Activated carbon

Abstract

This activated carbon has a total amount of surface functional groups of 2.50 mmol / g or more, an amount of functional groups derived from carboxylic acid metal salts of 0.30 mol / g or more, and a BET specific surface area of 300 m2 / g or more. The activated carbon has excellent metal removal performance.

Description

activated carbon

[0001] The present invention relates to activated carbon.

[0002] Activated carbon has excellent adsorption capacity for various pollutants, malodorous and harmful substances, and has been used as an adsorbent in various fields, both for domestic and industrial use. In recent years, in water purification applications, there has been a demand for delicious water free from chlorine odors, mold odors, etc., and various water purifiers using activated carbon have been proposed to meet this demand. On the other hand, there has been a recent increase in safety and hygiene concerns regarding water quality, such as trihalomethanes, environmental hormones, and heavy metals. To meet these demands, activated carbon alone is insufficient, and it has been necessary to use an adsorbent with a unique adsorption capacity in combination.

[0003] In particular, lead ions, among heavy metals, are suspected of having endocrine disrupting effects in water purification applications. In 2003, the lead ion concentration in drinking water was limited to 10 ppb or less, making it essential to develop effective water purification materials.

[0004] Under these circumstances, activated carbon with introduced functional groups is generally known as activated carbon with improved metal removal ability. For example, Patent Document 1 describes activated carbon to which a predetermined amount of acidic functional groups such as carboxylic acid has been introduced to impart metal removal ability. Meanwhile, Patent Document 2 describes activated carbon in which the specific surface area, the total amount of acidic functional groups, and the ratio of the total amount of hydroxyl groups and carboxyl groups to the total amount of acidic functional groups are each set within a predetermined range, thereby improving metal removal performance through a synergistic effect.

[0005] JP 2004-315243 A JP 2023-146963 A

[0006] However, in conventional activated carbons to which acidic functional groups have been introduced, as in Patent Documents 1 and 2, the functional groups are usually derived from carboxylic acids rather than salts, and therefore the ion exchange reaction between the hydrogen ions present in the carboxylic acids and the metal ions to be removed is difficult to occur, and the metal removal performance has not been sufficient.

[0007] The present invention is intended to solve the above-mentioned problems, and has an object to provide activated carbon having excellent metal removal performance.

[0008] The present inventors conducted extensive research to solve the above-mentioned problems and found that, since the metal removal performance of activated carbon is improved by substituting metal ions for hydrogen ions of carboxylic acids in activated carbon, activated carbon with excellent metal removal performance can be obtained by setting the total amount of surface functional groups, the amount of functional groups derived from carboxylic acid metal salts, and the BET specific surface area within specific ranges. Based on this finding, the present inventors conducted further research and completed the present invention. That is, the present invention includes the following features.

[0009] Item 1. The total amount of surface functional groups is 2.50 mmol / g or more, the amount of functional groups derived from carboxylic acid metal salts is 0.30 mmol / g or more, and the BET specific surface area is 300 m ２ / g or more.

[0010] Item 2. The activated carbon according to Item 1, wherein the metal constituting the functional group derived from the metal carboxylate is at least one metal selected from the group consisting of alkali metals and alkaline earth metals.

[0011] Item 3. The activated carbon according to Item 1 or 2, wherein the metal constituting the functional group derived from the metal carboxylate is at least one metal selected from the group consisting of sodium, potassium, calcium, and magnesium.

[0012] Item 4. The activated carbon according to any one of Items 1 to 3, wherein the amount of functional groups derived from the metal carboxylate is 10 mol % or more, with the total number of all functional groups being 100 mol %.

[0013] Item 5. The activated carbon according to any one of Items 1 to 4, which is granular activated carbon.

[0014] Item 6. The activated carbon according to any one of Items 1 to 5, having a median diameter of 1 to 130 μm.

[0015] Item 7. In the temperature programmed desorption spectroscopy (TPD spectroscopy), the activated carbon is subjected to CO precipitation at a temperature between 100 and 400°C. ２ Item 7. The activated carbon according to any one of Items 1 to 6, wherein the amount of generated is 200 μmol / g or more.

[0016] Item 8. The activated carbon according to any one of Items 1 to 7, having an oxygen content of 10% by mass or more.

[0017] Item 9. The activated carbon according to any one of Items 1 to 8, having an adsorption amount of free chlorine of 10 to 100 L / g as measured in accordance with the analytical method described in JIS S3201.

[0018] Item 10. The activated carbon according to any one of Items 1 to 9, which is a chemically activated activated carbon.

[0019] Item 11. The activated carbon according to any one of Items 1 to 10, having an average pore diameter of 2.30 nm or less.

[0020] Item 12. The activated carbon according to any one of Items 1 to 11, wherein the activated carbon has a decomposition onset temperature of 850°C or lower, as measured in thermogravimetric analysis in the atmosphere at a temperature increase rate of 10°C / min.

[0021] Item 13. A metal adsorbent containing the activated carbon according to any one of Items 1 to 12.

[0022] Item 14. The metal adsorbent according to Item 13, which adsorbs metal ions belonging to Groups 1 to 16 of the periodic table.

[0023] Item 15. A filter medium for a water purifier, comprising the metal adsorbent according to item 13 or 14.

[0024] Item 16. A filter for a water purifier, comprising the filter material for a water purifier according to Item 15.

[0025] Item 17. A cartridge for a water purifier comprising the filter for a water purifier according to Item 16.

[0026] Item 18. A water purifier comprising the water purifier cartridge according to Item 17.

[0027] Item 19. A system kitchen comprising the water purifier cartridge according to Item 18.

[0028] Item 20. A method for producing activated carbon according to any one of Items 1 to 12, comprising: (1) a step of oxidizing raw activated carbon; and (2) a step of washing the oxidized activated carbon obtained in the step (1) with a basic solution and adjusting the pH of the filtrate after washing to 4 or higher; and (3) a step of washing the activated carbon obtained in the step (2) that has been washed with the basic solution with water.

