Full-bio-based polyester composite nanofiltration membrane as well as preparation method and application thereof

Abstract

The invention provides a full-bio-based polyester composite nanofiltration membrane and a preparation method and application thereof, the full-bio-based polyester composite nanofiltration membrane comprises a supporting layer base membrane and a nanofiltration separation layer arranged on the supporting layer base membrane, and the nanofiltration separation layer is a polyester membrane constructed by reaction of bio-based saccharide monomers and bio-based furanyl chloride monomers. According to the nanofiltration separation layer, the bio-based saccharide monomer and the bio-based furan acyl chloride monomer serve as reactants, the two monomers are derived from biomass and meet the green and environment-friendly requirements, meanwhile, the used raw materials are low in price and easy to prepare on a large scale, and the nanofiltration separation layer has important significance for promoting development of next-generation green membrane materials.

Description

Technical Field

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

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

[0003] The promotion of biotechnology revolution and industrial revolution has promoted the rapid development of bio-based materials. The industry is actively promoting bio-based materials to replace non-renewable fossil-based materials. In recent years, some existing technologies have proposed new bio-based nanofiltration membranes, using bio-based monomers such as cucurbituril, stevioside, glucose, etc. to prepare polyamide nanofiltration membranes and polyester membranes, but the existing technology still needs to use non-renewable fossil-based trimesoyl chloride monomers for interfacial polymerization.

[0004] In addition, the structural precision, stability, permeability, molecular selectivity, and preparation controllability of bio-based nanofiltration membranes are also difficulties faced by existing technologies. In order to achieve the goals of sustainable development, energy conservation and emission reduction, and environmentally friendly economic development, it is of great significance to develop high-performance all-bio-based nanofiltration membranes. Summary of the invention

[0005] In view of the deficiencies of the prior art, the object of the present invention is to provide a new all-biobased nanofiltration membrane that is environmentally friendly and has excellent separation performance and stability.

[0006] To achieve the above objectives, the first method of the present invention provides a fully bio-based polyester composite nanofiltration membrane, comprising a support layer base membrane, and a nanofiltration separation layer disposed on the support layer base membrane, wherein the material of the nanofiltration separation layer is a polyester membrane constructed by the reaction of bio-based sugar monomers and bio-based furanyl chloride monomers.

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

[0008] Furthermore, the bio-based furanoyl chloride monomer is 2,5-furandicarboxylic acid chloride.

[0009] The nanofiltration separation layer of the present invention uses bio-based sugar monomers and bio-based furanoyl chloride monomers as reactants. Both monomers used are derived from biomass, achieving full replacement of aromatic monomers, meeting green environmental protection requirements. At the same time, the raw materials used are inexpensive and easy to prepare on a large scale, which is of great significance for promoting the development of the next generation of green membrane materials.

[0010] Furthermore, the thickness of the nanofiltration separation layer is 20 to 130 nm.

[0011] Furthermore, the material of the support layer base membrane is selected from one of polyethersulfone membrane, polysulfone membrane, polyacrylonitrile membrane, nylon membrane, cellulose acetate membrane, hydrophilically modified polyvinylidene fluoride membrane, and hydrophilically modified polypropylene membrane.

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

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

[0014] Furthermore, the pure water permeability coefficient of the all-biobased polyester composite nanofiltration membrane is 30 to 50 L m -2 h -1 bar -1 .

[0015] Furthermore, the permeability coefficient of the all-biobased polyester composite nanofiltration membrane to polar organic solvents is 10 to 35 Lm -2 h -1 bar -1 .

[0016] Furthermore, the retention rate of the all-biobased polyester composite nanofiltration membrane for monovalent salts is less than 10%, and the retention rate for divalent salts is less than 20%.

[0017] Furthermore, the molecular weight cutoff of the all-biobased polyester composite nanofiltration membrane is 400-800Da.

[0018] Both bio-based sugar monomers and bio-based furanoyl chloride monomers have rich polar structures and excellent affinity for water molecules and polar solvents, and can achieve high permeability separation in water environment systems and polar solvent systems.

