JP2000107608A - High strength photocatalyst, its production and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance fixability, separation workability and strength without reducing activity by agglomerating glass granules with a binding agent and fixing photocatalyst particles with an inorganic material as a bonding agent on the surface of the resultant agglomerate as a substrate. SOLUTION: Shirasu as volcanic ejecta particles is previously put in a pan type granulator and a sodium silicate solution and hydraulic cement are added while rotating the granulator to form the volcanic ejecta granules. The granules are put in a hermetically sealed vessel, gaseous carbon dioxide is injected, the granules are fired to obtain an agglomerate of the volcanic ejecta granules and the granules are further foamed to make them foamed particles. Titanium dioxide and an aqueous silica sol, together with glass beads, are charged into a mayonnaise bottle and dispersed with a paint conditioner to obtain a silica sol-containing coating material. After the agglomerate of the foamed volcanic ejecta granules is immersed as a substrate in the coating material, photocatalyst particles are fixed on the agglomerate and the coating material and the agglomerate are separated with a sieve and dried. By heat-treating it, the permeability and NOx removal rate are enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength photocatalyst, a method for producing the same, and uses thereof, and more particularly, to a photocatalyst using an aggregate of glass particles as a substrate, a method for producing the same, and uses thereof. .

[0002]

2. Description of the Related Art When a photocatalyst particle is irradiated with light having a wavelength having an energy greater than its band gap, electrons are generated in a conductor and holes are generated in a valence band by photoexcitation, and a strong reducing power of electrons and a strong oxidation of holes are generated. It is well known that power can be used for various reactions. The photocatalyst particles themselves are fine particles, and if used as such as a photocatalyst, solid-gas separation or solid-liquid separation after the reaction is difficult. Therefore, attempts have been made to fix and use the photocatalyst particles on a substrate larger than the photocatalyst particles.

As a method for fixing photocatalyst particles on a substrate, for example, the following methods have been proposed.

(1) Films, beads, and the like made of a light-transmitting material such as nitrocellulose, glass, polyvinyl chloride, nylon, methacrylic resin, and polypropylene.
A method in which titanium oxide fine powder is adhered to a substrate such as a board or a fiber (Japanese Patent Application Laid-Open No. 62-66861).

(2) Titanium (IV) on a porous glass support
Impregnated with an alcohol solution of tetrabutoxy oxide,
A method of heating and converting to titanium oxide of the anatase type to hold and fix it on a porous glass support (Japanese Patent Laid-Open No.
-50154).

(3) The semiconductor catalyst powder is held by a method such as press-fitting, impregnating, or adhering into a porous polymer film (for example, a polyfluoroethylene resin) having a photosensitizer such as a dye or a metal complex as a side chain. .Fixing method (Japanese Patent Laid-Open No. 58-125)
602).

(4) A method of fixing titanium oxide to a filter made of polypropylene fiber or ceramics (Japanese Patent Laid-Open No. 2-68190).

(5) A method in which a titanium oxide powder is held and fixed in the entanglement of quartz, glass and plastic fibers, and both surfaces thereof are held down with a light-transmitting glass (US Pat. No. 4,888,101).

(6) Platinum is fixed on an alumina substrate by a sputtering method, and a mixed dispersion of an anatase-type titanium oxide powder and an organic solvent solution of methyl methacrylate is applied thereon by a spin coating method. A method of thermally decomposing methyl methacrylate as a binder and converting anatase type titanium oxide to rutile type titanium oxide (Robert E. Hetri
c, Applied Physics Comuni
sessions, 5, (3), 177-187 (198
5)).

(7) A method in which titanium oxide is thermally spray-fixed to the surface of a polyester cloth by a low-temperature thermal spraying method (T. Sakurada, Surface Technology Vol. 41, No. 10, P60 (1990)).

However, each of the above-mentioned known methods for fixing the photocatalyst particles to the substrate has the following disadvantages.

First, in the case where the organic substance such as (1), (3), (4) or (5) is used as a binder, most of the organic substance is decomposed by the photocatalytic action of the photocatalyst particles. Is not reliable. In the method (2), since an expensive organic titanium compound is used as a raw material and the glass is directly fixed to a glass which is easily damaged, the reliability of strength is low. On the other hand, the methods (6) and (7) are not preferable because the temperature becomes extremely high during fixing and the high photocatalytic activity of the photocatalytic particles is lost.

Other commonly used methods include simply impregnating and fixing a slurry of titanium oxide in an inorganic porous material or fiber, or hydrolyzing or heating and melting an alkali salt such as silica or alumina. There is a method of using a binder, etc., but in the former, the titanium oxide particles are not fixed, so they easily fall off due to vibration and impact, and in the latter, the catalyst surface is coated with a binder for fixing the catalyst. There is a problem that the activity is largely lost.

Further, these methods are difficult to process, so that the cost is increased and there is a problem that light energy cannot be sufficiently utilized.

On the other hand, from a practical standpoint, the substrate to be immobilized is important from the viewpoint of workability when using the photocatalyst and operability in separating from the object to be treated. They were not always satisfactory.

Further, in recent years, the application range of the photocatalyst particles has been remarkably increased in connection with the prevention of environmental pollution. In this connection, there has been a demand for a method of fixing the photocatalytic function at low cost, firmly, and for a long time without impairing its photocatalytic function, but the conventional method has not always been satisfactory. In addition, the substrate of the photocatalyst is required to be inexpensive, have excellent fixability to the photocatalyst particles, have sufficient strength for practical use, and facilitate the operation of separating from the object to be treated. These requirements were not fully satisfied.