[0029] The activated carbon of the present invention can have excellent metal removal performance.

[0030] In this specification, the term "containing" is a concept that encompasses all of "comprise," "consist essentially of," and "consist only of."

[0031] In addition, in this specification, when a numerical range is expressed as "A to B," it means A or more and B or less.

[0032] 1. Activated Carbon The activated carbon of the present invention has a total surface functional group amount of 2.50 mmol / g or more, a functional group amount derived from a metal carboxylate of 0.30 mmol / g or more, and a BET specific surface area of ​​300 m ２ / g or more.

[0033] With this configuration, the hydrogen ions of the carboxylic acid in the activated carbon are replaced with metal ions, thereby improving the metal removal performance of the activated carbon.

[0034] Unlike inorganic porous carriers such as zeolite and alumina, activated carbon has a chaotic pore structure and therefore has sites that can adsorb metal species that are difficult to adsorb with other inorganic porous carriers.

[0035] The shape of the activated carbon is not particularly limited, and can be appropriately selected from, for example, powder, granules, pellets, honeycomb, etc. That is, any of powdered activated carbon, granular activated carbon, pelleted activated carbon, and honeycomb activated carbon can be used. Among these, the activated carbon of the present invention is preferably granular activated carbon, from the viewpoints of easily improving the metal (particularly lead) removal performance and preventing deterioration of the pore structure of the activated carbon.

[0036] As the activated carbon (primary carbon), various activated carbons can be used as long as they satisfy the above-mentioned conditions. Examples include activated carbons made from plant-based or fossil-based raw materials such as wood, wood flour (sawdust, etc.), bamboo, fruit shells (coconut shells, etc.), pulp manufacturing by-products, bagasse, blackstrap molasses, graphite, coal (peat, lignite, brown coal, bituminous coal, etc.), anthracite, coal pitch, petroleum (particularly petroleum distillation residue components), petroleum pitch, coke, and coal tar; various synthetic resins such as phenolic resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin, celluloid, epoxy resin, polyurethane resin, polyester resin, acrylic resin (polyacrylonitrile (PAN), etc.), and polyamide resin; synthetic rubbers such as polybutylene, polybutadiene, and polychloroprene; polysaccharides such as cellulose and regenerated cellulose; other synthetic wood; and synthetic pulp. Among these, from the viewpoints of easily improving the metal (particularly lead) removal performance and preventing deterioration of the pore structure of the activated carbon, plant-based activated carbon, coal-based activated carbon, synthetic resin-derived activated carbon, polysaccharide-derived activated carbon, etc. are preferred, coconut shell activated carbon, sawdust activated carbon, coal-based activated carbon, phenol-based activated carbon, polyacrylonitrile (PAN)-based activated carbon, cellulose-based activated carbon, etc. are more preferred, and coconut shell activated carbon is even more preferred. These activated carbons can be used alone or in combination of two or more types.

[0037] Activated carbon (raw carbon) can be obtained by carbonizing or infusibilizing these raw materials as necessary, followed by an activation treatment. The carbonization method, infusibilization method, and activation treatment method are not particularly limited, and conventional methods can be used. For example, the activation treatment can be performed using a gas activation method (gas-activated activated carbon) in which the carbon raw material (or its carbonized or infusibilized product) is heat-treated in an activation gas (water vapor, carbon dioxide, etc.) at about 500 to 1000°C; or a chemical activation method (chemically activated activated carbon) in which the carbon raw material (or its carbonized or infusibilized product) is mixed with an activator (phosphoric acid, zinc chloride, potassium hydroxide, sodium hydroxide, etc.) and heat-treated at about 300 to 800°C. Various commercially available activated carbons can also be used.

[0038] The activated carbon of the present invention can be obtained by subjecting these activated carbons (primary carbons) to, for example, the treatment shown in the production method described below.

[0039] Activated carbon usually has acidic groups present on its surface. The type of acidic group on the surface of activated carbon varies depending on the activated carbon, but the activated carbon of the present invention has a total surface functional group amount (particularly, a total surface acidic functional group amount) of 2.50 mmol / g or more, preferably 2.70 to 9.00 mmol / g, and more preferably 2.80 to 8.00 mmol / g. If the total surface functional group amount (particularly, a total surface acidic functional group amount) is less than 2.50 mmol / g, the activated carbon will be less likely to adsorb metals (particularly lead) and will have poor metal (particularly lead) removal performance. The total surface functional group amount (particularly, a total surface acidic functional group amount) of the activated carbon of the present invention is measured by acid-base neutralization titration (Boehm method).

[0040] As described above, the types of acidic groups on the surface of activated carbon vary depending on the activated carbon. However, in the activated carbon of the present invention, the metal removal performance of the activated carbon is improved by replacing the hydrogen ions of the carboxylic acid in the activated carbon with metal ions. Therefore, the amount of functional groups derived from the metal carboxylate is 0.30 mmol / g or more, preferably 0.35 to 5.00 mmol / g, more preferably 0.45 to 4.00 mmol / g, and particularly preferably 0.60 to 3.50 mmol / g. If the amount of functional groups derived from the metal carboxylate is less than 0.30 mmol / g, the metal (especially lead) is less adsorbed and the metal (especially lead) removal performance is inferior. Furthermore, from the viewpoint of preventing deterioration of the pore structure of the activated carbon, it is preferable that the amount of functional groups derived from the metal carboxylate is not excessively large. The amount of functional groups derived from the metal carboxylate in the activated carbon of the present invention is measured by acid-base neutralization titration (Boehm method).

