A method for preparing a biomass-based air purification membrane

Abstract

The application discloses a preparation method of a biomass-based air purification membrane and belongs to the technical field of air purification membrane preparation. The method comprises the following steps: step one, a spinnable polymer material is placed in a solvent and heated and stirred until the polymer material is dissolved, and then a solution of biomass material is added after cooling, and the solution is uniformly mixed to obtain a spinning precursor solution; step two, a drum is used as a receiving device, and electrostatic air-jet spinning is performed on the spinning precursor solution to obtain an electrostatic air-jet spun fiber membrane; and step three, an array template method is used to patternize and press the electrostatic air-jet spun fiber membrane by using a flat vulcanizing machine, so that the electrostatic air-jet spun fiber membrane has a periodic micro-pattern structure, and the air purification membrane is obtained. The application prepares an air purification membrane with a blocking effect on ultraviolet rays, and the air purification membrane has high filtration efficiency and small pressure drop, and has a good application prospect in the field of air purification.

Description

Technical Field

[0001] This invention belongs to the field of air purification technology and relates to a method for preparing a bio-based nanofiber membrane that is easy to process, has high-efficiency filtration, and has a blocking effect on ultraviolet rays. Background Technology

[0002] In today's world, air pollution has become a major global environmental problem. The air around us is filled with various tiny particulate matter, as well as pollutants such as bacteria and mold. When people breathe, these harmful substances enter the respiratory system, causing extremely serious harm to human health, such as causing respiratory diseases and reducing lung function.

[0003] During daily use, after a period of operation, pollutants such as dust, pollen, and fine particulate matter gradually accumulate inside and on the surface of air conditioners and household filters. This leads to a significant decrease in filtration efficiency and obstructs airflow within the filter, affecting its normal operation. More seriously, these accumulated pollutants contain bacteria and dust, which can easily penetrate the human body with the airflow, posing a potential threat to human health. To avoid these problems, frequent replacement of the filter membrane is necessary. However, traditional filter membranes mostly use petroleum-based materials and are manufactured using a melt-blown process. This manufacturing method has many drawbacks. On the one hand, its processing stability is poor, and quality instability may occur during production, affecting the overall performance of the filter membrane. On the other hand, the use of petroleum-based materials is not conducive to sustainable development, and petroleum-based materials are non-degradable, easily causing environmental pollution.

[0004] Biomass, with its advantages of being purely natural and renewable, can effectively solve the aforementioned problems of petroleum-based materials. However, the processing difficulty of biomass nanofiber membranes is far greater than that of petroleum-based materials. Therefore, developing an electrospun nanofiber membrane that is easy to process, highly efficient in filtration, and has antibacterial properties remains a significant challenge. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method for preparing a biomass-based air purification membrane. The specific steps of the technical solution adopted in this invention are as follows:

[0006] Step 1: Place the spinnable polymer material in a solvent, heat and stir until dissolved, and cool to obtain a spinnable polymer solution with a concentration of 10~20wt%; add a biomass material solution with a concentration of 1~10wt% to the spinnable polymer solution and stir evenly to obtain a spinning precursor solution; the mass ratio of the spinnable polymer solution to the biomass material solution is (10~40):1;

[0007] The spinnable polymer material is selected from one or more of polyvinyl alcohol, polyvinylidene fluoride, polylactic acid, polycaprolactone, polyethylene glycol, polyacrylamide, polyacrylic acid, and polyvinylpyrrolidone; wherein, polyvinyl alcohol is preferred.

[0008] The biomass material is selected from one or more of bamboo cellulose powder, loofah powder, cotton fiber powder, and hemp fiber powder, wherein the average particle size is between 100 mesh and 800 mesh.

[0009] Step 2: Using a roller covered with aluminum foil as a receiving device, electrostatic air-jet spinning is performed on the above-mentioned spinning precursor liquid to obtain an electrostatic air-jet spun fiber membrane, namely the biomass-based air purification membrane.

[0010] Furthermore, the method also includes step three: using an array template method to pattern and press the electrostatic air-jet spun fiber membrane with a flat vulcanizing machine to obtain an air purification membrane with a blocking effect on ultraviolet rays.

[0011] In a preferred embodiment of the present invention, the heating and stirring temperature of the polyvinyl alcohol particles in step one is 60°C.

