Preparation of nanofiber membranes that can adsorb a variety of perfluoro and polyfluoroalkyl substances

Abstract

The application discloses a kind of nanofiber membrane of adsorbing multiple kinds of perfluoro and polyfluoro alkyl substance preparation, using electrospinning and glutaraldehyde crosslinking method obtains quaternary ammonium chitosan and polyvinyl alcohol mixed nanofiber membrane of spinning, direct immersion in environmental water can be used, can simultaneously adsorb and remove short-chain perfluorocarboxylic acid, long-chain perfluorocarboxylic acid, short-chain perfluorosulfonic acid, long-chain perfluorosulfonic acid, perfluoroalkyl ether carboxylic acid, perfluoro-n-oxa-butane sulfonate and chlorinated polyfluoro ether sulfonate and other multiple types of perfluoro and polyfluoro alkyl substance in tap water, surface water, groundwater, domestic sewage, industrial wastewater, agricultural wastewater or medical wastewater.The adsorption removal is completed, and it is taken out from environmental water, and solid-liquid separation is completed.The existing adsorbent has more kinds of perfluoro and polyfluoro alkyl substance that can be simultaneously adsorbed and removed, higher adsorption removal efficiency for short-chain perfluoro substance, and wider environmental water matrix.

Description

TECHNICAL FIELD

[0001] The application provides a preparation method of a nanofiber membrane capable of simultaneously adsorbing and removing various perfluoroalkyl and polyfluoroalkyl substances in environmental water, and belongs to the technical field of environmental water treatment. BACKGROUND

[0002] Due to environmental persistence, bioaccumulation, and multiple hazards to ecology and health, emerging pollutant prevention and control is a proposition that the whole world pays great attention to. Typical persistent pollutants are emerging pollutants most closely related to ecological environment safety and human health, and are included in the "List of Key Controlled Emerging Pollutants (2023 Edition)" issued by the Ministry of Ecology and Environment and other six ministries. They are the first batch of emerging pollutants that must be controlled according to laws and regulations. Among them, perfluoroalkyl and polyfluoroalkyl substances are one of the emerging pollutants most closely related to human production and life and most widely contacted. They are widely used in more than 200 fields from industrial mining to food production and fire-fighting foam. They are released to the environment through solid, liquid and gas waste generated during the production process, and are widely distributed in air, soil, surface water, sediments and other media, and finally accumulate in environmental water. Environmental water is the key medium for the transport of perfluoroalkyl and polyfluoroalkyl substances in the environment. The detection concentration of traditional and new perfluoroalkyl and polyfluoroalkyl substances mainly including perfluorobutyric acid, perfluorobutane sulfonic acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluorohexane sulfonic acid, perfluorooctanoic acid, perfluorooctane sulfonic acid and perfluoro(2-methyl-3-oxahexanoic acid) ammonium is several ng / L to several million ng / L. Perfluoroalkyl and polyfluoroalkyl substances have extremely high stability and can enter the human body through the food chain, directly affecting human health. Therefore, the adsorption and removal of perfluoroalkyl and polyfluoroalkyl substances in environmental water is one of the important propositions in the field of environmental water treatment technology.

[0003] Perfluoroalkyl and polyfluoroalkyl substances have many types and large differences in physicochemical properties. They can be divided into strong polarity, medium polarity and strong hydrophobic perfluoroalkyl and polyfluoroalkyl substances according to the n-octanol / water partition coefficient, making it extremely challenging to simultaneously adsorb these perfluoroalkyl and polyfluoroalkyl substances with large differences in properties. Conventional adsorption materials such as granular activated carbon are suitable for treating long-chain perfluoroalkyl and polyfluoroalkyl substances with strong hydrophobicity, but the adsorption efficiency of short-chain perfluoroalkyl and polyfluoroalkyl substances is very low (<50%). This is because the carbon-fluorine chain length of short-chain perfluoroalkyl and polyfluoroalkyl substances is not as long as that of long-chain perfluoroalkyl and polyfluoroalkyl substances, and they cannot be effectively removed by hydrophobic interaction. In addition, the conditions required for preparing these carbon materials are harsh, and toxic / hazardous solvents are used, and used granular carbon materials are not easy to separate, causing secondary pollution to the environment.

