Molded body and method for removing perfluoroalkyl compounds and / or polyfluoroalkyl compounds

Abstract

A molded body according to the present application contains activated carbon and a binder, wherein the volume of voids having a diameter of 1-30 μm in the molded body as measured by a mercury intrusion method is 20% or more of the volume of all voids in the molded body as measured by the mercury intrusion method.

Description

Molded body and method for removing perfluoroalkyl and / or polyfluoroalkyl compounds

[0001] The present invention relates to a molded article containing activated carbon and a binder, and a method for removing fluorine-containing organic compounds (perfluoroalkyl compounds and / or polyfluoroalkyl compounds) using the same.

[0002] In recent years, there has been growing concern about the safety and health of tap water quality, and it is desirable to remove various harmful substances from tap water.

[0003] Fluorine-containing organic compounds have unique properties that cannot be achieved with other substances (excellent heat and chemical resistance, usable even under harsh conditions, no light absorption, etc.). For this reason, fluorine-containing organic compounds have been used in a variety of applications, including surfactants, emulsifiers, water repellents, fire extinguishing agents, waxes, carpet cleaning agents, and coating agents. Recently, they have also been increasingly used as functional materials, such as surface treatment agents for semiconductors and fuel cell components.

[0004] However, several years ago, researchers in the United States and Canada began to report that some fluorine-containing organic compounds accumulate in environmental water and in the bodies of wildlife. A typical example of this compound is perfluorooctanoic acid (PFOA). ７ F １５ COOH) and perfluorooctanesulfonic acid (PFOS:C ８ F １７ SO ３ These compounds are perfluorosulfonic acids, represented by H. Subsequently, European and Japanese researchers also began to participate in environmental analysis research, and it became clear that these compounds exist in the environment on a global scale, including in Japan.

[0005] In response to this situation, efforts have been initiated to reduce the environmental risks posed by fluorine-containing organic compounds (perfluoroalkyl compounds and / or polyfluoroalkyl compounds (hereinafter also referred to as "PFAS")). For example, Patent Document 1 describes a carbonaceous material with high PFAS removal performance that can also be used in water purifier applications.

[0006] Patent No. 7060772

[0007] An object of the present invention is to provide a molded body from which fluorine-containing organic compounds (PFAS) can be effectively removed.

[0008] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention.

[0009] A molded body according to a first aspect of the present invention is a molded body comprising activated carbon and a binder, wherein the volume of voids having a diameter of 1 μm to 30 μm inside the molded body measured by mercury porosimetry is 20% or more of the volume of all voids inside the molded body measured by mercury porosimetry.

[0010] A method for removing perfluoroalkyl compounds and / or polyfluoroalkyl compounds according to a second aspect of the present invention comprises using the molded article according to the first aspect of the present invention.

[0011] Fig. 1 is a perspective view showing an example of a mold for preparing a molded body in this embodiment. Fig. 2 is a perspective view showing an example of a molded body in this embodiment obtained using the mold of Fig. 1. Fig. 3 is a graph showing the particle size distribution (cumulative volume (%)) of the powdered activated carbon used in Examples 1 to 7 and Comparative Example 1. Fig. 4 is a diagram explaining how to cut out samples when measuring the void volume of a molded body. Fig. 5 is a perspective view showing an example of an automatic grinding machine for producing a molded body.

[0012] Patent Document 1 describes a technology for removing PFAS by using a carbonaceous material such as activated carbon with an increased degree of activation or a water purification filter containing the same.

[0013] Generally, when a carbonaceous material powder is used as a water purification filter without modification, there is a problem in that it is difficult to simultaneously improve the removal efficiency of target substances and suppress an increase in water flow resistance. Therefore, when using a carbonaceous material powder as a water purification filter, it is known that a fibrous binder or the like is typically added to the carbonaceous material powder to form a molded body. By forming the molded body in such a shape, the range of applications as a small water purification filter can be expanded. Therefore, from the viewpoint of the physical properties or configuration of the molded body, it would be preferable to obtain a molded body that can more efficiently remove PFAS.

[0014] As a result of intensive research by the present inventors, it has been found that a molded body that can effectively remove PFAS can be obtained by controlling the ratio of the volume of voids with diameters of 1 μm to 30 μm inside the molded body, as measured by mercury intrusion porosimetry, to a predetermined value or more in a molded body containing activated carbon and a binder.

[0015] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0016] <Molded body> The molded body in this embodiment is a molded body containing activated carbon and a binder, and the volume of voids having a diameter of 1 μm to 30 μm inside the molded body measured by mercury porosimetry is 20% or more of the volume of all voids inside the molded body measured by mercury porosimetry.

[0017] [Physical Properties of Molded Body] In the molded body of this embodiment, the volume of voids having a diameter of 1 μm to 30 μm inside the molded body measured by mercury intrusion porosimetry (hereinafter also simply referred to as "void volume of voids having a diameter of 1 μm to 30 μm of the molded body") is 20% or more of the volume of all voids inside the molded body measured by mercury intrusion porosimetry (hereinafter also simply referred to as "total void volume of the molded body"). In other words, the proportion of the volume of voids having a diameter of 1 μm to 30 μm in the molded body is 20% or more.

[0018] In this embodiment, the pore volume ratio of the molded body having a diameter of 1 μm to 30 μm is 20% or more, thereby enabling efficient and satisfactory removal of PFAS. This is because PFAS particles efficiently come into contact with and are adsorbed into the narrow pores between activated carbon particles having a diameter of 1 μm to 30 μm inside the molded body. The pore volume of the activated carbon itself contained in the molded body has almost no effect on the ratio of the pore volume of the molded body having a diameter of 1 μm to 30 μm. Therefore, the raw material activated carbon contained in the molded body in this embodiment may be activated carbon with a high degree of activation, or activated carbon with a normal degree of activation.

[0019] From the viewpoint of being able to obtain a particularly stable PFAS removal effect, specifically, the ratio of the void volume of the molded body having a diameter of 1 μm to 30 μm is, for example, preferably 22.0% to 95.0%, more preferably 25.0% to 93.0%, even more preferably 30.0% to 90.0%, and particularly preferably 33.0% to 88.0%.

[0020] Specifically, the proportion of void volume in the molded body having a diameter of 1 μm to 30 μm may be a value selected from 20.6%, 20.8%, 22.7%, 25.0%, 27.0%, 30.0%, 33.1%, 35.0%, 40.0%, 45.0%, 50.0%, 54.1%, 55.0%, 60.0%, 62.8%, 65.0%, 70.0%, 75.0%, 78.3%, 80.8%, 82.2%, 85.9%, 90.0%, etc., or may be a range set by using a value selected from these as the lower limit.

[0021] The upper limit of the void volume ratio of the molded body having a diameter of 1 μm to 30 μm is not particularly limited as long as a sufficient amount of activated carbon can be retained inside the molded body and the shape of the molded body can be maintained. For example, the void volume ratio of the molded body having a diameter of 1 μm to 30 μm may be a value selected from 95.0%, 93.0%, 90.0%, 85.9%, 82.2%, etc., or may be within a range set by setting a value selected from these as the upper limit.

[0022] The void volume of the molded body having a diameter of 1 μm to 30 μm is not particularly limited as long as it satisfies the condition that the ratio of the void volume of the molded body having a diameter of 1 μm to 30 μm is 20% or more, a sufficient amount of activated carbon can be held inside the molded body, and the shape of the molded body can be maintained. The void volume of the molded body having a diameter of 1 μm to 30 μm is, for example, 0.10 cm ３ / cc ~ 0.90cm ３ / cc, preferably 0.15 cm ３ / cc ~ 0.80cm ３ / cc, preferably 0.16 cm ３ / cc ~ 0.70cm ３ / cc, more preferably 0.23 cm ３ / cc ~ 0.60cm ３ It is more preferable that the ratio is / cc.