[0012] In a preferred embodiment of the present invention, bamboo cellulose is added to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, and stirred at high speed at room temperature until the bamboo cellulose is completely dissolved to obtain a 5wt% pale yellow bamboo cellulose solution.

[0013] In a preferred embodiment of the present invention, the voltage of the electrostatic air-jet spinning in step two is 12~20kV, the air pressure is 30~80KPa, the spinning distance is 20~30cm, the rotation speed of the roller is 100~150rpm, and the propulsion speed of the propulsion pump is 0.5~3mL / h.

[0014] In a preferred embodiment of the present invention, the relative humidity of the environment in step two is 30-40%, and the indoor temperature is controlled within the range of 23±0.2℃.

[0015] In a preferred embodiment of the present invention, the size of the array template in step three is 60-100 mesh, and the pressing time is 5-60 seconds.

[0016] In a preferred embodiment of the present invention, the array template in step three is one or more of the following: triangle, rectangle, hexagon, circle, and ellipse.

[0017] In a preferred embodiment of the present invention, the temperature of the flat vulcanizing machine during step three, patterning pressing, is 23±0.2℃, the pressure is 4MPa, and the time is 5s.

[0018] In a preferred embodiment of the present invention, step three involves using a BET plate to cover a fiber membrane for uniform imprinting.

[0019] The beneficial effects of this invention are:

[0020] 1. The air purification membrane prepared by the method of this invention is an environmentally friendly bio-based air-jet electrospun fiber membrane with high filtration efficiency, good UV protection, and processing stability.

[0021] 2. The preparation method provided by this invention utilizes electrostatic air-jet spinning technology to prepare an electrostatic air-jet spun fiber membrane. This membrane, upon completion of spinning, cannot effectively block ultraviolet light and exhibits low filtration efficiency because the nanofibers are relatively large, and the overlap between these large fibers leads to a high porosity. Then, natural biomass materials are added to the spinning solution to ensure uniform mixing. By controlling the content of the biomass materials, the fiber membrane acquires ultraviolet blocking properties. Finally, the fiber membrane is patterned and pressed using an array template method. The resulting fiber membrane effectively blocks ultraviolet light and exhibits high filtration efficiency and low pressure drop. This bio-based electrostatic air-jet spun nanofiber membrane can provide new ideas for the research and development of air purification membrane materials. Attached Figure Description

[0022] Figure 1 This is a schematic flowchart illustrating a method for preparing a bamboo fiber-based air purification membrane according to an embodiment of the present invention.

[0023] Figure 2 The images shown are scanning electron microscope (SEM) images of the PVA and PVA@FB-x fiber membranes of this invention.

[0024] Figure 3 The images show the ultraviolet absorption spectra of the PVA and PVA@FB-x fiber membranes of this invention.

[0025] Figure 4 The present invention relates to the PVA and PVA@FB-x fiber membranes for PM2.5. 1.0 PM 2.5 and PM 10 The filtration efficiency graph.

[0026] Figure 5 The effect of PVA@FB-2 patterned fiber membrane on PM before and after pressing in this invention. 1.0 PM 2.5 and PM 10 The filtration efficiency graph. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Comparative Example 1

[0029] This comparative example provides a method for preparing an air purification membrane without added bamboo fiber, which includes the following steps:

[0030] S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles and dissolve them in deionized water at 60°C. Stir until completely dissolved and cool to room temperature to prepare a 16wt% PVA spinning precursor solution.

[0031] S2, electrostatic air-jet spinning equipment such as Figure 1 As shown, the positive terminal of the high-voltage power supply is connected to the spinning head, and the negative terminal is connected to the aluminum foil covering the roller. The roller speed is set to 125 rpm, the voltage of the electrostatic air-jet spinning is set to 20 kV, the air pressure is set to 60 kPa, and the spinning distance is 25 cm. The above-mentioned PVA spinning precursor solution is injected into a 5 mL plastic syringe, and the feed pump speed is 2 mL / h. The relative humidity and room temperature are controlled at 30-40% and 23±0.2℃, respectively. The power is turned on, and the spinning time is set to 30 min to obtain a PVA fiber membrane (denoted as PVA).

[0032] The PVA fiber obtained in this comparative example has a diameter of 356.43 nm and a filtration efficiency of 62%.

[0033] Example 1

[0034] This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which includes the following steps:

[0035] S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles and dissolve them in deionized water at 60°C. Stir until completely dissolved and cool to room temperature to prepare a 16wt% polyvinyl alcohol solution.

