Multifunctional micro / nanofiber material for high efficiency air filtration and preparation method and application thereof

Abstract

This invention provides a multifunctional micro / nanofiber material for high-efficiency air filtration, its preparation method, and its applications. The multifunctional micro / nanofiber material comprises a micron-scale fiber support layer and a nanofiber layer grown on the micron-scale fiber support layer. The nanofiber layer is synthesized by a self-assembly method using a metal ion donor and an organic ligand L. The filter material of this invention achieves high filtration efficiency and low air resistance while possessing excellent antibacterial properties, air permeability, and moisture management capabilities.

Description

Technical Field

[0001] This invention belongs to the field of air filtration, and in particular relates to a multifunctional micro / nanofiber material for high-efficiency air filtration, its preparation method and application. Background Technology

[0002] Air filters are widely used for environmental purification and public health protection. Meltblown nonwoven fabrics dominate air filtration applications due to their three-dimensional network structure and electrostatic electret effect (Polymers 2020, 12(10), 2341). However, electret meltblown nonwoven fabrics suffer from reduced filtration efficiency due to electrostatic decay under high humidity conditions, limiting their long-term stability. In addition, micron-sized meltblown fibers present a trade-off between filtration efficiency and air resistance (Small 2017, 13(46), 1702139), making it difficult to maintain excellent air permeability while ensuring efficient particle capture. To overcome the limitations of meltblown materials, nanofiber membranes, due to their high specific surface area and fiber fineness, have been used in high-efficiency air filtration materials (Ind. Eng. Chem. Res. 2021, 60(20), 7517–7534.). Electrospun nanofiber membranes exhibit excellent performance in capturing submicron particles, but their permeability is limited due to the small gaps between nanofibers, and traditional electrospinning methods have low yields, making large-scale production difficult (Applied Materials Today 2019, 17, 1–35). In recent years, multi-scale fiber structures have been proposed to optimize filtration efficiency, air resistance, and humidity management (Sci. China Mater. 2019, 62(3), 423–436). This strategy combines the high permeability of micron-scale supporting fibers with the high particle retention capacity of nanofiber layers, improving overall filtration performance. However, existing methods for preparing layered structures, such as the combination of electrospinning and meltblowing, still face problems such as low production efficiency and poor adhesion of nanofiber layers, and challenges remain in achieving antibacterial and biodegradable properties.

[0003] Therefore, existing technologies still have shortcomings in terms of filtration performance, production scalability, humidity stability, and antibacterial function. There is an urgent need for an air filter material that combines high filtration efficiency, low air resistance, excellent antibacterial properties, and biodegradability to meet increasingly stringent environmental purification and health protection requirements. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and propose a multifunctional micro / nanofiber material for high-efficiency air filtration, its preparation method and application.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] In a first aspect, the present invention provides a multifunctional micro / nanofiber material for high-efficiency air filtration, the multifunctional micro / nanofiber material comprising a micron-scale fiber support layer and a nanofiber layer grown on the micron-scale fiber support layer, wherein the nanofiber layer is synthesized by a self-assembly method using a metal ion donor and an organic ligand L.

[0007] Preferably, the organic ligand L is tris(3-pyridyl)phenyl-1,3,5-tricarboxylic acid ester, with the following structural formula:

[0008]

[0009] Preferably, the silver metal salt is selected from one or more of AgNO3, AgBF4, AgClO4, and AgCF3SO3, the trivalent iron metal salt is FeNO3, the copper metal salt is CuSO4, the zinc metal salt is ZnCl2, the cobalt metal salt is CoCl2, and the nickel metal salt is Ni(NO3)2·6H2O or NiCl2·6H2O. More preferably, the metal salt is a silver metal salt or a trivalent iron metal salt.

[0010] Preferably, the molar ratio of the organic ligand L to the metal salt is 2:3.

[0011] Preferably, the micron-sized fiber scaffold layer is prepared by melt-blowing polylactic acid with a weight-average relative molecular mass Mw of 100,000-300,000.

