A zif-8@graphdiyne mixed matrix membrane and a preparation method thereof

Abstract

This invention relates to a ZIF-8@graphyne hybrid matrix membrane and its preparation method, belonging to the field of membrane separation technology. ZIF-8 and graphyne are in-situ composited using a solvothermal method to obtain a ZIF-8@graphyne material exhibiting both adsorption and diffusion selectivity. This material is then doped into an organic polymer matrix to prepare a hybrid matrix membrane. The resulting membrane has a three-layer structure consisting of a hybrid matrix layer, a pore-filled layer, and a porous substrate support layer, wherein the hybrid matrix layer and the pore-filled layer together form a selective separation layer. This structure fully utilizes the adsorption capacity of ZIF-8 for alcohol molecules and the regulating effect of the ordered pores of graphyne on molecular diffusion, effectively improving the separation performance of the membrane material in pervaporation separation of alcohol-water systems. The hybrid matrix membrane of this invention has the advantages of high flux and a large separation factor, making it suitable for the efficient recovery of bio-alcohols.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation and technology, specifically relating to a hybrid matrix membrane doped with metal-organic framework materials and graphyne materials, and its preparation method. Background Technology

[0002] In recent years, bioethanol recovered from biofermentation has received widespread attention as a clean and recyclable energy source that can alleviate fossil fuel shortages and address environmental degradation. However, the low ethanol concentration in biofermentation broth leads to enormous energy consumption for traditional recovery methods such as distillation. Pervaporation (PV), as a highly efficient and energy-saving membrane separation technology, is considered an ideal alternative for recovering bioethanol.

[0003] Polydimethylsiloxane (PDMS) has become the most widely studied preferred material for alcohol permeation membranes due to its excellent hydrophobicity and biocompatibility. However, the separation performance of pure polymer membranes is limited by the "trade-off" effect between permeability and selectivity. To overcome this bottleneck, researchers have developed hybrid matrix membranes (MMMs) by introducing nanomaterials such as metal-organic frameworks (MOFs), covalent organic scaffolds (COFs), zeolites, and carbon nanotubes (CNTs) into the polymer matrix to improve permeation selectivity.

[0004] Based on the "dissolution-diffusion" mechanism of pervaporation, the key to improving membrane separation performance lies in simultaneously enhancing both adsorption and diffusion selectivity. However, while MOF materials such as ZIF-8 possess high specific surface area, which is beneficial for enhancing adsorption selectivity, their pore structure often makes it difficult to achieve ideal diffusion selectivity. Therefore, combining them with a nanomaterial exhibiting high diffusion selectivity to improve diffusion selectivity and thus separation performance is of great significance for selective ethanol recovery.

[0005] Meanwhile, graphyne (GDY), as a novel two-dimensional carbon allotrope, possesses highly ordered intrinsic hexagonal channels and excellent alcohol-loving properties. Its unique two-dimensional planar structure provides extremely short diffusion paths for ethanol molecules, exhibiting excellent molecular sieving ability and high diffusion selectivity. Based on this, if MOFs with strong adsorption capacity can be composited with HsGDY exhibiting excellent diffusion selectivity, it is expected that the synergistic effect of the two can simultaneously improve the adsorption and diffusion selectivity of the mixed matrix membrane, thereby comprehensively enhancing its pervaporation performance.

[0006] Based on the above analysis, this invention prepares ZIF-8@graphyne nanomaterials with synergistic adsorption and diffusion effects by composite construction of ZIF-8 and graphyne materials. These nanomaterials are further doped into PDMS and loaded onto a porous substrate to form a ZIF-8@graphyne hybrid matrix membrane. This membrane structure fully combines the advantages of metal-organic framework materials in adsorption selectivity with the characteristics of graphyne materials in molecular sieving and diffusion selectivity, effectively improving the separation performance of the membrane material in the pervaporation separation process. This technical solution provides a new design concept for constructing high-performance hybrid matrix pervaporation membranes, enriches the application forms of porous materials in the field of pervaporation membranes, and has important engineering application significance for the efficient separation and recovery of organic solvents such as bioethanol. Summary of the Invention

[0007] The key problem this invention aims to solve is to provide a method for preparing a ZIF-8@graphyne mixed matrix membrane, thereby improving the diffusion selectivity of ZIF-8 and enhancing the adsorption of alcohols, thus further improving the performance of the preferential alcohol-permeable membrane in alcohol recovery. The specific technical solution is as follows:

