A method for adsorbing perfluoro- and polyfluoroalkyl substances in aqueous solutions

Abstract

The present application belongs to the technical field of environmental water treatment, and relates to a method for adsorbing perfluoroalkyl and polyfluoroalkyl compounds in an aqueous solution. The method comprises the following steps: S1, adjusting the pH value of the aqueous solution containing perfluoroalkyl and polyfluoroalkyl compounds to be below 7; S2, after the pH value adjustment is completed, adding a polystyrene-divinylbenzene microsphere modifier into the aqueous solution, the polystyrene-divinylbenzene microsphere modifier being a hydrophilic group modified polystyrene-divinylbenzene microsphere modifier, and then stirring at room temperature until the perfluoroalkyl and polyfluoroalkyl compounds dissolved in the water are completely adsorbed on the polystyrene-divinylbenzene microsphere modifier. The purpose of the present application is to develop a method for efficiently and low-costly removing PFASs in water, the method having a very high adsorption capacity for perfluoroalkyl and polyfluoroalkyl compounds and being capable of removing more than 99% of long-chain and short-chain perfluoroalkyl and polyfluoroalkyl compounds.

Description

Technical Field

[0001] This invention belongs to the field of environmental water treatment technology and relates to a method for adsorbing perfluorinated and polyfluoroalkyl compounds in aqueous solutions. Background Technology

[0002] PFASs (Perfluoroalkyl and Polyfluoroalkyl Substances) are a class of novel environmental pollutants with unique structures. As artificially synthesized persistent organic compounds, PFASs have been widely used in textile coatings, non-stick fillers, food packaging, detergents, fire protection, and many other fields.

[0003] PFAS is a broad class of chemical substances. Long-chain PFAS such as PFOA (Perfluorooctanoic Acid) and PFOS (Perfluorooctane Sulfonates), and short-chain PFAS such as PFBA (Perfluorobutanoic Acid) and PFBS (Perfluorobutane Sulfonates) are currently the most concerning PFASs. Data shows that although the concentrations in global surface water are mostly below the prescribed thresholds, various PFAS are detected to varying degrees, and many PFAS are still found in treated drinking water.

[0004] Traditional coagulation, sedimentation, sand filtration, and disinfection technologies achieve PFAS removal rates below 20%. Activated carbon is reasonably effective at removing long-chain PFAS (such as PFOA and PFOS) due to its strong hydrophobic properties, but it is less effective at removing shorter-chain PFAS (such as PFBA and PFAS) which are more polar. While nanofiltration and ion exchange resin technologies can relatively effectively remove PFAS from drinking water, they are inefficient, have extremely long equilibrium times, and are relatively costly.

[0005] Chinese patent CN119859214A mentions a hydrophobic porous adsorbent material for removing perfluorooctanoic acid (PFOA) from water, including a divinylbenzene ionic liquid polymer. However, the use of hydrophobic porous materials presents a problem: water cannot wet the materials, meaning the wastewater cannot wet the hydrophobic material, thus preventing adsorption.

[0006] Chinese patent CN106220786B mentions a method for developing a novel adsorbent material with selective adsorption capacity for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in aquatic environments. The method uses 2-(trifluoromethyl)acrylic acid and 4-vinylpyridine as bifunctional monomers, PFOA as the template molecule, and EDMA as the crosslinking agent to synthesize the bifunctional monomer molecularly imprinted polymer TFMAA / 4-Vpy-MIP. This polymer can simultaneously and efficiently selectively adsorb and remove PFOA and PFOS from the aqueous phase, achieving adsorption rates of 78.8% and 76.7% for PFOA and PFOS, respectively. However, this method has several drawbacks. Firstly, the use of molecular imprinting technology generates a large amount of PFOA wastewater before treatment. Secondly, while PFOA is a highly selective template, the wastewater contains many types of PFAS, requiring the use of multiple imprinted templates to remove different PFAS, resulting in high costs. Furthermore, the removal rate is relatively low and needs further improvement. In addition, the patent specifies that its adsorbent material is a powder that has been ground into gel and passed through 100 mesh. This amorphous powder is prone to pulverization during use, which may lead to problems such as the powder easily entering the water being purified, causing blockage and reducing the flow rate.

