Activated carbon adsorbent

Abstract

[Problem] To provide an activated carbon adsorbent capable of maintaining the adsorption performance of a low-molecular compound at a high level even when a low-molecular compound and a high-molecular compound coexist. [Solution] Provided is an activated carbon adsorbent in which: the pore diameter peak (Wp) in terms of the pore volume, as calculated by a GCMC method based on the CO2 adsorption, is 0.52-0.70 nm; the pore volume (VSN) of subnanopores having a pore diameter of 1.0 nm or less, as calculated by the GCMC method, is 0.45-0.55 cm3 / g; and the pore volume (VME) of the pores having a pore diameter of 3-50 nm, as calculated by a DH method based on the N2 adsorption, is 0.01-1.00 cm3 / g; and the average pore diameter as measured by the BET method is 1.7-5.0 nm.

Description

Activated carbon adsorbent

[0001] The present invention relates to an activated carbon adsorbent having excellent adsorption performance for toxic substances.

[0002] Kidney disease and liver disease are known to cause encephalopathy, such as uremia and impaired consciousness, due to the accumulation of toxic substances in the blood. Orally administered adsorbents utilizing the adsorption properties of activated carbon have been developed as treatments for mild kidney and liver diseases. This type of activated carbon adsorbent is required to selectively adsorb substances to be removed, such as uremic toxins, while minimizing the adsorption of useful substances, such as enzymes, in the body.

[0003] Generally, enzymes are polymeric compounds with molecular weights of tens of thousands, while toxins are low-molecular-weight compounds with molecular weights of hundreds. Therefore, it is believed that highly selective adsorption can be achieved in activated carbon adsorbents by developing only the micropores that serve as adsorption sites for toxins. Therefore, activated carbon adsorbents that achieve both selective adsorption rates and indole adsorption rates by reducing the volumes of mesopores and macropores (see, for example, Patent Document 1) and activated carbon adsorbents that improve the adsorption performance of harmful substances in the presence of bile acids by reducing the volume of mesopores relative to the volume of micropores (see, for example, Patent Document 2) have been proposed.

[0004] In the case of the activated carbon adsorbent of Patent Document 1, when evaluating the selective adsorption, a common method is to conduct multiple single-component adsorption tests, such as contacting the activated carbon with toxins and enzymes in separate systems and measuring the adsorption rate of each substance, and evaluate the adsorption selectivity based on the performance evaluation of each test. However, in the internal environment in which the activated carbon adsorbent is actually used, it is thought that the adsorbent is affected by various macromolecular compounds, such as digestive enzymes, during the process of adsorbing the toxins, such as by inhibition of toxin adsorption. Therefore, it has been difficult to obtain an appropriate evaluation that corresponds to the adsorption phenomenon in the internal environment in which digestive enzymes and the like are present, using conventional performance evaluations based on single-component adsorption tests.

[0005] Furthermore, the activated carbon adsorbent of Patent Document 2 employs a method for evaluating the adsorption performance of toxic substances by a test in which indole is adsorbed in the presence of cholic acid, which is contained in large amounts in bile. However, since cholic acid, which coexists with indole, has an extremely small molecular weight compared to high-molecular compounds such as digestive enzymes, it cannot be said to be compatible with the internal environment in which digestive enzymes and the like are present, and it has been difficult to appropriately evaluate the adsorption phenomenon in the coexistence of high-molecular compounds such as digestive enzymes.

[0006] Therefore, the present inventors have conducted extensive research, assuming that the adsorbent will be used in an internal environment where digestive enzymes and the like are present, and have invented an activated carbon adsorbent that can maintain a high level of adsorption performance for low molecular weight compounds even in the coexistence of low molecular weight compounds that correspond to toxic substances and high molecular weight compounds that may inhibit toxin adsorption.

[0007] Patent No. 6386571 Patent No. 6306721

[0008] The present invention has been proposed in view of the above circumstances, and provides an activated carbon adsorbent that can maintain a high level of adsorption performance for low molecular weight compounds even in the coexistence of low molecular weight compounds and high molecular weight compounds.

[0009] That is, the first invention is ２ The peak of the pore diameter based on the pore volume calculated by the GCMC method based on adsorption (W ｐ ) is 0.52 to 0.70 nm, and the pore volume (V ＳＮ ) is 0.45 to 0.55 cm ３ / g, and N ２ The pore volume (V) of pores with a diameter of 3 to 50 nm calculated by the DH method based on adsorption ＭＥ ) is 0.01 to 1.00 cm ３ / g and an average pore diameter measured by the BET method of 1.7 to 5.0 nm.

[0010] The second invention is the first invention, wherein the pore volume (V ＭＥ ) to the pore volume of the sub-nanopores (V ＳＮ ) volume ratio (V ＳＮ／ＭＥ) is 3 to 50.

[0011]

[0012] The third invention is the first or second invention, wherein the hardness (H Ｄ３００ ) is 2.0 to 30.0N.

[0013] A fourth invention relates to the activated carbon adsorbent according to the first or second invention, wherein the activated carbon adsorbent is an orally administered therapeutic or preventive agent for kidney disease or liver disease.

[0014] A fifth aspect of the present invention relates to the activated carbon adsorbent of the third aspect, wherein the activated carbon adsorbent is an orally administered therapeutic or preventive agent for kidney disease or liver disease.

[0015] According to the activated carbon adsorbent of the first invention, CO ２ The peak of the pore diameter based on the pore volume calculated by the GCMC method based on adsorption (W ｐ ) is 0.52 to 0.70 nm, and the pore volume (V ＳＮ ) is 0.45 to 0.55 cm ３ / g, and N ２ The pore volume (V) of pores with a diameter of 3 to 50 nm calculated by the DH method based on adsorption ＭＥ ) is 0.01 to 1.00 cm ３ / g and the average pore diameter measured by the BET method is 1.7 to 5.0 nm, so that the adsorption performance for low molecular weight compounds can be maintained at a high level even in the coexistence of low molecular weight compounds and high molecular weight compounds.

[0016] According to the activated carbon adsorbent of the second invention, in the first invention, the pore volume (V ＭＥ ) to the pore volume of the sub-nanopores (V ＳＮ ) volume ratio (V ＳＮ／ＭＥ ) is 3 to 50, the decrease in the adsorption performance for toxic substances can be suppressed.

