Method for reinforcing flexible inorganic hierarchical pore fiber membrane by using ore fibers

Abstract

The invention discloses a preparation method of an ore fiber reinforced flexible inorganic hierarchical pore fiber membrane. The method comprises the following steps: firstly, mixing ore fibers with polyvinylpyrrolidone, a titanium oxide precursor, a silicon oxide precursor and a solvent to prepare a spinning solution, forming a membrane through an electrostatic spinning process, and then carrying out subsequent calcination treatment to obtain the ore fiber reinforced flexible inorganic hierarchical pore fiber membrane. Compared with the inorganic hierarchical pore fiber membrane prepared by the existing process technology, the ore fiber reinforced inorganic hierarchical pore fiber membrane has higher tensile strength, the flexibility is greatly improved, and the stability of material application is ensured. The fiber membrane has high connectivity and high specific surface area, can generate an electrostatic effect, has high filtering efficiency and low filtering resistance to escape particles such as PM0.3, and also provides a key structure foundation and performance guarantee for loading of active components of a multifunctional membrane material.

Description

Technical Field

[0001] This invention belongs to the field of membrane material preparation technology, specifically relating to a method for preparing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane. Background Technology

[0002] In recent years, hierarchical porous fiber membranes have demonstrated significant advantages in applications such as filtration, adsorption, and catalysis due to their ultra-high specific surface area and interconnected porous structure. In the field of air purification, their hierarchical structure can achieve highly efficient interception of easily escaped particulate matter such as PM0.3 while maintaining low filtration resistance. However, traditional inorganic fibers often suffer from low mechanical strength and poor flexibility due to the influence of large grains and weak grain boundaries. Furthermore, while constructing a porous structure on fibers helps improve the permeability and functionality of the membrane, it also leads to uneven stress distribution within the material, making it prone to fracture or deformation under external loads.

[0003] Numerous studies have been reported on enhancing the mechanical properties of fiber membranes. Chinese invention patent CN114164666B, "A Polyimide-Reinforced and Toughened Silica Nanofiber Membrane and Its Preparation Method," utilizes polyimide to reinforce and toughen silica fiber membranes. Chinese invention patent CN112981704A, "A High-Strength Polylactic Acid-Based Electrospun Nanofiber Membrane and Its Preparation Method," uses modified cellulose nanocrystals as reinforcing nanofillers to strengthen polylactic acid nanofiber membranes. Chinese invention patent CN113651633B, "A Mullite Fiber-Reinforced Silicon Carbide Ceramic Filter Tube and Its Preparation Method," uses mullite fibers to prepare a transition layer, simultaneously enhancing the mechanical strength and filtration performance of the silicon carbide ceramic filter tube. However, the above methods have not yet achieved significant breakthroughs in enhancing the structure of inorganic hierarchical porous fiber membranes. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention utilizes mineral fibers—which are abundant, inexpensive, possess excellent mechanical properties, and exhibit electret characteristics—as reinforcing materials, providing a novel method for preparing reinforced flexible inorganic hierarchical porous fiber membranes. By adding mineral fiber materials, the tensile strength of the hierarchical porous fiber membrane is effectively improved. Simultaneously, the electrostatic effect induced by the electret enhances its filtration performance for particulate matter in indoor air. This reinforcement method can improve the durability and practicality of hierarchical porous fiber membranes in real-world applications, promoting the development of membrane-based air purification technology and possessing significant scientific and practical value.

[0005] The purpose of this invention is to provide a method for producing a mineral fiber-reinforced flexible inorganic hierarchical porous fiber membrane. The flexible inorganic hierarchical porous fiber membrane obtained by this method exhibits improved flexibility and mechanical properties, can be freely bent, possesses a rich porous structure and a high specific surface area, and can also generate electrostatic effects, enabling efficient purification of fine particulate matter in the air.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for preparing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane involves ultrasonically dispersing mineral fibers in a solvent, sequentially adding polyvinylpyrrolidone, titanium dioxide precursor, and silicon dioxide precursor, stirring to obtain a spinning solution, performing electrospinning, and then placing the obtained fiber membrane in a 60 ℃ forced-air drying oven for 12 h to remove excess solvent, obtaining a precursor fiber membrane, and then calcining the precursor fiber membrane in air to obtain the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane.

