Hybrid polyamide membrane containing intrinsic microporous polymer as well as preparation method and application of hybrid polyamide membrane

Abstract

The invention discloses a hybrid polyamide membrane containing an intrinsic microporous polymer as well as a preparation method and application of the hybrid polyamide membrane, and belongs to the technical field of membrane separation. The preparation method comprises the following steps: soaking a porous support base membrane in an aqueous phase monomer solution containing an intrinsic microporous polymer, and then soaking in an organic phase monomer solution for reaction to prepare the hybrid polyamide membrane containing the intrinsic microporous polymer. A unique nano-pore channel of the self-contained microporous polymer can construct a nano-channel beneficial to molecular transport in the membrane, so that the permeability of the membrane is improved; the self-contained microporous polymer can be covalently crosslinked and anchored in the membrane, so that the non-selective defect of the interface is reduced, and the stability of the membrane structure in the operation process is improved; the introduction of the self-contained microporous polymer can improve the hydrophilicity of the membrane and strengthen the selective transmission of water. The preparation process is simple and convenient, the prepared membrane is applied to pervaporation ethanol-water separation, and the permeation flux and separation factors of the membrane can be improved.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of membrane separation, and particularly relates to a hybrid polyamide membrane containing self-microporous polymer, a preparation method thereof and an application thereof. Background Art

[0002] Membrane separation is a new separation technology, which has the advantages of energy conservation, environmental protection, green efficiency, convenient operation, etc. Membrane materials are the core of membrane separation technology. Polymers have the advantages of strong film-forming property, low cost, easy scale-up, etc. Especially polyamide membranes, which are prepared by interfacial polymerization reaction between amine monomers and polyacyl chlorides, have the advantages of thin thickness, strong solvent resistance and good thermal stability. However, the surface hydrophilicity of polyamide membranes is insufficient and the chain segment packing density is not enough, making it difficult to form a dense and defect-free separation layer, which limits its application in pervaporation separation. Previously, we used in-situ polymerization of quantum dots to regulate the degree of interfacial polymerization reaction of monomers and optimize the structure of polyamide membranes, achieving an improvement in pervaporation separation performance (CN202410579246.2). However, the pore channels of the polymer membranes obtained by this method are still irregular free volume cavities. Considering the problem that the polymer membranes are prone to swelling under extreme working conditions, resulting in unstable separation performance, it is necessary to develop new modified materials.

[0003] Self-microporous polymers have attracted extensive attention from researchers due to their adjustable surface chemical properties and customizable pore structures. Self-microporous polymers have a non-planar spatial structure, and their unique rigid twisted structure can hinder the folding between chain segments, thereby generating highly dense and interconnected inherent micropores, which can serve as molecular transport channels. In addition, they have good mechanical properties, solubility and thermal stability. Lin et al. modified polyamide membranes with self-microporous polymers and achieved effective interception of salt ions (Chinese Journal of Chemical Engineering, 2022, 45:194 - 202), confirming the positive effect of self-microporous polymers on improving membrane separation performance. Currently, there have been studies on physically blending self-microporous polymers with polymers to improve the pervaporation separation performance of membranes, but the improvement effect is limited. Reasonable functional design of self-microporous polymers, regulation of the degree of interfacial polymerization reaction of monomers, optimization of the structure of polyamide membranes, and improvement of the matching degree between the two are expected to improve the pervaporation separation performance. Summary of the Invention

[0004] The object of the present invention is to provide a hybrid polyamide membrane containing self-integrated microporous polymer, and its preparation method and application. In the present invention, two kinds of NPIM containing amino groups are respectively prepared, and the physical structure and chemical properties of the membrane are regulated by NPIM. The microporous structure of NPIM can construct additional molecular mass transfer channels in the membrane, and the amino groups on its surface can covalently crosslink with polyacyl chloride to anchor it in the membrane, preventing the loss of NPIM during the operation process, and at the same time improving the hydrophilicity of the membrane. The preparation process of the hybrid polyamide membrane containing NPIM is simple in operation and can effectively separate alcohol-water by pervaporation.

[0005] In order to achieve the object of the present invention, the following technical solutions are adopted: The preparation method of the hybrid polyamide membrane containing self-integrated microporous polymer prepared by the present invention comprises the following steps: Disperse the self-integrated microporous polymer in the aqueous solution of amine monomer to obtain an aqueous dispersion, soak the porous support substrate membrane in the aqueous dispersion, and then soak it in the organic phase monomer solution to carry out an interfacial polymerization reaction. After heat treatment, a hybrid polyamide membrane containing self-integrated microporous polymer is obtained.

