WO2024262561A1 - Adsorbent, water purification filter, and water purifier - Google Patents

Abstract

Provided is an adsorbent capable of simultaneously removing high levels of a hydrophobic substance and a hydrophilic substance.　The adsorbent of the present invention contains: a hydrophobized carbon material that has been subjected to a hydrophobizing treatment using a hydrophobizing agent that is an organosilicon compound on a porous carbon material; and a low-hydrophobized carbon material that is subjected to a hydrophobizing treatment on a non-hydrophobized carbon material or a porous carbon material, which is a porous carbon material that has not been subjected to a hydrophobizing treatment, and that has a lower hydrophoby than the hydrophobized carbon material.

Description

Adsorbents, water filters and water purifiers

The present invention relates to an adsorbent, a water purification filter, and a water purifier.

Activated carbon (porous carbon material) is used for a wide range of substance purification and refinement, such as water purification and gas purification, by utilizing the diverse pores. In general, activated carbon has a hydrophobic surface and is known to exhibit high adsorption performance for hydrophobic substances. On the other hand, the surface of activated carbon is known to contain a number of various hydrophilic functional groups, such as oxygen atoms, which affect the adsorption performance of hydrophobic substances.

Therefore, efforts have been made to develop technology for modifying the surface of activated carbon by subjecting it to a hydrophobic treatment. For example, Patent Document 1 proposes a hydrophobic carbon material in which a silicon compound is attached to a porous carbon material.

The hydrophobic carbon material described in Patent Document 1 exhibits high adsorption performance for hydrophobic substances even in the presence of water molecules, because the surface of the porous carbon material is given hydrophobicity through hydrophobic treatment.

Patent No. 6509591

As mentioned above, hydrophobic carbon materials exhibit high adsorption performance for hydrophobic substances even in the presence of water molecules. Therefore, by using this hydrophobic carbon material as an adsorbent for water purification, it is expected that it will demonstrate high removal performance for hydrophobic organic compounds such as chloroform.

Here, adsorbents for water purification are required to have the ability to remove hydrophobic organic compounds as well as the ability to remove hydrophilic substances such as residual chlorine. However, when conventional hydrophobic carbon materials are used as adsorbents for water purification, there is a problem in that while the adsorbents exhibit high removal performance for hydrophobic substances, they do not have sufficient removal performance for hydrophilic substances, particularly residual chlorine.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an adsorbent, water purification filter, and water purifier that can simultaneously remove hydrophobic and hydrophilic substances at high levels.

The characteristic configuration of the adsorbent according to the present invention for achieving the above object is as follows:
The present invention is characterized in that it includes a hydrophobized carbon material in which a porous carbon material has been subjected to a hydrophobization treatment using a hydrophobization agent that is an organosilicon compound, and a non-hydrophobized carbon material which is the porous carbon material that has not been subjected to the hydrophobization treatment, or a low-hydrophobized carbon material in which the porous carbon material has been subjected to the hydrophobization treatment and has a lower degree of hydrophobicity than the hydrophobized carbon material.

As a result of extensive research, the present inventors have found that an adsorbent containing a hydrophobic carbon material suitable for adsorbing hydrophobic substances such as organic halogens, and a low-hydrophobic carbon material which has a lower degree of hydrophobicity than a non-hydrophobic carbon material or a hydrophobic carbon material suitable for adsorbing hydrophilic substances such as residual chlorine, and is suitable for adsorbing hydrophilic substances, can simultaneously achieve high levels of removal of hydrophobic substances and hydrophilic substances, and have completed the present invention.
That is, according to the above-mentioned characteristic configuration, the filter contains a hydrophobic carbon material suitable for adsorbing hydrophobic substances, and a non-hydrophobic carbon material suitable for adsorbing hydrophilic substances or a low-hydrophobic carbon material more suitable for adsorbing hydrophilic substances than the hydrophobic carbon material, thereby making it possible to simultaneously achieve high levels of removal of hydrophobic substances such as organic halogens and hydrophilic substances such as residual chlorine.

Further characteristic features of the adsorbent according to the present invention are:
The BET specific surface area of the hydrophobic carbon material is 600 m ² /g or more and 1450 m ² /g or less.

As a result of extensive research into the conditions under which hydrophobic and hydrophilic substances can be removed simultaneously at high levels, the inventors of the present application have discovered that by adjusting the BET specific surface area of the hydrophobic carbon material to 600 ^m2 /g or more and 1,450 ^m2 /g or less, a particularly high adsorption performance for hydrophobic substances can be achieved.
That is, according to the above characteristic configuration, it is possible to provide an adsorbent that has particularly excellent adsorption performance for hydrophobic substances and that satisfies a certain level or higher of removal performance for both hydrophobic substances and hydrophilic substances.

Further characteristic features of the adsorbent according to the present invention are:
The non-hydrophobic carbon material or the less-hydrophobic carbon material has a BET specific surface area of 860 m ² /g or more and 1700 m ² /g or less.

As a result of extensive research into conditions under which hydrophobic and hydrophilic substances can be removed simultaneously at high levels, the inventors of the present application have discovered that a non-hydrophobized carbon material or a low-hydrophobized carbon material can exhibit particularly high adsorption performance for hydrophilic substances by adjusting the BET specific surface area thereof to 860 ^m2 /g or more and 1700 ^m2 /g or less, at which the adsorption performance for hydrophilic substances is high.
That is, according to the above characteristic configuration, it is possible to provide an adsorbent that has particularly excellent adsorption performance for hydrophilic substances and that satisfies a certain level or higher of removal performance for both hydrophobic substances and hydrophilic substances.

Further characteristic features of the adsorbent according to the present invention are:
The BET specific surface area of the hydrophobic carbon material is equal to or less than the BET specific surface area of the non-hydrophobic carbon material or the low-hydrophobic carbon material.

The above characteristic configuration makes it possible to provide an adsorbent that has particularly excellent adsorption performance for hydrophobic and hydrophilic substances, and that meets a certain level of removal performance for both.

Further characteristic features of the adsorbent according to the present invention are:
The carbon material includes the hydrophobic carbon material and the non-hydrophobic carbon material.

The above characteristic configuration makes it possible to provide an adsorbent that has particularly excellent adsorption performance for hydrophobic substances and that meets a certain level of removal performance for both hydrophobic and hydrophilic substances.

Further characteristic features of the adsorbent according to the present invention are:
The mixing ratio of the hydrophobic carbon material is 10% by mass or more and 80% by mass or less.

