A microfluidic coupling grafting modification technology for preparing high-flux anti-pollution nanofiber separation membrane

Abstract

The application relates to a high-flux anti-pollution nanofiber separation membrane prepared by a microfluidic coupling graft modification technology. The application improves the hydrophilic performance of the membrane by using a microfluidic limited channel to strengthen the graft reaction technology, constructs nanofiber membrane fibers in the microfluidic chip, and simultaneously uses a microfluidic spinning equipment to prepare the separation membrane. In the process, the membrane preparation substrate is dissolved in a solvent, and a thermoplastic polyurethane elastomer is added, and heating and stirring are performed until a transparent solution is formed. Sulfobetaine type methacrylamide monomers and anhydrous copper chloride are dissolved in the solvent. The application has the advantages that a method for strengthening the hydrophilic modification process is innovated, the microchannel limitation greatly improves the grafting rate so that the hydrophilic performance of the separation membrane is improved. The method is time-saving and efficient, can on-line couple the ultraviolet light-induced free radical polymerization modification reaction with the fiber membrane production process, successfully grafts the sulfobetaine type methacrylamide monomers, realizes the hydrophilic modification of the membrane fiber surface, obviously improves the anti-pollution performance of the membrane, is beneficial to the long-term stable operation of the membrane, has a good interception rate for oil stains, has a good permeation rate for polypeptides, and the fiber membrane prepared by the microfluidic spinning technology also has the characteristics of large porosity and easy regulation. Therefore, the high-flux anti-pollution nanofiber separation membrane prepared by the method can be specifically regulated according to actual conditions to meet different separation requirements, and has a wide application.

Description

Technical Field

[0001] This invention relates to a microfluidic coupling grafting modification technique for preparing high-throughput, antifouling nanofiber separation membranes, belonging to the field of separation membrane preparation technology. The modified membrane has the advantages of simple and time-saving manufacturing method, high pure water flux, good retention performance of oil-in-water emulsions with long / short chain carbon, and good antifouling and recovery properties. It is suitable for oil-water separation, protein retention and other fields. Background Technology

[0002] With the increasing development of society, large amounts of oily wastewater are inevitably generated in industrial production and daily life. The food, metallurgical, petroleum, and transportation industries are significant sources of oily wastewater. Direct discharge of oily wastewater into rivers and lakes reduces dissolved oxygen, impacting aquatic life, causing foul odors, and lowering the utilization value of water resources. If oily wastewater enters the soil, it severely affects normal soil metabolism, further impacting the normal growth of plants and crops. Furthermore, oil spills in the ocean can damage beaches and disrupt the normal marine environment. Efficient treatment of oily wastewater is crucial for environmental protection and human health. Traditional treatment processes, including gravity separation, air flotation, and chemical methods, suffer from low oil-water separation efficiency, high energy consumption, large land area requirements, and severe secondary pollution. Oily wastewater often forms stable oil-in-water emulsions, with emulsified oil particles typically ranging from hundreds of nanometers to tens of micrometers in size. These emulsified oils are difficult to remove from water. Furthermore, with the development of biomedicine and the increasing pursuit of health standards, the demand for proteins and peptides is growing. However, the separation of proteins and peptides involves complex feed solutions, making separation difficult. Therefore, there is an urgent need to develop a sustainable, efficient, reliable, and space-efficient technology to achieve continued industrial development.

[0003] Membrane separation technology is a promising advanced technology, widely used in oily wastewater treatment due to its low cost, lack of chemical additives, high efficiency, and environmental friendliness. However, some membranes are hydrophobic with low surface energy and poor surface wettability, making them susceptible to adhesion of organic matter in the water, leading to pore blockage, significantly reduced membrane flux and separation performance, and consequently, affecting their lifespan. One effective method to improve membrane wettability is to graft or coat hydrophilic monomers onto the membrane surface. These monomers attract water molecules to form a hydration protective layer, protecting the membrane surface and pores from oil droplets and other pollutants. In recent years, polymer nanofiber membranes prepared by electrospinning technology have also attracted increasing attention. Unlike membrane materials prepared by traditional phase inversion methods, nanofiber membranes prepared by microfluidic spinning / spraying are composed of overlapping nanoscale fiber materials. Therefore, nanofiber membranes possess characteristics such as high specific surface area, high porosity, high surface roughness, and high orientation. In addition, compared with other membrane fabrication methods, microfluidic spinning / spraying is more likely to graft specific functional materials or functional groups onto the surface of a single nanofiber or coat it onto the surface of a nanofiber membrane substrate, and has excellent development prospects in the preparation of novel composite membrane materials.