[0017] According to the activated carbon adsorbent of the third invention, the hardness (H ) of activated carbon particles having a particle diameter of 300 μm calculated from the average hardness of activated carbon particles having a diameter of 150 to 500 μm in the first or second invention is Ｄ３００ ) is 2.0 to 30.0 N, the shape of the activated carbon particles is maintained, and the decrease in adsorption performance can be suppressed.

[0018] According to the activated carbon adsorbent of the fourth invention, in the first or second invention, the activated carbon adsorbent is an orally administered therapeutic or preventive agent for kidney disease or liver disease, and therefore has a high effect of selectively adsorbing causative substances of kidney disease or liver disease, making it suitable as a therapeutic or preventive agent.

[0019] According to the activated carbon adsorbent of the fifth invention, in the third invention, the activated carbon adsorbent is an orally administered therapeutic or preventive agent for kidney disease or liver disease, and therefore has a high effect of selectively adsorbing causative substances of kidney disease or liver disease, making it suitable as a therapeutic or preventive agent.

[0020] 1A and 1B are conceptual diagrams of adsorption phenomena in an activated carbon adsorbent according to an embodiment of the present invention, and in a conventional activated carbon adsorbent.

[0021] The activated carbon adsorbent of the present invention has a pore diameter peak (W) of 100 μm to effectively adsorb low molecular weight compounds in an environment where low molecular weight compounds and high molecular weight compounds coexist, which is assumed to be used in an internal body environment where digestive enzymes and the like are present. ｐ ) and the pore volume of sub-nanopores with a pore diameter of 1.0 nm or less (V ＳＮ ) and the pore volume of pores with a diameter of 3 to 50 nm (V ＭＥ The physical properties are specified by the average pore diameter.

[0022] Activated carbon adsorbents can be suitably used as oral medications, for example, by molding them into tablets using activated carbon as an adsorbent and an additive as a binder. Orally administered activated carbon adsorbents are particularly used as therapeutic or preventive agents for kidney disease or liver disease. Specifically, activated carbon adsorbents are highly effective at selectively adsorbing causative substances of kidney disease or liver disease. Oral administration of activated carbon adsorbents allows the causative substances of the disease or chronic symptoms to be adsorbed and retained within the pores on their surface, and then excreted from the body, thereby suppressing the worsening of symptoms and improving the pathological condition. Furthermore, by taking activated carbon adsorbents in advance, the concentration of causative substances of disease or chronic symptoms in the body can be reduced. Therefore, activated carbon adsorbents are also considered effective as prophylactic agents for suppressing the worsening of symptoms in cases of congenital or acquired metabolic disorders or those at risk of such disorders.

[0023] Examples of renal diseases include chronic renal failure, acute renal failure, chronic pyelonephritis, acute pyelonephritis, chronic nephritis, acute nephritic syndrome, acute progressive nephritic syndrome, chronic nephritic syndrome, nephrotic syndrome, nephrosclerosis, interstitial nephritis, tubulopathy, lipoid nephrosis, diabetic nephropathy, renovascular hypertension, hypertension syndrome, secondary renal diseases associated with these primary diseases, pre-dialysis mild renal failure, etc. Examples of liver diseases include fulminant hepatitis, chronic hepatitis, viral hepatitis, alcoholic hepatitis, hepatic fibrosis, liver cirrhosis, liver cancer, autoimmune hepatitis, drug-induced allergic liver damage, primary biliary cirrhosis, tremors, encephalopathy, metabolic disorders, functional disorders, etc.

[0024] The raw material for the activated carbon adsorbent is preferably, for example, a resin carbonized from a phenolic resin. The resin carbonized from a phenolic resin can increase the ratio (volume ratio) of the sum of the mesopore volume to the sum of the micropore volume while increasing the activation and the specific surface area, which facilitates improving the adsorption performance of toxic substances. Examples of the phenolic resin include well-known types such as novolac type, resol type, and composite phenolic resins of both.

[0025] The phenolic resin activated carbon is preferably granular or spherical with an average particle size in the range of 20 to 1000 μm. If the average particle size of the activated carbon is too small, the activated carbon may become too dense when made into a tablet, resulting in poor disintegration. If the average particle size of the activated carbon is too large, the surface area where the activated carbon particles come into contact and bond with each other due to the additive as a binder increases, which may weaken the bonding strength and result in low tablet hardness.

[0026] In addition to phenolic resin, cellulose can also be used as the raw material for activated carbon adsorbents. When cellulose is used as the raw material, it is thought that by making activated carbon with many macropores, it is possible to suppress the decrease in adsorption performance inherent in activated carbon when it is made into a tablet form using additives.

[0027] Pore ​​diameter peak (W ｐ ) is CO ２ This is the maximum value of the pore diameter based on the pore volume calculated by the GCMC method based on adsorption. ３ / g) is the pore volume of smaller micropores (diameter 1.4 nm or less) calculated by measuring a carbon dioxide adsorption isotherm at 298 K and analyzing it by the GCMC method. The peak of the pore diameter based on the pore volume shifts toward larger pore diameters as the activation of the activated carbon progresses. A preferred pore diameter peak is 0.52 to 0.70 nm. If the pore diameter peak is too small, toxic substances may not be adsorbed sufficiently. If the pore diameter peak is too large, it suggests that activation has progressed excessively, and there is a risk of unnecessary adsorption of useful substances with large molecular weights, such as endogenous enzymes.

[0028] The pore volume (V) of subnanopores with a pore diameter of 1.0 nm or less ＳＮ ) is a value calculated by measuring a carbon dioxide adsorption isotherm at 298 K and analyzing it by the GCMC method. The pore volume of the sub-nanopores corresponds to an index of the adsorption performance of low molecular weight compounds, which are toxic substances. The preferred pore volume of the sub-nanopores is 0.45 to 0.55 cm ３ / g. If the pore volume of the subnanopores is too small, there is a risk that the adsorption performance of toxic substances will be insufficient. If the pore volume of the subnanopores exceeds a certain level, the subnanopores will associate with each other to form larger micropores of 1 nm or more, so an upper limit is appropriately specified.

