Triazine covalent organic framework film as well as preparation method and application thereof

Abstract

The invention provides a triazine covalent organic framework film as well as a preparation method and application thereof. A preparation method of a triazine covalent organic framework membrane comprises the following steps: (1) soaking and washing a polyacrylonitrile ultrafiltration membrane in a strong alkali solution to obtain a pretreated ultrafiltration membrane; (2) soaking the pretreated ultrafiltration membrane in a 2-morpholine ethanesulfonic acid buffer solution containing N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) carbodiimide, and washing with water to obtain an activated ultrafiltration membrane; (3) soaking the activated ultrafiltration membrane in a first organic phase solution of a polyamine monomer and 1, 4-dioxane, and washing with water; soaking in a second organic phase solution of a polyaldehyde monomer and 1, 4-dioxane to obtain a modified ultrafiltration membrane; and (4) immersing the modified ultrafiltration membrane into a mixed solution composed of a polyamine monomer, a polyaldehyde monomer, acetic acid and 1, 4-dioxane, and cleaning to obtain the triazine covalent organic framework membrane. The triazine covalent organic framework membrane provided by the invention has good separation performance and catalytic oxidation performance.

Description

Technical Field

[0001] The present disclosure relates to the technical field of membrane material preparation, and in particular to a triazine covalent organic framework membrane and a preparation method and application thereof. Background Art

[0002] Membrane separation technology has been widely used in many fields such as food, medical, energy and water treatment due to its simple operation, high efficiency, energy saving and environmental friendliness. The core of membrane separation technology lies in the separation membrane. During the separation process, the membrane surface will inevitably be affected by the pollutants in the raw liquid, causing membrane fouling. Membrane fouling refers to the process in which organic matter, inorganic matter or microorganisms in the raw liquid adhere to and accumulate on the membrane surface or in the membrane pores to form a contamination layer, which will cause the separation performance and permeation flux of the separation membrane to continuously decrease and cannot be restored. After the separation membrane is fouled, there are mainly two obvious physical and chemical phenomena: 1. Severe concentration polarization and obvious gel layer on the membrane surface; 2. Adsorption and blockage on the membrane surface and in the membrane pores. Membrane fouling is one of the biggest challenges faced in the membrane separation process, which seriously limits the application and operation cost of separation membrane technology. In order to extend the service life of the separation membrane, chemical or physical cleaning methods are usually used to clean the separation membrane. However, excessive use of physical and chemical methods will cause irreversible damage to the separation membrane itself, further shortening the service life of the membrane. Therefore, how to effectively control the membrane fouling problem faced by separation membranes during operation has become one of the most concerning issues for membrane separation researchers today.

[0003] Covalent organic framework materials (COFs) are mainly composed of light elements such as C, H, O, and N. They are a type of crystalline porous polymers connected by covalent bonds, with low mass density, high thermal stability, good physicochemical stability, and permanent porosity. Covalent organic framework materials COFs are a type of polymer that can be completely pre-designed and controllably synthesized. They have the characteristics of large specific surface area, high porosity, adjustable pore size, and high physicochemical stability. They have been widely used in catalysis, optoelectronics, sensing, semiconductors, and adsorption. Among them, the application of triazine covalent organic framework materials (CTFs) in membrane separation is mainly reflected in their unique structural and performance advantages. CTFs are composed of graphene π-conjugated structures connected by nitrogen-containing fused rings, and have the characteristics of light elements (C, H, and N), porous structures, rich heteroatom participation, and extensive conjugated structures. These characteristics make CTFs perform well in the field of membrane separation. Triazine COFs (CTFs) are mainly synthesized through condensation reactions between aldehydes and amidines, cyano condensation and other methods. They have unique optoelectronic properties due to their aromatic planar π-conjugated structure of 1,3,5-triazine rings. However, their preparation conditions are harsh. For example, increasing the degree of reaction and purification in acidic media will destroy the ordered arrangement of CTFs, resulting in poor crystallinity and porosity of the products, making it difficult to prepare high-crystallinity products in large quantities. These defects limit the widespread application of CTFs. Summary of the invention

[0004] The present disclosure provides a triazine covalent organic framework membrane and a preparation method and application thereof, so as to at least solve one of the technical problems existing in the prior art.

[0005] According to a first aspect of the present disclosure, a triazine covalent organic framework film is provided, comprising the following steps: (1) Soaking and washing a polyacrylonitrile ultrafiltration membrane, a polyethersulfone ultrafiltration membrane or a polyvinylidene fluoride ultrafiltration membrane in a strong alkaline solution to obtain a pretreated ultrafiltration membrane; (2) immersing the pretreated ultrafiltration membrane in a 2-morpholineethanesulfonic acid buffer solution containing N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide for activation treatment and washing with water to obtain an activated ultrafiltration membrane; (3) soaking the activated ultrafiltration membrane in a first organic phase solution composed of a mixture of polyamine monomers and 1,4-dioxane and then washing with water; then soaking the activated ultrafiltration membrane in a second organic phase solution composed of a mixture of polyaldehyde monomers and 1,4-dioxane to obtain a modified ultrafiltration membrane; wherein the molar volume ratio of the polyamine monomers to 1,4-dioxane is 0.27-0.41 mmol:90-100 ml; and the molar volume ratio of the polyaldehyde monomers to 1,4-dioxane is 0.3-0.46 mmol:90-100 ml; (4) The modified ultrafiltration membrane is immersed in a mixed solution consisting of a polyamine monomer, a polyaldehyde monomer, acetic acid and 1,4-dioxane, and then washed alternately with deionized water and 1,4-dioxane to obtain a triazine covalent organic framework membrane; wherein the molar volume ratio of the polyamine monomer, the polyaldehyde monomer, the acetic acid and the 1,4-dioxane is 0.27~0.41mmol:0.3~0.46mmol:4~5.5ml:50~200ml.

[0006] In one embodiment, in step (1), the molar concentration of the strong base solution is 1-5 mol / L; In step (1), the strong alkaline solution is one or a mixture of sodium hydroxide solution and potassium hydroxide solution; In the step (1), when the polyacrylonitrile ultrafiltration membrane, polyethersulfone ultrafiltration membrane or polyvinylidene fluoride ultrafiltration membrane is immersed in a strong alkaline solution, the immersion temperature is 40-80° C. and the time is 1-10 hours.

