Molded adsorbent, and water purification cartridge

Abstract

Provided is a molded adsorbent capable of improving chloroform removal performance. A molded adsorbent (1) contains activated carbon (3) and a fibrous binder (7). The center particle diameter D50 of the activated carbon (3) is not less than 16 μm but less than 27 μm.

Description

Molded adsorbent and water purification cartridge

[0001] The present disclosure relates to molded adsorbents and water purification cartridges.

[0002] Patent Document 1 discloses a water treatment filter, which includes a cylindrical filter containing particulate activated carbon with a median particle size of 30 μm or more and 80 μm or less and a fibrillated fibrous binder.

[0003] International Publication No. 2014 / 061740

[0004] The chloroform removal capability of the water treatment filter disclosed in Patent Document 1 was not necessarily sufficient. An object of the present disclosure is to provide a molded adsorbent that can improve the chloroform removal performance.

[0005] The formed adsorbent of the present disclosure is a formed adsorbent containing activated carbon and a fibrous binder, and the activated carbon has a median particle diameter D50 of 16 μm or more and less than 27 μm.

[0006] Fig. 2 is an explanatory diagram showing a schematic configuration of a molded adsorbent body; Fig. 3 is a front view of an example of a water purification cartridge equipped with a molded adsorbent body; Fig. 4 is a cross-sectional view of the water purification cartridge of Fig. 2; Fig. 5 is a frequency distribution curve for a fibrous binder, plotting particle diameter on the horizontal axis and frequency on the vertical axis; Fig. 6 is a cumulative distribution curve for a fibrous binder, plotting particle diameter on the horizontal axis and cumulative volume on the vertical axis.

[0007] First, embodiments of the present disclosure will be listed and described. Any combination of the following embodiments without causing any contradiction is also included in the embodiments for carrying out the invention. [1] The formed adsorbent of the present disclosure is a formed adsorbent containing activated carbon and a fibrous binder, wherein the activated carbon has a median particle diameter D50 of 16 μm or more and less than 27 μm. [2] In the formed adsorbent described in [1] above, when the fibrous binder is measured using a laser diffraction / scattering particle size distribution analyzer, the median particle diameter D50 measured is 50 μm or more and 140 μm or less. [3] The formed adsorbent described in either [1] or [2] above further contains one or more lead removal materials selected from the group consisting of zeolite, titanium silicate, sodium titanate, aluminosilicate, and titanium oxide, wherein the median particle diameter D50 of the lead removal material is 25 μm or more and 40 μm or less. [4] In the molded adsorbent according to any one of [1] to [3] above, the content of the fibrous binder is 4% by mass or more and 12% by mass or less, when the molded adsorbent is taken as 100% by mass. [5] A water purification cartridge according to the present disclosure includes the molded adsorbent according to any one of [1] to [4] above.

[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 limit and the upper limit 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 Figure 1, the formed adsorbent 1 of this embodiment contains activated carbon 3 and a fibrous 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. Figure 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 thereto. The arrows in Figure 1 represent the flow of water purified by the formed adsorbent 1.

[0010] The activated carbon 3 can be obtained from any starting material. A specific example of the activated carbon 3 is activated carbon obtained by carbonizing at high temperature one or more materials selected from coconut shells, rice husks, coal, and phenolic resins and then activating them. The form of the activated carbon 3 is not particularly limited. The activated carbon 3 is, for example, in a granular form.

[0011] Conventional molded adsorbents use activated carbon with a median particle size D50 of approximately 65 μm to balance pressure loss suppression, turbidity filtration performance, and free residual chlorine removal. The present inventors hypothesized that reducing the particle size of activated carbon would be effective in improving the chloroform removal capacity specified in JIS S3201:2019, and proceeded with development. However, it was difficult to ensure the initial flow rate required for a molded adsorbent while improving chloroform removal capacity by making the activated carbon finer than conventional methods. After extensive research, the present inventors have developed the new technology disclosed herein, which combines activated carbon 3 with a median particle size D50 within a predetermined range and a fibrous binder 7.

[0012] From the viewpoint of ensuring an initial flow rate, the central particle diameter D50 of the activated carbon 3 is 16 μm or more, preferably 19 μm or more, and more preferably 20 μm or more. From the viewpoint of improving the chloroform removal capacity, the central particle diameter D50 of the activated carbon 3 is less than 27 μm, preferably 26 μm or less, and more preferably 25 μm or less. From these viewpoints, the central particle diameter D50 of the activated carbon 3 is 16 μm or more and less than 27 μm, preferably 19 μm or more and 26 μm or less, and more preferably 20 μm or more and 25 μm or less.