[0019] The second aspect of the present invention provides a method for preparing the above-mentioned all-biobased polyester composite nanofiltration membrane, comprising the following steps:

[0020] Dissolving a bio-based sugar small molecule monomer in water, adding a catalyst, and obtaining a bio-based sugar aqueous monomer solution;

[0021] dissolving the bio-based furanoyl chloride monomer in an organic solvent to obtain a bio-based furanoyl chloride organic phase monomer solution;

[0022] Placing the bio-based sugar aqueous monomer solution on the support layer basement membrane, and then placing the bio-based furanoyl chloride organic monomer solution on the bio-based sugar aqueous monomer solution, and performing free interface polymerization reaction to obtain a nanofiltration separation layer;

[0023] Applying negative pressure to remove excess monomers and washing with an organic solvent to obtain a primary membrane;

[0024] The primary membrane is heated to carry out a thermal cross-linking reaction to obtain a fully bio-based polyester composite nanofiltration membrane.

[0025] Furthermore, the concentration of the bio-based sugar aqueous monomer solution is 1 to 10 wt %.

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

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

[0028] Furthermore, the free interface polymerization reaction time is 2 to 10 minutes.

[0029] Furthermore, the temperature of the thermal cross-linking reaction is 60-100° C., and the time is 5-15 minutes.

[0030] The present invention uses bio-based sugar monomers and bio-based furanoyl chloride monomers as reaction monomers, and in-situ constructs a polyester membrane on a support layer base membrane through free interfacial 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 by an ester bond and have excellent stability; the bio-based furanoyl chloride monomer contains a polar furan ring, which can realize the kinetics and thermodynamic regulation of the interfacial polymerization reaction, thereby accurately controlling the structure of the nanofiltration separation layer.

[0031] The third aspect of the present invention provides an application of the above-mentioned all-bio-based polyester composite nanofiltration membrane, wherein the all-bio-based polyester composite nanofiltration membrane is used for nanofiltration separation of water systems or organic solvent systems. The present invention uses all-bio-based monomers as reaction monomers to construct an all-bio-based polyester composite nanofiltration membrane, which has the advantages of high permeability and high molecular selectivity, and has broad application prospects in deep treatment of water and organic solvent systems such as separation and purification of small molecules and molecular separation in organic solvent systems.

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

[0033] (1) The present invention uses bio-based sugars and bio-based furanoyl chloride monomers as raw materials for preparing the nanofiltration separation layer, without the need to use aromatic monomers, which meets green environmental protection requirements. At the same time, the raw materials are low in price and easy to mass produce.

[0034] (2) The bio-based furanyl chloride monomer used in the present invention contains a polar furan ring, which can achieve kinetic and thermodynamic regulation of the interfacial polymerization reaction by forming hydrogen bonds and other effects, thereby regulating the structure and performance of the nanofiltration membrane.

[0035] (3) The present invention constructs the nanofiltration separation layer in situ by free interface polymerization, so that the support layer base membrane is highly strongly bonded to the nanofiltration separation layer.

[0036] (4) The nanofiltration separation layer constructed in the present invention is connected to the support layer base membrane through an ester bond, has excellent chlorine resistance, and can maintain structural stability during the membrane cleaning process.

[0037] (5) The bio-based sugar monomers and bio-based furanoyl chloride monomers used in the present invention have rich polar structures and excellent affinity for water molecules and polar solvents, and can achieve efficient osmotic separation in water environment systems and polar solvent systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a photo of the all-biobased polyester composite nanofiltration membrane prepared in Example 1 of the present invention.

[0039] Figure 2 This is a photo of the all-biobased polyester composite nanofiltration membrane prepared in Example 3 of the present invention.

[0040] Figure 3 This is a surface electron micrograph of the all-biobased polyester composite nanofiltration membrane prepared in Example 3 of the present invention.

[0041] Figure 4 This is a cross-sectional electron micrograph of the all-biobased polyester composite nanofiltration membrane prepared in Example 3 of the present invention. DETAILED DESCRIPTION

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

[0043] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0044] A specific embodiment of the present invention provides a fully bio-based polyester composite nanofiltration membrane, which includes a support layer base membrane and a nanofiltration separation layer disposed on the support layer base membrane, wherein the material of the nanofiltration separation layer is a polyester membrane constructed by the reaction of bio-based sugar monomers and bio-based furanyl chloride monomers.

