C-peizif-8 hybrid matrix membrane based on reverse filling method, preparation method and application thereof

Abstract

The application discloses a c-PEI-ZIF-8 mixed matrix membrane based on a reverse filling method and a preparation method and application thereof. The c-PEI-ZIF-8 mixed matrix membrane is prepared by the following steps: constructing a ZIF-8 layer on a PAN base film through a reverse filling method, precisely filling gaps with a PEI solution, performing surface cross-linking on the PEI-ZIF-8 mixed matrix membrane by using trimesoyl chloride (TMC), and drying to obtain the c-PEI-ZIF-8 mixed matrix membrane. The c-PEI-ZIF-8 mixed matrix membrane prepared by the application is dense and defect-free, can simultaneously show high separation selectivity and high permeation flux during MeOH / DMC pervaporation separation, and has structural stability and can guarantee separation performance temperature. In addition, the process flow of the application is simple, the operation condition is mild, and the application has good repeatability and large-scale production potential.

Description

Technical Field

[0001] This invention relates to the field of separation membrane technology for methanol / dimethyl carbonate mixed systems, specifically to a c-PEI-ZIF-8 mixed matrix membrane based on the reverse packing method, its preparation method, and its application. Background Technology

[0002] Dimethyl carbonate (DMC) is an important chemical solvent and raw material, widely recognized for its low toxicity and environmental friendliness. DMC can be used as a raw material in the synthesis of polycarbonates, isocyanates, and other chemical products, and also as an environmentally friendly gasoline additive and lithium battery electrolyte. Currently, the main production process for DMC is transesterification, which generates a large amount of MeOH / DMC azeotrope. Industrially, the separation of MeOH / DMC azeotrope mainly employs extractive distillation and pressure swing distillation. Extractive distillation is relatively complex and produces lower product quality; while pressure swing distillation, although producing higher purity products, has high energy consumption during separation, and DMC is prone to decomposition at high temperatures, limiting the conditions for pressure swing distillation.

[0003] Compared to separation methods such as distillation, pervaporation is a membrane separation technology driven by chemical potential difference. It achieves the separation of liquid mixtures through the dissolution-diffusion selectivity of the membrane for components, and is particularly suitable for the dehydration and purification of azeotropes, near-boiling point substances, and heat-sensitive materials. However, currently, when pervaporation membranes are applied to the separation of MeOH / DMC azeotropes, it is difficult to simultaneously meet the requirements of high permeation flux and high separation selectivity, resulting in limited separation performance. Therefore, there is an urgent need to study a pervaporation membrane suitable for the separation of MeOH / DMC azeotropes that can simultaneously maintain high permeation flux and high separation selectivity. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a c-PEI-ZIF-8 mixed matrix membrane based on the reverse filling method, its preparation method, and its application. This mixed matrix membrane is dense and defect-free, and exhibits high permeation flux and high separation selectivity for the pervaporation separation of MeOH / DMC.

[0005] The technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, comprising the following steps: (1) Dissolve PEI in deionized water and stir for 10-15 hours to ensure it is fully dissolved, and prepare PEI casting solution; (2) Add ZIF-8 nanoparticles to deionized water and sonicate them to disperse them evenly, and prepare ZIF-8 dispersion; (3) Take the PAN film as the base film and fix it on the vacuum filtration device. Then pour the ZIF-8 dispersion prepared in step (2) onto the PAN film and perform vacuum filtration to obtain the PAN film loaded with ZIF-8 nanoparticle layer. (4) Pour the PEI casting solution prepared in step (1) onto the PAN membrane loaded with ZIF-8 nanoparticles obtained in step (3), and then filter it to obtain a PEI-ZIF-8 mixed matrix membrane. (5) Fix the PEI-ZIF-8 mixed matrix membrane obtained in step (4) with a plate and frame, and then pour TMC solution on its surface to crosslink TMC with PEI on the surface of the PEI-ZIF-8 mixed matrix membrane. After the crosslinking is completed, rinse the residual TMC with solvent and then place it in an oven to dry to obtain c-PEI-ZIF-8 mixed matrix membrane.

[0006] Furthermore, in step (1), the concentration of the PEI casting solution is 1~5 mg / mL, and the molecular weight of PEI is 10000~1000000.

