Activated carbon and an adsorption filter, a water purifier using the activated carbon, and a manufacturing method of activated carbon

Abstract

The present invention relates to an activated carbon having a BET specific surface area of 500 m 2 / g or more, and, in the solid state 19 A peak derived from F is observed between -100 and -120 ppm in F-NMR measurement. 19 F.

Description

Technical Field

[0001] This invention relates to activated carbon, adsorption filters and water purifiers using the activated carbon, and methods for manufacturing activated carbon. In particular, it relates to activated carbon used in water treatment for removing perfluoroalkyl and polyfluoroalkyl compounds from water. Background Technology

[0002] Due to the unique properties that fluorinated organic compounds cannot achieve with other substances (excellent heat resistance, chemical resistance, usability under harsh conditions, and no light absorption), they have been used in various applications such as surfactants, emulsifiers, waterproofing agents, fire extinguishing agents, waxes, carpet cleaners, and coating agents. Recently, they have also been increasingly used as functional materials such as surface treatment agents for semiconductors and components of fuel cells.

[0003] However, starting a few years ago, researchers, primarily in the United States and Canada, reported that some fluorinated organic compounds were accumulating in environmental water and wildlife. A typical example is perfluorooctanoic acid (PFOA: C7F). 15 Perfluorocarboxylic acids, represented by COOH, and perfluorooctane sulfonic acid (PFOS: C8F) 17 Perfluorosulfonic acids, represented by SO3H, are a type of fluorinated organic compound (PFC). Furthermore, researchers in Europe and Japan subsequently participated in environmental analysis studies, which confirmed the presence of these compounds in the environment globally, including in Japan. In response, efforts have begun to reduce PFC levels. S Environmental risks.

[0004] Patent Document 1 discloses a method for recovering PFOA using granular activated carbon. It should be noted that perfluoroalkyl compounds have fully fluorinated straight-chain alkyl groups, such as perfluorooctanoic acid (PFOA) (IUPAC name: 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecanoic acid) and perfluorooctane sulfonic acid (PFOS), as shown in the following chemical formula.

[0005] However, while the method of using activated carbon in the treatment of PFOA, as in Patent Document 1, has significant economic advantages, the treatment efficiency of previous technologies is not satisfactory.

[0006] Therefore, in view of the above situation, the main objective of the present invention is to provide activated carbon that can effectively remove fluorinated organic compounds, and an adsorption filter and water purifier using the activated carbon for treating water containing fluorinated organic compounds.

[0007] Existing technical documents Patent documents Patent Document 1: U.S. Patent Application Publication No. 2005 / 0000904. Summary of the Invention

[0008] The inventors conducted dedicated research to solve the aforementioned problems and discovered that activated carbon with the following composition could solve these problems. Based on this insight, they conducted further and repeated research, thereby completing the present invention.

[0009] That is, the first technical solution of the present invention relates to an activated carbon with a BET specific surface area of ​​500 m². 2 / g or more, and in solid state 19 In F-NMR measurements, ions originating from [source] were observed in the range of -100 to -120 ppm. 19 The peak of F. Attached Figure Description

[0010] Figure 1 The activated carbon obtained in the examples represents 19 Results of F-NMR measurements.

[0011] Figure 2 This is a comparative graph showing the removal effect of activated carbon on perfluorooctanoic acid (PFOA) of Examples 1, 3 and Comparative Example 1.

[0012] Figure 3 This is a comparison graph showing the removal effect of activated carbon in Example 2 and Comparative Example 2 on perfluorooctanoic acid (PFOA). Detailed Implementation

[0013] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0014] (Activated carbon) The activated carbon in this embodiment has a BET specific surface area of ​​500 m². 2 / g or more, in solid state 19 In F-NMR measurements, ions originating from [source] were observed in the range of -100 to -120 ppm. 19 The peak of F.

[0015] Based on the above composition, activated carbon capable of effectively removing fluorinated organic compounds, an adsorption filter using the activated carbon for treating water containing fluorinated organic compounds, and a water purifier can be provided.