As a result of extensive research into the conditions under which hydrophobic substances and hydrophilic substances can be removed simultaneously at a high level, the inventors of the present application have found that when the adsorbent contains a hydrophobized carbon material and a non-hydrophobized carbon material, the mixing ratio of the hydrophobized carbon material can be adjusted to 10 mass% or more and 80 mass% or less, thereby making it possible to achieve simultaneous removal of hydrophobic substances and hydrophilic substances at a high level.
That is, according to the above characteristic configuration, it is possible to provide an adsorbent that is particularly excellent in adsorption performance for hydrophobic substances and hydrophilic substances, and that satisfies a certain level or higher of removal performance for both.

Further characteristic features of the adsorbent according to the present invention are:
The carbon material includes the hydrophobic carbon material and the less hydrophobic carbon material.

The above characteristic configuration makes it possible to provide an adsorbent that has particularly excellent adsorption performance for hydrophobic substances and that meets a certain level of removal performance for both hydrophobic and hydrophilic substances.

Further characteristic features of the adsorbent according to the present invention are:
The mixing ratio of the hydrophobic carbon material is 20% by mass or more and 80% by mass or less.

As a result of extensive research into the conditions under which hydrophobic substances and hydrophilic substances can be removed simultaneously at a high level, the inventors of the present application have found that when the adsorbent contains a hydrophobic carbon material and a low-hydrophobic carbon material, by adjusting the mixing ratio of the hydrophobic carbon material to be 20 mass% or more and 80 mass% or less, it is possible to achieve simultaneous high-level removal of hydrophobic substances and hydrophilic substances.
That is, according to the above characteristic configuration, it is possible to provide an adsorbent that is particularly excellent in adsorption performance for hydrophobic substances and hydrophilic substances, and that satisfies a certain level or higher of removal performance for both.

Further characteristic features of the adsorbent according to the present invention are:
The hydrophobizing agent is an organic disilane compound.

According to the above characteristic configuration, the hydrophobic carbon material can be easily obtained by hydrophobization treatment using an easily available organic disilane compound as the hydrophobization agent. Therefore, the adsorbent can be easily provided.

Further characteristic features of the adsorbent according to the present invention are:
The hydrophobic carbon material has a weight loss starting temperature measured by thermogravimetric analysis that is higher than the boiling point of the hydrophobic treatment agent.

According to the above characteristic configuration, the hydrophobic treatment agent is strongly bonded to or interacts with the porous carbon material. Therefore, the adsorbent prevents the hydrophobic treatment agent from leaking out during use.

Further characteristic features of the adsorbent according to the present invention are:
The hydrophobizing agent is hexamethyldisilane,
The hydrophobic carbon material has a weight loss starting temperature of 200° C. or higher, as determined by thermogravimetric analysis.

The above characteristic configuration makes it possible to provide an adsorbent that prevents the outflow of hydrophobic treatment agents (such as hexamethyldisilane and its derivatives) during use.

The characteristic configuration of the water purification filter according to the present invention for achieving the above object is as follows:
The advantage is that the above-mentioned adsorbent is used.

The above characteristic configuration makes it possible to provide a water purification filter that can simultaneously remove hydrophobic and hydrophilic substances at high levels.

The characteristic configuration of the water purifier according to the present invention to achieve the above object is as follows:
The advantage is that the above-mentioned adsorbent is used.

The above characteristic configuration makes it possible to provide a water purifier that can simultaneously remove hydrophobic and hydrophilic substances at high levels.

As described above, the adsorbent, water purification filter, and water purifier of the present invention make it possible to simultaneously remove hydrophobic and hydrophilic substances at high levels.

1 is a graph showing the results of a chloroform adsorption performance test of Comparative Example 1 and Comparative Example 2. 1 is a graph showing the results of a residual chlorine adsorption performance test for Comparative Example 1 and Comparative Example 2.

The following describes the adsorbent, water purification filter, and water purifier according to the embodiments of the present invention. Note that although preferred examples are described below, each of these examples is described to more specifically illustrate the present invention, and various modifications are possible without departing from the spirit of the present invention, and the present invention is not limited to the following descriptions.

[Adsorbent]
In the present invention, the adsorbent includes a hydrophobized carbon material obtained by subjecting a porous carbon material to a hydrophobization treatment using a hydrophobization agent that is an organosilicon compound, a non-hydrophobized carbon material that is a porous carbon material that has not been subjected to a hydrophobization treatment, or a low-hydrophobized carbon material that has been subject to a hydrophobization treatment and has a lower degree of hydrophobization than the hydrophobized carbon material. The adsorbent has adsorption performance for hydrophobic substances and hydrophilic substances. In addition, examples of hydrophobic substances include organic halogens such as chloroform, aromatic compounds such as benzene, 2-MIB (methylisoborneol), and musty odor substances such as geosmin, and examples of hydrophilic substances include residual chlorine and anionic surfactants such as sodium alkylbenzenesulfonate. The adsorbent of the present invention is intended to remove chloroform and residual chlorine contained in tap water in particular.

Porous carbon material refers to a carbon material having a structure in which many pores are formed. Since many pores are formed in the porous carbon material, it has a large BET specific surface area. In the present invention, the BET specific surface area of the porous carbon material is not particularly limited, but it is preferable to appropriately adjust the BET specific surface area so that the hydrophobized carbon material, non-hydrophobized carbon material, and low-hydrophobized carbon material have the desired BET specific surface area.

The porous carbon material is not particularly limited, but activated carbon is usually used.

The raw material for the porous carbon material is not particularly limited. Examples include plant-based materials (e.g., plant-derived materials such as wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, pulp manufacturing by-products, lignin, and blackstrap molasses), mineral-based materials (e.g., mineral-derived materials such as peat, lignite, brown coal, bituminous coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residues, and petroleum pitch), synthetic resin-based materials (e.g., synthetic resin-derived materials such as phenolic resin, polyvinylidene chloride, and acrylic resin), and natural fiber-based materials (e.g., natural fibers such as cellulose, and regenerated fibers such as rayon).