[0041] In the activated carbon of the present invention, the metal species constituting the metal salt as the functional group derived from the carboxylate metal salt on the surface is not particularly limited, but examples thereof include alkali metals (sodium, potassium, etc.) and alkaline earth metals (calcium, magnesium, etc.). These metal species may be contained alone or in combination of two or more. That is, the surface of the activated carbon of the present invention may contain -COONa, -COOK, -(COO) ２ Ca, -(COO)２ It may contain one or more groups containing Mg or the like.

[0042] As described above, the types of acidic groups on the surface of activated carbon vary depending on the activated carbon. However, in the activated carbon of the present invention, the metal removal performance of the activated carbon is improved by replacing the hydrogen ions of the carboxylic acid in the activated carbon with metal ions, so the amount of functional groups derived from carboxylic acids is preferably small. Therefore, in the activated carbon of the present invention, the amount of functional groups derived from carboxylic acids is preferably 1.00 mmol / g or less, more preferably 0 to 0.95 mmol / g, and even more preferably 0 to 0.90 mmol / g. The amount of functional groups derived from carboxylic acids can be even smaller, 0 to 0.20 mmol / g, and particularly 0 to 0.10 mmol / g. The amount of functional groups derived from carboxylic acids in the activated carbon of the present invention is measured by acid-base neutralization titration (Boehm method).

[0043] As described above, the types of acidic groups on the surface of activated carbon vary depending on the activated carbon. However, in the activated carbon of the present invention, the metal removal performance of the activated carbon is improved by replacing the hydrogen ions of carboxylic acids in the activated carbon with metal ions. Therefore, it is preferable that the amount of functional groups derived from metal carboxylates among the functional groups possessed by the activated carbon of the present invention is large. Therefore, the amount of functional groups derived from metal carboxylates, where the total number of all functional groups is 100 mol%, is preferably 10 mol% or more, more preferably 14 to 60 mol%, and even more preferably 16 to 50 mol%. The amount of functional groups derived from metal carboxylates among the functional groups possessed by the activated carbon of the present invention is calculated from the amount of all surface functional groups and the amount of functional groups derived from metal carboxylates.

[0044] The method for analyzing the functional groups in the activated carbon of the present invention will be described below.

[0045] The amount of acidic functional groups on the surface of activated carbon can usually be determined by acid-base neutralization titration (Boehm method) to determine the amount of quinone groups, carboxyl groups, lactone groups, phenolic hydroxyl groups, etc. present on the surface. This acid-base neutralization titration method is a method in which various alkalis are added to activated carbon to cause a reaction, and the concentration of the alkali after the reaction is back-titrated with an acid to quantify the amount of acidic functional groups present on the surface of the activated carbon. In this case, due to differences in acidity, alkali metal ethoxides (sodium ethoxide, etc.) react with carboxyl groups, lactone groups, phenolic hydroxyl groups, quinone groups, etc., alkali metal hydroxides (sodium hydroxide, etc.) react with carboxyl groups, lactone groups, phenolic hydroxyl groups, etc., alkali metal carbonates (sodium carbonate, etc.) react with carboxyl groups, lactone groups, etc., and alkali metal bicarbonates (sodium bicarbonate, etc.) react with carboxyl groups, etc. By utilizing these differences, the amount of each acidic functional group can be separately quantified, and the amount of all surface functional groups (particularly the amount of all surface acidic functional groups) can also be quantified.

[0046] However, this acid-base neutralization titration method (Boehm method) cannot separately quantify groups derived from carboxylic acids and groups derived from metal carboxylates. Therefore, in the present invention, the amount of functional groups derived from metal carboxylates is calculated from the difference between the amount of carboxylic acid determined by titration for activated carbon after washing with an alkaline aqueous solution and the amount of carboxylic acid determined by titration for activated carbon before washing with an alkaline aqueous solution.

[0047] The BET specific surface area of ​​the activated carbon of the present invention is 300 m ２ / g or more, preferably 400 to 3500m ２ / g, more preferably 500 to 2000m ２ / g, more preferably 700 to 1500m ２ / g. BET specific surface area is 300 m ２ If the specific surface area is less than 1 / g, it is difficult to adsorb metals (especially lead), and the performance of removing metals (especially lead) is poor. The BET specific surface area of ​​activated carbon is measured by the BET method.

[0048] The median diameter of the activated carbon of the present invention is not particularly limited, but is preferably 1 to 130 μm, more preferably 5 to 100 μm, and even more preferably 10 to 75 μm, from the viewpoints of easily improving the metal (particularly lead) removal performance and preventing deterioration of the pore structure of the activated carbon. The median diameter of the activated carbon is calculated from the particle size distribution obtained by a laser diffraction / scattering method.

[0049] CO between 100 and 400°C ２ The amount of CO generated depends on the functional group derived from the metal carboxylate imparted to the activated carbon. In the activated carbon of the present invention, the metal (particularly lead) removal performance is easily improved and the pore structure of the activated carbon is less likely to deteriorate. Therefore, in the activated carbon of the present invention, the amount of CO generated depends on the functional group derived from the metal carboxylate imparted to the activated carbon. In ... ２ The amount of CO generated is preferably 200 μmol / g or more, more preferably 300 to 4000 μmol / g, even more preferably 500 to 3000 μmol / g, and particularly preferably 1000 to 3000 μmol / g. ２ The amount of generated is measured by a mass spectrometer.

[0050] The oxygen content of the activated carbon of the present invention is not particularly limited, but from the viewpoints of easily improving the metal (particularly lead) removal performance and preventing deterioration of the pore structure of the activated carbon, it is preferably 10% by mass or more, more preferably 11 to 25% by mass, and even more preferably 12 to 20% by mass, based on 100% by mass of the total amount of activated carbon. The oxygen content of the activated carbon is measured by energy dispersive X-ray spectroscopy.