[0008] A ZIF-8@graphyne mixed matrix membrane is characterized by comprising three layers, from top to bottom: a mixed matrix layer, a pore-filling layer, and a lower porous base membrane support layer. The mixed matrix layer is located on the upper surface of the porous base membrane. During preparation, the mixed matrix penetrates downwards from the upper surface of the porous base membrane into the porous base membrane to form a pore-filling layer. In other words, the mixed matrix layer penetrates into the upper part of the porous base membrane, and the thickness of the pore-filling layer is less than the thickness of the entire base membrane. Below the pore-filling layer is the remaining lower part of the porous base membrane, i.e., the lower porous base membrane support layer. The mixed matrix layer is a composite layer with ZIF-8@graphyne material as the dispersed phase and an organic polymer as the dispersed phase. The ZIF-8@graphyne material is dispersed in a cross-linked organic polymer generated by the cross-linking reaction of the organic polymer and a cross-linking agent. The mixed matrix layer and the pore-filling layer together constitute a selective separation layer.

[0009] Specifically, the particle size range of the ZIF-8@graphyne is 20 nm to 100 nm to ensure uniform dispersion in the film and the formation of continuous transport channels; the thickness of the pore filling layer is 1-20 μm, the thickness of the mixed matrix layer is 1-20 μm, and the thickness of the selective separation layer composed of the pore filling layer and the mixed matrix layer is 2-40 μm.

[0010] The ZIF-8@graphyne material is prepared by in-situ composite of ZIF-8 material and graphyne. The graphyne is one or more of graphitic monoyne and graphitic diyne; the ZIF-8 material has a crystal structure composed of zinc metal nodes and organic ligands, and has a regular pore system and excellent thermochemical stability; surface-modified ZIF-8 can also be used to further improve its interfacial compatibility with polymers.

[0011] Preferably, the porous base membrane is an organic polymer membrane, an inorganic membrane, or an organic / inorganic hybrid membrane, with an average pore size of 10-100 nm; the porous base membrane is in the form of a flat plate, a tubular membrane, or a hollow fiber membrane.

[0012] The preparation method of ZIF-8@graphyne hybrid matrix membrane includes the following steps:

[0013] Step a: The metal salt corresponding to ZIF-8, the organic ligand corresponding to ZIF-8, the acetylene synthesis catalyst and the graphdiyne monomer are added to the solvent and reacted under solvothermal conditions. They are mixed in a certain proportion, sonicated to completely dissolve, and then placed in a high-temperature oven to react for a period of time. After centrifugation, the precipitate is taken and washed with solvent to obtain ZIF-8@graphdiyne material.

[0014] Step b: Disperse the ZIF-8@graphyne material obtained in step a in a crosslinking agent and sonicate it for 2-24 h to make it uniformly dispersed. Then add the organic polymer and mix it evenly to prepare a casting solution.

[0015] Step c: The casting solution obtained in step b is added to the membrane surface to form a film, and then heated at 80°C for 8 hours to fully crosslink, thus obtaining the ZIF-8@graphyne mixed matrix membrane.

[0016] Specifically, the metal salt mentioned in step a is one or more of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc acetate hexahydrate (Zn(OAc)2·6H2O), and zinc oxide (ZnO), and the organic ligand is 2-methylimidazole with a concentration of 30 mg / mL.

[0017] Specifically, the graphynyne monomer mentioned in step a is one or more of 1,3,5-triethynylbenzene (TEB), tris(4-ethynylphenyl)amine (TEPA), 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB), or hexaethynylbenzene (HEB); the yne synthesis catalyst is one or more of copper hydroxide (Cu(OH)2) or copper acetate (Cu(CH3COO)2); the concentration of the yne synthesis catalyst is 0.9 mg / mL; the reaction temperature in the high-temperature oven is 60-120 ℃, and the reaction time is 2-8 h.

[0018] Specifically, the concentration of the graphyne monomer in step a is 7.2 mg / mL, and the concentration of the metal salt corresponding to ZIF-8 is 12 mg / mL; the solvent is selected from one or more of methanol, ethanol, or n-propanol.