[0006] Further, the amine monomer is one of ethylenediamine, m-phenylenediamine, and diethylenetriamine; the concentration of the amine monomer is 0.5 - 5 mg / mL.

[0007] Further, the content of the self-polymerized microporous polymer in the aqueous dispersion is 0.05 - 0.2 mg / mL.

[0008] Further, the soaking time of the porous support substrate membrane in the aqueous dispersion is 2 - 20 min.

[0009] Further, the organic phase monomer is one of trimesoyl chloride, terephthaloyl chloride, and isophthaloyl chloride; the concentration of the organic phase monomer is 0.5 - 1.5 mg / mL; the organic phase is one of n-hexane and n-heptane.

[0010] Further, the reaction time is 1 - 5 min.

[0011] Further, the heat treatment temperature is 50 - 80 °C, and the heat treatment time is 5 - 20 min.

[0012] The preparation method of the self-integrated microporous polymer as amino-functionalized NPIM is: (1) Dissolve 2,3,5,6-tetrafluoroterephthalonitrile and 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane in N,N-dimethylacetamide, add potassium carbonate, stir and react at 160 °C, then dilute with toluene, pour into methanol to precipitate, and obtain PIM-1; wherein, the molar ratio of 2,3,5,6-tetrafluoroterephthalonitrile:5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane:potassium carbonate is 1:1:3.

[0013] (2) Dissolve PIM-1 in tetrahydrofuran, add hydroxylamine, heat under reflux for 20 h, wash the crude product with ethanol and water, and obtain amino-functionalized NPIM-1 after drying; wherein, the mass ratio of PIM-1 to hydroxylamine is 1:12.

[0014] Or dissolve PIM-1 in methanol, add diethylenetriamine and N-acetylcysteine, heat and react at 60 °C for 48 h, wash the crude product with n-hexane and methanol, then absorb with sodium hydroxide, extract with dichloromethane, and obtain amino-functionalized NPIM-2 after drying; wherein, the mass ratio of PIM-1:diethylenetriamine:N-acetylcysteine is 1:2:3.3.

[0015] The structural formulas of PIM-1, NPIM-1 and NPIM-2 are respectively: .

[0016] Preferably, the self-integrated microporous polymer is NPIM-2.

[0017] Another object of the present invention is to provide a hybrid polyamide membrane containing a self-integrated microporous polymer.

[0018] Another object of the present invention is to provide an application of a hybrid polyamide membrane containing a self-integrated microporous polymer in pervaporation ethanol-water separation, with an operating temperature of 76 °C and a water content of 10 wt% in the feed liquid.

[0019] Compared with the prior art, the beneficial effects of the present invention are: In the present invention, amino-functionalized NPIM is synthesized to regulate the structure of the polyamide membrane. NPIM-1 and NPIM-2 are prepared. The abundant amino groups in their structures can covalently crosslink with organic phase monomers, stabilize NPIM in the membrane, and prevent the decline of separation performance caused by the loss of NPIM during operation; the intrinsic microporous structure of NPIM can construct additional molecular mass transfer channels in the membrane, and the hydrophilic groups of NPIM are beneficial to form a water molecule selective mass transfer channel in the membrane, which can enhance the water selective separation. Description of the Drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings. Among them: Figure 1 (a) is the 1 1H NMR spectrum of PIM-1; (b) is the infrared spectra of PIM-1, NPIM-1, and NPIM-2; Figure 2 (a) is the surface scanning electron micrograph of NPIM-1; (b) is the surface scanning electron micrograph of NPIM-2; Figure 3 is the surface scanning electron micrograph of Example 1; Figure 4 is the surface scanning electron micrograph of Example 5; Figure 5 is the surface scanning electron micrograph of Comparative Example 1. Detailed Embodiments

[0021] To further understand the purpose, content, and advantages of the present invention, the specific implementation schemes of the present invention are described in detail as follows. However, it cannot be limited to the following examples only, and should be freely combined according to the actual situation. The endpoints and any values within the disclosed ranges in this article are not limited to the exact ranges and values. For numerical ranges, the endpoints of each range, between the endpoints of each range and individual point values, and between 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.

[0022] The following is a further detailed description in combination with some specific examples and comparative examples: Among them, the preparation process of the carboxylated polyacrylonitrile ultrafiltration membrane described below is as follows: Immerse the polyacrylonitrile ultrafiltration membrane in an aqueous sodium hydroxide solution with a concentration of 1.5 M and a temperature of 55 °C for heat treatment for 1 h, then immerse it in an aqueous hydrochloric acid solution with a concentration of 1.5 M at room temperature for 1 h, and wash it with deionized water to obtain a carboxylated polyacrylonitrile ultrafiltration membrane.

