A fully bio-based polyester composite nanofiltration membrane and a preparation method and application thereof

Abstract

The application provides a full-bio-based polyester composite nanofiltration membrane and a preparation method and application thereof, and the full-bio-based polyester composite nanofiltration membrane comprises a support layer base film and a nanofiltration separation layer arranged on the support layer base film, and the nanofiltration separation layer is a polyester film constructed by reaction of a bio-based saccharide monomer and a bio-based furanoyl chloride monomer. The nanofiltration separation layer of the application takes the bio-based saccharide monomer and the bio-based furanoyl chloride monomer as reactants, both of the two monomers used are derived from biomass, meet the green environmental protection requirement, the raw materials used are low in price and easy to prepare on a large scale, and the application has important significance for promoting development of a next-generation green membrane material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanofiltration membrane, in particular to a full-bio-based polyester composite nanofiltration membrane and a preparation method and application thereof. BACKGROUND

[0002] Liquid separation membranes include nanofiltration membranes, reverse osmosis membranes, etc., mainly having structures of polyamide, polyester, etc., and using fossil-based amine monomers (such as m-phenylenediamine, piperazine, p-phenylenediamine, aromatic alcohol, etc.) and fossil-based acyl chloride monomers (such as aromatic acyl chloride, etc.) for polymerization reaction.

[0003] The promotion of the biotechnology revolution and the industrial revolution promotes the rapid development of bio-based materials, and the industry is actively promoting the replacement of non-renewable fossil-based materials with bio-based materials. In recent years, some prior art has proposed new bio-based nanofiltration membranes, using bio-based monomers such as cucurbituril, stevioside, glucose, etc. for the preparation of polyamide nanofiltration membranes and polyester membranes, but the prior art still needs to use non-renewable fossil-based trimesoyl chloride monomers for interfacial polymerization reaction.

[0004] In addition, the structural precision, stability, permeability, molecular selectivity, and preparation controllability of bio-based nanofiltration membranes are also difficult points faced by the prior art. In order to achieve the goals of sustainable development, energy saving and emission reduction, and environmentally friendly economic development, it is of great significance to develop full-bio-based nanofiltration membranes with high performance. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a new full-bio-based nanofiltration membrane, which is environmentally friendly and has excellent separation performance and stability.

[0006] To achieve the above-mentioned purpose, the first method of the present application provides a full-bio-based polyester composite nanofiltration membrane, which comprises a support layer base film and a nanofiltration separation layer disposed on the support layer base film, and the material of the nanofiltration separation layer is a polyester membrane constructed by reaction of a bio-based sugar monomer and a bio-based furan acyl chloride monomer.

[0007] Further, the bio-based sugar monomer is selected from at least one of glucose, lactose, maltose, and raffinose.

[0008] Further, the bio-based furan acyl chloride monomer is 2,5-furandicarboxylic acid chloride.

[0009] The nanofiltration separation layer of the present application uses bio-based sugar monomers and bio-based furan acyl chloride monomers as reactants, both of which are derived from biomass, achieving full replacement of aromatic monomers, meeting the requirements of green environmental protection, and the raw materials used are low in price and easy to scale up, which is of great significance for promoting the development of next-generation green membrane materials.

[0010] Further, the thickness of the nanofiltration separation layer is 20-130 nm.

[0011] Further, the material of the support layer base film is selected from one of polyether sulfone film, polysulfone film, polyacrylonitrile film, nylon film, cellulose acetate film, hydrophilic modified polyvinylidene fluoride film, and hydrophilic modified polypropylene film.

[0012] Further, the average pore size of the support layer base film is 0.05-0.5 μm.

[0013] The present application constructs a furan bio-based composite nanofiltration separation layer in situ on a microfiltration base film, and the support layer base film can be selected according to the application object.

[0014] Further, the pure water permeation coefficient of the full bio-based polyester composite nanofiltration membrane is 30-50 L m -2 h -1 bar -1 .

[0015] Further, the permeation coefficient of the full bio-based polyester composite nanofiltration membrane for polar organic solvents is 10-35 L m -2 h -1 bar -1 .

[0016] Further, the rejection rate of the full bio-based polyester composite nanofiltration membrane for monovalent salt is less than 10%, and the rejection rate for divalent salt is less than 20%.