[0051] The adsorption amount of free chlorine of the activated carbon of the present invention is not particularly limited, but from the viewpoints of easily improving the metal (particularly lead) removal performance and preventing deterioration of the pore structure of the activated carbon, it is preferably 10 to 100 L / g, more preferably 20 to 80 L / g, and even more preferably 40 to 60 L / g. The adsorption amount of free chlorine of the activated carbon is measured in accordance with the analytical method described in JIS S3201.

[0052] The average pore diameter of the activated carbon of the present invention is not particularly limited, but from the viewpoints of easily improving the metal (particularly lead) removal performance and preventing deterioration of the pore structure of the activated carbon, it is preferably 2.30 nm or less, more preferably 1.60 to 2.20 nm, and even more preferably 1.70 to 2.10 nm. The average pore diameter of the activated carbon is measured by a nitrogen adsorption method.

[0053] Generally, the higher the activation temperature during production of activated carbon, the more developed the hexagonal network structure of the activated carbon becomes, and the fewer the number of highly reactive edge sites. In the activated carbon of the present invention, since the sites where functional groups are introduced are edge sites, it is preferable to select activated carbon with many edge sites and a developed pore structure. From this perspective, the decomposition onset temperature measured by thermogravimetric analysis (TGA) in air at a temperature rise rate of 10°C / min is preferably 850°C or lower, more preferably 300 to 800°C, and even more preferably 400 to 700°C.

[0054] 2. Method for Producing Activated Carbon The method for producing activated carbon of the present invention is not particularly limited, but can be, for example, produced by a method comprising: (1) a step of oxidizing raw activated carbon; and (2) a step of washing the oxidized activated carbon obtained in the step (1) with a basic solution and adjusting the pH of the filtrate after washing to 4 or higher. (3) a step of washing the activated carbon obtained in the step (2) that has been washed with the basic solution.

[0055] (2-1) Step (1) The oxidation treatment that can be used in step (1) is not particularly limited, and oxidizing agents such as nitric acid, sulfuric acid, hydrogen peroxide, ammonium peroxydisulfide, sodium peroxodisulfate, and ozone can be used. Alternatively, heat treatment in air under an oxygen gas atmosphere or oxidation treatment using oxygen plasma and ultraviolet rays can be performed. These oxidation treatments can be performed alone or in combination of two or more. In particular, when hydrogen peroxide is used as the oxidizing agent, it is preferable to use it in combination with nitric acid, sulfuric acid, ammonium peroxydisulfide, sodium peroxodisulfate, or the like. Among these, from the viewpoint of mass production, it is preferable to use an oxidizing agent.

[0056] Here, the amount of the oxidizing agent used is preferably 5 to 50 parts by mass, and more preferably 10 to 30 parts by mass, per 100 parts by mass of activated carbon, from the viewpoints of easily increasing the amount of functional groups derived from the metal carboxylate, less likely to reduce the specific surface area, and less likely to cause deterioration of the pore structure.

[0057] The reaction temperature in step (1) is not particularly limited and can be adjusted appropriately depending on the oxidizing power of the oxidizing agent. However, from the viewpoints of easily increasing the amount of functional groups derived from the metal carboxylate, being less likely to reduce the specific surface area, and being less likely to cause deterioration of the pore structure, the reaction temperature is preferably 50 to 100°C, and more preferably 70 to 90°C.

[0058] The reaction temperature in step (1) is not particularly limited, and can be set to a time sufficient to sufficiently oxidize the starting activated carbon and to sufficiently increase the total amount of surface functional groups (particularly the total amount of surface acidic functional groups), but can be, for example, 10 minutes to 6 hours, preferably 30 minutes to 3 hours.

[0059] (2-2) Step (2) In step (2), washing with a base containing an alkali metal, alkaline earth metal, or the like (an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide; an alkaline earth metal hydroxide such as calcium hydroxide or magnesium hydroxide, or the like) as the base contained in the basic solution converts the carboxylic acid-derived group introduced by the oxidation in step (1) into a carboxylic acid metal salt-derived group, thereby facilitating an increase in the amount of carboxylic acid metal salt-derived functional group. Note that in step (1), when the oxidizing agent contains an alkali metal, alkaline earth metal, or the like, it is also possible to introduce a carboxylic acid metal salt-derived group in step (1), and therefore it is also possible to use a base (ammonia, etc.) that does not contain an alkali metal, alkaline earth metal, or the like.

[0060] In this case, the degree of washing with the basic solution is adjusted so that the pH of the filtrate after washing is 4 or higher, preferably 5 to 10, and more preferably 6 to 9. In this case, if the pH of the filtrate after washing is less than 3, the amount of functional groups derived from the metal carboxylate is insufficient, and the performance of removing metals (particularly lead) is poor.

[0061] (2-3) Step (3) Washing with water can be carried out by a conventional method, which can remove the oxidizing agent and basic solution remaining in the pores, and the products formed by the reaction between the oxidizing agent and the basic solution, as well as metals contained in the activated carbon and foreign matter attached to the surface.

[0062] Thereafter, if necessary, the activated carbon of the present invention can be obtained by drying it by a conventional method.

[0063] 3. Uses of Activated Carbon As described above, the activated carbon of the present invention is particularly useful as a metal adsorbent because of its excellent metal removal performance. Metals that can be removed by the activated carbon of the present invention are not particularly limited, but examples include metal ions belonging to Groups 1 to 16 of the periodic table, such as lead, mercury, cadmium, copper, arsenic, zinc, selenium, nickel, manganese, chromium, iron, barium, and aluminum, preferably metal ions belonging to Groups 6 to 16 of the periodic table, and preferably metal ions belonging to Groups 10 to 15 of the periodic table.

[0064] As described above, the adsorbent of the present invention is useful as an adsorbent for metals such as lead, and can therefore be used as a filter material for water purifiers. In this case, the activated carbon of the present invention can be filled into a cartridge case as is or as a filter-shaped water purifier filter, or the activated carbon of the present invention can be added to a desired binder and molded to obtain the water purifier cartridge of the present invention. Either a dry molding method or a wet molding method can be used as a molding method for producing the water purifier cartridge of the present invention.

