JP7427849B1

JP7427849B1 - Activated carbon for water treatment

Info

Publication number: JP7427849B1
Application number: JP2023544746A
Authority: JP
Inventors: 孝規塚▲崎▼; 陽司一樂
Original assignee: Kansai Coke and Chemicals Co Ltd
Current assignee: Kansai Coke and Chemicals Co Ltd
Priority date: 2023-03-01
Filing date: 2023-03-01
Publication date: 2024-02-05
Anticipated expiration: 2043-03-01
Also published as: WO2024180739A1

Abstract

ＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡに対して優れた吸着性能を有する処理用活性炭を提供すること。比表面積が２０２０～４０００ｍ２／ｇ、比表面積当たりの全酸性官能基量が０．２０μｅｑ／ｍ２以下、ゼータ電位が－４０ｍＶ以上、である水処理用活性炭。To provide activated carbon for treatment which has excellent adsorption performance for PFAS, especially PFOS and PFOA. Activated carbon for water treatment having a specific surface area of 2020 to 4000 m2/g, a total amount of acidic functional groups per specific surface area of 0.20 μeq/m2 or less, and a zeta potential of -40 mV or more.

Description

本発明は水処理用活性炭に関する。 The present invention relates to activated carbon for water treatment.

パーフルオロアルキル化合物、およびポリフルオロアルキル化合物（以下、ＰＦＡＳという）は、様々な工業工程や消費者製品で使用されている化学物質であり、現在、４７００以上もの様々な化合物がＰＦＡＳとして知られている。特にＰＦＯＳ（ＰｅｒｆｌｕｏｒｏｏｃｔａｎｅＳｕｌｆｏｎａｔｅ）やＰＦＯＡ（ＰｅｒｆｌｕｏｒｏｏｃｔａｎｏｉｃＡｃｉｄ）は撥水剤や消化剤など様々な製品で使用されているが、環境残留性、生物蓄積性に問題があることが指摘されている。またＰＦＯＳ、ＰＦＯＡは河川水や海水、水道水中でも検出されるなど、非常に広範囲での汚染が問題となっていた。そのためＰＦＡＳ、特にＰＦＯＳやＰＦＯＡを除去する技術が求められていた。 Perfluoroalkyl and polyfluoroalkyl compounds (hereinafter referred to as PFAS) are chemicals used in a variety of industrial processes and consumer products, and there are currently over 4,700 different compounds known as PFAS. There is. In particular, PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid) are used in various products such as water repellents and extinguishers, but it has been pointed out that they have problems with environmental persistence and bioaccumulation. In addition, PFOS and PFOA have been detected in river water, seawater, and tap water, and contamination over a very wide range has become a problem. Therefore, a technology for removing PFAS, especially PFOS and PFOA, has been required.

例えば特許文献１には、活性炭吸着材のＢＥＴ比表面積が８００ｍ^２／ｇ以上又は表面酸化物量が０．２０ｍｅｑ／ｇ以下である水試料中のペル及びポリフルオロアルキル化合物を脱離可能に吸着するための水試料中のペル及びポリフルオロアルキル化合物吸着活性炭が開示されている。 For example, Patent Document 1 discloses that an activated carbon adsorbent has a BET specific surface area of 800 m ² /g or more or a surface oxide amount of 0.20 meq/g or less, which adsorbs per- and polyfluoroalkyl compounds in a water sample in a desorbable manner. Activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples is disclosed.

特許文献２には、活性炭吸着材のＢＥＴ比表面積が８００ｍ^２／ｇ以上であって、表面酸化物量が０．５０ｍｅｑ／ｇ以下であり、かつ、細孔直径１ｎｍ以下のミクロ孔容積の和（Ｖｍｉｃ）が０．３０ｃｍ^３／ｇ以上であることを特徴とする水試料中のペル及びポリフルオロアルキル化合物吸着活性炭が開示されている。 Patent Document 2 states that an activated carbon adsorbent has a BET specific surface area of 800 m ² /g or more, a surface oxide amount of 0.50 meq/g or less, and a sum of micropore volumes with a pore diameter of 1 nm or less ( Disclosed is an activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples, characterized in that the activated carbon has a Vmic) of 0.30 cm ³ /g or more.

特許文献３には、夾雑物を含有する水中のペルフルオロアルキル化合物を吸着するための活性炭吸着材であって、前記活性炭吸着材がＤＨプロット法による測定において細孔直径が２～５０ｎｍの細孔における細孔容積和が０．０２５ｃｍ^３／ｇ以下であり、前記活性炭吸着材がＭＰプロット法による測定において細孔直径が１．５～２ｎｍの細孔における細孔容積和が０．０１４ｃｍ^３／ｇ以上であることを特徴とするペルフルオロアルキル化合物吸着活性炭が開示されている。 Patent Document 3 discloses an activated carbon adsorbent for adsorbing perfluoroalkyl compounds in water containing impurities, the activated carbon adsorbent having a pore diameter of 2 to 50 nm as measured by a DH plot method. The total pore volume is 0.025 cm ³ /g or less, and the activated carbon adsorbent has a pore diameter of 0.014 cm ³ /g in pores with a pore diameter of 1.5 to 2 nm as measured by the MP plot method. A perfluoroalkyl compound adsorbing activated carbon characterized by the above characteristics is disclosed.

国際公開第２０２１／０３３５９６号International Publication No. 2021/033596 特開２０２２－１７１７１１号公報Japanese Patent Application Publication No. 2022-171711 国際公開第２０２２／２５５２４９号International Publication No. 2022/255249

本発明の目的は、ＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡに対して優れた吸着性能を有する処理用活性炭を提供することである。 An object of the present invention is to provide activated carbon for treatment that has excellent adsorption performance for PFAS, particularly PFOS and PFOA.

本発明の活性炭は以下の構成を有する。
［１］比表面積が２０２０～４０００ｍ^２／ｇ、比表面積当たりの全酸性官能基量が０．２０μｅｑ／ｍ^２以下、ゼータ電位が－４０ｍＶ以上である水処理用活性炭。
［２］細孔径１ｎｍ以下のミクロ孔容積が０．３ｍＬ／ｇ未満、且つ細孔径２ｎｍ以下のミクロ孔容積と細孔径２～３０ｎｍのメソ孔容積の差が０．４５ｍＬ／ｇ以下である［１］に記載の活性炭。
［３］全酸性官能基量が０．５ｍｅｑ／ｇ以下、かつ、酸素含有量が３．０ｗｔ％以下である［１］または［２］に記載の活性炭。
［４］下記式（１）から求められるミクロ孔容積の割合が８０％以下、且つ下記式（２）から求められるメソ孔容積の割合が２０％以上である［１］～［３］のいずれかに記載の活性炭。
ミクロ孔容積／（ミクロ孔容積＋メソ孔容積）×１００・・・（１）
メソ孔容積／（ミクロ孔容積＋メソ孔容積）×１００・・・（２）
［５］前記活性炭は水中のペルフルオロアルキル化合物、およびポリフルオロアルキル化合物に対する吸着能を有するものである［１］～［４］のいずれかに記載の活性炭。
［６］前記活性炭はアルカリ賦活炭である［１］～［５］のいずれかに記載の活性炭。
［７］［１］～［６］のいずれかに記載の活性炭を用いた浄水器。 The activated carbon of the present invention has the following configuration.
[1] Activated carbon for water treatment having a specific surface area of 2020 to 4000 m ² /g, a total amount of acidic functional groups per specific surface area of 0.20 μeq/m ² or less, and a zeta potential of -40 mV or more.
[2] The volume of micropores with a pore diameter of 1 nm or less is less than 0.3 mL/g, and the difference between the volume of micropores with a pore diameter of 2 nm or less and the volume of mesopores with a pore diameter of 2 to 30 nm is 0.45 mL/g or less [ 1].
[3] The activated carbon according to [1] or [2], wherein the total amount of acidic functional groups is 0.5 meq/g or less and the oxygen content is 3.0 wt% or less.
[4] Any of [1] to [3], wherein the proportion of micropore volume calculated from the following formula (1) is 80% or less, and the proportion of mesopore volume calculated from the following formula (2) is 20% or more. Activated carbon as described in Crab.
Micropore volume/(micropore volume + mesopore volume) x 100...(1)
Mesopore volume/(micropore volume + mesopore volume) x 100...(2)
[5] The activated carbon according to any one of [1] to [4], wherein the activated carbon has an adsorption ability for perfluoroalkyl compounds and polyfluoroalkyl compounds in water.
[6] The activated carbon according to any one of [1] to [5], wherein the activated carbon is alkali-activated carbon.
[7] A water purifier using the activated carbon according to any one of [1] to [6].

本発明によればＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡに対して優れた吸着性能を有する処理用活性炭を提供することができる。
したがって本発明の活性炭は水中に存在するＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡ除去に有効である。 According to the present invention, it is possible to provide activated carbon for treatment that has excellent adsorption performance for PFAS, particularly PFOS and PFOA.
Therefore, the activated carbon of the present invention is effective in removing PFAS present in water, particularly PFOS and PFOA.

図１は、実施例と比較例のＰＦＯＳ平衡吸着量を示すグラフである。FIG. 1 is a graph showing the equilibrium adsorption amount of PFOS in Examples and Comparative Examples. 図２は、実施例と比較例のＰＦＯＡ平衡吸着量を示すグラフである。FIG. 2 is a graph showing the equilibrium adsorption amount of PFOA in Examples and Comparative Examples. 図３は、実施例と比較例のＰＦＯＡ累積通水量を示すグラフである。FIG. 3 is a graph showing the cumulative water flow amount of PFOA in Examples and Comparative Examples. 図４は、実施例と比較例の遊離残留塩素累積通水量を示すグラフである。FIG. 4 is a graph showing the cumulative water flow amount of free residual chlorine in Examples and Comparative Examples. 図５は、実施例と比較例のクロラミン累積通水量を示すグラフである。FIG. 5 is a graph showing the cumulative amount of chloramine water flow in Examples and Comparative Examples. 図６は、実施例と比較例のクロロホルム平衡吸着量を示すグラフである。FIG. 6 is a graph showing the equilibrium adsorption amount of chloroform in Examples and Comparative Examples.

本発明者らが鋭意研究を重ねた結果、活性炭を高比表面積とし、且つ比表面積当たりの全酸性官能基量と、ゼータ電位を適切に制御すると、活性炭の細孔に起因する吸着性能とゼータ電位に起因する吸着性能の相乗効果によって、水中に存在するＰＦＡＳの除去効果を向上できることを見出し、本発明に至った。
本発明の活性炭は、比表面積が２０２０～４０００ｍ^２／ｇ、比表面積当たりの全酸性官能基量が０．２０μｅｑ／ｍ^２以下、ゼータ電位が－４０ｍＶ以上である。 As a result of extensive research by the present inventors, we have found that if activated carbon has a high specific surface area and the total amount of acidic functional groups per specific surface area and zeta potential are appropriately controlled, the adsorption performance due to the activated carbon's pores will improve. It has been discovered that the removal effect of PFAS present in water can be improved by the synergistic effect of adsorption performance caused by electric potential, leading to the present invention.
The activated carbon of the present invention has a specific surface area of 2020 to 4000 m ² /g, a total amount of acidic functional groups per specific surface area of 0.20 μeq/m ² or less, and a zeta potential of -40 mV or more.