In connection with the above-mentioned environmental pollution prevention, photocatalytic particles are used to decompose and remove harmful gases such as aldehydes, mercaptans, and ammonia, and purify sewage such as industrial wastewater, mining wastewater, lakes and seawater. There is also a need for a simple method for sterilizing a hydroponic culture solution.

In particular, hydroponics is a resource saving in agriculture,
It is one of the production methods of vegetables and flowers for the purpose of energy saving and increase of production, and has rapidly spread in recent years.

In hydroponics, after harvesting the crop, the used culture solution is discarded, which causes contamination of groundwater and eutrophication of rivers and lakes. Therefore, establishing the culture solution recycling technique is an effective method from the viewpoint of saving resources and preventing environmental pollution. When considering the recycling of the culture solution, it is most important to remove plant pathogenic bacteria mixed during cultivation in addition to adjusting the fertilizer components.

Conventional techniques for removing plant pathogens in hydroponics include (1) drug administration, (2) ultraviolet irradiation, (3) ozone, (4)
There are heating method, (5) ultrasonic method, etc., but (1) is not permitted to register the use of mixing the drug with the culture solution, (2) is high running cost such as power and lamp replacement, (3) ) Has a low running cost, but iron and manganese in the culture solution required for growing the crop are insolubilized. (4) The total processing time (heating and cooling) is long, and the running cost is high.
(5) had a disadvantage that the effect was not clear.

[0021]

DISCLOSURE OF THE INVENTION In view of the above problems, the present inventors have found that the photocatalytic particles have excellent fixation to a substrate, are inexpensive, and can be used in both gas and aqueous solutions without lowering the activity of the photocatalytic particles. It can be used to separate
In order to provide a photocatalyst excellent in workability, a photocatalyst in which a hollow glass particle such as a hollow shirasu balloon is used as a base and a photocatalyst particle is fixed on the surface thereof with an inorganic substance as a binder has been invented and filed (Japanese Patent Application Hei 9-61132).

However, the photocatalyst is not sufficient in strength, and a photocatalyst having sufficient strength to withstand practical use has been demanded.

On the other hand, there has been conventionally known a structural material formed by solidifying with cement or gypsum using volcanic ejecta particles or volcanic ejecta foam particles as a binder. Molded articles using cement or gypsum as such a binder have a long training period (the period from pouring into a mold to solidifying into a product), a low production turnover rate, and damage during solidification. There is a problem that it is easy to receive the water, and because the specific gravity is large, the transportation cost is high, and it is impossible to float on water.

That is, from a practical point of view, the present invention is excellent in fixability to a substrate, is inexpensive, can be used for both gas and aqueous solution without deteriorating the activity of the photocatalyst particles. It is an object of the present invention to provide a photocatalyst having excellent strength for separation and workability from the material and having sufficient strength to withstand practical use, a method for producing the same, and an apparatus and method for preventing environmental pollution using the photocatalyst. .

[0025]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies from the above viewpoint, the present inventors have found that volcanic ejecta particles and volcanic ejecta foam particles are lightweight and inexpensive materials. Since the particle diameter is often 500 μm or less, the photocatalyst body is often not suitable in terms of the separation property from the object to be treated and the scattering property, and a mass of a size of 2 to 3 mm or more. Although there were some, it was found that there was a problem that the strength was insufficient, the strength unevenness was large, and further, it was not easy to adjust the particle size distribution. Therefore, the present inventors further studied and found that these volcanic ejecta particles and volcanic ejecta foam particles were granulated using a predetermined binder to form an agglomerate. The inventors have found that the distributions of these sizes are uniform, and as a result, a material having a significantly improved strength and suitable for practical use is obtained, and the present invention has been completed.

In other words, the high-strength photocatalyst of the present invention comprises a base made of a glass particle agglomerate obtained by aggregating glass particles with a binder, and fixing the photocatalyst particles on the surface thereof using an inorganic substance as a binder. It is characterized by.

In the present invention, “high strength” means
It is a sufficiently practical strength that it is not crushed by its own weight when an adult steps on it.

The glass particles include volcanic ejecta particles and / or
Alternatively, it is preferably a volcanic ejecta foam particle.

These particle agglomerates have properties required as a base for the photocatalyst, such as fixability to the photocatalyst, strength, fluidity, up-and-down in water, and high specific surface area. Has the feature that it is relatively easy to prepare, depending on the purpose of use, either alone or
Alternatively, they can be used in combination.

The agglomerate of volcanic ejecta particles as referred to herein is an agglomerate obtained by granulating volcanic ejecta particles such as shirasu, mullet, and perlite using a binder. Thing foamed particle agglomerate, the volcanic ejecta foam particles obtained by heating and foaming the volcanic ejecta particles are granulated using a binder,
It is an agglomerate.

The volcanic ejecta particles used in the present invention include:
Shirasu is preferred.

[0032] Shirasu is the white color produced in the southern Kyushu region.
It is a collective term for sediment fall associated with gray-white volcanic eruptions, and homogeneity is widely distributed throughout the country. Shirasu has a layer consisting of only pumice, which is a porous glass lump, and a layer consisting of pumice and scaly fine glass pieces. The former is called primary shirasu, and the latter is called secondary shirasu. The former is referred to as "pumice" and the latter as "shirasu", but includes up to secondary shirasu in the present invention.

