Thiazole-linked covalent organic framework nanofiltration membranes, their preparation methods and applications

Abstract

This invention relates to a thiazole-linked covalent organic framework nanofiltration membrane, its preparation method, and its applications. Using amphiphilic sulfur-containing amine monomers and aldehyde monomers as interfacial polymerization monomers, a covalent organic framework nanofiltration membrane with thiazole bonds as the connecting structural units is obtained through liquid-liquid free interface polymerization. The thiazole bond as the connecting unit improves the separation selectivity and acid resistance of the COF membrane. The thiazole-linked covalent organic framework nanofiltration membrane achieves a desalination selectivity of 690 and can be stably stored in 12M HCl for extended periods. It maintains excellent structural stability and can operate stably and be stored long-term under harsh conditions such as mechanical stress, high temperature, and strong corrosion. It can be used for membrane separation needs in neutral or strongly acidic environments.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, and in particular relates to a thiazole-linked covalent organic framework nanofiltration membrane, its preparation method, and its application. Background Technology

[0002] Molecular desalination and separation under strong acid conditions have wide applications in the new energy, chemical, and pharmaceutical industries, involving multiple fields such as acid recovery, acid purification, resource extraction, and wastewater reuse. Existing technologies such as ion exchange and electrodialysis generally suffer from low efficiency, high energy consumption, and poor material stability under strong acid conditions, resulting in insufficient separation selectivity and long-term durability. Membrane separation technology, based on differences in molecular size and shape and membrane-permeate interactions, offers an ideal approach for sustainable liquid filtration due to its advantages such as high energy efficiency, simple operation, and miniaturization. However, the application of molecular desalination under strong acid conditions is significantly limited by the scarcity of effective membrane materials, which need to possess soluble processability, permeate selectivity, and chemical stability.

[0003] Covalent organic frameworks (COFs), as crystalline porous materials linked by covalent bonds, have shown great potential in membrane separation under harsh conditions due to their periodically ordered pore structure, tunable chemical environment, and good chemical stability. However, maintaining the integrity of the micro and macroscopic structures of COF films in strongly acidic environments remains a significant challenge. Even local bond breakage or slight stacking separation can lead to membrane structure collapse and ultimately loss of separation selectivity. This instability stems from the inherent dynamic characteristics of COF materials: for example, the high nucleophilicity of reversible imine bonds makes them susceptible to proton-induced framework degradation; the limited π-conjugated system results in weak interlayer π-π interactions, easily causing COF layer loosening or slippage. Although various modification strategies have been developed (including reducing the nucleophilic activity of C=N bonds, enhancing intramolecular / interlayer hydrogen bonding, optimizing molecular docking, and utilizing resonance stabilization), these methods have failed to fundamentally alter the dynamic characteristics of COF materials. Therefore, COF membrane materials that can withstand strongly acidic environments while maintaining intact mass transfer channels remain extremely rare.

[0004] Studies have shown that the specific interactions between heteroatoms and permeates in the COF framework are crucial for transmembrane mass transfer. However, nitrogen atoms in traditional imine bonds are embedded within the framework, limiting their accessibility to solvents and solutes. While introducing side-chain groups such as sulfonic acid groups can improve permeate selectivity in existing technologies, these modified groups often suffer from insufficient chemical stability in strongly acidic environments. Developing acid-environment-specific membrane materials that combine high chemical stability, excellent separation selectivity, and scalable fabrication remains a key scientific challenge in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a thiazole-linked covalent organic framework nanofiltration membrane, its preparation method, and its applications.

[0006] The technical solution adopted in this invention is: a method for preparing a thiazole-linked covalent organic framework nanofiltration membrane, which uses amphiphilic sulfur-containing amine monomers and aldehyde monomers as interfacial polymerization monomers to obtain a thiazole-linked covalent organic framework nanofiltration membrane by polymerization at a liquid-liquid free interface.

[0007] Preferably, the amine monomer is 2,5-diamino-1,4-benzenedithiol dihydrochloride, and the aldehyde monomer is 1,3,5-benzenetriformaldehyde or 1,3,5-tris(p-formylphenyl)benzene (TFPB).

[0008] Preferably, the molar ratio of amine monomer to aldehyde monomer is 1:0.4-0.9; more preferably, it is 1:0.67.

