Graphyne-based preferential alcohol permeation pervaporation membrane and preparation method thereof

Abstract

The application discloses a kind of graphdiyne-based preferential alcohol pervaporation membrane and preparation method thereof, belong to membrane separation and technical field.Graphdiyne is mixed with organic polymer and ethanol to be configured into casting solution 1, the graphdiyne in casting solution 1 is loaded on the surface of porous substrate membrane, then the casting solution 2 of mixed organic polymer, crosslinking agent, catalyst and organic solvent is added to the surface of porous substrate membrane loaded with graphdiyne, due to the loose structure of graphdiyne, a part of casting solution 2 will penetrate through graphdiyne and sink to the lower layer of porous substrate membrane to form a new membrane structure, and after volatilizing organic solvent, it is cured into a film at 80 DEG C.The preferential alcohol membrane of the application has a three-layer membrane structure: a mixed matrix layer with graphdiyne as dispersed phase and organic polymer as dispersant, an organic polymer layer and a porous support layer, which provides a reference for the development of new membrane structure.The membrane prepared by the application has high pervaporation alcohol permeation performance, can efficiently and stably recover alcohol, and opens up a new field for the application of graphdiyne material.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation and technology, specifically relating to a graphitic acetylation-based preferential alcohol pervaporation membrane and its preparation method. Background Technology

[0002] The world today faces numerous problems and challenges, including the depletion of fossil fuels and environmental and climate degradation. Bioethanol (bioethanol, biobutanol) possesses advantages such as cleanliness, high efficiency, renewability, and biodegradability, making it an effective alternative to fossil fuels. However, due to product inhibition, bioethanol faces the problem of low fermentation product concentration in actual production processes, necessitating further separation of bioethanol from the fermentation broth, a process that also generates high energy consumption. Membrane separation technology based on pervaporation (PV) offers advantages such as low energy consumption, minimal harm to microorganisms, high selectivity, and environmental friendliness, and is gradually gaining popularity. Therefore, coupling the fermentation process with a pervaporation-preferred alcohol membrane can separate bioethanol from the fermentation broth in situ in real time, thereby improving biofermentation efficiency and bioethanol recovery yield. Since the organic composition of bioethanol is complex, we used aqueous solutions of ethanol and butanol to simulate bioethanol for membrane pervaporation performance evaluation.

[0003] Therefore, the selection of pervaporation membrane materials is crucial for preparing highly selective and permeable pervaporation membranes that can be used long-term and achieve efficient separation operations. Polydimethylsiloxane (PDMS) is currently the most widely used membrane material in the pervaporation separation of alcohols. However, due to the "trade-off" effect, the permeate flux and selectivity of traditional polymer membranes are mutually restrictive and cannot be improved simultaneously, greatly limiting their application range. Inorganic membranes have good performance, but their development is limited by high manufacturing costs, poor film-forming properties, and high brittleness. Hybrid matrix membranes (MMMs), prepared by dispersing porous particles in an organic polymer matrix, combine the advantages of organic polymer membranes and inorganic membranes. MMMs retain the easy processing and low cost of organic polymers, while the doped porous particles provide preferential permeation channels for alcohols, improving the membrane's separation performance. Therefore, MMMs are the preferred material for separating alcohols. The filling of porous particles is a key factor affecting the performance of mixed matrix membranes. Currently, porous particles used for filling include metal-organic frameworks (MOFs), covalent organic frameworks (COFs), zeolites, and carbon nanotubes (CNTs). However, the development of mixed matrix membranes faces several technical challenges: (1) the incompatibility between porous particles and organic polymers leads to interfacial voids and pore blockage, and porous particles exhibit severe aggregation and poor dispersion in organic polymers, resulting in decreased membrane performance; (2) traditional porous particles, especially MOFs and COFs, have poor crystallization stability at high temperatures or in the presence of moisture, making mixed matrix membranes prepared by filling organic polymers unstable and prone to performance degradation when separating alcohols. Therefore, it is essential to develop a new porous filling material to further improve the performance of mixed matrix membranes.

