A nanofiber air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities and its preparation method.

Abstract

The application discloses a kind of nanofiber membrane air filtration membranes with one-way wet, CO2 adsorption capacity and preparation method thereof, according to the following steps: (1) LiCl particles and first polymer are weighed and prepared into spinning solution A, (2) quaternary aminated polyether sulfone and second polymer are weighed and prepared into spinning solution B, (3) preparation of fiber membrane: the fiber membrane is prepared by electrospinning of the spinning solution;(4) drying.The application is prepared by continuous electrospinning technology, and a "Janus" structure with one-way wet characteristics is prepared.This structure combines double-scale fiber design and utilizes capillary difference effect to achieve excellent one-way wet function.Meanwhile, quaternary aminated polyether sulfone is introduced into the hydrophobic layer, which gives the membrane high-efficiency CO2 adsorption capacity.The synergistic effect of filtration, wetting and adsorption is achieved, especially the CO2 adsorption capacity is enhanced in humid environment, which provides an efficient and low-energy consumption solution for air purification and gas separation.

Description

Technical Field

[0001] This invention relates to a nanofiber air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities and its preparation method, belonging to the field of new materials technology. Background Technology

[0002] Air filtration and gas separation technologies are indispensable in modern industry and daily life, and their performance directly affects environmental quality, energy efficiency, and equipment lifespan. However, existing technologies have significant limitations in addressing specific challenges.

[0003] First, traditional air filter membranes, such as filter paper used in automobiles or industry, experience a significant decline in filtration performance in rainy, humid, or high-humidity environments. When moisture in the air mixes with dust particles, a dense "cake layer" forms on the filter membrane surface. This "cake layer" greatly increases the resistance to airflow through the filter membrane, leading to a sharp increase in pressure drop (differential pressure), which reduces system airflow, affects equipment operation, and shortens filter membrane life. For filter membranes that rely on electrostatic adsorption to capture fine particles, once wetted, their electrostatic charge dissipates rapidly, causing complete filtration failure. Furthermore, to achieve higher filtration efficiency, traditional filter membrane designs typically require a denser structure, but this inevitably comes at the cost of pressure drop. Finding a balance between filter membrane efficiency, pressure drop, and lifespan remains a long-standing challenge for existing filtration technologies.

[0004] Secondly, in the field of gas separation, especially for CO2 capture from industrial flue gas, existing mainstream technologies still face problems such as high energy consumption and operational complexity. For example, the widely used amine liquid absorption method (such as monoethanolamine MEA) has a core drawback in its huge regeneration energy consumption, which accounts for the highest proportion of the cost of the entire carbon capture system. In addition, amine liquid also has problems such as equipment corrosion and easy degradation, requiring the addition of antioxidants and corrosion inhibitors to maintain system stability. For solid adsorbents, although the corrosion problems of liquid adsorbents are avoided, their performance is usually highly sensitive to environmental humidity. In many adsorption systems, water vapor molecules compete with CO2 molecules for adsorption sites, thereby reducing the adsorption capacity for CO2. For example, in an environment with high relative humidity, activated carbon will adsorb a large number of water molecules in the gas, resulting in a decrease in the amount of CO2 adsorbed. This means that when using solid adsorbents, additional dehumidification pretreatment is usually required, which increases the complexity of the process and energy consumption.

[0005] In summary, current technologies lack a solution that can effectively address the degradation of filtration performance in humid environments while simultaneously achieving efficient and low-energy CO2 capture. More importantly, existing technologies generally treat moisture as a detrimental factor, requiring additional measures to eliminate it. Therefore, there is an urgent need to develop a novel functional material that can fundamentally overcome these limitations, especially maintaining or even enhancing its filtration and adsorption performance in humid environments, thereby providing a more efficient and cost-effective solution for air purification and gas separation. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a nanofiber membrane air filter with both unidirectional moisture-wicking and CO2 adsorption capabilities, and its preparation method, which can effectively solve the problem of filtration performance degradation in humid environments and achieve efficient and low-energy CO2 capture.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a nanofiber membrane air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities, characterized by the following steps:

[0008] (1) Preparation of spinning solution A: Weigh LiCl particles and the first polymer to prepare spinning solution A. The first polymer is at least one of polyvinylpyrrolidone, polyacrylonitrile, polyvinyl alcohol, and cellulose acetate.

