JP2007216215A - Adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an activated carbon-based adsorbent which can efficiently remove residual chlorine in tap water, volatile organic compounds such as trihalomethane, heavy metals, elutes silver ions gradually into water, and enables a stable gradual release of silver ions from the very early stage of passing water for a long period of time, especially when applied to a water purifier. <P>SOLUTION: Activated carbon is treated with hydrochloric acid to adsorb chloride ions at 0.1-2 mass fraction% to activated carbon, and then mixed with a silver or silver compound-containing liquid to be impregnated by silver of a silver compound. The adsorbent is made by mixing the silver-impregnated activated carbon and silver-unimpregnated activated carbon. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water treatment adsorbent that gradually elutes silver ions into water and exhibits a stable antibacterial effect, and a method for producing the same. Especially applied to water purifiers, adsorb and remove residual chlorine, volatile organic compounds such as trihalomethane, heavy metal ions, etc., and gradually release silver ions into water at a stable concentration from the very beginning to the long term, The present invention relates to an adsorbent for water treatment that exhibits a sustained antibacterial effect and a method for producing the same.

If water is retained in the water purifier using activated carbon as an adsorbent for a long time, residual chlorine is decomposed by the activated carbon, so that bacteria may grow in the water purifier. In order to suppress this, it is known to add silver or a silver compound to the activated carbon.
For example, a method of adhering silver or a silver compound to ordinary activated carbon has been proposed (Patent Document 1). However, when ordinary activated carbon is used as an adsorbent, the amount of silver or silver compound added or bound by activated carbon. The state is not constant, and the amount of silver ions eluted into the treated water cannot be adjusted.
Moreover, although the method of adding silver or a silver compound in the manufacturing process of activated carbon is proposed (patent document 2), the manufacturing process is complicated, and this document also describes the state of elution and the amount of elution of silver ions in treated water. No adjustment is mentioned or taken into account.
Furthermore, an attempt has been made to add silver to activated carbon in which chloride ions are adsorbed on activated carbon to increase the amount of silver deposited on the activated carbon and extend the elution period of silver into water (Patent Document 3).

JP-A-49-61950 Japanese Patent Laid-Open No. 10-99678 JP 2005-279494 A

In any of the adsorbents described in the above-mentioned documents, a high concentration of silver ions is released into the water at the beginning of water flow, and the release does not last long. When the release of silver ions stops, the adsorbent and the accumulated water in the water purifier are easily contaminated with bacteria.
In addition, when water is passed through these silver-impregnated activated carbons, very high concentrations of silver may be eluted at the very beginning, which is not only a safety concern, but also such containers with high water concentrations of silver are added. In some cases, silver may react with the components of the container to cause discoloration of the container.
The object of the present invention is not only to efficiently remove volatile organic compounds such as residual chlorine and trihalomethane in water, particularly tap water, but also to stably elute an appropriate amount of silver ions from the very beginning of water flow for a very long time. An object of the present invention is to provide an adsorbent that exhibits a stable antibacterial effect.

  When silver or a silver compound is impregnated with activated carbon, the silver or silver compound on the activated carbon surface is present as a fine solid on the outer surface or pore surface of the activated carbon, and silver ions are generated from these silver or silver compounds by passing water. It is gradually released. However, the inventors' research has revealed that the content of chloride ions contained in the activated carbon before the addition of silver or silver compound affects the elution amount of silver or silver compound. That is, the higher the concentration of chloride ions contained in the activated carbon before the addition of silver or silver compounds, the more stable the silver ions elute when passing water, even when a large amount of silver is attached to the activated carbon. Can be made. However, as described above, it was revealed that high concentration of silver ions elutes in water at the beginning of water flow.

  Therefore, the activated carbon is preliminarily adsorbed with chloride ions sufficient to react with silver or a silver compound, and silver or a silver compound is impregnated. When adsorbed by mixing, it was discovered that silver ions with an appropriate concentration can be released into water unexpectedly for a long time without releasing high concentrations of silver ions at the beginning of water flow. As a result of further research based on the knowledge, the present invention was completed.