[0023] Specifically, the void volume of the molded body with a diameter of 1 μm to 30 μm is 0.15 cm ３ / cc, 0.16cm ３ / cc, 0.20cm ３ / cc, 0.23cm ３ / cc, 0.30cm ３ / cc, 0.38cm ３ / cc, 0.40 cm ３ / cc, 0.49cm ３ / cc, 0.51cm ３ / cc, 0.54cm ３ / cc, 0.55cm ３ / cc, 0.58cm ３ / cc, 0.60cm ３ / cc, 0.70cm ３ / cc, or may be a range set by two values ​​selected from these.

[0024] The total void volume of the molded body is not particularly limited as long as it satisfies the condition that the ratio of the void volume of the molded body having a diameter of 1 μm to 30 μm is 20% or more, a sufficient amount of activated carbon can be held inside the molded body, and the shape of the molded body can be maintained. The total void volume of the molded body is, for example, 0.50 cm ３ / cc ~ 0.90cm ３ / cc, preferably 0.60 cm３ / cc ~ 0.88cm ３ / cc, more preferably 0.61 cm ３ / cc ~ 0.86cm ３ It is more preferable that the total void volume of the molded body is 0.90 cm3 / cc. ３ When the total void volume of the molded body is 0.50 cm3 or less, the total amount of activated carbon becomes a more preferable amount, and when the molded body is used as a water purification filter, etc., the performance of removing other common harmful substances can also be improved. ３ / cc or more, the water flow resistance can be kept satisfactorily low when the molded article is used as a water purification filter or the like.

[0025] Specifically, the total void volume of the molded body is 0.60 cm ３ / cc, 0.61 cm ３ / cc, 0.62 cm ３ / cc, 0.67cm ３ / cc, 0.71 cm ３ / cc, 0.72 cm ３ / cc, 0.73cm ３ / cc, 0.86 cm ３ / cc, 0.88cm ３ / cc, or may be a range set by two values ​​selected from these.

[0026] In this specification, the pore volume of a molded body having a diameter of 1 μm to 30 μm measured by mercury porosimetry, the total pore volume of the molded body, and the ratio of the pore volume of a molded body having a diameter of 1 μm to 30 μm calculated from these values ​​can be measured using a mercury porosimetry pore volume measuring device (MicroActive AutoPore V 9620 manufactured by Micromeritics) as described in the Examples below. Note that in the Examples below, the molded layer of the molded body is used as a measurement sample having a size of approximately 1 cm square, but it is preferable to change the size of this measurement sample as appropriate depending on the size of the molded body. For example, if the molded body is to be used in a spout-in type filter, it is desirable to measure it using a measurement sample of approximately 5 mm square.

[0027] The proportion of void volume with a diameter of 1 μm to 30 μm, the void volume with a diameter of 1 μm to 30 μm, and the total void volume can be controlled by various methods. For example, these values ​​can be controlled by appropriately selecting and / or adjusting the physical properties (particularly particle size distribution) and blending amount of the raw activated carbon, the blending ratio when two or more types of activated carbon with different physical properties are used, and various conditions during the production of the molded body (e.g., the solids concentration of the slurry used, whether or not a rolling step of the pre-molded body is performed, processing conditions in the suction filtration step such as suction pressure and suction time, etc.). As will be described in detail later, among these, the proportion of void volume with a diameter of 1 μm to 30 μm in the molded body can be easily controlled by adjusting the particle content (volume %) of 50 μm to 100 μm particle diameters of the raw activated carbon and D90 within a predetermined range.

[0028] The density of the molded body in this embodiment is not particularly limited as long as it satisfies the condition that the ratio of the void volume of the molded body having a diameter of 1 μm to 30 μm is 20% or more, a sufficient amount of activated carbon can be held inside the molded body, and the shape of the molded body can be maintained. The density of the molded body is, for example, 0.15 g / cm ３ ~0.60 g / cm ３ and preferably 0.20 g / cm ３ ~0.55g / cm ３ More preferably, it is 0.22 g / cm ３ ~0.51 g / cm ３ It is more preferable that the density of the molded body in this specification can be measured by the method described in detail in the Examples below.

[0029] In the molded body of this embodiment, the total amount of acidic functional groups in the activated carbon layer obtained by cutting out a portion of the molded body (hereinafter simply referred to as the "total amount of acidic functional groups in the activated carbon layer") is preferably 0.7 meq / g or less. When the total amount of acidic functional groups in the activated carbon layer is 0.7 meq / g or less, the hydrophobicity is high, and the affinity between the activated carbon layer and PFAS is increased. As a result, the PFAS removal performance of the molded body can be further improved. Note that, in this specification, the total amount of acidic functional groups in the activated carbon layer can be measured by a neutralization titration method, which will be described in detail in the Examples below.

[0030] The lower limit of the total amount of acidic functional groups in the activated carbon layer is not particularly limited as long as a sufficient amount of activated carbon can be retained inside the molded body and the shape of the molded body can be maintained. The total amount of acidic functional groups in the activated carbon layer is, for example, preferably 0.08 meq / g to 0.65 meq / g, more preferably 0.10 meq / g to 0.60 meq / g, and even more preferably 0.15 meq / g to 0.57 meq / g.

[0031] Specifically, the total amount of acidic functional groups in the activated carbon layer may be a value selected from 0.65 meq / g, 0.60 meq / g, 0.57 meq / g, 0.55 meq / g, 0.50 meq / g, 0.45 meq / g, 0.40 meq / g, 0.38 meq / g, 0.35 meq / g, 0.32 meq / g, 0.30 meq / g, 0.24 meq / g, 0.21 meq / g, 0.20 meq / g, 0.19 meq / g, 0.17 meq / g, 0.16 meq / g, 0.15 meq / g, 0.10 meq / g, 0.08 meq / g, 0.05 meq / g, and the like, or may be a range determined by two values ​​selected from these values.

[0032] In the molded body of this embodiment, the caramel decolorization rate of the activated carbon layer obtained by cutting out a part of the molded body (hereinafter also simply referred to as "caramel decolorization rate of the activated carbon layer") is preferably 35% or more.

[0033] The higher the caramel decolorization rate of the activated carbon layer, the higher the PFAS removal performance of the activated carbon itself contained in the molded body, which is preferable. The following reasons are considered to be the reasons for this. First, caramel is removed with high efficiency in activated carbon with relatively large pores. The pore regions of activated carbon where caramel is easily removed are similar to the pore regions of activated carbon where PFAS is thought to be easily introduced into the activated carbon during the process of PFAS adsorption to the activated carbon. Therefore, the higher the caramel decolorization rate of the activated carbon layer, the higher the PFAS removal performance of the molded body tends to be. From this perspective, the caramel decolorization rate of the activated carbon layer is preferably 35% or more, more preferably 40% or more, and particularly preferably 45% or more. Furthermore, there is no particular upper limit to the caramel decolorization rate of the activated carbon layer, and it may be 100% or less.

[0034] Specifically, the caramel decolorization rate of the activated carbon layer is, for example, preferably 35% to 100%, more preferably 40% to 99%, and even more preferably 45% to 98%.

[0035] Specifically, the caramel decolorization rate of the activated carbon layer may be a value selected from 37%, 39%, 47%, 51%, 53%, 55%, 58%, 60%, 65%, 66%, 69%, 70%, 73%, 80%, 85%, etc., or may be a range set by setting a value selected from these as the lower limit. The upper limit of the caramel decolorization rate of the activated carbon layer is not particularly limited as long as a sufficient amount of activated carbon can be retained inside the molded body and the shape of the molded body can be maintained. For example, the caramel decolorization rate of the activated carbon layer may be a value selected from 90%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc., or may be a range set by setting a value selected from these as the upper limit.

[0036] [Configuration of Molded Body] The molded body in this embodiment contains activated carbon and a binder.

[0037] (Activated Carbon) The activated carbon used as the raw material for the molded body in this embodiment preferably has a volume-based cumulative particle size distribution in which the content of particles having a particle diameter of 50 μm to 100 μm (hereinafter also simply referred to as "content of particles having a particle diameter of 50 μm to 100 μm") is 10% by volume or more, and D90 is 300 μm or less.