[0007] Preferably, the mineral fibers are one or more of 7 Å halloysite nanotubes, 10 Å halloysite nanotubes, sepiolite, or wollastonite.

[0008] Preferably, the silicon oxide precursor is one or more of tetramethyl silicate and tetraethyl orthosilicate, and the titanium oxide precursor is tetrabutyl titanate.

[0009] Preferably, the solvent is ethanol and acetic acid; in the spinning solution, the contents of mineral fiber, polyvinylpyrrolidone, titanium dioxide precursor, silicon dioxide precursor, ethanol and acetic acid are 0.125-0.5 wt.%, 10 wt.%, 5-25 wt.%, 5-25 wt.%, 50 wt.%, and 10 wt.%, respectively.

[0010] Preferably, the ultrasonic dispersion time is 10-30 min and the stirring time is 10-24 h.

[0011] Preferably, the conditions for electrospinning are as follows: spinning voltage 10~30 kV, nozzle inner diameter 0.5~1.55 mm, spinning solution flow rate 1~10 mL / h, distance between nozzle and receiving roller 10~20 cm, receiving roller rotation speed 30~120 r / min, ambient temperature 15~40 ℃, and ambient humidity 10~70% RH.

[0012] Preferably, the calcination conditions are as follows: the calcination atmosphere is air, the heating rate is 1~10 ℃ / min, the calcination temperature is 500~800 ℃, and the holding time is 1-3 h.

[0013] Preferably, the multi-level porous fiber membrane has two types of pore structures: (1) micropores and mesopores on the fibers; and (2) macropores formed by the stacking of fibers.

[0014] The beneficial effects of this invention are: 1. The mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared by this invention has excellent properties such as high tensile strength and good flexibility, which improves the stability of material application. The hierarchical porous fiber membrane has two types of pore structures: (1) micropores and mesopores on the fibers; (2) macropores formed by the interfibers.

[0015] 2. The mineral fiber reinforced flexible inorganic multi-level porous fiber membrane prepared by this invention has high connectivity and high specific surface area, and can generate electrostatic effect. It has high filtration efficiency and low filtration resistance for easily escaped particulate matter such as PM0.3, and also provides a key structural basis and performance guarantee for the loading of active components of multifunctional membrane materials.

[0016] 3. The enhancement method described in this invention is simple in process, easy to operate, and has broad application prospects. Attached Figure Description

[0017] Figure 1 This is a bending test diagram of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1 of the present invention.

[0018] Figure 2 This is a scanning electron microscope image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1 of the present invention.

[0019] Figure 3 This is a scanning electron microscope image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 2 of the present invention.

[0020] Figure 4 This is a scanning electron microscope image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 3 of the present invention.

[0021] Figure 5 This is a scanning electron microscope image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 4 of the present invention.

[0022] Figure 6 This is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1 of the present invention.

[0023] Figure 7 This is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 2 of the present invention.

[0024] Figure 8This is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 3 of the present invention.

[0025] Figure 9 This is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 4 of the present invention.

[0026] Figure 10 The attached figures show the nitrogen adsorption and desorption of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membranes prepared in Examples 1-4 of this invention.