[0007] Furthermore, the concentration of the ZIF-8 dispersion in step (2) is 0.01~1 mg / mL.

[0008] Furthermore, the filtration time in steps (3) and (4) is 5 to 30 minutes.

[0009] Furthermore, in the PEI-ZIF-8 mixed matrix membrane obtained in step (4), the loading of ZIF-8 nanoparticles is 0.0015 mg / cm², based on the effective separation membrane area. 2 ~0.5mg / cm 2 .

[0010] Furthermore, in the PEI-ZIF-8 mixed matrix membrane obtained in step (4), the loading of PEI is 1 to 10 times the loading of ZIF-8 nanoparticles, based on the effective separation membrane area.

[0011] Furthermore, in step (5), the concentration of the TMC solution is 1~5 mg / mL, and the crosslinking time is 1~30 min.

[0012] Furthermore, the c-PEI-ZIF-8 hybrid matrix membrane obtained in step (5) is composed of a PAN base film, a PEI-ZIF-8 hybrid layer, and a TMC-PEI crosslinking layer.

[0013] Secondly, the present invention provides a c-PEI-ZIF-8 mixed matrix membrane based on the reverse filling method, which is prepared using the above method.

[0014] Thirdly, the present invention provides an application of a c-PEI-ZIF-8 mixed matrix membrane based on reverse filling method in the pervaporation separation of MeOH / DMC organic mixtures.

[0015] The beneficial effects of this invention are as follows: (1) By using the reverse filling sequence of “loading ZIF-8 first and then adding PEI”, the present invention enables the PEI solution to fully wet and fill all the gaps between ZIF-8 particles, forming a dense and defect-free composite separation layer, which alleviates the inherent interfacial compatibility problem in the traditional blending method. Moreover, the dense composite separation layer can exhibit high separation selectivity and high permeation flux during the pervaporation separation of MeOH / DMC, that is, it maintains high permeability to MeOH and effectively blocks the passage of DMC. (2) The tightly interwoven structure formed between PEI and ZIF-8 in the PEI-ZIF-8 hybrid layer prepared in this invention can enhance the mechanical strength of the membrane and suppress the swelling phenomenon in the organic solvent environment, thereby ensuring stable separation performance. (3) In the preparation process, the present invention uses common vacuum filtration equipment for membrane preparation. The process is simple, the operating conditions are mild, and it has good repeatability and potential for large-scale production. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the c-PEI-ZIF-8 membrane prepared in Example 1 of the present invention.

[0018] Figure 2 This is a SEM image of the c-PEI-ZIF-8 membrane prepared in Example 1 of the present invention; Figure 3 SEM images of the PEI-ZIF-8 hybrid layer and surface crosslinking layer in the c-PEI-ZIF-8 membrane prepared in Example 1 of this invention; Figure 4 The infrared spectra of the films prepared in Example 1 and Comparative Example 1 of this invention are shown below. Figure 5 The XRD patterns of the films prepared in Example 1 and Comparative Example 1 of this invention are shown below. Figure 6 The results of the pervaporation separation of a mixed solution of MeOH and DMC in Example 6 of this invention are shown. Figure 7 This is the test result of pervaporation separation of a mixed solution of MeOH and DMC in Comparative Example 2 of this invention. Detailed Implementation

[0019] This invention provides a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] This invention provides a method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, comprising the following steps: (1) Dissolve PEI (polyethyleneimine) in deionized water and stir for 12 h to ensure it is fully dissolved, and prepare PEI casting solution; (2) Add ZIF-8 nanoparticles to deionized water and sonicate them to disperse them evenly, and prepare ZIF-8 dispersion; (3) Take a PAN (polyacrylonitrile) film as the base film and fix it on the vacuum filtration device. Then pour the ZIF-8 dispersion prepared in step (2) onto the PAN film and perform vacuum filtration to obtain a PAN film loaded with ZIF-8 nanoparticles. (4) Pour the PEI casting solution prepared in step (1) onto the PAN membrane loaded with ZIF-8 nanoparticles obtained in step (3), and then filter it to obtain a PEI-ZIF-8 mixed matrix membrane. (5) Fix the PEI-ZIF-8 mixed matrix membrane obtained in step (4) with a plate and frame, and then pour TMC (trimethylammonium chloride) solution on its surface. At room temperature, TMC crosslinks with PEI on the surface of the PEI-ZIF-8 mixed matrix membrane. After the crosslinking is completed, rinse the residual TMC with solvent and then place it in an oven to dry, and obtain c-PEI-ZIF-8 mixed matrix membrane.