[0019] Specifically, the organic polymers mentioned in step b are all one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxyacetylenic acid (PTMSP); the crosslinking agent is one or more of polymethylhydrosiloxane (PMHS), tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); and the mass ratio of the organic polymer to the crosslinking agent is 6:1.

[0020] Specifically, in step b, the mass ratio of ZIF-8@graphyne material to organic polymer is 1:2000-1:200.

[0021] Specifically, the film-forming method described in step c is a blade coating method with a coating speed of 20 cm / s.

[0022] The application of the ZIF-8@graphyne mixed matrix membrane of this invention separates bio-alcohols from aqueous solutions or fermentation broths through pervaporation.

[0023] This invention prepares a hybrid matrix membrane by constructing a nanomaterial by combining ZIF-8 and graphyne and incorporating it into an organic polymer matrix. ZIF-8 provides a tunable microporous structure and abundant mass transfer channels, while the introduction of graphyne effectively enhances the diffusion selectivity of the material. Compared to traditional pure polymer membranes, with the same membrane thickness, the separation factor of the ZIF-8@graphyne nanomaterial is increased by 30%-50% due to the richer alcohol-loving sites and more ordered separation channels provided by the ZIF-8@graphyne nanomaterial. Compared to traditional hybrid matrix membranes filled with single ZIF-8 or pure graphyne, the ZIF-8@graphyne nanomaterial of this invention significantly improves the permeate flux and separation selectivity of the membrane with the same filler content. This structure provides a new design concept for constructing high-performance alcohol-preferential permeate hybrid matrix membranes and expands the application of graphyne in the field of pervaporation separation. Attached Figure Description

[0024] Figure 1 Scanning electron microscope image of ZIF-8@graphyne prepared in Example 1 of this invention.

[0025] Figure 2Scanning electron microscope (SEM) image of the ZIF-8@graphyne mixed matrix film prepared in Example 1 of this invention.

[0026] Figure 3 (a) Cross-sectional scanning electron microscope image and (b) cross-sectional elemental distribution map of the graphdiyne mixed matrix film prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the following examples, but the present invention is not limited to the following embodiments. Surface and cross-sectional images were observed and measured using a TESCAN MIAI3 scanning electron microscope (SEM).

[0028] This invention provides a ZIF-8@graphyne mixed matrix membrane and its preparation method, characterized in that it includes a polydimethylsiloxane (PDMS) organic polymer matrix and ZIF-8@graphyne nanomaterials uniformly distributed in the matrix.

[0029] In the ZIF-8@graphyne mixed matrix membrane, ZIF-8@graphyne nanomaterials are used as functional fillers, and their regular pores and alcohol-loving properties are used to improve the selectivity and permeability of the membrane.

[0030] Its preparation method includes the following steps:

[0031] Step 101: The metal salt corresponding to ZIF-8, the organic ligand corresponding to ZIF-8, the alkyne synthesis catalyst and the graphdiyne monomer are added to the solvent and mixed in a certain proportion. The mixture is then sonicated to completely dissolve the mixture. The mixture is placed in a high-temperature oven and reacted for a period of time under solvothermal conditions. After the reaction is completed, the mixture is centrifuged, washed and dried to obtain the ZIF-8@graphdiyne material used for the preparation of mixed matrix membranes.

[0032] Step 102: Weigh an appropriate amount of ZIF-8@graphyne nanomaterials and add them to the crosslinking agent. Use ultrasonic treatment to disperse the filler evenly. Then add an organic polymer and stir continuously under vacuum to remove bubbles, thus obtaining a uniform and stable mixed matrix casting solution.

[0033] Step 103: The casting solution prepared in step 102 is added to the membrane surface to form a film, and then heated at 80 °C for 8 minutes to fully crosslink, thus obtaining the ZIF-8@graphyne mixed matrix membrane.

[0034] Specifically, the synthesis described in step 101 refers to: dissolving 1,3,5-triethynylbenzene (TEB), copper acetate, zinc nitrate, and 2-methylimidazole in a methanol solution and reacting at 110 °C for 3 h. This allows ZIF-8 and graphyne material to co-grow in the solvent, forming a graphyne-coated ZIF-8 hybrid structure with high specific surface area and specific molecular sieve channels.

[0035] Specifically, the graphyne monomer mentioned in step 101 is 1,3,5-triethynylbenzene; the concentration of the graphyne monomer is 7.2 mg / mL, and the concentration of copper acetate is 0.9 mg / mL, so that the graphyne monomer has a suitable reaction rate in the solvent.