[0027] Figure 11 Transmission electron microscopy (TEM) image of a single fiber of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1 of this invention. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification. Example 1

[0029] (1) Preparation of spinning solution: First, add 0.05 g halloysite nanotubes with an interlayer spacing of 7 Å to a mixed solvent of 10 g ethanol and 2 g acetic acid, and disperse by ultrasonication for 10 min; then add 2 g polyvinylpyrrolidone, and after complete dissolution, add 1.3 g tetrabutyl titanate and 4.7 g tetraethyl orthosilicate in sequence, and stir magnetically for 12 h to form a precursor solution; (2) Electrospinning preparation of precursor fiber membrane: The spinning solution was placed in an electrospinning device for spinning. The electrospinning conditions were set as follows: a 16G stainless steel dispensing needle with an inner diameter of 1.15 mm was used, the dispensing speed was 5 mL / h, the voltage was 24 kV, the distance between the collecting roller and the nozzle was 15 cm, and the receiving roller speed was 60 r / min. The spinning temperature was 25 ℃ and the ambient humidity was 40% RH. The obtained fiber membrane was placed in a 60 ℃ forced-air drying oven and dried for 12 h to remove excess solvent, thus obtaining an inorganic-organic composite precursor fiber membrane; (3) Calcination: The dried inorganic-organic composite fiber membrane was placed in a muffle furnace and calcined at 550 °C for 2 h at a heating rate of 5 °C / min.

[0030] Testing showed that the prepared mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane remained intact after a 180° torsion test, with a tensile breaking stress of 0.37 MPa and a specific surface area of ​​183 m². 2 / g, fiber diameter is 200~1500 nm; the micropore diameter inside the fiber membrane is 1.7 nm, the mesopore diameter is 2~8 nm, the macropore diameter between the fibers is 1.2~3.5 μm; the electrostatic value of the fiber membrane surface is 324 V.

[0031] Testing showed that the prepared mineral fiber reinforced flexible inorganic multi-level porous fiber membrane achieved a PM0.3 filtration efficiency of 99.83%, a pressure drop of 57.5 Pa, and a quality factor of 0.111 Pa. -1 It can meet the requirements for efficient filtration of easily escaped particulate matter such as PM0.3 in indoor air.

[0032] Figure 2 The image shows a scanning electron microscope (SEM) image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1, revealing that the fiber has an internal porous structure. Figure 6 The image shown is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1, showing that the fibers are randomly assembled to form a macroporous structure. Figure 10 The attached figure shows the nitrogen adsorption and desorption of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1. It shows a type IV isotherm with an H4 type hysteresis loop, indicating that the fiber membrane has both microporous and mesoporous structures. Figure 11 The image shows a transmission electron microscope (TEM) image of a single fiber of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 1, which shows that halloysite nanotubes are distributed in the denser outer shell of the fiber and are relatively uniformly distributed. Example 2

[0033] (1) Preparation of spinning solution: First, add 0.10 g halloysite nanotubes with an interlayer spacing of 7 Å to a mixed solvent of 10 g ethanol and 2 g acetic acid, and disperse by ultrasonication for 30 min; then add 2 g polyvinylpyrrolidone, and after complete dissolution, add 1.3 g tetrabutyl titanate and 4.7 g tetraethyl orthosilicate in sequence, and stir magnetically for 10 h to form a precursor solution; (2) Electrospinning preparation of precursor fiber membrane: The spinning solution was placed in an electrospinning device for spinning. The electrospinning conditions were set as follows: a 16G stainless steel dispensing needle with an inner diameter of 1.15 mm was used, the dispensing speed was 5 mL / h, the voltage was 24 kV, the distance between the collecting roller and the nozzle was 15 cm, and the receiving roller speed was 60 r / min. The spinning temperature was 25 ℃ and the ambient humidity was 40% RH. The obtained fiber membrane was placed in a 60 ℃ forced-air drying oven and dried for 12 h to remove excess solvent, thus obtaining an inorganic-organic composite precursor fiber membrane; (3) Calcination: The dried inorganic-organic composite fiber membrane was placed in a muffle furnace and calcined at 550 °C for 2 h at a heating rate of 5 °C / min.

