Active carbon, manufacturing method thereof, water purifier cartridge and water purifier

Abstract

To provide active carbon capable of improving an amount of adsorption of chloroform under water conduction with regard to a unit volume of the active carbon, and a water purifier cartridge and a water purifier using the same.SOLUTION: Active carbon is for a water purifier. In the active carbon, a cumulative pore volume is 0.165 cm3 / g or more at a pore size 0.6 nm or less obtained by a pore analysis by a GCMC method with regard to absorption isotherm prepared setting an adsorption gas as N2, a cumulative pore volume is 0.050 cm3 / g to 0.120 cm3 / g, inclusive, at a pore size 2.0 nm to 200 nm, inclusive, obtained by a pore analysis by a BJH method with regard to absorption isotherm prepared setting an adsorption gas as N2, and a bulk density is 0.500 g / cm3 or more. A water purifier cartridge includes the active carbon. A water purifier includes the active carbon.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to activated carbon, a water purifier cartridge, and a water purifier. [Background technology]

[0002] Traditionally, chlorine has been added to tap water for sterilization. The reaction of this chlorine with organic compounds present in the water produces trihalomethanes, a by-product of tap water. Trihalomethanes are compounds in which three of the four hydrogen atoms in methane (CH4) have been replaced with halogen atoms such as chlorine (Cl) or bromine (Br). Specific examples of trihalomethanes include chloroform (CHCl3), bromodichloromethane (CHBrCl2), dibromochloromethane (CHBr2Cl), and bromoform (CHBr3). Many water purifiers are available on the market to remove substances such as chlorine and trihalomethanes from tap water.

[0003] Water purifiers generally contain an adsorbent that adsorbs (dynamically adsorbs) and removes the above-mentioned substances while the water is flowing through it. Activated carbon is often used as this type of adsorbent. Activated carbon is usually placed in a water purifier cartridge and disposed in the water flow path of the water purifier. A widely known example of activated carbon used in water purifiers is that made from carbonized and activated coconut shells. In addition to coconut shells, activated carbons made from synthetic resins such as phenolic resins have also been proposed.

[0004] For example, Patent Document 1 describes activated carbon with a density of 1.3 g / cm that has excellent adsorption performance for chloroform. 3 The following low-density paper-phenolic resin laminate is carbonized and gas-activated to produce activated carbon. Specifically, the activated carbon using this paper-phenolic resin laminate as a raw material has a BET specific surface area of ​​650 m. 2 / g or more 1250m 2 / g or less, total pore volume is 0.25 cm 3 / g or more, an average pore diameter of 1.8 nm or more and 4.0 nm or less, and a chloroform water flow rate of 71 L / g or more in the water flow test method described below. Water flow test method: Test water is passed through a column packed with 2.0 g of activated carbon with a particle size of 53 to 180 μm, and the chloroform concentration is measured before and after passing through the column. The total amount of filtered water (L) up to the breakthrough point is used to calculate the amount of chloroform passing per 1 g of activated carbon (L / g), which is the chloroform flow rate. Test water: Distilled water with a chloroform concentration of 0.06 mg / L Space velocity (SV): 500h -1 Chloroform concentration measurement method: Headspace gas chromatograph Breakthrough point: The point at which the concentration of chloroform in the column effluent exceeds 20% of the column inflow water. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6542968 Summary of the Invention [Problem to be solved by the invention]

[0006] Chloroform, one of the trihalomethanes present in tap water, is a substance present in a relatively high proportion, but is particularly difficult to adsorb to activated carbon. Therefore, conventionally known activated carbon cannot adequately adsorb and remove chloroform when water is flowing through it. Furthermore, in recent years, there has been a trend toward space-saving water purifiers, and as a result, the volume of the space in which activated carbon is filled, such as the capacity of water purifier cartridges, has become limited. From these perspectives, it is important for activated carbon used in water purifiers to improve the amount of chloroform adsorption per unit volume of activated carbon when water is flowing through it. If this could be achieved, it would be possible to adsorb and remove chloroform with a smaller volume of activated carbon.

