JPH1099678A - Production of silver-compounded active carbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve the life of antibacterial function and the wear resistance by adding silver and/or a silver compound in a process before at least activation in active carbon production. SOLUTION: Silver and/or a silver compound is added to coal before granulation in the case of producing pulverized coal type active carbon by, for example, crushing, granulating, pulverizing, carbonizing, and activating coal. Also, silver and/or a silver compound is added raw material coal before granulation in the case of producing granulated active carbon by finely crushing raw material coal, kneading the resultant coal with a binder, granulating the resultant mixture, hardening and carbonizing the mixture, and activating the obtained mixture. In both cases, the coal or the raw material coal is crushed to 75μm or smaller and used. Moreover, silver and/or the silver compound to be used is preferably powder and the particle size of the powder is 1μm or smaller. There is no specific limitation for the silver compound to be used and silver carboxylate such as CH3COOAg, C6H4COOAg, etc., zeolites ion exchanged with silver ion, ion exchange resin, etc., may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a silver composite activated carbon. Since the silver composite activated carbon produced according to the present invention can disperse antibacterial silver in a metal state inside the activated carbon particles, the silver composite activated carbon has a higher silver than a conventional silver-impregnated activated carbon in which a silver compound is present on the activated carbon particles. Of the antimicrobial activity is greatly reduced, and as a result, the life span of the antibacterial activity is significantly prolonged. Further, even when used under such conditions that the surface of the activated carbon particles is worn, severe wear due to silver and / or silver compounds being present not only on the surface of the activated carbon particles but also inside the activated carbon particles. Later, silver can always be present on the surface and its antimicrobial properties can be maintained.

[0002] The silver composite activated carbon produced according to the present invention is
In particular, it is suitably used as an antibacterial material for sterilizing and removing bacteria and molds in water or in the gas phase.

[0003]

2. Description of the Related Art It has long been known that silver ions have an antibacterial effect. For this reason, a water purification material in which activated carbon is impregnated with silver has been used. Antibacterial activated carbon for drinking water purifiers needs to be used with a low concentration of silver eluted so that treated water does not adversely affect the human body even when used for a long time. for that reason,
Silver ion concentration in drinking water is regulated to 50 ppb or less.

[0004] In general, the solubility of silver and silver compounds in water is low, but nevertheless metallic silver (28 pp at 25 ° C).
Compared to b), that of the silver compound is larger, 193 in silver chloride.
0 ppb, 133 ppb for silver bromide, 33 pp for silver carbonate
m, which is much larger than the regulation value. Activated carbon for water purifier that releases and sterilizes silver ions and its production method,
There is one described in Japanese Patent No. 923347, which is obtained by immersing activated carbon particles in an aqueous silver nitrate solution and then drying.
This is a so-called silver-impregnated activated carbon, in which a large amount of silver and silver compounds are present on the outer surfaces of the activated carbon particles and are not uniformly dispersed inside the particles.

[0005] In addition, those dried after immersion have a large amount of silver compounds other than metallic silver. Therefore, in the case of the silver-impregnated activated carbon described in Japanese Patent No. 923347,
Since the solubility of the silver compound in water is high, the silver content relative to the total amount of activated carbon is reduced by decreasing the amount of silver impregnated itself or by mixing and diluting it with unimpregnated activated carbon.
It was necessary to control the concentration to 3% so that the silver elution concentration did not adversely affect the human body. In addition, since silver and silver compounds are mainly present on the surface of the activated carbon particles, there is a problem that the silver and silver compounds are easily peeled off and are weak against abrasion.

Further, the activated carbon impregnated with silver has a problem in that activated carbon particles are immersed in a silver nitrate solution, so that the pores of the activated carbon are partially blocked. In view of the above, there has been a demand for an activated carbon having a low silver dissolution rate, excellent abrasion resistance, and a long antibacterial life.

[0007]

Accordingly, the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by adding silver and / or a silver compound at a specific time during the production of activated carbon, the activated carbon particles contained Since silver exists only in the state of metallic silver and does not exist as a silver compound, it has been found that the solubility of silver in water is low, the dissolution rate is suppressed, and the life of the antibacterial activity is significantly improved. Furthermore, silver can be uniformly dispersed not only on the outer surface of activated carbon particles but also inside the activated carbon particles and can be present without filling pores, so it is resistant to abrasion and is suitable for use in severe environments such as fluidized beds. The present inventors have found that the activated carbon grain structure can endure and have reached the present invention.

