Antibacterial-catalytic dual-function nanofiber air filtering membrane and preparation method thereof

Abstract

The invention belongs to the field of nanofiber membranes, and particularly relates to an antibacterial-catalytic dual-function nanofiber air filtering membrane and a preparation method thereof. Comprising the following steps: preparation of a spinning solution: preparing a shell layer solution: dissolving PVDF-b-PTFE in a DMF / acetone mixed solvent; the core layer liquid is prepared by the following steps: dispersing H-TiO2 in DMF (Dimethyl Formamide), and then adding PVDF-b-PTFE (Polyvinylidene Fluoride An antibacterial layer spinning solution is prepared by the following steps: dissolving TPU and a Zn-SnO2 / Ag composite material in DMF, and then adding a pore-foaming agent; the method comprises the following steps: firstly, starting a coaxial electrostatic spinning unit, and depositing a catalytic fiber layer on a non-woven fabric; then immediately starting the solution blowing spinning unit, and depositing an antibacterial fiber layer on the catalytic fiber layer; continuously collecting by a wind-up roller to obtain a composite filter membrane; according to the invention, multiple functions of high filtration efficiency, low air flow resistance, strong antibacterial and sterilization and efficient catalytic degradation of VOCs are realized, and large-scale continuous preparation of the functional material with the complex structure is realized.

Description

Technical Field

[0001] This invention belongs to the field of nanofiber membranes, specifically an antibacterial-catalytic dual-functional nanofiber air filter membrane and its preparation method. Background Technology

[0002] With industrialization and urbanization, air pollution has become increasingly severe, especially smog (PM2.5) and bioaerosols such as bacteria and viruses, which pose a serious threat to human health. Electrospun nanofiber membranes, due to their high specific surface area, moderate porosity, and controllable fiber diameter, are widely used in high-efficiency air filtration. However, traditional electrospun nanofiber membranes have the following limitations: 1. Single filtration mechanism: mainly relies on the physical sieving of fibers and inertial collision to intercept particulate matter. The interception efficiency of ultrafine particulate matter (especially PM0.3) needs to be improved, and the air resistance is relatively large.

[0003] 2. Risk of secondary pollution: The trapped bacteria, viruses and other microorganisms may survive and multiply on the warm and humid filter membrane, leading to microbial growth and becoming a source of secondary pollution, or even penetrating the filter membrane and causing downstream pollution.

[0004] 3. Limited functionality: It lacks the ability to degrade gaseous pollutants such as volatile organic compounds (VOCs).

[0005] 4. Production efficiency bottleneck: Traditional single-needle electrospinning technology has extremely low production efficiency, which is difficult to meet the needs of large-scale commercial applications. While multi-needle or needleless spinning can increase the yield, it is often difficult to accurately construct complex multi-level structures and functional gradient distributions.

[0006] In existing technologies, although some studies have attempted to introduce antibacterial agents, such as silver nanoparticles (Ag NPs), or photocatalysts, such as titanium dioxide (TiO2), into fibers, simple blend spinning is usually employed. This often results in functional particles being easily encapsulated and deactivated, or exhibiting uneven distribution. Furthermore, the lack of precise design of the fiber membrane's structure makes it difficult to achieve low resistance and multifunctional synergy while ensuring high filtration efficiency.

[0007] Therefore, developing a nanofiber air filter membrane that combines a multi-level physical interception structure, efficient antibacterial and catalytic degradation functions, and can be mass-produced through a continuous process, has significant practical application value. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies and solve at least one of the technical problems mentioned in the background art, this invention provides an antibacterial-catalytic dual-functional nanofiber air filter membrane with a multi-level interception structure and its continuous preparation method. This filter membrane, through a unique "micro-nano multi-level structure" design, "antibacterial-catalytic dual-functional partitioning" design, and "gradient distribution" design, simultaneously achieves multiple functions including high filtration efficiency, low airflow resistance, strong antibacterial and bactericidal properties, and efficient catalytic degradation of VOCs. Furthermore, by combining coaxial electrospinning and solution blowing technologies, the large-scale continuous preparation of this complex functional material is achieved.

