Activated carbon and method for manufacturing activated carbon

Abstract

To provide activated carbon having a good balance of micropores, mesopores and macropores, and exhibiting high adsorption performance and decolorization performance.SOLUTION: The pore volume in the pore range with a diameter of less than 2 nm, calculated by the HK method from the nitrogen adsorption isotherm, is 0.32 to 0.50 mL / g; the pore volume in the pore range with a diameter of 50 to 1000 nm, calculated by the mercury intrusion method, is 0.17 to 0.25 mL / g; and the Rose Bengal adsorption performance is 100 to 240 mg / g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to activated carbon and a method for producing the same. [Background technology]

[0002] Activated carbon has advantages in terms of its specific surface area and adsorption speed, and is used in a wide range of applications, such as as an adsorbent to remove impurities and adjust the concentration of dissolved components.

[0003] Activated carbon typically has pores primarily called micropores, mesopores, and macropores. Micropores are pores primarily involved in the adsorption of substances with small molecular weights, such as gas components. Mesopores are pores primarily involved in the adsorption of substances with relatively large molecular weights, such as coloring substances. Macropores are pores that primarily function as transport paths for adsorbed substances.

[0004] Such conventional activated carbon and its manufacturing method are exemplified by the one disclosed in Patent Document 1 below. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7129428 Summary of the Invention [Problem to be solved by the invention]

[0006] Although it is desirable for activated carbon to have a balanced distribution of micropores, mesopores, and macropores, conventional activated carbon often exhibits a biased distribution of these pores. To reduce this bias, conventional activated carbon manufacturing methods require the separate preparation of a calcium element source and contacting it with the activated carbon raw material, leaving room for improvement in terms of operational efficiency. Furthermore, conventional activated carbons do not necessarily exhibit sufficient absorption and decolorization performance for, for example, 2-methylisoborneol (2-MIB), a substance that causes mold odors, and therefore also leave room for improvement in water treatment applications.

[0007] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide activated carbon having a balanced number of micropores, mesopores, and macropores and having high absorption and decolorization performance, and to provide a production method that enables such activated carbon to be produced more efficiently. [Means for solving the problem]

[0008] The activated carbon according to the present invention is characterized in that the pore volume in the range of pores with diameters of less than 2 nm, calculated from the nitrogen adsorption isotherm by the HK method, is 0.32 to 0.50 mL / g; The pore volume calculated by mercury intrusion porosimetry is 0.17 to 0.25 mL / g in the pore section having a diameter of 50 to 1000 nm, The rose bengal adsorption capacity is 100-240 mg / g.

[0009] According to this configuration, there is a good balance between pores (micropores) positioned in the pore range of less than 2 nm in diameter and pores (mesopores) positioned in the pore range of 2 to 50 nm in diameter. Furthermore, there is also a good balance between pores (macropores) positioned in the pore range of 50 to 10,000 nm in diameter, so that adsorbed substances such as gas components, 2-MIB, and coloring substances are efficiently adsorbed into the micropores and / or mesopores via the macropores.

[0010] The activated carbon according to the present invention preferably has an iodine adsorption capacity of 1000 to 1200 mg / g.

[0011] By having the above-mentioned iodine adsorption performance, the catalyst has a sufficient degree of activation and is capable of efficiently adsorbing an adsorbate.

[0012] In the activated carbon according to the present invention, it is preferable that the ratio of the pore volume in the pore section with a diameter of less than 2 nm among the pore volumes calculated from the nitrogen adsorption isotherm by the HK method to the pore volume in the pore section with a diameter of 2 to 50 nm among the pore volumes calculated from the nitrogen adsorption isotherm by the BJH method is 1.90 to 3.40.

[0013] By having the above pore volume ratio, micropores and mesopores are present in a balanced manner, making it possible to efficiently adsorb both small and large molecular sizes such as odors and colors.