[0009] Preferably, the specific preparation method is as follows:

[0010] Step 1: Dissolve the amine monomer in 1 volume of N,N-dimethylformamide, and then add 4 volumes of water to form a clear mixed solvent as an aqueous solution; dissolve the aldehyde monomer and catalyst in an organic solvent to obtain an organic solution.

[0011] Step 2: First, inject an aqueous phase solution into the reaction vessel, then inject an organic phase solution to form a stable interface. Allow the interface polymerization reaction to proceed at room temperature for 2-7 days to form a thiazole-linked covalent organic framework nanofiltration membrane at the interface.

[0012] Preferably, when the aldehyde monomer is 1,3,5-benzenetriformaldehyde, the catalyst is nonanoic acid and the organic solvent is mesitylene; when the aldehyde monomer is 1,3,5-tris(p-formylphenyl)benzene, the catalyst is acetic acid and the organic solvent is dichloromethane.

[0013] Preferably, the concentration of the amine monomer in the aqueous solution is 0.5-2 mM.

[0014] Preferably, the concentration of aldehyde monomer in the organic phase solution is 0.33-1.33 mM, and the concentration of catalyst is 200-700 mM.

[0015] A thiazole-linked covalent organic framework nanofiltration membrane prepared by a method for preparing thiazole-linked covalent organic framework nanofiltration membranes.

[0016] Application of thiazole-linked covalent organic framework nanofiltration membranes in membrane separation technology materials.

[0017] Preferably, it is used for molecular desalination, resource extraction, resource purification, or wastewater recycling in neutral or acidic environments.

[0018] The advantages and positive effects of this invention are: the thiazole-linked covalent organic framework nanofiltration membrane has excellent permeation selectivity and outstanding acid resistance. The obtained membrane material can still operate stably and be stored for a long time under harsh conditions such as mechanical stress, high temperature, and strong corrosion, maintaining excellent structural stability. The preparation process of the thiazole-linked covalent organic framework nanofiltration membrane is simple, and it has both universality and scalability, making it easy to promote in industry. Attached Figure Description

[0019] Figure 1 SEM image of a thiazole-linked COF membrane;

[0020] Figure 2 Thiazole-linked COF membranes 13 C ssNMR characterization results;

[0021] Figure 3 Comparison of pure water flux between thiazole-linked COF membranes and imine-linked COF membranes;

[0022] Figure 4 Comparison of selectivity factors for ceftriaxone / sodium chloride binary separation systems using thiazole-linked COF membranes and imine-linked COF membranes;

[0023] Figure 5 Comparison of the retention rates of Eriochrome Black T by thiazole-linked COF membranes and imine-linked COF membranes after immersion in 12M hydrochloric acid for different times. Detailed Implementation

[0024] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0025] This invention relates to a thiazole-linked covalent organic framework (COF) nanofiltration membrane, its preparation method, and its application. A COF membrane with thiazole bonds as the connecting structural units is constructed. Amphiphilic sulfur-containing amine monomers and aldehyde monomers are used as interfacial polymerization monomers. A Schiff base reaction occurs at the liquid-liquid free interface to polymerize the thiazole-linked COF nanofiltration membrane.

[0026] The specific steps for using a thiazole-linked covalent organic framework nanofiltration membrane are as follows:

[0027] Step 1: Dissolve the amphiphilic sulfur-containing amine monomer in 1 volume of N,N-dimethylformamide and sonicate until homogeneous. Then add 4 volumes of water to form a clear mixed solvent to obtain an aqueous solution. The concentration of the sulfur-containing amine monomer in the aqueous solution is 0.5-2 mM.

[0028] The aldehyde monomer and the catalyst are dissolved in an organic solvent to obtain an organic phase solution; the concentration of the aldehyde monomer in the organic phase solution is 0.33-1.33 mM, and the concentration of the catalyst is 200-700 mM; the molar ratio of the amine monomer to the aldehyde monomer is 1:0.4-0.9; preferably 1:0.67.

[0029] The amine monomer is 2,5-diamino-1,4-benzenedithiol dihydrochloride (Ba), and the aldehyde monomer is 1,3,5-benzenetriformaldehyde (Tb) or 1,3,5-tris(p-formylphenyl)benzene (TFPB). When the aldehyde monomer is 1,3,5-benzenetriformaldehyde, the catalyst is nonanoic acid, and the organic solvent is mesitylene. When the aldehyde monomer is 1,3,5-tris(p-formylphenyl)benzene, the catalyst is acetic acid, and the organic solvent is dichloromethane.

