Laser etching PVDF micro-nano structure ultrafiltration membrane and preparation method thereof

Abstract

The application provides a laser etching PVDF micro-nano structure ultrafiltration membrane and a preparation method thereof, and comprises the following steps: introducing a conjugated double bond into polyvinylidene fluoride by reacting the polyvinylidene fluoride with an organic base to obtain modified polyvinylidene fluoride; adding the modified polyvinylidene fluoride, carboxylated graphene oxide powder, a catalyst, a plasticizer and a pore-forming agent into a dimethylacetamide solution, mixing uniformly to obtain a composite base membrane casting solution, adding an alcohol-water solution for phase inversion to obtain a modified polyvinylidene fluoride ultrafiltration membrane, performing laser etching, immersing the laser etching modified polyvinylidene fluoride ultrafiltration membrane into a hydrophilic solution, and / or spraying a hydrophilic polymer on the surface of the laser etching modified polyvinylidene fluoride ultrafiltration membrane to obtain a target ultrafiltration membrane. Compared with the prior art, the laser etching PVDF ultrafiltration membrane preparation method has obvious beneficial effects in the aspects of improvement of hydrophilicity, improvement of separation efficiency, increase of stability, reduction of energy consumption and environmental protection sustainability, and brings significant innovation and progress to the field of membrane separation technology.

Description

Technical Field

[0001] This invention relates to the field of filter membrane material technology, and in particular to a laser-etched PVDF micro / nano structure ultrafiltration membrane and its preparation method. Background Technology

[0002] Ultrafiltration membrane technology has become one of the important methods in the field of water treatment due to its superior separation performance and wide range of applications. Polyvinylidene fluoride (PVDF) material is widely used in the preparation of ultrafiltration membranes because of its good corrosion resistance, high temperature stability and mechanical strength.

[0003] Ultrafiltration membranes, as an important separation technology, have wide applications in water treatment, desalination, and decolorization. PVDF-GO ultrafiltration membranes, due to their excellent chemical stability and mechanical properties, have also been extensively researched and applied in the ultrafiltration field. However, traditional PVDF ultrafiltration membranes still face some challenges in certain applications. For example, the membrane surface is susceptible to fouling by organic matter, microorganisms, and particulate matter, leading to reduced flux and operational instability. Furthermore, the hydrophobic nature of PVDF itself limits its applicability in treating certain water sources.

[0004] One of the main problems with traditional PVDF-GO ultrafiltration membranes is their insufficient hydrophilicity. Hydrophilicity is a key factor in the separation efficiency and stability of ultrafiltration membranes. However, due to the low surface energy of PVDF materials, their hydrophilicity is poor, making them susceptible to fouling and scaling, which affects the long-term stable operation of the membrane. Furthermore, since the surface morphology of ultrafiltration membranes has a significant impact on their separation performance, improving the micro / nanostructure of the ultrafiltration membrane surface has become an important approach to improving membrane performance. To overcome these problems, researchers have adopted a series of methods to improve the performance of PVDF ultrafiltration membranes, such as modification and surface alteration.

[0005] Currently, improving the hydrophilicity of ultrafiltration membranes typically involves surface modification methods, such as polymer grafting and the introduction of hydrophilic functional groups. However, these methods usually involve multiple steps and can easily cause changes in the physical properties of the membrane, thus affecting its overall performance.

[0006] Therefore, addressing the insufficient hydrophilicity of traditional PVDF-GO ultrafiltration membranes, researching a novel preparation method that can improve the hydrophilicity of ultrafiltration membranes while maintaining their physical properties is particularly important. Laser etching technology, as an advanced micro-nano fabrication technique, has received widespread attention in materials science in recent years. This technology can modify the surface properties of materials by precisely processing their microstructures, thereby achieving the control of material properties. In the field of ultrafiltration membranes, using laser etching technology to process PVDF ultrafiltration membranes into micro- and nano-structures can effectively improve their hydrophilicity, reduce surface fouling and scaling, and enhance separation efficiency and stability. Summary of the Invention

[0007] Therefore, the purpose of this invention is to propose a laser-etched PVDF micro / nano structure ultrafiltration membrane and its preparation method. By using laser etching technology to improve the micro / nano structure on the surface of the ultrafiltration membrane, the hydrophilicity and separation efficiency of the membrane are improved, thereby solving the problems in the prior art.

