A high-porosity corrosion-resistant armoring structure fiber membrane and a preparation method and application thereof

Abstract

The application provides a high-pore corrosion-resistant armoured structure fiber membrane and a preparation method and application thereof, and the method comprises the following steps: step S1, dissolving polylactic acid in an organic solvent to prepare a spinning dope; step S2, preparing a polylactic acid nanofiber membrane through a spinning technology; step S3, dissolving bromine monomers, alkyne monomers and a catalyst in a reaction solvent to prepare a conjugated microporous polymer precursor solution; and step S4, taking the polylactic acid nanofiber membrane obtained in step S2 as a solid template, placing the solid template in the conjugated microporous polymer precursor solution obtained in step S3, and preparing a fiber membrane through a coupling reaction in an inert gas atmosphere. The fiber membrane prepared by the application has the advantages of a large specific surface area, uniform pore distribution, corrosion-resistant steam erosion resistance, excellent dust filtration performance and the like, and has a fiber armoured structure, and is a high-performance multi-field dust and toxic gas synchronous filtration gas purification material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of controllable synthesis induced by fiber membranes, and in particular to a high-porosity corrosion-resistant fiber membrane for simultaneously filtering dust and toxic gases, and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen sulfide (H2S) is a colorless, highly toxic, acidic gas with a rotten egg odor, which is usually present in natural gas and biogas. Due to its extremely strong toxicity, even a low concentration of H2S can have a serious impact on human health and the atmospheric environment. People have explored various methods to reduce H2S emissions, including absorption, adsorption technology, membrane separation, catalytic oxidation, etc. However, due to the limitations of the acidic characteristics of H2S gas, strict requirements are placed on the pore and physicochemical properties of the materials used. Although H2S is harmful to the human body, it is also a valuable resource that can be recovered and converted into sulfur and mercaptans and other high-value products. At the same time, most of the emitted H2S gas streams inevitably carry harmful particulate matter such as dust, making it more difficult to filter out simultaneously. Therefore, for environmental protection and economic reasons, it is particularly important to develop a high-porosity corrosion-resistant material for simultaneous filtration of dust and toxic gases.

[0003] In recent decades, researchers have been studying various materials for removing H2S, including metal-organic frameworks (MOFs) and metal-free adsorbents (porous carbon materials, covalent organic frameworks (COFs), and covalent organic polymers (COPs)). However, these adsorbents have certain limitations that hinder their practical application. For example, MOFs have a large number of unsaturated metal sites, are structurally unstable, and are easily affected by acidic environments, leading to structural collapse and deformation, which significantly reduces the adsorption capacity and cycle life. The preparation of carbon materials usually requires high-temperature calcination, which is energy-consuming and complex, and the sulfur adsorption capacity is low and the active sites are insufficient. In addition, COFs and COPs also have problems such as high ligand cost, complex synthesis process, and poor H2S adsorption capacity. These inherent shortcomings greatly limit their practical application. Therefore, it is urgent to design a new type of adsorbent with low cost, simple operation, and strong H2S adsorption capacity to overcome these limitations.

[0004] The synthesis and application of polymer nanocomposites have attracted much attention from researchers and are currently in a stage of rapid innovation and development. Polymer nanofibers, as a key component of composites, have various preparation methods, including template synthesis, self-assembly, phase separation, etc. However, these methods have limitations such as complex process, high cost, and limited production. In contrast, the spinning method, as an important preparation method, has significant advantages such as mature process, continuous production, and easy scaling, and can efficiently prepare high-quality polymer nanofibers to meet the growing demand for nanofiber materials in different fields. Conjugated microporous polymers (CMPs) are a class of organic porous polymers with π-conjugated framework and permanent microporous structure, which are formed by covalently linked organic building blocks. As a kind of porous organic polymer (POPs) material, CMPs have a large specific surface area, adjustable pore size, controllable composition and structure, and moisture and acid and alkali resistance. In-situ growth of CMPs on degradable polylactic acid spinning membranes can significantly enhance the physical and chemical stability and porous properties of the fiber membranes, and is expected to improve the dust filtration efficiency and gas adsorption capacity while combining the low gas permeation resistance of nanofiber membranes. SUMMARY

[0005] The main purpose of the present application is to prepare a fiber membrane with rich porosity and acid and alkali resistance and corrosion resistance that can simultaneously filter dust and toxic gases, to solve the problem of low dust filtration efficiency and low gas adsorption capacity of existing dust and toxic gas simultaneous filtration gas purification materials.