[0038] In this specification, "D90" means the 90% particle size in a volume-based cumulative particle size distribution, "D50" means the 50% particle size in a volume-based cumulative particle size distribution, and "D10" means the 10% particle size in a volume-based cumulative particle size distribution.

[0039] Specifically, by using activated carbon as the raw material that satisfies the conditions of a particle content of 50 μm to 100 μm in particle diameter of 10% by volume or more and a D90 of 300 μm or less, it is possible to easily produce a molded body in which the volume of voids with diameters of 1 μm to 30 μm occupies a range of 20% or more.

[0040] When the content of particles with a particle diameter of 50 μm to 100 μm in the raw material activated carbon is 10% by volume or more, it is easy to form a void volume with a diameter of 1 μm to 30 μm and the void volume of that diameter can be increased. Furthermore, when the D90 of the raw material activated carbon is 300 μm or less, it is possible to avoid the inclusion of a large amount of activated carbon with an excessively large particle diameter and to easily form a void volume with a diameter of 1 μm to 30 μm.

[0041] From the viewpoint of being able to particularly stably increase the volume of voids with diameters of 1 μm to 30 μm, the content of particles with particle diameters of 50 μm to 100 μm is, for example, preferably 15.0 vol% to 50.0 vol%, more preferably 17.0 vol% to 50.0 vol%, and even more preferably 17.4 vol% to 39.1 vol%.

[0042] Specifically, the content of particles having a particle diameter of 50 μm to 100 μm in the raw material activated carbon may be a value selected from 11.0 vol%, 12.0 vol%, 13.0 vol%, 14.0 vol%, 15.0 vol%, 16.0 vol%, 17.0 vol%, 17.4 vol%, 18.0 vol%, 19.0 vol%, 20.0 vol%, 20.1 vol%, 20.8 vol%, 22.0 vol%, 24.0 vol%, 25.1 vol%, etc., or may be a range set by setting a value selected from these as the lower limit.

[0043] The upper limit of the particle content of particles having a particle diameter of 50 μm to 100 μm is not particularly limited as long as a molded body having a void volume ratio of 1 μm to 30 μm in diameter of 20% or more can be finally produced, a sufficient amount of activated carbon can be retained inside the produced molded body, and the shape of the molded body can be maintained. For example, the particle content of particles having a particle diameter of 50 μm to 100 μm may be a value selected from 80.0 vol%, 60.0 vol%, 55.0 vol%, 50.0 vol%, 45.0 vol%, 40.0 vol%, 39.1 vol%, etc., or may be a range set by setting a value selected from these as the upper limit.

[0044] From the viewpoint of being able to particularly stably increase the volume of voids with a diameter of 1 μm to 30 μm, the D90 of the raw material activated carbon is, for example, preferably 80 μm to 260 μm, more preferably 90 μm to 240 μm, and even more preferably 97 μm to 228 μm.

[0045] Specifically, the D90 of the raw material activated carbon may be a value selected from 290 μm, 280 μm, 270 μm, 260 μm, 250 μm, 240 μm, 230 μm, 228 μm, 223 μm, 220 μm, etc., or may be within a range set by setting a value selected from these as the upper limit value.

[0046] The lower limit of D90 is not particularly limited as long as it is possible to finally produce a molded body having a void volume ratio of 1 μm to 30 μm in diameter of 20% or more, a sufficient amount of activated carbon can be retained inside the produced molded body, and the shape of the molded body can be maintained. For example, D90 may be a value selected from 20 μm, 30 μm, 40 μm, 50 μm, 70 μm, 80 μm, 86 μm, 90 μm, 97 μm, etc., or may be a range set by setting a value selected from these as the lower limit.

[0047] The D50 and D10 of the raw activated carbon are not particularly limited as long as a molded body having a void volume ratio of 1 μm to 30 μm in diameter of 20% or more can be finally produced, a sufficient amount of activated carbon can be retained inside the produced molded body, and the shape of the molded body can be maintained. Alternatively, D50 and D10 are preferably adjusted so that the raw activated carbon has a particle content of 50 μm to 100 μm in particle diameter of 10% by volume or more and a D90 of 300 μm or less.

[0048] From the viewpoint of being able to particularly stably increase the void volume of diameters of 1 μm to 30 μm, D50 is, for example, preferably 25 μm to 180 μm, more preferably 30 μm to 160 μm, and even more preferably 38 μm to 149 μm. Specifically, D50 may be a value selected from 20 μm, 30 μm, 38 μm, 45 μm, 60 μm, 75 μm, 90 μm, 110 μm, 130 μm, 149 μm, 160 μm, 180 μm, 200 μm, etc., or may be a range set by two values ​​selected from these.

[0049] From the viewpoint of being able to particularly stably increase the volume of voids with a diameter of 1 μm to 30 μm, D10 is, for example, preferably 10 μm to 120 μm, more preferably 13 μm to 100 μm, and even more preferably 16 μm to 81 μm. For example, D10 may be a value selected from 10 μm, 12 μm, 16 μm, 18 μm, 25 μm, 35 μm, 60 μm, 70 μm, 81 μm, 90 μm, 100 μm, 120 μm, 140 μm, etc., or may be a range set by two values ​​selected from these.

[0050] The type of raw material activated carbon having such a particle content of 50 μm to 100 μm in particle diameter and D90 (and further D50 and D10) is not particularly limited, and it can be used alone or in combination of two or more types of activated carbon with different physical properties.

[0051] The content of particles having a particle diameter of 50 μm to 100 μm and D90 (and further D50 and D10) of the raw material activated carbon described above can be controlled by, for example, appropriately selecting and adjusting the type of carbonaceous material used as the raw material for the activated carbon, the activation treatment method and treatment conditions (heating temperature, time, etc.) of the carbonaceous material during the production of the activated carbon, as described below. Furthermore, in this specification, the content of particles having a particle diameter of 50 μm to 100 μm and D90 (and further D50 and D10) of the raw material activated carbon can be analyzed and measured, for example, by a laser diffraction / scattering method using a wet particle size distribution analyzer (Microtrac MT3300EX-II manufactured by Microtrac-Bell) or the like, as described in the Examples below.

[0052] The activated carbon used as the raw material for the molded body in this embodiment preferably has a mesopore volume of the activated carbon calculated by the BJH method relative to the total pore volume of the mesopores of the activated carbon calculated by the BJH method from the nitrogen adsorption isotherm and the micropore volume of the activated carbon calculated by the MP method (hereinafter, also simply referred to as the "mesopore volume ratio of the raw material activated carbon") of 5% to 30%. A mesopore volume ratio of greater than 5% can facilitate the introduction of PFAS into the activated carbon. Furthermore, in situations where a certain level of water flow rate is required through the molded body, such as when the molded body is used as a water purification filter, the PFAS removal performance of the molded body may be improved. On the other hand, a mesopore volume ratio of less than 30% can maintain the adsorption and retention capacity of PFAS introduced into the activated carbon, thereby improving the PFAS removal performance of the molded body.

[0053] The pores of activated carbon can be classified according to their diameter into micropores (diameter less than 2 nm), mesopores (diameter 2 nm to 50 nm), and macropores (diameter greater than 50 nm) (the numbers in parentheses indicate the IUPAC classification criteria). Mesopores are larger than micropores, and the volume of mesopores can be an indicator of the adsorption properties of substances with large molecular sizes. In other words, the volume of mesopores can be an indicator of the PFAS removal performance of the raw activated carbon itself. Furthermore, the proportion of the pore volume of mesopores in activated carbon is related to the degree of activation of the raw activated carbon.

[0054] The molded body of this embodiment can effectively remove PFAS regardless of the degree of activation of the activated carbon, so long as the molded body satisfies the condition regarding the ratio of pore volume within the diameter range of 1 μm to 30 μm. However, if the ratio of the mesopore volume is 5% to 30%, a molded body that can more reliably and effectively remove PFAS can be obtained. The ratio of the mesopore volume of the raw material activated carbon is, for example, preferably 5.5% to 30.0%, more preferably 6.0% to 27.0%, and even more preferably 6.5% to 25.0%.