[0016] Activated carbon is known to have a low number of functional groups relative to its specific surface area and is generally hydrophobic in water. On the other hand, perfluoroalkyl and polyfluoroalkyl compounds are amphiphilic, meaning they possess hydrophobic groups derived from CF bonds and hydrophilic groups such as carboxylic acids and sulfonic acids. It is generally believed that activated carbon, as a hydrophobic substance, adsorbs perfluoroalkyl and / or polyfluoroalkyl compounds in its pores, and the adsorption is attributed to hydrophobic interactions.

[0017] The activated carbon in this embodiment has a density of at least 500m. 2 A specific surface area of ​​500 μm or higher is sufficient. Specific surface area originates from the fine pores formed by activated carbon to adsorb substances; for example, a specific surface area of ​​500 μm is desirable. 2 A specific surface area of ​​600–3500 m² / g or higher ensures sufficient surface area for adsorption of substances. While there is no particular upper limit to the specific surface area, an excessively large surface area reduces the mechanical strength of the activated carbon and is therefore not preferred. From the viewpoint of more effectively thermally decomposing adsorbed perfluoroalkyl and / or polyfluoroalkyl compounds and suppressing the decrease in mechanical strength, a specific surface area of ​​600–3500 m² / g is preferred. 2 The range of / g is more preferably 750–2500m. 2 The range is / g. Specifically, it can also be 500m. 2 / g、750m 2 / g, 1000m 2 / g、1250m 2 / g, 1500m 2 / g、1750m 2 / g、2000m 2 / g、2250m 2 / g、2500m 2 / g、2750m 2 / g、3000m 2 / g、3250m 2 / g、3500m 2 / g etc.

[0018] In this embodiment, BET specific surface area refers to the specific surface area calculated by the nitrogen adsorption method and measured by the method described in the examples below.

[0019] The inventors believe that, in addition to the specific surface area, the presence of fluorine derived from CF bonds in activated carbon can enhance the affinity for perfluoroalkyl and / or polyfluoroalkyl compounds having CF bonds, thereby enabling more efficient adsorption. Based on this insight, adsorption carbons for perfluoroalkyl and / or polyfluoroalkyl compounds are described.

[0020] The activated carbon in this embodiment is in solid state.19 In F-NMR measurements, ions originating from [source] were observed in the range of -100 to -120 ppm. 19 The peak of F. Solid state. 19 F-NMR measurements can be performed without particular limitation as long as they are performed using an NMR apparatus capable of obtaining NMR spectra of solid samples by nuclear magnetic resonance (NMR) methods. For example, the apparatus used in the examples described later can be used for the measurements.

[0021] It is believed that the activated carbon that exhibited the above peaks as described above contains fluorine, and therefore has a high affinity for perfluoroalkyl compounds and / or polyfluoroalkyl compounds.

[0022] In the solid 19 F-NMR measurements originating from 19 The F peak is preferably derived from fluorine bonded to the activated carbon. Accordingly, since fluorine originating from the CF bond is present in the activated carbon, its affinity for perfluoroalkyl compounds and / or polyfluoroalkyl compounds having CF bonds is considered to be further enhanced, and the activated carbon of this embodiment adsorbs perfluoroalkyl compounds and / or polyfluoroalkyl compounds more effectively.

[0023] The fluorine content, relative to 100% by weight of the activated carbon in this embodiment, is preferably 0.0001% by weight or more. Regarding the fluorine content of the activated carbon, its presence in trace amounts can improve adsorption performance. The preferred fluorine content, relative to 100% by weight of the activated carbon, can be 0.0001 to 5% by weight, or 0.0001 to 3% by weight, 0.0001 to 2% by weight, 0.001 to 1.5% by weight, 0.001 to 1% by weight, 0.001 to 0.2% by weight, 0.005 to 0.15% by weight, or 0.01 to 0.1% by weight. Specifically, it can be 0.0001% by weight, 0.0005% by weight, 0.001% by weight, 0.002% by weight, 0.005% by weight, 0.01% by weight, 0.05% by weight, 0.1% by weight, 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, etc.

