Adsorbent, adsorbent for removing organic fluorine compounds, adsorbent for permeable purification walls, and method for removing organic fluorine compounds

Abstract

To provide a novel adsorbent, an adsorbent for removing organofluorine compounds, an adsorbent for permeable purification walls, and a method for removing organofluorine compounds. [Solution] An adsorbent containing (A) activated carbon and (B) zeolite.

Description

[Technical Field]

[0001] The present invention relates to a novel adsorbent, an adsorbent for removing organofluorine compounds, an adsorbent for permeable purification walls, and a method for removing organofluorine compounds. [Background technology]

[0002] Groundwater contaminated with pollutants from factory wastewater, waste disposal sites, and illegally dumped materials flows downstream, spreading the pollutants to surrounding areas and causing adverse environmental impacts. One known method for purifying the contaminated groundwater in situ and preventing the spread of pollutants to the surrounding area is to install a permeable purification wall.

[0003] By installing a permeable purification wall downstream of contaminated groundwater, intersecting the direction of flow of the contaminated groundwater, contaminants contained in the contaminated groundwater can be removed as the contaminated groundwater passes through this permeable purification wall.

[0004] The adsorbents and purifying materials used in permeable remediation walls vary depending on the target pollutant. For example, in Patent Document 1, a mixture of iron powder and a mud-conditioning material mainly composed of natural guar gum is used as a purifying material to purify groundwater contaminated with organochlorine compounds.

[0005] Furthermore, Patent Document 2 discloses a method for purifying a permeable groundwater purification wall, in which a filler containing biomaterials is added in addition to a purification material to form a permeable groundwater purification wall. When contaminated groundwater flows through the permeable groundwater purification wall, organic compounds in the contaminated groundwater are adsorbed and removed by the purification material, such as activated carbon adsorbent, and the organic compounds are decomposed by microorganisms in the biomaterials, thereby purifying the contaminated groundwater.

[0006] In particular, organofluorine compounds are chemically stable and persistent, meaning they can remain in the environment for long periods and are easily soluble in groundwater. For this reason, there are growing concerns that organofluorine compounds may migrate through the environment, accumulate in plants and animals, and negatively impact ecosystems.

[0007] In April 2020, the "Water Quality Management Target Setting Items" established under the Water Supply Act were revised, and PFOS (perfluorooctanesulfonic acid) and PFOA (perfluorooctanoic acid), which are types of PFAS (an abbreviation for perfluoroalkyl compounds, polyfluoroalkyl compounds, and their salts), were newly added to the water quality management items. A provisional target value of 50 ng / L or less was set for the combined value of PFOS and PFOA in tap water. Furthermore, in November 2023, "PFHxS or its isomers or salts thereof" were designated as Class I Specified Chemical Substances under Article 2, Paragraph 2 of the Act on the Examination and Regulation of Manufacture, etc., of Chemical Substances. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2004-113854 [Patent Document 2] Japanese Patent Publication No. 2011-156454 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, in view of the impact of the above-mentioned organofluorine compounds on the environment, the present invention aims to provide a novel adsorbent, an adsorbent for removing organofluorine compounds, an adsorbent for permeable purification walls, and a method for removing organofluorine compounds. [Means for solving the problem]

[0010] As a result of intensive studies to solve the above problems, the present inventors have found that organic fluorine compound-containing contaminated water can be brought into contact with an adsorbent containing (B) zeolite and an adsorbent containing (A) activated carbon simultaneously or in this order, whereby the organic fluorine compound can be adsorbed and removed by the adsorbent, and have thus completed the present invention.

[0011] That is, the present invention relates to the following inventions. [1] An adsorbent containing (A) activated carbon and (B) zeolite. [2] The adsorbent according to [1], wherein the Si / Al molar ratio of the component (B) is 1 to 1000. [3] The adsorbent according to [1], characterized in that when the component (B) is 100% by mass, it contains 1.9 to 3.3% by mass of K2O and 2.4 to 4.7% by mass of Na2O. [4] The adsorbent according to any one of [1] to [3], which is an adsorbent for removing organic fluorine compounds. [5] The adsorbent according to any one of [1] to [3], which is an adsorbent for a permeable purification wall. [6] A method for removing an organic fluorine compound, comprising a step of bringing contaminated water contaminated with an organic fluorine compound into contact with an adsorbent containing (A) activated carbon and (B) zeolite. [7] A method for removing an organic fluorine compound, comprising a step of bringing contaminated water contaminated with an organic fluorine compound into contact with an adsorbent containing (B) zeolite and a step of bringing it into contact with an adsorbent containing (A) activated carbon.