[0007] It is possible to simply increase the pore volume of activated carbon in order to improve the amount of chloroform adsorbed when water is flowing through it. However, such an improvement in the pore structure reduces the packing density of the activated carbon, thereby reducing the weight of activated carbon that can be added to a water purifier, making it difficult to improve the amount of chloroform adsorbed per unit volume of activated carbon when water is flowing through it. Furthermore, as described in Patent Document 1, improving the pore structure to increase the amount of chloroform adsorbed per unit weight of activated carbon when water is flowing through it would require, for example, packing more activated carbon into a water purifier cartridge or the like in order to sufficiently remove chloroform.

[0008] The present invention has been made in view of the above problems, and aims to provide activated carbon that can increase the amount of chloroform adsorbed per unit volume of activated carbon while water is flowing through it, as well as a water purifier cartridge and a water purifier that use the same. [Means for solving the problem]

[0009] One aspect of the present invention is Activated carbon for a water purifier, The cumulative pore volume of pores with diameters of 0.6 nm or less was determined by GCMC pore analysis using an adsorption isotherm prepared using N2 as the adsorption gas, and was found to be 0.165 cm 3 / g or more, The cumulative pore volume of the pores with diameters between 2.0 nm and 200 nm determined by the BJH method using an adsorption isotherm created using N2 as the adsorption gas was 0.050 cm 3 / g or more 0.120cm 3 / g or less, Packing density is 0.500g / cm 3 That's all. It's in activated carbon.

[0010] Another aspect of the present invention is A water purifier cartridge having the activated carbon.

[0011] Another aspect of the present invention is A water purifier having the activated carbon. [Effects of the Invention]

[0012] The activated carbon has the above-described structure, and therefore, the activated carbon can improve the amount of chloroform adsorbed per unit volume of activated carbon when water is passed through it.

[0013] The water purifier cartridge includes the activated carbon, and therefore, with a smaller volume of activated carbon, the water purifier cartridge can improve the adsorption and removal performance of chloroform when water flows through a water purifier to which the water purifier cartridge is attached.

[0014] The water purifier includes the activated carbon, and therefore, with the water purifier, it is possible to improve the adsorption and removal performance of chloroform when water is flowing through it, with a smaller volume of activated carbon. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 shows the relationship between the pore diameter W (nm) (horizontal axis) and the cumulative pore volume ΣVp (cm3 / g) (vertical axis) for each sample of activated carbon obtained by pore analysis using the GCMC method for adsorption isotherms prepared using N2 as the adsorption gas in an experimental example. [Figure 2] FIG. 2 shows the relationship between the pore diameter dp (nm) (horizontal axis) and the cumulative pore volume ΣVp (cm3 / g) (vertical axis) for each sample of activated carbon obtained by pore analysis using the BJH method for adsorption isotherms created using N2 as the adsorption gas in an experimental example. DETAILED DESCRIPTION OF THE INVENTION

[0016] The activated carbon, the cartridge for a water purifier, and the water purifier of this embodiment will be described.

[0017] (activated carbon) The activated carbon of this embodiment is for use in a water purifier. Here, "for use in a water purifier" means that the activated carbon is used in a water purifier, and includes, for example, a case where the activated carbon is placed in a water purifier cartridge and the water purifier cartridge is built into the water purifier, and a case where the activated carbon is placed directly in the water purifier.

[0018] The activated carbon of this embodiment has a cumulative pore volume of pores with diameters of 0.6 nm or less (hereinafter sometimes referred to as "cumulative pore volume of pores with diameters of 0.6 nm or less") of 0.165 cm2, as determined by pore analysis using the GCMC (Grand Canonical Monte Carlo) method for an adsorption isotherm created using N2 as the adsorption gas. 3 / g or more. In the field of activated carbon, the GCMC method is mainly used to measure the pore distribution in the region from micropores (pores with a diameter of 2 nm or less) to mesopores (pores with a diameter between 2 and 50 nm). Therefore, the activated carbon of this embodiment, which specifies a cumulative pore volume for pore diameters of 0.6 nm or less, can be said to have micropores. Note that the pore diameter referred to above means the pore diameter.

