A kind of water body in all perfluoroalkyl compound solid phase extraction column filler and its synthesis method and application

Abstract

This invention discloses a solid-phase extraction (SPE) column packing material for polyfluoroalkyl (PFOA) compounds in water, its synthesis method, and its applications. The SPE column packing material is a COF material polymerized from 1,3,5-tris(p-formylphenyl)benzene (TFPB) and triaminoguanidine hydrochloride (TGcl) in the presence of a deprotonated solvent. The SPE column packing material prepared by this invention achieves an adsorption and enrichment rate of 95.4% for PFOA and PFOS in water, and a solid-phase extraction recovery rate of 92.7%, meeting the pretreatment requirements for PFAS detection in various surface waters, groundwaters, and industrial wastewater in environmental monitoring.

Description

Technical Field

[0001] This invention relates to the fields of environmental functional materials and pretreatment detection technology for organic pollutants in water, specifically to a method for synthesizing and applying a solid-phase extraction column packing for polyfluoroalkyl compounds in water. Background Technology

[0002] Perfluoroalkyl compounds (PFAS) are a class of synthetic organofluorine compounds with extremely high chemical stability and hydrophobic and oleophobic properties, widely used in many industrial fields such as fire-fighting foam, surface coating, food packaging, electroplating, and textiles. Among them, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are the most representative long-chain PFAS pollutants, exhibiting environmental persistence, bioaccumulation, and high toxicity, and can cause health risks such as liver damage, immune disorders, endocrine disorders, and even cancer. Currently, PFOS is listed in Annex B of the Stockholm Convention, and PFOA has been included in the strict control lists of many countries and regions around the world.

[0003] Industrial emissions, fire site leaks, wastewater treatment plant effluent discharge, and groundwater migration contribute to the widespread distribution of PFOA and PFOS in surface water, groundwater, and industrial wastewater. The concentration of PFAS in environmental water bodies is generally in the range of ng / L to μg / L, making direct detection by instruments such as liquid chromatography-tandem mass spectrometry (LC-MS / MS) and high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) impossible. Pretreatment techniques, such as solid-phase extraction (SPE), are necessary for enrichment and purification of the water. The performance of the SPE packing material directly determines the enrichment efficiency and detection accuracy of the pollutants.

[0004] Commercially available SPE column packing materials mainly include reversed-phase adsorbents (such as C18 and HLB), weak anion exchange adsorbents (such as WAX), and graphitized carbon black. For anionic PFAS such as PFOA and PFOS, WAX columns are one of the most widely used packing materials, achieving adsorption through a dual mechanism of reversed-phase adsorption and anion exchange. However, water often contains coexisting anions such as chloride, sulfate, and nitrate, which significantly interfere with electrostatic interactions, compress the electric double layer, and weaken the affinity of anion exchange sites for PFAS carboxylates or sulfonates, leading to a sharp decline in recovery rates. Furthermore, reversed-phase packing materials such as C18 lack specific recognition sites, resulting in unsatisfactory enrichment efficiency and selectivity for PFAS in water.

[0005] In recent years, novel functional materials such as metal-organic frameworks (MOFs), molecularly imprinted polymers (MIPs), and covalent organic frameworks (COFs) have been gradually applied to the adsorption and enrichment of pollutants in PFAS. Among them, COF materials have advantages such as designable structure, tunable pore size, controllable functional groups, and excellent chemical stability, making them suitable for adsorption scenarios of pollutants in water bodies. However, the synthesis of existing COF materials for PFAS generally suffers from problems such as high temperature and pressure, the need for toxic organic solvents, high preparation costs, and difficulty in large-scale production. Moreover, most materials have poor adaptability to complex saline water bodies and unstable recovery rates.