[0007] In one embodiment, in step (2), the molar ratio of N-hydroxysuccinimide to 1-ethyl-(3-dimethylaminopropyl)carbodiimide is 1-100:1-200; In the step (2), the pH value of the 2-morpholineethanesulfonic acid buffer solution is 6; When the pre-treatment ultrafiltration membrane is activated in a 2-morpholineethanesulfonic acid buffer solution, the required temperature is 40-80° C. and the soaking time is 1-10 hours.

[0008] In one embodiment, in step (3), the activated ultrafiltration membrane is immersed in the first organic phase solution for 5 to 12 hours at a temperature of 20 to 60° C.; In the step (3), the activated ultrafiltration membrane is immersed in the second organic phase solution for 1 to 12 hours at a temperature of 20 to 60°C; In the step (4), the modified ultrafiltration membrane is immersed in the mixed solution for at least 48 hours at a temperature of 20-60°C.

[0009] In one embodiment, the polyamine monomer is a small molecule or polymer containing a divalent or polyvalent primary amine or secondary amine group in the structural formula.

[0010] In one embodiment, the polyamine monomer includes 2,4,6,-tris (4-aminophenyl) -1,3,5, triazine, piperazine, p-phenylenediamine, 2,5-dimethyl p-phenylenediamine, 1,4-diamino-2,5-divinylbenzene, 2,5-diaminopyridine, 5,5'-diamino-2,2'-bipyridine, m-phenylenediamine, o-phenylenediamine, 1,2,4,5-phenylenetetramine, biphenylenediamine and its derivatives. Biological, C2-C12 alkyl linear diamine and its derivatives, urea, oxalyl diamine, dithiooxalyl diamine, 2,5-diaminoterephthalic acid, 2-sulfonic acid-1,4-phenylenediamine, 2-isopropyl-1,4-phenylenediamine, 2,3,5,6-tetrakis(amino)benzoquinone, 4',5'-bis(4-aminophenyl)-[1,1':2',1"-terphenyl]-4,4"-diamine, 2, 4-diamino-6-phenyl-1,3,5-triazine, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin, tetrakis(4-aminophenyl)ethylene, 1,2,4,5-tetrakis(4-aminophenyl)ethynyl)benzene, 3,3',4,4'-tetraaminobenzophenone, diethylenetriamine, dipropylenetriamine, dihexyltriamine, melamine, 1,3,5-triaminobenzene, 1, One or more of 2,4-triaminobenzene, 2,6-diaminoanthracene, 4,4'-diaminoterphenyl, melem, p-diaminoazobenzene, 4,4,4,4-methylethanetetrayltetraphenylamine, 2,2-bis(4-aminophenyl)propane, hexa(4-aminobiphenyl)benzene, pyrazine-2,5-diamine, oxalic acid dihydrazide, succinic acid dihydrazide, tetrakis(4-aminophenyl)methane, polyethyleneimine, and polyethyleneamine.

[0011] In one embodiment, the polyaldehyde monomer is a small molecule containing a di- or poly-aldehyde group in the structural formula.

[0012] In one embodiment, the polyaldehyde monomer includes 1,4-dicyanobenzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 1,3,5-tris-(4-aminophenyl) triazine, 2,4,6-trichloro-1,3,5-triazine, glyoxal, glutaraldehyde, adipaldehyde, 1,3-butanedialdehyde, terephthalaldehyde, 2,5-dichloroterephthalaldehyde, 2,5-dihydroxyterephthalaldehyde, 1,4-dialdehyde-2,5-divinylbenzene, 2,3,5,6-tetrafluorobenzaldehyde, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 4,4'-biphenyldicarboxaldehyde, 2,2'-bipyridine-5,5'-dicarboxaldehyde, 1,4-di(4-formylphenyl)benzene, 2,6-naphthalene dicarboxaldehyde, 1,10-phenanthroline-2,9-dicarboxaldehyde, 2,2'-bipyridine -4,4'-diformaldehyde, 4-tert-butyl-2,6-formylphenol, 9,10-di(4-formylphenyl)anthracene, trimesicaldehyde, 4-hydroxyisophthalicaldehyde, 2,4,6-triformylphloroglucinol, 1,3,5-tri(p-formylphenyl)benzene, tri(4-formylphenyl)amine, 2,4,6-tri(4-formylphenyl)-1,3,5-triazine, 3,3',5,5'-tetraformyl-4,4'-dihydroxybiphenyl, tetra(4-formylphenyl)silane, 1,3,6,8-tetra(4-formylphenyl)perylene, tetra(4-formylphenyl)ethylene or one or more thereof.

[0013] According to a second aspect of the present disclosure, a triazine covalent organic framework membrane is provided, which is prepared by any preparation method described in the first aspect.

[0014] According to a third aspect of the present disclosure, there is provided an application of the triazine covalent organic framework membrane for dye separation or photocatalysis.

[0015] Compared with the prior art, the advantages of the present application are: 1) The triazine covalent organic framework membrane prepared by the present application has good separation performance, especially the triazine covalent organic framework membrane prepared by the method of the present application has good dye separation performance. 2) The triazine covalent organic framework membrane of the present application has the advantages of good catalytic oxidation performance and stable performance. 3) The triazine covalent organic framework membrane of the present application has good retention rate and permeability, especially retention rate. The triazine covalent organic framework membrane of the present application has a good retention rate for dyes. 4) The preparation conditions of the triazine covalent organic framework membrane of the present application are mild and have a wide range of applications.

