Method for removing organofluorine compounds and apparatus for removing organofluorine compounds

Abstract

This invention provides a method for removing organofluorine compounds contained in the gas phase, such as in the atmosphere or factory exhaust gases. [Solution] A method for removing organofluorine compounds from a gas to be treated containing organofluorine compounds using one or more gas adsorption filters, The gas to be treated contains PFAS as the organofluorine compound, The gas adsorption filter contains an ion exchanger. A method for removing organofluorine compounds, comprising the step of contacting the gas to be treated with the ion exchanger to adsorb and remove the PFAS.

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for removing organic fluorine compounds contained in a gas phase, such as air and factory exhaust gas.

Background Art

[0002] Per- and polyfluoroalkyl substances (hereinafter, "PFAS") are fluorine-substituted aliphatic compounds having high thermal stability, high chemical stability, and high surface modification activity. PFAS are widely used in various industrial and chemical applications such as surface treatment agents, packaging materials, and liquid fire extinguishing agents by taking advantage of the above characteristics.

[0003] Some of PFAS are very stable chemical substances and are difficult to decompose under natural conditions after being released into the environment. Therefore, in recent years, PFAS have been recognized as persistent organic pollutants (POPs), and perfluorooctane sulfonic acid (PFOS) (IUPAC name: 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfonic acid) has been regulated in the manufacture and use in the Stockholm Convention on Persistent Organic Pollutants (POPs Convention) since 2010. There are also perfluorooctanoic acid (PFOA) (IUPAC name: 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoic acid), etc., including short-chain ones with 1 to 6 carbon atoms and long-chain ones with 12 or more carbon atoms.

[0004] In recent years, the presence of PFAS in groundwater and environmental water has been confirmed and regulations have been strengthened, and various methods have been proposed as methods for removing PFAS in treated water such as environmental water. On the other hand, PFAS can be released into the atmosphere and gaseous phases such as factory exhaust gases, similar to environmental water, but currently, no specific measures have been taken to address PFAS in the gaseous phase. Activated carbon adsorbents have been conventionally used as a method for removing PFAS from the gaseous phase. For example, Patent Document 1 discloses an activated carbon adsorbent for adsorbing PFAS from the atmosphere, comprising an activated carbon adsorbent having a specific BET specific surface area and pore size distribution. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-024455 [Overview of the project] [Problems that the invention aims to solve]

[0006] It is said that in the atmosphere and gaseous phases such as factory exhaust gases, in addition to the organofluorine compounds with 6 or more carbon atoms that were investigated, short-chain PFAS with fewer than 4 carbon atoms are also present, and it has been pointed out that methods using activated carbon adsorbents do not have sufficient capture capacity, especially for short-chain PFAS.

[0007] In systems where these substances exist in the atmosphere or in gaseous environments such as factory exhaust, no concrete countermeasures have been taken to date. Under these circumstances, the object of the present invention is to provide a method and apparatus for removing organofluorine compounds suitable for removing PFAS contained in the gas phase, such as in the atmosphere or factory exhaust gas. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventors of this invention have found that the following invention is suitable for the above purpose, leading to the present invention.

[0009] In other words, the present invention relates to the following invention. <1> A method for removing organofluorine compounds from a gas to be treated that contains organofluorine compounds using one or more gas adsorption filters, The gas to be treated contains PFAS as the organofluorine compound, The gas adsorption filter contains an ion exchanger. A method for removing organofluorine compounds, comprising the step of contacting the gas to be treated with the ion exchanger to adsorb and remove the PFAS. <2> The ion exchanger includes an anion exchanger having an amine group. <1> A method for removing organofluorine compounds as described above. <3> The claim that the ion exchanger is an ion exchange resin-supported filter and / or a graft polymerization ion exchange filter. <1> or <2> A method for removing organofluorine compounds as described above. <4> The PFAS is perfluorooctanoic acid (PFOA) and / or perfluorooctanesulfonic acid (PFOS). <1> from <3> A method for removing organofluorine compounds as described in any of the following. <5> The process includes, before bringing the gas to be treated into contact with the ion exchanger, a step of bringing the gas to be treated into contact with an adsorbent different from the ion exchanger contained in the gas adsorption filter. <1> from <4> A method for removing organofluorine compounds as described in any of the following. <6> The adsorbent is one or more selected from particulate activated carbon, powdered activated carbon, and activated carbon filter. <5> A method for removing organofluorine compounds as described above.