[0004] The existing research and development of new adsorbents for adsorbing and removing perfluoroalkyl substances in environmental water include carbon materials functionalized with various functional groups (such as amino and carboxyl groups), cation-modified mineral materials, natural polymer materials (such as cellulose and beta-cyclodextrin), metal organic frameworks, covalent organic frameworks and other prepared adsorbents. These adsorbents are often used for adsorbing and removing perfluorocarboxylic acids, perfluorosulfonic acids, perfluoroalkyl ether carboxylic acids or perfluoroalkoxy benzene sulfonate in environmental water. However, there are few studies on the efficient simultaneous adsorption and removal of multiple perfluoroalkyl substances in environmental water. In addition, when adsorbing and removing multiple perfluoroalkyl substances with different polarities (different carbon chain lengths), it is difficult to efficiently adsorb and remove strongly polar (short-chain) perfluoroalkyl substances. Moreover, after the adsorbents developed by the existing research and development are used to adsorb target substances, secondary separation processes such as centrifugal separation, magnetic separation and membrane filtration are often required, which reduces the operation simplicity of the removal method. Therefore, considering the current situation of the co-pollution of multiple perfluoroalkyl substances in environmental water, it is of great practical significance to develop efficient adsorbents for simultaneously removing multiple perfluoroalkyl substances in environmental water. SUMMARY

[0005] TECHNICAL PROBLEM: The purpose of the present application is to prepare a method for preparing a nanofiber membrane that can adsorb multiple perfluoroalkyl substances, so that it can simultaneously adsorb and remove multiple perfluoroalkyl substance pollution.

[0006] TECHNICAL SCHEME: The method for preparing a nanofiber membrane that can adsorb multiple perfluoroalkyl substances of the present application is achieved by the following technical scheme:

[0007] S1: preparing quaternized chitosan;

[0008] S2: preparing quaternized chitosan-polyvinyl alcohol composite nanofiber membrane by electrospinning method;

[0009] S3: preparing quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane by glutaraldehyde chemical cross-linking method.

[0010] The preparation steps of the quaternized chitosan include:

[0011] S1.1: dissolving chitosan in v / v = 0.01% to 0.8% acetic acid aqueous solution to obtain chitosan solution, wherein the concentration of chitosan is 20 to 50 g / L;

[0012] S1.2: 2,3-epoxypropyl trimethyl ammonium chloride is dissolved in deionized water to obtain a 2,3-epoxypropyl trimethyl ammonium chloride solution, wherein the concentration of the 2,3-epoxypropyl trimethyl ammonium chloride solution is 0.60-1.2 g / mL;

[0013] S1.3: under the condition of heating and stirring at 60℃ water bath, 5%-25% (v / v) of the 2,3-epoxypropyl trimethyl ammonium chloride solution is added dropwise into the chitosan solution prepared in step S1.1 to obtain a clear and uniform mixed solution;

[0014] S1.4: after centrifugation of the obtained mixed solution, the supernatant is taken and poured into ethanol / acetone (1:1, v / v) with slow stirring, thereby producing a white gel-like precipitate;

[0015] S1.5: after washing the obtained white gel-like precipitate with anhydrous ethanol, vacuum drying is performed to obtain the quaternized chitosan.

[0016] The steps of the electrospinning method for preparing the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane include:

[0017] S2.1: quaternized chitosan and polyvinyl alcohol are respectively dissolved in 20%-80% (v / v) acetic acid solution to obtain a quaternized chitosan-polyvinyl alcohol composite solution, wherein the concentration of the quaternized chitosan is 0.1-20 g / L, the concentration of the polyvinyl alcohol is 80-100 g / L, and the mass ratio w / w of the quaternized chitosan to the polyvinyl alcohol is 5%-25%;

[0018] S2.2: the quaternized chitosan-polyvinyl alcohol composite solution is placed in a propeller, the distance from the nozzle to the receiving screen is adjusted, and the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane is prepared by electrospinning under a high-voltage electrostatic field.

[0019] The method for preparing the quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane from the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane by the glutaraldehyde chemical cross-linking method is as follows:

[0020] Glutaraldehyde with a concentration of 0.01-0.05 mol / L and dilute hydrochloric acid with a concentration of 0.1-2 mol / L are mixed at a volume ratio of 0.5:1-2:1 to obtain a cross-linking solvent. After the cross-linking solvent is placed at the bottom of a sealed container, the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane is hung in the sealed container. The sealed container is placed at 60-80℃, and after 0.5-3 h, the quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is obtained.