[0016] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which: In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0018] Figure 1 A schematic diagram showing a process of preparing a triazine covalent organic framework film according to an embodiment of the present disclosure; Figure 2 The actual photographs of the triazine covalent organic framework film obtained in Example 3 of the present disclosure, the modified PAN film obtained in Comparative Example 1 and the commercial PAN film are shown; Figure 3 The surface scanning electron microscope image of the triazine covalent organic framework film obtained in Example 3 of the present disclosure is shown; Figure 4 The surface scanning electron microscope image of the modified PAN film obtained by the preparation method of Comparative Example 1 of the present disclosure is shown; Figure 5 The surface scanning electron microscope image of the commercial PAN film purchased by the present disclosure is shown; Figure 6 The X-ray diffraction diagram of the triazine covalent organic framework film obtained by the preparation method of Example 3 of the present disclosure is shown; Figure 7 The figure shows the permeability of the triazine covalent organic framework film obtained by the preparation method of Example 3 of the present disclosure to methyl orange under visible light; Figure 8 The figure shows the interception performance of methyl orange under visible light of the triazine covalent organic framework membrane prepared by the preparation method of Example 3 of the present disclosure; Fig. 9 The pure water permeability diagram of the triazine covalent organic framework membrane obtained by the preparation method of Examples 1-5 of the present disclosure is shown; Fig.10 The permeability and retention performance of the triazine covalent organic framework membrane obtained by the preparation method of Examples 1-5 of the present disclosure to gentian violet are shown; Fig.11 The pure water permeability graphs of the triazine covalent organic framework membrane of Example 3 of the present disclosure, the modified PAN membrane of Comparative Example 1, and the commercial PAN membrane are shown; Fig.12 The graphs show the permeability and rejection performance of the triazine covalent organic framework membrane of Example 3 of the present disclosure, the modified PAN membrane of Comparative Example 1, and the commercial PAN membrane to Congo red. DETAILED DESCRIPTION

[0019] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0020] In the present application, the substrate (such as polyacrylonitrile ultrafiltration membrane, polyethersulfone ultrafiltration membrane or polyvinylidene fluoride ultrafiltration membrane) is first activated, and then immersed in organic phase solutions containing polyamine monomers and polyaldehyde monomers respectively, so that a "seed layer" is loaded on the surface of the substrate, and then the membrane is immersed in an organic phase solution containing both polyamine monomers and polyaldehyde monomers for in-situ growth to prepare a triazine covalent organic framework membrane. The triazine covalent organic framework membrane prepared in the present application has the advantages of good separation performance, catalytic oxidation performance and stable performance.

[0021] Specifically, according to the first aspect of the present disclosure, the present disclosure provides a method for preparing a triazine covalent organic framework film, comprising the following steps: (1) Soaking and washing a polyacrylonitrile ultrafiltration membrane, a polyethersulfone ultrafiltration membrane or a polyvinylidene fluoride ultrafiltration membrane in a strong alkaline solution to obtain a pretreated ultrafiltration membrane; (2) immersing the pretreated ultrafiltration membrane in a 2-morpholineethanesulfonic acid buffer solution containing N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide for activation treatment and washing with water to obtain an activated ultrafiltration membrane; (3) soaking the activated ultrafiltration membrane in a first organic phase solution composed of a mixture of polyamine monomers and 1,4-dioxane and then washing with water; then soaking the activated ultrafiltration membrane in a second organic phase solution composed of a mixture of polyaldehyde monomers and 1,4-dioxane to obtain a modified ultrafiltration membrane; wherein the molar volume ratio of the polyamine monomers to 1,4-dioxane is 0.27-0.41 mmol:90-100 ml; and the molar volume ratio of the polyaldehyde monomers to 1,4-dioxane is 0.3-0.46 mmol:90-100 ml; (4) The modified ultrafiltration membrane is immersed in a mixed solution consisting of a polyamine monomer, a polyaldehyde monomer, acetic acid and 1,4-dioxane, and then washed alternately with deionized water and 1,4-dioxane to obtain a triazine covalent organic framework membrane; wherein the molar volume ratio of the polyamine monomer, the polyaldehyde monomer, the acetic acid and the 1,4-dioxane is 0.27~0.41mmol:0.3~0.46mmol:4~5.5ml:50~200ml.

[0022] Preferably, in step (1), the molar concentration of the strong alkaline solution is 1-5 mol / L; In step (1), the strong alkaline solution is one or a mixture of sodium hydroxide solution and potassium hydroxide solution; In step (1), when the polyacrylonitrile ultrafiltration membrane, polyethersulfone ultrafiltration membrane or polyvinylidene fluoride ultrafiltration membrane is immersed in a strong alkaline solution, the immersion temperature is 40-80° C. and the time is 1-10 hours.

[0023] Preferably, in step (2), the molar ratio of N-hydroxysuccinimide to 1-ethyl-(3-dimethylaminopropyl)carbodiimide is 1-100:1-200; In step (2), the 2-morpholineethanesulfonic acid buffer solution is adjusted to a pH value of 6 using a hydrochloric acid solution; When the pretreated ultrafiltration membrane is activated in a buffer solution, the required temperature is 40~80℃ and the soaking time is 1~10h.

[0024] Preferably, in step (3), the activated ultrafiltration membrane is immersed in the first organic phase solution for 5 to 12 hours at a temperature of 20 to 60°C; In step (3), the activated ultrafiltration membrane is immersed in the second organic phase solution for 1 to 12 hours at a temperature of 20 to 60°C.

[0025] Preferably, in step (3), the molar volume ratio of the polyamine monomer to 1,4-dioxane is 0.27-0.41 mmol: 90 ml, 0.27-0.41 mmol: 92 ml, 0.27-0.41 mmol: 94 ml, 0.27-0.41 mmol: 96 ml, 0.27-0.41 mmol: 98 ml, 0.27-0.41 mmol: 100 ml; the molar volume ratio of the polyaldehyde monomer to 1,4-dioxane is 0.3-0.46 mmol: 90 ml, 0.3-0.46 mmol: 92 ml, 0.3-0.46 mmol: 94 ml, 0.3-0.46 mmol: 96 ml, 0.3-0.46 mmol: 98 ml, 0.3-0.46 mmol: 100 ml.

[0026] Preferably, in step (4), the modified ultrafiltration membrane is immersed in the mixed solution for at least 48 hours at a temperature of 20-60°C.

[0027] Preferably, the polyamine monomer is a small molecule or polymer containing a divalent or polyvalent primary amine or secondary amine group in the structural formula.

