JP4929508B2 - Silver impregnated activated carbon, method for producing the same, and water purifier - Google Patents

Description

  The present invention relates to silver-impregnated activated carbon, a method for producing the same, and a water purifier. More specifically, the present invention relates to a silver impregnated activated carbon impregnated with a silver compound mainly composed of silver carbonate, a method for producing the same, and a water purifier. Since the silver impregnated activated carbon of the present invention can stably elute 10 ppb to 100 ppb of silver ions in a so-called high temperature range of 40 to 80 ° C., it is excellent as an antibacterial water purification material and is used for a water purifier. It is suitable for.

In recent years, there has been a demand for delicious water free from chlorine odor and mold odor for water purification, and various water purifiers have been proposed for this demand. The water purifier is used to remove residual chlorine and other odorous substances in tap water, and the filter media such as activated carbon and membrane are used singly or in combination, but the water is retained in the water purifier for a long time. And bacteria may propagate inside the water purifier due to dechlorination by activated carbon. In order to suppress this, antibacterial activated carbon in which silver or a silver compound is impregnated with an adsorbent such as activated carbon is used as a water purification material (Patent Document 1).
JP-A-49-61950

  Antibacterial activated carbon for water purifiers must elute silver ions of 10 ppb or more in order to suppress bacterial growth, and at the same time low concentration of silver so that treated water does not adversely affect the human body even when used for a long time. It is necessary to elute ions. According to the US Public Health Service (USEPA), the standard of silver contained in drinking water is 100 ppb or less, and in antibacterial activated carbon, silver ions are in the range of 10 ppb to 100 ppb, preferably in the range of 10 to 50 ppb. It is necessary to elute stably.

  In recent years, hot and cold water mixing faucets have become widespread in ordinary households. The hot water and water mixing faucet is a faucet that can freely control the mixing ratio of hot water and cold water with a single lever. With the widespread use of the hot water and water mixing faucet, so-called high-temperature water of 40 ° C or higher passes through the water purifier. Opportunities are also increasing. Recently, there is an increasing demand for using warm water as water used for cooking. If hot water is used for cooking, the time for boiling hot water is shortened, and as a result, the time required for cooking can be shortened. Due to these social circumstances, an antibacterial activated carbon that can be used in a water purifier capable of handling hot water of 40 ° C. or higher is desired, but the above-described method of attaching silver or a silver compound to activated carbon is a so-called 35 ° C. or higher. There was a problem that the elution of silver ions exceeded 100 ppb even in the high temperature region.

In addition, a method is known in which activated carbon is placed in a silver nitrate solution and subjected to reduction treatment in the vicinity of the activated carbon surface while adsorbing silver nitrate to deposit metallic silver (silver simple substance), silver oxide, and silver chloride (Patent Document 2). However, since metallic silver and silver oxide have low solubility in water, in this method, elution of silver ions is less than 10 ppb in a normal temperature range of 0 to 20 ° C., which is not satisfactory. In addition, silver chloride exhibits a preferable elution behavior of silver ions in a normal temperature range of 0 to 20 ° C., but silver ions exceed 100 ppb in a high temperature hot water range of 40 ° C. to 80 ° C., which is not satisfactory. . Moreover, Patent Document 2 describes the presence of silver-impregnated activated carbon made of silver carbonate for the time being, but does not describe any specific method for attaching silver carbonate.
JP 2006-348966 A

As another method for producing silver impregnated activated carbon, after the activated carbon and colloidal silver carbonate emulsion are uniformly mixed, a reducing agent such as hydrogen peroxide is added, and the metallic silver produced by the reduction of the silver carbonate is impregnated to the activated carbon. A method is known (Patent Document 3). However, metallic silver and silver oxide have low solubility in water, and satisfactory results cannot be obtained because silver ions are below 10 ppb in the normal temperature range of 0 to 20 ° C.
JP-A-10-85759

  In addition, colloidal silver carbonate emulsion can be uniformly mixed with activated carbon and dried to attach silver carbonate to the activated carbon. However, since colloidal carbonate emulsion has already crystallized silver carbonate in the solution, Metal silver cannot be deposited in the pores. Therefore, there exists a problem that silver carbonate will flow out in the initial stage in the use stage of a water purifier, and it is not practical.