[0009] The technical solution adopted by this invention to solve its technical problem is: a method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane, comprising the following steps: S1. Preparation of functional nanomaterials: Hollow mesoporous H-TiO2 nanospheres were synthesized using a template method; Zn-SnO2 support was synthesized by hydrothermal method, and then Ag NPs were loaded on its surface by photoreduction method to obtain Zn-SnO2 / Ag composite antibacterial agent; S2. Preparation of spinning solution: The catalyst layer spinning solution includes a shell layer solution and a core layer solution; Shell liquid: Dissolve PVDF-b-PTFE in a DMF / acetone mixed solvent and stir magnetically for 6 hours; Core layer solution: H-TiO2 is dispersed in DMF, sonicated for 2 hours, and then PVDF-b-PTFE is added and stirred until dissolved; Antibacterial layer spinning solution: TPU and Zn-SnO2 / Ag composite material are dissolved in DMF and stirred for 12 hours. Then, a pore-forming agent is added and stirring is continued for 2 hours. S3. Continuous preparation: A 30cm wide PP nonwoven fabric is used as the base material and wound around a take-up roller. The roller's linear speed is set to 0.5m / min. First, the coaxial electrospinning unit is started to deposit a 50μm thick catalytic fiber layer on the nonwoven fabric; The solution blow spinning unit was then immediately started to deposit a 30μm thick antibacterial fiber layer on the catalytic fiber layer; The final product is continuously collected by a take-up roller to obtain a composite filter membrane.

[0010] As a further technical solution of the present invention: in the shell liquid, the mass ratio of PVDF-b-PTFE to DMF / acetone mixed solvent is 1:9.

[0011] As a further technical solution of the present invention: the mass ratio of H-TiO2, DMF and PVDF-b-PTFE in the core layer liquid is 0.6:3:0.4.

[0012] As a further technical solution of the present invention: the mass ratio of TPU, Zn-SnO2 / Ag composite material, DMF and pore-forming agent in the antibacterial layer spinning solution is 1:0.1:10:0.05.

[0013] As a further technical solution of the present invention: the pore-forming agent is polyvinylpyrrolidone or polyethylene oxide.

[0014] As a further technical solution of the present invention: the parameters of the coaxial electrospinning unit are as follows: the flow rates of the shell liquid and the core liquid are set to 0.5-1.0 mL / h and 0.2-0.5 mL / h, respectively; the distance between the nozzle and the receiving roller is 15-20 cm; and the voltage of the high-voltage power supply is 15-30 kV.

[0015] As a further technical solution of the present invention: Solution blowing unit: The spinning solution supply speed is 3-10 mL / min, the airflow pressure is 0.2-0.5 MPa, and the distance between the nozzle and the substrate is 15-20 cm.

[0016] An antibacterial-catalytic dual-functional nanofiber air filter membrane, comprising: The structure consists of a support layer, a primary catalytic fiber layer, and a secondary interception / antibacterial fiber layer, stacked sequentially from bottom to top. The primary catalytic fiber layer is prepared by coaxial electrospinning and is enriched with photocatalytic nanomaterials. The secondary interception / antibacterial fiber layer is prepared by solution blow spinning and contains antibacterial nanomaterials and has a micro-nano secondary interception network with a beaded structure.

[0017] As a further technical solution of the present invention: the photocatalytic nanomaterial is a hollow mesoporous titanium dioxide nanosphere; the antibacterial nanomaterial is a composite formed by zinc-doped tin oxide loaded with silver nanoparticles.

[0018] As a further technical solution of the present invention: the average fiber diameter of the primary catalytic fiber layer is 300-800 nm, and the average fiber diameter of the secondary interception / antibacterial fiber layer is 80-200 nm.

[0019] The beneficial effects of this invention are as follows: The antibacterial-catalytic dual-functional nanofiber air filter membrane of the present invention comprises: Support layer: It is a non-woven fabric substrate with coarse fiber and high porosity, which provides mechanical support, facilitates gas diffusion, and reduces overall pressure resistance.