[0012] Secondly, the present invention provides a method for preparing multifunctional micro / nanofiber materials for high-efficiency air filtration, comprising the following steps:

[0013] S1: Polylactic acid scaffold layer is prepared using melt-blown process;

[0014] S2: Dissolve organic ligand L in organic solvent I to form solution A, and dissolve metal salt in organic solvent II to form solution B, wherein the molar ratio of organic ligand L to metal salt is 2:3;

[0015] S3: The polylactic acid scaffold layer prepared in step S1 is sequentially immersed in solution A and solution B for dip coating treatment. The polylactic acid scaffold layer after dip coating treatment is air-dried and then dried at room temperature to obtain multifunctional micro / nanofiber materials.

[0016] Preferably, the mass fraction of ligand L in solution A is 0.08%-0.15%.

[0017] Preferably, the mass fraction of the metal salt in solution B is 0.05%-0.09%.

[0018] Preferably, both organic solvent I and organic solvent II are independently selected from methanol, ethanol, isopropanol, n-butanol, tetrahydrofuran (THF), acetone, and methyl ethyl ketone.

[0019] Thirdly, the present invention also provides the application of the above-mentioned multifunctional micro / nanofiber materials for high-efficiency air filtration in the field of air filtration.

[0020] The multifunctional micro / nanofiber material for high-efficiency air filtration described in this invention innovatively designs a hierarchical, dual-scale fiber network by integrating metal-coordinated supramolecular self-assembly with industrial melt-blowing technology. This network embeds ultrafine metal-organic supramolecular nanofibers into a biodegradable polylactic acid microfiber scaffold (MON@PM filter material). This filter material achieves high filtration efficiency and low air resistance while possessing excellent antibacterial properties, breathability, and moisture management capabilities, providing a high-performance, scalable solution for addressing air pollution and public health challenges.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) Improved filtration performance

[0023] a. Highly efficient particle capture capability:

[0024] This invention uses nanoscale MON fibers (30-152nm) to construct an ultrafine filter network, achieving a PM2.5 particulate matter filtration efficiency of >99.5%, which is >11.3% higher than that of traditional non-floating meltblown PLA nonwoven fabric (78.2%).

[0025] Compared to traditional electret meltblown materials (which are susceptible to humidity), the material of this invention can still maintain a filtration efficiency of >99% under a relative humidity of 80%, and its stability is improved by more than 30%.

[0026] b. Low air resistance, improving breathability:

[0027] This invention optimizes the airflow channel through a dual-scale layered structure, which reduces air resistance to 39Pa while ensuring high filtration efficiency. This is 30%-50% lower than that of traditional high-efficiency electret filter materials (80-100Pa), resulting in a significant improvement in breathing comfort.

[0028] (2) Enhanced humidity stability

[0029] Traditional electret meltblown nonwoven fabrics suffer from reduced filtration efficiency due to electrostatic decay under high humidity conditions. However, this invention uses metal-organic supramolecular self-assembled nanofibers, which enhance particle capture ability through physical adsorption and are unaffected by external environmental factors, resulting in more than a twofold improvement in humidity stability.

[0030] (3) Enhanced moisture permeability ensures breathing comfort.

[0031] The enhanced capillary effect of the secondary nanomesh and the hydrophilicity of silver ions in this invention result in the MON@PM filter material prepared by this invention having a viscosity of 1472 g / m³. 2 The water molecule permeability of the day is significantly higher than that of PLA meltblown nonwoven fabric (419 g / m²). 2 ·day.

[0032] (4) Antibacterial function, enhancing health protection

[0033] The material of this invention contains Ag + It provides >99% antibacterial efficiency (against Escherichia coli, Staphylococcus aureus, etc.) through a cell membrane disruption mechanism. Compared to traditional HEPA filter materials (which have no antibacterial function), it can effectively inhibit the growth of microorganisms and improve long-term safety. Attached Figure Description

[0034] Figure 1 Raman spectra of dry gels obtained with different molar ratios of organic ligand L and metal salt (a is the Raman spectrum of organic ligand L; b is the molar ratio of organic ligand L to metal salt of 1:1 with a mass concentration of 0.224 wt%; c is the molar ratio of organic ligand L to metal salt of 2:3 with a mass concentration of 0.224 wt%; d is the molar ratio of organic ligand L to metal salt of 2:3 with a mass concentration of 1 wt%).

