An air filtration membrane based on nano-hybrid modified polylactic acid fiber and its preparation method

Abstract

The present invention discloses an air filtration membrane based on nanohybrid-modified polylactic acid fiber and a preparation method thereof. The present invention adopts a microwave-assisted in-situ synthesis method to directly induce the in-situ growth of ZIF-8 nanocrystals on the surface of CNTs to obtain CNT@ZIF-8 nanohybrids. Through coaxial electrospinning technology, an air filtration membrane with CNT@ZIF-8 uniformly embedded in polylactic acid fibers is obtained. The preparation method of the present invention is simple and the conditions are controllable. The prepared air filtration fiber membrane has the advantages of high surface potential, large specific surface area, good air permeability, long-term filtration, etc., and is an air filtration material with broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance air filtration materials, and in particular to an air filtration membrane based on nano-hybrid modified polylactic acid fibers and a preparation method thereof. Background Art

[0002] With the increasing concern of human beings for environmental and health issues, the problem of fine particulate pollutants in the air has received more and more attention from countries around the world. Air filtration is one of the most effective methods to remove particles. Therefore, air filtration media with low pressure drop, good strength and high pathogen removal efficiency have gradually become a research hotspot.

[0003] Carbon nanotubes are coaxial circular tubes composed of several to dozens of layers of carbon atoms arranged in a hexagonal pattern. They have the advantages of large specific surface area, strong adsorption and desorption capabilities, good mechanical properties and electrical conductivity, and have great application potential in the field of nanomaterials.

[0004] Metal-organic frameworks (MOFs) are organic-inorganic hybrid materials with intramolecular pores, formed by the self-assembly of metal ions and organic ligands or clusters through coordination bonds. They are an emerging class of porous crystalline materials that play a crucial role in energy and environmental applications. Zeolitic imidazolate framework-8 (ZIF-8) is a typical MOF material, characterized by strong adsorption, high porosity, large specific surface area, adjustable pore size, and high thermal stability. Combining ZIF-8 with filter materials can significantly improve filtration performance. Typically, ZIF-8 is introduced into filter fiber materials through solution blending [Deng Lingli et al. Preparation and Filtration Performance of PVDF / ZIF-8 Composite Filter Materials, China Materials Progress, 2019, 5, 464.]. This results in the ZIF-8 being encapsulated by the polymer matrix, preventing the full utilization of its excellent properties. Significant improvements in filtration performance require increasing the ZIF-8 content.

[0005] To this end, the present invention aims to provide an air filtration membrane based on nanohybrid modified polylactic acid fiber and a preparation method thereof, so as to realize the structural characteristics of ZIF-8 being stably and evenly distributed on the fiber surface, and obtain the advantages of high efficiency, low resistance and long-term filtration. The preparation process of this method is simple, the conditions are mild, the product is biodegradable, and it has important economic and social value. Summary of the Invention

[0006] The purpose of the present invention is to provide an air filtration membrane based on nanohybrid modified polylactic acid fiber and a preparation method thereof, so as to realize the structural characteristics of ZIF-8 being stably and evenly distributed on the fiber surface, and obtain the advantages of high efficiency, low resistance and long-term filtration. The preparation process of this method is simple, the conditions are mild, the product is biodegradable, and it has important economic and social value.

[0007] The object of the present invention is achieved like this:

[0008] A method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber comprises the following steps: Step S1. Preparing a carbon nanotube dispersion: uniformly dispersing carbon nanotubes (CNTs) and a dispersant in water, and then performing liquid phase circulation high shear grinding to prepare a CNTs dispersion;

[0009] Step S2. Microwave-assisted preparation of CNT@ZIF-8 nanohybrids: The CNTs dispersion obtained in S1, 2-methylimidazole, and zinc salt were added to water, mixed evenly, and placed in a microwave reactor for in situ synthesis. After the reaction was completed, the mixture was cooled to room temperature under stirring, allowed to stand for 8-24 hours, and dried to obtain CNT@ZIF-8 nanohybrids.