[0029] Pore ​​volume (V) of pores with a diameter of 3 to 50 nm ＭＥ ) is N ２ This value is calculated by the DH method based on adsorption. This pore volume corresponds to the pore volume of mesopores with a pore diameter in the range of 3 to 50 nm, calculated by measuring a nitrogen adsorption isotherm at 77 K and analyzing it by the DH method (Dollimore-Heal method). The pore volume of pores with a diameter of 3 to 50 nm is the pore volume of mesopores corresponding to polymer compounds such as digestive enzymes, and corresponds to an index of the adsorption performance of polymer compounds. A preferred pore volume for pores with a diameter of 3 to 50 nm is 0.01 to 1.00 ml / g, and more preferably 0.01 to 0.20 ml / g. If the pore volume of pores with a diameter of 3 to 50 nm is too small, the mesopores that serve as diffusion paths for toxic substances to the micropores may be blocked due to the influence of polymer compounds such as various enzymes present in the body, which may result in insufficient adsorption performance for toxic substances. If the pore volume of pores with a diameter of 3 to 50 nm is too large, there is a risk that useful substances with large molecular weights, such as endogenous enzymes, may be unnecessarily adsorbed.

[0030] The average pore diameter is a value measured by the BET method. Specifically, assuming that the shape of the pores is cylindrical, the nitrogen adsorption isotherm is measured at 77 K, and the pore distribution is analyzed by the DH method and the MP method to determine the pore volume (mL / g). The specific surface area (m ２ / g) according to the following formula (ii). The average pore diameter is preferably 1.7 to 5.0 nm, more preferably 1.7 to 2.5 nm. If the average pore diameter is too small, there is a risk that the adsorption performance for toxic substances will decrease. If the average pore diameter is too large, there is a risk that useful substances with large molecular weights, such as endogenous enzymes, will be unnecessarily adsorbed.

[0031]

[0032] In the activated carbon adsorbent of the present invention, the pore volume (V ＭＥ ) to the pore volume of the sub-nanopores (V ＳＮ ) volume ratio (V ＳＮ／ＭＥ ) is preferably 3 to 50.

[0033]

[0034] This volume ratio (V ＳＮ／ＭＥ ) is the ratio of the pore volume of subnanopores intended for low molecular weight compounds to the pore volume of mesopores with a pore diameter in the range of 3 to 50 nm intended for high molecular weight compounds, and is 3 to 50, meaning that the pore volume intended for low molecular weight compounds is larger than the pore volume intended for high molecular weight compounds. This makes it possible to suppress the decrease in adsorption performance for toxic substances when both compounds coexist. The volume ratio (V ＳＮ／ＭＥ If the volume ratio (V) is too small, the pore volume for the low molecular weight compounds may be insufficient, resulting in a decrease in adsorption performance. ＳＮ／ＭＥ If the pore volume of the mesopores, which serve as diffusion paths for toxic substances, is too large, the adsorption of toxic substances is likely to be hindered, and the adsorption performance of toxic substances may be reduced.

[0035] Furthermore, by ensuring that the volume ratio satisfies the above range, it is possible to suppress excessive adsorption of the polymer compound in the coexistence of the low-molecular-weight compound and the polymer compound. In particular, if the volume ratio is too small, the pore volume for the polymer compound becomes excessive, which is undesirable because there is a risk of adsorption of more polymer compound than necessary.

[0036] Furthermore, in the activated carbon adsorbent of the present invention, the hardness (H Ｄ３００ ) is preferably 2.0 to 30.0 N. The average hardness is calculated as the average value of the crushing strength of any particle among activated carbon particles with a diameter of 150 to 500 μm, which is the particle size of an activated carbon adsorbent for oral administration. In particular, in order to suppress variations in hardness due to particle size between samples, a linear function is derived from the crushing strength of approximately 20 randomly selected activated carbon particles, and the hardness (H Ｄ３００It is desirable to calculate the hardness (H Ｄ３００ If the hardness (H) is too low, the activated carbon particles may easily collapse, and the desired adsorption performance may not be obtained. Ｄ３００ If the hardness of activated carbon particles with a particle diameter of 300 μm is 2.0 to 30.0 N, the shape of the activated carbon particles can be maintained and the deterioration of adsorption performance can be suppressed.

[0037] As will be shown in the examples below, the activated carbon adsorbent of the present invention has a pore diameter peak of 0.52 to 0.70 nm, and a pore volume of sub-nanopores with a pore diameter of 1.0 nm or less of 0.45 to 0.55 cm ３ / g, pore volume of pores with diameters of 3 to 50 nm is 0.01 to 1.0 cm ３ / g and an average pore diameter of 1.7 to 5.0 nm, it is possible to maintain a high level of adsorption performance for low molecular weight compounds even in the coexistence of low molecular weight compounds and high molecular weight compounds.

[0038] The adsorption phenomenon of an activated carbon adsorbent, which is specified by the pore diameter peak, the pore volume of subnanopores with a pore diameter of 1.0 nm or less, the pore volume of pores with a pore diameter of 3 to 50 nm, and the average pore diameter, will be explained using the conceptual diagrams in Figures 1 and 2. In the figures, reference numeral 10 denotes activated carbon particles, 20 denotes macropores, 30 denotes mesopores, 40 denotes micropores, 100 denotes activated carbon particles of a conventional activated carbon adsorbent, X and X1 denote low-molecular-weight compounds such as uremic toxins, and Y and Y1 denote high-molecular-weight compounds such as enzymes.

[0039] The activated carbon adsorbent of the present invention, whose pore diameter peak, pore volume of subnanopores with a pore diameter of 1.0 nm or less, pore volume of pores with a pore diameter of 3 to 50 nm, and average pore diameter are specified as described above, is expected to have a pore structure in which numerous mesopores 30 are formed within macropores 20 in activated carbon particles 10, and numerous micropores 40 are further formed within each mesopore 30, as shown in Figure 1. In other words, the structure has a relatively large number of mesopores 30 corresponding to polymeric compounds as well as micropores 40 corresponding to low-molecular-weight compounds.

[0040] On the other hand, in conventional activated carbon adsorbents, the pore volume of the mesopores is reduced relative to the pore volume of the micropores, and therefore, as shown in Figure 2, it is assumed that the activated carbon particles 100 have a pore structure in which there are few mesopores 30 within the macropores 20, and many micropores 40 are formed within each mesopore 30. In such activated carbon particles 100, the pore volume of the mesopores 30 is reduced relative to the pore volume of the micropores 40, and therefore, it is thought that a single-component adsorption test will demonstrate high adsorption performance for low-molecular-weight compound X.