[0035] Figure 2 This is a scanning electron microscope image of filter-6 as described in Example 1;

[0036] Figure 3 This is a scanning electron microscope image of filter-8 as described in Example 2;

[0037] Figure 4 This is a scanning electron microscope image of filter-10 as described in Example 3;

[0038] Figure 5 The image shows a scanning electron microscope (SEM) image of filter-12 as described in Example 4.

[0039] Figure 6 Here is a scanning electron microscope image of the MON@PM filter material described in Comparative Example 1;

[0040] Figure 7 Here is a scanning electron microscope image of the MON@PM filter material described in Comparative Example 2;

[0041] Figure 8The figures show the filtration efficiency test results of the filter materials prepared in Examples 1-4 and Comparative Example 3. In the figure, a is a comparison of filtration efficiency and pressure drop at a wind speed of 32 L / min, b is the DEHS particulate matter filtration efficiency, c is the quality factor, d is a comparison of filtration efficiency at different wind speeds, and e is a comparison of pressure drop at different wind speeds.

[0042] Figure 9 The results of the moisture permeability test of the filter materials prepared in Example 3 and Comparative Example 3 are shown.

[0043] Figure 10 The results of air permeability tests are for the filter materials prepared in Example 3 and Comparative Example 3.

[0044] Figure 11 The antibacterial test results of the filter materials prepared in Example 3 and Comparative Example 3 are shown in the figure (a is the antibacterial image of Escherichia coli, b is the antibacterial image of Staphylococcus aureus, and c is the comparison of antibacterial rates).

[0045] Figure 12 The silver ion binding test results are shown for the filter material prepared in Comparative Example 4 (Figure a is a scanning electron microscope image, and Figure b is an energy dispersive spectroscopy (EDS) image).

[0046] Figure 13 The silver ion binding test results for filter-6 prepared in Example 1 are shown in the figure (a is a scanning electron microscope image, b is an energy dispersive spectroscopy (EDS) spectrum of Ag, and c is the L / Ag ratio of the organic ligand). + High-resolution dark-field transmission image of a single supramolecular nanofiber, where d represents the L / Ag ratio of the organic ligand. + Energy dispersive X-ray spectroscopy (EDS) of Ag in supramolecular nanofibers (e is the XPS full spectrum scan, and f is the XPS fine spectrum). Detailed Implementation

[0047] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0048] In this document, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0049] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0050] In this article, the terms "multiple" or "more than" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0051] In this document, the terms "preferred" and "more preferred" are used only to describe implementation methods or embodiments with better effects, and should be understood as not constituting a limitation on the scope of protection of this invention.

[0052] In this document, terms such as "further" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0053] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0054] In this document, the term "about" means a specified value of + / - 10%, preferably + / - 5%, and more preferably + / - 1%.

[0055] In this article, the terms “include,” “including,” “have,” “contain,” etc., are all open-ended terms, meaning that they include but are not limited to.

