JPH10272368A - Activated carbon production method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To have excellent antibacterial activity regardless of irradiation or non-irradiation of ultraviolet light or sunlight, and to detect harmful substances in water or gas phase under irradiation of ultraviolet light or sunlight. The present invention provides an activated carbon capable of greatly improving the removal ability and providing a great industrial advantage. SOLUTION: In the method for producing activated carbon, silver and / or a silver compound and titanium and / or a titanium compound are added at least in a step before activation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a titanium dioxide-silver composite activated carbon. The titanium dioxide-silver composite activated carbon produced according to the present invention has both the photocatalytic ability of titanium dioxide and the antibacterial function of silver, and has the ability to remove harmful substances in water or the gas phase under irradiation of ultraviolet rays or sunlight and has a long life. It is greatly improved, and has antibacterial activity even when ultraviolet light or sunlight is not irradiated or in a non-irradiated part. Furthermore, titanium dioxide and silver having a small particle size are extremely excellent in terms of immobilization on activated carbon particles, and titanium dioxide and silver are present in a form in which titanium dioxide and silver are extremely hard to peel off on the surface without filling pores of the activated carbon. It is. Such activated carbon is suitably used for applications requiring antibacterial properties such as water purification, sewage treatment, waste liquid treatment, waste gas treatment, odor removal, and water purifiers, 24-hour baths, and nutrient solution cultivation.

[0002]

2. Description of the Related Art In recent years, water pollution, marine pollution, air pollution and the like caused by domestic wastewater and industrial wastewater have spread on a global scale. Eutrophication of lakes and rivers by domestic wastewater containing synthetic detergents, pollution of groundwater and water sources by organic solvents used in high-tech industries and laundry shops, and water pollution due to spillage of pesticides used in golf courses, etc. Is a typical example. Under such an environment, activated carbon having a high specific surface area having excellent adsorption capacity is used for adsorption and removal of harmful substances in water or in the gas phase. However, conventional activated carbon is not sufficient in all of the various required characteristics, and there is a demand for further enhanced activated carbon.

[0003]

Therefore, the present inventors have developed an activated carbon in which titanium dioxide having a photocatalytic property is appropriately present on the surface in order to impart the ability to decompose and remove by activated carbon to the ability to adsorb and remove activated carbon. Activated carbon (Japanese Patent Application No. 7-037758), characterized in that titanium dioxide is present on the surface and the lightness L value is 50 or less,
A method for producing a coal-based activated carbon by granulating, crushing, carbonizing and activating, wherein titanium dioxide is added to coal before granulation, and a method for producing the same (Japanese Patent Application Hei 7-187954), in a method of pulverizing raw coal, kneading with a binder, granulating, hardening carbonizing, and activating to produce granulated activated carbon, titanium dioxide is added to raw coal before granulation. Activated carbon characterized by adding titanium and a titanium compound (excluding titanium dioxide) at a stage prior to activation. (Japanese Patent Application No. 8-216062) has been proposed.

[0004] When light is applied to titanium dioxide, holes having strong oxidizing power and electrons having strong reducing power are generated, and oxygen and water in the air are respectively converted by superoxide ions (O ₂ ^- ), Hydroxyl radical (・
OH). This active oxygen has a much stronger oxidizing power than chlorine and ozone, which are widely used for disinfection and the like. Various organic and inorganic substances are decomposed by the action of the active oxygen. When bacteria come in contact, they can damage cell membranes and kill them in a short time. Therefore, the photocatalytic titanium dioxide is
Not only is it possible to decompose and remove harmful substances in water and in the gas phase, but it also has antibacterial properties, so it has begun to be used in fields requiring antibacterial properties. However, in the case of titanium dioxide, it is necessary to irradiate ultraviolet rays or sunlight in order to maintain the antibacterial activity.Therefore, when activated carbon having titanium dioxide on its surface is loaded into an adsorption tower or the like, light must be applied efficiently. It was necessary to devise the shape of the activated carbon filling tank such as an adsorption tower. In addition, there were portions in the activated carbon packed layer where light did not shine, and the antibacterial properties were not sufficient.

