Preparation method of biomass-based air purification membrane

Abstract

The invention discloses a biomass-based air purification membrane preparation method, and belongs to the technical field of air purification membrane preparation, the method comprises the following steps: 1, placing a spinnable high polymer material in a solvent, heating and stirring until the spinnable high polymer material is dissolved, cooling, adding a biomass material solution, and uniformly mixing to obtain a spinning precursor solution; 2, a roller is used as a receiving device, the spinning precursor solution is subjected to electrostatic air jet spinning, and an electrostatic air jet spinning fiber membrane is obtained; and 3, carrying out patterned pressing on the electrostatic air jet spinning fiber membrane by using a plate vulcanizing machine by adopting an array template method, so that the electrostatic air jet spinning fiber membrane has a periodic micro-pattern structure, and obtaining the air purification membrane. The air purification membrane with the blocking effect on ultraviolet rays is high in filtering efficiency and small in pressure drop and has good application prospects in the field of air purification.

Description

Technical Field

[0002] The invention belongs to the technical field of air purification, and relates to a method for preparing a bio-based nanofiber membrane which is easy to process, has high efficiency in filtering, and has a UV blocking effect. Background Art

[0003] In today's era, air pollution has become a major global environmental problem. The air around us is filled with a variety of tiny particles, as well as pollutants such as bacteria and mold. When people breathe, these harmful substances will enter the respiratory system, causing extremely serious harm to human health, such as causing respiratory diseases and reducing lung function.

[0004] In daily use, after a period of operation, pollutants such as dust, pollen, and tiny particles will gradually accumulate inside and on the surface of air conditioners and household filters. This will cause a significant decrease in filtration efficiency, and the circulation of air in the filter will also be hindered, affecting the normal operation of the air conditioner or household filter. What is more serious is that bacterial dust is mixed in these accumulated pollutants, which can easily invade the human body with the flow of air, thus posing a potential threat to people's health. In order to avoid these problems, the filter membrane needs to be replaced frequently. However, most traditional filter membranes are made of petroleum-based materials and are prepared using a melt-blown process. This preparation method has many disadvantages. On the one hand, its processing stability is poor, and quality instability may occur during the production process, 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 and easy to cause environmental pollution.

[0005] Biomass, with its natural and renewable advantages, can effectively solve the above-mentioned problems of petroleum-based materials. However, the processing difficulty of biomass material nanofiber membrane is much higher than that of petroleum-based materials. Therefore, it is still a huge challenge to develop an electrospinning nanofiber membrane that is easy to process, has high efficiency filtration, and is antibacterial for bio-based nanofiber membranes. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a method for preparing a biomass-based air purification membrane. The technical solution adopted by the present invention has the following specific steps: Step 1: placing a spinnable polymer material in a solvent, heating and stirring until it is dissolved, and cooling to obtain a spinnable polymer solution with a concentration of 10-20wt%; adding a biomass material solution with a concentration of 1-10wt% to the spinnable polymer solution and stirring evenly to obtain a spinning precursor solution; the mass ratio of the spinnable polymer solution to the biomass material solution is (10-40):1; The spinnable polymer material is selected from one or a combination of polyvinyl alcohol, polyvinylidene fluoride, polylactic acid, polycaprolactone, polyethylene glycol, polyacrylamide, polyacrylic acid, and polyvinyl pyrrolidone; among them, polyvinyl alcohol is preferred.

[0007] The biomass material is selected from one or a combination 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; Step 2: Using a roller covered with aluminum foil as a receiving device, the above spinning precursor solution is subjected to electrostatic air-jet spinning to obtain an electrostatic air-jet spun fiber membrane, namely the biomass-based air purification membrane.

[0008] Furthermore, the method also includes step three: using an array template method to pattern-press the electrostatic air-spun fiber membrane using a flat vulcanizer to obtain an air purification membrane with a UV-blocking effect.

[0009] In a preferred embodiment of the present invention, the heating and stirring temperature of the polyvinyl alcohol particles in step 1 is 60°C; 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% light yellow bamboo cellulose solution; In a preferred embodiment of the present invention, the voltage of the electrostatic air jet spinning in step 2 is 12~20kV, the air pressure is 30~80KPa, the spinning distance is 20~30cm, the rotation speed of the drum is 100~150rpm, and the propulsion speed of the propulsion pump is 0.5~3mL / h.