[0036] Specifically, the metal salt mentioned in step 101 is zinc nitrate hexahydrate (Zn(NO3)2·6H2O), with a concentration of 12 mg / mL, and the organic ligand is 2-methylimidazole, with a concentration of 30 mg / mL.

[0037] Specifically, the organic polymer is one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxyacetylenic acid (PTMSP); the crosslinking agent is one or more of polymethylhydrosiloxane (PMHS), tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); the mass ratio of the crosslinking agent to the organic polymer is 1:6.

[0038] Specifically, in step 102, the mass fraction of ZIF-8@graphyne in the film is 0.05 wt.%-0.25 wt.%.

[0039] Specifically, the pore-filling layer has a thickness of 1.5-20 μm, the mixed matrix layer has a thickness of 1.5-20 μm, and the selective separation layer composed of the pore-filling layer and the mixed matrix layer has a thickness of 3-40 μm.

[0040] Preferably, the porous base membrane is an organic polymer membrane, an inorganic membrane, or an organic / inorganic hybrid membrane. The organic polymer membrane can be a polysulfone membrane (PSf), a polyethylene membrane (PE), a polyethersulfone membrane (PES), a polytetrafluoroethylene membrane (PTFE), a polyvinylidene fluoride membrane (PVDF), etc.; the inorganic membrane can be an alumina membrane (Al2O3), a zirconia membrane (ZrO2), a zinc oxide membrane (ZnO), etc.; the organic / inorganic hybrid membrane can be a polysulfone / SiO2 membrane, a polysulfone / MOF membrane, a polysulfone / molecular sieve membrane, a polyvinylidene fluoride / SiO2 membrane, etc.; the average pore size of the porous base membrane is 10-100 nm; the shape of the porous base membrane can be a flat plate, a tubular type, or a hollow fiber type.

[0041] Preferably, the organic solvent in step 101 can be one or more of methanol, ethanol or n-propanol.

[0042] The present invention will be further described below through specific embodiments.

[0043] In the following specific embodiments, operations without specified conditions are performed under standard conditions or conditions recommended by the manufacturer. Raw materials without specified manufacturers and specifications are all commercially available products.

[0044] Example 1

[0045] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS). The selected filler is ZIF-8@graphyne nanomaterials.

[0046] Step a: 0.36 g of 1,3,5-triethynylbenzene (TEB), 0.045 g of copper acetate, 0.6 g of zinc nitrate, and 1.5 g of 2-methylimidazole were dissolved in 50 mL of methanol. After stirring and sonication, the mixture was reacted at 110 ℃ for 3 h. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, centrifuged, washed, and dried to obtain ZIF-8@graphyne nanomaterials.

[0047] Step b: Weigh an appropriate amount of ZIF-8@graphyne nanomaterial and add it to polymethylhydrosiloxane (PMHS). Sonicate the mixture to ensure uniform dispersion of the filler. Then add polydimethylsiloxane (PDMS) to achieve a ZIF-8@graphyne mass fraction of 0.2 wt.% (where the mass ratio of PDMS to PMHS is 6:1). Stir continuously under vacuum for 1 h to remove bubbles, thus preparing casting solution 1.

[0048] Step c: Add the casting solution 1 obtained in step b to the membrane surface to form a film. Then, place the membrane in an environment of 80 ℃ for 8 min to obtain a ZIF-8@graphyne mixed matrix membrane.

[0049] Figure 1 This is a scanning electron microscope (SEM) image of the ZIF-8@graphyne material prepared in Example 1 of this invention; the particle morphology is regular. SEM surface ( Figure 2 The prepared ZIF-8@graphyne mixed matrix film shows a uniform and defect-free surface. (Cross-section) Figure 3 The prepared ZIF-8@graphyne hybrid matrix film is shown, with a thickness of approximately 1.5 μm. Cross-sectional EDXS ( Figure 3 The thickness of the mixed matrix layer and the pore-filling layer is approximately 3 μm.

[0050] The prepared ZIF-8@graphyne mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the feed liquid was an aqueous solution of ethanol of different concentrations and the feed temperature was 60 ℃; (2) the downstream pressure of the membrane was 200 Pa.