[0009] (2) Preparation of spinning solution B: Weigh quaternary ammonium polyethersulfone and the second polymer to prepare spinning solution B. The second polymer is at least one of polycaprolactone, polyvinylidene fluoride, polytetrafluoroethylene, polyurethane, polystyrene, and polyethylene terephthalate.

[0010] (3) Preparation of fiber membrane: The fiber membrane is prepared by electrospinning the spinning solution A and the spinning solution B;

[0011] (4) Drying: The fiber membrane is dried overnight to remove residual solvent.

[0012] A "Janus" structure with unidirectional moisture-wicking properties was prepared using continuous electrospinning technology. This structure, combined with a dual-scale fiber design, utilizes capillary differential effects to achieve superior unidirectional moisture-wicking functionality. Simultaneously, quaternary ammonium polyethersulfone is introduced into the hydrophobic layer, endowing the membrane with highly efficient CO2 adsorption capacity. This invention achieves a synergistic effect of filtration, moisture wicking, and adsorption; particularly, its CO2 adsorption capacity is enhanced in humid environments, providing a highly efficient and low-energy-consumption solution for air purification and gas separation.

[0013] In the above scheme, the preparation method of spinning solution A is as follows: first, dissolve LiCl in the first solvent, then add the polymer to the above solution, and stir at a constant temperature of 70-80℃ for 6-8 hours until completely dissolved;

[0014] The first solvent is at least one of N,N-dimethylformamide, deionized water, anhydrous ethanol, acetone, and N,N-dimethylacetamide.

[0015] In the above scheme, the concentration of the first polymer in spinning solution A is 8-12 wt%, and the mass ratio of the amount of LiCl added to the first polymer is 1.2:80-120.

[0016] In the above scheme, the preparation method of spinning solution B is as follows: quaternary ammonium polyethersulfone is dissolved in a second organic solvent, and then the second polymer is added to the above solution. The solution is magnetically stirred at a constant temperature of 70-80℃ for 6-8 hours until it is completely dissolved.

[0017] The second organic solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, acetone, trifluoroacetic acid, dimethane, and N,N-dimethylacetamide.

[0018] In the above scheme, the concentration of the second polymer in spinning solution B is 14-17 wt%, and the mass ratio of quaternized polyethersulfone to the second polymer is 0.5:1.4-1.7.

[0019] In the above scheme, the substrate of the nanofiber membrane is a nonwoven fabric.

[0020] In the above scheme, during spinning, spinning solution A is loaded into the first syringe, and spinning solution B is loaded into the second syringe. After spinning with spinning solution A is completed, spinning solution B is spun sequentially.

[0021] In the above scheme, the spinning working voltage is 15kV, the feed speed is 0.8ml / h, the receiving distance is 15cm, and the inner diameter of the spinning needle is 0.4mm.

[0022] In the above scheme, the average diameter of the fiber membrane prepared by spinning solution A ranges from 118 to 206 nm, and the average diameter of the fiber membrane prepared by spinning solution B ranges from 225 to 390 nm.

[0023] A method for preparing a nanofiber air filter membrane with both unidirectional moisture conduction and CO2 adsorption capabilities.

[0024] Compared with the prior art, the present invention has the following significant advantages:

[0025] (1) The present invention first prepares a hydrophilic layer by continuous spinning and then prepares a hydrophobic layer to form a Janus structure; the hydrophilic layer nanofibers and the hydrophobic layer nanofibers have large diameter differences, forming different pore sizes, resulting in capillary difference effect. The dual-scale fibers and the Janus structure work together to achieve excellent unidirectional moisture conduction effect, realize the balance between filtration efficiency and pressure drop, and significantly improve the performance and life of the filter membrane.

[0026] (2) In this invention, quaternized polyether sulfone is introduced into the hydrophobic layer. The strong alkaline quaternary ammonium group has extremely high selectivity and affinity for weak acid CO2, giving the nanofiber membrane a high CO2 adsorption capacity.

[0027] (3) The unidirectional moisture-wicking and CO2 adsorption capacity of the nanofiber membrane prepared by the present invention have a synergistic effect, which enhances the CO2 adsorption capacity of quaternized polyether sulfone in a humid environment.

[0028] (4) The present invention has a wide variety of polymers and solvents for preparing nanofiber membranes, which is beneficial to expanding the application field of the present invention. Attached Figure Description

[0029] Figure 1 This is a physical image of the nanofiber membrane air filter membrane of the present invention, which has both unidirectional moisture-wicking and CO2 adsorption capabilities.