Effect of the Invention

[0012] According to the present invention, it is possible to provide a novel adsorbent, an adsorbent for removing organic fluorine compounds, an adsorbent for a permeable purification wall, and a method for removing organic fluorine compounds.

Brief Description of the Drawings

[0013] [Figure 1]This graph shows the changes in the adsorption amounts (ng / g) of PFOS, PFOA, PFHxS, and PFHxA per unit volume of granular activated carbon when serial batch adsorption test 1, in which material A is added to simulated contaminated water 1 and shaken at 100 rpm for 10 minutes, is repeated 5 times. [Figure 2] This graph shows the changes in the amount of PFOS, PFOA, PFHxS, and PFHxA adsorbed per unit amount of zeolite (ng / g) when serial batch adsorption test 1, in which material B is added to simulated contaminated water 1 and shaken at 100 rpm for 10 minutes, is repeated 5 times. [Figure 3] This graph shows the changes in the adsorption amounts (ng / g) of PFOS, PFOA, PFHxS, and PFHxA per unit volume of granular activated carbon when serial batch adsorption test 1, in which material C is added to simulated contaminated water 1 and shaken at 100 rpm for 10 minutes, is repeated five times. [Figure 4] This graph shows the changes in the adsorption amounts (ng / g) of PFOS, PFOA, PFHxS, and PFHxA per unit volume of granular activated carbon when serial batch adsorption test 2, in which material A is added to simulated contaminated water 2 and shaken at 100 rpm for 10 minutes, is repeated 5 times. [Figure 5] This graph shows the changes in the amount of PFOS, PFOA, PFHxS, and PFHxA adsorbed per unit amount of zeolite (ng / g) when serial batch adsorption test 2, in which material B is added to simulated contaminated water 2 and shaken at 100 rpm for 10 minutes, is repeated 5 times. [Figure 6] This graph shows the changes in the adsorption amounts (ng / g) of PFOS, PFOA, PFHxS, and PFHxA per unit volume of granular activated carbon when serial batch adsorption test 2, in which material C is added to simulated contaminated water 2 and shaken at 100 rpm for 10 minutes, is repeated 5 times. [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

[0015] In this specification, "contamination" means that groundwater is contaminated by organic fluorine compounds, that is, that organic fluorine compounds are present in groundwater, etc.

[0016] [1. Adsorbent] The adsorbent according to this embodiment is characterized by containing (A) activated carbon and (B) zeolite.

[0017] [1-1. (A) Activated Carbon] The activated carbon according to this embodiment is not particularly limited, and any known or commonly used material may be used. The raw materials for the activated carbon are not particularly limited, and examples include wood (waste wood, thinned wood, sawdust), coal, tree bark, bamboo, bagasse, rice husks, coffee beans, peat, and fruit shells (coconut, palm).

[0018] The shape of the activated carbon is not particularly limited, and examples include granular activated carbon, powdered activated carbon, and fibrous activated carbon. While it depends on the interaction with component (B), it is preferable to use granular activated carbon, as it has a large specific surface area.

[0019] Although activated carbon pores are distributed with various pore sizes, among macropores (pores with a diameter of 50 nm or more), mesopores (pores with a diameter of 2 to 50 nm), and micropores (pores with a diameter of 2 nm or less), those in which micropores are well-developed after activation are preferable.

[0020] [1-2. (B) Zeolite] The zeolite according to this embodiment is not particularly limited, and any known and commonly used zeolite can be used. Zeolite is a general term for crystalline aluminosilicates, and the general formula for zeolite can be expressed as follows. (M(I), M(II) 1 / 2 ) m (Al m Si n O 2(m+n) )·xH2O [In the formula, M(I) is a monovalent cation (e.g., H + Li + kaNa+ , K + , Cs + , Rb + , NH4 + , etc.) represents, and M(II) represents a divalent cation (e.g., Ca 2+ , Mg 2+ , Ba 2+ , Sr 2+ , etc.), and m, n, and x each represent a real number.