[0006] Therefore, developing a solid-phase extraction packing material with mild synthesis conditions, controllable cost, and high enrichment efficiency for PFOA and PFOS is of great practical significance for the accurate detection of PFAS in water and environmental monitoring. Summary of the Invention

[0007] To overcome the shortcomings of the existing technology, the present invention aims to provide a method for synthesizing and applying a solid-phase extraction column packing material for polyfluoroalkyl compounds in water, thereby solving the technical problems of low recovery rate and low enrichment rate of PFOA and PFOS of traditional packing materials.

[0008] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a solid-phase extraction (SPE) column packing material for polyfluoroalkyl compounds in water, wherein the SPE column packing material is a COF material obtained by polymerization of 1,3,5-tris(p-formylphenyl)benzene (TFPB) and triaminoguanidine hydrochloride (TGcl) in the presence of a deprotonating solvent.

[0009] Preferably, the deprotonating solvent is anhydrous sodium acetate, and the molar ratio of TFPB, monomer TGcl and deprotonating solvent is 1:1:(2~4).

[0010] Secondly, the present invention provides a method for synthesizing a solid-phase extraction column packing material for perfluoroalkyl compounds in water, specifically comprising the following steps: S1. Aldehyde phase preparation: Add monomer TFPB to a compounded organic solvent, disperse it thoroughly, and then perform ultrasonic pre-activation treatment for a certain period of time to obtain aldehyde phase solution; S2. Preparation of amine phase: Dissolve monomer TGcl in pure water, add anhydrous sodium acetate, and sonicate for a certain time to obtain amine phase solution; S3. Polymerization reaction and post-treatment: The amine phase solution from step S2 is added dropwise to the aldehyde phase solution from step S1. The mixture is magnetically stirred at room temperature for a certain time. After centrifugation, washing, and drying, a solid-phase extraction column packing is obtained.

[0011] Preferably, the molar ratio of the monomer TFPB, monomer TGcl, and anhydrous sodium acetate is 1:1:(2~4). Preferably, the organic solvent used in step S1 is a mixed solvent of 1,4-dioxane and acetic acid, more preferably a mixed solvent of 1,4-dioxane and acetic acid in a volume ratio of 1:1. Preferably, the ultrasonic pre-activation treatment time in step S1 is 15~60 min, more preferably 30 min; Preferably, the ultrasonic treatment time in step S2 is 10-30 min, more preferably 10 min; Preferably, the room temperature magnetic stirring reaction time in step S3 is 4-8 hours and the magnetic stirring speed is 250-350 rpm, more preferably 6 hours and 300 rpm; The centrifugation speed is 7000~9000 rpm, and the centrifugation time is 8~12 min, more preferably 8000 rpm and 10 min; The washing process involves sequentially washing with deionized water, ethanol, and acetone. The vacuum drying temperature is 75~85℃ and the time is 10~14 h, more preferably 80℃ and 12 h.

[0012] Thirdly, the present invention provides a solid-phase extraction column, wherein the solid-phase extraction column comprises a solid-phase extraction column packing material for polyfluoroalkyl compounds in water.

[0013] Preferably, the solid phase extraction column is obtained by filling a solid phase extraction column packing material into a hollow polypropylene or polyethylene column tube, and then assembling sieve plates at both ends of the column tube to fix the packing material.

[0014] Preferably, the packing amount of the solid phase extraction column packing is controlled at 50~200 mg.

[0015] Fourthly, the present invention provides an application of a solid-phase extraction column packing material for polyfluoroalkyl compounds in water in the removal of PFAS enriched in water. Preferably, the method of application is as follows: passing the water sample through a solid phase extraction column at a certain flow rate, then washing the impurities with deionized water or low-salt buffer, and then eluting the target PFOA and PFOS with elution buffer; Preferably, the pH of the water is 3-9 and the flow rate is 1-5 mL / min; the eluent is a mixed solution of water and methanol containing 0.1% sodium chloride, wherein the volume ratio of water containing 0.1% sodium chloride to methanol is 95:5; Preferably, after the eluent elutes the target PFOA and PFOS, it is concentrated by nitrogen blowing and then detected by HPLC-MS / MS.