比表面積
本発明において比表面積はＰＦＡＳ（特にＰＦＯＡ、ＰＦＯＳ、以下同じ）に対する吸着性能を考慮して規定した物性である。
比表面積が２０２０ｍ^２／ｇ以上であると、活性炭の細孔構造がＰＦＡＳなどの被吸着物質の吸着に適した細孔が多くなると共に、被処理媒体である水との接触面積が大きくなるため吸着性能が格段に向上すると共に、ＰＦＡＳ吸着量も増大する。一方、比表面積が４０００ｍ^２／ｇを超えると活性炭の強度が低下すると共に、活性炭の細孔構造が変化して吸着性能が低下する。
活性炭の比表面積は、２０２０ｍ^２／ｇ～４０００ｍ^２／ｇ、好ましくは２２００ｍ^２／ｇ～３８００ｍ^２／ｇ、より好ましくは２５００ｍ^２／ｇ～３５００ｍ^２／ｇ、さらに好ましくは２８００ｍ^２／ｇ～３２００ｍ^２／ｇである。
なお、本発明では数値範囲の上限、および下限を任意に組み合わせることができる。また各物性は任意に組み合わせた数値範囲同士を組み合わせて本発明の活性炭の好ましい物性とすることができる。本発明の活性炭の各物性は実施例記載の条件に基づく値である。 Specific Surface Area In the present invention, the specific surface area is a physical property defined in consideration of adsorption performance for PFAS (particularly PFOA and PFOS, hereinafter the same).
When the specific surface area is 2020 m ² /g or more, the pore structure of activated carbon has a large number of pores suitable for adsorption of substances to be adsorbed such as PFAS, and the contact area with water, which is the medium to be treated, increases. The adsorption performance is significantly improved and the amount of PFAS adsorbed is also increased. On the other hand, when the specific surface area exceeds 4000 m ² /g, the strength of the activated carbon decreases, and the pore structure of the activated carbon changes, resulting in a decrease in adsorption performance.
The specific surface area of the activated carbon is 2020 m ² /g to 4000 m ² /g, preferably 2200 m ² /g to 3800 m ² /g, more preferably 2500 m ² /g to 3500 m ² /g, even more preferably 2800 m ² /g to 3200 m ² /g.
Note that in the present invention, the upper and lower limits of the numerical ranges can be arbitrarily combined. In addition, each physical property can be set to preferable physical properties of the activated carbon of the present invention by combining arbitrary numerical ranges. Each physical property of the activated carbon of the present invention is a value based on the conditions described in Examples.

比表面積当たりの全酸性官能基量
本発明において比表面積当たりの全酸性官能基量はＰＦＡＳ（特にＰＦＯＡ、ＰＦＯＳ、以下同じ）に対する吸着性能を考慮して規定した物性である。
比表面積当たりの全酸性官能基量を低減すると、ＰＦＡＳに対する吸着性能を著しく向上できる。
活性炭の比表面積当たりの全酸性官能基量は０．２０μｅｑ／ｍ^２以下であり、好ましくは０．１８μｅｑ／ｍ^２以下、より好ましくは０．１５μｅｑ／ｍ^２以下、さらに好ましくは０．１３μｅｑ／ｍ^２以下、よりさらに好ましくは０．１０μｅｑ／ｍ^２以下である。比表面積当たりの全酸性官能基量は少ない程よいため下限は特に限定されず、０μｅｑ／ｍ^２であってもよいが、製造コストや技術的難易度を考慮して下限は例えば０μｅｑ／ｍ^２超でもよい。
酸性官能基とは、実施例に示す塩基性試薬と反応し得る基であり、全酸性官能基とは、（１）ヒドロキシ基（Ｒ－ＯＨ基）、（２）カルボキシ基（Ｒ－ＣＯＯＨ基）、（３）ラクトン基などのエステル基（Ｒ－ＯＣＯ基）、および（４）α，β－不飽和カルボニル基などのカルボニル基（キノン構造に含まれるカルボニル基など：Ｒ＝Ｏ基）をいう。
また全酸性官能基量とは、実施例に記載の測定方法によって求められる活性炭に含まれる上記（１）～（４）の各酸性官能基の合計量をいう。 Total amount of acidic functional groups per specific surface area In the present invention, the total amount of acidic functional groups per specific surface area is a physical property defined in consideration of the adsorption performance for PFAS (particularly PFOA and PFOS, hereinafter the same).
By reducing the total amount of acidic functional groups per specific surface area, the adsorption performance for PFAS can be significantly improved.
The total amount of acidic functional groups per specific surface area of activated carbon is 0.20 μeq/m ² or less, preferably 0.18 μeq/m ² or less, more preferably 0.15 μeq/m ² or less, and even more preferably 0.13 μeq/m 2 or less. m ² or less, more preferably 0.10 μeq/m ² or less. The lower limit is not particularly limited because the lower the total amount of acidic functional groups per specific surface area, the better, and may be 0 μeq/ ^m2 , but in consideration of manufacturing cost and technical difficulty, the lower limit is, for example, ^more than 0 μeq/m2. But that's fine.
The acidic functional group is a group that can react with the basic reagent shown in the examples, and the total acidic functional groups include (1) hydroxy group (R-OH group), (2) carboxy group (R-COOH group). ), (3) ester groups (R-OCO groups) such as lactone groups, and (4) carbonyl groups such as α,β-unsaturated carbonyl groups (carbonyl groups included in the quinone structure: R=O group). say.
In addition, the total amount of acidic functional groups refers to the total amount of each of the above-mentioned acidic functional groups (1) to (4) contained in the activated carbon determined by the measurement method described in the Examples.

ゼータ電位
本発明においてゼータ電位は、ＰＦＡＳ（特にＰＦＯＡ、ＰＦＯＳ、以下同じ）に対する吸着性能を考慮して規定した物性である。
ゼータ電位を－４０ｍＶ以上にすると、－４０ｍＶ未満である場合と比べてＰＦＡＳに対する吸着性能が格段に向上する。ゼータ電位の絶対値が大きくなりすぎると活性炭表面とＰＦＡＳ分子との間に作用する斥力が大きくなって反発し合うため吸着力が低下することがある。
活性炭のゼータ電位は－４０ｍＶ以上であり、好ましくは－３８ｍＶ～３８ｍＶ、より好ましくは－３５ｍＶ～３５ｍＶ、さらに好ましくは－３０ｍＶ～３０ｍＶ、よりさらに好ましくは－２８ｍＶ～２８ｍＶである。 Zeta Potential In the present invention, zeta potential is a physical property defined in consideration of adsorption performance for PFAS (particularly PFOA and PFOS, hereinafter the same).
When the zeta potential is -40 mV or more, the adsorption performance for PFAS is significantly improved compared to when it is less than -40 mV. If the absolute value of the zeta potential becomes too large, the repulsive force acting between the activated carbon surface and the PFAS molecules becomes large and they repel each other, which may reduce the adsorption force.
The zeta potential of activated carbon is -40 mV or more, preferably -38 mV to 38 mV, more preferably -35 mV to 35 mV, even more preferably -30 mV to 30 mV, even more preferably -28 mV to 28 mV.

本発明の活性炭は、好ましくはアルカリ賦活された活性炭（以下、アルカリ賦活炭ということがある）である。 The activated carbon of the present invention is preferably alkali-activated activated carbon (hereinafter sometimes referred to as alkali-activated carbon).

上記各物性を満足する活性炭は水中のＰＦＡＳ吸着に優れた特性を有する。また本発明の活性炭はＰＦＡＳの吸着だけでなく、次亜塩素酸等の遊離残留塩素やクロラミン等の結合残留塩素などの総残留塩素の除去にも優れた効果を有する。一方、本発明の活性炭は後記するようにクロロホルムなどのように活性炭細孔へ物理吸着する吸着質（化合物）はＰＦＡＳと競争吸着する可能性がある。そのため本発明の活性炭はＰＦＡＳと競争吸着するような化合物の吸着量を低くすることにより、ＰＦＡＳ吸着により優れた効果を発揮する。 Activated carbon that satisfies each of the above physical properties has excellent properties for adsorbing PFAS in water. Furthermore, the activated carbon of the present invention has an excellent effect not only in adsorbing PFAS but also in removing total residual chlorine such as free residual chlorine such as hypochlorous acid and combined residual chlorine such as chloramine. On the other hand, in the activated carbon of the present invention, as will be described later, adsorbates (compounds) that physically adsorb into the activated carbon pores, such as chloroform, may be competitively adsorbed with PFAS. Therefore, the activated carbon of the present invention exhibits superior effects in adsorbing PFAS by reducing the adsorption amount of compounds that competitively adsorb with PFAS.

本発明の活性炭は以下の物性を適切に制御することもＰＦＡＳ吸着性能のより一層の向上に有効である。 Appropriate control of the following physical properties of the activated carbon of the present invention is also effective in further improving the PFAS adsorption performance.

ミクロ孔容積、およびメソ孔容積
本発明の活性炭は細孔径１ｎｍ以下のミクロ孔容積が０．３ｍＬ／ｇ未満、且つ細孔径２ｎｍ以下のミクロ孔容積と細孔径２～３０ｎｍのメソ孔容積との差が０．４５ｍＬ／ｇ以下であることも好ましい実施態様である。 Micropore volume and mesopore volume The activated carbon of the present invention has a micropore volume with a pore diameter of 1 nm or less of less than 0.3 mL/g, and a micropore volume with a pore diameter of 2 nm or less and a mesopore volume with a pore diameter of 2 to 30 nm. It is also a preferred embodiment that the difference is 0.45 mL/g or less.

細孔径１ｎｍ以下のミクロ孔はＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡの最適な吸着サイトのサイズよりも小さいためＰＦＡＳの吸着力向上に対する寄与度は小さい。また後記するようにクロロホルムの吸着を抑制する観点からは１ｎｍ以下のミクロ孔容積は小さい程好ましい。
被処理水にはＰＦＡＳ以外の疎水性の化合物（以下、その他化合物ということがある）が存在していることがある。特にＰＦＡＳよりも活性炭との吸着力が高いその他化合物が存在すると、ＰＦＡＳとその他化合物との競合吸着が生じる可能性があり、いずれかの吸着質が脱離する可能性がある。活性炭との吸着力が高いその他化合物としてはクロロホルムが例示される。１ｎｍ以下の細孔容積はクロロホルムの吸着に寄与するため、上記競合吸着によるＰＦＡＳの脱離を抑制する観点からは１ｎｍ以下のミクロ孔容積は小さい程好ましい。
細孔径１ｎｍ以下のミクロ孔容積は、０．３ｍＬ／ｇ未満、０．２５ｍＬ／ｇ以下、０．２０ｍＬ／ｇ以下、０．１５ｍＬ／ｇ以下、０．１０ｍＬ／ｇ以下、０．０５ｍＬ／ｇ以下の順に小さい程好ましい。１ｎｍ以下のミクロ孔容積の下限は０ｍＬ／ｇであってもよいが製造難易度を考慮すると、下限は例えば０ｍＬ／ｇ超であってもよい。 Micropores with a pore diameter of 1 nm or less are smaller than the optimal adsorption site size for PFAS, particularly PFOS and PFOA, and therefore their contribution to improving the adsorption power of PFAS is small. Further, as will be described later, from the viewpoint of suppressing adsorption of chloroform, the smaller the micropore volume of 1 nm or less, the more preferable.
Hydrophobic compounds other than PFAS (hereinafter sometimes referred to as other compounds) may be present in the water to be treated. In particular, if other compounds that have a higher adsorption power with activated carbon than PFAS are present, competitive adsorption between PFAS and the other compounds may occur, and one of the adsorbates may be desorbed. Chloroform is exemplified as another compound that has a high adsorption power with activated carbon. Since the pore volume of 1 nm or less contributes to the adsorption of chloroform, the smaller the micropore volume of 1 nm or less is, the more preferable from the viewpoint of suppressing the desorption of PFAS due to the competitive adsorption.
Micropore volume with a pore diameter of 1 nm or less is less than 0.3 mL/g, 0.25 mL/g or less, 0.20 mL/g or less, 0.15 mL/g or less, 0.10 mL/g or less, 0.05 mL/g The smaller the value in the following order, the more preferable it is. The lower limit of the micropore volume of 1 nm or less may be 0 mL/g, but in consideration of manufacturing difficulty, the lower limit may be, for example, more than 0 mL/g.