[0017] Further, the molecular weight cut-off of the full bio-based polyester composite nanofiltration membrane is 400-800 Da.

[0018] Both the bio-based saccharide monomer and the bio-based furan acyl chloride monomer have rich polar structures, and have excellent affinity properties for water molecules and polar solvents, so that high permeation separation of water environment systems and polar solvent systems can be realized.

[0019] The second aspect of the present application provides a preparation method of the full bio-based polyester composite nanofiltration membrane, comprising the following steps:

[0020] The bio-based saccharide small molecule monomer is dissolved in water, and a catalyst is added to obtain a bio-based saccharide aqueous monomer solution;

[0021] The bio-based furan acyl chloride monomer is dissolved in an organic solvent to obtain a bio-based furan acyl chloride organic monomer solution;

[0022] The bio-based saccharide aqueous monomer solution is placed above the support layer base film, and the bio-based furan acyl chloride organic monomer solution is placed above the bio-based saccharide aqueous monomer solution, and a free interface polymerization reaction is carried out to obtain a nanofiltration separation layer;

[0023] The excess monomers are removed by applying negative pressure, and the nascent membrane is obtained by washing with an organic solvent;

[0024] The nascent membrane is heated to perform a thermal crosslinking reaction, thereby obtaining the full-bio-based polyester composite nanofiltration membrane.

[0025] Further, the concentration of the bio-based saccharide aqueous monomer solution is 1-10 wt%.

[0026] Further, the concentration of the bio-based acyl chloride organic monomer solution is 0.1-0.5 wt%.

[0027] Further, the catalyst is selected from one of triethylamine, sodium hydroxide and sodium bicarbonate, and the concentration of the catalyst is 0.1-1 wt%.

[0028] Further, the time of the free interface polymerization reaction is 2-10 min.

[0029] Further, the temperature of the thermal crosslinking reaction is 60-100 DEG C, and the time is 5-15 min.

[0030] In the application, bio-based saccharide monomers and bio-based furan acyl chloride monomers are used as reaction monomers to construct a polyester membrane in situ on a support layer base membrane through free interface polymerization, the nanofiltration separation layer and the support layer base membrane have high bonding strength, the nanofiltration separation layer and the support layer base membrane are connected through an ester bond and have excellent stability, the bio-based furan acyl chloride monomers contain a polar furan ring, the interface polymerization reaction kinetics and thermodynamics can be regulated, and thus the structure of the nanofiltration separation layer can be accurately controlled.

[0031] The third aspect of the application provides an application of the full-bio-based polyester composite nanofiltration membrane, and the full-bio-based polyester composite nanofiltration membrane is used for nanofiltration separation in a water system or an organic solvent system.

[0032] In summary, the application has the following beneficial effects compared with the prior art:

[0033] (1) The application uses bio-based saccharides and bio-based furan acyl chloride monomers as raw materials for preparing a nanofiltration separation layer, does not need to use aromatic monomers, meets the green environmental protection requirement, and has low raw material price and is easy to scale up.

[0034] (2) The bio-based furan acyl chloride monomers used in the application contain a polar furan ring, the interface polymerization reaction kinetics and thermodynamics can be regulated through the formation of hydrogen bonds and other actions, and thus the structure and performance of the nanofiltration membrane can be regulated.

[0035] (3) The application constructs a nanofiltration separation layer in situ by free interface polymerization, so that the support layer base film and the nanofiltration separation layer are combined at high strength.

[0036] (4) The nanofiltration separation layer constructed by the application is connected to the support layer base film through an ester bond, has excellent chlorine resistance, and can maintain the stability of the structure during membrane cleaning.

[0037] (5) The bio-based saccharide monomer and the bio-based furanoyl chloride monomer used in the application both have rich polar structures, have excellent affinity properties for water molecules and polar solvents, and can realize efficient permeation separation in a water environment system and a polar solvent system. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A photo of a full bio-based polyester composite nanofiltration membrane prepared in Example 1 of the application.

[0039] Figure 2 A photo of a full bio-based polyester composite nanofiltration membrane prepared in Example 3 of the application.

[0040] Figure 3 A surface electron microscope graph of a full bio-based polyester composite nanofiltration membrane prepared in Example 3 of the application.