[0021] In the above technical solution, the c-PEI-ZIF-8 hybrid matrix membrane obtained by the present invention is composed of a PAN base film, a PEI-ZIF-8 hybrid layer, and a TMC-PEI crosslinking layer. The PAN base film provides support, the TMC-PEI crosslinking layer acts as a surface protective layer, and the PEI-ZIF-8 hybrid layer is prepared by a reverse filling sequence of "first loading ZIF-8, then adding PEI". This layer is a defect-free composite separation layer that integrates the "ZIF-8 molecular sieving" and "PEI dissolution-diffusion" mechanisms. The PEI-ZIF-8 hybrid layer not only achieves efficient and selective transport of MeOH molecules through the size exclusion effect of ZIF-8 and the polar selection effect of PEI, but also exerts the synergistic effect of ZIF-8 and PEI at the nanoscale, effectively inhibiting polymer swelling and significantly enhancing interfacial stability. This overcomes the key problems of interfacial defects and swelling stability in traditional mixed matrix membranes, and thus achieves efficient and stable separation of MeOH / DMC azeotropes while maintaining high permeation flux and high separation selectivity.

[0022] In some specific embodiments, the concentration of the PEI casting solution in step (1) is 1~5 mg / mL, and the molecular weight of PEI is 10000~1000000; preferably, the concentration of the PEI casting solution is 2~4 mg / mL, and the molecular weight of PEI is 70000~800000.

[0023] In the above technical solution, PEI is made of ultra-high molecular weight, and its hydrogen bond strength between chain segments is high, which can improve the stability of the membrane.

[0024] In some specific embodiments, the concentration of the ZIF-8 dispersion in step (2) is 0.01~1 mg / mL, preferably 0.01~0.5 mg / mL.

[0025] In some specific implementations, the filtration time in steps (3) and (4) is 5 to 30 minutes.

[0026] In the above technical solution, the present invention uses a vacuum filtration membrane formation method, which is simple and easy to operate.

[0027] In some specific embodiments, the loading of ZIF-8 nanoparticles in the PEI-ZIF-8 mixed matrix membrane obtained in step (4) is 0.0015 mg / cm², based on the effective separation membrane area. 2 ~0.5mg / cm 2 .

[0028] In some specific implementations, in the PEI-ZIF-8 mixed matrix membrane obtained in step (4), the loading of PEI is 1 to 10 times the loading of ZIF-8 nanoparticles, based on the effective separation membrane area.

[0029] In some specific implementations, the concentration of the TMC solution in step (5) is 0.1~0.5wt%, and the crosslinking time is 1~30min; preferably 5~20min.

[0030] In some specific implementations, the c-PEI-ZIF-8 hybrid matrix membrane obtained in step (5) consists of a PAN base film, a PEI-ZIF-8 hybrid layer, and a TMC-PEI crosslinking layer.

[0031] The c-PEI-ZIF-8 mixed matrix membrane based on the reverse packing method described above was used for pervaporation separation of MeOH / DMC organic mixtures, exhibiting high permeation flux and high separation selectivity.