[0030] Step 2: First, inject an aqueous solution into a glass container, then inject an organic solution to form a stable interface and carry out an interfacial polymerization reaction. Let the reaction stand at room temperature for 3-7 days to form a self-supporting thiazole-linked covalent organic framework nanofiltration membrane at the interface, which appears as a yellow thin film.

[0031] Step 3: After the interfacial polymerization reaction is completed, the thiazole-linked covalent organic framework nanofiltration membrane at the interface is collected. Unreacted sulfur-containing amine monomers and aldehyde monomers are removed by washing three times with N,N-dimethylformamide and methanol. The self-supported thiazole-linked covalent organic framework nanofiltration membrane is then transferred to a support substrate and dried for 12 hours.

[0032] The thiazole bond, as a key structural unit, enables the organic combination of heteroatom spatial exposure and a fully conjugated framework structure. This structure not only enhances bonding and stacking energies but also strengthens atomic-level hydration, driving the formation of a lone pair electron network within the channel. These synergistic effects collectively improve the separation selectivity and acid resistance of the COF membrane. Testing revealed that the prepared thiazole-linked covalent organic framework nanofiltration membrane achieved a desalination selectivity of 690 and could be stably stored for an extended period in 12M HCl.

[0033] Aromatic heterocyclic thiazoles were used as connecting units to construct fully π-conjugated COF materials. Density functional theory calculations showed that the thiazole bonds possess intrinsically high bond energies (5.39-9.42 eV), significantly superior to imine bonds (4.23-7.83 eV) and β-keto-enamine bonds (4.77-8.16 eV), and the fully π-conjugated framework significantly improved the interlayer π-π stacking efficiency. Simultaneously, the thiazole bonds exposed amphiphilic heteroatoms (N, S) within the pores; these negatively charged active sites could regulate mass transport and induce localized ordered water molecule arrangement at the liquid-COF interface, thereby protecting the framework from proton attack. This unique thiazole-linked fully π-conjugated framework structure can simultaneously improve the separation performance and chemical stability of COF membranes in the desalination of strong acids.

[0034] This preparation method is both universal and scalable, capable of producing nanofiltration membranes with diameters exceeding 20 cm. The resulting membrane material maintains excellent structural stability and can be stably operated and stored for extended periods under harsh conditions such as mechanical stress, high temperature, and strong corrosion. The prepared thiazole-linked covalent organic framework nanofiltration membrane can be used in membrane separation technologies for molecular desalination, resource extraction, wastewater reuse, and resource purification in strongly acidic or neutral environments.

[0035] The present invention will now be described with reference to the accompanying drawings. Experimental methods not specifically described in terms of operation steps are performed in accordance with the corresponding product manuals. Unless otherwise specified, the instruments, reagents, and consumables used in the embodiments can be purchased from commercial companies.

[0036] Example 1:

[0037]

[0038] 2,5-Diamino-1,4-benzenedithiol dihydrochloride (Ba) monomer was dissolved in N,N-dimethylformamide at a concentration of 1 mM. The solution was sonicated for 10 minutes to ensure complete dissolution, and then 4 times the volume of ultrapure water was added to obtain an aqueous solution.

[0039] 1,3,5-Benztriformaldehyde (Tb) monomer and nonanoic acid were dissolved in mesitylene, with a Tb concentration of 0.67 mM and a nonanoic acid concentration of 500 mM. The mixture was sonicated for 15 minutes to ensure complete dissolution of all components, thus obtaining an organic phase solution.

[0040] The organic and aqueous phase solutions were sequentially injected into the reaction vessel, forming a stable interface through layering. The reaction was allowed to proceed for 3 days, resulting in a yellow film at the interface. After the reaction was complete, the thiazole-linked covalent organic framework (COF) nanofiltration membrane at the interface was collected. Unreacted sulfur-containing amine and aldehyde monomers were removed by washing three times with N,N-dimethylformamide and methanol. The thiazole-linked COF membrane was then transferred to a supporting substrate and dried for 12 hours to obtain a thiazole-linked COF membrane suitable for nanofiltration separation.