[0010] Step S3. Preparation of high-efficiency air filtration membrane using coaxial electrospinning technology: The CNT@ZIF-8 nanohybrid obtained in S2 is dispersed in a solvent as the external phase spinning solution, and polylactic acid is dissolved in a solvent as the internal phase spinning solution. Finally, the coaxial electrospinning technology is used to obtain an air filtration membrane in which the CNT@ZIF-8 nanohybrid is uniformly embedded in the polylactic acid fiber.

[0011] The carbon nanotubes (CNTs) used in step S1 have an average diameter of 10-50 nm and an aspect ratio of 1:100-1:1000. The mass concentration of the carbon nanotubes (CNTs) in the aqueous dispersion is 0.1-5 wt %.

[0012] The dispersant used in step S1 is at least one of sodium cholate, polyvinyl pyrrolidone, sodium tauroursodeoxycholate, dodecyltrimethylammonium bromide, sodium lauryl sulfate, and sodium hexadecylbenzenesulfonate, and the mass ratio of carbon nanotubes (CNTs) to dispersant is 1:100-1:10.

[0013] The solution dispersion equipment in step S1 is at least one of an intermittent high-shear dispersing emulsifier, a pipeline high-shear dispersing emulsifier, a planetary mixer, a mechanical mixer, a magnetic mixer, an ultrasonic crusher, an ultrasonic disperser, a nano grinder, and a planetary ball mill, and the energy consumption per unit volume of the solution dispersion process is 0.5-10 kWh / L; the equipment providing liquid-phase circulating high-shear grinding in step S1 is at least one of a pin sand mill, a turbine sand mill, a disc sand mill, and a vertical sand mill, and the energy consumption per unit mass of the liquid-phase grinding process is 0.1-20 kWh / kg.

[0014] The water-soluble zinc salt used in step S2 is at least one of zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride, the mass ratio of 2-methylimidazole to the water-soluble zinc salt is 5:1-10:1, and the mass ratio of carbon nanotubes (CNTs) to the water-soluble zinc salt is 1:20-1:100.

[0015] The microwave reactor used in step S2 has an output power of 200-1000 W, a stirring speed of 0-550 rpm, a reaction temperature of 100-180° C., and a reaction time of 1-60 min.

[0016] The drying method used in the step S2 is at least one of normal pressure drying, reduced pressure drying, spray drying, freeze drying, vacuum drying, and microwave drying.

[0017] The solvent in the external spinning solution in step S3 is at least one of dichloromethane, chloroform, dimethylformamide, N-methylpyrrolidone, hexafluoroisopropanol, methanol, ethanol, isopropanol, and glycerol, and the mass fraction of the CNT@ZIF-8 nanohybrid in the spinning solution is 0.1-2wt%. The solvent in the internal spinning solution in step S3 is at least one of dichloromethane, chloroform, dimethylformamide, N-methylpyrrolidone, hexafluoroisopropanol, methanol, ethanol, isopropanol, and glycerol, and the mass fraction of the polylactic acid is 0.5-10wt%.

[0018] In the S3 step, the coaxial electrospinning voltage is 10-65 kV, the external phase spinning solution consumption rate is 0.2-1.5 mL / h, the internal phase spinning solution consumption rate is 0.8-3.0 mL / h, the mass ratio of CNT@ZIF-8 nanohybrid to polylactic acid is 1:5-1:15, the receiving distance is 12-30 cm, and the average diameter of the obtained air filtration fiber is 10-240 nm, and the fiber membrane thickness is 50-300 μm.

[0019] The air filtration membrane based on nano hybrid modified polylactic acid fiber is prepared by the preparation method of the present invention.