[0006] To achieve the above-mentioned purpose, the present application provides a high-porosity corrosion-resistant armored structure fiber membrane and its preparation method and application. According to the first aspect of the present application, a method for preparing a high-porosity corrosion-resistant armored structure fiber membrane is provided, comprising the following steps: step S1, preparation of polylactic acid spinning solution: uniformly dispersing polylactic acid (PLA) in an organic solvent to prepare a polylactic acid spinning solution; step S2, preparation of polylactic acid nanofiber membrane: preparing a polylactic acid nanofiber membrane by spinning technology using the polylactic acid spinning solution obtained in step S1; step S3, preparation of conjugated microporous polymer precursor solution: fully dissolving bromine monomer, alkyne monomer, and catalyst in a reaction solvent to prepare a conjugated microporous polymer precursor solution; step S4, preparation of high-porosity corrosion-resistant fiber membrane: using the polylactic acid nanofiber membrane obtained in step S2 as a solid template, placing it in the conjugated microporous polymer precursor solution obtained in step S3, and allowing a coupling reaction to occur in an inert gas atmosphere to prepare a high-porosity corrosion-resistant fiber membrane with a fiber armored structure.

[0007] As a preferred embodiment, the organic solvent in step S1 is one or more of dichloromethane, trichloromethane, chloroform, acetone, ethyl acetate, N,N-dimethylformamide, methanol, ethanol, toluene, and triethylamine, and the concentration of polylactic acid in the polylactic acid spinning solution is 0.5-30 wt%.

[0008] As preferred, the spinning technique in step S2 is one or more of high-voltage electrostatic spinning, high-speed airflow spinning, high-speed centrifugal spinning, and high-temperature melt spinning, and the obtained polylactic acid nanofiber membrane has a thickness of 50-150 μm and a fiber average diameter of 50-500 nm.

[0009] As preferred, the alkyne monomer in step S3 is one or more of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene, 1,3,6,8-tetraethynylpyrene, 2,4,6-tris-4-ethynylphenyl-1,3,5-triazine, and tris-4-ethynylphenylamine; the bromine monomer is one or more of 2,6-dibromophenol, tribromophenol, tetrabromophenol, pentabromophenol, 2,6-dibromo-4-methylphenol, bromophenacyl bromide, and 4-amino-2,6-dibromophenol, and the functional group molar ratio of the bromine monomer to the alkyne monomer is 5:1-1:5.

[0010] As preferred, the catalyst in step S3 is a palladium-based catalyst and a copper-based catalyst, the palladium-based catalyst is one or more of palladium acetate, palladium chloride, tetrakis(triphenylphosphine)palladium, bis(dibenzylideneacetone)dipalladium, and palladium-carbon catalyst, the copper-based catalyst is one or more of cuprous iodide, cuprous bromide, copper chloride, copper acetate, copper sulfate, and nano-copper catalyst, and the molar ratio of the palladium-based catalyst to the copper-based catalyst is 1:5-1:20.

[0011] As preferred, the reaction solvent in step S3 is a mixed solution of one of toluene, dichloromethane, chloroform, tetrahydrofuran, 1,2-dichloroethane, acetonitrile, dioxane, pyridine, and N,N-dimethylformamide and triethylamine, and the volume ratio of the above-mentioned one to triethylamine is 5:1-1:5.

[0012] As preferred, the inert gas atmosphere in step S4 uses one or more of nitrogen, helium, neon, argon, krypton, and xenon, and the purity of the inert gas is kept above 99.9%.

[0013] As preferred, the coupling reaction in step S4 is a Sonogashira coupling reaction, the reaction temperature is 40-80℃, and the reaction time is 24-72 hours.

[0014] As preferred, the organic solvent in step S1 is selected from N,N-dimethylformamide and dichloromethane, and the mass ratio is 3:7.