That is, the present invention
(1) Activated carbon in which silver or a silver compound is impregnated on activated carbon in which chloride ions are adsorbed by 0.1 to 2% by mass with respect to the activated carbon and silver-free activated carbon in a mass ratio of 1: 0.5 to 1:19. Water treatment adsorbents mixed in proportions,
(2) The silver content of the activated carbon impregnated with silver or a silver compound is 0.1 to 5 mass%, and the silver content relative to the total amount of the water treatment adsorbent is 0.05 to 2 mass%. (1) Adsorbent for water treatment according to
(3) Adsorbent for water treatment according to (1) to (2), which is a filter medium for a water purifier,
(4) Adsorbent for water treatment according to (1) to (2), which is a filter medium for a water purifier that is intermittently passed.
(5) Activated charcoal is treated with hydrochloric acid to adsorb 0.1 to 2% by mass% of chloride ions to the activated carbon, and then mixed with silver or a silver compound-containing solution to attach silver or a silver compound. The method for producing an adsorbent for water treatment according to any one of (1) to (4), wherein the silver-free impregnated activated carbon is mixed at a mass ratio of 1: 0.5 to 1:19.
It is.

  An adsorbent obtained by impregnating silver or a silver compound with activated carbon adsorbing chloride ions and mixing non-implanted activated carbon in a mass ratio of 1: 0.5 to 1:19, Producing activated carbon by adsorbing chloride ions by bringing the activated carbon into contact with an aqueous hydrochloric acid solution, adding an aqueous solution of colloidal silver or a water-soluble silver compound to the resulting activated carbon, and then mixing the activated carbon without silver addition Can do.

Here, the chloride means a compound in which chlorine is combined with another more positive element as a negative element. The oxidation number of chlorine in chloride is always −1, and in a compound with a metal element having a high positiveity, chlorine becomes chloride ion Cl ⁻ to form an ionic bond. Simply spraying a chloride such as sodium chloride onto activated carbon or impregnating a chloride solution with activated carbon does not result in the adsorption of chloride ions in the present invention. That is, for example, chloride contained in sodium chloride or the like is not adsorbed on activated carbon as chloride ions, but only adheres on the activated carbon as sodium chloride crystals, and silver chloride is formed on a part of its surface. This is because they are easily peeled off due to wear or the like, or flow out together with unreacted chloride at the beginning of water flow.

  Therefore, in the present invention, chloride ions can be adsorbed on activated carbon by bringing activated carbon into contact with hydrochloric acid. In this case, since chloride ions are present on the entire surface of the activated carbon in a single ion state rather than in a crystalline state, when silver or a silver compound is impregnated, the silver is formed as fine silver chloride over the entire activated carbon surface. A large amount of silver can be deposited. When water is passed through activated carbon impregnated with silver or a silver compound, silver ions are released into the treated water for a relatively long period due to the solubility equilibrium of silver chloride. It elutes in treated water at a high concentration in the initial stage, causing the above-mentioned problems.

  However, if silver-free coal is simultaneously present in silver-impregnated coal, excessively eluted silver ions are temporarily adsorbed on the silver-free activated carbon, thereby preventing dissolution of high-concentration silver ions into the treated water. . Silver ions adsorbed on the silver-free activated carbon will eventually elute into the treated water. For this reason, silver does not elute at a high concentration exceeding 100 μg / L at the beginning of water flow. Moreover, the elution period of silver ions having an appropriate concentration for exhibiting the antibacterial effect is remarkably extended by using the mixed silver-free activated carbon.

The raw materials for the activated carbon used in the method of the present invention are coconut shell, coal, coke, wood flour, sawdust, natural fibers (eg, hemp, cotton, etc.), synthetic fibers (eg, rayon, polyester, etc.), synthetic resins (eg, , Polyacrylonitrile, phenol resin, polyvinylidene chloride, polycarbonate, polyvinyl alcohol) and the like which are generally used. Particularly preferred is coconut shell.
Although these raw materials are carbonized and activated to obtain activated carbon, the activation method is not particularly limited. For example, “activated carbon industry”, heavy chemical industry news agency (1974), p. 23-p. 37, any activated carbon other than activated with a halogen gas, such as activated charcoal with an active gas such as water vapor, oxygen, carbon dioxide, or chemical activated charcoal using phosphoric acid, zinc chloride, etc. Anything can be used.
The activated charcoal has a BET specific surface area of generally 00 to 2000 m ² / g, preferably 700 to 1800 m ² / g.
Although a particle size is not specifically limited, Usually, it is 0.075-5 mm, Preferably it is 0.1-3 mm.
The average particle size is preferably 0.075 to 5 mm, more preferably 0.075 to 1.0 mm.