[0024] In this embodiment, the activated carbon can be any one selected from powdered activated carbon, fibrous activated carbon, granular activated carbon, and block activated carbon. Fibrous activated carbon is obtained by carbonizing and activating suitable fibers, such as phenolic resin-based, acrylic resin-based, cellulose-based, and coal tar pitch-based fibers. The fiber length and cross-sectional diameter are appropriately selected.

[0025] Raw materials for granular activated carbon include wood (waste wood, thinnings, sawdust), coffee grounds, rice husks, coconut shells, bark, and fruits. These naturally sourced raw materials undergo carbonization and activation, resulting in well-developed micropores. Furthermore, because they represent a secondary use of waste materials, they can be purchased inexpensively. Additionally, tires, petroleum asphalt, calcined products derived from synthetic resins (polyurethane resins, phenolic resins, etc.), and coal can also be used as raw materials.

[0026] In this embodiment, the activated carbon is preferably in powder, granular, or block form.

[0027] Powdered activated carbon and block activated carbon can be manufactured by crushing or molding the above-mentioned fibrous or granular activated carbon.

[0028] (Methods for manufacturing activated carbon) The activated carbon of this embodiment can be obtained, for example, by activating the activated carbon raw material as described above, causing the activated carbon raw material (activated carbon as the matrix) to adsorb fluorine-containing compounds, and then heat-treating the activated carbon with fluorine-containing compounds attached at a temperature above the decomposition start temperature of the fluorine-containing compounds.

[0029] Activated carbon raw materials can be heated and carbonized in a temperature range of 200℃ to 600℃ as needed, thereby fixing the carbon and forming micropores. Carbonization is usually carried out in the absence of oxygen or air.

[0030] Next, the activated carbon raw material is activated by exposing it to water vapor, carbon dioxide gas, or mixtures thereof in a temperature range of 600°C to 1200°C. This results in activated carbon with various well-developed pore structures. Considering safety and reactivity, it is preferable to use a water vapor gas containing 10–40% by volume of water vapor as the activation gas. The activation time and heating rate are not particularly limited and can be appropriately selected based on the type, shape, and size of the selected carbonaceous material. It should be noted that, in addition to the gas activation method described above, chemical activation (chemical activation) by adding potassium hydroxide and / or zinc chloride and then heating can also be used, or a combination of gas activation and chemical activation can be performed. Furthermore, washing is performed sequentially.

[0031] In this embodiment, solid-state 19 F-NMR measurements showed that the source of [agent] was observed in the range of -100 to -120 ppm. 19 There are no particular limitations on the method for producing activated carbon with peak F. It can be produced by activating fluorinated resin (activated carbon raw material), or by adding fluorine compounds to the matrix activated carbon obtained after activating the activated carbon raw material and allowing it to be adsorbed, thereby producing activated carbon by reacting the matrix activated carbon with the fluorine compounds.

[0032] In this embodiment, examples of fluorinated resins that can be used include polytetrafluoroethylene, perfluoroalkoxyalkane, ethylene-tetrafluoroethylene copolymer, perfluoroethylene-propylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymer.

[0033] In a preferred embodiment, activated carbon with attached fluorine compounds is prepared by adding fluorine compounds to a matrix activated carbon obtained by activating activated carbon raw materials and allowing it to be adsorbed. The activated carbon is then manufactured by reacting the matrix activated carbon with the fluorine compounds. The method for reacting the matrix activated carbon with the fluorine compounds is not particularly limited, and examples include: replacing the hydrogen in the matrix activated carbon with a metal before reacting with the fluorine compounds; heating the matrix activated carbon together and using the free radicals generated by the heat to fluorinate it; and directly reacting it with hydrogen fluoride, etc. Considering the versatility of the method, heating the fluorine compounds together with the matrix activated carbon is preferred.