The volcanic ejecta foam particles used in the present invention are preferably shirasu balloons.

The shirasu balloon is, in a narrow sense, a fine glass (Si) obtained by heat-treating fine particles of volcanic glass contained in shirasu at about 1000 ° C. for a short time.
0 ₂ 60-80%), having an average particle size of 10-500 μm.
m, spherical hollow particles having a bulk specific gravity of 0.13 to 0.70, and include, in a broad sense, those obtained by heating a mullet, but in the present invention, they are obtained by heating a mullet in a broad sense. Also included.

Shirasu balloons have extremely low bulk specific gravity.
The material is nonflammable, has a high melting point, is inactive even at high temperatures, does not generate toxic gas, is lightweight, and has excellent properties in terms of heat insulation, sound insulation, heat resistance, and the like.

As a raw material for the shirasu balloon, among the volcanic glasses contained in the shirasu, those containing a large amount of thick and massive volcanic glass having a transparent and smooth surface are used to form the balloon.
It is desired in terms of specific gravity and strength, and is practically used.

Next, a binder for producing a glass particle aggregate, which is a substrate of the high-strength photocatalyst of the present invention, will be described.

As the binder used in the present invention, alkali silicates such as sodium silicate, potassium silicate, lithium silicate and the like are used from the viewpoint of forming a light and high-strength agglomerate so as to be used as a substrate for a photocatalyst. Aluminum phosphate, frit and hydraulic cement are preferred.

In order to further increase the strength of the granules,
Combination of alkali silicate and hydraulic cement, combination of alkali silicate and hydraulic cement and aluminum monophosphate, combination of alkali silicate and hydraulic cement and frit, and combination of alkali silicate and hydraulic cement More preferred.

The hydraulic cement is a cement which hardens when water is added, and includes Portland cement, alumina cement, blast furnace cement, slag cement, silica cement, pozzolan cement, etc. Among these, alumina cement and silica cement Is preferred,
Alumina cement is most preferred.

Although the strength of the glass particle aggregate obtained using these binders is difficult to express quantitatively, it has such a strength that it cannot be crushed even if an adult steps on it under its own weight.
The photocatalyst obtained using this as a substrate also has a similar strength.

The size of the glass agglomerate is preferably 1 in consideration of the practical use surface such as the photocatalytic ability and the separation property from the object to be treated, ease of installation, recovery and scattering.
５０50 mm, more preferably 1-10 mm, most preferably 1-5 mm.

The photocatalyst particles used in the present invention include:
At least one of titanium oxide, zinc oxide, iron oxide, potassium titanate, strontium titanate, titanate fiber, molybdenum sulfide, and indium oxide can be used. Among them, titanium oxide, zinc oxide, iron oxide, and strontium titanate can be used. Are preferable, and titanium oxide is particularly preferable. Further, those obtained by adding an appropriate dopant to these photocatalyst particles can also be used.

When the photocatalyst particles are titanium oxide,
Ze type is preferred. The specific surface area is 20 to 500 m ² / g
Is preferable, and 100 to 400 m < ² > / g is more preferable. The titanium oxide particle diameter is 0.01 to
1 μm is preferred, and more preferably 0.02 to 0.1
μm, and may be a granulated product or a sintered body. When the particle size is increased by forming a granulated product or a sintered body, when the thickness of the inorganic substance is relatively large depending on the application, the inorganic substance is caught from the film, and the photocatalytic activity appears effectively.

The titanium oxide may contain a metal oxide containing an element such as W, Sn, S, Mo, V, Mn and Zn in order to improve the catalytic activity.

As with titanium oxide, the purity of other photocatalyst particles is not particularly limited. If necessary, an appropriate impurity may be added for the purpose of adjusting the band gap.

The photocatalyst of the present invention includes Ag, Cu, Z
n or a functional substance that adsorbs harmful substances such as activated carbon or zeolite.

As the inorganic substance as a binder for fixing the photocatalyst particles on the substrate, silica, alumina, clay, frit and the like can be used. Among them, silica, frit and clay are preferable, and silica is preferable. Most preferred.

When silica is used as the binder, the fixability between the silica film containing the photocatalyst particles and the glass particle agglomerate, which is a substrate containing silica as a main component, is good. When the film thickness is large, it is useless for the photocatalytic effect, and the film strength tends to decrease. Therefore, the film thickness is preferably 100 μm or less. The ratio of the photocatalyst particles in the silica film containing the photocatalyst particles is preferably 10 to 90% by weight, more preferably 2 to 90% by weight.
0-85% by weight, most preferably 40-80% by weight.

The clay is not particularly limited, but the frit is preferably a compound containing phosphorus, and is typically Li ₂ O—Na ₂ OB ₂ O ₃ —Al ₂ O ₃ —P ₂ O because of the advantage that the melting point can be lowered. Those having the composition of ₅ are more preferred.

The high-strength photocatalyst of the present invention has excellent photocatalytic effects by irradiating ultraviolet rays and has excellent effects of removing odorous gases such as aldehydes and mercaptans, NOx, dioxins, etc. and sterilizing, and has practical strength. Excellent body workability, weather resistance, and separation operability from the object.

