A method for preparing a membrane having a patterned structure and its water filtration applications

Abstract

The application belongs to the field of membrane separation technology, and relates to a preparation method of a separation membrane with a pattern structure and water filtration application thereof. The method comprises the following steps: firstly, spinning is performed on an aqueous phase spinning solution by using a spinning device, and after jet phase separation and solidification, a fiber membrane is formed on a hollow receiving plate; then the aqueous phase spinning solution is changed from a jet stream into a sprayed droplet, which is sprayed on the fiber membrane and forms an aqueous phase liquid film inside; further, an oil phase interface reaction field regulation system is used to convert an oil phase solution into an aerosol and spray the aerosol on the fiber membrane; by regulating the concentration of the aqueous phase spinning solution, the concentration of the oil phase aerosol and the spraying rate, the interface polymerization reaction rate of the aqueous phase monomer and the oil phase monomer is controlled, and a separation membrane with a pattern structure is prepared. The separation membrane prepared by the application has excellent structural stability, the pattern structure is controllable, the filtration efficiency of 0.1-10 mu m particles is greater than or equal to 95%, the water flux is greater than or equal to 300 L·m ‑2 ·h ‑1 , and has a wide application prospect in the field of water filtration.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, and relates to a method for preparing a separation membrane with a patterned structure and its application in water filtration. Background Technology

[0002] Separation membranes, as highly efficient water filtration materials, play a crucial role in water filtration fields such as drinking water purification, industrial wastewater treatment, and seawater desalination. Their separation performance directly determines water purification efficiency and water quality compliance, making them key materials for ensuring the recycling and safe supply of water resources. Currently, separation membrane preparation methods encompass various types, including phase inversion, melt stretching, and interfacial polymerization. Among these, interfacial polymerization has become the primary method for separation membrane preparation due to its relatively simple operation process, strong controllability of the polymerization reaction, and the ability to rapidly construct a dense separation layer by adjusting the monomer ratio. However, traditional interfacial polymerization methods still suffer from problems in practical applications, such as weak interfacial bonding between the fiber membrane and the functional layer, and a limited range of structural types. This results in insufficient membrane structural stability and an inability to simultaneously achieve high flux and selectivity, thus restricting its application in the field of high-efficiency water filtration.

[0003] To address these issues, researchers have attempted to construct separation membranes with unique microstructures by controlling the kinetics of interfacial polymerization reactions. For example, by utilizing the instability effect of reaction-diffusion systems, Turing structures and other patterned structures can be formed in the separation layer. These heterogeneous structures significantly increase the specific surface area of ​​the membrane, optimize mass transfer channels, and improve both the water flux and retention selectivity, providing a new approach to overcoming the performance bottlenecks of traditional membranes. However, existing technologies and related patents still have significant shortcomings in practical applications. Patent CN115382403A, when preparing a composite membrane by combining electrospun fiber membranes with interfacial polymerization, requires the separate preparation of the fiber membrane first, followed by the construction of the functional layer through hydrophilic water spin coating, thermal crosslinking, and other steps. The lack of in-situ synergistic effect at the interface results in weak bonding, making it prone to delamination during long-term filtration operations and severely affecting membrane stability. Patent CN119499886A constructs a charged amino acid interlayer on the surface of an ultrafiltration base membrane and then utilizes water-soluble... Hydrogen bonding / electrostatic interactions between cellulose-based substances and diamines in the liquid jointly regulate the reaction-diffusion rate of the aqueous-organic phase, but the reaction system can only generate wrinkled patterned structures. Patent CN115845614A, by mixing an aqueous solution of nano-molecular sieves and graphene oxide to form a dispersion, constructs a continuous and homogeneous intermediate layer on the surface of a polyethersulfone substrate membrane through filtration, and then uses interfacial polymerization to form a polyamide separation layer on the surface of the intermediate layer. However, its reaction system can only form striped patterned structures, which cannot meet the differentiated membrane structure requirements of different separation scenarios. Therefore, there is an urgent need to develop a separation membrane preparation method that combines excellent interfacial bonding and rich patterned structures to meet the specific performance requirements of different water treatment applications. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art by providing a method for preparing a separation membrane with a patterned structure and its application in water filtration.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for preparing a separation membrane with a patterned structure includes the following steps: S1. Dissolve the aqueous phase reactant monomer and polymer in a solvent to obtain an aqueous phase spinning solution; S2. The aqueous spinning solution obtained in step S1 is sprayed into a jet by a spinning device. The jet is solidified and deposited on a hollow receiving plate after whipping phase separation to obtain a fiber membrane. S3. The aqueous spinning solution obtained in step S1 is transformed from a jet stream into jet droplets and sprayed onto the fiber membrane obtained in step S2. The droplets are immersed and spread inside the fiber membrane to obtain an aqueous liquid membrane. S4. Dissolve the oil-phase reactant monomer in an organic solvent to obtain an oil-phase solution; S5. Using the oil phase interface reaction field control system, the oil phase solution is made to penetrate the hollow receiving plate in the form of an aerosol and sprayed onto the aqueous phase liquid film obtained in step S3, so that the aqueous phase reactant and the oil phase reactant undergo a polymerization reaction at the interface, thereby forming a pattern structure on the fiber membrane. S6. The product with the patterned structure formed in step S5 is dried to obtain a separation membrane with a patterned structure.