[0020] Primary catalytic fiber layer: Formed by coaxial electrospinning of composite nanofibers of hollow mesoporous titanium dioxide (H-TiO2) carrying photocatalytic properties. This layer has a relatively large fiber diameter (300-800 nm), and the photocatalyst is mainly enriched in the outer shell of the fiber, ensuring sufficient contact with oxygen, aiming to preferentially catalyze the degradation of small molecule VOCs; Secondary interception / antibacterial fiber layer: Formed by solution blow spinning of composite nanofibers loaded with antibacterial nanomaterials Ag NPs; this layer has finer fiber diameters (80-200 nm) and contains a large number of beaded structures, forming a fine micro-nano secondary interception network. Antibacterial agents are distributed on the fiber surface and in the beads, aiming to efficiently intercept PM2.5 / PM0.3 and kill captured bacteria and viruses.

[0021] The photocatalytic nanomaterial in the primary catalytic fiber layer is a hollow mesoporous titanium dioxide (H-TiO2) nanosphere. Its advantages are: the hollow structure has a lower density and is easy to disperse in the fiber; the mesoporous shell provides a huge specific surface area and abundant active sites, which enhances the adsorption and catalytic degradation efficiency of VOCs; the hollow cavity can be loaded with other noble metals (such as Pt, Pd) or non-metallic elements (such as N, C) for doping, which broadens its visible light response range. The antibacterial nanomaterials in the secondary interception / antibacterial fiber layer are zinc-doped tin oxide / silver nanocomposites (Zn-SnO2 / Ag). Zn-SnO2 itself possesses certain photocatalytic properties and chemical stability, and Zn doping optimizes its band structure. Ag nanoparticles are anchored on the Zn-SnO2 support, which controls the slow release of Ag+, achieving long-lasting antibacterial effects while avoiding the rapid aggregation and deactivation of Ag NPs, thus improving the utilization rate and durability of the antibacterial agent.

[0022] The aforementioned multi-level structure also includes biomimetic micro-nano topological structures on the fiber surface, such as forming nano-pits or wrinkles on the fiber surface through pore-forming agents, further increasing the specific surface area and providing more attachment and reaction sites for pollutants.

[0023] In summary, this invention achieves a triple protection mechanism of "physical interception (secondary fibers + beads) + antibacterial (Zn-SnO2 / Ag) + catalytic degradation (H-TiO2)," effectively removing particulate matter, microorganisms, and VOCs simultaneously. The coarser lower catalytic fibers form a large-pore support, ensuring unobstructed gas flow; the upper ultrafine fibers and nano-webs form a fine interception layer, achieving highly efficient capture of ultrafine particles. This structure optimizes the pore size distribution, ensuring a PM0.3 filtration efficiency of >99.5% while exhibiting significantly lower pressure resistance than a single-layer homogeneous filter membrane with equivalent efficiency. The antibacterial agent exists in a complex form and is enriched on the fiber surface, while Ag... +Slow release provides long-lasting antibacterial protection while avoiding the risk of Ag NPs shedding. The photocatalyst is enriched in the fiber shell, ensuring full exposure and high catalytic activity. The combination of coaxial electrospinning (suitable for fine structure control) and solution blowing technology (ultra-high yield) overcomes the bottleneck of low efficiency in traditional electrospinning, enabling continuous, integrated, and large-scale preparation of complex structural functional materials, with enormous potential for industrial application. Attached Figure Description

[0024] The invention will now be further described with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the multi-level structure of the antibacterial-catalytic dual-functional nanofiber air filter membrane described in this invention.

[0026] Figure 2 The image shown is an SEM image of the composite filter membrane prepared in Example 1. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0028] Example 1 Please see Figure 1 and Figure 2 As shown in the embodiment of the present invention, a method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane includes the following steps: S1. Preparation of functional nanomaterials: Synthesis of hollow mesoporous H-TiO2: Preparation of carbon sphere templates: A 0.1 mol / L glucose aqueous solution was transferred to a high-pressure reactor and hydrothermally reacted at 160 °C for 4 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting carbon spheres were collected by centrifugation, washed several times with deionized water and ethanol, and dried at 60 °C for later use.

[0029] H-TiO2 coating and formation: The carbon spheres prepared above were dispersed in anhydrous ethanol to form a carbon sphere dispersion with a concentration of 0.5 mg / mL.

[0030] Tetrabutyl titanate was slowly added dropwise to the above dispersion under vigorous stirring. The mass ratio of tetrabutyl titanate to carbon spheres was controlled between 5:1.