[0010] <1a> An apparatus for removing an organofluorine compound from a gas to be treated that contains an organofluorine compound, wherein the gas to be treated includes PFAS as the organofluorine compound, and the apparatus for removing the organofluorine compound comprises one or more gas adsorption filters, at least one of the gas adsorption filters being a gas adsorption filter containing an ion exchanger, and the apparatus for removing the organofluorine compound adsorbs the PFAS by bringing the gas to be treated into contact with the gas adsorption filter. <2a> The apparatus for removing organofluorine compounds according to <1a>, wherein an adsorbent different from the ion exchanger is placed upstream of the gas adsorption filter containing the ion exchanger. <3a> The apparatus for removing organofluorine compounds according to <2a>, wherein the adsorbent is one or more selected from particulate activated carbon, powdered activated carbon, and activated carbon filter. [Effects of the Invention]

[0011] The present invention provides a method and apparatus for removing organofluorine compounds suitable for removing PFAS contained in the gas phase. [Brief explanation of the drawing]

[0012] [Figure 1] This is a conceptual diagram of the apparatus used in the method (1) for removing organofluorine compounds of the present invention. [Figure 2] This is a conceptual diagram of the apparatus used in the method (2) for removing organofluorine compounds of the present invention. [Modes for carrying out the invention]

[0013] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples, and can be modified and implemented as appropriate without departing from the spirit of the invention. In this specification, "~" is used to mean an expression that includes the numerical value or physical quantity before and after it. Also, in this specification, the expression "A and / or B" includes "A only," "B only," and "both A and B."

[0014] (Definition of terms) PFAS (Per- and Polyfluoroalkyl Substances) is a general term for "perfluoroalkyl compounds" and "polyfluoroalkyl compounds." Furthermore, "perfluoroalkyl compounds" are organic compounds in which the hydrogen atoms bonded to carbon are completely replaced by fluorine atoms. "Polyfluoroalkyl compounds," on the other hand, are organic compounds in which the hydrogen atoms bonded to carbon are partially replaced by fluorine atoms.

[0015] In this specification, when "PFAS" is described, it includes not only perfluoroalkyl compounds and polyfluoroalkyl compounds, but also those containing atoms other than carbon, such as ether oxygen atoms, between the carbon atoms of perfluoroalkyl compounds and polyfluoroalkyl compounds.

[0016] The present invention relates to a method for removing an organic fluorine compound from a gas to be treated containing the organic fluorine compound, using one or more gas adsorption filters. The gas to be treated contains PFAS as the organic fluorine compound, the gas adsorption filter contains an ion exchanger, and the method includes a step of bringing the gas to be treated into contact with the ion exchanger to adsorb and remove the PFAS (hereinafter referred to as "the method for removing an organic fluorine compound of the present invention").

[0017] The present invention also relates to an apparatus for removing an organic fluorine compound from a gas to be treated containing the organic fluorine compound. The gas to be treated contains PFAS as the organic fluorine compound, the apparatus for removing the organic fluorine compound includes one or more gas adsorption filters, at least one of the gas adsorption filters is a gas adsorption filter containing an ion exchanger, and the PFAS is adsorbed by bringing the gas to be treated into contact with the gas adsorption filter (hereinafter referred to as "the apparatus for removing an organic fluorine compound of the present invention").

[0018] In the present invention, by using a gas adsorption filter containing an ion exchanger having PFAS adsorption ability described later, PFAS in the gas to be treated can be selectively adsorbed and removed. In this specification, "removing PFAS" does not only mean completely removing PFAS from the gas to be treated, but also includes removing a part of PFAS from the gas to be treated.

[0019] The present invention may be implemented as a method for removing organofluorine compounds, or as an apparatus for removing organofluorine compounds, by adsorbing and removing PFAS from the gas to be treated as described above.

[0020] The method and apparatus for removing organofluorine compounds of the present invention will be described in more detail below.