[0008] The technical solution of this invention is implemented as follows:

[0009] One objective of this invention is to provide a method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane, comprising the following preparation steps:

[0010] S1 Preparation of modified PVDF: Conjugated double bonds are introduced by reacting polyvinylidene fluoride with an organic base to obtain modified polyvinylidene fluoride;

[0011] S2 Preparation of composite base film casting solution: Modified polyvinylidene fluoride, carboxylated graphene oxide powder, catalyst, plasticizer and pore-forming agent are added to dimethylacetamide (DMAC) solution and mixed to obtain composite base film casting solution; the mixing method can be ultrasonic stirring, that is, after each of the above materials is added to DMAC solution, ultrasonic stirring is performed for 0.5 to 1.5 hours;

[0012] S3 Preparation of PVDF Ultrafiltration Membrane: The composite base membrane casting solution is added to an alcohol-water solution for phase inversion to obtain a modified polyvinylidene fluoride ultrafiltration membrane;

[0013] S4 Laser Etching: The surface of the modified polyvinylidene fluoride ultrafiltration membrane is laser etched with a laser wavelength of 15-35nm and a scanning speed of 50-80mm / s to obtain the laser-etched modified polyvinylidene fluoride ultrafiltration membrane.

[0014] S5 Hydrophilicity Improvement: The laser-etched modified polyvinylidene fluoride ultrafiltration membrane is immersed in a hydrophilic solution, and / or a hydrophilic polymer is sprayed onto the surface of the laser-etched modified polyvinylidene fluoride ultrafiltration membrane to obtain a laser-etched PVDF micro / nano structure ultrafiltration membrane.

[0015] To further explain, in step S2, the mass ratio of the modified polyvinylidene fluoride, carboxylated graphene oxide powder, catalyst, plasticizer, and pore-forming agent is 10-15:5-8:5-10:5-9:71-81.

[0016] To further explain, the preparation method of the carboxylated graphene oxide powder includes: dispersing graphene oxide in water, performing liquid-solid phase separation using ultrasound, centrifuging, removing the supernatant, obtaining well-dispersed carboxylated graphene oxide precipitate when the pH is neutral, drying, and obtaining carboxylated graphene oxide powder.

[0017] Further, the catalyst includes at least one of 3-aminopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, or vinyltrisilane;

[0018] The plasticizers include, but are not limited to, phthalates, aliphatic diesters, fatty acid esters, polyphenolic esters, polyol esters, epoxy hydrocarbons, and alkyl sulfonates;

[0019] The pore-forming agents include, but are not limited to, polyethylene glycol, polypyrrolidone, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide.

[0020] Further explanation: In step S1, the organic base includes, but is not limited to: methylamine, urea, ethylamine, ethanolamine, ethylenediamine, dimethylamine, trimethylamine, triethylamine, propylamine, isopropylamine, 1,3-propanediamine, 1,2-propanediamine, tripropylamine, triethanolamine, butylamine, isobutylamine, tert-butylamine, hexylamine, octylamine, aniline, benzylamine, cyclohexylamine, pyridine, hexamethylenetetramine, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, o-aminophenol, m-aminophenol, p-aminophenol, o-toluidine, m-toluidine, p-toluidine, 8-hydroxyquinoline, diphenylamine, benzidine, n-butyllithium, diisopropylaminolithium (LDA), potassium bis(trimethylsilyl)amino (KHMDS), sodium bis(trimethylsilyl)amino (NaHMDS), potassium tert-butoxide, and sodium tert-butoxide.

[0021] To further explain, in step S1, the reaction temperature is 20–60°C and the reaction time is 5–15 min; in step S3, the alcohol-water solution is an ethanol-water solution and / or a methanol-water solution.

[0022] To further explain, in step S5, the soaking time is 1 to 10 minutes, and the soaking process also includes drying. The drying temperature is 50 to 70°C, and the drying time is 3 to 10 minutes. After uniformly spraying the hydrophilic polymer solution onto the surface of the laser-etched modified polyvinylidene fluoride ultrafiltration membrane using an electrostatic spray gun, it is cured by ultraviolet irradiation.

[0023] To further clarify, the hydrophilic solution includes, but is not limited to, ethyl acetate, diethyl ether, ethanol, methanol (wood alcohol), and acetone;

[0024] The hydrophilic polymers include, but are not limited to, polyacrylic acid, polyvinyl acid, polyvinyl alcohol, and polyethylene glycol.

[0025] The second objective of this invention is to provide a laser-etched PVDF micro / nano structure ultrafiltration membrane prepared by the above-mentioned preparation method.