[0065] When a dry molding method is employed, the composition containing the activated carbon of the present invention and a thermoplastic resin is preferably molded into a hollow cylindrical or disc shape. More specifically, the composition containing the activated carbon of the present invention and a thermoplastic resin is preferably placed in a mold made of aluminum or the like as needed, and heated to mold into a hollow cylindrical or disc shape.

[0066] Examples of usable thermoplastic resins include polyethylene, polypropylene, polystyrene, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene-styrene copolymer resin, polyethylene terephthalate, polybutylene terephthalate, ethylene acrylic resin, polymethyl methacrylate, nylon, mesophase pitch, and hydrophilic resins (e.g., polyvinyl alcohol resin, ethylene-vinyl alcohol resin, etc.). The content of the thermoplastic resin is not particularly limited. Specifically, from the viewpoint of the strength and adsorption properties of the molded body, the content is preferably 5 to 20 parts by mass, and more preferably 8 to 18 parts by mass, per 100 parts by mass of the activated carbon of the present invention.

[0067] When a wet molding method is employed, it is preferable that the composition containing the activated carbon of the present invention and the fibrous binder be molded into a hollow cylindrical or disc shape. More specifically, it is preferable that the composition containing the activated carbon of the present invention and the fibrous binder be dispersed in water to prepare a slurry, and then molded into a hollow cylindrical or disc shape while suctioning the slurry as necessary.

[0068] The fibrous binder is not particularly limited as long as it can entangle and shape the fibrous activated carbon and powdered activated carbon by fibrillation, and a wide range of materials, both synthetic and natural, can be used. Examples of such fibrous binders include acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, cellulose fibers, nylon fibers, and aramid fibers.

[0069] The shape of the fibrous binder is not particularly limited, and from the viewpoint of the strength of the molded product and workability, the average fiber length is preferably 0.5 to 4 mm, more preferably 0.7 to 2 mm.

[0070] The content of the fibrous binder is not particularly limited. Specifically, from the viewpoint of the strength and adsorption characteristics of the molded body, the content is preferably 2 to 15 parts by mass, more preferably 5 to 10 parts by mass, per 100 parts by mass of the activated carbon for a water purifier of the present invention.

[0071] When filling the cartridge with the activated carbon of the present invention, it is possible to fill it with ordinary activated carbon. It is also possible to fill it with zeolite, titanosilicate, etc., which can adsorb and remove soluble lead, or an adsorbent containing silver ions and / or silver compounds, which can impart antibacterial properties. In this case, the mass of the activated carbon of the present invention relative to the total amount of activated carbon filled is preferably 50% by mass or more (50 to 100% by mass), more preferably 70% by mass or more (70 to 100% by mass), and even more preferably 80% by mass or more (80 to 100% by mass).

[0072] The method for molding the composition into a hollow cylindrical or disc shape is not particularly limited and can be performed according to a conventional method. The size of the resulting hollow cylindrical or disc-shaped molded article is not particularly limited and can be set to a size corresponding to the cartridge to be filled.

[0073] Furthermore, by employing the above-described water purifier cartridge of the present invention, it is possible to make a water purifier in a conventional manner, and it is also possible to make a system kit having a conventional configuration other than the water purifier.

[0074] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0075] The phosphoric acid activated carbon was phosphoric acid activated carbon (manufactured by Jacobi Carbons; BET specific surface area: 2445 m ２ The coconut shell activated carbon used was coconut shell activated carbon (Jacobi Carbons; steam activated; BET specific surface area: 1093 m). ２ / g: pore diameter 1.7 nm), classified coconut shell activated carbon, or coconut shell activated carbon pulverized by a roll mill was used. Furthermore, as the zinc chloride activated carbon, commercially available zinc chloride activated carbon (Carborafine manufactured by Osaka Gas Chemicals Co., Ltd.; BET specific surface area 1497 m) was used. ２ / g: pore diameter 3.4 nm) was used.

[0076] Example 1 Phosphoric acid activated carbon (2420 m ２To 5 g of activated carbon (100 mL / g; median diameter 34 μm), 100 mL of water was added, and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 36 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 g of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 1, which was used as a lead adsorbent.

[0077] Example 2 Coconut shell activated carbon (1093 m ２ To 5 g of activated carbon (100 mL / g; median diameter 66 μm), 100 mL of water was added, and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 g of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 2, which was used as a lead adsorbent.

[0078] Example 3 Phosphoric acid activated carbon (2420 m ２ 300 mL of water was added to 60 g of activated carbon (particle size: 1.5 μm / g; median diameter: 34 μm), and while stirring, 46 mL of aqueous hydrogen peroxide (30% by mass) and 14 mL of nitric acid (60% by mass) were slowly added, and the temperature was then raised to 80°C, and the reaction was carried out for 90 minutes. This was followed by suction filtration, and the residue was washed with 420 g of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate was 8. After washing with water, the activated carbon was dried at 100°C to obtain the activated carbon of Example 3, which was used as a lead adsorbent.

[0079] Example 4 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of the activated carbon (calcium hydroxide, 0.115 wt. / g; median diameter 21 μm), and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then suction filtered, and the residue was washed with 530 mL of a 0.002% by mass aqueous calcium hydroxide solution so that the pH of the filtrate became 7. After washing with water, the activated carbon was dried at 100°C to obtain the activated carbon of Example 4, which was used as a lead adsorbent.

[0080] Example 5 Coconut shell activated carbon (1093 m ２100 mL of water was added to 5 g of the activated carbon (particle size: 1 / g; median diameter: 19 μm), and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 50 mL of a 1% by mass aqueous potassium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 5, which was used as a lead adsorbent.

[0081] Example 6 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of the activated carbon (particle size: 1 / g; median diameter: 19 μm), and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 g of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 7. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 6, which was used as a lead adsorbent.