[0021] The zeolite used in this embodiment may be either natural zeolite or synthetic zeolite. Also, the framework structure of the zeolite (the framework structure represented by a three-letter structure code defined by the International Zeolite Association) is not particularly limited, and examples include LTA, FER, MWW, MFI, MOR, CLP, LTL, FAU, BEA, etc. When represented by the name of the crystal structure of the zeolite, examples include zeolites such as type A, type X, type Y, type L, USY type, beta type, ZSM-5 type, etc.

[0022] The Si / Al molar ratio of the zeolite used in this embodiment is not particularly limited, and it may be a high-silica zeolite with a relatively large Si / Al molar ratio value (e.g., MOR, CLP, type Y, USY type, beta type, ZSM-5 type, etc.) or a low-silica zeolite with a relatively small Si / Al molar ratio value (e.g., a part of type A, a part of type X, etc.). As the zeolite used in this embodiment, the value of the Si / Al molar ratio is preferably 1 to 1000, more preferably 2 to 100, even more preferably 2.5 to 40, and even more preferably 3 to 30. In some cases, the value of the Si / Al molar ratio of the zeolite may be 3 to 20 or 3.5 to 15.

[0023] Furthermore, the zeolite used in this embodiment preferably contains natural zeolites such as analcime, chabasite, clinoptilolite, erionite, foujasite, or mordenite, which correspond to high-silica zeolites with a Si / Al molar ratio of 3 or more, from the viewpoint of ease of cation exchange of organofluorine compounds, more preferably contains natural zeolites such as clinoptilolite, erionite, or mordenite, and even more preferably contains natural zeolites such as clinoptilolite or mordenite. These zeolites may be included individually or in combination of two or more types.

[0024] The Si / Al molar ratio of component (B), which contains the above-mentioned clinoptilolite, mordenite, or a mixture thereof, is preferably 3 to 12, more preferably 3.2 to 10, even more preferably 3.5 to 8, even more preferably 3.7 to 7, and may optionally be 4 to 6.

[0025] Furthermore, as component (B) containing the above-mentioned clinoptilolite, mordenite, or a mixture thereof, the zeolite (M(I), M(II)) which is component (B) 1 / 2 ) m (Al m Si n O 2(m+n) When the total mass is taken as 100%, it is preferable that the zeolite contains 1.9 to 3.3 mass% of K2O and 2.4 to 4.7 mass% of Na2O, more preferably 2.0 to 3.1 mass% of K2O and 2.5 to 4.5 mass% of Na2O, and even more preferably 2.1 to 2.9 mass% of K2O and 2.6 to 4.3 mass% of Na2O. Surprisingly, the zeolite containing more K2O and Na2O is preferable to the zeolite containing more Na2O. + and K + Ca 2+ Mg 2+ Based on supplying the like.

[0026] [2. Adsorbent for removing organic fluorine compounds] The adsorbent according to this embodiment can be suitably used as an adsorbent for removing organofluorine compounds.

[0027] <Organofluorine compounds> In this embodiment, the organofluorine compound adsorbed by the adsorbent is not particularly limited and may be any compound in which some or all of the hydrogen in the hydrocarbon is replaced with fluorine and / or salts thereof.

[0028] Examples of the above-mentioned organofluorine compounds include: Perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, 4,8-dioxa-3H-perfluorononanoic acid, perfluoro-3-methoxypropanoic acid, perfluoro-4-methoxybutanoic acid, nonafluoro-3,6-dioxaheptanoic acid, 3-perfluoropropylpropanoic acid, 3-perfluoroheptylpropanoic acid, 2H,2H,3H,3H-perfluorooctanoic acid, and other per- or polyfluoroalkyl carboxylic acids; Perfluorobutanesulfonic acid, perfluoropentanesulfonic acid, perfluorohexanesulfonic acid (PFHxS), perfluoroheptanesulfonic acid, perfluorooctanesulfonic acid (PFOS), perfluorononanesulfonic acid, perfluorodecanesulfonic acid, perfluorododecanesulfonic acid, 1H,1H,2H,2H-perfluorohexanesulfonic acid, 1H,1H,2H,2H-perfluorooctanesulfonic acid, 1H,1H,2H,2H-perfluorodecanesulfonic acid, 9-chlorohexadecafluoro-3-oxanonanane-1-sulfonic acid, 11-chloroicosafluoro-3-oxaundecane-1-sulfonic acid, perfluoro(2-ethoxyethane)sulfonic acid, and other per- or polyfluoroalkyl sulfonic acids; Examples include perfluorooctanesulfonamide (PFOSA), N-methylperfluorooctanesulfonamide, N-ethylperfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide acetate, N-ethylperfluorooctanesulfonamide acetate, N-methylperfluorooctanesulfonamide ethanol, N-ethylperfluorooctanesulfonamide ethanol, and hexafluoropropylene oxide dimer acid. These organofluorine compounds may be present in one or more types in contaminated water, contaminated groundwater, or contaminated soil.