[0041] Figure 4 A cross-section electron microscope graph of a full bio-based polyester composite nanofiltration membrane prepared in Example 3 of the application. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the drawings. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the application, and are not used to limit the parameter range described in the application, and any reasonable changes derived therefrom are still within the protection scope of the claims of the application.

[0043] It should be noted that the endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values stated are approximate values and should be understood to include values approximately close thereto. For ranges of values, the endpoints of the ranges are combinable with one another to form new ranges of values, and the values of the ranges are combinable with one another to form new ranges of values, which are to be understood to be specifically disclosed herein.

[0044] The specific embodiment of the application provides a full bio-based polyester composite nanofiltration membrane, which comprises a support layer base film and a nanofiltration separation layer disposed on the support layer base film, wherein the material of the nanofiltration separation layer is a polyester film constructed by the reaction of a bio-based saccharide monomer and a bio-based furanoyl chloride monomer.

[0045] In specific embodiments, the bio-based sugar monomer can be glucose, lactose, maltose, raffinose, etc.; the bio-based furanoyl chloride monomer is preferably 2,5-furan dicarboxylic chloride. The reaction monomers used in the nanofiltration separation layer are all derived from biomass, meeting the green and environmentally friendly requirements, and the bio-based sugar monomer and the bio-based furanoyl chloride monomer both have abundant polar structures, and have excellent affinity properties for water molecules and polar solvents, so that high permeation separation can be achieved in water environment systems and polar solvent systems.

[0046] In specific embodiments, the thickness of the nanofiltration separation layer is 20-130 nm, and the thickness and structure thereof can be adjusted according to the application object.

[0047] In specific embodiments, the material of the support layer base film is a microporous membrane; preferably a microfiltration membrane, and the average pore size thereof is 0.05-0.5 μm. The material of the support layer base film can be selected according to the application object, and typical materials include polyether sulfone membrane, polysulfone membrane, polyacrylonitrile membrane, nylon membrane, cellulose acetate membrane, hydrophilically modified polyvinylidene fluoride membrane, hydrophilically modified polypropylene membrane, etc.

[0048] The preparation method of the above-mentioned full-bio-based polyester composite nanofiltration membrane specifically includes the following steps:

[0049] S1, dissolving a bio-based sugar small molecule monomer in water, adding a catalyst to obtain a bio-based sugar aqueous monomer solution.

[0050] In specific embodiments, the concentration of the bio-based sugar small molecule monomer in the solution is 1-10 wt%, and the concentration of the catalyst is 0.1-1 wt%; the catalyst can be selected from triethylamine, sodium hydroxide, sodium bicarbonate, etc.

[0051] S2, dissolving a bio-based furanoyl chloride monomer in an organic solvent to obtain a bio-based furanoyl chloride organic phase monomer solution.

[0052] In specific embodiments, the organic solvent can be selected from n-hexane, cyclohexane, etc.; and the concentration of the bio-based furanoyl chloride monomer in the solution is 0.1-0.5 wt%.

[0053] S3, placing the bio-based sugar aqueous monomer solution obtained in step S1 above the support layer base film, and placing the bio-based furanoyl chloride organic phase monomer solution obtained in step S2 above the bio-based sugar aqueous monomer solution, and performing a free interface polymerization reaction to obtain a nanofiltration separation layer; applying a negative pressure to remove excess monomers, and washing with an organic solvent to obtain a nascent membrane.

[0054] In specific embodiments, the time of the free interface polymerization reaction is 2-10 min.

[0055] S4, heating the nascent membrane obtained in step S3 to perform a thermal crosslinking reaction to obtain a full-bio-based polyester composite nanofiltration membrane.

[0056] In specific embodiments, the temperature of the thermal crosslinking reaction is 60-100℃, and the time is 5-15 min.

[0057] The full-bio-based polyester composite nanofiltration membrane provided by the specific embodiments has the advantages of high permeability and high molecular selectivity,

[0058] The full-bio-based polyester composite nanofiltration membrane has the advantages of high permeability and high molecular selectivity, and the pure water permeability coefficient is 30-50 L m -2 h -1 bar -1 , the permeability coefficient of the organic solvent is 10-35 L m - 2 h -1 bar -1 , the rejection rate of monovalent salt is less than 10%, the rejection rate of divalent salt is less than 20%, the molecular weight cut-off is 400-800 Da, and high permeation separation of water environment system and organic solvent system can be realized.

