TWI891653B - Activated carbon for adsorption of per- and polyfluoroalkyl compounds in water samples - Google Patents

Abstract

The present invention provides an activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples, which has a high capture rate for per- and polyfluoroalkyl compounds in water samples, and a filter using the same. The solution is an activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples, which is composed of an activated carbon adsorbent material and is used to releasably adsorb per- and polyfluoroalkyl compounds in water samples. The activated carbon adsorbent material has a BET specific surface area of 800 ^m² /g or greater, or a surface oxide content of 0.20 meq/g or less, or a BET specific surface area of 800 ^m² /g or greater and a surface oxide content of 0.50 meq/g or less, and a total volume of micropores smaller than 1 nm (V _mic ) of 0.30 ^cm³ /g or greater.

Description

Activated carbon for adsorption of per- and polyfluoroalkyl compounds in water samples

The present invention relates to an activated carbon for adsorbing perfluoroalkyl compounds and polyfluoroalkyl compounds, which can capture perfluoroalkyl compounds and polyfluoroalkyl compounds contained in water samples.

Perfluoroalkyl and polyfluoroalkyl compounds (PFAs) are fluorine-substituted aliphatic compounds that exhibit high thermal and chemical stability and high surface modification activity. Utilizing these properties, PFAs are widely used in industrial and chemical applications such as surface treatment agents, packaging materials, and liquid fire extinguishers.

Some perfluoroalkyl (PFAS) compounds (PFAs) are extremely stable chemicals that are difficult to decompose under natural conditions after release into the environment. Consequently, they have become widely known as persistent organic pollutants (POPs) in recent years. Among them, perfluorooctane sulfonic acid (PFOS) (IUPAC name: 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfonic acid) has been regulated under the Stockholm Convention on Persistent Organic Pollutants (POPs Convention) since 2010.

Furthermore, perfluoroalkyl compounds are substances with fully fluorinated linear alkyl groups and are represented by the chemical formula (i). Examples include perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) (IUPAC name: 2,2,3,3,4,4,5,5, 6,6,7,7, 8,8,8-pentadecafluorooctanoic acid).

[Number 1]

Polyfluoroalkyl compounds are compounds in which a portion of the hydrogen atoms in an alkyl group are replaced by fluorine atoms and are represented by the chemical formula (ii). Examples include fluorinated short-chain polymer alcohols.

[Number 2]

As mentioned above, because PFASs (perfluoroalkyl compounds) persist in the natural world (water, soil, and atmosphere), research is underway to establish quantitative test methods for their presence. Research into quantitative test methods focuses on developing capture materials with high adsorption and desorption properties for PFASs. This method involves bringing water or air, which contains trace amounts of PFASs, into contact with the capture material to capture the PFASs. The compounds adsorbed on the capture material are then extracted and concentrated into an extract. Following concentration, quantitative analysis is performed using instruments such as LC-MS/MS or GC-MS/MS to determine the concentration of PFASs in the sample.

As an existing capture material, an organic fluorine compound adsorbent composed of a cyclodextrin polymer has been proposed (Patent Document 1). This adsorbent is specially modified to only adsorb the compound and not release it, making it unsuitable for quantitative measurement. Furthermore, cyclodextrin polymers are in powder or microparticle form, making them difficult to handle. The high resistance to liquid or gas flow creates the risk of fine powders leaking out of the secondary side.

Furthermore, perfluorinated and polyfluorinated alkyl compounds often remain in the environment in a variety of forms with a wide range of physical and chemical properties. Existing adsorbents do not have sufficient capture performance, making it difficult to accurately quantify them.