[0007] Chinese patent CN111171199A mentions an adsorption resin for removing perfluorinated pollutants from water, its preparation, and its application. It uses styrene and divinylbenzene as framework materials, selects suitable porogens and dispersants to prepare a macroporous resin with moderate pore size, and uses p-dichlorobenzyl (XDC) as a post-crosslinking agent to induce alkylation under low steric hindrance. This post-crosslinking introduces a rigid benzene ring structure into the resin, further increasing its hydrophobicity, improving the degree of crosslinking, and adjusting the microporous structure, resulting in an adsorption resin with narrow particle size distribution, uniform pore size, and high specific surface area. Although the microspheres prepared by this patent introduce chlorine, their hydrophobicity remains strong. Poor wetting of the wastewater with the material leads to a long PFAS adsorption equilibrium time. Furthermore, their small pore size (3-5 nm) further exacerbates the long adsorption equilibrium time, resulting in very low adsorption efficiency. Moreover, the small pore size is unsuitable for removing long-chain molecules of PFAS with relatively large pore sizes.

[0008] Therefore, researching low-cost and renewable adsorbent materials that can effectively and rapidly remove PFASs and exploring their processes is of great significance for water resource protection and public health. Summary of the Invention

[0009] To address the aforementioned problems, the purpose of this invention is to develop a highly efficient and low-cost method for removing PFASs from water. This method exhibits a very high adsorption capacity for perfluorinated and polyfluoroalkyl (PFAS) compounds, capable of removing over 99% of both long-chain and short-chain PFAS compounds. Furthermore, the PFAS compounds can be repeatedly recycled after elution, enabling high-throughput, low-cost, and large-scale water purification.

[0010] In a first aspect, the method for adsorbing perfluorinated and polyfluoroalkyl compounds in aqueous solution according to the present invention includes: S1. Adjust the pH of the aqueous solution containing perfluorinated and polyfluorinated alkyl compounds to below 7; S2. After pH adjustment, add polystyrene-divinylbenzene microsphere modifier to the aqueous solution, and then stir at room temperature until the perfluorinated and polyfluoroalkyl compounds dissolved in the water are completely adsorbed onto the polystyrene-divinylbenzene microsphere modifier.

[0011] In an optional embodiment, the concentration of the polystyrene-divinylbenzene microsphere modifier is 10 mg / L to 10 g / L.

[0012] In an optional embodiment, the polystyrene-divinylbenzene microsphere modifier is a hydrophilic group modified polystyrene-divinylbenzene microsphere modifier; preferably, the polystyrene-divinylbenzene microsphere modifier is an N-vinylpyrrolidone modified polystyrene-divinylbenzene microsphere modifier.

[0013] In optional embodiments, the perfluorinated and polyfluoroalkyl compounds are one or a mixture of several of perfluorooctane carboxylic acid, perfluorooctane sulfonic acid, perfluorobutane carboxylic acid, perfluorobutyl sulfonic acid, hexafluoropropylene oxide dimer acid, perfluorohexane sulfonic acid, and 6:2-fluorohydroxy alcohol.

[0014] In an optional embodiment, the pH of the aqueous solution after pH adjustment is 3 to 7.

[0015] In an optional embodiment, the pH adjuster for adjusting the aqueous solution is formic acid, acetic acid, or hydrochloric acid.

[0016] Secondly, the present invention provides the application of polystyrene-divinylbenzene microspheres modified with polystyrene for the adsorption of perfluorinated and polyfluoroalkyl compounds in aqueous solutions. Attached Figure Description

[0017] Figure 1 This is a multiple reaction monitoring (MRM) extractive ion chromatogram of a 1000 ng / L PFOA standard solution; Figure 2 This is a multiple reaction monitoring (MRM) extractive ion chromatogram of a 1000 ng / L PFBS standard solution; Figure 3 This is a standard curve of PFOA in the concentration range of 100 ng / L to 1000 ng / L; Compound name: PFOA; Correlation coefficient: r = 0.995316, r 2 =0.990653, Standard curve: 18.4932*x±73.8361; Response type: External standard, area; Curve type: Linear.

