A method for preparing a polymer nanoparticle organic framework nanofiltration membrane

Abstract

The application discloses a preparation method of a polymer nanoparticle organic framework nanofiltration membrane. First, a polyamine conjugated polymer nanoparticle is synthesized, then the interface diffusion rate of an aromatic amine monomer is regulated through the interaction between the polyamine conjugated polymer nanoparticle and the aromatic amine monomer, a limited crystallization reaction of a covalent organic framework is induced on the surface interface of the polyamine conjugated polymer nanoparticle, and a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane is formed. Through regulating the limited crystallization reaction conditions of the polyamine conjugated polymer nanoparticle and the COF, the membrane pore structure is optimized, the membrane layer thickness is reduced, the membrane permeability and separation selectivity are simultaneously improved, the membrane exhibits high permeation selectivity and stability in long-term operation, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation, and particularly relates to a method for preparing a polymer nanoparticle organic framework nanofiltration membrane. Background Technology

[0002] Nanofiltration, a membrane separation technology situated between ultrafiltration and reverse osmosis, typically uses membranes with pore sizes ranging from 0.5 to 2 nm. It effectively separates inorganic salt ions of different valence states and small organic molecules of varying molecular weights, finding wide applications in wastewater treatment, biopharmaceuticals, and food processing. Currently, commercially available nanofiltration membranes are primarily produced by interfacial polymerization, forming a polyamide separation layer on a polymer porous support membrane to obtain composite nanofiltration membranes. However, polymer membranes are typically composed of tightly packed polymer molecular chains, resulting in small and widely distributed pore sizes, leading to low permeation flux and poor separation selectivity. Traditional polymer nanofiltration membranes still struggle to overcome the "trade-off" limitation between permeability and separation selectivity. Therefore, there is an urgent need to develop novel polymer membrane-forming materials to prepare high-performance nanofiltration membranes that overcome these problems and meet the separation system requirements of various practical applications.

[0003] In recent years, membrane materials with unique pore structures, such as carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymers with self-contained micropores (PIMs), and covalent organic frameworks (COFs), have attracted widespread research interest. Their application in the preparation of high-performance separation membranes can improve solvent permeability and selective separation of substances. Among these, COFs, as an emerging class of porous materials, are composed of elements such as C, N, and O through covalent bonds. They possess characteristics such as high porosity, regular pore structure, and good stability, and can be used in fields such as gas storage, adsorption, separation, catalysis, and controlled drug release (Science 355, eaal1585, 2017). Currently, the main methods for preparing COF nanofiltration membranes include physical blending, layer-by-layer self-assembly, interfacial polymerization, and in-situ growth. Among these, interfacial polymerization, with its advantages of simple operation, fast film formation rate, and ease of scale-up, is increasingly being used in COF membrane preparation. However, interfacial polymerization methods struggle to precisely control the crystallization growth rate of COFs materials, easily leading to grain boundary defects. The resulting COF membranes typically have pore sizes larger than 1 nm, making precise separation of inorganic salt ions or small organic molecules difficult. Furthermore, the demanding conditions, long reaction times, and reliance on specialized support membrane materials in the preparation of COFs materials and their membranes limit their large-scale fabrication and application. Therefore, there is an urgent need to explore simple and controllable preparation methods for novel COF membrane materials and their nanofiltration membranes, capable of effectively controlling membrane pore structure and properties, and simultaneously improving membrane permeability and separation selectivity.

[0004] This invention proposes a method for preparing hybrid covalent organic framework (COF) nanofiltration membranes using polyamine conjugated polymer nanoparticles as templates via induced interfacial confined crystallization. First, polyamine conjugated polymer nanoparticles are synthesized. Then, the diffusion rate of aromatic amine monomers is restricted through the interaction between the nanoparticles and the aromatic amine monomers, thereby allowing for the confined growth of COF membranes on the surface and at the interface of the polymer nanoparticles. The resulting membrane exhibits a uniform and defect-free COF crystal distribution, a thin membrane thickness, and a pore size less than 1 nm. The COF nanofiltration membrane preparation method provided by this invention is simple and controllable, with mild conditions and a short film formation time, making it suitable for industrial-scale production. The obtained membrane possesses high water permeability and selective separation of organic molecules, making it suitable for the efficient separation, purification, and concentration of biopharmaceutical molecules, and showing promising applications in the food, biopharmaceutical, and chemical industries. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to overcome the shortcomings of existing technologies and provide a method for preparing a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for preparing a polymer nanoparticle organic framework nanofiltration membrane, characterized by comprising the following steps:

[0008] 1) Dissolve 1-3 parts by weight of aromatic amine monomer in 100 parts by weight of acidic / alkaline aqueous solution, then add 0.1-0.3 parts by weight of oxidant to the above aqueous solution, and sonicate for 30-60 minutes to obtain an aqueous dispersion of aromatic amine monomer polyamine conjugated polymer nanoparticles.

