JPH07148434A - Photocatalyst and water cleaning method using the same - Google Patents

Abstract

PURPOSE:To obtain a photoctalyst which maintains its function over a long period of time and can be separated easily by simple operation from a system of water to be treated by depositing photo-semiconductor particles on the surfaces and the pare walls of inorganic porous particles. CONSTITUTION:A photocatalyst is made by depositing photo-semiconductor particles on the surfaces and pare walls of inorganic porous particles. Natural or artificial minerals can be used for inorganic porous particles; however, in view of the porosity and cost of the particles, natural minerals such as scoria, burnt perlite, pumice, and vermiculite are used preferably. Titanium oxide which has a high catalytic function and is chemically stable and harmless is preferable as a photo-semiconductor having a photocatalytic function. The photocatalyst having an average particle size of 0.1-100mm, preferably 1-100mm, is desirable in terms of less outflow of the catalyst itself and easy handling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst and a method for purifying water using the photocatalytic function.

[0002]

2. Description of the Related Art Domestic wastewater, irrigation wastewater or industrial wastewater contains a large amount of substances such as nitrogen and phosphorus, which cause eutrophication phenomenon in lakes, rivers and sea bays. When algae such as plankton, picoplankton, water-bloom, and red-crown grow due to eutrophication, water becomes musty due to odorous substances such as holmium, which is a type of plankton, or 2-methylisoborneol, which is an odor substance produced by oscillatria. Forming a so-called water flower or freshwater red tide that adversely affects the water supply, or colors the water of lakes and rivers green, brown, or forms a so-called red tide that colors seawater reddish brown, pink, brown, It damages the landscape, digests oxygen in the water to cause oxygen deficiency, and the plankton that is generated clogging the gills of fish, which causes great damage to fisheries.
Furthermore, the algae that have propagated interfere with the water purification process, such as clogging filter tanks such as water purification plants and dams and filtration screens. In addition, domestic wastewater, irrigation wastewater, or industrial wastewater contains fungi such as mold, fungi such as actinomycetes, and bacteria such as Escherichia coli, which may grow in lakes, rivers, sea bays, and the like. Fungi include harmful diseases such as infectious disease bacteria such as typhoid fever and Shigella, sulfur bacteria that promote corrosion, iron bacteria, sulfate-reducing bacteria, slime-producing bacteria and fungi, and actinomycetes that smell water. Not a few, various types of damage have occurred. Especially, in the ponds and aquariums where aquatic animals such as fish, shellfish, crabs, shrimps, and frogs and aquatic plants such as seaweed and seaweed are cultivated, and in ornamental ponds and aquariums where fish are raised, excretion is further Also, due to food and spoilage of foods, water often becomes dirty and odors are emitted, and excrements and spoilage of foods often cause fungi and bacteria. In addition to the above, domestic wastewater, irrigation wastewater, or industrial wastewater may contain oxygen-requiring substances such as detergents and oils, and harmful substances such as organic halogen compounds and pesticides contained in the wastewater of semiconductor manufacturing plants. , Lakes, rivers,
May pollute sea bays and damage organisms.

In order to kill or sterilize the algae, fungi, and bacteria that have grown, for example, a method of treating with a chlorine, ozone, copper sulfate, ultraviolet ray or the like is adopted. Further, in order to remove odorous substances and coloring substances generated by algae, fungi and bacteria, for example, a method of adsorbing them on activated carbon has been adopted. In particular, in water purification plants that take water from polluted lakes and rivers, a large amount of activated carbon is administered to improve water quality. On the other hand, when photo-semiconductor particles such as titanium oxide are irradiated with light having a wavelength having an energy larger than the band gap, photoexcitation produces electrons in the conduction band and holes in the valence band. A method of sterilizing or deodorizing using a strong reducing power and a strong oxidizing power of holes has been proposed.