[0041] The microstructure and structure of the prepared thiazole-linked COF membrane were characterized, and the results are as follows: Figure 1 Figure 2 As shown in the figure. SEM reveals that the thiazole-linked COF membrane has a good membrane morphology, proving that the thiazole COF units are grown in a large-area, long-range manner to form a continuous film. SSNMR confirms that the thiazole-linked COF membrane has the expected framework chemical structure, confirming it as a thiazole-linked structure.

[0042] Example 2:

[0043] 2,5-Diamino-1,4-benzenedithiol dihydrochloride (Ba) monomer was dissolved in N,N-dimethylformamide at a concentration of 0.5 mM. The solution was sonicated for 10 minutes to ensure complete dissolution. Then, 4 times the volume of ultrapure water was added to prepare an aqueous solution.

[0044] 1,3,5-Benztriformaldehyde (Tb) monomer and nonanoic acid were dissolved in mesitylene, with a Tb concentration of 0.33 mM and a nonanoic acid concentration of 200 mM. The mixture was sonicated for 15 minutes to ensure complete dissolution of all components, thus obtaining an organic phase solution.

[0045] The organic and aqueous phase solutions were sequentially injected into the reaction vessel, forming a stable interface through layering. The reaction was allowed to proceed for 3 days, resulting in a yellow film at the interface. After the reaction was complete, the thiazole-linked covalent organic framework (COF) nanofiltration membrane at the interface was collected. Unreacted sulfur-containing amine and aldehyde monomers were removed by washing three times with N,N-dimethylformamide and methanol. The thiazole-linked COF membrane was then transferred to a supporting substrate and dried for 12 hours to obtain a thiazole-linked COF membrane suitable for nanofiltration separation.

[0046] Example 3:

[0047] 2,5-Diamino-1,4-benzenedithiol dihydrochloride (Ba) monomer was dissolved in N,N-dimethylformamide at a concentration of 1.5 mM. The solution was sonicated for 10 minutes to ensure complete dissolution, and then 4 times the volume of ultrapure water was added to obtain an aqueous solution.

[0048] 1,3,5-Benztriformaldehyde (Tb) monomer and nonanoic acid were dissolved in mesitylene, with a Tb concentration of 1.0 mM and a nonanoic acid concentration of 400 mM. The mixture was sonicated for 15 minutes to ensure complete dissolution of all components, thus obtaining an organic phase solution.

[0049] The organic and aqueous phase solutions were sequentially injected into the reaction vessel, forming a stable interface through layering. The reaction was allowed to proceed for 3 days, resulting in a yellow film at the interface. After the reaction was complete, the thiazole-linked covalent organic framework (COF) nanofiltration membrane at the interface was collected. Unreacted sulfur-containing amine and aldehyde monomers were removed by washing three times with N,N-dimethylformamide and methanol. The thiazole-linked COF membrane was then transferred to a supporting substrate and dried for 12 hours to obtain a thiazole-linked COF membrane suitable for nanofiltration separation.

[0050] Example 4:

[0051] 2,5-Diamino-1,4-benzenedithiol dihydrochloride (Ba) monomer was dissolved in N,N-dimethylformamide at a concentration of 2 mM. The solution was sonicated for 10 minutes to ensure complete dissolution, and then 4 times the volume of ultrapure water was added to obtain an aqueous solution.

[0052] 1,3,5-Benzenetriformaldehyde (Tb) monomer and nonanoic acid were dissolved in mesitylene, with a Tb concentration of 1.33 mM and a nonanoic acid concentration of 700 mM. The mixture was sonicated for 15 minutes to ensure complete dissolution of all components, thus obtaining an organic phase solution.

[0053] The organic and aqueous phase solutions were sequentially injected into the reaction vessel, forming a stable interface through layering. The reaction was allowed to proceed for 3 days, resulting in a yellow film at the interface. After the reaction was complete, the thiazole-linked covalent organic framework (COF) nanofiltration membrane at the interface was collected. Unreacted sulfur-containing amine and aldehyde monomers were removed by washing three times with N,N-dimethylformamide and methanol. The thiazole-linked COF membrane was then transferred to a supporting substrate and dried for 12 hours to obtain a thiazole-linked COF membrane suitable for nanofiltration separation.

