A method for preparing and using a self-assembled ordered fiber network separation membrane

Abstract

This invention belongs to the field of water filtration materials technology, and relates to a method for preparing and applying a self-assembled ordered fiber network separation membrane. A water-soluble polymer is dissolved in water to form a sludge-like material. Then, an amine-based aqueous monomer dispersion is gradually incorporated into the sludge to obtain an aqueous solution. A polyacrylamide chloride is dissolved in an organic solvent to obtain an oil solution. The aqueous and oil solutions are separately injected into a dual-system fractal channel supply device. The spin-coating sequence, support rotation speed, and scraper height of the aqueous and oil solutions are controlled to regulate the thickness of the aqueous and oil phase films. Finally, the aqueous and oil monomers undergo interfacial polymerization, self-assembling to form an ordered fiber network separation membrane. The separation membrane of this invention has a fiber diameter of 50-500 nm, a separation efficiency of ≥90% for heavy metal ions, and a mass transfer flux of ≥30 L / (m²). 2 ·h) has great application potential in the field of liquid filtration and separation.

Description

Technical Field

[0001] This invention belongs to the field of water filtration materials technology, and relates to a method for preparing and applying a self-assembled ordered fiber network separation membrane. Background Technology

[0002] With the development of industrialization, the effective utilization of resources and the achievement of environmental protection have become key global challenges. Filtration separation is a crucial technology for the purification and recovery of substances, playing a vital role in energy, chemical industry, environmental protection, and many other fields. Filtration separation technology achieves selective retention or permeation of specific components in a mixture by rationally designing and optimizing the structure of the filter media. Membrane separation technology can effectively remove substances including surfactants, heavy metals, microorganisms, salts, and organic pollutants, and has been widely researched and applied in my country in recent years. Currently, most commercially available separation membranes are polyamide membranes. Although these membranes have wide applications, there is a trade-off between permeability and selectivity, making it difficult to simultaneously achieve high throughput and high filtration efficiency, thus limiting their application in the field of high-efficiency filtration separation.

[0003] To synergistically improve the performance of polyamide separation membranes, researchers often employ strategies such as surface modification, matrix mixing, and solution design to control the membrane's chemical properties or physical morphology. Patent ZL202210733225.2 describes a method that loads HA-CD polymers onto the base membrane surface, allowing PIP molecules to diffuse uniformly on the base membrane surface while slowing their diffusion rate into the oil phase. Subsequent interfacial polymerization with a polyacrylamide chloride oil phase solution yields a polyamide composite nanofiltration membrane with a negatively charged surface and uniform pore size, achieving a filtration efficiency of over 90%, but with a relatively low mass transfer flux. Patent ZL202311604790.X utilizes porous two-dimensional nanosheets with active reactive sites as an interlayer material. This layer is deposited onto the ultrafiltration membrane surface via pressure-assisted filtration to obtain a porous and reactive interlayer. Interfacial polymerization is then performed on this interlayer to prepare the separation membrane. However, this process suffers from significant thickness variations in the final separation membrane due to the uneven thickness of the water-oil two-phase solution, limiting its practical application efficiency. Patent CN202510806741.7 describes a method that involves adding piperazine, an acidic absorbent, and modified nanomaterials to deionized water to prepare an aqueous solution, then mixing trimesoyl chloride and n-hexane to form an organic solution. This solution is subsequently subjected to interfacial polymerization on a polyethersulfone-based membrane to generate a polyamide layer, resulting in a composite membrane. However, this method suffers from difficulties in precisely controlling the diffusion rate of aqueous monomers due to uneven distribution of hydrophilic macromolecules, and the critical conditions for Turing structure formation remain unclear. To synergistically improve membrane performance, studies have employed monomer design, surface modification, and mixed matrices to regulate the chemical properties or physical morphology of the membrane, aiming to obtain polyamide membranes with higher performance. Patent ZL201810120316.2 obtained a polyamide membrane with a Turing structure by adding hydrophilic macromolecules to the aqueous solution of interfacial polymerization to reduce the diffusion coefficient of the aqueous monomers. Its water permeability is 3 to 6 times higher than that of traditional polyamide membranes. However, the uneven distribution of its hydrophilic macromolecules in the solution makes it impossible to precisely control the diffusion rate of the aqueous monomers, and the critical conditions for the formation of the Turing structure are difficult to define. Patent ZL201810868127.3 introduced a microporous material dispersion onto a porous support layer to form an intermediate layer, and then carried out interfacial polymerization to prepare a nanofiltration membrane. The pore structure of the intermediate layer was used to control the migration rate of the aqueous monomers, which significantly improved the water permeability of the nanofiltration membrane. Patent ZL202010684455.5 uses aromatic polyamine monomers, aldehydes, and dicarbonyl compounds as reactants to form imidazole nanoparticles through condensation polymerization in an acidic aqueous solution. Dopamine is then added to the alkaline aqueous dispersion, and polydopamine-modified imidazole nanoparticles are obtained through oxidative polymerization. Finally, a composite nanofiltration membrane is prepared on a porous ultrafiltration membrane by surface coating-interfacial crosslinking. However, the uneven thickness of the water-oil two-phase solution leads to a large difference in the thickness of the separation membrane after interfacial polymerization, which limits its efficiency in practical applications.