[0004]

Although the above-mentioned method of treating with chlorine or ozone can reduce algae, fungi, and bacteria, its effect is not sufficient, and the treatment time is long, There is a problem that the used drug and the compound generated from the drug remain in the water to be treated. The activated carbon adsorption method can reduce odor and coloring, but does not kill algae, fungi, and bacteria. In the method using the above-mentioned photo-semiconductor particles, in order to improve the utilization efficiency of the irradiation light and to obtain a high photocatalytic function, the ultra-fine photo-semiconductors are usually treated in a dispersed state. For this reason, it is necessary to separate the optical semiconductor particles from the water system to be treated, but this separation operation may be extremely difficult and has not yet been put to practical use.

[0005]

[Means for Solving the Problems] The present inventors have paid attention to the photocatalytic function of photo-semiconductor particles and killed harmful organisms such as algae, fungi and bacteria contained in the water to be treated to remove harmful substances. As a result of various studies on the method of decomposing and purifying the water to be treated, (1) in order to facilitate the separation operation of the photo-semiconductor particles used as a photocatalyst, a substance having photo-semiconductor particles attached to various carrier surfaces was used. In some cases, contact between substances or contact with water to be treated causes wear or destruction of the substance, and the photo-semiconductor particles are separated from the substance surface, or the surface to which the photo-semiconductor particles are not attached appears. The photocatalytic function of the substance is deteriorated in a short period of time. On the other hand, when inorganic porous particles are used as the carrier, the photocatalytic function is caused by the photo semiconductor particles existing in the pores of the inorganic porous particles. For a long time Can be maintained over with, disposed at a position capable of contacting the water to be treated (2) such photocatalyst,
Then, by irradiating the photocatalyst with light containing ultraviolet rays, algae killing, sterilization, deodorization, decolorization or decomposition of harmful substances can be carried out easily and easily, and water to be treated can be purified, (3) In addition, optical semiconductor particles and microorganisms having a water purification function can be attached to the inorganic porous particles, and the water to be treated can be treated for a short time by the photocatalytic function of the optical semiconductor particles and the water purification function of the microorganisms. It was found that it can be purified. Based on these findings, further research was conducted to complete the present invention.

That is, the present invention is to provide a photocatalyst having a stable photocatalytic function over a long period of time.
Further, using the photocatalyst of the present invention, water in lakes and rivers, seawater, water in water reservoirs such as storage tanks, water in water supply / hot water supply equipment and air conditioning equipment using solar energy, bath water, pool Domestic water such as irrigation water, tap water, drinking water, or water used for domestic purposes, water in aquaculture area, as well as domestic wastewater discharged from each household or industrial wastewater discharged from golf courses. It is to provide an optimal method for purifying water to be treated such as waste water.

The present invention is a photocatalyst body comprising photo-semiconductor particles adhered to at least a part of the surface of the inorganic porous particles and at least a part of pore walls of the inorganic porous particles. In particular, a photocatalyst body obtained by filling the pores of the inorganic porous particles with photo semiconductor particles is preferable. In the present invention, the term “inorganic porous particles” refers to inorganic particles having pores in the particles, and natural minerals or artificially produced particles can be used. Examples of natural minerals include andesite, quartz andesite, rhyolite, shale, sandstone, and lithic material, and other porous rocks, pumice tuff,
Mudstone, gravel, sand, silt, clay and volcanic ash, substances containing porous rock, scoria, scoria tuff, substances containing scoria, calcined perlite, calcined obsidian, calcined pumice, vermiculite, zeolite, mica, Coral sand, sea shell, bakuhanseki (main component: SiO ₂ about 70%,
Al ₂ O _{3 (} about 14%, Fe ₂ O ₃ about 2-3%) and the like can be used. Further, as the artificial inorganic porous particles, artificial pumice, artificial gravel, artificial sand, mesalite (main component: SiO ₂ about 70%, Al ₂ O ₃ about 15%, Fe ₂ O
₃ about 5%, made by Nippon Mesalite Kogyo Co., Ltd., Krisvar (main component: SiO ₂ about 86-87%, Al ₂ O ₃ about 5
7%, Fe ₂ O ₃ about 1 to 3%), artificial aggregates, porous glass, hollow glass, porous blocks, ceramics, and the like can be used. Furthermore, synthetic zeolite, ceramics such as expandable silica, activated carbon, charcoal, charcoal, coke, fly ash, blast furnace slug, foamed concrete (ALC), inorganic porous particles such as lightweight concrete are used as they are or after granulation and molding. You can also In the present invention, natural minerals are preferable because they have large pore volumes and are inexpensive.