[0020] The beneficial effects of the present invention are as follows: the present invention adopts a microwave-assisted in-situ synthesis method to directly induce the in-situ growth of ZIF-8 nanocrystals on the surface of CNTs to obtain CNT@ZIF-8 nanohybrids, and through coaxial electrospinning technology, a high-efficiency filtration membrane in which CNT@ZIF-8 is uniformly embedded in polylactic acid fibers is obtained. The surface potential of the fiber membrane is 9.3-19.8KV, and the specific surface area is 160-450m2 / g. At a gas flow rate of 10-85L / min, the air resistance is lower than 100Pa, the PM0.3 filtration efficiency is greater than 98%, the PM2.5 filtration efficiency is greater than 99%, and the antibacterial efficiency is high (>95%). The preparation method is simple and the conditions are controllable. The prepared air filtration fiber membrane has the advantages of high surface potential, large specific surface area, good air permeability, long-term filtration, etc., and is an air filtration material with broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1Scanning electron microscopic images of CNTs at different magnifications in Example 1 of the present invention;

[0022] Figure 2 These are scanning electron microscopic images of the CNT@ZIF-8 nanohybrid obtained in Example 1 of the present invention at different magnifications. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings and examples.

[0024] Example 1:

[0025] A method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber comprises the following steps:

[0026] Step S1. Preparation of carbon nanotube dispersion: CNTs and sodium cholate (mass ratio 1:10) are uniformly dispersed in an ultrasonic disruptor. After the energy consumption per unit volume reaches 0.5 kWh / L, liquid phase circulating high shear grinding is performed in a turbine sand mill. After the energy consumption per unit mass reaches 0.1 kWh / kg, a CNTs dispersion (mass concentration 0.1 wt%) is obtained.

[0027] Step S2. Microwave-assisted synthesis of CNT@ZIF-8 nanohybrids: The CNTs dispersion obtained in S11, 2-methylimidazole, and zinc nitrate were added to water (the mass ratio of zinc nitrate to 2-methylimidazole was 1:5, and the mass ratio of CNTs dispersion to zinc nitrate was 1:20), mixed evenly, and placed in a microwave reactor for in situ synthesis (output power 200 W, temperature 120°C, time 3 min, stirring speed 0 rpm). After the reaction was completed, it was cooled to room temperature, allowed to stand for 8 h, and then spray-dried to obtain the CNT@ZIF-8 nanohybrid.

[0028] Step S3. Preparation of high-efficiency air filtration membrane by coaxial electrospinning technology: The CNT@ZIF-8 nanohybrid obtained in S12 is dispersed in dimethylformamide (the mass fraction of CNT@ZIF-8 nanohybrid is 0.1wt%) as the external phase spinning solution, and polylactic acid is dissolved in dichloromethane (the mass fraction of polylactic acid is 0.5wt%) as the internal phase spinning solution. Finally, the CNT@ZIF-8 nanohybrid is uniformly embedded in the polylactic acid fiber through coaxial electrospinning technology (voltage 12KV, external phase spinning solution consumption rate 0.2mL / h, internal phase spinning solution consumption rate 0.8mL / h, receiving distance 10cm) to obtain a high-efficiency air filtration membrane. The average diameter of the obtained fiber is 10nm and the fiber membrane thickness is 50μm.

[0029] Example 2

[0030] A method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber comprises the following steps:

[0031] Step S1. Preparation of carbon nanotube dispersion: CNTs and polyvinyl pyrrolidone (mass ratio 1:30) are uniformly dispersed in an ultrasonic disperser. After the energy consumption per unit volume reaches 3 kWh / L, liquid phase circulating high shear grinding is performed in a pin-type sand mill. After the energy consumption per unit mass reaches 5 kWh / kg, a CNTs dispersion (mass concentration 1.5 wt%) is obtained.

[0032] Step S2. Microwave-assisted synthesis of CNT@ZIF-8 nanohybrid: The CNTs dispersion obtained in S21, 2-methylimidazole, and zinc nitrate were added to water (the mass ratio of zinc acetate to 2-methylimidazole was 1:6, and the mass ratio of CNTs dispersion to zinc acetate was 1:40), mixed evenly, and placed in a microwave reactor for in situ synthesis (output power 400 W, temperature 130 ° C, time 6 min, stirring speed 120 r / min). After the reaction was completed, it was cooled to room temperature, allowed to stand for 12 h, and then microwave dried to obtain the CNT@ZIF-8 nanohybrid.

