A tubular nanofiber membrane material and a preparation method and application thereof

Abstract

The application belongs to the technical field of air filtration materials, and specifically discloses a tubular nanofiber membrane material and a preparation method and application thereof. A two-dimensional braided tube is first subjected to surface modification in a surface modification liquid, and then subjected to biomimetic modification in a manganese-containing biomimetic modification liquid to obtain a biomimetic modified two-dimensional braided tube base; the tubular nanofiber membrane material is obtained by electrospinning a mixed spinning dope on the base. The mixed spinning dope is obtained by mixing poly-m-phenylene isophthalamide spinning solution or poly-m-phenylene isophthalamide / MnO2 spinning solution and polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution. The tubular nanofiber membrane material obtained by the application has high packing density and does not need to be supported by a skeleton; the tubular air filter prepared therefrom has good mechanical properties, filtration performance, formaldehyde removal performance and durability, and excellent antibacterial performance, and is universal.

Description

Technical Field

[0001] This invention relates to the field of air filtration materials technology, and in particular to a tubular nanofiber membrane material, its preparation method, and its application. Background Technology

[0002] With rapid industrial development, air pollution is becoming increasingly severe, and prolonged exposure to polluted environments can lead to various diseases. Air filters, used in conjunction with high-efficiency particulate matter (HEPA) filters, have become one of the most effective methods for removing particulate matter (PM) from the air, and the structure and performance of the filter element are key factors affecting air filters. Compared to planar filter substrates, tubular nanofiber membrane materials have advantages such as good self-supporting properties and high packing density, which helps to simplify the construction of air filters and improve manufacturing efficiency.

[0003] In addition to particulate matter, formaldehyde is classified as a Group 1 carcinogen. Long-term exposure to environments with excessive formaldehyde levels can lead to chronic poisoning, causing respiratory and digestive diseases, and greatly increasing the probability of developing leukemia, tumors, and cancer, and in more serious cases, death.

[0004] The removal of HCHO from indoor air is mainly achieved by using air purifiers with absorption media or by increasing the air exchange rate through air conditioning systems. However, currently available purifiers are limited to those based on traditional activated carbon adsorption materials, which require a long cycle time and pose a risk of secondary pollution.

[0005] With the development of catalysts, catalytic oxidation has become a research hotspot for formaldehyde removal. Among the transition metal oxide catalysts used, manganese dioxide (MnO2) is widely used for the catalytic removal of HCHO, which can convert HCHO into CO2 and H2O. However, MnO2 particulate catalysts are difficult to use in air filters and are not suitable for the removal of HCHO in room temperature air in practical applications.

[0006] Therefore, how to provide a tubular nanofiber membrane material with good mechanical properties, filtration performance, formaldehyde removal performance and durability, and then prepare a tubular nanofiber air filter with excellent antibacterial properties and universal applicability, is an urgent problem to be solved in this field. Summary of the Invention

[0007] In view of this, the present invention provides a tubular nanofiber membrane material, its preparation method and application, which solves the problems of poor support performance and low packing density of existing planar filter substrates; it also solves the problems of long purification cycles and the risk of secondary pollution in existing air purifiers targeting HCHO in the air.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing a tubular nanofiber membrane material includes the following steps:

[0010] 1) The two-dimensional braided tube is immersed in a surface modification solution to perform surface modification, thereby obtaining a surface-modified two-dimensional braided tube;

[0011] 2) The surface-modified two-dimensional braided tube is immersed in a manganese-containing biomimetic modification solution to carry out biomimetic modification and in-situ growth of MnO2 to obtain a biomimetic modified two-dimensional braided tube substrate.

[0012] 3) Using a biomimetic modified two-dimensional braided tube substrate as the receiving substrate, electrospinning of the mixed spinning solution was performed to obtain tubular nanofiber membrane materials.

[0013] The mixed spinning solution is obtained by mixing poly(m-phenylene isophthalamide) spinning solution or poly(m-phenylene isophthalamide) / MnO2 spinning solution with polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution.

