JPH0975747A - Method for caking photocatalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cake a photocatalyst such as titanium oxide or silver oxide at ordinary temp. SOLUTION: At least one of silica and alumina or ash contg. at least one of silica and alumina produced by incineration, a caking agent contg. a quick lime-cement mixture, an additive based on a hydration regulating agent contg. a lime supersaturating material and water are added to a photocatalyst and they are mixed and hardened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for solidifying a photocatalyst such as titanium oxide or silver oxide.
The present invention relates to a method for consolidating a photocatalyst using incineration ash of activated sludge, incineration ash of municipal waste, incineration ash of industrial waste, and the like.

[0002]

_2. Description of the Related Art Titanium oxide (TiO ₂ ) and silver oxide (Ag
When a photocatalyst composed of O, Ag ₂ O) or the like is irradiated with light, it has a strong oxidizing power, and has the effects of sterilization, foul odor decomposition, ozone decomposition, etc. Therefore, it has recently been applied to building materials such as tiles and bricks. Clean air, treat ozone in wastewater,
It is proposed to use it for sterilization in hospitals. By the way, since the above-mentioned titanium oxide and silver oxide are usually powders, silica (SiO ₂ ) and alumina (Al
₂ O ₃ ) and the like are added, and sintering and solidification are performed at high temperature.

[0003]

However, when titanium oxide is sintered at a high temperature, its crystal structure changes from anatase type to rutile type between about 600 ° C. and 700 ° C., and as a result, the catalytic activity decreases. Such a problem occurs. Also,
A large amount of fuel is required to sinter at a high temperature, resulting in high cost.

The present invention has been made in view of the above problems, and an object of the present invention is to realize a method for consolidating a photocatalyst capable of rapidly producing a condensate product of the photocatalyst at room temperature. is there.

Further, waste incineration ash such as activated sludge incineration ash, municipal solid waste incineration ash, industrial waste incineration ash, etc. is used,
It is an object of the present invention to realize a photocatalyst consolidation method capable of producing a photocatalyst consolidation product at room temperature without sintering at high temperature.

[0006]

The present invention relates to silica (Si
O ₂ ) or alumina (Al ₂ O ₃ ) is reacted with quick lime to obtain a stable hardened product of a calcium compound (calcium silicate, calcium aluminate), that is, so-called pozzolanic reaction is used to consolidate the photocatalyst. To do.

Further, silica (S which is indispensable for the pozzolanic reaction
Focusing on the fact that iO ₂ ) and alumina (Al ₂ O ₃ ) are often contained in incinerated ash of activated sludge, incinerated ash of municipal waste, incinerated ash of industrial waste, etc., the pozzolanic reaction is used. The incinerated ash is to be recycled as a solidified product of the photocatalyst.

By the way, in the pozzolanic reaction, the solubility of quicklime in water is extremely small at 0.131 (10 ° C.), and its reaction efficiency is low. Therefore, when starting the reaction, a lime supersaturating agent for increasing the solubility of quicklime in water is added. It is necessary to.

That is, the method for consolidating a photocatalyst of the present invention is
To the photocatalyst, at least one of silica and alumina, a solidifying agent containing quicklime and a cement mixture, an additive containing a hydration regulator containing a lime supersaturated material as a main component, and water are added and mixed. , To cure.

Further, addition to the photocatalyst of which main components are incinerated ash containing at least one of silica and alumina, a solidifying agent containing quick lime and a cement mixture, and a hydration modifier containing a lime supersaturated material. Add the agent and water and mix,
By curing, the incineration ash of the waste is used as a solidification product of the photocatalyst.

Examples of the photocatalyst of the present invention include titanium oxide (TiO ₂ ), silver oxide (AgO, Ag ₂ O), zinc oxide (ZnO), and tungsten oxide (WO ₃ ).