[0005] Under these circumstances, there is a demand for activated carbon having titanium dioxide having antibacterial activity on the surface even when ultraviolet light or sunlight is not irradiated or in a non-irradiated part.
Activated carbon is proposed in which titanium dioxide is present on the surface and contains silver or silver compounds. However, there are various techniques for immobilizing titanium dioxide and silver, but there is a problem of releasability, and titanium dioxide and silver are hardly separated from the activated carbon surface into treated water or treated gas. Silver composite activated carbon was required.

Accordingly, the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found a method of producing crushed coal-based activated carbon by pulverizing, granulating, crushing, carbonizing and activating coal. Various types of activated carbon, such as a method of pulverizing raw carbon, kneading with a binder, granulating, hardening and carbonizing, and activating to produce granulated activated carbon, a method of producing powdered activated carbon, and a method of producing fibrous activated carbon In the manufacturing method, at a specific time of the manufacturing process,
By adding silver and / or a silver compound and titanium and / or a titanium compound, in the activated carbon obtained, silver having excellent antibacterial activity and titanium dioxide having photocatalytic activity are firmly fixed to activated carbon particles. It has been found that silver and titanium dioxide are present in a state in which they are hardly peeled off, and the present invention has been reached.

[0007]

That is, the present invention is characterized in that in a method for producing activated carbon, silver and / or a silver compound and titanium and / or a titanium compound are added in a step before activation. It is in the production method of activated carbon

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The greatest feature of the present invention is that, in the production of activated carbon, silver and / or a silver compound and titanium and / or a titanium compound are added in a step before activation.
This can be applied to various activated carbon production methods. According to the feature of the present invention, when silver and / or a silver compound and titanium dioxide are immobilized on activated carbon, these components do not fill the pores of the activated carbon and can freely control the pore distribution of the activated carbon. it can. Using coal as a raw material, pulverizing, granulating, crushing, carbonizing, and activating the coal to produce a crushed coal-based activated carbon, the coal before granulation, silver and / or silver compound, It is preferable to adopt a mode of adding titanium and / or a titanium compound. In the method of pulverizing raw coal, kneading it with a binder, granulating, hardening and carbonizing, and activating the raw carbon, silver and / or silver is added to the raw coal before granulation. It is desirable to adopt an embodiment in which a compound and titanium and / or a titanium compound are added. Also in the method for producing powdered activated carbon, silver and / or
Alternatively, a silver compound and titanium and / or a titanium compound are added. Also in the method for producing fibrous activated carbon, silver and / or a silver compound and titanium and / or a titanium compound are added in a step before activation. By adopting such a method, silver and titanium dioxide can be firmly fixed in the activated carbon particles, and silver having excellent antibacterial activity and titanium dioxide having a very small particle size having photocatalytic activity are formed on the surface of the activated carbon particles. May exist.

In the present invention, when producing crushed coal-based activated carbon, the coal to be used is not particularly limited, but generally, granulation is a condition for selection. Examples of coal that can be used include bituminous coal, lignite, anthracite, lignite, peat, peat, and the like. Tar and pitch may be mixed as needed to improve granulation properties. Of these, bituminous coal having caking properties is particularly preferred. In the case of producing granulated activated carbon in the present invention, the raw coal used is not particularly limited, and includes, for example, coconut shell charcoal, coke, charcoal, coal and the like, and there is basically no restriction on the raw material.
The degree of pulverization of coking coal is 100 μm
It is preferably at most 75 μm. If necessary, a binder such as coal tar, pitch, molasses, sap and starch and a titanium compound are added to the finely pulverized coal obtained as required, and the mixture is heated and kneaded. Granulate with a granulator.