The porous carbon material can be obtained by carbonizing or infusible the above-mentioned raw materials as necessary, and then activating them. The carbonization method, infusibility method, and activation method are not particularly limited, and known methods can be applied. For example, the activation method can be a gas activation method or a chemical activation method. The gas activation method is a method in which the carbon raw material (or its carbonized or infusible material) is heat-treated at about 500 to 1000°C in an activation gas (water vapor, carbon dioxide, etc.). The chemical activation method is a method in which the carbon raw material (or its carbonized or infusible material) is mixed with an activator (phosphoric acid, zinc chloride, potassium hydroxide, sodium hydroxide, etc.) and heat-treated at about 300 to 800°C. The porous carbon material may be one that has been activated in advance. Furthermore, commercially available porous carbon materials can also be used.

The raw material for the porous carbon material is preferably a plant-based material, a mineral-based material, a synthetic resin-based material, a natural fiber-based material, etc. In particular, wood-based porous carbon materials made from coconut shells, etc., are more preferable from the viewpoint that the hydrophobicity of the carbon material is easily promoted, the amount of water vapor adsorbed can be reduced in the presence of water molecules, and excellent adsorption, separation, and water repellency can be exhibited.

The shape of the porous carbon material is not particularly limited, and can be, for example, particulate, fibrous (thread, woven fabric (cloth), felt), block, powder, etc., and can be appropriately selected depending on the specific usage mode. Taking into consideration high adsorption performance per unit volume and ease of filling into the filter, the shape is preferably granular or block. The dimensions of the porous carbon material are not particularly limited, but it is preferable to appropriately adjust them so that the hydrophobic carbon material, non-hydrophobic carbon material, and low-hydrophobic carbon material have the desired average particle size.

In the present invention, the hydrophobized carbon material is the porous carbon material that has been subjected to hydrophobization treatment using a hydrophobization agent. The hydrophobization treatment is, for example, a treatment that performs a heating step in which the porous carbon material and the hydrophobization agent are heated in an inert gas atmosphere at a temperature of from room temperature to 900°C, preferably from 200°C to 900°C, more preferably from 200°C to 400°C, and even more preferably from 200°C to 350°C. The hydrophobization treatment may also be a treatment in which the porous carbon material and the hydrophobization agent are simply mixed together without performing a heating step.

The hydrophobic treatment agent is not particularly limited as long as it is an organic silicon compound, and various known compounds can be used as the hydrophobic treatment agent. As the hydrophobic treatment agent, an organic disilane compound can be used, for example, alkyl disilanes such as hexamethyldisilane, alkyl silanols such as trimethylsilanol, alkyl halogenated silanes such as trimethylchlorosilane, hexamethyldisilazane, triethylchlorosilane, triisopropylchlorosilane, t-butyldimethylchlorosilane, trimethylvinylsilane, trimethylallylsilane, etc. can be used. Among these, from the viewpoint of easily hydrophobizing the carbon material by hydrophobizing the pores of the porous carbon material to the depths, reducing the amount of water vapor adsorption in the presence of water molecules, and exhibiting excellent adsorption, separation, and water repellency, organic silicon compounds with small molecular size are preferred, and silicon compounds having trimethylsilyl groups (hexamethyldisilane, trimethylsilanol, trimethylchlorosilane, hexamethyldisilazane, trimethylvinylsilane, trimethylallylsilane, etc.) are preferred, with hexamethyldisilane, trimethylsilanol, hexamethyldisilazane, etc. being more preferred, and hexamethyldisilane being particularly preferred. The hydrophobizing treatment agent may be one of these organic silicon compounds used alone, or may be a combination of two or more of them.

In the present invention, the hydrophobic carbon material exhibits high adsorption performance for hydrophobic substances. For example, the hydrophobic carbon material preferably has a surface silicon concentration of 1% by mass or more and 20% by mass or less as measured by energy dispersive X-ray analysis. From the viewpoint of exhibiting superior adsorption performance for hydrophobic substances, the hydrophobic carbon material preferably has a surface silicon concentration of 1% by mass or more and 10% by mass or less as measured by energy dispersive X-ray analysis, more preferably 1.5% by mass or more and 10% by mass or less, even more preferably 1.5% by mass or more and 5% by mass or less.

In the present invention, the BET specific surface area of the hydrophobized carbon material is not particularly limited. The BET specific surface area of the hydrophobized carbon material affects the adsorption performance of the hydrophobic substance in the adsorbent. If the BET specific surface area of the hydrophobized carbon material is less than 600 m ² /g, the pore volume decreases, causing a decrease in the amount of adsorption of the hydrophobic substance, and the pores become smaller, causing a decrease in the adsorption speed. If the BET specific surface area exceeds 1450 m ² /g, the pores become too large, causing a decrease in the interaction energy between the hydrophobic substance and the hydrophobized carbon material, causing a decrease in the amount of adsorption. Therefore, it is preferable that the BET specific surface area of the hydrophobized carbon material is 600 m ² /g or more and 1450 ^{m 2} /g or less. From the viewpoint of exhibiting a better adsorption performance for hydrophobic substances, the BET specific surface area of the hydrophobized carbon material is more preferably 650 m ² /g or more and 1300 m ² /g or less, and even more preferably 700 m ² /g or more and 1200 m ² /g or less. When the BET specific surface area of the hydrophobized carbon material is high, the pore size becomes large, and the adsorption performance of hydrophobic substances, which is a characteristic of the hydrophobized carbon material, is likely to decrease. On the other hand, the adsorption performance of hydrophilic substances increases as the BET specific surface area increases, so that for non-hydrophobized carbon materials and low-hydrophobized carbon materials that compensate for the problem of the adsorption performance of hydrophilic substances, it is preferable to have a high BET specific surface area. Therefore, from the viewpoint of enabling the adsorbent to exhibit high adsorption performance for both hydrophobic substances and hydrophilic substances, it is preferable that the BET specific surface area of the hydrophobized carbon material be equal to or less than the BET specific surface area of the non-hydrophobized carbon material or low-hydrophobized carbon material described below.

In addition, in the present invention, it is preferable that the hydrophobic carbon material has a weight loss onset temperature measured by thermogravimetric analysis (TGA) that is higher than the boiling point of the hydrophobic treatment agent. When the weight loss onset temperature measured by TGA is higher than the boiling point of the hydrophobic treatment agent, the hydrophobic treatment agent is firmly bonded to or interacts with the porous carbon material, so that leakage of the hydrophobic treatment agent during use is suppressed, and the performance of the hydrophobic carbon material is maintained over a long period of time. For example, when hexamethyldisilane is used as the hydrophobic treatment agent, it is preferable that the hydrophobic carbon material has a weight loss onset temperature measured by TGA that is 200°C or higher.