[0015] To achieve the above-mentioned purpose, according to the second aspect of the present application, the present application also provides a fiber membrane obtained by the above-mentioned preparation method, which has a fiber armoring structure (fiber average diameter of 650-780 nm), a high specific surface area (277 m 2 / g-324 m 2 / g), small pore size (1.87 nm-2.29 nm), high dust (PM 0.3 and PM 2.5 The characteristics of the high filtration efficiency of more than 96.8% and the high adsorption capacity of more than 4.9 mmol / g of H2S.

[0016] In order to achieve the above-mentioned purpose, according to the third aspect of the present application, the present application also provides the application of the above-mentioned fiber membrane in the filter material for simultaneously filtering out ultrafine dust and toxic gas.

[0017] The present application has the beneficial effects that: by applying the technical scheme of the present application, the preparation method of the high-porosity corrosion-resistant armored structure fiber membrane of the present application, (1) the polylactic acid nanofiber membrane is used as a solid template, and the conjugated microporous polymer is uniformly encapsulated on the fiber surface through molecular level interaction induction, so as to reduce the disordered accumulation and agglomeration of the porous polymer; (2) the conjugated microporous polymer is uniformly encapsulated on the outer wall of the fiber tube, so as to promote the fiber membrane to have rich porosity, and at the same time, the problem of poor processability and difficult forming of the conjugated microporous polymer is solved, and the application range and scene of the fiber membrane are widened; (3) the rigid conjugated skeleton of the conjugated microporous polymer itself endows the polylactic acid nanofiber membrane with excellent acid and alkali corrosion resistance, and the three-dimensional network structure of electrospinning reduces the mass transfer resistance of airflow, so that the simultaneous filtration of dust and toxic gas can be realized; (4) the steps are mutually synergistic, not only have excellent porosity, but also have excellent acid and alkali corrosion resistance, effectively solving the demand for simultaneous filtration of dust and toxic gas, and having wide application potential and market prospect.

[0018] The fiber membrane of the present application not only has a series of advantages such as large specific surface area, uniform pore distribution, corrosion resistance to steam erosion, excellent dust filtration performance, ideal adsorption capacity of toxic gas, etc., but also has a unique fiber armored structure, simple preparation process and mild conditions, and is a high-performance multi-field dust and toxic gas simultaneous filtration gas purification material. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is a scanning electron microscope image of the high-porosity corrosion-resistant fiber membrane in Example 1.

[0021] Figure 2is a transmission electron microscope image of the high-porosity corrosion-resistant fiber membrane in Example 1.

[0022] Figure 3 is a Fourier transform infrared spectrogram of the high-porosity corrosion-resistant fiber membrane in Example 2.

[0023] Figure 4 is a powder X-ray diffraction spectrogram of the high-porosity corrosion-resistant fiber membrane in Example 3.

[0024] Figure 5 is a nitrogen adsorption-desorption isotherm graph of the high-porosity corrosion-resistant fiber membrane in Example 4.

[0025] Figure 6 is a pore size distribution graph of the high-porosity corrosion-resistant fiber membrane in Example 4.

[0026] Figure 7 is a flowchart of the method of the present application. DETAILED DESCRIPTION

[0027] In order to make the objects, technical solutions, and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application. The present application will be described in detail below in combination with the embodiments.

[0028] As Figure 7As shown, the embodiment 1 of the present application provides a preparation method of a high-porous corrosion-resistant armoring structure fiber membrane, comprising the following steps: step S11, preparation of a polylactic acid spinning solution: uniformly dispersing polylactic acid (PLA) in a mixed solvent composed of N,N-dimethylformamide and acetone (mass ratio 4:1) to prepare a polylactic acid spinning solution, and the concentration of polylactic acid in the polylactic acid spinning solution is 11 wt%; step S12, preparation of a polylactic acid nanofiber membrane: preparing a polylactic acid nanofiber membrane by high-pressure electrospinning technology (working voltage 2-60 kV, spraying speed 0.5-5 mL / h, receiving distance 15-25 cm, temperature 10-50°C, relative humidity 10-70%, reciprocating speed 1-5 cm / min) from the polylactic acid spinning solution obtained in step S11, the thickness of the obtained fiber membrane is 50-150 μm, and the average diameter of the polylactic acid nanofiber is 50-500 nm; step S13, preparation of a conjugated microporous polymer precursor solution: fully dissolving 2,6-dibromophenol and 1,3,5-triethynylbenzene (functional group molar ratio 1:1), tetrakis triphenylphosphine palladium and cuprous iodide (molar ratio 1:10) in a reaction solvent composed of toluene and triethylamine (volume ratio 1:1) to prepare a conjugated microporous polymer precursor solution; step S14, preparation of a high-porous corrosion-resistant fiber membrane: taking the polylactic acid nanofiber membrane obtained in step S12 as a solid template, placing it in the conjugated microporous polymer precursor solution obtained in step S13, replacing the air in the reaction system with nitrogen at room temperature, slowly increasing the temperature from room temperature to 50°C, and reacting for 48 hours to prepare a high-porous corrosion-resistant fiber membrane with a fiber armoring structure, the average diameter of the armoring fiber is 700 nm, the specific surface area is 324 m 2 / g, and the average pore size is 1.87 nm.