細孔径２ｎｍ以下のミクロ孔容積と２～３０ｎｍのメソ孔容積との差（ミクロ孔－メソ孔）は、ＰＦＡＳに対する吸着容量増大と吸着サイトに至るまでの水の拡散速度向上のバランスを考慮すると小さい程よい。
細孔径２ｎｍ以下のミクロ孔容積と細孔径２～３０ｎｍのメソ孔容積との差（ミクロ孔－メソ孔）は０．４５ｍＬ／ｇ以下、０．４０ｍＬ／ｇ以下、０．３５ｍＬ／ｇ以下、０．３０Ｌ／ｇ以下、０．２５ｍＬ／ｇ以下、０．２０ｍＬ／ｇ以下、０．１５ｍＬ／ｇ以下の順に小さい程好ましい。 The difference between the volume of micropores with a pore diameter of 2 nm or less and the volume of mesopores with a pore diameter of 2 to 30 nm (micropores - mesopores) is determined by considering the balance between increasing the adsorption capacity for PFAS and increasing the diffusion rate of water to the adsorption site. The smaller the better.
The difference between the micropore volume with a pore diameter of 2 nm or less and the mesopore volume with a pore diameter of 2 to 30 nm (micropore - mesopore) is 0.45 mL / g or less, 0.40 mL / g or less, 0.35 mL / g or less, It is preferably as small as 0.30 L/g or less, 0.25 mL/g or less, 0.20 mL/g or less, and 0.15 mL/g or less.

またＰＦＡＳの脱離を抑制する観点からは活性炭のクロロホルム吸着量は少ない程、好ましい。活性炭のクロロホルム平衡吸着量は好ましくは２．５ｍｇ／ｇ以下、より好ましくは２．０ｍｇ／ｇ以下、さらに好ましくは１．５ｇ／ｇ以下、最も好ましくは０ｍｇ／ｇであるが、細孔径１ｎｍ以下のミクロ孔容積を全て無くすことは困難であるため０ｍｇ／ｇ超であってもよい。 Furthermore, from the viewpoint of suppressing the desorption of PFAS, it is preferable that the amount of chloroform adsorbed by activated carbon is as small as possible. The equilibrium adsorption amount of chloroform on activated carbon is preferably 2.5 mg/g or less, more preferably 2.0 mg/g or less, even more preferably 1.5 g/g or less, and most preferably 0 mg/g, but the pore size is 1 nm or less. Since it is difficult to completely eliminate the micropore volume, the amount may exceed 0 mg/g.

全酸性官能基量、および酸素含有量
全酸性官能基量が０．５ｍｅｑ／ｇ以下、かつ、酸素含有量が３．０ｗｔ％以下であることも好ましい実施態様である。
活性炭の全酸性官能基量が少なく、かつ酸素含有量が少ない程、ＰＦＡＳに対する吸着性能が向上する。 Total acidic functional group amount and oxygen content It is also a preferred embodiment that the total acidic functional group amount is 0.5 meq/g or less and the oxygen content is 3.0 wt% or less.
The lower the total amount of acidic functional groups and the lower the oxygen content of activated carbon, the better the adsorption performance for PFAS will be.

活性炭の全酸性官能基量は、好ましくは０．５０ｍｅｑ／ｇ以下、より好ましくは０．４５ｍｅｑ／ｇ以下、さらに好ましくは０．４０ｍｅｑ／ｇ以下、よりさらに好ましくは０．３５ｍｅｑ／ｇ以下である。全酸性官能基量は少ない程よく、０ｍｅｑ／ｇであってもよいが製造難易度を考慮すると、下限は例えば０ｍｅｑ／ｇ超であってもよい。 The total amount of acidic functional groups in the activated carbon is preferably 0.50 meq/g or less, more preferably 0.45 meq/g or less, even more preferably 0.40 meq/g or less, even more preferably 0.35 meq/g or less. . The lower the total amount of acidic functional groups, the better, and it may be 0 meq/g, but considering the difficulty of production, the lower limit may be, for example, more than 0 meq/g.

活性炭の酸素含有量は、好ましくは３．０ｗｔ％以下、より好ましくは２．０ｗｔ％以下、さらに好ましくは２．０ｗｔ％以下、よりさらに好ましくは１．５ｗｔ％以下である。酸素含有量は少ない程よく、０ｗｔ％であってもよいが製造難易度を考慮すると、下限は例えば０ｗｔ％超であってもよい。 The oxygen content of the activated carbon is preferably 3.0 wt% or less, more preferably 2.0 wt% or less, even more preferably 2.0 wt% or less, even more preferably 1.5 wt% or less. The lower the oxygen content, the better, and it may be 0 wt%, but in consideration of manufacturing difficulty, the lower limit may be, for example, more than 0 wt%.

ミクロ孔容積の割合、およびメソ孔容積の割合
本発明の活性炭は、ミクロ孔容積の割合（ミクロ孔容積／（ミクロ孔容積＋メソ孔容積）×１００）が８０％以下であって、メソ孔容積の割合（メソ孔容積／（ミクロ孔容積＋メソ孔容積）×１００）が２０％以上であることも好ましい実施態様である。
ミクロ容積とメソ孔容積の合計に対するミクロ孔容積の割合が多いとＰＦＡＳの吸着量増大に有効であり、また前記合計に対するメソ孔容積の割合が多いと水の拡散速度向上に有効であり、効率的なＰＦＡＳ含有水の処理を行える。 Micropore volume ratio and mesopore volume ratio The activated carbon of the present invention has a micropore volume ratio (micropore volume/(micropore volume + mesopore volume) x 100) of 80% or less, and has mesopores. It is also a preferred embodiment that the volume ratio (mesopore volume/(micropore volume + mesopore volume) x 100) is 20% or more.
A high ratio of micropore volume to the total of microvolume and mesopore volume is effective in increasing the adsorption amount of PFAS, and a high ratio of mesopore volume to the total is effective in increasing the water diffusion rate, which increases efficiency. can be used to treat PFAS-containing water.

ミクロ孔容積の割合（ミクロ孔容積／（ミクロ孔容積＋メソ孔容積）×１００）は、好ましくは８０％以下、より好ましくは７０％以下、さらに好ましくは６０％以下、よりさらに好ましくは５５％以下である。
ミクロ孔容積の割合の下限は下記メソ孔容積の割合に対応する値である。 The ratio of micropore volume (micropore volume/(micropore volume + mesopore volume) x 100) is preferably 80% or less, more preferably 70% or less, still more preferably 60% or less, even more preferably 55%. It is as follows.
The lower limit of the micropore volume ratio is a value corresponding to the mesopore volume ratio below.

メソ孔容積の割合（メソ孔容積／（ミクロ孔容積＋メソ孔容積）×１００）は、好ましくは２０％以上、より好ましくは３０％以上、さらに好ましくは４０％以上、よりさらに好ましくは４５％以上である。 The ratio of mesopore volume (mesopore volume/(micropore volume + mesopore volume) x 100) is preferably 20% or more, more preferably 30% or more, still more preferably 40% or more, even more preferably 45%. That's all.

本発明の活性炭は全細孔容積を制御することも好ましい実施態様である。
ＰＦＡＳに対する吸着量を確保するためには細孔容積は大きい方が好ましいが、細孔容積を大きくし過ぎると使用時の活性炭の充填密度の低下を招くため、体積当たりの吸着性能が低下することがある。
本発明の活性炭の全細孔容積は、好ましくは０．５ｍＬ／ｇ～４．０ｍＬ／ｇ、より好ましくは０．７ｍＬ／ｇ～３．０ｍＬ／ｇ、さらに好ましくは１．０ｍＬ／ｇ～２．０ｍＬ／ｇである。 It is also a preferred embodiment that the activated carbon of the present invention has controlled total pore volume.
In order to ensure the adsorption amount for PFAS, it is preferable to have a large pore volume, but if the pore volume is made too large, the packing density of activated carbon during use will decrease, resulting in a decrease in adsorption performance per volume. There is.
The total pore volume of the activated carbon of the present invention is preferably 0.5 mL/g to 4.0 mL/g, more preferably 0.7 mL/g to 3.0 mL/g, even more preferably 1.0 mL/g to 2 .0 mL/g.

本発明の活性炭は、平均細孔径を制御することも好ましい実施態様である。
平均細孔径を大きくするとＰＦＡＳ含有水の細孔内への拡散性が向上して吸着性能が向上する。一方、平均細孔径が大きくなりすぎると嵩高くなって使用時の活性炭の充填量が減少すると共に、ＰＦＡＳ吸着サイトが減少し吸着能が低下することがある。
本発明の多孔質炭素材料の平均細孔径は、好ましくは１．５ｎｍ～５．０ｎｍ、より好ましくは１．７５ｎｍ～４．０ｎｍ、さらに好ましくは１．９ｎｍ～３．０ｎｍ、よりさらに好ましくは２．０ｎｍ～２．５ｎｍである。 In the activated carbon of the present invention, it is also a preferred embodiment to control the average pore diameter.
When the average pore diameter is increased, the diffusivity of PFAS-containing water into the pores is improved, and the adsorption performance is improved. On the other hand, if the average pore diameter becomes too large, it becomes bulky and the amount of activated carbon packed during use decreases, and the number of PFAS adsorption sites decreases, resulting in a decrease in adsorption capacity.
The average pore diameter of the porous carbon material of the present invention is preferably 1.5 nm to 5.0 nm, more preferably 1.75 nm to 4.0 nm, even more preferably 1.9 nm to 3.0 nm, even more preferably 2 .0 nm to 2.5 nm.

活性炭の形状
本発明の活性炭は、用途に応じた形状にすればよく、粉末状、粒状、破砕状（顆粒状）、繊維状などが例示される。また炭素系金属吸着材は、必要に応じてバインダーや他の吸着材と共に、円柱状、球状、シート状など任意の形状に成形してもよい。活性炭の粒子径は用途に応じて適宜調整できる。 Shape of Activated Carbon The activated carbon of the present invention may be shaped in accordance with the intended use, and examples include powder, granules, crushed (granules), and fibrous shapes. Further, the carbon-based metal adsorbent may be formed into any shape such as a columnar shape, a spherical shape, a sheet shape, etc. together with a binder and other absorbent materials as necessary. The particle size of activated carbon can be adjusted as appropriate depending on the application.

