JP2000117102A - Charcoal and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing charcoal provided with innovative functions by adding functions of decomposing organic substances by a photocatalyst to charcoal having an adsorptive function and further promoting the optimization of crystal structure of the photocatalyst of the charcoal by thermal denaturation. SOLUTION: The method for producing this photocatalytic charcoal comprises processes of setting anatase-type titanium oxide on the surface of a hydrocarbon material in the state that the titanium oxide is deposited on the surface, heating the resultant hydrocarbon material in a temperature range of 500-1,200 deg.C for about 10-90 minutes to promote carbonization of the hydrocarbon material, and then stopping the heating treatment in the middle of conversion process of the crystal structure of the deposited titanium oxide from the anatase type to the rutile type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the development of a new purifying agent, a deodorant, a moisture absorbent, a soil conditioner, etc. by combining charcoal and a photocatalyst, and to provide a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a method of utilizing charcoal, (a) drinking water for purifying drinking water and wastewater, which has a strong adsorption capacity with a fine pore structure and promotes adsorption, decolorization, reduction of COD, and denitrification. As a treatment agent, (b) as a deodorant that adsorbs odor components with a fine pore structure, and as a humidity conditioner that absorbs the same moisture and moisture,
(C) It has been known to be used as a soil conditioner or the like that enhances water retention and air permeability of soil, breeds useful microorganisms, and promotes an increase in soil temperature.

However, these methods only utilize the adsorption characteristics of porous charcoal, and the performance is limited by the charcoal adsorption capacity. For example, when the charcoal adsorption capacity becomes full, the purification is performed. There are drawbacks such as that the performances such as odor and deodorization are extremely reduced.

[0004]

An object of the present invention is to develop a charcoal having a new function by adding the above-mentioned conventional charcoal having an adsorptive capacity to the resolution of organic substances by a photocatalyst and the like. In addition, the present invention aims at producing the carbonization by a method which can simultaneously promote the carbonization treatment and the optimization of the crystal structure of the photocatalyst.

[0005]

The present invention first refers to an object that can be carbonized by hot dry distillation or the like as a carbonized material, and refers to, for example, general charcoal obtained by carbonizing wood such as oak, pine, and oak. This includes, of course, demolition wood discarded from buildings and thinned wood resulting from deforestation. Further, carbonized materials such as discarded paper materials and fir shells may be carbonized by carbonization, which means that materials that can be carbonized are widely included.

Next, a photocatalyst is used. For example, titanium oxide is used as the photocatalyst. When the titanium oxide is supplied with energy equal to or more than the band gap, electrons are excited from the valence band to the conduction band. Electrons are generated in the conduction band and holes are generated in the valence band to be excited, and the excitation promotes the resolution of the organic substance, and brings about actions such as purification and deodorization. The titanium oxide has an anatase type and a rutile type due to a difference in crystal structure. Anatase type titanium oxide is used as a starting material used at this time. This is for promoting the structural conversion from the anatase type to the rutile type for the reason described later, and for obtaining the catalyst in the state of the conversion from the anatase type to the rutile type in the crystal structure.

Then, a photocatalyst is placed on the surface of the carbonized material. Here, the attached state means that the carbonized material and the photocatalyst are physically as close as possible to each other.For example, a powder of titanium oxide is dispersed in a viscous solution, and the dispersion is sprayed with a sprayer. A state in which the dispersion is applied by spraying or the like. At this time, by adjusting the concentration of the photocatalyst with respect to the dispersion, the amount of the photocatalyst attached can be controlled, and the composition ratio between the charcoal and the photocatalyst can be optimized.

Next, the carbonized material and the photocatalyst placed on the surface of the carbonized material are subjected to a heat treatment based on the following two purposes. One of the purposes is to carbonize the carbonized material to form a so-called charcoal. For that purpose, it is heated under oxygen-free condition to evaporate volatile components and leave carbon content. Generally, it is about 400 to 1300 ° C. The second purpose is to promote the change of the crystal structure of titanium oxide, and therefore, the crystal structure can be changed from anatase-type titanium oxide to rutile-type titanium oxide.
The range is 0 ° C. Therefore, the temperature condition in the present invention is set to 500 ° C. to 1200 ° C., where the conditions of the first object and the second object described later overlap.

In detail, as described above, titanium oxide as a photocatalyst includes an anatase type and a rutile type. In the anatase type, as shown in FIG. 1, oxygen is distributed around central titanium. It has a vertically long rectangular crystal structure,
The band cap is 3.23 eV. On the other hand, as shown in FIG. 2, the rutile type has a short structure with oxygen coordinated to the central titanium, and has a band cap of 3.02 eV.
It is. Therefore, although there is a difference in the respective catalytic activities, in the present invention, for the reasons described below, the anatase type titanium oxide causes a structural change to the rutile type titanium oxide, and the crystal structure changes from the anatase type to the rutile type. Heating is stopped in the middle of the conversion. Therefore, the above temperature range is set to 500 ° C. to 1200 ° C., and at the same time,
The heating time is set to about 10 to 90 minutes at which the conversion from the anatase type to the rutile type is stopped halfway.