[0004] A high-throughput, antifouling nanofiber membrane prepared using a microfluidic confined channel enhancement technique combined with spinning / spraying technology can be widely applied in practical production. Currently, there is extensive research both domestically and internationally on methods for grafting specific functional materials or functional groups onto the surface of single nanofibers using electrospinning and electrostatic spraying. However, research on combining microfluidic confined channel enhancement techniques with microfluidic spinning / spraying to improve membrane preparation efficiency is limited. Therefore, it is necessary to develop a high-throughput, hydrophilic modified nanofiber separation membrane with wide applicability, stable performance, and good separation properties. Summary of the Invention

[0005] The purpose of this invention is to address the current problem of membranes being easily fouled, which prevents them from meeting the requirements of membrane separation. This invention provides a microfluidic coupling grafting modification technique for preparing high-flux, anti-fouling nanofiber separation membranes. The hydrophilic modified nanofiber membranes prepared by this method have advantages such as high flux, good anti-fouling performance, thin thickness, time-saving and efficient membrane fabrication, and good separation effect on long / short chain carbon-in-oil emulsions. They are suitable for membrane separation processes and can ensure excellent separation performance and long-term stable operation.

[0006] The high-throughput, antifouling nanofiber separation membrane prepared by this invention combines microfluidic confined channel enhancement grafting technology with spinning / spraying technology, and further incorporates UV-induced free radical polymerization modification within a microfluidic chip. Simultaneously, a micropump propels the reaction solution into the membrane preparation section for fiber membrane fabrication. The process includes the following steps: Step 1): Preparation of the membrane substrate solution. The substances involved in the preparation of the membrane substrate solution are composed of the following mass percentages: substrate 10-20%, solvent 70-85%, and thermoplastic polyurethane elastomer 5-10%. The substrate, thermoplastic polyurethane elastomer, and solvent are heated and stirred at 60-80℃ until a transparent liquid is formed, and then set aside. Step 2): Preparation of the modified substance solution. Feed solution 2 is prepared from the following components in the indicated mass percentages: 0.5-1% sulfonate betaine-type methacrylamide monomers, 0.5-1% anhydrous copper chloride, with the remainder being solvent. Dissolve the sulfonate betaine-type methacrylamide monomers in the solvent and add anhydrous copper chloride, stirring until completely dissolved. Set aside for later use. Separately, weigh out 0%-1% inorganic hydrophilic nanoparticles and dissolve them in the solvent for later use. Step 3): Modification and preparation of the fiber membrane: Feed solution one and feed solution two are added to the chip placed under ultraviolet light at a certain flow rate ratio using a microfluidic pump of a microfluidic device. The two solutions mix in the chip and undergo ultraviolet light-induced free radical polymerization modification reaction while flowing in the chip. After the reaction in the chip is completed, the unit volume of reaction solution is driven by the pump to carry out electrospinning according to the set path and flow rate. The voltage and humidity are adjusted according to the objective conditions to ensure the stability of the spinning process. The following operating parameters are involved in this process: the ultraviolet power is selected between 24 W and 48 W, the wavelength is selected as 365 nm, and the reaction time is 20 to 45 min. The spinning flow rate of the feed solution is 0.5 to 0.8 ml / h, the voltage is selected as 16 to 20 kV, and the humidity of the spinning process is between 40% and 60%, which can be adjusted according to the objective environmental conditions to ensure the smooth spinning process. Step 4): The prepared membrane is rinsed with anhydrous ethanol and then rinsed with deionized water and dried in a vacuum dryer.

[0007] Preferably, the stirring time of the feed liquid in step 1) is 2-4 hours.

[0008] Preferably, the substrate in step 1) is one of polyvinylidene fluoride 1001, polyvinylidene fluoride 1015, polyethersulfone, and polypropylene.