[0014] The activated carbon according to the present invention preferably has a hardness of 90.0% or more.

[0015] By having the above hardness, it is possible to suppress the generation of fine powder when using activated carbon, thereby shortening the fine powder removal process due to the generation of fine powder and suppressing clogging of the filter installed after the adsorption tower.

[0016] In the activated carbon according to the present invention, the particles are preferably spherical in shape.

[0017] By having sufficient macropores, it is possible to increase the adsorption rate by acting as a transport path for the adsorbate. Also, because there are a good balance of micropores and mesopores, it is possible to remove both small and large molecular substances such as odors and color in a single activated carbon treatment. The spherical shape allows for better water permeability compared to other shapes and makes it easier to handle when backwashing.

[0018] The method for producing activated carbon according to the present invention is characterized in that, in the method for producing activated carbon including a carbonization step and an activation step, The method further includes a mixing step of mixing a coal-based material containing calcium oxide with the activated carbon raw material, and the coal-based material has an ash content of calcium oxide of 10% by weight or more and 30% by weight or less.

[0019] The present inventors discovered that using a coal-based material as part of the activated carbon raw material enables the production of activated carbon with a balanced distribution of micropores and mesopores, leading to the completion of the present invention. Specifically, this method includes a step of mixing a coal-based material containing at least calcium oxide with the activated carbon raw material. Unlike conventional manufacturing methods, this method eliminates the need for a separate calcium element supply source and contacting it with the activated carbon raw material, thereby improving operational efficiency. Furthermore, if the proportion of calcium oxide in the ash of the coal-based material is less than 10 wt%, mesopores may not fully develop or may take too long to develop, resulting in reduced yield and strength. Furthermore, if the proportion of calcium oxide in the ash exceeds 30 wt%, mesopores will develop excessively and the proportion of micropores will decrease. Excessive mesopore development may also result in reduced density and strength.

[0020] The method for producing activated carbon according to the present invention preferably further comprises a molding step of granulating the kneaded product obtained in the mixing step into spherical granules.

[0021] Conventionally, mesopores are developed by adding a calcium element source, but by using two different raw materials without adding these, it is possible to control the fine pore distribution simply by changing the blending ratio of the raw materials.In addition, the spherical shape allows for better water permeability than other shapes and makes it easier to handle when backwashing.

[0022] In the method for producing activated carbon according to the present invention, it is preferable that the weight ratio of the activated carbon raw material to the coal-based material is 1:9 to 9:1.

[0023] When the ratio of activated carbon raw material to coal-based material is less than 1 (when the ratio of coal-based material exceeds 9), mesopores become more developed and the ratio of micropores decreases. Alternatively, excessive mesopore development may result in a decrease in density and strength. When the ratio of activated carbon raw material to coal-based material is more than 9 (when the ratio of coal-based material is less than 1), mesopores may not develop sufficiently or may take a long time to develop, resulting in a decrease in yield and strength. DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the activated carbon and the method for producing the same according to the present invention will be described. (activated carbon) In the activated carbon according to the present invention, of the pore volume calculated from the nitrogen adsorption isotherm by the HK method, pores located in the pore section with a diameter of less than 2 nm are referred to as micropores. Furthermore, of the pore volume calculated from the nitrogen adsorption isotherm by the BJH method, pores located in the pore section with a diameter of 2 to 50 nm are referred to as mesopores. Furthermore, of the pore volume calculated by mercury intrusion porosimetry, pores located in the pore section with a diameter of 50 to 10,000 nm are referred to as macropores.

[0025] The activated carbon according to the present invention has a micropore volume of 0.32 to 0.50 mL / g, a macropore volume of 0.17 to 0.25 mL / g, and a Rose Bengal adsorption capacity of 100 to 240 mg / g.

[0026] The nitrogen adsorption isotherm in the present invention can be measured by a known measurement method, such as a method in which activated carbon is heated at a predetermined temperature for a predetermined time under a nitrogen atmosphere using a known specific surface area / pore distribution measuring device, and then the nitrogen adsorption isotherm is measured at the predetermined temperature.