[0008]

That is, the present invention resides in a method for producing activated carbon, characterized by adding silver and / or a silver compound at least in a step prior to activation in the production of activated carbon.

[0009]

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 silver and / or a silver compound is added at least in a step before activation in the method for producing activated carbon. This can be applied to various activated carbon production methods. For example, when crushing, granulating, crushing, carbonizing, and activating coal to produce crushed coal-based activated carbon, silver and / or a silver compound is added to the coal before granulation. The invention can be implemented. In the case of producing granulated activated carbon, raw carbon is finely pulverized, kneaded with a binder, granulated, hardened and carbonized,
The present invention can be carried out by adding silver and / or a silver compound to raw material carbon before granulation upon activation to produce granulated activated carbon.

When the present invention is applied to the production of crushed coal-based activated carbon, the coal used as a raw material is not particularly limited, but those having good granulation properties are preferred. For example, bituminous coal, lignite, anthracite, lignite, peat, peat and the like can be mentioned. If necessary, tar and pitch may be mixed to improve the granulation properties. Of these, bituminous coal having caking properties is particularly preferred.

The above coal is pulverized, granulated, crushed, carbonized and activated to form activated carbon. The method for pulverizing coal is not particularly limited, and a known technique can be employed. The degree of pulverization is preferably 100 μm or less, particularly preferably to 75 μm or less. The addition of silver and / or a silver compound described below may be mixed with coal before pulverization or may be mixed after pulverization. The former method is more preferable from the viewpoint of dispersibility of silver particles in activated carbon. In the latter case, silver and / or a silver compound can be added to pulverized coal and mixed using a general powder mixer. The finely pulverized coal thus obtained may be compression-molded by a known technique such as a pelletizer, a compactor or the like to produce granulated coal. The obtained granulated coal is crushed to a size that is actually used as activated carbon, and if necessary, sized to obtain a crushed coal having a uniform particle size.

When the present invention is applied to the production of granulated activated carbon, the raw coal to be used is not particularly limited, and examples thereof include coconut shell charcoal, coke, charcoal, coal, and resin carbonized products. Coking coal is finely pulverized.
The particle size is preferably 100 μm or less,
Particularly preferably, it is 75 μm or less. If necessary, a binder such as coal tar, pitch, molasses, sap, or starch is added to the obtained pulverized coal, and the mixture is heated and kneaded, and granulated by a granulator such as a pelletizer, a compactor, or an injection press.
The timing of adding silver and / or a silver compound is not limited as long as it is before activation, but it is preferable to add it to the pulverized coal together with a binder.

The form of the silver and / or silver compound used in the present invention is preferably a powder.
It is preferably 10 μm or less, more preferably 1 μm or less. The silver compound used in the present invention is not particularly limited. For example, CH ₃ COOAg, C ₆ H
Silver carboxylate such as ₅ COOAg, Ag ₃ C ₆ H ₅ O ₇ , Ag ₂
CO ₃ , AgBF ₄ , AgNO ₃ , AgCl, AgBr,
AgF, AgI, AgClO ₂ , AgClO ₃ , AgCl
O ₄ , AgBrO ₂ , AgBrO ₃ , AgBrO ₄ , AgI
O ₂ , AgIO ₃ , AgIO ₄ , AgBO ₂ , AgCN, A
_{gOCN, Ag 3 PO 4, Ag} 4 P 2 O 7, AgSO 3 N
H ₂ , Ag ₂ SO ₄ , Ag ₂ SO ₃ , zeolite ion-exchanged with silver ions, ion-exchange resins and the like are preferably used.

The silver compound may be dissolved in water or an organic solvent such as alcohol and used in the form of a solution. In the present invention, the effect can be exhibited irrespective of the form at the time of adding silver and / or a silver compound, which is very useful. That is, even when silver and / or a silver compound is a solution, or is added in a solid state such as a powder, the metallic silver is firmly fixed in the activated carbon particles without filling the pores of the activated carbon. It can be fixed as a state of only metallic silver, and can be in a state in which a silver compound does not substantially exist.

As described above, in any case of obtaining activated carbon by any method, the timing of adding silver and / or a silver compound to raw coal may be any timing as long as it is performed before activation. Preferably, it is performed before the carbonization step. For example, in a method of producing crushed coal-based activated carbon, silver or a silver compound may be mixed before pulverizing the coal, or may be mixed after pulverizing, and in any case, mixing before the carbonization step. Is preferred.