[0033] Step S3. Preparation of high-efficiency air filtration membrane by coaxial electrospinning technology: The CNT@ZIF-8 nanohybrid obtained in S22 is dispersed in N-methylpyrrolidone (the mass fraction of CNT@ZIF-8 nanohybrid is 0.8wt%) as the external phase spinning solution, and polylactic acid is dissolved in chloroform (the mass fraction of polylactic acid is 3wt%) as the internal phase spinning solution. Finally, by coaxial electrospinning technology (voltage 15KV, external phase spinning solution consumption rate 0.5mL / h, internal phase spinning solution consumption rate 1.2mL / h, receiving distance 13cm), a high-efficiency air filtration membrane in which the CNT@ZIF-8 nanohybrid is uniformly embedded in the polylactic acid fiber is obtained. The average diameter of the obtained fiber is 80nm and the fiber membrane thickness is 100μm.

[0034] Example 3

[0035] A method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber comprises the following steps:

[0036] Step S1. Preparation of carbon nanotube dispersion: CNTs and sodium taurodeoxycholate (mass ratio 1:60) are uniformly dispersed in a nano-grinder. After the energy consumption per unit volume reaches 6 kWh / L, liquid phase circulating high shear grinding is performed on a disc sand mill. After the energy consumption per unit mass reaches 8 kWh / kg, a CNTs dispersion (mass concentration 3.5 wt%) is obtained.

[0037] Step S2. Microwave-assisted synthesis of CNT@ZIF-8 composite material: The CNTs dispersion obtained in S31, 2-methylimidazole, and zinc nitrate were added to water (the mass ratio of zinc sulfate to 2-methylimidazole was 1:8, and the mass ratio of CNTs dispersion to zinc sulfate was 1:60), mixed evenly, and placed in a microwave reactor for in situ synthesis (output power 600 W, temperature 140 ° C, time 9 min, stirring speed 370 r / min). After the reaction was completed, it was cooled to room temperature, allowed to stand for 18 hours, and then dried at normal pressure to obtain a CNT@ZIF-8 nanohybrid.

[0038] Step S3. Preparation of high-efficiency air filtration membrane by coaxial electrospinning technology: The CNT@ZIF-8 (CNT@ZIF-8 nanohybrid mass fraction is 1.5wt%) obtained in S32 is dispersed in methanol as the external phase spinning solution, and polylactic acid is dissolved in hexafluoroisopropanol (polylactic acid mass fraction is 6wt%) as the internal phase spinning solution. Finally, by coaxial electrospinning technology (voltage 18KV, external phase spinning solution consumption rate 0.8mL / h, internal phase spinning solution consumption rate 1.8mL / h, receiving distance 15cm), a high-efficiency nanofiber membrane in which the CNT@ZIF-8 nanohybrid is uniformly embedded in the polylactic acid fiber is obtained. The average diameter of the obtained fiber is 150nm and the fiber membrane thickness is 180μm.

[0039] Example 4

[0040] A method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber comprises the following steps:

[0041] Step S1. Prepare a carbon nanotube dispersion: CNTs and alkylphenol polyoxyethylene ether (mass ratio 1:80) are uniformly dispersed in a pipeline high-shear dispersing emulsifier. After the energy consumption per unit volume reaches 10 kWh / L, liquid phase circulation high-shear grinding is performed in a vertical sand mill. After the energy consumption per unit mass reaches 10 kWh / kg, a CNTs dispersion (mass concentration 5 wt%) is obtained.

[0042] Step S2. Microwave-assisted synthesis of CNT@ZIF-8 nanohybrid: The CNTs dispersion obtained in S41, 2-methylimidazole, and zinc chloride were added to water (the mass ratio of zinc nitrate to 2-methylimidazole was 1:8, and the mass ratio of CNTs dispersion to zinc chloride was 1:60), mixed evenly, and placed in a microwave reactor for in situ synthesis (output power 800 W, temperature 160°C, time 15 min, stirring speed 550 r / min). After the reaction was completed, it was cooled to room temperature, allowed to stand for 24 h, and then vacuum dried to obtain the CNT@ZIF-8 nanohybrid.