[0032] Example 1 This embodiment provides a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, and its preparation process is as follows: (1) Dissolve 0.1g of PEI with a molecular weight of 70,000 in 100mL of deionized water and stir for 12h to make it fully dissolved, and prepare a PEI casting solution with a concentration of 1mg / mL. (2) Take 0.01g of ZIF-8 nanoparticles and add them to 100mL of deionized water and sonicate for 30min to disperse them evenly, and prepare a ZIF-8 dispersion with a concentration of 0.1mg / mL. (3) Soak the PAN film as a base film in deionized water for 1 hour to remove impurities in the pores of the PAN base film. Then fix it on the vacuum filtration device, take 15 mL of the ZIF-8 dispersion prepared in step (2) and pour it into the vacuum filtration device. Filter for 5 minutes to obtain the PAN film loaded with ZIF-8 nanoparticle layer. (4) Take 10 mL of the PEI casting solution prepared in step (1) and pour it onto the PAN membrane loaded with ZIF-8 nanoparticles. Then filter for 10 min to form a PEI-ZIF-8 hybrid layer on the PAN substrate, thus obtaining the PEI-ZIF-8 mixed matrix membrane. (5) Dissolve 0.2g of TMC in 100mL of n-hexane and stir for 0.5h to fully dissolve the TMC and prepare a TMC crosslinking solution with a concentration of 2mg / mL. Fix the PEI-ZIF-8 hybrid matrix membrane obtained in step (4) with a plate and frame, pour in 20mL of TMC crosslinking solution, crosslink at room temperature for 5min, rinse the residual TMC with n-hexane after crosslinking, and then dry in a 60℃ oven for 5min to form a crosslinking layer on the surface of the PEI-ZIF-8 hybrid layer to obtain a c-PEI-ZIF-8 hybrid matrix membrane with an effective membrane area of ​​11cm×7cm.

[0033] Example 2 This embodiment provides a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, and its preparation process is as follows: (1) Dissolve 0.1g of PEI with a molecular weight of 750,000 in 100mL of deionized water and stir for 12h to make it fully dissolved, and prepare a PEI casting solution with a concentration of 1mg / mL. (2) Take 0.05g of ZIF-8 nanoparticles and add them to 100mL of deionized water and sonicate for 30min to disperse them evenly, and prepare a ZIF-8 dispersion with a concentration of 0.5mg / mL. (3) Soak the PAN film as a base film in deionized water for 1 hour to remove impurities in the pores of the PAN base film. Then fix it on the vacuum filtration device, take 30 mL of the ZIF-8 dispersion prepared in step (2) and pour it into the vacuum filtration device. Filter for 5 minutes to obtain the PAN film loaded with ZIF-8 nanoparticle layer. (4) Take 20 mL of the PEI casting solution prepared in step (1) and pour it onto the PAN membrane loaded with ZIF-8 nanoparticles. Then filter for 15 min to form a PEI-ZIF-8 hybrid layer on the PAN substrate, thus obtaining the PEI-ZIF-8 mixed matrix membrane. (5) Dissolve 0.2g of TMC in 100mL of n-hexane and stir for 0.5h to fully dissolve the TMC and prepare a TMC crosslinking solution with a concentration of 2mg / mL. Fix the PEI-ZIF-8 hybrid matrix membrane obtained in step (4) with a plate and frame, pour in 20mL of TMC crosslinking solution, crosslink at room temperature for 20min, rinse the residual TMC with n-hexane after crosslinking, and then dry in a 60℃ oven for 5min to form a crosslinking layer on the surface of the PEI-ZIF-8 hybrid layer to obtain a c-PEI-ZIF-8 hybrid matrix membrane with an effective membrane area of ​​11cm×7cm.

[0034] Example 3 This embodiment provides a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, and its preparation process is as follows: (1) Dissolve 0.3g of PEI with a molecular weight of 750,000 in 100mL of deionized water and stir for 12h to make it fully dissolved, and prepare a PEI casting solution with a concentration of 3mg / mL. (2) Take 0.015g of ZIF-8 nanoparticles and add them to 100mL of deionized water and sonicate for 30min to disperse them evenly, and prepare a ZIF-8 dispersion with a concentration of 0.15mg / mL. (3) Soak the PAN film as a base film in deionized water for 1 hour to remove impurities in the pores of the PAN base film. Then fix it on the vacuum filtration device, take 20 mL of the ZIF-8 dispersion prepared in step (2) and pour it into the vacuum filtration device. Filter for 5 minutes to obtain the PAN film loaded with ZIF-8 nanoparticle layer. (4) Take 10 mL of the PEI casting solution prepared in step (1) and pour it onto the PAN membrane loaded with ZIF-8 nanoparticles. Then filter for 10 min to form a PEI-ZIF-8 hybrid layer on the PAN substrate, thus obtaining a PEI-ZIF-8 mixed matrix membrane. (5) Take 0.4 g of TMC and dissolve it in 100 mL of n-hexane. Stir for 0.5 h to fully dissolve the TMC and prepare a TMC crosslinking solution with a concentration of 4 mg / mL. Fix the PEI-ZIF-8 mixed matrix membrane obtained in step (4) with a plate and frame, pour in 20 mL of TMC crosslinking solution, crosslink at room temperature for 10 min, rinse the residual TMC with n-hexane after crosslinking, and then dry it in a 60℃ oven for 5 min to form a crosslinking layer on the surface of the PEI-ZIF-8 hybrid layer, thus obtaining a c-PEI-ZIF-8 mixed matrix membrane with an effective membrane area of ​​11 cm × 7 cm.