Silica and alumina added to the photocatalyst and quicklime in the solidifying agent start solidification by a pozzolon reaction. Then, the reaction efficiency is increased by the lime supersaturating agent, and the solidification reaction rapidly progresses, but the rapid progress of condensation by the lime supersaturating agent is controlled by the presence of the photocatalyst, and the photocatalyst powder, silica, and alumina. Alternatively, after the incinerated ash containing silica or alumina and the quick lime are sufficiently mixed, the condensation reaction proceeds, and the solidified product of the photocatalyst is obtained at room temperature.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The method for consolidating a photocatalyst according to the present invention will be specifically described below by taking as an example a case where a photocatalyst consolidating product is produced from waste incineration ash. Examples of the photocatalyst to be consolidated include usually titanium oxide (TiO ₂ ) and silver oxide (AgO, Ag ₂ O) which are powders, but the photocatalyst is not limited to this, and other photocatalysts such as zinc oxide (ZnO) and oxides. It is also applicable to tungsten (WO ₃ ).

The types of incineration ash added to the above photocatalyst are
Although it is not particularly limited, since the photocatalyst is solidified by utilizing the pozzolanic reaction, silica (calcium silicate, calcium aluminate) is used to obtain a cured product of calcium compound (calcium silicate, calcium aluminate) by reacting with quicklime. Si
It is necessary to contain at least one of O ₂ ) and alumina (Al ₂ O ₃ ). That is, silica (SiO
₂ ) and alumina (Al ₂ O ₃ ) containing at least one kind, activated sludge incineration ash, municipal waste incineration ash, EP
All kinds of incineration ash such as ash (incineration ash of dust collected by an electric dust collector), industrial waste incineration ash can be used.

Since the incinerated ash may contain a substance that promotes or delays the solidification reaction or changes after the completion of the solidification reaction, before the present invention is carried out. It is desirable to analyze the components of the incineration ash used in advance in order to remove substances that cause harmful effects and to perform stabilization operations as pretreatment. For example, iron expands due to the oxidation reaction after solidification and may cause cracks in the solidified product, so iron is removed in advance, and metallic aluminum foams and deteriorates the strength of the solidified product. Therefore, it is treated with slaked lime and stabilized as calcium aluminate.

Next, the solidifying agent of the present invention is quicklime 95-5.
It is a mixture of 0% and 5 to 50% cement.
The cement is a single substance such as Portland cement, blast furnace slag, alumina cement, burnt alum, silicate, etc., or a mixture of two or more thereof. In the present invention, the product obtained by reacting the silica or alumina in the incinerated ash with the solidifying agent is calcium silicate and calcium aluminate, so that the same product as the above Portland cement hydrate is produced. However, the calcium silicate and calcium aluminate formed in the initial stage of the reaction are amorphous gels and lack strength. Therefore, in order to easily generate crystalline calcium silicate hydrate or calcium aluminate from a gel-like substance, the above cements are added to form the nucleus of the crystal, which increases the strength of the cured product and also improves the water resistance. is there.

The lime supersaturating agent of the present invention acts at the time of hydration of quick lime to form ultrafine particles of active slaked lime (colloidal form) and at the same time enhances the solubility of quick lime in water to cause a supersaturated state of lime. It is an additive. Examples of the lime supersaturating agent include sodium hydroxycitrate citrate, potassium tartarate, ketocarboxylate sodium diketoglutarate, sodium gluconate, dicarboxylate disodium EDTA, sodium succinate, sodium lactate, and natural products. Sodium humate, sugar, lignin sulfonate and the like are preferable. Further, polyhydric alcohols such as glycerin, propylene glycol, ethylene glycol, pentaerythritol alone or a polymer thereof or a copolymer thereof,
It may be a polyacrylic acid salt of a polycarboxylic acid salt, an isobutylene maleic anhydride copolymer salt, or the like. These lime supersaturants are used as a powder or an aqueous solution, and may be used alone or in combination of two or more thereof.

When the lime supersaturating agent is used, the lime supersaturating agent first reacts with quick lime in an aqueous solution to form a complex salt, and then the complex salt reacts with incineration ash. Further, after the reaction, the lime supersaturating agent is released and again reacts with quick lime, and this reaction continues repeatedly. Therefore, this lime supersaturating agent exerts a sufficient effect even in a small amount.
The lime supersaturating agent is a quick lime hydration retarder,
It can also be used together with alkalis such as caustic soda, caustic potash, lithium hydroxide, magnesium silicofluoride and sodium sesquisilicate.