In the present invention, when producing fibrous activated carbon, the fiber raw material used is not particularly limited.
For example, there are cellulose-based, acrylonitrile-based, phenol-based, pitch-based, and vinylidene chloride. Among the titanium and / or titanium compound used in the present invention, titanium dioxide is particularly preferred from the viewpoint of cost. Titanium dioxide may be rutile or anatase, regardless of its crystal form. As for the particle size, a smaller one is preferably 5 nm to 10 μm, and more preferably 5 nm to 1 μm. As the titanium and / or titanium compound used in the present invention, those in the form of a solution are particularly preferable from the viewpoint of reducing the particle size of titanium dioxide after the activation step. Specifically, TiCl ₄ , Ti ( SO ₄ ) ₂ , TiOSO ₄ ,
Aqueous solution such as (NH ₄ ) ₂ TiO (C ₂ O ₄ ) ₂ .2H ₂ O, or a precipitate of titanic acid formed therefrom, titanium tetraisopropoxide, titanium tetrabutoxide, titanium 2 ethyl / 1 hexanolate A solution obtained by dissolving the above organic metal salt in an organic solvent such as alcohol is preferred.
It is preferable to add them in the form of a solution in the step before activation.

The form of silver and / or silver compound used in the present invention is preferably powdery, and the particle size is preferably 10 μm or less, more preferably 1 μm or less. The silver and / or silver compound used in the present invention is not particularly limited. For example, CH ₃ C
Silver carboxylate such as OOAg, C ₆ H ₅ COOAg, Ag ₃
C ₆ H ₅ O ₇ , Ag ₂ CO ₃ , AgBF ₄ , AgNO ₃ , Ag
Cl, AgBr, AgF, AgI, AgClO ₂ , Ag
ClO ₃ , AgClO ₄ , AgBrO ₂ , AgBrO ₃ , A
gBrO ₄ , AgIO ₂ , AgIO ₃ , AgIO ₄ , AgB
O ₂ , AgCN, AgOCN, Ag ₃ PO ₄ , Ag ₄ P
₂ O ₇ , AgSO ₃ NH ₂ , Ag ₂ SO ₄ , Ag ₂ SO ₃ , zeolite ion-exchanged with silver ions, ion-exchange resin and the like are preferably used.

The silver and / or silver compound may be dissolved in water or an organic solvent such as alcohol and added in the form of a solution. The mixing of titanium and / or a titanium compound into the raw coal is not particularly limited as long as it is before the activation step, but is particularly preferably performed before the carbonization step. For example, when producing crushed coal-based activated carbon, titanium and / or a titanium compound may be mixed before the pulverization of the coal, or may be mixed after the pulverization. Mixing is preferred. Although the final desirable ratio of activated carbon and titanium or silver varies depending on the degree of activation, it is difficult to specify them. However, the contents of titanium dioxide and silver are 0.1 to 30 wt% and 0.001 to 20 w, respectively.
t%, preferably 0.1 to 20 wt%, 0.01 to 0.1 wt%.
5 wt% is preferred.

The mixing amount of titanium and / or a titanium compound or silver and / or a silver compound in the raw coal is not particularly limited, but is preferably such that granulation properties and spinning are not impaired. And / or a total amount of titanium compound and silver and / or silver compound of 40% by weight or less, more preferably 30% by weight or less. Titanium and / or
Most preferably, the ratio of the titanium compound to silver and / or the silver compound is about 10 to 100 times that of titania and silver in terms of titania and silver. The mixing of silver and / or silver compound into the raw coal is not particularly limited, but is preferably performed before the activation step, and more preferably before the carbonization step. For example, when producing crushed coal-based activated carbon, silver and / or a silver compound may be mixed before pulverizing the coal,
Mixing may be performed after pulverization, but in any case, mixing is preferably performed before the carbonization step.

The carbonization step is performed at about 500 to 900 ° C., and carbonized organic matter is decomposed and carbonized by heating to dry distillation.
Subsequently, activation is performed. As the method of activation, a known method such as water vapor activation or chemical activation is used, and the temperature at the time of activation is preferably 900 to 1100 ° C. if water vapor activation.
For chemical activation, 500 to 800 ° C. is suitable. From the viewpoint of cost, steam activation is more preferable, but from the viewpoint of suppressing grain growth of titanium dioxide, it can be said that chemical activation at lower temperature is preferable. In the carbonization and activation step, titanium or a titanium compound other than titanium dioxide is oxidized to titanium dioxide. The titanium dioxide obtained by such a method can have an extremely small particle size of several tens of nm, and a large effect can be obtained even in a small amount.