[0010] Thus, when placed under the above-mentioned heating conditions, first, the carbonized material is placed in a dry-distilled state, the volatile components inside the material are evaporated, and the wood vinegar and the like are fractionated. Charcoal with many holes is formed. At the same time, the titanium oxide deposited on the surface causes a change in the crystal structure from the anatase type to the rutile type, and heating is stopped during the change, and the conversion from the anatase type to the rutile type is performed. The photocatalyst in the state described above is formed, and the form in which the photocatalyst faces as close as possible to the porous charcoal is obtained.
That is, a new charcoal having a form in which a photocatalyst is bonded to a part of the charcoal is obtained, and a crystal form of the photocatalyst is in a state of being converted from an anatase type to a rutile type. Whether the charcoal is used as it is or crushed into granules or powder is optional, and is selected according to the purpose.

Next, the function of the charcoal obtained by the method of the present invention will be described. The coal of the present invention is, as described above, a purifying agent,
It is used as a deodorant, a hygroscopic agent, a soil conditioner, etc. First, for example, when it acts as a purifying agent, the charcoal obtained by the above-mentioned manufacturing method is granulated and placed near the toxic component. Then, the organic toxic components existing in the air or water are captured in the pores of the charcoal. At this time, the charcoal exerts a stronger cohesive force on the carbon to attract the toxic component, and the fine cavities are formed therein, so that the toxic component can be reliably captured in the pores.

Next, a photocatalyst adjacent to the charcoal acts on the toxic component caught in the pore, and the excitation decomposes the toxic component. The reaction may for example take the case toxic components chloroform which is one of trihalomethanes is an environmental pollutant ^{_{example, TiO 2 + hν → e -}} + hν O 2 + e - → O 2 - OH - + h ⁺ → OH CHCl ₃ + ・ OH → ・ CCl ₃ + H ₂ O ・ CCl ₃ + ・ OH → COCl ₂ + HCl COCl ₂ + H ₂ O → CO ₂ + 2HCl And is decomposed into carbon dioxide.

At this time, as described above, the activity of the photocatalyst is most likely to be in the state during the conversion of the titanium oxide from the anatase type to the rutile type, rather than the anatase type alone or the rutile type alone. good. It is because the anatase-type and rutile-type titanium oxides exhibit their respective activities, and in the process of changing the crystal structure from the anatase-type to the rutile-type by heating, the connection of the elements that form the initial lattice. In the process of collapse and generation of a new crystal lattice, lattice disorder occurs, and many defects as lattices are generated. Then, the generated lattice defect becomes an active point as a catalyst and, when acting as a photocatalyst, is considered to effectively act on decomposition of organic substances and the like.

That is, the toxic component adsorbed by the activated carbon comes to the nearest physically position and is decomposed extremely efficiently by the photocatalyst in a highly active state.

Although the above description has been made by taking one kind of purifying agent as an example, charcoal adsorbs other halogenated organic substances such as trichloroethylene and dioxin, pesticides, etc., and a photocatalyst acts on the trapped organic substances to cause carbon dioxide, water, etc. Can be decomposed into harmless substances. Similarly, a deodorant decomposes malodorous components, and a soil conditioner adsorbs and decomposes nitrate nitrogen present in soil. The dehumidifying agent mainly adsorbs water, but can adsorb and decompose harmful substances such as ammonia and formaldehyde emitted from new building materials. That is, the coal of the present invention has adsorption and decomposition performance, and can be widely applied to other fields requiring adsorption and decomposition performance in addition to the above-mentioned deodorants and purifying agents.

[0016]

[Example] Construction waste and thinned wood were crushed into chips of about 50 mm under. On the other hand, 200 g of anatase-type titanium oxide (TiO ₂ ) was prepared and mixed with 1 liter of a 15% solution of polyvinyl alcohol (PVA). The mixed solution was sprayed on the chip-shaped building waste and thinned wood using a spray gun. This was put into a carbonization furnace and heat-treated at 800 ° C. for about 20 minutes. As a result, charcoal was obtained in which titanium oxide was bonded to the surface of carbonized chip-shaped charcoal.

[0017]

According to the present invention based on the above configuration and operation,
By combining charcoal with excellent adsorption characteristics and photocatalyst with excellent resolution of organic substances, it can be decomposed into harmless substances while reliably capturing the target substance, and deodorants, purifiers, soil conditioners, dehumidifiers, etc. Demonstrate a revolutionary effect that has never been seen before. or,
Even in the production method, it is possible to simultaneously perform the thermal modification of the photocatalyst at the same time as the carbonization of the carbonized material, and to obtain a rational production method capable of obtaining the most active structure as a catalyst. It is.

[Brief description of the drawings]

FIG. 1 is a crystal structure diagram of anatase type titanium oxide.

FIG. 2 is a crystal structure diagram of rutile-type titanium oxide.

Claims (3)

[Claims] 1. An anatase type titanium oxide is placed on a surface of a carbonized material in an adhered state, and then heat-treated to promote carbonization of the carbonized material. At the same time, the attached titanium oxide is changed into a rutile type titanium oxide in a crystal structure. And the heat treatment is stopped during the conversion from the anatase type to the rutile type. 2. The conditions of the heat treatment are as follows:
The method for producing charcoal according to claim 1, wherein the temperature is 1200 ° C. and the heating time is 10 to 90 minutes. 3. A charcoal comprising a part of charcoal and titanium oxide having a crystal structure in a state in which the structure is changed from an anatase type to a rutile type.