[0059] The technical solutions and effects of the present application are described below through specific embodiments.

[0060] Example 1

[0061] In this embodiment, a polyether sulfone membrane with an average pore size of 0.22 μm is used as a base film to prepare a full-bio-based polyester composite nanofiltration membrane, and the preparation process is as follows:

[0062] (1) Prepare a 5wt% glucose aqueous monomer solution, and add 0.5% sodium hydroxide as a catalyst to the above aqueous monomer solution; prepare a 0.15wt% 2,5-furandicarboxylic acid chloride organic monomer solution, and the organic solvent is n-hexane.

[0063] (2) Pour the aqueous monomer solution onto the polyether sulfone membrane, then add the organic monomer solution, and perform free interface polymerization for 5 min.

[0064] (3) After the reaction is completed, remove the unreacted aqueous monomer solution by applying negative pressure, then pour off the excess organic monomer solution, and wash with n-hexane to obtain a full-bio-based polyester nascent membrane.

[0065] (4) Place the nascent membrane in a 60℃ oven, and heat crosslink for 10 min to obtain a full-bio-based polyester composite nanofiltration membrane.

[0066] The macroscopic morphology of the full-bio-based polyester composite nanofiltration membrane prepared in this embodiment is as shown in Figure 1The full-bio-based polyester composite nanofiltration membrane has a support layer base film and a nanofiltration separation layer, and the thickness of the nanofiltration separation layer is about 98 nm. Under the operation of cross flow at 5 bar, the permeation coefficient of pure water after stabilization is 32 L m -2 h -1 bar -1 ; and the rejection rate reaches 99.9% when 1000 ppm Congo red is used as the feed liquid.

[0067] Example 2

[0068] In this example, a full-bio-based polyester composite nanofiltration membrane is prepared using a polyether sulfone membrane with an average pore size of 0.22 μm as a base film, and the preparation process is as follows:

[0069] (1) 3 wt% fructose is prepared as an aqueous monomer solution, and 0.3% triethylamine of the mass of the aqueous monomer solution is added as a catalyst; 0.6 wt% 2,5-furandicarboxylic acid chloride organic monomer solution is prepared, and the organic solvent is cyclohexane.

[0070] (2) The aqueous monomer solution is poured onto the polyether sulfone membrane, and then the organic monomer solution is added, and the free interface polymerization reaction is carried out for 5 min.

[0071] (3) After the reaction is completed, the unreacted aqueous monomer solution is removed by applying negative pressure, and then the excess organic monomer solution is poured off and washed with cyclohexane to obtain a full-bio-based polyester nascent membrane.

[0072] (4) The nascent membrane is placed in an oven at 80°C, and heat crosslinking is carried out for 15 min to obtain a full-bio-based polyester composite nanofiltration membrane.

[0073] The full-bio-based polyester composite nanofiltration membrane prepared in this example has a support layer base film and a nanofiltration separation layer, and the thickness of the nanofiltration separation layer is about 102 nm. Under the operation of cross flow at 5 bar, the permeation coefficient of pure water after stabilization is 35 L m -2 h -1 bar -1 ; and the rejection rate is 98.8% when 1000 ppm Congo red is used as the feed liquid.

[0074] Example 3

[0075] In this example, a full-bio-based polyester composite nanofiltration membrane is prepared using a polyether sulfone membrane with an average pore size of 0.22 μm as a base film, and the preparation process is as follows:

[0076] (1) 8 wt% raffinose is prepared as an aqueous monomer solution, and 0.5% sodium hydroxide of the mass of the aqueous monomer solution is added as a catalyst; 0.5 wt% 2,5-furandicarboxylic acid chloride organic monomer solution is prepared, and the organic solvent is n-hexane.

[0077] (2) Pour the aqueous monomer solution onto the polyethersulfone membrane, and then add the organic monomer solution to perform free interfacial polymerization for 2 min.

[0078] (3) After the reaction, remove the unreacted aqueous monomer solution by applying negative pressure, then pour off the excess organic monomer solution, and rinse with n-hexane to obtain a full-bio-based polyester nascent membrane.