[0004] Graphdiyne (GDY) is a novel carbon allotrope composed of sp and sp2 atoms. 2Two-dimensional carbon materials are formed by hybrid carbon atoms interconnected by covalent bonds according to a certain pattern. Compared with traditional porous particles, graphyne has advantages such as large specific surface area, uniform pore dispersion, high porosity, excellent hydrophobicity and alcohol affinity, and chemimechanical stability. Therefore, graphyne has broad application prospects in alcohol permeation. Currently, no graphyne-based preferential alcohol permeation membrane has been developed for alcohol recovery, but the excellent properties of graphyne further illustrate its feasibility for alcohol recovery. Therefore, doping graphyne into organic polymers to construct selective separation layers with alcohol-preferred channels can significantly improve the pervaporation performance of mixed matrix membranes. This invention prepares a graphyne-based preferential alcohol permeation pervaporation membrane with a three-layer membrane structure by dropping organic polymers onto a porous base membrane loaded with two-dimensional graphyne material. Alcohol recovery is achieved through the pervaporation process, further enriching the types of preferential alcohol permeation membrane structures and materials, providing inspiration and reference for the development of new materials, and broadening the application fields of graphyne materials, accelerating their industrial application. Summary of the Invention

[0005] The key technical problem to be solved by this invention is to provide a method for preparing a graphitized acetylene-based preferential alcohol pervaporation membrane, thereby further improving the performance of the preferential alcohol pervaporation membrane in alcohol recovery. The specific technical solution is as follows:

[0006] A graphdiyne-based preferential alcohol pervaporation membrane is characterized by comprising three layers, from top to bottom: a mixed matrix layer, an organic polymer layer, and a lower porous base membrane support layer. The mixed matrix layer is located on the upper surface of the porous base membrane. An organic polymer layer extends downwards from the upper surface into the porous base membrane, meaning the organic polymer layer penetrates into the upper part of the porous base membrane. The thickness of the organic polymer layer is less than or equal to the thickness of the entire base membrane. Below the organic polymer 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 graphdiyne as the dispersion medium and the organic polymer as the dispersant. The graphdiyne is dispersed in the organic polymer generated by the crosslinking reaction of the organic polymer with a crosslinking agent and a catalyst. The mixed matrix layer and the organic polymer layer together constitute a selective separation layer.

[0007] The thickness of the mixed matrix layer with graphyne as the dispersant and the organic polymer as the dispersant is 1-10 μm, the thickness of the organic polymer layer is 1-10 μm, and the thickness of the selective separation layer composed of the mixed matrix layer with graphyne as the dispersant and the organic polymer layer is 2-20 μm.

[0008] The graphyne is one or more of graphitic monoyne and graphitic diyne. The particle size of graphyne ranges from 100 to 1000 nm, and it is a nanomaterial with extremely strong hydrophobicity.

[0009] 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.

[0010] The preparation method of graphitized acetylation-based preferential alcohol pervaporation membrane includes the following steps:

[0011] Step a: Mix the monomer containing terminal alkyne and the catalyst in an ethanol solution in a certain proportion, sonicate to completely dissolve them, react in a high-temperature oven for a period of time, centrifuge and take the precipitate, wash it with ethanol to obtain graphyne.

[0012] Step b: Disperse the graphyne obtained in step a in an ethanol solution of organic polymer, and sonicate for 2-24 hours to make it uniformly dispersed to prepare casting solution 1. Take a certain amount of casting solution 1 and load the graphyne in it onto the surface of the porous base membrane. The organic polymer remains on the surface of the loaded graphyne to increase the binding and loading force of the graphyne.

[0013] Step c: Mix the organic polymer, crosslinking agent, and catalyst evenly to prepare a crosslinking solution. Then, mix the crosslinking solution with the organic solvent evenly to prepare casting solution 2. Add a certain amount of casting solution 2 to the surface of the porous base membrane loaded with graphyne in step b. Due to the loose structure of the loaded graphyne, the casting solution 2 will automatically permeate through the graphyne into the porous base membrane layer, so that part of the casting solution 2 permeates into the porous base membrane layer to form the corresponding organic polymer layer. A portion of the casting solution 2 is left in the graphyne layer to form the corresponding mixed matrix layer together with the graphyne. After evaporating the organic solvent for 3-12 hours, place the membrane at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0014] Specifically, the organic polymers mentioned in steps b and c are one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsilylpropyne (PTMSP); the crosslinking agent is one or more of tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); and the catalyst is one or more of dibutyltin dilaurate (DBTDL), monobutyltin oxide (MBTO), dibutyltin oxide (DBTO), tripropyltin oxide (TPTO), or chloroplatinic acid.

[0015] Specifically, the terminal alkyne-containing 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 catalyst is one or more of copper hydroxide (Cu(OH)2), copper foil (Cu), or copper acetate (Cu(CH3COO)2); the ratio of the terminal alkyne-containing monomer to the catalyst is 1:5-5:1; the reaction temperature in the high-temperature oven is 60-120℃, and the reaction time is 2-8h.

[0016] Specifically, the graphylene prepared in step a has a particle size range of 100-1000 nm and is a nanomaterial with extremely strong hydrophobicity.

[0017] Specifically, the method for loading graphylene in step b is one or more of the following: vacuum filtration, titration coating, spraying, and dip coating.

[0018] Preferably, the content of organic polymer in the casting solution 1 in step b is 5wt%-50wt%; and the content of graphyne in the organic polymer is 0.1wt%-10wt%.