In the aqueous solution containing the lime supersaturating agent, quick lime hydrates very slowly, so that the lime supersaturating agent is absorbed by the incineration ash and a solid-liquid reaction occurs. As a result, the reaction between the incineration ash and the quick lime becomes drastically efficient, and before the incineration ash and the quick lime are sufficiently mixed, a quick-setting phenomenon occurs in which the condensation reaction proceeds, but when the photocatalyst is present, The quick setting phenomenon is prevented, and the setting reaction proceeds after the photocatalyst powder, incineration ash and quick lime are thoroughly mixed.

As described above, the photocatalyst prevents the rapid setting phenomenon, but a curing retarder may be added to control the curing time. As the curing retarder, for example,
Gypsum, mirabilite, potassium sulfate, aluminum sulfate, magnesium sulfate, or an acidic salt thereof is preferable, and alkyl sulfates such as ethyl sulfate, organic salts such as naphthalene sulfonate, lignin sulfonate, and sulfate of organic amine are also preferable. Is. When such a sulfate is used in combination with a lime supersaturating agent, it is possible to delay the hydration rate of quicklime and the solidification reaction rate of photocatalyst and incineration ash, and by adjusting the addition amount of the hardening retarder, Since the curing time can be freely set to about 5 to 360 minutes, it can be applied to any molding method or molding machine having a different curing time.

Further, by adjusting the curing time using a curing retarder, the solidifying agent which is a mixture of quick lime and cement, the photocatalyst and the incineration ash can be homogeneously mixed to obtain a uniform slurry. it can.

The above-mentioned photocatalyst, caking agent, lime supersaturating agent, and water are blended in amounts of 1 part by weight to 10 parts by weight, preferably 3 parts by weight to 7 parts by weight of the photocatalyst per 100 parts by weight of incinerated ash. 10 to 70 parts by weight, preferably 20 to 6 parts by weight
0 part by weight, lime supersaturating agent 0.01 part by weight to 5 parts by weight, preferably 0.2 part by weight to 1.0 part by weight, water 30 parts by weight to
80 parts by weight, preferably 40 to 60 parts by weight. Further, the component ratio of each of silica and alumina contained in the incinerated ash is 50% or more, preferably 60% or more. Is 50% or more, preferably 60% or more. When a curing retarder is added, it is added to 100 parts by weight of incinerated ash.
01 to 10 parts by weight, preferably 0.2 to 2 parts by weight
It is preferably 0 parts by weight.

In carrying out the present invention, in addition to the above-mentioned main components such as the photocatalyst, the solidifying agent and the lime supersaturating agent, a water reducing agent, a fluidizing agent, which is optionally used as a cement admixture, A foaming agent, a setting accelerator, a setting retarder, a swelling agent, a polymer emulsion, an aggregate and the like may be added.

The following is an example of blending in the case of obtaining a solidified product of a photocatalyst by using activated sludge incineration ash.

The above activated sludge incineration ash contains Fe _{2 in} addition to the above silica (SiO ₂ ) and alumina (Al ₂ O ₃ ).
O ₃ (9.11%), MnO (0.18%), TiO
₂ (1.07%), CaO (9.32%), MgO
(2.86%), K ₂ O (0.27%), P ₂ O ₅ (1
5.6%).

The above formulation example is a formulation for producing a brick-like cured product from activated sludge incineration ash, which has a fluidity such that it can be poured into a mold to be molded, and after being poured into the mold, about It cures in 1 hour.

The solidified product of the photocatalyst obtained in the above formulation example has a specific gravity of about 1.4 and a water absorption amount per unit weight of 36.
%. The specific gravity and the amount of water absorption vary depending on the amount of blended water, and the addition of a foaming agent reduces the weight.

Incidentally, when various metal oxides other than silica and alumina are contained as in the above activated sludge incineration ash, the solidification reaction is further promoted.

Further, since Fe ₂ O ₃ , MnO and CuO enhance the catalytic effect, it is desirable to produce the solidified product of the photocatalyst by using the incinerated ash containing these components.

Furthermore, Fe ₂ O ₃ , CuO and P are contained in the incinerated ash.
When bO or the like is contained, the silver nitrate can be added to the Fe ₂ O ₃ or CuO or PbO by adding inexpensive silver nitrate (AgNO ₃ ) without using silver oxide powder.
Reacts with silver oxide (AgO, Ag ₂ O), which is a photocatalyst, to form a solidified product of the photocatalyst at low cost.