[0051] When the feed solution was a 1 wt.% ethanol aqueous solution, the pervaporation performance of the ZIF-8@graphyne hybrid matrix membrane was measured to be: a permeation flux of 1560 gm. -2 h -1 The separation factor was 15.3, and the ethanol content in the permeate was approximately 13 wt.%.

[0052] When the feed solution was a 3 wt.% ethanol aqueous solution, the pervaporation performance of the ZIF-8@graphyne mixed matrix membrane was measured to be: a permeation flux of 1750 gm. -2 h -1 The separation factor was 13.9, and the ethanol content in the permeate was approximately 30 wt.%.

[0053] When the feed solution was a 5 wt.% ethanol aqueous solution, the pervaporation performance of the ZIF-8@graphyne mixed matrix membrane was measured to be: a permeation flux of 1970 gm. -2 h -1 The separation factor was 13.2, and the ethanol content in the permeate was approximately 41 wt.%. Under these conditions, the membrane was subjected to a 120-h continuous operation stability test. During the test, the changes in the membrane separation factor and flux were less than 5%, demonstrating that the membrane has strong continuous operation stability.

[0054] When the feed solution was a 7 wt.% ethanol aqueous solution, the pervaporation performance of the ZIF-8@graphyne hybrid matrix membrane was measured to be: a permeation flux of 2140 gm. -2 h -1 The separation factor was 11.9, and the ethanol content in the permeate was approximately 47 wt.%.

[0055] When the feed solution was a 9 wt.% ethanol aqueous solution, the pervaporation performance of the ZIF-8@graphyne hybrid matrix membrane was measured to be: a permeation flux of 2280 gm. -2 h -1 The separation factor was 10.9, and the ethanol content in the permeate was approximately 52 wt.%.

[0056] Comparative Experiment 1

[0057] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS).

[0058] Step a: Mix polymethylhydrosiloxane (PMHS) and polydimethylsiloxane (PDMS) in a mass ratio of 6:1. Stir continuously under vacuum for 1 h to remove bubbles, thus preparing a pure PDMS casting solution.

[0059] Step b: Add the casting solution obtained in step a to the membrane surface to form a film, and then place the membrane in an environment of 80 ℃ for 8 min to obtain a PDMS membrane.

[0060] Performance test results: The prepared PDMS membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) The raw material liquid composition was 5 wt.% ethanol aqueous solution, and the feed temperature was 60 ℃; (2) The downstream pressure of the membrane was 200 Pa.

[0061] The pervaporation performance of the PDMS membrane was measured to be: permeation flux of 1100 gm³. -2 h -1 The separation factor was 7.7, and the ethanol content in the permeate was approximately 29 wt.%.

[0062] Comparative Experiment 2

[0063] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS). The selected filler is graphyne (GDY) nanomaterial.

[0064] Step a: Dissolve 0.36 g of 1,3,5-triethynylbenzene (TEB) and 0.045 g of copper acetate in 50 mL of methanol, stir and sonicate, and then react at 110 ℃ for 3 h. After the reaction is complete, allow it to cool naturally to room temperature, centrifuge, wash and dry to obtain graphyne nanomaterials.

[0065] Step b: Weigh an appropriate amount of graphyne nanomaterial and add it to polymethylhydrosiloxane (PMHS). Sonicate the mixture to ensure uniform dispersion of the filler. Then add polydimethylsiloxane (PDMS) and dibutyltin dilaurate (DBTDL) to achieve a graphyne mass fraction of 0.2 wt.% (where the mass ratio of PDMS to PMHS is 6:1). Stir continuously under vacuum for 1 h to remove bubbles, thus preparing solvent-free casting solution 2.

[0066] Step c: Add the casting solution 2 obtained in step b to the membrane surface to form a film, and then place the membrane in an environment of 80 ℃ for 8 min to obtain a graphdiyne mixed matrix membrane.

[0067] Performance test results: The prepared graphdiyne mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) The raw material liquid composition was 5 wt.% ethanol aqueous solution, and the feed temperature was 60 ℃; (2) The downstream pressure of the membrane was 200 Pa.

[0068] The pervaporation performance of the graphdiyne hybrid matrix membrane was measured to be: a permeation flux of 2420 gm³. -2 h -1 The separation factor was 10.8, and the ethanol content in the permeate was approximately 36 wt.%.

[0069] Comparative Experiment 3

[0070] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS). The selected filler is ZIF-8 nanomaterial.