[0013] From the viewpoint of improving chloroform removal capability, the content of activated carbon 3 having a particle diameter of 10 μm or less is preferably 1 vol% or more, more preferably 3 vol% or more, even more preferably 5 vol% or more, and may be 7 vol% or more, or even 8 vol% or more. From the viewpoint of ensuring an initial flow rate, the content of activated carbon 3 having a particle diameter of 10 μm or less is preferably 15 vol% or less, more preferably 10 vol% or less, and even more preferably 8 vol% or less. From these viewpoints, the content of activated carbon 3 having a particle diameter of 10 μm or less is preferably 1 vol% or more and 15 vol% or less, more preferably 3 vol% or more and 10 vol% or less, and even more preferably 5 vol% or more and 8 vol% or less. The content of activated carbon 3 having a particle diameter of 10 μm or less means the volume fraction of activated carbon 3 having a particle diameter of 10 μm or less contained in 100 vol% of the total amount of activated carbon 3. Activated carbon 3 having a particle diameter of 10 μm or less has a particle diameter greater than 0 μm.

[0014] The median particle diameter D50 of the activated carbon 3 and the content of activated carbon 3 having a particle diameter of 10 μm or less can be measured by a laser diffraction / scattering type particle diameter distribution measuring device.

[0015] The median particle diameter D50 and particle size distribution of the activated carbon 3 can be controlled, for example, by appropriately selecting the particle diameter of the raw material activated carbon. When the activated carbon 3 is a mixture of activated carbons with different particle diameters, they may be controlled by adjusting the blending amounts of activated carbons with each particle diameter.

[0016] There are no particular limitations on the content of activated carbon 3. The content of activated carbon 3 is preferably 64% by mass or more and 96% by mass or less, more preferably 75% by mass or more and 94% by mass or less, and even more preferably 80% by mass or more and 92% by mass or less, based on 100% by mass of the formed adsorbent 1.

[0017] The fibrous binder 7 is not particularly limited as long as the desired effect is not impaired. The fibrous binder 7 may be either a synthetic fiber or a natural fiber. The fibrous binder 7 is, for example, one or more fibers selected from the group consisting of acrylic fiber, polyethylene fiber, polypropylene fiber, polyacrylonitrile fiber, cellulose fiber, polyamide fiber, and aramid fiber. Among these, acrylic fiber is preferred. From the viewpoint of the shape retention of the molded adsorbent 1, the fibrous binder 7 is preferably fibrillated.

[0018] It has been found that, in the technology of the present disclosure, the fibrous binders 7, 7A, and 7B can also be suitably evaluated by particle size distribution measurement, similar to the particle size distribution of the activated carbon 3. For this reason, the fibrous binders 7, 7A, and 7B of the present disclosure are defined by measured values ​​measured using a laser diffraction / scattering particle size distribution measuring device.

[0019] When the fibrous binder 7 is measured using a laser diffraction / scattering particle size distribution analyzer, the measured value obtained as the median particle diameter D50 is preferably 50 μm or more and 140 μm or less, more preferably 70 μm or more and 130 μm or less, and even more preferably 90 μm or more and 120 μm or less.

[0020] From the viewpoints of ensuring the shape retention of the molded adsorbent 1 and the loading amount of activated carbon 3, the fibrous binder 7 is preferably a mixture of a first fibrous binder 7A and a second fibrous binder 7B having a particle size distribution different from that of the first fibrous binder 7A. The first fibrous binder 7A and the second fibrous binder 7B may be the same type of fiber or different types of fibers as long as they have different particle size distributions. The first fibrous binder 7A and the second fibrous binder 7B are preferably the same type of fiber, and more preferably both are acrylic fibers. Such a second fibrous binder 7B can be obtained, for example, by subjecting the first fibrous binder 7A to a process for reducing the particle size. The process for reducing the particle size is, for example, a grinding process or a classification process.