[0029] Embodiment 2 of the present application provides a preparation method of a high-pore corrosion-resistant armoring structure fiber membrane, comprising the following steps: Step S21, preparation of a polylactic acid spinning solution: uniformly dispersing polylactic acid (PLA) in a mixed solvent composed of N,N-dimethylformamide and dichloromethane (mass ratio 3:7) to prepare a polylactic acid spinning solution, the concentration of polylactic acid in the solution being 9 wt%; Step S22, preparation of a polylactic acid nanofiber membrane: preparing a polylactic acid nanofiber membrane by high-speed airflow spinning technology (jet angle 15-60°, jet speed to extrusion speed ratio 1k-30k, jet pressure 0.2-10 MPa, airflow temperature 25-85°C, relative humidity 40-80%) from the polylactic acid spinning solution obtained in Step S21, the obtained fiber membrane having a thickness of 150 μm and the polylactic acid nanofiber having an average diameter of 400 nm; Step S23, preparation of a conjugated microporous polymer precursor solution: fully dissolving tribromophenol and 1,4-diethynylbenzene (functional group molar ratio 1:3), palladium chloride and cuprous bromide (molar ratio 1:5) in a reaction solvent composed of dichloromethane and triethylamine (volume ratio 2:1) to prepare a conjugated microporous polymer precursor solution; Step S24, preparation of a high-pore corrosion-resistant fiber membrane: taking the polylactic acid nanofiber membrane obtained in Step S22 as a solid template, placing it in the conjugated microporous polymer precursor solution obtained in Step S23, replacing the air in the reaction system with nitrogen at room temperature, slowly increasing the temperature from room temperature to 80°C, and reacting for 24 hours to prepare a high-pore corrosion-resistant fiber membrane with a fiber armoring structure, the obtained armoring fiber having an average diameter of 780 nm, a specific surface area of 306 m 2 / g, and an average pore size of 2.11 nm.

[0030] Embodiment 3 of the present application provides a preparation method of a high-porosity corrosion-resistant armoring structure fiber membrane, comprising the following steps: Step S31, preparation of a polylactic acid spinning solution: uniformly dispersing polylactic acid (PLA) in a mixed solvent composed of dichloromethane and N,N-dimethylformamide (mass ratio 7:3) to prepare a polylactic acid spinning solution, the concentration of polylactic acid in the solution being 13 wt%; Step S32, preparation of a polylactic acid nanofiber membrane: preparing a polylactic acid nanofiber membrane by high-speed centrifugal spinning technology (centrifugal rotation speed 1k-50k, rotation radius 5-50 cm, solution supply rate 0.1-10 ml / h, receiving distance 10-50 cm, ambient temperature 15-35℃, relative humidity 30-60%) from the polylactic acid spinning solution obtained in Step S31, the thickness of the obtained fiber membrane being 50 μm, and the average diameter of the polylactic acid nanofiber being 200 nm; Step S33, preparation of a conjugated microporous polymer precursor solution: fully dissolving tetrabromophenol and 1,3,6,8-tetraethynylpyrene (functional group molar ratio 3:1), palladium acetate and copper acetate (molar ratio 1:15) in a reaction solvent composed of chloroform and triethylamine (volume ratio 2:1) to prepare a conjugated microporous polymer precursor solution; Step S34, preparation of a high-porosity corrosion-resistant fiber membrane: taking the polylactic acid nanofiber membrane obtained in Step S32 as a solid template, placing it in the conjugated microporous polymer precursor solution obtained in Step S33, replacing the air in the reaction system with nitrogen at room temperature, slowly increasing the temperature from room temperature to 40℃, and reacting for 72 hours to prepare a high-porosity corrosion-resistant fiber membrane with a fiber armoring structure, the average diameter of the armored fiber being 650 nm, the specific surface area being 291 m 2 / g, and the average pore size being 2.17 nm.