The carbonization step is performed at about 500 to 900 ° C., and carbonized organic matter is decomposed and carbonized by heating to dry distillation. Next, activation is performed. As the activation method, a known method such as water vapor activation or chemical activation can be used. The temperature during activation is preferably 850 to 1100 ° C for steam activation, and 500 to 800 ° C for chemical activation. Thus, according to the production method of the present invention, a silver composite activated carbon in which silver is present inside the activated carbon can be obtained.

The ratio of activated carbon to metallic silver after activation differs depending on the degree of activation, and cannot be specified unconditionally. However, since expensive silver is used, the cost of silver composite activated carbon obtained roughly from the viewpoint of cost is high. 10% by weight or less, particularly preferably 5%
It is suitable that the content is not more than 1% by weight, more preferably not more than 1% by weight. Even at 1% by weight or less, the effect of adding silver can be sufficiently exhibited.

When the activated carbon of the present invention is used under a low silver content such as a drinking water purification material, the activated carbon itself may be reduced in its silver content itself, or may be replaced with ordinary activated carbon containing no silver. It may be used after being mixed and diluted. In general, it is necessary to consider that chlorine in tap water changes metallic silver to silver chloride and the solubility increases rapidly.However, compared to ordinary silver-impregnated activated carbon in which silver and silver compounds are present on the outer surface, In the case of the activated carbon of the present invention, the effect can be said to be much less. This is because, since the metallic silver is dispersed in the activated carbon particles, chlorine is adsorbed and removed by the activated carbon, and the production of silver chloride is suppressed, and as a result, the solubility does not increase so much. The silver content of a conventional commercially available silver-impregnated activated carbon is 0.01 to 0.3% by weight. One of the features is that the density standard (50 ppb or less) can be satisfied. From this, the activated carbon of the present invention can significantly extend the life of the antibacterial activity as compared with the conventional commercially available silver impregnation activity.

In the silver composite activated carbon of the present invention, silver exists only in the form of metallic silver and does not exist as a silver compound. Therefore, silver has low solubility in water, has a low elution rate, and has an antibacterial activity. The life of the device is significantly improved. Furthermore, since silver can be uniformly dispersed not inside the outer surface of the activated carbon particles but inside the particles and can be present without filling the pores, it is resistant to abrasion and withstands its use even in a severe environment such as a fluidized bed. It can be an activated carbon grain structure. Therefore, it can be used similarly to conventionally used activated carbon,
It does not matter how to use the fluidized bed, 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.
In addition, since the life of the antibacterial function is prolonged, maintenance and management of the device becomes easier than ever.

[0020]

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) Silver acetate CH ₃ C00Ag (manufactured by Kishida Chemical)
3.1 g was mixed with 140 g of bituminous coal pulverized to 44 μm or less, granulated, and then crushed to about 0.5 to 2.0 mm.
Carbonization is performed at 750 ° C. for 30 minutes in a stream of nitrogen at 5 l / min, and nitrogen gas containing 50 vol% of steam is added at 1 l / min.
Was activated for 2 hours in the kiln at 900 ° C. introduced in the above.
Nitrogen adsorber "SORPOMATIC 2" manufactured by Carlo Elba
The specific surface area was 1190 m ² / g as measured by the BET method at 100 ”. When the obtained sample (silver composite activated carbon of the present invention) was subjected to X-ray diffraction measurement, it was only carbon and cubic silver except for SiO ₂ which was detected even with no added activated carbon. Not detected. The X-ray diffraction pattern is shown in FIG. The solid concentration of silver was 3.4 wt% as measured with an ICP emission spectrometer “JY38S” manufactured by Johan Bonn. SEM observation (including ED) to confirm the presence state of silver in activated carbon particles
X). 10,10 of the silver composite activated carbon obtained in FIG.
A SEM photograph at a magnification of 00 is shown. SEM-EDX (SEM: Hitachi “S-4500”, EDX: Kevex “Delt”)
a System ") from the X-ray spectrum of Ag. FIG. 3 shows the spectrum of SEM-EDX. From this, silver particles of about 1 μm are present in the activated carbon,
Moreover, it can be seen that it is firmly fixed.

Example 2 In Example 1, 140 g of bituminous coal obtained by pulverizing 0.31 g of silver acetate to 44 μm or less.
When activated carbon was produced in the same manner except that it was mixed with
The specific surface area was 1200 m ² / g. The solid concentration of silver was 0.35 wt% by ICP emission analysis. 0.50 g of the activated carbon thus obtained was placed in an Erlenmeyer flask containing 20 ml of deionized water, and shaken in a thermostat at 25 ° C. to perform a silver dissolution test. Twenty-four hours later, when the silver concentration in water was measured by ICP emission spectroscopy, it was 32 ppb.
Met. (Example 3) A silver elution test was performed in the same manner as in Example 2 except that tap water (tap water) was used instead of deionized water. The silver concentration in the water after 24 hours was 23 ppb. Was.