[0079] (4) Place the nascent membrane in an oven at 100°C for thermal crosslinking for 5 min to obtain a full-bio-based polyester composite nanofiltration membrane.

[0080] The morphology of the full-bio-based polyester composite nanofiltration membrane prepared in this example is shown in FIG. 1, and the surface and cross-sectional electron micrographs are shown in FIGS. 2 and 3, respectively. Figure 2 Figure 3 Figure 4 The nanofiltration membrane has a support layer base membrane and a nanofiltration separation layer, and the thickness of the nanofiltration separation layer is about 96 nm. Under a cross-flow condition at 5 bar, the permeation coefficient of pure water after stabilization is 38.2 L m -2 h -1 bar -1 ; and the rejection rate is 98.2% when 1000 ppm Congo red is used as the feed liquid.

[0081] Example 4

[0082] In this example, a full-bio-based polyester composite nanofiltration membrane is prepared using a nylon membrane with an average pore size of 0.22 μm as a base membrane, and the preparation process is as follows:

[0083] (1) Prepare 5 wt% glucose as an aqueous monomer solution, and add sodium hydroxide as a catalyst at a mass fraction of 0.5% of the aqueous monomer solution; and prepare an organic monomer solution of 0.15 wt% 2,5-furandicarboxylic dichloride, with n-hexane as the organic solvent.

[0084] (2) Pour the aqueous monomer solution onto the nylon membrane, and then add the organic monomer solution to perform free interfacial polymerization for 5 min.

[0085] (3) After the reaction, remove the unreacted aqueous monomer solution by applying negative pressure, then pour off the excess organic monomer solution, and rinse with n-hexane to obtain a full-bio-based polyester nascent membrane.

[0086] (4) Place the nascent membrane in an oven at 60°C for thermal crosslinking for 10 min to obtain a full-bio-based polyester composite nanofiltration membrane.

[0087] The full-bio-based polyester composite nanofiltration membrane prepared in this example has a support layer base membrane and a nanofiltration separation layer, and the thickness of the nanofiltration separation layer is about 40 nm. Under a cross-flow condition at 5 bar, the permeation coefficient of pure water after stabilization is 34.2 L m -2 ​​h - 1 bar -1 ; the rejection rate was 96.3% with 1000 ppm Congo red as the feed solution.

[0088] Example 5

[0089] The full-bio-based polyester composite nanofiltration membrane prepared in Example 1 was applied to the separation of salt ions in an antibiotic desalination system, and the specific steps were as follows:

[0090] The full-bio-based polyester composite nanofiltration membrane prepared in Example 1 was operated under a cross-flow condition at 5 bar, and a tetracycline / sodium chloride solution of 1000 mg / L -1 / 1000 mg / L -1 was used as the feed solution. The test results showed that the rejection rate of the full-bio-based polyester composite nanofiltration membrane to tetracycline was 98.2%, the flux was 30.2 L / m -2 h -1 bar -1 , the rejection rate of sodium chloride was 9.5%, and the separation factor was 50.3.

[0091] The above results show that the full-bio-based polyester composite nanofiltration membrane obtained by the present technology has excellent permeation performance and separation effect on the antibiotic desalination system.

[0092] Example 6

[0093] The full-bio-based polyester composite nanofiltration membrane prepared in Example 4 was applied to the effective separation of solute molecules in a polar organic solution, and the specific steps were as follows:

[0094] The full-bio-based polyester composite nanofiltration membrane prepared in Example 4 was operated under a cross-flow condition at 5 bar, and a Congo red / ethanol solution of 50 mg / L -1 was used as the feed solution. The test results showed that the rejection rate of the full-bio-based polyester composite nanofiltration membrane was 99.2%, and the flux of the Congo red / ethanol solution was 21.6 L / m -2 h -1 bar -1 .

[0095] The above results show that the full-bio-based polyester composite nanofiltration membrane obtained by the present technology has excellent permeation performance and rejection performance on the polar organic solvent separation system.