[0082] Example 7 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of activated carbon (particle size: 1 / g; median diameter: 21 μm), and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then suction filtered, and the residue was washed with 49,000 mL of a 0.0001% by mass aqueous magnesium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 7, which was used as a lead adsorbent.

[0083] Example 8 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of activated carbon (particle size: 1 / g; median diameter: 4 μm), and the temperature was raised to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the reaction was allowed to proceed for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 g of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 8, which was used as a lead adsorbent.

[0084] Example 9 Coconut shell activated carbon (1093 m ２100 mL of water was added to 5 g of the activated carbon (calcium hydroxide, 0.11g / g; median diameter 111 μm), and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then suction filtered, and the residue was washed with 530 mL of a 0.002 mass% aqueous calcium hydroxide solution so that the pH of the filtrate became 7. After washing with water, the activated carbon was dried at 100°C to obtain the activated carbon of Example 9, which was used as a lead adsorbent.

[0085] Example 10 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of the activated carbon (particle size: 1 / g; median diameter: 4 μm), and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 32 mL of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 5. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 10, which was used as a lead adsorbent.

[0086] Example 11 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of (particle size: 1 / g; median diameter: 66 μm), and the mixture was heated to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then suction filtered, and the residue was washed with 35 mL of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 11, which was used as a lead adsorbent.

[0087] Example 12 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of activated carbon (calcium carbonate, stearate ...

[0088] Example 13 Coconut shell activated carbon (1093 m ２100 mL of water was added to 5 g of activated carbon (calcium carbonate, stearate, phosphate, phosphate buffer, phosphate buffer solution; median diameter 66 μm), and the mixture was heated to 80°C with stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 mL of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 11, which was used as a cadmium adsorbent.

[0089] Example 14 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of activated carbon (particle size: 1 / g; median diameter: 66 μm), and the temperature was raised to 80°C while stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the reaction was allowed to proceed for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 mL of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the activated carbon was dried at 100°C to obtain the activated carbon of Example 14, which was used as a barium adsorbent.

[0090] Example 15 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of activated carbon (particle size: 1 / g; median diameter: 66 μm), and the mixture was heated to 80°C with stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 mL of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 8. After washing with water, the mixture was dried at 100°C to obtain the activated carbon of Example 15, which was used as a mercury adsorbent.

[0091] Example 16 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of activated carbon (calcium carbonate, stearate, sintered body ...

[0092] Example 17 Coconut shell activated carbon (1093 m ２100 mL of water was added to 5 g of activated carbon (calcium carbonate, stearate, saturation ...

[0093] Comparative Example 1 Zinc chloride activated carbon (1700 m ２ / g; median diameter 28 μm) was used as the activated carbon of Comparative Example 1.

[0094] Comparative Example 2 Phosphoric acid activated carbon (2420 m ２ / g; median diameter 34 μm) was used as the activated carbon of Comparative Example 2.

[0095] Comparative Example 3 Zinc chloride activated carbon (1700 m ２ To 12 g of activated carbon (iron sulfate heptahydrate; median diameter 28 μm), 20 g of iron sulfate heptahydrate and 300 mL of water were added, and while stirring, 60 g of hydrogen peroxide solution (30% by mass) was slowly added. The mixture was then heated to 60°C and reacted for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 35 mL of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate was 8 or higher. After washing with water, the mixture was dried at 100°C to obtain activated carbon of Comparative Example 3.

[0096] Comparative Example 4 Coconut shell activated carbon (1093 m ２ 100 mL of water was added to 5 g of the cellulose acetate copolymer (1 / g; median diameter 22 μm), and the mixture was heated to 80°C with stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then suction filtered, and the filtrate was washed with water and dried at 100°C.

[0097] Comparative Example 5 Coconut shell activated carbon (1093 m ２100 mL of water was added to 5 g of activated carbon (particle size: 1 / g; median diameter: 4 μm), and the mixture was heated to 80°C with stirring. A solution of 20 g of sodium peroxodisulfate dissolved in 160 mL of water was slowly added, and the mixture was allowed to react for 90 minutes. The mixture was then subjected to suction filtration, and the residue was washed with 30 g of a 1% by mass aqueous sodium hydroxide solution so that the pH of the filtrate became 3. After washing with water, the mixture was dried at 100°C to obtain activated carbon of Comparative Example 6.

[0098] Comparative Example 6: Crushed and carbonized coconut shells were activated at a steam-carbon ratio of 0.9 to 1.3 and a temperature of 650 to 950°C for 18 to 20 hours, and then crushed and separated into pellets to produce activated carbon (1093 m ２ / g; median diameter 66 μm) was obtained and used as a lead adsorbent.

[0099] Comparative Example 7: Crushed and carbonized coconut shells were activated at a steam-carbon ratio of 0.9 to 1.3 and a temperature of 650 to 950°C for 18 to 20 hours, and then crushed and separated into pellets to produce activated carbon (1093 m ２ / g; median diameter 66 μm) was obtained and used as a copper adsorbent.

[0100] Comparative Example 8: Crushed and carbonized coconut shells were activated at a steam-carbon ratio of 0.9 to 1.3 and a temperature of 650 to 950°C for 18 to 20 hours, and then crushed and separated into pellets to produce activated carbon (1093 m ２ / g; median diameter 66 μm) was obtained and used as a cadmium adsorbent.

[0101] Comparative Example 9: Crushed and carbonized coconut shells were activated at a steam-carbon ratio of 0.9 to 1.3 and a temperature of 650 to 950°C for 18 to 20 hours, and then crushed and separated into pellets to produce activated carbon (1093 m ２ / g; median diameter 66 μm) was obtained and used as a barium adsorbent.