Regarding the selection of the substrate used in the present invention, when it is preferable to sink in water, agglomerates of volcanic ejecta particles may be used as the agglomerates of glass particles. On the other hand, when using agglomerates of expanded particles of volcanic ejecta, the apparent specific gravity can be made larger or smaller than water, that is, floated and / or settled in water depending on the amount of the binder, the inorganic substance, and the photocatalyst particles. Therefore, the substrate can be selected as needed, and the photocatalyst using such a substrate can be widely used for purification of water, sterilization of water, sterilization of a culture solution for hydroponics, and the like described below.

The high-strength photocatalyst of the present invention can be used, for example, in a coating material in which photocatalyst particles are dispersed in aqueous silica sol and water, by adding agglomerates of glass particles (particularly, agglomerates of volcanic products and / or foams of volcanic products). (Agglomerated particles), and the coating is adhered to the surface thereof, followed by heat treatment at 100 to 900 ° C.

In the above-mentioned production method, a silica film containing photocatalyst particles is formed on the surface of the glass particle agglomerate serving as a substrate.

The silica sol used has a particle size of 0.1 to
It is a fine particle type of 10 nm, and a particle size of 1 to 10 nm is more preferable. If the particle size of the silica sol is large, the contact area with the photocatalyst particles becomes small, so that the adhesive force becomes weak, which is not preferable. This silica sol needs to be an aqueous silica sol that has been subjected to Na removal treatment. Aqueous silica sol, in which Na ions are left as a basic sol, is practically used as a binder for fixing photocatalyst particles for photocatalysts, since Na ions are adsorbed on photocatalyst particles and greatly attenuate the photocatalytic ability when used as a paint. There is no sex. The aqueous silica sol subjected to Na removal can be obtained, for example, by removing sodium using sodium silicate as a raw material with an ion exchange resin.

The bonding between the silica sol and the surface of the photocatalyst particles occurs at the contact point between the sol particles and the photocatalyst particles, and the fine particle silica sol is suitable for the primary particle size of the photocatalyst particles of 0.01 to 1 μm considered to be preferable in the present invention. Due to the size, there are many active sites not bonded to silica on the surface of the photocatalyst particles. Therefore, the photocatalytic ability is kept high.

When the ratio (A / B) of the primary particle size (A) of the photocatalyst particles to the particle size (B) of the silica sol is in the range of 200 to 2, the number of silica sols adhered to the primary particles of the photocatalyst particles is as follows: An optimal state is obtained in terms of the balance between the adhesive strength and the resolution as the photocatalyst fixing film. When the ratio (A / B) is more than 200, the adhesive force is strong, but the silica sol almost covers the active sites on the titanium oxide surface, and the resolution is hardly recognized. On the other hand, when (A / B) is smaller than 2, the resolution is high but the adhesive strength as the fixing film is extremely reduced.

The ratio of the aqueous silica sol to the photocatalyst particles at the time of preparing the coating material is 1 based on SiO _2.
The amount is preferably from 0 to 900 parts by weight, more preferably from 15 to 4 parts by weight.
00 parts by weight, most preferably 25 to 150 parts by weight. If the addition ratio of the silica sol is less than 10 parts by weight, the strength of the photocatalytic film is reduced, and if the addition ratio of the silica sol is more than 900 parts by weight, the titanium oxide concentration in the coating film is reduced. Is not preferred because the photocatalytic ability of the compound decreases.

Even if the amount of silica sol added is increased within the above range, the photocatalytic activity hardly decreases, and the strength of the coating film increases almost in proportion to the amount added. The extra silica sol after covering the first layer forms a siloxane bond network on the silica sols each other, thereby contributing to the enhancement of the coating film strength. The lamination of silica sol has a lot of pores of nm order and the porosity of the coating film is kept relatively high at 30 to 70%, so that adsorption of decomposed gas and desorption of reaction product gas are easy and photocatalytic reaction Is not considered to be rate-limiting.

If the particle size of the fine particle silica sol is smaller than 0.1 nm, it is not suitable as a binder for a coating material which requires stability over a long period of storage because it is unstable and easily gelled due to its properties close to oligomers. On the other hand, if the particle size is larger than 10 nm, the adhesive strength between the silica sols and between the silica sol and the photocatalyst particles, and furthermore, the adhesion between the silica sol and the adhesive layer between the substrate is weak, and the peel strength as a coating film cannot be obtained.

The peel strength of the coating film can be improved by adding a low-concentration acid or a small amount of sodium silicate or sodium aluminate to the above-mentioned photocatalytic paint for the purpose of strengthening the bond of the silica sol. is there.

Depending on the type of the gas to be decomposed, the use of an adsorbent other than the photocatalyst particles in the coating film may improve the photocatalytic effect in some cases. For example, when used for NOx purification, zeolite, zinc oxide fine powder, titanium industrial adsorbent TZ-100 or the like is used as an adsorbent per 1 titanium oxide.
By adding up to 30 parts by weight, the NOx purification ability can be significantly improved.

The high-strength photocatalyst according to the present invention can be obtained not only by mixing and dispersing photocatalyst particles, fine-particle silica sol, and water to form a coating and dipping the substrate in the coating, but also by coating the substrate with the coating. Can also be manufactured.