[0031] After the addition is complete, continue stirring for 2 hours to allow the titanium source to fully hydrolyze and condense on the surface of the carbon spheres.

[0032] The product was collected by centrifugation, washed with ethanol, and dried at 80°C.

[0033] Finally, the dried powder was heated to 450°C in air at a heating rate of 1°C / min and held at that temperature for 2 hours to completely remove the carbon sphere template, thus obtaining H-TiO2 nanospheres with a hollow mesoporous structure.

[0034] Synthesis of Zn-SnO2 / Ag Preparation of Zn-SnO2 precursor: Mix SnCl4·5H2O and ZnCl2 according to Zn 2+ / (Zn 2+ +Sn 4+ The molar percentage of ) is 1% dissolved in deionized water.

[0035] Urea was added to the above solution as a precipitant. The molar ratio of urea to total metal ions was controlled between 3:1.

[0036] The mixed solution was transferred to a high-pressure reactor and hydrothermally reacted at 160°C for 10 hours.

[0037] After the reaction was completed, the precipitate was collected by centrifugation, washed with water and ethanol, and dried to obtain the Zn-SnO2 precursor.

[0038] Preparation of Zn-SnO2 nanopowder: The above precursor was calcined in air at 400°C for 2 hours to obtain Zn-SnO2 nanopowder.

[0039] Preparation of Zn-SnO2 / Ag composite materials: Zn-SnO2 nanoparticles were dispersed in deionized water to form a dispersion with a concentration of 1 mg / mL.

[0040] Add AgNO3 solution to the dispersion. The loading of Ag (mass percentage) is 0.5% of the mass of Zn-SnO2.

[0041] Continue stirring for 30 minutes to allow Ag to mature. + Ions are fully adsorbed on the Zn-SnO2 surface.

[0042] Subsequently, the suspension was irradiated with ultraviolet light (e.g., a 300 W mercury lamp, dominant wavelength 365 nm) for 1 hour. Under illumination, Ag... + It was reduced to elemental Ag nanoparticles and loaded onto Zn-SnO2.

[0043] Finally, the product was collected by centrifugation, washed with water and ethanol, and dried to obtain the Zn-SnO2 / Ag composite material.

[0044] S2. Preparation of spinning solution: The catalyst layer spinning solution includes a shell layer solution and a core layer solution; Shell liquid: Dissolve 1g of PVDF-b-PTFE in 9g of DMF / acetone (7:3 w / w) mixed solvent and stir magnetically for 6h.

[0045] Core layer solution: Disperse 0.6g H-TiO2 in 3g DMF, sonicate for 2h, then add 0.4g PVDF-b-PTFE and stir until dissolved.

[0046] Antibacterial layer spinning solution: Dissolve 1g TPU and 0.1g Zn-SnO2 / Ag composite material in 10g DMF, stir for 12h, then add 0.05g polyethylene oxide (weight average molecular weight Mw=100,000), and continue stirring for 2h.

[0047] S3. Continuous preparation: 1. Use PP non-woven fabric with a width of 30cm as the base material, and wrap it around the take-up roller. The roller linear speed is set to 0.5m / min.

[0048] 2. First, start the coaxial electrospinning unit: set the flow rates of the shell liquid and core liquid to 0.5 mL / h and 0.2 mL / h respectively, the distance between the nozzle and the receiving roller to 15 cm, and the high-voltage power supply voltage to 15 kV. Deposit a catalytic fiber layer approximately 50 μm thick on the nonwoven fabric.

[0049] 3. Immediately afterwards, the solution blowing unit was started: the spinning solution supply rate was 3 mL / min, the airflow pressure was 0.2 MPa, and the distance between the nozzle and the substrate was 15 cm. A layer of antibacterial fiber with a thickness of about 30 μm was then deposited on the catalytic fiber layer.

[0050] 4. The final product is continuously collected by the take-up roller to obtain a composite filter membrane.