[0009] Preferably, the solvent in step 1) can be one of N,N-dimethylformamide or N-methylpyrrolidone.

[0010] Preferably, in step 2), the sulfonate betaine methacrylamide monomer is one of methacryloyl ethyl sulfonate betaine, sulfonate betaine methacrylate, methacrylamide, and N,N-dimethyl-N-methacrylamidopropyl-N-propane sulfonate inner salt.

[0011] Preferably, the mass percentage of anhydrous copper chloride in step 2) is 0.5-1%.

[0012] Preferably, the inorganic hydrophilic nanoparticles in step 2) can be nano-sized SiO2, nano-sized TiO2, etc.

[0013] Preferably, the overall film-forming time in step 3) is 1-1.6 h.

[0014] This invention discloses a high-flux, antifouling nanofiber separation membrane prepared using a microfluidic coupling grafting modification technique. The membrane is characterized by a thickness of 25–100 µm and a pure water flux of 5000–10000 L·m⁻¹ at 0.1 bar pressure. -2 ·h -1 The hexadecane water-in-oil emulsion exhibits a hexadecane rejection rate of ≥98%, a petroleum ether water-in-oil emulsion rejection rate of ≥99%, and a lysine peptide permeability of >99%, while also demonstrating good antifouling properties and flux recovery rate. Beneficial effects

[0015] Compared with existing technologies, this invention combines microfluidic confined channel-enhanced grafting reaction technology with spinning / spraying technology to perform grafting hydrophilic modification reactions within a microfluidic chip. Simultaneously, a microfluidic pump propels the reaction solution into the microfluidic spinning section for fiber membrane preparation, thereby obtaining a nanofiber membrane with high throughput, good antifouling performance, and good long-term stability. Ultraviolet light-induced free radical polymerization modification is used in the substrate to successfully graft zwitterionic monomers, such as sulfonate betaine and methacrylamide monomers, onto the fiber surface, and inorganic hydrophilic nanoparticles are doped, enhancing both hydrophilicity and antifouling performance, thus ensuring the long-term stability of the membrane. Attached Figure Description

[0016] Figure 1 Scanning electron microscope image of the polyvinylidene fluoride modified film in Embodiment 1 of the present invention Figure 2 Scanning electron microscope image of the surface of the polyvinylidene fluoride modified film in Embodiment 2 of the present invention Figure 3 Comparison of the retention effect of hexadecane oil-in-water emulsion in Example 3 of this invention Figure 4 Actual image of the casting solution for the polyvinylidene fluoride modified membrane in Embodiment 4 of this invention. Figure 5 Example 3 of this invention compares the polyvinylidene fluoride nanofiber membrane with currently commercially available membranes and laboratory work (serial numbers ①-③ are selected from J. Membr. Sci. 583(2019), 117223, Nanoscale 9, 2017, 7508–7518, Journal of Membrane Science 2023, 679, 121705, respectively. Serial number ④ is the commercial membrane from Maibore, and serial number ⑤ is the membrane from this experiment). Detailed Implementation

[0017] The present invention will be further described below with reference to specific embodiments. Example

[0018] Step 1): Preparation of Feed Solution 1. The substances involved in the preparation of Feed Solution 1 are composed of the following mass composition: 1 g of polyvinylidene fluoride (1015) as the base material, 4.5 g of N,N-dimethylformamide as the solvent, and 0.5 g of thermoplastic polyurethane elastomer. Polyvinylidene fluoride, thermoplastic polyurethane elastomer, and N,N-dimethylformamide are heated and stirred at 80°C until dissolved to form a transparent liquid.

[0019] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass ratios: 0.1 g of N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt, 0.1 g of anhydrous copper chloride, and 4 g of N,N-dimethylformamide as solvent. Dissolve the N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt in N,N-dimethylformamide and add anhydrous copper chloride, stirring until completely dissolved.