[0004] In summary, existing interfacial polymerization separation membrane technologies still generally suffer from problems such as difficulty in precisely controlling the diffusion rate of aqueous monomers and uneven distribution of liquid membrane thickness in the water / oil two-phase systems. Ultimately, this leads to poor membrane thickness consistency and difficulty in controlling the fiber network structure, making it difficult to simultaneously achieve synergistic optimization of high throughput and high retention efficiency. This presents a significant bottleneck in the efficient separation of pollutants such as heavy metal ions. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a method for preparing and applying a self-assembled ordered fiber network separation membrane.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a self-assembled ordered fiber network separation membrane includes the following steps: S1. Dissolve amine monomers in water to obtain an aqueous monomer dispersion; S2. Add the water-soluble polymer to water and stir to pre-swell the polymer to form a mud-like substance. Then, slowly and gradually incorporate the aqueous monomer dispersion obtained in step S1 into the mud-like substance and continue stirring to diffuse the monomer into the polymer molecular chains to obtain an aqueous solution. S3. Dissolve the polyacryl chloride monomer in an organic solvent to obtain an oil phase solution; S4. Using a dual-system fractal flow channel liquid supply device, the aqueous phase solution obtained in step S2 and the oil phase solution obtained in step S3 are coated on the surface of the support membrane in a set order, so that the amine monomer and the polyacryl chloride monomer undergo a polymerization reaction at the interface, forming an ordered fiber network on the surface of the support membrane, thereby producing a separation membrane with the support membrane as the substrate and the ordered fiber network as the functional layer. S5. After drying, cleaning and baking the separation membrane obtained in step S4, a self-assembled ordered fiber network separation membrane is obtained.

[0007] Further, the amine monomer is selected from one or more of ethylenediamine, hexamethylenediamine, piperazine, m-phenylenediamine, p-phenylenediamine, polyethyleneimine, diethyltriamine, benzidine, 1,4-cyclohexanediamine, methylcyclohexanediamine, tetradecylamine, 1,11-undecanediamine, 1,7-heptanediamine, or 1,4-butanediamine; Preferably, the amine monomer is selected from one or more of ethylenediamine, hexamethylenediamine, piperazine, m-phenylenediamine, p-phenylenediamine, polyethyleneimine, diethyltriamine, methylcyclohexanediamine, and 1,4-cyclohexanediamine; The water-soluble polymer is selected from one or more of the following: polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, starch, polyethylene glycol, polypropylene glycol, polymaleic anhydride, polyacrylic acid, polymethacrylic acid, alginate, polyethylene oxide-propylene oxide copolymer, polyether-amide block copolymer, sodium carboxymethyl cellulose, gelatin, hydroxypropyl methylcellulose, or polyethylene glycol diacrylate. Preferably, the water-soluble polymer is selected from one or more of polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, and polyacrylamide; The polyacryl chloride is selected from one or more of the following: pyromellitic trichloroisocyanurate, 3,4',5-biphenyltrichloroisocyanurate, 3,3',5,5'-biphenyltetrachloroisocyanurate, isophthaloyl chloride, terephthaloyl chloride, phthaloyl chloride, 5-isocyanate isophthaloyl chloride, 3,5-dichloroformylphenylphosphonochloroisocyanurate, malonyl chloride, succinic acid chloride, glutaryl chloride, adipyl chloride, glutaryl chloride, naphthalene dichloroisocyanurate, p-dicarboxyl chloride diphenoxyethanebutane or 4,4'-diphenyl ether diacryl chloride; Preferably, the polyacryl chloride is selected from one or more of pyromellitic triacryl chloride, 3,4',5-biphenyltriacryl chloride, 4,4'-diphenyl ether diacryl chloride, isophthaloyl chloride, terephthaloyl chloride, phthaloyl chloride, and 5-isocyanate isophthaloyl chloride; The organic solvent is selected from one or more of the following: n-hexane, cyclohexane, n-heptane, isooctane, n-dodecane, cyclopentane, methylcyclohexane, petroleum ether, toluene, xylene, carbon tetrachloride, chloroform, dichloromethane, tert-amyl methyl ether, and o-dichlorobenzene.

[0008] Further, in step S1, the concentration of amine monomers in the aqueous monomer dispersion is 0.1~10wt%. In step S2, the concentration of water-soluble polymer in the sludge is 10-50 wt%; the gradient-incorporated aqueous monomer dispersion is added to the sludge in three batches, with a mass ratio of 2:3:5, and the mixture is stirred vigorously for 1-5 minutes after each addition; the content of sludge in the aqueous solution is 0.05-1 wt%. In step S3, the concentration of polyacrylamide chloride monomer in the oil phase solution is 0.01~5wt%.

[0009] Further, in step S4, the supporting membrane includes a fiber membrane, a phase separation membrane, a stretched membrane, or a particle sintered membrane; the pore size of the supporting membrane is 0.5~5μm, the porosity is ≥70%, and the thickness is 10~50μm; The material of the support membrane is selected from one or more of polyurethane, polyamide, polyvinylidene fluoride, polyethersulfone, polypropylene, polytetrafluoroethylene, high-density polyethylene, alumina, zirconium oxide, titanium oxide, silicon oxide, and silicon carbide.

[0010] Furthermore, in step S4, the dual-system fractal flow channel liquid supply device includes a dual-system fractal flow channel and a variable height swirl scraper unit; The dual-system fractal flow channel includes two independent and symmetrically distributed microchannel arrays, namely a first microchannel array and a second microchannel array, and a first inlet and a second inlet respectively connected to the two; the first inlet is used to introduce an aqueous phase solution and is connected to the first microchannel array; the second inlet is used to introduce an oil phase solution and is connected to the second microchannel array; the two sets of microchannel arrays are used to accurately transport the aqueous phase solution and the oil phase solution respectively, ensuring that the two-phase solutions do not interfere with each other during the transport process.

[0011] The variable height rotary scraping unit includes a lifting assembly and a collecting assembly; wherein, the lifting assembly includes a lifting rod that is vertically and vertically disposed between two microchannel arrays and a scraper fixedly connected to the lower end of the lifting rod, and also includes a first drive motor for driving the lifting rod to perform lifting and lowering movements, and controlling the liquid film thickness by adjusting the height of the scraper; The collection assembly includes a rotating support disposed directly below the microchannel array, and a support membrane fixed to the upper surface of the rotating support. The support membrane is used to receive the two-phase solution and serve as a film-forming substrate.