[0016] This invention introduces anhydrous sodium acetate as a deprotonating agent, which can gently dissociate TGcl hydrochloride, releasing highly active amino sites while maintaining a weakly acidic environment in the system. This is beneficial for the reversible formation of imine bonds and framework rearrangement, giving the prepared COF material a regular macroporous structure and abundant amino and imine functional groups. The COF material can specifically bind to the fluorocarbon chains and anionic functional groups of PFOA and PFOS through a triple synergistic mechanism of hydrophobic interactions, hydrogen bonding, and electrostatic adsorption, effectively resisting interference from conventional anions in water bodies and significantly improving the enrichment efficiency and recovery rate of PFAS in small column packing materials in complex water bodies.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The synthesis process is green and mild: the entire process is carried out at room temperature, without the need for high temperature and high pressure equipment, without the use of highly toxic organic solvents, and is simple to operate, with low energy consumption and controllable cost. It can be prepared on a large scale and is suitable for industrial production and routine laboratory applications. 2. Strong anti-interference ability and high enrichment efficiency: The adsorption and enrichment rate of PFOA and PFOS reaches 95.4%, and the solid phase extraction recovery rate is 92.7%, which is better than the traditional commercial WAX column (adsorption and enrichment rate <85.2%, recovery rate <82.4%).

[0018] 3. Wide water body adaptability: It can be stably applied to conventional water bodies with pH 3~9 and complex saline water bodies, meeting the pretreatment requirements for PFAS detection of various surface water, groundwater and industrial wastewater in environmental monitoring. Detailed Implementation

[0019] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0020] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0021] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±1℃. Example 1

[0022] A solid-phase extraction column packing material for perfluoroalkyl compounds in water is synthesized as follows: S1. Aldehyde phase preparation: Weigh 0.4 mmol of aldehyde monomer (TFPB) and add it to a 20 mL reaction flask. Add a mixed solvent of 1,4-dioxane and 6 M acetic acid in a volume ratio of 1:1 (total volume 4 mL) to form a uniform suspension system. Sonicate for 30 min at room temperature. S2, Amine Phase Preparation: Take another 20 mL reaction flask, dissolve the amine monomer (TGcl 0.4 mmol) in 4 mL of deionized water, then add 1.2 mmol (100 mg) of anhydrous sodium acetate (NaOAc), and sonicate for 10 min to promote dissolution; S3. Polymerization reaction and post-processing: The amine phase solution was slowly added to the aldehyde phase system and the reaction was carried out under magnetic stirring at 300 rpm for 6 h at room temperature. After the reaction was completed, the solid product was collected by centrifugation (centrifugation speed 8000 rpm, time 10 min). The product was washed repeatedly with deionized water, ethanol and acetone to remove unreacted monomers and small molecule impurities. Finally, it was dried in a vacuum drying oven at 80°C for 12 h to obtain the target COF powder material, which is the solid phase extraction column packing. Example 2

[0023] A solid-phase extraction column packing material for perfluoroalkyl compounds in water is synthesized as follows: S1. Aldehyde phase preparation: Weigh 0.4 mmol of aldehyde monomer (TFPB) and add it to a 20 mL reaction flask. Add a mixed solvent of 1,4-dioxane and 6 M acetic acid in a volume ratio of 1:1 (total volume 4 mL) to form a uniform suspension system. Sonicate for 30 min at room temperature. S2, Amine Phase Preparation: Take another 20 mL reaction flask, dissolve the amine monomer (TGcl 0.4 mmol) in 4 mL of deionized water, then add 0.8 mmol (100 mg) of anhydrous sodium acetate (NaOAc), and sonicate for 10 min to promote dissolution; S3. Polymerization reaction and post-processing: The amine phase solution was slowly added to the aldehyde phase system and the reaction was carried out under magnetic stirring at 300 rpm for 6 h at room temperature. After the reaction was completed, the solid product was collected by centrifugation (centrifugation speed 8000 rpm, time 10 min). The product was washed repeatedly with deionized water, ethanol and acetone to remove unreacted monomers and small molecule impurities. Finally, it was dried in a vacuum drying oven at 80°C for 12 h to obtain the target COF powder material, which is the solid phase extraction column packing. Example 3