Therefore, the applicants in this case conducted research using activated carbon as a capture material for per- and polyfluoroalkyl compounds (PFACs) and discovered that it can capture PFACs and is highly beneficial for accurate quantitative determination. [Prior Art] [Patent]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2012-101159

[The problem that the invention aims to solve]

The present invention was made in light of the foregoing issues and, in particular, provides an activated carbon capable of releasably capturing per- and polyfluoroalkyl compounds in water samples and a filter using the same. [Means for Solving the Problem]

That is, the first invention relates to an activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples, which is used for releasably adsorbing per- and polyfluoroalkyl compounds in water samples, wherein the activated carbon adsorbent has a BET specific surface area of 800 ^m2 /g or more or a surface oxide content of 0.20 meq/g or less.

The second invention relates to an activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples. The activated carbon is used for releasably adsorbing per- and polyfluoroalkyl compounds in water samples. The activated carbon adsorbent has a BET specific surface area of 800 ^m2 /g or greater and a surface oxide content of 0.50 meq/g or less.

The third invention relates to the activated carbon of the first or second invention, wherein the sum of the micropore volumes (V _mic ) of the activated carbon adsorbent material having a size of 1 nm or less is 0.30 cm ³ /g or more and is capable of adsorbing perfluoroalkyl and polyfluoroalkyl compounds in water samples.

The fourth invention relates to any one of the first to third inventions, wherein the activated carbon adsorbent is fibrous activated carbon that adsorbs perfluoroalkyl and polyfluoroalkyl compounds in water samples.

The fifth invention relates to a filter for adsorbing perfluoroalkyl and polyfluoroalkyl compounds in water samples, characterized by maintaining the adsorption activated carbon of any one of the first to fourth inventions. [Effects of the Invention]

The activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples according to the first invention has a BET specific surface area of 800 ^m² /g or more or a surface oxide content of 0.20 meq/g or less for releasably adsorbing per- and polyfluoroalkyl compounds in water samples. Therefore, the activated carbon for adsorbing per- and polyfluoroalkyl compounds can releasably capture these compounds, which have been difficult to quantitatively determine.

The activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples according to the second invention has a BET specific surface area of at least 800 ^m² /g and a surface oxide content of at most 0.50 meq/g for releasably adsorbing per- and polyfluoroalkyl compounds in water samples. Therefore, the activated carbon for adsorbing per- and polyfluoroalkyl compounds can more effectively and releasably capture these compounds, which have been difficult to quantitatively determine.

The activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples according to the third invention is capable of effectively and releasably capturing per- and polyfluoroalkyl compounds because the sum of the micropore volumes (V _mic ) of the activated carbon adsorbent material having a diameter of 1 nm or less is 0.30 cm ³ /g or more.

According to the fourth invention, the activated carbon for adsorbing perfluoroalkyl and polyfluoroalkyl compounds in water samples, since the activated carbon adsorption material in any one of the first to third inventions is fibrous activated carbon, the contact efficiency with perfluoroalkyl and polyfluoroalkyl compounds can be increased, thereby enhancing the adsorption performance.

The filter for adsorbing perfluoroalkyl and polyfluoroalkyl compounds in water samples according to the fifth invention is formed by retaining the adsorption activated carbon of any one of the first to fourth inventions. Therefore, the capture efficiency of perfluoroalkyl and polyfluoroalkyl compounds can be improved and the filter has good operability.

[Form of implementing the invention]

The activated carbon of the present invention, which adsorbs per- and polyfluoroalkyl compounds in water samples, is composed of fibrous activated carbon or granular activated carbon. Fibrous activated carbon is obtained by carbonizing and activating suitable fibers, such as phenolic resins, acrylic resins, cellulose, and coal asphalt. The fiber length and cross-sectional diameter are suitable.

Granular activated carbon can be made from materials such as wood (waste wood, thinnings, sawdust), coffee bean residue, rice husks, coconut shells, bark, and fruit. These natural materials are easily carbonized and activated to create fine pores. Furthermore, since they are recycled waste, they are available at a low cost. Other materials include tires, petroleum asphalt, charcoal from synthetic resins such as urethane and phenolic resins, and even coal.