[0012] Furthermore, the variable height scraping unit also includes a rotary drive assembly; wherein the rotary drive assembly includes a rotary shaft fixedly connected to the center of the bottom of the rotary support, a transmission rod pulverizedly connected to the rotary shaft, and a second drive motor for driving the transmission rod to drive the rotary support and the support film to rotate synchronously.

[0013] The specific operation process is as follows: the aqueous solution obtained in step S2 and the oil solution obtained in step S3 are injected into the first inlet and the second inlet, respectively, and stably transported to the support membrane through the microchannel array; by controlling the spin-coating order of the aqueous solution and the oil solution, the rotation speed of the rotating support, and the height of the scraper, the thickness of the aqueous and oil phase liquid films can be precisely controlled, forming a position-controllable biphase interface layer on the surface of the support membrane; after the interfacial polymerization reaction has been carried out for a period of time, an ordered fiber network is formed on the surface of the support membrane, thereby producing a separation membrane with the support membrane as the substrate and the ordered fiber network as the functional layer; after drying, cleaning, and baking the separation membrane, an ordered fiber network separation membrane is obtained.

[0014] Furthermore, the rotation speed of the rotating bracket is 1~20 rpm; the height of the scraper refers to the vertical distance between its bottom and the upper surface of the support membrane, and the adjustment range is 0.5~5 mm.

[0015] Furthermore, the microchannel array has a main channel and sub-channels; the diameter of the main channel is 10~20mm; and the diameter of the sub-channels is 2~8mm.

[0016] Furthermore, in step S4, the coating sequence is either aqueous solution first followed by oil solution or oil solution first followed by aqueous solution.

[0017] This invention also provides a self-assembled ordered fiber network separation membrane prepared by the method described in any of the preceding claims. The self-assembled ordered fiber network separation membrane has fibers with a diameter of 50-500 nm and a pore size of 10 nm-100 nm, exhibiting a separation efficiency of ≥90% for heavy metal ions and a mass transfer flux of ≥30 L / (m²). 2 ·h).

[0018] The present invention also provides an application of the self-assembled ordered fiber network separation membrane prepared by the method described in any of the preceding claims, wherein the self-assembled ordered fiber network separation membrane is applied in the field of water treatment.

[0019] Specifically, the self-assembled ordered fiber network separation membrane achieves the filtration and separation of heavy metal ions through the ordered fiber network and small pore size.

[0020] The technical principle of this invention is as follows: an aqueous solution with adjustable monomer diffusion rate is prepared by using a "polymer mud-state pre-swelling-aqueous monomer gradient blending" process; then, the aqueous solution and oil solution are spin-coated on the surface of the support membrane, and an ordered fiber network separation membrane is formed through an interfacial polymerization-self-assembly process. The specific implementation process is as follows: First, a quantitative amount of water-soluble polymer is dissolved in water for pre-swelling to form a uniform sludge. Then, an aqueous monomer dispersion is slowly added to the sludge to allow the aqueous monomers to be gradually incorporated into the sludge. By changing the type and content of the water-soluble polymer and the amount of aqueous monomer added at one time, and by vigorously stirring for 1 to 5 minutes after each addition, the aggregation phenomenon caused by excessively high local concentrations is avoided, and the monomer molecules are promoted to gradually penetrate into the three-dimensional network structure of the water-soluble polymer, thereby achieving a uniform spatial distribution and finally obtaining an aqueous solution with uniformly dispersed aqueous monomers. At the same time, a quantitative amount of polyacrylamide chloride is dissolved in an organic solvent to obtain an oil phase solution. Subsequently, the aqueous solution and the oil phase solution are injected into a dual-system fractal flow channel liquid supply device, respectively. By changing the parameters such as the swirl speed and scraper height of the variable height swirl unit, the thickness of the aqueous liquid film and the oil liquid film are differentially controlled, thereby adjusting the mass transfer rate and reaction intensity at the interface between the two phases. Finally, the aqueous monomer and the oil monomer come into contact and undergo interfacial polymerization, forming a uniformly thick ordered fiber network separation membrane through solution polymerization and self-assembly.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The water-soluble polymer sludge-state pre-swelling-aqueous monomer gradient blending technology of the present invention is as follows: the water-soluble polymer is dissolved in water and stirred at high speed to pre-swell the polymer to form a sludge-state material, which forms a dense molecular entanglement network inside. By gradient blending of aqueous monomers, they can gradually penetrate into the gaps between polymer chains under shear force to form a spatially confined uniform dispersion system, effectively delaying the free diffusion rate of aqueous monomers to the oil phase, realizing precise control of the reaction rate in the early stage of interfacial polymerization, avoiding uneven thickness and fiber network structure caused by abrupt film formation, and helping to form an ordered fiber network.

[0022] 2. The dual-system fractal flow channel liquid supply device of the present invention delivers aqueous and oil phase solutions through a microchannel array. The total flow rate is dispersed, reducing the fluid velocity and Reynolds number within the sub-channels, thus maintaining a stable laminar flow state, suppressing flow instability and disturbances, and ensuring uniform distribution of fluid flow rate and velocity at the sub-channel inlets, achieving uniform and stable liquid supply of the two-phase solution. By changing the scraping speed and scraper height of the variable height scraping unit, differentiated control of the thickness of the aqueous and oil phase liquid films can be achieved. At the instant of contact between the two-phase liquid films, amine monomers slowly diffuse from the aqueous phase to the oil phase interface, undergoing a condensation reaction with polyacrylamide monomers to generate polyamide primary chains. Due to the confinement and regulation of the diffusion of aqueous monomers by the polymer network, the reaction rate is stable, ultimately self-assembling to form an ordered fiber network separation membrane with a fiber diameter of 50~500nm and a pore size of 10~100nm, enabling highly efficient separation of heavy metal ions, with a separation efficiency of ≥90% and a mass transfer flux of ≥30L / (m²). 2 ·h). Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the dual-system fractal flow channel liquid supply device according to an embodiment of the present invention; The numbers in the diagram are as follows: 1-First microchannel array, 2-Second microchannel array, 3-First inlet, 4-Second inlet, 5-Lifting rod, 6-Scraper, 7-First drive motor, 8-Rotating bracket, 9-Supporting membrane, 10-Rotating shaft, 11-Transmission rod, 12-Second drive motor, 13-Main channel, 14-Sub-channel; Figure 2 This is a scanning electron microscope image of the self-assembled ordered fiber network separation membrane prepared in Example 2 of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0025] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available products.