  In order to adsorb chloride ions on the activated carbon, the activated carbon is brought into contact with hydrochloric acid, and then washed with water as necessary, so that the pH value of the activated carbon is 7.0 or less, preferably 6.0 or less, more preferably 5.0 or less. This can be done. The contact can cause the activated carbon to be adsorbed to the activated carbon by immersing the activated carbon in an aqueous hydrochloric acid solution having an appropriate concentration and amount, or circulating the aqueous solution through the activated carbon.

The concentration of hydrochloric acid to be contacted is not particularly limited, but 0.1 to 15% hydrochloric acid is preferable. At this time, the activated carbon may be in an activated state or may be previously washed with water to remove the water-soluble inorganic component.
The contact between the activated carbon and hydrochloric acid is usually 5 to 80 ° C, preferably 5 to 35 ° C. The contact time is usually preferably from 10 minutes to 6 hours, but can be set to about 15 minutes to 2 hours by appropriately changing the concentration of hydrochloric acid.
After contact with hydrochloric acid, the activated carbon may be washed with water. Washing with water may be either a batch method or a continuous method, and hydrochloric acid that has not been adsorbed by this washing with water can be removed.
Thus, after making a activated carbon adsorb | suck a chloride ion, water is drained by a well-known method, and it dries.

The adsorption amount of chloride ions is usually 0.1-2 mass fraction%, preferably 0.1-1 mass fraction%, more preferably 0.1-0.5 mass fraction% with respect to the activated carbon. It is.
The adsorption amount of chloride ions can be measured by the following method.
Chloride ion adsorption amount measuring method Weigh 3 g of activated carbon into a 200 ml Erlenmeyer flask, add 100 ml of an aqueous sodium sulfate solution (containing 400 ppm of sulfate ions), gently boil for 5 minutes, cool, and then cool down to a pore size of 0.45 μm. Measure the chloride ion concentration in the filtrate filtered through the membrane filter and determine the total chloride ion content in the activated carbon. Separately, the chloride ion in the activated carbon is obtained according to the method of JIS K1474, and it is subtracted from the previously obtained total chloride ion content to calculate the chloride ion adsorption amount.

Addition of silver or a silver compound to activated carbon is performed by mixing a liquid containing colloidal silver or a water-soluble silver compound and activated carbon on which chloride ions are adsorbed, and then at 80 to 250 ° C., preferably 100 to 200 ° C., for example. Usually, it can be carried out by heating and drying for 0.1 to 20 hours, preferably 0.5 to 10 hours. The liquid is usually water, but may contain an organic solvent miscible with water.
Moreover, hydrogen chloride is volatilized by taking drying time as long as 5 hours or more, for example, and the pH value of activated carbon can also be raised.
The content of silver or silver compound is 0.1 to 5% by mass, preferably 0.1 to 3% by mass, and most preferably 0.1 to 2% in terms of silver with respect to the mass of the activated carbon. 0.0 mass fraction%.
Examples of the silver compound include water-soluble silver compounds such as silver nitrate, silver sulfate, and silver acetate.

  Unimpregnated activated carbon is mixed with the silver-impregnated activated carbon obtained here. The mixing of the silver impregnated activated carbon and the non-added activated carbon may be carried out by mixing the non-added product into the mixer before drying the silver-added product, or by mixing the dried silver-added charcoal and the non-added charcoal. Also good. This silver-impregnated coal and non-adhered coal are mixed so that the silver content is 0.05 to 2, preferably 0.05 to 1% by mass, based on the total amount of the water treatment adsorbent. The specific mixing ratio of the silver impregnated activated carbon and the non-impregnated activated carbon is preferably 1: 0.5 to 1:19, more preferably 1: 2 to 1:19, and more preferably 1: 3 to 1:19 in terms of mass ratio. preferable.

Moreover, in order to provide lead removal performance, an ion exchanger can be further mixed with the adsorbent, or can be immobilized on the surface of the adsorbent.
As the ion exchanger, known materials such as zeolite and ion exchange resin can be used.