[0034] The fluorine compounds adsorbed onto the activated carbon substrate are not particularly limited, but can include: inorganic fluorides such as sodium fluoride, potassium fluoride, lithium fluoride, calcium fluoride, magnesium fluoride, iron fluoride, copper fluoride, and nickel fluoride; and perfluorobutane, perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, perfluorononane, perfluorodecane, perfluoroundecane, perfluorododecane, perfluorotridecane, perfluorotetradecane, perfluorobutyric acid, perfluorovaleric acid, perfluorohexanoic acid, and perfluoroheptanoic acid. Perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluorobutane sulfonate, perfluoropentane sulfonate, perfluorohexane sulfonate, perfluoroheptane sulfonate, perfluorooctane sulfonate, perfluorononane sulfonate, perfluorodecane sulfonate, 1H,1H,2H,2H-perfluorohexane sulfonic acid, 1H,1H,2H,2H-perfluorooctane sulfonic acid, 1H,1H,2H,2H-perfluorooctane sulfonic acid, 1H,1H,2H,2H H-perfluorodecanesulfonic acid, perfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide, N-ethylperfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide acetic acid, N-ethylperfluorooctanesulfonamide acetic acid, N-methylperfluorooctanesulfonamide ethanol, N-ethylperfluorooctanesulfonamide ethanol; hexafluoropropylene oxide dimer acid, 4,8-dioxa-3H-perfluorononanoic acid, perfluoro-3-methoxypropionic acid, perfluoro-4-methoxy Compounds of butyric acid, perfluoro-3,6-dioxaheptanoic acid; 9-chlorohexadecylfluoro-3-oxanonane-1-sulfonic acid, 11-chloroeicofluoro-3-oxaundecan-1-sulfonic acid, perfluoro(2-ethoxyethane)sulfonic acid; 3-perfluoropropylpropionic acid, 2H,2H,3H,3H-perfluorooctanoic acid, 3-perfluoroheptylpropionic acid, bis(1H,1H,2H,2H-perfluorodecyl)phosphate, and their salts and derivatives. These can be used alone or in combination.

[0035] In addition, fluorine-containing high molecular weight substances can also be used. There are no particular limitations on the high molecular weight substances used; polytetrafluoroethylene, perfluoroalkoxyalkanes, ethylene-tetrafluoroethylene copolymers, perfluoroethylene-propylene copolymers, polyvinylidene fluoride, polychlorotrifluoroethylene, and ethylene-chlorotrifluoroethylene copolymers, etc., can be used. These can be used alone or in combination.

[0036] The amount of fluorine compound added to the matrix activated carbon is not particularly limited, but since the amount of fluorination varies depending on the amount of fluorine compound added, it is preferable to add a slightly higher amount to achieve more efficient fluorination. On the other hand, if too much is added, the excess portion will not be used for fluorination and will volatilize, posing a risk of highly reactive fluorine leaking out of the system, which is therefore undesirable. Therefore, the amount added to the activated carbon relative to 100% by weight of the matrix activated carbon used is preferably in the range of 0.01 ppm to 100% by weight, more preferably in the range of 0.1 ppm to 10% by weight, and even more preferably in the range of 0.2 ppm to 8% by weight.

[0037] In the manufacturing method of this embodiment, the fluorination conditions are not particularly limited. As long as the conditions allow for the decomposition of the fluorine-containing compound added to the activated carbon to generate fluoride anions and fluoride free radicals, thermal decomposition methods, free radical decomposition methods, etc., can be used. That is, methods such as heating the activated carbon and the fluorine-containing compound together to the decomposition temperature of the fluorine-containing compound, irradiating with ultraviolet light, electron beams, etc., are preferred. Considering that no special equipment is used, heat treatment is preferred.

[0038] In this embodiment, when heat treatment is performed, as described above, it is preferable to perform the heat treatment at a temperature above the decomposition temperature of the fluorine-containing compound. The heating temperature is preferably 200–2000°C, more preferably 300–1800°C, and even more preferably 400–1500°C. If the temperature exceeds 2000°C, the generated reactive fluorine compound may be difficult to react with the activated carbon.

[0039] In this embodiment, it is preferable to perform the heat treatment without burning or consuming the carbon. That is, it is preferable to perform the heat treatment in the absence of oxygen. "In the absence of oxygen" is intended to mean an atmosphere in which carbon is not oxidized by oxygen and is not burned or consumed. Therefore, "in the absence of oxygen" in this specification can refer to an environment replaced by an inert gas such as nitrogen, or an environment in which the decomposition products during heating react with oxygen to form a substantially oxygen-free state.