[0071] Step a: Dissolve 0.6 g of zinc nitrate and 1.5 g of 2-methylimidazole in 50 mL of methanol, stir and sonicate, then react at 50 ℃ for 5 h. After the reaction is complete, allow to cool naturally to room temperature, centrifuge, wash and dry to obtain ZIF-8 nanomaterials.

[0072] Step b: Weigh an appropriate amount of ZIF-8 nanomaterial and add it to polymethylhydrosiloxane (PMHS). Sonicate the mixture to ensure uniform dispersion of the filler. Then add polydimethylsiloxane (PDMS) and dibutyltin dilaurate (DBTDL) to achieve a ZIF-8 mass fraction of 0.2 wt.% (where the mass ratio of PDMS to PMHS is 6:1). Stir continuously under vacuum for 1 h to remove bubbles, thus preparing casting solution 3.

[0073] Step c: Add the casting solution 3 obtained in step b to the membrane surface to form a membrane, and then place the membrane in an environment of 80 ℃ for 8 min to obtain the ZIF-8 mixed matrix membrane.

[0074] The prepared ZIF-8 mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid composition was 5 wt.% ethanol aqueous solution and the feed temperature was 60 ℃; (2) the downstream pressure of the membrane was 200 Pa.

[0075] The pervaporation performance of the ZIF-8 hybrid matrix membrane was measured to be: a permeation flux of 1750 gm³. -2 h -1 The separation factor was 9.09, and the ethanol content in the permeate was approximately 32 wt.%.

[0076] Comparative Experiment 4

[0077] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS). The selected filler is Cu / Zn ZIF-8 nanomaterial.

[0078] Step a: Dissolve 0.045 g of copper acetate, 0.6 g of zinc nitrate, and 1.5 g of 2-methylimidazole in 50 mL of methanol, stir, and sonicate. Then react at 110 °C for 3 h. After the reaction is complete, allow to cool naturally to room temperature, centrifuge, wash, and dry to obtain Cu / Zn ZIF-8 nanomaterials.

[0079] Step b: Weigh an appropriate amount of Cu / Zn ZIF-8 nanomaterial and add it to polymethylhydrosiloxane (PMHS). Sonicate the mixture to ensure uniform dispersion of the filler. Then add polydimethylsiloxane (PDMS) and dibutyltin dilaurate (DBTDL) to achieve a Cu / Zn ZIF-8 mass fraction of 0.2 wt.% (where the mass ratio of PDMS to PMHS is 6:1). Stir continuously under vacuum for 1 h to remove bubbles, thus preparing casting solution 4.

[0080] Step c: Add the casting solution 4 obtained in step b to the membrane surface to form a film, and then place the film in an environment of 80 ℃ for 8 min to obtain a Cu / Zn ZIF-8 mixed matrix membrane.

[0081] The prepared Cu / Zn ZIF-8 mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid composition was 5 wt.% ethanol aqueous solution and the feed temperature was 60 ℃; (2) the downstream pressure of the membrane was 200 Pa.

[0082] The pervaporation performance of the Cu / Zn ZIF-8 mixed matrix membrane was measured to be: a permeation flux of 1620 gm. -1 h -1The separation factor was 10.08, and the ethanol content in the permeate was approximately 35 wt.%.

[0083] Comparative Experiment 5

[0084] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS). The selected filler is ZIF-8 / graphyne nanomaterials.

[0085] Step a: Dissolve 0.36 g of 1,3,5-triethynylbenzene (TEB) and 0.045 g of copper acetate in 50 mL of methanol, stir and sonicate, and then react at 110 ℃ for 3 h. After the reaction is complete, allow it to cool naturally to room temperature, centrifuge, wash and dry to obtain graphyne nanomaterials.

[0086] Step b: Dissolve 0.045 g of copper acetate, 0.6 g of zinc nitrate, and 1.5 g of 2-methylimidazole in 50 mL of methanol, stir, and sonicate. Then react at 110 °C for 3 h. After the reaction is complete, allow to cool naturally to room temperature, centrifuge, wash, and dry to obtain ZIF-8 nanomaterials.