[0029] Of these organofluorine compounds, per- or polyfluoroalkyl carboxylic acid and per- or polyfluorosulfonic acid are preferred, and per- or polyfluorooctanoic acid, per- or polyfluorooctanesulfonic acid, per- or polyfluorohexanoic acid, per- or polyfluorohexanoic acid, per- or polyfluorohexanoic acid, and per- or polyfluorohexanesulfonic acid are more preferred, given that they are widely used in industrial and daily products, are abundant in soil, easily transfer to groundwater and public water bodies such as rivers and lakes, and are subject to regulations.

[0030] <(A) and (B) component content by mass> The adsorbent material according to this embodiment includes component (A) and component (B). In the adsorbent according to this embodiment, the mass ratio of component (A) to component (B) is not particularly limited and can be appropriately set depending on the type of component (A), the type of component (B), the type and content of organofluorine compounds in the contaminated water, etc. As for the mass ratio of component (A) to component (B), for example, it is preferable that component (A):component (B) is 1 to 10:1 to 10, more preferably 1 to 5:1 to 5, and even more preferably 1 to 3:1 to 3.

[0031] There is a difference in the range of pore sizes between component (A) and component (B), and by including both, a range can be provided from the perspective of physical adsorption or molecular sieving. Furthermore, although component (A), activated carbon, is a hydrophobic adsorbent, it is known that various surface functional groups containing oxygen atoms exist on the surface of activated carbon. For example, when the pH increases, acidic groups such as carboxyl groups and phenolic hydroxyl groups among the surface functional groups of activated carbon dissociate into anions, which hinders the adsorption of anionic compounds. In contrast, component (B), zeolite, has a certain degree of pH buffering function and cation exchange function. Furthermore, by creating an adsorbent containing both component (A) and component (B), sodium ions, potassium ions, etc. of per or polyfluoroalkyl carboxylic acid or per or polyfluoroalkyl sulfonic acid are adsorbed onto component (B), and Ca is adsorbed from component (B). 2+ Mg 2+ By supplying these components, it becomes possible to adsorb per- or polyfluoroalkyl carboxylic acids, or calcium salts, magnesium salts, etc. of per- or polyfluoroalkyl sulfonic acids, onto component (A). Based on the above mechanism, it is believed that by incorporating components (A) and (B) into the adsorbent, the capacity of the adsorbent to adsorb organic fluorine compounds is increased, thereby enabling the adsorbent to be used repeatedly.

[0032] [3. Permeable Adsorbent for Wall Purification] The adsorbent material according to this embodiment can also be suitably used as an adsorbent material for permeable purification walls.

[0033] A permeable purification wall can be installed in the downstream watershed of groundwater contaminated with organic fluorine compounds, so as to intersect with the direction of flow of the contaminated groundwater. In this way, as the contaminated groundwater passes through the permeable purification wall, the organic fluorine compounds are adsorbed onto the adsorbent material according to this embodiment in the purification wall, and thus can be removed.

[0034] The construction method for the permeable remediation wall is not particularly limited, and publicly known and conventional methods can be used. Generally, the construction method for the permeable remediation wall can be a method in which the adsorbent material according to this embodiment is filled into a hole or groove made in the ground by excavation such as trenching, or a method in which a casing pipe is driven in, the soil inside is replaced with the adsorbent material according to this embodiment, and then the casing pipe is withdrawn.

[0035] The adsorbent according to this embodiment contains components (A) and (B), which increases its capacity to adsorb organic fluorine compounds and allows for long-term use. Therefore, when the adsorbent according to this embodiment is used as an adsorbent for permeable purification walls, it enables continuous adsorption of organic fluorine compounds over a long period, making it suitable from the viewpoint of running costs and other factors.