[0026] The dual-system fractal flow channel liquid supply device used in various embodiments of the present invention includes a dual-system fractal flow channel and a variable height swirl scraper unit; The dual-system fractal flow channel includes a first microchannel array 1 and a second microchannel array 2 that are independent and symmetrically distributed, and a first inlet 3 and a second inlet 4 that are respectively connected to the two. The first inlet 3 is used to introduce an aqueous solution and is connected to the first microchannel array 1. The second inlet 4 is used to introduce an oil solution and is connected to the second microchannel array 2. The two sets of microchannel arrays are used to accurately transport the aqueous solution and the oil solution respectively, ensuring that the two-phase solutions do not interfere with each other during the transport process. The main channel diameter in the microchannel array is 10~20mm, and the sub-channel diameter is 2~8mm; The variable height rotary scraper unit includes a lifting assembly, a collecting assembly, and a rotation drive assembly; The lifting assembly includes a lifting rod 5 that is vertically disposed in the middle of the dual-system fractal flow channel, a scraper 6 fixedly connected to the lower end of the lifting rod 5, and a first drive motor 7 for driving the lifting rod 5 to move up and down. The thickness of the liquid film is controlled by adjusting the height of the scraper 6. The height of the scraper 6 refers to the vertical distance between its bottom and the upper surface of the support film, and the adjustment range is 0.5~5mm. The collection assembly includes a rotating support 8 disposed directly below the biphase fractal channel, and a support membrane 9 fixed to the upper surface of the rotating support 8. The support membrane 9 is used to receive the biphase solution and serve as a film-forming substrate. The rotation drive assembly includes a rotation shaft 10 connected to the lower end of the rotation bracket 8, a transmission rod 11 connected to the rotation shaft 10, and a second drive motor 12 for driving the transmission rod 11 to drive the rotation bracket 8 and the support membrane 9 to rotate synchronously; the rotation speed of the rotation bracket 8 is 1~20 rpm.

[0027] The specific operation process is as follows: The support membrane 9 is flattened and fixed on the upper surface of the rotating bracket 8. The height of the lifting rod 5 is adjusted by the first drive motor 7, and the scraper 6 is adjusted to the target height of 0.5~5mm; the target rotation speed of the rotating bracket 8 is set to 1~20rpm by the second drive motor 12. The rotating bracket 8 drives the support membrane 9 to rotate at the set speed. The aqueous phase solution and the oil phase solution are injected from the first inlet 3 and the second inlet 4, respectively, and are stably transported to the top of the support membrane 9 through the main channels and sub-channels of the first microchannel array 1 and the second microchannel array 2, respectively; by controlling the spin coating order of the aqueous phase solution and the oil phase solution, the rotation speed of the rotating bracket 8, and the height of the scraper 6, the thickness of the aqueous phase and oil phase liquid films can be precisely controlled, forming a position-controllable biphase interface layer on the surface of the support membrane 9; after the interface polymerization reaction has been carried out for a period of time, an ordered fiber network is formed on the surface of the support membrane 9, thereby producing a separation membrane with the support membrane 9 as the substrate and the ordered fiber network as the functional layer; after drying, cleaning and baking treatment, the ordered fiber network separation membrane is obtained.

[0028] Example 1 A self-assembled ordered fiber network separation membrane is prepared by the following steps: S1. Dissolve piperazine in deionized water and stir continuously for 1 hour to obtain a piperazine dispersion, wherein the piperazine content in the dispersion is 0.1 wt%. S2. Dissolve polyvinyl alcohol in deionized water and stir vigorously for 3 hours to allow the polyvinyl alcohol to fully swell and form a mud-like substance with a polyvinyl alcohol content of 50 wt%. Then, add the piperazine dispersion obtained in step S1 to the mud-like substance in three portions with a mass ratio of 2:3:5. The mud-like substance content in the aqueous solution is 1 wt%. After mixing evenly, an aqueous solution in which polyvinyl alcohol and piperazine are uniformly dispersed is obtained. S3. Dissolve trimesoyl chloride in n-hexane and stir continuously for 2 hours to obtain an oil phase solution, wherein the content of trimesoyl chloride is 5 wt%. S4. Select a polyurethane fiber membrane with an average pore size of 1μm, a porosity of 90%, and a thickness of 50μm, and fix it on the rotating support 8 of the dual-system fractal flow channel liquid supply device to ensure that the polyurethane fiber membrane and the rotating support 8 have no relative displacement and are fully spread. S5. Adjust the height of the lifting rod of the dual-system fractal flow channel liquid supply device to 3mm, and control the rotation speed of the rotating support 8 to 1rpm; inject the aqueous solution obtained in step S2 into the first microchannel array 1 through the first inlet 3, and transport it to the drip port through its main channel (diameter 20mm) and sub-channel (diameter 8mm), so that the solution is stably dripped onto the surface of the polyurethane fiber membrane to form an aqueous liquid film; then inject the oil phase solution obtained in step S3 into the second microchannel array 2 through the second inlet 4, and transport it to the drip port through its main channel (diameter 20mm) and sub-channel (diameter 8mm), so that the solution is stably dripped onto the surface of the aqueous liquid film to form an oil liquid film; control the thickness ratio of the aqueous liquid film to the oil liquid film to be 1:1, and the total thickness of the overall liquid film to be 6μm; after standing for 60s, a separation membrane with a polyurethane fiber membrane as the substrate and an ordered fiber network as the functional layer can be prepared; S6. The separation membrane obtained in step S5 is dried at 40°C for 5 minutes, then rinsed with deionized water for 5 minutes to completely remove unreacted monomers and residual solvents, and then dried at 60°C for 10 minutes to finally obtain a self-assembled ordered fiber network separation membrane with a fiber diameter of 500 nm and an average pore size of 10 nm.