[0018] Figure 4 This is a standard curve of PFBS in the concentration range of 100 ng / L to 1000 ng / L; Compound name: PFBS; Correlation coefficient: r = 0.995736, r 2 =0.991490, Standard curve: 11.453*x±44.9277; Response type: External standard, area; Curve type: Linear.

[0019] Figure 5 (a) Contact angle of polystyrene-divinylbenzene microspheres with water; (b) Contact angle of N-vinylpyrrolidone modified polystyrene-divinylbenzene microspheres with water. Detailed Implementation

[0020] The present invention is further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the invention. New environmental pollutants such as PFASs readily exist in water bodies. Specifically, the present invention provides the application of HPB in the adsorption of perfluorinated and polyfluorinated compounds in aqueous solutions. Particularly preferred is HPB, a hydrophilic N-vinylpyrrolidone-modified polystyrene-divinylbenzene copolymer adsorbent, which exhibits good water wetting and reverse-phase retention of both polar and nonpolar compounds. The following exemplary method for adsorbing perfluorinated and polyfluorinated alkyl compounds in aqueous solutions is described.

[0021] The pH of the aqueous solution containing perfluorinated and polyfluoroalkyl compounds is adjusted. Changing the pH can adjust the charge state of the polar head groups of PFASs, making short-chain PFASs more easily adsorbed by HPB. The removal of short-chain PFASs is currently a more important and challenging technical problem. In an optional embodiment, the pH of the adjusted aqueous solution is neutral or weakly acidic. For example, the pH of the aqueous solution is adjusted to below 7. Preferably, the pH of the aqueous solution is adjusted to 3-7.

[0022] As an example, the pH of an aqueous solution containing perfluorinated and polyfluoroalkyl compounds is adjusted by adding a reagent. The reagent includes, but is not limited to, formic acid, acetic acid, or hydrochloric acid. The concentration of hydrochloric acid can be 0.1–1 M.

[0023] After pH adjustment, polystyrene-divinylbenzene microspheres or their modified forms are added to the aqueous solution, and then stirred at room temperature until perfluorinated and polyfluoroalkyl compounds are completely adsorbed.

[0024] The concentration of polystyrene-divinylbenzene microspheres or their modified forms is 10 mg / L to 10 g / L. Too low a concentration of polystyrene-divinylbenzene microspheres or their modified forms may result in incomplete adsorption of PFASs in water by HPB or an excessively long adsorption time. Preferably, the concentration of polystyrene-divinylbenzene microspheres or their modified forms is 1 g / L.

[0025] In an optional embodiment, the polystyrene-divinylbenzene microsphere modifier is a hydrophilic-modified PD-DVB (polystyrene-divinylbenzene) microsphere. Preferably, the polystyrene-divinylbenzene microsphere modifier is an N-vinylpyrrolidone-modified polystyrene-divinylbenzene microsphere (HPB, Hydrohilic-modified polymerbeads), which is a copolymer of styrene and divinylbenzene. A copolymer adsorbent with hydrophilic groups such as N-vinylpyrrolidone introduced onto its surface reduces the contact angle from 120° to 30° (see...). Figure 5 This material can achieve complete water wetting, exhibits good retention of both strongly polar and non-polar compounds, and can be used within a pH range of 0-14. This invention applies it as a simple, inexpensive, and environmentally friendly adsorbent material for water purification. Hydrophilic resin microspheres (HPB) can adsorb various PFASs in water, exhibiting high adsorption capacity, rapid equilibration time, and resistance to pulverization. They also offer higher flux, longer lifespan, and are more suitable for column bed processes, and can be recycled and reused.

[0026] In an optional embodiment, stirring is performed at room temperature (25°C) to allow HPB to adsorb fluoride-containing compounds in the water. The constant temperature condition for adsorption is room temperature, approximately 25°C.