[0051] The antibacterial-catalytic dual-functional nanofiber air filter membrane described in this embodiment of the invention is prepared by the above-described method. It comprises a support layer, a primary catalytic fiber layer, and a secondary interception / antibacterial fiber layer stacked sequentially from bottom to top. The primary catalytic fiber layer is prepared by coaxial electrospinning, and its fibers are enriched with photocatalytic nanomaterials. The secondary interception / antibacterial fiber layer is prepared by solution blown spinning, and its fibers contain antibacterial nanomaterials and have a micro-nano secondary interception network with a beaded structure. The photocatalytic nanomaterial is a hollow mesoporous titanium dioxide nanosphere; the antibacterial nanomaterial is a composite formed by zinc-doped tin oxide loaded with silver nanoparticles; the average fiber diameter of the primary catalytic fiber layer is 300 nm, and the average fiber diameter of the secondary interception / antibacterial fiber layer is 80 nm.

[0052] Example 2 The method for preparing an antibacterial-catalytic bifunctional nanofiber air filter membrane according to an embodiment of the present invention includes the following steps: S1. Preparation of functional nanomaterials: Synthesis of hollow mesoporous H-TiO2: Preparation of carbon sphere templates: A 0.3 mol / L glucose aqueous solution was transferred to a high-pressure reactor and hydrothermally reacted at 170 °C for 6 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting carbon spheres were collected by centrifugation, washed several times with deionized water and ethanol, and dried at 70 °C for later use.

[0053] H-TiO2 coating and formation: The carbon spheres prepared above were dispersed in anhydrous ethanol to form a carbon sphere dispersion with a concentration of 1.5 mg / mL.

[0054] Tetrabutyl titanate was slowly added dropwise to the above dispersion under vigorous stirring. The mass ratio of tetrabutyl titanate to carbon spheres was controlled between 12:1.

[0055] After the addition is complete, continue stirring for 4 hours to allow the titanium source to fully hydrolyze and condense on the surface of the carbon spheres.

[0056] The product was collected by centrifugation, washed with ethanol, and dried at 80°C.

[0057] Finally, the dried powder was heated to 450°C in air at a heating rate of 3°C / min and held at that temperature for 2 hours to completely remove the carbon sphere template, thus obtaining H-TiO2 nanospheres with a hollow mesoporous structure.

[0058] Synthesis of Zn-SnO2 / Ag Preparation of Zn-SnO2 precursor: Mix SnCl4·5H2O and ZnCl2 according to Zn 2+ / (Zn 2+ +Sn 4+ The molar percentage of ) is 5% dissolved in deionized water.

[0059] Urea was added to the above solution as a precipitating agent. Urea reacts with total metal ions (Sn). 4+ + Zn 2+） The molar ratio is controlled between 5:1.

[0060] The mixed solution was transferred to a high-pressure reactor and hydrothermally reacted at 170°C for 12 hours.

[0061] After the reaction was completed, the precipitate was collected by centrifugation, washed with water and ethanol, and dried to obtain the Zn-SnO2 precursor.

[0062] Preparation of Zn-SnO2 nanopowder: The above precursor was calcined in air at 500°C for 3 hours to obtain Zn-SnO2 nanoparticles.

[0063] Preparation of Zn-SnO2 / Ag composite materials: Zn-SnO2 nanoparticles were dispersed in deionized water to form a dispersion with a concentration of 3 mg / mL.

[0064] Add AgNO3 solution to the dispersion. The Ag loading (mass percentage) is 3% of the Zn-SnO2 mass. Continue stirring for 50 minutes to allow the Ag to settle. + Ions are fully adsorbed on the Zn-SnO2 surface.

[0065] Subsequently, the suspension was irradiated with ultraviolet light (e.g., a 300 W mercury lamp, dominant wavelength 365 nm) for 2 hours. Under illumination, Ag... + It was reduced to elemental Ag nanoparticles and loaded onto Zn-SnO2.

[0066] Finally, the product was collected by centrifugation, washed with water and ethanol, and dried to obtain the Zn-SnO2 / Ag composite material.

[0067] S2. Preparation of spinning solution: The catalyst layer spinning solution includes a shell layer solution and a core layer solution; Shell liquid: Dissolve 1g of PVDF-b-PTFE in 9g of DMF / acetone (7:3 w / w) mixed solvent and stir magnetically for 6h.

[0068] Core layer solution: Disperse 0.6g H-TiO2 in 3g DMF, sonicate for 2h, then add 0.4g PVDF-b-PTFE and stir until dissolved.