[0026] The third objective of this invention is to provide the application of the aforementioned laser-etched PVDF micro / nano structure ultrafiltration membrane in the removal of organic pollutants, including sulfapyridine. Furthermore, the application of this laser-etched PVDF micro / nano structure ultrafiltration membrane in water treatment also includes multi-stage continuous ultrafiltration desalination under energy recovery and surplus pressure reuse.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) Through laser etching, the present invention can form a larger surface area and micro / nano structures on the surface of PVDF ultrafiltration membrane, thereby significantly improving the hydrophilicity of the membrane. Compared with traditional PVDF membranes, the improved ultrafiltration membrane is less prone to fouling during water treatment, which helps to improve the membrane's separation efficiency and stability.

[0029] (2) The improved hydrophilicity of the PVDF ultrafiltration membrane allows it to interact better with solutes in water, which helps to improve the separation efficiency of polymers, colloidal particles, and microparticles. Therefore, the ultrafiltration membrane of the present invention can achieve more efficient separation of substances in water treatment and wastewater purification.

[0030] (3) The micro- and nano-structures formed by laser etching can exist stably on the membrane surface and are not easily washed away or worn. This stability helps maintain the hydrophilicity and separation efficiency of the membrane surface, enabling the membrane to maintain stability and high efficiency during long-term operation.

[0031] (4) Improved hydrophilicity makes the membrane surface easier for water to pass through, allowing water molecules to pass through the membrane pores more freely, thereby reducing the residence time of water on the membrane surface. This helps to reduce membrane resistance, reduce the pressure or suction force required in the membrane process, and thus reduce energy consumption.

[0032] (5) The preparation method of this invention uses laser etching, which is more environmentally friendly and sustainable than traditional chemical modification methods. It does not require the use of large amounts of chemical reagents, avoids the generation of waste, and conforms to the principle of green preparation.

[0033] In summary, compared with the prior art, the present invention has significant advantages in terms of improved hydrophilicity, increased separation efficiency, increased stability, reduced energy consumption, and environmental sustainability of the PVDF ultrafiltration membrane preparation method through laser etching, bringing significant innovation and progress to the field of membrane separation technology. Attached Figure Description

[0034] Figure 1 The images shown are scanning electron microscope (SEM) images of the surface of the laser-etched PVDF micro / nano structure ultrafiltration membrane in Embodiment 1 of the present invention. Among them, (a1) is a 1500x SEM image of the laser-etched PVDF micro / nano structure ultrafiltration membrane, (a2) is a 10000x SEM image of the surface, and (a3) ​​is a cross-sectional SEM image. Detailed Implementation

[0035] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0036] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0037] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0038] Example 1

[0039] PVDF powder and 1,3-propanediamine were placed in a reactor and reacted at 60°C for 10 min to introduce conjugated double bonds, thus obtaining modified PVDF. The modified PVDF, carboxylated graphene oxide powder, 3-aminopropyltriethoxysilane, phthalate, and sodium dodecyl sulfate were added in batches to a DMAC solution at a mass ratio of 14:5:5:5:71. Each material was ultrasonically stirred for 1 h after being added to the DMAC solution. After all materials were added, a composite membrane casting solution was obtained. The composite membrane casting solution was then added to a 20%-30% ethanol-water solution for phase inversion to obtain a PVDF ultrafiltration membrane. The prepared PVDF ultrafiltration membrane was placed in a laser etching apparatus. By adjusting the laser wavelength to 15-35 nm and the scanning speed to 50-80 mm / s, the surface of a PVDF membrane was etched to obtain a PVDF ultrafiltration membrane with a micro / nano structure. The laser-etched PVDF membrane was then immersed in ethyl acetate, a hydrophilicity-enhancing solution, for 5 minutes to allow the hydrophilicity enhancer to form a thin film on the membrane surface. The immersed membrane was then dried at 60°C for 5 minutes to allow the hydrophilicity enhancer to firmly adhere to the membrane surface, forming an enhanced hydrophilic layer, thus obtaining a laser-etched PVDF micro / nano structured ultrafiltration membrane.