[0006] Furthermore, in the aqueous spinning solution, the concentration of the aqueous reactive monomer is 0.01~4wt%, and the concentration of the polymer is 10~30wt%; in the oil phase solution, the concentration of the oil phase reactive monomer is 0.05~5wt%.

[0007] Furthermore, in step S1, the aqueous phase reaction monomer is a polyamine; The polymer is selected from one or more of the following: polyethylene oxide, polyvinyl chloride, polyvinylidene fluoride, polycarbonate, polymethyl methacrylate, polypropylene terephthalate, polystyrene, polyurethane, polybenzimidazole, polyethylene terephthalate, polycaprolactone, polylactic acid, polyhydroxybutyrate, polyacrylonitrile, polyamide, polyamide imide, polyvinyl alcohol, polyvinyl butyral, polysulfone, polyethyleneimine, or polyimide. The solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, water, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, isobutanol, ethylene glycol, butanediol, hexanediol, or glycerol.

[0008] In step S4, the oil phase reaction monomer is a polyacrylamide chloride; the organic solvent is selected from one or more of n-hexane, n-decane, isooctane, or n-heptane.

[0009] Furthermore, the polyamine is selected from one or more of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, pyromellitic triamine, piperazine, ethylenediamine, propylenediamine, butanediamine, hexamethylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, or 1,4-diaminocyclohexane; The polyacryl chloride is selected from one or more of terephthaloyl chloride, orthophthaloyl chloride, isophthaloyl chloride, biphenyl dichloroyl chloride, benzene disulfonyl chloride, pyromellitic acid trichloroyl chloride, succinic acid chloride, succinic acid trichloroyl chloride, glutaryl chloride, glutaryl trichloroyl chloride, or adipyl chloride.

[0010] Furthermore, the spinning device is one of an electrostatic spinning device or an air-jet spinning device; The hollow receiving plate is disposed below the spinning device; The perforated receiving plate has a perforation rate of 60-95%, the hole shape is circular, the hole diameter is 0.3-5mm, and the thickness is 1-3mm; In step S5, the ratio of polyamine concentration to oil aerosol concentration in the aqueous spinning solution is 0.1:1 to 1:5, the oil aerosol spraying rate is 0.1 to 3 mL / h, and the spraying time is 2 to 3 h. By adjusting the ratio of polyamine concentration to oil aerosol concentration in the aqueous spinning solution and the oil aerosol spraying rate, the type of pattern structure can be controlled. The pattern structure includes spots, stripes, and spot-stripe composite structures. In step S6, the drying conditions are 30~80℃ for 1~5 hours.

[0011] Furthermore, in step S2, the electrospinning process of the electrospinning device is as follows: the electrospinning voltage is 10~100kV, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 0.5~10mL / h, and the spinning time is 3~4h. In step S3, the spinning process of changing the aqueous spinning solution from a jet to a droplet is as follows: the electrospinning voltage is 5~50kV, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 1~20mL / h, and the spinning time is 2~3h.

[0012] Furthermore, in step S2, the spinning process of the air-jet spinning device is as follows: the air-jet spinning airflow velocity is 2~20m / s, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 0.5~10mL / h, and the spinning time is 3~4h. In step S3, the spinning process of changing the aqueous spinning solution from a jet to a droplet is as follows: the air jet spinning airflow velocity is 1~10m / s, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 1~20mL / h, and the spinning time is 1~2h.

[0013] Furthermore, in step S5, the oil phase interface reaction field control system includes an aerosol generation unit and a directional deposition unit; The aerosol generating unit includes an oil phase storage tank, a high-pressure air pump, an ultrasonic transducer, and an oil phase aerosol tank. The directional deposition unit includes a porous capillary nozzle; The oil phase storage tank is connected to the high-pressure air pump and the oil phase aerosol tank via pipelines; the ultrasonic transducer is installed in the oil phase storage tank; the oil phase aerosol tank is connected to the porous capillary nozzle via pipelines; the porous capillary nozzle is located below the hollow receiving plate in step S2.

[0014] Furthermore, the aerosol generating unit also includes an aerosol particle size detector disposed inside the oil phase aerosol tank; The directional deposition unit also includes an aerosol concentration sensor disposed above the porous capillary nozzle.