The photo-semiconductor particles having a photocatalytic function include known photo-semiconductors such as titanium oxide, zinc oxide, tungsten oxide, iron oxide, strontium titanate, molybdenum sulfide and cadmium sulfide, which may be used alone or in combination of two or more kinds. Can be used. In particular, titanium oxide, which has a high photocatalytic function, is chemically stable, and is harmless, is preferable. In the present invention, titanium oxide includes, in addition to titanium oxide, those generally called hydrous titanium oxide, hydrated titanium oxide, metatitanic acid, orthotitanic acid, titanium hydroxide and the like, and the crystal form thereof does not matter. . The titanium oxide can be obtained by various known methods. For example, a method of hydrolyzing a titanium compound such as titanyl sulfate, titanium chloride, or an organotitanium compound in the presence of seeds for nucleation, if necessary, and titanyl sulfate in the presence of seeds for formation of nucleation, if necessary. , A method of neutralizing by adding an alkali to a titanium compound such as titanium chloride or an organic titanium compound, a method of vapor-phase oxidizing titanium chloride or an organic titanium compound, a method of firing the titanium oxide obtained by the above method Is mentioned. In particular, the titanium oxide obtained by the above method is preferable because it has a high photocatalytic function. In order to improve the photocatalytic function of the photo-semiconductor particles, platinum, gold, silver, copper, palladium, on the surface of the photo-semiconductor particles,
A metal such as rhodium or ruthenium or a metal oxide such as ruthenium oxide or nickel oxide may be coated.

Further, the present invention is a photocatalyst body comprising photo-semiconductor particles and microorganisms having a water purification function attached to the surface of the inorganic porous particles and the pore walls of the inorganic porous particles. As the microorganism having a water purification function, at least one selected from the group consisting of nitrite bacteria, nitric acid bacteria, and sulfur bacteria is preferable. In order to attach a microorganism having a water purification function, the inorganic porous particles or the inorganic porous particles to which the photo-semiconductor particles are attached are immersed in a solution in which the microorganism is cultivated, or the solution in which the microorganism is cultivated is treated with an inorganic porous material. It is possible to use a method of spraying fine particles or optical semiconductor particles onto the inorganic porous particles to which they are attached. The adhered amount of microorganisms having a water purification function can be set appropriately.

In the photocatalyst of the present invention, inorganic porous particles are appropriately selected, and the amount of photo-semiconductor particles attached is appropriately selected.
The apparent specific gravity of the obtained photocatalyst can be adjusted arbitrarily. When the apparent specific gravity of the photocatalyst body is larger than 1, the photocatalyst body sinks and is fixed on the water bottom, and the outflow of the photocatalyst body is reduced, which is preferable. Further, if the apparent specific gravity is 1 or less, it is necessary to take measures to prevent the outflow of the photocatalyst, but the photocatalyst floats or floats in the water to be treated, resulting in the treatment of algae or the like. It is possible to improve the photocatalytic function by further improving the contact with the photocatalyst. The photocatalyst of the present invention has an average particle size of 0.1 mm or more, particularly 0.1 mm or more.
It is preferable that the thickness is -100 mm, more preferably 1-100 mm, because the photocatalyst itself is less outflowed and is easy to handle. The amount of the photo-semiconductor particles attached can be set appropriately, but is 0.5 to 70% by weight based on the weight of the inorganic porous particles.
The degree is appropriate.