[0020] Step 3): Modification and preparation of the fiber membrane: Feed solution one and feed solution two were added to a chip placed under UV light at a flow rate ratio of 2:1 using a microfluidic pump. The two feed solutions mixed in the Y-shaped path chip and underwent UV-induced free radical polymerization modification reaction while flowing within the chip. After the reaction was completed in the chip, a unit volume of reaction solution was driven by the pump to undergo electrospinning in a unidirectional path. The following operating parameters were involved in this process: UV power of 24 W, lamp height of 30 cm, wavelength of 365 nm, and reaction time of 45 min. The spinning flow rate of the feed solution was 0.5 ml / h, the voltage was 20 kV, the humidity during the spinning process was 40%, and the spinning time was 1 h.

[0021] The nanofiber separation membrane has a porosity of 86% and a dry membrane thickness of 25 µm; the pure water flux at 0.1 bar is 5781 L·m⁻¹. -2·h -1 The nanofiber membrane exhibited a hexadecane rejection rate ≥99.45%, a petroleum ether rejection rate ≥99.8%, and a lysine peptide permeation rate of 99.4%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane-oil-in-water emulsion for 90 min, the flux decay rate was 12%. After simple cleaning, the flux recovery rate reached 98%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 93% after four cycles. The surface SEM image of the membrane is shown below. Figure 1 As shown. Example

[0022] Step 1): Preparation of Feed Solution 1. The substances involved in the preparation of Feed Solution 1 are composed of the following mass components: 1.1 g of polyvinylidene fluoride (1015) as the base material, 4.3 g of N,N-dimethylformamide as the solvent, and 0.6 g of thermoplastic polyurethane elastomer. Polyvinylidene fluoride, thermoplastic polyurethane elastomer, and N,N-dimethylformamide are heated and stirred at 70°C until dissolved to form a transparent liquid.

[0023] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass ratios: 0.1 g of N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt, 0.1 g of anhydrous copper chloride, and 4 g of N,N-dimethylformamide as solvent. Dissolve the N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt in N,N-dimethylformamide and add anhydrous copper chloride, stirring until completely dissolved.

[0024] Step 3): Modification and preparation of the fiber membrane: Feed solution one and feed solution two were added to a chip placed under UV light at a flow rate ratio of 1:1 using a microfluidic pump. The two feed solutions mixed in the S-shaped path of the chip and underwent UV-induced free radical polymerization modification reaction while flowing within the chip. After the reaction was completed in the chip, a unit volume of reaction solution was driven by the pump to undergo electrospinning in a crisscross (orthogonal) path. The following operating parameters were involved in this process: UV power of 36 W, lamp height of 40 cm, wavelength of 365 nm, and reaction time of 20 min. The spinning flow rate of the feed solution was 0.6 ml / h, the voltage was 25 kV, the humidity during the spinning process was 50%, and the spinning time was 1.2 h.

[0025] The nanofiber separation membrane has a porosity of 82% and a dry membrane thickness of 55 µm; the pure water flux of the nanofiber separation membrane at 0.1 bar is 6325 L·m. -2 ·h -1The nanofiber membrane exhibited a hexadecane rejection rate ≥99.45%, a petroleum ether rejection rate ≥99.81%, and a lysine peptide permeation rate of 99.18%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane-oil-in-water emulsion for 90 min, the flux decay rate was 20%. After simple cleaning, the flux recovery rate reached 90%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 90% after four cycles. SEM images of the membrane surface are shown below. Figure 2 As shown. Example

[0026] Step 1): Preparation of Feed Solution 1. The substances involved in the preparation of Feed Solution 1 are composed of the following mass composition: 1 g of polyvinylidene fluoride (1015) as the base material, 4.5 g of N,N-dimethylformamide as the solvent, and 0.5 g of thermoplastic polyurethane elastomer. Polyvinylidene fluoride, thermoplastic polyurethane elastomer, and N,N-dimethylformamide are heated and stirred at 80°C until dissolved to form a transparent liquid.

[0027] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass ratios: 0.13 g of N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt, 0.1 g of anhydrous copper chloride, and 4.5 g of N,N-dimethylformamide as solvent. Dissolve the N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt in N,N-dimethylformamide and add anhydrous copper chloride, stirring until completely dissolved.