[0040] Example 2

[0041] PVDF powder and p-aminophenol were placed in a reactor and reacted at 20°C for 5 min to introduce conjugated double bonds, thus obtaining modified PVDF. The modified PVDF, carboxylated graphene oxide powder, vinyltriethoxysilane, aliphatic diester, and polypyrrolidone were added in batches to a DMAC solution at a mass ratio of 10:8:10:9:81. Each material was ultrasonically stirred for 0.5 h after being added to the DMAC solution. After all materials were added, a composite membrane casting solution was obtained. The composite membrane casting solution was then added to a 20%-30% ethanol-water solution for phase inversion to obtain a CFGO-PVDF ultrafiltration membrane. The prepared PVDF ultrafiltration membrane was placed in a laser etching apparatus. By adjusting the laser wavelength to 15-35 nm and the scanning speed to 50-80 mm / s, the surface of the PVDF membrane was etched to obtain a PVDF ultrafiltration membrane with a micro / nano structure. A hydrophilic polymer solution of polyvinyl alcohol (PVA) was uniformly sprayed onto the membrane surface using an electrostatic spray gun (2 kV) to form a thin coating. The hydrophilic polymer solution sprayed onto the membrane surface was then cured by ultraviolet irradiation to obtain the laser-etched PVDF micro / nano structured ultrafiltration membrane.

[0042] Example 3

[0043] The difference between Example 3 and Example 1 is that the steps for improving hydrophilicity have changed.

[0044] PVDF powder and p-aminophenol were placed in a reactor and reacted at 20°C for 5 min to introduce conjugated double bonds, resulting in modified PVDF. The modified PVDF, carboxylated graphene oxide powder, vinyltriethoxysilane, aliphatic diester, and polypyrrolidone were added in batches to a DMAC solution at a mass ratio of 10:8:10:9:81. Each material was ultrasonically stirred for 0.5 h after addition. Once all materials were added, a composite membrane casting solution was obtained. This composite membrane casting solution was then added to a 20%-30% ethanol-water solution for phase inversion, yielding a PVDF ultrafiltration membrane. The prepared PVDF ultrafiltration membrane was placed in a laser etching apparatus. The surface of the PVDF membrane was etched by adjusting the laser wavelength to 15-35 nm and the scanning speed to 50-80 mm / s, resulting in a PVDF ultrafiltration membrane with a micro / nano structure. The laser-etched PVDF membrane was then immersed in a hydrophilicity-modifying solution, ethyl acetate, for 1 min, allowing the hydrophilicity modifier to form a thin film on the membrane surface. Then, the soaked membrane was dried at 60°C for 5 minutes to allow the hydrophilicity improver to adhere firmly to the membrane surface, forming an enhanced hydrophilic layer. A polyvinyl alcohol (PVA) hydrophilic polymer solution was then uniformly sprayed onto the membrane surface using an electrostatic spray gun (2Kv) to form a thin coating. The hydrophilic polymer solution sprayed onto the membrane surface was then cured by ultraviolet irradiation to obtain a laser-etched PVDF micro / nanostructured ultrafiltration membrane.

[0045] Comparative Example 1

[0046] The difference between Comparative Example 1 and Example 1 is that graphene oxide (GO) was not added; the remaining raw materials and preparation methods are the same as in Example 1, specifically:

[0047] PVDF powder and 1,3-propanediamine were placed in a reactor and reacted at 60°C for 10 min to introduce conjugated double bonds, resulting in modified PVDF. The modified PVDF, phthalate, and sodium dodecyl sulfate were added in batches to a DMAC solution at a mass ratio of 14:5:76. Each material was ultrasonically stirred for 0.5-1 h after addition to the DMAC solution. After all materials were added, a composite membrane casting solution was obtained. This composite membrane casting solution was then added to a 20%-30% (v / v) ethanol-water solution for phase inversion, yielding a PVDF ultrafiltration membrane. The prepared PVDF ultrafiltration membrane was placed in a laser etching apparatus. The surface of the PVDF membrane was etched by adjusting the laser wavelength to 15-35 nm and the scanning speed to 50-80 mm / s, resulting in a PVDF ultrafiltration membrane with a micro / nano structure. The laser-etched PVDF membrane was then immersed in a hydrophilicity-modifying solution, ethyl acetate, for 5 min to allow the hydrophilicity modifier to form a thin film on the membrane surface. Then, the soaked membrane is dried at 60°C for 5 minutes to allow the hydrophilicity improver to adhere firmly to the membrane surface, forming an enhanced hydrophilic layer, thus obtaining a laser-etched PVDF micro / nano structure ultrafiltration membrane.

[0048] Comparative Example 2

[0049] The main difference between Comparative Example 2 and Example 1 is that no laser etching was performed.