[0056] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0057] To determine the optimal molar ratio of organic ligand L to metal salt, solutions A (organic ligand L with different molar ratios dissolved in THF) and B (metal salt dissolved in THF) were mixed to obtain a wet gel, which was then dried to obtain a dry gel. Raman spectroscopy analysis was performed on the organic ligand L, different molar ratios of organic ligand L to metal salt, and the dry gels at different concentrations. The results are as follows: Figure 1 As shown in the figure. It is worth noting that for the same gel, the pyridine peak, which is the main focus of observation, is not significantly different between the wet and dry gels, except for the solvent peak; therefore, only the results for the dry gel are shown. It can be clearly seen from the figure that when the molar ratio of organic ligand L to metal salt is 1, with the addition of AgNO3, the peak at 1000 cm⁻¹... -1 The respiratory vibration peak of the pyridine ring ( Figure 1 (b) compared to pure organic ligands L( Figure 1 The decrease is significant in (a) but almost disappears when the molar ratio of organic ligand L to metal salt is 2 / 3. Figure 1 (c) Theoretically, 1000cm -1 The pyridine ring breathing vibration peak at the position is due to the N atom and Ag. + Coordination should shift towards higher wavenumbers, but here it's different from 1040 cm⁻¹. -1The pyridine ring triangular mode peaks overlapped. According to Ag... + The coordination chemistry of Ag shows that when Ag forms a coordination with pyridine, the two pyridine groups are often connected at an angle or similar angle to each other. + Therefore, when both sides contain ligands L and Ag containing three pyridine groups... + When the reaction occurs, if the molar ratio of the organic ligand L to the metal salt is 2 / 3, it can be guaranteed that pyridine can react with Ag. + Regarding coordination, the problem is that due to the poor solubility and rapid gelation rate of L / Ag+ coordination polymers, it is difficult to ensure that all pyridine groups on the L organic ligand can react with Ag+ during gel formation. + Therefore, there will always be Ag that is either uncoordinated or has only one position coordinated. + It exists. (In the diagram) Figure 1 b, Figure 1 Both gels in section c were prepared at very low concentrations. If the concentration is increased, the gelation rate will inevitably increase, which means that Ag cannot be completely coordinated. + The more free pyridinium groups there are, the more free pyridinium groups there will be. Figure 1 This was verified in d. It can be seen that, even with the same molar ratio of organic ligand L to metal salt = 2 / 3, due to the increased concentration, the peak representing the free pyridinium group is relatively higher. Figure 1 The middle 'c' has become larger again.

[0058] The present invention will be described in detail below with reference to the embodiments.

[0059] Example 1: Preparation of MON@PM filter material

[0060] The MON@PM filter material in this embodiment includes a micron-sized fiber scaffold layer and a nanofiber layer grown on the micron-sized fiber scaffold layer. The nanofiber layer is synthesized by a self-assembly method using metal salts and organic ligand L.

[0061] 1.1 Materials and Equipment

[0062] Raw material: Polylactic acid (PLA) (Mw = 150,000);

[0063] Metal salt: AgNO3;

[0064] Organic ligand L: Tris(3-pyridyl)benzene-1,3,5-tricarboxylic acid ester, with the following structural formula:

[0065]

[0066] Organic solvent: methanol;

[0067] Equipment: Meltblown spinning machine (SRY-600).

[0068] 1.2 Preparation steps

[0069] 1. PLA Meltblown Frame Fabrication: PLA meltblown frames were fabricated using a meltblown spinning machine with a 1.5-meter wide spinning die. During fabrication, polylactic acid melt was extruded through a screw extruder and metering pump, then decayed into ultrafine fibers in high-speed hot air. The fibers were subsequently collected on a stainless steel sieve under negative pressure. The die and screw temperatures were set to 230°C and 220°C, respectively. The flow rate of the polylactic acid (PLA) melt was approximately 0.1 g / min / hole, equivalent to a metering pump speed of 15 rpm. The hot air pressure at the die outlet was maintained at 0.04 MPa. Finally, the PLA meltblown nonwoven fabric was continuously collected using a roller collection system, resulting in the PLA meltblown frame.

[0070] 2. Preparation of MON nanofiber solution: Organic ligand L was dissolved in methanol to form solution A, with a mass fraction of 0.08%; 1.5 molar equivalents of AgNO3 relative to organic ligand L were dissolved in a water-methanol mixture (volume ratio of 4:5) to prepare solution B, with a mass fraction of 0.05%.

[0071] 3. Synthesis of MON@PM Filter Material: Using a dip-coating process, a PLA meltblown substrate was sequentially immersed in solution A and solution B, ensuring complete wetting until the weight of the PLA meltblown substrate no longer increased. The treated PLA meltblown substrate was first air-dried at room temperature to facilitate the growth of supramolecular nanofibers, and then dried to ensure complete solvent removal. The resulting MON@PM filter material was named filter-6, and its scanning electron microscope image is shown below. Figure 2 As shown.