[0027] The perfluorinated and polyfluoroalkyl compounds include, but are not limited to, long-chain perfluorinated and polyfluoroalkyl compounds. For example, perfluorooctanoic acid (perfluorooctane carboxylic acid) and perfluorooctane sulfonic acid.

[0028] The perfluorinated and polyfluoroalkyl compounds include, but are not limited to, short-chain perfluorinated and polyfluoroalkyl compounds. For example, perfluorobutyric acid (perfluorobutane carboxylic acid), perfluorobutylsulfonic acid, 6:2-fluoropolymer (6:2 FTOH), and hexafluoropropylene oxide dimer (HFPO-DA).

[0029] In an optional embodiment, the method for HPB adsorbing PFBSs in tap water includes the following steps: Adsorption performance: Measure 1 L of water and add 1 mL of formic acid (or acetic acid, 0.1 M dilute hydrochloric acid, or other strong acids), then add 100 μL of a 10 μg / mL PFASs standard solution. Weigh 1 g of the adsorbent HPB and add it to the water. Shake for 30 s and let stand. After 24 h, take a sample and filter it through a 0.22 μm aqueous polyethersulfone membrane. Detect the concentration using LC-MS / MS. For example, typical PFOA and PFBS PFASs were added to 1 L of water along with 1% formic acid, followed by 1 g of HPB adsorbent. The results showed that 99.2% of PFOA and 98.8% of PFBS were removed. HPB exhibits good removal capabilities for both long-chain and short-chain PFASs.

[0030] Reuse: Measure 1L of water or 1L of water with 1mL formic acid, add 100µL of 10µg / mL PFASs standard solution, weigh 1g of adsorbent HPB and add it to the water, shake for 30s and let stand for 24h, then measure the PFASs content in the water; collect the HPB adsorbent and wash it with 20mL of methanol; collect the eluent and blow it to near dryness with nitrogen, reconstitute the eluent with 1mL of water and filter it through a 0.22µm aqueous polyethersulfone filter membrane, analyze it with LC-MSMS and calculate the recovery rate of each substance, regenerate HPB and perform a second static adsorption experiment.

[0031] As an example, the method for HPB to adsorb PFBSs in tap water includes the following steps: Adsorption performance: Measure 1L of water, add 100 μL of PFASs standard solution with 10 μg / mL, weigh 1g of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22 μm aqueous polyethersulfone filter membrane, and detect the concentration with LCMSMS.

[0032] Adsorption performance: Measure 1L of water and add 1mL of formic acid, add 100μL of PFASs standard solution of 10 μg / mL, weigh 1g of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22μm aqueous polyethersulfone filter membrane, and detect the concentration with LCMSMS.

[0033] Reuse: Measure 1L of water or 1L of water with 1mL formic acid, add 100μm of 10 μg / mL PFASs standard solution, weigh 10 mg of adsorbent HPB and add it to the water, shake for 30s and let stand for 24h, then measure the PFASs content in the water; collect the HPB adsorbent and wash it with 20 mL of methanol to recover PFAS and calculate the recovery rate; collect the eluent and blow it to near dryness with nitrogen, reconstitute the eluent with 1 mL of water and filter it through a 0.22μm aqueous polyethersulfone filter membrane, analyze it with LC-MSMS and calculate the recovery rate of each substance, and perform a second static adsorption experiment on the regenerated HPB to compare the change in PFAS removal capacity before and after regeneration.

[0034] After regenerating the HPB adsorbent with methanol and conducting a second adsorption experiment, the regenerated HPB retained over 90% of the adsorption capacity of the fresh adsorbent. Data shows that HPB is regenerable, has low application costs, is easy to operate, and can be used for large-scale water purification. Furthermore, it exhibits good removal performance under neutral and acid washing conditions.

[0035] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. The N-vinylpyrrolidone-modified polystyrene-divinylbenzene microspheres (HPB) used in the examples are commercially available products from MicroPure Biotechnology (Guangzhou) Co., Ltd., product number HPB-50-1000G.

[0036] Reagent preparation Weigh 10 mg of PFOA and PFBS standard substances respectively, dilute with 10 mL of methanol, and prepare standard stock solutions of 1000 mg / L respectively.