[0019] Pores with a diameter of 0.6 nm or less, preferably 0.59 nm or less, and more preferably 0.58 nm or less are micropores effective for chloroform adsorption. 3 If the cumulative pore volume is less than 0.167 cm / g, the pore volume with a diameter of 0.6 nm or less that is effective for chloroform adsorption will be insufficient, and the amount of chloroform adsorbed under constant volume water flow will decrease. 3 / g or more, more preferably 0.170 cm 3 / g or more, more preferably 0.171 cm 3 / g or more, and even more preferably 0.172 cm 3 / g or more, and even more preferably 0.173 cm 3 The upper limit of the cumulative pore volume for pores with diameters of 0.6 nm or less is, for example, 0.2 cm from the viewpoint of suppressing a decrease in the packing density of the activated carbon and ensuring the strength of the structure. 3 / g or less.

[0020] In calculating the cumulative pore volume for pores with a diameter of 0.6 nm or less, the adsorption isotherm using N2 as the adsorption gas was measured at 400°C and 10 -3 After pretreatment under the condition of maintaining the pressure at 0.1 kPa or less for 4 hours, the gas adsorption can be measured using a gas adsorption analyzer (Microtrac-Bell, "BELSORP MAX 2"). The cumulative pore volume for pores with a diameter of 0.6 nm or less can be calculated in accordance with JIS Z8831-2 using the adsorption isotherm measured above. If the specific gas adsorption analyzer described above is discontinued, its successor can be used.

[0021] The activated carbon of this embodiment has a cumulative pore volume (hereinafter sometimes referred to as "cumulative pore volume by the BJH method") of 0.050 cm for pore diameters of 2.0 nm or more and 200 nm or less, determined by pore analysis by the BJH (Barrett-Joyner-Halenda) method using an adsorption isotherm created using N2 as the adsorption gas. 3 / g or more 0.120cm 3 / g or less. The BJH method is used in the field of activated carbon to measure the pore distribution mainly in the mesopore region (pores with diameters between 2 and 50 nm). Therefore, the activated carbon of this embodiment, which specifies the cumulative pore volume by the BJH method, can be said to have mesopores. The lower and upper limits of the pore diameter range in the BJH method are calculated values ​​based on a general definition. That is, the lower limit of the pore diameter range in the BJH method is derived from the definition of mesopores as 2 nm or more (IUPAC definition) (i.e., the calculation formula itself can calculate up to around 1 nm, so the definition of mesopores has a lower limit of 2 nm), and the upper limit of the pore diameter range in the BJH method is due to the fact that the calculation formula can only calculate up to 200 nm. Furthermore, the pore diameter referred to above means the pore diameter.

[0022] The cumulative pore volume measured by the BJH method is an important indicator for the adsorption of chloroform under water flow (dynamic adsorption). 3 If the cumulative pore volume is less than 0.055 cm / g, the amount of chloroform adsorbed when water is passed through a constant volume column will be small, making it difficult to improve the amount of chloroform adsorbed when water is passed through the column per unit volume of activated carbon. 3 / g or more, more preferably 0.060 cm 3 / g or more, more preferably 0.065 cm 3 The upper limit of the cumulative pore volume by the BJH method is 0.120 cm3 from the viewpoints of suppressing a decrease in the packing density of the activated carbon and ensuring the strength of the structure. 3 The upper limit of the cumulative pore volume according to the BJH method is preferably 0.110 cm 3 / g or less, more preferably 0.100 cm 3 / g or less, more preferably 0.090 cm 3 / g or less, and even more preferably 0.080 cm 3 / g or less.

[0023] In calculating the cumulative pore volume by the BJH method, the adsorption isotherm using N2 as the adsorption gas was measured at 400°C and 10 -3 After pretreatment under the condition of maintaining the pressure at or below 100 kPa for 4 hours, the gas adsorption can be measured using a gas adsorption analyzer (Microtrac-Bell, "BELSORP MAX 2"). The cumulative pore volume measured by the BJH method can be calculated in accordance with JIS Z8831-2 using the adsorption isotherm measured above. If the specific gas adsorption analyzer mentioned above is no longer available, its successor can be used.