[0028] Polyamine monomers include 2,4,6,-tris(4-aminophenyl)-1,3,5,triazine, piperazine, p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 1,4-diamino-2,5-divinylbenzene, 2,5-diaminopyridine, 5,5'-diamino-2,2'-bipyridine, m-phenylenediamine, o-phenylenediamine, 1,2,4,5-phenylenetetramine, biphenylenediamine and its derivatives, C2-C12 alkyl straight Chain diamines and their derivatives, urea, oxalyl diamine, dithiooxalyl diamine, 2,5-diaminoterephthalic acid, 2-sulfonic acid-1,4-phenylenediamine (also known as 1,4-phenylenediamine-2-sulfonic acid), 2-isopropyl-1,4-phenylenediamine, 2,3,5,6-tetrakis(amino)benzoquinone, 4',5'-bis(4-aminophenyl)-[1,1':2',1"-terphenyl]-4,4"-diamine , 2,4-diamino-6-phenyl-1,3,5-triazine, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin, tetrakis(4-aminophenyl)ethylene, 1,2,4,5-tetrakis(4-aminophenyl)ethynyl)benzene, 3,3',4,4'-tetraaminobenzophenone, diethylenetriamine, dipropylenetriamine, dihexyltriamine, melamine, 1,3,5-triaminobenzene, 1 , 2,4-triaminobenzene, 2,6-diaminoanthracene, 4,4'-diaminoterphenyl, melem, p-diaminoazobenzene, 4,4,4,4-methylethanetetrayltetraphenylamine, 2,2-bis(4-aminophenyl)propane, hexa(4-aminobiphenyl)benzene, pyrazine-2,5-diamine, oxalic acid dihydrazide, succinic acid dihydrazide, tetrakis(4-aminophenyl)methane, polyethyleneimine, and polyethyleneamine.

[0029] Preferably, the polyaldehyde monomer is a small molecule containing a di- or poly-aldehyde group in the structural formula.

[0030] The polyaldehyde monomers include 1,4-dicyanobenzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 1,3,5-tris-(4-aminophenyl) triazine, 2,4,6-trichloro-1,3,5-triazine, glyoxal, glutaraldehyde, adipaldehyde, 1,3-succinaldehyde, terephthalaldehyde, 2,5-dichloroterephthalaldehyde, 2,5-dihydroxyterephthalaldehyde, 1,4-dialdehyde-2,5-divinylbenzene, 2,3,5,6-tetrafluorobenzaldehyde, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 4,4'-biphenyldicarboxaldehyde, 2,2'-bipyridine-5,5'-dicarboxaldehyde, 1,4-di(4-formylphenyl)benzene, 2,6-naphthalene dicarboxaldehyde, 1,10-phenanthroline-2,9-dicarboxaldehyde, 2,2'-bipyridine -4,4'-diformaldehyde, 4-tert-butyl-2,6-formylphenol, 9,10-di(4-formylphenyl)anthracene, trimesicaldehyde, 4-hydroxyisophthalicaldehyde, 2,4,6-triformylphloroglucinol, 1,3,5-tri(p-formylphenyl)benzene, tri(4-formylphenyl)amine, 2,4,6-tri(4-formylphenyl)-1,3,5-triazine, 3,3',5,5'-tetraformyl-4,4'-dihydroxybiphenyl, tetra(4-formylphenyl)silane, 1,3,6,8-tetra(4-formylphenyl)perylene, tetra(4-formylphenyl)ethylene or one or more thereof.

[0031] Preferably, when the polyamine monomer is 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, the mass volume ratio of the polyamine monomer to 1,4-dioxane is 0.096-0.144 g:90-100 ml. When the polyaldehyde monomer is 2,4,6-triformylphloroglucinol, the mass volume ratio of the polyaldehyde monomer to 1,4-dioxane is 0.064-0.096 g:90-100 ml.

[0032] According to a second aspect of the present disclosure, a triazine covalent organic framework membrane is provided, which is prepared by any one of the preparation methods described above.

[0033] According to a third aspect of the present disclosure, a triazine covalent organic framework membrane is provided for use in dye separation. Specifically, the triazine covalent organic framework membrane is used in the separation of small molecule organic matter. For example, the small molecule organic matter is a dye.

[0034] According to a fourth aspect of the present disclosure, there is provided an application of a triazine covalent organic framework film in photocatalysis, for example, an application of a triazine covalent organic framework film in photocatalytic dye degradation.

[0035] There is no particular restriction on the sources of all raw materials in this application, and any raw materials can be commercially available.

[0036] The water permeability test method in this application is as follows: The cross-flow test system was used to test the dye retention performance of the membrane in the dark and under visible light irradiation with a wavelength of 420 nm-780 nm (50W xenon lamp). The test system consisted of a pump, a membrane pool, a pipeline, a regulating valve, a pressure and flow detector, etc. The effective membrane area tested was 4.9 cm 2 , the test pressure is 0.5 bar and the test temperature is 25±0.5℃.

[0037] The water permeability is calculated as follows: J=V / [A×Δt×Δp] Where J is the water permeability of the membrane (L m -2 h -1 bar -1 ), V is the permeate volume (L), A is the membrane effective area (m 2 ), Δt is the penetration time (s), and Δp is the test pressure (bar).

[0038] The dye retention rate is calculated as follows: R=(1-C p / C f ) ×100% Among them, C p is the concentration of the permeate (g L -1 ), C f is the concentration of the raw material solution (g L -1 ).

[0039] The formula for calculating the dye retention rate under light conditions is as follows: R=(C / C0) ×100% Where C is the concentration of the permeate (g L -1 ), C0 is the concentration of the raw material solution (g L -1 ).

[0040] The concentration of organic pollutants in the catalytic oxidation reaction system of the present application is 50 ppm, and the organic pollutants include one or more combinations of gentian violet, Congo red, methyl orange, and Evans blue.