[0102] Comparative Example 10: Crushed and carbonized coconut shells were activated at a steam-carbon ratio of 0.9 to 1.3 and a temperature of 650 to 950°C for 18 to 20 hours, and then crushed and separated into pellets to produce activated carbon (1093 m ２ / g; median diameter 66 μm) was obtained and used as a mercury adsorbent.

[0103] Comparative Example 11: Crushed and carbonized coconut shells were activated at a steam-carbon ratio of 0.9 to 1.3 and a temperature of 650 to 950°C for 18 to 20 hours, and then crushed and separated into pellets to produce activated carbon (1093 m ２ / g; median diameter 66 μm) was obtained and used as an aluminum adsorbent.

[0104] Comparative Example 12: Crushed and carbonized coconut shells were activated at a steam-carbon ratio of 0.9 to 1.3 and a temperature of 650 to 950°C for 18 to 20 hours, and then crushed and separated into pellets to produce activated carbon (1093 m ２ / g; median diameter 66 μm) was obtained and used as a chromium adsorbent.

[0105] Test Example 1: Amount of Acidic Functional Groups The acidic functional groups on the surface of activated carbon were reacted with a 0.1 mol / L aqueous solution of sodium ethoxide. The alkaline aqueous solution obtained after the reaction was then back-titrated with hydrochloric acid to quantify the total amount of functional groups (total amount of acidic functional groups) present on the surface of the activated carbon.

[0106] The acidic functional groups on the surface of activated carbon were reacted with an aqueous sodium bicarbonate solution, and the resulting alkaline aqueous solution was then back-titrated with hydrochloric acid to quantify the amount of carboxyl groups present on the surface of the activated carbon.

[0107] In addition, 0.1 mol / L hydrochloric acid was reacted with the activated carbon to convert the metal salt of the carboxyl group on the surface into a carboxyl group. This activated carbon was washed with distilled water in an amount 100 times the weight of the activated carbon and dried at 115°C. The acidic functional groups on the surface of the dried activated carbon were reacted with an aqueous sodium bicarbonate solution. Next, the alkaline aqueous solution obtained after the reaction was back-titrated with 0.1 mol / L hydrochloric acid to quantify the carboxyl groups present on the activated carbon surface.

[0108] The amount of functional groups derived from the carboxylic acid metal salt was determined from the difference in the amount of carboxyl groups before and after the reaction with hydrochloric acid.

[0109] Test Example 2: BET specific surface area Activated carbon was heated at 115°C for 3 hours under a reduced pressure atmosphere, and then the nitrogen adsorption isotherm was measured, and the BET specific surface area was calculated by the BET method.

[0110] Test Example 3: Median diameter The particle size distribution was measured by a laser diffraction / scattering method using a laser particle size distribution analyzer (MT3300exII manufactured by Microtrac Bel) and the median diameter was calculated.

[0111] Test Example 4: Average pore diameter The average pore diameter was calculated from the nitrogen adsorption isotherm of the activated carbon.

[0112] Test Example 5: Amount of soluble lead adsorption (Examples 1 to 10 and Comparative Examples 1 to 5) A plurality of Erlenmeyer flasks were prepared, and each flask was individually charged with the activated carbon of each of the Examples and Comparative Examples, except for one Erlenmeyer flask. 50 mL of raw water prepared by dissolving lead nitrate in ultrapure water and adjusting the concentration to 5 mg / L was added, and the flasks were shaken for 20 hours while being kept at 20° C. Thereafter, the raw water in each Erlenmeyer flask was filtered, and 60% by mass nitric acid was added in an amount of 1% by mass relative to the filtrate. The concentration of soluble lead was analyzed using an atomic absorption spectrophotometer, and the amount of adsorption at which the concentration reached 1 ppb was determined from the adsorption isotherm.

[0113] Test Example 6: Lead adsorption amount (Example 11 and Comparative Example 6) A plurality of Erlenmeyer flasks were prepared, and each flask was individually charged with the activated carbon from the Examples and Comparative Examples, except for one Erlenmeyer flask. 1000 mL of raw water prepared by diluting a lead standard solution (1000 ppm) with ultrapure water to 500 μg / L was added, and the mixture was shaken at room temperature for 24 hours. Then, 10 mL of the raw water in each Erlenmeyer flask was collected and diluted with a diluent (70%-HNO ) for ICP analysis. ３ The concentration of lead was analyzed by ICP-OES, and the amount of adsorption when the concentration reached 100 ppb was confirmed from the adsorption isotherm.

[0114] Test Example 7: Copper adsorption amount (Example 12 and Comparative Example 7) A plurality of Erlenmeyer flasks were prepared, and activated carbons from the Examples and Comparative Examples were individually placed in each Erlenmeyer flask, except for one Erlenmeyer flask. 1000 mL of raw water prepared by diluting a copper standard solution (1000 ppm) with ultrapure water to 500 μg / L was added, and the mixture was shaken at room temperature for 24 hours. Then, 10 mL of raw water was sampled from each Erlenmeyer flask, and a dilution solution (70%-HNO ) for ICP analysis was added. ３ The copper concentration was analyzed by ICP-OES analysis, and the amount of adsorption when the concentration reached 100 ppb was confirmed from the adsorption isotherm.

[0115] Test Example 8: Cadmium adsorption amount (Example 13 and Comparative Example 8) A plurality of Erlenmeyer flasks were prepared, and activated carbons from the Examples and Comparative Examples were individually placed in each Erlenmeyer flask, except for one Erlenmeyer flask. 1000 mL of raw water prepared by diluting a cadmium standard solution (1000 ppm) with ultrapure water to 500 μg / L was added, and the mixture was shaken at room temperature for 24 hours. Then, 10 mL of the raw water in each Erlenmeyer flask was collected and diluted with a diluent (70%-HNO ) for ICP analysis. ３ The cadmium concentration was analyzed by ICP-OES analysis, and the amount of adsorption when the concentration reached 100 ppb was confirmed from the adsorption isotherm.

