Molded adsorbent body and water purification filter

Abstract

To secure moldability and filtration capacity in a molded adsorbent using a cellulose binder.SOLUTION: The molded adsorbent 1 contains activated carbon 3 and a fibrous cellulose binder 7. The cellulose binder 7 is a mixture of a first cellulose binder 7A and a second cellulose binder 7A having a mean fiber size smaller than that of the first cellulose binder 7B. The first cellulose binder 7A has an average fiber length of 500 μm or more and 2000 μm or less, and the first cellulose binder 7A has an average fiber length of 10 μm or more and 30 μm or less. The average fiber length of the second cellulose binder 7B is 750 μm or less, and the average fiber size of the second cellulose binder 7B is 0.1 μm or more and 1 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to formed adsorbents and water purification filters. [Background technology]

[0002] Patent Document 1 discloses a cartridge in which a housing is filled with a molded activated carbon body as a molded adsorbent. As a specific example of the molded adsorbent, the document describes a molded mixture containing activated carbon having a predetermined particle size distribution and acrylic fiber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-136589 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, molded adsorbents using acrylic fibers as a fibrous binder have good moldability. Recently, the use of naturally derived cellulose binders as fibrous binders has been considered from the perspective of reducing environmental impact. However, compared to acrylic fibers, it is difficult to ensure moldability while maintaining filtration capacity with cellulose binders.

[0005] The present disclosure has been made in view of the above-mentioned conventional situation, and aims to solve the problem of ensuring moldability and filtration capacity in a molded adsorbent using a cellulose binder. [Means for solving the problem]

[0006] The molded adsorbent of the present disclosure is a molded adsorbent containing activated carbon and a fibrous cellulose binder, wherein the cellulose binder is a mixture of a first cellulose binder and a second cellulose binder having an average fiber diameter smaller than that of the first cellulose binder, wherein the first cellulose binder has an average fiber length of 500 μm or more and 2000 μm or less, and an average fiber diameter of 10 μm or more and 30 μm or less, and the second cellulose binder has an average fiber length of 750 μm or less, and an average fiber diameter of 0.1 μm or more and 1 μm or less. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is an explanatory diagram illustrating a schematic configuration of a molded adsorbent body. [Figure 2] FIG. 1 is a front view of an example of a water purification filter including a molded adsorbent. [Figure 3] FIG. 3 is a cross-sectional view of the water purification filter of FIG. 2. [Figure 4] FIG. 2 is a diagram showing an example of a first cellulose binder. [Figure 5] FIG. 2 is a diagram showing another example of the first cellulose binder. [Figure 6] FIG. 2 is a diagram showing an example of a second cellulose binder. [Figure 7] FIG. 1 is a plot diagram showing the relationship between the average fiber length and the average fiber diameter of the binder. [Figure 8] FIG. 1 is a first plot diagram showing the relationship between the ratio of binder 1 to activated carbon and the ratio of binder 2 to activated carbon, plotted with circles. [Figure 9] FIG. 2 is a second plot diagram showing the relationship between the ratio of binder 1 to activated carbon and the ratio of binder 2 to activated carbon, plotted with circles. DETAILED DESCRIPTION OF THE INVENTION

[0008] Embodiments of the present disclosure will be described with reference to the drawings. In this specification, when a numerical range is described using "greater than or equal to" or "less than or equal to," the range includes both the lower and upper limits, unless otherwise specified. For example, the expression "10 or greater and 20 or less" includes both the lower limit "10" and the upper limit "20." Furthermore, in this specification, the upper and lower limits of each numerical range can be combined in any combination.

[0009] As shown in Fig. 1, the formed adsorbent 1 of this embodiment contains activated carbon 3 and a fibrous cellulose binder 7. The formed adsorbent 1 may further contain one or more lead removal materials 5 selected from the group consisting of zeolite, titanium silicate, sodium titanate, aluminosilicate, and titanium oxide. Fig. 1 is an explanatory diagram schematically showing the configuration of the formed adsorbent 1. The size, shape, and amount of each component are not limited to those shown.