[0009] 2) The aqueous dispersion obtained in step 1) is impregnated on the surface of a porous support membrane, and excess aqueous dispersion is removed from the membrane surface to obtain a nanoparticle deposition membrane loaded with aromatic amine monomer polyamine conjugated polymer.

[0010] 3) Pour the organic phase solution containing aldehyde monomers onto the above membrane surface, and remove the excess organic phase solution from the membrane surface by inducing confined crystallization reaction through polyamine conjugated polymer nanoparticles on the membrane surface. Finally, obtain the polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane by heat curing treatment and pure water washing.

[0011] In step 1), the aromatic amine monomer is selected from p-phenylenediamine, benzidine, 4,4'-diamino-3,3'-biphenyl disulfonic acid, or 3,8-diamino-6-phenylaniline; the oxidant in step 1) is selected from dopamine, catecholamine, hydrogen peroxide, ammonium persulfate, ferric chloride, or sodium hypochlorite; the porous support membrane in step 2) is selected from polysulfone membrane, polyethersulfone membrane, polyacrylonitrile membrane, polyvinylidene fluoride membrane, or polytetrafluoroethylene membrane; the aldehyde monomer in step 3) is selected from pyromellitic pyrrolidone, 4,4'-biphenyldicarboxaldehyde, trialdehyde-resorcinol, 2-hydroxy-1,3,5-benzenetrialdehyde, or 1,3,5-tris(p-formylphenyl)benzene; and the solvent in the organic phase solution in step 3) is selected from n-hexane, cyclohexane, n-heptane, or toluene.

[0012] Preferably, the acidic aqueous solution in step 1) is a hydrochloric acid or acetic acid aqueous solution with a mass percentage concentration of 5wt% to 10wt%.

[0013] Preferably, the alkaline aqueous solution in step 1) is an aqueous solution of sodium hydroxide or potassium hydroxide with a mass percentage concentration of 0.01 to 1.0 wt%.

[0014] Preferably, the ultrasonic treatment conditions described in step 1) are 15–35°C and 20–40 kHz.

[0015] Preferably, the water dispersion obtained in step 1) in step 2) is impregnated on the porous support membrane surface under the following conditions: immersion at 15–35°C for 20–40 minutes.

[0016] Preferably, the concentration of the organic phase solution containing aldehyde monomers in step 2) is 0.01 to 0.1 wt% by mass.

[0017] Preferably, the polyamine conjugated polymer nanoparticle-induced confined crystallization reaction conditions on the membrane surface described in step 2) are 15–35°C for 1–30 minutes.

[0018] Preferably, the thermosetting treatment conditions described in step 2) are heating at 60–80°C for 5–30 minutes.

[0019] Preferably, the water rinsing conditions described in step 2) are water rinsing at 15–35°C for 30–60 minutes.

[0020] The prepared polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane can be used in the separation of natural biomolecules of different molecular weights.

[0021] The separation performance testing method of a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane according to the present invention is as follows: The nanofiltration membrane is placed in a conventional nanofiltration testing device in the art. Before testing, the membrane is pre-pressurized at an operating pressure of 0.5 MPa for 1 hour. Then, under test conditions of 25°C and 0.1 MPa, the water permeation flux (J) and the organic molecule rejection rate (R) of the membrane are measured. The calculation formulas are: J = V / (At); R = 1 - C p / C f Where V represents the volume of feed liquid permeating through the membrane, and A represents the effective area of ​​the membrane, which is 22.4 cm². 2 t – runtime, C p - Osmotic concentration, C f - Feed concentration; the concentration of organic molecules in the solution is obtained by measuring the ultraviolet absorbance of the solution.