[0015] Furthermore, the high-pressure gas pump delivers high-pressure gas into the oil phase storage tank, atomizing the oil phase solution into oil phase droplets. These droplets collide with the high-speed gas flow, breaking into micron-sized droplets. Upon activation of the ultrasonic transducer built into the oil phase storage tank, high-frequency ultrasonic vibrations act on the atomized oil phase droplets, further causing them to break apart. Simultaneously, the droplets undergo intense friction with the gas, forming an oil phase aerosol that is suspended in the gaseous medium. The oil phase aerosol generated in the oil phase storage tank enters the oil phase aerosol tank through a pipeline. An aerosol particle size analyzer in the oil phase aerosol tank detects the particle size of the oil phase aerosol. When the detected particle size reaches 2-5 μm, it is transported through a pipeline to the porous high-pressure capillary nozzle, which uniformly sprays the oil phase aerosol onto the substrate surface. The aerosol concentration sensor monitors the aerosol concentration in real time.

[0016] The present invention also provides a separation membrane with a patterned structure, wherein the separation membrane with the patterned structure is prepared by the method described in any of the preceding claims. The separation membrane material with the patterned structure exhibits a filtration efficiency of ≥95% for particles of 0.1~10 μm and a water flux of ≥300 L·m³. -2 ·h -1 .

[0017] The present invention also provides an application of the separation membrane with a patterned structure as described above, wherein the separation membrane with a patterned structure is applied in the field of water filtration.

[0018] The technical principle of this invention is as follows: This invention is based on reaction-diffusion kinetics theory. It constructs a synergistic structure of a fiber membrane and an aqueous liquid membrane using electrospinning or air-jet spinning techniques, and utilizes an oil-phase interface reaction field control system to precisely regulate the interfacial polymerization reaction. Specifically, by controlling the concentration of polyamine monomers in the aqueous spinning solution and spinning parameters (voltage, ambient temperature and humidity, and injection speed), a fiber membrane with a specific pore structure and a uniform aqueous liquid membrane are formed on a perforated receiving plate, providing a reaction substrate for subsequent interfacial polymerization. Simultaneously, the oil-phase interface reaction field control system (including an aerosol generation unit and a directional deposition unit) converts the polyacrylamide chloride solution into an aerosol. After penetrating the perforated receiving plate, the aerosol reacts with the aqueous liquid membrane in the fiber membrane. By controlling the aerosol concentration, the proportion of polyacrylamide chloride at the water-oil interface can be altered. Controlling the spraying rate ensures a stable supply of polyacrylamide chloride aerosol, thereby regulating the reaction rate between the polyamine and polyacrylamide chloride at the water-oil interface, causing instability in the reaction-diffusion system, and subsequently spontaneously forming spots, streaks, and spot-streak composite structures. In this process, the high porosity of the fiber membrane and the high specific surface area of ​​the patterned structure produce a synergistic effect, significantly improving the membrane's mass transfer efficiency and separation performance.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) Enhanced interfacial bonding: The fiber membrane and the aqueous liquid membrane are formed by in-situ spinning, which makes the fiber membrane and the functional layer form a tight interfacial bonding state, which enhances the interfacial bonding strength between the two, ensures that the separation membrane maintains the structural integrity during long-term filtration operation, and ensures the stable performance of filtration.

[0020] (2) Precision of structure control: By controlling the spraying mode of aqueous solution through step-by-step spinning parameters, jets are easily formed under high voltage / gas pressure and droplets are easily formed under low voltage / gas pressure. The ambient temperature and humidity help to adjust the state of the aqueous system. Then, the spinning parameters are linked with the concentration of oil phase aerosol and the spraying rate to control the reaction rate between the aqueous liquid film and the oil phase monomer, thereby accurately controlling the type of pattern structure (spots, stripes, etc.).

[0021] (3) Integrated preparation process: The fiber membrane preparation, aqueous liquid membrane formation and interfacial polymerization reaction are integrated into the same system. The hollow receiving plate serves as both a receiving carrier for the fiber membrane and a directional transport channel for oil phase aerosols through its hollow structure. The oil phase aerosol control system precisely controls the particle size, concentration and deposition rate of the aerosols. The synergy between the two enables the continuous development of fiber membrane preparation, aqueous liquid membrane formation and interfacial polymerization reaction. Through the linkage control of spinning parameters and oil phase aerosol parameters by the system, the pattern structure is ensured to be controlled in real time during the preparation process, realizing the in-situ controllable construction of the pattern structure and simplifying the overall preparation process.