[0030] Figure 2 This is a SEM image of the hydrophilic layer of the nanofiber membrane of the present invention, which has both unidirectional moisture-wicking and CO2 adsorption capabilities.

[0031] Figure 3 This is a diagram showing the diameter distribution of the hydrophilic layer fibers in the nanofiber membrane of the present invention, which has both unidirectional moisture-wicking and CO2 adsorption capabilities.

[0032] Figure 4 This is a SEM image of the hydrophobic layer of the nanofiber membrane of the present invention, which has both unidirectional moisture-wicking and CO2 adsorption capabilities.

[0033] Figure 5 This is a diagram showing the fiber diameter distribution of the hydrophobic layer of the nanofiber membrane of the present invention, which has both unidirectional moisture-wicking and CO2 adsorption capabilities.

[0034] Figure 6 This is a schematic diagram of the contact angle of the nanofiber membrane of the present invention, which has both unidirectional moisture-wicking and CO2 adsorption capabilities. Detailed Implementation

[0035] The present invention will be further described below with reference to embodiments.

[0036] The materials and equipment used in this invention are as follows: polyacrylonitrile (PAN, Mw = 15000, powder, Beijing Mairuida Technology Co., Ltd.); cellulose acetate (CA, Mw = 3000, solution, Shanghai Maclean Biochemical Technology Co., Ltd.); polyvinyl alcohol (PVA, powder, Shanghai Maclean Biochemical Technology Co., Ltd.); polyvinylpyrrolidone (PVP, powder, Shanghai Maclean Biochemical Technology Co., Ltd.); lithium chloride (LiCl, Mw = 42.44, granules, Beijing Innocare Technology Co., Ltd.); polycaprolactone (PCL, Mw = 80000, powder, Shanghai Maclean Biochemical Technology Co., Ltd.); polyethylene terephthalate (PEO, Mw = 228.199, granules, Shanghai Maclean Biochemical Technology Co., Ltd. Polyurethane (PU, powder, Sigma-Aldrich); Polyvinylidene fluoride (PVDF, solid, Beijing Innocare Technology Co., Ltd.); Polytetrafluoroethylene (PTFE, solid, Shanghai Yanbida Biotechnology Co., Ltd.); Polystyrene (PS, solid, Jinan Erben Biotechnology Co., Ltd.); Acetone (analytical grade AR 99.5%, Qingdao Yanyu Laboratory Instrument Co., Ltd.); Dichloromethane (analytical grade AR 99.5%, Qingdao Yanyu Laboratory Instrument Co., Ltd.); Trifluoroacetic acid (analytical grade AR 99.5%, Weifang Dianhe Import & Export Trading Co., Ltd.); N,N-dimethylformamide (analytical grade AR 99%, Beijing Innocare Technology Co., Ltd.); and N,N-dimethylacetamide (analytical grade AR 99%, Beijing Innocare Technology Co., Ltd.). The GeminiSEM360 scanning electron microscope was purchased from Zeiss GmbH, Germany; the contact angle measuring instrument was purchased from KRUSS GmbH, Germany; the electrospinning equipment was purchased from Yunfan (Tianjin) Instrument Co., Ltd. (DP30 model); and the MU-K1030 mask particulate filtration efficiency tester was purchased from Shandong Jinan Ruix Measurement and Control Technology Co., Ltd.

[0037] Example 1

[0038] This embodiment provides a method for preparing a nanofiber membrane air filter membrane that combines unidirectional moisture wicking and CO2 adsorption capabilities, comprising the following steps:

[0039] a. Preparation of spinning solution A: Weigh 0.012g of LiCl and dissolve it in 9.2g of DMF. Then add 0.8g of PAN and stir at 70-80℃ for 6 hours to prepare spinning solution A. The concentration of the spinning solution is 8wt% (the mass of LiCl is ignored when calculating the concentration, the same below).

[0040] b. Preparation of spinning solution B: Weigh 0.5g of quaternary ammonium polyethersulfone and dissolve it in 8.6g of DMF, then add 1.4g of polyvinylidene fluoride and stir to dissolve at 70-80℃ for 6h to prepare spinning solution B. The concentration of the spinning solution is 14wt% (the mass of quaternary ammonium polyethersulfone is ignored when calculating the concentration, the same below).

[0041] c. Preparation of fibrous membrane: Using nonwoven fabric as a substrate, the spinning solution is used to prepare a nanofiber membrane by electrospinning. Spinning solution A is loaded into the first syringe, and spinning solution B is loaded into the second syringe. After spinning with spinning solution A is completed, spinning solution B is spun sequentially.