[0040] The reaction time for the heat treatment in this embodiment is not particularly limited, as long as fluorination can be carried out. For example, it can be carried out in the range of 1 to 720 minutes, more preferably in the range of 2 to 360 minutes, and even more preferably in the range of 5 to 180 minutes.

[0041] In this embodiment, the activated carbon that has undergone the heat treatment can be cooled to an inert temperature, typically below 200°C, before being removed.

[0042] In addition to the aforementioned processes, it is known that reducing the surface oxide concentration is also effective in further improving the hydrophobicity of activated carbon. As a method for reducing surface oxides on activated carbon, known methods such as heat treatment under an inert gas atmosphere can be used, thereby reducing acidic functional groups such as phenolic hydroxyl groups and carboxyl groups on the activated carbon surface.

[0043] The fluorinated activated carbon obtained as described above has a BET specific surface area of ​​500 m². 2 / g or more, and in solid state 19 In F-NMR measurements, ions originating from [source] were observed in the range of -100 to -120 ppm. 19 Activated carbon with a peak of F can effectively remove fluorine-containing organic compounds.

[0044] Furthermore, in the manufacturing method of this embodiment, used activated carbon, i.e., activated carbon after being used to remove perfluoroalkyl compounds and / or polyfluoroalkyl compounds, may also be used as activated carbon raw material. In this case, the used activated carbon may be ordinary activated carbon (activated carbon that has not yet adsorbed fluorine-containing compounds after activation) used to remove perfluoroalkyl compounds and / or polyfluoroalkyl compounds.

[0045] In other words, unfluorinated activated carbon is first used to remove perfluoroalkyl compounds and / or polyfluoroalkyl compounds, thereby obtaining activated carbon adsorbed with perfluoroalkyl compounds and / or polyfluoroalkyl compounds. By subjecting the used activated carbon to the aforementioned heat treatment, fluorine-bonded activated carbon can be obtained. Further heat treatment of the activated carbon after removal yields activated carbon with stronger hydrophobicity, and it has the advantage of more easily adsorbing perfluoroalkyl compounds and / or polyfluoroalkyl compounds by utilizing the fluorine introduced onto the activated carbon (fluorine bonded to the activated carbon).

[0046] (Adsorption filter) This embodiment includes an adsorption filter comprising activated carbon as described above. The adsorption filter of this embodiment is not particularly limited as long as it contains the activated carbon described above; for example, it may include the activated carbon and a fibrous binder.

[0047] As for the fibrous binder used in the adsorption filter of this embodiment, there are no particular limitations as long as it can be shaped to wrap around the activated carbon, and both synthetic and natural products can be widely used. Examples of such binders include: acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, cellulose fibers, nylon fibers, aramid fibers, pulp, etc. The fiber length of the fibrous binder is preferably 4 mm or less.

[0048] These fibrous binders can be used in combination of two or more. Polyacrylonitrile fibers or cellulose fibers are particularly preferred as binders. This further increases the density and strength of the molded body and prevents performance degradation.

[0049] In this embodiment, the water permeability of the fibrous polymer binder, expressed as a CSF value, is approximately 10 to 150 mL. More preferably, it is approximately 20 to 110 mL. In this embodiment, the CSF value is determined based on the freeness method of the Canadian Standard JIS P8121 (2012) "Test Method for Filterability of Pulp". Alternatively, the CSF value can be adjusted, for example, by fibrillating the binder.

[0050] Furthermore, as long as the effect of the present invention is not inhibited, the adsorption filter of the embodiment may also contain functional components other than those described above. For example, various adsorption materials containing silver ions and / or silver compounds to impart antibacterial properties, silica for removing metals such as lead and copper, zeolites such as titanium silicates, shaped diatomaceous earth, etc., may be added in any amount. In this case, 0.1 to 30 parts by weight are usually added relative to the entire adsorption filter.