[0022] (4) The separation membrane with a patterned structure prepared by this invention has excellent structural stability and controllable patterned structure, with a filtration efficiency of ≥95% for particles of 0.1~10μm and a water flux of ≥300L·m -2 ·h -1 It has broad application prospects in the field of water filtration. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the oil phase interface reaction field control system and its relationship with the spinning device and the hollow receiving plate according to an embodiment of the present invention. The numbers in the figure are as follows: 1-spinning device, 2-perforated receiving plate, 3-oil phase storage tank, 4-high pressure air pump, 5-ultrasonic transducer, 6-oil phase aerosol tank, 7-aerosol particle size detector, 8-porous capillary nozzle, 9-aerosol concentration sensor. Figure 2 This is an electron microscope image of the patterned separation membrane prepared in Example 1. 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] In this technical solution, any component models, material names, connection structures, control methods, etc., that are not explicitly stated are considered common technical features disclosed in the prior art and can be selected or implemented based on conventional technical means without additional special conditions.

[0026] like Figure 1As shown, the oil phase interface reaction field control system used in each embodiment includes an aerosol generation unit and a directional deposition unit. The aerosol generation unit includes an oil phase storage tank 3, a high-pressure air pump 4, an ultrasonic transducer 5, an oil phase aerosol tank 6, and an aerosol particle size analyzer 7. The directional deposition unit includes a porous capillary nozzle 8 and an aerosol concentration sensor 9. The oil phase storage tank 3 is connected to the high-pressure air pump 4 and the oil phase aerosol tank 6 via pipes. The ultrasonic transducer 5 is installed in the oil phase storage tank 3. The aerosol particle size analyzer 7 is installed in the oil phase aerosol tank 6. The oil phase aerosol tank 6 is connected to the porous capillary nozzle 8 via pipes. The porous capillary nozzle 8 is installed below the perforated receiving plate 2 and is used to spray aerosols onto the perforated receiving plate 2. The aerosol concentration sensor 9 is installed in the space between the porous capillary nozzle 8 and the perforated receiving plate 2 and is used to detect the aerosol concentration.

[0027] During the spinning process, a perforated receiving plate 2 is positioned below the spinning device 1. The perforation rate of the perforated receiving plate 2 is 60-95%, the aperture is 0.3-5 mm, and the thickness is 1-3 mm. First, the aqueous spinning solution is spun using the spinning device 1. After phase separation and solidification, the jet formed by the jet is deposited on the perforated receiving plate 2 to form a fiber membrane. Then, the parameters of the spinning device 1 are adjusted to change the aqueous spinning solution from a jet to a droplet jet. The droplets are sprayed onto the surface and interior of the fiber membrane, and after wetting and spreading, an aqueous liquid film is formed. The oil phase solution is then transferred to the oil phase storage tank 3 and sealed. The oil phase interface reaction field is then activated for regulation. The system starts the high-pressure air pump 4 and the ultrasonic transducer 5 to atomize the oil phase solution into an aerosol. The aerosol is introduced into the oil phase aerosol tank 6, and the aerosol particle size detector 7 installed in the tank monitors and ensures that the aerosol particle size is 2~5μm in real time. After the aerosol is transported to the porous capillary nozzle 8 through the pipeline, it penetrates the hollow structure of the hollow receiving plate 2 and is vertically and uniformly sprayed onto the surface of the aqueous phase liquid film. The concentration ratio of polyamine to oil phase aerosol in the aqueous phase liquid film is monitored and adjusted in real time by the aerosol concentration sensor 9, which promotes the polymerization reaction of polyamine and oil phase monomer at the water-oil interface, thereby forming a continuous pattern structure on the fiber membrane.

[0028] Example 1 A separation membrane with a patterned structure is prepared by the following steps: S1. Piperazine and polyvinylidene fluoride (Mw=100000) were dissolved together in N-methylpyrrolidone and mechanically stirred for 4 hours at a stirring temperature of 50℃ and a stirring speed of 250rpm to obtain an aqueous spinning solution. In the aqueous spinning solution, the mass fraction of piperazine was 0.01wt% and the mass fraction of polyvinylidene fluoride was 10wt%.

[0029] S2. Preparation of fiber membrane by air-jet spinning: Select a perforated receiving plate 2 with a perforation rate of 60%, a pore size of 0.3 mm, and a thickness of 3 mm; inject the aqueous spinning solution obtained in step S1 into a syringe and fix it on the injection pump, and set the spinning process parameters as follows: air-jet spinning airflow speed of 2 m / s, spinning ambient temperature of 10℃, ambient relative humidity of 10%, and injection pump injection speed of 0.5 mL / h; after starting the equipment, the aqueous spinning solution is sprayed under the drive of airflow to form a continuous jet, which is deposited on the perforated receiving plate 2 after phase separation and solidification. Spinning is stopped after 4 hours to obtain a continuous and uniform fiber membrane.