[0069] Antibacterial layer spinning solution: Dissolve 1g TPU and 0.1g Zn-SnO2 / Ag composite material in 10g DMF, stir for 12h, then add 0.05g polyethylene oxide (weight average molecular weight Mw=100,000), and continue stirring for 2h.

[0070] S3. Continuous preparation: 1. Use PP non-woven fabric with a width of 30cm as the base material, and wrap it around the take-up roller. The roller linear speed is set to 0.5m / min.

[0071] 2. First, start the coaxial electrospinning unit: set the flow rates of the shell liquid and core liquid to 0.8 mL / h and 0.4 mL / h, respectively; the distance between the nozzle and the receiving roller to 18 cm; and the high-voltage power supply voltage to 25 kV. Deposit a catalytic fiber layer approximately 50 μm thick on the nonwoven fabric.

[0072] 3. Immediately afterwards, the solution blowing unit was started: the spinning solution supply rate was 5 mL / min, the airflow pressure was 0.3 MPa, and the distance between the nozzle and the substrate was 15 cm. A layer of antibacterial fiber with a thickness of about 30 μm was then deposited on the catalytic fiber layer.

[0073] 4. The final product is continuously collected by the take-up roller to obtain a composite filter membrane.

[0074] The antibacterial-catalytic dual-functional nanofiber air filter membrane described in this embodiment of the invention is prepared by the above-described method. It comprises a support layer, a primary catalytic fiber layer, and a secondary interception / antibacterial fiber layer stacked sequentially from bottom to top. The primary catalytic fiber layer is prepared by coaxial electrospinning, and its fibers are enriched with photocatalytic nanomaterials. The secondary interception / antibacterial fiber layer is prepared by solution blown spinning, and its fibers contain antibacterial nanomaterials and have a micro-nano secondary interception network with a beaded structure. The photocatalytic nanomaterial is a hollow mesoporous titanium dioxide nanosphere; the antibacterial nanomaterial is a composite formed by zinc-doped tin oxide loaded with silver nanoparticles; the average fiber diameter of the primary catalytic fiber layer is 550 nm, and the average fiber diameter of the secondary interception / antibacterial fiber layer is 190 nm.

[0075] Example 3 The method for preparing an antibacterial-catalytic bifunctional nanofiber air filter membrane according to an embodiment of the present invention includes the following steps: S1. Preparation of functional nanomaterials: Synthesis of hollow mesoporous H-TiO2: Preparation of carbon sphere templates: A 0.5 mol / L glucose aqueous solution was transferred to a high-pressure reactor and hydrothermally reacted at 190℃ for 8 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting carbon spheres were collected by centrifugation and washed several times with deionized water and ethanol, respectively, and then dried at 80℃ for later use.

[0076] H-TiO2 coating and formation: The carbon spheres prepared above were dispersed in anhydrous ethanol to form a carbon sphere dispersion with a concentration of 2.0 mg / mL.

[0077] Tetrabutyl titanate was slowly added dropwise to the above dispersion under vigorous stirring. The mass ratio of tetrabutyl titanate to carbon spheres was controlled between 20:1.

[0078] After the addition is complete, continue stirring for 6 hours to allow the titanium source to fully hydrolyze and condense on the surface of the carbon spheres.

[0079] The product was collected by centrifugation, washed with ethanol, and dried at 80°C.

[0080] Finally, the dried powder was heated to 450°C in air at a heating rate of 5°C / min and calcined for 2 hours to completely remove the carbon sphere template, thus obtaining H-TiO2 nanospheres with a hollow mesoporous structure.

[0081] Synthesis of Zn-SnO2 / Ag Preparation of Zn-SnO2 precursor: Mix SnCl4·5H2O and ZnCl2 according to Zn 2+ / (Zn 2+ +Sn 4+ The molar percentage of ) is 10% dissolved in deionized water.

[0082] Urea was added to the above solution as a precipitating agent. Urea reacts with total metal ions (Sn). 4+ + Zn 2+） The molar ratio is controlled between 6:1.

[0083] The mixed solution was transferred to a high-pressure reactor and hydrothermally reacted at 180°C for 14 hours.

[0084] After the reaction was completed, the precipitate was collected by centrifugation, washed with water and ethanol, and dried to obtain the Zn-SnO2 precursor.