[0028] Step 3): Modification and preparation of the fiber membrane: Feed solution one and feed solution two were added to a chip placed under UV light at a flow rate ratio of 3:2 using a microfluidic pump. The two feed solutions mixed in the rectangular wavy path of the chip and underwent UV-induced free radical polymerization modification reaction while flowing within the chip. After the reaction was completed in the chip, a unit volume of reaction solution was driven by the pump to undergo electrospinning in an "S" shaped path. The following operating parameters were involved in this process: UV power of 48 W, lamp height of 50 cm, wavelength of 365 nm, and reaction time of 30 min. The spinning flow rate of the feed solution was 0.8 ml / h, the voltage was 40 kV, the humidity during the spinning process was 60%, and the spinning time was 1.3 h.

[0029] The nanofiber separation membrane has a porosity of 90% and a dry membrane thickness of 85 µm; the pure water flux of the nanofiber separation membrane at 0.1 bar is 9937 L·m. -2 ·h -1The nanofiber membrane exhibited a hexadecane rejection rate ≥99.31%, a petroleum ether rejection rate ≥99.01%, and a lysine peptide permeation rate of 99.37%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane oil-in-water emulsion for 90 min, the flux decay rate was 16%. After simple cleaning, the flux recovery rate reached 95%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 90% after four cycles. Figure 3 This is a comparison chart showing the retention effect of hexadecane oil-in-water emulsion in this embodiment. Example

[0030] Step 1): Preparation of Feed Liquid One. The substances involved in the preparation of Feed Liquid One are composed of the following mass composition: 1 g of polyvinylidene fluoride (1001) as the base material, 6 g of N,N-dimethylformamide as the solvent, and 0.6 g of thermoplastic polyurethane elastomer. Polyvinylidene fluoride, thermoplastic polyurethane elastomer, and N,N-dimethylformamide are heated and stirred at 80°C until dissolved to form a transparent liquid.

[0031] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass ratios: 0.067 g of N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt, 0.06 g of anhydrous copper chloride, and 2.4 g of N,N-dimethylformamide as solvent. Dissolve the N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt in N,N-dimethylformamide and add anhydrous copper chloride, stirring until completely dissolved.

[0032] Step 3): Modification and preparation of the fiber membrane: Feed solution one and feed solution two were added to the chip placed under UV light at a flow rate ratio of 3:1 using a microfluidic pump. The two feed solutions mixed in the S-shaped path chip and underwent UV-induced free radical polymerization modification reaction while flowing in the chip. After the reaction was completed in the chip, the unit volume of reaction solution was driven by the pump to undergo electrospinning in a unidirectional path. The following operating parameters were involved in this process: UV power of 36 W, lamp source height of 45 cm, wavelength of 365 nm, and reaction time of 35 min. The spinning flow rate of the feed solution was 0.7 ml / h, the voltage was 40 kV, the humidity during the spinning process was 55%, and the spinning time was 1.5 h.

[0033] The nanofiber separation membrane has a porosity of 92%, a dry membrane thickness of 42 µm, and a dry membrane thickness of 25 µm. The pure water flux of the nanofiber separation membrane at 0.1 bar is 8407 L·m³. -2 ·h -1The nanofiber membrane exhibited a hexadecane rejection rate ≥99.48%, a petroleum ether rejection rate ≥99.05%, and a lysine peptide permeation rate of 99.48%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane oil-in-water emulsion for 90 min, the flux decay rate was 15%. After simple cleaning, the flux recovery rate reached 96%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 90% after four cycles. Figure 4 This is a photograph of the mixture of the two feed liquids for the polyvinylidene fluoride modified membrane in this embodiment. Example

[0034] Step 1): Preparation of Feed Solution 1. The substances involved in the preparation of Feed Solution 1 are composed of the following mass composition: 1 g of polyvinylidene fluoride (1001) as the base material, 5.4 g of N,N-dimethylformamide as the solvent, and 0.6 g of thermoplastic polyurethane elastomer. Polyvinylidene fluoride, thermoplastic polyurethane elastomer, and N,N-dimethylformamide are heated and stirred at 80°C until dissolved to form a transparent liquid.

[0035] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass ratios: 0.16 g of N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt, 0.1 g of anhydrous copper chloride, and 2 g of N,N-dimethylformamide as solvent. Dissolve the N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt in N,N-dimethylformamide and add anhydrous copper chloride, stirring until completely dissolved.