In order to obtain the photocatalyst of the present invention, the above-mentioned photo-semiconductor particles are suspended in a solvent such as water, alcohol or toluene. If necessary, various dispersants and binders may be added. A method of impregnating the obtained suspension with inorganic porous particles, performing degassing treatment if necessary, and impregnating the particles,
It is applied to the inorganic porous particles using a method such as dip coating, or the suspension is sprayed on the inorganic porous particles, and then dried to form at least a part of the surface of the inorganic porous particles and the inorganic porous particles. Photo-semiconductor particles are attached to at least a part of the pore walls, and the photo-semiconductor particles are filled in the pores. The adhered optical semiconductor particles may be fired if necessary, and the firing can firmly adhere the optical semiconductor particles to the inorganic porous particles.
The firing is 100 ° C. or higher, preferably 200 to 800.
It is suitable to bake at a temperature of ℃, particularly preferably 300 to 800 ℃. In particular, it is preferable that the titanium oxide obtained by the above method is highly dispersed in a solvent to form a titanium oxide sol, and the titanium oxide sol is applied or sprayed. It is also possible to hydrolyze or neutralize a compound capable of forming an optical semiconductor in the presence of inorganic porous particles to adhere the optical semiconductor particles to the inorganic porous particles, and then dry or calcine. Furthermore, the photo-semiconductor particles and the inorganic porous particles may be mixed with a mixer or the like, and then the obtained mixture may be dried or calcined. Thus, the photocatalyst body of the present invention is obtained.

In order to purify water to be treated using the photocatalyst of the present invention, lakes, rivers, sea bays, lakeshores, riverbanks, coasts, running waterways, water reservoirs, filters, or aquatic animal breeding areas, etc. The photocatalyst is placed at a position where it can come into contact with the water to be treated, or the photocatalyst is placed in the water to be treated. Next, the arranged photocatalyst is irradiated with light containing ultraviolet rays to purify the water to be treated by utilizing the photocatalytic function of the photosemiconductor particles. Examples of the light containing ultraviolet rays include sunlight, fluorescent lamps, black lamps, xenon flash lamps, and mercury lamps. Particularly, light containing near-ultraviolet rays of 300 to 400 nm is preferable. In the present invention, the water to be treated can be purified by sunlight or light from a fluorescent lamp. The irradiation amount and irradiation time of the light containing ultraviolet rays can be appropriately set according to the degree of contamination of the water to be treated. The method of irradiating the photocatalyst with light containing ultraviolet rays can be appropriately selected, for example, irradiation from above the water surface, irradiation by setting a light source in the water to be treated, or purification of the water to be treated in the water tank. In this case, irradiation can be performed from the side surface of the water tank. Further, the photocatalyst of the present invention is arranged at the above-mentioned location where it can come into contact with water to be treated, and then the photocatalyst is irradiated with light containing ultraviolet rays. At the location in the same reaction system where the water to be treated can be purified by the above method and is not irradiated with light containing ultraviolet rays, the microorganisms having the water purification function generated in the reaction system adhere to the inorganic porous particles. By preliminarily attaching a microorganism having a water purification function to the photocatalyst, purification by the microorganism can be performed.

[0013]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. Example 1 Acidic titania sol (CS-C manufactured by Ishihara Sangyo Co., Ltd.) obtained by heating and hydrolyzing titanyl sulfate was 40 based on TiO _2.
Diluted with water to g / l. Next, the diluting solution was impregnated with horticultural pumice stone hugaga soil (trade name, manufactured by Hyuugachi Sales Co., Ltd., average particle diameter 15 mm) for 2 hours, and then ammonia water was added to neutralize the pH to 7. Titanium oxide was attached to the surface of the hail soil and the pore walls of the hail soil. Succeedingly, the hail to which titanium oxide is attached separates the soil by filtration,
After washing with water and drying, the product was baked in the air at a temperature of 600 ° C. for 2 hours. Next, the calcined hail was washed with water and dried to obtain a photocatalyst A (apparent specific gravity 1.0). The amount of titanium oxide deposited on this photocatalyst A was 2.5 parts by weight with respect to 100 parts by weight of Hyuga soil.