[0027] The measurement by mercury intrusion porosimetry in the present invention can be performed using, for example, a known mercury intrusion pore volume measuring device.

[0028] The Rose Bengal adsorption performance in the present invention can be evaluated, for example, by measuring the amount of Rose Bengal adsorbed per unit weight of activated carbon according to the measurement method shown in "Measurement of Rose Bengal adsorption performance of activated carbon" in the following Examples.

[0029] The activated carbon according to the present invention preferably has an iodine adsorption capacity of 1000 to 1200 mg / g.

[0030] The iodine adsorption performance in the present invention can be evaluated by measuring the amount of iodine adsorbed per unit weight of activated carbon according to a known measurement method (for example, JIS K1474).

[0031] The activated carbon according to the present invention preferably has a ratio of micropores to mesopores (micropores / mesopores) of 1.90 to 3.40.

[0032] The hardness of the activated carbon according to the present invention is preferably 90.0% or more.

[0033] The hardness of the activated carbon in the present invention can be measured according to a known measurement method (for example, JIS K1474).

[0034] The particle shape of the activated carbon of the present invention is preferably spherical. Specifically, the sphericity of the activated carbon of the present invention is preferably 1.10 or less, more preferably 1.00 to 1.09, and even more preferably 1.02 to 1.08. The sphericity of the spherical activated carbon of the present invention is measured by calculating the longest diameter (a) / shortest diameter (b) from an image taken with a digital microscope.

[0035] (raw materials) Examples of activated carbon raw materials that can be used in the present invention include coal with a Button index of 1.0 or more, and carbonized materials such as coconut shells (palm shells, coconut shells, etc.), wood flour, and sawdust, but coal with a Button index of 1.0 or more is preferred. Using coal with a Button index of 1.0 or more makes it easier to obtain activated carbon that is strong and has excellent adsorption properties for odorous substances with relatively small molecular sizes.

[0036] The coal-based material that can be used in the present invention is not particularly limited and may be any of a wide variety of materials that are commonly used as raw materials for activated carbon. However, it is preferable that the proportion of calcium oxide contained in the ash contained in the coal-based material be 10% by weight or more and 30% by weight or less.

[0037] (Activated carbon manufacturing method) The method for producing activated carbon according to the present invention comprises the steps of: (1) a mixing step of mixing at least a coal-based material with an activated carbon raw material; (2) a molding step of granulating the kneaded material obtained in the mixing step into spherical granules; (3) a carbonization step of carbonizing the molded product obtained after the molding step to obtain a carbonized product; (4) an activation step of activating the carbonized material obtained after the carbonization step to obtain an activated material. The molding step may be carried out as needed.

[0038] (1)Mixing process In the mixing step, the activated carbon raw material and the coal-based material are first mixed to obtain a main raw material mixture. At this time, the ratio of the activated carbon raw material to the coal-based material is preferably 1:9 to 9:1. The median diameter of the main raw material mixture is preferably 5 to 150 μm, more preferably 6 to 90 μm, and even more preferably 7 to 50 μm.

[0039] If the median diameter of the main raw material mixture is 5 μm or greater, the proportion of materials that function as porous materials will be higher, and the mixture will be closer to a powder state than a slurry state, making it easier to mold. Furthermore, if the median diameter of the main raw material mixture is 150 μm or less, the contact efficiency with the binder (described below) will be increased, making it easier to solidify, making it easier to mold. Furthermore, once molded, it will be less likely to crack during the carbonization and activation processes and will have a hardness that can withstand manufacturing. The median diameter of the main raw material mixture can be measured using a laser diffraction / scattering particle size distribution analyzer. If the main raw material mixture needs to be pulverized, a roll mill, hammer mill, rotary mill, or other suitable device can be used.