[0041] The present application is further described in detail below with reference to specific embodiments: Example 1 A method for preparing a triazine covalent organic framework film comprises the following steps: Step (1): pretreatment: soaking the polyacrylonitrile ultrafiltration membrane in a 1 mol / L sodium hydroxide solution, placing it in a 60° C. oven for 2 hours, and then rinsing it with deionized water to obtain a pretreated polyacrylonitrile ultrafiltration membrane; Step (2): Activation treatment: immerse the pretreated polyacrylonitrile ultrafiltration membrane in 50 ml of 2-morpholineethanesulfonic acid buffer solution (pH=6) containing 3.5 g of N-hydroxysuccinimide and 15 ml of 100 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide; soak at 40°C for 4 hours to activate it, and then rinse with deionized water to obtain an activated ultrafiltration membrane; Step (3): Modification treatment: The activated ultrafiltration membrane was first immersed in a 100 ml 1,4-dioxane solution containing 0.096 g (0.27 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine at room temperature (25°C) for 12 hours, and then rinsed with deionized water; then immersed in a 100 ml 1,4-dioxane solution containing 0.064 g (0.30 mmol) of 2,4,6-triformylphloroglucinol at room temperature for 1 hour to obtain a modified CHPAN membrane (modified polyacrylonitrile ultrafiltration membrane); Step (4): In situ growth: 0.096 g (0.27 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.064 g (0.30 mmol) of 2,4,6-triformylphloroglucinol were dissolved in a mixed solution consisting of 4 ml of acetic acid and 100 ml of 1,4-dioxane, and then the modified CHPAN membrane was immersed in the mixed solution and soaked at room temperature for 2 days, and then washed alternately with deionized water and 1,4-dioxane three times to obtain a triazine covalent organic framework membrane.

[0042] Fig. 9 The pure water permeability diagram of the triazine covalent organic framework membrane prepared by the preparation method of Example 1 is shown in FIG. Fig. 9 As can be seen in Example 1, the pure water permeability of the triazine covalent organic framework membrane is approximately 355.4 L m -2 h -1 bar -1 .

[0043] Fig.10 The permeability and retention performance of the triazine covalent organic framework membrane prepared by the method of Example 1 to gentian violet are shown in FIG. Fig.10 As shown in Example 1, the permeability of triazine covalent organic framework membrane to gentian violet is approximately 172.0 L m - 2 h -1 bar -1 , the interception rate was 74.39%.

[0044] Example 2 A method for preparing a triazine covalent organic framework film comprises the following steps: Step (1): pretreatment: soaking the polyacrylonitrile ultrafiltration membrane in a 1 mol / L sodium hydroxide solution, placing it in a 60° C. oven for 2 hours, and then rinsing it with deionized water to obtain a pretreated polyacrylonitrile ultrafiltration membrane; Step (2): Activation treatment: immerse the pretreated polyacrylonitrile ultrafiltration membrane in 50 ml of 2-morpholineethanesulfonic acid buffer solution (pH=6), wherein the buffer solution contains 3.5 g (30.4 mmol) N-hydroxysuccinimide and 15 ml of 100 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide; immerse at 50°C for 4 hours to activate it, and then rinse with deionized water to obtain an activated polyacrylonitrile ultrafiltration membrane; Step (3): Modification treatment: The activated polyacrylonitrile ultrafiltration membrane is first immersed in a 100 ml 1,4-dioxane solution containing 0.108 g (0.30 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and immersed at room temperature for 12 hours, and then rinsed with deionized water; then immersed in a 100 ml 1,4-dioxane solution containing 0.072 g (0.34 mmol) of 2,4,6-triformylphloroglucinol, and immersed at room temperature for 1 hour to obtain a modified CHPAN membrane (modified polyacrylonitrile ultrafiltration membrane); Step (4): In situ growth: 0.108 g (0.30 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.072 g (0.34 mmol) of 2,4,6-triformylphloroglucinol were dissolved in a mixed solution consisting of 4.5 ml of acetic acid and 100 ml of 1,4-dioxane, and the CHPAN membrane was immersed and soaked at room temperature for 2 days. The membrane was then washed alternately with deionized water and 1,4-dioxane three times to obtain a triazine covalent organic framework membrane.

[0045] Fig. 9 The pure water permeability diagram of the triazine covalent organic framework membrane prepared by the preparation method of Example 2 is shown in FIG. Fig. 9 As can be seen in Example 2, the pure water permeability of the triazine covalent organic framework membrane is approximately 286.6 L m -2 h -1 bar -1 .

[0046] Fig.10 The permeability and retention performance of the triazine covalent organic framework membrane prepared by the method of Example 2 to gentian violet are shown in FIG. Fig.10 As shown in Example 2, the permeability of triazine covalent organic framework membrane to gentian violet is approximately 121.7 L m - 2 h -1 bar -1, the interception rate was 84.85%.

[0047] Example 3 A method for preparing a triazine covalent organic framework film comprises the following steps: Step (1): pretreatment: soaking the polyacrylonitrile ultrafiltration membrane in a 1 mol / L sodium hydroxide solution, placing it in a 60° C. oven for 2 hours, and then rinsing it with deionized water to obtain a pretreated polyacrylonitrile ultrafiltration membrane; Step (2): Activation treatment: immerse the pretreated polyacrylonitrile ultrafiltration membrane in 50 ml of 2-morpholineethanesulfonic acid buffer solution (pH=6) containing 3.5 g of N-hydroxysuccinimide and 15 ml of 100 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide; soak at 60°C for 4 hours to activate it, and then rinse with deionized water to obtain an activated polyacrylonitrile ultrafiltration membrane; Step (3): Modification treatment: The activated polyacrylonitrile ultrafiltration membrane is first immersed in a 100 ml 1,4-dioxane solution containing 0.12 g (0.34 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and immersed at room temperature for 12 hours, and then rinsed with deionized water; then immersed in a 100 ml 1,4-dioxane solution containing 0.08 g (0.38 mmol) of 2,4,6-triformylphloroglucinol, and immersed at room temperature for 1 hour to obtain a modified polyacrylonitrile ultrafiltration membrane (modified CHPAN membrane); Step (4): In situ growth: 0.12 g (0.34 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.08 g (0.38 mmol) of 2,4,6-triformylphloroglucinol were dissolved in a mixed solution consisting of 5 ml of acetic acid and 100 ml of 1,4-dioxane, and the modified CHPAN membrane was immersed and soaked at room temperature for 2 days. The membrane was then washed alternately with deionized water and 1,4-dioxane three times to obtain a triazine covalent organic framework membrane.