[0010] The activated carbon 3 can be obtained from any starting material. Specific examples of the activated carbon 3 include activated carbon obtained from biomass materials such as fruit shells, bamboo, and rice husks, and activated carbon obtained from petroleum-derived materials such as coal and resin. Examples of fruit shells include coconut shells, walnut shells, peach seed shells, and plum seed shells. It is preferable that the activated carbon 3 does not use petroleum-derived materials. The form of the activated carbon 3 is not particularly limited. The activated carbon 3 is, for example, in a granular form.

[0011] From the viewpoint of moldability, the median particle diameter D50 of the activated carbon 3 is preferably 10 μm or more, more preferably 20 μm or more; from the viewpoints of moldability and water permeability, it is even more preferably 30 μm or more, and particularly preferably 35 μm or more. From the viewpoint of moldability, it is preferably 150 μm or less, more preferably 120 μm or less; from the viewpoint of moldability and turbidity removal, it is even more preferably 100 μm or less, and particularly preferably 90 μm or less. From these viewpoints, the median particle diameter D50 of the activated carbon 3 is preferably 10 μm or more and 150 μm or less, more preferably 20 μm or more and 120 μm or less; from the viewpoints of moldability and water permeability, it is even more preferably 30 μm or more and 90 μm or less, and particularly preferably 35 μm or more and 90 μm or less.

[0012] The median particle diameter D50 of activated carbon 3A can be measured as the median particle diameter of the cumulative volume distribution using a laser diffraction / scattering particle size distribution analyzer. The median particle diameter D50 of activated carbon 3 can be controlled, for example, by appropriately selecting the particle diameter of the raw material activated carbon. When activated carbon 3 is a mixture of activated carbons with different particle sizes, the median particle diameter D50 may be controlled by adjusting the blending amounts of activated carbons with each particle size.

[0013] There are no particular limitations on the content of activated carbon 3. When the formed adsorbent 1 is taken as 100% by mass, the content of activated carbon 3 is preferably 64% by mass or more and 98.5% by mass or less, more preferably 75% by mass or more and 95% by mass or less, and even more preferably 80% by mass or more and 92% by mass or less.

[0014] The fibrous cellulose binder 7 is composed of cellulose fibers having a predetermined average fiber length and a predetermined average fiber diameter. From the viewpoint of reducing the environmental load, the cellulose fibers are preferably cellulose fibers derived from biomass. The raw material for the cellulose fibers may be, for example, one or more selected from the group consisting of wood pulp and non-wood plant pulp. From the viewpoint of reducing the environmental load, the molded adsorbent 1 preferably does not contain a petroleum-derived fibrous binder, and more preferably contains only the fibrous cellulose binder 7.

[0015] In the molded adsorbent, the fibrous binder has the functions of "retaining activated carbon" and "ensuring a water path." Acrylonitrile fibers, which have conventionally been used as fibrous binders, have a fibrillated structure resembling a tree with a trunk and countless branched branches. Acrylonitrile fibers with a fibrillated structure can effectively achieve both "retaining activated carbon" mainly through the branched parts and "ensuring a water path" through the trunk. On the other hand, untreated cellulose fibers do not usually have a fibrillated structure. A fibrillated structure is formed when untreated cellulose fibers are subjected to a beating treatment. Beating is a process in which an external force is applied to fibers to disentangle them. However, the cellulose fibers that have been subjected to the beating treatment have smaller fiber length and fiber diameter than the cellulose fibers before the treatment. That is, even if cellulose fibers are subjected to a beating treatment, it is difficult to achieve both "retention of activated carbon" by the branched portions and "ensuring water paths" by the trunk portions, as is the case with acrylonitrile fibers. After extensive research, the inventors of the present application have developed the technology of the present disclosure, which achieves "retention of activated carbon" and "ensuring water paths" by using a combination of cellulose fibers with a relatively long fiber length and cellulose fibers with a relatively short fiber length.