[0051] Regarding the mixing ratio of the components in the adsorption filter of this embodiment, from the perspective of adsorption effect and formability, it is preferable that the fibrous binder is set to about 3 to 8 parts by mass relative to 100 parts by mass of the activated carbon or the mixture of the activated carbon and the functional components. If the amount of fibrous binder is less than 3 parts by mass, there is a risk that sufficient strength may not be obtained, making it impossible to form a molded article. In addition, if the amount of fibrous binder exceeds 8 parts by mass, there is a risk that the adsorption performance may decrease. More preferably, it is desirable to use 3.5 to 6 parts by mass of fibrous binder.

[0052] The adsorption filter of this embodiment can be a cylindrical filter, which further contains a central core in addition to the activated carbon and the fibrous binder. By making it cylindrical, there are advantages such as reduced water flow resistance, and when used as a filter cartridge by filling the housing as described later, the filter cartridge can be easily installed into the water purifier and replaced.

[0053] The core that can be used in this embodiment is not particularly limited as long as it can be inserted into the hollow part of the cylindrical filter to enhance the cylindrical filter. Preferred examples include, for instance, a triangular pipe, a netron pipe, or a ceramic filter. Alternatively, non-woven fabric or the like can be wrapped around the outer periphery of the core.

[0054] (Applications of adsorption filters, etc.) The adsorption filter of this embodiment can be used, for example, as a filter for a water purifier, a simple water purifier, or an air cleaning filter. When used as a filter for a water purifier, the adsorption filter of this embodiment can be shaped, dried, and then cut into the desired size and shape. Furthermore, a cover can be installed on the front end or a non-woven fabric can be installed on the surface, as needed.

[0055] The adsorption filter of this embodiment can be filled into the housing and used as a filter element for water purification. The filter element is installed in the water purifier for water circulation, and the water circulation method can be a full filtration method that filters the total amount of raw water or a circulating filtration method. Therefore, this embodiment also includes a water purifier using the adsorption filter described above.

[0056] In this embodiment, the filter element installed in the water purifier can be used simply by filling the housing with a water purifier filter, or it can be further combined with known non-woven filters, various adsorbent materials, mineral additives, ceramic filter materials, etc.

[0057] This specification discloses various techniques as described above, and its main techniques are summarized below.

[0058] That is, the first technical solution of the present invention relates to an activated carbon with a BET specific surface area of ​​500 m². 2 / g or more, and in solid state 19 In F-NMR measurements, ions originating from [source] were observed in the range of -100 to -120 ppm. 19 The peak of F.

[0059] Furthermore, the activated carbon involved in the second technical solution of the present invention is the activated carbon of the first technical solution, in the solid state 19 In F-NMR measurements, originating from 19 The peak of F originates from fluorine bonded to activated carbon.

[0060] The activated carbon involved in the third technical solution of the present invention has a fluorine content of 0.0001% by weight or more relative to 100% by weight of the activated carbon in the first or second technical solution.

[0061] The activated carbon involved in the fourth technical solution of the present invention is the activated carbon of any one of the first to third technical solutions, wherein the activated carbon is in powder, granular or block form.

[0062] The activated carbon involved in the fifth technical solution of the present invention is the activated carbon of any one of the first to fourth technical solutions for removing perfluoroalkyl compounds and polyfluoroalkyl compounds.

[0063] The sixth technical solution of the present invention relates to an adsorption filter, which includes activated carbon of any one of the first to fifth technical solutions.

[0064] The seventh technical solution of the present invention relates to a water purifier, which includes: the adsorption filter of the sixth technical solution.

[0065] The eighth technical solution of the present invention relates to a manufacturing method, which is a method for manufacturing activated carbon according to any one of the first to fifth technical solutions, comprising: activating activated carbon raw material; adsorbing a fluorine-containing compound onto the activated carbon raw material after activation; and heat-treating the activated carbon with the fluorine-containing compound attached at a temperature above the decomposition start temperature of the fluorine-containing compound. Example

[0066] The present invention will be further described in detail below through embodiments; however, the present invention is not limited to any of the embodiments.