[0010] In a preferred embodiment of the present invention, in step 2, the relative humidity of the environment is 30-40%, and the indoor temperature is controlled within the range of 23±0.2°C.

[0011] In a preferred embodiment of the present invention, the size of the array template in step three is 60-100 meshes, and the pressing time is 5-60s.

[0012] In a preferred embodiment of the present invention, the array template in step three is one or more of a triangle, a rectangle, a hexagon, a circle, and an ellipse.

[0013] In a preferred embodiment of the present invention, during the pattern pressing in step 3, the temperature of the flat vulcanizer is 23±0.2° C., the pressure is 4 MPa, and the time is 5 s.

[0014] In a preferred embodiment of the present invention, in step three, a BET plate is used to cover the fiber membrane for uniform imprinting.

[0015] Beneficial effects of the present invention: 1. The air purification membrane prepared by the method of the present invention is an environmentally friendly bio-based air-jet electrospun fiber membrane with high filtration efficiency, good UV resistance and processing stability. 2. The preparation method provided by the present invention utilizes electrostatic air-spray spinning technology to prepare an electrostatic air-sprayed fiber membrane. The membrane cannot effectively block ultraviolet rays when spinning is completed, and the filtration efficiency is low because the nanofiber diameter is relatively thick and the overlap between the thicker fibers leads to a larger porosity; then, natural biomass materials are added to the spinning solution to uniformly mix the biomass materials in the spinning solution, and by controlling the content of the biomass materials, the fiber membrane has ultraviolet blocking properties; finally, the fiber membrane is patterned and pressed using an array template method, and the obtained fiber membrane can effectively block ultraviolet rays and has the characteristics of high filtration efficiency, low pressure drop, etc. This bio-based electrostatic air-sprayed nanofiber membrane can provide new ideas for the research and development of air purification membrane materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic flow chart of a method for preparing a bamboo fiber-based air purification membrane provided in an embodiment of the present invention.

[0017] Figure 2 These are scanning electron microscope images of the PVA and PVA@FB-x fiber membranes of the present invention.

[0018] Figure 3 It is the ultraviolet absorption spectrum of the PVA and PVA@FB-x fiber membranes of the present invention.

[0019] Figure 4 The PVA and PVA@FB-x fiber membranes of the present invention are 1.0 、PM 2.5 and PM 10 Filtration efficiency diagram.

[0020] Figure 5 The fiber membrane of PVA@FB-2 before and after patterned pressing is PM 1.0 、PM 2.5 and PM 10 Filtration efficiency diagram. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific implementation methods. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Comparative Example 1 This comparative example provides a method for preparing an air purification membrane without adding a bamboo fiber base, which comprises the following steps: S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles, dissolve them in deionized water at 60°C, stir until completely dissolved, and cool to room temperature to prepare a 16 wt% PVA spinning precursor solution.

[0023] S2, electrostatic air jet spinning equipment such as Figure 1 As shown in , the positive electrode of the high-voltage power supply is connected to the spinning head, the negative electrode is connected to the aluminum foil covering the drum, the rotation speed of the drum is set to 125rpm, the voltage of the electrostatic air jet spinning is set to 20kV, the air pressure is set to 60KPa, and the spinning distance is 25cm. The above PVA spinning precursor solution is injected into a 5mL plastic syringe, and the propulsion speed of the propulsion pump is 2mL / h. The relative humidity and room temperature of the environment are controlled at 30-40% and 23±0.2℃ respectively. The power is turned on, and the spinning time is set to 30min to obtain a PVA fiber membrane (referred to as PVA).

[0024] The diameter of the PVA fiber obtained in this comparative example is 356.43 nm, and the filtration efficiency is 62%.

[0025] Example 1 This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which comprises the following steps: S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles, dissolve them in deionized water at 60° C., stir until completely dissolved, and cool to room temperature to prepare a 16 wt % polyvinyl alcohol solution; The bamboo cellulose was added into 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 5wt% light yellow bamboo cellulose solution; Then, 5 wt % of the bamboo cellulose solution was added into the PVA solution and mixed evenly, and the mass ratio of the polyvinyl alcohol solution to the bamboo cellulose solution was 10:1, so as to obtain a bamboo fiber-based spinning precursor solution.