[0036] Step 3): Preparation of feed solution 3. Weigh 0.1 g of nano-sized SiO2 and dissolve it in 1 g of N-N-dimethylformamide.

[0037] Step 4): Modification and preparation of the fiber membrane: Feed solution 1, feed solution 2, and feed solution 3 were added to a chip placed under UV light at a flow rate ratio of 2:1:1 using a microfluidic pump. The three feed solutions mixed in the rectangular wavy path of the chip and underwent grafting modification reaction while flowing within the chip. After the reaction was completed in the chip, a unit volume of reaction solution was driven by the pump to undergo electrospinning in a unidirectional path. The following operating parameters were involved in this process: UV power was 36 W, lamp height was set to 35 cm, wavelength was selected as 365 nm, and reaction time was 35 min. The spinning flow rate of the feed solution was 0.7 ml / h, the voltage was selected as 40 kV, the humidity during the spinning process was 55%, and the spinning time was 1 h.

[0038] The nanofiber separation membrane has a porosity of 91%, a dry membrane thickness of 65 µm, and a pure water flux of 6433 L·m at 0.1 bar. -2 ·h -1 The nanofiber membrane exhibited a hexadecane rejection rate ≥99.14%, a petroleum ether rejection rate ≥99.35%, and a lysine peptide permeation rate of 99.17%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane oil-in-water emulsion for 90 min, the flux decay rate was 17%. After simple cleaning, the flux recovery rate reached 93%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 92% after four cycles. Example

[0039] Step 1): Preparation of Feed Solution 1. The substances involved in the preparation of Feed Solution 1 are composed of the following mass composition: 1 g of polyvinylidene fluoride (1001) as the base material, 4 g of N,N-dimethylformamide as the solvent, and 0.6 g of thermoplastic polyurethane elastomer. Polyvinylidene fluoride, thermoplastic polyurethane elastomer, and N,N-dimethylformamide are heated and stirred at 80°C until dissolved to form a transparent liquid.

[0040] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass ratios: 0.067 g of N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt, 0.06 g of anhydrous copper chloride, and 2.4 g of N,N-dimethylformamide as solvent. Dissolve the N,N-dimethyl-N-methacrylamidopropyl-N,N-dimethyl-N-propanesulfonic acid inner salt in N,N-dimethylformamide and add anhydrous copper chloride, stirring until completely dissolved.

[0041] Step 3): Preparation of feed solution 3. Weigh 0.6 g of nano-sized TiO2 and dissolve it in 2 g of N-N-dimethylformamide.

[0042] Step 4): Modification and preparation of the fiber membrane: Feed solution one, feed solution two, and feed solution three were added to the chip placed under UV light at a flow rate ratio of 3:1:1 using a microfluidic pump. The three solutions mixed and flowed within the chip while undergoing grafting modification. After the reaction was completed in the chip, a unit volume of the reaction solution was driven by the pump to undergo electrospinning in a unidirectional path. The following operating parameters were used in this process: UV power was 36W, wavelength was 365 nm, and reaction time was 35 min. The spinning flow rate of the feed solution was 0.7 ml / h, voltage was 40 kV, humidity was 55%, and spinning time was 2 h.

[0043] The nanofiber separation membrane has a porosity of 94%, a dry membrane thickness of 82 µm, and a pure water flux of 7407 L·m at 0.1 bar. -2 ·h -1 The nanofiber membrane exhibited a hexadecane rejection rate ≥99.48%, a petroleum ether rejection rate ≥99.05%, and a lysine peptide permeation rate of 99.57%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane oil-in-water emulsion for 90 min, the flux decay rate was 15%. After simple cleaning, the flux recovery rate reached 96%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 90% after four cycles. Example

[0044] Step 1): Preparation of Feed Solution 1. The substances involved in the preparation of Feed Solution 1 are composed of the following mass components: 1 g of polyethersulfone as the base material, 4.5 g of N,N-dimethylacetamide as the solvent, and 0.5 g of thermoplastic polyurethane elastomer. The polyethersulfone, thermoplastic polyurethane elastomer, and N,N-dimethylacetamide are heated and stirred at 80°C until dissolved to form a transparent liquid.