In the method of the present invention, when importance is placed on cost, for example, ordinary titanium dioxide particles may be added together with the titanium compound to reduce the cost. The production method of the present invention is different from a conventional treatment method in which silver or a silver compound and a titanium compound are immobilized on activated carbon, and in a step before activation, a silver and / or silver compound and a titanium and / or a titanium compound are used. Is characterized by the fact that the pore distribution can be freely controlled without filling the pores of the activated carbon, because the carbon is mixed with the raw coal. Furthermore, the activated carbon obtained by the production method of the present invention is extremely excellent in terms of immobilizing titanium dioxide and silver having a small particle size to activated carbon particles, and the surface of titanium dioxide and silver or a silver compound has abrasion resistance. It exists in a form that is extremely resistant to peeling.

Activated carbon obtained by the production method of the present invention can be used in the same manner as conventionally used activated carbon, and it does not matter how to use a fluidized bed, a fixed bed and the like. The conventional device can be used as it is, and there is no need to increase the size of the device. Further, by using the activated carbon of the present invention under irradiation of ultraviolet rays or sunlight, removal of harmful substances in water or in the gas phase is compared with adsorption removal by activated carbon alone, because decomposition and removal by titanium dioxide photocatalytic reaction are added. , Its removal ability will increase dramatically. Further, antibacterial activity can be expected even when ultraviolet light or sunlight is not irradiated or in a non-irradiated part.
It is suitably used for applications requiring antibacterial properties such as time baths and hydroponics. In addition, since there are advantages such as the difficulty of algae growing on the activated carbon and the longer time required for regeneration of the activated carbon, the maintenance and management of the apparatus becomes easier than ever.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. (Example 1) 1 kg of bituminous coal was ground to about 1 mm, and titanium dioxide (anatase "ST-01") manufactured by Ishihara Sangyo Co., Ltd.
50 g and 22 g of silver acetate (manufactured by Wako Pure Chemical Industries, Ltd.), and further pulverized to 45 μm or less by a vibration type pulverizer, and after granulation,
Crushed to about 0.6 to 1.2 mm. 600 in a nitrogen stream
Activated carbon was obtained in a 850 ° C. rotary kiln in which nitrogen gas containing 50 vol% of steam was introduced at 1 liter / minute. B with a nitrogen adsorption device manufactured by Carlo Elba ("Soapomatic 2100")
When measured by the ET method, the specific surface area was 710 m ² / g
Met. As a result of X-ray diffraction measurement, an anatase phase of titanium dioxide and cubic metallic silver were detected (FIG. 1). When the solid content concentrations of titanium dioxide and silver were determined by ICP emission spectroscopy, each was 9.3 wt.
%, 0.32 wt%. TEM observation (including EDX) was performed to confirm the presence state of titanium dioxide and silver in the activated carbon particles (TEM: Hitachi H-9000N).
A Acceleration voltage 300kV, EDX: Kevex Del
ta series UTW detector, high resolution TEM: Hitachi H
-9000 UHR). FIG. 7 shows a TEM photograph. The TEM-EDX spectrum of the particle C is shown in FIG. Ag was similarly detected from the particles A and B. Cu is from a microgrit copper mesh. FIG. 5 shows an electron beam diffraction pattern (selected area electron beam diffraction pattern) of the particle C of FIG. FIG. 6 shows an electron beam diffraction reference of a gold thin film. FIG. 3 (Analysis result of electron beam diffraction image (Ag / Si
It was confirmed to be cubic silver as shown in (1). In the particles DF in FIG. 7, Ti was detected as shown in the TEM-EDX spectrum in FIG. FIG. 8 is a high-resolution TEM photograph of TiO ₂ (anatase phase) in activated carbon. The particle size is as extremely small as 10 to 30 nm, and it can be seen from the lattice image that it is an anatase phase.

A column having an inner diameter of 2 mm was packed with the obtained activated carbon (16 g), and demineralized water was passed through at SV = 2000 for 5 hours.
A peel test was performed. When the silver content was measured by ICP emission spectroscopy, the silver content was 0.32 wt% before and after water passage.
%, There was no change at all.