[0041] However, in an environment where low-molecular-weight compounds and high-molecular-weight compounds coexist, as shown in Fig. 2, when the high-molecular-weight compound Y1 is adsorbed into the mesopores 30, the entrances of the mesopores 30, which have numerous micropores 40 formed therein, may be blocked by the high-molecular-weight compound Y1. The mesopores 30, which have micropores 40 formed therein, correspond to the paths (diffusion paths) required for pore diffusion when the low-molecular-weight compound is adsorbed into the micropores. Therefore, it is thought that the blocking of the entrances of the mesopores 30 by the high-molecular-weight compound Y1 blocks the path of the low-molecular-weight compound X1 to the micropores 40. Furthermore, because there are fewer mesopores 30 in the macropores 20, it is thought that the rate at which the diffusion paths of the low-molecular-weight compound X1 are blocked increases, resulting in a decrease in the adsorption performance for the low-molecular-weight compounds.

[0042] In contrast, in the activated carbon particles 10 of the activated carbon adsorbent of the present invention, a large number of mesopores 30 are formed within the macropores 20 in the activated carbon particles 10, and therefore, even if some of the mesopores 30 are blocked by the polymer compound Y1, as shown in Fig. 1 , it is believed that many other open mesopores 30 remain, ensuring a path for the low-molecular-weight compound X1 to reach the micropores 40. Therefore, it is believed that the rate at which the diffusion path of the low-molecular-weight compound X1 is blocked is reduced, and a decrease in the adsorption performance for the low-molecular-weight compound is suppressed.

[0043] The activated carbon adsorbent of the present invention can be obtained by a known production method that includes a carbonization step of carbonizing an activated carbon raw material and an activation step of activating the carbonized product obtained in the carbonization step. In the carbonization step, the activated carbon raw material is placed in a firing furnace such as a cylindrical retort electric furnace, and carbonized at 300 to 1000°C, preferably 450 to 700°C, for 1 to 20 hours under an inert atmosphere such as nitrogen, argon, or helium to obtain a carbonized product.

[0044] In the activation step, the carbonized material obtained in the carbonization step is placed in a known heating furnace or the like, and steam activation is performed at 750 to 1000°C, preferably 800 to 1000°C, and more preferably 850 to 950°C. The activation time varies depending on the production scale, equipment, etc., and is preferably about 0.5 to 50 hours, for example. In addition to steam activation, gas activation such as carbon dioxide can also be used in the activation step. The activated activated carbon is washed with dilute hydrochloric acid or the like, and after washing with dilute hydrochloric acid, it is washed with water until the pH reaches about 5 to 7. The pH is measured in accordance with JIS K 1474 (2014).

[0045] After washing with dilute hydrochloric acid, the adsorbent is optionally heated in a gas mixture of oxygen and nitrogen and washed with water to remove impurities such as ash and residual hydrochloric acid from the heat treatment. The oxygen concentration during the heat treatment is 0.1 to 21% by volume, the heating temperature is 150 to 1000°C, preferably 400 to 800°C, and the heating time is preferably about 15 minutes to 2 hours. With activated carbon adsorbents, the amount of surface oxides is adjusted by each treatment, and the amount of surface oxides is increased by the heat treatment after acid washing.

[0046] The shape of the activated carbon adsorbent is not particularly limited, but it is preferable to select the activated carbon by sieving after activation treatment or after heat treatment following activation treatment into granular or spherical activated carbon with an average particle size of 20 to 1000 μm, preferably 150 to 350 μm. Selecting the particle size within the above range ensures an appropriate surface area for the activated carbon adsorbent. Furthermore, adjusting and separating the particle size can stabilize the adsorption rate and adsorption capacity of the activated carbon adsorbent. That is, uniform particle size stabilizes adsorption performance in the digestive tract, maintains particle hardness, and prevents further powdering in the digestive tract after oral administration (ingestion). While spherical shapes are preferred for activated carbon adsorbents, granular shapes are also included, as variations in sphericity due to manufacturing processes are acceptable.

[0047] Phenolic resin, used as a raw material for activated carbon, has an aromatic ring structure in its molecule, which increases the carbonization yield. Furthermore, activation produces activated carbon with a large surface area. The activated carbon has a smaller pore size and a higher packing density than conventional activated carbons made from wood, coconut shells, petroleum pitch, and other materials. Therefore, it is suitable for adsorption of nitrogen-containing ionic organic compounds with relatively small molecular weights (molecular weights ranging from tens to hundreds), such as indoxyl sulfate, aminoisobutyric acid, and tryptophan, which are representative of uremia-causing substances and their precursors. Furthermore, phenolic resin has a lower ash content (e.g., nitrogen, phosphorus, sodium, and magnesium) and a higher carbon ratio per unit mass than conventional activated carbon raw materials such as wood. This allows for the production of activated carbon with fewer impurities.

[0048] [Preparation of Activated Carbon Adsorbents] The activated carbon raw materials described below were placed in a cylindrical retort electric furnace, nitrogen was sealed in, and then a heat treatment was performed. Further, steam was injected into the furnace to perform an activation treatment, and activated carbon adsorbents of Prototype Examples 1 to 16 were obtained.

[0049] [Prototype Example 1] As the activated carbon raw material, novolak resol composite spherical phenolic resin prepared by a known manufacturing method was used. 1 kg of this phenolic resin was placed in a cylindrical retort electric furnace, nitrogen was sealed inside, and the temperature was increased to 75°C / hour and maintained at 600°C for 1 hour to carbonize the spherical phenolic resin in the furnace. The resulting carbonized material was then heated to 900°C, and steam was injected into the furnace. The temperature was maintained at 900°C for 4 hours to activate the carbonized material, yielding the activated carbon adsorbent of Prototype Example 1.

[0050] [Prototype Example 2] Spherical phenolic resin (manufactured by Lignite Corporation) was used as the activated carbon raw material. 10 kg of this spherical phenolic resin was placed in a cylindrical retort electric furnace, nitrogen was sealed inside, and the temperature was increased at 50°C / hour and maintained at 600°C for 1 hour to carbonize the spherical phenolic resin in the furnace. The resulting carbonized material was then heated to 900°C, and steam was injected into the furnace. The temperature was maintained at 900°C for 10 hours to activate the carbonized material, yielding the activated carbon adsorbent of Prototype Example 2.

[0051] [Prototype 3] Prototype 3 is an activated carbon adsorbent obtained in accordance with Prototype 2, except that the activation time was set to 27 hours.

[0052] [Prototype Example 4] Prototype Example 4 is an activated carbon adsorbent obtained in accordance with Prototype Example 2, except that the activation time was changed to 33 hours.