[0054] Comparative example:

[0055] p-phenylenediamine (Pa) was dissolved in N,N-dimethylformamide at a concentration of 1.5 mM. After sonication for 10 min, ultrapure water was added to prepare an aqueous solution.

[0056] 1,3,5-Benzenetriformaldehyde (Tb) and nonanoic acid were dissolved in mesitylene, with Tb concentration of 1 mM and nonanoic acid concentration of 50 mM. The mixture was sonicated for 15 minutes to ensure complete dissolution of all components, thus obtaining an organic phase solution.

[0057] The organic and aqueous phase solutions were sequentially injected into the reaction vessel, where they separated to form a stable interface. After two days of reaction, a brown film formed at the interface. Once the reaction was complete, unreacted sulfur-containing amine and aldehyde monomers were removed by washing three times with N,N-dimethylformamide and methanol. The self-supported imine-linked COF membrane was then transferred to a supporting substrate and dried for 12 hours to obtain an imine-linked COF membrane suitable for nanofiltration separation.

[0058] Example 5: Performance comparison of thiazole-linked COF membranes and imine-linked COF membranes

[0059] 5.1 Comparison of Permeability Performance

[0060] The pure water flux of the thiazole-linked COF membrane prepared in Example 1 and the imine-linked COF membrane prepared in the comparative example was compared.

[0061] Two COF membranes were transferred onto a 0.22 μm pore size polyethersulfone (PES) microfiltration membrane support substrate and cut into circular or square membrane sheets to fit the membrane cell size. The membrane sheets were installed in dead-end or cross-flow filtration devices, with deionized water as the feed solution. Before testing, the membrane layers were compacted at 2 bar for 0.5 h until flux stability was achieved, and then the pure water flux was tested at 2 bar. The results are as follows: Figure 3 As shown, tests revealed that the flux of the thiazole-linked COF membrane reached 95.8 LMH MPa. -1The imine-linked COF membrane (56.9 LMH MPa) -1 The permeability of the thiazole-linked COF membrane increased by 68.4%, confirming that the permeability of the COF membrane linked by thiazole is much higher than that of the COF membrane linked by imine.

[0062] 5.2 Comparison of Separation Performance

[0063] The separation capabilities of the thiazole-linked COF membrane prepared in Example 1 and the imine-linked COF membrane prepared in the comparative example in the ceftriaxone / sodium chloride system were compared. Both COF membranes were transferred to a 0.22 μm pore size polyethersulfone (PES) microfiltration membrane support substrate and cut into circular or square membrane sheets to fit the membrane cell size. The membrane sheets were installed in dead-end or cross-flow filtration devices, with an aqueous solution containing ions and molecules as the feed. Before testing, the membrane layers were compacted at 2 bar for 0.5 h until the flux stabilized, and then the pure water flux was tested at 2 bar.

[0064] The test results of the molecular / salt binary system are as follows: Figure 4 As shown, the thiazole-linked COF membrane achieved a separation factor of 690.0 in the ceftriaxone / sodium chloride binary separation system, which is significantly better than the imine-linked COF membrane (the separation factor in the ceftriaxone / sodium chloride binary separation system is 10.67).

[0065] 5.3 Membrane stability analysis

[0066] The stability of the thiazole-linked COF membrane prepared in Example 1 and the imine-linked COF membrane prepared in the comparative example were compared. Both were immersed in 12M HCl for a period of time, and the integrity of the COF membrane and the retention rate of Eriochrome Black T molecules were measured. The results are as follows: Figure 5 As shown, the thiazole-linked COF membrane maintained its structural integrity after immersion in 12M HCl for 504 hours, with a molecular rejection rate consistently above 99.2%, indicating that its mass transfer channels remained intact under strongly acidic conditions. In contrast, the molecular rejection rate of the imine-linked COF membrane decreased significantly from 99.9% to 64.5% after immersion in 12M HCl for 504 hours, confirming that its channel structure suffered irreversible damage and lost its molecular sieving ability. The thiazole-linked COF membrane exhibits superior stability under strongly acidic conditions compared to the imine-linked COF membrane.

[0067] Through the above experimental comparisons, the thiazole-linked COF membrane exhibits excellent permeation selectivity and acid resistance.