[0023] Example 1: This example provides a method for preparing a hybrid polyamide membrane containing a polymer of intrinsic microporosity, specifically: Dissolve 15 mmol of 2,3,5,6-tetrafluoroterephthalonitrile and 15 mmol of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane in 30 mL of N,N-dimethylacetamide, add 45 mmol of potassium carbonate, stir and react at 160 °C, then dilute with 40 mL of toluene, pour into 300 mL of methanol to precipitate, and obtain PIM-1; Then dissolve 0.5 g of PIM-1 in 30 mL of tetrahydrofuran, add 6 g of hydroxylamine, heat and reflux for 20 h, wash the crude product with ethanol and water, and dry to obtain amino-functionalized NPIM-1; Immerse the carboxyl polyacrylonitrile ultrafiltration membrane in a dispersion containing 0.10 mg / mL of NPIM-1 and 1 mg / mL of diethylenetriamine for 3 min, then immerse in n-hexane containing 1 mg / mL of trimesoyl chloride for 1 min for interfacial polymerization reaction, and heat-treat at 60 °C for 10 min to obtain a hybrid polyamide membrane containing NPIM-1, denoted as Membrane 1.

[0024] Apply the hydrophilic membrane of Membrane 1 to pervaporation ethanol-water separation. When the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 3553 g m -2 h -1 , and the separation factor is 1210. Figure 3 Figure 1 is the scanning electron microscope image of the surface of Membrane 1.

[0025] Example 2: The difference between this example and Example 1 is that the concentration of NPIM-1 is adjusted to 0.05 mg / mL, and the rest of the process steps are referred to Example 1 to obtain a hybrid polyamide membrane containing NPIM-1, denoted as Membrane 2.

[0026] Apply Membrane 2 to pervaporation ethanol-water separation. When the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 3409 g m -2 h -1 , and the separation factor is 1044.

[0027] Example 3: The difference between this example and Example 1 is that the concentration of NPIM-1 is adjusted to 0.15 mg / mL, and the rest of the process steps are referred to Example 1 to obtain a hybrid polyamide membrane containing NPIM-1, denoted as Membrane 3.

[0028] Apply Membrane 3 to pervaporation ethanol-water separation. When the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 3789 g m -2 h -1 , and the separation factor is 604.

[0029] Example 4: The difference between this example and Example 1 is that the concentration of NPIM-1 is adjusted to 0.20 mg / mL, and the rest of the process steps refer to Example 1, obtaining a hybrid polyamide membrane containing NPIM-1, denoted as Membrane 4.

[0030] Membrane 4 was applied to pervaporation ethanol-water separation. When the operating temperature was 76 °C and the water content in the feed liquid was 10 wt%, the permeation flux was 3380 g m -2 h -1 , and the separation factor was 242.

[0031] Example 5: 15 mmol of 2,3,5,6-tetrafluoroterephthalonitrile and 15 mmol of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane were dissolved in 30 mL of N,N-dimethylacetamide, 45 mmol of potassium carbonate was added, and the mixture was stirred and reacted at 160 °C. Then 40 mL of toluene was added for dilution, and the mixture was poured into 300 mL of methanol to precipitate a solid, obtaining PIM-1; 0.5 g of PIM-1 was dissolved in 10 mL of methanol, 1 g of diethylenetriamine and 1.63 g of N-acetylcysteine were added, and the mixture was heated and reacted at 60 °C for 48 h. The crude product was washed with n-hexane and methanol, absorbed by sodium hydroxide, extracted with dichloromethane, and dried to obtain amino-functionalized NPIM-2.

[0032] The difference between this example and Example 1 is that NPIM-1 was changed to NPIM-2, and the rest of the process steps refer to Example 1, obtaining a hybrid polyamide membrane containing NPIM-2, denoted as Membrane 5.

[0033] Membrane 5 was applied to pervaporation ethanol-water separation. When the operating temperature was 76 °C and the water content in the feed liquid was 10 wt%, the permeation flux was 3974 g m -2 h -1 , and the separation factor was 1178. Figure 4 is the scanning electron micrograph of the surface of Membrane 5.

[0034] Example 6: The difference between this example and Example 1 is that NPIM-1 was changed to NPIM-2 and the concentration was changed to 0.05 mg / mL, and the rest of the process steps refer to Example 1, obtaining a hybrid polyamide membrane containing NPIM-2, denoted as Membrane 6.