[0031] Embodiment 4 of the present application provides a preparation method of a high-porosity corrosion-resistant armoring structure fiber membrane, comprising the following steps: Step S41, preparation of a polylactic acid spinning solution: uniformly dispersing polylactic acid (PLA) in a mixed solvent composed of dichloromethane and acetone (mass ratio 6:4) to prepare a polylactic acid spinning solution, and the concentration of polylactic acid in the solution is 11wt%; Step S42, preparation of a polylactic acid nanofiber membrane: preparing a polylactic acid nanofiber membrane by high-temperature melt spinning technology (melting temperature is 100-150℃, heating rate is 5-20℃ / min, pressure control is 1-10 MPa, spinning speed is 500-5000 m / min, draw ratio is 1-10 times, and collection distance is 0.3-1.0 m) from the polylactic acid spinning solution obtained in Step S41, the obtained fiber membrane has a thickness of 70 μm, and the average diameter of the polylactic acid nanofiber is 280 nm; Step S43, preparation of a conjugated microporous polymer precursor solution: fully dissolving penta-bromophenol and 1,3,5-triethynylbenzene (functional group molar ratio is 1:2), tris-dibenzalacetone palladium and copper sulfate (molar ratio is 1:10) in a reaction solvent composed of 1,2-dichloroethane and triethylamine (volume ratio is 3:2) to prepare a conjugated microporous polymer precursor solution; Step S44, preparation of a high-porosity corrosion-resistant fiber membrane: taking the polylactic acid nanofiber membrane obtained in Step S42 as a solid template, placing it in the conjugated microporous polymer precursor solution obtained in Step S43, replacing the air in the reaction system with nitrogen at room temperature, slowly increasing the temperature from room temperature to 60℃, and reacting for 48 hours to prepare a high-porosity corrosion-resistant fiber membrane with a fiber armoring structure, the average diameter of the armoring fiber is 720 nm, the specific surface area is 277 m 2 / g, and the average pore size is 2.29 nm.

[0032] Comparative Example 1 of the present application provides a preparation method of a high-porosity corrosion-resistant armoring structure fiber membrane, which is basically prepared by the method of Embodiment 1. The difference is that, in this example, the polylactic acid nanofiber membrane is not used as a solid template, and the conjugated microporous polymer is directly synthesized. Specifically, 2,6-dibromophenol and 1,3,5-triethynylbenzene (functional group molar ratio is 1:1), tetrakis-triphenylphosphine palladium and cuprous iodide (molar ratio is 1:10) are fully dissolved in a reaction solvent composed of toluene and triethylamine (volume ratio is 1:1) to prepare a conjugated microporous polymer precursor solution; the obtained conjugated microporous polymer precursor solution is replaced with nitrogen at room temperature to replace the air in the reaction system, the temperature is slowly increased from room temperature to 50℃, and the reaction is carried out for 48 hours to prepare a powder-shaped conjugated microporous polymer, the specific surface area is 57 m 2 / g, and the average pore size is 2.45 nm.

[0033] The present application provides a preparation method of a high-porosity corrosion-resistant fiber film for Comparative Example 2. The high-porosity corrosion-resistant fiber film is prepared by the method of Example 2. The difference is that polyvinylidene fluoride nanofiber membrane is used as a solid template to prepare the high-porosity corrosion-resistant fiber film. Specifically, polyvinylidene fluoride (PVDF) is uniformly dispersed in a mixed solvent composed of N,N-dimethylformamide and dichloromethane (mass ratio 3:1), and the concentration of polylactic acid in the solution is 9 wt%, to prepare a polylactic acid spinning dope; the obtained polylactic acid spinning dope is prepared into a polyvinylidene fluoride nanofiber membrane by high-speed airflow spinning technology (jet angle 15-60°, jet speed to extrusion speed ratio 1k-30k, jet pressure 0.2-10 MPa, airflow temperature 25-85°C, relative humidity 40-80%), the obtained polylactic acid fiber membrane has a thickness of 150 μm and an average nanofiber diameter of 400 nm; tribromophenol and 1,4-diethynylbenzene (functional group molar ratio 1:3), palladium tetrachloride and cuprous bromide (molar ratio 1:5) are dissolved in a reaction solvent composed of dichloromethane and triethylamine (volume ratio 2:1) to prepare a conjugated microporous polymer precursor solution; the obtained polyvinylidene fluoride nanofiber membrane is used as a solid template and is placed in the obtained conjugated microporous polymer precursor solution, the air in the reaction system is replaced by nitrogen at room temperature, the temperature is slowly increased from room temperature to 80°C, and the reaction time is 24 hours, to prepare a high-porosity corrosion-resistant fiber film with a fiber armoring structure, the obtained fiber has an average diameter of 850 nm, a specific surface area of 91 m 2 / g, and an average pore size of 2.26 nm.

