Preparation method and application of ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane
By etching the surface of ZIF-8 to form mesoporous channels and grafting polyaniline sheets, a ZIF-8-grafted polyaniline-doped PDMS hybrid matrix membrane was prepared, which solved the "trade-off" problem between the permeability and selectivity of PDMS membrane and improved the separation performance of biobutanol.
Patent Information
- Application Number
- CN202511541456.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2025-12-23
AI Technical Summary
Existing pure PDMS membranes exhibit a "trade-off" effect between permeability and selectivity in the separation of biobutanol, and ZIF-8 has poor compatibility with the PDMS matrix, which limits the membrane separation performance.
By etching the surface of ZIF-8 to form mesoporous channels, grafting polyaniline sheets and performing hydrophobic modification, a ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film was prepared, which enhanced the dispersibility and hydrophobicity of the filler.
It improved the membrane's permeation flux and separation factor, solved the membrane's "trade-off" effect, enhanced the compatibility of the packing material with the matrix, and improved molecular mass transfer efficiency.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of membranes, and particularly relates to a mesoporous hollow ZIF-8 grafted polyaniline sheet doped PDMS-based mixed matrix membrane and a preparation method and application thereof. BACKGROUND
[0002] Biofuel is an important direction of renewable energy development and utilization, and bio-butanol is a high-quality biofuel. Bio-butanol has high calorific value, small vapor pressure, small corrosion, and good compatibility, and thus becomes a biofuel product with excellent performance. At present, bio-butanol is usually obtained by fermentation of biomass, but this approach has problems of low yield, high energy consumption, and the like, and the toxicity of the final product also affects the production efficiency of bio-butanol. In order to improve the yield and energy consumption of the separation process of bio-butanol, the use of hydrophobic pervaporation membranes to assist in the separation and enrichment of bio-butanol in bio-fermentation has been widely studied. As a new type of membrane separation technology, pervaporation can realize separation tasks that are difficult to complete by traditional means such as distillation, extraction, and adsorption under low energy consumption, and has high separation performance. The research and industrialization of membranes are of great significance to promote the large-scale production of bio-butanol and reduce the cost of bio-butanol.
[0003] The selection and structure of the membrane material have a great influence on the separation performance, which is a key factor to determine the separation cost and energy consumption. The most common hydrophobic membrane material for recovering alcohols is a high molecular polymer such as polydimethylsiloxane (PDMS), polyether block polyamide (PEBA), and polyvinylidene fluoride (PVDF). PDMS has been widely used in the preparation of pervaporation membranes due to its high hydrophobicity, high thermal stability, and chemical stability. However, the separation performance of pure PDMS membranes no longer meets the production requirements, and there is a “trade-off” effect between the permeability and selectivity of the membranes.
[0004] Metal-organic framework (MOF) doped mixed matrix membranes (MMMs) have attracted widespread attention due to their unique characteristics of improving selectivity and permeability through the synergistic integration of polymer matrix and inorganic fillers, and can effectively improve the separation effect of the membranes on bio-butanol. At present, the preparation of ZIF fillers mainly includes two strategies of post-synthesis modification and in-situ growth. Although in-situ growth of MOF has good compatibility with the polymer matrix and exhibits a very high separation factor, the total flux is generally not ideal. Post-synthesis modification (PSM) is an effective method for introducing functional chemical groups into metal-organic frameworks (MOFs) by modifying metal clusters or ligands after the synthesis of MOFs, and is a main strategy for obtaining balanced separation performance. However, the problems of agglomeration of fillers in the membranes and compatibility with the matrix need to be solved.
[0005] In order to improve the filler dispersion problem, improve the upper limit of the "trade off" effect of the pervaporation membrane, and make certain progress in the separation performance, there is still a lot of room for improvement. ZIF-8 has a high separation of alcohol / water separation system due to the hydrophobic pore surface. However, due to its surface chemical inertness, it has poor compatibility with the PDMS matrix, resulting in defects such as cracks that affect the separation performance of the membrane. Therefore, in this study, tannic acid is used to etch the surface of ZIF-8 to obtain a hollow ZIF-8 structure with mainly mesoporous channels, thereby promoting the mass transfer efficiency of the molecules and greatly improving the permeation flux of the membrane; then polyaniline sheets are grafted to eliminate the influence of the hydroxyl groups on the surface of the tannic acid on the performance of the membrane and improve the hydrophobicity of the filler; finally, MPTES is used to modify the surface of the membrane to further enhance the hydrophobicity of the membrane to maintain high permeation flux while obtaining high separation factor. SUMMARY
[0006] In order to improve the dispersion of MOF fillers in the membrane and solve the problem of low mass transfer efficiency of target molecules in the membrane, and to break through the upper limit of the "trade off" effect of the membrane, the present application provides a ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane and a preparation method thereof.