[0021] (Gas to be treated) In this invention, the removal of organofluorine compounds is performed in the gas phase. The gas to be treated is the gas to be treated in this invention, and any gas containing an organofluorine compound including PFAS is subject to treatment in this invention.

[0022] The gas to be treated is not particularly limited, but examples include the following: (1) Exhaust gas from the chemical industry Exhaust gases from chemical reactions involving fluorinated compounds (e.g., polymer manufacturing, surfactant manufacturing), combustion exhaust gases generated during the manufacture of products and materials containing PFAS, and ventilation gases from exhaust systems (e.g., laboratories, manufacturing facilities, industrial facilities, etc.) when chemicals containing PFAS are used in buildings and facilities. (2) Exhaust gas from semiconductor manufacturing Exhaust gases containing PFAS (fluorine-based compounds) used in semiconductor manufacturing (etching, cleaning, etc.) (3) Vapors and aerosols generated when water-repellent and oil-repellent agents containing PFAS are applied, and volatile compounds generated from PFAS-containing chemicals. (4) PFAS-containing gases that volatilize from soil and groundwater in PFAS-contaminated areas. (5) Atmosphere other than (1)~(4)

[0023] (Organofluorine compounds) In the present invention, the organofluorine compound contained in the gas to be treated is an organic compound having a carbon (C)-fluorine (F) bond, and includes at least PFAS.

[0024] In this invention, PFAS present in the gas phase are the targets for removal, including gaseous PFAS (volatile PFAS) and particulate PFAS.

[0025] In the present invention, PFAS having polar groups are suitable targets for removal. Examples of polar groups include anionic functional groups such as hydroxyl groups, sulfonic acid groups (sulfo groups), and carboxylic acid groups (carboxyl groups), and cationic functional groups such as amine groups.

[0026] PFAS having a sulfonic acid group or a carboxylic acid group are particularly preferred targets, specifically including perfluoroalkyl sulfonic acid, polyfluoroalkyl sulfonic acid, perfluoroalkyl carboxylic acid, and polyfluoroalkyl carboxylic acid.

[0027] The carbon number of the PFAS targeted by this invention is not limited as long as it can be dispersed in the gas phase and removed by adsorption using the ion exchanger described later. Depending on the type and number of functional groups the PFAS has, PFAS with 1 to 21 carbon atoms are targeted for removal. In particular, perfluorooctanoic acid (PFOA) and / or perfluorooctanesulfonic acid (PFOS) are preferred targets for removal.

[0028] In the method for removing organofluorine compounds of the present invention, the content of PFAS in the gas to be treated is not particularly limited, but is typically 1 pg / m³. 3 ~1g / m 3 That is the case.

[0029] In the present invention, the gas to be treated may contain organofluorine compounds other than PFAS, as long as the adsorption and removal of PFAS is not significantly impaired. The organofluorine compounds other than PFAS may be in gaseous or particulate form. Examples include aromatic fluorine compounds such as fluorobenzene, and fluorine-based polymers such as polytetrafluoroethylene (PTFE).

[0030] In the present invention, the gas to be treated may contain organic compounds other than organofluorine compounds, as long as the adsorption removal of PFAS by the ion exchanger is not significantly impaired. Other organic compounds besides organofluorine compounds can be any compounds present in the gas phase, including volatile organic compounds and particulate organic compounds.

[0031] Organic compounds other than organofluorine compounds are not particularly limited, but examples include: aliphatic alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; alicyclic alcohols such as cyclopentanol, cyclohexanol, and cycloheptanol; ethers such as dimethyl ether, diethyl ether, ethyl methyl ether, and tetrahydrofuran; carboxylic acids or their acid anhydrides such as formic acid, acetic acid, propionic acid, butyric acid, and valeric acid; esters such as ethyl formate, ethyl acetate, and ethyl butyrate; amides such as acetamide and N,N-dimethylformamide; aldehydes such as formaldehyde, acetaldehyde, pentanal, and hexanal; ketones such as acetone and diethyl ketone; amines such as trimethylamine; phenols such as phenol and cresol; benzene, toluene, and the like.

[0032] If the gas to be treated contains organic compounds other than organofluorine compounds, it is preferable to remove these other organic compounds from the gas using other adsorbents (such as activated carbon) before it is subjected to the ion exchange.