Further, another method for producing silver-impregnated carbon is disclosed in which silver-activated carbon is obtained by impregnating activated carbon with silver chloride obtained by mixing an aqueous silver nitrate solution with sodium chloride, calcium chloride, or other chlorinated compounds and an aqueous solution or hydrochloric acid thereof. (Patent Document 4). However, although this silver-impregnated activated carbon shows a preferable elution behavior of silver ions in a normal temperature range of 0 to 20 ° C., the elution of silver ions exceeds 100 ppb in a high temperature hot water range of 40 ° C. to 80 ° C. Even the silver-impregnated activated carbon obtained in (1) cannot be suitably used.
JP 2006-26598 A

  Therefore, the object of the present invention is not only to stably elute silver ions having antibacterial properties in a temperature range of 0 to 40 ° C., but preferably 10 ppb even in a so-called high temperature range of 40 ° C. to 80 ° C. An object of the present invention is to provide a silver-impregnated activated carbon capable of stably eluting silver ions in the range of ˜100 ppb, a method for producing the same, and a water purifier.

  As a result of intensive studies to achieve the above object, the present inventors adsorbed an aqueous silver compound solution on activated carbon, mixed an aqueous solution or carbonate compound of sodium carbonate, calcium carbonate, or other carbonate compound, The present inventors have found that the above-mentioned problems can be achieved by silver-impregnated activated carbon in which silver carbonate is impregnated by crystallization in the pores, and have reached the present invention. That is, the present invention is a silver impregnated activated carbon in which a silver compound is impregnated with activated carbon, and the silver compound adhering is a silver compound mainly composed of silver carbonate, and the amount of silver impregnation is 0.03% by weight or more and 0.2. It is a silver impregnated activated carbon characterized by being not more than wt%.

  Another invention of the present invention is a silver-impregnated activated carbon characterized by mixing an aqueous solution of calcium chloride and an aqueous sodium carbonate solution into a mixture obtained by uniformly mixing activated carbon and a silver nitrate solution, washing, dehydrating and drying. It is a manufacturing method.

  Another invention of the present invention is a method for producing a silver-impregnated activated carbon characterized by mixing an aqueous solution of sodium carbonate with a mixture obtained by uniformly mixing activated carbon and a silver nitrate solution, washing, dehydrating and drying. .

  Another invention of the present invention is a water purifier using these silver-coated activated carbons.

  According to the present invention, it is possible to provide a silver-impregnated activated carbon in which a silver compound mainly composed of silver carbonate is attached to the surface of the activated carbon. Since such silver impregnated activated carbon can stably elute antibacterial silver ions in a temperature range of 0 to 80 ° C., it is suitably used for water purifier applications corresponding to hot water. In particular, silver ions can be stably eluted in a high temperature region (region where the water temperature is high) at 40 ° C to 80 ° C. Moreover, since elution of silver ions is stable within the range of 10 ppb to 50100 ppb, there is an advantage that the life is longer than that of a conventional silver chloride-impregnated activated carbon.

  The greatest feature of the silver-impregnated activated carbon of the present invention is to provide a silver-impregnated activated carbon in which a silver compound mainly composed of silver carbonate is impregnated on the surface of the activated carbon. By using it as a material, it is possible not only to stably elute silver ions having antibacterial properties in a temperature range of 0 to 40 ° C., but also in a high temperature region (region where water temperature is high) at 40 ° C. to 80 ° C. Silver ions can be eluted.

The activated carbon used in the present invention may be activated carbon obtained from any carbonaceous material as long as it becomes activated carbon by carbonizing and activating the carbonaceous material, but has a specific surface area of several hundred m ² / g or more. Is preferred. The activated carbon may have any shape such as powder, granule, or fiber.