[0007] The technical scheme adopted by the present application is as follows: A ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane, the mixed matrix membrane is prepared by the following method: (1) Disperse ZIF-8 powder in a solvent, ultrasonic treatment, heat to 20-70 ℃, add 0.5-4 g / L tannic acid solution and catalyst, stir at 30-70 ℃ (preferably 40 ℃) for 10-30 min, after the reaction is completed, centrifuge to take the precipitate, wash with ethanol, and dry to obtain eZIF-8 powder; the catalyst is one or more of hydrochloric acid, sodium hydroxide or potassium iodide; the mass ratio of tannic acid in the tannic acid solution, ZIF-8 powder and catalyst is 1:1-3:0.1-3 (preferably 1:2:0.33); (2) Add polyaniline sheets to anhydrous ethanol A, ultrasonic stirring treatment (ultrasonic stirring each for 30 min alternately for 8-48 h), collect the upper uniform dispersion liquid to obtain solution A; add the eZIF-8 powder of step (1) to anhydrous ethanol B, ultrasonic treatment, to obtain solution B; mix solution B and solution A, stir for 0.5-6 h (preferably 1.5 h), centrifuge to take the precipitate (10000 rpm, 8 min), wash with ethanol, and dry to obtain eZIF-8@PANI; the mass ratio of polyaniline sheets to eZIF-8 powder is 10:1-20 (preferably 1:0.5); (3) dissolving polydimethylsiloxane (PDMS) in a non-polar solvent, stirring and dissolving, adding the eZIF-8@PANI prepared in step (2), continuing to stir for 3-8 h, mixing uniformly, adding tetraethyl orthosilicate (TEOS, crosslinking agent) for crosslinking for 10-30 min, adding dibutyltin dilaurate (DBTDL, catalyst) for catalytic reaction for 8-20 min, to obtain a casting solution; pouring the casting solution on a hydrophobic base film for blade coating to obtain a wet film, and after the solvent in the casting solution in the wet film evaporates, the eZIF-8@PANI / PDMS mixed matrix membrane is obtained; the mass ratio of the polydimethylsiloxane, the eZIF-8@PANI, the tetraethyl orthosilicate and the dibutyltin dilaurate is 100:5-20:5-15:1-3 (preferably 100:15:10:1); (4) dissolving γ-mercaptopropyltriethoxysilane (MPTES) in anhydrous ethanol, ultrasonic treatment to obtain solution C, immersing the eZIF-8@PANI / PDMS mixed matrix membrane in step (3) in solution C, grafting reaction at 20-75°C (preferably 40°C) for 1-8 h (preferably 3 h), drying at room temperature, and then heat crosslinking at 60-120°C (preferably 80°C) for 6-12 h (preferably 10 h) to obtain the ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane.
[0008] Further, the solvent in step (1) is water, methanol, anhydrous ethanol or DMF.
[0009] Further, the volume of the anhydrous ethanol A in step (2) is 500-2000 ml / g (preferably 1000 ml / g) based on the mass of the polyaniline sheet.
[0010] Further, the volume of the anhydrous ethanol B in step (2) is 400-5000 ml / g (preferably 2000 ml / g) based on the mass of the eZIF-8.
[0011] Further, the non-polar solvent in step (3) is one or more of n-heptane, n-hexane, chloroform or toluene.
[0012] Further, the hydrophobic base film in step (3) is one or more of polyvinylidene fluoride ultrafiltration membrane (PVDF), polysulfone ultrafiltration membrane (PSU) or polytetrafluoroethylene ultrafiltration membrane (PTFE).
[0013] Further, the hydrophobic base film in step (3) is pretreated by immersing in a 20wt% ethanol aqueous solution for 1-5 h.
[0014] Further, the thickness of the wet film in the blade coating experiment in step (3) is 30-100 μm, and the blade coating rate is 30-50 mm / s.