[0021] When the first fibrous binder 7A is measured with a laser diffraction / scattering particle size distribution analyzer, the measured value obtained as the median particle diameter D50 is preferably 60 μm or more and 300 μm or less, more preferably 80 μm or more and 200 μm or less, and even more preferably 100 μm or more and 160 μm or less. When the second fibrous binder 7B is measured with a laser diffraction / scattering particle size distribution analyzer, the measured value obtained as the median particle diameter D50 is preferably 14 μm or more and 60 μm or less, more preferably 18 μm or more and 40 μm or less, and even more preferably 20 μm or more and 30 μm or less.

[0022] The ratio (mass ratio) of the first fibrous binder 7A to the second fibrous binder 7B is not particularly limited, and the mass ratio of the first fibrous binder 7A to the second fibrous binder 7B is preferably 5:5 to 9.9:0.1, more preferably 6:4 to 9.5:0.5, and even more preferably 7:3 to 9:1.

[0023] There are no particular limitations on the content of the fibrous binder 7. The content of the fibrous binder 7 is preferably 4% by mass or more and 12% by mass or less, more preferably 5% by mass or more and 11% by mass or less, and even more preferably 6% by mass or more and 10% by mass or less, based on 100% by mass of the molded adsorbent body 1.

[0024] The lead removal material 5 is not particularly limited as long as the desired effect is not impaired. 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, and among these, zeolite is preferred. The form of the lead removal material 5 is not particularly limited. The lead removal material 5 is, for example, in a particulate form.

[0025] The median particle diameter D50 of the lead removal material 5 is preferably 25 μm or more and 40 μm or less, more preferably 28 μm or more and 37 μm or less, and even more preferably 30 μm or more and 35 μm or less, from the viewpoint of ensuring water flow rate by matching the particle size of the activated carbon 3. The median particle diameter D50 of the lead removal material 5 can be measured with a laser diffraction / scattering type particle size distribution measuring device.

[0026] There are no particular limitations on the content of the lead removal material 5. When the molded adsorbent 1 is taken as 100% by mass, the content of the lead removal material 5 is preferably 2.5% by mass or more and 32% by mass or less, more preferably 3.0% by mass or more and 20% by mass or less, and even more preferably 4.5% by mass or more and 12% by mass or less.

[0027] The pressure loss of the formed adsorbent 1 is preferably 0.07 MPa or more and 0.15 MPa or less. A formed adsorbent 1 with such a pressure loss is practical. The pressure loss refers to the pressure loss at a flow rate of 1.5 L / min when water is passed from the outer peripheral surface to the inner peripheral surface of a cartridge filter having an outer diameter of 24.4 mm, an inner diameter of 8.1 mm, and a length of 90.0 mm and a filtration volume of 37.4 mL.

[0028] The density of the molded adsorbent 1 is 0.28 g / cm ３ 0.45g / cm or more ３ It is preferable that the density is 0.35 g / cm or less. ３ 0.43g / cm or more ３ More preferably, it is 0.38 g / cm or less. ３ 0.41g / cm or more ３ The density of the molded adsorbent body 1 is determined by multiplying the mass (g) of the molded adsorbent body 1 by the volume (cm ３ ) refers to the apparent density calculated based on

[0029] The water purification cartridge 11 of this embodiment includes a molded adsorbent 1. The shape and structure of the water purification cartridge 11 are not particularly limited. As shown in Figures 2 and 3, one example of the water purification cartridge 11 is cylindrical. This water purification cartridge 11 includes a core 12, a molded adsorbent 1, a nonwoven fabric 14, and sealing caps 15 and 16. The core 12 is cylindrical and is located at the innermost part of the water purification cartridge 11. The core 12 has pores formed therein that allow water to pass from the outside to the inside, and a flow path 20 is formed therein. Any material can be used for the core 12. Examples of materials for the core 12 include porous ceramic, a porous metal filter, and a hard nonwoven fabric.

[0030] The molded adsorbent 1 in one example has a cylindrical shape and is disposed on the outer peripheral surface of the core 12. The nonwoven fabric 14 is disposed on the outer peripheral surface of the molded adsorbent 1. For example, the nonwoven fabric 14 may be a nonwoven fabric specified in JIS L0222. There are no particular restrictions on the type of fiber that is the raw material for the nonwoven fabric 14.

[0031] The sealing cap 15 covers one end of the molded adsorbent 1, thereby closing one side of the flow path 20. The sealing cap 16 covers the other end of the molded adsorbent 1. The sealing cap 16 is formed with an outlet 60 through which water that has flowed through the flow path 20 is discharged.