本発明の活性炭は、水処理用途に好適である。被処理水の具体的として工場や家庭などからの排水、河川水、海水、飲料水、工業用水など各種ＰＦＡＳ含有水が挙げられる。
本発明の活性炭を用いてＰＦＡＳ含有水を処理すると、被処理水からＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡを除去できる。また本発明の活性炭はＰＦＡＳ以外の化合物、例えば次亜塩素酸等の遊離残留塩素やクロラミン等の結合残留塩素などの総残留塩素の除去にも優れた効果を有する。
本発明の活性炭による水処理は平衡状態と通水状態のいずれにも適用可能である。
本発明の水処理用途の具体例としては、浄水器、水処理用フィルターなど、被処理水と活性炭との接触によりＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡを除去する態様であれば適用できる。
なお、本発明の活性炭は吸着したＰＦＡＳが活性炭から脱離することがないため、活性炭の処分時にＰＦＡＳが流失することがない。したがって活性炭処分時にＰＦＡＳによる汚染も防止できる。 The activated carbon of the present invention is suitable for water treatment applications. Specific examples of water to be treated include various types of PFAS-containing water, such as wastewater from factories and households, river water, seawater, drinking water, and industrial water.
When PFAS-containing water is treated using the activated carbon of the present invention, PFAS, particularly PFOS and PFOA, can be removed from the water to be treated. The activated carbon of the present invention also has an excellent effect in removing total residual chlorine from compounds other than PFAS, such as free residual chlorine such as hypochlorous acid and combined residual chlorine such as chloramine.
The water treatment using activated carbon of the present invention can be applied in both an equilibrium state and a water flow state.
Specific examples of water treatment applications of the present invention include water purifiers, water treatment filters, and the like, as long as PFAS, particularly PFOS and PFOA, are removed by contacting the water to be treated with activated carbon.
Note that in the activated carbon of the present invention, since the adsorbed PFAS does not desorb from the activated carbon, the PFAS will not be washed away when the activated carbon is disposed of. Therefore, contamination by PFAS can also be prevented during activated carbon disposal.

以下、本発明の活性炭の好適な実施態様であるアルカリ賦活炭の製造方法を説明するが、本発明の製造方法は上記所望の物性が得られれば下記製造方法に限定されない。なお、下記製造条件は好ましい範囲を示したものであり、所望の物性が得られるように各製造条件を適切に調整することを要する。 Hereinafter, a method for producing alkali-activated carbon, which is a preferred embodiment of the activated carbon of the present invention, will be described, but the production method of the present invention is not limited to the following production method as long as the above desired physical properties are obtained. Note that the following manufacturing conditions indicate preferred ranges, and it is necessary to appropriately adjust each manufacturing condition so that desired physical properties can be obtained.

原料
本発明の活性炭の賦活原料となる炭素質材料としては、特に限定されないが、例えば、木材、鋸屑、木炭、ヤシ殻やクルミ殻などの果実殻、果実種子、パルプ製造副生物、リグニン、廃糖蜜などの植物由来の炭素質原料；泥炭、亜炭、褐炭、レキ青炭、無煙炭、コークス、コールタール、石炭ピッチ、石油蒸留残査、石油ピッチなどの鉱物由来の炭素質原料；フェノール樹脂、ポリ塩化ビニリデン、アクリル樹脂などの合成樹脂由来の炭素質原料；セルロースなどの天然繊維、レーヨンなどの再生繊維などの天然繊維由来の炭素質原料；ピッチ系炭素繊維などのコールタールピッチや石油ピッチ由来の炭素質材料が挙げられる。炭素質原料は、単独、または二種以上組み合わせて使用できる。これらの炭素質材料のうち、比表面積、酸性官能基量、及びゼータ電位を上記範囲に制御しやすいコールタールピッチや石油ピッチ由来の炭素質原料が好ましく、ピッチ系炭素繊維がより好ましい。 Raw Materials Carbonaceous materials that serve as activation raw materials for the activated carbon of the present invention are not particularly limited, but include, but are not limited to, wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, pulp production by-products, lignin, and waste. Carbonaceous raw materials derived from plants such as molasses; carbonaceous raw materials derived from minerals such as peat, lignite, lignite, yellow coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, petroleum pitch; phenolic resins, polyester, etc. Carbonaceous materials derived from synthetic resins such as vinylidene chloride and acrylic resin; Carbonaceous materials derived from natural fibers such as natural fibers such as cellulose and recycled fibers such as rayon; Carbonaceous materials derived from coal tar pitch and petroleum pitch such as pitch-based carbon fibers Examples include carbonaceous materials. The carbonaceous raw materials can be used alone or in combination of two or more. Among these carbonaceous materials, carbonaceous raw materials derived from coal tar pitch and petroleum pitch, which can easily control the specific surface area, amount of acidic functional groups, and zeta potential within the above ranges, are preferred, and pitch-based carbon fibers are more preferred.

炭化処理
上記賦活原料のうち、炭化されていない炭素質材料は賦活処理前に必要に応じて炭化処理することが好ましい。炭化処理は炭素質原料を窒素などの不活性ガス中で熱処理、例えば４００℃～１０００℃で１時間～３時間保持すればよい。なお、ピッチ系炭素繊維など既に炭化されている炭素質原料は、炭化処理をしなくてもよい。 Carbonization Treatment Among the above-mentioned activation raw materials, it is preferable that the carbonaceous material that has not been carbonized is subjected to a carbonization treatment as necessary before the activation treatment. The carbonization treatment may be carried out by subjecting the carbonaceous raw material to heat treatment in an inert gas such as nitrogen, for example by holding it at 400° C. to 1000° C. for 1 hour to 3 hours. Note that carbonaceous raw materials that have already been carbonized, such as pitch-based carbon fibers, do not need to be carbonized.

アルカリ賦活処理
本発明のアルカリ賦活処理はアルカリ金属化合物を含む賦活剤と、賦活原料とを混合し、不活性ガス中で加熱する工程である。アルカリ賦活処理条件を調整することで比表面積を上記範囲に制御できる。
アルカリ金属化合物は例えば、水酸化カリウム、水酸化ナトリウムなどのアルカリ金属水酸化物；炭酸カリウム、炭酸ナトリウムなどのアルカリ金属炭酸塩；硫酸カリウム、硫酸ナトリウムなどのアルカリ金属の硫酸塩である。好ましくはアルカリ金属水酸化物であり、より好ましくは水酸化カリウムである。 Alkali Activation Treatment The alkali activation treatment of the present invention is a process in which an activator containing an alkali metal compound and an activation raw material are mixed and heated in an inert gas. The specific surface area can be controlled within the above range by adjusting the alkali activation treatment conditions.
Examples of the alkali metal compound include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; alkali metal carbonates such as potassium carbonate and sodium carbonate; and alkali metal sulfates such as potassium sulfate and sodium sulfate. Preferably it is an alkali metal hydroxide, more preferably potassium hydroxide.

賦活剤の使用量は賦活原料に対する賦活剤の混合比率を高くする程、活性炭の比表面積が増大傾向を示すため、上記比表面積となるように賦活剤の混合比率を調整することが望ましい。賦活原料に対する賦活剤の質量比(賦活剤のアルカリ成分の質量/賦活原料の質量)は、好ましくは０．５以上、より好ましくは１．０以上、更に好ましくは２．０以上であって、好ましくは１０．０以下、より好ましくは５．０以下、更に好ましくは４．０以下である。 As for the amount of activator used, as the mixing ratio of the activator to the activation raw material increases, the specific surface area of the activated carbon tends to increase, so it is desirable to adjust the mixing ratio of the activator so that the specific surface area is as described above. The mass ratio of the activator to the activation raw material (mass of the alkaline component of the activator/mass of the activation raw material) is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 2.0 or more, Preferably it is 10.0 or less, more preferably 5.0 or less, still more preferably 4.0 or less.

アルカリ賦活処理はアルゴン、ヘリウム、窒素など任意の不活性ガス雰囲気下で行う。 The alkali activation treatment is performed in an atmosphere of any inert gas such as argon, helium, or nitrogen.

アルカリ賦活処理温度を高くすると賦活が進行して比表面積が高くなると共に全酸性官能基量が低下する傾向を示す。したがってアルカリ賦活処理時の加熱温度は好ましくは３５０℃～９５０℃、より好ましくは４００℃～９００℃、さらに好ましくは４５０℃～８５０℃、よりさらに好ましくは５００℃～８００℃である。
また上記加熱温度までの昇温速度は、好ましくは１℃／分以上、より好ましくは５℃／分以上であって、好ましくは２０℃／分以下、より好ましくは１５℃／分以下である。
上記加熱温度での賦活処理時間は好ましくは１時間～１０時間、より好ましくは２時間～８時間、さらに好ましくは３時間～７時間、より更に好ましくは３．５時間～５時間である。 When the alkali activation treatment temperature is increased, activation progresses, the specific surface area increases, and the total amount of acidic functional groups tends to decrease. Therefore, the heating temperature during the alkali activation treatment is preferably 350°C to 950°C, more preferably 400°C to 900°C, still more preferably 450°C to 850°C, even more preferably 500°C to 800°C.
Further, the rate of temperature increase to the above heating temperature is preferably 1° C./min or more, more preferably 5° C./min or more, and preferably 20° C./min or less, more preferably 15° C./min or less.
The activation treatment time at the above heating temperature is preferably 1 hour to 10 hours, more preferably 2 hours to 8 hours, even more preferably 3 hours to 7 hours, even more preferably 3.5 hours to 5 hours.

洗浄処理洗浄処理は、アルカリ賦活処理して得られた活性炭に水洗浄処理や無機酸洗浄処理を行ってアルカリ賦活炭中に残留するアルカリ金属を除去する工程である。洗浄処理は複数回繰り返すことでアルカリ金属除去率を高めることができる。 Cleaning Treatment The cleaning treatment is a step in which the activated carbon obtained by the alkali activation treatment is subjected to a water cleaning treatment or an inorganic acid cleaning treatment to remove alkali metals remaining in the alkali activated carbon. The alkali metal removal rate can be increased by repeating the cleaning process multiple times.

水洗浄処理
水洗浄処理で使用する水の温度は好ましくは２０℃～１００℃未満、より好ましくは３０℃～９０℃、さらに好ましくは４０℃～８０℃、よりさらに好ましくは５０℃～７０℃である。水洗浄処理は水洗浄とろ過を複数回繰り返し、ろ液のｐＨが例えば７．０以下となるまで行うことが望ましい。 Water washing treatment The temperature of the water used in the water washing treatment is preferably from 20°C to less than 100°C, more preferably from 30°C to 90°C, even more preferably from 40°C to 80°C, even more preferably from 50°C to 70°C. be. In the water washing treatment, it is desirable to repeat water washing and filtration multiple times until the pH of the filtrate becomes, for example, 7.0 or less.