[0096] Example 7

[0097] The full-bio-based polyester composite nanofiltration membrane used in Example 6 was subjected to active chlorine cleaning to restore the membrane performance, and the specific steps were as follows:

[0098] The full-bio-based polyester composite nanofiltration membrane used in Example 6 was immersed in active chlorine with a concentration of 100 ppm for 4 h to eliminate membrane fouling. The performance of the immersed membrane was tested, and the test results show that the rejection rate of the full-bio-based polyester composite nanofiltration membrane still remains above 99.0%, and the flux of the Congo red ethanol solution is 23.5 L m-2h-1bar-1. -2 h -1 bar -1 .

[0099] The above results show that the full-bio-based polyester composite nanofiltration membrane obtained by the present application has excellent structural chlorine resistance.

[0100] Although the present application is disclosed as above, the present application is not limited to this. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A fully biobased polyester composite nanofiltration membrane, characterized in that, The full-bio-based polyester composite nanofiltration membrane comprises a support layer base film and a nanofiltration separation layer disposed on the support layer base film, wherein the material of the nanofiltration separation layer is a polyester film constructed by reaction of a bio-based sugar monomer and a bio-based furanoyl chloride monomer, the bio-based sugar monomer is at least one selected from glucose, lactose, maltose and raffinose, and the bio-based furanoyl chloride monomer is 2,5-furandicarboxylic dichloride.

2. The all-bio-based polyester composite nanofiltration membrane according to claim 1, characterized in that, The thickness of the nanofiltration separation layer is 20-130 nm.

3. The all-bio-based polyester composite nanofiltration membrane according to claim 1 or 2, characterized in that, The material of the support layer base film is selected from one of polyether sulfone film, polysulfone film, polyacrylonitrile film, nylon film, cellulose acetate film, hydrophilically modified polyvinylidene fluoride film and hydrophilically modified polypropylene film.

4. The all-bio-based polyester composite nanofiltration membrane according to claim 3, characterized in that, The average pore size of the support layer base film is 0.05-0.5 μm.

5. The all-bio-based polyester composite nanofiltration membrane according to claim 1, wherein, The pure water permeation coefficient of the full-bio-based polyester composite nanofiltration membrane is 30-50 L m -2 h -1 bar -1 ; And / or, the permeation coefficient of the full-bio-based polyester composite nanofiltration membrane to polar organic solvents is 10-35 L m -2 h -1 bar -1 ; And / or, the rejection rate of the full-bio-based polyester composite nanofiltration membrane to monovalent salt is less than 10%, and the rejection rate to divalent salt is less than 20%; And / or, the molecular weight cut-off of the full-bio-based polyester composite nanofiltration membrane is 400-800 Da.

6. A method for preparing a fully biobased polyestcr composite nanofiltration membrane according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: dissolving the bio-based sugar monomer in water to obtain a bio-based sugar aqueous monomer solution; dissolving the bio-based furanoyl chloride monomer in an organic solvent to obtain a bio-based furanoyl chloride organic monomer solution; placing the bio-based sugar aqueous monomer solution above the support layer base film, and then placing the bio-based furanoyl chloride organic monomer solution above the bio-based sugar aqueous monomer solution to perform a free interface polymerization reaction to obtain a nanofiltration separation layer; applying negative pressure to remove excess monomers, and washing with an organic solvent to obtain a nascent membrane; heating the nascent membrane to perform a thermal crosslinking reaction to obtain a full-bio-based polyester composite nanofiltration membrane.

7. The method for preparing a full-bio-based polyester composite nanofiltration membrane according to claim 6, characterized in that, The concentration of the bio-based sugar aqueous monomer solution is 1-10 wt%; And / or, the concentration of the bio-based furanoyl chloride organic monomer solution is 0.1-0.5 wt%; And / or, the catalyst is selected from one of triethylamine, sodium hydroxide and sodium bicarbonate, and the concentration of the catalyst is 0.1-1 wt%.

8. The method for preparing a full-bio-based polyester composite nanofiltration membrane according to claim 6, characterized in that, The time of the free interface polymerization reaction is 2-10 min.

9. The method of producing a fully biobased polyester composite nanofiltration membrane according to claim 6, characterized in that, The temperature of the thermal crosslinking reaction is 60-100 ℃, and the time is 5-15 min.

10. Use of a fully biobased polyester composite nanofiltration membrane according to any one of claims 1-5, characterized in that, The full-bio-based polyester composite nanofiltration membrane is used for nanofiltration separation in a water system or an organic solvent system.

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