In preparing the coating material, the addition ratio of the fine particle silica sol to the photocatalyst particle powder is from 20 to 200.
Parts by weight. If the amount is less than 20 parts by weight, adhesion between the photocatalyst particle particles and the silica sol for forming a coating film, and further, the adhesion of the coating film to the substrate is weak, and peeling occurs. Because the titanium concentration decreases, and as a result the titanium oxide concentration in the coating film decreases,
It is not preferable because the photocatalytic ability per unit area of the photocatalytic coating film is reduced.

The heat treatment after fixing is generally 100 to 9
00 ° C is preferred, and 100 ° C to 500 ° C is more preferred. The reason for defining this range is that if the temperature is lower than 100 ° C., it takes a long time for the silica sol to gel, and it is difficult to obtain a film strength. If the temperature is higher than 900 ° C., the activity of the photocatalyst particles decreases.

The high-strength photocatalyst of the present invention also comprises clay,
After adhering the frit and the photocatalyst particles or the paste containing the frit and the photocatalyst particles to the glass particle agglomerate (particularly, the volcanic ejecta particle agglomerate and / or the volcanic ejecta foamed particle agglomerate), 450- It can also be obtained by heat treatment at 1000 ° C.

That is, concretely, clay, frit and photocatalyst particles, or powder composed of frit and photocatalyst particles are mixed and kneaded into a paste using water or an organic solvent. Put an appropriate amount of glass particle agglomerates such as ejecta particle agglomerates and / or volcanic ejecta foam agglomerates, and apply lateral vibration to advance fixation of photocatalytic particles on the particle agglomerate surface, This is 45
The heating is performed at 0 to 1000 ° C, preferably 450 to 800 ° C, more preferably 450 to 600 ° C. When the heating temperature is lower than 450 ° C., the photocatalytic particles are not fixed on the substrate because the melting point is lower than the melting point of the frit, and when the heating temperature is higher than 1000 ° C., the activity of the photocatalytic particles is undesirably reduced.

According to this method, the effective surface area of the photocatalyst particles fixed on the surface is slightly reduced, but the photocatalyst does not peel off from the surface during use and the photocatalytic ability is not deteriorated, so that the solid-gas or It has the feature that solid-liquid separation is not difficult.

The high-strength photocatalyst of the present invention is prepared by using fiber, resin,
A high-strength photocatalyst container can be stored in a bag-like or mesh-like container made of at least one of nonwoven fabric, metal, and alloy.

Here, it is preferable to put a floating body in the storage container, and the floating body can be at least one of styrene foam, hollow filler, wood, and plastic.

Further, according to the present invention, the harmful gas is passed through the above-mentioned high-intensity photocatalyst or the above-mentioned high-intensity photocatalyst housing, and the container or the housing is irradiated with light containing ultraviolet rays. By decomposing harmful gas,
Can be removed.

The harmful gas referred to here includes aldehyde, mercaptan, ammonia, NOx, dioxin and the like.

Since the high-intensity photocatalyst exhibits gray, yellow, brown, and white depending on the type of photocatalyst particles and volcanic ejecta particles, it can be placed in an appropriate place such as a park or a street tree. , Can be used without spoiling aesthetics.

To decompose and remove harmful gases efficiently and simply and inexpensively, a high-intensity photocatalyst may be used in a column. That is, the high-intensity photocatalyst is placed in a column made of a material that transmits ultraviolet light, and the harmful gas is forcibly or naturally passed through the column, and the harmful gas is decomposed and removed by irradiating a lamp containing sunlight or ultraviolet light. can do. In the high-strength photocatalyst, particularly when the agglomerates of expanded particles of volcanic eruptions are used as the base material, they are lightweight and high-strength, so that gas flow is easy even when used in a column, and exchange of the photocatalyst is also easy. Easy.

Further, it is effective for removing dioxins discharged into the environment. Even when primary generation of dioxin is sufficiently suppressed in combustion, secondary generation of dioxins occurs when exhaust gas comes into contact with unburned components or dust having a catalytic action in a temperature range of 200 to 600 ° C. It has been. The high-strength photocatalyst of the present invention can be used to remove primary and secondary dioxins discharged into such an environment from the exhaust gas side. For example, there is a method in which a column filled with a high-strength photocatalyst is attached to a chimney portion of an incinerator in one stage or in multiple stages. If it is a column that transmits ultraviolet light, it can be decomposed at the same time as adsorption by using sunlight.However, if the column is easily removed, remove the adsorption column from the chimney and place it in another place. By irradiating with sunlight or an ultraviolet lamp, the adsorbed substance can be decomposed. This may be used repeatedly.

Further, the photocatalyst can be used by putting it in a frame or the like made of a material which transmits ultraviolet rays. In this case, it is easy to carry, and it is easy to install and exchange the photocatalyst.

Further, the decomposition and removal of the harmful gas can be performed in the same manner by using the high-strength photocatalyst container.

Further, according to the present invention, water is passed through the above-described high-intensity photocatalyst or the above-described high-intensity photocatalyst housing whose specific gravity is adjusted so as to float and / or settle in water, and contains ultraviolet rays. By irradiating the light, the water can be purified.

The water referred to here is factory wastewater, mining wastewater,
It includes industrial water, agricultural water, drinking water, lakes and marshes, river water, seawater, and the like. These existing lake shores, river banks, shores,
In purifying water using the high-strength photocatalyst of the present invention in a flowing water channel, a water tank, a filter, a sewer, or a breeding area of aquatic organisms, at a location that can come into contact with these waters, A photocatalyst is provided, or the high-intensity photocatalyst is placed in water. Next, the disposed high-intensity photocatalyst is irradiated with light containing ultraviolet rays to purify water.