[0021] The method for adsorbing and removing perfluoroalkyl and polyfluoroalkyl substances in environmental water by the nanofiber membrane is: putting 200-500 mg of quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane into each liter of environmental water sample, and fully immersing the nanofiber membrane in the environmental water sample; after adsorption is completed, the composite nanofiber membrane is directly taken out from the environmental water sample.

[0022] The environmental water includes groundwater, surface water, tap water, domestic sewage, industrial sewage, agricultural sewage or medical sewage.

[0023] The perfluoroalkyl and polyfluoroalkyl substances include short-chain perfluorocarboxylic acids, long-chain perfluorocarboxylic acids, short-chain perfluorosulfonic acids, long-chain perfluorosulfonic acids, perfluoroalkyl ether carboxylic acids, perfluoroalkyl ether sulfonates, chlorinated polyfluoroether sulfonates.

[0024] Beneficial effects: the application discloses a preparation method and application of a nanofiber membrane capable of adsorbing various perfluoroalkyl and polyfluoroalkyl substances, and compared with existing adsorption materials, the nanofiber membrane has the following advantages and effects:

[0025] (1) The quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane can adsorb various perfluoroalkyl and polyfluoroalkyl substances by providing multiple adsorption mechanisms, and is suitable for multiple sample substrates.

[0026] The prepared quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane can simultaneously adsorb perfluoroalkyl and polyfluoroalkyl substances including short-chain perfluorocarboxylic acids, long-chain perfluorocarboxylic acids, short-chain perfluorosulfonic acids, long-chain perfluorosulfonic acids, perfluoroalkyl ether carboxylic acids, perfluoroalkyl ether sulfonates and chlorinated polyfluoroether sulfonates, compared with existing adsorption materials, the adsorption target species of the existing adsorption materials are concentrated in traditional long-chain perfluoroalkyl and polyfluoroalkyl substances or a small number of short-chain perfluoroalkyl and polyfluoroalkyl substances, and the prepared quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane can adsorb various perfluoroalkyl and polyfluoroalkyl substances.

[0027] The quaternary ammonium chitosan-polyvinyl alcohol composite nanofiber membrane can form adsorption with perfluoro and polyfluoro alkyl substances through strong electrostatic interaction and hydrophobic interaction, and further cross-linking with glutaraldehyde, which enhances the hydrophobic interaction between the quaternary ammonium chitosan-polyvinyl alcohol composite nanofiber membrane and perfluoro and polyfluoro alkyl substances, so that the adsorption efficiency of various perfluoro and polyfluoro alkyl substances, especially short-chain perfluoro and polyfluoro alkyl substances, can be improved to more than 70%. Compared with existing adsorption materials such as granular activated carbon and anion exchange resin, the adsorption efficiency of short-chain perfluoro and polyfluoro alkyl substances is less than 50%, and the adsorption efficiency is significantly improved. That is, the electrostatic interaction provided by the quaternary ammonium chitosan and the hydrophobic interaction provided by the cross-linking of polyvinyl alcohol and glutaraldehyde constitute the adsorption mechanism of the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane for perfluoro and polyfluoro alkyl substances, thereby realizing the efficient co-adsorption of various perfluoro and polyfluoro alkyl substances. It is suitable for tap water, groundwater, surface water, domestic sewage, industrial sewage, agricultural sewage or medical wastewater and other environmental water. It only needs to be immersed in the environmental water sample, and the minimum removal rate of various perfluoro and polyfluoro alkyl substances in it can reach more than 70% within 45 minutes.

[0028] (2) The application performance of the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is excellent: the adsorption application is flexible and easy to operate.

[0029] The quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is a "whole membrane", which can be directly immersed in environmental water for adsorption to remove perfluoro and polyfluoro alkyl substances therein. After adsorption removal, no secondary operation such as centrifugal filtration is required, and only the composite nanofiber membrane is taken out of the environmental water, so that solid-liquid separation can be easily completed. Compared with existing adsorption materials such as granular activated carbon, metal-organic framework / covalent organic framework and magnetic material, which need to be packed into a column or need to be separated by high-speed centrifugation or strong magnetic field before use, the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane not only facilitates operation, but also fundamentally avoids secondary pollution to the environment caused by difficult separation.