[0072] Example 2

[0073] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the mass fraction of solution A is 0.1% and the mass fraction of solution B is 0.06%; all other aspects are the same as in Example 1. The obtained MON@PM filter material is named filter-8, and its scanning electron microscope image is shown below. Figure 3 As shown.

[0074] Example 3

[0075] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the mass fraction of solution A is 0.13% and the mass fraction of solution B is 0.075%; all other aspects are the same as in Example 1. The obtained MON@PM filter material is named filter-10, and its scanning electron microscope image is shown below. Figure 4 As shown.

[0076] Example 4

[0077] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the mass fraction of solution A is 0.15% and the mass fraction of solution B is 0.09%; all other aspects are the same as in Example 1. The obtained MON@PM filter material is named filter-12, and its scanning electron microscope image is shown below. Figure 5 As shown.

[0078] Example 5

[0079] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the metal salt is FeNO3; all other aspects are the same as in Example 1.

[0080] Example 6

[0081] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the metal salt is CuSO4; all other aspects are the same as in Example 1.

[0082] Example 7

[0083] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the metal salt is ZnCl2; all other aspects are the same as in Example 1.

[0084] Example 8

[0085] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the metal salt is CoCl2; all other aspects are the same as in Example 1.

[0086] Example 9

[0087] The only difference between the MON@PM filter material in this embodiment and that in Example 1 is that the metal salt is Ni(NO3)2·6H2O; all other aspects are the same as in Example 1.

[0088] Comparative Example 1

[0089] The only difference between the MON@PM filter material in this comparative example and Example 1 is that the mass fraction of solution A is 0.05% and the mass fraction of solution B is 0.03%; all other aspects are the same as in Example 1. The scanning electron microscope images are shown below. Figure 6 As shown.

[0090] Comparative Example 2

[0091] The only difference between the MON@PM filter material in this comparative example and Example 1 is that the mass fraction of solution A is 0.18% and the mass fraction of solution B is 0.1%; all other aspects are the same as in Example 1. The scanning electron microscope images are shown below. Figure 7 As shown.

[0092] Comparative Example 3

[0093] The filter material in this comparative example is the PLA meltblown support obtained in step 1 of Example 1, namely polylactic acid meltblown fabric.

[0094] Comparative Example 4

[0095] The filter material in this embodiment is the PLA meltblown support prepared in step 1 of Example 1, which is directly immersed in solution B, namely polylactic acid meltblown cloth-Ag.

[0096] The performance results of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1:

[0097] Table 1 Tensile strength test results

[0098] Serial Number Tensile strength (MPa) Example 1 5.7 Example 2 8.1 Example 3 10.5 Example 4 13.4 Comparative Example 1 A complete secondary nanonetwork was not formed. Comparative Example 2 The secondary mesh size is too small to be used for air filtration.

[0099] Test case

[0100] 1. Filtration efficiency test

[0101] Equipment: TOPAS AFC 131 filtration tester;

[0102] Test conditions:

[0103] Particulate matter: DEHS aerosols (particle size 0.196-4.595 μm);

[0104] Airflow velocity: 1.9 cm / s - 14.2 cm / s;

[0105] Relative humidity: 30%-80%;

[0106] Filter area: 176.63 cm² 2 .

[0107] The results are as follows Figure 9As shown, compared with the polylactic acid meltblown fabric of Comparative Example 3, the addition of the nanofiber layer significantly improved the filtration performance. All MON@PM filter materials exhibited filtration efficiencies of over 90%, especially Filter-12 prepared in Example 4, which achieved a filtration efficiency of 99.74%. For particles larger than 2.5 μm, all MON@PM filter materials showed filtration efficiencies exceeding 99.99%. Airflow velocity generally affects filtration performance. MON@PM filter materials showed a significant decrease in filtration efficiency when the airflow velocity exceeded 8 cm / s. In contrast, Filter-10 prepared in Example 3 and Filter-12 prepared in Example 4 maintained high filtration efficiencies even under high-speed airflow of 14.2 cm / s, revealing the contribution of the stable secondary nanonetwork structure to the interception of highly efficient particles. Furthermore, humidity had no significant effect on the adsorption effect; the MON@PM filter materials maintained a high filtration efficiency of over 90% within a humidity range of 30%–80%. After a long filtration test of 120 hours, the filtration efficiencies for PM2.5 and PM10 remained unchanged. Significantly stable, at 99.88% and 99.91% respectively. These findings demonstrate the superior filtration durability and long-term performance of the engineered MON@PM filter material.