[0024] The activated carbon of this embodiment has a packing density of 0.500 g / cm 3or more. In the activated carbon of this embodiment, the packing density is an important physical property for adsorbing and removing chloroform with a smaller volume of activated carbon in water purifier cartridges and water purifiers where the spatial volume of activated carbon packed therein is limited. The packing density is measured in accordance with JIS K1474 7.8.5 Powder Packing Method for sample powders collected by classifying the activated carbon and having a particle size range of 38 μm to 75 μm. However, in the case of activated carbon that is originally in the particle size range of 38 μm to 75 μm, the classification may not be necessary. The reason for setting the particle size range to 38 μm to 75 μm is to match the particle size range often required by water purifier manufacturers as activated carbon specifications in the water purifier field.

[0025] Packing density of activated carbon is 0.500g / cm 3 If the packing density is less than 0.510 g / cm, the volume of activated carbon required to sufficiently adsorb chloroform while water is flowing through the activated carbon increases, making it difficult to adsorb and remove chloroform with a smaller volume of activated carbon. 3 More preferably, 0.520 g / cm 3 More preferably, 0.530 g / cm 3 More preferably, 0.540 g / cm 3 The upper limit of the packing density of the activated carbon in this embodiment is, for example, 0.650 g / cm from the viewpoint of water permeability and uniform dispersion of the activated carbon in the water purifier cartridge. 3 It can be as follows:

[0026] The present inventors have conducted trial and error to find an appropriate pore distribution for chloroform adsorption in activated carbon, and have found that a pore volume with a pore diameter of 0.6 nm or less contributes to an improvement in the amount of chloroform adsorbed per unit volume of activated carbon, and that a mesopore volume of at least a certain volume enables the activated carbon to fully exhibit chloroform adsorption performance per unit volume even under dynamic adsorption. The present inventors then investigated various raw materials that have a high bulk density from the start and raw materials whose bulk density can be increased by pelletizing or compression processing, and have found an activated carbon with a pore distribution and high packing density that are appropriate for chloroform-adsorbing activated carbon for use in water purifiers.

[0027] As described above, the activated carbon of this embodiment has a sufficient pore volume with a pore diameter of 0.6 nm or less that is effective for chloroform adsorption, and also has the pore volume measured by the BJH method that is necessary for adsorption under water flow, while ensuring a packing density. Therefore, the activated carbon of this embodiment can improve the amount of chloroform adsorbed under water flow per unit volume of activated carbon.

[0028] The activated carbon of this embodiment is preferably made from plant biomass. That is, the activated carbon of this embodiment is preferably derived from plant biomass. This configuration makes it easier to reduce the cost of activated carbon compared to when synthetic resins such as phenolic resins are used as raw materials. Furthermore, plant biomass contains lignocellulose, which is the main component of plant cell walls and forms the skeleton of plants, and this has an advantageous effect on the formation of a predetermined pore distribution compared to synthetic resins such as phenolic resins. Plant biomass also has the advantage of being a sustainable resource.

[0029] Furthermore, from the perspective of carbon neutrality, which helps curb global warming, plant biomass can be said to be a more environmentally friendly raw material than phenolic resin, which is made from fossil resources.

[0030] Specific examples of plant biomass include trees (woody plants), flowers (herbaceous plants), seed husks, and fruits. These can be used alone or in combination of two or more. More specific examples of the trees include conifers such as cedar and cypress, broad-leaved trees such as camellia and apple trees, and grasses such as bamboo. Furthermore, using plant biomass such as cedar, cypress, and bamboo, which can be procured domestically in Japan, as a raw material rather than coconut shells, which are produced only in South and Southeast Asia, has the advantage of leading to the effective use of unused resources such as thinned wood, sawdust, and bamboo from abandoned bamboo forests, which have low sales value as lumber.