[0024] A solid-phase extraction column packing material for perfluoroalkyl compounds in water is synthesized as follows: S1. Aldehyde phase preparation: Weigh 0.4 mmol of aldehyde monomer (TFPB) and add it to a 20 mL reaction flask. Add a mixed solvent of 1,4-dioxane and 6 M acetic acid in a volume ratio of 1:1 (total volume 4 mL) to form a uniform suspension system. Sonicate for 30 min at room temperature. S2, Amine Phase Preparation: Take another 20 mL reaction flask, dissolve the amine monomer (TGcl 0.4 mmol) in 4 mL of deionized water, then add 1.6 mmol (100 mg) of anhydrous sodium acetate (NaOAc), and sonicate for 10 min to promote dissolution; S3. Polymerization reaction and post-processing: The amine phase solution was slowly added to the aldehyde phase system and the reaction was carried out under magnetic stirring at 300 rpm for 6 h at room temperature. After the reaction was completed, the solid product was collected by centrifugation (centrifugation speed 8000 rpm, time 10 min). The product was washed repeatedly with deionized water, ethanol and acetone to remove unreacted monomers and small molecule impurities. Finally, it was dried in a vacuum drying oven at 80°C for 12 h to obtain the target COF powder material, which is the solid phase extraction column packing.

[0025] Comparative Example 1 (without NaOAc) A solid-phase extraction column packing material for perfluoroalkyl compounds in water is synthesized as follows: S1. Aldehyde phase preparation: Weigh 0.4 mmol of aldehyde monomer (TFPB) and add it to a 20 mL reaction flask. Add a mixed solvent of 1,4-dioxane and 6 M acetic acid in a volume ratio of 1:1 (total volume 4 mL) to form a uniform suspension system. Sonicate for 30 min at room temperature. S2, Amine Phase Preparation: Take another 20 mL reaction flask, dissolve the amine monomer (TGcl 0.4 mmol) in 4 mL of deionized water, and sonicate for 10 min to promote dissolution; S3. Polymerization reaction and post-processing: The amine phase solution was slowly added to the aldehyde phase system and the reaction was carried out under magnetic stirring at 300 rpm for 6 h at room temperature. After the reaction was completed, the solid product was collected by centrifugation (centrifugation speed 8000 rpm, time 10 min). The product was washed repeatedly with deionized water, ethanol and acetone to remove unreacted monomers and small molecule impurities. Finally, it was dried in a vacuum drying oven at 80℃ for 12 h to obtain the target COF powder material, which is the solid phase extraction column packing.

[0026] Comparative Example 2 (using sodium hydroxide as an alkaline substance instead of NaOAc) A solid-phase extraction column packing material for perfluoroalkyl compounds in water is synthesized as follows: S1. Aldehyde phase preparation: Weigh 0.4 mmol of aldehyde monomer (TFPB) and add it to a 20 mL reaction flask. Add a mixed solvent of 1,4-dioxane and 6 M acetic acid in a volume ratio of 1:1 (total volume 4 mL) to form a uniform suspension system. Sonicate for 30 min at room temperature. S2, Amine Phase Preparation: Take another 20 mL reaction flask, dissolve the amine monomer (TGcl 0.4 mmol) in 4 mL of deionized water, then add 1.6 mmol (100 mg) of sodium hydroxide (NaOH) and sonicate for 10 min to promote dissolution; S3. Polymerization reaction and post-processing: The amine phase solution was slowly added to the aldehyde phase system and the reaction was carried out under magnetic stirring at 300 rpm for 6 h at room temperature. After the reaction was completed, the solid product was collected by centrifugation (centrifugation speed 8000 rpm, time 10 min). The product was washed repeatedly with deionized water, ethanol and acetone to remove unreacted monomers and small molecule impurities. Finally, it was dried in a vacuum drying oven at 80°C for 12 h to obtain the target COF powder material, which is the solid phase extraction column packing.