[0016] From the viewpoints of moldability and filtration ability, the cellulose binder 7 is a mixture of a first cellulose binder 7A and a second cellulose binder 7B having an average fiber diameter smaller than that of the first cellulose binder 7A. There are no particular limitations on the first cellulose binder 7A and the second cellulose binder 7B as long as they have the average fiber diameter and average fiber length described below.

[0017] In the present disclosure, the average fiber length of the fibrous cellulose binder 7 is determined by the following measurement method. First, a sample of a slurry liquid of the cellulose binder 7 is prepared. The prepared sample is placed in a shape and particle size distribution measuring device. The shape and particle size distribution measuring device is, for example, manufactured by PartAN SI:Microtrac. The sample is dispersed in a circulator and photographed for a predetermined time, and projection images of 5,000 to 20,000 cellulose binders 7 are obtained. The photographing time can be set according to the number of cellulose binders 7 to be photographed, and is, for example, 90 seconds. The above average fiber length is determined by calculating fiber parameters for all the obtained projection images of the cellulose binder 7 and averaging them. The fiber parameters are calculated by the following formula (1). The fiber parameters are calculated as follows: Fiber length(X LG ) is also called. Fiber parameter = 1 / 4 [P + (P 2 -16A) 1 / 2 ) (1) A: Area of ​​the projected image (μm 2 ) P: Perimeter of the projected image (μm)

[0018] In the present disclosure, the average fiber diameter of the fibrous cellulose binder 7 is determined by the following measurement method. First, a slurry of the cellulose binder 7 is prepared. The concentration of the slurry is set so that the cellulose binders 7 do not overlap when observed under a microscope. The microscope is, for example, a digital microscope, VHX-7000, manufactured by Keyence Corporation. The prepared slurry is observed under the microscope, and 10 cellulose binders 7 are photographed. The illumination, magnification, and focus of the microscope are adjusted according to the shape and size of the cellulose binder 7. The average fiber diameter is determined by calculating the fiber diameters of the 10 photographed images of the cellulose binder 7 and averaging them. The fiber diameter is determined by identifying the portion of the photographed image where the length of the cellulose binder 7 is greatest in the direction perpendicular to the longitudinal direction, and measuring the identified portion using a two-point planar measurement tool.

[0019] The first cellulose binder 7A has an average fiber length of 500 μm to 2000 μm, preferably 550 μm to 1800 μm, and more preferably 600 μm to 1600 μm, and an average fiber diameter of 10 μm to 30 μm, preferably 10 μm to 25 μm, and more preferably 10 μm to 20 μm.

[0020] The average fiber length and average fiber diameter of the first cellulose binder 7A can be controlled, for example, by whether or not the cellulose fibers are beaten and by adjusting the beating conditions. When the first cellulose binder 7A is a mixture of cellulose fibers having different average fiber lengths and average fiber diameters, they may also be controlled by adjusting the blending amounts of the cellulose fibers to be mixed.

[0021] The average fiber length of the second cellulose binder 7B is 750 μm or less, more preferably 730 μm or less, and may be 700 μm or less. The lower limit of the average fiber length of the second cellulose binder 7B is not particularly limited, and may be, for example, 50 μm or more, 100 μm or more, or 200 μm or more. The average fiber diameter of the second cellulose binder 7B is 0.1 μm or more and 1 μm or less, preferably 0.3 μm or more and 1 μm or less, and more preferably 0.5 μm or more and 1 μm or less.

[0022] The average fiber length and average fiber diameter of the second cellulose binder 7B can be controlled, for example, by adjusting the conditions for beating the cellulose fibers. When the second cellulose binder 7B is a mixture of cellulose fibers having different average fiber lengths and average fiber diameters, they may be controlled by adjusting the blending amounts of the cellulose fibers to be mixed.

[0023] The first cellulose binder 7A may not have a fibrillated structure, as shown in Figure 4, or may have a fibrillated structure, as shown in Figure 5. The second cellulose binder 7B preferably has a fibrillated structure, as shown in Figure 6. The cellulose binder 7 may be a mixture of a first cellulose binder 7A that does not have a fibrillated structure and a second cellulose binder 7B that has a fibrillated structure, or a mixture of a first cellulose binder 7A that has a fibrillated structure and a second cellulose binder 7B that has a fibrillated structure. Figures 4 to 6 conceptually illustrate cellulose binders 7A and 7B, and may not be accurate in size.