(Comparative Example 1) Except that silver acetate was not mixed,
Activated carbon was produced in the same manner as in Example 1. The obtained activated carbon was immersed in a 1% silver nitrate aqueous solution and then dried. The specific surface area is 6
It was 90 m ² / g. As a result of X-ray diffraction measurement, titanium dioxide in the anatase phase, and silver and silver chloride were detected. When the solid content concentrations of titanium dioxide and silver were determined by ICP emission spectroscopy, 9.5 wt%, 0.34 w
t%. When a peeling test similar to that in Example 1 was performed, the silver content was 0.34 wt% before water flow, but was significantly reduced to 0.12 wt% after water flow.

[0020]

According to the production method of the present invention, activated carbon is
Unlike the treatment method of immobilizing silver or a silver compound and a titanium compound, in a step before activation, silver or a silver compound and a titanium compound are mixed with raw coal, so that the pore distribution is not filled in the activated carbon. It is characterized in that it can be controlled freely. Further, activated carbon obtained by the production method of the present invention,
It is extremely excellent in terms of immobilization of titanium dioxide and silver having a small particle size to activated carbon particles, and titanium dioxide and silver or a silver compound are present on the surface in a form excellent in wear resistance and extremely hard to peel off. . Activated carbon obtained by the production method of the present invention having the above characteristics has excellent antibacterial activity regardless of irradiation with ultraviolet light or sunlight and non-irradiation. Alternatively, the ability to remove harmful substances in the gas phase can be greatly improved, and a great industrial advantage is provided.

[Brief description of the drawings]

FIG. 1 shows the results of X-ray diffraction measurement of activated carbon obtained in Example 1.

FIG. 2 is a view showing a TEM-EDX spectrum of the C particles in FIG. 7 of the activated carbon obtained in Example 1.

FIG. 3 is a view showing an analysis result (indexing with Ag / Silver) of an electron beam diffraction image of the activated carbon obtained in Example 1.

FIG. 4 shows the activated carbon obtained in Example 1 from D to FIG.
The figure which shows the TEM-EDX spectrum of the particle of F.

FIG. 5 is a view showing a photograph of a particle structure of the activated carbon obtained in Example 1 by an electron diffraction pattern of the particles of FIG. 7C.

6 is a view showing a photograph showing an electron beam diffraction reference of a gold thin film in the particle structure based on the electron beam diffraction pattern of the particle of FIG. 7C of the activated carbon obtained in Example 1.

FIG. 7 is a view showing the particle structure of the activated carbon obtained in Example 1 by a TEM photograph.

FIG. 8 is a diagram showing a particle structure of TiO ₂ (anatase phase) in activated carbon obtained in Example 1 by a high-resolution TEM photograph.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI D01F 9/12 501 D01F 9/12 501

Claims (7)

[Claims] 1. A method for producing activated carbon, wherein silver and / or a silver compound and titanium and / or a titanium compound are added in a step prior to activation in the method for producing activated carbon. 2. Coal is crushed, granulated, crushed, carbonized,
In the method of producing crushed coal-based activated carbon by activating,
In the coal before granulation, silver and / or silver compound and titanium and / or
Or a method for producing a crushed coal-based activated carbon, characterized by adding a titanium compound. 3. A method for producing granulated activated carbon by pulverizing raw coal, kneading it with a binder, granulating, hardening and carbonizing, and activating the raw coal. Alternatively, a method for producing granulated activated carbon, comprising adding a silver compound and titanium and / or a titanium compound. 4. A method for producing powdered activated carbon, comprising adding silver and / or a silver compound and titanium and / or a titanium compound in a step prior to activation. 5. A method for producing fibrous activated carbon, comprising adding silver and / or a silver compound and titanium and / or a titanium compound in a step prior to activation. 6. The method according to claim 1, wherein the silver compound is added in the form of a solution.
6. The method for producing activated carbon according to any one of claims 1 to 5. 7. The method for producing activated carbon according to claim 1, wherein the titanium compound is added in the form of a solution.