[0031] Cedar is particularly suitable as the above-mentioned tree. The reason is as follows. That is, the pore distribution and packing density of activated carbon are highly dependent on the raw material. With conventional raw materials such as phenolic resin, pitch, and coconut shell, it is difficult to form mesopores (generally pores measured by the BJH method) and micropores (generally pores measured by the GCMC method) required to achieve the above-mentioned pore volume specified for the activated carbon of this embodiment while simultaneously satisfying the above-mentioned packing density requirements. For example, phenolic resin tends to easily grow micropores but has difficulty growing mesopores. Even if activated carbon satisfying the above-mentioned pore volume could be produced using these raw materials, it is expected that the packing density would likely be low.

[0032] Additionally, activated carbon made from coconut shells, a type of plant-based biomass, has traditionally been used primarily in water purifiers. However, activated carbon made from coconut shells is primarily composed of micropores, a characteristic of coconut shells. Therefore, it is necessary to increase the packing density by miniaturizing the particle size of the activated carbon to improve adsorption performance. This makes it difficult to improve chloroform adsorption performance by adjusting the pore distribution, which also contributes to the increased cost of water purifiers. Furthermore, coconut shells are a plant-based biomass that is dependent on imports, and compared to plant-based biomass produced in Japan, there is a potential issue of whether stable imports will be possible in the future.

[0033] In contrast, cedar is a material in which mesopores (relatively large pores) and micropores (relatively small pores) are easily formed simultaneously, even without extensive activation treatment. Therefore, when cedar is used as the raw material, it is easy to obtain activated carbon that simultaneously satisfies the three requirements of cumulative pore volume measured by the GCMC method, cumulative pore volume measured by the BJH method, and packing density. However, this does not necessarily mean that the above three requirements will be met if cedar is used as the raw material, as will be understood from the experimental examples described below.

[0034] Furthermore, cedar is a common material in Japan, often produced as thinning material, making it easy to secure a stable supply of raw material within the country. Therefore, when cedar is used as the raw material, there is no need to refine the particle size of the activated carbon to improve packing density and chloroform adsorption performance. Packing density and chloroform adsorption performance can be improved primarily through an approach based on pore distribution, making it easier to reduce the production cost of activated carbon.

[0035] The activated carbon of this embodiment has a chloroform flow rate of preferably 20 L / cm in a chloroform flow test. 3 More preferably, 21 L / cm 3 More preferably, 22 L / cm 3 or more, and even more preferably 23 L / cm 3 It can be more than that.

[0036] The chloroform water flow rate is a value measured by the following water flow test method: A column packed with 0.36 mL of sample powder, which is obtained by classifying the activated carbon of this embodiment and has a particle size range of 38 μm to 75 μm, and which is dried at 110° C. for 3 hours or more, is subjected to a water flow test at a temperature of 20° C. and a space velocity (SV) of 500 h. -1 Distilled water with a chloroform concentration of 60 μg / L was passed through the column, and the chloroform concentration was measured before and after passing through the column. The point at which the chloroform concentration after passing through the column exceeded 20% of the chloroform concentration before passing through the column was set as the breakthrough point, and the activated carbon capacity (cm) was calculated from the total amount of water (L) passed up to the breakthrough point. 3) per chloroform flow rate (L / cm 3 ) is calculated and this is the amount of chloroform passing through in the chloroform water passing test. The water passing test method complies with JIS S3201, and details will be described later in the experimental examples.

[0037] It is usually difficult to identify the raw materials used for activated carbon from activated carbon itself, but activated carbon that simultaneously satisfies the three requirements of the present embodiment, i.e., the cumulative pore volume measured by the GCMC method, the cumulative pore volume measured by the BJH method, and the packing density, cannot be obtained from commonly used conventional materials such as coconut shells, which will be described in the experimental examples below. Therefore, by specifying the amount of chloroform passing through in the chloroform water passing test, the difference in effect from conventional activated carbon becomes clearer, and it is possible to more clearly distinguish the activated carbon from conventional activated carbon.

[0038] The activated carbon of this embodiment can be produced, for example, as follows, but is not limited to this.