[0022] In this invention, the separation layer of the polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane is composed of both polyamine conjugated polymer nanoparticles and covalent organic framework materials. Specifically, the polyamine conjugated polymer nanoparticles act as a carrier for aromatic amine monomers, controlling the interfacial diffusion rate of aromatic amine monomers and the rate of confined crystallization reaction of COFs, inhibiting the formation of grain boundary defects, optimizing the pore structure of the COF membrane, and reducing the membrane thickness. The water permeation flux of the polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane prepared by this invention is generally higher than 90 L·m⁻¹. -2 .h -1 .bar -1 The membrane exhibits a retention rate of over 95% for organic molecules (>500 Da), while the retention rate for organic molecules with a molecular weight <300 Da is generally below 20%. Furthermore, the polyamine conjugated polymer nanoparticles can form strong covalent and non-covalent bonds with COF crystalline materials and porous support membranes, giving the membrane both high permeability selectivity and strong structural stability. The membrane demonstrates excellent separation stability and antifouling properties during long-term operation, showing promising prospects for industrial applications. Detailed Implementation

[0023] The following are embodiments of the present invention, but the present invention is not limited to the embodiments:

[0024] Example 1:

[0025] 1 g of p-phenylenediamine monomer was dissolved in 100 g of 0.01 wt% sodium hydroxide aqueous solution, and then 0.1 g of dopamine was added to the above aqueous solution. After ultrasonic treatment at 15 °C and 20 kHz for 30 minutes, an aqueous dispersion of p-phenylenediamine-loaded polyamine conjugated polymer nanoparticles was obtained. The above dispersion was immersed on the surface of a polysulfone membrane at 15 °C for 20 minutes. Excess aqueous dispersion on the membrane surface was removed to obtain a deposited membrane of p-phenylenediamine-loaded polyamine conjugated polymer nanoparticles. Then, a hexane solution containing 0.01 wt% trimesaldehyde monomer was poured onto the above membrane surface to induce the covalent organic framework material to undergo a confined crystallization reaction at 15 °C for 1 minute. Excess hexane solution on the membrane surface was removed. After heat curing at 60 °C for 5 minutes, the membrane was finally washed in pure water at 15 °C for 30 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0026] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 110.0 Lm. -2 .h -1 The retention rates for chlorophyll and artemisinin were 98% and 14.2%, respectively.

[0027] Example 2:

[0028] 3g of p-phenylenediamine monomer was dissolved in 100g of 1wt% sodium hydroxide aqueous solution, and then 0.3g of dopamine was added to the above aqueous solution. After ultrasonic treatment at 35℃ and 40kHz for 60 minutes, an aqueous dispersion of p-phenylenediamine-loaded polyamine conjugated polymer nanoparticles was obtained. The above dispersion was immersed on the surface of a polysulfone membrane at 35℃ for 40 minutes. Excess aqueous dispersion on the membrane surface was removed to obtain a deposited membrane of p-phenylenediamine-loaded polyamine conjugated polymer nanoparticles. Then, a hexane solution containing 0.1wt% trimesaldehyde monomer was poured onto the above membrane surface to induce the covalent organic framework material to undergo a confined crystallization reaction at 35℃ for 30 minutes. Excess hexane solution on the membrane surface was removed. After heat curing treatment at 80℃ for 30 minutes, the membrane was finally washed in pure water at 35℃ for 60 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0029] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 91.0 Lm. -2 .h -1 The retention rates for chlorophyll and artemisinin were 99% and 17.6%, respectively.

[0030] Example 3:

[0031] 1 g of p-phenylenediamine monomer was dissolved in 100 g of 0.02 wt% sodium hydroxide aqueous solution, and then 0.2 g of dopamine was added to the above aqueous solution. After ultrasonic treatment at 20 °C and 25 kHz for 40 minutes, an aqueous dispersion of p-phenylenediamine-loaded polyamine conjugated polymer nanoparticles was obtained. The above dispersion was immersed on the surface of a polysulfone membrane at 20 °C for 20 minutes. Excess aqueous dispersion on the membrane surface was removed to obtain a deposited membrane of p-phenylenediamine-loaded polyamine conjugated polymer nanoparticles. Then, a hexane solution containing 0.02 wt% trimesaldehyde monomer was poured onto the above membrane surface to induce the covalent organic framework material to undergo a confined crystallization reaction at 25 °C for 2 minutes. Excess hexane solution on the membrane surface was removed. After heat curing treatment at 60 °C for 5 minutes, the membrane was finally washed in pure water at 20 °C for 30 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0032] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 101.0 Lm. -2 .h -1 The retention rates for chlorophyll and artemisinin were 99% and 12%, respectively.