[0032] There are no particular limitations on the manufacturing method of the water purification cartridge 11. The manufacturing method of the water purification cartridge 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.

[0033] The mixing step involves mixing at least particulate matter containing activated carbon, a fibrous binder 7, and water to obtain a slurry. The suction molding step involves molding the formed adsorbent 1. For example, the suction molding step includes sealing the other end of the flow path 20 of the core 12 and connecting one end of the flow path 20 of the core 12 to a suction pump via a hose. The core 12 connected to the suction pump is immersed in the above-mentioned slurry stored in a container and the suction pump is operated. The water in the slurry permeates the core 12, and the mixture of particulate matter and binder remains on the surface of the core 12 and gradually accumulates. The water in the slurry sucked into the suction pump is discharged through a drainage channel. Operating the suction pump allows the formed adsorbent 1 to be formed to a specified thickness.

[0034] The drying step dries the formed adsorbent body 1 formed in the suction forming step. The surface polishing step polishes the outer peripheral surface of the formed adsorbent body 1. The nonwoven fabric winding step winds nonwoven fabric 14 around the outer peripheral surface of the formed adsorbent body 1 polished in the surface polishing step. The sealing step attaches sealing cap 15 to one end of the formed adsorbent body 1 wrapped with nonwoven fabric 14, and sealing cap 16 to the other end.

[0035] As described above, the molded adsorbent 1 of this embodiment is a molded adsorbent containing activated carbon 3 and a fibrous binder 7, and the activated carbon 3 has a median particle diameter D50 of 16 μm or more and less than 27 μm. The molded adsorbent 1 of this embodiment can achieve sufficient chloroform removal performance. By using a combination of activated carbon 3 and a fibrous binder 7, the molded adsorbent 1 can preferably ensure the shape retention and initial flow rate required of the molded adsorbent 1.

[0036] Experimental Examples 2 to 11 are working examples, and Experimental Example 1 is a comparative example. In Table 1, "*" indicates a comparative example.

[0037] The molded adsorbents of each experimental example were prepared as follows: First, the experimenter prepared a slurry with the following blending ratios so that the total amount of activated carbon, lead removal material, and fibrous binder was 100% by mass: <Slurry Blending Ratio> Activated carbon: 80% by mass to 92% by mass Lead removal material: 4.5% by mass to 12% by mass Fibre binder: 6% by mass to 10% by mass

[0038] Details of each component are as follows: Activated carbon: granular activated carbon having the particle size distribution shown in Table 1. Lead removal material: zeolite (BASF Japan ATS) ＴＭ MEDIA NSF / ANSI61 D50 = 29 μm. Fiber binder: A mixture of the following first fiber binder and second fiber binder in a mass ratio of 87.5:12.5. The measured D50 is 105.37 μm. First fiber binder: Toyobo Co., Ltd., Japan Exlan Industrial Co., Ltd. Bi-PUL 50 TWF (acrylonitrile fibrillated fiber). The measured D50 is 131.5 μm. Second fiber binder: A fiber binder obtained by pulverizing and classifying the first fiber binder to adjust the measured D50 to 25 μm.

[0039] FIG. 4 is a frequency distribution curve for the fibrous binder, plotting the particle diameter (μm) on the horizontal axis and the frequency (%) on the vertical axis. FIG. 5 is a cumulative distribution curve for the fibrous binder, plotting the particle diameter (μm) on the horizontal axis and the cumulative volume (%) on the vertical axis. The distribution curve for the first fibrous binder is the curve for "Sample A." The distribution curve for the second fibrous binder is the curve for "Sample B." The distribution curve for the fibrous binder with a measured D50 of 105.37 μm used in each experimental example is the curve for "Sample 2." The curves for "Sample 1," "Sample 3," and "Sample 4" are distribution curves for fibrous binders with different mass ratios of the first fibrous binder and the second fibrous binder, and were not used in this experimental example.