[0030] S3. Adjust the air jet spinning parameters: Keep the spinning environment temperature at 10℃ and the relative humidity at 10%, adjust the air jet spinning airflow speed to 1m / s and the injection pump injection speed to 1mL / h; at this time, the aqueous spinning solution changes from a continuous jet to fine droplets, which are sprayed onto the surface and interior of the fiber membrane obtained in step S2. Spinning is stopped after 2 hours. After the droplets are wetted and spread, an aqueous liquid film of uniform thickness is formed.

[0031] S4. Isophthaloyl chloride was dissolved in n-hexane and mechanically stirred for 1 hour at room temperature and a stirring speed of 400 rpm to obtain a homogeneous oil phase solution; the mass fraction of isophthaloyl chloride in the oil phase solution was 0.05 wt%.

[0032] S5. Transfer the oil phase solution prepared in step S4 to the oil phase storage tank 3 and seal it; turn on the oil phase interface reaction field control system, start the high-pressure air pump 4 (output pressure 0.3MPa) and ultrasonic transducer 5 to atomize the oil phase solution into aerosols with a particle size of 2~5μm; the aerosol generated in the oil phase storage tank 3 enters the oil phase aerosol tank 6 through the pipeline; the aerosol is transported to the porous capillary nozzle 8 through the pipeline and sprayed vertically and uniformly on the surface of the aqueous phase liquid film obtained in step S3 at a rate of 0.1mL / h; monitor and control the aerosol concentration in real time through the aerosol concentration sensor 9 to maintain the mass fraction ratio of piperazine to oil phase aerosol at 0.1:1, so as to promote the polymerization reaction of piperazine and isophthaloyl chloride at the water-oil interface. Stop the spraying after 3h, and finally form a continuous spot structure.

[0033] S6. The membrane material obtained after interfacial polymerization in step S5 is repeatedly washed with deionized water and ethanol to remove unreacted monomers and residual impurities. It is then transferred to a forced-air drying oven and dried at 30°C for 5 hours. During the drying process, residual n-hexane and N-methylpyrrolidone in the membrane material gradually evaporate. After drying, a separation membrane with a dotted structure is obtained. This dotted structure is densely and uniformly distributed, with dot diameters of approximately 0.1–0.5 μm, achieving a balance between retention performance and mass transfer efficiency. The electron micrograph is shown below. Figure 2As shown. Under a pressure of 0.3 MPa, filtration tests were conducted on simulated wastewater containing 0.1–10 μm silica particles. The speckled structure membrane demonstrated a filtration efficiency ≥95% for 0.1–10 μm particles and a water flux ≥300 L·m⁻¹. -2 ·h -1 .

[0034] Example 2 A separation membrane with a patterned structure is prepared by the following steps: S1. Ethylenediamine and polyethylene oxide (Mw=300000) were dissolved together in a water:ethanol (5:1, v / v) mixed solvent and mechanically stirred for 2 hours at a stirring temperature of 25℃ and a stirring speed of 200rpm to obtain an aqueous spinning solution. In this aqueous spinning solution, the mass fraction of ethylenediamine was 4wt% and the mass fraction of polyethylene oxide was 30wt%.

[0035] S2. Preparation of fiber membrane by air-jet spinning: Select a perforated receiving plate 2 with a perforation rate of 95%, a hole diameter of 5 mm, and a thickness of 1 mm; inject the aqueous spinning solution obtained in step S1 into a syringe and fix it on the injection pump, and set the spinning process parameters: air-jet spinning airflow speed of 20 m / s, spinning ambient temperature of 40℃, ambient relative humidity of 70%, and injection pump injection speed of 10 mL / h; after starting the equipment, a continuous jet is formed under the drive of airflow, and after phase separation and solidification, it is deposited on the perforated receiving plate 2. Spinning is stopped after 3 hours to obtain a continuous and uniform fiber membrane.

[0036] S3. Adjust the air jet spinning parameters: Keep the spinning environment temperature at 40℃ and the relative humidity at 70% constant. Adjust the air jet spinning airflow speed to 10m / s and the injection pump injection speed to 20mL / h. At this time, the aqueous spinning solution changes from a continuous jet to fine droplets. The droplets are sprayed onto the surface and interior of the fiber membrane obtained in step S2. Spinning is stopped after 1 hour. After the droplets are wetted and spread, a uniform aqueous liquid film is formed.

[0037] S4. Dissolve adipicoyl chloride in n-decane and mechanically stir for 1 hour at room temperature and a stirring speed of 400 rpm to obtain a homogeneous oil phase solution; the mass fraction of adipicoyl chloride in the oil phase solution is 5 wt%.