In the present invention, the non-hydrophobic carbon material is the porous carbon material that has not been subjected to a hydrophobic treatment. In other words, in the present invention, the porous carbon material is used as the non-hydrophobic carbon material.

In the present invention, the low-hydrophobic carbon material is the porous carbon material that has been subjected to a hydrophobic treatment using a hydrophobic treatment agent, and has a lower degree of hydrophobicity than the hydrophobic carbon material. The content of the hydrophobic treatment and the hydrophobic treatment agent used in the hydrophobic treatment are the same as those in the case of the hydrophobic carbon material. The hydrophobic carbon material, non-hydrophobic carbon material, and low-hydrophobic carbon material may be the same porous carbon material, or may be porous carbon materials with different BET specific surface areas, average particle sizes, raw materials, etc.

In the present invention, the BET specific surface area of the non-hydrophobized carbon material (in other words, the BET specific surface area of a porous carbon material that has not been subjected to a hydrophobization treatment) and the BET specific surface area of the low-hydrophobized carbon material are not particularly limited. The BET specific surface areas of the non-hydrophobized carbon material and the low-hydrophobized carbon material affect the adsorption performance of a hydrophilic substance in the adsorbent. If the BET specific surface area of the non-hydrophobized carbon material and the low-hydrophobized carbon material is less than 860 ^{m 2} /g, the pore volume decreases, resulting in a decrease in the adsorption amount of the hydrophilic substance, and if it exceeds 1700 m ² /g, the non-hydrophobized carbon material and the low-hydrophobized carbon material become bulky, resulting in a decrease in the adsorption amount per volume and an extreme decrease in the adsorption performance of small molecules (e.g., chloroform). Therefore, the BET specific surface area of the non-hydrophobized carbon material and the low-hydrophobized carbon material is preferably 860 m ² /g or more and 1700 ^{m 2} /g or less. From the viewpoint of being able to exhibit a better adsorption performance for hydrophilic substances and being able to suppress an extreme decrease in the adsorption performance for hydrophobic substances, the BET specific surface area of the non-hydrophobized carbon material and the low-hydrophobized carbon material is more preferably 860 ^{m 2} /g or more and 1450 m ² /g or less, and further preferably 1000 m ² /g or more and 1400 m ² /g or less.

In the present invention, the non-hydrophobic carbon material exhibits high adsorption performance for hydrophilic substances. For example, the non-hydrophobic carbon material preferably has a concentration of inorganic silicon derived from the porous carbon material on the surface measured by energy dispersive X-ray analysis of 3 mass % or less, more preferably 2 mass % or less, and even more preferably 1 mass % or less.

In addition, in the present invention, the low hydrophobic carbon material exhibits higher adsorption performance for hydrophilic substances than the hydrophobic carbon material. For example, the low hydrophobic carbon material preferably has a surface silicon concentration of less than 1 mass% as measured by energy dispersive X-ray analysis. From the viewpoint of exhibiting better adsorption performance for hydrophilic substances than the hydrophobic carbon material, the low hydrophobic carbon material preferably has a surface silicon concentration of 0.8 mass% or less as measured by energy dispersive X-ray analysis, more preferably 0.4 mass% or less, and even more preferably 0.2 mass% or less.

In addition, in the present invention, the mixing ratio of the hydrophobized carbon material, in other words, the ratio of the hydrophobized carbon material in the adsorbent is not particularly limited, but when the adsorbent contains a hydrophobized carbon material and a non-hydrophobized carbon material, if the ratio of the hydrophobized carbon material is less than 10 mass%, the adsorption performance of the hydrophobized carbon material decreases, and if it exceeds 80 mass%, the adsorption performance of the hydrophilic substance decreases. Therefore, from the viewpoint that the adsorbent can simultaneously remove hydrophobic substances and hydrophilic substances at a high level, when the adsorbent contains a hydrophobized carbon material and a non-hydrophobized carbon material, it is preferable that the mixing ratio of the hydrophobized carbon material is 10 mass% or more and 80 mass% or less.

In addition, when the adsorbent contains a hydrophobized carbon material and a non-hydrophobized carbon material, the optimal range of the mixing ratio of the hydrophobized carbon material depends on the BET specific surface area of the non-hydrophobized carbon material. For example, when the BET specific surface area of the non-hydrophobized carbon material is 860 m ² /g or more and 1150 ^{m 2} /g or less, the mixing ratio of the hydrophobized carbon material is preferably 10 mass% or more and 70 mass% or less, and more preferably 30 mass% or more and 50 mass% or less. Furthermore, when the BET specific surface area of the non-hydrophobized carbon material is 1150 m ² /g or more and 1500 m ² /g or less, the mixing ratio of the hydrophobized carbon material is preferably 10 mass% or more and 75 mass% or less, and more preferably 30 mass% or more and 60 mass% or less. Furthermore, when the BET specific surface area of the non-hydrophobic carbon material is 1500 ^m2 /g or more and 1700 ^m2 /g or less, the mixing ratio of the hydrophobic carbon material is preferably 30 mass% or more and 80 mass% or less, and more preferably 50 mass% or more and 80 mass% or less.

In the present invention, even when the adsorbent contains a hydrophobic carbon material and a low hydrophobic carbon material, the mixing ratio of the hydrophobic carbon material, in other words, the ratio of the hydrophobic carbon material in the adsorbent is not particularly limited, but if the ratio of the hydrophobic carbon material is less than 20 mass%, the adsorption performance of hydrophobic substances decreases, and if it exceeds 80 mass%, the adsorption performance of hydrophilic substances decreases. Therefore, from the viewpoint that the adsorbent can simultaneously remove hydrophobic substances and hydrophilic substances at a high level, when the adsorbent contains a hydrophobic carbon material and a low hydrophobic carbon material, the mixing ratio of the hydrophobic carbon material is preferably 20 mass% or more and 80 mass% or less.

The average particle diameters of the hydrophobized carbon material, the non-hydrophobized carbon material, and the low-hydrophobized carbon material are not particularly limited, but it is preferable that the average particle diameters of the non-hydrophobized carbon material and the low-hydrophobized carbon material are equal to or smaller than the average particle diameter of the hydrophobized carbon material. Usually, the smaller the average particle diameter of the non-hydrophobized carbon material and the low-hydrophobized carbon material, the higher the contact efficiency with the hydrophilic substance to be removed, and the higher the removal performance of the hydrophilic substance. On the other hand, when the average particle diameter of the particles constituting the water purification adsorbent becomes smaller, the filling rate in the water purification filter also becomes higher, and as a result, the pressure loss during water flow increases, making it difficult to purify water at a high flow rate. However, when a hydrophobized carbon material is mixed as the water purification adsorbent, the hydrophobization effect makes it difficult to increase the pressure loss even if particles with a small average particle diameter are mixed. Therefore, as described above, by having the average particle diameters of the non-hydrophobized carbon material and the low-hydrophobized carbon material be equal to or smaller than the average particle diameter of the hydrophobized carbon material, the removal performance of the hydrophilic substance is improved while the increase in pressure loss is suppressed.