[0019] Preferably, the organic solvent in step c is one or more of ethanol, n-heptane, n-hexane, or cyclohexane; the crosslinking agent content in the crosslinking solution is 1wt%-30wt%, and the catalyst content is 0.1wt%-5wt%; the crosslinking solution content in the casting solution 2 is 5wt%-50wt%.

[0020] The present invention relates to the application of a graphite-based acetylation-preferential alcohol pervaporation membrane, which uses pervaporation to separate bio-alcohols from aqueous solutions or fermentation broths.

[0021] The beneficial effects of the technical solution provided by this invention are as follows: This invention comprises a three-layer membrane structure from top to bottom: a mixed matrix layer, an organic polymer layer, and a porous support layer. The outermost layer uses graphyne particles to increase the membrane's hydrophobicity and alcohol-affinity. The water contact angle of the membrane prepared by this invention can reach 136.2°, and the dynamic contact angle of ethanol is 1.7°. The graphyne in the outermost mixed matrix layer effectively increases the contact between the membrane and alcohols, preventing the membrane from being wetted by water. The addition of graphyne with a regular pore structure to the polymer provides preferential channels for alcohols. The second organic polymer layer further improves the separation performance through its dense polymer structure, and its embedding within the porous base membrane further increases the bonding force between the porous base membrane and the graphyne. The third porous support layer provides support for the selective separation layer of the membrane, increasing the membrane's stability. Therefore, the prepared graphyne-based preferential alcohol pervaporation membrane can efficiently and stably recover alcohols. The membrane's permeation flux and separation factor are increased by 50%-100% and 30%-60% respectively compared to traditional mixed matrix membranes. The doping of graphdiyne as a novel material further enhances the separation performance of the mixed matrix membrane. Furthermore, the three-layer membrane structure proposed in this invention provides inspiration for the development of new membrane materials and further broadens the application fields of graphdiyne. Attached Figure Description

[0022] Figure 1 The water contact angle test image (1-1), surface (1-2), and cross-section (1-3) of the GDY1-PDMS (GDY1 content is 2wt%) mixed matrix membrane prepared in Example 1 of this invention.

[0023] Figure 2 The water contact angle test image (2-1), surface (2-2), and cross-section (2-3) of the GDY1-PDMS (GDY1 content is 3wt%) mixed matrix membrane prepared in Example 2 of this invention are shown.

[0024] Figure 3 The water contact angle test image (3-1), surface (3-2), and cross-section (3-3) of the pure PDMS membrane prepared in the comparative embodiment of the present invention are shown in the following:

[0025] Figure 4 The structural diagrams of (4-1)GDY1 prepared in Example 1 of the present invention, (4-2)GDY2 prepared in Example 4 of the present invention, and (4-3)GDY3 prepared in Example 5 of the present invention are shown below. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments. Surface and cross-sectional images were observed and measured using a ZEISS Sigma 300 scanning electron microscope (SEM) and a TESCAN MIRA LMS scanning electron microscope (SEM), respectively. The water contact angle was observed and measured using an SDC-300 contact angle goniometer.

[0027] This invention provides a graphdiyne-based preferential alcohol pervaporation membrane and its preparation method, characterized in that it comprises a three-layer membrane structure consisting of a mixed matrix layer with graphdiyne as the dispersant and an organic polymer as the dispersant, an organic polymer layer, and a porous support layer.

[0028] In the graphdiyne-based preferential alcohol pervaporation membrane, a mixed matrix layer with graphdiyne as the dispersion medium and an organic polymer layer together constitute a selective separation layer; the graphdiyne is dispersed in the organic polymer generated by the crosslinking reaction of the organic polymer with a crosslinking agent and a catalyst.

[0029] Its preparation method includes the following steps:

[0030] Step 101: Mix the monomer containing terminal alkyne and the catalyst in an ethanol solution in a certain proportion, sonicate to completely dissolve them, react in a high-temperature oven for a period of time, centrifuge and take the precipitate, wash it with ethanol to obtain graphyne.

[0031] Step 102: Disperse the graphylene obtained in step 101 in a certain amount and proportion of organic polymer and ethanol solution, and sonicate for 4 hours to make it uniformly dispersed to prepare casting solution 1. Take a certain amount of casting solution 1 and load the graphylene in it onto the surface of the porous base membrane. The amount of casting solution added is 0.32 L / m. 2 .