[0033] (Gas adsorption filter containing ion exchanger) The gas adsorption filter according to the present invention includes an ion exchanger. The ion exchanger included in the gas adsorption filter (hereinafter referred to as "the ion exchanger of the present invention") can be any ion exchanger that has the ability to adsorb PFAS in the gas phase. The ion exchange material of the present invention is supported or bound to the substrate (filter substrate) of a gas adsorption filter. The ion exchange material of the present invention may be a granular or powdered ion exchange resin, or a graft polymer bound to the filter substrate as a graft side chain.

[0034] The PFAS adsorption capacity of the ion exchanger contained in the gas adsorption filter is determined by a combination of hydrophobic and electrical interactions between the ion exchanger and the PFAS. PFAS generally exhibits high hydrophobicity, depending on the length of its carbon chain and the type of functional groups it contains. Therefore, it interacts with the hydrophobic portion of the ion exchanger, promoting adsorption. Furthermore, if the PFAS has polar groups, adsorption is enhanced through electrical interactions with the ion exchanger, particularly via anion exchange. Thus, the synergistic effect of hydrophobic and electrical interactions between the ion exchanger and PFAS enables the effective removal of PFAS in the gas adsorption filter.

[0035] The ion exchanger of the present invention can be either a cation exchanger or an anion exchanger, as long as it has the adsorption capacity for PFAS and can be retained on the filter substrate, but it is typically an anion exchanger.

[0036] The functional group having the ability to adsorb PFAS is arbitrary as long as it achieves the objective of the present invention. As an anion exchanger (ion exchange resin or graft polymer) having the adsorption capacity for PFAS, an anion exchanger containing one or more selected from the group consisting of primary amine groups, secondary amine groups, tertiary amine groups, quaternary amine groups, polyamine groups, and bispicolylamine groups can be used. Among these, primary amine groups, secondary amine groups, tertiary amine groups, and quaternary amine groups are preferred, and tertiary amine groups and quaternary amine groups, which have excellent PFAS adsorption capacity, are particularly preferred.

[0037] The form of the gas adsorption filter of the present invention is not limited, but it is preferably an ion exchange resin-supported filter and / or a graft polymerization ion exchange filter.

[0038] (Ion exchange resin supported filter) An ion exchange resin-supported filter is a gas adsorption filter having a structure in which an ion exchange resin having the ability to adsorb granular or powdered PFAS is supported on a filter substrate.

[0039] The filter substrate is not particularly limited as long as it can support the ion exchange resin and allows gas flow after support. Woven or nonwoven fabrics with good adhesion of the ion exchange resin are used. The fibers of the nonwoven fabric may be organic or inorganic. Examples of organic fibers include synthetic fibers such as polypropylene fibers and polyester fibers, natural fibers such as cotton and linen, and regenerated fibers such as rayon. Examples of inorganic fibers include glass fibers. As the filter substrate, a nonwoven fabric of organic fibers is preferred because it has a simple structure and is easy to manufacture, and the fiber diameter of the organic fibers is appropriately set in the range of, for example, 0.1 to 1000 μm. In addition to nonwoven fabric, the filter substrate may also be made of other materials, such as woven fabric, honeycomb structure, or wrinkled paper.

[0040] When the ion exchanger having PFAS adsorption capacity is an ion exchange resin, any polymer can be used as the base polymer as long as it does not impair the objective of the present invention. Examples include styrene-based crosslinked copolymers and (meth)acrylic-based crosslinked copolymers. In this invention, "(meth)acrylic" refers to a combination of "acrylic" and "methacrylic."

[0041] In the present invention, "styrene-based crosslinked copolymer" means a crosslinked copolymer obtained by copolymerizing a monovinyl aromatic monomer with a crosslinkable aromatic monomer, and "(meth)acrylic-based crosslinked copolymer" means a crosslinked copolymer obtained by copolymerizing a (meth)acrylic monomer with a crosslinkable (meth)acrylic monomer.

[0042] Examples of monovinyl aromatic monomers include alkyl-substituted styrenes such as styrene, methylstyrene, and ethylstyrene, and halogen-substituted styrenes such as bromostyrene. These may be used individually or in mixtures of two or more. Among the monovinyl aromatic monomers, styrene or monomers mainly composed of styrene are preferred.