[0026] S2, electrostatic air jet spinning equipment such as Figure 1 As shown in , the positive electrode of the high-voltage power supply is connected to the spinning head, the negative electrode is connected to the aluminum foil covering the drum, the speed of the drum is set to 125rpm, the voltage of the electrostatic air jet spinning is set to 20kV, the air pressure is set to 60KPa, and the spinning distance is 25cm. The above bamboo fiber-based spinning precursor solution is injected into a 5mL plastic syringe, and the propulsion speed of the propulsion pump is 2mL / h. The relative humidity and room temperature of the environment are controlled at 30-40% and 23±0.2℃ respectively. The power is turned on, and the spinning time is set to 30min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-4).

[0027] The fiber diameter obtained in this example is 244.12 nm, and the filtration efficiency is 91%.

[0028] Example 2 This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which comprises the following steps: S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles, dissolve them in deionized water at 60° C., stir until completely dissolved, and cool to room temperature to prepare a 16 wt % polyvinyl alcohol solution; The bamboo cellulose was added into 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 5wt% light yellow bamboo cellulose solution; Then, 5 wt % of the bamboo cellulose solution was added into the PVA solution and mixed evenly, and the mass ratio of the polyvinyl alcohol solution to the bamboo cellulose solution was 20:1, so as to obtain a bamboo fiber-based spinning precursor solution.

[0029] S2, electrostatic air jet spinning equipment such as Figure 1 As shown in , the positive electrode of the high-voltage power supply is connected to the spinning head, the negative electrode is connected to the aluminum foil covering the drum, the speed of the drum is set to 125rpm, the voltage of the electrostatic air jet spinning is set to 20kV, the air pressure is set to 60KPa, and the spinning distance is 25cm. The above bamboo fiber-based spinning precursor solution is injected into a 5mL plastic syringe, and the propulsion speed of the propulsion pump is 2mL / h. The relative humidity and room temperature of the environment are controlled at 30-40% and 23±0.2℃ respectively. The power is turned on, and the spinning time is set to 30min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-3).

[0030] The fiber diameter obtained in this embodiment is 208.55 and the filtration efficiency is 92%.

[0031] Example 3 This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which comprises the following steps: S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles, dissolve them in deionized water at 60° C., stir until completely dissolved, and cool to room temperature to prepare a 16 wt % polyvinyl alcohol solution; The bamboo cellulose was added into 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 5wt% light yellow bamboo cellulose solution; Then, 5 wt % of the bamboo cellulose solution was added into the PVA solution and mixed evenly, and the mass ratio of the polyvinyl alcohol solution to the bamboo cellulose solution was 30:1, so as to obtain a bamboo fiber-based spinning precursor solution.

[0032] S2, electrostatic air jet spinning equipment such as Figure 1 As shown in , the positive electrode of the high-voltage power supply is connected to the spinning head, the negative electrode is connected to the aluminum foil covering the drum, the speed of the drum is set to 125rpm, the voltage of the electrostatic air jet spinning is set to 20kV, the air pressure is set to 60KPa, and the spinning distance is 25cm. The above bamboo fiber-based spinning precursor solution is injected into a 5mL plastic syringe, and the propulsion speed of the propulsion pump is 2mL / h. The relative humidity and room temperature of the environment are controlled at 30-40% and 23±0.2℃ respectively. The power is turned on, and the spinning time is set to 30min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-2).

[0033] The fiber diameter obtained in this example is 237.58 nm, and the filtration efficiency is 89%.

[0034] Example 4 This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which comprises the following steps: S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles, dissolve them in deionized water at 60° C., stir until completely dissolved, and cool to room temperature to prepare a 16 wt % polyvinyl alcohol solution; The bamboo cellulose was added into 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 5wt% light yellow bamboo cellulose solution; Then, 5 wt % of the bamboo cellulose solution was added into the PVA solution and mixed evenly, and the mass ratio of the polyvinyl alcohol solution to the bamboo cellulose solution was 40:1, so as to obtain a bamboo fiber-based spinning precursor solution.