[0043] Step S3. Preparation of high-efficiency air filtration membrane by coaxial electrospinning technology: The CNT@ZIF-8 (CNT@ZIF-8 nanohybrid mass fraction is 2 wt%) obtained in S42 is dispersed in isopropanol as the external phase spinning solution, and polylactic acid is dissolved in glycerol (polylactic acid mass fraction is 10 wt%) as the internal phase spinning solution. Finally, by coaxial electrospinning technology (voltage 65 kV, external phase spinning solution consumption rate 1.5 mL / h, internal phase spinning solution consumption rate 3.0 mL / h, receiving distance 18 cm), a high-efficiency nanofiber membrane in which the CNT@ZIF-8 nanohybrid is uniformly embedded in the polylactic acid fiber is obtained. The average diameter of the obtained fiber is 240 nm and the fiber membrane thickness is 300 μm.

[0044] Comparative Example 1 (not using nanohybrid, directly using ZIF-8)

[0045] The air filtration membrane of ZIF-8 modified polylactic acid was prepared basically by the method in Example 1. The difference is that this example does not use microwave-assisted synthesis of CNT@ZIF-8 nanohybrids. Instead, the CNTs dispersion and commercially purchased ZIF-8 powder (purity 95%, average size 80 nm, Xi'an Ruixi Biotechnology Co., Ltd.) are directly dispersed into the solvent as the external phase spinning solution. Specifically, CNTs and ZIF-8 powder are dispersed in dichloromethane as the external phase spinning solution, and polylactic acid is dissolved in dichloromethane (mass ratio 1:60) as the internal phase spinning solution; the air filtration membrane is prepared by coaxial electrospinning technology (voltage 12KV, solution consumption rate 0.5mL / h, receiving distance 12cm), and the obtained fiber has an average diameter of 10nm and a fiber membrane thickness of 50μm.

[0046] Comparative Example 2 (conventional spinning was performed directly without using coaxial electrospinning technology)

[0047] CNT@ZIF-8 was prepared using the same method as in Example 2. The difference was that, instead of using coaxial electrospinning technology to prepare the air filtration fiber membrane, this example used uniaxial electrospinning technology to prepare the fiber membrane. Specifically, the CNT@ZIF-8 obtained in S22 and polylactic acid (mass ratio 1:10) were uniformly dispersed in N-methylpyrrolidone, and the air filtration fiber membrane was prepared by uniaxial electrospinning technology (voltage 15 kV, solution consumption rate 0.8 mL / h, receiving distance 15 cm). The average diameter of the obtained fiber was 80 nm and the fiber membrane thickness was 100 μm.

[0048] Structural characterization and performance testing:

[0049] Scanning electron microscopy observation: The microstructures of CNTs and CNT@ZIF-8 nanohybrids were observed by field emission scanning electron microscopy (model JSM-7900F, JEOL).

[0050] Specific surface area test: A gas adsorption instrument (ASAP 2060, Micromeritics, USA) was used to measure the nitrogen adsorption isotherm at 77 K.

[0051] Particle size testing: The average particle size of CNT@ZIF-8 was measured based on the ISO 13321 standard method for particle size analysis. At least three parallel test samples were performed for each group, and the average of the results was taken.

[0052] Surface potential test: A non-contact electrostatic meter (VM54XQS, Quatek, USA) was used to test the surface potential of the nanofiber membrane. The test height was 2 cm, the temperature and humidity were constant at 25°C and 45%, and 20 data points were randomly collected for each sample and the average value was taken.

[0053] Filtration Performance Testing: The air filtration performance of nanofiber membranes (113.04 cm²) was tested using an LZC-K automatic filter tester (Suzhou Huada Instrument Co., Ltd.). The air flow rate was set at 85 L / min, and the aerosol generator produced NaCl atomized particles with a particle size range of 0.1 to 10 μm. Each set of membranes was tested at least three different locations, and the results were averaged.