[0034] Testing revealed that the prepared mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane had a tensile breaking stress of 0.20 MPa and a specific surface area of ​​189 m². 2 / g, fiber diameter is 200~1600 nm; the micropore diameter inside the fiber membrane is 1.7 nm, the mesopore diameter is 2~8 nm, the macropore diameter between the fibers is 1.3~5.2 μm; the electrostatic value of the fiber membrane surface is 487 V.

[0035] Testing showed that the prepared mineral fiber reinforced flexible inorganic multi-level porous fiber membrane achieved a PM0.3 filtration efficiency of 99.92%, a pressure drop of 56.0 Pa, and a quality factor of 0.128 Pa. -1 It can meet the requirements for efficient filtration of easily escaped particulate matter such as PM0.3 in indoor air.

[0036] Figure 3 The image shown is a scanning electron microscope (SEM) image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 2, which shows that the fiber has an internal porous structure. Figure 7 The image shown is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 2, which shows that the fibers are randomly assembled to form a macroporous structure. Figure 10 The attached figure shows the nitrogen adsorption and desorption of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 2. It shows a type IV isotherm with an H4 type hysteresis loop, indicating that the fiber membrane has both microporous and mesoporous structures. Example 3

[0037] (1) Preparation of spinning solution: First, add 0.025 g halloysite nanotubes with an interlayer spacing of 10 Å to a mixed solvent of 10 g ethanol and 2 g acetic acid, and disperse by ultrasonication for 30 min; then add 2 g polyvinylpyrrolidone, and after complete dissolution, add 1.3 g tetrabutyl titanate and 4.7 g tetraethyl orthosilicate in sequence, and stir magnetically for 24 h to form a precursor solution; (2) Electrospinning preparation of precursor fiber membrane: The spinning solution was placed in an electrospinning device for spinning. The electrospinning conditions were set as follows: a 16G stainless steel dispensing needle with an inner diameter of 1.15 mm was used, the dispensing speed was 5 mL / h, the voltage was 24 kV, the distance between the collecting roller and the nozzle was 15 cm, and the receiving roller speed was 60 r / min. The spinning temperature was 25 ℃ and the ambient humidity was 40% RH. The obtained fiber membrane was placed in a 60 ℃ forced-air drying oven and dried for 12 h to remove excess solvent, thus obtaining an inorganic-organic composite precursor fiber membrane; (3) Calcination: The dried inorganic-organic composite fiber membrane was placed in a muffle furnace and calcined at 550 °C for 2 h at a heating rate of 5 °C / min.

[0038] Testing revealed that the prepared mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane had a tensile breaking stress of 0.27 MPa and a specific surface area of ​​219 m². 2 / g, fiber diameter is 300~1100 nm; the micropore diameter inside the fiber membrane is 1.7 nm, the mesopore diameter is 2~8 nm, the macropore diameter between the fibers is 0.8~4.1 μm; the electrostatic value of the fiber membrane surface is 298 V.

[0039] Figure 4 The image shows a scanning electron microscope (SEM) image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 3, revealing that the fiber has an internal porous structure. Figure 8 The image shown is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 3, showing that the fibers are randomly assembled to form a macroporous structure. Figure 10 The attached figure shows the nitrogen adsorption and desorption of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 3. It shows a type IV isotherm with an H4 type hysteresis loop, indicating that the fiber membrane has both microporous and mesoporous structures. Example 4