[0037] Take 100 μL of the standard stock solutions of PFOA and PFBS respectively, dilute with 10 mL of water, and prepare a primary stock solution of 10 mg / L.

[0038] Take 100 μL of the primary stock solution of PFOA and PFBS respectively, dilute with 10 mL of water, and prepare a secondary stock solution of 100 μg / L.

[0039] Take an appropriate amount of PFOA secondary stock solution and dilute it with water to prepare standard curves of 100 ng / L, 200 ng / L, 500 ng / L, 800 ng / L, and 1000 ng / L.

[0040] Take an appropriate amount of PFBS secondary stock solution and dilute it with water to prepare standard curves of 100 ng / L, 200 ng / L, 500 ng / L, 800 ng / L, and 1000 ng / L.

[0041] LC-MS / MS was used for detection, with a Waters TQS micro system. Data was acquired in negative mode, with a capillary voltage of 0.5 kV, a source temperature of 150 °C, a desolvation gas temperature of 500 °C, and a desolvation gas flow rate of 800 L / h.

[0042] Table 1: MRM Acquisition Parameters for PFOA and PFBS .

[0043] Mobile phase A was methanol; mobile phase B was 5 mM ammonium acetate; the chromatographic column was an XP tC18 1.7 μm 2.1*50 mm; the column temperature was 40℃; the injection volume was 5 μL; and the flow rate was 0.3 mL / min. The phase A ratio is the volume percentage of mobile phase A (methanol) at that time point, and the phase B ratio is the volume percentage of mobile phase B (5 mM ammonium acetate) at that time point.

[0044] Figure 1 This is a multiple reaction monitoring (MRM) extractive ion chromatogram of a 1000 ng / L PFOA standard solution; Figure 2 This is a multiple reaction monitoring (MRM) extractive ion chromatogram of a 1000 ng / L PFBS standard solution; Figure 3 This is a standard curve of PFOA in the concentration range of 100 ng / L to 1000 ng / L; Compound name: PFOA; Correlation coefficient: r = 0.995316, r 2 =0.990653, Standard curve: 18.4932*x±73.8361; Response type: External standard, area; Curve type: Linear.

[0045] Figure 4 This is a standard curve of PFBS in the concentration range of 100 ng / L to 1000 ng / L; Compound name: PFBS; Correlation coefficient: r = 0.995736, r 2 =0.991490, Standard curve: 11.453*x±44.9277; Response type: External standard, area; Curve type: Linear.

[0046] Figure 5 (a) Contact angle of polystyrene-divinylbenzene microspheres with water; (b) Contact angle of N-vinylpyrrolidone modified polystyrene-divinylbenzene microspheres with water.

[0047] Table 2: Gradient Methods .

[0048] Example 1

[0049] Application of HPB in adsorbing PFASs in water at a dosage of 10 mg / L.

[0050] (1) Adsorption performance 1-1: Measure 1L of water, add 100μL of PFOA standard solution with 10 μg / mL, weigh 10mg of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22 μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0051] (2) Adsorption performance 1-2: Measure 1L of water, add 100μL of PFBS standard solution with 10 μg / mL, weigh 10mg of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22 μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0052] (3) Adsorption performance 2-1: Measure 1L of water and add 1mL of formic acid, add 100μL of PFOA standard solution with 10 μg / mL, weigh 10mg of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0053] (4) Adsorption performance 2-2: Measure 1L of water and add 1mL of formic acid, add 100μL of 10 μg / mL PFBS standard solution, weigh 10mg of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0054] Qt = (C0 - Ct) × V / ma. Qt (mg / g): adsorption capacity; C0 (ng / L): initial concentration of PFASs in the sample; Ct (ng / L): final concentration of PFASs in the sample after a period of time; V (L): sample volume; ma (g): mass of adsorbent.

[0055] Table 3: Static adsorption performance analysis results of HPB for PFOA .

[0056] Table 4: Static adsorption performance analysis results of HPB on PFBS .