[0029] The self-assembled ordered fiber network separation membrane obtained in step S6 was fixed on a dead-end filter device. Following standard GB / T 32360-2015, a filtration test was conducted on wastewater containing 2 mg / L of heavy metal ions at a pressure of 0.1 MPa. The concentration of heavy metal ions in the filtered water sample decreased to 0.2 mg / L. The separation efficiency of the self-assembled ordered fiber network separation membrane for heavy metal ions was 90%, and the mass transfer flux was 53 L / (m²). 2 ·h).

[0030] Example 2 A self-assembled ordered fiber network separation membrane is prepared by the following steps: S1. Dissolve piperazine in deionized water and stir continuously for 2 hours to obtain a piperazine dispersion, wherein the piperazine content in the dispersion is 1 wt%. S2. Dissolve polyvinyl alcohol in deionized water and stir vigorously for 5 hours to allow the polyvinyl alcohol to fully swell and form a mud-like substance with a polyvinyl alcohol content of 50 wt%. Then, add the piperazine dispersion obtained in step S1 to the mud-like substance in three portions with a mass ratio of 2:3:5. The mud-like substance content in the aqueous solution is 1 wt%. After mixing evenly, an aqueous solution in which polyvinyl alcohol and piperazine are uniformly dispersed is obtained. S3. Dissolve trimesoyl chloride in n-hexane and stir continuously for 2 hours to obtain an oil phase solution, wherein the content of trimesoyl chloride is 3 wt%. S4. Select a polyurethane fiber membrane with an average pore size of 2μm, a porosity of 70%, and a thickness of 50μm, and fix it on the rotating support 8 of the dual-system fractal flow channel liquid supply device to ensure that the polyurethane fiber membrane and the rotating support 8 have no relative displacement and are fully spread. S5. Adjust the height of the lifting rod of the dual-system fractal flow channel liquid supply device to 2.5mm, and control the rotation speed of the rotating support 8 to 5rpm; inject the aqueous solution obtained in step S2 into the first microchannel array 1 through the first inlet 3, and transport it to the drip port through its main channel (diameter 20mm) and sub-channel (diameter 8mm), so that the solution is stably dripped onto the surface of the polyurethane fiber membrane to form an aqueous liquid film; then inject the oil phase solution obtained in step S3 into the second microchannel array 2 through the second inlet 4, and transport it to the drip port through its main channel (diameter 20mm) and sub-channel (diameter 8mm), so that the solution is stably dripped onto the surface of the aqueous liquid film to form an oil liquid film; control the thickness ratio of the aqueous liquid film to the oil liquid film to be 2:1, and the total thickness of the overall liquid film to be 6μm; after standing for 60s, a separation membrane with a polyurethane fiber membrane as the substrate and an ordered fiber network as the functional layer can be prepared; S6. The separation membrane obtained in step S5 is dried at 40°C for 5 minutes, then rinsed with deionized water for 5 minutes to thoroughly remove unreacted monomers and residual solvents. It is then dried at 60°C for 10 minutes to obtain a separation membrane with a fiber network structure. The average fiber diameter is 420 nm, and the average pore size is 7.3 nm. The electron micrograph is shown below. Figure 2 As shown.

[0031] The self-assembled ordered fiber network separation membrane obtained in step S6 was fixed on a dead-end filter device, and a filtration test was conducted on wastewater containing 2 mg / L of heavy metal ions under a pressure of 0.1 MPa. The concentration of heavy metal ions in the filtered water sample decreased to 0.18 mg / L. The separation efficiency of the self-assembled ordered fiber network separation membrane for heavy metal ions was 91%, and the mass transfer flux was 45 L / (m²). 2 ·h).

[0032] Example 3 A self-assembled ordered fiber network separation membrane is prepared by the following steps: S1. Dissolve piperazine in deionized water and stir continuously for 2 hours to obtain a piperazine dispersion, wherein the piperazine content in the dispersion is 3 wt%. S2. Dissolve polyvinyl alcohol in deionized water and stir vigorously for 5 hours to allow the polyvinyl alcohol to fully swell and form a mud-like substance with a polyvinyl alcohol content of 30 wt%. Then, add the piperazine dispersion obtained in step S1 to the mud-like substance in three portions at a mass ratio of 2:3:5. The mud-like substance content in the aqueous solution is 0.5 wt%. After mixing evenly, a uniformly dispersed aqueous solution of polyvinyl alcohol and piperazine is obtained. S3. Dissolve trimesoyl chloride in n-hexane and stir continuously for 2 hours to obtain an oil phase solution, wherein the content of trimesoyl chloride is 1 wt%. S4. Select a polyamide phase separation membrane with an average pore size of 1μm, a porosity of 70%, and a thickness of 10μm, and fix it on the rotating support 8 of the dual-system fractal flow channel liquid supply device to ensure that the polyamide phase separation membrane and the rotating support 8 have no relative displacement and are fully spread. S5. Adjust the height of the lifting rod of the dual-system fractal flow channel liquid supply device to 2mm, and control the rotation speed of the rotating support 8 to 1rpm; inject the aqueous phase solution obtained in step S2 into the first microchannel array 1 through the first inlet 3, and transport it to the drip port through its main channel (diameter 15mm) and sub-channel (diameter 5mm), so that the solution is stably dripped onto the surface of the polyurethane fiber membrane to form an aqueous phase liquid film; then inject the oil phase solution obtained in step S3 into the second microchannel array 2 through the second inlet 4, and transport it to the drip port through its main channel (diameter 15mm) and sub-channel (diameter 5mm), so that the solution is stably dripped onto the surface of the aqueous phase liquid film to form an oil phase liquid film; control the thickness ratio of the aqueous phase liquid film to the oil phase liquid film to be 1:1, and the total thickness of the overall liquid film to be 6μm; after standing for 60s, a separation membrane with a polyamide phase separation membrane as the substrate and an ordered fiber network as the functional layer can be prepared; S6. The separation membrane obtained in step S5 is dried at 40°C for 5 minutes, then rinsed with deionized water for 5 minutes to completely remove unreacted monomers and residual solvents, and then dried at 60°C for 10 minutes to obtain a self-assembled ordered fiber network separation membrane with an average fiber diameter of 300 nm and an average pore size of 5.4 nm.