[0040] (1) Preparation of spinning solution: First, add 0.10 g halloysite nanotubes with an interlayer spacing of 10 Å to a mixed solvent of 10 g ethanol and 2 g acetic acid, and disperse by ultrasonication for 10 min; then add 2 g polyvinylpyrrolidone, and after complete dissolution, add 1.3 g tetrabutyl titanate and 4.7 g tetraethyl orthosilicate in sequence, and stir magnetically for 24 h to form a precursor solution; (2) Electrospinning preparation of precursor fiber membrane: The spinning solution was placed in an electrospinning device for spinning. The electrospinning conditions were set as follows: a 16G stainless steel dispensing needle with an inner diameter of 1.15 mm was used, the dispensing speed was 5 mL / h, the voltage was 24 kV, the distance between the collecting roller and the nozzle was 15 cm, and the receiving roller speed was 60 r / min. The spinning temperature was 25 ℃ and the ambient humidity was 40% RH. The obtained fiber membrane was placed in a 60 ℃ forced-air drying oven and dried for 12 h to remove excess solvent, thus obtaining an inorganic-organic composite precursor fiber membrane; (3) Calcination: The dried inorganic-organic composite fiber membrane was placed in a muffle furnace and calcined at 550 °C for 2 h at a heating rate of 5 °C / min.

[0041] Testing revealed that the prepared mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane had a tensile breaking stress of 0.20 MPa and a specific surface area of ​​229 m². 2 / g, fiber diameter is 200~2000 nm; the micropore diameter inside the fiber membrane is 1.7 nm, the mesopore diameter is 2~8 nm, the macropore diameter between the fibers is 1.3~7.9 μm; the electrostatic value of the fiber membrane surface is 464 V.

[0042] Figure 5 The image shown is a scanning electron microscope (SEM) image of the cross-section of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 4, which shows that the fiber has an internal porous structure. Figure 9 The image shown is a scanning electron microscope image of the surface of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 4, showing that the fibers are randomly assembled to form a macroporous structure. Figure 10 The attached figure shows the nitrogen adsorption and desorption of the mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane prepared in Example 4. It shows a type IV isotherm with an H4 type hysteresis loop, indicating that the fiber membrane has both microporous and mesoporous structures. Example 5

[0043] (1) Preparation of spinning solution: First, add 0.05 g sepiolite fiber to a mixed solvent of 10 g ethanol and 2 g acetic acid and disperse it by ultrasonication for 30 min; then add 2 g polyvinylpyrrolidone and dissolve it completely. Then add 1.0 g tetrabutyl titanate and 5.0 g tetramethyl silicate in sequence and stir magnetically for 12 h to form a precursor solution. (2) Electrospinning preparation of precursor fiber membrane: The spinning solution was placed in an electrospinning device for spinning. The electrospinning conditions were set as follows: a 21G stainless steel dispensing needle with an inner diameter of 0.50 mm was used, the dispensing speed was 1.0 mL / h, the voltage was 10 kV, the distance between the collecting roller and the nozzle was 10 cm, and the receiving roller speed was 120 r / min. The spinning temperature was 15 ℃ and the ambient humidity was 10% RH. The obtained fiber membrane was placed in a 60 ℃ forced-air drying oven and dried for 12 h to remove excess solvent, thus obtaining an inorganic-organic composite precursor fiber membrane. (3) Calcination: The dried inorganic-organic composite fiber membrane was placed in a muffle furnace and calcined at 500 °C for 3 h at a heating rate of 1 °C / min. Example 6

[0044] (1) Preparation of spinning solution: First, add 0.05g of wollastonite powder to a mixed solvent of 10g of ethanol and 2g of acetic acid, and disperse it by ultrasonication for 30 min; then add 2g of polyvinylpyrrolidone, and after it is completely dissolved, add 5.0g of tetrabutyl titanate and 1.0g of tetraethyl orthosilicate in sequence, and stir magnetically for 24 h to form a precursor solution; (2) Electrospinning preparation of precursor fiber membrane: The spinning solution was placed in an electrospinning device for spinning. The electrospinning conditions were set as follows: a 14G stainless steel dispensing needle with an inner diameter of 1.55 mm was used, the dispensing speed was 10.0 mL / h, the voltage was 30 kV, the distance between the collecting roller and the nozzle was 20 cm, and the receiving roller speed was 30 r / min. The spinning temperature was 40 ℃ and the ambient humidity was 70% RH. The obtained fiber membrane was placed in a 60 ℃ forced-air drying oven and dried for 12 h to remove excess solvent, thus obtaining an inorganic-organic composite precursor fiber membrane; (3) Calcination: The dried inorganic-organic composite fiber membrane was placed in a muffle furnace and calcined at 800 °C for 1 h with a heating rate of 10 °C / min.