[0055] Specifically, the pore volume ratio of mesopores in the raw material activated carbon may be a value selected from 5.5%, 6.0%, 6.7%, 7.1%, 8.0%, 9.0%, 9.9%, 10.0%, 11.0%, 11.6%, 15.0%, 20.0%, 20.8%, 23.0%, etc., or may be within a range determined by two values ​​selected from these.

[0056] The pore volume (ml / g) of mesopores with pore diameters in the range of 2 nm to 50 nm in such activated carbon can be calculated from the nitrogen adsorption isotherm of the activated carbon by applying the BJH (Barrett-Joyner-Hallenda) method, which is used to analyze mesopores in porous bodies (pores with pore diameters of 2 nm to 50 nm or less). Furthermore, in this specification, the proportion of the mesopore volume of the raw material activated carbon can be calculated by dividing the mesopore volume (ml / g) calculated by the BJH method by the sum of the mesopore volume calculated by the BJH method and the micropore volume calculated by the MP method, as will be described in detail in the Examples below.

[0057] Furthermore, the activated carbon used as the raw material for the molded body in this embodiment preferably has a benzene saturation adsorption capacity of 25% to 60%.

[0058] The benzene saturation adsorption capacity is an index showing the degree of activation of the raw material activated carbon. The molded body of this embodiment can effectively remove PFAS regardless of the degree of activation of the activated carbon, as long as it satisfies the condition regarding the ratio of void volume within a diameter range of 1 μm to 30 μm of the molded body. However, if the benzene saturation adsorption capacity is 25% to 60%, a molded body that can more reliably and effectively remove PFAS can be obtained. The benzene saturation adsorption capacity of the raw material activated carbon is more preferably 27% to 55%, and even more preferably 29% to 51%.

[0059] Specifically, the saturated benzene adsorption capacity of the raw material activated carbon may be a value selected from 25%, 26%, 27%, 28%, 29%, 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 58%, 59%, etc., or may be within a range determined by two values ​​selected from these values.

[0060] In this specification, the saturated benzene adsorption amount of the raw material activated carbon can be measured by the method specified in JIS K 1474:2014, which will be described in detail in the Examples below.

[0061] The mesopore volume ratio and saturated benzene adsorption capacity of the raw material activated carbon can also be controlled by, for example, appropriately selecting and adjusting the type of carbonaceous material used as the raw material for the activated carbon (described later) and the activation treatment method and treatment conditions (heating temperature, time, etc.) for the carbonaceous material during production of the activated carbon.

[0062] The activated carbon used as the raw material may be a commercially available product. Alternatively, activated carbon may be used that is obtained by, for example, optionally carbonizing a carbonaceous material that serves as the raw material for the activated carbon, followed by an activation treatment, and optionally washing, drying, and pulverizing the carbonaceous material.

[0063] The carbonaceous material used as the raw material is not particularly limited, and examples thereof include plant-based carbonaceous materials (e.g., plant-derived materials such as wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, rice husks, pulp manufacturing by-products, lignin, and blackstrap molasses), mineral-based carbonaceous materials (e.g., mineral-derived materials such as peat, lignite, brown coal, bituminous coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, and petroleum pitch), synthetic resin-based carbonaceous materials (e.g., synthetic resin-derived materials such as phenolic resin, polyvinylidene chloride, and acrylic resin), and natural fiber-based carbonaceous materials (e.g., natural fiber-derived materials such as natural fibers such as cellulose and recycled fibers such as rayon). These carbonaceous materials may be used alone or in combination of two or more.

[0064] When carbonization is required, these carbonaceous materials can be carbonized, for example, at about 400°C to 800°C in an environment that is generally shielded from oxygen or air. After that, particle size adjustment may be performed as necessary. Furthermore, when the carbonaceous material is bituminous coal or the like, it is preferable to perform a carbonization treatment before the activation treatment. Conventional means can be used for the carbonization treatment. For example, the carbonization treatment can be performed at a temperature of about 400°C to 800°C while shielding from oxygen or air.

[0065] The carbonaceous material is then subjected to an activation treatment. The activation treatment can be performed by a method commonly used in the art and is not particularly limited, and mainly includes two types of treatment methods: gas activation treatment and chemical activation treatment. Of these, when used for water purification treatment, gas activation treatment is preferred from the viewpoint of leaving fewer impurities behind.

[0066] Gas activation is a process in which a carbonaceous material is heated in the presence of, for example, water vapor, carbon dioxide, air, oxygen, combustion gas, or a mixture thereof. The heating temperature is not particularly limited, but is typically about 700°C to 1100°C. The activation time and heating rate are also not particularly limited, and can be adjusted appropriately depending on the type, shape, and size of the selected carbonaceous material. Considering safety and reactivity, it is preferable to use a water vapor-containing gas containing 10% to 40% water vapor by volume. Chemical activation may be performed using a known method in which an activator such as zinc chloride, calcium chloride, phosphoric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, magnesium hydroxide, or calcium hydroxide is mixed with the carbonaceous material and heated under an inert gas atmosphere.

[0067] The activated carbon after activation treatment is washed and dried as necessary. Specifically, when the raw material for activated carbon is a plant-based carbonaceous material such as coconut shell or a mineral-based carbonaceous material containing impurities such as alkali metals, alkaline earth metals, and transition metals, washing is performed as necessary to remove ash, chemicals, etc. Mineral acid or water is used for washing, and hydrochloric acid is preferred as the mineral acid because of its high washing efficiency.

[0068] The activated carbon after activation treatment is subjected to pulverization and / or classification as necessary. The pulverization can be carried out using a pulverizer generally used for pulverizing activated carbon, such as aerofoil mills, rod mills, roller mills, hammer mills, blade mills, pin mills, and other high-speed rotary mills, ball mills, jet mills, etc. The classification can be performed using methods generally used for classifying activated carbon, such as sieve classification, wet classification, and dry classification. Examples of wet classifiers include classifiers that utilize the principles of gravity classification, inertia classification, hydraulic classification, centrifugal classification, etc. Examples of dry classifiers include classifiers that utilize the principles of sedimentation classification, mechanical classification, centrifugal classification, etc.

[0069] The activated carbon obtained through such a treatment or commercially available activated carbon may be in any form, such as powder, particles, or fibers (thread, woven fabric (cloth), felt, etc.), and can be appropriately selected depending on the application. Among these forms, powder, which has high adsorption performance per volume, is preferred.

[0070] (Binder) The binder used in the molded body in this embodiment is not particularly limited, and a powdery or fibrous binder may be used alone or in combination of two or more. Among these, it is preferable to include a fibrous binder from the viewpoint of excellent water permeability when the produced molded body is used as, for example, a water purification filter.

[0071] The fibrous binder is not particularly limited as long as it can be entangled with activated carbon and shaped, and a wide range of synthetic and natural binders can be used. Examples of such binders include acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, cellulose fibers, nylon fibers, aramid fibers, and pulp.

[0072] The fibrous binder preferably includes an acrylic fibrous binder. Furthermore, the fibrous binder more preferably includes a cellulose fibrous binder. Furthermore, two or more of these fibrous binders may be used in combination. For example, it is more preferable to use both an acrylic fibrous binder and a cellulose fibrous binder in combination.

[0073] In this embodiment, the water permeability of the fibrous binder is preferably about 1 mL to 200 mL, more preferably about 10 mL to 150 mL, in terms of CSF value. Here, in this specification, the CSF value is a value measured with reference to the Canadian Standard Freeness Method, "Testing Method for Pulp Freeness" specified in JIS P 8121:2012. Note that when two or more types of fibrous binders are used in combination, it is preferable that the CSF value of the two or more types of fibrous binders in a mixed state falls within the above range.

[0074] The blending ratio of activated carbon to binder is not particularly limited and may be appropriately set so as to obtain a molded body having a void volume ratio of 1 μm to 30 μm in diameter of 20% or more. For example, the blending ratio is preferably about 3 to 10 parts by mass of binder per 100 parts by mass of activated carbon.