[0045] In a specific embodiment, the bio-based sugar monomers may be selected from glucose, lactose, maltose, raffinose, etc.; the bio-based furanoyl chloride monomer is preferably 2,5-furandicarboxylic acid chloride. The reaction monomers used in the nanofiltration separation layer are all derived from biomass, which meets the requirements of green environmental protection. In addition, the bio-based sugar monomers and bio-based furanoyl chloride monomers have rich polar structures and excellent affinity for water molecules and polar solvents, which can achieve high permeability separation in water environment systems and polar solvent systems.

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

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

[0048] The preparation method of the above-mentioned all-biobased polyester composite nanofiltration membrane specifically comprises the following steps:

[0049] S1. Dissolving a bio-based sugar small molecule monomer in water, adding a catalyst, and obtaining a bio-based sugar aqueous monomer solution.

[0050] In a specific embodiment, 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 may be triethylamine, sodium hydroxide, sodium bicarbonate, or the like.

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

[0052] In a specific embodiment, the organic solvent may be n-hexane, cyclohexane, etc.; the concentration of the bio-based furanyl 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 on top of the support layer base membrane, and placing the bio-based furanoyl chloride organic monomer solution obtained in step S2 on top of the bio-based sugar aqueous monomer solution, and performing free interfacial polymerization reaction to obtain a nanofiltration separation layer; applying negative pressure to remove excess monomers, and washing with an organic solvent to obtain a primary membrane.

[0054] In a specific embodiment, the free interface polymerization reaction time is 2 to 10 minutes.

[0055] S4, heating the primary membrane obtained in step S3 to perform a thermal cross-linking reaction to obtain a fully bio-based polyester composite nanofiltration membrane.

[0056] In a specific embodiment, the temperature of the thermal crosslinking reaction is 60-100° C., and the time is 5-15 minutes.

[0057] The all-biobased polyester composite nanofiltration membrane provided in the above specific embodiment has the advantages of high permeability and high molecular selectivity.

[0058] The bio-based polyester composite nanofiltration membrane is constructed with all-bio-based monomers as reaction monomers, which has the advantages of high permeability and high molecular selectivity. Its pure water permeability coefficient is 30-50 L m -2 h -1 bar -1 The permeability coefficient of organic solvents is 10-35 L m - 2 h -1 bar -1 The retention rate of monovalent salt is less than 10%, the retention rate of divalent salt is less than 20%, and the molecular weight cutoff is 400-800Da, which can achieve high permeability separation of water environment system and organic solvent system.

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

[0060] Example 1

[0061] In this embodiment, a polyethersulfone membrane with an average pore size of 0.22 μm is used as a base membrane to prepare a fully bio-based polyester composite nanofiltration membrane. The preparation process is as follows:

[0062] (1) preparing a 5 wt % aqueous phase monomer solution of glucose, and adding 0.5 wt % of the mass of the aqueous phase monomer solution of sodium hydroxide as a catalyst; preparing a 0.15 wt % 2,5-furandicarboxylic acid chloride organic phase monomer solution, wherein the organic solvent is n-hexane.

[0063] (2) The aqueous monomer solution was poured onto the polyethersulfone membrane, and then the organic monomer solution was added to carry out free interfacial polymerization for 5 minutes.

[0064] (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 out and rinsed with n-hexane to obtain a fully bio-based polyester primary film.

[0065] (4) The primary membrane was placed in an oven at 60°C and thermally cross-linked for 10 minutes to obtain a fully bio-based polyester composite nanofiltration membrane.

[0066] The macroscopic morphology of the all-biobased polyester composite nanofiltration membrane prepared in this example is as follows: Figure 1The bio-based polyester composite nanofiltration membrane has a support layer base membrane and a nanofiltration separation layer, and the thickness of the nanofiltration separation layer is about 98nm. When operating under 5bar cross-flow conditions, the permeability coefficient of pure water after stabilization is 32L m -2 h -1 bar -1 ; Using 1000ppm Congo red as the feed liquid, the retention rate reached 99.9%.