[0043] Examples of crosslinkable aromatic monomers include divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, divinylbiphenyl, bis(vinylphenyl)methane, bis(vinylphenyl)ethane, bis(vinylphenyl)propane, and bis(vinylphenyl)butane. These may be used individually or in combination of two or more.

[0044] Examples of (meth)acrylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-(meth)acrylate, iso-butyl (meth)acrylate, t-butyl (meth)acrylate, n-butyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, butyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, etc. These may be used individually or in combination of two or more.

[0045] Examples of crosslinkable (meth)acrylic monomers include polymethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate. These may be used individually or in combination of two or more.

[0046] Furthermore, the structure of the resin portion of these anion exchangers may be gel-type or porous (MP type (macroporous type) or MR type (macroretic type)).

[0047] Examples of commercially available granular or powdered ion exchange resin-supported filters with PFAS adsorption capacity include Gigasorb R (Nitta Corporation), Gigawave HS (Nitta Corporation), and Iochemix (Nippon Muki Co., Ltd.).

[0048] (Graft polymerization ion exchange filter) A graft polymerization ion exchange filter is a gas adsorption filter manufactured by using graft polymerization to impart graft side chains and ion exchange groups (preferably the anion exchange groups) to a filter substrate. When the ion exchange material with PFAS adsorption capacity is a graft polymer, the ion exchange groups are located on the surface and readily come into contact with the PFAS in the gas being treated, which has the advantage of excellent adsorption reaction rate.

[0049] The filter substrate is not particularly limited as long as it can be to which graft side chains and ion exchange groups are attached and gas flow is possible after support. Woven or nonwoven fabrics with good adhesion of ion exchange resin are used. The fibers of the nonwoven fabric may be organic or inorganic fibers. Examples of organic fibers include synthetic fibers such as polyethylene fibers, polypropylene fibers, and polyester fibers, natural fibers such as cotton and linen, and regenerated fibers such as rayon. Examples of inorganic fibers include glass fibers. As the filter substrate, a nonwoven fabric of organic fibers is preferred because it has a simple structure and is easy to manufacture, and the fiber diameter of the organic fibers is appropriately set in the range of, for example, 0.1 to 1000 μm. In addition to nonwoven fabric, the filter substrate may also be made of other materials, such as woven fabric, honeycomb structure, or wrinkled paper.

[0050] Examples of graft polymerization ion exchange filters having anion exchange groups include the weakly basic anion exchange nonwoven fabric (EPIX-A) and the strongly basic anion exchange nonwoven fabric (EPIX-B) manufactured by ECE Corporation. As shown in the examples, the weakly basic anion exchange nonwoven fabric (EPIX-A) and the strongly basic anion exchange nonwoven fabric (EPIX-B) manufactured by ECE Corporation can selectively adsorb and remove PFOS and PFOA.

[0051] (Method and apparatus for removing organic fluorine compounds) The method of using the gas adsorption filter containing the ion exchanger of the present invention is sufficient as long as it can be brought into contact with the gas to be treated, which contains PFAS. For example, the gas adsorption filter may be used by installing a new, dedicated device for removing organofluorine compounds, or it may be used by installing it below other adsorbents in a treatment facility that already uses other adsorbents such as activated carbon.

[0052] Hereinafter, in the present invention, the method using only the gas adsorption filter containing the ion exchanger of the present invention will be referred to as "method for removing organofluorine compounds of the present invention (1)", the method using the gas adsorption filter containing the ion exchanger of the present invention and other adsorbents will be referred to as "method for removing organofluorine compounds of the present invention (2)", and the two will be collectively referred to as "method for removing organofluorine compounds of the present invention".

[0053] The present invention's method for removing organofluorine compounds (1) involves using a gas adsorption filter containing the ion exchanger of the present invention to remove PFAS from the gas to be treated. Since the method for removing organofluorine compounds (1) of the present invention uses only the gas adsorption filter containing the ion exchanger of the present invention, the process can be simplified.

[0054] Furthermore, the method for removing organofluorine compounds of the present invention may include any additional processing steps, as long as the objective of removing PFAS is achieved.