[0035] Membrane 6 was applied to pervaporation ethanol-water separation. When the operating temperature was 76 °C and the water content in the feed liquid was 10 wt%, the permeation flux was 3779 g m -2 h -1 , and the separation factor was 1730.

[0036] Example 7: The difference between this example and Example 1 is that NPIM-1 is changed to NPIM-2, and the concentration is changed to 0.15 mg / mL. The remaining steps are the same as those in Example 1, and a hybrid polyamide membrane containing NPIM-2 is obtained, denoted as Membrane 7.

[0037] When Membrane 7 is applied to pervaporation ethanol-water separation, when the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 4225 g m -2 h -1 , and the separation factor is 1797.

[0038] Example 8: The difference between this example and Example 1 is that NPIM-1 is changed to NPIM-2, and the concentration is changed to 0.20 mg / mL. The remaining steps are the same as those in Example 1, and a hybrid polyamide membrane containing NPIM-2 is obtained, denoted as Membrane 8.

[0039] When Membrane 8 is applied to pervaporation ethanol-water separation, when the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 3491 g m -2 h -1 , and the separation factor is 1306.

[0040] Example 9: The difference between this example and Example 1 is that diethylenetriamine is changed to ethylenediamine, and the remaining steps are the same as those in Example 1.

[0041] That is, the carboxyl polyacrylonitrile ultrafiltration membrane is immersed in an aqueous dispersion containing 0.10 mg / mL NPIM-1 and 1 mg / mL ethylenediamine for 3 min, and then immersed in n-hexane containing 1 mg / mL trimesoyl chloride for 1 min for interfacial polymerization reaction. After heat treatment at 60 °C for 10 min, a hybrid polyamide membrane containing NPIM-1 is obtained, denoted as Membrane 9.

[0042] When Membrane 9 is applied to pervaporation ethanol-water separation, when the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 3152 g m -2 h -1 , and the separation factor is 1080.

[0043] Example 10: The difference between this example and Example 1 is that diethylenetriamine is changed to m-phenylenediamine, and the remaining steps are the same as those in Example 1, and a hybrid polyamide membrane containing NPIM-1 is obtained, denoted as Membrane 10.

[0044] When Membrane 10 is applied to pervaporation ethanol-water separation, when the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 3157 g m -2 h -1, the separation factor is 1182.

[0045] Comparative Example 1: The difference between this comparative example and Example 1 is that NPIM is not added, and the remaining process steps are all referred to Example 1 to obtain the polyamide film of this comparative example, denoted as Comparative Film 1.

[0046] Applying Comparative Film 1 to pervaporation ethanol-water separation, when the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 2733 g m -2 h -1 , and the separation factor is 721. Figure 5 is the surface scanning electron micrograph of Comparative Film 1.

[0047] Comparative Example 2: The difference between this comparative example and Example 5 is that NPIM-2 is changed to PIM-1, and the remaining process steps are all referred to Example 5 to obtain the hybrid polyamide film containing PIM-1, denoted as Comparative Film 2.

[0048] Applying Comparative Film 2 to pervaporation ethanol-water separation, when the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 3318 g m -2 h -1 , and the separation factor is 825.

[0049] Comparative Example 3: The difference between this comparative example and Example 1 is that diethylenetriamine is not added, and the remaining process steps are all referred to Example 1 to obtain the polyamide film containing NPIM-1, denoted as Comparative Film 3.

[0050] Applying Comparative Film 3 to pervaporation ethanol-water separation, when the operating temperature is 76 °C and the water content of the feed liquid is 10 wt%, the permeation flux is 10418 g m -2 h -1 , and the separation factor is 315.