If the average particle size of the non-hydrophobic carbon material and the low-hydrophobic carbon material is less than 20 μm, when the water purification adsorbent is used in a water purifier, the allowable pressure of the water purifier (0.1 MPa) specified in JIS S301 is likely to be exceeded. Therefore, it is preferable that the average particle size of the non-hydrophobic carbon material and the low-hydrophobic carbon material is 20 μm or more. From the viewpoint of suppressing an increase in pressure loss, it is preferable that the average particle size of the non-hydrophobic carbon material and the low-hydrophobic carbon material is 25 μm or more, and more preferably 35 μm or more.

In this way, the adsorbent of the present invention contains a hydrophobized carbon material that exhibits high adsorption performance for hydrophobic substances, and a non-hydrophobized carbon material that exhibits high adsorption performance for hydrophilic substances, or a low-hydrophobized carbon material that exhibits higher adsorption performance for hydrophilic substances than the hydrophobized carbon material. Therefore, the adsorbent of the present invention can simultaneously remove hydrophobic substances and hydrophilic substances at high levels.

[Method of producing hydrophobic carbon material and low hydrophobic carbon material]
The hydrophobic carbon material and the low hydrophobic carbon material of the present invention can be obtained by a manufacturing method including a step of mixing a porous carbon material with an organosilicon compound as a hydrophobic treatment agent. This mixing step is a step of simply mixing a porous carbon material with an organosilicon compound as a hydrophobic treatment agent without performing heating as described below. For example, activated carbon and an organosilicon compound are mixed. In this mixing step, for example, when mixing activated carbon and an organosilicon compound, it is preferable to use a liquid organosilicon compound in order to mix them thoroughly.
The hydrophobic carbon material and the low hydrophobic carbon material of the present invention can be obtained by a manufacturing method including a step of mixing a porous carbon material with an organosilicon compound as a hydrophobizing agent, followed by a step of heating at a temperature of 200° C. or higher. For example, it is more preferable to mix activated carbon with an organosilicon compound and heat it at a temperature of 200° C. or higher. In this case, it is preferable to mix activated carbon with a liquid organosilicon compound, since it can be sufficiently impregnated. Specifically, for example, it is preferable to charge a sufficiently mixed mixture of activated carbon and an organosilicon compound into a stainless steel or ceramic container, replace the hollow wall of the furnace with an inert gas, and then heat it to a temperature of 200° C. or higher and 350° C. or lower, hold it for 9 minutes or more, and cool it to room temperature. The amount of the organosilicon compound used in producing the hydrophobic carbon material is preferably 1 part by mass or more and 25 parts by mass or less, more preferably 5 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of activated carbon, from the viewpoint of being able to adsorb more hydrophobic substances (such as chloroform in tap water) in order to further advance the hydrophobization of the activated carbon by making the attachment of the organosilicon compound stronger. On the other hand, the amount of the organosilicon compound used in producing the low hydrophobic carbon material is preferably more than 0 parts by mass or more and 3 parts by mass or less, more preferably 0.01 parts by mass or more and 3 parts by mass or less, even more preferably 0.01 parts by mass or more and 2 parts by mass or less, and even more preferably 0.01 parts by mass or more and 1 part by mass or less, relative to 100 parts by mass of activated carbon, from the viewpoint of being able to lower the hydrophobicity degree than the hydrophobic carbon material and to adsorb more hydrophilic substances.

In the above heating process, the heating temperature is preferably 200°C or higher and 350°C or lower, and heating at a temperature exceeding 350°C will slightly reduce the amount of hydrophobic substances (such as chloroform in tap water) adsorbed. In this specification, the heating temperature refers to the maximum temperature reached in the heating process.

In the above heating step, the heating time is from 5 to 90 minutes, preferably from 5 to 60 minutes, and more preferably from 9 to 19 minutes. If the heating time exceeds 19 minutes, the amount of hydrophobic substances (such as chloroform in tap water) adsorbed will decrease slightly with increasing heating time.

The heating step may be carried out in an open atmosphere or in a closed atmosphere (in a closed container), but is preferably carried out in an open heating device. When carried out in an open atmosphere, an open heating device such as a conveyor furnace, fluidized bed furnace, hot air blowing furnace, flash dryer, electric tubular furnace, or externally heated rotary tubular furnace can be used. When carried out in a closed atmosphere (in a closed container), a closed heat-resistant and pressure-resistant container (autoclave, etc.) can be used.

After the above heating step, it is preferable to cool the atmosphere to room temperature and remove the obtained activated carbon for water purifiers from the container.

[Water purification filter]
The water purification filter can be suitably realized by using the adsorbent described above in a filter having a known configuration.

The water purification filter may contain other functional components as long as the effects of the present invention are not impaired. Examples of other functional components include lead adsorbents such as titanosilicate and zeolite powders that can adsorb and remove soluble lead, ion exchange resins, or chelating resins, or various adsorbents that contain silver ions and/or silver compounds to impart antibacterial properties.

[Water purifier]
The water purifier can be realized by, for example, including a water purification cartridge formed by filling a housing with a molded body containing the water purification filter or the adsorbent. The water purification cartridge may include a combination of a known nonwoven fabric filter, an adsorbent such as an ion exchanger, a mineral additive, a ceramic filter material, a hollow fiber membrane, etc., in addition to the water purification filter or the molded body containing the adsorbent.

The present invention will be specifically explained below using examples, but the present invention is not limited to these examples. Various measurements were performed using the methods shown below.