[0055] Figure 1 shows a conceptual diagram of the apparatus (organofluorine compound removal apparatus 1) used in the method (1) for removing organofluorine compounds of the present invention. The organofluorine compound removal apparatus 1 comprises a treatment apparatus 10 equipped with a gas adsorption filter containing the ion exchanger of the present invention. By supplying the gas to be treated, which contains PFAS, to the treatment apparatus 10, the gas to be treated is brought into contact with the ion exchanger to adsorb and remove the PFAS, and the treated gas from which the PFAS has been removed is discharged.

[0056] The processing device 10 has one or more gas adsorption filters installed inside (not shown). The number of gas adsorption filters should be sufficient to remove the target PFAS. When using multiple gas adsorption filters, the same type of gas adsorption filters may be used, or different types of gas adsorption filters may be used. For example, the processing apparatus 10 may use two types of gas adsorption filters with different PFAS adsorption capacities, with gas adsorption filter A, suitable for adsorbing particulate PFAS, placed in the front stage and gas adsorption filter B, suitable for adsorbing gaseous (volatile) PFAS, placed in the rear stage.

[0057] The treatment conditions in the method for removing organofluorine compounds (1) of the present invention are any conditions that can remove the target PFAS, and can be appropriately determined by considering the type and content (concentration) of PFAS in the gas phase, the type of ion exchanger contained in the gas adsorption filter and its PFAS adsorption capacity, the number of gas adsorption filters, etc. The flow rate LV of the gas to be treated is, for example, 1 to 1000 h -1 Preferably 1 to 100 hours -1 This can be done. The temperature of the gas to be treated can be, for example, 0 to 100°C.

[0058] Although Figure 1 shows one processing unit 10, two or more processing units 10 may be arranged in series or parallel (or a combination of series and parallel). For example, two types of gas adsorption filters with different PFAS adsorption capacities may be used in a series configuration, where a processing device equipped with gas adsorption filter A, which has PFAS adsorption capacity and a large adsorption capacity, is placed in the front stage, and a processing device equipped with gas adsorption filter B, which has even better PFAS adsorption capacity, is placed in the back stage.

[0059] The method for removing organofluorine compounds (2) of the present invention uses a gas adsorption filter containing the ion exchanger of the present invention and another adsorbent, and includes a step of contacting the gas to be treated with an adsorbent different from the gas adsorption filter (another adsorbent) before contacting the gas to be treated with the ion exchanger having PFAS adsorption capacity contained in the gas adsorption filter.

[0060] In the method for removing organofluorine compounds of the present invention, if the gas to be treated contains organic substances or inorganic components other than PFAS, these components may reduce the PFAS adsorption capacity of the ion exchanger contained in the gas adsorption filter of the present invention. Therefore, by placing another adsorbent in the preceding stage to remove organic substances other than PFAS, the removal of PFAS by the gas adsorption filter in the subsequent stage can be performed efficiently.

[0061] Figure 2 shows a conceptual diagram of the apparatus (organofluorine compound removal apparatus 1A) used in the method for removing organofluorine compounds (2) of the present invention. The organofluorine compound removal apparatus 1A comprises a processing apparatus 20 filled with other adsorbents in the front stage, and a processing apparatus 10 installed in the rear stage, which is equipped with a gas adsorption filter containing the ion exchanger of the present invention. The gas to be treated is supplied to the treatment device 20, where it comes into contact with other adsorbents to remove impurities (inorganic components and organic substances other than PFAS). Then, it is supplied to the treatment device 10, where it comes into contact with an ion exchanger containing a gas adsorption filter that has PFAS adsorption capacity, causing PFAS to be adsorbed. The treated gas, from which PFAS has been removed, is then discharged.

[0062] Although Figure 2 shows an example where one processing unit 10 and one processing unit 20 are arranged in series, the processing unit 20 only needs to be in front of the processing unit 10, and a combination of one or more processing units 20 and one or more processing units 10 is also acceptable.