[0045] Comparative Example 1 The difference between this embodiment and Embodiment 1 is that halloysite nanotubes are not added to the spinning solution, while the remaining steps are the same as in Embodiment 1.

[0046] The tensile breaking stress of the prepared flexible inorganic hierarchical porous fiber membrane was tested to be 0.15 MPa. Compared with Example 1, the tensile breaking stress of the flexible inorganic hierarchical porous fiber membrane prepared in Comparative Example 1 was significantly reduced, mainly because the mineral fibers have a better reinforcing effect on the flexible inorganic hierarchical porous fiber membrane.

[0047] Testing revealed that the prepared flexible inorganic hierarchical porous fiber membrane had a surface electrostatic value of 0 V; a PM0.3 filtration efficiency of 99.83%; a pressure drop of 66.0 Pa; and a quality factor of 0.097 Pa. -1 Compared with Examples 1 and 2, the filtration efficiency of the flexible inorganic multi-level porous fiber membrane prepared in Comparative Example 1 for PM0.3 decreased significantly. This is mainly because the mineral fibers, as electrets, can generate electrostatic effects during the filtration process, thereby improving the capture efficiency of particulate matter. At the same time, the mineral fibers have a good reinforcing effect on the fibers, making the fibers less prone to breakage during the filtration process and ensuring the stability of the material application.

Claims

1. A method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane, characterized in that: Mineral fibers were ultrasonically dispersed in a solvent, and polyvinylpyrrolidone, titanium dioxide precursor, and silicon dioxide precursor were added sequentially. The mixture was stirred to prepare a spinning solution, which was then electrospun. The resulting fiber membrane was then dried in a 60 °C forced-air drying oven for 12 h to remove excess solvent, thus obtaining a precursor fiber membrane. The precursor fiber membrane was then calcined in air to obtain a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane.

2. The method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane according to claim 1, characterized in that, The mineral fibers are one or more of 7 Å halloysite nanotubes, 10 Å halloysite nanotubes, sepiolite, or wollastonite.

3. The method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane according to claim 1, characterized in that, The silicon oxide precursor includes one or more of tetramethyl silicate and tetraethyl orthosilicate; the titanium oxide precursor is tetrabutyl titanate.

4. The method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane according to claim 1, characterized in that, The solvents are ethanol and acetic acid; in the spinning solution, the contents of mineral fiber, polyvinylpyrrolidone, titanium dioxide precursor, silicon dioxide precursor, ethanol and acetic acid are 0.125-0.5 wt.%, 10 wt.%, 5-25 wt.%, 50 wt.%, and 10 wt.%, respectively.

5. The method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane according to claim 1, characterized in that, The ultrasonic dispersion time is 10-30 min, and the stirring time is 10-24 h.

6. The method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane according to claim 1, characterized in that, The conditions for electrospinning are as follows: spinning voltage 10~30 kV, nozzle inner diameter 0.5~1.55 mm, spinning solution flow rate 1~10 mL / h, distance between nozzle and receiving roller 10~20 cm, receiving roller speed 30~120 r / min, ambient temperature 15~40℃, and ambient humidity 10~70% RH.

7. The method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane according to claim 1, characterized in that, The calcination conditions are as follows: the calcination atmosphere is air, the heating rate is 1~10 ℃ / min, the calcination temperature is 500~800 ℃, and the holding time is 1-3 h.

8. The method for producing a mineral fiber reinforced flexible inorganic hierarchical porous fiber membrane according to claim 1, characterized in that: The multi-level porous fiber membrane has two types of pore structures: (1) micropores and mesopores on the fibers; and (2) macropores formed by the inter-fiber structure.

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