  Carbonaceous materials include, for example, fruit husks such as wood, sawdust, charcoal, coconut husk, walnut husk, fruit seeds, pulp production by-products, lignin, molasses, etc. Mineral materials such as blue coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, petroleum pitch, synthetic materials such as phenol, saran and acrylic resin, and natural materials such as recycled fiber (rayon) can be mentioned. . Among these, it is preferable to use plant-based coconut shell activated carbon in view of adsorption performance and water purifier application.

  When powdered activated carbon is used, the average particle diameter is preferably 75 μm to 2.8 mm (200 mesh to 7 mesh), from the viewpoint of workability, contact efficiency with water, resistance to water passage, etc., and 100 μm to 2.0 mm. Is more preferable. When using granular activated carbon, for the same reason, an average particle diameter of 75 μm to 1.7 mm (200 mesh to 10 mesh) is preferable, and 100 μm to 1.4 mm is more preferable. When using fibrous activated carbon, it is preferable to cut it to about 1 to 5 mm from the viewpoint of moldability, and use an iodine adsorption amount of 1200 to 3000 mg / g from the viewpoint of removability of free chlorine. Is preferred.

  The silver compound mainly composed of silver carbonate attached to the activated carbon may contain other silver compounds such as silver chloride and silver oxide as long as silver carbonate is the main component. Then, silver chloride is preferable as the silver compound other than silver carbonate, and these may be mixed crystals. This is because the presence of silver carbonate destroys the colloidal formation of silver chloride and consequently suppresses elution of silver ions.

  The ratio (A) / (B) of silver chloride (A) and silver carbonate (B) is preferably 1/100 to 80/100, more preferably 5/100 to 30/100, by weight. . 10/100 to 20/100 is more preferable. The term “addition” in the present invention means all states in which the silver carbonate produced by the reaction of the silver compound and the carbonic acid compound and the activated carbon are firmly fixed, but it is preferable that the activated carbon is fixed inside the pores. If the amount of silver compound impregnated is too small, the antibacterial property will be poor, and if it is too large, the elution amount of silver will be too large. preferable.

  The silver compound mainly composed of silver carbonate attached to the activated carbon is most preferably only silver carbonate. The silver-impregnated activated carbon impregnated with the silver compound mainly composed of the above-mentioned silver carbonate has a dissolution amount of silver ions in a temperature range of 40 ° C. to 80 ° C. in order to stably elute silver ions in a high temperature range. Is preferably 10 ppb or more and 100 ppb or less.

  The activated carbon impregnated with the silver compound mainly composed of silver carbonate of the present invention is firstly uniformly mixed with powder, granule or aqueous solution of activated carbon and a silver compound, and then, 1) of the chloride compound is added to the mixture. Powder, granule or aqueous solution, and 2) Carbonate powder, granule or aqueous solution are added and mixed, washed with water, dehydrated, dried, and sieved as necessary. The mixing means can be, for example, a mixer such as various blenders and mixers.

  Examples of the silver compound include, but are not limited to, silver halide such as silver chloride, silver carboxylate, silver nitrate, silver oxide, silver carbonate, silver sulfate, silver phosphate, silver cyanide, and silver colloid. A powder, a granular material, and a solution can be mentioned. These silver compounds may be used alone or as a mixture of two or more silver compounds. Moreover, it is preferable to use a highly soluble silver compound as an aqueous solution, and it is more preferable to use an aqueous silver nitrate solution because it can be uniformly attached to the activated carbon particles.

  Although the density | concentration in the case of using a silver compound by aqueous solution is not specifically limited, 10-200 g / liter (L) is preferable and 20-70 g / L is further more preferable. When the water content of the activated carbon exceeds 50%, the stirring state in the blender deteriorates and unevenness may occur in the adhesion. Therefore, the amount of the silver compound aqueous solution is 10 to 50% by weight of the activated carbon and the total silver compound aqueous solution. It is preferable to be 25 to 45% by weight.