[Measurement of silicon concentration on the surface of hydrophobic carbon material and low hydrophobic carbon material]
The silicon concentration on the surface of the hydrophobic carbon material and the less hydrophobic carbon material was measured using a scanning electron microscope equipped with an X-ray analyzer, Microscope TM3000/ShiftED3000, manufactured by Hitachi High-Technologies Corporation.
[Measurement of BET specific surface area]
The BET specific surface area of the hydrophobized carbon material, the non-hydrophobized carbon material, and the low-hydrophobized carbon material was measured by the nitrogen gas adsorption method using a high-precision gas/vapor adsorption amount measuring device BELSORP-max manufactured by BEL Japan Co., Ltd. As a pretreatment, the material was dried at 250°C under vacuum for 2.5 hours.
[Chloroform adsorption performance measurement]
The activated carbon was packed into a column, and the water was passed through the column in accordance with the test method for household water purifiers specified in JIS S 3201, with the test water having a chloroform concentration of 60 ppb being passed through the column at a flow rate of 3 L/min. The chloroform concentration was measured by collecting a sample in a container, sealing it, sampling the gas phase, and analyzing it with a gas chromatograph. The cumulative amount of water passed at the time when the chloroform removal rate became less than 80% of the initial value was evaluated as the removal performance.
[Measurement of residual chlorine adsorption performance]
The activated carbon was packed into a column, and the water was passed through the column in accordance with the test method for household water purifiers specified in JIS S 3201, with the test water having a free residual chlorine concentration of 2.0 ppm being passed through the column at a flow rate of 3 L/min. The free residual chlorine concentration was evaluated as the removal performance by collecting a sample in a container, developing the color with a DPD reagent, and measuring the free residual chlorine removal rate with an absorptiometer at less than 80% of the initial value, as the cumulative amount of water passed through.
[Measurement of weight loss onset temperature by thermogravimetric analysis]
Using a thermogravimetric analyzer Thermo plus Evo manufactured by Rigaku Corporation, the temperature was raised to 500° C. at 10° C./min in a nitrogen atmosphere to obtain a thermogravimetric curve. The weight loss starting temperature was calculated by extrapolation from the obtained thermogravimetric curve.

Example 1
Coconut shell activated carbon (Osaka Gas Chemicals Co., Ltd., average particle size 210 μm) with a BET specific surface area of 1094 ^m2 /g was used as the porous carbon material that was the base of the hydrophobic carbon material. 1000 g of coconut shell activated carbon dried by heating at 200°C was mixed with 90 g of hexamethyldisilane (Tokyo Chemical Industry Co., Ltd.), the mixture was placed in a stainless steel container, and reacted in a kiln under an inert gas atmosphere at 300°C for 19 minutes to obtain 1036 g of hydrophobic carbon material 1.
The surface silicon concentration of the obtained hydrophobized carbon material 1 was analyzed by an energy dispersive X-ray analyzer and found to be 3.5% (mass concentration). The hydrophobized carbon material 1 was subjected to nitrogen adsorption measurement at -196°C and the BET specific surface area was calculated to be 977 ^m2 /g. The weight loss starting temperature by thermogravimetric analysis was 239°C.
The porous carbon material used as the non-hydrophobic carbon material was coconut shell activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 210 μm) with a BET specific surface area of 1006 ^m2 /g, and this was not subjected to hydrophobic treatment and was designated as non-hydrophobic carbon material 1.
Hydrophobized carbon material 1 and non-hydrophobized carbon material 1 were uniformly mixed to obtain 11 types of adsorbents 1 with a mixing ratio of hydrophobized carbon material 1 ranging from 0 mass % (only non-hydrophobized carbon material 1) to 100 mass % (only hydrophobized carbon material 1) in 10 mass % increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 1 were measured.
The measurement results are shown in Table 1.

 

 

Example 2
The hydrophobic carbon material used was that obtained in Example 1.
As the porous carbon material to be the non-hydrophobic carbon material, coconut shell activated carbon with a BET specific surface area of 1193 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 210 μm) was used, and this was not subjected to hydrophobic treatment and was used as non-hydrophobic carbon material 2.
Hydrophobized carbon material 1 and non-hydrophobized carbon material 2 were uniformly mixed to obtain 11 types of adsorbents 2 in which the mixing ratio of hydrophobized carbon material 1 ranged from 0 mass % (only non-hydrophobized carbon material 2) to 100 mass % (only hydrophobized carbon material 1) in 10 mass % increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 2 were measured.
The measurement results are shown in Table 2.

 

 

Example 3
The hydrophobic carbon material used was that obtained in Example 1.
As the porous carbon material to be the non-hydrophobic carbon material, coconut shell activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 100 μm) with a BET specific surface area of 1,558 ^{m 2} /g was used, and this was not subjected to hydrophobic treatment and was used as the non-hydrophobic carbon material 3.
Hydrophobized carbon material 1 and non-hydrophobized carbon material 3 were uniformly mixed to obtain 11 types of adsorbents 3 in which the mixing ratio of hydrophobized carbon material 1 ranged from 0 mass % (only non-hydrophobized carbon material 3) to 100 mass % (only hydrophobized carbon material 1) in 10 mass % increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 3 were measured.
The measurement results are shown in Table 3.

 

 

Example 4
The hydrophobic carbon material used was that obtained in Example 1.
Coconut shell activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 100 μm) with a BET specific surface area of 1538 ^m2 /g was used as the porous carbon material that was the base of the low-hydrophobic carbon material. 1000 g of coconut shell activated carbon dried by heating at 200°C was mixed with 10 g of hexamethyldisilane (manufactured by Tokyo Chemical Industry Co., Ltd.), the mixture was placed in a stainless steel container, and reacted in a kiln under an inert gas atmosphere at 300°C for 19 minutes to obtain 983 g of low-hydrophobic carbon material 4.
The surface silicon concentration of the obtained low hydrophobic carbon material 4 was analyzed by an energy dispersive X-ray analyzer and found to be 0.38% (mass concentration). In addition, nitrogen adsorption measurement was performed on the low hydrophobic carbon material 4 at -196°C, and the BET specific surface area was calculated to be 1487 ^m2 /g.
The hydrophobic carbon material 1 and the less hydrophobic carbon material 4 were uniformly mixed to obtain nine types of adsorbents 4 in which the mixing ratio of the hydrophobic carbon material 1 ranged from 10% by mass to 90% by mass in 10% increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 4 were measured, and the results are shown in the table below.