Examples of the zeolite include sodium-substituted types of natural zeolite and synthetic zeolite such as chabazite, erionite, mordenite, and clinoptilolite. As the synthetic zeolite, for example, synthetic A type, X type, Y type zeolite shown in “Latest applied technology of zeolite”, CMC Co., Ltd., p.11 to p.13 can be used. As the type, 4A type, 5A type, and X type are preferably 13X type. In particular, the 13X type is more preferable. As described above, both natural zeolite and synthetic zeolite can be used as the zeolite. However, since natural zeolite has a lower ion exchange capacity than synthetic zeolite, it is necessary to use a larger amount. A finely pulverized one is preferred. These zeolites can also be used as a mixture of different types.
The particle size of the zeolite used may be the same as the particle size of the activated carbon when used in combination. When immobilized on the surface, it is usually 45 μm or less, preferably 20 μm or less, more preferably 5 μm or less. is there.
Examples of the ion exchange resin include “Pollution Prevention Technology and Law”, p. Examples include chelating resins such as iminodiacetic acid form, aldoxime form, and aminophosphoric acid form described in Japan Industrial Environment Management Association (1995).
The use ratio of the ion exchanger to the adsorbent is usually 5 to 40% by mass, preferably 10 to 30% by mass, more preferably 15 to 25% by mass, based on the total weight of the adsorbent. It is.

Immobilization of the ion exchanger to the activated carbon is preferably performed using a binder. A binder that does not harm the human body, does not block the pores of the activated carbon, and can immobilize the zeolite on the activated carbon surface by physical means such as heating may be used.
Specific examples include organic binders such as latex resins such as polyurethane, polystyrene, polyvinylidene chloride, and polyvinyl acetate, and inorganic binders such as water glass (sodium silicate) and silica alumina ceramics.
Water glass, silica, and alumina are particularly preferable because they serve as binders and have high affinity with zeolite. One kind of binder may be used, or a mixture of two or more kinds may be used.

The density | concentration of the binder solution to be used is 1-15 mass fraction% normally, Preferably, it is 3-10 mass fraction%. Moreover, the usage-amount (mass) of a binder is 0.5-25 mass% with respect to the total mass of a zeolite and activated carbon, Preferably it is 1-15 mass%.
The method for coating the surface of the activated carbon with the zeolite is not particularly limited, and a known method is used. For example, a method of immersing activated carbon in a binder solution containing zeolite powder and then drying (impregnation method), a method of spraying a binder solution containing zeolite powder on the activated carbon surface and drying (spraying method), or flowing activated carbon. For example, a method of adding a binder solution containing zeolite powder and drying it (flow method) can be used.

The adsorbent of the present invention is usually used by filling a cartridge. Passing water is normally SV = 1~4000hr about ^-1, conditions 100～4000Hr ^-1 are common, conditions 300～2000Hr ^-1 is more common. Moreover, although it is common to directly connect with a faucet or piping as a water purifier, it may pass to intermittent water supply as a filtration filter. In this case, the activated carbon is filled in the cartridge, the water poured into the water purifier main body passes through the cartridge, and the filtered water is stored in the container at the lower portion of the water purifier. SV = 50 to 500 hr ⁻¹ It will be about. Further, a part of the cartridge is generally immersed in the water in the container when the cartridge is full.
Since this adsorbent is also used as a filter for a water purifier, it is used for tap water.

  The adsorbent of the present invention not only can efficiently remove residual chlorine, trihalomethane and heavy metals in water, particularly tap water, but also can gradually elute silver ions into water at a stable concentration from the very beginning. When applied as a filter medium to a water purifier, silver ions can be released slowly over a long period of time.

  Hereinafter, the present invention will be specifically described with reference to Examples and Test Examples.

Commercially available coconut shell activated carbon (crushed charcoal) was sieved to have a particle size of 0.250 to 0.106 mm. 100 g of this activated carbon is put into a 1000 ml beaker, and an aqueous hydrochloric acid solution prepared by dissolving 7 ml of hydrochloric acid (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) in 500 ml of tap water is added and stirred for 1 hour in a room at 20 ° C. After discarding, 500 ml of water was further added and stirred for 1 hour. Drained and dried for 3 hours in an electric dryer maintained at 115 ± 5 ° C. The activated carbon had a pH value of 5.0, a chloride ion adsorption amount of 0.28 mass fraction%, and a BET specific surface area of 1080 m ² / g.
While stirring this activated carbon, a silver nitrate aqueous solution in which 0.314 g of silver nitrate (0.2 g as silver) was dissolved was sprayed in 70 ml of distilled water, and dried in an electric dryer maintained at 115 ± 5 ° C. for 3 hours. The silver impregnated activated carbon obtained here and the activated carbon before silver impregnation separately dried were mixed at a mass ratio of 1: 1. Got 1