[0042] The spinning parameters were set as follows: working voltage 15kV, feed speed 0.8ml / h, receiving distance 15cm, and spinning needle inner diameter 0.4mm. The average diameter range of the fiber membranes prepared by spinning solution A was 118-206nm, and the average diameter range of the fiber membranes prepared by spinning solution B was 225-390nm.

[0043] d. Drying: The fiber membrane is dried overnight at 60°C to remove residual solvent.

[0044] Example 2

[0045] A method for preparing a nanofiber air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities includes the following steps:

[0046] a. Preparation of spinning solution A: Weigh 0.012g of LiCl and dissolve it in 9g of deionized water, then add 1g of PVP. Stir at 70-80℃ for 8h to prepare spinning solution A. The concentration of the spinning solution is 10wt%.

[0047] b. Preparation of spinning solution B: Weigh 0.5g of quaternary ammonium polyethersulfone and dissolve it in 8.5g of DMF, then add 1.5g of PU and stir at 70-80℃ for 8h to prepare spinning solution B. The concentration of the spinning solution is 15wt%.

[0048] c. Preparation of fiber membrane: The spinning solution is used as a nonwoven fabric as a substrate to prepare a fiber membrane by electrospinning; spinning solution A is loaded into the first syringe, spinning solution B is loaded into the second syringe, and spinning solution B is spun sequentially after spinning solution A is completed.

[0049] The spinning parameters were set as follows: working voltage 15kV, feed speed 0.8ml / h, receiving distance 15cm, and spinning needle inner diameter 0.4mm. The average diameter range of the fiber membranes prepared by spinning solution A was 118-206nm, and the average diameter range of the fiber membranes prepared by spinning solution B was 225-390nm.

[0050] d. Drying: The fiber membrane is dried overnight at 60°C to remove residual solvent;

[0051] Example 3

[0052] A method for preparing a nanofiber air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities includes the following steps:

[0053] a. Preparation of spinning solution A: Weigh 0.012g of LiCl and dissolve it in 8.8g of anhydrous ethanol, then add 1.2g of CA and stir at 70-80℃ for 7h to prepare spinning solution A. The concentration of the spinning solution is 12wt%.

[0054] b. Preparation of spinning solution B: Weigh 0.5g of quaternary ammonium polyethersulfone and dissolve it in 8.4g of acetone, then add 1.6g of PCL and stir to dissolve at 70-80℃ for 7h to prepare spinning solution B with a concentration of 16wt%.

[0055] c. Preparation of fiber membrane: The spinning solution is used as a nonwoven fabric as a substrate to prepare a fiber membrane by electrospinning; spinning solution A is loaded into the first syringe, spinning solution B is loaded into the second syringe, and spinning solution B is spun sequentially after spinning solution A is completed.

[0056] The spinning parameters were set as follows: working voltage 15kV, feed speed 0.8ml / h, receiving distance 15cm, and spinning needle inner diameter 0.4mm.

[0057] d. Drying: The fiber membrane is dried overnight at 60°C to remove residual solvent; the average diameter of the fiber membrane prepared by spinning solution A is in the range of 118-206 nm, and the average diameter of the fiber membrane prepared by spinning solution B is in the range of 225-390 nm.

[0058] Example 4

[0059] A method for preparing a nanofiber air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities includes the following steps:

[0060] a. Preparation of spinning solution A: Weigh 0.012g of LiCl and dissolve it in deionized water, then add 0.9g of PVA and stir at 70-80℃ for 8 hours to prepare spinning solution A with a concentration of 9wt%.

[0061] b. Preparation of spinning solution B: Weigh 0.5g of quaternary ammonium polyethersulfone and add it to 8.3g of tetrahydrofuran, then add 1.7g of PS and stir at 70-80℃ for 8 hours to dissolve, thus preparing spinning solution B with a concentration of 17wt%.

[0062] c. Preparation of fiber membrane: The spinning solution is used as a nonwoven fabric as a substrate to prepare a fiber membrane by electrospinning; spinning solution A is loaded into the first syringe, spinning solution B is loaded into the second syringe, and spinning solution B is spun sequentially after spinning solution A is completed.

[0063] The spinning parameters were set as follows: working voltage 15kV, feed speed 0.8ml / h, receiving distance 15cm, and spinning needle inner diameter 0.4mm. The average diameter range of the fiber membranes prepared by spinning solution A was 118-206nm, and the average diameter range of the fiber membranes prepared by spinning solution B was 225-390nm.