[0038] S5. Transfer the oil phase solution prepared in step S4 to the oil phase storage tank 3 and seal it; turn on the oil phase interface reaction field control system, start the high-pressure air pump 4 (output pressure 0.3MPa) and ultrasonic transducer 5 to atomize the oil phase solution into aerosols with a particle size of 2~5μm; the aerosol generated in the oil phase storage tank 3 enters the oil phase aerosol tank 6 through the pipeline; the aerosol is transported to the porous capillary nozzle 8 through the pipeline and sprayed vertically and uniformly on the surface of the aqueous phase liquid film obtained in step S3 at a rate of 3mL / h; the aerosol concentration sensor 9 monitors and controls in real time to maintain the concentration ratio of ethylenediamine to oil phase aerosol at 1:5, so as to promote the polymerization reaction of ethylenediamine and adipyl chloride at the water-oil interface. The spraying is stopped after 2 hours, and finally a continuous striped structure is formed.

[0039] S6. The membrane material obtained after interfacial polymerization in step S5 is repeatedly washed with deionized water to remove unreacted monomers and residual impurities; then transferred to a forced-air drying oven and dried at 80℃ for 1 hour; during the drying process, the residual n-decane and ethanol in the membrane material gradually evaporate; after drying, a separation membrane with a striped structure is obtained. This striped structure is continuous and uniformly spaced, with a stripe width of approximately 0.2~0.3μm, achieving a balance between retention performance and mass transfer efficiency. Filtration tests were conducted on simulated wastewater containing 0.1~10μm silica particles at a pressure of 0.3MPa. The striped structure separation membrane showed a filtration efficiency ≥96% for 0.1~10μm particles and a water flux ≥450L·m³. -2 ·h -1 .

[0040] Example 3 A separation membrane with a patterned structure is prepared by the following steps: S1. Soluble m-phenylenediamine and polyethyleneimine (Mw=300000) were dissolved together in a mixed solvent of N,N-dimethylacetamide:methanol (2:1, v / v) and mechanically stirred for 3 hours at a stirring temperature of 45℃ and a stirring speed of 300 rpm to obtain an aqueous spinning solution. In this aqueous spinning solution, the mass fraction of m-phenylenediamine was 0.01 wt% and the mass fraction of polyethyleneimine was 10 wt%.

[0041] S2. Preparation of fiber membrane by electrospinning: A perforated receiving plate 2 with a perforation rate of 60%, a pore size of 0.3 mm, and a thickness of 3 mm is selected; the aqueous spinning solution obtained in step S1 is injected into a syringe and fixed on an injection pump. The spinning process parameters are set as follows: voltage 10 kV, spinning ambient temperature 10℃, ambient relative humidity 10%, and injection pump injection speed 0.5 mL / h. After starting the equipment, the aqueous spinning solution forms a continuous jet under the action of the electric field force. After phase separation and solidification, it is deposited on the perforated receiving plate 2. Spinning is stopped after 4 hours to obtain a continuous and uniform fiber membrane.

[0042] S3. Adjust electrospinning parameters: Keep the spinning environment temperature at 10℃ and the relative humidity at 10%, adjust the voltage to 5kV and the injection pump speed to 1mL / h; at this time, the aqueous spinning solution changes from a continuous jet to fine droplets, which are sprayed onto the surface and interior of the fiber membrane obtained in step S2. Spinning is stopped after 3 hours. After the droplets are wetted and spread, an aqueous liquid film of uniform thickness is formed.

[0043] S4. Dissolve pyromellitic chloride in n-hexane and mechanically stir for 2 hours at room temperature and a stirring speed of 400 rpm to obtain a homogeneous oil phase solution; the mass fraction of pyromellitic chloride in the oil phase solution is 0.05 wt%.

[0044] S5. Transfer the oil phase solution prepared in step S4 to the oil phase storage tank 3 and seal it; turn on the oil phase interface reaction field control system, start the high-pressure air pump 4 (output pressure 0.3MPa) and ultrasonic transducer 5 to atomize the oil phase solution into aerosols with a particle size of 2~5μm; the aerosol generated in the oil phase storage tank 3 enters the oil phase aerosol tank 6 through the pipeline; the aerosol is transported to the porous capillary nozzle 8 through the pipeline and sprayed vertically and uniformly on the surface of the aqueous phase liquid film obtained in step S3 at a rate of 0.1mL / h; monitor and control the aerosol concentration in real time through the aerosol concentration sensor 9 to maintain the mass fraction ratio of m-phenylenediamine to oil phase aerosol at 0.1:1, so as to promote the polymerization reaction of m-phenylenediamine and trimesoyl chloride at the water-oil interface. Stop the spraying after 3h, and finally form a continuous spot-striped composite structure.