[0036] Bamboo cellulose was added to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, and stirred at high speed at room temperature until the bamboo cellulose was completely dissolved to obtain a 5 wt% pale yellow bamboo cellulose solution.

[0037] Then, 5 wt% bamboo cellulose solution was added to the PVA solution and mixed evenly. The mass ratio of polyvinyl alcohol solution to bamboo cellulose solution was 10:1 to obtain bamboo fiber-based spinning precursor solution.

[0038] S2, electrostatic air-jet spinning equipment such as Figure 1As shown, the positive terminal of the high-voltage power supply is connected to the spinning head, and the negative terminal is connected to the aluminum foil covering the roller. The roller speed is set to 125 rpm, the voltage of the electrostatic air-jet spinning is set to 20 kV, the air pressure is set to 60 kPa, and the spinning distance is 25 cm. The above-mentioned bamboo fiber-based spinning precursor solution is injected into a 5 mL plastic syringe, and the feed pump speed is 2 mL / h. The relative humidity and room temperature are controlled at 30-40% and 23±0.2℃, respectively. The power is turned on, and the spinning time is set to 30 min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-4).

[0039] The fiber diameter obtained in this embodiment is 244.12 nm, and the filtration efficiency is 91%.

[0040] Example 2

[0041] This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which includes the following steps:

[0042] S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles and dissolve them in deionized water at 60°C. Stir until completely dissolved and cool to room temperature to prepare a 16wt% polyvinyl alcohol solution.

[0043] Bamboo cellulose was added to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, and stirred at high speed at room temperature until the bamboo cellulose was completely dissolved to obtain a 5 wt% pale yellow bamboo cellulose solution.

[0044] Then, 5 wt% bamboo cellulose solution was added to the PVA solution and mixed evenly. The mass ratio of polyvinyl alcohol solution to bamboo cellulose solution was 20:1 to obtain bamboo fiber-based spinning precursor solution.

[0045] S2, electrostatic air-jet spinning equipment such as Figure 1 As shown, the positive terminal of the high-voltage power supply is connected to the spinning head, and the negative terminal is connected to the aluminum foil covering the roller. The roller speed is set to 125 rpm, the voltage of the electrostatic air-jet spinning is set to 20 kV, the air pressure is set to 60 kPa, and the spinning distance is 25 cm. The above-mentioned bamboo fiber-based spinning precursor solution is injected into a 5 mL plastic syringe, and the feed pump speed is 2 mL / h. The relative humidity and room temperature are controlled at 30-40% and 23±0.2℃, respectively. The power is turned on, and the spinning time is set to 30 min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-3).

[0046] The fiber diameter obtained in this embodiment is 208.55 mm, and the filtration efficiency is 92%.

[0047] Example 3

[0048] This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which includes the following steps:

[0049] S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles and dissolve them in deionized water at 60°C. Stir until completely dissolved and cool to room temperature to prepare a 16wt% polyvinyl alcohol solution.

[0050] Bamboo cellulose was added to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, and stirred at high speed at room temperature until the bamboo cellulose was completely dissolved to obtain a 5 wt% pale yellow bamboo cellulose solution.

[0051] Then, 5 wt% bamboo cellulose solution was added to the PVA solution and mixed evenly. The mass ratio of polyvinyl alcohol solution to bamboo cellulose solution was 30:1 to obtain bamboo fiber-based spinning precursor solution.

[0052] S2, electrostatic air-jet spinning equipment such as Figure 1 As shown, the positive terminal of the high-voltage power supply is connected to the spinning head, and the negative terminal is connected to the aluminum foil covering the roller. The roller speed is set to 125 rpm, the voltage of the electrostatic air-jet spinning is set to 20 kV, the air pressure is set to 60 kPa, and the spinning distance is 25 cm. The above-mentioned bamboo fiber-based spinning precursor solution is injected into a 5 mL plastic syringe, and the feed pump speed is 2 mL / h. The relative humidity and room temperature are controlled at 30-40% and 23±0.2℃, respectively. The power is turned on, and the spinning time is set to 30 min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-2).

[0053] The fiber diameter obtained in this embodiment is 237.58 nm, and the filtration efficiency is 89%.

[0054] Example 4

[0055] This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which includes the following steps:

[0056] S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles and dissolve them in deionized water at 60°C. Stir until completely dissolved and cool to room temperature to prepare a 16wt% polyvinyl alcohol solution.