[0027] Comparative Example 3 Extraction and enrichment experiments were conducted using a commercially available Oasis WAX solid-phase extraction column (150 mg, 6 mL, Waters, USA).

[0028] Performance testing: Adsorption and enrichment performance: The synthesized solid-phase extraction (SPE) column packing material (COF material) was packed into an empty SPE column with an inner diameter of 12 mm to assemble a PFAS adsorption column. The specific procedure was as follows: retaining the bottom sealing gasket of the empty SPE column, 150 mg of packing material was slowly added to the empty column while wetting it with methanol. The top of the column was then sealed tightly to obtain the laboratory-made PFAS adsorption column. Comparative Example 3 used a commercially available Oasis WAX solid-phase extraction column. Before use, the column was purified with methanol (20 mL) and then with deionized water (20 mL) to remove impurities and prevent interference with subsequent PFAS adsorption experiments. Then, 100 mL of three water samples (pure water, surface water, and groundwater) contaminated with PFAS (PFOA and PFOS concentrations of 20 µg / L, respectively) were pumped into the column at a flow rate of 3 mL / min. The filtrate was collected and analyzed by HPLC-MS / MS to calculate the adsorption enrichment rate.

[0029] 2. Solid-phase extraction recovery rate: The used solid-phase extraction column was regenerated using a 0.1% NaCl aqueous solution / methanol (95:5, v:v) mixture. Specifically, the column was washed with 5 mL of pure water to remove excess salt; then eluted twice with 5 mL of the 0.1% NaCl aqueous solution / methanol (95:5, v:v) mixture. The eluent was collected, purged with nitrogen at 40 °C, and brought to a final volume of 1.0 mL. 5 ng of internal standard (added before instrument analysis) was added to achieve the preset concentration. The concentrations of target PFOA and PFOS were then analyzed using HPLC-MS / MS to calculate the solid-phase extraction recovery rate.

[0030]

[0031] The results above show that, compared with Comparative Examples 1-3, the solid-phase extraction column packing materials prepared in Examples 1-3 introduce anhydrous sodium acetate as a deprotonating agent, which can gently dissociate TGcl hydrochloride, release highly active amino sites, and maintain a weakly acidic environment in the system. This is conducive to the reversible formation of imine bonds and framework rearrangement, so that the prepared COF material has a regular macroporous structure and abundant amino and imine functional groups. COF materials can specifically bind to the fluorocarbon chains and anionic functional groups of PFOA and PFOS through a triple synergistic mechanism of hydrophobic interaction, hydrogen bonding, and electrostatic adsorption. This effectively resists interference from conventional ions and soluble organic matter in water. In three types of water bodies (pure water, surface water, and groundwater), the adsorption and enrichment rates of PFOA and PFOS are 89.2%–95.1% and 87.1%–95.4%, respectively, and the recovery rates of solid-phase extraction are 86.2%–92.7% and 84.3%–90.3%, respectively. COF materials have good adsorption and enrichment and solid-phase extraction recovery effects on PFAS, which are higher than those of comparative examples and commercial extraction columns.

[0032] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A solid-phase extraction column packing material for polyfluoroalkyl compounds in water, characterized in that, The solid-phase extraction column packing material is a COF material obtained by polymerization of 1,3,5-tris(p-formylphenyl)benzene (TFPB) and triaminoguanidine hydrochloride (TGcl) in the presence of a deprotonating solvent.

2. The solid-phase extraction column packing for polyfluoroalkyl compounds in water according to claim 1, characterized in that, The deprotonating solvent is anhydrous sodium acetate, and the molar ratio of TFPB, monomer TGcl and deprotonating solvent is 1:1:(2~4).