[0035] Example 4 This embodiment provides a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, and its preparation process is as follows: (1) Dissolve 0.2g of PEI with a molecular weight of 750,000 in 100mL of deionized water and stir for 12h to make it fully dissolved, and prepare a PEI casting solution with a concentration of 2mg / mL. (2) Take 0.04g of ZIF-8 nanoparticles and add them to 100mL of deionized water and sonicate for 30min to disperse them evenly, and prepare a ZIF-8 dispersion with a concentration of 0.4mg / mL. (3) Soak the PAN film as a base film in deionized water for 1 hour to remove impurities in the pores of the PAN base film. Then fix it on the vacuum filtration device, take 20 mL of the ZIF-8 dispersion prepared in step (2) and pour it into the vacuum filtration device. Filter for 5 min to obtain the PAN film loaded with ZIF-8 nanoparticle layer. (4) Take 10 mL of the PEI casting solution prepared in step (1) and pour it onto the PAN membrane loaded with ZIF-8 nanoparticles. Then filter for 10 min to form a PEI-ZIF-8 hybrid layer on the PAN substrate, thus obtaining the PEI-ZIF-8 mixed matrix membrane. (5) Dissolve 0.3g of TMC in 100mL of n-hexane and stir for 0.5h to fully dissolve the TMC and prepare a TMC crosslinking solution with a concentration of 3mg / mL. Fix the PEI-ZIF-8 hybrid matrix membrane obtained in step (4) with a plate and frame, pour in 20mL of TMC crosslinking solution, crosslink at room temperature for 10min, rinse the residual TMC with n-hexane after crosslinking, and then dry in a 60℃ oven for 5min to form a crosslinking layer on the surface of the PEI-ZIF-8 hybrid layer to obtain a c-PEI-ZIF-8 hybrid matrix membrane with an effective membrane area of ​​11cm×7cm.

[0036] Example 5 This embodiment provides a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, and its preparation process is as follows: (1) Dissolve 0.4g of PEI with a molecular weight of 750,000 in 100mL of deionized water and stir for 12h to make it fully dissolved, and prepare a PEI casting solution with a concentration of 4mg / mL. (2) Take 0.03g of ZIF-8 nanoparticles and add them to 100mL of deionized water and sonicate for 30min to disperse them evenly, and prepare a ZIF-8 dispersion with a concentration of 0.3mg / mL. (3) Soak the PAN film as a base film in deionized water for 1 hour to remove impurities in the pores of the PAN base film. Then fix it on the vacuum filtration device, take 20 mL of the ZIF-8 dispersion prepared in step (2) and pour it into the vacuum filtration device. Filter for 5 min to obtain the PAN film loaded with ZIF-8 nanoparticle layer. (4) Take 15 mL of the PEI casting solution prepared in step (1) and pour it onto the PAN membrane loaded with ZIF-8 nanoparticles. Then filter for 10 min to form a PEI-ZIF-8 hybrid layer on the PAN substrate, thus obtaining the PEI-ZIF-8 mixed matrix membrane. (5) Dissolve 0.3g of TMC in 100mL of n-hexane and stir for 0.5h to fully dissolve the TMC and prepare a TMC crosslinking solution with a concentration of 3mg / mL. Fix the PEI-ZIF-8 hybrid matrix membrane obtained in step (4) with a plate and frame, pour in 20mL of TMC crosslinking solution, crosslink at room temperature for 15min, rinse the residual TMC with n-hexane after crosslinking, and then dry in a 60℃ oven for 5min to form a crosslinking layer on the surface of the PEI-ZIF-8 hybrid layer to obtain a c-PEI-ZIF-8 hybrid matrix membrane with an effective membrane area of ​​11cm×7cm.