[0040] Next, the main raw material mixture and the binder are kneaded. The main raw material mixture and the binder may be kneaded as they are, or may be kneaded in the presence of a solvent such as water or an organic solvent, as necessary. The binder used in the present invention is preferably a material other than a resin-based binder, and specific examples include carboxymethyl cellulose, hard pitch, soft pitch, and pulp waste liquor (main component is lignin sulfonate). These binders may be used alone or in combination of two or more.

[0041] The amounts of the main raw material mixture and binder used are 5 to 40 parts by weight, preferably 7 to 35 parts by weight, and more preferably 10 to 30 parts by weight, per 100 parts by weight of the main raw material mixture. When the amount of binder used is 5 parts by weight or more, the binder has a high caking power and is easy to mold. When the amount of binder used is 40 parts by weight or less, the viscosity does not increase easily and stickiness does not occur easily, making molding easy. Furthermore, since the adsorption performance of activated carbon is affected by the proportion of binder, satisfactory adsorption performance can be easily obtained by appropriately adjusting the amount of binder used.

[0042] When kneading is performed in the presence of a solvent, the main raw material mixture and a binder may be added to the solvent and kneaded, or the main raw material mixture may be added to the solvent and kneaded with the binder, or the binder may be added to the solvent and kneaded with the main raw material mixture. When kneading is performed in the presence of a solvent, the amount of solvent used is 5 to 40 parts by weight, preferably 7 to 30 parts by weight, and more preferably 10 to 20 parts by weight, per 100 parts by weight of the main raw material mixture.

[0043] In addition to the main raw material mixture, binder, and solvent, other additives such as oil may be added as needed during kneading. The amount of such additives used is such that the effects of the present invention are not impaired, for example, about 0 to 5 parts by weight per 100 parts by weight of the main raw material mixture.

[0044] The kneading method is not particularly limited, and kneading can be performed using a known kneading device, such as a paddle mixer, a kneader mixer, a screw mixer, etc. The kneading temperature is also not particularly limited, and can be, for example, 5 to 50°C, and the kneading time is also not particularly limited, and can be, for example, 5 to 60 minutes.

[0045] (2) Molding process In the molding step, the kneaded product obtained in the mixing step is used as the activated carbon raw material and molded using an extrusion granulator, basket granulator, flat die granulator, tumbling granulator, etc. When granulating the activated carbon raw material into spherical shapes, it is desirable to use a tumbling granulator or an extrusion granulator in combination with a rotating plate type granulator (Marmerizer), and it is preferable to use a tumbling granulator.

[0046] (3) Carbonization process In the carbonization step, the molded product obtained after the molding step is carbonized to obtain a carbonized product. The carbonization method is not particularly limited, and examples include a method of heating to 400°C or higher and 800°C or lower under oxygen-free conditions. The carbonization temperature may be appropriately set depending on the molded product used and the carbonization equipment, but is generally performed at 600 to 800°C. The carbonization time may be appropriately set depending on the molded product used and the carbonization equipment, but is preferably about 3 to 24 hours. The carbonization step can be performed using known manufacturing equipment such as a rotary kiln.

[0047] (4) Activation process In the activation step, the carbonized material obtained after the carbonization step is activated to obtain an activated product. The activation method can be any known method, and is not particularly limited. Examples of suitable activation methods include activation using activated gases such as steam, oxygen, and carbon dioxide, and activation using chemicals such as phosphoric acid and zinc chloride. Among these, steam activation is preferred from the viewpoint of obtaining activated carbon with a hardness suitable for use. The activation step is preferably carried out at a temperature of approximately 750 to 1050°C using known manufacturing equipment such as a rotary kiln or fluidized furnace. The activation time can be appropriately set depending on the conditions of the carbonized material used, the activation temperature, and the manufacturing equipment, but is preferably approximately 0.5 to 24 hours. [Example]

[0048] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0049] Example 1 Calcium-containing subbituminous coal and bituminous coal were pulverized to adjust the particle size distribution. The subbituminous coal and bituminous coal were mixed in a 5:5 ratio, and 100 parts by weight of the resulting powder was added to the mixture along with a predetermined amount of pitch and water. The mixture was then kneaded and formed into spheres using a tumbling granulator. The resulting carbonized product was then carbonized in a rotary electric furnace at 800°C for one hour and activated in a rotary electric furnace at 900°C for 100 minutes, yielding the activated carbon of Example 1.