[0014] Preferably, the two-dimensional braided tube in step 1) includes polyethylene terephthalate fiber two-dimensional braided tube, polyacrylonitrile fiber two-dimensional braided tube, polyamide fiber two-dimensional braided tube, and polyolefin fiber two-dimensional braided tube.

[0015] Preferably, the surface modification liquid includes one or more of the following: dopamine hydrochloride aqueous solution, tannic acid aqueous solution, and catechol aqueous solution;

[0016] The mass concentration of the surface modification liquid is 0.1–10 g / L.

[0017] Preferably, the pH value of the surface modification is 7-10, and the surface modification time is 6-48 hours.

[0018] Preferably, the manganese-containing biomimetic modification solution in step 2) is a potassium permanganate solution; the molar concentration of the manganese-containing biomimetic modification solution is 0.01 to 0.4 mol / L.

[0019] Preferably, the biomimetic modification time in step 2) is 3 to 24 hours, and the biomimetic modification temperature is 20 to 80°C.

[0020] Preferably, in step 3), the volume ratio of poly(m-phenylene isophthalamide) spinning solution or poly(m-phenylene isophthalamide / MnO2) spinning solution to polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution is 3 to 10:1.

[0021] Preferably, the electrospinning voltage is 10-25kV positive high voltage and -1-5kV negative high voltage, the distance between the spinning needle and the receiving substrate is 5-20cm, and the feeding speed is 0.1-2mL / h.

[0022] Another objective of this invention is to provide a tubular nanofiber membrane material prepared by the above-described preparation method.

[0023] Another object of the present invention is to provide an application of a tubular nanofiber membrane material as an air filter element.

[0024] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention uses a biomimetic modified two-dimensional braided tube substrate as the receiving matrix and poly(m-phenylene isophthalamide) (PMIA), which has excellent high-temperature resistance, as one of the main raw materials for nanofiber membrane fabrication. Electrospinning technology is employed to prepare PMIA nanofiber air filter materials with high-efficiency filtration performance. Unlike the planar structure of traditional nanofiber air filter materials, the nanofiber air filter material prepared in this invention has a unique tubular structure, which improves its air filtration performance and endows the PMIA nanofiber air filter material with multifunctionality. This unique filter structure design reduces production costs, improves preparation efficiency and service life, and provides a more comprehensive reference for practical applications. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a surface morphology image of the modified PET two-dimensional braided tube material in Example 1 of the present invention;

[0028] Figure 2 This is a cross-sectional SEM image of the tubular nanofiber membrane material prepared in Example 1 of the present invention;

[0029] Figure 3 This is a SEM image of the tubular nanofiber membrane material prepared in Comparative Example 1 of this invention.

[0030] Figure 4 This is a SEM image of the tubular nanofiber membrane material prepared in Example 2 of the present invention. Detailed Implementation

[0031] This invention provides a method for preparing tubular nanofiber membrane materials, comprising the following steps:

[0032] 1) The two-dimensional braided tube is immersed in a surface modification solution to perform surface modification, thereby obtaining a surface-modified two-dimensional braided tube;

[0033] 2) The surface-modified two-dimensional braided tube is immersed in a manganese-containing biomimetic modification solution to carry out biomimetic modification and in-situ growth of MnO2 to obtain a biomimetic modified two-dimensional braided tube substrate.

[0034] 3) Using a biomimetic modified two-dimensional braided tube substrate as the receiving substrate, electrospinning of the mixed spinning solution was performed to obtain tubular nanofiber membrane materials.

[0035] In this invention, the mixed spinning solution is obtained by mixing poly(m-phenylene isophthalamide) spinning solution or poly(m-phenylene isophthalamide) / MnO2 spinning solution with polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution; the mixing temperature is preferably 60-80℃, specifically 62℃, 64℃, 65℃, 66℃, 68℃, 70℃, 72℃, 75℃, or 78℃.

[0036] In this invention, the two-dimensional braided tube in step 1) includes polyethylene terephthalate fiber two-dimensional braided tube, polyacrylonitrile fiber two-dimensional braided tube, polyamide fiber two-dimensional braided tube, and polyolefin fiber two-dimensional braided tube.