Comparative Example In Example 1, the hail soil without titanium oxide was used as a comparative sample.

2 kg of the photocatalyst A of Example 1 and Comparative Example 1
2 kg of each sample is spread on the bottom of the water tank, 50 liters of water to be treated is put, and the 20 W fluorescent lamp 2 is placed from the outside of the water tank.
20 goldfish (Japanese gold) were bred while irradiating light with a book. In addition, 0.5 g of food was administered to this aquarium twice a day. The treated water after 3 weeks was collected from the water tanks of Example 1 and Comparative Example 1 and the transmittance at a wavelength of 600 nm was measured, and it was found that the treated water of Example 1 had a transmittance of 95.0%. On the other hand, the transmittance of the water to be treated in Comparative Example 1 was 28.2%, and in Example 1, a remarkable effect of preventing water contamination was recognized. In the aquarium of Comparative Example 1, phytoplankton was found to occur after 1 week, but in the aquarium of Example 1, phytoplankton was scarcely observed until after 3 weeks. Then, after a further 2 weeks, generation of green phytoplankton was observed on a part of the surface of the photocatalyst A, but after 2 to 3 days, the green phytoplankton was blackened. This was due to the death of phytoplankton due to the photocatalytic function of titanium oxide.
From this, it was confirmed that titanium oxide has an algicidal function. Further, the number of viable bacteria and the number of coliforms in the water to be treated 4 weeks after the start of the test was examined by the following method. Although the number of cells / ml was present, the treated water of Comparative Example 1 had a viable cell count of 8000 cells / ml and a coliform cell count of 470.
There were 0 cells / ml, and the photocatalyst A could suppress the growth of fungi and bacteria. It was confirmed that the photocatalytic function of the photocatalyst A hardly changed for 2 years.

<Method for measuring the number of viable fungi and coliforms> The collected water is diluted 10 times or 100 times with sterile water, and 1 ml is dispensed to each of 5 sterilized petri dishes.
l, and after stirring, the mixture was incubated at 37 ° C. overnight, and the next day,
The number of colonies was counted. <Used medium> Viable cell count: Brain heart infusion broth (manufactured by Nissui) Number of coliforms: Desoxycholate medium (manufactured by Nissui)

Example 2 400 g / l acidic titania sol based on TiO ₂ (manufactured by Ishihara Sangyo Co., Ltd., obtained by heating and hydrolyzing titanyl sulfate)
CS-C) was impregnated with horticultural pumice stone Hyuga soil (trade name, manufactured by Hyuga Earth Sales Co., Ltd., average particle diameter 15 mm) for 2 days, and then the Hyuga soil was separated by filtration, washed with water and dried, Titanium oxide was adhered to the surface of the soil and to the pore walls of this soil, and titanium oxide was filled into the pores of the soil. Succeedingly, the mulberry soil to which titanium oxide was adhered was fired in the atmosphere at a temperature of 600 ° C. for 2 hours. Then, the calcined hail was washed with water and dried to obtain a photocatalyst B (apparent specific gravity 1.2). The amount of titanium oxide adhered to this photocatalyst B was 35 parts by weight with respect to 100 parts by weight of hyokyu soil.

The photocatalyst B of Example 2 (300 g) was spread on the bottom of a water tank containing 50 liters of water to be treated from Lake Biwa, which is used for domestic water, and the black odor was emitted from the outside of the water tank with two black lights. The change in the concentration of the component 2-methylisoborneol was examined. 27 before light irradiation
The concentration of 2-methylisoborneol that was ppt was
Within 30 minutes after the light irradiation, it was reduced to 10 ppt, where most people did not feel a musty odor. It was confirmed that the photocatalytic function of the photocatalyst B was almost unchanged for 2 years. In addition,
When the domestic wastewater was similarly treated using the photocatalyst B, organic matter contained in the domestic wastewater was decomposed to produce C
The OD value decreased.