[0045] S6. The membrane material obtained after interfacial polymerization in step S5 is repeatedly washed with deionized water and ethanol to remove unreacted monomers and residual impurities. It is then transferred to a forced-air drying oven and dried at 30°C for 5 hours. During the drying process, residual hexane, N,N-dimethylacetamide, and methanol in the membrane material gradually evaporate. After drying, a separation membrane with a speckled-striped composite structure is obtained. This structure consists of spots with a diameter of 0.1–0.3 μm and narrow stripes with a spacing of 0.3–0.5 μm, achieving a balance between retention performance and mass transfer efficiency. Filtration tests were conducted on simulated wastewater containing 0.1–10 μm silica particles at a pressure of 0.3 MPa. The speckled-striped composite structure separation membrane showed a filtration efficiency ≥97% for 0.1–10 μm particles and a water flux ≥400 L·m⁻¹. -2 ·h -1 .

[0046] Example 4 A separation membrane with a patterned structure is prepared by the following steps: S1. Pyromellitic triamine and polyacrylonitrile (Mw=150000) were dissolved together in a dimethyl sulfoxide:ethanol (4:1, v / v) mixed solvent and mechanically stirred for 3.5 h at a stirring temperature of 35℃ and a stirring speed of 350 rpm to obtain an aqueous spinning solution; in the aqueous spinning solution, the mass fraction of pyromellitic triamine was 4 wt% and the mass fraction of polyacrylonitrile was 30 wt%.

[0047] S2. Preparation of fiber membrane by electrospinning: Select a perforated receiving plate 2 with a perforation rate of 95%, a pore size of 5 mm, and a thickness of 1 mm; inject the aqueous spinning solution obtained in step S1 into a syringe and fix it on the injection pump, set the spinning process parameters as follows: voltage 100 kV, spinning ambient temperature 40℃, ambient relative humidity 70%, injection pump injection speed 10 mL / h. After starting the equipment, the aqueous spinning solution forms a continuous jet under the action of the electric field force, and after phase separation and solidification, it is deposited on the perforated receiving plate 2. Spinning is stopped after 3 hours to obtain a continuous and uniform fiber membrane.

[0048] S3. Adjust electrospinning parameters: Keep the spinning environment temperature at 40℃ and the relative humidity at 70%, adjust the voltage to 50kV and the injection pump speed to 20mL / h; at this time, the aqueous spinning solution changes from a continuous jet to fine droplets, which are sprayed onto the surface and interior of the fiber membrane obtained in step S2. Spinning is stopped after 2 hours. After the droplets are wetted and spread, an aqueous liquid film of uniform thickness is formed.

[0049] S4. Dissolve biphenyl dicarboxylate in isooctane and mechanically stir for 2 hours at room temperature and a stirring speed of 400 rpm to obtain a homogeneous oil phase solution; the mass fraction of biphenyl dicarboxylate in the oil phase solution is 5 wt%.

[0050] S5. Transfer the oil phase solution prepared in step S4 to the oil phase storage tank 3 and seal it; turn on the oil phase interface reaction field control system, start the high-pressure air pump 4 (output pressure 0.3MPa) and ultrasonic transducer 5 to atomize the oil phase solution into aerosols with a particle size of 2~5μm; the aerosol generated in the oil phase storage tank 3 enters the oil phase aerosol tank 6 through the pipeline; the aerosol is transported to the porous capillary nozzle 8 through the pipeline and sprayed vertically and uniformly on the surface of the aqueous phase liquid film obtained in step S3 at a spraying rate of 3mL / h; monitor and control the aerosol concentration in real time through the aerosol concentration sensor 9 to maintain the mass fraction ratio of pyromellitic triamine to oil phase aerosol at 1:5, so that pyromellitic triamine and biphenyl dicarboxylate chloride undergo a polymerization reaction at the water-oil interface. Stop spraying after 2 hours to finally form a continuous spot structure.

[0051] S6. The membrane material obtained after interfacial polymerization in step S5 is repeatedly washed with deionized water to remove unreacted monomers and residual impurities; then transferred to a forced-air drying oven and dried at 80℃ for 1 hour; during the drying process, the residual isooctane, dimethyl sulfoxide, and ethanol in the membrane material gradually evaporate; after drying, a separation membrane with a dotted structure is obtained. This dotted structure is densely and uniformly distributed, with a dot diameter of approximately 0.2~0.6μm, achieving a balance between retention performance and mass transfer efficiency. Filtration tests were conducted on simulated wastewater containing 0.1~10μm silica particles at a pressure of 0.3MPa. The dotted structure separation membrane showed a filtration efficiency ≥98% for 0.1~10μm particles and a water flux ≥300L·m³. -2 ·h -1 .