[0045] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass: 0.09 g of methacryloylethyl sulfobetaine, 0.09 g of anhydrous copper chloride, and 3 g of N,N dimethylacetamide as solvent. Dissolve methacryloylethyl sulfobetaine in N,N dimethylacetamide and add anhydrous copper chloride, stirring until completely dissolved.

[0046] Step 3): Preparation of feed solution 3. Weigh 0.2 g of nano-sized ZnO and dissolve it in 1 g of N-N-dimethylformamide.

[0047] Step 3): Modification and preparation of the fiber membrane: Feed solution 1, feed solution 2, and feed solution 3 were added to a chip placed under UV light at a flow rate ratio of 3:2:2 using a microfluidic pump. The three feed solutions mixed in the S-shaped path of the chip and underwent grafting modification reaction while flowing within the chip. After the reaction was completed in the chip, a unit volume of the reaction solution was driven by the pump to undergo electrospinning in a unidirectional path. The following operating parameters were involved in this process: UV power of 48 W, lamp source height of 30 cm, wavelength of 365 nm, and reaction time of 30 min. The spinning flow rate of the feed solution was 0.6 ml / h, the voltage was 40 kV, the humidity during the spinning process was 55%, and the spinning time was 1.8 h.

[0048] The nanofiber separation membrane achieved a porosity of 92%, a dry membrane thickness of 34 µm, and a pure water flux of 5492 L·m at 0.1 bar.-2 ·h -1 The nanofiber membrane exhibited a hexadecane rejection rate ≥99.02%, a petroleum ether rejection rate ≥99.33%, and a lysine peptide permeation rate of 99.52%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane oil-in-water emulsion for 90 min, the flux decay rate was 16%. After simple cleaning, the flux recovery rate reached 90%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 88% after four cycles. Example

[0049] Step 1): Preparation of Feed Solution 1. The substances involved in the preparation of Feed Solution 1 are composed of the following mass composition: 1 g of polyacrylonitrile as the base material, 4 g of N-methylpyrrolidone as the solvent, and 0.5 g of thermoplastic polyurethane elastomer. The polyacrylonitrile, thermoplastic polyurethane elastomer, and N-methylpyrrolidone are heated and stirred at 70°C until dissolved to form a transparent liquid.

[0050] Step 2): Preparation of Feed Solution II. The substances involved in the preparation of Feed Solution II are prepared according to the following mass ratios: 0.13 g of betaine sulfonate methacrylate, 0.1 g of anhydrous copper chloride, and 4.5 g of N-methylpyrrolidone as solvent. Dissolve betaine sulfonate methacrylate in N-methylpyrrolidone and add anhydrous copper chloride, stirring until completely dissolved.

[0051] Step 3): Modification and preparation of the fiber membrane: Feed solution one and feed solution two were added to a chip placed under UV light at a certain flow rate ratio using a microfluidic pump. The two solutions mixed within the chip and underwent UV-induced free radical polymerization modification while flowing through the chip. After the reaction was completed in the chip, a unit volume of the reaction solution was driven by the pump to undergo electrospinning in a unidirectional path. The following operating parameters were involved in this process: UV power was 48 W, wavelength was 365 nm, and reaction time was 30 min. The spinning flow rate of the feed solution was 0.6 ml / h, voltage was 40 kV, humidity during spinning was 55%, and spinning time was 1 h.

[0052] The nanofiber separation membrane has a porosity of 94%, a dry membrane thickness of 100 µm, and a pure water flux of 7368 L·m at 0.1 bar. -2 ·h -1The nanofiber membrane exhibited a hexadecane rejection rate ≥99.06%, a petroleum ether rejection rate ≥99.53%, and a lysine peptide permeation rate of 99.73%. When the prepared nanofiber membrane was run in a 5 g / L hexadecane oil-in-water emulsion for 90 min, the flux decay rate was 20%. After simple cleaning, the flux recovery rate reached 86%. In an antifouling test conducted in a 0.1 g / L LBSA solution, the flux recovery rate reached 85% after four cycles.