The light containing ultraviolet rays includes, for example, light from sunlight, fluorescent lamps, black lamps, xenon flash lamps, mercury lamps and the like. Among them, light containing ultraviolet rays of 300 to 400 nm is particularly preferable. The irradiation amount and irradiation time of the light containing ultraviolet rays can be appropriately set depending on the degree of contamination of the wastewater. The method of irradiating the high-intensity photocatalyst with light containing ultraviolet rays can be appropriately selected.For example, when irradiating from the upper surface of the water, irradiating by installing a light source in the sewage, or purifying the sewage in the water tank Can be irradiated from the side of the water tank.
Further, when the high-intensity photocatalyst of the present invention is disposed at the above-mentioned place where it can come into contact with wastewater, and then irradiated with light containing ultraviolet rays, at the place to be irradiated, the wastewater can be purified by the photocatalytic function of the photocatalyst. In addition, in a part of the same reaction system that is not irradiated with light containing ultraviolet light, microorganisms having a water purification function generated in the reaction system may adhere to the substrate, or microorganisms having a water purification function in advance may be photocatalyzed. By adhering to the microorganism, purification by the microorganism can be performed.

Regarding the target treated substances in the above-mentioned sewage purification method, organic substances such as free chlorine and trihalomethane remaining in water can be decomposed and removed, and regulations have been strengthened by the revision of the Water Pollution Control Law. It can also be used to remove selenium from mining wastewater.

In the latter case, a method in which a high-intensity photocatalyst is put into mining wastewater and sunlight is used, or the high-intensity photocatalyst of the present invention is put in a column, and the mining wastewater is passed through the column to contain ultraviolet light Hexavalent selenium is reduced to tetravalent or zero-valent by a method of applying an irradiation lamp or the like and collected.

Further, as an application of the method for purifying sewage using the high-strength photocatalyst of the present invention, a pipe is immersed in water into which the photocatalyst has been charged, and the harmful gas is passed through and bubbled to decompose the harmful gas. It can also be done.

Further, in terms of the apparatus, in order to increase the efficiency of irradiating the photocatalyst with light containing ultraviolet light, a light reflecting plate is provided, the inner wall surface of the container is mirror-finished, or the inner wall surface of the container is mirror or similar. You can also install things.

In the case of purifying water, for example, using the high-strength photocatalyst of the present invention, a net or the like can be provided at the outlet of water to prevent the photocatalyst from flowing out. If the photocatalyst is put in the storage container and used as a photocatalyst storage, the outflow can be prevented and the collection can be facilitated.

When the high-strength photocatalyst storage material is to be used in a state of being suspended in water, the floating body may be put in the storage container. Styrofoam, hollow filler, wood, plastics and the like can be used as the floating body. Conversely, when you want to submerge and fix it, or when you want to avoid movement due to wind when placed on a road or street tree, if possible, you can fix it with a rope, wire, adhesive, etc. Wood, stone and metal lump may be put in the storage container as a fixing material.

Further, according to the present invention, floating in water and / or
Alternatively, the culture solution is passed through the above-described high-intensity photocatalyst or the above-described high-intensity photocatalyst housing, the specific gravity of which is adjusted to settle, and the hydroponic culture is sterilized by irradiating light containing ultraviolet rays. be able to.

The high-strength photocatalyst of the present invention can use titanium oxide or zinc oxide having a bactericidal effect against various fungi, and has an apparent specific gravity larger or smaller than water depending on the amount of the photocatalyst particles and the inorganic substance. Can also be adjusted,
Plant pathogens can be efficiently killed by being present at any position in the culture solution tank.

As a light source for promoting photocatalytic activity, an ultraviolet lamp is desirable, but the conventional intensity is not required, and the running cost can be reduced. Further, the high-intensity photocatalyst body of the present invention is provided together with the ultraviolet irradiation device in a container different from the culture solution container,
If it is connected to the culture solution container and circulated by a pump, the sterilization effect is more efficient and the maintenance of the culture solution container is improved.

Further, the culture solution for hydroponics can be sterilized in the same manner by using the above-mentioned high-strength photocatalyst storage material.

In any case, in addition to the photocatalyst, the adsorbent for harmful substances such as activated carbon and zeolite as well as the photocatalyst adjuvant and the granulated or molded product, the antibacterial substance and the antibacterial material for the photocatalyst effect auxiliary agent in any use. Appropriate amounts of granules and moldings can be added at the same time.

Hereinafter, the contents of the present invention will be described in more detail with reference to examples, but these examples are merely examples, and the scope of the present invention is not limited thereto.

[0093]

Example A: Method for producing agglomerates of volcanic ejecta particles 100 parts by weight of shirasu, which are volcanic ejecta particles, were previously charged into a pan-type granulator and, while rotating, 100 parts by weight of a sodium silicate solution; 100 parts by weight of hydraulic cement was gradually added to obtain granules of volcanic ejecta particles. Next, the granules of the volcanic ejecta particles were placed in a closed container, and carbon dioxide gas was injected. This was calcined at 900 ° C. for 1 hour to obtain an agglomerate of volcanic ejecta particles.

B: Method for Producing Agglomerates of Volcanic Effluent Foamed Particles The same procedure was carried out except that the volcanic ejecta particles in Example A were replaced with shirasu balloons of foamed volcanic ejecta particles.

