A method for producing a photocatalytic filter according to claim 4. 6. Polyethylene glycol for titania sol
The amount of coal or polyethylene oxide added
5. The photocatalyst according to claim 4, wherein the photocatalyst is equal to or less than the resolution.
Manufacturing method of filter. 7. From 600 ° C. to 700 ° C. gradually from room temperature.
It is characterized by heating and heating to the final temperature of C and firing.
The method for producing a photocatalytic filter according to claim 4. 8. The method according to claim 8, wherein the titania sol is an alkoxide of titanium.
Specially, it is prepared from alcohol amines.
A method for producing a photocatalytic filter according to claim 4.