[0030] (3) The quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane has environmental friendliness: chitosan has good biocompatibility, biodegradability, non-toxicity, environmental friendliness, low price and easy accessibility. The quaternization modification increases the cationicity and water solubility of chitosan, and the combination of polyvinyl alcohol and electrospinning maintains the good biocompatibility and biodegradability of the nanofiber membrane, while enhancing the mechanical strength of the nanofiber membrane. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0032] Embodiment 1: This embodiment is applied to the adsorption and removal of various perfluoroalkyl and polyfluoroalkyl substances in tap water samples. The specific steps are as follows:

[0033] S1: Preparing quaternized chitosan from chitosan

[0034] Chitosan is dissolved in 0.01% (v / v) aqueous acetic acid solution to obtain a chitosan solution, wherein the concentration of chitosan is 20 g / L; 2,3-epoxypropyltrimethylammonium chloride is dissolved in deionized water to obtain a 2,3-epoxypropyltrimethylammonium chloride solution, wherein the mass concentration of the 2,3-epoxypropyltrimethylammonium chloride solution is 0.60 g / mL; under the condition of 60℃ water bath heating and stirring, 25% (v / v) 2,3-epoxypropyltrimethylammonium chloride solution is added dropwise into the chitosan solution to obtain a clear and uniform mixed solution; after centrifugation of the obtained mixed solution, the supernatant is taken and poured into v / v = 1:1 ethanol / acetone, and slowly stirred to produce a white gel-like precipitate; the obtained white gel-like precipitate is washed with anhydrous ethanol and vacuum dried to obtain quaternized chitosan.

[0035] S2: Preparing quaternized chitosan-polyvinyl alcohol composite nanofiber membrane by electrospinning method

[0036] Quaternized chitosan and polyvinyl alcohol are respectively dissolved in 20% (v / v) acetic acid solution to obtain a quaternized chitosan-polyvinyl alcohol composite solution, wherein the concentration of quaternized chitosan is 6.5 g / L, the concentration of polyvinyl alcohol is 93.5 g / L, and the mass ratio of quaternized chitosan to polyvinyl alcohol is 7% (w / w); the quaternized chitosan-polyvinyl alcohol composite solution is placed in a propeller, the distance from the nozzle to the receiving screen is adjusted, and a quaternized chitosan-polyvinyl alcohol composite nanofiber membrane is prepared by electrospinning method under a high-voltage electrostatic field.

[0037] S3: Preparing quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane from quaternized chitosan-polyvinyl alcohol composite nanofiber membrane by glutaraldehyde chemical cross-linking method

[0038] The glutaraldehyde with a concentration of 0.01 mol / L and the dilute hydrochloric acid with a concentration of 1 mol / L are mixed at a volume ratio of 0.5:1 to obtain a cross-linking solvent, and then the quaternary ammonium chitosan-polyvinyl alcohol composite nanofiber membrane is hung in a closed container after the cross-linking solvent is placed at the bottom of the closed container; the closed container is placed at 60°C for 3 hours to obtain a quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane.

[0039] S4: The quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is used as an adsorbent to adsorb and remove perfluoroalkyl substances in tap water.

[0040] The nanofiber membrane prepared by the method of the present application can be used for adsorption and removal of perfluorobutyric acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorobutane sulfonic acid, perfluoropentane sulfonic acid, perfluoroethane sulfonic acid, perfluoroheptane sulfonic acid, perfluorooctane sulfonic acid, perfluorononane sulfonic acid, perfluorodecane sulfonic acid, perfluoro(2-methyl-3-oxahexanoic acid) ammonium, sodium perfluorinated nonene oxybenzene sulfonate, and 6:2 chlorinated polyfluoroether sulfonate, and other perfluoroalkyl substances in tap water samples.

[0041] 200 mg of the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is added to each liter of tap water sample, and the composite nanofiber membrane is fully immersed in the environmental water sample. After the adsorption is completed, the composite nanofiber membrane is directly taken out from the environmental water sample. The removal efficiency can reach more than 80%.

[0042] Example 2: The present example is applied to adsorption and removal of various perfluoroalkyl substances in river water samples. The specific steps are as follows:

[0043] S1: Chitosan is prepared into quaternary ammonium chitosan

[0044] Chitosan is dissolved in 0.8% (v / v) aqueous acetic acid solution to obtain a chitosan solution, wherein the concentration of chitosan is 50 g / L; 2,3-epoxypropyltrimethylammonium chloride is dissolved in deionized water to obtain a 2,3-epoxypropyltrimethylammonium chloride solution, wherein the mass concentration of the 2,3-epoxypropyltrimethylammonium chloride solution is 1.2 g / mL; under the condition of 60°C water bath heating and stirring, 5% (v / v) 2,3-epoxypropyltrimethylammonium chloride solution is added dropwise into the chitosan solution to obtain a clear and uniform mixed solution; after the mixed solution is centrifuged, the supernatant is taken, and the supernatant is poured into v / v=1:1 ethanol / acetone, and slowly stirred to produce white gel-like precipitate; the white gel-like precipitate is washed with anhydrous ethanol, and then vacuum dried to obtain quaternary ammonium chitosan.