Example 1 Titanium oxide (anatase type specific surface area 150 m ² / g)
6 g, aqueous silica sol (particle diameter 5 nm, primary particle diameter of titanium dioxide / particle diameter of silica sol = 4) 23.5 g was charged into a 120 ml mayonnaise bottle together with 60 g of 3 mm glass beads, and was treated with a red Devil paint conditioner for 30 minutes. The mixture was dispersed and mixed to obtain a coating containing silica sol.

Further, the agglomerate of expanded particles of volcanic ejecta having an average particle diameter of 5 mm was immersed in the above-mentioned paint using the substrate as a base, and the agglomerate of expanded particles of volcanic ejecta and the immobilized photocatalyst particles were separated by a sieve. did. After air drying all day and night, baking was performed at 150 ° C. to fix the silica film containing the photocatalyst particles to the substrate.
Heat treatment was performed at 400 ° C. for 1 hour to obtain a photocatalyst.

Example 2 Example 2 was repeated except that the amount of titanium oxide in the paint was changed to 2.6 g.

Example 3 Example 3 was repeated except that the photocatalyst particles were changed to zinc oxide.

Example 4 The procedure of Example 1 was repeated, except that the photocatalyst particles were changed to strontium titanate.

Example 5 The procedure of Example 1 was repeated, except that the base material was a volcanic ejecta particle aggregate.

Example 6 The procedure was performed in the same manner as in Example 1 except that the agglomerate of expanded particles of volcanic ejecta having an average particle diameter of 0.3 mm was used as the substrate.

Example 7 6 g of the titanium oxide powder of Example 1 and 4 g of a phosphate ester frit were mixed in a coffee mill, and the mixed powder was spread on a vat. The agglomerates of expanded particles of volcanic ejecta having an average particle size of about 2 mm, which are the base material, were put into a vat, and water was sprayed by spraying to fix the titanium oxide powder to the base while rolling. Volcanic effluent expanded particle agglomerates fixed with titanium oxide are 1
After drying at 10 ° C. for 1 hour, heat treatment was performed at 550 ° C. for 2 hours to obtain a photocatalyst.

Example 8 40 g of the sample of Example 1 and 10 spherical polystyrene foams having a diameter of 3 mm were placed in a nonwoven fabric bag of 10 cm × 10 cm to obtain a photocatalyst container.

Example 9 A 40 g sample of Example 1 was placed in a stainless steel mesh container of 10 cm × 10 cm × 2 cm to form a photocatalyst container.

Comparative Example 1 The same procedure as in Example 1 was carried out except that porcelain pumice for horticultural use was replaced with agglomerated agglomerates of expanded particles of the volcanic ejecta of Example 1.

Comparative Example 2 Only the agglomerates of expanded particles of volcanic products were used as samples.

Comparative Example 3 Only the agglomerate of volcanic ejecta particles was used as a sample.

Comparative Example 4 A coating material in which the titanium oxide of Example 1 was dispersed in acrylic, acryl-melamine and urethane resin was applied to a substrate.

Comparative Example 5 The sample of Comparative Example 2 was placed in a stainless steel net-shaped container to make a storage.

Test Example 1 Peeling test After observing the fixation of the photocatalyst particles on the substrate surface in the photocatalyst from scanning electron microscope observation, the photocatalyst was placed in water, sonicated for 10 minutes, and the photocatalyst was separated from water. The water transmission was measured. A transmittance of 95% or more was rated as ○, and a transmittance of less than 95% was rated as x.

[0111] 2. NOx purification test The test method, test equipment, and test conditions are described below.

<Test Method> Two evaluation samples were placed in both petri dish type reaction vessels connected in series. 2. The NOx gas from the cylinder was mixed with air and flowed by bypass, and stabilized at a NOx concentration of 200 ppb and an air flow rate of 1 L / min. 3. 30 minutes after flowing the gas into the reaction vessel, irradiation was started at an ultraviolet intensity of 0.1 mW / cm ² . The NOx concentration (Vint) immediately before the irradiation with ultraviolet rays was measured. 4. NOx concentration 30 minutes after the start of UV irradiation (V30)
Was measured. The NOx purification rate was defined as follows. NOx purification rate (%) = {(Vint−V30) / Vint} × 1
00

<Testing Apparatus> NOx measuring apparatus: Instrument Service Co., Ltd. ML9841A Reactor: Vidro Chemical Petri dish-type photoreactor (inner diameter: 156 mm, depth: 32 mm) A glass lid is sandwiched between a Teflon ring and bolts It was fixed to the main body and gas was passed through a glass tube on the side. Raw gas: NO / N ₂ 0.1% gas cylinder Flow rate adjustment: Thermal mass flow controller manufactured by Kofloc Co., Ltd. Piping: Teflon pipe was used.

<Test conditions> NOx concentration: about 200 ppb Gas flow rate: 1 L / min. Evaluation sample: 40 g of a sample was put in a 10 cm × 10 cm × 1 cm paper frame. UV intensity: 0.1 mW / cm ² Measurement temperature: 20 ° C. Humidity: Air was dried with silica gel.
(About 60% at room temperature)

3. Mold Development Test Five rice grains cooked in a 200 ml glass beaker containing 100 ml of tap water and 10 g of a test sample were placed. It was left in a room at a temperature of 20 to 30 ° C. and a humidity of 40 to 60% for one week. A blank containing no test sample was left at the same time, and one week later, the presence or absence of mold generation from rice was confirmed.