  Although it does not specifically limit as a chloride compound, Calcium chloride, sodium chloride, hydrochloric acid, etc. can be mentioned. In addition, the carbonate compound is not particularly limited, and examples thereof include powders such as sodium carbonate, calcium carbonate, aluminum carbonate, magnesium carbonate, sodium hydrogen carbonate, calcium hydrogen carbonate, and carbonic acid, granules, and solutions. Can do. These carbonic acid compounds may be used alone, or two or more carbonic acid compounds may be mixed and used. In addition, it is preferable to use a carbonate compound having high solubility as an aqueous solution. Particularly when an aqueous sodium carbonate solution is used, it can be uniformly mixed with the activated carbon particles and can react with the silver compound, and silver carbonate can be uniformly attached to the activated carbon particles. More preferred.

  The chloride compound needs to be reacted with the added silver compound to form silver chloride. When using a calcium chloride aqueous solution, the concentration of the aqueous solution is not particularly limited, but is preferably 1 to 108 g / L, and more preferably 2 to 30 g / L.

  The carbonic acid compound needs to react with the total amount of the charged silver compound to form silver carbonate. When using sodium carbonate aqueous solution, the density | concentration of aqueous solution is although it does not specifically limit, 10-294 g / L is preferable and 40-150 g / L is more preferable.

  The activated carbon in which only silver carbonate is impregnated with the silver compound mainly composed of silver carbonate of the present invention can be obtained without using the chloride compound 1) in the above production method. In this case, the carbonic acid compound needs to be reacted with the total amount of the added silver compound to form silver carbonate.

Although the mechanism leading to the addition of silver carbonate according to the present invention cannot be clearly described, it is presumed that the activated carbon added with silver carbonate is obtained by the following chemical reaction.
AgNO ₃ + H ₂ O → Ag (+) + NO ₃ (−) + H ₂ O (1)
2Ag (+) + Na ₂ CO ₃ → Ag ₂ CO ₃ + 2Na (+) (2)
In the case of silver chloride impregnation, the sodium carbonate of the formula (2) becomes a chloride such as sodium chloride.
Ag (+) + NaCl → AgCl + Na (+) (3)

  Electron micrographs of silver carbonate-impregnated coal and silver chloride-impregnated coal obtained in Examples and Comparative Examples described later are shown in FIGS. 1 and 2, and silver carbonate is more stable in elution of silver ions than silver chloride. The following points can be considered as the first reason. The silver chloride-impregnated carbon has spherical silver chloride particles fixed on the surface of the activated carbon particles, while the silver carbonate-added carbon has silver carbonate crystals fixed inside the pores of the activated carbon. For this reason, silver carbonate-impregnated charcoal has a structure in which there is less contact between the silver compound and water due to water flow, and the elution is less likely to occur.

Moreover, the following points can be considered as the second reason that elution of silver ions is more stable in silver carbonate than in silver chloride.
Since the solubility of silver chloride at 25 ° C. is 1.9 ppm and the solubility of silver carbonate is 33 ppm, silver chloride has less elution of silver ions. However, silver chloride, which is originally bonded and crystallized between molecules, is a colloid that forms chloride ions in the first layer and sodium ions in the second layer mainly in silver chloride due to the large amount of chloride ions in tap water. In order to form, it cannot bond between molecules and cannot crystallize. Furthermore, since the solubility of salts such as sodium chloride, sodium carbonate, and calcium carbonate increases as the temperature rises, the concentration of chloride ions and sodium ions that form colloids increases in warm water, making it easier to form colloids. . For this reason, it is considered that silver ions are eluted in a large amount in the case of silver chloride in warm water compared to silver carbonate.

  The obtained silver carbonate-impregnated activated carbon is granular and can be used as a water purification material as it is, but it may be further mixed with 2 to 10 times the amount of activated carbon depending on the purpose. The silver carbonate-impregnated activated carbon can be automatically filled and used as a water purification material as it is, but it is also a preferable aspect that it is further heated and molded to be used as a molded product in the form of a cartridge. Furthermore, in order to give heavy carbonate adsorption performance to silver carbonate impregnated activated carbon, an ion exchanger or zeolite may be added as appropriate.