When the solidified product of the photocatalyst is produced by using the incinerated ash as described above, since the incinerated ash often contains heavy metals, harmful substances and malodorous substances, It is desirable to add an absorbent that seals them. Examples of the absorbent include heavy metal-trapping zeolite, natural ion-exchange substances such as Otaniishi powder, activated carbon that adsorbs heavy metals and malodorous substances, sodium phosphate, EDTA2Na, and powder ion-exchange resins. In addition, when the incineration ash containing a large amount of heavy metals is used to the extent that the above-mentioned adsorbent is insufficient, it is 3 to 4
No. 1 mol of silicic acid / 2 mol or more of alumina cement or 1 mol or more of aluminum salt is used to wrap the incineration ash and treat it, and then to add a solidifying agent and a wettable powder to produce a solidified product. Good.

As described above, in the present embodiment, the main components are the incineration ash containing silica and alumina as the photocatalyst, the solidifying agent containing the quick lime and the cement mixture, and the hydration regulator containing the lime supersaturated material. Additives and water are added and mixed, and the photocatalyst is solidified at room temperature by using the pozzolan reaction, so the solidification of the photocatalyst can be produced at a lower cost than the conventional case of sintering and solidification at high temperature. You can get things. Also,
When the photocatalyst is titanium oxide, an anatase-type solidified product having high catalytic activity can be obtained. Furthermore, the incineration ash that is a waste can be effectively recycled as a solidified product of the photocatalyst.

Since the photocatalyst is solidified at room temperature,
As shown in FIG. 1, it is possible to solidify the photocatalyst solidified product 1 with the light source 2 inside, and to enhance the photocatalytic action of the solidified product 1. In this case,
The solidified product 1 is foamed so that the light from the light source 2 is transmitted, or a mold having a shape capable of forming a hole in the solidified product 1 is prepared and solidified.

The solidified product of the photocatalyst using the incinerated ash is produced as, for example, pseudo stone, artificial wood, block, sculpture, etc., and is installed indoors or outdoors such as in a park,
It can be used for decomposing harmful substances such as nitrogen oxides (NO _x ), sulfur oxides (SO _x ), ozone (O ₃ ), decomposing odorous substances, and sterilizing. In addition, a solidified product of photocatalyst that uses incinerated ash is manufactured as a revetment block and placed on the bottom of rivers or swamps to be used for the decomposition of harmful organic substances and pollutants such as trichlorne and triethane in water. be able to.

[0035]

According to the method for consolidating a photocatalyst of the present invention, the photocatalyst contains at least one of silica and alumina, a consolidating agent containing a mixture of quick lime and cement, and a hydration adjusting agent containing a lime supersaturated material. Since the additive containing the agent as a main component and water are added and mixed and cured, the photocatalyst can be solidified at room temperature by utilizing the pozzolan reaction without sintering.

In addition, an incineration ash containing at least one of silica and alumina, a solidifying agent containing quick lime and a cement mixture, and a hydration modifier containing a lime supersaturant as main components are added to the photocatalyst. Add the agent and water and mix,
Since it cures, incineration ash of waste can be effectively recycled as a solidified product of the photocatalyst.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a solidified product of a photocatalyst having a light source inside.

[Explanation of symbols]

 1 Solidified product of photocatalyst 2 Light source

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B01J 37/00 B01J 37/00 J

Claims (3)

[Claims] 1. A photocatalyst containing at least one of silica and alumina, a solidifying agent containing quicklime and a cement mixture, an additive containing a hydration regulator containing a lime supersaturating agent as a main component, and water. A method of consolidating a photocatalyst, which comprises adding, mixing and curing. 2. A photocatalyst containing incineration ash containing at least one of silica and alumina, a solidifying agent containing quicklime and a cement mixture, and a hydration modifier containing a lime supersaturant as main components. A method for consolidating a photocatalyst, which comprises adding an agent and water, mixing and curing. 3. The method for consolidating a photocatalyst according to claim 1, wherein the photocatalyst is any one of titanium oxide, silver oxide, zinc oxide and tungsten oxide.