[0064] d. Drying: The fiber membrane is dried overnight at 60°C to remove residual solvent;

[0065] The performance test results of the nanofiber air filter membrane of this invention, which combines unidirectional moisture wicking and CO2 adsorption capabilities, are shown in Table 1:

[0066]

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention. For example, the first polymer may be at least one of polyvinylpyrrolidone, polyacrylonitrile, polyvinyl alcohol, and cellulose acetate; the second polymer may be at least one of polycaprolactone, polyvinylidene fluoride, polytetrafluoroethylene, polyurethane, polystyrene, and polyethylene terephthalate; the first solvent may be at least one of N,N-dimethylformamide, deionized water, anhydrous ethanol, acetone, and N,N-dimethylacetamide; and the second organic solvent may include at least one of N,N-dimethylformamide, tetrahydrofuran, acetone, trifluoroacetic acid, dimethane, and N,N-dimethylacetamide. The scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nanofiber membrane air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities, characterized in that, Follow these steps: (1) Preparation of spinning solution A: Weigh LiCl particles and the first polymer to prepare spinning solution A. The first polymer is at least one of polyvinylpyrrolidone, polyacrylonitrile, polyvinyl alcohol, and cellulose acetate. The first solvent used in spinning solution A is at least one of N,N-dimethylformamide, deionized water, anhydrous ethanol, acetone, and N,N-dimethylacetamide. (2) Preparation of spinning solution B: Weigh quaternary ammonium polyethersulfone and the second polymer to prepare spinning solution B. The second polymer is at least one of polycaprolactone, polyvinylidene fluoride, polytetrafluoroethylene, polyurethane, polystyrene, and polyethylene terephthalate. The second organic solvent used in spinning solution B includes at least one of N,N-dimethylformamide, tetrahydrofuran, acetone, trifluoroacetic acid, and N,N-dimethylacetamide. (3) Preparation of fiber membrane: The fiber membrane is prepared by electrospinning of the spinning solution A and the spinning solution B; the average diameter of the fiber membrane prepared by spinning solution A is 118-206 nm, and the average diameter of the fiber membrane prepared by spinning solution B is 225-390 nm. (4) Drying: Dry the fiber membrane at 60°C overnight to remove residual solvent.

2. The method for preparing the nanofiber membrane air filter membrane with unidirectional moisture-wicking and CO2 adsorption capabilities according to claim 1, characterized in that, The preparation method of spinning solution A is as follows: First, dissolve LiCl in the first solvent, then add the first polymer to the above solution, and stir at a constant temperature of 70-80℃ for 6-8 hours until completely dissolved.

3. The method for preparing the nanofiber membrane air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities according to claim 2, characterized in that, The concentration of the first polymer in spinning solution A is 8-12 wt%, and the mass ratio of LiCl added to the first polymer is 1.2:80-120.

4. The method for preparing a nanofiber air filter membrane with unidirectional moisture-wicking and CO2 adsorption capabilities according to any one of claims 1-3, characterized in that, The preparation method of spinning solution B is as follows: Dissolve quaternary ammonium polyethersulfone in a second organic solvent, then add the second polymer to the above solution, and stir magnetically at a constant temperature of 70-80℃ for 6-8 hours until completely dissolved.

5. The method for preparing a nanofiber membrane air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities according to claim 4, characterized in that, The concentration of the second polymer in spinning solution B is 14-17 wt%, and the mass ratio of quaternized polyethersulfone to the second polymer is 0.5:1.4-1.

7.

6. The method for preparing a nanofiber air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities according to claim 5, characterized in that, The substrate of the nanofiber membrane is a nonwoven fabric.

7. The method for preparing a nanofiber air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities according to claim 6, characterized in that, During spinning, spinning solution A is loaded into the first syringe, and spinning solution B is loaded into the second syringe. After spinning with spinning solution A is completed, spinning solution B is spun sequentially.

8. The method for preparing a nanofiber membrane air filter membrane with both unidirectional moisture-wicking and CO2 adsorption capabilities according to claim 7, characterized in that: The spinning operating voltage is 15kV, the feed speed is 0.8ml / h, the receiving distance is 15cm, and the inner diameter of the spinning needle is 0.4mm.

9. A nanofiber membrane air filter membrane with unidirectional moisture-wicking and CO2 adsorption capabilities prepared by a method according to any one of claims 1-8.

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