無機酸洗浄処理
無機酸洗浄では無機酸として塩酸、フッ化水素酸等の水素酸や、硫酸、硝酸、リン酸、過塩素酸等の酸素酸などを使用でき、好ましくは塩酸である。
無機酸濃度はアルカリ賦活炭の物性を維持しつつ、アルカリ金属除去率を高める観点から調整することが好ましい。
無機酸水溶液中の無機酸濃度は必要に応じ適宜調整すればよい。無機酸濃度は好ましくは０．１ｗｔ％～３０ｗｔ％、より好ましくは０．５ｗｔ％～２０ｗｔ％、さらに好ましくは１．０ｗｔ％～１５ｗｔ％である。
無機酸水溶液の液温は、無機酸の揮発を抑制しつつ、アルカリ賦活炭中のアルカリ金属除去効率を高めることができる温度域に設定することが望ましい。
無機酸水溶液の温度は、好ましくは２０℃～１００℃未満、より好ましくは３０℃～９０℃、さらに好ましくは４０℃～８０℃、よりさらに好ましくは５０℃～７０℃である。
無機酸洗浄処理は洗浄とろ過を複数回繰り返し、アルカリ賦活炭中のカリウム残存量が好ましくは５０００ｍｇ／ｋｇ以下（０ｍｇ／ｋｇ超）であり、またアルカリ賦活炭中のアルカリ金属残存量が好ましくは２５００ｍｇ/ｋｇ以下（０ｍｇ／ｋｇ超）、より好ましくは１０００ｍｇ/ｋｇ以下（０ｍｇ／ｋｇ超）、さらに好ましくは５００ｍｇ／ｋｇ以下（０ｍｇ／ｋｇ超）となるまで行うことが望ましい。アルカリ賦活炭中のアルカリ金属残存量はＩＣＰ発光分光分析装置で測定できる。 Inorganic Acid Cleaning Treatment In the inorganic acid cleaning process, hydrogen acids such as hydrochloric acid and hydrofluoric acid, and oxygen acids such as sulfuric acid, nitric acid, phosphoric acid, and perchloric acid can be used as inorganic acids, and hydrochloric acid is preferred.
It is preferable to adjust the inorganic acid concentration from the viewpoint of increasing the alkali metal removal rate while maintaining the physical properties of the alkali-activated carbon.
The concentration of the inorganic acid in the inorganic acid aqueous solution may be adjusted as necessary. The inorganic acid concentration is preferably 0.1 wt% to 30 wt%, more preferably 0.5 wt% to 20 wt%, even more preferably 1.0 wt% to 15 wt%.
The liquid temperature of the inorganic acid aqueous solution is desirably set in a temperature range that can increase the efficiency of removing alkali metals from the alkali-activated carbon while suppressing volatilization of the inorganic acid.
The temperature of the inorganic acid aqueous solution is preferably 20°C to less than 100°C, more preferably 30°C to 90°C, even more preferably 40°C to 80°C, even more preferably 50°C to 70°C.
In the inorganic acid cleaning treatment, washing and filtration are repeated multiple times, and the residual amount of potassium in the alkali-activated carbon is preferably 5000 mg/kg or less (more than 0 mg/kg), and the residual amount of alkali metal in the alkali-activated carbon is preferably It is desirable to carry out the treatment until the concentration is 2500 mg/kg or less (more than 0 mg/kg), more preferably 1000 mg/kg or less (more than 0 mg/kg), even more preferably 500 mg/kg or less (more than 0 mg/kg). The amount of alkali metal remaining in the alkali-activated carbon can be measured using an ICP emission spectrometer.

水洗浄処理
水洗浄処理は、無機酸洗浄処理後、水洗浄処理してアルカリ賦活炭中に残留する無機酸を除去する工程である。
水洗浄処理で使用する水の温度は無機酸の除去効率を考慮して設定することが望ましい。
洗浄水の温度は、好ましくは２０℃～１００℃未満、より好ましくは３０℃～９０℃、さらに好ましくは４０℃～８０℃、よりさらに好ましくは５０℃～７０℃である。
水洗浄処理は水洗浄とろ過を複数回繰り返し、ろ液のｐＨが６．５以上となるまで行うことが望ましい。 Water Washing Process The water washing process is a process of removing the inorganic acid remaining in the alkali activated carbon by washing with water after the inorganic acid washing process.
It is desirable to set the temperature of the water used in the water washing treatment in consideration of the removal efficiency of inorganic acids.
The temperature of the washing water is preferably from 20°C to less than 100°C, more preferably from 30°C to 90°C, even more preferably from 40°C to 80°C, even more preferably from 50°C to 70°C.
In the water washing treatment, it is desirable to repeat water washing and filtration multiple times until the pH of the filtrate becomes 6.5 or higher.

乾燥処理
乾燥処理は、洗浄処理後のアルカリ賦活炭から水分を除去する工程である。
乾燥はアルカリ賦活炭に残存する水分を除去できる条件であればよく、例えば大気雰囲気下で例えば１００～１２０℃程度に加熱し、０．５時間～２４時間乾燥させることが望ましい。 Drying Process The drying process is a process of removing moisture from the alkali activated carbon after the washing process.
Drying may be carried out under any conditions that can remove moisture remaining in the alkali-activated carbon. For example, it is preferable to heat the carbon to about 100 to 120° C. and dry it for 0.5 to 24 hours in an air atmosphere.

加熱処理工程
加熱処理工程は、アルカリ賦活炭を加熱して全酸性官能基量を低減させると共に、ゼータ電位を上記範囲に制御する工程である。
加熱温度を高くするとアルカリ賦活炭から酸性官能基を離脱させることができると共に、ゼータ電位を上記範囲に誘導できるが、加熱温度を高くしすぎるとゼータ電位が上記範囲を外れたり、細孔構造が変化する。
加熱処理時の温度は、好ましくは８００℃～１５００℃、より好ましくは９００℃～１４００℃、さらに好ましくは１０００℃～１３００℃である。
上記加熱温度までの昇温速度は、好ましくは１℃／分～２０℃／分、より好ましくは５℃／分～１５℃／分、さらに好ましくは１０℃／分～１５℃／分である。
上記加熱温度での加熱時間は好ましくは３０分～１０時間、より好ましくは１時間～５時間、さらに好ましくは２時間～４時間である。 Heat Treatment Step The heat treatment step is a step of heating the alkali activated carbon to reduce the total amount of acidic functional groups and controlling the zeta potential within the above range.
If the heating temperature is raised, the acidic functional groups can be removed from the alkali-activated carbon, and the zeta potential can be induced within the above range. However, if the heating temperature is too high, the zeta potential may fall outside the above range or the pore structure may change. Change.
The temperature during the heat treatment is preferably 800°C to 1500°C, more preferably 900°C to 1400°C, even more preferably 1000°C to 1300°C.
The heating rate to the above heating temperature is preferably 1°C/min to 20°C/min, more preferably 5°C/min to 15°C/min, and even more preferably 10°C/min to 15°C/min.
The heating time at the above heating temperature is preferably 30 minutes to 10 hours, more preferably 1 hour to 5 hours, and even more preferably 2 hours to 4 hours.

粉砕処理
本発明のアルカリ賦活炭は必要に応じてミル等の粉砕機を用いて所望の粒度になるように粉砕処理してもよい。なお、粉砕は製造過程の任意の段階で行ってもよいし、予め粉砕処理された原料を用いてもよい。 Grinding Treatment The alkali-activated carbon of the present invention may be pulverized to a desired particle size using a pulverizer such as a mill, if necessary. Note that pulverization may be performed at any stage of the manufacturing process, or raw materials that have been previously pulverized may be used.

成形工程
本発明のアルカリ賦活炭は必要に応じて各種用途に応じた形状に成形してもよい。成形方法としては特に限定されず、各種公知の成形方法を使用して所望のサイズ、形状に成形すればよい。また成形時に他の材料、例えばバインダーなどの任意の添加剤と混合してもよい。 Molding Step The alkali-activated carbon of the present invention may be molded into shapes suitable for various uses, if necessary. The molding method is not particularly limited, and may be molded into a desired size and shape using various known molding methods. It may also be mixed with other materials such as binders and other optional additives during molding.

上記物性が得られるように各製造条件を適切に調整し得られた本発明のアルカリ賦活炭は、液体中のＰＦＡＳ、特にＰＦＯＳ、ＰＦＯＡに対して優れた除去効果を発揮する。 The alkali-activated carbon of the present invention, which is obtained by appropriately adjusting each production condition so as to obtain the above-mentioned physical properties, exhibits an excellent removal effect on PFAS, particularly PFOS, and PFOA in liquids.

以下、実施例を挙げて本発明をより具体的に説明するが、本発明はもとより下記実施例によって制限を受けるものではなく、前・後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも勿論可能であり、それらはいずれも本発明の技術的範囲に包含される。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the Examples below, and modifications may be made as appropriate within the scope of the spirit of the preceding and following. Of course, other implementations are also possible, and all of them are included within the technical scope of the present invention.

実施例１
石炭ピッチ系炭素繊維１．０重量部に、賦活剤として質量比（[賦活剤のアルカリ成分の質量]／[賦活原料の質量]：以下、ＫＯＨ／Ｃ比という）が３．０となるように市販のアルカリ賦活剤（濃度４８．５％水酸化カリウム水溶液）を添加・混合した後、窒素雰囲気下、８００℃まで昇温し、該温度で３．７５時間保持してアルカリ賦活炭を得た。
得られたアルカリ賦活炭は、ろ液のｐＨが７．０以下になるまで６０℃の温水で洗浄を繰り返した。
次いで５．２５ｗｔ％塩酸水溶液中で１時間酸洗浄を行い、吸引ろ過を行った。
ろ過後の活性炭を更に６０℃の温水でろ液のｐＨが６．５以上になるまで温水洗浄を繰り返し行い、洗浄品を得た。
得られた洗浄品を１１５℃に設定した乾燥機にて２４時間の乾燥処理を行った。
乾燥後の活性炭を昇降炉(東洋アドバンテック社製)に装入し、窒素雰囲気中１１５０℃まで１０／分で昇温し、該温度で２時間保持して実施例１の繊維状活性炭を得た。 Example 1
1.0 parts by weight of coal pitch-based carbon fiber was added as an activator so that the mass ratio ([mass of alkaline component of activator]/[mass of activation raw material]: hereinafter referred to as KOH/C ratio) was 3.0. After adding and mixing a commercially available alkali activator (concentration 48.5% potassium hydroxide aqueous solution) to the mixture, the temperature was raised to 800°C under a nitrogen atmosphere and maintained at this temperature for 3.75 hours to obtain alkali activated carbon. Ta.
The obtained alkali activated carbon was repeatedly washed with 60°C warm water until the pH of the filtrate became 7.0 or less.
Next, acid washing was performed in a 5.25 wt % aqueous hydrochloric acid solution for 1 hour, and suction filtration was performed.
The activated carbon after filtration was further washed repeatedly with warm water at 60° C. until the pH of the filtrate became 6.5 or higher to obtain a washed product.
The obtained washed product was dried for 24 hours in a dryer set at 115°C.
The activated carbon after drying was charged into a lifting furnace (manufactured by Toyo Advantech Co., Ltd.), and the temperature was raised to 1150°C at a rate of 10/min in a nitrogen atmosphere, and the temperature was maintained for 2 hours to obtain the fibrous activated carbon of Example 1. .

比較例１
市販のアルカリ賦活活性炭素繊維（ＭＣエバテック社製ＭＳＦ－Ａ３０Ｍ）を比較例１の繊維状活性炭とした。 Comparative example 1
A commercially available alkali-activated carbon fiber (MSF-A30M manufactured by MC Evertech) was used as the fibrous activated carbon of Comparative Example 1.

比較例２
市販のヤシガラ水蒸気賦活活性炭（ＭＣエバテック社製Ｗ１０－３０）を比較例２の粒状活性炭とした。 Comparative example 2
Commercially available coconut shell steam-activated activated carbon (W10-30 manufactured by MC Evertech) was used as the granular activated carbon of Comparative Example 2.

比較例３
市販の石炭系水蒸気賦活活性炭（ＭＣエバテック社製Ｃ－６）を比較例３の粒状活性炭とした。 Comparative example 3
Commercially available coal-based steam-activated activated carbon (C-6 manufactured by MC Evertech) was used as the granular activated carbon of Comparative Example 3.