[0054] Antibacterial performance test: The antibacterial performance of the samples was tested according to the modified experimental method in AATCC 100-2004 "Resistant Finishes on Textile Materials: Evaluation". Gram-negative Escherichia coli O157:H7 (ATCC 43895) and Gram-positive Staphylococcus aureus (ATCC 6538) were selected as test bacteria. The fiber membrane was subjected to antibacterial testing, and the inhibition rate was calculated according to the following formula:

[0055]

[0056] Where: R-inhibition rate; A-average colony count of the test sample before treatment; B-average colony count of the test sample after treatment; each group was tested three times, and the results were averaged.

[0057] Table 1. Specific surface area, surface potential, filtration efficiency, antibacterial efficiency, and pressure drop test results of air filtration membranes

[0058]

[0059] Experimental results: Figure 1 As shown in Figure 2, the CNTs obtained by liquid phase grinding are more evenly dispersed and more densely arranged. Figure 2 As shown in the figure, through microwave-assisted synthesis, ZIF-8 nanocrystals were induced to grow in situ directly on the surface of CNTs, and the obtained CNT@ZIF-8 nanohybrids had good structural regularity and crystallinity.

[0060] Table 1 compares the specific surface area, surface potential, filtration efficiency, antibacterial efficiency and air permeability test results of the fiber membranes of the examples and the comparative examples. Examples 1-4 have a relatively high specific surface area (160-450m2 / g), which greatly increases the roughness of the fiber and thus effectively improves the mechanical filtration performance of the fiber membrane. Examples 1-4 all exhibit extremely high surface potentials (9.3-19.8KV), and almost no attenuation occurs over time, proving to have extremely high long-term stability. The surface potential of the fiber membrane is closely related to the filtration performance. Examples 1-4 with extremely high surface potential have a filtration efficiency of more than 98% for PM0.3 and PM2.5, and the air resistance is much lower than that of traditional nanofiber membranes (all <100Pa), truly achieving high efficiency and low resistance. Among them, Example 4, which has the highest surface potential, exhibited the best filtration performance, achieving filtration efficiencies of 99.3% for PM0.3 and 99.8% for PM2.5, respectively. This was significantly higher than Comparative Examples 1-2, which had lower surface potentials (PM0.3 and PM2.5 filtration efficiencies of <90%). Examples 1-4 achieved antibacterial efficiencies exceeding 95%, demonstrating excellent antibacterial performance.

[0061] This shows that the technical solution proposed in the present invention enables the CNT@ZIF-8 nanohybrid to have good surface activity and size uniformity. The obtained air filtration fiber membrane has the advantages of high surface potential, excellent filtration performance, significant antibacterial effect, and low air resistance. These are due to: (1) The liquid phase grinding technology not only makes the obtained CNTs structure uniform, but also makes the obtained CNTs have uniform particle size. (2) Microwave-assisted synthesis not only greatly shortens the reaction time, but also is more conducive to inducing in situ growth of ZIF-8 crystals on the surface of CNTs, which helps the air filtration membrane to have significant filtration efficiency and antibacterial properties. (3) Coaxial electrospinning technology is conducive to the effective embedding of CNT@ZIF-8 nanohybrids into the surface of polylactic acid fibers, which is not easy to fall off, so that the air filtration fiber membrane has a high surface potential and long-term electrostatic adsorption capacity, and has good application prospects.