 

 

Example 5
The porous carbon material used as the base of the hydrophobic carbon material was coconut shell activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 210 μm) having a BET specific surface area of 1094 ^m2 /g. 1000 g of coconut shell activated carbon and 55 g of hexamethyldisilane (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed to obtain 1050 g of hydrophobic carbon material 2.
The surface silicon concentration of the obtained hydrophobized carbon material 2 was analyzed by an energy dispersive X-ray analyzer and found to be 3.5% (mass concentration). The hydrophobized carbon material 2 was subjected to nitrogen adsorption measurement at -196°C and the BET specific surface area was calculated to be 1024 ^m2 /g. The weight loss starting temperature by thermogravimetric analysis was 242°C.
The hydrophobized carbon material 2 and the non-hydrophobized carbon material 2 of Example 2 were uniformly mixed to obtain 11 types of adsorbents 5 in which the mixing ratio of the hydrophobized carbon material 2 ranged from 0 mass % (only non-hydrophobized carbon material 2) to 100 mass % (only hydrophobized carbon material 2) in 10 mass % increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 5 were measured. The measurement results are shown in Table 5.

 
 

 
 

Example 6
The hydrophobic carbon material used was that obtained in Example 5.
The hydrophobized carbon material 2 and the non-hydrophobized carbon material 3 of Example 3 were uniformly mixed to obtain 11 types of adsorbents 6 in which the mixing ratio of the hydrophobized carbon material 2 ranged from 0 mass % (only the non-hydrophobized carbon material 3) to 100 mass % (only the hydrophobized carbon material 2) in 10 mass % increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 6 were measured. The measurement results are shown in Table 6.

 

 

Example 7
The porous carbon material used as the base of the hydrophobic carbon material was coconut shell activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 210 μm) having a BET specific surface area of 1094 m ² /g. 1000 g of coconut shell activated carbon and 143 g of hexamethyldisilane (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed to obtain 1130 g of hydrophobic carbon material 3.
The surface silicon concentration of the obtained hydrophobized carbon material 3 was analyzed by an energy dispersive X-ray analyzer and found to be 3.5% (mass concentration). The hydrophobized carbon material 3 was subjected to nitrogen adsorption measurement at -196°C and the BET specific surface area was calculated to be 930 ^m2 /g. The weight loss starting temperature by thermogravimetric analysis was 243°C.
The hydrophobized carbon material 3 and the non-hydrophobized carbon material 1 of Example 1 were uniformly mixed to obtain 11 types of adsorbents 7 in which the mixing ratio of the hydrophobized carbon material 3 ranged from 0 mass % (only non-hydrophobized carbon material 1) to 100 mass % (only hydrophobized carbon material 3) in 10 mass % increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 7 were measured. The measurement results are shown in Table 7.

 

 

Example 8
The hydrophobic carbon material used was that obtained in Example 7.
The hydrophobized carbon material 3 and the non-hydrophobized carbon material 3 of Example 3 were uniformly mixed to obtain 11 types of adsorbents 8 in which the mixing ratio of the hydrophobized carbon material 3 ranged from 0 mass % (only non-hydrophobized carbon material 3) to 100 mass % (only hydrophobized carbon material 3) in 10 mass % increments.
The chloroform adsorption performance and residual chlorine adsorption performance of the obtained adsorbent 8 were measured. The measurement results are shown in Table 8.

 

 

Comparative Example
The porous carbon materials used were coconut shell activated carbon with a BET specific surface area of 807 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon with a BET specific surface area of 1094 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon with a BET specific surface area of 1150 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon with a BET specific surface area of 1305 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), and coconut shell activated carbon with a BET specific surface area of 1538 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm). These were subjected to a hydrophobization treatment similar to that in Example 1 to obtain five types of hydrophobized carbon materials for measuring chloroform adsorption performance.
As the porous carbon materials, coconut shell activated carbon with a BET specific surface area of 807 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon with a BET specific surface area of 917 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon with a BET specific surface area of 1031 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon with a BET specific surface area of 1071 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), and coconut shell activated carbon with a BET specific surface area of 1538 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm) were used, and these were subjected to a hydrophobization treatment similar to that in Example 1 to obtain five types of hydrophobized carbon materials for measuring residual chlorine adsorption performance.
As the porous carbon material, coconut shell activated carbon having a BET specific surface area of 650 m ² /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon having a BET specific surface area of 807 m ² /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon having a BET specific surface area of 862 m ² /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon having a BET specific surface area of 1094 m ² /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon having a BET specific surface area of 1193 m ² /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), coconut shell activated carbon having a BET specific surface area of 1581 m ² /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm), Coconut shell activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd., average particle size 200 μm) having a molecular weight of 1.0 g/g was used, and this carbon material was not subjected to hydrophobic treatment to be used as a non-hydrophobic carbon material for measuring chloroform adsorption performance.
Furthermore, as porous carbon materials, coconut shell activated carbon with a BET specific surface area of 807 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle diameter 200 μm), coconut shell activated carbon with a BET specific surface area of 1006 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle diameter 200 μm), coconut shell activated carbon with a BET specific surface area of 1193 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle diameter 200 μm), and coconut shell activated carbon with a BET specific surface area of 1558 ^m2 /g (manufactured by Osaka Gas Chemicals Co., Ltd., average particle diameter 200 μm) were used, and these were not subjected to hydrophobic treatment and were used as non-hydrophobic carbon materials for measuring residual chlorine adsorption performance.
The chloroform adsorption performance and residual chlorine adsorption performance of the hydrophobized carbon material and the non-hydrophobized carbon material were measured. The measurement results are shown in Figures 1 and 2. Note that Figure 1 is a graph with the measured chloroform adsorption performance (L/ml) on the vertical axis and the BET specific surface area on the horizontal axis, and Figure 2 is a graph with the measured residual chlorine adsorption performance (L/ml) on the vertical axis and the BET specific surface area on the horizontal axis.

1 and 2, the chloroform adsorption performance of the hydrophobic carbon material varies depending on the BET specific surface area, reaching a maximum value at 1000 m ² /g to 1200 m ² /g and decreasing around that value. In addition, when the BET specific surface area is less than 600 m ² /g or more than 1450 m ² /g, the performance is lower than that of the non-hydrophobic carbon material.
On the other hand, the residual chlorine adsorption performance of the hydrophobic carbon material improves with an increase in the BET specific surface area, and particularly improvement in performance is seen from about 1000 ^m2 /g or more. However, in order to achieve the same level of performance as a non-hydrophobic carbon material with the same BET specific surface area, a BET specific surface area of 1400 ^m2 /g or more is required, and in this case, the chloroform adsorption performance becomes extremely low.
In addition, the non-hydrophobic carbon material has a maximum chloroform adsorption capacity of about 15 L/ml, which is extremely low compared to the hydrophobic carbon material, whereas the residual chlorine adsorption capacity exceeds the maximum value of chloroform adsorption capacity of 15 L/ml when the BET specific surface area exceeds about 850 ^m2 /g, which is superior to the hydrophobic carbon material.
Thus, when the hydrophobized carbon material and the non-hydrophobized carbon material are used alone as the adsorbent, they are unable to simultaneously exhibit high levels of both chloroform adsorption performance and residual chlorine adsorption performance.