[0037] Example 6 This embodiment prepares a c-PEI-ZIF-8 hybrid matrix membrane based on the reverse filling method, and the preparation process is as follows: (1) Dissolve 0.2g of PEI with a molecular weight of 750,000 in 100mL of deionized water and stir for 12h to make it fully dissolved, and prepare a PEI casting solution with a concentration of 2mg / mL. (2) Take 0, 0.005 g, 0.01 g, 0.015 g and 0.02 g of ZIF-8 nanoparticles respectively, add them to 100 mL of deionized water and sonicate for 30 min to disperse them evenly, and prepare ZIF-8 dispersions with concentrations of 0, 0.05, 0.1, 0.015 and 0.2 mg / mL respectively; (3) Take 5 PAN films as the base film and soak them in deionized water for 1 hour to remove impurities in the pores of the PAN base film. Then fix them on the vacuum filtration device. Take 10 mL of the ZIF-8 dispersion prepared in step (2) and pour it into the vacuum filtration device. Filter for 5 minutes to obtain PAN films loaded with ZIF-8 nanoparticle layers, and the loading amount is different. (4) Take 10 mL of the PEI casting solution prepared in step (1) and pour it onto the PAN membranes with different ZIF-8 nanoparticle loadings obtained in step (3). Then filter for 10 min to form a PEI-ZIF-8 hybrid layer on the PAN substrate, thus obtaining PEI-ZIF-8 mixed matrix membranes with different ZIF-8 nanoparticle loadings. (5) Dissolve 0.2g of TMC in 100mL of n-hexane and stir for 0.5h to fully dissolve the TMC and prepare a TMC crosslinking solution with a concentration of 2mg / mL. Fix the PEI-ZIF-8 hybrid matrix membrane obtained in step (4) with a plate and frame, pour in 20mL of TMC crosslinking solution, crosslink at room temperature for 15min, rinse the residual TMC with n-hexane after crosslinking, and then dry in a 60℃ oven for 5min to form a crosslinking layer on the surface of the PEI-ZIF-8 hybrid layer, and obtain c-PEI-ZIF-8 hybrid matrix membranes with different ZIF-8 nanoparticle loadings, and the effective membrane area is 11cm×7cm.

[0038] Comparative Example 1 The difference between this comparative example and Example 1 is that ZIF-8 was not added when preparing the mixed matrix membrane in this comparative example, that is, only the PEI layer was prepared on the PAN substrate; all other parameters are the same as in Example 1.

[0039] Comparative Example 2 The difference between this comparative example and Example 6 is that, in preparing the PEI-ZIF-8 hybrid layer, this comparative example first mixes the PEI solution with ZIF-8 nanoparticles to prepare a mixed casting solution, and then pours it over the PAN film for filtration; all other parameters are the same as in Example 6.

[0040] The c-PEI-ZIF-8 membranes prepared in Example 1 above were examined by scanning electron microscopy (SEM), and the resulting SEM images are shown below. Figure 2 and Figure 3 As shown, the films prepared in Example 1 and Comparative Example 1 were also subjected to infrared spectroscopy and XRD tests, respectively, and the detection results are shown below. Figure 3 and Figure 4 As shown. From Figure 2 and Figure 3 As can be seen, a dense, defect-free composite separation layer exists on the PAN substrate; this layer is the c-PEI-ZIF-8 mixed matrix membrane layer. From... Figure 4 and Figure 5 As can be seen from the above, compared with Comparative Example 1, the c-PEI-ZIF-8 film prepared in Example 1 was successfully doped with ZIF-8 nanoparticles.

[0041] Additionally, refer to Figure 1 The membranes prepared in Examples 1-5 and Comparative Example 1 were used to test the pervaporation separation effect of the MeOH and DMC mixed solution. The mass ratio of MeOH to DMC in the MeOH and DMC mixed solution was 1:9, and the test condition was 50℃. The test results are shown in Table 1 below.