[0037] In this invention, the surface modification liquid includes one or more of the following: dopamine hydrochloride aqueous solution, tannic acid aqueous solution, and catechol aqueous solution;

[0038] In this invention, the mass concentration of the surface modification liquid is 0.1 to 10 g / L, specifically 0.5 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, or 9 g / L.

[0039] In this invention, the pH value of the surface modification is 7 to 10, specifically 7.5, 8, 8.5, 9, or 9.5; the surface modification time is 6 to 48 hours, specifically 8 hours, 10 hours, 12 hours, 18 hours, 24 hours, 30 hours, or 36 hours.

[0040] In this invention, the manganese-containing biomimetic modification solution in step 2) is a potassium permanganate solution; the molar concentration of the manganese-containing biomimetic modification solution is 0.01 to 0.4 mol / L, specifically 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, or 0.35 mol / L.

[0041] In this invention, the biomimetic modification time in step 2) is 3 to 24 hours, specifically 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, and 22 hours; the biomimetic modification temperature is 20 to 80 degrees Celsius, specifically 25 degrees Celsius, 30 degrees Celsius, 35 degrees Celsius, 40 degrees Celsius, 45 degrees Celsius, 50 degrees Celsius, 55 degrees Celsius, 60 degrees Celsius, 65 degrees Celsius, 70 degrees Celsius, and 75 degrees Celsius.

[0042] In this invention, the volume ratio of poly(m-phenylene isophthalamide) spinning solution or poly(m-phenylene isophthalamide / MnO2) spinning solution to polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution in the mixed spinning solution in step 3) is 3 to 10:1, preferably 5 to 7:1, and more preferably 6:1.

[0043] In this invention, the solvents of poly(m-phenylene isophthalamide) spinning solution, poly(m-phenylene isophthalamide) / MnO2 spinning solution, and polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution include one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0044] In this invention, the preparation method of poly(m-phenylene isophthalamide) spinning solution is as follows: LiCl and poly(m-phenylene isophthalamide) are added sequentially to a solvent to obtain poly(m-phenylene isophthalamide) spinning solution; the mass concentration of poly(m-phenylene isophthalamide) spinning solution is 5-25 wt.%, specifically 8 wt.%, 10 wt.%, 12 wt.%, 15 wt.%, 18 wt.%, 20 wt.%, 22 wt.%, and 24 wt.%.

[0045] In this invention, the mass concentration of the polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution is 5-30 wt.%, specifically 8 wt.%, 10 wt.%, 12 wt.%, 15 wt.%, 18 wt.%, 20 wt.%, 22 wt.%, 24 wt.%, 25 wt.%, and 28 wt.%.

[0046] In this invention, the preparation method of poly(m-phenylene isophthalamide) / MnO2 spinning solution is as follows: LiCl, MnO2 powder and poly(m-phenylene isophthalamide) are added sequentially to a solvent to obtain poly(m-phenylene isophthalamide) / MnO2 spinning solution.

[0047] In this invention, the ratio of LiCl, MnO2 powder, poly(m-phenylene isophthalamide) to solvent is 1-5:0-8:5-25:62-94, preferably 2-4:1-6:8-20:65-90, more preferably 3:2-5:10-18:70-80, and even more preferably 3:4:15:75; the amount of MnO2 powder added is not 0.

[0048] In this invention, the electrospinning voltage is a positive high voltage of 10-25kV, specifically 12kV, 15kV, 18kV, 20kV, 22kV, or 24kV; the negative high voltage is -1 to -5kV, specifically -2kV, -3kV, or -4kV; the distance between the spinning needle and the receiving substrate is 5-20cm, specifically 6cm, 8cm, 10cm, 12cm, 15cm, or 18cm; and the feeding rate is 0.1-2mL / h, 0.2mL / h, 0.5mL / h, 0.8mL / h, 1mL / h, 1.2mL / h, 1.5mL / h, or 1.8mL / h.

[0049] The present invention also provides a tubular nanofiber membrane material prepared by the above preparation method.

[0050] This invention also provides an application of tubular nanofiber membrane material as an air filter element.