[0051] Table 1 membrane <![CDATA[Permeation flux (g m -2 h -1 ).]]> separation factor membrane 1 3553 1210 membrane 2 3409 1044 membrane 3 3789 604 membrane 4 3380 242 membrane 5 3974 1178 membrane 6 3779 1730 membrane 7 4225 1797 membrane 8 3491 1306 membrane 9 3152 1080 membrane 10 3157 1182 comparative membrane 1 2733 721 comparative membrane 2 3318 825 comparative membrane 3 10418 315 In order to enhance the pervaporation separation performance of polyamide membranes, two kinds of amino-NPIMs were prepared to regulate the structure of polyamide membranes. Compared with unfunctionalized PIM-1, amino-NPIMs can significantly improve the separation performance of polyamide membranes. By regulating the addition amount of NPIM, the microstructure of the membranes can be optimized, and thus efficient pervaporation separation of alcohol-water can be achieved. The abundant hydrophilic amino groups on the surface of NPIM can be covalently anchored into the polyamide matrix, endowing the membrane with a dense and stable structure. Meanwhile, the hydrophilicity of the membrane is improved, and the selective transport of water molecules by the membrane is enhanced. The intrinsic microporous structure of NPIM endows the membrane with more molecular mass transfer channels and enhances the permeability of the membrane. The addition of NPIM synergistically increases the permeation flux and separation factor of polyamide membranes, demonstrating that the rational design of polymers with intrinsic microporosity helps to optimize the structure of polyamide membranes and improve the separation performance. The preparation method of the hybrid polyamide membrane containing polymers with intrinsic microporosity proposed in this invention is simple and controllable, and has broad application prospects in the field of pervaporation water-selective separation.

[0052] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many variations without departing from the purpose of the present invention, and all of these fall within the protection scope of the present invention.

[0053] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and its concept of the present invention, makes equivalent substitutions or changes, and all should be covered by the protection scope of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

Claims

1. A hybrid polyamide membrane containing self - microporous polymer, characterized in that: Disperse the intrinsically microporous polymer in the aqueous solution of amine monomer to obtain an aqueous dispersion. Soak the porous support base membrane in the aqueous dispersion first, and then soak it in the organic phase monomer solution to carry out an interfacial polymerization reaction. After heat treatment, a hybrid polyamide membrane containing the intrinsically microporous polymer is obtained.

2. The preparation method of the self-microporous polymer according to claim 1, characterized in that, Dissolve 2,3,5,6-tetrafluoroterephthalonitrile and 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane in N,N-dimethylacetamide, add potassium carbonate, stir and react under heating conditions, then dilute with toluene, pour into methanol to precipitate, and obtain PIM-1; wherein, the molar ratio of 2,3,5,6-tetrafluoroterephthalonitrile:5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane:potassium carbonate is 1:1:

3. Dissolve PIM-1 in tetrahydrofuran, add hydroxylamine, heat under reflux, wash the crude product with ethanol and water, and dry to obtain amino-functionalized NPIM-1; wherein, the mass ratio of PIM-1 to hydroxylamine is 1:

12. Or dissolve PIM-1 in methanol, add diethylenetriamine and N-acetylcysteine amide, heat and react at 60 °C for 48 h, wash the crude product with n-hexane and methanol, absorb with sodium hydroxide, extract with dichloromethane, and dry to obtain amino-functionalized NPIM-2; wherein, the mass ratio of PIM-1:diethylenetriamine:N-acetylcysteine is 1:2:3.

3.

3. The preparation method of the hybrid polyamide membrane containing self-microporous polymer according to claim 1, characterized in that, The amine monomer is one of ethylenediamine, m-phenylenediamine, and diethylenetriamine; the concentration of the amine monomer is 0.5 - 5 mg / mL.

4. The preparation method of the hybrid polyamide membrane containing self-microporous polymer according to claim 1, characterized in that, The content of the intrinsically microporous polymer in the aqueous dispersion is 0.05 - 0.2 mg / mL.

5. The preparation method of the hybrid polyamide membrane containing self-microporous polymer according to claim 1, characterized in that, The soaking time of the porous support base membrane in the aqueous dispersion is 2 - 20 min.

6. The preparation method of the hybrid polyamide membrane containing self-microporous polymer according to claim 1, characterized in that, The organic phase monomer is one of trimesoyl chloride, terephthaloyl chloride, and isophthaloyl chloride; the concentration of the organic phase monomer is 0.5 - 1.5 mg / mL; the solvent of the organic phase monomer solution is one of n-hexane and n-heptane.

7. The preparation method of the hybrid polyamide membrane containing self-microporous polymer according to claim 1, characterized in that, The interfacial polymerization reaction time is 1 - 5 min.

8. The preparation method of the hybrid polyamide membrane containing self-microporous polymer according to claim 1, characterized in that, The heat treatment temperature is 50 - 80 °C, and the heat treatment time is 5 - 20 min.

9. A hybrid polyamide membrane containing an intrinsically microporous polymer prepared by the method according to any one of claims 1 - 8.

10. Use of the hybrid polyamide membrane containing self-microporous polymer according to claim 9, characterized in that, The membrane is used for pervaporation ethanol-water separation, the operating temperature is 76 °C, and the water content of the feed liquid is 10 wt%.

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