[0024] When the cellulose binders 7A and 7B have a fibrillated structure, the projected image for measuring the fiber length is an image of the trunk portion. That is, when the cellulose binder 7 has a fibrillated structure, the fiber length corresponds to the length of the trunk portion. When the cellulose binders 7A and 7B have a fibrillated structure, the image for measuring the fiber diameter is an image of the trunk portion. That is, when the cellulose binder 7 has a fibrillated structure, the fiber diameter corresponds to the diameter of the trunk portion.

[0025] The properties of the first cellulose binder 7A and the second cellulose binder 7B can be evaluated, for example, by freeness. Freeness is measured in accordance with JIS P8121:1995, "Testing Method for Freeness of Pulp." This freeness is also referred to as the Canadian Standard Freeness (CSF). In a freeness measurement test, a fiber slurry is poured from above a mesh, and the amount of water that passes through is used to quantify the filtration characteristics. Therefore, if the cellulose binder does not pass through the mesh, the test is successful, and a freeness within the specified range is obtained. If most of the cellulose binder passes through the mesh, the test is unsuccessful. However, in this case, the filtrate becomes cloudy, and the small size of the cellulose binder can be visually confirmed.

[0026] The freeness of the first cellulose binder 7A is preferably 0 mL or more and 650 mL or less. The second cellulose binder 7B preferably has a lower freeness than the first cellulose binder 7A, and more preferably fails the Canadian Standard Freeness measurement test and produces cloudy filtrate. In other words, the cellulose binder 7 may be a mixture of the first cellulose binder 7A and the second cellulose binder 7B, which have different properties evaluated by freeness.

[0027] The content of the first cellulose binder 7A is preferably 1.5 to 25 parts by mass, more preferably 2.0 to 20 parts by mass, and even more preferably 2.5 to 10 parts by mass, relative to 100 parts by mass of activated carbon. The content of the second cellulose binder 7B is preferably 0.1 to 3.5 parts by mass, more preferably 0.2 to 2.5 parts by mass, and even more preferably 0.3 to 2.0 parts by mass, relative to 100 parts by mass of activated carbon.

[0028] The ratio (mass ratio) of the first cellulose binder 7A to the second cellulose binder 7B is not particularly limited, and the mass ratio of the first cellulose binder 7A to the second cellulose binder 7B is preferably 50:50 to 99:1, more preferably 60:40 to 98:2, and even more preferably 70:30 to 95:5.

[0029] There are no particular limitations on the total content of the fibrous cellulose binder 7. The total content of the cellulose binder 7 is preferably 1.5% by mass or more and 21% by mass or less, more preferably 3% by mass or more and 14.5% by mass or less, and even more preferably 4.5% by mass or more and 8% by mass or less, based on 100% by mass of the formed adsorbent body 1.

[0030] The lead removal material 5 is not particularly limited as long as the desired effect is not impaired. It is preferable that the lead removal material 5 does not use a petroleum-derived material. The lead removal material 5 is, for example, one or more selected from the group consisting of zeolite, titanium silicate, sodium titanate, aluminosilicate, and titanium oxide. The form of the lead removal material 5 is not particularly limited. The lead removal material 5 is, for example, in a particulate form.

[0031] The filtration flow rate of the formed adsorbent 1 is preferably 1.5 L / min or more, more preferably 2.0 L / min or more, and even more preferably 2.5 L / min or more. There are no particular limitations on the upper limit of the filtration flow rate of the formed adsorbent 1, and it is, for example, 3.5 L / min or less. The filtration flow rate of the formed adsorbent 1 can be measured in accordance with JIS S3201 6.1 "Filtration Flow Rate Test."

[0032] The turbidity removal rate of the formed adsorbent 1 is preferably 80% or more. The water permeability of the formed adsorbent 1 can be measured in accordance with JIS S3201 6.4.3 "Turbidity removal performance test."