[0039] Raw materials such as plant biomass are crushed and, if necessary, pelletized or compressed. Pelletization or compression is useful for increasing the bulk density of the raw material. When plant biomass is used as the raw material, the packing density may be low, so pelletization or compression is preferred. In other words, for raw materials with low bulk density, it is preferred to increase the bulk density of the raw material by pelletizing or compression at the raw material stage so as to increase the packing density of activated carbon. Note that when the size of the crushed pieces is sufficient to not affect productivity (for example, size of crushed pieces: about 10 to 30 mm) and the bulk density of the raw material is sufficient (for example, bulk density: 0.65 to 0.95 g / cm 3For materials with a bulk density of approximately 1000 sq m (approximately 1000 sq ft), pelleting or compression may not be necessary. The bulk density of the raw material can be increased by optimizing the processing conditions during pelleting or compression. For example, when using a flat-type pelletizer, raw material with the desired bulk density can be obtained by adjusting the moisture content of the raw material, the amount of raw material input, the rotation speed of the compression roller, the die temperature, the die diameter (pellet diameter), etc.

[0040] The prepared raw material is then carbonized to obtain a carbonized product. Examples of carbonization conditions include a nitrogen atmosphere, a carbonization temperature of 700 to 900°C, a heating rate up to the carbonization temperature of 2 to 10°C / min, and a holding time of 5 to 60 minutes.

[0041] The carbonized product is then activated to obtain activated carbon. Examples of activation conditions include a carbonization atmosphere of nitrogen, an activation temperature of 750 to 950°C, an activator such as water vapor, carbon dioxide, or an alkali agent, a rate of temperature increase up to the activation temperature of 5 to 20°C / min, and a retention time of 10 to 900 minutes.

[0042] The activated carbon obtained may be subjected to pulverization, classification, or the like, if necessary.

[0043] (Water purifier cartridge) The water purifier cartridge of this embodiment includes the activated carbon of this embodiment described above. Specifically, the water purifier cartridge of this embodiment may include only the activated carbon of this embodiment, or may include the activated carbon of this embodiment and activated carbon other than that of this embodiment. That is, the water purifier cartridge of this embodiment may use the activated carbon of this embodiment as part of the adsorbent, or may use the activated carbon of this embodiment for the entire adsorbent. Note that when the water purifier cartridge of this embodiment includes the activated carbon of this embodiment as part of the adsorbent, the remainder of the adsorbent may be, for example, a known activated carbon suitable for adsorbing and removing substances other than chloroform contained in tap water.

[0044] The shape of the water purifier cartridge of this embodiment is not particularly limited, and any known shape can be appropriately selected.

[0045] The water purifier cartridge of this embodiment contains the activated carbon of this embodiment, and therefore can improve the chloroform adsorption and removal performance when water flows through a water purifier to which the water purifier cartridge is attached, even with a smaller volume of activated carbon. Furthermore, the water purifier cartridge of this embodiment has improved chloroform adsorption and removal performance, which can contribute to extending the life of the water purifier cartridge in terms of chloroform adsorption and removal.

[0046] (Water purifier) The water purifier of this embodiment includes the activated carbon of this embodiment described above. Specifically, the water purifier of this embodiment may include only the activated carbon of this embodiment, or may include the activated carbon of this embodiment and activated carbon other than that of this embodiment. That is, the water purifier of this embodiment may use the activated carbon of this embodiment as part of the adsorbent, or may use the activated carbon of this embodiment as the entire adsorbent. Note that when the water purifier of this embodiment includes the activated carbon of this embodiment as part of the adsorbent, the remainder of the adsorbent may be, for example, a known activated carbon suitable for adsorbing and removing substances other than chloroform contained in tap water.

[0047] In the water purifier of this embodiment, the activated carbon of this embodiment may be placed in a water purifier cartridge that is attached to the water purifier, or may be placed directly in the water purifier without being placed in a water purifier cartridge. Note that the water purifier of this embodiment includes a faucet fitting or the like that has a water purification function.

[0048] The water purifier of this embodiment includes the activated carbon of this embodiment, and therefore can improve the adsorption and removal performance of chloroform while water is flowing through it, even with a smaller volume of activated carbon. Furthermore, the improved adsorption and removal performance of chloroform in the water purifier of this embodiment can contribute to extending the life of the water purifier with respect to adsorption and removal of chloroform.