[0045] S2: Preparing quaternized chitosan-polyvinyl alcohol composite nanofiber membrane by electrospinning method

[0046] Quaternized chitosan and polyvinyl alcohol were respectively dissolved in 20% (v / v) acetic acid solution to obtain a quaternized chitosan-polyvinyl alcohol composite solution, wherein the concentration of quaternized chitosan was 4.8 g / L, the concentration of polyvinyl alcohol was 95.2 g / L, and the mass ratio of quaternized chitosan to polyvinyl alcohol was 5% (w / w); the quaternized chitosan-polyvinyl alcohol composite solution was placed in a propeller, the distance from the nozzle to the receiving screen was adjusted, and a quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was prepared by electrospinning method in a high-voltage electrostatic field.

[0047] S3: Preparing quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane by glutaraldehyde chemical cross-linking method

[0048] Glutaraldehyde with a concentration of 0.05 mol / L and dilute hydrochloric acid with a concentration of 2 mol / L were mixed at a volume ratio of 2:1 to obtain a cross-linking solvent, and then the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was hung in a closed container after the cross-linking solvent was placed at the bottom of the closed container; the closed container was placed at 80℃, and after 0.5 h, a quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane was obtained.

[0049] S4: Using the quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane as an adsorbent to adsorb and remove perfluoroalkyl substances in river water.

[0050] The material prepared in the application was applied to adsorb and remove perfluorobutyric acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorobutane sulfonic acid, perfluoropentane sulfonic acid, perfluoroethane sulfonic acid, perfluoroheptane sulfonic acid, perfluorooctane sulfonic acid, perfluorononane sulfonic acid, perfluorodecane sulfonic acid, perfluoro(2-methyl-3-oxahexanoic acid) ammonium, sodium perfluoroprenyloxybenzenesulfonate, and 6:2 chlorinated polyfluoroether sulfonate, and other perfluoroalkyl substances in river water samples,

[0051] 400 mg of quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane was added to each liter of river water sample, and the composite nanofiber membrane was fully immersed in the environmental water sample; after adsorption was completed, the composite nanofiber membrane was directly taken out from the environmental water sample. The removal efficiency can reach more than 75%.

[0052] Example 3: This example was applied to adsorb and remove various perfluoroalkyl substances in lake water samples. The specific steps were as follows:

[0053] S1: Preparing chitosan into quaternized chitosan

[0054] Chitosan was dissolved in 0.4% (v / v) aqueous acetic acid to obtain a chitosan solution, wherein the concentration of chitosan was 30 g / L; 2,3-epoxypropyltrimethylammonium chloride was dissolved in deionized water to obtain a 2,3-epoxypropyltrimethylammonium chloride solution, wherein the mass concentration of the 2,3-epoxypropyltrimethylammonium chloride solution was 0.80 g / mL; under the condition of 60 °C water bath heating and stirring, 20% (v / v) 2,3-epoxypropyltrimethylammonium chloride solution was added dropwise into the chitosan solution to obtain a clear and uniform mixed solution; after centrifugation of the obtained mixed solution, the supernatant was taken and poured into ethanol / acetone (v / v = 1:1), and a white gelatinous precipitate was generated after slow stirring; the obtained white gelatinous precipitate was washed with anhydrous ethanol and vacuum dried to obtain quaternized chitosan.

[0055] S2: Preparation of quaternized chitosan-polyvinyl alcohol composite nanofiber membrane by electrospinning method

[0056] Quaternized chitosan and polyvinyl alcohol were respectively dissolved in 40% (v / v) acetic acid solution to obtain a quaternized chitosan-polyvinyl alcohol composite solution, wherein the concentration of quaternized chitosan was 10.7 g / L, the concentration of polyvinyl alcohol was 89.3 g / L, and the mass ratio of quaternized chitosan to polyvinyl alcohol was 12% (w / w); the quaternized chitosan-polyvinyl alcohol composite solution was placed in a propeller, the distance from the nozzle to the receiving screen was adjusted, and a quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was prepared by electrospinning method under a high-voltage electrostatic field.