[0050] Example 2 The activated carbon of Example 2 was obtained in the same manner as in Example 1, except that the activation treatment was carried out for 80 minutes in the activation step.

[0051] Example 3 Calcium-containing subbituminous coal and bituminous coal were pulverized to adjust the particle size distribution. The subbituminous coal and bituminous coal were then mixed in a 1:9 ratio, and 100 parts by weight of the resulting powder was added to the mixture along with a predetermined amount of pitch and water. The mixture was then molded into pellets using a die, carbonized in a rotary electric furnace at 800°C for one hour, and the resulting carbonized product was activated in a rotary electric furnace at 900°C for 50 minutes, yielding the activated carbon of Example 3.

[0052] Example 4 The activated carbon of Example 4 was obtained in the same manner as in Example 3, except that the ratio of calcium-containing subbituminous coal to bituminous coal was 9:1.

[0053] Example 5 The activated carbon of Example 5 was obtained in the same manner as in Example 3, except that the ratio of calcium-containing subbituminous coal to bituminous coal was 7:3 and the activation time was 60 minutes.

[0054] Example 6 The activated carbon of Example 6 was obtained in the same manner as in Example 3, except that the ratio of calcium-containing subbituminous coal to bituminous coal was 5:5 and the activation time was 60 minutes.

[0055] Example 7 The activated carbon of Example 7 was obtained in the same manner as in Example 3, except that the ratio of calcium-containing subbituminous coal to bituminous coal was 3:7 and the activation time was 60 minutes.

[0056] (Comparative Example 1) The carbonized material obtained by carbonizing coconut shells from the Philippines at a temperature of 600°C for approximately 2 hours was activated in a rotary electric furnace at 900°C for 250 minutes, washed with an aqueous hydrochloric acid solution and then with water, and sieved to obtain the activated carbon of Comparative Example 1.

[0057] (Comparative Example 2) Bituminous coal was pulverized to adjust the particle size distribution, and 100 parts by weight of the resulting powder was mixed with water and a predetermined amount of a calcium element supply source, and then molded into spheres using a tumbling granulator. The spheres were then carbonized in a rotary electric furnace at 800°C for one hour, and the resulting carbonized product was activated in a rotary electric furnace at 850°C for 100 minutes, thereby obtaining the activated carbon of Comparative Example 2.

[0058] The following various tests and evaluations were carried out on the activated carbons of Examples 1 to 7 and Comparative Examples 1 and 2. The results are shown in Table 1.

[0059] (Measurement of Rose Bengal adsorption capacity of activated carbon) The Rose Bengal adsorption capacity (mg / g) of the activated carbon was measured. Specifically, the activated carbon was first crushed to a volume-based cumulative distribution of 50% particle size (D50) of approximately 10.0 μm or less, and then dried in a constant temperature oven at 115°C for 3 hours. The activated carbon was then allowed to cool to room temperature in a desiccator using silica gel as a desiccant, yielding activated carbon after cooling.

[0060] Separately, 1.0 g of rose bengal reagent was added to 1 L of distilled water to prepare a 1000 mg / L rose bengal solution. The amount of rose bengal added to 1 L of distilled water was adjusted appropriately so that the absorbance of the resulting test solution, diluted 100 times, would be in the range of 0.95 to 1.05. The absorbance was measured at a wavelength of 549 nm using a glass cell with a 10 mm path length on a UV-visible spectrophotometer.