  The silver adsorbent adsorbent No. was the same as in Example 1 except that the mass of silver nitrate was 0.471 g (0.3 g as silver), and the mixing ratio of the silver-impregnated activated carbon and the non-additive dry product was a mass ratio of 1: 2. . 2 was obtained.

  The silver adsorbent adsorbent No. was the same as in Example 1 except that the mass of silver nitrate was 0.785 g (0.5 g as silver), and the mixing ratio of the silver-impregnated activated carbon and the non-additive dry product was a mass ratio of 1: 4. . 3 was obtained.

  The silver adsorbent adsorbent No. was the same as in Example 1, except that the mass of silver nitrate was 1.57 g (1.0 g as silver), and the mixing ratio of the silver impregnated activated carbon and the non-additive dry product was a mass ratio of 1: 9. . 4 was obtained.

  The silver adsorbent adsorbent No. was the same as in Example 1 except that the mass of silver nitrate was 3.14 g (2.0 g as silver), and the mixing ratio of the silver-impregnated activated carbon and the non-additive dry product was a mass ratio of 1:19. . 5 was obtained.

  The mass of silver nitrate is 0.785 g (0.5 g as silver), the mixing ratio of the silver-impregnated activated carbon and the non-additive dry product is a mass ratio of 1: 3, and is preliminarily substituted with calcium, and the particle size is 0.250-0. The silver-adsorbed adsorbent No. 1 was prepared in the same manner as in Example 1 except that the zeolite 13X having a thickness of 106 mm was mixed so as to be 20% by mass of the whole. 6 was obtained.

  The silver-adsorbed adsorbent No. was the same as in Example 1 except that the mass of silver nitrate was 4.71 g (3.0 g as silver), and the mixing ratio of the silver-added activated carbon and the non-added dry product was a mass ratio of 1: 2. . 7 was obtained.

  The silver-adsorbed adsorbent No. was the same as in Example 1 except that the mass of silver nitrate was 4.71 g (3.0 g as silver), and the mixing ratio of the silver-added activated carbon and the non-added dry product was a mass ratio of 1: 9. . 8 was obtained.

  The silver-adsorbed adsorbent No. was the same as in Example 1 except that the mass of silver nitrate was 7.85 g (5.0 g as silver), and the mixing ratio of the silver-added activated carbon and the non-added dry product was 1: 2. . 9 was obtained.

  Implemented except that the hydrochloric acid used for washing was 9 ml, the mass of silver nitrate used for impregnation was 0.785 g (0.5 g as silver), and the mixing ratio of the silver-added activated carbon and the non-attached dry product was 1: 4. In the same manner as in Example 1, the silver adsorbent adsorbent No. 10 was obtained.

  The procedure was carried out except that the hydrochloric acid used for washing was 11 ml, the mass of silver nitrate used for impregnation was 1.57 g (1.0 g as silver), and the mixing ratio of the silver-added activated carbon and the non-added dry product was 1: 4. In the same manner as in Example 1, the silver adsorbent adsorbent No. 11 was obtained.

The silver-adsorbed adsorbent No. 1 was prepared in the same manner as in Example 11 except that the mixing ratio of the silver-impregnated activated carbon and the non-added dry product was set to 1: 9 by mass. 12 was obtained.
[Comparative Example 1]

Silver was the same as in Example 1 except that the mass of silver nitrate was 0.157 g (0.1 g as silver), and the mixing ratio of the silver-impregnated activated carbon and the non-additive dry product was a mass ratio of 1: 0 (not mixed). Adsorbent adsorbent No. 13 was obtained.
[Test Example 1]

The silver adsorbent adsorbent no. 1-13 were filled, and the silver density | concentration in the passage water when water-flowing by SV = 500hr < ^-1 > was measured for every predetermined time. Table 1 shows the silver elution amount 2 minutes after the start of water flow and the water flow until the silver concentration in the passing water reached 5 μg / L.