[0033] The water purification filter 11 of this embodiment includes a molded adsorbent 1. The shape and structure of the water purification filter 11 are not particularly limited. As shown in FIGS. 2 and 3, an example of the water purification filter 11 is cylindrical. This water purification filter 11 includes a core material 12, the molded adsorbent 1, a support 14, and sealing caps 15 and 16. The core material 12 is hollow and cylindrical. The core material 12 has pores formed therein that allow water to pass from the outside to the inside, forming a flow path 20 therein. Any material can be used for the core material 12. It is preferable that the core material 12 not be made of a petroleum-derived material. The material of the core material 12 is, for example, a porous ceramic, a porous metal filter, or a hard nonwoven fabric.

[0034] An example of the molded adsorbent body 1 is cylindrical and disposed on the outer peripheral surface of the core material 12. The support body 14 is disposed on the outer peripheral surface of the molded adsorbent body 1. The support body 14 is made of, for example, a nonwoven fabric. For example, a nonwoven fabric specified in JIS L0222 can be used for the support body 14. There are no particular limitations on the type of fiber that is the raw material for the support body 14. The fiber that is the raw material for the support body 14 preferably contains cellulose fiber.

[0035] The sealing cap 15 is in watertight contact with the bottom surface of the molded adsorbent body 1. The sealing cap 16 is in watertight contact with the top surface of the molded adsorbent body 1. The sealing cap 16 has an outlet 60 through which water that has flowed through the flow path 20 is discharged.

[0036] There are no particular limitations on the manufacturing method of the water purification filter 11. The manufacturing method of the water purification filter 11 includes, for example, a mixing step, a suction molding step, a drying step, a surface polishing step, a nonwoven fabric winding step, and a sealing step.

[0037] The mixing step involves mixing at least activated carbon 3, a fibrous cellulose binder 7, and water to obtain a slurry. The suction molding step involves molding a molded adsorbent 1. For example, the suction molding step includes sealing the other end of the flow path 20 of the core material 12 and connecting one end of the flow path 20 of the core material 12 to a suction pump via a hose; immersing the core material 12 connected to the suction pump in the above-mentioned slurry stored in a container and operating the suction pump; and allowing the water in the slurry to permeate the core material 12, leaving a mixture of activated carbon 3 and fibrous cellulose binder 7 on the surface of the core material 12 and gradually depositing it. The water in the slurry sucked into the suction pump is discharged through a drainage channel. Operating the suction pump allows the molded adsorbent 1 to be formed to a specified thickness.

[0038] In the drying step, the formed adsorbent body 1 formed in the suction forming step is dried. In the surface polishing step, the outer peripheral surface of the formed adsorbent body 1 is polished. In the nonwoven fabric winding step, a support 14 is wrapped around the outer peripheral surface of the formed adsorbent body 1 polished in the surface polishing step. In the sealing step, a sealing cap 15 is attached to one end of the formed adsorbent body 1 around which the support 14 is wrapped, and a sealing cap 16 is attached to the other end.

[0039] As described above, the molded adsorbent 1 of this embodiment contains activated carbon 3 and a fibrous cellulose binder 7. The cellulose binder 7 is a mixture of a first cellulose binder 7A and a second cellulose binder 7B having a smaller average fiber diameter than the first cellulose binder 7A. The first cellulose binder 7A has an average fiber length of 500 μm to 2000 μm and an average fiber diameter of 10 μm to 30 μm. The second cellulose binder 7B has an average fiber length of 750 μm or less and an average fiber diameter of 0.1 μm to 1 μm. Because the cellulose binder 7 is a mixture of the first cellulose binder 7A and the second cellulose binder 7B, the moldability of the molded adsorbent 1 of this embodiment is excellent. The formed adsorbent 1 of this embodiment has a better turbidity removal rate than, for example, a formed adsorbent using only the first cellulose binder 7A. The formed adsorbent 1 of this embodiment has better water permeability than, for example, a formed adsorbent using only the second cellulose binder 7B. The formed adsorbent 1 of this embodiment can maintain the filtering ability of a formed adsorbent using a cellulose binder.