[0032] Step 103: Take a certain amount of organic polymer, crosslinking agent, and catalyst in a certain proportion and mix them evenly to prepare a crosslinking solution. Then, mix the crosslinking solution with an organic solvent evenly to prepare casting solution 2. Add casting solution 2 dropwise to the surface of the porous base membrane loaded with graphylene in step 102. The amount of casting solution added is 0.32 L / m. 2 Due to the loose structure of the graphyne-loaded membrane, casting solution 2 will permeate through the graphyne and settle to the lower layer of the porous substrate membrane, forming a new membrane structure. After evaporating the organic solvent for 10 hours, the membrane is reacted at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0033] Specifically, the graphyne is one or more of graphene monoyne and graphene diyne.

[0034] Specifically, the organic polymer is one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsilylpropyne (PTMSP); the crosslinking agent is one or more of tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); and the catalyst is one or more of dibutyltin dilaurate (DBTDL), monobutyltin oxide (MBTO), dibutyltin oxide (DBTO), tripropyltin oxide (TPTO), or chloroplatinic acid.

[0035] Specifically, the thickness of the mixed matrix layer with graphyne as the dispersant and the organic polymer as the dispersant is 1-10 μm, the thickness of the organic polymer layer is 1-10 μm, and the thickness of the selective separation layer composed of the mixed matrix layer with graphyne as the dispersant and the organic polymer layer is 2-20 μm.

[0036] 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 zirconium oxide 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.

[0037] Specifically, the terminal alkyne-containing monomer mentioned in step 101 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 catalyst is one or more of copper hydroxide (Cu(OH)2), copper foil (Cu), or copper acetate (Cu(CH3COO)2); the ratio of the terminal alkyne-containing monomer to the catalyst can be 1:2, 1:1, 3:2, 2:1, or 5:2; the reaction temperature in the high-temperature oven can be 60℃, 80℃, 100℃, or 120℃, and the reaction time can be 2h, 4h, 6h, or 8h.

[0038] Specifically, the graphylene prepared in step 101 has an average particle size range of 100-1000 nm and is a nanomaterial with extremely strong hydrophobicity.

[0039] Preferably, the method for loading graphdiyne in step 102 is one or more of the following: vacuum filtration, titration coating, spraying, and dip coating.

[0040] Preferably, the content of organic polymer in the casting solution in step 102 can be 10wt%, 15wt%, 20wt%, 25wt%, or 30wt%; and the content of graphyne in the organic polymer can be 1wt%, 2wt%, 3wt%, 4wt%, or 5wt%.

[0041] Preferably, the organic solvent in step 103 can be one or more of ethanol, n-heptane, n-hexane, or cyclohexane; the content of the crosslinking agent in the crosslinking solution can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, or 25 wt%, and the content of the catalyst can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%; the content of the crosslinking solution in the casting solution can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, or 30 wt%.

[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] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0046] Step a: Dissolve the terminal alkyne monomer 1,3,5-triethynylbenzene (TEB) in a 0.5 g / L copper acetate ethanol solution (TEB to copper acetate mass ratio 2:1), sonicate to dissolve TEB, and then react in a 60℃ oven for 6 h. The resulting graphyne deposits at the bottom of the solution. After washing the precipitate with ethanol, centrifuge at 10000 r / min for 5 min to obtain graphyne.

[0047] Step b: Disperse 100 mg of graphyne obtained in step a in a mixed solution of 5 g polydimethylsiloxane (PDMS) and 20 g ethanol, and sonicate for 4 h to ensure uniform dispersion to prepare casting solution 1. Use casting solution 1 to load graphyne onto the surface of a porous substrate membrane using a vacuum-assisted method. The addition amount of casting solution 1 is 0.32 L / m³.2 .

[0048] Step c: Mix polydimethylsiloxane (PDMS), 15 wt% tetraethyl orthosilicate (TEOS) as a crosslinking agent, and 2 wt% dibutyltin dilaurate (DBTDL) as a catalyst to prepare a crosslinking solution. Then, mix 20 wt% of the crosslinking solution with ethanol to prepare casting solution 2. Add casting solution 2 dropwise to the surface of the porous substrate membrane loaded with graphdiene in step b. The amount of casting solution 2 added is 0.32 L / m. 2 Due to the loose structure of the graphyne-loaded membrane, casting solution 2 will permeate through the graphyne and settle to the lower layer of the porous base membrane, forming a new membrane structure. Afterwards, ethanol is evaporated for 10 hours, and the membrane is reacted at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0049] Figure 1-1 The hybrid matrix membrane prepared in this example shows a water contact angle of 129.3°, exhibiting good hydrophobicity. (SEM results) Figure 1-2 The prepared mixed matrix film showed uniform graphylene loading and no defects on its surface. Figure 1-3 The prepared mixed matrix membrane has a three-layer structure, in which the mixed matrix layer with graphynyne as the dispersant and organic polymer as the dispersant has a thickness of about 1.8 μm, the organic polymer layer has a thickness of about 6 μm, and the selective separation layer constructed by the two together has a thickness of 7.8 μm.