[0075] (Optional Components) The molded body of this embodiment may contain other optional functional components as long as the PFAS removal effect is not impaired. Examples include zeolite powder (lead adsorbent), ion exchange resin, or chelating resin, which can adsorb and remove soluble lead. The amount of these other optional components added is not particularly limited as long as a molded body having a void volume ratio of 1 μm to 30 μm in diameter of 20% or more can be finally produced. For example, 1 to 30 parts by mass of these optional components can be added per 100 parts by mass of the entire molded body.

[0076] The molded body containing activated carbon and a binder in this embodiment may further include a core and be a cylindrical molded body. The cylindrical shape reduces water flow resistance, making it suitable for use as a water purification filter, etc. Furthermore, as described below, when the molded body as a water purification filter is filled into a housing and used as a cartridge, there is an advantage in that the cartridge can be easily loaded into a water purifier and replaced.

[0077] The core is not particularly limited as long as it can be inserted into the hollow portion of the cylindrical molded body and can reinforce the cylindrical molded body. Examples include toric pipe, Netron pipe, ceramic filter, etc. Furthermore, the core can also be used by wrapping a nonwoven fabric around its outer periphery.

[0078] [Method for Producing Molded Body] The method for producing the molded body in this embodiment may be any method known to those skilled in the art, and is not particularly limited. From the viewpoint of efficient production, a slurry suction method is preferred.

[0079] Hereinafter, a method for manufacturing a cylindrical molded body will be described in detail as an example of a method for manufacturing a molded body in this embodiment, but the present invention is not limited to this manufacturing method.

[0080] Specifically, for example, the cylindrical molded body in this embodiment can be produced by a method including a slurry preparation step, a suction filtration step, an optional rolling step, a drying step, and an optional grinding step. In the slurry preparation step, powdered activated carbon and a fibrous binder are dispersed in water to prepare a slurry. In the suction filtration step, the prepared slurry is filtered while being suctioned to obtain a preformed body. In the rolling step, the preformed body after suction filtration is compressed on a shaping table to shape the outer surface as needed. In the drying step, the shaped preformed body is dried to obtain a dried molded body. In the grinding step, the outer surface of the dried molded body is ground as needed. Each step will be described in detail below.

[0081] (Slurry Preparation Step) In the slurry preparation step, a slurry is prepared by dispersing powdered activated carbon and a fibrous binder in a solvent so that the solid content concentration is, for example, 0.1% by mass to 10% by mass. The solvent is not particularly limited, but it is preferable to use water or the like. One factor for controlling the void volume of a predetermined diameter in the finally obtained molded body within a desired range is to appropriately adjust the solid content concentration of the slurry in the slurry preparation step.

[0082] (Suction Filtration Process) The suction filtration process will be described with reference to FIG. 1. In FIG. 1, the respective symbols represent a mold 1, a core 2, suction holes 3, flanges 4, 4', and a filtrate outlet 5. In the suction filtration process, for example, as shown in FIG. 1, a mold 1 for a cylindrical molded body is used, which has a number of suction holes 3 on the surface of a core 2, flanges 4, 4' attached to both ends, and a filtrate outlet 5. First, a core as described above is attached to the mold 1, which is placed in the prepared slurry. The slurry is then filtered while being sucked from the inside of the mold 1 through the filtrate outlet 5, thereby adhering the slurry to the mold 1. As a suction method, a conventional method, such as a method using a suction pump, can be used. In this way, the preform is adhered to the mold 1. Furthermore, the desired pore structure can be obtained by controlling the suction force in this suction filtration process.

[0083] (Rolling Step) If necessary, a rolling step can be performed after the suction filtration step to adjust the outer diameter of the preform. In the rolling step, the mold 1 with the preform obtained in the suction filtration step still attached thereto is placed on a table and moved back and forth while being pressed down with a predetermined force. Note that such an optional rolling step can also lead to a reduction in the void volume of the relatively large diameter of the molded body.

[0084] The suction filtration step and the rolling step, which are performed as needed, may be performed any number of times.

[0085] (Drying Step) Next, the flanges 4, 4' at both ends of the mold 1 are removed, and the core 2 is extracted. This allows a hollow cylindrical preform to be obtained. In the drying step, the preform removed from the mold 1 is dried in a dryer or the like, allowing the molded body 6 shown in FIG. 2 to be obtained. The drying temperature is, for example, about 100°C to 150°C. The drying time is, for example, about 4 to 24 hours.

[0086] (Grinding step) If necessary, after the drying step, a grinding step can be carried out to further adjust the outer diameter of the molded body or to reduce unevenness on the outer peripheral surface. The grinding method is not particularly limited as long as it can grind (or polish) the outer surface of the dried molded body, and any grinding method known to those skilled in the art can be used. From the viewpoint of grinding uniformity, a method using a grinding machine that rotates and grinds the molded body itself is preferred.

[0087] [Uses of Molded Article] The molded article of this embodiment can be suitably used as a molded article for removing PFAS. For example, the molded article of this embodiment can be suitably used as a water purification filter for removing PFAS. When used as a water purification filter, for example, the molded article can be produced by the method described above, and then cut into a size and shape suitable for use as a water purification filter. Furthermore, if necessary, a cap may be attached to the tip of the molded article as a water purification filter. Furthermore, the molded article as a water purification filter can also be used in combination with known nonwoven fabric filters, various adsorbents, mineral additives, ceramic filtering materials, etc.

[0088] When the molded article of this embodiment is used as a water purification filter, it can be filled into a housing and used as a water purification cartridge. The water purification cartridge is loaded into a water purifier and used to pass water through it.

[0089] <Method for Removing Perfluoroalkyl Compounds and / or Polyfluoroalkyl Compounds> The method for removing perfluoroalkyl compounds and / or polyfluoroalkyl compounds in this embodiment includes using the molded article in the above-described embodiment. For example, the molded article in the above-described embodiment may be cut to a desired size and shape and used, or the molded article may be used as a cylindrical water purification filter as described above, thereby making it possible to suitably remove PFAS.

[0090] The outline of the present invention has been explained above. The molded article and the method for removing perfluoroalkyl compounds and / or polyfluoroalkyl compounds in this embodiment can be summarized as follows.

[0091] A molded body according to a first aspect of the present invention is a molded body containing activated carbon and a binder, wherein the volume of voids having a diameter of 1 μm to 30 μm inside the molded body measured by mercury porosimetry is 20% or more of the volume of all voids inside the molded body measured by mercury porosimetry.

[0092] A molded body according to a second aspect of the present invention is the molded body according to the first aspect, wherein in a cumulative particle size distribution on a volume basis of the activated carbon, the content of particles having a particle diameter of 50 μm to 100 μm is 10% by volume or more, and D90 is 300 μm or less.

[0093] A molded body according to a third aspect of the present invention is the molded body according to the first or second aspect, wherein the activated carbon layer obtained by cutting out a part of the molded body has a total amount of acidic functional groups of 0.7 meq / g or less.

[0094] A molded body according to a fourth aspect of the present invention is a molded body according to any one of the first to third aspects, wherein the caramel decolorization rate of an activated carbon layer obtained by cutting out a part of the molded body is 35% or more.

[0095] A molded body according to a fifth aspect of the present invention is the molded body according to any one of the first to fourth aspects, wherein the benzene saturation adsorption amount of the activated carbon is 25% to 60%.

[0096] A molded body according to a sixth aspect of the present invention is the molded body according to any one of the first to fifth aspects, wherein the ratio of the mesopore volume of the activated carbon calculated by the BJH method to the total pore volume of the mesopores of the activated carbon calculated by the BJH method from the nitrogen adsorption isotherm and the micropore volume of the activated carbon calculated by the MP method is 5% to 30%.

[0097] A molded article according to a seventh aspect of the present invention is a molded article according to any one of the first to sixth aspects, and is used for removing perfluoroalkyl compounds and / or polyfluoroalkyl compounds.

[0098] A method for removing perfluoroalkyl compounds and / or polyfluoroalkyl compounds according to an eighth aspect of the present invention comprises using the molded article according to any one of the first to seventh aspects.