[0048] Figure 2 These are actual photos of the triazine covalent organic framework film obtained by the preparation method of Example 3, the modified PAN film obtained by the preparation method of Comparative Example 1, and the commercial PAN film. As can be seen from Figure 2, the original commercial PAN film is white, yellow after modification (Comparative Example 1), and orange after in-situ growth is completed (Example 3), and there is an obvious color difference.

[0049] Figure 3 is a surface scanning electron microscope image of the triazine covalent organic framework film obtained by the preparation method of Example 3. Figure 3 It can be seen that the surface of the polyacrylonitrile ultrafiltration membrane is covered with a mesh structure, indicating that the COF layer (covalent organic framework material layer) grows well.

[0050] Figure 6 This is the X-ray diffraction pattern of the triazine covalent organic framework film obtained by the preparation method of Example 3, where 5.8° corresponds to the 100 crystal plane of the triazine covalent organic framework, but the characteristic peak is not obvious, which may be due to the fact that the COF layer is too thin and the growth of COF on the polyacrylonitrile ultrafiltration membrane sacrifices crystallinity. 25-27° corresponds to the 001 crystal plane, and this characteristic peak proves the π-π stacking of the COF two-dimensional layer.

[0051] Figure 7 The permeability of the triazine covalent organic framework membrane to methyl orange under visible light obtained by the preparation method of Example 3 shows that within 30 minutes after the light is turned off, the permeability of methyl orange of the triazine covalent organic framework membrane increases from 300 L m -2 h - 1 bar -1 Rapidly decrease to 250 L m -2 h -1 bar -1 The following shows that the triazine covalent organic framework membrane surface is seriously blocked by dye molecules. However, under the irradiation of visible light, the permeability decline trend of the triazine covalent organic framework membrane is significantly slowed down, reflecting that the blockage of the membrane surface has been alleviated. This shows that under the irradiation of visible light, the triazine covalent organic framework membrane has photocatalytic oxidation performance on dye molecules.

[0052] Figure 8 This is a graph showing the interception performance of methyl orange by the triazine covalent organic framework membrane prepared by the preparation method of Example 3 under visible light. Within 30 minutes after the light is turned off, the interception rate of methyl orange by the triazine covalent organic framework membrane is close to 20%, which may be due to the accumulation of dye molecules on the surface of the triazine covalent organic framework membrane, resulting in the loss of permeability of the triazine covalent organic framework membrane. Under visible light irradiation, the interception rate of methyl orange by the triazine covalent organic framework membrane is stable at about 25%.

[0053] Fig. 9 The pure water permeability diagram of the triazine covalent organic framework membrane prepared by the preparation method of Example 3 of the present invention is shown in FIG. Fig. 9 As can be seen in Example 3, the pure water permeability of the triazine covalent organic framework membrane is approximately 272.6 L m -2 h -1 bar -1 .

[0054] Fig.10 The permeability and retention performance of the triazine covalent organic framework membrane prepared by the method of Example 3 to gentian violet are shown in FIG. Fig.10 As shown in Example 3, the permeability of triazine covalent organic framework membrane to gentian violet is approximately 96.2 L m -2 h-1 bar -1 , the interception rate was 90.42%.

[0055] Example 4 A method for preparing a triazine covalent organic framework film comprises the following steps: Step (1): pretreatment: soaking the polyacrylonitrile ultrafiltration membrane in a 1 mol / L sodium hydroxide solution, placing it in a 60° C. oven for 2 hours, and then rinsing it with deionized water to obtain a pretreated polyacrylonitrile ultrafiltration membrane; Step (2): Activation treatment: immerse the pretreated polyacrylonitrile ultrafiltration membrane in 50 ml of 2-morpholineethanesulfonic acid buffer solution (pH=6), wherein the buffer solution contains 3.5 g of N-hydroxysuccinimide and 15 ml of 100 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide; immerse at 80°C for 4 hours to activate it, and then rinse with deionized water to obtain an activated polyacrylonitrile ultrafiltration membrane; Step (3): Modification treatment: The activated polyacrylonitrile ultrafiltration membrane is first immersed in a 100 ml 1,4-dioxane solution containing 0.132 g (0.37 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and immersed at room temperature for 12 hours, and then rinsed with deionized water; then immersed in a 100 ml 1,4-dioxane solution containing 0.088 g (0.42 mmol) of 2,4,6-triformylphloroglucinol, and immersed at room temperature for 1 hour to obtain a modified CHPAN membrane (modified polyacrylonitrile ultrafiltration membrane); Step (4): In situ growth: 0.132 g (0.37 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.088 g (0.42 mmol) of 2,4,6-triformylphloroglucinol were dissolved in a mixed solution consisting of 5.5 ml of acetic acid and 100 ml of 1,4-dioxane, and the modified CHPAN membrane was immersed and soaked at room temperature for 2 days, and then washed alternately with deionized water and 1,4-dioxane three times to obtain a triazine covalent organic framework membrane.

[0056] Fig. 9 The pure water permeability diagram of the triazine covalent organic framework membrane prepared by the preparation method of Example 4 is shown in FIG. Fig. 9 As can be seen in Example 4, the pure water permeability of the triazine covalent organic framework membrane is approximately 309.6 L m -2 h -1 bar -1 .

[0057] Fig.10 The permeability and retention performance of the triazine covalent organic framework membrane prepared by the method of Example 4 to gentian violet are shown in FIG. Fig.10 As shown in Example 4, the permeability of triazine covalent organic framework membrane to gentian violet is approximately 146.5 L m - 2 h -1 bar -1 , the interception rate was 81.11%.