3. A method for synthesizing the solid-phase extraction column packing material for polyfluoroalkyl compounds in water as described in claim 1 or 2, characterized in that, Specifically, the following steps are included: S1. Aldehyde phase preparation: Add monomer TFPB to a compounded organic solvent, disperse it thoroughly, and then perform ultrasonic pre-activation treatment for a certain period of time to obtain aldehyde phase solution; S2. Preparation of amine phase: Dissolve monomer TGcl in pure water, add anhydrous sodium acetate, and sonicate for a certain time to obtain amine phase solution; S3. Polymerization reaction and post-treatment: The amine phase solution from step S2 is added dropwise to the aldehyde phase solution from step S1. The mixture is magnetically stirred at room temperature for a certain time. After centrifugation, washing, and drying, a solid-phase extraction column packing is obtained.

4. The method for synthesizing the solid-phase extraction column packing material for polyfluoroalkyl compounds in water according to claim 3, characterized in that, The molar ratio of the monomer TFPB, monomer TGcl and anhydrous sodium acetate is 1:1:(2~4). The organic solvent used in step S1 is a mixture of 1,4-dioxane and acetic acid. The ultrasonic pre-activation treatment in step S1 takes 15-60 minutes; The ultrasonic treatment time in step S2 is 10~30 min; The room temperature magnetic stirring reaction time in step S3 is 4-8 hours, and the magnetic stirring speed is 250-350 rpm; the centrifugation speed is 7000-9000 rpm, and the centrifugation time is 8-12 minutes; the washing is carried out by washing with deionized water, ethanol and acetone in sequence; the vacuum drying temperature is 75-85℃, and the time is 10-14 hours.

5. The method for synthesizing the solid-phase extraction column packing material for polyfluoroalkyl compounds in water according to claim 4, characterized in that, The organic solvent used in step S1 is a mixture of 1,4-dioxane and acetic acid in a volume ratio of 1:1; the ultrasonic pre-activation treatment in step S1 lasts for 30 min; the ultrasonic treatment in step S2 lasts for 10 min; the room temperature magnetic stirring reaction in step S3 lasts for 6 h at a magnetic stirring speed of 300 rpm; the centrifugation speed is 8000 rpm for 10 min; and the vacuum drying temperature is 80℃ for 12 h.

6. A solid-phase extraction column, characterized in that, The solid-phase extraction column comprises the solid-phase extraction column packing material for polyfluoroalkyl compounds in water as described in claim 1 or 2, or the solid-phase extraction column packing material for polyfluoroalkyl compounds in water as described in any one of claims 3 to 5, prepared by the synthesis method of the solid-phase extraction column packing material for polyfluoroalkyl compounds in water.

7. The solid-phase extraction column according to claim 6, characterized in that, The solid-phase extraction column is obtained by filling a solid-phase extraction column packing material into a hollow polypropylene or polyethylene column tube, and then assembling sieve plates at both ends of the column tube to fix the packing material.

8. The application of a solid-phase extraction column packing material prepared by the synthesis method of the solid-phase extraction column packing material for polyfluoroalkyl compounds in water as described in claim 1 or 2, or the solid-phase extraction column packing material for polyfluoroalkyl compounds in water as described in any one of claims 3 to 5, in the removal of PFAS enriched in water.

9. The application of the solid-phase extraction column packing material according to claim 8 in the removal of PFAS enriched in water, characterized in that, The method described is as follows: water samples are passed through a solid-phase extraction column at a certain flow rate, impurities are washed with deionized water or low-salt buffer, and then the target PFOA and PFOS are eluted with elution buffer.

10. The application of the solid-phase extraction column packing material according to claim 9 in the removal of PFAS enriched in water, characterized in that, The pH of the water body is 3-9, and the flow rate is 1-5 mL / min; the eluent is a mixed solution of water and methanol containing 0.1% sodium chloride, wherein the volume ratio of water containing 0.1% sodium chloride to methanol is 95:5; after eluting the target PFOA and PFOS, the eluent is concentrated by nitrogen blowing and then detected by HPLC-MS / MS.

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