As a comparative experiment, the same treatment as in Example 2 was conducted except that the photocatalyst B was not used, and the change in the concentration of 2-methylisoborneol was examined. As a result,
It was found that the concentration of 2-methylisoborneol did not change. When the domestic wastewater was treated in the same manner, the organic matter contained in the domestic wastewater was not decomposed and the COD value did not change.

Example 3 Nitrosomonas and Trobar as nitric acid bacteria
After immersing 1 kg of the photocatalyst B prepared in Example 2 in a solution prepared by dispersing the culture solution of or in 2 liters of sterilized water for 1 hour, the photocatalyst B is separated and air-dried at room temperature to provide a water purification function. A photocatalyst C of the present invention having the attached microorganisms and photo-semiconductor particles was obtained.

1 kg of the photocatalyst B of Example 2, 1 kg of the photocatalyst C of Example 3, and a sample 1k of Comparative Example 1 as a comparative sample.
g, a commercially available nylon wool filter (Comparative Example 2) was used as a comparative sample in a container (W320 mm × L11).
5 mm × H 100 mm) and the filling height was 80 mm. 50m from the overflow water surface when water is poured into these containers
A 10 W black light (one) was installed at a height of m, and a pump for sending water. The above-mentioned container is placed on an aquarium (50 liters of water) in which 20 goldfish are bred, and water in the aquarium is sent to this container, water is circulated, and NH which is toxic to fish is used.
₄ , changes in NO ₂ concentration were investigated. The change in concentration of NH ₄ in Table 1, the change in concentration of NO ₂ in Table 2, further, Table 3 shows the change in concentration of nitrate (NO ₃₎ the NO ₂ generated by oxidation. It was found that when the photocatalysts B and C of Examples 2 and 3 were used, the concentrations of NH ₄ and NO ₂ were kept low. In particular, the effect of the photocatalyst C having the microorganism having a water purification function and the photo-semiconductor particles adhered was more remarkable. This is due to the photocatalytic function of the photo-semiconductor particles.
This is because H ₄ and NO ₂ were oxidized to nitric acid (NO ₃ ) having low toxicity. Further, in the case of the photocatalyst C, the photocatalyst function of the photocatalyst in the place where the light containing the ultraviolet ray is irradiated, and the photocatalyst in the place in the same reaction system where the light containing the ultraviolet ray is not irradiated. NH ₄ and NO ₂ are converted to nitric acid (N
This is because it was further oxidized to O ₃ ). On the other hand, when the sample of Comparative Example 1 used as a comparative sample and the nylon wool filter of Comparative Example 2 were used, the concentrations of NH ₄ and NO ₂ were found to be high. Even when these comparative samples were used, N
It is speculated that the concentration of H ₄ decreases because the microorganisms that have grown gradually purify water.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

Example 4 400 g / l of an acidic titania sol (manufactured by Ishihara Sangyo Co., Ltd., CS-N) based on TiO ₂ obtained by heating and hydrolyzing titanyl sulfate was converted to mesalite (trade name, manufactured by Nippon Mesalite Kogyo Co., Ltd.). , Average particle size 5 mm) was impregnated with 400 g for 1 hour, and then the mesalite was separated by filtration and dried to attach titanium oxide to the surface of the mesalite and the pore walls of the mesalite, and further the titanium oxide was added to the pores of the mesalite. Filled inside. Successively, the mesalite to which titanium oxide was adhered was fired in the atmosphere at a temperature of 500 ° C. for 2 hours. Next, the calcined mesalite was washed with water and dried to obtain the photocatalyst D of the present invention. The amount of titanium oxide deposited on this photocatalyst D was 2.0 parts by weight based on 100 parts by weight of mesalite. After putting 25 g of the photocatalyst D into an 8 liter glass container, 70 ppm of acetaldehyde which is a malodorous component
And the glass container was sealed. Next, when the surface of the photocatalyst D was continuously irradiated with black light so that the ultraviolet light intensity became 1.6 mW / cm ² , the concentration of acetaldehyde in the glass container was 20 p after 1 hour.
It decreased to 6 ppm after 2 hours, and acetaldehyde was efficiently decomposed by the photocatalytic function of titanium oxide.