[0015] Further, the volume of the non-polar solvent in step (3) is 2-20 ml / g based on the mass of the polydimethylsiloxane
[0016] Further, the mass fraction of the gamma-mercaptopropyl triethoxysilane in the solution C in step (4) is 1-4 wt%.
[0017] The application also provides a use of a ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane in butanol separation.
[0018] In the application, the polyaniline sheet is prepared by a conventional method known in the art, and a recommended preparation method is as follows: Aniline is dissolved in 1M hydrochloric acid to obtain an aniline solution; ammonium persulfate is dissolved in 1M hydrochloric acid to obtain an ammonium persulfate solution; the ammonium persulfate aqueous solution is added (quickly) into the aniline solution at 0-2 ℃, and stirred for 1 h, filtered, and the filter cake is washed with water and ethanol in sequence (until the filtrate is colorless), and dried. The obtained solid is stirred in 10 wt% ammonia water solution for 30 h, filtered, the filter cake is washed with water and methanol in sequence, and dried to obtain the polyaniline sheet; In the application, the ZIF-8 is prepared by a conventional method known in the art, and a recommended preparation method is as follows: 1 g of zinc nitrate hexahydrate is dissolved in 50 mL of methanol, and is recorded as solution A; 2.22 g of 2-methylimidazole is dissolved in 50 mL of methanol, and is recorded as solution B. Then, the solution B is poured into the solution A, and stirred at room temperature for 50 min, centrifuged and washed with methanol for 2 times, and dried in an oven at 80 ℃ for 12 h to obtain the ZIF-8.
[0019] Compared with the prior art, the application has the following beneficial effects: (1) The microporous and mesoporous multi-channel system is formed by a thermal induction recombination process, the mesoporous eZIF-8 is obtained, and the mesoporous eZIF-8 is used for the preparation of a pervaporation membrane, so that the molecular transmission efficiency of butanol is improved.
[0020] (2) The completely dispersed polyaniline sheet and the mesoporous eZIF-8 are integrally compounded by bonding, which not only covers the hydrophilic hydroxyl groups existing on the surface of the mesoporous eZIF-8 to ensure the hydrophobicity of the filler, but also enhances the dispersity of the filler and the compatibility between the filler and the polymer matrix, and weakens the agglomeration problem.
[0021] (3) The graft modification of MPTES is applied to the field of butanol recovery by pervaporation for the first time. The modification enhances the hydrophobicity of the membrane and improves the durability of the membrane. BRIEF DESCRIPTION OF DRAWINGS
[0022] Figure 1 It is a schematic diagram of a pervaporation test device.
[0023] Figure 2 Scanning and transmission electron micrographs of the prepared eZIF-8. DETAILED DESCRIPTION
[0024] The performance test method in the examples is as follows: The prepared mixed matrix membrane was evaluated by using a pervaporation test device, and the effective area of the membrane was 7 cm 2 . The test temperature was 40 ℃, the feed liquid was 1 wt% n-butanol aqueous solution, and the gas chromatograph (GC-14B) was used to determine the permeation solution flux and the concentration of n-butanol.
[0025] The calculation formula of the permeation flux is:
[0026] In the formula, J (g m - ²h -1 ) is the total permeation flux; W (g) is the total mass of the permeation liquid collected in the PV performance test, S (m 2 ) is the effective membrane area, and T (h) is the performance test duration.
[0027] The calculation formula of the separation factor is:
[0028] In the formula, is the separation factor; Y p and X f are the n-butanol content (wt%) in the permeation liquid and the feed liquid, respectively.
[0029] The PVDF ultrafiltration membrane used in the following examples is manufactured by China Kureha Membrane Technology (Beijing) Co., Ltd., with the product number SG-UF050-8040 and a molecular weight cut-off of 50000 Da.
[0030] Example 1: (1): Preparation of eZIF-8: 0.3 g ZIF-8 powder was dispersed in 50 mL water, ultrasonic treatment, heated to 40 °C, ready for use; 0.15 g tannic acid was dissolved in 50 mL water, stirred until the tannic acid was completely dissolved, to obtain a 3 g / L tannic acid solution; 0.05 g sodium hydroxide was dissolved in 25 mL anhydrous ethanol to obtain a 2 g / L sodium hydroxide solution. The tannic acid solution and sodium hydroxide solution were slowly poured into the ZIF-8 solution, stirred at 40 °C for 15 min, centrifuged and washed twice with ethanol, dried in an oven at 80 °C for 8 h, and dried to obtain eZIF-8 powder.