[0057] Bamboo cellulose was added to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, and stirred at high speed at room temperature until the bamboo cellulose was completely dissolved to obtain a 5 wt% pale yellow bamboo cellulose solution.

[0058] Then, 5 wt% bamboo cellulose solution was added to PVA solution and mixed evenly. The mass ratio of polyvinyl alcohol solution to bamboo cellulose solution was 40:1 to obtain bamboo fiber-based spinning precursor solution.

[0059] S2, electrostatic air-jet spinning equipment such as Figure 1 As shown, the positive terminal of the high-voltage power supply is connected to the spinning head, and the negative terminal is connected to the aluminum foil covering the roller. The roller speed is set to 125 rpm, the voltage of the electrostatic air-jet spinning is set to 20 kV, the air pressure is set to 60 kPa, and the spinning distance is 25 cm. The above-mentioned bamboo fiber-based spinning precursor solution is injected into a 5 mL plastic syringe, and the feed pump speed is 2 mL / h. The relative humidity and room temperature are controlled at 30-40% and 23±0.2℃, respectively. The power is turned on, and the spinning time is set to 30 min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-1).

[0060] The fiber diameter obtained in this embodiment is 255.38 nm, and the filtration efficiency is 89%.

[0061] Example 5

[0062] This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which includes the following steps:

[0063] S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles and dissolve them in deionized water at 60°C. Stir until completely dissolved and cool to room temperature to prepare a 16wt% polyvinyl alcohol solution.

[0064] Bamboo cellulose was added to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, and stirred at high speed at room temperature until the bamboo cellulose was completely dissolved to obtain a 5 wt% pale yellow bamboo cellulose solution.

[0065] Then, 5 wt% bamboo cellulose solution was added to the PVA solution and mixed evenly. The mass ratio of polyvinyl alcohol solution to bamboo cellulose solution was 20:1 to obtain bamboo fiber-based spinning precursor solution.

[0066] S2, electrostatic air-jet spinning equipment such as Figure 1 As shown, the positive terminal of the high-voltage power supply is connected to the spinning head, and the negative terminal is connected to the aluminum foil covering the roller. The roller speed is set to 125 rpm, the voltage of the electrostatic air-jet spinning is set to 20 kV, the air pressure is set to 60 kPa, and the spinning distance is 25 cm. The above-mentioned bamboo fiber-based spinning precursor solution is injected into a 5 mL plastic syringe, and the feed pump speed is 2 mL / h. The relative humidity and room temperature are controlled at 30-40% and 23±0.2℃, respectively. The power is turned on, and the spinning time is set to 60 min to obtain a bamboo fiber-based PVA fiber membrane.

[0067] S3, patterning pressing equipment such as Figure 1As shown, a patterned pressing method is used to pattern the fiber membrane, where the fiber membrane serves as the substrate and a periodically arranged rectangular screen serves as the pattern array template. In a flat vulcanizing machine, at a temperature of 23±0.2℃, a pressure of 4MPa, and a time of 5s, a 10cm×10cm fiber pad is heat-imprinted. To replicate the micro-pattern of the metal mesh, a BET plate is used to cover the fiber membrane for uniform imprinting in this embodiment. A composite nanofiber membrane with a filtration efficiency of 99% is obtained.

[0068] This invention employs electrostatic air-jet spinning combined with an array template method to prepare a bamboo fiber-based air purification membrane. First, a bamboo fiber-based nanofiber membrane is prepared using electrostatic air-jet spinning. Then, the electrostatic air-jet spun fiber membrane is patterned and pressed using a flat vulcanizing machine to obtain the bamboo fiber-based air purification membrane. Polyvinyl alcohol (PVA) is a biodegradable polymer material with excellent performance and environmental friendliness, exhibiting good film-forming properties. Bamboo fiber is a natural, environmentally friendly green fiber with unparalleled advantages over other fibers, such as good air permeability, instant water absorption, strong abrasion resistance, antibacterial, bacteriostatic, deodorizing, UV resistant, and readily biodegradable characteristics. Patterning and pressing the fiber membrane using the array template method improves both its mechanical properties and filtration efficiency. Therefore, this invention provides a method for preparing a bamboo fiber-based air purification membrane, which has promising application prospects in the field of air purification.