なお、粒状炭である比較例２、３は、粒度の影響を小さくするため予め粒度調整を行ってから特性を調べた。具体的には、メノウ乳鉢を用いて活性炭を粉砕した後に、篩目が５３μｍおよび１２５μｍの篩で分級することで平均粒子径（Ｄ５０）が１００～１５０μｍ程度となるように粒度調整を行った。 In addition, in Comparative Examples 2 and 3, which are granular charcoal, the characteristics were examined after particle size was adjusted in advance in order to reduce the influence of particle size. Specifically, after pulverizing activated carbon using an agate mortar, the particle size was adjusted so that the average particle diameter (D50) was about 100 to 150 μm by classifying it with sieves with mesh sizes of 53 μm and 125 μm.

粒子径
各試料の粒子径はレーザー回折式粒度分布測定装置（島津製作所社製、ＳＡＬＤ（登録商標）－２０００）を用いて測定し、得られた粒度分布の測定結果から体積基準の累積頻度曲線を求め、累積頻度５０％における平均粒子径Ｄ５０を算出した。 Particle size The particle size of each sample was measured using a laser diffraction particle size distribution analyzer (Shimadzu Corporation, SALD (registered trademark)-2000), and the volume-based cumulative frequency curve was calculated from the obtained particle size distribution measurement results. was determined, and the average particle diameter D50 at a cumulative frequency of 50% was calculated.

比表面積
試料（０．２ｇ）を２５０℃にて真空乾燥させた後、窒素吸着装置(マイクロメリティックス社製ＡＳＡＰ－２４２０）を用いて液体窒素雰囲気下（－１９６℃）における窒素ガスの吸着量を測定して窒素吸着等温線を求め、ＢＥＴ法にて比表面積（ｍ^２／ｇ）を求めた。 Specific surface area After vacuum drying the sample (0.2 g) at 250°C, adsorption of nitrogen gas in a liquid nitrogen atmosphere (-196°C) using a nitrogen adsorption device (ASAP-2420 manufactured by Micromeritics) The amount was measured to obtain a nitrogen adsorption isotherm, and the specific surface area (m ² /g) was determined by the BET method.

全細孔容積
窒素吸着等温線から相対圧（Ｐ／Ｐ０）＝０．９３における窒素吸着量から全細孔容積（ｍＬ／ｇ）を算出した。
ミクロ孔容積およびメソ孔容積:
得られた窒素吸着等温線からＢＪＨ法により解析を行い、２～３０ｎｍのメソ孔容積を求めた。また、ミクロ孔容積を以下の式により算出した。
ミクロ孔容積（ｍＬ／ｇ）＝全細孔容積（ｍＬ／ｇ）－［ＢＪＨ法により解析した２～３０ｎｍのメソ孔容積（ｍＬ／ｇ）］
上記値を用いて下記式よりミクロ孔容積とメソ孔容積の差を求めた。
ミクロ孔容積（ｍＬ／ｇ）－メソ孔容積（ｍＬ／ｇ）
また下記式よりミクロ孔容積の割合とメソ孔容積の割合を求めた。
ミクロ孔容積の割合＝ミクロ孔容積／（ミクロ孔容積＋メソ孔容積）×１００
メソ孔容積の割合＝メソ孔容積／（ミクロ孔容積＋メソ孔容積）×１００
１ｎｍ以下の細孔容積は以下の式により算出した。
１ｎｍ以下の細孔容積（ｍＬ／ｇ）＝全細孔容積（ｍＬ／ｇ）－［ＢＪＨ法で解析した１～３０ｎｍの細孔容積（ｍＬ／ｇ）］ Total pore volume The total pore volume (mL/g) was calculated from the nitrogen adsorption amount at relative pressure (P/P0) = 0.93 from the nitrogen adsorption isotherm.
Micropore volume and mesopore volume:
The obtained nitrogen adsorption isotherm was analyzed by the BJH method to determine the mesopore volume of 2 to 30 nm. Further, the micropore volume was calculated using the following formula.
Micropore volume (mL/g) = total pore volume (mL/g) - [2-30 nm mesopore volume (mL/g) analyzed by BJH method]
Using the above values, the difference between the micropore volume and mesopore volume was determined from the following formula.
Micropore volume (mL/g) - Mesopore volume (mL/g)
Further, the ratio of micropore volume and the ratio of mesopore volume were determined from the following formula.
Ratio of micropore volume = micropore volume / (micropore volume + mesopore volume) × 100
Mesopore volume ratio = mesopore volume / (micropore volume + mesopore volume) × 100
The pore volume of 1 nm or less was calculated using the following formula.
Pore volume of 1 nm or less (mL/g) = total pore volume (mL/g) - [pore volume of 1 to 30 nm analyzed by BJH method (mL/g)]

平均細孔径（４Ｖ／Ａ）
活性炭の細孔をシリンダー状と仮定し、下記式に基づいて平均細孔径を算出した。
平均細孔径（ｎｍ）＝４×全細孔容積（ｍＬ／ｇ）／比表面積（ｍ^２／ｇ）×１０００ Average pore diameter (4V/A)
Assuming that the pores of activated carbon are cylindrical, the average pore diameter was calculated based on the following formula.
Average pore diameter (nm) = 4 x total pore volume (mL/g) / specific surface area (m ² /g) x 1000

全酸性官能基量評価
全酸性官能基量は、Ｂｏｅｈｍ法（文献「Ｈ．Ｐ．Ｂｏｅｈｍ，Ａｄｚａｎ．Ｃａｔａｌ，１６，１７９（１９６６）」）に従って求めた。具体的には活性炭２ｇにナトリウムエトキシド水溶液（０．１ｍｏｌ／Ｌ）を５０ｍＬ加え、２時間、５００ｒｐｍで撹拌した後、２４時間放置した。２４時間経過後、さらに３０分間撹拌を行いろ過分離した。得られたろ液２５ｍＬに対して０．１ｍｏｌ／Ｌの塩酸を滴下し、ｐＨ４．０になるときの塩酸滴定量を測定した。また、ブランクテストとして、前記ナトリウムエトキシド水溶液（０．１ｍｏｌ／Ｌ）２５ｍＬに対して０．１ｍｏｌ／Ｌの塩酸を滴下し、ｐＨ４．０になるときの塩酸滴定量を測定した。そして、下記式により全酸性官能基量（ｍｅｑ／ｇ）を算出した。
全酸性官能基量（ｍｅｑ／ｇ）＝（ａ－ｂ）×０．１／（Ｓ×２５／５０）
ａ：ブランクテストにおける塩酸滴定量（ｍＬ）
ｂ：試料を反応させたときの塩酸滴定量（ｍＬ）
Ｓ：試料重量（ｇ） Evaluation of Total Acid Functional Group Amount The total acid functional group amount was determined according to the Boehm method (document "H.P. Boehm, Adzan. Catal, 16, 179 (1966)"). Specifically, 50 mL of sodium ethoxide aqueous solution (0.1 mol/L) was added to 2 g of activated carbon, stirred at 500 rpm for 2 hours, and then left for 24 hours. After 24 hours, the mixture was stirred for an additional 30 minutes and then filtered and separated. 0.1 mol/L hydrochloric acid was added dropwise to 25 mL of the obtained filtrate, and the titration amount of hydrochloric acid when the pH reached 4.0 was measured. Further, as a blank test, 0.1 mol/L hydrochloric acid was added dropwise to 25 mL of the sodium ethoxide aqueous solution (0.1 mol/L), and the titer of hydrochloric acid when the pH reached 4.0 was measured. Then, the total amount of acidic functional groups (meq/g) was calculated using the following formula.
Total acidic functional group amount (meq/g) = (ab) x 0.1/(S x 25/50)
a: Hydrochloric acid titer in blank test (mL)
b: Hydrochloric acid titer (mL) when reacting the sample
S: Sample weight (g)

比表面積当たりの全酸性官能基量
比表面積当たりの全酸性官能基量は以下の式により算出した。
比表面積当たりの全酸性官能基量（μｅｑ／ｍ^２）＝全酸性官能基量（ｍｅｑ／ｇ）／比表面積（ｍ^２／ｇ）×１０００（単位調整） Total amount of acidic functional groups per specific surface area The total amount of acidic functional groups per specific surface area was calculated using the following formula.
Total amount of acidic functional groups per specific surface area (μeq/m ² ) = total amount of acidic functional groups (meq/g)/specific surface area (m ² /g) x 1000 (unit adjustment)

酸素含有量
１２０℃で２時間乾燥した試料を、Ｅｌｅｍｅｎｔａｒ社製ｖａｒｉｏＥＬｃｕｂｅを使用し、基準物質に安息香酸を用いて活性炭中の酸素含有量を測定した。 Oxygen Content The sample dried at 120° C. for 2 hours was used to measure the oxygen content in the activated carbon using a vario EL cube manufactured by Elementar and benzoic acid as a reference substance.

ゼータ電位
純水２５ｍＬに対して、ディスクミルを用いて平均粒子径が５～１０μｍ程度となるように粉砕した試料を５ｍｇ添加し、撹拌することで分散液を調製した。この分散液をゼータ電位測定装置ＺｅｔａｓｉｚｅｒＮａｎｏＺ（ＭａｌｖｅｒｎＰａｎａｌｙｔｉｃａｌ社製、型番ＺＥＮ２６００）を使用し、測定した。ゼータ電位は、所定のキャピラリーセルに入れた分散液中の粒子の電気泳動移動度を測定し、得られた電気泳動移動度から以下の式を用いることで算出した。
Ｕｅ＝２εｚｆ（ｋａ）／３η
ｚ：ゼータ電位
Ｕｅ：電気泳動移動度
ｆ（ｋａ）：ヘンリー関数（水系では１．５）
ε：誘電率
η：粘度 Zeta potential A dispersion liquid was prepared by adding 5 mg of a sample ground to 25 mL of pure water using a disk mill so that the average particle size was about 5 to 10 μm, and stirring. This dispersion liquid was measured using a zeta potential measuring device Zetasizer Nano Z (manufactured by Malvern Panalytical, model number ZEN2600). The zeta potential was calculated by measuring the electrophoretic mobility of particles in a dispersion liquid placed in a predetermined capillary cell, and using the following formula from the obtained electrophoretic mobility.
Ue = 2εzf(ka)/3η
z: Zeta potential Ue: Electrophoretic mobility f(ka): Henry function (1.5 in aqueous systems)
ε: Dielectric constant η: Viscosity

ＰＦＯＳ、ＰＦＯＡ平衡吸着試験
ＰＦＯＳ、ＰＦＯＡ試験溶液の調製
ＰＦＯＳ（富士フィルム和光純薬社製、純度１００％）またはＰＦＯＡ（富士フィルム和光純薬社製、純度１００％）試薬１８．０ｍｇを５０ｍＬメスフラスコに量り取り、メタノール（関東化学社製、高速液体クロマトグラフィー用）を加えて溶解させた。次いで、この溶液を１００ｍＬメスフラスコに５．５ｍＬまたは８．２５ｍＬ分取し、標線までメタノールを加えて希釈した。希釈後の溶液１ｍＬまたは３０ｍＬを３Ｌメスフラスコに入れ、超純水でメスアップすることで、ＰＦＯＳまたはＰＦＯＡ試験水を調製した。 PFOS, PFOA equilibrium adsorption test Preparation of PFOS, PFOA test solution 18.0 mg of PFOS (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., purity 100%) or PFOA (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., purity 100%) reagent was added to a 50 mL volumetric flask. methanol (manufactured by Kanto Kagaku Co., Ltd., for high performance liquid chromatography) was added to dissolve it. Next, 5.5 mL or 8.25 mL of this solution was dispensed into a 100 mL volumetric flask, and methanol was added to dilute it to the marked line. PFOS or PFOA test water was prepared by putting 1 mL or 30 mL of the diluted solution into a 3 L volumetric flask and making up the volume with ultrapure water.