[0061] Next, an arbitrary mass of the activated carbon after cooling (an amount such that the residual concentration of Rose Bengal in the filtrate would be 2 mg / L according to the following formula (V)) was dispensed into a 100 mL Erlenmeyer flask with a stopper, and the activated carbon was added to 50 mL of the test solution prepared above. Using a thermostatic shaking bath, the mixture was shaken in a water bath at 25°C at a speed of 140 rpm for 24 hours to obtain a mixed solution. The mixed solution was then filtered using a membrane filter to obtain a filtrate.

[0062] The test solution was diluted to concentrations ranging from 0.5 to 10 mg / L and the absorbance of each solution was measured using a UV-visible spectrophotometer in a glass cell with a 10 mm optical path length, and a calibration curve was created. The absorbance of the resulting filtrate was measured, and the residual rose bengal concentration in the filtrate was calculated from the calibration curve. The calculated residual rose bengal concentration was used to calculate the amount of rose bengal adsorbed per gram of activated carbon using the following formula:

[0063] Amount of Rose Bengal adsorbed per 1 g of activated carbon (mg / g) = (1000 - residual concentration of Rose Bengal in the filtrate) × 50 / 1000 / mass of activated carbon (g) (I)

[0064] Next, a power approximation curve was created using the residual Rose Bengal concentration (mg / L) on the horizontal axis and the adsorption amount of Rose Bengal per gram of activated carbon (mg / g) on ​​the vertical axis. Using this power approximation formula, the adsorption amount of Rose Bengal (mg / g) at a residual Rose Bengal concentration of 2 mg / L was calculated, and this was taken as the Rose Bengal adsorption performance (mg / g).

[0065] (Measurement of iodine adsorption performance of activated carbon) The amount of iodine adsorption by activated carbon was measured in accordance with JIS K1474.

[0066] (Measurement of activated carbon hardness) The hardness of the activated carbon was measured in accordance with JIS K1474.

[0067] (Nitrogen adsorption / desorption isotherm measurement) Using a high-precision gas / vapor adsorption measuring device (Microtrac-Bel Corporation, BELSORP-max), the activated carbon was heated at 250°C for 3 hours under vacuum, and then the nitrogen adsorption / desorption isotherm of the porous material at 77K was measured.

[0068] (Measurement of micropore volume of activated carbon) The pore volume was calculated by applying the HK method to the nitrogen adsorption isotherm obtained by the above method. The pore volume in the range of less than 2 nm was taken as the micropore volume.

[0069] (micropore / mesopore ratio of activated carbon) The BJH method was applied to the nitrogen adsorption isotherm obtained by the above method to calculate the pore volume. The pore volume in the 2 to 50 nm range of the pore volume was taken as the mesopore volume. The micropore / mesopore ratio (micropore volume / mesopore volume) was calculated using the above micropore volume and mesopore volume.

[0070] (Measurement of macropore volume of activated carbon) The pore volume was calculated by measuring using a mercury intrusion pore volume measuring device (Shimadzu Corporation, AutoPore IV 9500). Of the pore volume, the pore volume in the range of 50 to 1000 nm was taken as the macropore volume.

[0071] (Measurement of 2-MIB value of activated carbon) The 2-MIB (2-methylisoborneol) value of the activated carbon was measured in accordance with JWWA K 113. A 2-MIB (2-methylisoborneol) value of 3 or less was evaluated as having good adsorption performance.