  When the activated carbon of silver carbonate impregnated according to the present invention is used as a water purification material, it has excellent antibacterial properties in a temperature range of 0 to 40 ° C., has low water resistance, and maintains the removal performance of free chlorine, THM and the like in a well-balanced manner. It is excellent in removal, and fine particles of the fine particle compound do not flow out when water is passed. In particular, a stable silver elution amount can be achieved in a high temperature region (region where the water temperature is high) at 40 ° C. to 80 ° C.

  The silver carbonate-impregnated activated carbon of the present invention is filled in a container as a water purification material and can be used alone as it is, but it is used in combination with known nonwoven fabrics, various adsorbents, ceramic filter media, hollow fiber membranes, etc. Also good. EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

Example 1
45 kg of granular activated carbon (Kuraray Chemical Co., Ltd. GW48 / 100 (particle size: 0.30 mm to 0.15 mm, specific surface area: 800 m ² / g)) is charged into a mixer and stirred. [Manufactured] An aqueous silver nitrate solution having a silver nitrate concentration of 52 g / L obtained by dissolving 1052 g in 20 L of water was sprayed over 20 minutes, and further stirred for 20 minutes. To this mixture, a sodium carbonate aqueous solution having a sodium carbonate concentration of 113 g / L obtained by dissolving 790 g of sodium carbonate [manufactured by Central Glass Co., Ltd.] in 7 L of water was sprayed over 20 minutes while stirring, and further stirred for 20 minutes. .

  The mixture is transferred to a centrifuge, washed with additional 180 L of water, dehydrated, heated for 12 hours using a heat dryer at a temperature of 150 ° C., then passed through a vibration sieve to 48/100 mesh (upper sieve) 48 mesh, 0.3 mm aperture, lower mesh 100 mesh, aperture 0.15 mm) to obtain silver carbonate-impregnated activated carbon. 1.0 kg of this silver carbonate-impregnated charcoal and 9.0 kg of the above-mentioned granular activated carbon (GW48 / 100) manufactured by Kuraray Chemical Co., Ltd. are charged into a mixer and mixed to obtain 10.0 kg of a mixture of silver carbonate-impregnated activated carbon and granular activated carbon. Obtained. The amount of silver applied was measured by ICP analysis and found to be 0.15% by weight.

30 cc of a mixture of silver carbonate impregnated activated carbon and granular activated carbon is packed into a 60 cc column as a water purification material, and tap water with water temperatures of 20 ° C., 40 ° C. and 80 ° C. is 1.0 liter (L) / min (SV1000hr ⁻¹ ). The silver concentration was measured. The relationship between the water flow rate and the silver concentration is shown in FIGS. The silver carbonate-impregnated activated carbon of the present invention not only shows stable silver elution at 20 ° C., but also shows no significant silver elution behavior at 40 ° C. and 80 ° C., and silver elution is stable. Was.

Example 2
10.0 kg of a mixture of silver carbonate-impregnated activated carbon and granular activated carbon was obtained in the same manner as in Example 1 except that a silver nitrate aqueous solution having a silver nitrate concentration of 35 g / L was used and a sodium carbonate aqueous solution having a sodium carbonate concentration of 75 g / L was used. . The amount of silver attached was measured by ICP analysis and found to be 0.1% by weight. The silver concentration at a water temperature of 80 ° C. is shown in Table 1.

Examples 3-5
A mixture of silver carbonate-impregnated activated carbon and granular activated carbon was prepared in the same manner as in Example 1 except that the concentration of silver nitrate and the particle size of activated carbon were changed, and the silver concentration at a water temperature of 80 ° C. was prepared in the same manner as in Example 1. Table 1 shows.