[0057] S3: Preparation of quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane by glutaraldehyde chemical cross-linking method

[0058] Glutaraldehyde with a concentration of 0.04 mol / L and dilute hydrochloric acid with a concentration of 1 mol / L were mixed at a volume ratio of 1:1 to obtain a cross-linking solvent, and the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was hung in the closed container after the cross-linking solvent was placed at the bottom of the closed container; the closed container was placed at 65 °C, and after 2.0 h, a quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane was obtained.

[0059] S4: Use of quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane as an adsorbent to adsorb and remove perfluoroalkyl and polyfluoroalkyl substances in lake water

[0060] The material prepared by the application is applied to adsorption and removal of perfluoroalkyl substances such as perfluorobutyric acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorobutane sulfonic acid, perfluoropentane sulfonic acid, perfluoroethane sulfonic acid, perfluoroheptane sulfonic acid, perfluorooctane sulfonic acid, perfluorononane sulfonic acid, perfluorodecane sulfonic acid, perfluoro(2-methyl-3-oxahexanoic acid) ammonium, sodium perfluoro-n-oxylene oxybenzene sulfonate and 6:2 chlorinated polyfluoro ether sulfonate in a lake water sample.

[0061] 300 mg of the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is added to each liter of the lake water sample, and the composite nanofiber membrane is fully immersed in the environmental water sample; after adsorption is completed, the composite nanofiber membrane is directly taken out from the environmental water sample. The removal efficiency can be more than 75%.

[0062] Example 4: The example is applied to adsorption and removal of various perfluoroalkyl substances in industrial wastewater samples, and the specific steps are as follows:

[0063] S1: Prepare chitosan into quaternary ammonium chitosan

[0064] Chitosan is dissolved in 0.5% (v / v) aqueous acetic acid solution to obtain a chitosan solution, wherein the concentration of chitosan is 25 g / L; 2,3-epoxypropyltrimethylammonium chloride is dissolved in deionized water to obtain a 2,3-epoxypropyltrimethylammonium chloride solution, wherein the mass concentration of the 2,3-epoxypropyltrimethylammonium chloride solution is 0.70 g / mL; under the condition of 60°C water bath heating and stirring, 15% (v / v) 2,3-epoxypropyltrimethylammonium chloride solution is added dropwise into the chitosan solution to obtain a clear and uniform mixed solution; after centrifugation of the obtained mixed solution, the supernatant is taken and poured into v / v = 1:1 ethanol / acetone, and slowly stirred to produce white gel-like precipitate; the obtained white gel-like precipitate is washed with anhydrous ethanol and vacuum dried to obtain quaternary ammonium chitosan.

[0065] S2: Prepare quaternary ammonium chitosan-polyvinyl alcohol composite nanofiber membrane by electrospinning method

[0066] Quaternary ammonium chitosan and polyvinyl alcohol are respectively dissolved in 80% (v / v) acetic acid solution to obtain a quaternary ammonium chitosan-polyvinyl alcohol composite solution, wherein the concentration of quaternary ammonium chitosan is 20 g / L, the concentration of polyvinyl alcohol is 80 g / L, and the mass ratio of quaternary ammonium chitosan to polyvinyl alcohol is 25% (w / w); the quaternary ammonium chitosan-polyvinyl alcohol composite solution is placed in a propeller, the distance from the nozzle to the receiving screen is adjusted, and a quaternary ammonium chitosan-polyvinyl alcohol composite nanofiber membrane is prepared by electrospinning method under a high-voltage electrostatic field.

[0067] S3: glutaraldehyde chemical cross-linking method is used to prepare the quaternary ammonium chitosan-polyvinyl alcohol composite nanofiber membrane into quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane

[0068] The quaternary ammonium chitosan-polyvinyl alcohol composite nanofiber membrane is hung in the closed container after the cross-linking solvent is placed at the bottom of the closed container; the closed container is placed at 75℃, and after 1.0h, the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is obtained.