[0040] The molded adsorbent 1 of this embodiment employs a cellulose binder as the fibrous binder, thereby contributing to a reduction in environmental impact. For example, if 1,000 g of acrylonitrile fiber were replaced with 1,000 g of cellulose fiber as the fibrous binder, the increase in CO2 on the earth's surface due to the CO2 released during disposal could be reduced by 1,266 L. The increase in CO2 was calculated using the following formula, assuming a molar mass of 53.06 g / mol of the acrylonitrile unit C3H3N of the acrylonitrile fiber and a volume of 22.4 L of 1 mole of carbon dioxide. (1000 / 53.06)×3×22.4=1266 [Example]

[0041] Experiment numbers 7, 15 to 19, 22 to 24, 26 to 32, and 35 to 42 are examples, and experiment numbers 1 to 6, 8 to 14, 20, 21, 25, 33, 34, 43, and 44 are comparative examples. In Tables 1 to 7, "*" indicates a comparative example.

[0042] The molded adsorbents of each experimental example were prepared as follows. First, the experimenters prepared a slurry containing activated carbon and a fibrous binder. The fibrous binders used were Binder 1 and Binder 2, as listed in Tables 1 to 3. The amounts of Binder 1 and Binder 2 were adjusted so that the ratio (%) of Binder 1 and the ratio (%) of Binder 2 to 100 parts by mass of activated carbon were the values ​​listed in the "Parts by mass" columns of Tables 1 to 3.

[0043] Details of each component are as follows. The activated carbon used was granular activated carbon of the type and median particle diameter D50 shown in Tables 1 to 3. In Table 3, "T-SCOB-05" is a biomass-derived activated carbon with a median particle diameter D50 of 672 μm, manufactured by Kuraray Chemical Co., Ltd. In Tables 1 to 3, "Pulverized Products 1 to 11" are activated carbons obtained by pulverizing T-SCOB-05 and adjusting the particle size.

[0044] The fibrous binders used were binder 1 and binder 2 listed in Tables 1 to 3. In Table 1, "Bi-PUL" is a fibrillated acrylonitrile fiber manufactured by Nippon Exlan Kogyo Co., Ltd. In Tables 1 to 3, fibers other than "Bi-PUL" are cellulose fibers. Details of each fiber are as shown in Table 4. In Table 4, the fibers listed in the "First Cellulose Binder" column are cellulose fibers that meet the requirements of an average fiber length of 500 μm or more and 2000 μm or less, and an average fiber diameter of 10 μm or more and 30 μm or less. The fibers listed in the "Second Cellulose Binder" column are cellulose fibers that meet the requirements of an average fiber length of 750 μm or less, and an average fiber diameter of 0.1 μm or more and 1 μm or less. The fibers listed in the "Other (outside range)" column are cellulose fibers that do not meet the average fiber length and average fiber diameter requirements of the above-mentioned "First Cellulose Binder" and do not meet the average fiber length and average fiber diameter requirements of the "Second Cellulose Binder." The fibers listed in the "Reference (Petroleum-derived)" column are fibers made from petroleum-derived raw materials, specifically the above-mentioned "Bi-PUL," a fibrillated acrylonitrile fiber manufactured by Nippon Exlan Kogyo Co., Ltd.

[0045] Details of the shape and particle size distribution measuring device and measurement conditions for measuring the average fiber length of Binder 1 and Binder 2 are as follows. The average fiber length was measured wet. The results are shown in Tables 1 to 4. Shape and particle size distribution measuring device: PartAN SI, manufactured by Microtrac Distribution: Volume Solvent: Water Scale classification: particle size from 5 μm to 3000 μm Resolution:2048 Threshold Level: 7% Shooting time: 90 seconds

[0046] The average fiber diameters of Binder 1 and Binder 2 were determined according to the method described in the embodiment. The results are shown in Tables 1 to 4.