[0031] (2): Preparation of eZIF-8@PANI: 0.1 g of polyaniline sheet was weighed and added to 100 mL of anhydrous ethanol, and ultrasonic stirring was alternated for 30 min for 24 h. The upper layer of the uniform dispersion was collected and labeled as solution A. 0.05 g of eZIF-8 was weighed and added to 100 mL of anhydrous ethanol, and ultrasonic dispersion was performed for 30 min, labeled as solution B. Solution B was then poured into A and stirred for 1.5 h, then centrifuged (10000 rpm, 8 min), washed twice with ethanol, and dried to obtain eZIF-8@PANI.
[0032] (3): Preparation of eZIF-8@PANI / PDMS mixed matrix membrane: 0.855 g of PDMS (polydimethylsiloxane) was dissolved in 5 mL of n-heptane; then 0.1283 g of eZIF-8@PANI was added and stirring was continued for 5 h. 92 μL (0.0855 g) of tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g of dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain a casting solution. The casting solution was then poured onto a PVDF hydrophobic base membrane pretreated by soaking in a 20 wt% ethanol aqueous solution for 2 h for blade coating experiments (the PVDF membrane was fixed on the surface of the blade coater in advance, and the thickness of the blade was set to 50 μm, and the blade coating rate was 40 mm / s. After the casting solution was poured onto the surface of the PVDF membrane in front of the blade, the machine was started to obtain a wet film). After the solvent evaporated at room temperature, the eZIF-8@PANI / PDMS mixed matrix membrane was obtained.
[0033] (4): Preparation of MT-eZIF-8@PANI / PDMS membrane: 3 mL MPTES was dissolved in 100 g anhydrous ethanol, and ultrasonic treatment was performed to prepare a solution. The prepared eZIF-8@PANI / PDMS membrane was immersed in the solution, and a grafting reaction was performed at 40 °C for 3 h. After the membrane surface solution was wiped off with a water absorption paper, the membrane was air-dried at room temperature and then placed in an oven for heat crosslinking at 80 °C for 10 h to obtain a MT-eZIF-8@PANI / PDMS mixed matrix membrane (i.e., a ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane).
[0034] The obtained MT-eZIF-8@PANI / PDMS membrane had a permeation flux of 2977 g m-2h-1 for 1 wt% butanol / water at 40 °C, a flow rate of 180 mL / min, and a vacuum degree of less than 200 Pa, and a separation factor of 51.9. -2 h -1
[0035] Example 2: (change of etching temperature)
[0036] (1): Preparation of eZIF-8: 0.3 g of ZIF-8 powder was dispersed in 50 mL of water, ultrasonic treatment was performed, and heating was performed to 40 °C, for standby; 0.15 g of tannic acid was dissolved in 50 mL of water, and stirring was performed until the tannic acid was completely dissolved to obtain a 3 g / L tannic acid solution; 0.05 g of sodium hydroxide was dissolved in 25 mL of anhydrous ethanol to obtain a 2 g / L sodium hydroxide solution. The tannic acid solution and the sodium hydroxide solution were slowly poured into the ZIF-8 solution, and stirring was performed at 65 °C for 15 min. After the reaction was completed, centrifugation was performed, and ethanol was used for washing twice, and drying was performed in an oven at 80 °C for 8 h. The dried eZIF-8 powder was obtained.
[0037] (2): Preparation of eZIF-8@PANI: 0.1 g of polyaniline sheet was weighed and added into 100 mL of anhydrous ethanol, and ultrasonic stirring was alternately performed for 30 min for 24 h. The upper layer of the uniform dispersion liquid was collected, and was recorded as solution A. 0.05 g of eZIF-8 was weighed and added into 100 mL of anhydrous ethanol, and ultrasonic treatment was performed for 30 min, and was recorded as solution B. Then, solution B was poured into A, and stirring was performed for 1.5 h. After centrifugation (10000 rpm, 8 min), ethanol was used for washing twice, and drying was performed to obtain eZIF-8@PANI.