[0050] Specifically, PVDF powder and 1,3-propanediamine were placed in a reactor and reacted at 60°C for 10 min to introduce conjugated double bonds, resulting in modified PVDF. The modified PVDF, carboxylated graphene oxide powder, 3-aminopropyltriethoxysilane, phthalate, and sodium dodecyl sulfate were added in batches to a DMAC solution at a mass ratio of 14:5:5:5:71. Each material was ultrasonically stirred for 1 h after addition to the DMAC solution. Once all materials were added, a composite membrane casting solution was obtained. This composite membrane casting solution was then added to a 20%-30% ethanol-water solution for phase inversion, yielding a PVDF ultrafiltration membrane. The PVDF membrane was then immersed in an ethyl acetate solution for 5 min to allow the hydrophilicity modifier to form a thin film on the membrane surface. The immersed membrane was then dried at 60°C for 5 min to allow the hydrophilicity modifier to firmly adhere to the membrane surface, forming an enhanced hydrophilic layer, resulting in a laser-etched PVDF micro / nanostructured ultrafiltration membrane.

[0051] Comparative Example 3

[0052] The main difference between Comparative Example 3 and Example 1 is that no hydrophilicity improvement was performed.

[0053] PVDF powder and p-aminophenol were placed in a reactor and reacted at 20°C for 5 min to introduce conjugated double bonds, resulting in modified PVDF. The modified PVDF, carboxylated graphene oxide powder, vinyltriethoxysilane, aliphatic diester, and polypyrrolidone were added in batches to a DMAC solution at a mass ratio of 10:8:10:9:81. Each material was ultrasonically stirred for 0.5 h after addition. Once all materials were added, a composite membrane casting solution was obtained. This composite membrane casting solution was then added to a 20%-30% ethanol-water solution for phase inversion, yielding a CFGO-PVDF ultrafiltration membrane. The prepared PVDF ultrafiltration membrane was placed in a laser etching apparatus. By adjusting the laser wavelength to 15-35 nm and the scanning speed to 50-80 mm / s, the surface of the PVDF membrane was etched to obtain a PVDF ultrafiltration membrane with a micro / nano structure.

[0054] Performance testing

[0055] (1) Membrane water purification performance test

[0056] Sulfapyridine solutions with a concentration of 5 mg / L were prepared, and the filtration pressure was adjusted to 0.05 MPa. The micro / nano-structured composite ultrafiltration membranes prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to filtration tests to determine the removal efficiency of the ultrafiltration membranes for sulfapyridine. The flux of the two membranes was calculated by measuring the mass of the permeate and using the formula F = J / A*t (where F is the membrane flux, J is the sample volume, A is the effective membrane area, and t is time). Using the same method, the sulfapyridine concentration was adjusted to 50 mg / L, and the pressure was adjusted to 0.5 MPa, 2.5 MPa, and 20 MPa, respectively. Three commercially available ultrafiltration membranes with good performance (Hydranautics) were selected. The MAX40 ultrafiltration membrane, Dow SFD-2880 ultrafiltration membrane, and MEMOS tubular ultrafiltration membrane were tested, and the removal rate and membrane flux were calculated.

[0057] (2) Organic pollutant removal performance test

[0058] The ultrafiltration cup was used to compare the ultrafiltration membranes prepared in Examples 1-3 and Comparative Examples 1-3 with three commercially available ultrafiltration membranes with good performance. 2. Ultrafiltration Cassette membrane IIHollow Fiber Ultrafiltration Cartridge Ultrafiltration Membrane The organic pollutant removal performance of the IIHollowFiberUltrafiltrationCartridge membrane was tested in three parallel tests, and the removal rate was recorded and the average value was taken.

[0059] (3) Test results

[0060]

[0061]