[0050] The prepared mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0051] The measured pervaporation performance of the mixed matrix membrane was: a permeation flux of 1919.7 gm³. -2 h -1 The separation factor was 11.5, and the ethanol content in the permeate was 35 wt%.

[0052] Example 2

[0053] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0054] Step a: Dissolve the terminal alkyne monomer 1,3,5-triethynylbenzene (TEB) in a 0.5 g / L copper acetate ethanol solution (TEB to copper acetate mass ratio 2:1), sonicate to dissolve TEB, and then react in a 60℃ oven for 6 h. The resulting graphyne deposits at the bottom of the solution. After washing the precipitate with ethanol, centrifuge at 10000 r / min for 5 min to obtain graphyne.

[0055] Step b: Disperse 150 mg of graphyne obtained in step a in a mixed solution of 5 g polydimethylsiloxane (PDMS) and 20 g ethanol, and sonicate for 4 h to ensure uniform dispersion, thus preparing casting solution 1. Use casting solution 1 to load graphyne onto the surface of a porous substrate membrane using a vacuum-assisted method. The amount of casting solution added is 0.32 L / m³. 2 .

[0056] Step c: Mix polydimethylsiloxane (PDMS), 15 wt% tetraethyl orthosilicate (TEOS) as a crosslinking agent, and 2 wt% dibutyltin dilaurate (DBTDL) as a catalyst to prepare a crosslinking solution. Then, mix 20 wt% of the crosslinking solution with ethanol to prepare casting solution 2. Add casting solution 2 dropwise to the surface of the porous substrate membrane loaded with graphdiene in step b. The amount of casting solution 2 added is 0.32 L / m. 2 Due to the loose structure of the graphyne-loaded membrane, casting solution 2 will permeate through the graphyne and settle to the lower layer of the porous base membrane, forming a new membrane structure. Afterwards, ethanol is evaporated for 10 hours, and the membrane is reacted at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0057] Figure 2-1 The hybrid matrix membrane prepared in this example shows a water contact angle of 136.2°, exhibiting good hydrophobicity. (SEM results) Figure 2-2 The prepared mixed matrix film showed uniform graphylene loading and no defects on its surface. Figure 2-3 The prepared mixed matrix membrane has a three-layer structure, in which the mixed matrix layer with graphyne as the dispersant and organic polymer as the dispersant has a thickness of about 2.2 μm, the organic polymer layer has a thickness of about 6 μm, and the selective separation layer constructed by the two has a thickness of 8.2 μm.

[0058] The prepared mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0059] The measured pervaporation performance of the hybrid matrix membrane was: a permeation flux of 1535.7 gm³. -2 h -1 The separation factor was 12.8, and the ethanol content in the permeate was 38 wt%.

[0060] Example 3

[0061] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0062] Step a: Dissolve the terminal alkyne monomer 1,3,5-triethynylbenzene (TEB) in a 0.5 g / L copper acetate ethanol solution (TEB to copper acetate mass ratio 2:1), sonicate to dissolve TEB, and then react in a 60℃ oven for 6 h. The resulting graphyne deposits at the bottom of the solution. After washing the precipitate with ethanol, centrifuge at 10000 r / min for 5 min to obtain graphyne.

[0063] Step b: Disperse 150 mg of graphyne obtained in step a in a mixed solution of 5 g polydimethylsiloxane (PDMS) and 20 g ethanol, and sonicate for 4 h to ensure uniform dispersion, thus preparing casting solution 1. Use casting solution 1 to load graphyne onto the surface of a porous substrate membrane using a vacuum-assisted method. The addition amount of casting solution 1 is 0.32 L / m³. 2 .

[0064] Step c: Mix polydimethylsiloxane (PDMS), 15 wt% tetraethyl orthosilicate (TEOS) as a crosslinking agent, and 2 wt% dibutyltin dilaurate (DBTDL) as a catalyst to prepare a crosslinking solution. Then, mix 20 wt% of the crosslinking solution with ethanol to prepare casting solution 2. Add casting solution 2 dropwise to the surface of the porous substrate membrane loaded with graphdiene in step b. The amount of casting solution 2 added is 0.32 L / m. 2 Due to the loose structure of the graphyne-loaded membrane, casting solution 2 will permeate through the graphyne and settle to the lower layer of the porous base membrane, forming a new membrane structure. Afterwards, ethanol is evaporated for 10 hours, and the membrane is reacted at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0065] The prepared mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% butanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0066] The measured pervaporation performance of the mixed matrix membrane was: a permeation flux of 2662.4 gm³. -2 h -1 The separation factor was 30.7, and the butanol content in the permeate was 59 wt%.