[0057] The results in Tables 3 and 4 show that adding 1% formic acid to 1 L of water before adding HPB adsorbent improves the adsorption capacity of HPB for PFOA and PFBS. PFBS has four carbons, while PFOA has eight carbons. PFBS is more polar and acidic. In pure water, HPB has a relatively weak retention capacity for both, and the retention of compounds with shorter carbon chains is even worse. The addition of 1% formic acid creates acidic conditions that enhance the retention of PFASs compounds.

[0058] Example 2

[0059] PFAS removal efficiency of HPB at a dosage of 1 g / L over 24 hours.

[0060] (1) Adsorption performance 2-1: Measure 1L of water, add 100μL of PFOA standard solution with 10 μg / mL, weigh 1g of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22 μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0061] (2) Adsorption performance 2-2: Measure 1L of water, add 100μL of PFBS standard solution with 10 μg / mL, weigh 1g of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22 μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0062] (3) Adsorption performance 3-1: Measure 1L of water and add 1mL of formic acid, add 100μL of PFOA standard solution with 10 μg / mL, weigh 1g of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0063] (4) Adsorption performance 3-2: Measure 1L of water and add 1mL of formic acid, add 100μL of 10 μg / mL PFBS standard solution, weigh 1mg of adsorbent HPB and add it to the water, shake for 30s and let stand, take a sample after 24h and filter it with a 0.22μm aqueous polyether sulfone filter membrane, and detect the concentration with LCMSMS.

[0064] The results showed that when the HPB addition reached 1 g / L, both acidic and neutral conditions could remove more than 99% of long-chain and short-chain PFASs. When the HPB addition was 1 g / L, the adsorption capacity for PFOA at a concentration of 10 μg / L was 0.92 mg / g, and the adsorption capacity for PFOA was 0.883 mg / g.

[0065] Example 3

[0066] PFAS removal efficiency of HPB at an addition of 1 g / L and a 5-minute equilibration time.

[0067] The operation is the same as in Example 2. After shaking for 5 minutes, samples are taken for testing.

[0068] Example 4

[0069] PFAS removal efficiency of HPB under neutral conditions.

[0070] The procedure is the same as in Example 3, but without adding acid. After shaking for 5 minutes, samples are taken for testing.

[0071] Example 5

[0072] PFAS removal efficiency of HPB with the addition of 0.1% (volume ratio) 98% pure acetic acid.

[0073] The procedure is the same as in Example 3: after adding 0.1% acetic acid, shake for 5 minutes, and then take a sample for testing.

[0074] Example 6

[0075] The PFAS removal efficiency of HPB under the addition of 0.1% concentration of 37% ammonia water.

[0076] The procedure is the same as in Example 3: after adding 0.1% of 37% ammonia water, shake for 5 minutes, and then take a sample for testing.

[0077] Examples 1-6 show that the efficiency of HPB in removing PFAS from water is highly dependent on application conditions. Excellent removal of both long-chain and short-chain PFAS is achieved under neutral or acidic conditions. Removal is less effective under alkaline conditions. Examples 1-6 also demonstrate that HPB adsorption kinetics are rapid, reaching equilibrium in just 5 minutes, with no difference in removal efficiency compared to after 24 hours of equilibrium.

[0078] Table 5: PFAS Removal Efficiency .

[0079] [PFOA] and [PABS] initial concentration 10 μg / L, [HPB] dosage 1 g / L, equilibration time 5 min.

[0080] Example 7

[0081] PFAS removal efficiency of polystyrene-divinylbenzene microspheres.

[0082] The procedure was the same as in Example 2, except that the adsorbent was replaced with 1g of polystyrene-divinylbenzene microspheres. Since the microspheres are non-wetting in water, they float on the water surface. After 24 hours, regardless of whether formic acid was added to adjust the pH, there was no significant PFAS removal effect.

[0083] Example 8

[0084] HPB can be reused.