[0034] The preparation method of the high-pore corrosion-resistant armoring structure fiber membrane of the present application is provided in Comparative Example 3. The high-pore corrosion-resistant fiber membrane is prepared by the method of Example 3. The difference is that the conjugated microporous polymer shell is prepared using a polyaromatic benzene ring monomer in this example. Specifically, polylactic acid (PLA) is uniformly dispersed in a mixed solvent composed of dichloromethane / N,N-dimethylformamide (mass ratio 7:3), and the concentration of the polylactic acid in the solution is 13 wt%, to prepare a polylactic acid spinning dope; the obtained polylactic acid spinning dope is prepared into a polylactic acid nanofiber membrane by high-speed centrifugal spinning technology (centrifugal rotation speed 1k-50k, rotation radius 5-50 cm, solution supply rate 0.1-10 ml / h, receiving distance 10-50 cm, ambient temperature 15-35°C, relative humidity 30-60%); the obtained fiber membrane has a thickness of 50 μm, and the average diameter of the polylactic acid nanofiber is 200 nm; 3,9-dibromoperylene and 1,3,6,8-tetraethynylpyrene (functional group molar ratio 3:1), palladium acetate and copper acetate (molar ratio 1:15) are dissolved in a reaction solvent composed of trichloromethane and triethylamine (volume ratio 2:1) to prepare a conjugated microporous polymer precursor solution; the obtained polylactic acid nanofiber membrane is used as a solid template and is placed in the obtained conjugated microporous polymer precursor solution; the air in the reaction system is replaced by nitrogen at room temperature, and the temperature is slowly increased from room temperature to 40°C; the reaction time is 72 hours, to prepare a high-pore corrosion-resistant fiber membrane with a fiber armoring structure, and the average diameter of the obtained fiber is 680 nm, the specific surface area is 97 m 2 / g, and the average pore size is 2.22 nm.

[0035] The structural characterization and performance testing are as follows.

[0036] Scanning electron microscope observation: the microstructure of the high-pore corrosion-resistant fiber membrane is observed by a field emission scanning electron microscope (model JSM-7900F, Japan Electron) ( Figure 1 ).

[0037] Transmission electron microscope observation: the microstructure of the high-pore corrosion-resistant fiber membrane is observed by a field emission transmission electron microscope (model TECNI G2 TF20, FEI Company, Netherlands) ( Figure 2 ).

[0038] Functional group structure testing: an infrared spectrometer (model VERTEX 70, Bruker, USA) is used to record the functional groups of the high-pore corrosion-resistant fiber membrane ( Figure 3 ).

[0039] Crystal structure testing: an X-ray spectrometer (model D / Max-2400, Rigaku, Japan) is used to record the crystal structure of the high-pore corrosion-resistant fiber membrane ( Figure 4).

[0040] Specific surface area test: The nitrogen adsorption isotherm of the high-porosity corrosion-resistant fiber membrane was measured at 77 K using a gas adsorption instrument (ASAP 2060, Micromeritics, USA) Figure 5 、 Figure 6 ).

[0041] Filtering performance test: The air filtering performance of the fiber membrane (area 25 cm 2 ) was tested using a CLJ-3016 type laser dust particle counter (Shenzhen Huashengchang Machinery Experiment Co., Ltd.). The gas flow rate was set to 85 L / min. Each group of filtering membranes was tested at least 3 different positions, and the average value was taken.