[0063] The treatment conditions in the method for removing organofluorine compounds (2) of the present invention are any conditions that can remove the target PFAS, and can be appropriately determined by considering the type and content (concentration) of PFAS in the gas phase, the type of ion exchanger contained in the gas adsorption filter and its PFAS adsorption capacity, the number of gas adsorption filters, the type and amount of other adsorbents used, etc. The flow rate LV of the gas to be treated is, for example, 1 to 1000 h -1 Preferably 1 to 100 hours -1 This can be done. The temperature of the gas to be treated can be, for example, 0 to 100°C.

[0064] In the method for removing organofluorine compounds (2) of the present invention, other adsorbents are optional as long as they do not impair the objective of the present invention, and may be appropriately selected depending on impurities other than PFAS contained in the gas to be treated.

[0065] As other adsorbents, any carbon-based adsorbent, inorganic adsorbent, or organic adsorbent can be used, as long as it does not impair the objective of the present invention. One or more of the other adsorbents may be mixed in any proportion. Furthermore, the form of the other adsorbents is not limited; they may be in the form of particulate or powdered adsorbents filled into a filter, or they may be in the form of a gas filter with the other adsorbents fixed to the filter.

[0066] Activated carbon is a specific example of a carbon-based adsorbent. The shape (powder, granules, fibers, etc.) and size of activated carbon are arbitrary and can be appropriately selected according to the type and amount of gas to be treated. Activated carbon is suitable as an adsorbent because of its cost-effectiveness and excellent adsorption capacity for organic compounds other than PFAS. The carbon-based adsorbent may also be a filter, and a commercially available example of a carbon-based adsorbent filter is the activated carbon adsorbent GAIAC (manufactured by GL Sciences).

[0067] Examples of inorganic adsorbents include natural zeolites, synthetic zeolites, acid clay, molecular sieves, silica gel, silica alumina gel, and porous glass. The shape (powder, granules, fibers, etc.) and size of these inorganic adsorbents are arbitrary and can be appropriately selected according to the type and amount of gas to be treated.

[0068] Specifically, as the organic adsorbent, an ion exchanger that does not fall under the category of an ion exchanger having the above-mentioned PFAS adsorption capacity (another ion exchanger) can be used. The structure of the ion exchanger contained in the other ion exchanger may be gel type or porous type (MP type (macroporous type) or MR type (macroretic type)), and it is preferable to use styrene-based or acrylic-based ion exchangers.

[0069] The method for removing organofluorine compounds according to the present invention has been described above, but the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. Furthermore, matters not explicitly disclosed in the above embodiments do not deviate from what is normally practiced by those skilled in the art, and values ​​that can be easily anticipated by those skilled in the art can be adopted. [Examples]

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these. In addition, the "%" shown in the solutions of the examples refers to "weight percent" unless otherwise specified. Also, when the extraction solvent is a mixed solvent, the balance of water is omitted. For example, when "50% ethanol" is written, it means a mixed solvent of 50% by volume ethanol and 50% by volume water.

[0071] [Reference example 1] The adsorption characteristics of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in an aqueous system were confirmed using the test method described below.

[0072] The adsorption filters used are as follows: Filter A: Weakly basic anion exchange nonwoven fabric (EPIX-A, manufactured by E.C.E. Co., Ltd.) Filter B: Strongly basic anion exchange nonwoven fabric (EPIX-B, manufactured by E.C.E. Co., Ltd.) Filters A and B were each cut into 2-3 mm squares, weighed out to 1 mg, and used for the adsorption test.

[0073] The following batch tests were conducted. Pure water (1 L) was placed in a designated polyethylene container, and PFOS or PFOA dissolved in methanol was added to a concentration of 100 μg / L to prepare the stock solution for evaluation. A specified amount of filter A or filter B was placed in the prepared stock solution so as to be completely immersed, and the mixture was shaken using a shaker (iuchi, SHAKER SRR-2) at 100 rpm and 20°C for 48 hours. Next, the contents were removed from the container and solid-liquid separation was performed using silica filter paper (ADVANTEC, QR-100), and the resulting liquid was used as the treatment solution.

[0074] The raw and treated water were analyzed using LC-MS / MS (Waters Xevo-TQ) to measure the PFOS or PFOA concentration, and the removal rate of PFOS or PFOA was determined. The evaluation results are shown in Tables 1 and 2.