The activated carbon raw material is heated and carbonized at a temperature between 200°C and 600°C, forming fine pores. Next, it is activated by exposing it to steam and carbon dioxide at a temperature between 600°C and 1200°C. This results in activated carbon with well-defined pores. Other activation methods include zinc chloride activation. Sequential washing is also performed.

The adsorption performance of the adsorbate is determined by the physical properties of the activated carbon thus formed. The adsorption performance of activated carbon for perfluoroalkyl and polyfluoroalkyl compounds, the target adsorbates of this invention, is determined by its specific surface area, which is an indicator of the amount of pores formed in the activated carbon. In this specification, the specific surface area of each experimental example was measured using the BET method (Brunauer, Emmett, and Teller method).

The adsorption performance of activated carbon is also determined by the acidic functional groups present on its surface. The acidic functional groups that increase due to surface oxidation of activated carbon are primarily hydrophilic groups such as carboxyl and phenolic hydroxyl groups. The acidic functional groups on the activated carbon surface affect its capture capacity. The amount of these acidic functional groups can be measured by the amount of surface oxides.

In water, the greater the amount of surface oxides on activated carbon, the more likely water molecules, strongly adsorbed to surface functional groups through hydrogen bonds, and the resulting water molecule clusters, are to clog pores, hindering the physical access and egress of the target adsorbate to the adsorption sites (micropores). Therefore, it is believed that the lower the amount of surface oxides on activated carbon, the better the adsorption performance of the target adsorbate.

As a method to reduce the surface oxides of activated carbon, a known method such as heat treatment in an inert gas environment can be used to reduce acidic functional groups such as phenolic hydroxyl groups or carboxyl groups on the surface of the activated carbon.

Furthermore, activated carbon is also defined by the pore size. Adsorbent materials such as activated carbon can contain micropores, mesopores, and macropores. The adsorption targets and performance of activated carbon can be modified by further developing and perfecting the pores within any range. The activated carbon desired in the present invention is capable of releasably and effectively adsorbing molecules of per- and polyfluoroalkyl compounds.

As demonstrated in the examples described below, activated carbon capable of releasably adsorbing per- and polyfluoroalkyl compounds in aqueous samples exhibits adsorption performance when its specific surface area is greater than 800 ^m² /g or its surface oxide content is less than 0.20 meq/g. We hypothesize that the acidic functional groups on the activated carbon surface clog pores with water molecules adsorbed via hydrogen bonds, and the resulting water molecule clusters. Therefore, when the surface oxide content is low, activated carbon with a small specific surface area and a small number of pores can still adsorb a certain amount of the compound. Conversely, even when a large surface oxide content hinders the compound's adsorption into pores, activated carbon with a large specific surface area and a large number of pores can still adsorb a certain amount of the compound.

Furthermore, as long as the specific surface area is above a certain value and the surface oxide content is below a certain value, per- and polyfluoroalkyl compounds in water samples can be more effectively and releasably adsorbed. As shown in the examples described below, by setting the BET specific surface area of the activated carbon adsorbent to 800 ^m² /g or above and the surface oxide content to 0.50 meq/g or below, the adsorption performance of per- and polyfluoroalkyl compounds in water samples can be further improved. [Examples]