[0047] The details of the particle size distribution measurement device used to measure the median particle size of activated carbon and the measurement conditions are as follows. The particle size distribution was measured wet. The particle size of each substance in the solvent does not change even after drying in the formed adsorbent. The particle size distribution of each substance in the solvent reflects the particle size distribution of each substance in the formed adsorbent after drying. The results are shown in Tables 1 to 3. Laser diffraction / scattering particle size distribution analyzer: Microtrac MT3300EXII Distribution: Volume Solvent: Water Scale classification: particle size from 0.021 μm to 2000 μm Number of channels: 132

[0048] [Table 1]

[0049] [Table 2]

[0050] [Table 3]

[0051] [Table 4]

[0052] Next, the experimenter attached a ceramic core (outer diameter φ8 mm, inner diameter φ5 mm) to the molding machine and sucked it into the slurry to form a cylindrical molded adsorbent. The size of the molded adsorbent was set to an outer diameter of φ24.7 mm, an inner diameter of φ8 mm, and a height of 90 mm. The experimenter dried and polished the molded adsorbent, wrapped it in nonwoven fabric, and attached a sealing cap to create a water purification filter.

[0053] The moldability of the molded adsorbent was evaluated according to the following criteria, and the results are shown in Tables 5 to 7. Acceptable: The moldability is good and it can be used as a molded adsorbent. Unacceptable: Poor moldability meant that the product could not be used as a molded adsorbent.

[0054] The water-permeability characteristics of water-purifying filters that were rated "fair" for moldability were evaluated. The filtration flow rate was evaluated as follows, in accordance with JIS S3201 6.1 "Filtration Flow Rate Test." An unused water-purifying filter from each experimental example was attached to the housing, and raw water was continuously passed through at SV = 4000 / h (2.5 L / min) for 10 minutes. Then, while continuing to pass water, the pressure gauge was adjusted to 0.1 MPa, and the flow rate (LPM, L / min) at that time was measured. The results are shown in Tables 5 to 7.

[0055] The water purification filters that were evaluated for moldability as "fair" were evaluated for turbidity removal performance. The turbidity removal rate was measured in accordance with JIS S3201 6.4.3 "Turbidity removal performance test." The results are shown in Tables 5 to 7. Note that in experiment number 26, no flow rate was obtained, so the turbidity removal rate was not calculated.

[0056] The water purification filters were evaluated comprehensively according to the following criteria. The results are shown in Tables 4 to 6. Note that for experiment number 26, the turbidity removal performance could not be evaluated, so an overall evaluation was not made. A: The moldability is evaluated as "Fair," the water permeability is 1.5 L / min or more, and the turbidity removal rate is 80% or more. However, if the central particle diameter D50 of the activated carbon is less than 35 μm or more than 90 μm, the water permeability and turbidity removal rate will not be taken into consideration and the evaluation will be "A" as long as the moldability is evaluated as "Fair." B: Either the moldability is evaluated as "unacceptable," or the moldability is evaluated as "acceptable" and the activated carbon has a central particle diameter D50 of 35 μm or more and 90 μm or less, and the water permeability is less than 1.5 L / min or the turbidity removal rate is less than 80%.

[0057] [Table 5]

[0058] [Table 6]

[0059] [Table 7]

[0060] A preferred combination of Binder 1 and Binder 2 will be investigated. Figure 7 is a plot diagram showing the relationship between the average fiber length and average fiber diameter of Binder 1 for the molded adsorbent of each experiment number, with the circle plot representing the relationship between the average fiber length and average fiber diameter of Binder 2, and the triangle plot representing the relationship between the average fiber length and average fiber diameter of Binder 2. The horizontal axis represents the average fiber length (μm), and the vertical axis represents the average fiber diameter (μm). For example, the circle plot and the triangle plot labeled "No. 7" correspond to the combination of Binder 1 and Binder 2 for experiment number 7.

[0061] In the plot of Figure 7, the range of the square in the upper right indicates the range where the average fiber length is 500 μm or more and 2000 μm or less, and the average fiber diameter is 10 μm or more and 30 μm or less. The range of the square in the lower left indicates the range where the average fiber length is 750 μm or less, and the average fiber diameter is 0.1 μm or more and 1 μm or less. When the overall evaluation was "A," Binder 1 was included in the range of the square in the upper right, and Binder 2 was included in the range of the square in the lower left.