Example 6
45 kg of granular activated carbon (Kuraray Chemical Co., Ltd. GW48 / 100 (particle size: 0.30 mm to 0.15 mm, specific surface area: 800 m ² / g)) is charged into a mixer and stirred. [Manufactured] A silver nitrate aqueous solution having a silver nitrate concentration of 35 g / L obtained by dissolving 695 g in 20 L of water was sprayed over 20 minutes, and further stirred for 20 minutes. To this mixture, a calcium chloride aqueous solution having a calcium chloride concentration of 28 g / L obtained by dissolving 47 g of calcium chloride [manufactured by Central Glass Co., Ltd.] in 1.5 L of water was sprayed over 3 minutes while stirring, and further 10 minutes. Stir. Subsequently, a sodium carbonate aqueous solution having a sodium carbonate concentration of 78 g / L obtained by dissolving 470 g of sodium carbonate [manufactured by Central Glass Co., Ltd.] in 6 L of water was sprayed over 20 minutes while stirring, and further stirred for 20 minutes.

  The mixture is transferred to a centrifuge, washed with additional 180 L of water, dehydrated, heated for 12 hours using a heat dryer at a temperature of 150 ° C., then passed through a vibration sieve to 48/100 mesh (upper sieve) Was obtained by sieving to 48 mesh, mesh opening 0.3 mm, lower sieve 100 mesh, mesh opening 0.15 mm) to obtain activated carbon to which silver chloride and silver carbonate were attached. 1.0 kg of the activated carbon to which silver chloride and silver carbonate are impregnated and 9.0 kg of the above-mentioned granular activated carbon (GW48 / 100) manufactured by Kuraray Chemical Co., Ltd. are put into a mixer, mixed and silver chloride and silver carbonate are impregnated. 10.0 kg of a mixture of activated carbon and granular activated carbon was obtained. The amount of silver attached was measured by ICP analysis and found to be 0.1% by weight. Using this as a water purification material, the silver concentration of water flow was evaluated in the same manner as in Example 1. Table 1 shows the relationship between the concentration of silver nitrate at 80 ° C. and the silver concentration of water flow.

Examples 7-8
A silver-impregnated activated carbon was prepared in the same manner as in Example 6 except that the amounts of calcium chloride and sodium carbonate to be added were changed, and a water purification material was prepared in the same manner as in Example 5. Water was passed in the same manner as in Example 1. The silver concentration of was evaluated. Table 1 shows the relationship between the concentration of silver nitrate at 80 ° C. and the silver concentration of water flow.

Comparative Example 1
In Example 1, silver chloride impregnation was carried out in the same manner as in Example 1 except that sodium carbonate was not used and a calcium chloride aqueous solution having a calcium chloride concentration of 28 g / L obtained by dissolving 413 g of calcium chloride in 15 L of water was used. Activated carbon was obtained. A mixture of silver chloride impregnated activated carbon and granular activated carbon in the same manner as in Example 1 using 1.0 kg of this silver carbonate impregnated carbon and 9.0 kg of the above-mentioned granular activated carbon (GW48 / 100) manufactured by Kuraray Chemical Co., Ltd. 10.0 kg Got. The amount of silver applied was measured by ICP analysis and found to be 0.15% by weight.

Using this as a water purification material, 30 g is packed in a 60 cc column, tap water with a water temperature of 20 ° C., 40 ° C., and 80 ° C. is passed at a flow rate of 1.0 L / min (SV1000hr ⁻¹ ), and the silver concentration is measured. did. The relationship between the water flow rate and the silver concentration is shown in FIG. 3, FIG. 4, and FIG. The silver elution concentration of silver chloride impregnated activated carbon increased rapidly with increasing water temperature. In particular, in the region where the water temperature was 80 ° C., the elution concentration of silver easily exceeded 100 ppb, and good results could not be obtained.

Comparative Examples 2-3
A water purification material was prepared in the same manner as in Comparative Example 1 except that the concentration of silver nitrate to be added and the particle size of the activated carbon were changed, and the silver concentration of water flow was evaluated in the same manner as in Comparative Example 1. Table 2 shows the relationship between the concentration of silver nitrate at 80 ° C. and the silver concentration of water flow.