[0036] [4. Method for removing organofluorine compounds] The method for removing organofluorine compounds according to this embodiment includes the step of bringing contaminated water contaminated with organofluorine compounds into contact with an adsorbent containing (A) activated carbon and (B) zeolite. Furthermore, the method for removing organofluorine compounds according to this embodiment may include the steps of (B) bringing contaminated water contaminated with organofluorine compounds into contact with an adsorbent containing zeolite, and (A) bringing the contaminated water into contact with an adsorbent containing activated carbon.

[0037] Contact is not particularly limited and includes, for example, bringing contaminated water containing an organofluorine compound into contact with a layer filled with an adsorbent containing (A) activated carbon and / or (B) zeolite, or bringing contaminated water containing an organofluorine compound into contact with an adsorbent containing (A) activated carbon and / or (B) zeolite by placing them together in the same container.

[0038] As described above, the method for removing organofluorine compounds according to this embodiment includes a step of contacting contaminated water contaminated with organofluorine compounds with an adsorbent containing (A) activated carbon and (B) zeolite. Therefore, the adsorption capacity of the adsorbent for organofluorine compounds is increased, and it can be suitably used as a method for removing organofluorine compounds.

[0039] Furthermore, in the method for removing organofluorine compounds according to this embodiment, the contaminated water contaminated with organofluorine compounds may be brought into contact with (B) an adsorbent containing zeolite, followed by a step of bringing it into contact with (A) an adsorbent containing activated carbon. As described above, there are differences in the range of pore sizes between (B) zeolite and (A) activated carbon, as well as differences in their physical and chemical adsorption properties. Furthermore, (B) zeolite can convert the cations of per- or perfluoroalkyl carboxylic acids or per- or polyfluoroalkyl sulfonic acids, making them easier to adsorb onto (A) activated carbon. For these reasons, the above process order allows for more favorable removal of organofluorine compounds. Furthermore, by following the above process order, it is possible to enjoy the advantage of reducing the frequency of replacing the more costly adsorbent containing (A) activated carbon by appropriately replacing the adsorbent containing (B) zeolite. [Examples]

[0040] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0041] [Test Example 1: Adsorption of organofluorine compounds by components (A) and (B) (Serial batch adsorption test 1)] <Preparation of simulated contaminated water 1> Tap water was mixed with PFOS, PFOA, PFHxS, and PFHxA (hereinafter collectively referred to as "PFAS"), all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., with a purity of 95% or higher, to prepare PFAS aqueous solutions at a concentration of 100 μg / L for each component. Next, 18.75 g of the above PFAS aqueous solution was added to 56.25 g of river water (turbidity of 2 degrees or less) to prepare simulated contaminated water 1, which was a four-fold dilution of the PFAS aqueous solution.

[0042] <Serial batch adsorption test 1> Materials A to C were added to the simulated contaminated water 1 described above, and the mixture was shaken at 100 rpm for 10 minutes. After that, solid-liquid separation was performed using a paper filter, and the materials were recovered. The recovered materials were then added to another simulated contaminated water 1, shaken at 100 rpm for 10 minutes, and then solid-liquid separation was performed using a paper filter. This process was repeated a total of five times. Material A: Granular activated carbon (manufactured by Futamura Chemical Co., Ltd.) 0.75g Material B: Zeolite (Itaya zeolite (Si / Al molar ratio = 4.2~5.7, K2O (2.1~2.9%), Na2O (2.7~4.3%), same below), manufactured by Zeiklite Co., Ltd.) 0.75g Material C: Granular activated carbon (manufactured by Futamura Chemical Co., Ltd.) 0.325g, Zeolite (Itaya zeolite, manufactured by Zeeklite Co., Ltd.) 0.325g

[0043] The concentrations of PFOS, PFOA, PFHxS, and PFHxA contained in the simulated contaminated water (repeated cycles 1-3 and 5) recovered during the solid-liquid separation described above were measured in accordance with Environmental Notification No. 18. The amount of PFOS, PFOA, PFHxS, and PFHxA adsorbed onto the materials (hereinafter also referred to as "PFAS adsorption amount") was then calculated. The results are shown in Figures 1-3.