[0033] Comparative Example 1

[0034] Following the steps in Example 3, a covalent organic framework separation membrane was prepared directly from p-phenylenediamine and pyromellitic methyl ether as raw materials through interfacial polymerization (preparation conditions refer to Example 3).

[0035] Comparative Example 2

[0036] Following the steps in Example 3, a conjugated polymer separation membrane was prepared directly from conjugated polymer nanoparticles and pyromellitic trimethylolpropionate as raw materials through interfacial polymerization (preparation conditions as described in Example 3).

[0037] Table 1. Comparison of membrane separation selectivity prepared in Example 3 and Comparative Examples 1-2

[0038]

[0039] The results in Table 1 show that the separation membranes prepared by the three methods have significant differences in the retention rate of natural biomolecules and water flux, which is due to the different chemical composition and microstructure of the membrane-forming materials.

[0040] In Comparative Example 1, no conjugated polymer nanoparticles were added; instead, interfacial polymerization was directly performed using aromatic amine monomers and aldehyde monomers. The aromatic amine monomers diffused rapidly, resulting in a fast crystallization growth rate of the covalent organic framework material. The resulting membrane was too dense, with a high rejection rate for small biological molecules, making precise separation difficult. At the same time, the membrane water flux was low. In Comparative Example 2, interfacial polymerization was directly performed using conjugated polymer nanoparticles and aldehyde monomers. Since the nanoparticles were not loaded with aromatic amine monomers, no covalent organic framework material was formed inside the membrane. This resulted in a larger membrane pore size and increased water flux. However, the selectivity for the rejection and separation of biomolecules was significantly reduced.

[0041] In Example 3, polyamine conjugated polymer nanoparticles loaded with aromatic amine monomers were used to induce confined crystallization of covalent organic frameworks (COFs), forming a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane. The polyamine conjugated polymer nanoparticles, acting as a carrier for the aromatic amine monomers, controlled the interfacial diffusion rate of the aromatic amine monomers and the rate of confined crystallization reaction in the COFs, inhibited the formation of grain boundary defects, optimized the COF membrane pore structure, and reduced the membrane thickness. This achieved a simultaneous improvement in membrane water permeability and the selectivity for organic molecule separation, demonstrating promising application prospects in the separation and purification of biopharmaceutical molecules.

[0042] Example 4:

[0043] 2 g of 3,8-diamino-6-phenylaniline monomer was dissolved in 100 g of 0.05 wt% potassium hydroxide solution. Then, 0.2 g of catecholamine was added to the aqueous solution. After ultrasonic treatment at 25 °C and 30 kHz for 55 minutes, an aqueous dispersion of polyamine conjugated polymer nanoparticles loaded with 3,8-diamino-6-phenylaniline was obtained. The dispersion was then immersed on the surface of a polyethersulfone membrane at 30 °C for 30 minutes. Excess aqueous dispersion was removed from the membrane surface to obtain a polyamine conjugated polymer nanoparticle deposition membrane loaded with 3,8-diamino-6-phenylaniline. A cyclohexane solution containing 0.02 wt% trialdehyde resorcinol monomer was poured onto the membrane surface to induce confined crystallization of the covalent organic framework material at 25 °C for 5 minutes. Excess cyclohexane solution was removed from the membrane surface. The membrane was then heat-cured at 60 °C for 10 minutes and finally washed in pure water at 25 °C for 45 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0044] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 99.0 Lm. -2 .h -1 The retention rates for chlorophyll and artemisinin were 99% and 13.5%, respectively.