Comparative Examples 4-5
A water purification material was prepared in the same manner as in Example 1 except that the concentration of silver nitrate to be added and the particle size of activated carbon were changed, and the silver concentration of water flow was evaluated in the same manner as in Comparative Example 1. Table 3 shows the relationship between the concentration of silver nitrate at 80 ° C. and the silver concentration of water flow. Even in the case of activated carbon impregnated with silver carbonate, when the amount of silver adhering exceeded 0.2% by weight, the elution amount of silver increased rapidly, exceeding 100 ppb, and good results were not obtained.

Comparative Example 6
Using the same method as in Example 1, the amount of silver nitrate was reduced to prepare a silver carbonate-impregnated activated carbon having a silver content of 0.02% by weight. The silver elution amount of this silver carbonate impregnated activated carbon at 80 ° C. was measured. The elution amount of silver was 8 ppb. Moreover, this silver carbonate-impregnated activated carbon had an elution of silver of 3 ppb or less at 20 ° C., and could only elute silver in an amount that could hardly be expected to have antibacterial properties.

  According to the present invention, it is possible to provide a silver-impregnated activated carbon in which a silver compound mainly composed of silver carbonate is attached to the surface of the activated carbon. Since such silver impregnated activated carbon can stably elute antibacterial silver ions in a temperature range of 0 to 80 ° C., it is suitably used for water purifier applications corresponding to hot water. Moreover, since elution of silver ions is stable within a range of 10 to 100 ppb, there is an advantage that the life is longer than that of the conventional silver chloride-impregnated activated carbon.

2 is a micrograph (magnification 3000 times) of the silver chloride impregnated activated carbon obtained in Comparative Example 1. 2 is a photomicrograph (magnification 3000 times) of the silver carbonate obtained in Example 1. It is a graph which shows the relationship between the silver concentration (ppb) measured at the water temperature of 20 degreeC using the activated carbon containing silver carbonate impregnation charcoal obtained in Example 1 and Comparative Example 1 as a water purification material, and the amount of water flow (L). . It is a graph which shows the relationship between the silver density | concentration (ppb) measured at the water temperature of 40 degreeC using the activated carbon containing the silver carbonate impregnation activated carbon obtained in Example 1 and Comparative Example 1 as a water purification material, and the amount of water flow (L). . It is a graph which shows the relationship between the silver concentration (ppb) measured at the water temperature of 80 degreeC using the activated carbon containing the silver carbonate impregnated activated carbon obtained in Example 1 and Comparative Example 1 as a water purification material, and the amount of water flow (L). .

Explanation of symbols

1 Silver chloride 2 Silver carbonate 3 Activated carbon

Claims (9)

A silver impregnated activated carbon in which a silver compound is impregnated with activated carbon, and the silver compound adhering is a silver compound mainly composed of silver carbonate, and the amount of silver adhering is 0.03% by weight or more and 0.2% by weight or less. Silver impregnated activated carbon characterized by The silver impregnated activated carbon according to claim 1, wherein the impregnated silver compound contains silver chloride. The silver impregnated activated carbon according to claim 1 or 2, wherein the ratio (A) / (B) of silver chloride (A) to silver carbonate (B) is 1/100 to 80/100 by weight. 2. The silver impregnated activated carbon according to claim 1, wherein the impregnated silver compound is silver carbonate. The silver-impregnated activated carbon according to any one of claims 1 to 4, wherein an elution amount of silver ions is 10 ppb or more and 100 ppb or less in a temperature range of 40 ° C or more and 80 ° C or less. A method for producing a silver-impregnated activated carbon, comprising mixing a mixture obtained by uniformly mixing activated carbon and a silver nitrate solution with an aqueous calcium chloride solution and an aqueous sodium carbonate solution, washing, dehydrating and drying. A method for producing silver-impregnated activated carbon, comprising mixing a mixture obtained by uniformly mixing activated carbon and a silver nitrate solution with an aqueous sodium carbonate solution, washing, dehydrating and drying. A water purifier using the silver-coated activated carbon according to claim 1 as a water purification material. The water purifier according to claim 8, wherein the water purification material further contains activated carbon.

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