[0051] In this invention, the air filter element is prepared by: using the tubular nanofiber membrane material as the filter material, encapsulating one end of the tubular nanofiber membrane material in a nylon tube with epoxy resin, and then inserting it into a silicone base in a honeycomb arrangement to form an air filter element.

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] The PET two-dimensional braided tubing used in all embodiments of the present invention was purchased from Xuzhou Shiheng Environmental Protection Technology Co., Ltd. (inner diameter 1.1cm, outer diameter 1.8cm), but this is not considered a limitation of the present invention.

[0054] Example 1

[0055] (1) Biomimetic surface modification of braided tubing: PET two-dimensional braided tubing was immersed in a dopamine hydrochloride solution (mass concentration 2 g / L), and the pH of the solution was adjusted to 8.5. After reacting at room temperature for 24 h, it was placed in a 0.03 mol / L potassium permanganate solution and soaked at 60℃ for 5 h. It was then removed, thoroughly rinsed with deionized water, and air-dried. The surface morphology of the modified PET two-dimensional braided tubing material is as follows: Figure 1 As shown, through Figure 1 It can be seen that MnO2 nanoparticles were successfully grown in situ on the fiber surface.

[0056] (2) Preparation of spinning solution: Weigh 1g of LiCl powder into a three-necked round-bottom flask containing 43g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Then add 6g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA spinning solution).

[0057] A certain amount of 9g of polyvinylidene fluoride-hexafluoropropylene copolymer was added to 41g of dimethylacetamide solution, and then the mixture was stirred in a water bath at 65℃ for 5h to remove bubbles, thus obtaining polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution (PVDF-HFP spinning solution).

[0058] The PMIA spinning solution and the PVDF-HFP spinning solution were mixed at a ratio of 8:1 to obtain the mixed spinning solution.

[0059] (3) The mixed spinning solution was added to a syringe, with the modified braided tube as the receiving substrate. The positive spinning voltage was 15 kV, the negative receiving voltage was -2 kV, the spinning distance was 10 cm, and the feeding rate was 0.2 mL / h. Electrospinning was performed using an electrospinning device to obtain a tubular PMIA / MnO2 nanofiber membrane material. The cross-sectional SEM image of the tubular PMIA / MnO2 nanofiber membrane material is shown below. Figure 2 As shown, through Figure 2 It can be seen that the nanofiber layer is tightly wrapped around the outer surface of the braided tube.

[0060] Tests showed that the obtained tubular nanofiber air filter had a PM2.5 filtration efficiency of 97.1% and a formaldehyde removal efficiency of over 73.7%.

[0061] Comparative Example 1

[0062] (1) Preparation of spinning solution: Weigh 1g of LiCl powder into a three-necked round-bottom flask containing 43g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Then add 6g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA spinning solution).

[0063] A certain amount of 9g of polyvinylidene fluoride-hexafluoropropylene copolymer was added to 41g of dimethylacetamide solution, and then the mixture was stirred in a water bath at 65℃ for 5h to remove bubbles, thus obtaining polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution (PVDF-HFP spinning solution).

[0064] The PMIA spinning solution and the PVDF-HFP spinning solution were mixed at a ratio of 8:1 to obtain the mixed spinning solution.

[0065] (2) The mixed spinning solution was added to a syringe, using an unmodified PET two-dimensional braided tube as the receiving substrate. The spinning positive voltage was 15kV, the receiving negative voltage was -2kV, the spinning distance was 10cm, and the feeding rate was 0.2mL / h. Electrospinning was performed to obtain tubular PMIA nanofiber membrane material. Its SEM morphology is shown below. Figure 3 As shown, through Figure 3 It can be seen that the nanofiber structure is relatively uniform and the fiber surface is relatively smooth.

[0066] Tests showed that the obtained tubular nanofiber air filter had a PM2.5 filtration efficiency of 96.9% and no formaldehyde degradation performance, because the tubular nanofiber membrane material does not contain any functional substances that degrade formaldehyde.

[0067] Comparative Example 2

[0068] (1) Biomimetic modification of the surface of braided tubing: PET two-dimensional braided tubing was immersed in dopamine hydrochloride solution (mass concentration of 2 g / L), and the pH value of the solution was adjusted to 8.5. After reacting at room temperature for 24 h, it was placed in 0.03 mol / L potassium permanganate solution and soaked at 60℃ for 5 h. After that, it was taken out, rinsed thoroughly with deionized water, and dried.