[0042] Hydrogen sulfide adsorption performance test: H2S was adsorbed using a gas adsorption instrument (ASAP 2020, Micromeritics, USA). High-purity gas H2S (99.999%) was used for adsorption measurement, and free space was measured with helium (99.999%). Isothermal adsorption was carried out at 273 K (ice water bath) and 298 K (water bath).

[0043] The experimental results are shown below, Figure 1 The scanning electron microscope image of the high-porosity corrosion-resistant fiber membrane obtained in Example 1 shows that the polylactic acid nanofiber is uniformly encapsulated with a conjugated microporous polymer shell, and the average diameter of the fiber is 700 nm. Due to the guidance of the polylactic acid nanofiber membrane template effect, the membrane product of the cross-coupled conjugated microporous polymer presents a nanotube armoring form, which is uniformly encapsulated in the polylactic acid nanofiber tube, proving that the template preparation method can change the micro-morphology of the conjugated microporous polymer. In addition, it is found in Comparative Example 3 that the type of monomer will affect the encapsulation phenomenon on the surface of the conjugated microporous polymer nanotube. A large number of conjugated microporous polymer particles attached to the tube wall can be clearly seen.

[0044] Figure 2 The transmission electron microscope image of the high-porosity corrosion-resistant fiber membrane in Example 1 shows that the conjugated microporous polymer is uniformly wrapped on the surface of the polylactic acid fiber, and there is no obvious agglomeration or dissociation. The shell thickness of the conjugated microporous polymer is measured to be in the range of 100-200 nm. In addition, it is found in Comparative Example 3 that the type of monomer will affect the encapsulation thickness on the surface of the conjugated microporous polymer nanotube.

[0045] Figure 3 The Fourier transform infrared spectrum of the high-porosity corrosion-resistant fiber membrane in Example 2 shows that the peak at 3450 cm −1 proves the stretching vibration related to the O-H band connected with intermolecular and intramolecular hydrogen bonds. The peak at 3039 cm −12834 cm −1 The peak between 1000 and 1140 cm −1 -1 gradually broadened is the C-O vibration of the phenol group, and the above results show that the conjugated microporous polymer is uniformly synthesized on the polylactic acid nanofiber, and there is a molecular level interaction between the two.

[0046] Figure 4 is the powder X-ray spectrum of the high-porosity corrosion-resistant fiber membrane in Example 3, the spectrum has a wide diffraction peak at 20º, the peak position of the fiber membrane after the synthesis of the conjugated microporous polymer does not change, indicating that the crystal structure of the membrane does not change, and it is an amorphous polymer similar to the conjugated microporous polymer, without a fixed crystal structure.

[0047] As shown in Figure 5 , the nitrogen adsorption-desorption isotherm curve of the high-porosity corrosion-resistant fiber membrane in Example 4 of the application shows a mixed curve of type I and type IV isotherms, indicating that there are micropores and mesopores in the fiber membrane. As shown in Figure 6 , the pore size distribution curve of the high-porosity corrosion-resistant fiber membrane in Example 4 of the application shows a continuous pore size distribution, which is composed of a large number of nanopores with a pore size of less than 10 nm, corresponding to a microporous structure.

[0048] The adsorption-desorption isotherms show similar trends, i.e., a middle pressure section with gradually increasing nitrogen adsorption and a high pressure section with rapid nitrogen adsorption, and the pore size distribution curve shows that the integral adsorbent has a hierarchical porous structure.

[0049] Table 1 compares the specific surface area, pore size, average fiber diameter, filtration efficiency, and hydrogen sulfide adsorption capacity of the high-porosity corrosion-resistant fiber membranes obtained in the examples and comparative examples, as shown in the following table.

[0050] Table 1

[0051]

[0052] Examples 1-4 have a relatively high specific surface area (277 m 2 / g-324 m 2 / g) and a relatively small pore size (1.87 nm-2.29 nm), because polylactic acid nanofibers are used as a solid template to induce uniform and ordered growth of the conjugated microporous polymer on the fiber through molecular level interaction, thereby fully exposing the pore properties of the porous polymer; the specific surface area of Comparative Example 1 is only 57 m 2 / g, and the average pore size is 2.45 nm, because the polylactic acid nanofiber membrane is not used as a solid template, and the direct preparation of the conjugated microporous polymer leads to disordered growth and partial agglomeration.