[0108] 2. Moisture permeability test:

[0109] Equipment: Permeation cup;

[0110] Test method: GB / T 12704.1-2009;

[0111] Test results are as follows Figure 10 As shown, the water vapor transmission rate (WVTR) of the MON@PM filter material of the present invention reaches 1472 g / (m²·day), while the water vapor transmission rate of the polylactic acid meltblown nonwoven fabric of Comparative Example 3 is 419 g / (m²·day).

[0112] 3. Breathability test:

[0113] Equipment: Fabric air permeability tester;

[0114] Test method: GB / T 24218.15-2018;

[0115] The results are as follows Figure 11 As shown, the air permeability of the MON@PM filter material of this invention is 105.7 mm·s. -1 The load of the secondary nanomesh did not significantly improve air permeability. The air permeability of the polylactic acid meltblown nonwoven fabric in Comparative Example 3 was 99.1 mm / s. -1 .

[0116] 4. Antibacterial test:

[0117] Test method:

[0118] Measure 100 mL of distilled water into a 250 mL reagent bottle using a graduated cylinder. Weigh 2.5 g of LB broth culture medium and add it to the bottle using an analytical electronic balance. Mix well and sterilize in a high-temperature, high-pressure steam autoclave at 121°C for 15 minutes. Measure 100 mL of distilled water into a 250 mL reagent bottle using a graduated cylinder. Weigh 2.5 g of LB broth culture medium and 1.5 g of agar powder using an analytical electronic balance. Add the weighed reagents to the bottle and mix well. Sterilize in a high-temperature, high-pressure steam autoclave at 121°C for 15 minutes. Once the culture medium has cooled to approximately 40-50°C, use a power pipette to transfer 15 mL of the medium into a disposable sterile Petri dish. Take a 12 mL bacterial culture tube and add 3 mL of LB liquid culture medium. Pick single colonies from the solid culture media of *E. coli* and *Staphylococcus aureus* and add them to the liquid culture medium. Incubate in a constant-temperature shaker (37°C, 200 rpm) for 15 hours. Cut the sample into 4 equal parts (each part weighing 12mg), take one part of each type and place it in a disposable sterile dish, sterilize it by irradiating both sides with ultraviolet light for 30 minutes, and set aside.

[0119] The experiment consisted of a control group and an experimental group, with the experimental group further divided into group 1 and group 2, and each group was replicated once. *Escherichia coli* and *Staphylococcus aureus* bacterial suspensions were diluted to 10⁻¹⁰ using LB liquid medium. 6 CFU / mL was collected, and then the corresponding samples were added according to the groups, along with 25 μL of diluted bacterial suspension. The co-culture solution was incubated at 37°C for 18 h. After incubation, the culture was washed with 5 mL of sterile PBS, and then the bacterial solution was serially diluted 10-fold with sterile PBS. 100 μL of each dilution was evenly spread onto LB solid medium. The culture was incubated at 37°C for 18 h, and then photographed and the colony count was recorded.

[0120] The results are as follows Figure 11 As shown, the MON@PM filter material of the present invention has an antibacterial rate of greater than 99.9% against both Escherichia coli and Staphylococcus aureus.

[0121] 5. Silver ion release test

[0122] Equipment: Inductively coupled plasma mass spectrometer (ICP-MS, 7800(MS), Agilent Technologies, USA);

[0123] Test method: The MON@PM filter material prepared in Example 1 was cut into 2.50cm × 2.50cm squares and placed in 100.00mL of deionized water for immersion at room temperature. 10.00mL of sample solution was taken at predetermined time intervals for ICP-MS analysis.