[0087] Step c: Weigh appropriate amounts of ZIF-8 and graphylene nanomaterials and add them to polymethylhydrosiloxane (PMHS). Sonicate the mixture to ensure uniform dispersion of the filler. Then add polydimethylsiloxane (PDMS) to achieve a ZIF-8 / graphylene mass fraction of 0.2 wt.% (where the mass ratio of PDMS to PMHS is 6:1). Stir continuously under vacuum for 1 h to remove bubbles, thus preparing casting solution 5.

[0088] Step d: Add the casting solution 5 obtained in step c to the membrane surface to form a film, and then place the membrane in an environment of 80 ℃ for 8 min to obtain a ZIF-8 / graphyne mixed matrix membrane.

[0089] The prepared ZIF-8 / graphyne mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid composition was 5 wt.% ethanol aqueous solution and the feed temperature was 60 ℃; (2) the downstream pressure of the membrane was 200 Pa.

[0090] The pervaporation performance of the ZIF-8 / graphyne hybrid matrix membrane was measured to be: a permeation flux of 1723 gm. -2 h -1 The separation factor was 11.2, and the ethanol content in the permeate was approximately 35 wt.%.

[0091] Example 2

[0092] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS). The selected filler is ZIF-8@graphyne nanomaterials.

[0093] Step a: 0.36 g of 1,3,5-triethynylbenzene (TEB), 0.045 g of copper acetate, 0.6 g of zinc nitrate, and 1.5 g of 2-methylimidazole were dissolved in 50 mL of methanol. After stirring and sonication, the mixture was reacted at 110 ℃ for 3 h. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, centrifuged, washed, and dried to obtain ZIF-8@graphyne nanomaterials.

[0094] Step b: Weigh an appropriate amount of ZIF-8@graphyne nanomaterial and add it to polymethylhydrosiloxane (PMHS). Sonicate the mixture to ensure uniform dispersion of the filler. Then add polydimethylsiloxane (PDMS) to achieve a ZIF-8@graphyne mass fraction of 0.25 wt.% (where the mass ratio of PDMS to PMHS is 6:1). Stir continuously under vacuum for 1 h to remove bubbles, thus preparing casting solution 6.

[0095] Step c: Add the casting solution 6 obtained in step b to the membrane surface to form a film, and then place the membrane in an environment of 80 ℃ for 8 min to obtain the ZIF-8@graphyne mixed matrix membrane.

[0096] The prepared ZIF-8@graphyne mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid composition was 5 wt.% ethanol aqueous solution and the feed temperature was 60 ℃; (2) the downstream pressure of the membrane was 200 Pa.

[0097] The pervaporation performance of the ZIF-8@graphyne hybrid matrix membrane was measured to be: a permeation flux of 2120 gm. -2 h -1 The separation factor was 10.84, and the ethanol content in the permeate was approximately 36 wt.%.

[0098] Example 3

[0099] The selected organic polymer is polydimethylsiloxane (PDMS), and the selected crosslinking agent is polymethylhydrosiloxane (PMHS). The selected filler is ZIF-8@graphyne nanomaterials.

[0100] Step a: 0.36 g of 1,3,5-triethynylbenzene (TEB), 0.045 g of copper acetate, 0.6 g of zinc nitrate, and 1.5 g of 2-methylimidazole were dissolved in 50 mL of methanol. After stirring and sonication, the mixture was reacted at 110 ℃ for 3 h. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, centrifuged, washed, and dried to obtain ZIF-8@graphyne nanomaterials.

[0101] Step b: Weigh an appropriate amount of ZIF-8@graphyne nanomaterial and add it to polymethylhydrosiloxane (PMHS). Sonicate the mixture to ensure uniform dispersion of the filler. Then add polydimethylsiloxane (PDMS) to achieve a ZIF-8@graphyne mass fraction of 0.05 wt.% (where the mass ratio of PDMS to PMHS is 6:1). Stir continuously under vacuum for 1 h to remove bubbles, thus preparing casting solution 7.

[0102] Step c: Add the casting solution 7 obtained in step b to the membrane surface to form a film, and then place the membrane in an environment of 80 ℃ for 8 min to obtain the ZIF-8@graphyne mixed matrix membrane.

[0103] The prepared ZIF-8@graphyne mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid composition was 5 wt.% ethanol aqueous solution and the feed temperature was 60 ℃; (2) the downstream pressure of the membrane was 200 Pa.