[0067] Comparative experiment

[0068] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0069] Step a: Add 5g of polydimethylsiloxane (PDMS) to 20g of ethanol and sonicate for 4 hours to mix evenly to prepare a casting solution. Use the casting solution to load PDMS onto the surface of a porous base membrane using a vacuum-assisted method. The amount of casting solution added is 0.32L / m. 2 .

[0070] Step b: Mix polydimethylsiloxane (PDMS), 15 wt% tetraethyl orthosilicate (TEOS) as a crosslinking agent, and 2 wt% dibutyltin dilaurate (DBTDL) as a catalyst to prepare a crosslinking solution. Then, mix 20 wt% of the crosslinking solution with ethanol to prepare casting solution 2. Drop casting solution 2 onto the surface of the PDMS-loaded membrane. The amount of casting solution 2 added is 0.32 L / m. 2 After evaporating ethanol for 10 hours, the membrane was placed at 80°C for 8 hours to prepare a pure PDMS preferential alcohol pervaporation membrane.

[0071] Figure 3-1 The SEM results show that the water contact angle of the pure PDMS membrane prepared in this example is 102.3°. Figure 3-2 The prepared pure PDMS film showed a dense and defect-free surface. Figure 3-3 The prepared pure PDMS membrane has a two-layer structure, with the selective separation layer having a thickness of 5.5 μm.

[0072] The prepared PDMS polymer membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0073] The measured pervaporation performance of the mixed matrix membrane was: a permeation flux of 1112.7 gm³. -2 h -1 The separation factor was 8.9, and the ethanol content in the permeate was 30 wt%.

[0074] Example 4

[0075] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0076] Step a: Dissolve the terminal alkyne monomer tris(4-ethynylphenyl)amine (TEPA) in a 0.5 g / L copper acetate ethanol solution (TEPA to copper acetate mass ratio 2:1), sonicate to dissolve the TEPA, and then react in a 60℃ oven for 6 h. The resulting graphyne deposits at the bottom of the solution. The precipitate is washed with ethanol and then centrifuged at 10000 r / min for 5 min to obtain graphyne.

[0077] Step b: Disperse 150 mg of graphyne obtained in step a in a mixed solution of 5 g polydimethylsiloxane (PDMS) and 20 g ethanol, and sonicate for 4 h to ensure uniform dispersion, thus preparing casting solution 1. Use casting solution 1 to load graphyne onto the surface of a porous substrate membrane using a vacuum-assisted method. The addition amount of casting solution 1 is 0.32 L / m³. 2 .

[0078] Step c: Mix polydimethylsiloxane (PDMS), 15 wt% tetraethyl orthosilicate (TEOS) as a crosslinking agent, and 2 wt% dibutyltin dilaurate (DBTDL) as a catalyst to prepare a crosslinking solution. Then, mix 20 wt% of the crosslinking solution with ethanol to prepare casting solution 2. Add casting solution 2 dropwise to the surface of the porous substrate membrane loaded with graphdiene in step b. The amount of casting solution 2 added is 0.32 L / m. 2 Due to the loose structure of the graphyne-loaded membrane, casting solution 2 will permeate through the graphyne and settle to the lower layer of the porous base membrane, forming a new membrane structure. Afterwards, ethanol is evaporated for 10 hours, and the membrane is reacted at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0079] The prepared mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0080] The measured pervaporation performance of the mixed matrix membrane was: a permeation flux of 1377.1 gm³. -2 h -1 The separation factor was 12.2, and the ethanol content in the permeate was 37 wt%.

[0081] Example 5

[0082] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0083] Step a: Dissolve the terminal alkyne monomer 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB) in a 0.5 g / L copper acetate ethanol solution (Ext-TEB to copper acetate mass ratio 2:1). Sonicate the solution to dissolve Ext-TEB, then react it in a 60°C oven for 6 hours. The resulting graphyne deposits at the bottom of the solution. Wash the precipitate with ethanol and centrifuge at 10000 r / min for 5 minutes to obtain graphyne.

[0084] Step b: Disperse 150 mg of graphyne obtained in step a in a mixed solution of 5 g polydimethylsiloxane (PDMS) and 20 g ethanol, and sonicate for 4 h to ensure uniform dispersion, thus preparing casting solution 1. Use casting solution 1 to load graphyne onto the surface of a porous substrate membrane using a vacuum-assisted method. The addition amount of casting solution 1 is 0.32 L / m³. 2 .