[0075] [Table 1]

[0076] [Table 2]

[0077] As shown in Tables 1 and 2, it was confirmed that filter A and filter B, respectively, could adsorb and remove PFOS and PFOA in the aqueous system.

[0078] [Example 1] The adsorption characteristics of adsorption filters for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in a gas phase system were confirmed using the test method described below.

[0079] The adsorption filters used are as follows: Filter A: Weakly basic anion exchange nonwoven fabric (EPIX-A, manufactured by E.C.E. Co., Ltd.) Filter B: Strongly basic anion exchange nonwoven fabric (EPIX-B, manufactured by E.C.E. Co., Ltd.) Filter C: Activated carbon filter (Activated carbon adsorbent GAIAC, manufactured by GL Sciences Co., Ltd.)

[0080] The following ventilation tests were conducted. Filters A, B, or C (activated carbon) with a diameter of φ47 mm (effective filter area: φ45 mm) were set in a designated vent pipe, and air from a designated location was passed through at a flow rate of approximately 2 L / min for 10 hours. Next, the filter was collected after aeration, and 30 mL of 5% NaCl / 70% methanol aqueous solution was placed in a centrifuge tube. The aeration-removed filter was then added, and the tube was shaken for 10 minutes to eluate PFOS and PFOA. The contents of the centrifuge tube were then collected and used as the sample solution. The sample solutions corresponding to filters A to C were analyzed using LC-MS / MS (Thermo Scientific TSQ Quantis Plus) to measure the concentrations of PFOS and PFOA, and the removal rates of PFOS and PFOA were determined. The evaluation results are shown in Tables 3-1 to 3-3.

[0081] [Table 3-1]

[0082] [Table 3-2]

[0083] [Table 3-3]

[0084] As shown in Tables 3-1 to 3-3, it was confirmed that in the gas phase system, filter A and filter B were able to effectively adsorb and remove PFOS and PFOA compared to filter C (activated carbon). [Industrial applicability]

[0085] According to the present invention, it is possible to effectively remove PFAS from the gas phase, such as from the atmosphere or factory exhaust gas. [Explanation of Symbols]

[0086] 1.1A Apparatus for removing organofluorine compounds 10 Processing Unit 20 Processing equipment (other adsorbents)

Claims

1. A method for removing organofluorine compounds from a gas to be treated that contains organofluorine compounds using one or more gas adsorption filters, The gas to be treated contains PFAS as the organofluorine compound, The gas adsorption filter contains an ion exchanger. A method for removing organofluorine compounds, comprising the step of bringing the gas to be treated into contact with the ion exchanger to adsorb and remove the PFAS.

2. The method for removing an organofluorine compound according to claim 1, wherein the ion exchanger includes an anion exchanger having an amine group.

3. The method for removing an organofluorine compound according to claim 1 or 2, wherein the ion exchanger is an ion exchange resin-supported filter and / or a graft polymerization ion exchange filter.

4. The method for removing an organofluorine compound according to claim 1, wherein the PFAS is perfluorooctanoic acid (PFOA) and / or perfluorooctanesulfonic acid (PFOS).

5. The method for removing an organofluorine compound according to claim 1, further comprising the step of contacting the gas to be treated with an adsorbent different from the ion exchanger contained in the gas adsorption filter, before the step of contacting the gas to be treated with the gas adsorption filter.

6. The method for removing an organofluorine compound according to claim 5, wherein the adsorbent is one or more selected from particulate activated carbon, powdered activated carbon, and activated carbon filter.

7. An apparatus for removing organofluorine compounds from a gas to be treated that contains organofluorine compounds, The gas to be treated includes PFAS as the organofluorine compound, The apparatus for removing the organofluorine compound comprises one or more gas adsorption filters, at least one of which is a gas adsorption filter containing an ion exchanger, and the apparatus for removing the organofluorine compound adsorbs the PFAS by bringing the gas to be treated into contact with the gas adsorption filter.

8. The apparatus for removing organofluorine compounds according to claim 7, wherein an adsorbent different from the ion exchanger is placed upstream of the gas adsorption filter containing the ion exchanger.

9. The apparatus for removing organic fluorine compounds according to claim 8, wherein the adsorbent is one or more selected from particulate activated carbon, powdered activated carbon, and activated carbon filter.

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