[0069] (2) Preparation of spinning solution: Weigh 1g of LiCl powder into a three-necked round-bottom flask containing 43g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Then add 6g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA spinning solution), thus obtaining the electrospinning dope.

[0070] (3) The spinning solution was added to a syringe, with the modified braided tube as the receiving substrate. The positive spinning voltage was 15kV, the negative receiving voltage was -2kV, the spinning distance was 10cm, and the feeding rate was 0.2mL / h. Electrospinning was performed to obtain tubular PMIA nanofiber membrane material.

[0071] Tests showed that the obtained tubular nanofiber air filter achieved a PM2.5 filtration efficiency of 95.1% and a formaldehyde removal efficiency of over 71.5%. Adding PVDF-HFP to the spinning solution facilitates nanofiber formation during electrospinning.

[0072] Example 2

[0073] (1) Biomimetic surface modification of braided tubing: PET two-dimensional braided tubing was immersed in a dopamine hydrochloride solution (4 g / L), and the pH of the solution was adjusted to 8.5. After reacting at room temperature for 24 h, it was placed in a 0.11 mol / L potassium permanganate solution and soaked at 60 °C for 5 h. Afterwards, it was removed, thoroughly rinsed with deionized water, and air-dried.

[0074] (2) Preparation of spinning solution: Weigh 1g of LiCl powder into a three-necked round-bottom flask containing 43g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Add 0.5g of MnO2 powder to the above solution and stir continuously for 1h. Then add 6g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA / MnO2 spinning solution).

[0075] A certain amount of 9g of polyvinylidene fluoride-hexafluoropropylene copolymer was added to 41g of dimethylacetamide solution, and then stirred in a water bath at 65℃ for 5h. After degassing, polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution (PVDF-HFP spinning solution) was obtained.

[0076] The PMIA / MnO2 spinning solution and the PVDF-HFP solution were mixed at a ratio of 4:1 to obtain the mixed spinning solution.

[0077] (3) The spinning solution was added to a syringe, with the modified braided tube as the receiving substrate. The positive spinning voltage was 15 kV, and the negative voltage at the receiving end was -2 kV. The spinning distance was 10 cm, and the feeding rate was 0.3 mL / h. Electrospinning was performed using an electrospinning device to obtain a tubular PMIA / MnO2 nanofiber membrane material. Its SEM morphology is shown below. Figure 4 As shown, through Figure 4 It can be seen that there are a large number of MnO2 nanoparticles on the surface of the nanofibers.

[0078] Tests showed that the obtained tubular nanofiber air filter had a PM2.5 filtration efficiency of 97.4% and a formaldehyde removal efficiency of over 97.2%.

[0079] Example 3

[0080] (1) Biomimetic modification of the surface of braided tubing: PET two-dimensional braided tubing was immersed in a dopamine hydrochloride solution (mass concentration of 6 g / L), and the pH of the solution was adjusted to 8.5. After reacting at room temperature for 24 h, it was placed in a 0.11 mol / L potassium permanganate solution and soaked at 60℃ for 5 h. After that, it was taken out, rinsed thoroughly with deionized water, and dried.

[0081] (2) Preparation of spinning solution: Weigh 1g of LiCl powder into a three-necked round-bottom flask containing 42.25g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Add 1g of MnO2 powder to the above solution and stir continuously for 1h. Then add 6g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA / MnO2 spinning solution).

[0082] A certain amount of 9g of polyvinylidene fluoride-hexafluoropropylene copolymer was added to 41g of dimethylacetamide solution, and then stirred in a water bath at 65℃ for 5h. After degassing, polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution (PVDF-HFP spinning solution) was obtained.

[0083] The PMIA / MnO2 spinning solution and the PVDF-HFP solution were mixed at a ratio of 6:1 to obtain the mixed spinning solution.