As is apparent from Table 1, when the adsorbents of Examples 1 to 12 were used, the silver concentration after 2 minutes of water flow was suppressed to 100 μg / L or less, whereas the activated carbon of Comparative Example 1 ( In the case of no mixing), silver was eluted at a high concentration of 116 μg / L.
In addition, when the adsorbents of Examples 1 to 12 were used, the water flow rate until the silver concentration reached 5 μg / L was significantly greater than that of the activated carbon of Comparative Example 1. This was an unexpected effect.
[Test Example 2]

The silver elution amount was measured in the same manner as in the water flow experiment 1 except that SV = 2000 hr ⁻¹ . Table 2 shows the silver elution amount 2 minutes after the start of water flow and the water flow until the silver concentration in the passing water reached 5 μg / L.

As can be seen from Table 2, even under different SV conditions, the adsorbents of Examples 1 to 12 of the present invention had a silver concentration after 2 minutes of water flow of 100 μg / L or less. In the activated carbon of Example 1 (without mixing), silver was eluted at a high concentration of 135 μg / L.
In addition, when the adsorbents of Examples 1 to 12 were used, the water flow rate until the silver concentration reached 5 μg / L was significantly greater than that of the activated carbon of Comparative Example 1.
[Test Example 3]

  The adsorbent No. 1 with silver adsorbent was placed in a pot-type water purifier cartridge with an adsorbent filling volume of 120 ml, which was installed in an air thermostat whose temperature was adjusted. 1 to 13 was charged, and water having various compositions adjusted in advance to the same temperature as the temperature of the air thermostat was poured into the 1 L water purifier body to obtain filtered water. The filtered water was discarded, and water prepared to the same composition was poured again to obtain filtered water. The filtered water was discarded again, and water prepared to the same composition was poured into it to obtain 3 L of filtered water. The filtrate was collected and the silver concentration was measured. Moreover, the same operation was repeated, water was sampled every 10 L, the silver concentration was measured, and the amount of water until it was below 10 μg / L was determined. The silver concentration measurement results are shown in Table 3.

As is apparent from Table 3, even in intermittent water flow, the adsorbents of Examples 1 to 12 of the present invention had the silver concentration in the 3 L filtered water suppressed to 100 μg / L or less. In the activated carbon of Comparative Example 1 (without mixing), silver was eluted at a high concentration of 210 μg / L.
Further, when the adsorbents of Examples 1 to 12 were used, the water flow rate until the silver concentration became 10 μg / L or less was significantly increased as compared with the activated carbon of Comparative Example 1. Unlike the case of continuous water flow, such a water purifier has a long contact time between activated carbon and water, and the activated carbon cartridge keeps in contact with water even after the filtration is completed. Was totally unexpected and surprising.

  The present invention not only can efficiently remove residual chlorine, trihalomethane and other volatile organic compounds and heavy metals in tap water, but also can be applied to an adsorbent that elutes silver ions gradually into water, particularly a water purifier. It is possible to provide an activated carbon-based adsorbent capable of stably releasing silver stably from the very beginning to a long period. Moreover, since it is possible to release silver stably and stably even when intermittently passing water, it is particularly useful as a filter medium for tap water purifiers.

Claims (5)

  Activated carbon in which silver or a silver compound is impregnated on activated carbon in which 0.1 to 2 mass% of chloride ions are adsorbed with respect to the activated carbon and mixed silver-free activated carbon in a mass ratio of 1: 0.5 to 1:19. An adsorbent for water treatment.   The silver content of the activated carbon impregnated with silver or a silver compound is 0.1 to 5% by mass, and the silver content relative to the total amount of the water treatment adsorbent is 0.05 to 2% by mass. The adsorbent for water treatment as described.   The water treatment adsorbent according to claim 1, which is a material for a water purifier.   The adsorbent for water treatment according to claim 1, which is a filter medium for a water purifier that is intermittently passed.   Activated carbon is treated with hydrochloric acid to adsorb chloride ions to activated carbon in an amount of 0.1 to 2% by mass, then mixed with silver or a silver compound-containing solution to add silver or silver compound, and silver is not added to this. The method for producing an adsorbent for water treatment according to any one of claims 1 to 4, wherein the activated carbon is mixed at a mass ratio of 1: 0.5 to 1:19.