[0099] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0100] First, the raw materials used in the production of the molded bodies in each Example and Comparative Example, the methods for measuring the physical properties of the raw material activated carbon (powdered activated carbon), and the methods for measuring the physical properties and performance of the produced molded bodies will be described in detail.

[0101] [Raw material for molded body] (Raw material activated carbon) Hereinafter, a manufacturing method of the activated carbon (powdered activated carbon) used as the raw material will be described, but the manufacturing method is not particularly limited as long as the required physical properties are satisfied. Furthermore, Figure 3 shows a graph of the particle size distribution (cumulative volume (%)) of the activated carbon (powdered activated carbon) described below.

[0102] Powdered activated carbon A: Coconut shell charcoal obtained by carbonizing coconut shells from the Philippines was activated with steam at 900°C, and the resulting coconut shell activated carbon was washed with dilute hydrochloric acid and desalted with ion-exchanged water to obtain granular activated carbon. The obtained granular activated carbon was pulverized in a roll mill to obtain powdered activated carbon A, which exhibited the particle size distribution shown in Figure 3 and had a D10 of 39 μm, a D50 of 123 μm, and a D90 of 197 μm.

[0103] Powdered activated carbon B Granular activated carbon was obtained in the same manner as in the preparation of powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon B having a particle size distribution as shown in FIG. 3 and having D10 of 34 μm, D50 of 106 μm, and D90 of 184 μm.

[0104] Powdered activated carbon C Granular activated carbon was obtained in the same manner as in the preparation of powdered activated carbon A, and the obtained granular activated carbon was pulverized in a ball mill to obtain powdered activated carbon C having a particle size distribution as shown in FIG. 3 and having D10 of 16 μm, D50 of 38 μm, and D90 of 86 μm.

[0105] Powdered activated carbon D Granular activated carbon was obtained in the same manner as in the preparation of powdered activated carbon A, and the obtained granular activated carbon was pulverized in a roll mill and then dry-classified. Finally, powdered activated carbon D was obtained, which had a particle size distribution as shown in Figure 3 and a D10 of 78 µm, a D50 of 146 µm, and a D90 of 228 µm.

[0106] Powdered activated carbon E: Bituminous coal was carbonized at 700°C, and the carbonized product was activated at 750°C using a mixed gas containing water vapor, carbon dioxide, and nitrogen. The resulting granular activated carbon was pulverized in a roll mill and then dry-classified. Finally, powdered activated carbon E was obtained, which exhibited the particle size distribution shown in Figure 3 and had a D10 of 64 μm, a D50 of 149 μm, and a D90 of 223 μm.

[0107] Powdered activated carbon F Granular activated carbon was obtained in the same manner as in powdered activated carbon A, and the obtained granular activated carbon was pulverized in a roll mill and then dry-classified. Finally, powdered activated carbon F was obtained, which had a particle size distribution as shown in Figure 3 and a D10 of 81 µm, a D50 of 139 µm, and a D90 of 212 µm.

[0108] Powdered activated carbon G: Woody raw material was impregnated with phosphoric acid, activated at 500°C, washed with water, and then dried to obtain woody activated carbon. The obtained woody activated carbon was then dry-classified. The classified woody activated carbon was then mixed with the aforementioned powdered activated carbon B in a weight ratio of (woody activated carbon):(powdered activated carbon B) = 85:15. Finally, powdered activated carbon G was obtained, which exhibited the particle size distribution shown in Figure 3, with a D10 of 26 μm, a D50 of 54 μm, and a D90 of 97 μm.

[0109] Powdered activated carbon H Granular activated carbon was obtained in the same manner as in powdered activated carbon A, and the obtained granular activated carbon was pulverized in a roll mill with a wide gap between the rolls, followed by dry classification. Finally, powdered activated carbon H was obtained, which had a particle size distribution as shown in Figure 3 and a D10 of 148 µm, a D50 of 222 µm, and a D90 of 305 µm.

[0110] The physical properties of the activated carbons used as raw materials for the above-mentioned powdered activated carbons A to H are summarized in Table 2 below, along with the physical properties and performance measurement results of the molded bodies of each Example and Comparative Example produced using the activated carbons. Table 2 also shows, as physical properties of the raw activated carbons, the content of particles with particle diameters of 50 μm to 100 μm in the raw activated carbons described above, measured by the method described below.

[0111] (Binders) Acrylic fibrous binder: "Acrylic fiber Bi-PUL / F" manufactured by Nippon Exlan Kogyo Co., Ltd., CSF value 83 mL Cellulose fibrous binder: "Cerish PC110S" manufactured by Daicel Miraizu Co., Ltd. (CSF value of 28 mL when 50 parts by mass of the cellulose fibrous binder is blended with 100 parts by mass of the acrylic fibrous binder (CSF value 83 mL))

[0112] (Others) Titanosilicate lead adsorbent: "ATS" manufactured by Solenis, average particle size 20 μm Core: "MF filter (30 μm)" manufactured by Asahi Textile Industries Co., Ltd. Nonwoven fabric: "9540-F" manufactured by Shinwa Co., Ltd.

[0113] [Measurement of particle size distribution of raw activated carbon] The D10 (μm), D50 (μm), and D90 (μm) of the raw activated carbon, as well as the particle content (volume %) of particles with particle diameters of 50 μm to 100 μm, were measured by laser diffraction / scattering. That is, the activated carbon to be measured was placed in ion-exchanged water together with a surfactant, and ultrasonic vibrations were applied to create a uniform dispersion, which was then measured using a wet particle size distribution analyzer (Microtrac MT3300EX-II, manufactured by Microtrac-Bell). The surfactant used was "Polyoxyethylene (10) octylphenyl ether" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. The analytical conditions are shown below.

[0114] (Analysis conditions) Number of measurements: average of 3 measurements Measurement time: 30 seconds Distribution display: volume Particle size range: standard Calculation mode: MT3000II Solvent name: WATER Upper measurement limit: 2000 μm, lower measurement limit: 0.021 μm Remaining ratio: 0.00 Passing ratio: 0.00 Remaining ratio setting: disabled Particle permeability: absorption Particle refractive index: N / A Particle shape: N / A Solvent refractive index: 1.333 DV value: 0.0882 Transmittance (TR): 0.880-0.900 Extension filter: disabled Flow rate: 70% Ultrasonic output: 40 W Ultrasonic time: 180 seconds

[0115] [Measurement of Saturated Benzene Adsorption Capacity (%) of Raw Activated Carbon] The saturated benzene adsorption capacity (%) of the raw activated carbon was determined in accordance with the test method specified in JIS K 1474:2014 by passing air containing solvent vapor at 1 / 10 of the solvent saturation concentration through the sample at 25°C, and measuring the increase in sample weight (%) when the mass became constant.

[0116] [Measurement of the pore volume ratio of mesopores (diameter 2 nm to 50 nm) in raw activated carbon] Using a gas adsorption measurement device (BELSORP-MAX II manufactured by Microtrac-Bell Corporation), the raw activated carbon to be measured was heated at 300°C for 3 hours under a nitrogen stream (nitrogen flow rate: 50 mL / min), and then the nitrogen adsorption isotherm of the activated carbon at 77 K was measured. Furthermore, the BJH method was applied to the obtained nitrogen adsorption isotherm, and the pore volume (ml / g) of mesopores with pore diameters in the pore diameter range of 2 nm to 50 nm among the pores possessed by the activated carbon to be measured was calculated in the relative pressure P / P0 range of 0.10 to 0.99. In the analysis by the BJH method, the adsorbate molecular weight was set to 28.013 and the adsorbate density was set to 0.808 g / cm. ３ The file data interpolation method was a straight line. The pore volume (ml / g) of micropores with a pore diameter of less than 2 nm was calculated using the MP method. The standard curve "NGCB-BEL.t" provided by Microtrac-Bel Co., Ltd. was used for the analysis of the MP method. Finally, the mesopore volume calculated by the BJH method was divided by the sum of the mesopore volume calculated by the BJH method and the micropore volume calculated by the MP method to calculate the ratio (%) of the mesopore volume (to the total pore volume of the mesopore volume and the micropore volume).