[0053] The dust and toxic gas synchronous filtration ability of the high-porosity corrosion-resistant fiber membrane is closely related to the specific surface area, pore size and membrane formation. The dust (PM 0.3 and PM 2.5 ) filtration efficiency of Examples 1-4 with large specific surface area, small pore size and solid fiber membrane is all above 96.8%, and the adsorption amount of toxic gas (H2S) is all above 4.9 mmol / g, showing good dust and toxic gas synchronous filtration ability. Among them, Example 1 with the highest specific surface area and the smallest pore size performs best in performance test, and the PM 0.3 and PM 2.5 filtration efficiency reaches 99.7% and 99.9% respectively, and the H2S adsorption amount is 6.1 mmol / g, which is much higher than that of Comparative Examples 1-3 with low specific surface area and large pore size (H2S adsorption amount is less than 3.2 mmol / g). The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations. Furthermore, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the spirit of the present application, it should also be considered as disclosed by the present application.

Claims

1. A method of making a fibrous membrane of high-porosity corrosion- resistant armoring structure, characterized by, It comprises the following steps: Step S1, dissolving polylactic acid in an organic solvent to obtain a polylactic acid spinning solution; Step S2, processing the polylactic acid spinning solution obtained in step S1 by spinning technology to obtain a polylactic acid nanofiber membrane; Step S3, dissolving bromine monomer, alkyne monomer and catalyst in a reaction solvent to obtain a conjugated microporous polymer precursor solution; Step S4, taking the polylactic acid nanofiber membrane obtained in step S2 as a solid template, placing it in the conjugated microporous polymer precursor solution obtained in step S3, and obtaining a high-porosity corrosion-resistant fiber membrane with a fiber-armor structure through a coupling reaction in an inert gas atmosphere; The organic solvent in step S1 is one or more of dichloromethane, chloroform, acetone, ethyl acetate, N,N-dimethylformamide, methanol, ethanol, toluene, and triethylamine, and the concentration of polylactic acid in the polylactic acid spinning solution is 0.5-30 wt%; The spinning technology in step S2 is one or more of high-voltage electrospinning, high-speed airflow spinning, high-speed centrifugal spinning, and high-temperature melt spinning technology, and the thickness of the obtained polylactic acid nanofiber membrane is 50-150 μm, and the fiber diameter is 50-500 nm; The alkyne monomer in step S3 is one or more of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene, 1,3,6,8-tetraethynylpyrene, 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine, and tri(4-ethynylphenyl)amine, and the bromine monomer is one or more of 2,6-dibromophenol, tribromophenol, tetrabromophenol, pentabromophenol, 2,6-dibromo-4-methylphenol, bromophenyl cyanide, and 4-amino-2,6-dibromophenol, and the molar ratio of the functional groups of the bromine monomer to the alkyne monomer is 5:1-1:5; The catalyst in step S3 is a palladium-based catalyst and a copper-based catalyst, the palladium-based catalyst is one or more of palladium acetate, palladium chloride, tetrakis(triphenylphosphine)palladium, bis(dibenzylideneacetone)dipalladium, and palladium-carbon catalyst, the copper-based catalyst is one or more of cuprous iodide, cuprous bromide, copper chloride, copper acetate, copper sulfate, and nano-copper catalyst, and the molar ratio of the palladium-based catalyst to the copper-based catalyst is 1:5-1:20; The reaction solvent in step S3 is a mixed solution of one of toluene, dichloromethane, chloroform, tetrahydrofuran, 1,2-dichloroethane, acetonitrile, dioxane, pyridine, and N,N-dimethylformamide and triethylamine, and the volume ratio of the two substances in the mixed solution is 5:1-1:5; The inert gas in step S4 is one or more of nitrogen, helium, neon, argon, krypton, and xenon, and the purity of the inert gas is maintained at 99.9% or higher; The coupling reaction in step S4 is a Sonogashira coupling reaction, the reaction temperature is 40-80℃, and the reaction time is 2-72 hours.

2. A fiber membrane prepared by the method of claim 1.

3. The use of the fiber membrane of claim 2 in a filter material for simultaneously filtering out ultrafine dust and toxic gas.

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