[0085] (1) Reuse: Measure 1L of water and add 1mL of formic acid, add 100uL of PFOA standard solution (10μg / mL), weigh 10mg of adsorbent HPB and add it to the water, shake for 30s and let stand for 24h. Filter the water through a 0.22μm filter membrane. The HPB adsorbent is retained on the filter membrane. Then rinse with 20mL of methanol and 20mL of water in sequence, and then dry in an oven. Collect the dried HPB adsorbent and conduct a second and third reuse experiment.

[0086] (2) Reuse: Measure 1L of water and add 1mL of formic acid, add 100uL of 10μg / mL PFBS standard solution, weigh 10mg of adsorbent HPB and add it to the water, shake for 30s and let stand for 24h. Filter the water through a 0.22μm filter membrane. The HPB adsorbent is retained on the filter membrane. Rinse with 20mL of methanol, collect the regenerated HPB adsorbent, and conduct a second and third reuse experiment.

[0087] Elution recovery rate R = C2 × V2 / M × 100%. R (%): elution recovery rate; C2 (ng / L): concentration of PFASs eluted from the adsorbent with methanol; V2 (mL): methanol elution volume; M (ng): mass of PFASs adsorbed by the adsorbent.

[0088] Table 6: Test results of PFOA and PFBS in HPB eluent .

[0089] Table 7: Adsorption and retention rates of regenerated HPB for PFAS compared to fresh HPB .

[0090] Table 6 shows the process of washing the HPB adsorbent with methanol to recover PFAS, collecting the eluent, and testing the PFAS content. In the first collection, the recovery rates of PFOA and PFBS in the eluent were both above 90%. After HPB was reused three times, the recovery rates of PFOA and PFBS in the eluent were still above 75%. The results show that at least 77% of PFAS can be recovered, which has excellent economic value. It also reduces the environmental pollution caused by the production of new PFAS.

[0091] Table 7 shows that HPB can be reused after eluting PFSAs with methanol. The adsorption capacity of PFOA was 102% of the first time in the second reuse and 88% of the first time in the third reuse; the adsorption capacity of PFBS was 93% of the first time in the second reuse and 88% of the first time in the third reuse. The regeneration and reuse of HPB adsorbent helps reduce the production cost of water purification, making it more economical and environmentally friendly.

Claims

1. A method for adsorbing perfluorinated and polyfluoroalkyl compounds from an aqueous solution, characterized in that, The method includes: S1. Adjust the pH of the aqueous solution containing perfluorinated and polyfluorinated alkyl compounds to below 7; S2. After pH adjustment, polystyrene-divinylbenzene microsphere modifier is added to the aqueous solution. The polystyrene-divinylbenzene microsphere modifier is a hydrophilic group modified polystyrene-divinylbenzene microsphere modifier. Then, the mixture is stirred at room temperature until the perfluorinated and polyfluoroalkyl compounds dissolved in the water are completely adsorbed onto the polystyrene-divinylbenzene microsphere modifier.

2. The method according to claim 1, characterized in that, The concentration of the polystyrene-divinylbenzene microsphere modifier is 10 mg / L to 10 g / L.

3. The method according to claim 1 or 2, characterized in that, The polystyrene-divinylbenzene microsphere modified product is an N-vinylpyrrolidone modified polystyrene-divinylbenzene microsphere modified product.

4. The method according to claim 1, characterized in that, Perfluorinated and polyfluoroalkyl compounds are one or a mixture of several of the following: perfluorooctane carboxylic acid, perfluorooctane sulfonic acid, perfluorobutane carboxylic acid, perfluorobutyl sulfonic acid, hexafluoropropylene oxide dimer acid, perfluorohexane sulfonic acid, and 6:2-fluorohydroxy alcohol.

5. The method according to claim 1, characterized in that, The pH of the aqueous solution after pH adjustment is 3-7.

6. The method according to claim 1, characterized in that, The pH adjuster for aqueous solutions is formic acid, acetic acid, or hydrochloric acid.

7. The application of polystyrene-divinylbenzene microspheres modified for adsorbing perfluorinated and polyfluoroalkyl compounds in aqueous solutions, characterized in that... The modified polystyrene-divinylbenzene microspheres are hydrophilic modified polystyrene-divinylbenzene microspheres.

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