[0117] [Measurement of Density of Molded Body] The density of the molded body (g / cm ３ The density of the molded body was calculated according to the following formula after drying the obtained molded body at 120°C for 2 hours. The density of the molded body refers to the density of the molded layer of activated carbon only. Density of molded body = (mass of the molded layer of activated carbon of the molded body) / (volume of the molded layer of activated carbon of the molded body)

[0118] [Measurement of pore volume of molded body using mercury porosimeter] The pore volume of the molded body was measured using a mercury intrusion pore volume measuring device (MicroActive AutoPore V 9620, manufactured by Micromeritics). The measurement pressure was 0.7 kPa to 420 MPa. After cutting out the molded layer consisting of activated carbon and binder from the cylindrical molded body as shown in Figure 4, the cut piece was further cut into pieces approximately 1 cm square. The pore volume (cm) of the cut sample of approximately 1 cm square with a diameter of 1 μm to 30 μm was measured based on the weight of the molded body. ３ / g) and total void volume (cm ３ These values ​​were multiplied by the density of the molded body determined by the above-mentioned method to calculate the void volume (cm) of 1 μm to 30 μm in diameter based on the volume of the molded body. ３ / cc) and total void volume (cm ３ Further, from these values, the ratio (%) of the void volume of the molded body having a diameter of 1 μm to 30 μm (to the total void volume) was calculated.

[0119] [Measurement of Total Acidic Functional Group Amount (meq / g)] The total acidic functional group amount (meq / g) of the activated carbon layer of the molded body was measured by the following method. First, a portion of the activated carbon layer of the molded body was cut out with a utility knife and finely pulverized until the average particle size of the cut-out sample was 2 mm or less. Next, the pulverized sample was dried at 115°C for 3 hours and then allowed to cool to room temperature in a desiccator. 1.0 g of the cooled sample was weighed and used as a measurement sample. Furthermore, 1.0 g of the measurement sample was added to 50 mL of 0.1 mol / L aqueous sodium hydroxide solution, and the solution was shaken for 30 minutes and then allowed to stand at 25°C for 24 hours. The solution was then centrifuged, and 10 mL of the supernatant was collected. The collected 10 mL of the supernatant was then subjected to neutralization titration with 0.1 mol / L hydrochloric acid solution to determine the total acidic functional group amount (meq / g) of the molded body.

[0120] [Measurement of caramel decolorization performance] The caramel decolorization performance of the activated carbon layer of the molded body was measured with reference to the method specified in JIS K 1474:2014. Specifically, the caramel decolorization rate (%) of the activated carbon layer of the molded body at 25°C was determined by measuring the absorbance of the caramel test liquid and the filtrate of the caramel test liquid after adsorption by a powder sample of the activated carbon layer of the molded body. The powder sample of the activated carbon layer was prepared by cutting out a portion of the activated carbon layer of the molded body with a cutter knife and pulverizing the cut-out fragment using a sample mill.

[0121] [Measurement of PFAS Removal Performance] The PFAS removal performance of the molded body was measured by the following method in accordance with JWPAS B.210 "Standards for Testing Methods of Removal Performance, etc. of Water Purifiers" (Japan Water Purifier Association). First, diluted water with PFOS and PFOA concentrations of 25 ppt±5 ppt each was prepared, and the temperature of the diluted water was adjusted to 20±3°C to prepare test water. This test water was flowed from the outside to the inside of the cylindrical molded body at a flow rate of SV1200 / hr relative to the volume of activated carbon, and the test water and treated water were simultaneously collected over time to prepare samples. The PFOS and PFOA concentrations in these samples were measured by liquid chromatography-mass spectrometry, and the removal rates (%) were calculated. Furthermore, the cumulative amount of water passing through per volume of molded product at the time when the PFOS and PFOA removal rates became less than 80% was calculated as the PFOS and PFOA removal rate life (L / cc). In this test, a PFOS and PFOA removal rate life (L / cc) of 15 L / cc or more was considered acceptable, and the molded product was evaluated as being capable of effectively removing PFOS and PFOA for a long period of time.

[0122] Next, the manufacturing method of the molded body in each example and comparative example will be described in detail.

[0123] Example 1 Powdered activated carbon A and an acrylic fibrous binder were mixed in the proportions shown in Table 1 below to prepare a total of 1.2 kg, and tap water was added to the mixture. The volume of the slurry after the addition was 20 L.

[0124] Next, a core (outer diameter 35 mmφ, inner diameter 30.5 mmφ, height 245 mmH) was attached to a cylindrical molding frame (outer diameter 63 mmφ, center shaft diameter 30 mmφ, and height 245 mmH) with multiple 3 mm diameter suction holes as shown in Figure 1, and the slurry obtained by the above-mentioned method was sucked using this at 450 mmHg until the outer diameter reached 73 mmφ, thereby obtaining a preform.The outer surface of the obtained preform was then rolled until the outer diameter of the obtained preform reached 63 mmφ.The molded body was then dried, and finally, a hollow cylindrical molded body with an outer diameter of 63 mmφ, an inner diameter of 35 mmφ, and a height of 245 mmH was obtained.

[0125] The density, void volume, total amount of acidic functional groups, and caramel decolorizing performance of the molded body of Example 1 thus produced were measured by the methods described above. The physical properties and performance measurement results of the molded body of Example 1 are summarized in Table 2 below.

[0126] In addition, a nonwoven fabric was wrapped around the outer periphery of the produced molded body, and gaskets were attached to both ends of the molded body. Furthermore, the molded body with the nonwoven fabric wrapped around it and the gaskets attached was loaded into a transparent plastic housing with an average diameter of 79 mm, a length of approximately 250 mm, and an internal volume of approximately 1200 ml. Using this, water was passed from the outside to the inside, and the PFAS removal performance was measured using the method described above. The performance measurement results are also shown in Table 2 below.

[0127] Example 2 Powdered activated carbon B, a titanosilicate-based lead adsorbent, an acrylic fibrous binder, and a cellulose fibrous binder were mixed in the proportions shown in Table 1 below to prepare a total of 1.2 kg, and tap water was added to the mixture. The volume of the slurry after the addition was 20 L.

[0128] A preform was then obtained in the same manner as in Example 1. The obtained preform was then dried and then mounted in an automatic grinding machine as shown in Fig. 5, and the outer surface of the preform was ground at a molded body rotation speed of 360 rpm, a grindstone rotation speed of 2535 rpm, and a grindstone movement speed of 250 mm / 10 sec (2.5 cm / sec), to obtain a hollow cylindrical molded body having an outer diameter of 63 mmφ, an inner diameter of 35 mmφ, and a height of 245 mmH.

[0129] The molded body of Example 2 thus produced was used to measure the physical properties and performance of the molded body in the same manner as in Example 1. The measurement results of the physical properties and performance of the molded body are shown in Table 2 below.

[0130] Examples 3 to 7 As shown in Table 1 below, in Example 3, a hollow cylindrical molded body was obtained using the same method as in Example 2, except that powdered activated carbon C was used as the raw activated carbon instead of powdered activated carbon B, and the blending ratio was different. Furthermore, in Examples 4 to 7, a hollow cylindrical molded body was obtained using the same method as in Example 2, except that powdered activated carbon D to powdered activated carbon G were used as the raw activated carbon instead of powdered activated carbon B, and that the titanosilicate-based lead adsorbent and cellulose-based fibrous binder were not blended and the blending ratios were different. Furthermore, the physical properties and performance of the molded bodies of Examples 3 to 7 thus produced were measured using the same method as in Example 1 described above. The physical properties and performance measurement results of these molded bodies are summarized in Table 2 below.