[0035] S2, electrostatic air jet spinning equipment such as Figure 1 As shown in , the positive electrode of the high-voltage power supply is connected to the spinning head, the negative electrode is connected to the aluminum foil covering the drum, the speed of the drum is set to 125rpm, the voltage of the electrostatic air jet spinning is set to 20kV, the air pressure is set to 60KPa, and the spinning distance is 25cm. The above bamboo fiber-based spinning precursor solution is injected into a 5mL plastic syringe, and the propulsion speed of the propulsion pump is 2mL / h. The relative humidity and room temperature of the environment are controlled at 30-40% and 23±0.2℃ respectively. The power is turned on, and the spinning time is set to 30min to obtain a bamboo fiber-based PVA fiber membrane (denoted as PVA@FB-1).

[0036] The fiber diameter obtained in this example is 255.38 nm, and the filtration efficiency is 89%.

[0037] Example 5 This embodiment provides a method for preparing a bamboo fiber-based air purification membrane, which comprises the following steps: S1. Weigh a certain amount of polyvinyl alcohol (PVA) particles, dissolve them in deionized water at 60° C., stir until completely dissolved, and cool to room temperature to prepare a 16 wt % polyvinyl alcohol solution; The bamboo cellulose was added into 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 5wt% light yellow bamboo cellulose solution; Then, 5 wt % of the bamboo cellulose solution was added into the PVA solution and mixed evenly, and the mass ratio of the polyvinyl alcohol solution to the bamboo cellulose solution was 20:1, so as to obtain a bamboo fiber-based spinning precursor solution.

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

[0039] S3, patterned pressing equipment such as Figure 1 As shown in , the fiber membrane is patterned by an array template method, in which the fiber membrane is used as a substrate and a rectangular screen with periodic arrangement is used as a pattern array template. In a flat vulcanizer, the temperature is 23±0.2℃, the pressure is 4MPa, and the time is 5s, and a 10cm×10cm fiber mat is thermally imprinted. In order to replicate the micropattern of the metal mesh, a BET plate is used in this embodiment to cover the fiber membrane for uniform imprinting. A composite nanofiber membrane with a filtration efficiency of 99% is obtained.

[0040] The embodiment of the present invention adopts electrostatic air-jet spinning technology combined with array template method to prepare bamboo fiber-based air purification membrane. First, bamboo fiber-based nanofiber membrane is prepared by electrostatic air-jet spinning technology, and then, the electrostatic air-jet spinning fiber membrane is subjected to pattern pressing treatment by a flat vulcanizer to obtain the bamboo fiber-based air purification membrane. Polyvinyl alcohol (PVA) is a biodegradable polymer material with good performance and environmentally friendly performance and good film-forming property. Bamboo fiber is a natural environmentally friendly green fiber, which has advantages that other fibers cannot match, such as good air permeability, instant water absorption, strong wear resistance, antibacterial, antibacterial, deodorant, anti-ultraviolet and easy biodegradation. The fiber membrane is patterned and pressed by the array template method, and the mechanical properties and filtration efficiency are improved. Therefore, the present invention provides a method for preparing a bamboo fiber-based air purification membrane, which has good application prospects in the field of air purification.

[0041] Effect verification: 1. The morphology of the electrostatically spun nanofiber membranes of PVA, PVA@FB-4, PVA@FB-3, PVA@FB-2 and PVA@FB-1 prepared in Comparative Example 1 and Examples 1 to 4 is as follows: Figure 2 The average fiber diameter of PVA is 356.43nm; the average fiber diameters of PVA@FB-4, PVA@FB-3, PVA@FB-2 and PVA@FB-1 are 244.12nm, 208.55nm, 237.58nm and 255.38nm, respectively. With the increase of the proportion of bamboo fiber solution, the fiber diameter first decreases and then increases.

[0042] 2. The ultraviolet absorption spectra of the PVA, PVA@FB-4, PVA@FB-3, PVA@FB-2 and PVA@FB-1 electrostatic air-spun nanofiber membranes prepared in the above-mentioned comparative example 1 and examples 1 to 4 are as follows: Figure 3 As shown. For pure PVA nanofiber membrane, there is no absorption peak in the ultraviolet band of 200-280nm wavelength. When the bamboo fiber solution system is added to the spinning solution system, an absorption peak begins to appear in the ultraviolet band of 200-280nm, and as the proportion of bamboo fiber solution increases, the absorption peak becomes stronger and stronger.