[0085] Preparation of Zn-SnO2 nanopowder: The above precursor was calcined in air at 600°C for 4 hours to obtain Zn-SnO2 nanoparticles.

[0086] Preparation of Zn-SnO2 / Ag composite materials: Zn-SnO2 nanoparticles were dispersed in deionized water to form a dispersion with a concentration of 5 mg / mL.

[0087] Add AgNO3 solution to the dispersion. The Ag loading (mass percentage) is 5% of the mass of Zn-SnO2.

[0088] Continue stirring for 60 minutes to allow Ag to mature. + Ions are fully adsorbed on the Zn-SnO2 surface.

[0089] Subsequently, the suspension was irradiated with ultraviolet light (e.g., a 300 W mercury lamp, dominant wavelength 365 nm) for 1-3 hours. Under light irradiation, Ag... + It was reduced to elemental Ag nanoparticles and loaded onto Zn-SnO2.

[0090] Finally, the product was collected by centrifugation, washed with water and ethanol, and dried to obtain the Zn-SnO2 / Ag composite material.

[0091] S2. Preparation of spinning solution: The catalyst layer spinning solution includes a shell layer solution and a core layer solution; Shell liquid: Dissolve 1g of PVDF-b-PTFE in 9g of DMF / acetone (7:3 w / w) mixed solvent and stir magnetically for 6h.

[0092] Core layer solution: Disperse 0.6g H-TiO2 in 3g DMF, sonicate for 2h, then add 0.4g PVDF-b-PTFE and stir until dissolved.

[0093] Antibacterial layer spinning solution: Dissolve 1g TPU and 0.1g Zn-SnO2 / Ag composite material in 10g DMF, stir for 12h, then add 0.05g polyvinylpyrrolidone (weight average molecular weight Mw=100,000), and continue stirring for 2h.

[0094] S3. Continuous preparation: 1. Use PP non-woven fabric with a width of 30cm as the base material, and wrap it around the take-up roller. The roller linear speed is set to 0.5m / min.

[0095] 2. First, start the coaxial electrospinning unit: set the flow rates of the shell liquid and core liquid to 1.0 mL / h and 0.5 mL / h, respectively; the distance between the nozzle and the receiving roller to 20 cm; and the high-voltage power supply voltage to 30 kV. Deposit a catalytic fiber layer approximately 50 μm thick on the nonwoven fabric.

[0096] 3. Immediately afterwards, the solution blowing unit was started: the spinning solution supply rate was 10 mL / min, the airflow pressure was 0.5 MPa, and the distance between the nozzle and the substrate was 20 cm. A layer of antibacterial fiber about 30 μm thick was then deposited on the catalytic fiber layer.

[0097] 4. The final product is continuously collected by the take-up roller to obtain a composite filter membrane.

[0098] The antibacterial-catalytic dual-functional nanofiber air filter membrane described in this embodiment of the invention is prepared by the above-described method. It comprises a support layer, a primary catalytic fiber layer, and a secondary interception / antibacterial fiber layer stacked sequentially from bottom to top. The primary catalytic fiber layer is prepared by coaxial electrospinning, and its fibers are enriched with photocatalytic nanomaterials. The secondary interception / antibacterial fiber layer is prepared by solution blown spinning, and its fibers contain antibacterial nanomaterials and have a micro-nano secondary interception network with a beaded structure. The photocatalytic nanomaterial is a hollow mesoporous titanium dioxide nanosphere; the antibacterial nanomaterial is a composite formed by zinc-doped tin oxide loaded with silver nanoparticles; the average fiber diameter of the primary catalytic fiber layer is 800 nm, and the average fiber diameter of the secondary interception / antibacterial fiber layer is 200 nm.

[0099] Comparative Example 1 Comparative Example 1 uses conventional blend electrospinning to prepare a single-layer PVDF-b-PTFE nanofiber membrane, which is loaded with the same total content of TiO2 and Ag NPs to obtain an air filter membrane.