[0040] Details of the particle size distribution measuring device and measurement conditions are as follows. Particle size distribution measurement was performed in a wet manner. 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 Table 1. Laser diffraction / scattering type Particle size distribution measuring device: Microtrac MT3300EXII Distribution: Volume Solvent: Water Scale division: Particle size from 0.021 μm to 2000 μm Number of channels: 132

[0041]

[0042] Next, the experimenter attached a ceramic core (outer diameter 8.1 mm, inner diameter 5.0 mm) to the molding machine, sucked it into the slurry, and molded a molded adsorbent. The size of the molded adsorbent was set to an outer diameter of 24.4 mm, an inner diameter of 8.1 mm, and a length of 90 mm. The experimenter dried and polished the molded adsorbent, wrapped it in nonwoven fabric, and attached a cap to create a water purification cartridge. The density (g / cm) of each molded adsorbent was measured. ３ ) was determined by measuring the mass (g) of the formed adsorbent body and calculating the volume of the formed adsorbent body as 37.4 cm ３ The results are shown in Table 1.

[0043] The initial flow rate was evaluated in accordance with JIS S3201 6.1 "Filtration Flow Rate Test" as follows. An unused water purification cartridge from each experimental example was attached to the housing, and raw water was continuously passed through at SV = 2400 / h (1.5 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 Table 1.

[0044] For Experimental Examples 1 to 11, a linear approximation curve was obtained by the least squares method for the relationship between the particle size distribution D50 (μm) of the activated carbon and the initial flow rate (LPM). The obtained linear approximation curve is expressed by the following formula: Coefficient of determination of the linear approximation curve R ２ was 0.86. Initial flow rate (LPM) = 0.0701 × x + 0.377 where x represents the particle size distribution D50 (μm) of the activated carbon.

[0045] Chloroform removal performance was evaluated in accordance with JIS S3201 as follows. Test water with a chloroform concentration of 60 ppb was prepared. The water purification cartridge of each experimental example was attached to the housing, and water was passed through at SV = 2400 / h (1.5 L / min). The cumulative water flow rate (L) until the removal rate of the filtered water relative to the raw water reached 80% was measured. Hereinafter, this cumulative water flow rate (L) is also referred to as chloroform removal performance (L). The results are shown in Table 1.

[0046] For Experimental Examples 1 to 11, a linear approximation curve was obtained by the least squares method for the relationship between the particle size distribution D50 (μm) of the activated carbon and the chloroform removal performance (L). The obtained linear approximation curve is expressed by the following formula: The coefficient of determination of the linear approximation curve R ２ was 0.695. Chloroform removal performance (L) = -24.8 × x + 1893 where x represents the particle size distribution D50 (μm) of the activated carbon.

[0047] Based on the linear approximation curve showing the relationship between the particle size distribution D50 of the activated carbon and the chloroform removal performance (L), an estimated value of the chloroform removal performance (L) for each experimental example was calculated. The results are shown in the "Estimated value of chloroform removal performance (L)" column of Table 1.

[0048] The results of the experimental examples are as follows. Experimental examples 2 to 11 satisfy all of the following requirements a, b, and c. In contrast, experimental example 1 does not satisfy requirement b. Requirement a: Activated carbon and a fibrous binder are included. Requirement b: The median particle diameter D50 of the activated carbon is 16 μm or more and less than 27 μm. Requirement c: It is possible to produce a molded adsorbent by molding.

[0049] In Experimental Examples 2 to 11, the estimated chloroform removal performance was 1,200 L or more and the initial flow rate was 1.50 LPM or more. These Experimental Examples were able to improve the chloroform removal capacity and ensure the initial flow rate required for a molded adsorbent.

[0050] DESCRIPTION OF SYMBOLS 1...molded adsorbent, 3...activated carbon, 5...lead removal material, 7...fibrous binder, 7A...first fibrous binder, 7B...second fibrous binder, 11...water purification cartridge, 12...core, 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 binder, wherein the activated carbon has a median particle diameter D50 of 16 μm or more and less than 27 μm.

2. The molded adsorbent according to claim 1, wherein the measured value obtained as the median particle diameter D50 when the fibrous binder is measured using a laser diffraction / scattering particle size distribution measuring device is 50 μm or more and 140 μm or less.

3. The molded adsorbent according to claim 1 or claim 2, further comprising one or more lead removal materials selected from the group consisting of zeolite, titanium silicate, sodium titanate, aluminosilicate, and titanium oxide, wherein the median particle diameter D50 of the lead removal material is 25 μm or more and 40 μm or less.

4. A molded adsorbent described in any one of claims 1 to 3, wherein the content of the fibrous binder is 4% by mass or more and 12% by mass or less, when the molded adsorbent is 100% by mass.

5. A water purification cartridge comprising the molded adsorbent according to any one of claims 1 to 4.

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