[Activated Carbon Adsorbent Materials Used] The inventors used the following raw materials to create activated carbon for adsorbing perfluoroalkyl and polyfluoroalkyl compounds. • Fibrous Activated Carbon Futamura Chemical Co., Ltd.: Fibrous Activated Carbon "CF" (Average Fiber Diameter: 15μm) {Hereinafter, C1} Futamura Chemical Co., Ltd.: Fibrous Activated Carbon "FE3010" (Average Fiber Diameter: 15μm) {Hereinafter, C2} Futamura Chemical Co., Ltd.: Fibrous Activated Carbon "FE3012" (Average Fiber Diameter: 15μm) {Hereinafter, C3} Futamura Chemical Co., Ltd.: Fibrous Activated Carbon "FE3013" (Average Fiber Diameter: 15μm) {Hereinafter, C4} FUTAMURA Manufactured by Chemical Co., Ltd.: Fibrous activated carbon "FE3015" (average fiber diameter: 15μm) {Hereinafter referred to as C5} Manufactured by Futamura Chemical Co., Ltd.: Fibrous activated carbon "FE3018" (average fiber diameter: 15μm) {Hereinafter referred to as C6} • Granular activated carbon Manufactured by Futamura Chemical Co., Ltd.: Coconut shell activated carbon "CW480SZ" (average particle size: 250μm) {Hereinafter referred to as C7}

[Study on the Capture Performance of Per- and Polyfluoroalkyl Compounds in Water Samples 1] The inventors of this application conducted Experiment 1 on the capture of per- and polyfluoroalkyl compounds in water samples using the following Experiment 1.

[Trial Example Preparation] <Trial Example 1> 10g of Futamura Chemical's fibrous activated carbon "FE3015" (C5) was immersed in 500ml of a 6% hydrogen peroxide solution. After standing for 70 hours, the mixture was removed and dried to produce the activated carbon for Trial Example 1.

[Determination of Activated Carbon 1] [Surface Oxide Content] The surface oxide content (meq/g) was determined by applying the Boehm method. The adsorbed activated carbon of each example was shaken in a 0.05N aqueous sodium hydroxide solution, filtered, and the resulting filtrate was neutralized and titrated with 0.05N hydrochloric acid to determine the amount of sodium hydroxide present.

[BET specific surface area] The specific surface area (m ² /g) was determined by the BET method using the automatic specific surface area/pore distribution measuring apparatus "BELSORP-miniII" manufactured by Microtrac BEL Co., Ltd. to measure the nitrogen adsorption isotherm at 77 K (BET specific surface area).

[Average Pore Diameter] The average pore diameter (nm) is calculated using formula (iii) using the pore volume (cm ³ /g) and specific surface area (m ² /g), assuming the pore shape is cylindrical.

[number 3]

The physical properties of the activated carbon of Experimental Example 1 are shown in Table 1. From the top of Table 1, they are surface oxide content (meq/g), BET specific surface area (m ² /g), average pore diameter (nm), and average fiber diameter (μm).

[Determination of the Capture Efficiency of Per- and Polyfluoroalkyl Compounds in Water Samples 1] Fluorinated short-chain polymer alcohols (hereinafter referred to as "FTOHs") were used as per- and polyfluoroalkyl compounds for evaluation. FTOHs are substances represented by the chemical formula (ii) above, and their names vary depending on the number of carbon atoms. For example, C ₈ F ₁₇ CH ₂ CH ₂ OH is designated as 8:2FTOH (IUPAC name: 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decanol).

A standard test solution of each FTOH of interest was added to ultrapure water to prepare a 0.5 ng/ml (0.5 ppb) test solution.

A 20ml syringe was filled with 0.2g of the fibrous activated carbon from Experimental Example 1. The test solution was then introduced into the syringe at a rate of 1 drop/second. After 30 seconds of aeration and dehydration, the activated carbon in the syringe was thoroughly stirred with 15ml of a mixture of dichloromethane and ethyl acetate. The solid-liquid separation was then performed by centrifugation, and the extract was collected.

The extract was quantitatively analyzed by GC-MS/MS (QuatrimicroGC manufactured by Waters) in MRM mode to confirm the capture performance.

Table 2 shows the recovery rate (%) of FTOHs for each target substance, 4:2FTOH, 6:2FTOH, 8:2FTOH, and 10:2FTOH, for the activated carbon in Experiment 1.