Comparative Example 1 SEM observation (including EDX) of silver-impregnated activated carbon for a commercial water purifier was performed. SEM-ED
From grains of several tens of μm whiter than X, X of Ag and Cl
The line spectrum was confirmed. 0.50 g of this silver impregnated activated carbon
Into an Erlenmeyer flask containing 20 ml of demineralized water,
Was shaken in a thermostat to perform a silver dissolution test. 2
After 4 hours, the silver concentration in the water was 47 ppb as measured by ICP emission analysis. (Comparative Example 2) A silver elution test was performed in the same manner as in Comparative Example 2 except that tap water (tap water) was used instead of demineralized water. The silver concentration in water after 24 hours was 21 ppb. Was.

(Comparative Example 3) 3.10 g of silver nitrate AgNO ₃ (manufactured by Wako Pure Chemical Industries) was dissolved in 70 ml of water, and 100 g of activated carbon (“Diahope 006” manufactured by Mitsubishi Chemical Corporation) was uniformly sprayed and washed with water. Dried. The specific surface area after drying is 11
70 m ² / g. The solid concentration of silver was 1.94% by ICP emission analysis. When an X-ray diffraction measurement was performed on the obtained sample, S was detected even with no added activated carbon.
iO ₂ and carbon and cubic silver and silver chloride were detected.
FIG. 4 shows an X-ray diffraction pattern of the obtained sample. SEM observation (including EDX) was performed to confirm the presence state of silver in the activated carbon particles. FIG. 5 shows an SEM photograph. The fact that the white grains of several tens of μm are silver and silver chloride was confirmed by SEM-
It was confirmed from the X-ray spectra of Ag and Cl by EDX. FIG. 6 shows the spectrum of SEM-EDX.

(Comparative Example 4) 0.84 g of silver nitrate AgNO ₃ (manufactured by Wako Pure Chemical Industries) was dissolved in 70 ml of water, 1000 g of activated carbon (“Diahop 006”) was uniformly dispersed, washed with water and dried. The solid concentration of silver was 0.05% by ICP emission analysis. 0.50 g of the silver-impregnated activated carbon thus obtained was placed in an Erlenmeyer flask containing 20 ml of demineralized water, and shaken in a thermostat at 25 ° C. to perform a silver dissolution test. Twenty-four hours later, the silver concentration in water was measured by ICP emission spectroscopy and found to be 44 ppb.

(Comparative Example 5) A silver elution test was performed in the same manner as in Comparative Example 4 except that tap water (tap water) was used instead of demineralized water. 2
It was 0 ppb.

[0026]

Industrial Applicability The silver composite activated carbon of the present invention has greatly improved antibacterial life and abrasion resistance, and provides a great industrial advantage.

[Brief description of the drawings]

FIG. 1 is a view showing an X-ray diffraction pattern of a silver composite activated carbon obtained in Example 1.

FIG. 2 is a 10,000 × SEM photograph showing the particle shape of the silver composite activated carbon obtained in Example 1.

FIG. 3 shows SEM-E of the silver composite activated carbon obtained in Example 1.
The figure which shows the spectrum of DX

FIG. 4 shows an X-ray diffraction pattern of a sample obtained in Comparative Example 3.

FIG. 5 shows the particle shape of the sample obtained in Comparative Example 3,
The figure which shows a 000 times SEM photograph

FIG. 6 shows a spectrum of SEM-EDX obtained in Comparative Example 3.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C02F 1/50 540 C02F 1/50 540F

Claims (4)

[Claims] 1. A method for producing a silver composite activated carbon, comprising adding silver and / or a silver compound at least in a step prior to activation. 2. Coal is crushed, granulated, crushed, carbonized,
The method for producing a silver composite activated carbon according to claim 1, wherein silver and / or a silver compound is added to the coal before granulation when the activated carbon is activated to produce the crushed coal-based activated carbon. 3. The raw coal is finely pulverized, kneaded with a binder, granulated, hardened and carbonized, and activated to produce granulated activated carbon. The method for producing a silver composite activated carbon according to claim 1, wherein a silver compound is added. 4. The method for producing a silver composite activated carbon according to claim 1, wherein silver and / or a silver compound is added in the form of a solution.