[0053] [Prototype Example 5] Prototype Example 5 is an activated carbon adsorbent obtained in accordance with Prototype Example 2, except that the activation time was set to 37 hours.

[0054] [Prototype Example 6] Prototype Example 6 is a spherical adsorptive carbon (manufactured by Taewon Farm Company Limited, "Renamegin") using furan resin as the activated carbon raw material.

[0055] [Prototype Example 7] Prototype Example 7 is a spherical adsorptive carbon (manufactured by Nichi-Iko Pharmaceutical Co., Ltd., "Nichi-Iko") made from phenolic resin as a raw material.

[0056] [Prototype Example 8] Prototype Example 8 is an activated carbon adsorbent obtained in accordance with Prototype Example 2, except that the activation time was 40 hours.

[0057] [Prototype Example 9] Prototype Example 9 is an activated carbon adsorbent obtained in accordance with Prototype Example 2, except that the activation time was changed to 52 hours.

[0058] [Prototype Example 10] Prototype Example 10 is an activated carbon adsorbent obtained in accordance with Prototype Example 2, except that the activation time was changed to 56 hours.

[0059] [Prototype Example 11] Prototype Example 11 is an activated carbon adsorbent obtained in accordance with Prototype Example 2, except that the activation time was set to 60 hours.

[0060] [Prototype Example 12] Spherical furan resin manufactured by Asahi Organic Chemicals Co., Ltd. was used as the activated carbon raw material. 500 g of this furan resin was placed in a cylindrical retort electric furnace, nitrogen was sealed inside, and the temperature was increased at 50°C / hour and maintained at 500°C for 1 hour to carbonize the spherical furan resin in the furnace. The resulting carbonized product was then heated to 900°C, and steam was injected into the furnace. The temperature was maintained at 900°C for 5 hours to activate the carbonized product by adding steam, thereby obtaining the activated carbon adsorbent of Prototype Example 12.

[0061] [Example 13] The same novolak resol composite spherical phenolic resin as in Example 1 was used as the activated carbon raw material. 6 kg of this phenolic resin was placed in a cylindrical retort electric furnace, nitrogen was sealed in, and the temperature was maintained at an appropriate temperature of 150 to 250°C until it was fully cured. The temperature was then increased at 50°C / hour and maintained at 600°C for 1 hour to carbonize the spherical phenolic resin in the furnace. The resulting carbonized product was then heated to 850°C, and steam was injected into the furnace. The temperature was maintained at 850°C for 36 hours, and the steam was added to activate the carbonized product, yielding the activated carbon adsorbent of Example 13.

[0062] [Example 14] Example 14 is an activated carbon adsorbent obtained in the same manner as Example 1, except that the same novolak resol composite spherical phenolic resin as in Example 1 was used as the activated carbon raw material, the temperature rise rate was 50°C / hour, and the activation time was 6 hours.

[0063] [Example 15] A flame-retardant-treated spherical cellulose resin prepared by a known manufacturing method was used as the activated carbon raw material. 400 g of this flame-retardant-treated cellulose resin was placed in a cylindrical retort electric furnace, nitrogen was sealed inside, and the temperature was increased at 50°C / hour and maintained at 250°C for 1 hour. The carbonized product was then heated to 900°C, and steam was injected into the furnace. The temperature was maintained at 900°C for 3 hours, and the carbonized product was activated by adding steam, to obtain the activated carbon adsorbent of Example 15.

[0064] [Example 16] Example 16 is an activated carbon adsorbent obtained in the same manner as Example 1, except that the same novolak resol composite spherical phenolic resin as in Example 1 was used as the activated carbon raw material, the temperature rise rate was 50°C / hour, and the activation time was 8 hours.

[0065] [Measurements of activated carbon] The pore volume of the subnanopores, the pore volume of the ultramicropores, the pore diameter peak, the pore volume of all micropores, the pore volume of pores with diameters of 3 to 50 nm, the monolayer adsorption amount, the total specific surface area, the total pore volume, the average pore diameter, the average diameter of activated carbon particles, the average hardness of activated carbon particles, the hardness of particles with a diameter of 300 μm, and the volume ratio were each determined for the activated carbon adsorbents of Prototype Examples 1 to 16. The measurement results for each Prototype Example are shown in Tables 1 to 3 below.

[0066] [Subnanopore pore volume] For the activated carbon adsorbents of Examples 1 to 16, the pore volume (cm) of the subnanopores (pore diameter less than 1 nm) was ３ The pore volume of the subnanopores was determined by measuring a carbon dioxide adsorption isotherm at 298 K using a specific surface area / pore distribution measuring device ("BELSORP-mini II" manufactured by Microtrac-Bell Corporation), and then analyzing the obtained carbon dioxide adsorption isotherm using the GCMC method, with the activated carbon adsorbent set to graphite carbon and the pore shape set to a slit model.

[0067] [Ultramicropore pore volume] For the activated carbon adsorbents of Prototype Examples 1 to 16, the carbon dioxide adsorption isotherms obtained by the above measurement were similarly analyzed by the GCMC method to determine the pore volume (cm) of pores with a diameter of less than 0.7 nm (ultramicropores). ３ / g) was calculated for each.

[0068] [Pore Diameter Peak] For the activated carbon adsorbents of Prototype Examples 1 to 16, the carbon dioxide adsorption isotherms obtained by the above measurements were similarly analyzed by the GCMC method to determine the pore diameter peak based on the pore volume at each pore diameter.

[0069] [Pore Volume of All Micropores] For the activated carbon adsorbents of Prototype Examples 1 to 16, nitrogen adsorption isotherms were measured at 77 K using an automatic specific surface area / pore distribution measuring device ("BELSORP-mini II" manufactured by Microtrac-Bell Co., Ltd.), and the pore distribution was analyzed by the MP method (micropore method) to determine the pore volume (cm) of 0.42 to 2 nm (total micropores). ３ / g) was calculated for each.

[0070] [Pore volume of pores with diameters of 3 to 50 nm] For the activated carbon adsorbents of Examples 1 to 16, the pore distribution was analyzed by the DH method for the nitrogen adsorption isotherm obtained by the above measurement, and the pore volume (cm) of pores with diameters of 3 to 50 nm was calculated. ３ / g) was calculated for each.

[0071] [Monomolecular Layer Adsorption Amount] For the activated carbon adsorbents of Examples 1 to 16, the monomolecular layer adsorption amount (cm) was calculated by the BET method using the nitrogen adsorption isotherm obtained by the above measurement. ３ / g) was calculated for each.