[0045] Example 5:

[0046] 1.5 g of benzidine monomer was dissolved in 100 g of 5.5 wt% acetic acid solution, and then 0.2 g of hydrogen peroxide was added to the aqueous solution. After ultrasonic treatment at 25 °C and 40 kHz for 35 minutes, an aqueous dispersion of benzidine-loaded polyamine conjugated polymer nanoparticles was obtained. The dispersion was then immersed on the surface of a polyacrylonitrile membrane at 25 °C for 25 minutes. Excess aqueous dispersion was removed from the membrane surface to obtain a benzidine-loaded polyamine conjugated polymer nanoparticle deposited membrane. A toluene solution containing 0.1 wt% 4,4'-biphenyldicarboxaldehyde was poured onto the membrane surface, and a confined crystallization reaction was induced in a covalent organic framework material at 35 °C for 10 minutes to remove excess toluene solution from the membrane surface. The membrane was then heat-cured at 80 °C for 15 minutes and finally washed in pure water at 25 °C for 60 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0047] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 101.0 Lm. -2 .h -1 The retention rates for chlorophyll and artemisinin were 97.7% and 9.4%, respectively.

[0048] Example 6:

[0049] 2g of benzidine monomer was dissolved in 100g of 5wt% hydrochloric acid solution, and then 0.25g of ammonium persulfate was added to the aqueous solution. After ultrasonic treatment at 25℃ and 30kHz for 30 minutes, an aqueous dispersion of benzidine-loaded polyamine conjugated polymer nanoparticles was obtained. The dispersion was then immersed on the surface of a polyvinylidene fluoride membrane at 30℃ for 30 minutes. Excess aqueous dispersion was removed from the membrane surface to obtain a benzidine-loaded polyamine conjugated polymer nanoparticle deposited membrane. A cyclohexane solution containing 0.05wt% 2-hydroxy-1,3,5-benzenetriformaldehyde was poured onto the membrane surface to induce confined crystallization of the covalent organic framework material at 25℃ for 10 minutes. Excess cyclohexane solution was removed from the membrane surface. The membrane was then heat-cured at 60℃ for 10 minutes and finally washed in pure water at 20℃ for 45 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0050] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 105 L / m. -2 .h-1 The retention rates of chlorophyll and artemisinin were 98.7% and 10.3%, respectively.

[0051] Example 7:

[0052] 1.5 g of 3,8-diamino-6-phenylaniline monomer was dissolved in 100 g of 8 wt% hydrochloric acid aqueous solution. Then, 0.22 g of ferric chloride was added to the aqueous solution. After ultrasonic treatment at 25 °C and 25 kHz for 50 minutes, an aqueous dispersion of polyamine conjugated polymer nanoparticles loaded with 3,8-diamino-6-phenylaniline was obtained. The dispersion was then impregnated onto the surface of a polyacrylonitrile membrane at 25 °C for 25 minutes. Excess aqueous dispersion was removed from the membrane surface to obtain the 3,8-diamino-6-phenylaniline-loaded polyamine conjugated polymer nanoparticles. A polyamine conjugated polymer nanoparticle membrane with 6-phenylaniline was deposited. Then, a heptane solution containing 0.05 wt% 2-hydroxy-1,3,5-benzenetriformaldehyde was poured onto the surface of the membrane to induce confined crystallization of the covalent organic framework material at 25 °C for 5 minutes. The excess heptane solution on the membrane surface was removed, and the membrane was heat-cured at 70 °C for 10 minutes. Finally, it was washed in pure water at 25 °C for 50 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0053] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 100 L / m. -2 .h -1 The retention rates of chlorophyll and artemisinin were 96% and 15.6%, respectively.

[0054] Example 8:

[0055] 3 g of 4,4'-diamino-3,3'-biphenyl disulfonic acid was dissolved in 100 g of 7 wt% hydrochloric acid solution. Then, 0.3 g of sodium hypochlorite amine was added to the aqueous solution. After ultrasonic treatment at 25 °C and 30 kHz for 40 minutes, an aqueous dispersion of polyamine conjugated polymer nanoparticles loaded with 4,4'-diamino-3,3'-biphenyl disulfonic acid was obtained. The dispersion was then impregnated onto the surface of a polytetrafluoroethylene membrane at 25 °C for 30 minutes. Excess aqueous dispersion was removed from the membrane surface to obtain the 4,4'-diamino-3,3'-biphenyl disulfonic acid-loaded polyamine conjugated polymer nanoparticles. A polyamine conjugated polymer nanoparticle membrane was deposited using '-diamino-3,3'-biphenyl disulfonic acid. Then, a toluene solution containing 0.05 wt% 1,3,5-tris(p-formylphenyl)benzene was poured onto the membrane surface to induce confined crystallization of the covalent organic framework material at 25°C for 5 minutes. Excess toluene solution was removed from the membrane surface, followed by heat curing at 60°C for 25 minutes. Finally, the membrane was washed in pure water at 25°C for 30 minutes to obtain a polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane.