[0084] (3) The spinning solution was added to a syringe, with the modified braided tube as the receiving substrate. The positive spinning voltage was 15 kV, the negative receiving voltage was -2 kV, and the feeding rate was 0.4 mL / h. The spinning distance was 10 cm. Electrospinning was performed to obtain tubular PMIA / MnO2 nanofiber membrane material.

[0085] Tests showed that the obtained tubular nanofiber air filter has a PM2.5 filtration efficiency of 96.5% and a formaldehyde removal efficiency of over 99.9%.

[0086] Example 4

[0087] (1) Biomimetic surface modification of braided tubing: Polyamide two-dimensional braided tubing was immersed in tannic acid aqueous solution (mass concentration of 8 g / L), and the pH value of the solution was adjusted to 9. After reacting at room temperature for 48 h, it was placed in 0.3 mol / L potassium permanganate solution and soaked at 70 °C for 5 h. After that, it was taken out, rinsed thoroughly with deionized water, and dried.

[0088] (2) Preparation of spinning solution: Weigh 1.5g of LiCl powder into a three-necked round-bottom flask containing 40.5g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Add 1.5g of MnO2 powder to the above solution and stir continuously for 1h. Then add 8g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA / MnO2 spinning solution).

[0089] A certain amount of 10g of polyvinylidene fluoride-hexafluoropropylene copolymer was added to 40g of dimethylacetamide solution, and then stirred in a water bath at 65℃ for 5h. After degassing, polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution (PVDF-HFP spinning solution) was obtained.

[0090] The PMIA / MnO2 spinning solution and the PVDF-HFP solution were mixed at a ratio of 10:1 to obtain the mixed spinning solution.

[0091] (3) The spinning solution was added to a syringe, with the modified braided tube as the receiving substrate. The positive spinning voltage was 20 kV, the negative receiving voltage was -3 kV, and the feeding rate was 0.3 mL / h. The spinning distance was 15 cm. Electrospinning was performed to obtain tubular PMIA / MnO2 nanofiber membrane material.

[0092] Tests showed that the obtained tubular nanofiber air filter had a PM2.5 filtration efficiency of 97.8% and a formaldehyde removal efficiency of over 99.8%.

[0093] Example 5

[0094] (1) Biomimetic surface modification of braided tubing: Two-dimensional polyacrylonitrile braided tubing was immersed in catechol aqueous solution (mass concentration of 10 g / L), and the pH value of the solution was adjusted to 9.5. After reacting at room temperature for 6 h, it was placed in 0.01 mol / L potassium permanganate solution and soaked at 80℃ for 5 h. After that, it was taken out, rinsed thoroughly with deionized water, and dried.

[0095] (2) Preparation of spinning solution: Weigh 2g of LiCl powder into a three-necked round-bottom flask containing 37g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Add 1.0g of MnO2 powder to the above solution and stir continuously for 1h. Then add 10g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA / MnO2 spinning solution).

[0096] A certain amount of 12g of polyvinylidene fluoride-hexafluoropropylene copolymer was added to 38g of dimethylacetamide solution, and then stirred in a water bath at 65℃ for 5h. After degassing, polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution (PVDF-HFP spinning solution) was obtained.

[0097] The PMIA / MnO2 spinning solution and the PVDF-HFP solution were mixed at a ratio of 3:1 to obtain the mixed spinning solution.

[0098] (3) The spinning solution was added to a syringe, with the modified braided tube as the receiving substrate. The positive spinning voltage was 12kV, the negative receiving voltage was -1kV, and the feeding rate was 1.2mL / h. The spinning distance was 18cm. Electrospinning was performed to obtain tubular PMIA / MnO2 nanofiber membrane material.

[0099] Tests showed that the obtained tubular nanofiber air filter had a PM2.5 filtration efficiency of 95.8% and a formaldehyde removal efficiency of over 93.8%.

[0100] Example 6

[0101] (1) Biomimetic surface modification of braided tubing: Two-dimensional polyacrylonitrile braided tubing was immersed in an aqueous solution of tannic acid (mass concentration of 2 g / L), and the pH of the solution was adjusted to 7.5. After reacting at room temperature for 12 h, it was placed in a 0.4 mol / L potassium permanganate solution and soaked at 50 °C for 6 h. After that, it was taken out, rinsed thoroughly with deionized water, and dried.