[0033] The self-assembled ordered fiber network separation membrane obtained in step S6 was fixed on a dead-end filter device, and a filtration test was conducted on wastewater containing 2 mg / L of heavy metal ions under a pressure of 0.1 MPa. The concentration of heavy metal ions in the filtered water sample decreased to 0.12 mg / L. The separation efficiency of the self-assembled ordered fiber network separation membrane for heavy metal ions was 94%, and the mass transfer flux was 43 L / (m²). 2 ·h).

[0034] Example 4 A self-assembled ordered fiber network separation membrane is prepared by the following steps: S1. Hexamethylenediamine is dissolved in deionized water and stirred continuously for 2 hours to obtain a hexamethylenediamine dispersion, wherein the content of hexamethylenediamine in the dispersion is 5 wt%. S2. Dissolve polyethylene oxide in deionized water and stir vigorously for 5 hours to allow the polyethylene oxide to fully swell and form a sludge-like substance. The polyethylene oxide content in the sludge-like substance is 30 wt%. Then, add the hexamethylenediamine dispersion obtained in step S1 to the sludge-like substance in three portions at a mass ratio of 2:3:5. The sludge-like substance content in the aqueous solution is 0.5 wt%. After mixing evenly, an aqueous solution in which polyethylene oxide and hexamethylenediamine are uniformly dispersed is obtained. S3. Dissolve adipic acid chloride in cyclohexane and stir continuously for 2 hours to obtain an oil phase solution, wherein the content of adipic acid chloride is 0.5 wt%. S4. Select a polyamide phase separation membrane with an average pore size of 0.5 μm, a porosity of 70%, and a thickness of 10 μm, and fix it on the rotating support 8 of the dual-system fractal flow channel liquid supply device to ensure that the polyamide phase separation membrane and the support have no relative displacement and are fully spread. S5. Adjust the height of the lifting rod of the dual-system fractal flow channel liquid supply device to 1.5mm, and control the rotation speed of the rotating support 8 to 1rpm; inject the aqueous solution obtained in step S2 into the first microchannel array 1 through the first inlet 3, and transport it to the drip port through its main channel (diameter 15mm) and sub-channel (diameter 5mm), so that the solution is stably dripped onto the surface of the polyurethane fiber membrane to form an aqueous liquid film; then inject the oil phase solution obtained in step S3 into the second microchannel array 2 through the second inlet 4, and transport it to the drip port through its main channel (diameter 15mm) and sub-channel (diameter 5mm), so that the solution is stably dripped onto the surface of the aqueous liquid film to form an oil liquid film; control the thickness ratio of the aqueous liquid film to the oil liquid film to be 2:1, and the total thickness of the overall liquid film to be 6μm; after standing for 60s, a separation membrane with a polyamide phase separation membrane as the substrate and an ordered fiber network as the functional layer can be prepared; S6. The separation membrane obtained in step S5 is dried at 40°C for 5 minutes, then rinsed with deionized water for 5 minutes to completely remove unreacted monomers and residual solvents, and then dried at 60°C for 10 minutes to finally obtain a self-assembled ordered fiber network separation membrane with an average fiber diameter of 180 nm and an average pore size of 3.8 nm.

[0035] The self-assembled ordered fiber network separation membrane obtained in step S6 was fixed on a dead-end filter device, and a filtration test was conducted on wastewater containing 2 mg / L of heavy metal ions under a pressure of 0.1 MPa. The concentration of heavy metal ions in the filtered water sample decreased to 0.1 mg / L. The separation efficiency of the self-assembled ordered fiber network separation membrane for heavy metal ions was 95%, and the mass transfer flux was 39 L / (m²). 2 ·h).

[0036] Example 5 A self-assembled ordered fiber network separation membrane is prepared by the following steps: S1. Hexamethylenediamine is dissolved in deionized water and stirred continuously for 2 hours to obtain a hexamethylenediamine dispersion, wherein the content of hexamethylenediamine in the dispersion is 7 wt%. S2. Dissolve polyethylene oxide in deionized water and stir vigorously for 5 hours to allow the polyethylene oxide to fully swell and form a sludge-like substance. The polyethylene oxide content in the sludge-like substance is 10 wt%. Then, add the hexamethylenediamine dispersion obtained in step S1 to the sludge-like substance in three portions at a mass ratio of 2:3:5. The sludge-like substance content in the aqueous solution is 0.05 wt%. After mixing evenly, an aqueous solution in which polyethylene oxide and hexamethylenediamine are uniformly dispersed is obtained.