Claims

1. A method for preparing a high-throughput, anti-fouling nanofiber separation membrane using microfluidic coupling grafting modification technology, characterized in that, Includes the following steps: Preparation of high-flux anti-fouling nanofiber separation membrane: Multiple feed streams are added to a chip placed under ultraviolet light at a certain flow rate ratio using a microfluidic pump of a microfluidic device. The multiple feed streams mix and react in the chip. After the reaction is completed, the reaction liquid per unit volume is driven by the pump to perform microfluidic spinning according to the set path and flow rate. The voltage and humidity are adjusted according to objective conditions to ensure the stability of the spinning process. (1) Preparation of feed liquid one: The substances involved in the preparation of feed liquid one are composed of the following mass percentages: 10-20% substrate, 70-85% solvent, and 5-10% thermoplastic polyurethane elastomer; the substrate, thermoplastic polyurethane elastomer and solvent are heated and stirred at 60-80°C and mixed and dissolved to form a transparent liquid. (2) Preparation of feed liquid II: Feed liquid II is prepared by the following components in mass percentage: 0.5-1% sulfonate betaine methacrylamide monomer, 0.5-1% anhydrous copper chloride, and the remainder is solvent; dissolve the sulfonate betaine methacrylamide monomer in the solvent and add anhydrous copper chloride and stir until completely dissolved; (3) Preparation of feed solution three: feed solution three is prepared by dissolving inorganic nanoparticles in a solvent, wherein the mass fraction of inorganic nanoparticles is 0%-1%; (4) Selection of feed rate ratio: The feed rate ratio of feed liquid one, feed liquid two and feed liquid three can be selected in the range of 1:1:1 to 3:1:3; (5) Path selection of microfluidic confined channel chip: The chip paths involved in the microfluidic confined channel enhanced grafting reaction include S-type, Y-type, and rectangular wave-shaped. The path selection is performed after feeding and mixing through multiple feed ports. (6) Setting of spinning / spraying process path: grid path, S-shaped path, spiral path, can be selected according to actual needs.

2. The preparation method according to claim 1, characterized in that: The substrate is one of polyvinylidene fluoride 1001, polyvinylidene fluoride 1015, polyethersulfone, and polyacrylonitrile.

3. The preparation method according to claim 1, characterized in that: Preparation of feed liquid one: The solvent is one of N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylacetamide.

4. The preparation method according to claim 1, characterized in that: Preparation of feed solution II: The sulfonate betaine and methacrylamide monomers are one of the following: methacryloyl ethyl sulfonate betaine, sulfonate betaine methacrylate, methacrylamide, and N,N-dimethyl-N-methacrylamidopropyl-N-propane sulfonate inner salt.

5. The preparation method according to claim 1, characterized in that: Preparation of feed liquid three: Inorganic nanoparticles can be selected from hydrophilic nano-sized silica, hydrophilic nano-sized titanium dioxide, and nano-sized zinc oxide.

6. The preparation method according to claim 1, characterized in that: The UV power was selected between 24 W and 48 W, the wavelength was selected as 365 nm, the lamp source height was 20-50 cm, and the reaction time was 20-45 min; the spinning flow rate after the reaction was 0.5-0.8 ml / h, the voltage was selected as 16-20 kV; the spinning time was 1-2 h, and the film thickness was 25-100 μm.

7. The preparation method according to claim 1, characterized in that: The humidity during the spinning process for preparing fiber membranes is between 40% and 60%, and can be adjusted according to the objective environmental conditions to ensure the smooth spinning process.

8. The antifouling high-flux nanofiber separation membrane prepared by the preparation method according to any one of claims 1-6, characterized in that, First, the microfluidic confined channels enhance the grafting reaction, allowing for a more complete reaction within the micro-element and significantly increasing the grafting rate of hydrophilic substances onto the membrane fibers, reaching up to 60%. Second, the fiber membrane exhibits a pure water flux of 6000-10000 L·m⁻² at 0.1 bar pressure. -2 ·h -1 The hexadecane water-in-oil emulsion has a hexadecane rejection rate of ≥99%, the petroleum ether water-in-oil emulsion has a petroleum ether rejection rate of ≥99%, the permeability of lysine peptides reaches 99%, and it has good antifouling properties and flux recovery rate, with a flux recovery rate of ≥90%.

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