[0056] A polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane was used at 25 °C and 0.1 MPa pressure for 0.05 g / L of [aluminum / water / oil]. -1 The filtration separation efficiency of the chlorophyll and artemisinin solution was as follows: water flux was 98 L / m. -2 .h -1 The retention rates of chlorophyll and artemisinin were 97% and 13.7%, respectively.

Claims

1. A method for preparing a polymer nanoparticle organic framework nanofiltration membrane, characterized in that: Includes the following steps: 1) Dissolve 1-3 parts by weight of aromatic amine monomer in 100 parts by weight of acidic or alkaline aqueous solution, then add 0.1-0.3 parts by weight of oxidant to the above aqueous solution, and sonicate for 30-60 minutes to obtain an aqueous dispersion of aromatic amine monomer polyamine conjugated polymer nanoparticles; wherein the acidic aqueous solution is a hydrochloric acid or acetic acid aqueous solution with a mass percentage concentration of 5wt%-10wt%; and the alkaline aqueous solution is a sodium hydroxide or potassium hydroxide aqueous solution with a mass percentage concentration of 0.01-1.0wt%. 2) The aqueous dispersion obtained in step 1) is impregnated on the surface of a porous support membrane, and excess aqueous dispersion is removed from the membrane surface to obtain a nanoparticle deposition membrane loaded with aromatic amine monomer polyamine conjugated polymer. 3) Pour the organic phase solution containing aldehyde monomers onto the above membrane surface, and remove the excess organic phase solution from the membrane surface by inducing confined crystallization reaction through polyamine conjugated polymer nanoparticles on the membrane surface. Finally, obtain the polyamine conjugated polymer nanoparticle hybrid covalent organic framework nanofiltration membrane by heat curing treatment and pure water washing. In step 1), the aromatic amine monomer is selected from p-phenylenediamine, benzidine, 4,4'-diamino-3,3'-biphenyl disulfonic acid, or 3,8-diamino-6-phenylaniline; when the aromatic amine monomer is dissolved in an acidic solution, the oxidant is selected from hydrogen peroxide, ammonium persulfate, ferric chloride, or sodium hypochlorite; when the aromatic amine monomer is dissolved in an alkaline solution, the oxidant is catecholamine; in step 2), the porous support membrane is selected from polysulfone membrane, polyethersulfone membrane, polyacrylonitrile membrane, polyvinylidene fluoride membrane, or polytetrafluoroethylene membrane; in step 3), the aldehyde monomer is selected from pyromellitic methyl ether, 4,4'-biphenyldimethyl ether, trialdehyde-resorcinol, 2-hydroxy-1,3,5-benzenetriformaldehyde, or 1,3,5-tris(p-formylphenyl)benzene; and in step 3), the organic phase solution solvent is selected from n-hexane, cyclohexane, n-heptane, or toluene.

2. The method for preparing the polymer nanoparticle organic framework nanofiltration membrane as described in claim 1, characterized in that: The ultrasonic treatment conditions described in step 1) are 15–35°C and 20–40 kHz.

3. The method for preparing the polymer nanoparticle organic framework nanofiltration membrane as described in claim 1, characterized in that: The aqueous dispersion obtained in step 1) is impregnated on the surface of the porous support membrane in step 2) at 15-35°C for 20-40 minutes.

4. The method for preparing the polymer nanoparticle organic framework nanofiltration membrane as described in claim 1, characterized in that: The organic phase solution containing aldehyde monomers mentioned in step 3) has a concentration of 0.01 to 0.1 wt% by mass.

5. The method for preparing the polymer nanoparticle organic framework nanofiltration membrane as described in claim 1, characterized in that: The polyamine conjugated polymer nanoparticle-induced confined crystallization reaction on the membrane surface described in step 3) is carried out at 15–35 °C for 1–30 minutes.

6. The method for preparing the polymer nanoparticle organic framework nanofiltration membrane as described in claim 1, characterized in that: The thermosetting treatment described in step 3) is performed by heating at 60–80°C for 5–30 minutes.

7. The method for preparing the polymer nanoparticle organic framework nanofiltration membrane as described in claim 1, characterized in that: The pure water rinsing described in step 3) is performed at 15–35°C for 30–60 minutes.

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