[0042] Table 1 Analysis of Table 1 above: The membranes prepared in Examples 1-5 have high permeation flux and high separation factor for the mixed solution of MeOH and DMC. However, when the ZIF-8 loading is too high, although the permeation flux increases, the separation factor decreases. This is because an excessively high ZIF-8 loading will lead to interface defects, which weakens the separation performance.

[0043] In addition, the membranes prepared in Example 6 and Comparative Example 2 were used to test the pervaporation separation effect on the MeOH and DMC mixed solution. The mass ratio of MeOH to DMC in the MeOH and DMC mixed solution was 1:9, and the test condition was 50℃. The test results are as follows: Figure 6 and Figure 7 As shown. From Figure 6 and Figure 7As can be seen, when the ZIF-8 loading is low, the membrane exhibits good separation performance, along with relatively high permeation flux and separation factor. However, when the ZIF-8 loading is high, while the permeation flux increases, the separation factor decreases significantly, affecting the separation effect, especially the purity of the separated products. Furthermore, [the text abruptly ends here, likely due to an incomplete sentence or missing information]. Figure 6 and Figure 7 In comparison, the membrane prepared by the reverse filling method in Example 6 has better separation performance.

[0044] It should be noted that any parts not mentioned in this invention can be achieved by using or referencing existing technologies.

[0045] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method, characterized in that, Including the following steps: (1) Dissolve PEI in deionized water and stir until it is fully dissolved to prepare PEI casting solution; (2) Add ZIF-8 nanoparticles to deionized water and sonicate them to disperse them evenly, and prepare ZIF-8 dispersion; (3) Take the PAN film as the base film and fix it on the vacuum filtration device. Then pour the ZIF-8 dispersion prepared in step (2) onto the PAN film and perform vacuum filtration to obtain the PAN film loaded with ZIF-8 nanoparticle layer. (4) Pour the PEI casting solution prepared in step (1) onto the PAN membrane loaded with ZIF-8 nanoparticles obtained in step (3), and then filter it to obtain a PEI-ZIF-8 mixed matrix membrane. (5) Fix the PEI-ZIF-8 mixed matrix membrane obtained in step (4) with a plate and frame, and then pour TMC solution on its surface to crosslink TMC with PEI on the surface of the PEI-ZIF-8 mixed matrix membrane. After the crosslinking is completed, rinse the residual TMC with solvent and then place it in an oven to dry to obtain c-PEI-ZIF-8 mixed matrix membrane.

2. The method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method according to claim 1, characterized in that, In step (1), the concentration of the PEI casting solution is 1~5 mg / mL, and the molecular weight of PEI is 10000~1000000.

3. The method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method according to claim 1, characterized in that, The concentration of ZIF-8 dispersion in step (2) is 0.01~1 mg / mL.

4. The method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method according to claim 1, characterized in that, The filtration time in steps (3) and (4) is 5 to 30 minutes.

5. The method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method according to claim 1, characterized in that, In the PEI-ZIF-8 hybrid matrix membrane obtained in step (4), the loading of ZIF-8 nanoparticles is 0.0015 mg / cm², based on the effective separation membrane area. 2 ~0.5mg / cm 2 .

6. The method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method according to claim 5, characterized in that, In the PEI-ZIF-8 mixed matrix membrane obtained in step (4), the loading of PEI is 1 to 10 times the loading of ZIF-8 nanoparticles, based on the effective separation membrane area.

7. The method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method according to claim 1, characterized in that, In step (5), the concentration of the TMC solution is 1~5 mg / mL, and the crosslinking time is 1~30 min.

8. The method for preparing a c-PEI-ZIF-8 hybrid matrix membrane based on a reverse filling method according to claim 1, characterized in that, The c-PEI-ZIF-8 hybrid matrix membrane obtained in step (5) consists of a PAN base film, a PEI-ZIF-8 hybrid layer, and a TMC-PEI crosslinking layer.

9. A c-PEI-ZIF-8 hybrid matrix membrane based on reverse filling method, prepared by the method described in any one of claims 1-8.

10. The application of the c-PEI-ZIF-8 mixed matrix membrane based on the reverse packing method as described in claim 9 in the pervaporation separation of MeOH / DMC organic mixtures.

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