[Study 2 on the Capture Performance of Per- and Polyfluoroalkyl Compounds in Water Samples] Next, the inventors used PFOA (C ₈ HF ₁₅ O ₂ ) and PFOS (C ₈ HF ₁₇ O ₃ S) as per- and polyfluoroalkyl compounds, and conducted capture experiment 2 and evaluation on the following experimental examples 2 to 13.

[Trial Example Preparation] <Trial Example 2> 10g of FUTAMURA CHEMICAL fibrous activated carbon "CF" (C1) was used as the activated carbon for Trial Example 2.

<Trial Example 3> 10 g of Futamura Chemical fibrous activated carbon "CF" (C1) was immersed in 500 ml of a 4.2% hydrogen peroxide solution. After standing for 220 hours, the mixture was removed and dried to produce the activated carbon for Trial Example 3.

<Trial Example 4> For Trial Example 4, 10 g of Futamura Chemical's fibrous activated carbon "FE3010" (C2) was used.

<Trial Example 5> 10 g of Futamura Chemical's fibrous activated carbon "FE310" (C2) was immersed in 500 ml of a 4.2% hydrogen peroxide solution. The solution was allowed to stand for 150 hours, then removed and dried to produce the activated carbon of Trial Example 5.

<Trial Example 6> For Trial Example 6, 10 g of Futamura Chemical's fibrous activated carbon "FE3012" (C3) was used.

<Trial Example 7> 10 g of Futamura Chemical's fibrous activated carbon "FE3012" (C3) was immersed in 500 ml of a 4.2% hydrogen peroxide solution. The solution was allowed to stand for 100 hours, then removed and dried to produce the activated carbon of Trial Example 7.

<Trial Example 8> 10g of Futamura Chemical's fibrous activated carbon "FE3013" (C4) was immersed in 500ml of a 1.5% hydrogen peroxide solution. After standing for 70 hours, the mixture was removed and dried to produce the activated carbon of Trial Example 8.

<Trial Example 9> For Trial Example 9, 10 g of Futamura Chemical's fibrous activated carbon "FE3015" (C5) was used.

<Trial Example 10> 10g of Futamura Chemical's fibrous activated carbon "FE3015" (C5) was immersed in 500ml of a 1.5% hydrogen peroxide solution. After standing for 40 hours, the mixture was removed and dried to produce the activated carbon of Trial Example 10.

<Trial Example 11> 10 g of Futamura Chemical's fibrous activated carbon "FE3015" (C) was immersed in 500 ml of a 4.2% hydrogen peroxide solution. The solution was allowed to stand for 70 hours, then removed and dried to produce the activated carbon for Trial Example 11.

<Trial Example 12> 10 g of Futamura Chemical's fibrous activated carbon "FE3015" (C5) was immersed in 500 ml of a 14.0% hydrogen peroxide solution. The solution was allowed to stand for 350 hours, then removed and dried to produce the activated carbon for Trial Example 12.

<Trial Example 13> 10 g of Futamura Chemical's fibrous activated carbon "FE3015" (C5) was immersed in 500 ml of an 18.9% hydrogen peroxide solution. The solution was allowed to stand for 480 hours, then removed and dried to produce the activated carbon of Trial Example 13.

<Trial Example 14> For Trial Example 14, 10 g of FUTAMURA CHEMICAL fibrous activated carbon "FE3018" (C6) was used.

<Trial Example 15> 10 g of Futamura Chemical's fibrous activated carbon "FE3018" (C6) was immersed in 500 ml of a 4.2% hydrogen peroxide solution. The solution was allowed to stand for 50 hours, then removed and dried to produce the activated carbon of Trial Example 15.

<Trial Example 16> 10 g of Futamura Chemical's fibrous activated carbon "FE3018" (C6) was immersed in 500 ml of a 14.0% hydrogen peroxide solution. The solution was allowed to stand for 350 hours, then removed and dried to produce the activated carbon of Trial Example 16.