[0069] Effect verification:

[0070] I. The morphologies of the PVA, PVA@FB-4, PVA@FB-3, PVA@FB-2, and PVA@FB-1 electrostatically spun nanofiber membranes obtained in Comparative Examples 1 and Examples 1-4 are as follows: Figure 2 As shown, the average fiber diameter of PVA is 356.43 nm; the average fiber diameters of PVA@FB-4, PVA@FB-3, PVA@FB-2, and PVA@FB-1 are 244.12 nm, 208.55 nm, 237.58 nm, and 255.38 nm, respectively. With the increase of the proportion of bamboo fiber solution, the fiber diameter first decreases and then increases.

[0071] II. The ultraviolet absorption spectra of the PVA, PVA@FB-4, PVA@FB-3, PVA@FB-2, and PVA@FB-1 electrostatically spun nanofiber membranes prepared in Comparative Examples 1 and Examples 1-4 are as follows: Figure 3 As shown, for pure PVA nanofiber membranes, no absorption peak appears in the ultraviolet band with a wavelength range of 200-280 nm. When the bamboo fiber solution system is added to the spinning solution system, an absorption peak begins to appear in the ultraviolet band of 200-280 nm, and the absorption peak becomes stronger with the increase of the proportion of bamboo fiber solution.

[0072] III. The filtration efficiency of the electrospun nanofiber membranes prepared in Comparative Examples 1 and Examples 1-4 above is as follows: Figure 4 As shown, PVA@FB-2 has the highest filtration efficiency, exceeding 92%.

[0073] IV. The nanofiber membrane prepared in Example 5 above has an effect on PM2.5. 1.0 and PM 2.5 Changes in filtration efficiency, such as Figure 5 As shown in the figure, after patterning and pressing, the filtration efficiency of the fiber membrane increases from 92% to over 99%.

[0074] The above embodiments only provide some preferred solutions of the present invention. Loofah powder, cotton fiber powder, and hemp fiber powder with a particle size between 100 mesh and 800 mesh can also replace bamboo cellulose powder with similar effects.

[0075] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art can appropriately combine or supplement the technical solutions in the above specific embodiments or take similar alternatives, without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing a biomass-based air purification membrane, characterized by, The specific steps of this method are as follows: Step 1: Place the spinnable polymer material in a solvent, heat and stir at 60°C until dissolved, and cool to obtain a spinnable polymer solution with a concentration of 16wt%; add a biomass material solution with a concentration of 5wt% to the spinnable polymer solution and stir evenly to obtain a spinning precursor solution; the mass ratio of the spinnable polymer solution to the biomass material solution is 20:

1. The spinnable polymer material is polyvinyl alcohol; the biomass material is bamboo cellulose with an average particle size between 100 mesh and 800 mesh. Step 2: Using a roller covered with aluminum foil as a receiving device, electrostatic air-jet spinning is performed on the above-mentioned spinning precursor liquid to obtain an electrostatic air-jet spun fiber membrane, namely the biomass-based air purification membrane. Step 3: The electrostatic air-jet spun fiber membrane is patterned and pressed using a flat vulcanizing machine with an array template method to obtain an air purification membrane with a UV blocking effect; the size of the array template is 60~100 mesh. The bamboo cellulose solution in step one is obtained by the following method: bamboo cellulose is added to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, and stirred at high speed at room temperature until the bamboo cellulose is completely dissolved to obtain the bamboo cellulose solution.

2. The method for preparing a biomass-based air purification membrane according to claim 1, characterized by, Step 2: The voltage of electrostatic air-jet spinning is 20kV, the air pressure is 60KPa, the spinning distance is 25cm, the rotation speed of the roller is 125rpm, and the propulsion speed of the feed pump is 2mL / h; the relative humidity of the environment is 30~40%, the indoor temperature is controlled within the range of 23±0.2℃, and the spinning time is 30min, to obtain an electro-jet spun fiber membrane.

3. The method for preparing the biomass-based air purification membrane according to claim 1, characterized in that, Step 3: The array template size is 60~100 mesh, the pressing time is 5s, the temperature of the flat vulcanizing machine during pressing is 23±0.2℃, the pressure is 4MPa, and a BET plate is used to cover the fiber membrane for uniform imprinting during pressing, thereby obtaining a biomass air purification membrane with a periodic micro-pattern structure.

4. The method for preparing the biomass-based air purification membrane according to claim 1, characterized in that, Step 3: The array template is one or more of the following shapes: triangle, rectangle, hexagon, circle, and ellipse.

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