On the other hand, as shown in Tables 1 to 8, by using a mixture of a hydrophobized carbon material and a non-hydrophobized carbon material as an adsorbent, it is possible to simultaneously exhibit high levels of both chloroform adsorption performance and residual chlorine adsorption performance.
Specifically, as is clear from Table 1, when the mixing ratio of the hydrophobic carbon material in adsorbent 1 is from 10% by mass to 60% by mass, both the chloroform adsorption capacity and the residual chlorine adsorption capacity exceed 15 L/ml, which is the maximum value of the chloroform adsorption capacity of the non-hydrophobic carbon material. In particular, when the mixing ratio is from 30% by mass to 40% by mass, both adsorption capacities become 20 L/ml or more.
Furthermore, as is clear from Table 2, when the mixing ratio of the hydrophobic carbon material in the adsorbent 2 is 10 mass% or more and 70 mass% or less, both the chloroform adsorption capacity and the residual chlorine adsorption capacity exceed 15 L/ml, and in particular, when the mixing ratio is 30 mass% or more and 50 mass% or less, both adsorption capacities become 20 L/ml or more.
Furthermore, as is clear from Table 3, when the mixing ratio of the hydrophobic carbon material in the adsorbent 3 is 30 mass% or more and 80 mass% or less, both the chloroform adsorption capacity and the residual chlorine adsorption capacity exceed 15 L/ml, and in particular, when the mixing ratio is 50 mass% or more and 80 mass% or less, both adsorption capacities become 20 L/ml or more.

Furthermore, as shown in Table 4, by using a mixture of a hydrophobic carbon material and a less hydrophobic carbon material as an adsorbent, it is possible to simultaneously exhibit high levels of both chloroform adsorption performance and residual chlorine adsorption performance.
Specifically, as is clear from Table 4, when the mixing ratio of the hydrophobic carbon material in the adsorbent 4 is 20 mass% or more and 80 mass% or less, both the chloroform adsorption performance and the residual chlorine adsorption performance exceed 15 L/ml, which is the maximum value of the chloroform adsorption performance of the non-hydrophobic carbon material, and in particular, when the mixing ratio is 30 mass% or more and 70 mass% or less, both adsorption performances become 20 L/ml or more.

Furthermore, as is clear from Table 5, when the mixing ratio of the hydrophobic carbon material in the adsorbent 5 is 10 mass% or more and 80 mass% or less, both the chloroform adsorption capacity and the residual chlorine adsorption capacity exceed 15 L/ml, and in particular, when the mixing ratio is 50 mass% or more and 70 mass% or less, both adsorption capacities become 20 L/ml or more.
Furthermore, as is clear from Table 6, when the mixing ratio of the hydrophobic carbon material in the adsorbent 6 is set to 50 mass% or more and 90 mass% or less, both the chloroform adsorption capacity and the residual chlorine adsorption capacity exceed 15 L/ml, and in particular, when the mixing ratio is set to 70 mass% or more and 80 mass% or less, both adsorption capacities become 20 L/ml or more.
Furthermore, as is clear from Table 7, when the mixing ratio of the hydrophobic carbon material in the adsorbent 7 is set to 10 mass% or more and 50 mass% or less, both the chloroform adsorption capacity and the residual chlorine adsorption capacity exceed 15 L/ml, and in particular, when the mixing ratio is set to 20 mass% or more and 40 mass% or less, both adsorption capacities become 20 L/ml or more.
Furthermore, as is clear from Table 8, when the mixing ratio of the hydrophobic carbon material in the adsorbent 8 is set to 30 mass% or more and 80 mass% or less, both the chloroform adsorption capacity and the residual chlorine adsorption capacity exceed 15 L/ml, and in particular, when the mixing ratio is set to 40 mass% or more and 70 mass% or less, both adsorption capacities become 20 L/ml or more.

Claims (13)

An adsorbent comprising a hydrophobic carbon material in which a porous carbon material has been subjected to a hydrophobic treatment using a hydrophobic treatment agent that is an organosilicon compound, and a non-hydrophobic carbon material in which the porous carbon material has not been subjected to the hydrophobic treatment, or a low-hydrophobic carbon material in which the porous carbon material has been subjected to the hydrophobic treatment and has a lower degree of hydrophobicity than the hydrophobic carbon material. The adsorbent according to claim 1 , wherein the BET specific surface area of the hydrophobized carbon material is 600 m ² /g or more and 1450 ^{m 2} /g or less. The adsorbent according to claim 1, wherein the non-hydrophobic carbon material or the less-hydrophobic carbon material has a BET specific surface area of 860 m ² /g or more and 1700 ^{m 2} /g or less. The adsorbent according to claim 1, wherein the BET specific surface area of the hydrophobic carbon material is equal to or less than the BET specific surface area of the non-hydrophobic carbon material or the low-hydrophobic carbon material. The adsorbent according to claim 1, comprising the hydrophobized carbon material and the non-hydrophobized carbon material. The adsorbent according to claim 5, wherein the mixing ratio of the hydrophobic carbon material is 10% by mass or more and 80% by mass or less. The adsorbent according to claim 1, comprising the hydrophobic carbon material and the less hydrophobic carbon material. The adsorbent according to claim 7, wherein the mixing ratio of the hydrophobic carbon material is 20% by mass or more and 80% by mass or less. The adsorbent according to claim 1, wherein the hydrophobic treatment agent is an organic disilane compound. The adsorbent according to claim 1, wherein the hydrophobic carbon material has a temperature at which weight loss begins, as determined by thermogravimetric analysis, that is higher than the boiling point of the hydrophobic treatment agent. The hydrophobizing agent is hexamethyldisilane,
The adsorbent according to claim 1 , wherein the hydrophobic carbon material has a weight loss starting temperature of 200° C. or higher according to thermogravimetric analysis. A water purification filter using the adsorbent according to any one of claims 1 to 11. A water purifier using the adsorbent according to any one of claims 1 to 11.

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