[0102] (2) Preparation of spinning solution: Weigh 1g of LiCl powder into a three-necked round-bottom flask containing 40g of dimethylacetamide solvent, sonicate for 30min, and then mechanically stir in a 65℃ water bath for 1h to uniformly disperse the powder. Add 1.0g of MnO2 powder to the above solution and stir continuously for 1h. Then add 9g of poly(m-phenylene isophthalamide) to the above solution and stir continuously for 5h until the poly(m-phenylene isophthalamide) is completely dissolved to form a homogeneous poly(m-phenylene isophthalamide) spinning solution (PMIA / MnO2 spinning solution).

[0103] A certain amount of 10g of polyvinylidene fluoride-hexafluoropropylene copolymer was added to 40g of dimethylacetamide solution, and then stirred in a water bath at 65℃ for 5h. After degassing, polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution (PVDF-HFP spinning solution) was obtained.

[0104] The PMIA / MnO2 spinning solution and the PVDF-HFP solution were mixed at a ratio of 8:1 to obtain the mixed spinning solution.

[0105] (3) The spinning solution was added to a syringe, with the modified braided tube as the receiving substrate. The positive spinning voltage was 15 kV, the negative receiving voltage was -1 kV, and the feeding rate was 0.3 mL / h. The spinning distance was 15 cm. Electrospinning was performed to obtain tubular PMIA / MnO2 nanofiber membrane material.

[0106] Tests showed that the obtained tubular nanofiber air filter had a PM2.5 filtration efficiency of 96.3% and a formaldehyde removal efficiency of over 95.8%.

[0107] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0108] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a tubular nanofiber membrane material, characterized in that, Includes the following steps: 1) The two-dimensional braided tube is immersed in a surface modification solution to perform surface modification, thereby obtaining a surface-modified two-dimensional braided tube; 2) The surface-modified two-dimensional braided tube is immersed in a manganese-containing biomimetic modification solution to carry out biomimetic modification and in-situ growth of MnO2 to obtain a biomimetic modified two-dimensional braided tube substrate. 3) Using a biomimetic modified two-dimensional braided tube substrate as the receiving substrate, electrospinning of the mixed spinning solution was performed to obtain tubular nanofiber membrane materials. The mixed spinning solution is obtained by mixing poly(m-phenylene isophthalamide) spinning solution or poly(m-phenylene isophthalamide) / MnO2 spinning solution with polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution. The surface modification solution includes one or more of the following: dopamine hydrochloride aqueous solution, tannic acid aqueous solution, and catechol aqueous solution; The mass concentration of the surface modification liquid is 0.1~10 g / L; The pH value for surface modification is 7~10, and the surface modification time is 6~48h; The manganese-containing biomimetic modification solution mentioned in step 2) is a potassium permanganate solution; the molar concentration of the manganese-containing biomimetic modification solution is 0.01~0.4 mol / L; The biomimetic modification time in step 2) is 3~24h, and the biomimetic modification temperature is 20~80℃.

2. The method for preparing a tubular nanofiber membrane material according to claim 1, characterized in that, The two-dimensional braided tube mentioned in step 1) includes any one of polyethylene terephthalate fiber two-dimensional braided tube, polyacrylonitrile fiber two-dimensional braided tube, polyamide fiber two-dimensional braided tube, and polyolefin fiber two-dimensional braided tube.

3. The method for preparing a tubular nanofiber membrane material according to claim 1, characterized in that, In step 3), the volume ratio of poly(m-phenylene isophthalamide) spinning solution or poly(m-phenylene isophthalamide / MnO2) spinning solution to polyvinylidene fluoride-hexafluoropropylene copolymer spinning solution is 3~10:

1.

4. The method for preparing a tubular nanofiber membrane material according to claim 3, characterized in that, The electrospinning voltage is 10~25kV positive high voltage and -1~-5kV negative high voltage. The distance between the spinning needle and the receiving substrate is 5~20cm, and the feeding speed is 0.1~2mL / h.

5. The tubular nanofiber membrane material prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the tubular nanofiber membrane material according to claim 5 as an air filter element.

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