[0044] Comparing the results in Figures 1 and 3, it can be seen that adding zeolite in addition to granular activated carbon to simulated contaminated water 1 increases the amount of PFAS adsorbed per unit of granular activated carbon. More specifically, when the amount of PFAS adsorbed after 1 and 3 repetitions when material C is added (Figure 3) is divided by the amount of PFAS adsorbed after 1 and 3 repetitions when material A is added (Figure 1) and compared, it can be seen that the amount of PFAS adsorbed per unit of granular activated carbon increases as follows. • Number of repetitions: 1 (PFOS adsorption amount 1.75 times, PFOA adsorption amount 1.67 times, PFHxS adsorption amount 1.59 times, PFHxA adsorption amount 1.47 times) • Number of repetitions: 3 (PFOS adsorption amount: 1.39 times, PFOA adsorption amount: 1.98 times, PFHxS adsorption amount: 1.73 times, PFHxA adsorption amount: 1.38 times)

[0045] The results in Figure 2 show that when only zeolite is added to simulated contaminated water 1, PFOS, PFOA, PFHxS, and PFHxA are hardly adsorbed by the zeolite.

[0046] The results in Figures 1-3 show that adding both granular activated carbon and zeolite to simulated contaminated water 1 increases the amount of PFAS adsorbed per unit volume of granular activated carbon, resulting in a synergistic effect. Furthermore, it is evident that not only does the amount of PFAS adsorbed increase, but the combination of granular activated carbon and zeolite maintains the PFAS adsorption capacity even after repeated use.

[0047] [Test Example 2: Adsorption of organofluorine compounds by components (A) and (B) (Serial batch adsorption test 2)] <Preparation of simulated contaminated water 2> Commercially available decomposed granite soil (from Kagawa Prefecture, manufactured by Kanea Co., Ltd.) was sieved to less than 2 mm, tap water was added, and then PFOS, PFOA, PFHxS, and PFHxA were added to prepare simulated contaminated water so that the concentration of each of these substances in the aqueous solution was 100 μg / L. Simulated contaminated water 2 (turbidity 9 degrees) was prepared by filtering out the decomposed granite soil from the above simulated contaminated water.

[0048] <Serial batch adsorption test 2> Similar to Test Example 1, materials A to C were added to simulated contaminated water 2, then shaken at 100 rpm for 10 minutes. After that, solid-liquid separation was performed using a paper filter, and the added materials were recovered. The recovered materials were then added again to another set of simulated contaminated water 2, and this process was repeated a total of five times.

[0049] The concentrations of PFOS, PFOA, PFHxS, and PFHxA contained in the simulated contaminated water (repeated cycles 1-3 and 5) recovered during the solid-liquid separation described above were measured in accordance with Environmental Notification No. 18, and the amount of PFAS adsorbed onto the materials was calculated. The results are shown in Figures 4-6.

[0050] Comparing the results in Figures 4 and 6, it can be seen that adding zeolite to granular activated carbon in addition to simulated contaminated water 2 increases the amount of PFAS adsorbed per unit volume of granular activated carbon (ng / g). More specifically, when comparing the amount of PFAS adsorbed after 1 and 3 repetitions when material C is added (Figure 6) by the amount of PFAS adsorbed after 1 and 3 repetitions when material A is added (Figure 4), it can be seen that the amount of PFAS adsorbed per unit volume of granular activated carbon increases as follows. • Number of repetitions: 1 (PFOS adsorption: 2.30 times, PFOA adsorption: 2.31 times, PFHxS adsorption: 1.98 times, PFHxA adsorption: 1.65 times) • Number of repetitions: 2 (PFOS adsorption: 2.30 times, PFOA adsorption: 4.62 times, PFHxS: 2.30 times, PFHxA adsorption: cannot be compared because the adsorption amount of material A is 0 ng / g)

[0051] The results in Figure 5 show that when only zeolite is added to simulated contaminated water 2, PFOS, PFOA, PFHxS, and PFHxA are hardly adsorbed by the zeolite.

[0052] The results shown in Figures 4-6 indicate that adding both granular activated carbon and zeolite to simulated contaminated water 2 increases the amount of PFAS adsorbed per unit volume of granular activated carbon, resulting in a synergistic effect. Furthermore, it is evident that not only does the amount of PFAS adsorbed increase, but the combination of granular activated carbon and zeolite maintains the PFAS adsorption capacity even after repeated use.