[0068] Example 6:

[0069] 2,5-Diamino-1,4-benzenedithiol dihydrochloride (Ba) monomer was dissolved in N,N-dimethylformamide at a concentration of 2 mM. The solution was sonicated for 10 minutes to ensure complete dissolution, and then 4 times the volume of ultrapure water was added to obtain an aqueous solution.

[0070] 1,3,5-tris(p-formylphenyl)benzene (TFPB) monomer and acetic acid were dissolved in dichloromethane at a concentration of 1.33 mM and a concentration of acetic acid of 200 mM. The mixture was sonicated for 15 minutes to ensure complete dissolution of all components, thus obtaining an organic phase solution.

[0071] The organic and aqueous phase solutions were sequentially injected into the reaction vessel, forming a stable interface through layering. The reaction was allowed to proceed for 3 days, resulting in a yellow film at the interface. After the reaction was complete, the thiazole-linked covalent organic framework (COF) nanofiltration membrane at the interface was collected. Unreacted sulfur-containing amine and aldehyde monomers were removed by washing three times with N,N-dimethylformamide and methanol. The thiazole-linked COF membrane was then transferred to a supporting substrate and dried for 12 hours to obtain a thiazole-linked COF membrane suitable for nanofiltration separation.

[0072] The prepared thiazole-linked COF membrane exhibits similar structural characteristics and performance to that of Example 1, demonstrating excellent permeation selectivity and superior acid resistance. Testing showed that the prepared thiazole-linked COF membrane had a pure water flux of 1247.5 LMH / MPa and a rejection rate of over 95% for Eriochrome Black T.

[0073] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for preparing a thiazole-linked covalent organic framework nanofiltration membrane, characterized in that: Using amphiphilic sulfur-containing amine monomers and aldehyde monomers as interfacial polymerization monomers, thiazole-linked covalent organic framework nanofiltration membranes were obtained by polymerization at a liquid-liquid free interface; the amine monomer was 2,5-diamino-1,4-benzenedithiol dihydrochloride, and the aldehyde monomer was 1,3,5-benzenetriformaldehyde or 1,3,5-tris(p-formylphenyl)benzene.

2. The method for preparing a thiazole-linked covalent organic framework nanofiltration membrane according to claim 1, characterized in that: The molar ratio of amine monomer to aldehyde monomer is 1:0.4-0.

9.

3. The method for preparing a thiazole-linked covalent organic framework nanofiltration membrane according to claim 1 or 2, characterized in that: The specific preparation method is as follows: Step 1: Dissolve the amine monomer in 1 volume of N,N-dimethylformamide, and then add 4 volumes of water to form a clear mixed solvent as an aqueous solution; dissolve the aldehyde monomer and the catalyst in a homogeneous organic solvent to obtain an organic solution. Step 2: First, inject an aqueous phase solution into the reaction vessel, then inject an organic phase solution to form a stable interface. Allow the interface polymerization reaction to proceed at room temperature for 2-7 days to form a thiazole-linked covalent organic framework nanofiltration membrane at the interface.

4. The method for preparing a thiazole-linked covalent organic framework nanofiltration membrane according to claim 3, characterized in that: When the aldehyde monomer is 1,3,5-benzenetriformaldehyde, the catalyst is nonanoic acid and the organic solvent is mesitylene; when the aldehyde monomer is 1,3,5-tris(p-formylphenyl)benzene, the catalyst is acetic acid and the organic solvent is dichloromethane.

5. The method for preparing a thiazole-linked covalent organic framework nanofiltration membrane according to claim 3, characterized in that: The concentration of amine monomers in the aqueous solution is 0.5-2 mM.

6. The method for preparing a thiazole-linked covalent organic framework nanofiltration membrane according to claim 3, characterized in that: The concentration of aldehyde monomer in the organic phase solution is 0.33-1.33 mM, and the concentration of catalyst is 200-700 mM.

7. A thiazole-linked covalent organic framework nanofiltration membrane prepared by any of the preparation methods of the thiazole-linked covalent organic framework nanofiltration membrane according to any one of claims 1-6.

8. The application of the thiazole-linked covalent organic framework nanofiltration membrane as described in claim 7 in membrane separation technology materials.

9. The application according to claim 8, characterized in that: Used for molecular desalination, resource extraction, resource purification, or wastewater recycling in neutral or acidic environments.

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