[0072] [Total Specific Surface Area] For the activated carbon adsorbents of Samples 1 to 16, the total specific surface area (m ２ / g) was determined (BET specific surface area).

[0073] [Total Pore Volume] For the activated carbon adsorbents of Examples 1 to 16, the total pore volume (cm) was calculated by the BET method using the nitrogen adsorption isotherm obtained by the above measurement. ３ / g) was calculated for each.

[0074] [Average pore diameter] For the activated carbon adsorbents of Examples 1 to 16, the total specific surface area (m ２ The average pore diameter (nm) was calculated from the values ​​of the pore diameter (mL / g) and the total pore volume (mL / g) according to the above formula (ii).

[0075] [Average diameter of activated carbon particles] For the activated carbon adsorbents of Prototype Examples 1 to 16, 20 particles of activated carbon particles ranging from 150 to 500 μm were randomly selected, and the particle diameters were measured using a digital micrometer (manufactured by Shinwa Measurement Co., Ltd.). The average value was taken as the average diameter (μm).

[0076] [Average Hardness of Activated Carbon Particles] For the activated carbon adsorbents of Prototype Examples 1 to 16, the diameters of the activated carbon particles were measured using the digital micrometer. The maximum crushing strength until the activated carbon particles were broken was measured using a digital force gauge (manufactured by Imada Co., Ltd., "ZTA-50N"), and the average value was taken as the average hardness (N).

[0077] [Hardness of particles with a diameter of 300 μm] For the activated carbon adsorbents of Prototype Examples 1 to 16, the particle diameter and crushing strength data of 20 activated carbon particles measured by the above method were plotted, and a linear function was derived using spreadsheet software. After confirming that the correlation coefficient of the graph excluding outliers was 0.7 or more, the hardness of particles with a diameter of 300 μm was calculated from the mathematical formula of the linear function.

[0078] [Volume Ratio] For the activated carbon adsorbents of Examples 1 to 16, the pore volumes (cm) of the subnanopores obtained by the above measurement were ３ / g) and the pore volume (cm) of mesopores with a pore diameter in the range of 3 to 50 nm ３ Using the values ​​of (1 / g), the volume ratios were calculated from the above formula (i).

[0079]

[0080]

[0081]

[0082] [Adsorption Performance Test] For the activated carbon adsorbents of Prototype Examples 1 to 16, a toxin adsorption test, coexistence adsorption test (1) and coexistence adsorption test (2) were conducted as tests of the adsorption performance of low molecular weight compounds in the coexistence of low molecular weight compounds and high molecular weight compounds.

[0083] Toxin adsorption test: Three toxic substances were selected for the toxin adsorption test: tryptophan, indole, and indoleacetic acid, which are nitrogen-containing low-molecular-weight compounds that can cause uremia. Each substance was dissolved in a phosphate buffer solution at pH 7.4 to prepare a 0.1 g / L mixed solution of the three toxins. To the mixed solution of the three toxins, 0.1 g of each of the activated carbon adsorbents from Samples 1 to 16, which had been previously dried at 120°C for 15 minutes or more in a static dryer, was added. The mixture was then shaken at 37°C for 3 hours. The filtrate was then filtered through a membrane filter. The adsorption rate (%) was calculated from the difference in peak area before and after adsorption of each adsorbed substance (tryptophan, indole, and indoleacetic acid) using a high-performance liquid chromatograph (HPLC) (Agilent Technologies, Inc., 1260 Infinity II LC System) with gradient elution.

[0084] For gradient elution, an aqueous solution containing 0.05% trifluoroacetic acid was used as mobile phase A, and an ethanol solution containing 0.05% trifluoroacetic acid was used as mobile phase B. An "XBridge® Premier Protein BEH C4 300 Å 2.5 μm Column" (manufactured by Nihon Waters K.K.) was used as the separation column, the column heating temperature was set to 60°C, and the target substance was detected at a UV wavelength of 278 nm. Detailed gradient elution conditions are shown in Table 4.

[0085]

[0086] [Co-adsorption test (1)] In the co-adsorption test (1), three substances, "tryptophan," "indole," and "indoleacetic acid," were selected as toxic substances, and one substance, "α-amylase," was selected as an enzyme (polymer compound). A mixed solution of the three toxins and enzymes was prepared by dissolving each toxic substance at 0.1 g / L and α-amylase at 1 g / L in a phosphate buffer solution at pH 7.4. The adsorption rate (%) of each adsorbed substance (tryptophan, indole, indoleacetic acid, α-amylase) was determined using the same procedure as in the toxin adsorption test. Note that the concentration of α-amylase was set at 10 times the toxic substances because its molecular weight is higher than that of the toxic substances and the detected peak intensity is smaller.

[0087] [Coadsorption Test (2)] In Coadsorption Test (2), three toxic substances (tryptophan, indole, and indoleacetic acid) and four enzymes (α-amylase, pepsin, trypsin, and lipase) were selected. Each substance was dissolved in a phosphate buffer solution at pH 7.4 to prepare a 0.1 g / L mixed solution of the three toxins and four enzymes. The adsorption rate (%) of each adsorbed substance (tryptophan, indole, and indoleacetic acid) was calculated using the same procedure as in the toxin adsorption test. Note that in Coadsorption Test (2), due to the technical difficulty of separating the enzymes, only the adsorption rate of the toxic substances was calculated.

[0088] [Calculation of Adsorption Reduction Rate] For each of the toxin adsorption test, co-adsorption test (1), and co-adsorption test (2), the average adsorption rate of the toxins in each adsorption test ([adsorption rates of the three toxins] ÷ 3) was calculated from the calculated adsorption rates of the three toxins (tryptophan, indole, and indoleacetic acid). The average adsorption rate of the toxins in the toxin adsorption test was defined as the standard adsorption rate, and the average adsorption rate of the toxins in co-adsorption test (1) or co-adsorption test (2) was defined as the co-adsorption rate of each co-adsorption test. The adsorption reduction rate (%) was calculated using the following formula (iii). The adsorption reduction rate is an index showing the degree to which the adsorption rate of a low-molecular-weight compound decreases in the co-presence of a polymer compound compared to an environment in which the polymer compound does not coexist.