[0062] The blending amounts of binder 1 and binder 2 will now be examined. Figures 8 and 9 are plots showing the relationship between the ratio of binder 1 to activated carbon and the ratio of binder 2 to activated carbon for the above-mentioned molded adsorbent, plotted with circles. The horizontal axis represents the ratio (parts by mass) of binder 1 to 100 parts by mass of activated carbon, and the vertical axis represents the ratio (parts by mass) of binder 2 to 100 parts by mass of activated carbon.

[0063] In the first plot diagram of Figure 8, the dashed-dotted line range is the range that includes the plots of the experiment numbers where the moldability evaluation was "Fair." In the second plot diagram of Figure 9, the dashed-dotted line range is the range that includes the plots of the experiment numbers where the "water permeability" was 1.5 L / min or more and the turbidity removal rate was 80% or more. These results suggest that moldability and filtration capacity can be ensured when the content of binder 1 is 1.5 to 25 parts by mass per 100 parts by mass of activated carbon and the content of binder 2 is 0.1 to 3.5 parts by mass per 100 parts by mass of activated carbon.

[0064] The experimental results are as follows: Experiments No. 7, 15 to 19, 22 to 24, 26 to 32, and 35 to 42 all meet the following requirements a, b, c, and d. Requirement a: The formed adsorbent contains activated carbon and a fibrous cellulose binder. Requirement b: The cellulose binder is a mixture of a first cellulose binder and a second cellulose binder having an average fiber diameter smaller than that of the first cellulose binder. Requirement c: The first cellulose binder has an average fiber length of 500 μm or more and 2000 μm or less, and an average fiber diameter of 10 μm or more and 30 μm or less, and the second cellulose binder has an average fiber length of 750 μm or less and an average fiber diameter of 0.1 μm or more and 1 μm or less. Requirement d: It is possible to form a molded adsorbent body by molding.

[0065] In contrast, experiment number 1 does not satisfy requirements a, b, and c. Experiment numbers 2 to 6 do not satisfy requirements b and c. Experiment numbers 8, 10, 11, and 25 do not satisfy requirement c. Experiment numbers 9, 12 to 14, and 20 do not satisfy requirements c and d. Experiment numbers 21, 33, 34, 43, and 44 do not satisfy requirement d.

[0066] The overall evaluation of Experiments Nos. 7, 15 to 19, 22 to 24, 27 to 32, and 35 to 42 was "A." These experimental examples ensured the formability and filtration capacity of the formed adsorbent using the cellulose binder. [Explanation of symbols]

[0067] REFERENCE SIGNS LIST 1...molded adsorbent, 3...activated carbon, 5...lead removal material, 7...cellulose binder, 7A...first cellulose binder, 7B...second cellulose binder, 11...water purification filter, 12...core material, 14...nonwoven fabric, 15...sealing cap, 16...sealing cap, 20...flow path, 60...discharge port

Claims

1. A molded adsorbent comprising activated carbon and a fibrous cellulose binder, the cellulose binder is a mixture of a first cellulose binder and a second cellulose binder having an average fiber diameter smaller than that of the first cellulose binder; the first cellulose binder has an average fiber length of 500 μm or more and 2000 μm or less, and an average fiber diameter of 10 μm or more and 30 μm or less; The second cellulose binder has an average fiber length of 750 μm or less, and an average fiber diameter of 0.1 μm or more and 1 μm or less.

2. the content of the first cellulose binder is 1.5 parts by mass or more and 25 parts by mass or less relative to 100 parts by mass of the activated carbon; 2. The formed adsorbent according to claim 1, wherein the content of the second cellulose binder is 0.1 parts by mass or more and 3.5 parts by mass or less per 100 parts by mass of the activated carbon.

3. 3. The formed adsorbent according to claim 1, wherein the activated carbon has a median particle diameter D50 of 10 μm or more and 150 μm or less.

4. A water purification filter comprising the molded adsorbent according to claim 1 or 2.

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