[0038] (3): Preparation of eZIF-8@PANI / PDMS mixed matrix membrane: 0.855 g PDMS was dissolved in 5 mL n-heptane; then 0.1283 g eZIF-8@PANI was added and stirred for 5 h until well mixed. 92 μL (0.0855 g) tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain the casting solution. The casting solution was then poured onto the PVDF hydrophobic substrate membrane which was pretreated by soaking in 20 wt% aqueous ethanol solution for 2 h and then subjected to blade coating (the PVDF membrane was fixed on the flat surface of the blade coater, and the thickness of the blade was set to 50 μm, and the blade coating speed was 40 mm / s. After the casting solution was obtained, it was poured onto the surface of the PVDF membrane in front of the blade, and then the machine was started to obtain the wet membrane). After the room temperature solvent evaporated, the eZIF-8@PANI / PDMS mixed matrix membrane was obtained.
[0039] (4): Preparation of MT-eZIF-8@PANI / PDMS membrane: 3 mL MPTES was dissolved in 100 g anhydrous ethanol and ultrasonically treated to prepare a solution. The prepared eZIF-8@PANI / PDMS membrane was immersed in the solution and subjected to grafting reaction at 40 °C for 3 h. After the membrane was taken out and the solution on the surface of the membrane was wiped off with absorbent paper, it was air-dried at room temperature and then placed in an oven for thermal crosslinking at 80 °C for 10 h to obtain the MT-eZIF-8@PANI / PDMS mixed matrix membrane (i.e. ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane).
[0040] The obtained MT-eZIF-8@PANI / PDMS membrane had a permeation flux of 1235 g m -2 h -1 -1 for the separation of 1 wt% butanol / water at 40 °C, a flow rate of 180 mL / min, and a vacuum degree of less than 200 Pa, and a separation factor of 31.4. (The ZIF-8 framework partially collapsed at too high a temperature, losing most of the pore channel; in addition, non-selective defects were easily generated in the membrane)
[0041] Example 3: (Changing the loading of eZIF-8@PANI in the membrane)
[0042] (1): Preparation of eZIF-8: 0.3 g ZIF-8 powder was dispersed in 50 mL water, ultrasonic treatment, heated to 40 °C, ready for use; 0.15 g tannic acid was dissolved in 50 mL water, stirred until the tannic acid was completely dissolved, to obtain a 3 g / L tannic acid solution; 0.05 g sodium hydroxide was dissolved in 25 mL anhydrous ethanol to obtain a 2 g / L sodium hydroxide solution. The tannic acid solution and sodium hydroxide solution were slowly poured into the ZIF-8 solution, stirred at 40 °C for 15 min, centrifuged and washed twice with ethanol, dried in an oven at 80 °C for 8 h, and dried to obtain eZIF-8 powder.
[0043] (2): Preparation of eZIF-8@PANI: 0.1 g of polyaniline sheet was weighed into 100 mL of anhydrous ethanol, and ultrasonic stirring was alternated for 30 min for 24 h. The upper layer of the uniform dispersion was collected and labeled as solution A. 0.05 g of eZIF-8 was weighed into 100 mL of anhydrous ethanol and dispersed by ultrasonic treatment for 30 min, labeled as solution B. Then solution B was poured into A and stirred for 1.5 h. After centrifugation (10000 rpm, 8 min), ethanol washing was performed twice, and drying was performed to obtain eZIF-8@PANI.
[0044] (3): Preparation of eZIF-8@PANI / PDMS mixed matrix membrane: 0.855 g of PDMS was dissolved in 5 mL of n-heptane; then 0.0428 g of eZIF-8@PANI was added and stirring was continued for 5 h. 92 μL (0.0855 g) of tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g of dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain a casting solution. The casting solution was then poured onto a PVDF hydrophobic base membrane pretreated by immersion in a 20 wt% ethanol aqueous solution for 2 h and subjected to a blade coating experiment (the PVDF membrane was fixed on the surface of the blade coater in advance, the thickness of the blade was set to 50 μm, and the blade coating rate was 40 mm / s. After the casting solution was poured onto the surface of the PVDF membrane in front of the blade, the machine was started to obtain a wet membrane). After the solvent evaporated at room temperature, an eZIF-8@PANI / PDMS mixed matrix membrane was obtained.
[0045] (4): Preparation of MT-eZIF-8@PANI / PDMS membrane: 3 mL of MPTES was dissolved in 100 g of anhydrous ethanol and ultrasonically treated to prepare a solution. The prepared eZIF-8@PANI / PDMS membrane was immersed in the solution and subjected to grafting reaction at 40 °C for 3 h. After the membrane surface solution was wiped off with a blotting paper, it was air-dried at room temperature and then placed in an oven for thermal crosslinking at 80 °C for 10 h to obtain a MT-eZIF-8@PANI / PDMS mixed matrix membrane (i.e., a ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane).