[0053] Furthermore, the results in Figures 1-6 show that even when simulated contaminated water 2 has higher turbidity than simulated contaminated water 1 and contains many impurities other than PFOS, PFOA, PFHxS, and PFHxA, adding both granular activated carbon and zeolite increases the amount of PFAS adsorbed, and the PFAS adsorption capacity can be maintained even after repeated use. In other words, the results in Figures 1 and 4 show that when the simulated contaminated water contains many impurities, as in the case of simulated contaminated water 2, the amount of PFAS adsorbed per unit amount of granular activated carbon decreases. In contrast, the results in Figure 6 show that by adding both granular activated carbon and zeolite to simulated contaminated water 2, the decrease in the amount of PFAS adsorbed per unit amount of granular activated carbon can be suppressed, even when the water contains many impurities.

[0054] The zeolite used in materials B and C (Itaya zeolite, manufactured by Zeeklite Co., Ltd.) contains clinoptilite, mordenite, etc., and is equivalent to a high-silica zeolite with a Si / Al ratio of 3 or higher. Furthermore, the above zeolite contains 2.1-2.9% K2O and 2.7-4.3% Na2O, which is a higher proportion of K2O and Na2O compared to natural zeolite (1.8% K2O and 2.3% Na2O). In the previous test, the above zeolite showed better results than natural zeolite, so the above zeolite was used in test examples 1-3.

[0055] [Test Example 3: Adsorption of organofluorine compounds by components (A) and (B) (upward flow column water flow test)] <Preparation of simulated contaminated water 3> Commercially available decomposed granite soil (from Kagawa Prefecture, manufactured by Kanea Co., Ltd.) was sieved to a size of less than 2 mm, and approximately 2 L of tap water was added. Further, PFOS solution (1 mg / L) and PFOA solution (1.4 mg / L) were added to the aqueous solution so that the concentrations of these substances in the solution were 20 μg / L for PFOS and 28 μg / L for PFOA, thereby preparing simulated contaminated water. The decomposed granite soil was filtered out of the above simulated contaminated water to prepare simulated contaminated water 3 (turbidity 9 degrees).

[0056] <Column creation> A plastic column with an inner diameter of 5 cm and a length of 5 cm was used as the column. Column A was prepared by packing 70 g of granular activated carbon (manufactured by Futamura Chemical Co., Ltd.), Column B by packing 70 g of zeolite (Itaya zeolite, manufactured by Zeeklite Co., Ltd.), and Column C by packing 70 g of granular activated carbon (manufactured by Futamura Chemical Co., Ltd.) and 70 g of zeolite (Itaya zeolite, manufactured by Zeeklite Co., Ltd.).

[0057] <Upward flow column water flow test> Simulated contaminated water 3 was passed through each column in an upward flow at a rate of 1.2 mL / min. Samples were taken from the column outlet every 70 mL of water passed through columns A and B, and every 140 mL of water passed through column C. The concentrations of PFOS and PFOA in the leachate were measured by LC / MS / MS according to "Appendix 1: Measurement Method for Perfluorooctanesulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA)" in Environmental Water and Land Affairs Notifications No. 2005281 and No. 2005282. The results are shown in Tables 1 to 3.

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] The results in Tables 1 and 3 show that column C, which is packed with granular activated carbon and zeolite, can maintain its ability to adsorb PFOS and PFOA contained in simulated contaminated water 3 over a longer period of time compared to column A, which is packed with granular activated carbon alone. Furthermore, the results in Table 2 show that column B, which is packed with zeolite alone, hardly adsorbs any PFOS and PFOA contained in the simulated contaminated water 3.

Claims

1. An adsorbent containing (A) activated carbon and (B) zeolite.

2. The adsorbent according to claim 1, wherein the Si / Al molar ratio of component (B) is 1 to 1000.

3. In the aforementioned component (B), when component (B) is 100% by mass, K ２ The oxygen content is 1.9 to 3.3% by mass, and Na ２ The adsorbent according to claim 1, characterized in that it contains 2.4 to 4.7% by mass of oxygen.

4. An adsorbent for removing organofluorine compounds, as described in any one of claims 1 to 3.

5. An adsorbent material for permeable purification walls, as described in any one of claims 1 to 3.

6. A method for removing organofluorine compounds, comprising the step of contacting contaminated water contaminated with organofluorine compounds with an adsorbent containing (A) activated carbon and (B) zeolite.

7. A method for removing organofluorine compounds, comprising the steps of (B) contacting contaminated water contaminated with organofluorine compounds with an adsorbent containing zeolite, and (A) contacting contaminated water containing organofluorine compounds with an adsorbent containing activated carbon.

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