[0067] First, the test methods for evaluating various physical properties in this embodiment will be explained.

[0068] [BET Specific Surface Area Measurement] The specific surface area was determined by the BET method, which uses a nitrogen adsorption capacity measuring device "BELSORP-MAX" manufactured by Microtrac BEL, to measure the nitrogen adsorption isotherm of the sample.

[0069] Solid State 19 [F-NMR determination] The following apparatus was used to measure solid-state... 19 F-NMR.

[0070] Equipment: JEOL Ltd.'s ECZ-500R nuclear magnetic resonance imaging (MRI) device. condition: The resonant frequency is 19F470MHz, and the probe is 3.2mm. The measurement mode was MAS (relaxation delay = 10 seconds). The speed is 14kHz The measurement temperature was room temperature. BF is 20Hz [Fluoride content] The fluorine content contained in activated carbon was calculated using automated combustion ion chromatography.

[0071] (Combustion device) • Apparatus: Automatic sample combustion apparatus "AQF-2100H" manufactured by Mitsubishi Chemical Analysis Technology Co., Ltd. • Combustion temperature: 1000℃ • Absorbent: Ion-exchanged water (Ion chromatography) • Apparatus: Thermo Fisher Scientific ICS-2100 ion chromatograph • Separation column: IonPac AS20 manufactured by Thermo Fisher Scientific • Eluent: KOH aqueous solution • Column temperature: 35℃ [Using activated carbon adsorption materials] The activated carbon raw material (activated carbon that forms the matrix) used in the following examples (manufacturing examples) is as follows.

[0072] Granular activated carbon: "F400" manufactured by Calgon Carbon (specific surface area: 1200 m²) 2 g) • Granular activated carbon: "PGW" manufactured by Kuraray Co., Ltd. (specific surface area: 1400 m²) 2 / g) <Example 1> In a 500 ml round-bottom flask, 200 ml of methanol, 2 g of perfluorooctanoic acid (PFOA), and 100 g of activated carbon "F400" manufactured by Calgon Carbon were added and stirred for 1 hour. Then, methanol was removed by distillation through three cycles of heating at 60 °C and 14 Torr, each lasting 5 minutes. The resulting activated carbon, adsorbed with 2% wt% PFOA, was further dried under vacuum at 80 °C for 2 hours to prepare PFOA-adsorbing activated carbon.

[0073] 20g of the obtained activated carbon was placed in a crucible and calcined in a quartz tubular furnace under a nitrogen flow (1L / min) at a rate of 10°C / min, reaching 900°C. The carbon was then heat-treated at 900°C for 1 hour and subsequently cooled naturally to room temperature. The resulting fluorinated activated carbon weighed 19.6g and had a specific surface area of ​​1210 m². 2 / g.

[0074] Regarding the obtained activated carbon, the above method was used to determine its properties. 19 F-NMR confirmed the presence of a peak at the specified chemical shift. 19 The results of F-NMR are shown in Figure 1Furthermore, the fluorine content of the activated carbon, determined according to the above method, was 0.07% by weight.

[0075] <Example 2> Except that "PGW" manufactured by Kuraray Co., Ltd. was used instead of "F400" as a raw material, the experiment was conducted in the same manner as in Example 1, and fluorinated activated carbon was obtained. The obtained activated carbon was measured according to the method described above. 19 F-NMR confirmed the presence of a peak at the specified chemical shift. 19 The results of F-NMR are shown in Figure 1 Furthermore, the activated carbon, determined according to the above method, has a fluorine content of 0.002% by weight and a specific surface area of ​​1380 m². 2 / g.

[0076] <Example 3> The calcination temperature in Example 1 was set to 700°C, and the calcination time was set to 3 hours, in the same manner as in Example 1. The specific surface area was 1200 m². 2 / g.

[0077] The obtained activated carbon was tested according to the above method. 19 18F-NMR confirmed the presence of peaks at the specified chemical shifts (between -100 and -120 ppm). Furthermore, the fluorine content of the activated carbon, determined according to the above method, was 0.11% by weight.

[0078] <Comparative Example 1> The unfluorinated "F400" was used.