ＰＦＯＳ、ＰＦＯＡ平衡吸着試験
１０５℃で１５時間乾燥した活性炭を２００ｍＬガラス製三角フラスコに所定量投入し、前記で調製したＰＦＯＳまたはＰＦＯＡ試験溶液を１００ｍＬ加えた後、２５℃に設定した恒温槽内にて振とう速度２００ｒｐｍで２４時間振とうさせた。その後、０．４５μｍのメンブレンフィルターで濾過し、固相カラム（ジーエルサイエンス社製ＰＬＳ－３）を用いて固相抽出したものを測定試料とした。なお、測定は「上水試験方法III 有機物編III－２有機物類３１．３固相抽出－液体クロマトグラフ質量分析法２」に記載の方法で行い、分析装置には高速液体クロマトグラフ質量分析計（ＡｇｉｌｅｎｔＴｅｃｈｎｏｌｏｇｉｅｓ社製１２６０ＩｎｆｉｎｉｔｙＬＣ／ＭＳ）を使用した。ＬＣ／ＭＳ測定結果から得られたＰＦＯＳまたはＰＦＯＡ残留濃度と活性炭重量当たりの吸着量（ｍｇ／ｇ－活性炭）の関係から吸着等温線を作成し、残留濃度０．０７μｇ／Ｌにおける吸着量をＦｒｅｕｎｄｌｉｃｈ式により求めた。 PFOS, PFOA equilibrium adsorption test A predetermined amount of activated carbon that had been dried at 105°C for 15 hours was put into a 200mL glass Erlenmeyer flask, and after adding 100mL of the PFOS or PFOA test solution prepared above, it was placed in a constant temperature bath set at 25°C. The mixture was shaken for 24 hours at a shaking speed of 200 rpm. Thereafter, the sample was filtered with a 0.45 μm membrane filter and subjected to solid phase extraction using a solid phase column (PLS-3, manufactured by GL Sciences), which was used as a measurement sample. The measurement was performed using the method described in "Water Test Method III Organic Matter Part III-2 Organic Matter 31.3 Solid Phase Extraction - Liquid Chromatography Mass Spectrometry 2", and the analysis equipment was a high performance liquid chromatograph mass spectrometer. (1260 Infinity LC/MS manufactured by Agilent Technologies) was used. An adsorption isotherm was created from the relationship between the PFOS or PFOA residual concentration obtained from the LC/MS measurement results and the adsorption amount per activated carbon weight (mg/g-activated carbon), and the adsorption amount at a residual concentration of 0.07 μg/L was calculated using the Freundlich method. It was calculated using the formula.

ＰＦＯＡ通水性能評価
ＰＦＯＡ試験溶液の調製
２ＬメスフラスコにＰＦＯＡ（富士フィルム和光純薬社製、純度１００％）試薬を３０１．８ｍｇ投入し、メタノール１ｍＬを加えて溶解させた後に超純水でメスアップすることで濃度１５０ｍｇ／ＬのＰＦＯＡ溶液を調製した。この溶液を２Ｌのポリ瓶に移し替え、通水試験装置内で初濃度が８００μｇ／Ｌとなるように純水と混合し、これを試験溶液とした。 PFOA water flow performance evaluation Preparation of PFOA test solution Pour 301.8 mg of PFOA (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., purity 100%) reagent into a 2L volumetric flask, add 1 mL of methanol to dissolve, and then evaporate with ultrapure water. By increasing the concentration, a PFOA solution with a concentration of 150 mg/L was prepared. This solution was transferred to a 2L polyethylene bottle and mixed with pure water in a water flow testing device so that the initial concentration was 800 μg/L, and this was used as a test solution.

ＰＦＯＡ通水性能評価試験
１０５℃で１５時間乾燥した活性炭を内径１５．８ｍｍ、高さ１００ｍｍの樹脂製カラムに活性炭層厚が実施例１は１０ｍｍ、比較例２、３については２０ｍｍとなるように充填した。作製した活性炭カラムを通水試験装置に取り付け、ＳＶ＝２５００ｈ^－１（実施例１は流量約８０ｍＬ／分、比較例２，３は約１６０ｍＬ／分）となるように試験溶液を通水し、カラム出口側より活性炭吸着後の試験溶液を適宜サンプリングした。また、活性炭カラムへの通水開始前後においてカラムを通過前の試験溶液をカラム入口側よりサンプリングし、試験溶液の初期濃度の算出に用いた。サンプリングした試験溶液は、高速液体クロマトグラフ質量分析計（ＡｇｉｌｅｎｔＴｅｃｈｎｏｌｏｇｉｅｓ社製１２６０ＩｎｆｉｎｉｔｙＬＣ／ＭＳ）を用いて分析を行い、得られた試験溶液の初期濃度と活性炭出口側からサンプリングした溶液中の残留濃度から除去率を算出し、求めた除去率と活性炭重量当たりの通水量から破過曲線を得た。また、経時時間毎でサンプリングした活性炭吸着後の残留濃度と活性炭へ吸着したＰＦＯＡの総量（ｍｇ／ｇ―活性炭）の関係から残留濃度０．０７μｇ／Ｌにおける活性炭重量当たりのＰＦＯＡ累積吸着量（ｍｇ／ｇ－活性炭）を算出し、求めたＰＦＯＡ吸着量（ｍｇ／ｇ－活性炭）を試験溶液の初期濃度（μｇ／Ｌ）で除することで残留濃度０．０７μｇ／Ｌに到達時のＰＦＯＡ通水可能量（Ｌ／ｇ－活性炭）を算出した。 PFOA water flow performance evaluation test Activated carbon dried at 105°C for 15 hours was placed in a resin column with an inner diameter of 15.8 mm and a height of 100 mm so that the activated carbon layer thickness was 10 mm for Example 1 and 20 mm for Comparative Examples 2 and 3. Filled. The prepared activated carbon column was attached to a water flow test device, and the test solution was passed through it so that SV = 2500 h ^-1 (flow rate of about 80 mL/min for Example 1, about 160 mL/min for Comparative Examples 2 and 3). The test solution after activated carbon adsorption was appropriately sampled from the column outlet side. In addition, before and after the start of water flow to the activated carbon column, the test solution before passing through the column was sampled from the column inlet side and used to calculate the initial concentration of the test solution. The sampled test solution was analyzed using a high-performance liquid chromatography mass spectrometer (Agilent Technologies 1260 Infinity LC/MS) to determine the initial concentration of the obtained test solution and the residual concentration in the solution sampled from the activated carbon outlet side. The removal rate was calculated from the concentration, and a breakthrough curve was obtained from the calculated removal rate and the amount of water passed per weight of activated carbon. In addition, from the relationship between the residual concentration after activated carbon adsorption sampled over time and the total amount of PFOA adsorbed on activated carbon (mg/g-activated carbon), the cumulative amount of PFOA adsorbed per activated carbon weight at a residual concentration of 0.07 μg/L (mg /g-activated carbon) and divide the determined PFOA adsorption amount (mg/g-activated carbon) by the initial concentration of the test solution (μg/L) to calculate the PFOA value when the residual concentration reaches 0.07μg/L. The available amount of water (L/g-activated carbon) was calculated.

遊離残留塩素通水性能評価
試験溶液の調製
市販の活性炭カートリッジフィルター（アズワン社製、Ｔｙｐｅ－２）を用いて濾過した水道水２８０Ｌを容量３００Ｌのタンクに注水し、有効塩素濃度が２ｍｇ／Ｌとなるように次亜塩素酸ナトリウム溶液（キシダ化学社製、有効塩素濃度１２重量％）４．７ｍＬをピペッターを用いて投入した。その後、ケミカルポンプにより撹拌することで試験溶液を調製した。 Free residual chlorine water flow performance evaluation Preparation of test solution 280L of tap water filtered using a commercially available activated carbon cartridge filter (manufactured by As One Corporation, Type-2) was poured into a tank with a capacity of 300L, and the effective chlorine concentration was 2mg/L. Using a pipettor, 4.7 mL of sodium hypochlorite solution (manufactured by Kishida Chemical Co., Ltd., effective chlorine concentration: 12% by weight) was introduced into the solution. Thereafter, a test solution was prepared by stirring with a chemical pump.

遊離残留塩素通水性能評価試験
家庭用浄水器試験方法（ＪＩＳＳ３２０１）を参考に評価試験を行った。１１５℃で２時間乾燥した活性炭を内径１９ｍｍ、高さ１００ｍｍの樹脂製カラムに活性炭層厚が１０ｍｍとなるように充填した。作製した活性炭カラムを通水試験装置に取り付け、ＳＶ＝６０００ｈ－１（流量約２８０ｍＬ／分）となるように試験溶液を通水し、カラム通過前後の試験溶液１０ｍＬをバイアル瓶に適宜サンプリングした。遊離残留塩素濃度（ｍｇ／Ｌ）の測定は、サンプリングした試験溶液にＤＰＤ試薬（関東化学社製ラピッドＤＰＤ試薬（分包））を加えて２０秒ほど振とうさせ、残留塩素計（ＨＡＣＨ社製）にて濃度測定を行った。測定した濃度から、活性炭重量あたりの通水量（Ｌ／ｇ）における除去率を算出し、除去率８０％の時の累積通水量を求めた。 Free residual chlorine water flow performance evaluation test An evaluation test was conducted with reference to the domestic water purifier test method (JIS S 3201). Activated carbon dried at 115° C. for 2 hours was packed into a resin column with an inner diameter of 19 mm and a height of 100 mm so that the activated carbon layer thickness was 10 mm. The prepared activated carbon column was attached to a water flow test device, and the test solution was passed through it at SV = 6000 h-1 (flow rate of about 280 mL/min), and 10 mL of the test solution before and after passing through the column was appropriately sampled into a vial bottle. To measure the free residual chlorine concentration (mg/L), add a DPD reagent (Rapid DPD reagent (packaged) manufactured by Kanto Kagaku Co., Ltd.) to the sampled test solution, shake it for about 20 seconds, and use a residual chlorine meter (manufactured by HACH Co., Ltd.). ), the concentration was measured. From the measured concentration, the removal rate in the amount of water passed per weight of activated carbon (L/g) was calculated, and the cumulative amount of water passed when the removal rate was 80% was determined.