[0085] Step c: Mix polydimethylsiloxane (PDMS), 15 wt% tetraethyl orthosilicate (TEOS) as a crosslinking agent, and 2 wt% dibutyltin dilaurate (DBTDL) as a catalyst to prepare a crosslinking solution. Then, mix 20 wt% of the crosslinking solution with ethanol to prepare casting solution 2. Add casting solution 2 dropwise to the surface of the porous substrate membrane loaded with graphdiene in step b. The amount of casting solution 2 added is 0.32 L / m. 2 Due to the loose structure of the graphyne-loaded membrane, casting solution 2 will permeate through the graphyne and settle to the lower layer of the porous base membrane, forming a new membrane structure. Afterwards, ethanol is evaporated for 10 hours, and the membrane is reacted at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0086] The prepared mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0087] The measured pervaporation performance of the mixed matrix membrane was: a permeation flux of 1205.1 gm³. -2 h -1 The separation factor was 11.5, and the ethanol content in the permeate was 35 wt%.

[0088] Example 6

[0089] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0090] Step a: Dissolve the terminal alkyne monomer 1,3,5-triethynylbenzene (TEB) in a 0.5 g / L copper acetate ethanol solution (TEB to copper acetate mass ratio 2:1), sonicate to dissolve TEB, and then react in a 60℃ oven for 6 h. The resulting graphyne deposits at the bottom of the solution. After washing the precipitate with ethanol, centrifuge at 10000 r / min for 5 min to obtain graphyne.

[0091] Step b: Disperse 150 mg of graphyne obtained in step a in a mixed solution of 5 g polydimethylsiloxane (PDMS) and 20 g ethanol, and sonicate for 4 h to ensure uniform dispersion to prepare casting solution 1. Use casting solution 1 to load graphyne onto the surface of a porous substrate membrane using a titration coating method. The amount of casting solution added is 0.32 L / m³. 2 .

[0092] Step c: Mix polydimethylsiloxane (PDMS), 15 wt% tetraethyl orthosilicate (TEOS) as a crosslinking agent, and 2 wt% dibutyltin dilaurate (DBTDL) as a catalyst to prepare a crosslinking solution. Then, mix 20 wt% of the crosslinking solution with ethanol to prepare casting solution 2. Add casting solution 2 dropwise to the surface of the porous substrate membrane loaded with graphdiene in step b. The amount of casting solution 2 added is 0.32 L / m. 2 Due to the loose structure of the graphyne-loaded membrane, casting solution 2 will permeate through the graphyne and settle to the lower layer of the porous base membrane, forming a new membrane structure. Afterwards, ethanol is evaporated for 10 hours, and the membrane is reacted at 80°C for 8 hours to obtain a graphyne-based preferential alcohol pervaporation membrane.

[0093] The prepared mixed matrix membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0094] The measured pervaporation performance of the mixed matrix membrane was: a permeation flux of 1312.7 gm³. -2 h -1 The separation factor was 10.9, and the ethanol content in the permeate was 34 wt%.

[0095] 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 graphitized acetylenic preferential alcohol pervaporation membrane, characterized in that, The membrane consists of three layers, from top to bottom: a mixed matrix layer, an organic polymer layer, and a lower porous membrane support layer. The mixed matrix layer is located on the upper surface of the porous membrane. An organic polymer layer extends downwards into the porous membrane, meaning it penetrates into the upper part of the membrane. The thickness of the organic polymer layer is less than or equal to the thickness of the entire membrane. Below the organic polymer layer is the remaining lower part of the porous membrane, i.e., the lower porous membrane support layer. The mixed matrix layer is a composite layer using graphyne as the dispersion medium and the organic polymer as the dispersant. Graphyne is dispersed in the organic polymer generated by the crosslinking reaction of the organic polymer with a crosslinking agent and catalyst. The mixed matrix layer and the organic polymer layer together constitute a selective separation layer. The preparation method of graphitized acetylation-based preferential alcohol pervaporation membrane includes the following steps: Step a: Mix the monomer containing terminal alkyne and the catalyst in an ethanol solution in a certain proportion, sonicate to completely dissolve them, place them in a high-temperature oven to react for a period of time, centrifuge them and take the precipitate, wash it with ethanol, and obtain graphylene. Step b: Disperse the graphyne obtained in step a in an ethanol solution of organic polymer and sonicate it for 2-24 h to make it uniformly dispersed to prepare casting solution 1. Take a certain amount of casting solution 1 and load the graphyne in it onto the surface of the porous base membrane. The organic polymer remains on the surface of the loaded graphyne to increase the binding and loading force of the graphyne. Step c: Mix the organic polymer, crosslinking agent, and catalyst evenly to prepare a crosslinking solution. Then, mix the crosslinking solution with the organic solvent evenly to prepare casting solution 2. Add a certain amount of casting solution 2 to the surface of the porous base membrane loaded with graphyne in step b. Due to the loose structure of the loaded graphyne, the casting solution 2 will automatically permeate through the graphyne into the porous base membrane layer, so that part of the casting solution 2 permeates into the porous base membrane layer to form the corresponding organic polymer layer. A portion of the casting solution 2 is left in the graphyne layer to form the corresponding mixed matrix layer together with the graphyne. After evaporating the organic solvent for 3-12 h, place the membrane in an environment of 80 ℃ for 8 h to obtain a graphyne-based preferential alcohol pervaporation membrane.