[0049] (Experimental example) <Preparation of each activated carbon> -Activated carbon of sample 1- Cedar trunks were crushed to approximately 20-30 mm in size using a crusher (Ohashi Co., Ltd., "GS121GB") and then pelletized using a flat die pelletizer (Shinko Koki Co., Ltd., "Biomass Pellet Maker S-60") to a diameter of approximately 6 mm and length of 20 mm, with a bulk density of 0.67 g / cm as measured in accordance with JIS Z7302-9. 3 Cedar pellet raw material was prepared.

[0050] Next, 12 kg of cedar pellet raw material was placed in a kiln, heated to 850°C at a rate of 5°C / min in a nitrogen atmosphere, and then held at that temperature for 30 minutes to obtain 3.14 kg of cedar pellet carbonized material.

[0051] Next, 780 g of the resulting cedar pellet carbonized material was placed in a kiln and heated to 850°C at a rate of 10°C / min under a nitrogen atmosphere. After that, steam activation was performed by circulating steam through the furnace at 12 g / min for 75 minutes, and 520 g of cedar pellet activated carbon was obtained.

[0052] Next, the cedar pellet activated carbon was crushed and classified to obtain powdered activated carbon with a particle size ranging from 38 μm to 75 μm. This was designated as Sample 1 activated carbon.

[0053] -Activated carbon of sample 2- 450 g of cedar pellet activated carbon was obtained in the same manner as in the preparation of activated carbon for sample 1, except that steam activation was performed by passing steam through the furnace at 12 g / min for 100 minutes. This was designated as activated carbon for sample 2.

[0054] -Activated carbon of sample 1C- 400 g of cedar pellet activated carbon was obtained in the same manner as in the preparation of activated carbon for Sample 1, except that steam activation was performed by passing steam through the furnace at 12 g / min for 125 minutes. This was designated as activated carbon for Sample 1C.

[0055] -Activated carbon of sample 2C- The same procedure was used to prepare activated carbon from sample 1, except that steam activation was performed by passing steam through the furnace at 12 g / min for 50 minutes, yielding 610 g of activated carbon from cedar pellets. This was designated sample 2C.

[0056] -Activated carbon of sample 3C- Commercially available activated carbon made from coconut shells was used as the activated carbon for Sample 3C, which was prepared by pulverization and classification into a powder with a particle size ranging from 38 μm to 75 μm.

[0057] <Physical properties of each activated carbon> As described above, the adsorption isotherm of each activated carbon was measured using a gas adsorption measurement device (Microtrack-Bell, "BELSORP MAX 2") with N2 as the adsorption gas. Next, for each obtained adsorption isotherm, the cumulative pore volume ΣVp (cm) of pores with a pore diameter (W) of 0.6 nm or less was calculated by pore analysis using the GCMC method, as described above. 3 / g), and cumulative pore volume ΣVp (cm) for pore diameters (dp) of 2.0 nm to 200 nm, as determined by pore analysis using the BJH method. 3 / g) was measured.

[0058] <Chloroform passing amount for each activated carbon> The amount of chloroform passing through each activated carbon (L / cm) was measured using the following water flow test method. 3 ) was measured.

[0059] Each activated carbon was adjusted to a particle size range of 38 μm to 75 μm by crushing and classification, and then dried at 110°C for at least 3 hours. 0.36 mL of the activated carbon was then accurately measured and weighed. This activated carbon was packed into an adsorption column with an inner diameter of 9 mm, leaving no gaps, and pure water was passed through the column for at least 8 hours to degas it.

[0060] Next, a water flow test was carried out in accordance with JIS S3201 under the following conditions.

[0061] Specifically, the column after degassing was heated at a temperature of 20°C and a space velocity (SV) of 500 h -1Distilled water with a chloroform concentration of 60 μg / L was passed through the column. Test water was sampled at specified times before and after passing through the column, and the chloroform concentration before and after passing through the column was measured using a trihalomethane meter (manufactured by DKK-TOA Corporation, "THM-201").