[0089]

[0090] [Evaluation of Adsorption Performance] The molecular weights of tryptophan, indoleacetic acid, and indole are 204, 175, and 117, respectively, which are smaller in order. Indole, in particular, is a highly hydrophobic substance and is therefore highly adsorbed by activated carbon, making it less susceptible to the effects of coexisting substances on the adsorption rate. Therefore, in each adsorption test, the adsorption rate of tryptophan, the adsorption rate of indoleacetic acid, and the average adsorption rate of toxins were evaluated as "good (○)" if they were 50% or higher, and "poor (×)" if they were less than 50%. The adsorption rate of indole was evaluated as "good (○)" if they were 95% or higher, and "poor (×)" if they were less than 95%. Furthermore, the adsorption rate and adsorption reduction rate of α-amylase were evaluated as "good (○)" if they were less than 30%, and "poor (×)" if they were 30% or higher. The results and evaluations are shown in Tables 5 to 7.

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[0092]

[0093]

[0094] [Results and Discussion] For the activated carbon adsorbents of prototype examples 1 to 16, a toxin adsorption test was conducted in which toxic substances (low molecular weight compounds) and enzymes (high molecular weight compounds) did not coexist, a coexistence adsorption test (1) in which multiple toxic substances and one type of enzyme coexisted, and a coexistence adsorption test (2) in which multiple toxic substances and multiple enzymes coexisted.The measurement results shown in Tables 5 to 7 were used to examine changes in adsorption performance in the coexistence of low molecular weight compounds and high molecular weight compounds.

[0095] In the toxin adsorption test, the adsorption performance for multiple toxic substances was measured in an environment where polymer compounds did not coexist. In prototype 1, the average adsorption rate for toxins exceeded the standard value, but the adsorption performance for tryptophan and indoleacetic acid was insufficient. In addition, prototype 2 did not have sufficient toxin adsorption performance. On the other hand, prototypes 3 to 16 all showed good toxin adsorption performance.

[0096] In the coexistence adsorption test (1), the adsorption performance for multiple toxic substances was measured in an environment where multiple toxic substances coexisted with one type of enzyme. In prototypes 1 to 7, although the adsorption rate for indole exceeded the standard value in some cases, the overall adsorption rate for each toxic substance was below the standard value, indicating that sufficient toxin adsorption performance could not be obtained in the coexistence of one type of polymer compound.

[0097] Furthermore, focusing on the adsorption reduction rate, which is an index of the reduction in the adsorption rate of low-molecular-weight compounds in the coexistence of polymer compounds, among Prototypes 1 to 7, Prototypes 1 and 2, which showed relatively low adsorption rates in the toxin adsorption test, had low adsorption reduction rates, while Prototypes 3 to 7, which showed good adsorption rates in the toxin adsorption test, had high adsorption reduction rates. This indicates that although Prototypes 3 to 7 had good toxin adsorption performance, the toxin adsorption performance was significantly reduced in the coexistence of one polymer compound. Furthermore, Prototypes 1 and 2 had relatively low toxin adsorption performance, so the adsorption reduction rate was suppressed, but it was shown that the toxin adsorption performance in the coexistence was insufficient.

[0098] On the other hand, in Prototype Examples 8 to 16, even in the presence of one polymer compound, the average adsorption rates of each toxic substance and toxin were good, and the adsorption reduction rate was also low and good. Therefore, Prototype Examples 8 to 16 demonstrated good toxin adsorption performance and were able to maintain a high level of toxin adsorption performance even in the presence of one polymer compound.

[0099] In co-adsorption test (2), the adsorption performance for multiple toxic substances was measured in an environment where multiple toxic substances and multiple enzymes coexisted. Prototypes 1 to 7 and 8 to 16 showed trends similar to those in co-adsorption test (1). Therefore, it was shown that the toxin adsorption performance of Prototypes 1 to 7 decreased in the presence of multiple polymer compounds, while that of Prototypes 8 to 16 maintained a high level of toxin adsorption performance even in the presence of multiple polymer compounds.

[0100] As described above, regardless of whether one or more polymer compounds are present, it was found that in the presence of polymer compounds, Prototypes 8 to 16 were able to maintain a high level of toxin adsorption performance, while the toxin adsorption performance decreased in Prototypes 1 to 7. Therefore, the differences in physical properties between Prototypes 8 to 16 and Prototypes 1 to 7 will be examined using Tables 1 to 3.

[0101] First, regarding the adsorption performance of toxic substances, Prototypes 1 and 2 are compared with Prototypes 3 to 16 based on the pore volume of subnanopores (pore diameter less than 1 nm) which are thought to correspond to the adsorption of toxic substances (low molecular weight compounds) and the pore volume of ultramicropores (pore diameter less than 0.7 nm). The pore volume of the subnanopores was larger in all of Prototypes 3 to 16, which had good adsorption performance, than in Prototypes 1 and 2, which had insufficient adsorption performance for each toxic substance in the toxin adsorption test. On the other hand, no different tendency was observed in the pore volume of the ultramicropores. Therefore, the pore volume of the subnanopores is effective as an index of the adsorption performance of toxic substances, and the measurement results of Prototypes 3 to 16 suggest that the preferable condition is 0.45 to 0.55 cm. ３ / g.

[0102] Next, regarding the adsorption performance of toxic substances in the presence of other substances, Prototype Examples 3 to 7 and Prototype Examples 8 to 16 are compared based on the pore diameter peak, pore volume of all micropores, pore volume of pores with diameters of 3 to 50 nm, monolayer adsorption amount, total specific surface area, total pore volume, average pore diameter, average diameter of activated carbon particles, average hardness of activated carbon particles, hardness of particles with a diameter of 300 μm, and volume ratio. No differences were observed between Prototype Examples 3 to 7 and Prototype Examples 8 to 16 regarding the pore volume of all micropores, monolayer adsorption amount, total specific surface area, total pore volume, average diameter of activated carbon particles, average hardness of activated carbon particles, and hardness of particles with a diameter of 300 μm.

[0103] On the other hand, the pore diameter peak, pore volume of pores with diameters of 3 to 50 nm, average pore diameter, and volume ratio tended to differ between Prototypes 3 to 7 and Prototypes 8 to 16. ２Since the measurement range is the micropores in the GCMC method based on adsorption, this corresponds to the peak of the pore diameter in the micropores. When Prototype Examples 3 to 7 are compared with Prototype Examples 8 to 16, the peak pore diameters of Prototype Examples 8 to 16 were all larger than the peak pore diameters of Prototype Examples 3 to 7.