2. The graphitized acetylation-based preferential alcohol pervaporation membrane according to claim 1, characterized in that, The thickness of the mixed matrix layer with graphyne as the dispersant and the organic polymer as the dispersant is 1-10 μm, the thickness of the organic polymer layer is 1-10 μm, and the thickness of the selective separation layer composed of the mixed matrix layer with graphyne as the dispersant and the organic polymer layer is 2-20 μm.

3. A graphitized acetylation-based preferential alcohol pervaporation membrane according to claim 1, characterized in that, The graphyne is one or more of graphene monoacetylenes and graphene diacetylenes; the particle size of graphyne ranges from 100 to 1000 nm, and it is a nanomaterial with extremely strong hydrophobicity.

4. A graphitized acetylenic preferential alcohol pervaporation 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 form of a flat plate, a tubular membrane, or a hollow fiber membrane.

5. A graphitized acetylenic preferential alcohol pervaporation membrane according to claim 1, characterized in that, The organic polymers are all one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxypyridine (PTMSP).

6. The method for preparing the graphitized acetylenic preferential alcohol pervaporation membrane according to any one of claims 1-5, characterized in that, Includes the following steps: Step a: Mix the monomer containing terminal alkyne and the catalyst in an ethanol solution in a certain proportion, sonicate to completely dissolve them, place them in a high-temperature oven to react for a period of time, centrifuge them and take the precipitate, wash it with ethanol, and obtain graphylene. Step b: Disperse the graphyne obtained in step a in an ethanol solution of organic polymer and sonicate it for 2-24 h to make it uniformly dispersed to prepare casting solution 1. Take a certain amount of casting solution 1 and load the graphyne in it onto the surface of the porous base membrane. The organic polymer remains on the surface of the loaded graphyne to increase the binding and loading force of the graphyne. Step c: Mix the organic polymer, crosslinking agent, and catalyst evenly to prepare a crosslinking solution. Then, mix the crosslinking solution with the organic solvent evenly to prepare casting solution 2. Add a certain amount of casting solution 2 to the surface of the porous base membrane loaded with graphyne in step b. Due to the loose structure of the loaded graphyne, the casting solution 2 will automatically permeate through the graphyne into the porous base membrane layer, so that part of the casting solution 2 permeates into the porous base membrane layer to form the corresponding organic polymer layer. A portion of the casting solution 2 is left in the graphyne layer to form the corresponding mixed matrix layer together with the graphyne. After evaporating the organic solvent for 3-12 h, place the membrane in an environment of 80 ℃ for 8 h to obtain a graphyne-based preferential alcohol pervaporation membrane.

7. The method according to claim 6, characterized in that, The organic polymers mentioned in steps b and c are all one or more of polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsilylpropyne (PTMSP); the crosslinking agent is one or more of tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); and the catalyst is one or more of dibutyltin dilaurate (DBTDL), monobutyltin oxide (MBTO), dibutyltin oxide (DBTO), tripropyltin oxide (TPTO), or chloroplatinic acid. Specifically, the terminal alkyne-containing monomer 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 catalyst is one or more of copper hydroxide (Cu(OH)2), copper foil (Cu), or copper acetate (Cu(CH3COO)2); the ratio of the terminal alkyne-containing monomer to the catalyst is 1:5-5:1; the reaction temperature in the high-temperature oven is 60-120 ℃, and the reaction time is 2-8 h; The graphdiene prepared in step a has a particle size range of 100-1000 nm and is a nanomaterial with extremely strong hydrophobicity. The method for loading graphylene in step b is one or more of the following: vacuum filtration, titration coating, spraying, and dip coating.

8. The method according to claim 6, characterized in that, In step b, the content of the organic polymer in the casting solution 1 is 5 wt%-50 wt%; the content of the graphyne in the organic polymer is 0.1 wt%-10 wt%. The organic solvent mentioned in step c is one or more of ethanol, n-heptane, n-hexane or cyclohexane; the crosslinking agent content in the crosslinking solution is 1 wt%-30 wt%, and the catalyst content is 0.1 wt%-5 wt%; the crosslinking solution content in the casting solution 2 is 5 wt%-50 wt%.

9. The application of the graphene-based preferential alcohol pervaporation membrane according to any one of claims 1-5, wherein bio-alcohols are separated from aqueous solutions or fermentation broths by pervaporation.

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