[0037] S3. Dissolve adipic acid chloride in cyclohexane and stir continuously for 2 hours to obtain an oil phase solution, wherein the content of adipic acid chloride is 0.1 wt%. S4. Select a biaxially oriented polyvinylidene fluoride membrane with an average pore size of 1 μm, a porosity of 70%, and a thickness of 30 μm. Fix it on the rotating support 8 of the dual-system fractal flow channel liquid supply device to ensure that the biaxially oriented polyvinylidene fluoride membrane and the rotating support 8 have no relative displacement and are fully spread. S5. Adjust the height of the lifting rod of the dual-system fractal flow channel liquid supply device to 1mm, and control the rotation speed of the rotating support 8 to 1rpm; inject the aqueous solution obtained in step S2 into the first microchannel array 1 through the first inlet 3, and transport it to the drip port through its main channel (diameter 10mm) and sub-channel (diameter 2mm), so that the solution is stably dripped onto the surface of the polyurethane fiber membrane to form an aqueous liquid film; then inject the oil phase solution obtained in step S3 into the second microchannel array 2 through the second inlet 4, and transport it to the drip port through its main channel (diameter 10mm) and sub-channel (diameter 2mm), so that the solution is stably dripped onto the surface of the aqueous liquid film to form an oil liquid film; control the thickness ratio of the aqueous liquid film to the oil liquid film to be 1:1, and the total thickness of the overall liquid film to be 6μm; after standing for 60s, a separation membrane with polyvinylidene fluoride biaxially oriented membrane as the substrate and an ordered fiber network as the functional layer can be prepared; S6. The separation membrane obtained in step S5 is dried at 40°C for 5 minutes, then rinsed with deionized water for 5 minutes to completely remove unreacted monomers and residual solvents, and then dried at 60°C for 10 minutes to finally obtain a self-assembled ordered fiber network separation membrane with a fiber diameter of 80 nm and an average pore size of 2.1 nm.

[0038] The self-assembled ordered fiber network separation membrane obtained in step S6 was fixed on a dead-end filter device, and a filtration test was conducted on wastewater containing 2 mg / L of heavy metal ions under a pressure of 0.1 MPa. The concentration of heavy metal ions in the filtered water sample decreased to 0.06 mg / L. The separation efficiency of the self-assembled ordered fiber network separation membrane for heavy metal ions was 97%, and the mass transfer flux was 35 L / (m²). 2 ·h).

[0039] Example 6 A self-assembled ordered fiber network separation membrane is prepared by the following steps: S1. Hexamethylenediamine is dissolved in deionized water and stirred continuously for 2 hours to obtain a hexamethylenediamine dispersion, wherein the content of hexamethylenediamine in the dispersion is 10 wt%. S2. Dissolve polyethylene oxide in deionized water and stir vigorously for 5 hours to allow the polyethylene oxide to fully swell and form a sludge-like substance. The polyethylene oxide content in the sludge-like substance is 10 wt%. Then, add the hexamethylenediamine dispersion obtained in step S1 to the sludge-like substance in three portions at a mass ratio of 2:3:5. The sludge-like substance content in the aqueous solution is 0.05 wt%. After mixing evenly, an aqueous solution in which polyethylene oxide and hexamethylenediamine are uniformly dispersed is obtained. S3. Dissolve adipic acid chloride in cyclohexane and stir continuously for 2 hours to obtain an oil phase solution, wherein the content of adipic acid chloride is 0.01 wt%. S4. Select a biaxially oriented polyvinylidene fluoride (PVDF) membrane with an average pore size of 0.5 μm, a porosity of 50%, and a thickness of 30 μm. Fix it on the rotating support 8 of the dual-system fractal flow channel liquid supply device to ensure that the PVDF membrane and the rotating support 8 have no relative displacement and are fully spread. S5. Adjust the height of the lifting rod of the dual-system fractal flow channel liquid supply device to 0.8 mm, and control the rotation speed of the rotating support 8 to 1 rpm; inject the aqueous solution obtained in step S2 into the first microchannel array 1 through the first inlet 3, and transport it to the drip port through its main channel (diameter 10 mm) and sub-channel (diameter 2 mm), so that the solution is stably dripped onto the surface of the polyurethane fiber membrane to form an aqueous liquid film; then inject the oil phase solution obtained in step S3 into the second microchannel array 2 through the second inlet 4, and transport it to the drip port through its main channel (diameter 10 mm) and sub-channel (diameter 2 mm), so that the solution is stably dripped onto the surface of the aqueous liquid film to form an oil liquid film; control the thickness ratio of the aqueous liquid film to the oil liquid film to be 2:1, and the total thickness of the overall liquid film to be 6 μm; after standing for 60 s, a separation membrane with polyvinylidene fluoride biaxially oriented membrane as the substrate and an ordered fiber network as the functional layer can be prepared; S6. The separation membrane obtained in step S5 is dried at 40°C for 5 minutes, then rinsed with deionized water for 5 minutes to completely remove unreacted monomers and residual solvents, and then dried at 60°C for 10 minutes to finally obtain an ordered fiber network separation membrane with an average fiber diameter of 50 nm and an average pore size of 0.5 nm.

[0040] The self-assembled ordered fiber network separation membrane obtained in step S6 was fixed on a dead-end filter device, and a filtration test was conducted on wastewater containing 2 mg / L of heavy metal ions under a pressure of 0.1 MPa. The concentration of heavy metal ions in the filtered water sample decreased to 0.02 mg / L. The separation efficiency of the self-assembled ordered fiber network separation membrane for heavy metal ions was 99%, and the mass transfer flux was 30 L / (m²). 2 ·h).

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a self-assembled ordered fiber network separation membrane, characterized in that, Including the following steps: S1. Dissolve amine monomers in water to obtain an aqueous monomer dispersion; S2. Add the water-soluble polymer to water and stir to form a mud-like substance. Then, gradually incorporate the aqueous monomer dispersion obtained in step S1 into the mud-like substance and continue stirring to obtain an aqueous solution. S3. Dissolve the polyacryl chloride monomer in an organic solvent to obtain an oil phase solution; S4. Using a dual-system fractal flow channel liquid supply device, the aqueous phase solution obtained in step S2 and the oil phase solution obtained in step S3 are coated on the surface of the support membrane in a set order, so that the amine monomers and polyacrylamide monomers undergo polymerization reaction at the interface, and self-assemble into an ordered fiber network on the surface of the support membrane, thereby producing a separation membrane with the support membrane as the substrate and the ordered fiber network as the functional layer. S5. After drying, cleaning and baking the separation membrane obtained in step S4, a self-assembled ordered fiber network separation membrane is obtained.