[0058] Example 5 A method for preparing a triazine covalent organic framework film comprises the following steps: Step (1): soaking the polyacrylonitrile ultrafiltration membrane in a 1 mol / L sodium hydroxide solution, placing it in a 60° C. oven for 2 hours, and then rinsing it with deionized water to obtain a pretreated polyacrylonitrile ultrafiltration membrane; Step (2): immersing the pretreated polyacrylonitrile ultrafiltration membrane in 50 ml of 2-morpholineethanesulfonic acid buffer solution (pH=6), wherein the buffer solution contains 3.5 g of N-hydroxysuccinimide and 15 ml of 100 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide; immersing at 60°C for 4 hours to activate it, and then rinsing with deionized water to obtain an activated polyacrylonitrile ultrafiltration membrane; Step (3): Modification treatment: The activated polyacrylonitrile ultrafiltration membrane is first immersed in a 100 ml 1,4-dioxane solution containing 0.144 g (0.41 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and immersed at room temperature for 12 hours, and then rinsed with deionized water; then immersed in a 100 ml 1,4-dioxane solution containing 0.096 g (0.46 mmol) of 2,4,6-triformylphloroglucinol, and immersed at room temperature for 1 hour to obtain a modified CHPAN membrane (modified polyacrylonitrile ultrafiltration membrane); Step (4): In situ growth: 0.144 g (0.41 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.096 g (0.46 mmol) of 2,4,6-triformylpyrogallol were dissolved in a mixed solution consisting of 5.5 ml of acetic acid and 100 ml of 1,4-dioxane, and the modified CHPAN membrane was immersed and soaked at room temperature for 2 days, and then washed alternately with deionized water and 1,4-dioxane three times to obtain a triazine covalent organic framework membrane.

[0059] Fig. 9 The pure water permeability diagram of the triazine covalent organic framework membrane prepared by the preparation method of Example 5 is shown in FIG. Fig. 9 As can be seen in Example 5, the pure water permeability of the triazine covalent organic framework membrane is approximately 387.3 L m -2 h -1 bar -1 .

[0060] Fig.10 The permeability and retention performance of the triazine covalent organic framework membrane prepared by the method of Example 5 to gentian violet are shown in FIG. Fig.10 As shown in Figure 5, the permeability of the triazine covalent organic framework membrane to gentian violet is approximately 204.5 L m - 2 h -1 bar -1 , the interception rate was 69.6%.

[0061] Comparative Example 1 A method for preparing a modified polyacrylonitrile ultrafiltration membrane comprises the following steps: Step (1): pretreatment: soaking the polyacrylonitrile ultrafiltration membrane in a 1 mol / L sodium hydroxide solution, placing it in a 60° C. oven for 2 hours, and then rinsing it with deionized water to obtain a pretreated polyacrylonitrile ultrafiltration membrane; Step (2): Activation treatment: immerse the pretreated polyacrylonitrile ultrafiltration membrane in 50 ml of 2-morpholineethanesulfonic acid buffer solution (pH=6) containing 50 mM N-hydroxysuccinimide and 100 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide; soak at 60°C for 4 hours to activate it, and then rinse with deionized water to obtain an activated PAN membrane (activated polyacrylonitrile ultrafiltration membrane); Step (3): Modification treatment: The activated PAN membrane was first immersed in a 100 ml 1,4-dioxane solution containing 0.12 g 2,4,6-tris(4-aminophenyl)-1,3,5-triazine for 12 h at room temperature, and then rinsed with deionized water; then immersed in a 100 ml 1,4-dioxane solution containing 0.08 g 2,4,6-triformylpyrogallol for 1 h at room temperature to obtain a modified polyacrylonitrile ultrafiltration membrane (referred to as "modified PAN membrane").

[0062] Figure 4 is a surface scanning electron microscope image of the modified PAN film obtained by the preparation method of this comparative example 1, and Figure 5 Compared with the surface scanning electron microscopy image of the purchased commercial PAN membrane, it can be observed that after modification, the pores on the surface of the PAN membrane are significantly reduced, and the pore size is also significantly reduced.

[0063] Fig.11 The pure water permeability diagram of the modified PAN membrane obtained by the preparation method of this comparative example 1 and the commercial PAN membrane (i.e., the original PAN membrane) is shown in FIG. Fig.11 As can be seen in Figure 2, the pure water permeability of the original PAN membrane is approximately 473.9 L m -2 h -1 bar -1The pure water permeability of the modified PAN membrane obtained in Comparative Example 1 is approximately 412.7 L m -2 h -1 bar -1 , which is due to the high pure water permeability caused by the presence of large pores in the PAN membrane itself.

[0064] Fig.12 The figure shows the permeability and interception performance of the modified PAN membrane prepared by the preparation method of this comparative example 1 and the commercial PAN membrane (i.e., the original PAN membrane) to Congo red. The Congo red permeability of the original PAN membrane is 250.96 L m -2 h -1 bar -1 The interception rate was 60.19%. The Congo red permeability of the modified PAN membrane obtained in Comparative Example 1 was 179.62 L m -2 h -1 bar -1 The interception rate was 87.84%. In comparison, the Congo red permeability of the triazine covalent organic framework membrane prepared in Example 3 was 98.09 L m -2 h - 1 bar -1 The retention rate is as high as 99.6%, which indicates that the in-situ growth of the COF layer significantly improves the retention performance of the membrane, while at the same time it leads to a decrease in permeability.

[0065] Based on the above embodiments, the triazine covalent organic framework membrane prepared in the present application has good separation performance and catalytic oxidation performance, high dye interception rate, and has the advantages of reusability and low economic cost.