[0104] The pervaporation performance of the ZIF-8@graphyne mixed matrix membrane was measured as follows: permeation flux of 1750 gm⁻² h⁻¹, separation factor of 8.8, and ethanol content in the permeate of approximately 32 wt.%.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A ZIF-8@graphyne hybrid matrix membrane, characterized in that, The hybrid matrix membrane has a three-layer structure, consisting of a hybrid matrix layer, a pore-filling layer, and a porous base membrane support layer from top to bottom. The hybrid matrix layer is formed by cross-linking ZIF-8@graphyne material and an organic polymer matrix. During the preparation process, the hybrid matrix layer partially penetrates into the porous base membrane to form a pore-filling layer. The hybrid matrix layer and the pore-filling layer together constitute a selective separation layer.

2. The ZIF-8@graphyne hybrid matrix membrane according to claim 1, characterized in that, The ZIF-8@graphyne material is formed by in-situ composite of ZIF-8 material and graphyne.

3. The ZIF-8@graphyne hybrid matrix membrane according to claim 1, characterized in that, The particle size of the ZIF-8@graphyne material is 20-100 nm.

4. The ZIF-8@graphyne hybrid matrix membrane according to claim 1, characterized in that, The thickness of the mixed matrix layer is 1.5-20 μm, the thickness of the pore-filling layer is 1.5-20 μm, and the total thickness of the selective separation layer is 3-40 μm.

5. The ZIF-8@graphyne hybrid matrix membrane according to claim 1, characterized in that, The porous base membrane is an organic polymer membrane, an inorganic membrane, or an organic / inorganic hybrid membrane, with an average pore size of 10~100 nm; the porous base membrane is in the shape of a flat plate.

6. The ZIF-8@graphyne hybrid matrix membrane according to claim 1, characterized in that, The organic polymer is one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxypyridine (PTMSP).

7. A method for preparing a ZIF-8@graphyne mixed matrix membrane as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Step a: The metal salt corresponding to ZIF-8, the organic ligand corresponding to ZIF-8, the acetylene synthesis catalyst and the graphdiyne monomer are added to the solvent and reacted under solvothermal conditions. They are mixed in a certain proportion, sonicated to completely dissolve, and then placed in a high-temperature oven to react for a period of time. After centrifugation, the precipitate is taken and washed with solvent to obtain ZIF-8@graphdiyne material. Step b: Disperse the ZIF-8@graphyne material obtained in step a in a crosslinking agent and sonicate it for 2-24 h to make it uniformly dispersed. Then, add the organic polymer evenly to prepare the casting solution. Step c: Add the casting solution obtained in step b to the membrane surface to form a film, and then place the membrane in an environment of 80 ℃ for 8 min to obtain the ZIF-8@graphyne mixed matrix membrane.

8. The preparation method according to claim 7, characterized in that, The metal salt mentioned in step a is one or more of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc acetate hexahydrate (Zn(OAc)2·6H2O), and zinc oxide (ZnO), and the organic ligand is 2-methylimidazole with a concentration of 30 mg / mL. Specifically, the graphynyne monomer mentioned in step a is one or more of 1,3,5-triethynylbenzene (TEB), tris(4-ethynylphenyl)amine (TEPA), 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB), or hexaethynylbenzene (HEB); the yne synthesis catalyst is one or more of copper hydroxide (Cu(OH)2) or copper acetate (Cu(CH3COO)2); the concentration of the yne synthesis catalyst is 0.9 mg / mL; the reaction temperature in the high-temperature oven is 60-120 ℃, and the reaction time is 2-8 h; Specifically, the concentration of the graphyne monomer in step a is 7.2 mg / mL, and the concentration of the metal salt corresponding to ZIF-8 is 12 mg / mL; the solvent is selected from one or more of methanol, ethanol, or n-propanol. Specifically, the organic polymers mentioned in step b are all one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxyacetylenic acid (PTMSP); the crosslinking agent is one or more of polymethylhydrosiloxane (PMHS), tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); the mass ratio of the organic polymer to the crosslinking agent is 6:1; Specifically, the method for loading the casting liquid in step c is a blade coating method with a coating speed of 20 cm / s.

9. The preparation method according to claim 7, characterized in that, The mass ratio of ZIF-8@graphyne material to organic polymer in step b is 1:2000-1:

200.

10. The application of the ZIF-8@graphyne mixed matrix membrane as described in any one of claims 1 to 6 in the pervaporation separation of alcohol-water mixtures.

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