2. The method for preparing a self-assembled ordered fiber network separation membrane according to claim 1, characterized in that, The amine monomers are selected from one or more of ethylenediamine, hexamethylenediamine, piperazine, m-phenylenediamine, p-phenylenediamine, polyethyleneimine, diethyltriamine, benzidine, 1,4-cyclohexanediamine, methylcyclohexanediamine, tetradecylamine, 1,11-undecanediamine, 1,7-heptanediamine, or 1,4-butanediamine. The water-soluble polymer is selected from one or more of the following: polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, starch, polyethylene glycol, polypropylene glycol, polymaleic anhydride, polyacrylic acid, polymethacrylic acid, alginate, polyethylene oxide-propylene oxide copolymer, polyether-amide block copolymer, sodium carboxymethyl cellulose, gelatin, hydroxypropyl methylcellulose, or polyethylene glycol diacrylate. The polyacryl chloride is selected from one or more of the following: pyromellitic trichloroisocyanurate, 3,4',5-biphenyltrichloroisocyanurate, 3,3',5,5'-biphenyltetrachloroisocyanurate, isophthaloyl chloride, terephthaloyl chloride, phthaloyl chloride, 5-isocyanate-isophthaloyl chloride, 3,5-dichloroformylphenylphosphonochloride, malonyl chloride, succinic chloride, glutaryl chloride, adipyl chloride, glutaryl chloride, naphthalene dichloroisocyanurate, p-dichlorodiphenoxyethanebutane or 4,4'-diphenyl ether diacryl chloride; The organic solvent is selected from one or more of the following: n-hexane, cyclohexane, n-heptane, isooctane, n-dodecane, cyclopentane, methylcyclohexane, petroleum ether, toluene, xylene, carbon tetrachloride, chloroform, dichloromethane, tert-amyl methyl ether, and o-dichlorobenzene.

3. The method for preparing a self-assembled ordered fiber network separation membrane according to claim 1, characterized in that, In step S1, the concentration of amine monomers in the aqueous monomer dispersion is 0.1~10 wt%. In step S2, the concentration of the water-soluble polymer in the sludge is 10-50 wt%; the gradient-incorporated aqueous monomer dispersion is added to the sludge in three batches, with a mass ratio of 2:3:5, and the mixture is stirred vigorously for 1-5 minutes after each addition; the content of the sludge in the aqueous solution is 0.05-1 wt%. In step S3, the concentration of polyacrylamide chloride monomer in the oil phase solution is 0.01~5wt%.

4. The method for preparing a self-assembled ordered fiber network separation membrane according to claim 1, characterized in that, In step S4, the supporting membrane includes a fiber membrane, a phase separation membrane, a stretched membrane, or a particle sintered membrane; the pore size of the supporting membrane is 0.5~5μm, the porosity is ≥70%, and the thickness is 10~50μm; The material of the support membrane is selected from one or more of polyurethane, polyamide, polyvinylidene fluoride, polyethersulfone, polypropylene, polytetrafluoroethylene, high-density polyethylene, alumina, zirconium oxide, titanium oxide, silicon oxide, and silicon carbide.

5. The method for preparing a self-assembled ordered fiber network separation membrane according to claim 1, characterized in that, In step S4, the dual-system fractal flow channel liquid supply device includes a dual-system fractal flow channel and a variable height swirl scraper unit; The dual-system fractal flow channel comprises two independent and symmetrically distributed microchannel arrays; The variable height rotary scraper unit includes a lifting assembly and a collecting assembly; The lifting assembly includes a lifting rod (5) that is vertically and vertically disposed between the two microchannel arrays and a scraper (6) fixedly connected to the lower end of the lifting rod (5); the collecting assembly includes a rotating bracket (8) disposed directly below the microchannel array.

6. The method for preparing a self-assembled ordered fiber network separation membrane according to claim 5, characterized in that, The variable height swivel scraper unit further includes a rotary drive assembly; wherein the rotary drive assembly includes a rotary shaft (10) fixedly connected to the bottom center of the rotary support (8), a transmission rod (11) pulsatorically connected to the rotary shaft (10), and a second drive motor (12) for driving the transmission rod (11) to drive the rotary support (8) to rotate. The rotation speed of the rotating bracket (8) is 1~20 rpm; the height of the scraper (6) is 0.5~5 mm.

7. The method for preparing a self-assembled ordered fiber network separation membrane according to claim 5, characterized in that, The microchannel array has a main channel (13) and sub-channels (14); the diameter of the main channel (13) is 10~20mm; the diameter of the sub-channels (14) is 2~8mm.

8. The method for preparing a self-assembled ordered fiber network separation membrane according to claim 1, characterized in that, In step S4, the coating sequence is either aqueous solution first, then oil phase solution, or oil phase solution first, then aqueous solution.

9. A self-assembled ordered fiber network separation membrane prepared by the method according to any one of claims 1 to 8, characterized in that, The self-assembled ordered fiber network separation membrane has fibers with a diameter of 50-500 nm and a pore size of 10-100 nm. It achieves a separation efficiency of ≥90% for heavy metal ions and a mass transfer flux of ≥30 L / (m²). 2 ·h).

10. An application of a self-assembled ordered fiber network separation membrane prepared by the method according to any one of claims 1 to 8, characterized in that, The self-assembled ordered fiber network separation membrane is applied to the field of water treatment.

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