[0069] S4: the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is used as an adsorbent to adsorb and remove perfluoroalkyl substances in industrial wastewater

[0070] The material prepared in the application is applied to adsorb and remove perfluoroalkyl substances such as perfluorobutyric acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorobutane sulfonic acid, perfluoropentane sulfonic acid, perfluoroethane sulfonic acid, perfluoroheptane sulfonic acid, perfluorooctane sulfonic acid, perfluorononane sulfonic acid, perfluorodecane sulfonic acid, perfluoro(2-methyl-3-oxahexanoic acid) ammonium, sodium perfluorinated nonene oxybenzene sulfonate and 6:2 chlorinated polyfluoroether sulfonate in industrial wastewater samples.

[0071] 500mg of quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is added to each liter of industrial wastewater sample, and it is fully immersed in the environmental water sample; after adsorption is completed, the composite nanofiber membrane is directly taken out from the environmental water sample. The removal efficiency can reach more than 70%.

[0072] Example 5: this embodiment is applied to adsorb and remove various perfluoroalkyl substances in domestic wastewater samples, and the specific steps are as follows:

[0073] S1: chitosan is prepared into quaternary ammonium chitosan

[0074] Chitosan was dissolved in 0.65% (v / v) acetic acid aqueous solution to obtain a chitosan solution, wherein the concentration of chitosan was 35 g / L; 2,3-epoxypropyltrimethylammonium chloride was dissolved in deionized water to obtain a 2,3-epoxypropyltrimethylammonium chloride solution, wherein the mass concentration of the 2,3-epoxypropyltrimethylammonium chloride solution was 1.0 g / mL; under the condition of 60°C water bath heating and stirring, 10% (v / v) 2,3-epoxypropyltrimethylammonium chloride solution was added dropwise into the chitosan solution to obtain a clear and uniform mixed solution; after centrifugation of the obtained mixed solution, the supernatant was taken and poured into ethanol / acetone (v / v = 1:1), and then slowly stirred to produce a white gel-like precipitate; the obtained white gel-like precipitate was washed with anhydrous ethanol and vacuum dried to obtain quaternized chitosan.

[0075] S2: Preparation of quaternized chitosan-polyvinyl alcohol composite nanofiber membrane by electrospinning method

[0076] Quaternized chitosan and polyvinyl alcohol were respectively dissolved in 60% (v / v) acetic acid solution to obtain a quaternized chitosan-polyvinyl alcohol composite solution, wherein the concentration of quaternized chitosan was 15.3 g / L, the concentration of polyvinyl alcohol was 84.7 g / L, and the mass ratio of quaternized chitosan to polyvinyl alcohol was 18% (w / w); the quaternized chitosan-polyvinyl alcohol composite solution was placed in a propeller, the distance from the nozzle to the receiving screen was adjusted, and a quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was prepared by electrospinning method under a high-voltage electrostatic field.

[0077] S3: Preparation of quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane by glutaraldehyde chemical cross-linking method

[0078] Glutaraldehyde with a concentration of 0.05 mol / L and dilute hydrochloric acid with a concentration of 1.5 mol / L were mixed at a volume ratio of 0.5:1 to obtain a cross-linking solvent, and then the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was hung in the closed container; the closed container was placed at 70°C, and after 0.5 h, a quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane was obtained.

[0079] S4: Use of quaternized chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane as an adsorbent to adsorb and remove perfluoroalkyl and polyfluoroalkyl substances in domestic sewage

[0080] The material prepared by the application is applied to adsorb and remove perfluorobutyric acid, perfluoropentanoic acid, perfluorohexanoic acid, perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorobutane sulfonic acid, perfluoropentane sulfonic acid, perfluoroethane sulfonic acid, perfluoroheptane sulfonic acid, perfluorooctane sulfonic acid, perfluorononane sulfonic acid, perfluorodecane sulfonic acid, perfluoro(2-methyl-3-oxahexanoic acid) ammonium, sodium p-perfluorononenyloxybenzenesulfonate, 6:2 chlorinated polyvinyl ether sulfonate and other perfluoro and polyfluoro alkyl substances in domestic sewage samples.

[0081] 300 mg of the quaternary ammonium chitosan-polyvinyl alcohol-glutaraldehyde cross-linked composite nanofiber membrane is added to each liter of domestic sewage sample, and the composite nanofiber membrane is fully immersed in the environmental water sample; after the adsorption is completed, the composite nanofiber membrane is directly taken out from the environmental water sample. The removal efficiency can reach more than 72%.

[0082] In the description of the specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0083] The basic principles, main features and advantages of the application are shown and described above. It should be understood by those skilled in the art that the application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application.