[0067] Example 2

[0068] In this embodiment, a polyethersulfone membrane with an average pore size of 0.22 μm is used as a base membrane to prepare a fully bio-based polyester composite nanofiltration membrane. The preparation process is as follows:

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

[0070] (2) The aqueous monomer solution was poured onto the polyethersulfone membrane, and then the organic monomer solution was added to carry out free interfacial polymerization for 5 minutes.

[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 out and rinsed with cyclohexane to obtain a fully bio-based polyester primary film.

[0072] (4) The primary membrane was placed in an oven at 80°C and thermally cross-linked for 15 minutes to obtain a fully bio-based polyester composite nanofiltration membrane.

[0073] The all-biobased 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 102nm. When operated under 5bar cross-flow conditions, the permeability coefficient of pure water after stabilization is 35L m -2 h -1 bar -1 ; Using 1000ppm Congo red as the feed liquid, the retention rate is 98.8%.

[0074] Example 3

[0075] In this embodiment, a polyethersulfone membrane with an average pore size of 0.22 μm is used as a base membrane to prepare a fully bio-based polyester composite nanofiltration membrane. The preparation process is as follows:

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

[0077] (2) The aqueous monomer solution was poured onto the polyethersulfone membrane, and then the organic monomer solution was added to carry out free interfacial polymerization for 2 minutes.

[0078] (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 out and rinsed with n-hexane to obtain a fully bio-based polyester primary film.

[0079] (4) The primary membrane was placed in an oven at 100°C and thermally cross-linked for 5 minutes to obtain a fully bio-based polyester composite nanofiltration membrane.

[0080] The morphology of the all-biobased polyester composite nanofiltration membrane prepared in this example is as follows Figure 2 The surface and cross-sectional electron microscopy images are shown in Figure 3 and Figure 4 As shown in FIG. 1 , 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. When operated under cross-flow conditions at 5 bar, the permeability coefficient of pure water after stabilization is 38.2 L m -2 h -1 bar -1 ; Using 1000ppm Congo red as the feed liquid, the retention rate is 98.2%.

[0081] Example 4

[0082] In this example, a nylon membrane with an average pore size of 0.22 μm was used as a base membrane to prepare a fully bio-based polyester composite nanofiltration membrane. The preparation process is as follows:

[0083] (1) 5 wt% glucose was prepared as an aqueous monomer solution, and 0.5% of the mass of the aqueous monomer solution of sodium hydroxide was added as a catalyst; 0.15 wt% of 2,5-furandicarboxylic acid chloride was prepared as an organic monomer solution, and the organic solvent was n-hexane.

[0084] (2) The aqueous monomer solution was poured onto the nylon membrane, and then the organic monomer solution was added to carry out free interfacial polymerization for 5 minutes.

[0085] (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 out and rinsed with n-hexane to obtain a fully bio-based polyester primary film.

[0086] (4) The primary membrane was placed in an oven at 60°C and thermally cross-linked for 10 minutes to obtain a fully bio-based polyester composite nanofiltration membrane.

[0087] The 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. When operated under 5 bar cross-flow conditions, the permeability coefficient of pure water after stabilization is 34.2 L m -2h - 1 bar -1 ; Using 1000ppm Congo red as the feed liquid, the retention rate is 96.3%.

[0088] Example 5

[0089] The all-biobased polyester composite nanofiltration membrane prepared in Example 1 is applied to the separation of salt ions in the antibiotic desalination system, and the specific steps are as follows:

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

[0091] The above results show that the all-biobased polyester composite nanofiltration membrane obtained by the technology of the present invention has excellent permeability and separation effect for the antibiotic desalination system.

[0092] Example 6

[0093] The all-biobased polyester composite nanofiltration membrane prepared in Example 4 is applied to effectively separate solute molecules in polar organic solutions, and the specific steps are as follows:

[0094] The bio-based polyester composite nanofiltration membrane prepared in Example 4 was operated under 5 bar cross-flow conditions at 50 mg / L -1 The Congo red / ethanol solution was used as the feed solution. The test results showed that the rejection rate of the all-biobased 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 all-biobased polyester composite nanofiltration membrane obtained by the technology of the present invention has excellent permeability and retention performance for the polar organic solvent separation system.