[0072] (Measurement of activated carbon's ability to decolorize sugar solutions) Brown sugar and distilled water were mixed in a 10:9 ratio and heated to approximately 70°C until dissolved (this was referred to as the raw sugar solution). Granulated sugar and distilled water were then mixed in a 10:6 ratio and heated to approximately 70°C until dissolved (this was referred to as the refined sugar solution). Distilled water, 10 w / v% sodium hydroxide solution, and hydrochloric acid were added to the raw sugar solution and refined sugar solution, respectively, and the sugar content was adjusted to 50% and the pH to 7.0±0.1 as measured with a sugar manufacturing refractometer. The adjusted raw sugar solution was diluted with the refined sugar solution, and the diluted solution was measured using a quartz cell (light path length 10 mm) with a UV-visible spectrophotometer. The difference in absorbance between the wavelengths of 420 nm and 750 nm was adjusted to 0.758±0.005 (this adjusted solution was used as the test solution).

[0073] The activated carbon to be measured was crushed to a volume-based cumulative distribution of 50% particle size (D50) of approximately 10.0 μm or less and dried in a constant-temperature oven at 115°C for 3 hours. It was then cooled to room temperature in a desiccator using silica gel as a desiccant, yielding the cooled activated carbon. 0.092 g of the cooled activated carbon was weighed into a 100 mL Erlenmeyer flask with a stopper, and 50 mL of the test solution was added. The mixture was shaken at 140 rpm in a water bath at 80°C ± 1°C for 1 hour to obtain a mixed solution (this was designated the test filtrate). The mixture was then filtered through Type 5C filter paper. Separately, the same procedure was repeated for the test solution without activated carbon, which served as the blank filtrate. The absorbance of the filtered solution was measured at wavelengths of 420 nm and 750 nm using a quartz cell (10 mm path length) on a UV-visible spectrophotometer. The sugar solution decolorization performance (%) was calculated using the following formula:

[0074] Sugar solution decolorization performance (%) = (1 - ((absorbance of test filtrate at 420 nm - absorbance of 750 nm) / (absorbance of blank filtrate at 420 nm - absorbance of 750 nm))) × 100

[0075] [Table 1]

[0076] As shown in Table 1 above, in Examples 1 to 7 of the present invention, compared to Comparative Examples 1 and 2, micropores, mesopores, and macropores were all present in a balanced manner, and higher adsorption performance was observed in terms of both 2-MIB value and sugar solution decolorization performance. [Industrial Applicability]

[0077] The activated carbon according to the present invention can be suitably used, for example, as an adsorbent for removing impurities or adjusting the concentration of dissolved components.

Claims

1. The pore volume in the section of pores with a diameter of less than 2 nm in the pore volume calculated by the HK method from the nitrogen adsorption isotherm is 0.32 to 0.50 mL / g, The pore volume in the pore section having a diameter of 50 to 1000 nm in the pore volume calculated by mercury intrusion porosimetry is 0.17 to 0.25 mL / g, Activated carbon having a rose bengal adsorption capacity of 100 to 240 mg / g.

2. 2. The activated carbon according to claim 1, having an iodine adsorption capacity of 1000 to 1200 mg / g.

3. 3. The activated carbon according to claim 1, wherein the ratio of the pore volume in the pore section with a diameter of less than 2 nm among the pore volumes calculated from the nitrogen adsorption isotherm by the HK method to the pore volume in the pore section with a diameter of 2 to 50 nm among the pore volumes calculated from the nitrogen adsorption isotherm by the BJH method is 1.90 to 3.

40.

4. 3. The activated carbon according to claim 1, which has a hardness of 90.0% or more.

5. 3. The activated carbon according to claim 1, wherein the particles are spherical.

6. A method for producing activated carbon including a carbonization step and an activation step, A method for producing activated carbon, further comprising a mixing step of mixing a coal-based material containing calcium oxide with the activated carbon raw material, wherein the coal-based material has an ash content of calcium oxide of 10% by weight or more and 30% by weight or less.

7. The method for producing activated carbon according to claim 6, further comprising a molding step of granulating the kneaded product obtained in the mixing step into spherical granules.

8. 7. The method for producing activated carbon according to claim 6, wherein the weight ratio of the activated carbon raw material to the coal-based material is 1:9 to 9:1.

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