[0079] <Comparative Example 2> Unfluorinated "PGW" was used.

[0080] In Comparative Examples 1 and 2, regardless of the method 19 F-NMR analysis and combustion ion chromatography both failed to detect fluorine. Figure 1 Comparative Example 1 and a reference example, which is simply Comparative Example 1 with the addition of perfluorooctanoic acid (PFOA), are shown. 19 F-NMR measurement results. Only when PFOA was added to Comparative Example 1 was no PFOA observed at the designated location in this embodiment. 19 Fluorine peak in F-NMR.

[0081] <Evaluation Methods> The removal efficiency of perfluorooctanoic acid (PFOA) was evaluated using the activated carbons of Examples 1-3 and Comparative Examples 1-2. Five columns were prepared using only the activated carbons of Examples 1-3 and Comparative Examples 1-2, according to ASTM D 6586. The tests were conducted using the Rapid Small Scale Column Test (RSSCT) prepared as described above, and according to the "Methodology" in EPA Method 537 Version 1.1 for determining the adsorption of pollutants into granular activated carbon in an aqueous system. Water was passed through the column, and the effluent PFOA concentration was measured at specified intervals to evaluate the removal capacity of the compound. To normalize the bed size, the results were expressed as "bed volume," obtained by dividing the volume of water passing through the activated carbon bed by the volume of the bed itself. Figure 2 The results of Examples 1 and 3 and Comparative Example 1 are shown in the figure. Figure 3 The results of Example 2 and Comparative Example 2 are shown in the figure.

[0082] (Inspection) according to Figure 2 and Figure 3 The results clearly show that the fluorinated activated carbon of the examples has a lower concentration of perfluorooctanoic acid (PFOA) at the outlet compared to the untreated activated carbon of the comparative examples, and the removal capacity of the compound is excellent. Furthermore, it is also evident that the activated carbon of the examples can maintain its excellent removal capacity for a longer period compared to the activated carbon of the comparative examples.

[0083] This application is based on Japanese Patent Application No. 2023-193657, filed on November 14, 2023, the contents of which are incorporated in the invention of this application.

[0084] To illustrate the invention, the invention has been appropriately and sufficiently described above with reference to specific examples and other embodiments. However, it should be understood that modifications and / or improvements to the described embodiments can be readily made by those skilled in the art. Therefore, any modified or improved embodiments implemented by those skilled in the art that do not depart from the scope of protection of the claims set forth in the claims are to be interpreted as being included within the scope of protection of those claims.

[0085] Industrial availability This invention has broad industrial applicability in the fields of activated carbon and its manufacturing methods, as well as adsorption filters and water purification using activated carbon.

Claims

1. An activated carbon, characterized in that, The activated carbon has a BET specific surface area of ​​500 m². 2 / g or more, and, In solid state 19 In F-NMR measurements, ions originating from [source] were observed in the range of -100 to -120 ppm. 19 The peak of F.

2. The activated carbon according to claim 1, characterized in that, In the solid 19 In F-NMR measurements, originating from 19 The peak of F originates from fluorine bonded to activated carbon.

3. The activated carbon according to claim 1, characterized in that, The fluorine content is above 0.0001% by weight relative to 100% by weight of activated carbon.

4. The activated carbon according to claim 1, characterized in that, The activated carbon is in powder, granular, or block form.

5. The activated carbon according to claim 1, characterized in that, The activated carbon is used to remove perfluoroalkyl and polyfluoroalkyl compounds.

6. An adsorption filter, characterized in that... include: The activated carbon according to any one of claims 1 to 5.

7. A water purifier, characterized in that, Use the adsorption filter as described in claim 6.

8. A method for manufacturing activated carbon, characterized in that, The method for manufacturing activated carbon according to any one of claims 1 to 5 comprises: Activation treatment is performed on the activated carbon raw material; Fluorine-containing compounds are adsorbed onto the activated carbon raw material after activation treatment; and... Activated carbon coated with fluorine-containing compounds is heat-treated at a temperature above the decomposition initiation temperature of the fluorine-containing compounds.

Images