[0062] The point at which the chloroform concentration after passing through the column exceeds 20% of the chloroform concentration before passing through the column is defined as the breakthrough point, and the total amount of water (L) passed up to the breakthrough point is subtracted from the activated carbon capacity (cm 3 ) per chloroform flow rate (L / cm 3 ) was calculated (see Equation 1 below), and this was taken as the amount of chloroform passing through in the chloroform passing test. Chloroform flow rate (L / cm 3 ) = (total amount of water passed up to the breakthrough point (L)) / (activated carbon capacity (cm 3 ))...Equation 1

[0063] The raw materials, physical properties, and water flow test results of each sample of activated carbon are summarized in Table 1. Figure 1 also shows the pore diameter W (nm) (horizontal axis) and cumulative pore volume ΣVp (cm) of each sample of activated carbon obtained by pore analysis using the GCMC method. 3 / g) (vertical axis). Figure 2 shows the relationship between the pore diameter dp (nm) (horizontal axis) and cumulative pore volume ΣVp (cm) for each sample of activated carbon obtained by pore analysis using the BJH method. 3 / g) (vertical axis).

[0064] [Table 1]

[0065] Table 1, Figure 1, and Figure 2 reveal the following:

[0066] The activated carbon of sample 1C had a high cumulative pore volume measured by the BJH method, resulting in a low packing density. As a result, the amount of chloroform adsorbed when water was passed through a constant-volume column was significantly reduced.

[0067] Furthermore, although the activated carbon of sample 2C had a sufficient packing density, the required cumulative pore volume measured by the BJH method and the cumulative pore volume for pores with a diameter of 0.6 nm or less were both low, resulting in a low amount of chloroform adsorption when water was passed through a constant-volume column.

[0068] Furthermore, although the activated carbon of sample 3C had sufficient cumulative pore volume and packing density for pores with diameters of 0.6 nm or less, the cumulative pore volume measured by the BJH method was low, which made it difficult for the chloroform adsorption action to work when water was passed through the activated carbon, resulting in a low amount of chloroform adsorption when water was passed through a constant-volume column.

[0069] From these findings, it can be said that in the case of activated carbon used in water purifier cartridges and water purifiers, which have limited capacity, if emphasis is placed on micropores, the chloroform adsorption performance cannot be fully demonstrated under dynamic adsorption, and if emphasis is placed on mesopores or macropores, the packing density of the activated carbon decreases, reducing the weight of activated carbon that can be put into the water purifier cartridge or water purifier, and as a result, the chloroform adsorption performance of the water purifier itself decreases.

[0070] In contrast to the above, the activated carbons of Samples 1 and 2 had a sufficient pore volume with a pore diameter of 0.6 nm or less that was effective for chloroform adsorption, and were able to ensure a packing density while also providing the pore volume measured by the BJH method that was necessary for adsorption under water flow. Therefore, it was confirmed that the activated carbon of the present disclosure can improve the amount of chloroform adsorbed under water flow per unit volume of activated carbon.

[0071] The present invention is not limited to the above-described embodiments and experimental examples, and various modifications are possible within the scope of the gist thereof. Furthermore, the configurations shown in the above-described embodiments and experimental examples can be arbitrarily combined with each other. Furthermore, the claims set forth in the scope of the claims as originally filed can be arbitrarily combined with each other.

Claims

1. Activated carbon for a water purifier, The adsorbed gas is N ２ The cumulative pore volume of pores with diameters of 0.6 nm or less was determined by pore analysis using the GCMC method for the adsorption isotherm created as follows: 0.165 cm ３ / g or more, The adsorbed gas is N ２ The cumulative pore volume in the pore diameter range of 2.0 nm to 200 nm obtained by pore analysis using the BJH method was 0.050 cm ３ / g or more 0.120cm ３ / g or less, Packing density is 0.500 g / cm ３ That's all. activated carbon.

2. Made from plant biomass, Activated carbon according to claim 1.

3. A water purifier cartridge comprising the activated carbon according to claim 1 or 2.

4. A water purifier comprising the activated carbon according to claim 1 or 2.

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