[0124] The results showed that the total amount of silver ions released by the MON@PM filter material over seven days was 0.78 μg / mL, which was higher than the reported minimum concentration required for effective antibacterial activity in aqueous systems (0.01 μg / mL), but lower than the median lethal concentration (LD50) in vitro. 50 =1.42 μg / mL).

[0125] 6. Silver ion binding test

[0126] The MON@PM filter material prepared in Example 1 and the polylactic acid meltblown fabric-Ag prepared in Comparative Example 4 were subjected to high-magnification transmission electron microscopy and energy dispersive spectroscopy analysis, respectively. The results are as follows: Figure 12 and Figure 13 As shown. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) images reveal that polylactic acid meltblown fabric-Ag (… Figure 12 a and Figure 12 In b), silver ions are distributed across the entire plane of the meltblown fabric and do not adhere individually to the fibers.

[0127] Compared with the MON@PLA filter material of the present invention ( Figure 13 c. Figure 13 The scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) images in section d) show that silver ions are more tightly bound to the surface of the MON@PM filter material. Silver ions form a stronger bond with the nanofiber surface through supramolecular self-assembly, resulting in a more uniform and dense distribution of silver on these fibers.

[0128] Figure 13 The transmission electron microscopy (TEM) image in Figure c shows that aggregated silver nanoparticles are uniformly distributed on the MON@PM filter material. These silver nanoparticles exhibit a significant nanoscale size and are distributed on the fiber surface, demonstrating the aggregation of silver in nanoparticle form. Additionally, XPS full-spectrum and fine-spectrum images (…) Figure 13 e and Figure 13 f) This further confirms the presence of silver nanoparticles. XPS analysis confirms that silver ions form a relatively stable silver nanoparticle structure on the surface of supramolecular nanofibers. Due to their small size and uniform distribution, silver nanoparticles generally exhibit low toxicity. The low toxicity of silver nanoparticles, especially when they are small in size and uniformly dispersed, can reduce their potential risks to the environment and organisms.

[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multifunctional micro / nanofiber material for high-efficiency air filtration, characterized in that: The multifunctional micro / nanofiber material comprises a micron-scale fiber scaffold layer and a nanofiber layer grown on the micron-scale fiber scaffold layer. The nanofiber layer is synthesized by a self-assembly method using a metal ion donor and an organic ligand L. The organic ligand L is tris(3-pyridyl)phenyl-1,3,5-tricarboxylic acid ester, and its structural formula is: ； The metal ion donor is AgNO3; The preparation method of the multifunctional micro / nanofiber material includes the following steps: S1: Polylactic acid scaffold layer is prepared using melt-blown process; S2: Dissolve organic ligand L in organic solvent I to form solution A, and dissolve AgNO3 in organic solvent II to form solution B, wherein the molar ratio of organic ligand L to AgNO3 is 2:3; S3: The polylactic acid scaffold layer prepared in step S1 is sequentially immersed in solution A and solution B for dip coating treatment. The polylactic acid scaffold layer after dip coating treatment is air-dried and then dried at room temperature to obtain multifunctional micro / nanofiber materials.

2. The multifunctional micro / nanofiber material for high-efficiency air filtration according to claim 1, characterized in that: The micron-scale fiber scaffold layer is prepared by melt-blowing polylactic acid with a weight-average relative molecular mass Mw of 100,000-300,000.

3. The multifunctional micro / nanofiber material for high-efficiency air filtration according to claim 1, characterized in that: The mass fraction of ligand L in solution A is 0.08%-0.15%.

4. The multifunctional micro / nanofiber material for high-efficiency air filtration according to claim 1, characterized in that: The mass fraction of AgNO3 in solution B is 0.05%-0.09%.

5. The multifunctional micro / nanofiber material for high-efficiency air filtration according to claim 1, characterized in that: Both organic solvent I and organic solvent II are independently selected from methanol, ethanol, isopropanol, n-butanol, tetrahydrofuran, acetone, and methyl ethyl ketone.

6. The application of the multifunctional micro / nanofiber material for high-efficiency air filtration as described in any one of claims 1-5 in the field of air filtration.

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