[0116] Test Example 9: Barium adsorption amount (Example 14 and Comparative Example 9) A plurality of Erlenmeyer flasks were prepared, and each of them was individually charged with the activated carbon of the Examples and Comparative Examples, except for one Erlenmeyer flask. 1000 mL of raw water prepared by diluting a barium standard solution (1000 ppm) with ultrapure water to 500 μg / L was added, and the mixture was shaken at room temperature for 24 hours. Then, 10 mL of the raw water in each Erlenmeyer flask was collected and diluted with a diluent (70%-HNO ) for ICP analysis. ３ The barium concentration was analyzed by ICP-OES analysis, and the amount of adsorption when the concentration reached 100 ppb was confirmed from the adsorption isotherm.

[0117] Test Example 10: Mercury Adsorption Amount (Example 15 and Comparative Example 10) A plurality of Erlenmeyer flasks were prepared, and activated carbons from the Examples and Comparative Examples were individually placed in each Erlenmeyer flask, except for one Erlenmeyer flask. 1000 mL of raw water prepared by diluting a mercury standard solution (1000 ppm) with ultrapure water to 500 μg / L was added, and the mixture was shaken at room temperature for 24 hours. Then, 10 mL of the raw water in each Erlenmeyer flask was collected and diluted with a diluent (70%-HNO ) for ICP analysis. ３ The mercury concentration was analyzed by ICP-OES analysis, and the amount of adsorption when the concentration reached 100 ppb was confirmed from the adsorption isotherm.

[0118] Test Example 11: Aluminum adsorption amount (Example 16 and Comparative Example 11) A plurality of Erlenmeyer flasks were prepared, and each of the Erlenmeyer flasks was individually charged with the activated carbon of the Examples and Comparative Examples, except for one Erlenmeyer flask. 1000 mL of raw water prepared by diluting an aluminum standard solution (1000 ppm) with ultrapure water to 500 μg / L was added, and the mixture was shaken at room temperature for 24 hours. Then, 10 mL of the raw water in each Erlenmeyer flask was collected and diluted with a diluent (70%-HNO ) for ICP analysis. ３ The aluminum concentration was analyzed by ICP-OES analysis, and the amount of adsorption when the concentration reached 100 ppb was confirmed from the adsorption isotherm.

[0119] Test Example 12: Chromium adsorption amount (Example 17 and Comparative Example 12) A plurality of Erlenmeyer flasks were prepared, and activated carbons from the Examples and Comparative Examples were individually placed in each Erlenmeyer flask, except for one Erlenmeyer flask. 1000 mL of raw water prepared by diluting a chromium standard solution (1000 ppm) with ultrapure water to 500 μg / L was added, and the mixture was shaken at room temperature for 24 hours. Then, 10 mL of the raw water in each Erlenmeyer flask was collected and diluted with a diluent (70%-HNO ) for ICP analysis. ３ The concentration of chromium was analyzed by ICP-OES analysis, and the amount of adsorption when the concentration reached 100 ppb was confirmed from the adsorption isotherm.

[0120] The results are shown in Tables 1 and 2.

[0121]

[0122]

Claims

1. The total amount of surface functional groups is 2.50 mmol / g or more, the amount of functional groups derived from carboxylic acid metal salts is 0.30 mmol / g or more, and the BET specific surface area is 300 m ２ / g or more.

2. The activated carbon according to claim 1, wherein the metal constituting the functional group derived from the metal carboxylate is at least one metal selected from the group consisting of alkali metals and alkaline earth metals.

3. The activated carbon according to claim 1 or 2, wherein the metal constituting the functional group derived from the metal carboxylate is at least one metal selected from the group consisting of sodium, potassium, calcium and magnesium.

4. The activated carbon according to any one of claims 1 to 3, wherein the amount of functional groups derived from the metal carboxylate is 10 mol % or more, with the total number of all functional groups being 100 mol %.

5. The activated carbon according to any one of claims 1 to 4, which is a granular activated carbon.

6. The activated carbon according to any one of claims 1 to 5, having a median diameter of 1 to 130 µm.

7. In the temperature programmed desorption analysis (TPD analysis), the CO ２ The activated carbon according to any one of claims 1 to 6, wherein the amount of generated carbon is 200 µmol / g or more.

8. The activated carbon according to any one of claims 1 to 7, having an oxygen content of 10% by mass or more.

9. The activated carbon according to any one of claims 1 to 8, which has an adsorption capacity of free chlorine of 10 to 100 L / g as measured in accordance with the analytical method described in JIS S3201.

10. The activated carbon according to any one of claims 1 to 9, which is a chemically activated activated carbon.

11. The activated carbon according to any one of claims 1 to 10, having an average pore diameter of 2.30 nm or less.

12. The activated carbon according to any one of claims 1 to 11, which has a decomposition initiation temperature of 850°C or lower, measured in thermogravimetric analysis in the atmosphere at a temperature increase rate of 10°C / min.

13. A metal adsorbent containing the activated carbon according to any one of claims 1 to 12.

14. The metal adsorbent according to claim 13, which adsorbs metal ions belonging to groups 1 to 16 of the periodic table.

15. A filter medium for a water purifier containing the metal adsorbent according to claim 13 or 14.

16. A water purifier filter containing the water purifier filter material according to claim 15.

17. A cartridge for a water purifier comprising the filter for a water purifier according to claim 16.

18. A water purifier comprising the water purifier cartridge according to claim 17.

19. A system kitchen comprising the water purifier cartridge according to claim 18.

20. A method for producing activated carbon according to any one of claims 1 to 12, comprising: (1) a step of oxidizing raw activated carbon; and (2) a step of washing the oxidized activated carbon obtained in step (1) with a basic solution and adjusting the pH of the filtrate after washing to 4 or higher; and (3) a step of washing the activated carbon obtained in step (2) that has been washed with the basic solution.

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