クロラミン通水性能評価
試験溶液の調製
市販の活性炭カートリッジフィルター（アズワン社製、Ｔｙｐｅ－２）を用いて濾過した水道水２８０Ｌを容量３００Ｌのタンクに注水し、クロラミン濃度が３．０±０．３ｍｇ／Ｌになるように２８％アンモニア水（キシダ化学社製）を３．３ｍｌおよび１２％次亜塩素酸ナトリウム溶液（キシダ化学社製）を７．２６ｍｌ加えた後、ハンディポンプで約３０分間攪拌することで調製した。 Chloramine water flow performance evaluation Preparation of test solution 280 L of tap water filtered using a commercially available activated carbon cartridge filter (manufactured by As One Corporation, Type-2) was poured into a tank with a capacity of 300 L, and the chloramine concentration was 3.0 ± 0.3 mg. After adding 3.3 ml of 28% ammonia water (manufactured by Kishida Chemical Co., Ltd.) and 7.26 ml of 12% sodium hypochlorite solution (manufactured by Kishida Chemical Co., Ltd.) so that the solution was 28% aqueous ammonia (manufactured by Kishida Chemical Co., Ltd.) so as to make a total of It was prepared by

クロラミン通水性能評価試験
米国における浄水器規格（ＮＳＦ／ＡＮＳＩ４２）を参考に評価試験を行った。１１５℃で２時間乾燥した活性炭を内径１９ｍｍ、高さ１００ｍｍの樹脂製カラムに活性炭層厚が１５ｍｍとなるように充填した。作製した活性炭カラムを通水試験装置に取り付け、ＳＶ＝５００ｈ^－１（流量約３５ｍＬ／分）となるように試験溶液を通水し、カラム通過前後の試験溶液１０ｍＬを１０ｍＬ比色管に適宜サンプリングした。１０ｍＬ比色管に採取した試験水にリン酸緩衝液を０．５ｍＬ加えて均一に混合した後、ＤＰＤ試薬（関東化学社製）を投入して約２０秒間振盪させ、塩素濃度計（ＨＡＣＨ社製）で残留遊離塩素濃度を測定した。その後、測定した試験水にヨウ化カリウム（キシダ化学社製）を０．１ｇ加えて発色させ、２分間静置した後、塩素濃度計（ＨＡＣＨ社製）で残留塩素濃度を測定した。測定した残留遊離塩素濃度と残留塩素濃度から、下記式を用いて残留クロラミン濃度を算出した。
残留クロラミン濃度（ｍｇ／Ｌ）＝残留塩素濃度（ｍｇ／Ｌ）－残留遊離塩素濃度（ｍｇ／Ｌ）
測定した濃度から活性炭重量あたりの通水量（Ｌ／ｇ）における除去率を算出し、活性炭通過後の試験水における残留クロラミン濃度が０．５ｐｐｍ（除去率約８３％）に達した際の累積通水量を求めた。 Chloramine water flow performance evaluation test An evaluation test was conducted with reference to the water purifier standard (NSF/ANSI42) in the United States. Activated carbon dried at 115° C. for 2 hours was packed into a resin column with an inner diameter of 19 mm and a height of 100 mm so that the activated carbon layer thickness was 15 mm. Attach the prepared activated carbon column to a water flow test device, pass water through the test solution so that SV = 500 h ^-1 (flow rate approximately 35 mL/min), and sample 10 mL of the test solution before and after passing through the column into a 10 mL colorimetric tube as appropriate. did. After adding 0.5 mL of phosphate buffer to the test water collected in a 10 mL colorimetric tube and mixing uniformly, DPD reagent (manufactured by Kanto Kagaku Co., Ltd.) was added and shaken for about 20 seconds. The residual free chlorine concentration was measured using Thereafter, 0.1 g of potassium iodide (manufactured by Kishida Chemical Co., Ltd.) was added to the measured test water to develop color, and after standing for 2 minutes, the residual chlorine concentration was measured with a chlorine concentration meter (manufactured by HACH Co., Ltd.). The residual chloramine concentration was calculated from the measured residual free chlorine concentration and residual chlorine concentration using the following formula.
Residual chloramine concentration (mg/L) = Residual chlorine concentration (mg/L) - Residual free chlorine concentration (mg/L)
From the measured concentration, calculate the removal rate based on the amount of water passed per activated carbon weight (L/g), and calculate the cumulative removal rate when the residual chloramine concentration in the test water after passing through the activated carbon reaches 0.5 ppm (removal rate approximately 83%). The amount of water was determined.

クロロホルム吸着性能評価
クロロホルム（ＣＨＣｌ_３）０．５ｇをメタノール５０ｍｌに希釈し、更にメタノールで１０倍希釈したものを原液とし、クロロホルム原液１ｍＬを純水で１Ｌに希釈して１ｍｇ／Ｌのクロロホルム溶液を作製した。１００ｍＬ三角フラスコを５本（三角フラスコ１～５）用意し、各三角フラスコに攪拌子を入れると共に、活性炭を０．０１３ｇ（三角フラスコ１）、０．０２６ｇ（三角フラスコ２）、０．０６４ｇ（三角フラスコ３）、０．１３ｇ（三角フラスコ４）、０．２６ｇ（（三角フラスコ５）入れ、１ｍｇ／Ｌのクロロホルム溶液で満水にし、テフロン（登録商標）グリスを塗布したガラス栓で密栓し、クリップで固定した。この時、注水した溶液の重量を測定した。その後、三角フラスコを２０℃恒温庫内で、マグネチックスターラーを用いて１４時間攪拌した。攪拌後、活性炭をシリンジフィルターでろ別し、ろ液をスクリュー瓶に満水状態で１０℃恒温庫内にて測定直前まで冷蔵保存した。クロロホルム濃度測定はＨＳ－ＧＣ／ＭＳ（ＨＳ：パーキンエルマー社製ＴｕｒｂｏＭａｔｒｉｘＨＳ、ＧＣ／ＭＳ：島津製作所社製ＱＰ２０１０）を用いた。定量したろ液中の濃度から、活性炭重量あたりの吸着量（ｍｇ／ｇ）を算出することで吸着等温線を作成し、クロロホルム残留濃度０．０６ｍｇ／Ｌのときの平衡吸着量を求めた。 Chloroform adsorption performance evaluation: Dilute 0.5 g of chloroform (CHCl ₃ ) in 50 ml of methanol and further dilute it 10 times with methanol to make a stock solution. Dilute 1 mL of chloroform stock solution to 1 L with pure water to make a 1 mg/L chloroform solution. Created. Prepare five 100 mL Erlenmeyer flasks (Erlenmeyer flasks 1 to 5), put a stirrer in each Erlenmeyer flask, and add activated carbon of 0.013g (Erlenmeyer flask 1), 0.026g (Erlenmeyer flask 2), and 0.064g (Erlenmeyer flask 2). Erlenmeyer flask 3), 0.13 g (Erlenmeyer flask 4), 0.26 g (Erlenmeyer flask 5), filled with 1 mg/L chloroform solution, and sealed with a glass stopper coated with Teflon (registered trademark) grease. It was fixed with a clip. At this time, the weight of the water-poured solution was measured. Then, the Erlenmeyer flask was stirred for 14 hours using a magnetic stirrer in a constant temperature chamber at 20°C. After stirring, activated carbon was filtered out using a syringe filter. The filtrate was kept refrigerated in a screw bottle filled with water in a thermostatic chamber at 10°C until immediately before measurement.Chloroform concentration was measured using HS-GC/MS (HS: TurboMatrixHS manufactured by PerkinElmer, GC/MS: manufactured by Shimadzu Corporation). QP2010) was used.From the determined concentration in the filtrate, an adsorption isotherm was created by calculating the adsorption amount (mg/g) per activated carbon weight, and the equilibrium value was calculated when the residual chloroform concentration was 0.06 mg/L. The amount of adsorption was determined.

実施例１は本発明の好適な活性炭であり、アルカリ賦活後に加熱処理を行った例である。
比較例１はアルカリ賦活炭に加熱処理を行わなかった例であり、比表面積当たりの全酸性官能基量が多く、またゼータ電位も満足しなかった。
比較例２は水蒸気賦活炭に加熱処理を行わなかった例であり、比表面積が小さく、またミクロ孔容積とメソ孔容積のバランス（差、割合）が悪かった。
比較例３は水蒸気賦活炭に加熱処理を行わなかった例であり、比表面積が小さく、また比表面積当たりの全酸性官能基量、およびミクロ孔容積とメソ孔容積のバランス（差）が悪かった。 Example 1 is a preferred activated carbon of the present invention, and is an example in which heat treatment was performed after alkali activation.
Comparative Example 1 is an example in which the alkali-activated carbon was not heat-treated, and the total amount of acidic functional groups per specific surface area was large, and the zeta potential was also unsatisfactory.
Comparative Example 2 is an example in which steam-activated carbon was not heat-treated, and the specific surface area was small, and the balance (difference, ratio) between micropore volume and mesopore volume was poor.
Comparative Example 3 is an example in which steam-activated carbon was not heat-treated, and the specific surface area was small, and the total amount of acidic functional groups per specific surface area and the balance (difference) between micropore volume and mesopore volume were poor. .

図１～３に示すように本発明を満足する実施例１の活性炭はＰＦＯＳ平衡吸着量、ＰＦＯＡ平衡吸着量、ＰＦＯＡ累積通水量の各試験において、比較例１～３の活性炭よりも優れた吸着性能を示し、水中からＰＦＯＳ、ＰＦＯＡの除去率を高めることができた。 As shown in Figures 1 to 3, the activated carbon of Example 1, which satisfies the present invention, exhibited better adsorption than the activated carbon of Comparative Examples 1 to 3 in each test of PFOS equilibrium adsorption amount, PFOA equilibrium adsorption amount, and PFOA cumulative water flow rate. It showed good performance and was able to increase the removal rate of PFOS and PFOA from water.

また図４、５に示す様に実施例１の活性炭は遊離残留塩素（図４）、クロラミン（図５）に対しても比較例２、３の活性炭よりも優れた除去効果が得られた。したがって本発明の活性炭はＰＦＯＳ、ＰＦＯＡなどのＰＦＡＳだけでなく、遊離残留塩素や結合塩素などの総残留塩素に対する除去効果も有する。 Furthermore, as shown in FIGS. 4 and 5, the activated carbon of Example 1 had a better removal effect on free residual chlorine (FIG. 4) and chloramine (FIG. 5) than the activated carbon of Comparative Examples 2 and 3. Therefore, the activated carbon of the present invention has the effect of removing not only PFAS such as PFOS and PFOA, but also total residual chlorine such as free residual chlorine and combined chlorine.

一方、図６に示す様に、実施例１の活性炭は比較例２、３の活性炭と比べてクロロホルムに対する除去効果が低かった。
図１～３、図６に示す様に本発明の活性炭はクロロホルムの吸着・除去効果が低く、一方でＰＦＯＳ、ＰＦＯＡに対する吸着・除去効果に優れていた。 On the other hand, as shown in FIG. 6, the activated carbon of Example 1 had a lower removal effect on chloroform than the activated carbon of Comparative Examples 2 and 3.
As shown in FIGS. 1 to 3 and 6, the activated carbon of the present invention had a low adsorption/removal effect on chloroform, but an excellent adsorption/removal effect on PFOS and PFOA.

Claims

Specific surface area is 2020 to 4000 m ² /g,
The total amount of acidic functional groups per specific surface area is 0.20 μeq/m ² or less,
Zeta potential is -40mV or more,
The volume of micropores with a pore diameter of 1 nm or less is less than 0.3 mL/g,
Equilibrium adsorption amount of chloroform is 2.5 mg/g or less,
A fibrous activated carbon for removing PFAS in water.

The difference between the volume of micropores with a pore diameter of 2 nm or less and the volume of mesopores with a pore diameter of 2 to 30 nm is 0.45 mL/g or less,
The fibrous activated carbon according to claim 1.

The fibrous activated carbon according to claim 1, wherein the total amount of acidic functional groups is 0.5 meq/g or less and the oxygen content is 3.0 wt% or less.

The fibrous activated carbon according to claim 1, wherein the ratio of micropore volume determined from the following formula (1) is 80% or less, and the ratio of mesopore volume determined from the following formula (2) is 20% or more.
Micropore volume/(micropore volume + mesopore volume) x 100...(1)
Mesopore volume/(micropore volume + mesopore volume) x 100...(2)

The fibrous activated carbon according to claim 1, wherein the activated carbon has an adsorption ability for perfluoroalkyl compounds and polyfluoroalkyl compounds in water.

The fibrous activated carbon according to claim 1, wherein the activated carbon is alkali activated carbon.

A water purifier using the fibrous activated carbon according to claims 1 to 6.