[0100] Performance testing The filter membranes of Examples 1-3 and Comparative Example 1 were subjected to performance tests. Filtration performance: TSI 8130 automatic filter media tester was used; antibacterial performance: GB / T 20944.3 standard was used; catalytic performance: formaldehyde with an initial concentration of 10 ppm was injected into a sealed chamber, and the degradation rate was measured within 4 hours under ultraviolet light irradiation. The test results are shown in Table 1 below. Table 1

[0101] As can be seen from Table 1 above, the antibacterial-catalytic bifunctional nanofiber air filter membrane prepared by the present invention has significant advantages in multi-level structure, functional partitioning and synergistic effect.

[0102] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an antibacterial-catalytic bifunctional nanofiber air filter membrane, characterized in that: Includes the following steps: S1. Preparation of functional nanomaterials: Hollow mesoporous H-TiO2 nanospheres were synthesized using a template method; Zn-SnO2 support was synthesized by hydrothermal method, and then Ag NPs were loaded on its surface by photoreduction method to obtain Zn-SnO2 / Ag composite antibacterial agent; S2. Preparation of spinning solution: The catalyst layer spinning solution includes a shell layer solution and a core layer solution; Shell liquid: Dissolve PVDF-b-PTFE in a DMF / acetone mixed solvent and stir magnetically for 6 hours; Core layer solution: H-TiO2 is dispersed in DMF, sonicated for 2 hours, and then PVDF-b-PTFE is added and stirred until dissolved; Antibacterial layer spinning solution: TPU and Zn-SnO2 / Ag composite material are dissolved in DMF and stirred for 12 hours. Then, a pore-forming agent is added and stirring is continued for 2 hours. S3. Continuous preparation: A 30cm wide PP nonwoven fabric is used as the base material and wound around a take-up roller. The roller's linear speed is set to 0.5 m / min. First, the coaxial electrospinning unit is started to deposit a 50μm thick catalytic fiber layer on the nonwoven fabric; The solution blow spinning unit was then immediately started to deposit a 30μm thick antibacterial fiber layer on the catalytic fiber layer; The final product is continuously collected by a take-up roller to obtain a composite filter membrane.

2. The method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 1, characterized in that: In the shell liquid: the mass ratio of PVDF-b-PTFE to DMF / acetone mixed solvent is 1:

9.

3. The method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 2, characterized in that: In the core layer solution, the mass ratio of H-TiO2, DMF and PVDF-b-PTFE is 0.6:3:0.

4.

4. The method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 3, characterized in that: In the antibacterial layer spinning solution, the mass ratio of TPU, Zn-SnO2 / Ag composite material, DMF, and pore-forming agent is 1:0.1:10:0.

05.

5. The method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 4, characterized in that: The pore-forming agent is polyvinylpyrrolidone or polyethylene oxide.

6. The method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 5, characterized in that: The parameters of the coaxial electrospinning unit are as follows: the flow rates of the shell liquid and the core liquid are set to 0.5-1.0 mL / h and 0.2-0.5 mL / h, respectively; the distance between the nozzle and the receiving roller is 15-20 cm; and the high voltage power supply voltage is 15-30 kV.

7. The method for preparing an antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 6, characterized in that: Solution blowing unit: The solution supply rate is 3-10 mL / min, the air pressure is 0.2-0.5 MPa, and the distance between the nozzle and the substrate is 15-20 cm.

8. An antibacterial-catalytic dual-functional nanofiber air filter membrane, characterized in that: The antibacterial-catalytic bifunctional nanofiber air filter membrane, prepared by the method according to any one of claims 1-7, comprises: The structure consists of a support layer, a primary catalytic fiber layer, and a secondary interception / antibacterial fiber layer, stacked sequentially from bottom to top. The primary catalytic fiber layer is prepared by coaxial electrospinning and is enriched with photocatalytic nanomaterials. The secondary interception / antibacterial fiber layer is prepared by solution blow spinning and contains antibacterial nanomaterials and has a micro-nano secondary interception network with a beaded structure.

9. The antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 8, characterized in that: The photocatalytic nanomaterial is a hollow mesoporous titanium dioxide nanosphere; the antibacterial nanomaterial is a composite formed by zinc-doped tin oxide loaded with silver nanoparticles.

10. The antibacterial-catalytic dual-functional nanofiber air filter membrane according to claim 8, characterized in that: The average fiber diameter of the primary catalytic fiber layer is 300-800 nm, and the average fiber diameter of the secondary interception / antibacterial fiber layer is 80-200 nm.

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