<Trial Example 17> 10 g of Futamura Chemical's fibrous activated carbon "FE3018" (C6) was immersed in 500 ml of an 18.9% hydrogen peroxide solution. After standing for 480 hours, the mixture was removed and dried to produce the activated carbon of Trial Example 17.

<Trial Example 18> 10g of Futamura Chemical coconut shell activated carbon "CW480SZ" (C7) was used as the activated carbon for Trial Example 18.

[Activated Carbon Measurement 2] The surface oxide, specific surface area, and average pore diameter of Experimental Examples 2-18 were determined using the same method as in "Activated Carbon Measurement 1" above.

[Micropore Volume] Pore volume was measured by nitrogen adsorption using an automated surface area/pore distribution analyzer (BELSORP-miniII, manufactured by Microtrac BEL Co., Ltd.). The sum of the pore volume (V _mic ) (cm ³ /g) for pores with a diameter of 1 nm or less in Experimental Examples 2-18 was determined by analyzing the dV/dD value of the nitrogen adsorption isotherm for the pore diameter range of 1 nm or less using the MP method.

[Mesopore Volume] The dV/dD values for pores with a diameter of 2 to 60 nm were analyzed using the DH method based on nitrogen adsorption isotherms. Furthermore, the pore diameter range for pores with a diameter of 2 to 60 nm using the analytical software was 2.43 to 59.72 nm. Based on these analytical results, the sum of the pore volume and the mesopore volume (V _met ) (cm ³ /g) for the pores with a diameter of 2 to 60 nm in Experimental Examples 6 to 21 was calculated.

The physical properties of the activated carbons from Experimental Examples 2 to 18 are shown in Tables 3 to 5. From the top of Table 3, they are surface oxide content (meq/g), BET specific surface area (m ² /g), average pore diameter (nm), micropore volume (V _mic ) (cm ³ /g), and mesopore volume (V _met ) (cm ³ /g).

[Determination of Capture Efficiency of Per- and Polyfluoroalkyl Compounds in Water Samples 2] PFOA and PFOS were used for the evaluation of per- and polyfluoroalkyl compounds.

The test solutions were prepared by adding standard reagents of the target substances PFOA and PFOS to ultrapure water and adjusting the concentration of the PFOA and PFOS solutions to 10 ng/ml (10 ppb).

A 20ml syringe was filled with 0.2g of the above-mentioned carbon sample. A total of 20ml of the test solution was introduced at a rate of 1 drop/second. After the solution was introduced, the water content of the activated carbon sample in the syringe was removed by centrifugation. Subsequently, 14ml of a methanol solution adjusted to a 0.01% ammonia concentration was introduced into the dehydrated sample at a rate of 1 drop/second, and the extract was collected.

The extracted solution was concentrated to 1 ml using a nitrogen purge concentrator and then quantitatively analyzed using LC-MS/MS ("LCMS-8030", manufactured by Shimadzu Corporation) in MRM mode to confirm the capture performance.

Tables 6 through 8 show the recovery rate (%) for each target substance for Experiments 2 through 18. The target substances were PFOA and PFOS.

Results and Discussion: Tests 3 and 5 resulted in low recovery rates for both PFOA and PFOS, indicating insufficient adsorption of the target substances. This is presumably due to the small surface area and high amount of surface oxides, resulting in insufficient pores for adsorption, hindering optimal adsorption performance.

In contrast, Trial Example 2, with its smaller specific surface area, was able to adequately adsorb the target substance. This is believed to be because the lower amount of surface oxides prevents water molecules from adsorbing to the functional groups on the activated carbon surface via hydrogen bonds, or because the resulting water molecule clusters are less likely to clog the pores. This results in sufficient pores to adsorb the target substance, even with a smaller specific surface area. Consequently, the activated carbon's adsorption performance is believed to be fully utilized.