[0066] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0067] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0068] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for preparing a triazine covalent organic framework membrane, Features: The steps include: (1) soaking and washing a polyacrylonitrile ultrafiltration membrane, a polyethersulfone ultrafiltration membrane or a polyvinylidene fluoride ultrafiltration membrane in a strong alkaline solution to obtain a pretreated ultrafiltration membrane; (2) immersing the pretreated ultrafiltration membrane in a 2-morpholineethanesulfonic acid buffer solution containing N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide for activation treatment and washing with water to obtain an activated ultrafiltration membrane; (3) soaking the activated ultrafiltration membrane in a first organic phase solution composed of a mixture of polyamine monomers and 1,4-dioxane and then washing with water; then soaking the activated ultrafiltration membrane in a second organic phase solution composed of a mixture of polyaldehyde monomers and 1,4-dioxane to obtain a modified ultrafiltration membrane; wherein the molar volume ratio of the polyamine monomers to 1,4-dioxane is 0.27-0.41 mmol:90-100 ml; and the molar volume ratio of the polyaldehyde monomers to 1,4-dioxane is 0.3-0.46 mmol:90-100 ml; (4) The modified ultrafiltration membrane is immersed in a mixed solution consisting of a polyamine monomer, a polyaldehyde monomer, acetic acid and 1,4-dioxane, and then washed alternately with deionized water and 1,4-dioxane to obtain a triazine covalent organic framework membrane; wherein the molar volume ratio of the polyamine monomer, the polyaldehyde monomer, the acetic acid and the 1,4-dioxane is 0.27~0.41mmol:0.3~0.46mmol:4~5.5ml:50~200ml.

2. The preparation method according to claim 1, Features: In the step (1), the molar concentration of the strong alkaline solution is 1-5 mol / L; In step (1), the strong alkaline solution is one or a mixture of sodium hydroxide solution and potassium hydroxide solution; In the step (1), when the polyacrylonitrile ultrafiltration membrane, polyethersulfone ultrafiltration membrane or polyvinylidene fluoride ultrafiltration membrane is immersed in a strong alkaline solution, the immersion temperature is 40-80° C. and the time is 1-10 hours.

3. The preparation method according to claim 1, Features: In the step (2), the molar ratio of N-hydroxysuccinimide to 1-ethyl-(3-dimethylaminopropyl)carbodiimide is 1-100:1-200; In the step (2), the pH value of the 2-morpholineethanesulfonic acid buffer solution is 6; When the pre-treatment ultrafiltration membrane is activated in a 2-morpholineethanesulfonic acid buffer solution, the required temperature is 40-80° C. and the soaking time is 1-10 hours.

4. The preparation method according to claim 1, Features: In the step (3), the activated ultrafiltration membrane is immersed in the first organic phase solution for 5 to 12 hours at a temperature of 20 to 60°C; In the step (3), the activated ultrafiltration membrane is immersed in the second organic phase solution for 1 to 12 hours at a temperature of 20 to 60°C; In the step (4), the modified ultrafiltration membrane is immersed in the mixed solution for at least 48 hours at a temperature of 20-60°C.

5. The preparation method according to claim 1, Features: The polyamine monomer is a small molecule or polymer containing a divalent or polyvalent primary amine or secondary amine group in the structural formula.

6. The preparation method according to claim 5, Features: The polyamine monomers include 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, piperazine, p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 1,4-diamino-2,5-divinylbenzene, 2,5-diaminopyridine, 5,5'-diamino-2,2'-bipyridine, m-phenylenediamine, o-phenylenediamine, 1,2,4,5-phenylenetetramine, biphenylenediamine and its derivatives, C2-C 12-alkyl linear diamines and their derivatives, urea, oxalyl diamine, dithiooxalyl diamine, 2,5-diaminoterephthalic acid, 2-sulfonic acid-1,4-phenylenediamine, 2-isopropyl-1,4-phenylenediamine, 2,3,5,6-tetrakis(amino)benzoquinone, 4',5'-bis(4-aminophenyl)-[1,1':2',1"-terphenyl]-4,4"-diamine, 2,4-diamino 6-phenyl-1,3,5-triazine, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin, tetrakis(4-aminophenyl)ethylene, 1,2,4,5-tetrakis(4-aminophenyl)ethynyl)benzene, 3,3',4,4'-tetraaminobenzophenone, diethylenetriamine, dipropylenetriamine, dihexyltriamine, melamine, 1,3,5-triaminobenzene, 1,2, One or more of 4-triaminobenzene, 2,6-diaminoanthracene, 4,4'-diaminoterphenyl, melem, p-diaminoazobenzene, 4,4,4,4-methylethanetetrayltetraphenylamine, 2,2-bis(4-aminophenyl)propane, hexa(4-aminobiphenyl)benzene, pyrazine-2,5-diamine, oxalic acid dihydrazide, succinic acid dihydrazide, tetrakis(4-aminophenyl)methane, polyethyleneimine, and polyethyleneamine.

7. The preparation method according to claim 1, Features: The polyaldehyde monomer is a small molecule containing a divalent or polyvalent aldehyde group in the structural formula.

8. The preparation method according to claim 7, Features: The polyaldehyde monomers include 1,4-dicyanobenzene, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 1,3,5-tris-(4-aminophenyl) triazine, 2,4,6-trichloro-1,3,5-triazine, glyoxal, glutaraldehyde, adipaldehyde, 1,3-succinaldehyde, terephthalaldehyde, 2,5-dichloroterephthalaldehyde, 2,5-dihydroxyterephthalaldehyde, 1,4-dialdehyde-2,5-divinylbenzene, 2,3,5,6-tetrafluorobenzaldehyde, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, 4,4'-biphenyldicarboxaldehyde, 2,2'-bipyridine-5,5'-dicarboxaldehyde, 1,4-di(4-formylphenyl)benzene, 2,6-naphthalene dicarboxaldehyde, 1,10-phenanthroline-2,9-dicarboxaldehyde, 2,2'-bipyridine -4,4'-diformaldehyde, 4-tert-butyl-2,6-formylphenol, 9,10-di(4-formylphenyl)anthracene, trimesicaldehyde, 4-hydroxyisophthalicaldehyde, 2,4,6-triformylphloroglucinol, 1,3,5-tri(p-formylphenyl)benzene, tri(4-formylphenyl)amine, 2,4,6-tri(4-formylphenyl)-1,3,5-triazine, 3,3',5,5'-tetraformyl-4,4'-dihydroxybiphenyl, tetra(4-formylphenyl)silane, 1,3,6,8-tetra(4-formylphenyl)perylene, tetra(4-formylphenyl)ethylene or one or more thereof.

9. A triazine covalent organic framework membrane, Features: It is prepared by the preparation method described in any one of claims 1 to 8.

10. Use of the triazine covalent organic framework membrane according to claim 9 for dye separation or photocatalysis.

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