Claims

1. A method for adsorbing various perfluorinated and polyfluoroalkyl substances in environmental water using a nanofiber membrane, characterized in that, The method for adsorbing and removing perfluorinated and polyfluoroalkyl substances in environmental water using the nanofiber membrane is as follows: 200-500 mg of quaternized chitosan-polyvinyl alcohol-glutaraldehyde crosslinked composite nanofiber membrane is added to each liter of environmental water sample, allowing it to fully immerse in the sample; after adsorption is complete, the composite nanofiber membrane is directly removed from the environmental water sample; wherein, the nanofiber membrane is prepared through the following steps: S1: Preparation of quaternized chitosan; S2: Quaternized chitosan-polyvinyl alcohol composite nanofiber membrane prepared by electrospinning; S3: Quaternized chitosan-polyvinyl alcohol-glutaraldehyde crosslinked composite nanofiber membrane was prepared by glutaraldehyde chemical crosslinking method; The preparation steps of the quaternized chitosan include: S1.1: Dissolve chitosan in an aqueous solution of acetic acid with a v / v ratio of 0.01%~0.8% to obtain a chitosan solution, wherein the concentration of chitosan is 20~50 g / L; S1.2: Dissolve 2,3-epoxypropyltrimethylammonium chloride in deionized water to obtain a 2,3-epoxypropyltrimethylammonium chloride solution, wherein the concentration of the 2,3-epoxypropyltrimethylammonium chloride solution is 0.60~1.2 g / mL; S1.3: Under the conditions of heating and stirring in a water bath at 60℃, a 2,3-epoxypropyltrimethylammonium chloride solution with a v / v ratio of 5%~25% was added dropwise to the chitosan solution prepared in step S1.1 to obtain a clear and homogeneous mixed solution; S1.4: After centrifuging the obtained mixed solution, take the supernatant and pour it into ethanol / acetone with v / v = 1:

1. Stir slowly to produce a white gel-like precipitate. S1.5: The obtained white gel-like precipitate was washed with anhydrous ethanol and then dried under vacuum to obtain quaternized chitosan. The method for preparing quaternized chitosan-polyvinyl alcohol-glutaraldehyde crosslinked composite nanofiber membranes using the glutaraldehyde chemical crosslinking method is as follows: A crosslinking solvent was prepared by mixing 0.01–0.05 mol / L glutaraldehyde and 0.1–2 mol / L dilute hydrochloric acid at a volume ratio of 0.5:1–2:

1. The crosslinking solvent was placed at the bottom of a sealed container, and the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was suspended in the sealed container. The sealed container was placed at 60–80 °C for 0.5–3 h to obtain the quaternized chitosan-polyvinyl alcohol-glutaraldehyde crosslinked composite nanofiber membrane.

2. The method for adsorbing various perfluorinated and polyfluoroalkyl substances in environmental water using a nanofiber membrane as described in claim 1, characterized in that, The steps for preparing quaternized chitosan-polyvinyl alcohol composite nanofiber membranes by electrospinning include: S2.1: Quaternized chitosan and polyvinyl alcohol are dissolved in an acetic acid solution with a v / v ratio of 20-80% to obtain a quaternized chitosan-polyvinyl alcohol composite solution, wherein the concentration of quaternized chitosan is 0.1-20 g / L, the concentration of polyvinyl alcohol is 80-100 g / L, and the mass ratio of quaternized chitosan to polyvinyl alcohol is 5-25% w / w. S2.2: The quaternized chitosan-polyvinyl alcohol composite solution was placed in the propeller, the distance between the nozzle and the receiving screen was adjusted, and the quaternized chitosan-polyvinyl alcohol composite nanofiber membrane was prepared by electrospinning under a high voltage electrostatic field.

3. The method for adsorbing various perfluorinated and polyfluoroalkyl substances in environmental water using a nanofiber membrane as described in claim 1, characterized in that, The environmental water includes groundwater, domestic sewage, industrial wastewater, agricultural wastewater, or medical wastewater.

4. The method for adsorbing various perfluorinated and polyfluoroalkyl substances in environmental water using a nanofiber membrane as described in claim 1, characterized in that, The perfluorinated and polyfluoroalkyl substances include short-chain perfluorinated carboxylic acids, long-chain perfluorinated carboxylic acids, short-chain perfluorinated sulfonic acids, long-chain perfluorinated sulfonic acids, perfluorinated alkyl ether carboxylic acids, p-perfluorononoxybenzene sulfonates, and chlorinated polyfluoroether sulfonates.