[0026]

INDUSTRIAL APPLICABILITY The present invention is a photocatalyst body comprising photo-semiconductor particles adhered to at least a part of the surface of inorganic porous particles and at least a part of pore walls of the inorganic porous particles. Since it has a stable photocatalytic function over a period of time and is extremely easy to separate from the water to be treated, various photocatalytic reactions such as decomposition and purification of malodorous gas, purification of air, sulfur oxide and nitrogen oxidation It is useful as it can be used for oxidation of materials, sterilization of soil, water decomposition reaction, carbon dioxide immobilization reaction and the like. In particular, the photocatalyst of the present invention is placed at a location where it can come into contact with the water to be treated, and then, when the photocatalyst is irradiated with light containing ultraviolet rays, algae contained in the water to be treated due to the photocatalytic function of the photo-semiconductor particles, It is extremely useful as a water purification method not only for industrial use but also for general households because it can easily and easily kill pests such as fungi and bacteria, decompose harmful substances, and further deodorize and decolorize. . Furthermore, pathogenic bacteria such as Ogusale's disease that occur in a feeding area of fish and the like can be sterilized, and the death of fish and the like can be prevented. Further, the present invention is a photocatalyst body comprising photo-semiconductor particles and microorganisms having a water purification function adhered to the surface of the inorganic porous particles and the pore walls of the inorganic porous particles, which contains ultraviolet rays. The water to be treated can be purified by the photocatalytic function of the photocatalyst at the location where it is irradiated with light, and the water purification function adhered to the photocatalyst at the location in the same reaction system where it is not exposed to the light containing ultraviolet rays. Since the water to be treated can be purified by the microorganism having, the water to be treated can be purified in a short time. Further, the photocatalyst of the present invention is highly safe, has a wide range of applicable harmful substances, and does not pollute the environment even if it is discarded, and thus is industrially very useful.

Claims (8)

[Claims] 1. A photocatalyst body comprising photo-semiconductor particles adhered to the surface of inorganic porous particles and the pore walls of the inorganic porous particles. 2. A photocatalyst body comprising photo-semiconductor particles and microorganisms having a water purification function adhered to the surface of the inorganic porous particles and the pore walls of the inorganic porous particles. 3. The photocatalyst body according to claim 1, which has an average particle diameter of 0.1 to 100 mm. 4. The photocatalyst body according to claim 1 or 2, wherein the photo-semiconductor particles are titanium oxide. 5. The photocatalyst body according to claim 1 or 2, wherein the inorganic porous particles are natural minerals. 6. A nitrite bacterium having a water purification function,
The photocatalyst body according to claim 2, wherein the photocatalyst body is at least one selected from the group consisting of nitric acid bacteria and sulfur bacteria. 7. The photocatalyst according to claim 1 or 2 is arranged at a location where it can come into contact with water to be treated, and then the photocatalyst is irradiated with light containing ultraviolet rays to purify the water to be treated. A method for purifying water, which is characterized in that 8. The photocatalyst function of the photocatalyst is arranged by arranging the photocatalyst according to claim 1 or 2 at a position where it can come into contact with water to be treated, and then irradiating the photocatalyst with light containing ultraviolet rays. The water to be treated is purified by the above method, and at the location in the same reaction system that is not irradiated with light containing ultraviolet rays, the water to be treated is purified by microorganisms having a water purification function attached to the photocatalyst. Characterizing water purification method.