[0046] The obtained MT-eZIF-8@PANI / PDMS membrane has a permeation flux of 2208 g m-2h-1 for 1 wt% butanol / water at 40 °C, a flow rate of 180 mL / min, and a vacuum degree of less than 200 Pa. -2 h -1 The separation factor is 44.6.
[0047] Example 4: (changing the reaction time of eZIF-8 and PANI)
[0048] (1): Preparation of eZIF-8: 0.3 g of ZIF-8 powder was dispersed in 50 mL of water, ultrasonically treated, heated to 40 °C, and prepared for use; 0.15 g of tannic acid was dissolved in 50 mL of water, stirred until the tannic acid was completely dissolved, and a 3 g / L tannic acid solution was obtained; 0.05 g of sodium hydroxide was dissolved in 25 mL of anhydrous ethanol to obtain a 2 g / L sodium hydroxide solution. The tannic acid solution and the sodium hydroxide solution were slowly poured into the ZIF-8 solution, stirred at 40 °C for 15 min, and after the reaction was completed, centrifuged and washed twice with ethanol, dried in an oven at 80 °C for 8 h, and dried to obtain eZIF-8 powder.
[0049] (2): Preparation of eZIF-8@PANI: 0.1 g of polyaniline sheets was weighed into 100 mL of anhydrous ethanol, alternately ultrasonically stirred for 30 min for 24 h, and the upper layer of the uniform dispersion was collected, marked as solution A; 0.05 g of eZIF-8 was weighed into 100 mL of anhydrous ethanol, ultrasonically dispersed for 30 min, and marked as solution B. Then solution B was poured into A, stirred for 0.5 h, and then centrifuged (10000 rpm, 8 min), washed twice with ethanol, and dried to obtain eZIF-8@PANI.
[0050] (3): Preparation of eZIF-8@PANI / PDMS mixed matrix membrane: 0.855 g of PDMS was dissolved in 5 mL of n-heptane; then 0.1283 g of eZIF-8@PANI was added, and stirring was continued for 5 h until the mixture was uniform. 92 μL (0.0855 g) of tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g of dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain a casting solution; then the casting solution was poured onto a PVDF hydrophobic base membrane that had been pretreated by immersion in a 20 wt% ethanol aqueous solution for 2 h to perform a blade coating experiment (the PVDF membrane was fixed on the plane of the blade coating machine in advance, the thickness of the blade was set to 50 μm, and the blade coating rate was 40 mm / s. After the casting solution was poured onto the surface of the PVDF membrane in front of the blade, the machine was started to obtain a wet membrane). After the solvent evaporated at room temperature, an eZIF-8@PANI / PDMS mixed matrix membrane was obtained.
[0051] (4): Preparation of MT-eZIF-8@PANI / PDMS membrane: 3 mL MPTES was dissolved in 100 g anhydrous ethanol, ultrasonic treatment, prepared into a solution. The prepared eZIF-8@PANI / PDMS membrane was immersed in the solution, grafted at 40 ℃ for 3 h, after taking out and wiping the membrane surface solution with water absorption paper, drying at room temperature, and then placed in an oven for heat crosslinking at 80 ℃ for 10 h, to obtain the MT-eZIF-8@PANI / PDMS mixed matrix membrane (i.e. ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane).
[0052] The obtained MT-eZIF-8@PANI / PDMS membrane has a permeation flux of 2661 g m-2h-1 for 1 wt% butanol / water separation under the conditions of 40 ℃, flow rate of 180 mL / min, and vacuum degree less than 200 Pa. -2 h -1 , and a separation factor of 36.7. (PANI and eZIF-8 reaction is not complete, and too much hydrophilic group of filler remains)
[0053] Example 5: (change of MPTES grafting time)
[0054] (1): Preparation of eZIF-8: 0.3 g ZIF-8 powder was dispersed in 50 mL water, ultrasonic treatment, heated to 40 ℃, and used; 0.15 g tannic acid was dissolved in 50 mL water, stirred until the tannic acid was completely dissolved, to obtain a 3 g / L tannic acid solution; 0.05 g sodium hydroxide was dissolved in 25 mL anhydrous ethanol, to obtain a 2 g / L sodium hydroxide solution. The tannic acid solution and the sodium hydroxide solution were slowly poured into the ZIF-8 solution, stirred at 40 ℃ for 15 min, centrifuged, washed with ethanol twice, and dried in an oven at 80 ℃ for 8 h, to obtain eZIF-8 powder.