[0104] The pore volume of pores with diameters of 3 to 50 nm corresponds to the pore diameter range of 3 to 50 nm, which corresponds to the adsorption of enzymes (polymer compounds), and can be used as an indicator of the adsorption performance of enzymes. Comparing Prototypes 3 to 7 with Prototypes 8 to 16, the pore volumes of pores with diameters of 3 to 50 nm in Prototypes 8 to 16 were all larger than the pore volumes of pores with diameters of 3 to 50 nm in Prototypes 3 to 7.

[0105] The average pore diameter can be used as an index of the adsorption performance of an activated carbon adsorbent. Comparing Prototypes 3 to 7 with Prototypes 8 to 16, the average pore diameters of Prototypes 8 to 16 were generally larger than the average pore diameters of Prototypes 3 to 7.

[0106] Therefore, in activated carbon adsorbents, in addition to the pore volume of subnanopores, which is an indicator of toxin adsorption performance, the physical properties specified by the pore diameter peak, the pore volume of pores with diameters of 3 to 50 nm, and the average pore diameter can be said to be effective indicators for maintaining a high level of adsorption performance for low-molecular-weight compounds (toxic substances) in the coexistence of low-molecular-weight compounds and high-molecular-weight compounds.

[0107] Therefore, considering the relationship between Prototype Examples 3 to 7 and Prototype Examples 8 to 16, preferable conditions for the peak pore diameter, the pore volume of pores with diameters of 3 to 50 nm, and the average pore diameter can be derived from the respective measurement results. The peak pore diameter is about 0.52 to 0.70 nm, and the pore volume of pores with diameters of 3 to 50 nm is 0.01 to 1.00 cm. ３ / g and an average pore diameter of about 1.7 to 5.0 nm. Therefore, an activated carbon adsorbent suitable for adsorbing toxins in the coexistence of toxic substances (low molecular weight compounds) and enzymes (high molecular weight compounds) has a subnanopore pore volume of 0.45 to 0.55 cm. ３ / g, it has excellent toxin adsorption performance, and the peak pore diameter is about 0.52 to 0.70 nm, and the pore volume of pores with diameters of 3 to 50 nm is 0.01 to 1.00 cm ３ It is considered necessary to satisfy all of the physical properties of about 1.7 to 5.0 nm, and a pore size of about 1.7 to 5.0 nm.

[0108] Furthermore, when Prototype Examples 8 to 16, which are suitable for toxin adsorption in the presence of coexistence, were compared, Prototype Example 16 had a higher adsorption rate of α-amylase than the other Prototype Examples 8 to 15 in the coexistence adsorption test (1). Considering the need to further improve the quality of activated carbon adsorbents, a lower adsorption rate of enzymes such as α-amylase in the presence of coexistence is preferable because it is less likely to cause side effects such as indigestion and loss of appetite. Therefore, when the physical properties of Prototype Example 16 and Prototype Examples 8 to 15 were compared, the volume ratio of Prototype Example 16 was smaller than the other Prototype Examples 8 to 15.

[0109] The volume ratio is the ratio of the pore volume of subnanopores, which is an indicator of the adsorption performance of toxic substances, to the pore volume of pores with diameters of 3 to 50 nm, which is an indicator of the adsorption performance of enzymes, and represents the balance between the subnanopores and pores with diameters of 3 to 50 nm in the activated carbon adsorbent. Since the volume ratio of Prototype 16 is 0.54, this indicates that the volume of pores with diameters of 3 to 50 nm is in excess compared to the pore volume of the subnanopores. Therefore, it is believed that Prototype 16 adsorbed more α-amylase than necessary. Therefore, based on the measurement results of Prototypes 8 to 15, a volume ratio of approximately 3 to 50 is considered to be the preferred condition for avoiding excessive adsorption of enzymes (polymer compounds) such as α-amylase.

[0110] It is preferable that the activated carbon adsorbent has a predetermined hardness, assuming that it will be formed into tablets or the like as a drug for oral administration. The preferred hardness of the activated carbon adsorbent is approximately 2.0 to 30.0 N for activated carbon particles with a particle diameter of 300 μm. Therefore, among the activated carbon adsorbents of Prototypes 1 to 16, the activated carbon adsorbents of Prototypes 8 to 13 were found to be excellent in terms of toxin adsorption performance in the presence of toxins, avoidance of excessive adsorption of enzymes, and hardness.

[0111] The activated carbon adsorbent of the present invention can maintain a high level of adsorption performance for low molecular weight compounds in the coexistence of both low molecular weight compounds and high molecular weight compounds, and therefore can exhibit excellent toxin adsorption performance in the body environment where low molecular weight toxic substances and high molecular weight enzymes coexist, making it a promising alternative to conventional activated carbon adsorbents.

[0112] 10 Activated carbon particle 20 Macropore 30 Mesopore 40 Micropore 100 Activated carbon particle of conventional activated carbon adsorbent X, X1 Low molecular weight compound Y, Y1 High molecular weight compound

Claims

1. CO ２ The peak of the pore diameter based on the pore volume calculated by the GCMC method based on adsorption (W ｐ ) is 0.52 to 0.70 nm, and the pore volume (V ＳＮ ) is 0.45 to 0.55 cm ３ / g, N ２ The pore volume (V) of pores with diameters of 3 to 50 nm calculated by the DH method based on adsorption ＭＥ ) is 0.01 to 1.00 cm ３ / g, and an average pore diameter measured by a BET method is 1.7 to 5.0 nm.

2. The pore volume (V) of the pores having a diameter of 3 to 50 nm as defined by the following formula (i) ＭＥ ) to the pore volume of the sub-nanopore (V ＳＮ ) volume ratio (V ＳＮ／ＭＥ 2. The activated carbon adsorbent according to claim 1, wherein the molecular weight of the activated carbon adsorbent is 3 to 50.

3. The hardness (H) of activated carbon particles with a particle diameter of 300 μm calculated from the average hardness of activated carbon particles with a diameter of 150 to 500 μm Ｄ３００ 3. The activated carbon adsorbent according to claim 1, wherein the concentration of the activated carbon adsorbent is 2.0 to 30.0 N.

4. The activated carbon adsorbent according to claim 1 or 2, which is an orally administered therapeutic or preventive agent for kidney disease or liver disease.

5. The activated carbon adsorbent according to claim 3, which is an orally administered therapeutic or preventive agent for kidney disease or liver disease.

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