Samples 12, 13, 16, and 17, which had high amounts of surface oxide, also showed adsorption of the target substance. This is believed to be because, despite the clogging of pores by water molecules or clusters caused by the high amount of surface oxide, the large specific surface area still provided sufficient pores for adsorption. Therefore, it is believed that the activated carbon's adsorption properties were fully utilized, demonstrating adsorption of per- and polyfluoroalkyl compounds. These facts demonstrate that a specific surface area greater than a certain value or a surface oxide content below a certain value are the conditions for ensuring adsorption of per- and polyfluoroalkyl compounds in water samples.

Looking at the results of Experiments 9-13 and 14-17, which used the same activated carbon but varied the amount of surface oxide, it can be seen that in Experiments where the amount of surface oxide increased through oxidation treatment, both with and without oxidation treatment, the adsorption performance tended to be inferior to that of Experiments with less surface oxide. Therefore, as mentioned above, regarding the adsorption performance of per- and polyfluoroalkyl compounds in water samples, a lower amount of surface oxide is preferred.

Comparing samples 2, 6, 9, and 14, which all had similar amounts of surface oxide, revealed that adsorption of per- and polyfluoroalkyl compounds from aqueous samples was superior when the specific surface area was above a certain value. In particular, it was determined that when the amount of surface oxide was low, sufficient adsorption performance was achieved with a BET specific surface area of 800 ^m² /g or higher. When the amount of surface oxide was high, samples with larger specific surface areas tended to exhibit better adsorption performance.

Using activated carbon with a larger specific surface area and a lower amount of surface oxides has been shown to further enhance adsorption performance for both PFOA and PFOS. It is known that by increasing the specific surface area above a certain value and keeping the amount of surface oxides below a certain value, adsorption performance for per- and polyfluoroalkyl compounds in water samples can be further enhanced, resulting in better recovery rates. Furthermore, from the perspective of the contact efficiency between the target substance and the activated carbon, it has been determined that using fibrous activated carbon is even more effective in adsorbing per- and polyfluoroalkyl compounds.

Furthermore, if activated carbon with perfectly formed micropores that meet the aforementioned conditions is used, it is expected that its adsorption performance for per- and polyfluoroalkyl compounds in water samples will be further enhanced. Furthermore, if the mesopores are perfectly formed, it is expected that the molecules of the target substance can be smoothly introduced into the pores of the activated carbon, thereby exerting excellent adsorption performance. Furthermore, it is believed that after the molecules of the target substance are adsorbed within the micropores, they can be easily and smoothly removed from the pores during extraction, achieving a good recovery rate. [Industrial Applicability]

The activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples of the present invention can releasably adsorb per- and polyfluoroalkyl compounds in water samples, enabling quantitative determination of these compounds, which is not possible with existing capture materials. This enables effective quantitative assessment of persistent organic pollutants.

Claims (4)

An activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples is disclosed. The activated carbon adsorbent has a BET specific surface area of 800 ^m² /g or greater, or a surface oxide content of 0.20 meq/g or less, and a total volume of micropores smaller than 1 nm (V _mic ) of 0.30 ^cm³ /g or greater. The desorption is performed by extracting the per- and polyfluoroalkyl compounds from the water sample into an extract. An activated carbon for adsorbing per- and polyfluoroalkyl compounds in water samples is disclosed. The activated carbon adsorbent has a BET specific surface area of 800 ^m² /g or greater, a surface oxide content of 0.50 meq/g or less, and a micropore volume (V _mic ) of 1 nm or less of 0.30 ^cm³ /g or greater. The desorption is performed by extracting the per- and polyfluoroalkyl compounds from the water sample into an extract. The activated carbon for adsorbing perfluoroalkyl and polyfluoroalkyl compounds in water samples as claimed in claim 1 or 2, wherein the activated carbon adsorption material is fibrous activated carbon. A filter for adsorbing perfluoroalkyl and polyfluoroalkyl compounds in water samples, characterized in that it is made of adsorbent activated carbon as described in any one of claims 1 to 3.