[0062] The results above show that, compared with the three commercially available ultrafiltration membranes with better performance, the PVDF ultrafiltration membranes prepared in Examples 1-3 of this invention achieve higher removal rates and filtration fluxes for sulfapyridine under a low pressure of 0.05 MPa, with the highest filtration flux reaching 1920 L / m³. 2 The maximum removal rate reaches 90%, and its water flux far exceeds that of commercially available ultrafiltration membranes. It is evident that the ultrafiltration membrane prepared by the method of this invention has advantages such as low energy consumption, high efficiency, and strong filtration capacity. As shown in Example 3 and Comparative Examples 1-3, changing the material mass ratio, omitting the catalyst, failing to modify the PVDF, or changing the mixing method of the raw materials during the preparation process all have a significant impact on the material's performance.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane, characterized in that, The preparation steps include the following: S1 Preparation of modified PVDF: Conjugated double bonds are introduced by reacting polyvinylidene fluoride with an organic base to obtain modified polyvinylidene fluoride; S2 Preparation of composite base film casting solution: Modified polyvinylidene fluoride, carboxylated graphene oxide powder, catalyst, plasticizer and pore-forming agent are added to dimethylacetamide solution and mixed to obtain composite base film casting solution; S3 Preparation of PVDF Ultrafiltration Membrane: The composite base membrane casting solution is added to an alcohol-water solution for phase inversion to obtain a modified polyvinylidene fluoride ultrafiltration membrane; S4 Laser Etching: The surface of the modified polyvinylidene fluoride ultrafiltration membrane is laser etched with a laser wavelength of 15~35nm and a scanning speed of 50~80mm / s to obtain the laser-etched modified polyvinylidene fluoride ultrafiltration membrane. S5 Hydrophilicity Improvement: The laser-etched modified polyvinylidene fluoride ultrafiltration membrane is immersed in a hydrophilic solution, and / or a hydrophilic polymer is sprayed onto the surface of the laser-etched modified polyvinylidene fluoride ultrafiltration membrane to obtain a laser-etched PVDF micro / nano structure ultrafiltration membrane. In step S2, the mass ratio of the modified polyvinylidene fluoride, carboxylated graphene oxide powder, catalyst, plasticizer, and pore-forming agent is 10~15:5~8:5~10:5~9:71~81. The catalyst includes at least one of 3-aminopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, or vinyltrisilane.

2. The method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane according to claim 1, characterized in that, The method for preparing the carboxylated graphene oxide powder includes: dispersing graphene oxide in water, performing liquid-solid phase separation using ultrasound, centrifuging, removing the supernatant, obtaining well-dispersed carboxylated graphene oxide precipitate when the pH is neutral, drying, and obtaining carboxylated graphene oxide powder.

3. The method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane according to claim 1, characterized in that, The plasticizer includes at least one of phthalates, aliphatic diesters, fatty acid esters, polyphenolic esters, polyol esters, epoxy hydrocarbons, and alkyl sulfonates. The pore-forming agent includes at least one of polyethylene glycol, polypyrrolidone, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide.

4. The method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane according to claim 1, characterized in that, In step S1, the organic base includes at least one of methylamine, urea, ethylamine, ethanolamine, ethylenediamine, dimethylamine, trimethylamine, triethylamine, propylamine, isopropylamine, 1,3-propanediamine, 1,2-propanediamine, tripropylamine, triethanolamine, butylamine, isobutylamine, tert-butylamine, hexylamine, octylamine, aniline, benzylamine, cyclohexylamine, pyridine, hexamethylenetetramine, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, o-aminophenol, m-aminophenol, p-aminophenol, o-toluidine, m-toluidine, p-toluidine, 8-hydroxyquinoline, diphenylamine, benzidine, n-butyllithium, diisopropylaminolithium, bis(trimethylsilyl)aminopotassium, bis(trimethylsilyl)aminosodium, potassium tert-butoxide, and sodium tert-butoxide.

5. The method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane according to claim 1, characterized in that, In step S1, the reaction temperature is 20~60℃ and the reaction time is 5~15min; in step S3, the alcohol-water solution is an ethanol-water solution and / or a methanol-water solution.

6. The method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane according to claim 1, characterized in that, In step S5, the soaking time is 1~10 min, and after soaking, drying is also included. The drying temperature is 50~70℃ and the drying time is 3~10 min. After uniformly spraying the hydrophilic polymer solution onto the surface of the laser-etched modified polyvinylidene fluoride ultrafiltration membrane using an electrostatic spray gun, it is cured by ultraviolet irradiation.

7. The method for preparing a laser-etched PVDF micro / nano structured ultrafiltration membrane according to claim 1 or 6, characterized in that, The hydrophilic solution includes at least one of ethyl acetate, diethyl ether, ethanol, methanol, and acetone; The hydrophilic polymer includes at least one of polyacrylic acid, polyvinyl acid, polyvinyl alcohol, and polyethylene glycol.

8. The laser-etched PVDF micro / nano structure ultrafiltration membrane prepared by the method for preparing a laser-etched PVDF micro / nano structure ultrafiltration membrane according to any one of claims 1 to 7.

9. The application of the laser-etched PVDF micro / nano structure ultrafiltration membrane according to claim 8 in the removal of organic pollutants, characterized in that, The organic pollutants include sulfapyridine.

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