Claims

1. A method for preparing an air filtration membrane based on nanohybrid modified polylactic acid fiber, characterized in that: The method comprises the following steps: Step S1. preparing a carbon nanotube dispersion: uniformly dispersing carbon nanotubes (CNTs) and a dispersant in water, and then subjecting the dispersion to liquid-phase circulation high shear grinding to prepare a CNTs dispersion, wherein the mass concentration of the carbon nanotubes (CNTs) in the aqueous dispersion is 0.1-5wt%; Step S2. Microwave-assisted preparation of CNTs@ZIF-8 nanohybrids: The CNTs dispersion obtained in S1, 2-methylimidazole, and zinc salt are added to water, mixed evenly, and then placed in a microwave reactor for in situ synthesis. After the reaction is completed, the mixture is cooled to room temperature under stirring, allowed to stand for 8-24 hours, and dried to obtain CNTs@ZIF-8 nanohybrids, wherein the mass ratio of 2-methylimidazole to water-soluble zinc salt is 5:1-10:1, and the mass ratio of carbon nanotubes (CNTs) to water-soluble zinc salt is 1:20-1:100; Step S3. Preparation of high-efficiency air filtration membrane using coaxial electrospinning technology: The CNTs@ZIF-8 nanohybrid obtained in S2 is dispersed in a solvent as the external phase spinning solution, and the mass fraction of the CNTs@ZIF-8 nanohybrid in the spinning solution is 0.1-2wt%. At the same time, polylactic acid is dissolved in a solvent as the internal phase spinning solution, and the mass fraction of polylactic acid is 0.5-10wt%. Finally, an air filtration membrane in which the CNTs@ZIF-8 nanohybrid is uniformly embedded in the polylactic acid fiber is obtained by coaxial electrospinning technology, and the mass ratio of the CNTs@ZIF-8 nanohybrid to polylactic acid is 1:5-1:

15.

2. The method for preparing an air filtration membrane based on nanohybrid modified polylactic acid fiber according to claim 1, characterized in that: The carbon nanotubes (CNTs) used in step S1 have an average diameter of 10-50 nm and an aspect ratio of 1:100-1:1000.

3. The method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber according to claim 1, characterized in that: The dispersant used in step S1 is at least one of sodium cholate, polyvinyl pyrrolidone, sodium tauroursodeoxycholate, dodecyltrimethylammonium bromide, sodium lauryl sulfate, and sodium hexadecylbenzenesulfonate, and the mass ratio of carbon nanotubes (CNTs) to dispersant is 1:100-1:

10.

4. The method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber according to claim 1, wherein: The solution dispersion equipment in step S1 is at least one of an intermittent high-shear dispersing emulsifier, a pipeline high-shear dispersing emulsifier, a planetary mixer, a mechanical mixer, a magnetic mixer, an ultrasonic crusher, an ultrasonic disperser, a nano grinder, and a planetary ball mill, and the energy consumption per unit volume of the solution dispersion process is 0.5-10 kWh / L; the equipment providing liquid-phase circulating high-shear grinding in step S1 is at least one of a pin sand mill, a turbine sand mill, a disc sand mill, and a vertical sand mill, and the energy consumption per unit mass of the liquid-phase grinding process is 0.1-20 kWh / kg.

5. The method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber according to claim 1, characterized in that: The water-soluble zinc salt used in step S2 is at least one of zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride.

6. The method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber according to claim 1, characterized in that: The microwave reactor used in step S2 has an output power of 200-1000 W, a stirring speed of 0-550 rpm, a reaction temperature of 100-180° C., and a reaction time of 1-60 min.

7. The method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber according to claim 1, characterized in that: The drying method used in the step S2 is at least one of normal pressure drying, reduced pressure drying, spray drying, freeze drying, vacuum drying, and microwave drying.

8. The method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber according to claim 1, characterized in that: The solvent in the external phase spinning solution in step S3 is at least one of dichloromethane, chloroform, dimethylformamide, N-methylpyrrolidone, hexafluoroisopropanol, methanol, ethanol, isopropanol, and glycerol; the solvent in the internal phase spinning solution in step S3 is at least one of dichloromethane, chloroform, dimethylformamide, N-methylpyrrolidone, hexafluoroisopropanol, methanol, ethanol, isopropanol, and glycerol.

9. The method for preparing an air filtration membrane based on nanohybrid-modified polylactic acid fiber according to claim 1, characterized in that: In the S3 step, the coaxial electrospinning voltage is 10-65KV, the external phase spinning solution consumption rate is 0.2-1.5mL / h, the internal phase spinning solution consumption rate is 0.8-3.0mL / h, the receiving distance is 12-30cm, and the average diameter of the obtained air filtration fiber is 10-240nm, and the fiber membrane thickness is 50-300μm.

10. An air filtration membrane based on nanohybrid-modified polylactic acid fiber, characterized by: The invention relates to an air filtration membrane prepared by the preparation method according to any one of claims 1 to 9.

Images