4. Photocatalyst weather resistance test After exposing the photocatalyst to ultraviolet light for 500 hours using a Suga Test Machine Co., Ltd. due panel light control weather meter, the change in the color tone of the photocatalyst surface was examined, and the peeling described in 1. According to the test conditions, a peel test was performed to measure the transmittance. The case where no discoloration was visually observed and the transmittance in the peeling test was 95% or more was evaluated as ○, and the case where discoloration was observed or the transmittance in the peeling test was less than 95% was evaluated as x.

Table 1 shows the results.

[0118]

[Table 1]

From the results shown in Table 1, it was found that the samples of the examples were superior to those of the comparative examples in transmittance and NOx purification rate, had no mold, and had good weather resistance.

The strength of the sample of this example was so good that the sample was not destroyed by its own weight even when stepped on by an adult.

[0121]

The high-strength photocatalyst according to the present invention is characterized in that the photocatalyst particles are fixed on the surface of the agglomerate of glass particles with an inorganic substance as a binder on the surface thereof. It has excellent fixation to the substrate, is inexpensive, can be used for both gas and aqueous solution, has good separation and workability from these objects, and has sufficient strength to withstand practical use without lowering It will be.

Therefore, the high-strength photocatalyst of the present invention is excellent in practicality and workability, and can be suitably used particularly in an apparatus and method for preventing environmental pollution.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Ochiai 1978, Ogushi, Ube-shi, Yamaguchi 25-Titan Industry Co., Ltd. F-term (reference) 4C080 AA07 BB02 CC01 HH05 JJ09 KK08 LL03 MM02 NN01 NN03 NN06 QQ03 4D037 AA08 AB03 BA18 CA01 CA16

Claims (16)

[Claims] 1. A high-strength photocatalyst comprising: a glass particle agglomerate obtained by aggregating glass particles with a binder; and a photocatalyst particle fixed on the surface of the substrate using an inorganic substance as a binder. 2. The high-strength photocatalyst according to claim 1, wherein the glass particles are volcanic ejecta particles and / or foam particles. 3. The method of claim 1, wherein the average particle size of the glass particle aggregate is 1
The high-strength photocatalyst according to claim 1 or 2, wherein the thickness is from 50 to 50 mm. 4. The method according to claim 1, wherein the binder is at least one selected from the group consisting of alkali silicate, hydraulic cement, aluminum monophosphate and frit. Item 7. The high-strength photocatalyst according to item 1. 5. The method according to claim 1, wherein the photocatalyst particles are at least one selected from the group consisting of titanium oxide, zinc oxide, iron oxide, potassium titanate, strontium titanate, titanate fiber, molybdenum sulfide, and indium oxide. The high-intensity photocatalyst according to any one of claims 1 to 4, wherein 6. The at least one inorganic material selected from the group consisting of silica, alumina, clay, and frit.
6. The method according to claim 1, wherein the seed is a seed.
Item 7. The high-strength photocatalyst according to item 1. 7. The high-strength photocatalyst according to claim 6, wherein the raw material of the frit is a compound containing phosphorus. 8. A method in which a glass particle agglomerate is immersed in a coating material in which photocatalytic particles are dispersed in an aqueous silica sol and water, and the coating material is adhered to the surface thereof, and then heat-treated at 100 to 900 ° C. A method for producing a high-strength photocatalyst. 9. Clay, frit and photocatalytic particles, or
A method for producing a high-strength photocatalyst, comprising: applying a paste containing a frit and photocatalyst particles to a glass particle aggregate, followed by heat treatment at 450 to 1000 ° C. 10. The production of a high-strength photocatalyst according to claim 8, wherein the glass particle aggregate is a volcanic ejecta particle aggregate and / or a volcanic ejecta foam particle aggregate. Method. 11. A high-strength photocatalyst according to any one of claims 1 to 7, wherein the high-strength photocatalyst according to any one of claims 1 to 7 is placed in a bag-like or mesh-like storage container made of at least one of a fiber, a resin, a nonwoven fabric, a metal, and an alloy. High-strength photocatalyst storage items. 12. The high-strength photocatalyst storage article according to claim 11, wherein a floating body is placed in the storage container. 13. The high-strength photocatalyst container according to claim 12, wherein the floating body is at least one of styrene foam, hollow filler, wood, and plastic. 14. A high-intensity photocatalyst according to any one of claims 1 to 7 or a high-intensity photocatalyst housing according to any one of claims 11 to 13, wherein a harmful gas is passed. And a method of decomposing and removing harmful gases, which comprises irradiating the container or the storage object with light containing ultraviolet rays. 15. The high-intensity photocatalyst according to any one of claims 1 to 7, or the photocatalyst according to any one of claims 11 to 13, wherein the specific gravity is adjusted so as to float and / or settle in water. A method for purifying water, comprising passing water through a high-strength photocatalyst container and irradiating it with light containing ultraviolet rays. 16. The high-intensity photocatalyst according to any one of claims 1 to 7, wherein the specific gravity is adjusted so as to float and / or settle in water, or according to any one of claims 11 to 13. A method for disinfecting a hydroponic culture solution, comprising irradiating the culture solution through a high-strength photocatalyst storage object and irradiating light containing ultraviolet light.