[0043] 3. The filtration efficiency of the electrospun nanofiber membranes obtained in Comparative Example 1 and Examples 1 to 4 is as follows: Figure 4 As shown in the figure, PVA@FB-2 has the highest filtration efficiency, which is above 92%.

[0044] 4. Effect of the Nanofiber Membrane Prepared in Example 5 on PM 1.0 and PM 2.5 The change of filtration efficiency is as follows Figure 5 As shown in the figure, it can be seen that after patterned pressing, the filtration efficiency of the fiber membrane increased from 92% to more than 99%.

[0045] 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.

[0046] The specific embodiments described in this document are merely examples of the spirit of the present invention. For those skilled in the art, the technical solutions in the above-mentioned specific embodiments can be appropriately combined or supplemented or replaced in a similar manner, but this will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.

Claims

1. A method for preparing a biomass-based air purification membrane, characterized in that: The steps of this method are as follows: Step 1: placing a spinnable polymer material in a solvent, heating and stirring until it is dissolved, and cooling to obtain a spinnable polymer solution with a concentration of 10-20wt%; adding a biomass material solution with a concentration of 1-10wt% to the spinnable polymer solution and stirring evenly to obtain a spinning precursor solution; the mass ratio of the spinnable polymer solution to the biomass material solution is (10-40):1; The spinnable polymer material is selected from one or a combination of polyvinyl alcohol, polyvinylidene fluoride, polylactic acid, polycaprolactone, polyethylene glycol, polyacrylamide, polyacrylic acid, and polyvinyl pyrrolidone; The biomass material is selected from one or a combination 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; Step 2: Using a roller covered with aluminum foil as a receiving device, the above spinning precursor solution is subjected to electrostatic air-jet spinning to obtain an electrostatic air-jet spun fiber membrane, namely the biomass-based air purification membrane.

2. The method for preparing a biomass-based air purification membrane according to claim 1, characterized in that: The method also includes step three: using an array template method to pattern-press the electrostatic air-spun fiber membrane using a flat vulcanizer to obtain an air purification membrane with a UV-blocking effect.

3. The method for preparing a biomass-based air purification membrane according to claim 1, characterized in that: The spinnable polymer material is polyvinyl alcohol, and the biomass material is bamboo cellulose.

4. The method for preparing a biomass-based air purification membrane according to claim 3, characterized in that: The heating and stirring temperature of the polyvinyl alcohol particles in step 1 is 60°C.

5. The method for preparing a biomass-based air purification membrane according to claim 3, characterized in that: In step 1, the bamboo cellulose solution is obtained by the following method: adding bamboo cellulose to a solution prepared by sodium hydroxide, urea and deionized water in a mass ratio of 0.5:1.5:8, stirring at high speed at room temperature until the bamboo cellulose is completely dissolved, to obtain a bamboo cellulose solution.

6. The method for preparing a biomass-based air purification membrane according to claim 1, characterized in that: Step 2: The voltage of electrostatic air jet spinning is 12~20kV, the air pressure is 30~80KPa, the spinning distance is 20~30cm, the rotation speed of the drum is 100~150rpm, and the propulsion speed of the propulsion pump is 0.5~3mL / h; the relative humidity of the environment is 30~40%, and the indoor temperature is controlled within the range of 23±0.2℃.

7. The method for preparing a biomass-based air purification membrane according to claim 2, characterized in that: Step 3: The size of the array template is 60-100 mesh, and the pressing time is 5-60s.

8. The method for preparing a biomass-based air purification membrane according to claim 2, characterized in that: Step three: the array template is one or more of a triangle, rectangle, hexagon, circle, and ellipse.

9. The method for preparing a biomass-based air purification membrane according to claim 2, characterized in that: During the pattern pressing in step 3, the temperature of the flat vulcanizer is 23±0.2°C, the pressure is 4 MPa, and the time is 5 s.

10. The method for preparing a biomass-based air purification membrane according to claim 2, characterized in that: Step 3: Use a BET plate to cover the fiber membrane.

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