[0096] Example 7

[0097] In Example 6, the used all-biobased polyester composite nanofiltration membrane is cleaned with active chlorine to restore the membrane performance. The specific steps are as follows:

[0098] The all-biobased polyester composite nanofiltration membrane used in Example 6 was immersed in active chlorine at a concentration of 100 ppm for 4 hours to eliminate membrane contamination. The membrane performance after immersion was tested. The test results showed that the retention rate of the all-biobased polyester composite nanofiltration membrane was still maintained above 99.0%, and the flux of Congo red ethanol solution was 23.5 L m -2 h -1 bar -1 .

[0099] The above results show that the all-biobased polyester composite nanofiltration membrane obtained by the technology of the present invention has excellent structural chlorine resistance.

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

Claims

1. A fully bio-based polyester composite nanofiltration membrane, characterized in that: The invention comprises a supporting layer base membrane and a nanofiltration separation layer arranged on the supporting layer base membrane. The material of the nanofiltration separation layer is a polyester membrane constructed by the reaction of bio-based sugar monomers and bio-based furanyl chloride monomers.

2. The all-biobased polyester composite nanofiltration membrane according to claim 1, characterized in that: The bio-based sugar monomer is selected from at least one of glucose, lactose, maltose and raffinose.

3. The all-biobased polyester composite nanofiltration membrane according to claim 1, characterized in that: The bio-based furanoyl chloride monomer is 2,5-furandicarboxylic acid chloride.

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

5. The all-biobased polyester composite nanofiltration membrane according to any one of claims 1 to 4, characterized in that: The material of the support layer base membrane is selected from one of polyethersulfone membrane, polysulfone membrane, polyacrylonitrile membrane, nylon membrane, cellulose acetate membrane, hydrophilically modified polyvinylidene fluoride membrane and hydrophilically modified polypropylene membrane.

6. The all-biobased polyester composite nanofiltration membrane according to claim 5, characterized in that: The average pore size of the support layer base membrane is 0.05-0.5 μm.

7. The all-biobased polyester composite nanofiltration membrane according to claim 1, characterized in that: The pure water permeability coefficient of the all-biobased polyester composite nanofiltration membrane is 30 to 50 L m -2 h -1 bar -1 ; And / or, the permeability coefficient of the all-biobased polyester composite nanofiltration membrane to polar organic solvents is 10 to 35 L m -2 h - 1 bar -1 ; And / or, the retention rate of the all-biobased polyester composite nanofiltration membrane for monovalent salts is less than 10%, and the retention rate of the divalent salts is less than 20%; And / or, the molecular weight cutoff of the all-biobased polyester composite nanofiltration membrane is 400-800Da.

8. A method for preparing a fully bio-based polyester composite nanofiltration membrane as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: Dissolving a bio-based sugar small molecule monomer in water, adding a catalyst, and obtaining 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 phase monomer solution; Placing the bio-based sugar aqueous monomer solution on the support layer basement membrane, and then placing the bio-based furanoyl chloride organic monomer solution on the bio-based sugar aqueous monomer solution, and performing 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 primary membrane; The primary membrane is heated to carry out a thermal cross-linking reaction to obtain a fully bio-based polyester composite nanofiltration membrane.

9. The method for preparing the all-biobased polyester composite nanofiltration membrane according to claim 8, characterized in that: The concentration of the bio-based sugar aqueous monomer solution is 1 to 10 wt %; and / or, the concentration of the bio-based acyl chloride organic phase monomer solution is 0.1 to 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 0.1-1wt%.

10. The method for preparing the all-biobased polyester composite nanofiltration membrane according to claim 8, characterized in that: The free interface polymerization reaction time is 2 to 10 minutes.

11. The method for preparing the all-biobased polyester composite nanofiltration membrane according to claim 8, characterized in that: The temperature of the thermal crosslinking reaction is 60-100° C., and the time is 5-15 minutes.

12. An application of the all-biobased polyester composite nanofiltration membrane as claimed in any one of claims 1 to 7, characterized in that: The all-biobased polyester composite nanofiltration membrane is used for nanofiltration separation of water systems or organic solvent systems.

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