[0052] 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 separation membrane with a patterned structure, characterized in that, Includes the following steps: S1. Dissolve the aqueous phase reactant monomer and polymer in a solvent to obtain an aqueous phase spinning solution; S2. The aqueous spinning solution obtained in step S1 is sprayed into a jet by a spinning device. The jet is solidified and deposited on a hollow receiving plate after whipping phase separation to obtain a fiber membrane. S3. The aqueous spinning solution obtained in step S1 is converted from a jet stream to jet droplets and sprayed onto the fiber membrane obtained in step S2 to obtain an aqueous liquid membrane. S4. Dissolve the oil-phase reactant monomer in an organic solvent to obtain an oil-phase solution; S5. Using the oil phase interface reaction field control system, the oil phase solution is made to penetrate the hollow receiving plate in the form of an aerosol and sprayed onto the aqueous phase liquid film obtained in step S3, so that the aqueous phase reactant and the oil phase reactant undergo a polymerization reaction at the interface, thereby forming a pattern structure on the fiber membrane. S6. The product with the patterned structure formed in step S5 is dried to obtain a separation membrane with a patterned structure.

2. The preparation method according to claim 1, characterized in that, In the aqueous spinning solution, the concentration of the aqueous reactive monomer is 0.01~4wt%, and the concentration of the polymer is 10~30wt%. The concentration of the oil phase reactant in the oil phase solution is 0.05~5wt%.

3. The preparation method according to claim 1, characterized in that, In step S1, the aqueous phase reaction monomer is a polyamine; The polymer is selected from one or more of the following: polyethylene oxide, polyvinyl chloride, polyvinylidene fluoride, polycarbonate, polymethyl methacrylate, polypropylene terephthalate, polystyrene, polyurethane, polybenzimidazole, polyethylene terephthalate, polycaprolactone, polylactic acid, polyhydroxybutyrate, polyacrylonitrile, polyamide, polyamide imide, polyvinyl alcohol, polyvinyl butyral, polysulfone, polyethyleneimine, or polyimide. The solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, water, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, isobutanol, ethylene glycol, butanediol, hexanediol, or glycerol. In step S4, the oil phase reaction monomer is a polyacryl chloride; The organic solvent is selected from one or more of n-hexane, n-decane, isooctane, or n-heptane.

4. The preparation method according to claim 1, characterized in that, In step S2, the spinning device is either an electrospinning device or an air-jet spinning device. The hollow receiving plate is disposed below the spinning device; The perforated receiving plate has a perforation rate of 60-95%, a hole diameter of 0.3-5mm, and a thickness of 1-3mm; In step S5, the ratio of aqueous phase reactant concentration to oil phase aerosol concentration in the aqueous spinning solution is 0.1:1 to 1:5; the oil phase aerosol spraying rate is 0.1 to 3 mL / h, and the spraying time is 2 to 3 h.

5. The preparation method according to claim 4, characterized in that, In step S2, the electrospinning process of the electrospinning device is as follows: the electrospinning voltage is 10~100kV, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 0.5~10mL / h, and the spinning time is 3~4h. In step S3, the spinning process of changing the aqueous spinning solution from a jet to a droplet is as follows: the electrospinning voltage is 5~50kV, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 1~20mL / h, and the spinning time is 2~3h.

6. The preparation method according to claim 4, characterized in that, In step S2, the spinning process of the air-jet spinning device is as follows: the air-jet spinning airflow velocity is 2~20m / s, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 0.5~10mL / h, and the spinning time is 3~4h. In step S3, the spinning process of changing the aqueous spinning solution from a jet to a droplet is as follows: the air jet spinning airflow velocity is 1~10m / s, the ambient temperature is 10~40℃, the ambient relative humidity is 10~70%, the injection rate is 1~20mL / h, and the spinning time is 1~2h.

7. The preparation method according to claim 1, characterized in that, In step S5, the oil phase interface reaction field control system includes an aerosol generation unit and a directional deposition unit; The aerosol generating unit includes an oil phase storage tank (3), a high-pressure air pump (4), an ultrasonic transducer (5), and an oil phase aerosol tank (6). The directional deposition unit includes a porous capillary nozzle (8); The oil phase storage tank (3) is connected to the high-pressure air pump (4) and the oil phase aerosol tank (6) respectively through pipes; the ultrasonic transducer (5) is installed in the oil phase storage tank (3); the oil phase aerosol tank (6) is connected to the porous capillary nozzle (8) through pipes.

8. The preparation method according to claim 7, characterized in that, The aerosol generating unit also includes an aerosol particle size detector (7) installed in the oil phase aerosol tank (6). The directional deposition unit also includes an aerosol concentration sensor (9) disposed above the porous capillary nozzle (8).

9. A separation membrane having a patterned structure, characterized in that, The separation membrane with the patterned structure is prepared by the method described in any one of claims 1 to 8.

10. An application of the separation membrane with a patterned structure as described in claim 9, characterized in that, The separation membrane with the patterned structure is used in the field of water filtration.

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