[0131] Examples 8 and 9 As shown in Table 1 below, in Example 8, a total of 0.6 kg of powdered activated carbon A and acrylic fibrous binder were prepared in the same blending ratio as in Example 1, and a hollow cylindrical molded body was obtained in the same manner as in Example 1, except that a slurry with a different solid content concentration was used. In Example 9, a total of 2.0 kg of powdered activated carbon A and acrylic fibrous binder were prepared in the same blending ratio as in Example 1, and a hollow cylindrical molded body was obtained in the same manner as in Example 1, except that a slurry with a different solid content concentration was used. The physical properties and performance of the molded bodies of Examples 8 and 9 thus produced were measured in the same manner as in Example 1. The physical properties and performance measurement results of these molded bodies are summarized in Table 2 below.

[0132] Examples 10 and 11 As shown in Table 1 below, in Example 10, a total of 0.6 kg of powdered activated carbon F and acrylic fibrous binder were prepared in the same blending ratio as in Example 6, and a hollow cylindrical molded body was obtained in the same manner as in Example 6, except that a slurry with a different solids concentration was used. In Example 11, a total of 2.0 kg of powdered activated carbon F and acrylic fibrous binder were prepared in the same blending ratio as in Example 6, and a hollow cylindrical molded body was obtained in the same manner as in Example 6, except that a slurry with a different solids concentration was used. The physical properties and performance of the molded bodies of Examples 10 and 11 thus produced were measured in the same manner as in Example 1. The physical properties and performance measurement results of these molded bodies are summarized in Table 2 below.

[0133] Comparative Examples 1 and 2 As shown in Table 1 below, in Comparative Example 1, a hollow cylindrical molded body was obtained in the same manner as in Example 2, except that powdered activated carbon H was used instead of powdered activated carbon B as the raw activated carbon, and that the titanosilicate-based lead adsorbent and cellulose-based fibrous binder were not blended and the blending ratios were different. In Comparative Example 2, a hollow cylindrical molded body was obtained in the same manner as in Comparative Example 1, except that a total of 0.6 kg of powdered activated carbon H and acrylic fibrous binder were prepared in the same blending ratio as in Comparative Example 1, and a slurry with a different solids concentration was used. The physical properties and performance of the molded bodies of Comparative Examples 1 and 2 thus produced were measured in the same manner as in Example 1. The physical properties and performance measurement results of the molded bodies are summarized in Table 2 below.

[0134] Table 1 below shows the compounding ratios used when producing the molded bodies of each Example and Comparative Example.

[0135]

[0136] In Table 1, "-" indicates that an amount is not included. The amounts of the acrylic fibrous binder and the cellulose fibrous binder are shown in parts by mass relative to 100 parts by mass of the total amount of the raw material activated carbon and titanosilicate lead adsorbent.

[0137] Table 2 below shows the physical properties of the raw activated carbon material and the measurement results of the physical properties and performance of the produced molded bodies in each Example and Comparative Example.

[0138]

[0139] [Discussion] As shown in Table 2 above, the molded bodies of Examples 1 to 11 had a void volume ratio of 1 μm to 30 μm in diameter of 20% or more. Furthermore, the activated carbon (powdered activated carbon A to G) used as the raw material for the molded bodies of Examples 1 to 11 satisfied the conditions of a particle content of 50 μm to 100 μm in diameter of 10% by volume or more and a D90 of 300 μm or less. As shown in Table 2 above, the molded bodies of Examples 1, 8, and 9 were produced using the same type and blending ratio of raw activated carbon and binder, but the solids concentration of the slurry used was different, so the void structures of the molded bodies of each Example were different. For the same reason, the void structures of the molded bodies of Examples 6, 10, and 11 were also different.

[0140] The molded bodies of Comparative Examples 1 and 2 had a void volume ratio of 1 μm to 30 μm in diameter of the molded body of less than 20%. Furthermore, the activated carbon (powdered activated carbon H) used as the raw material for the molded bodies of Comparative Examples 1 and 2 did not satisfy either of the conditions of a particle content of 50 μm to 100 μm in diameter of 10% by volume or more and a D90 of 300 μm or less. As shown in Table 2 above, the molded bodies of Comparative Examples 1 and 2 were produced using the same type and blending ratio of raw activated carbon and binder, but the solids concentrations of the slurries used were different, resulting in different void structures of the molded bodies.

[0141] The molded bodies of Examples 1 to 11 had PFOS and PFOA removal life (L / cc) values ​​exceeding the acceptable standard of 15 L / cc, demonstrating excellent PFAS removal. This is believed to be due to the large proportion of void volume within the molded bodies with diameters of 1 μm to 30 μm, allowing PFOS and PFOA particles to effectively contact and be adsorbed within the voids between activated carbon particles with diameters of 1 μm to 30 μm within the molded bodies. Furthermore, the raw activated carbon (powdered activated carbons A to G) satisfied the conditions of a particle content of 50 μm to 100 μm in particle diameter of 10% or more by volume and a D90 of 300 μm or less, which is believed to have enabled the large proportion of void volume within the molded bodies with diameters of 1 μm to 30 μm.

[0142] Furthermore, as can be seen from the results of the benzene saturated adsorption amount in Table 2 above, in Examples 1 to 3 and Examples 8 to 11, the activation degree of the raw material activated carbon was lower than in Examples 4, 5, and 7, but the molded bodies were able to effectively remove PFAS.

[0143] On the other hand, the molded bodies of Comparative Examples 1 and 2 had PFOS and PFOA removal rate life (L / cc) values ​​below the acceptable standard of 15 L / cc, and were inferior in PFAS removal performance. This is thought to be because the molded bodies of Comparative Examples 1 and 2 had a small void volume ratio of 1 μm to 30 μm in diameter, and PFOS and PFOA were not effectively removed by the voids in the molded bodies. Furthermore, the raw material activated carbon (powdered activated carbon H) did not satisfy either of the conditions of a particle content of 50 μm to 100 μm in particle diameter of 10 vol% or more and a D90 of 300 μm or less, and therefore it is thought that the void volume ratio of 1 μm to 30 μm in diameter in the molded bodies could not be increased.

[0144] The embodiments and examples disclosed herein should be understood to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0145] This application is based on Japanese Patent Application No. 2024-021875 filed on February 16, 2024, the contents of which are incorporated herein by reference.

[0146] In order to express the present invention, the present invention has been properly and sufficiently described above through embodiments and examples with reference to specific examples, but it should be recognized that those skilled in the art can easily make changes and / or improvements to the above-mentioned embodiments and examples. Therefore, unless changes or improvements made by those skilled in the art deviate from the scope of the claims set forth in the claims, such changes or improvements are construed as being encompassed within the scope of the claims.

[0147] The molded article of the present invention can be used, for example, as a cylindrical water purification filter to suitably remove fluorine-containing organic compounds (PFAS).

Claims

1. A molded body comprising activated carbon and a binder, wherein the volume of voids with a diameter of 1 μm to 30 μm inside the molded body measured by mercury intrusion porosimetry is 20% or more of the volume of all voids inside the molded body measured by mercury intrusion porosimetry.

2. The molded body according to claim 1, wherein the volume-based cumulative particle size distribution of the activated carbon has a particle content of 50 μm to 100 μm of 10% by volume or more, and D90 is 300 μm or less.

3. The molded body according to claim 1, wherein the activated carbon layer obtained by cutting out a portion of said molded body has a total amount of acidic functional groups of 0.7 meq / g or less.

4. The molded body according to claim 1, wherein the activated carbon layer obtained by cutting out a portion of the molded body has a caramel decolorization rate of 35% or more.

5. The molded body according to claim 1, wherein the saturated benzene adsorption capacity of the activated carbon is 25% to 60%.

6. The molded body according to claim 1, wherein the ratio of the mesopore volume of the activated carbon calculated by the BJH method to the total pore volume of the mesopores of the activated carbon calculated by the BJH method from the nitrogen adsorption isotherm and the micropore volume of the activated carbon calculated by the MP method is 5% to 30%.

7. The molded article according to any one of claims 1 to 6, which is used to remove perfluoroalkyl compounds and / or polyfluoroalkyl compounds.

8. A method for removing perfluoroalkyl compounds and / or polyfluoroalkyl compounds, comprising using the molded article according to any one of claims 1 to 6.

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