[0055] (2): Preparation of eZIF-8@PANI: 0.1 g polyaniline sheet was weighed and added into 100 mL anhydrous ethanol, ultrasonic stirring for 30 min, and the stirring was continued for 24 h, the upper uniform dispersion was collected, and was recorded as solution A; 0.05 g eZIF-8 was weighed and added into 100 mL anhydrous ethanol, ultrasonic treatment for 30 min, and was recorded as solution B. Then solution B was poured into A, stirred for 1.5 h, centrifuged (10000 rpm, 8 min), washed with ethanol twice, and dried to obtain eZIF-8@PANI.
[0056] (3): Preparation of eZIF-8@PANI / PDMS mixed matrix membrane: 0.855 g PDMS was dissolved in 5 mL n-heptane; then 0.1283 g eZIF-8@PANI was added and stirred for 5 h until well mixed. 92 μL (0.0855 g) tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain the casting solution. The casting solution was then poured onto the PVDF hydrophobic substrate membrane which was pretreated by soaking in 20 wt% aqueous ethanol solution for 2 h, and then the blade coating experiment was carried out (the PVDF membrane was fixed on the plane of the blade coater in advance, and the thickness of the blade was set to 50 μm, and the blade coating speed was 40 mm / s. After the casting solution was obtained, it was poured onto the surface of the PVDF membrane in front of the blade, and then the machine was started to obtain the wet membrane). After the room temperature solvent evaporated, the eZIF-8@PANI / PDMS mixed matrix membrane was obtained.
[0057] (4): Preparation of MT-eZIF-8@PANI / PDMS membrane: 3 mL MPTES was dissolved in 100 g anhydrous ethanol and ultrasonically treated to prepare a solution. The prepared eZIF-8@PANI / PDMS membrane was immersed in the solution and grafted at 40 °C for 6 h. After the membrane surface solution was wiped off with absorbent paper, it was air-dried at room temperature and then placed in an oven for heat crosslinking at 80 °C for 10 h to obtain the MT-eZIF-8@PANI / PDMS mixed matrix membrane (i.e. ZIF-8 grafted polyaniline doped PDMS mixed matrix membrane).
[0058] The obtained MT-eZIF-8@PANI / PDMS membrane had a permeation flux of 2038 g m -2 h -1 -1 for 1 wt% butanol / water separation at 40 °C, a flow rate of 180 mL / min, and a vacuum degree of less than 200 Pa, and a separation factor of 55.2. (The modification time was too long, and MPTES blocked the membrane surface pore size and reduced the porosity)
[0059] Comparative Example 1: Preparation of PDMS membrane
[0060] Preparation of PDMS mixed matrix membrane: 0.855 g PDMS was dissolved in 5 mL n-heptane. 92 μL (0.0855 g) tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain the casting solution. The casting solution was then poured onto the PVDF hydrophobic base membrane pretreated by soaking in 20 wt% ethanol aqueous solution for 2 h for the blade coating experiment (the PVDF membrane was fixed on the plane of the film applicator in advance, and the thickness of the doctor blade was set to 50 μm, and the film application rate was 40 mm / s. After the casting solution was obtained, it was poured onto the surface of the PVDF membrane in front of the doctor blade, and then the machine was started to obtain the wet film). After the solvent was evaporated at room temperature, it was placed in an oven for heat crosslinking at 80 °C for 10 h to obtain the PDMS membrane.
[0061] The obtained PDMS membrane had a permeation flux of 843 g m -2 h -1 -1
[0062] Preparation of ZIF-8 / PDMS mixed matrix membrane
[0063] Preparation of ZIF-8 / PDMS mixed matrix membrane: 0.855 g PDMS was dissolved in 5 mL n-heptane. 92 μL (0.0855 g) tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain the casting solution. The casting solution was then poured onto the PVDF hydrophobic base membrane pretreated by soaking in 20 wt% ethanol aqueous solution for 2 h for the blade coating experiment (the PVDF membrane was fixed on the plane of the film applicator in advance, and the thickness of the doctor blade was set to 50 μm, and the film application rate was 40 mm / s. After the casting solution was obtained, it was poured onto the surface of the PVDF membrane in front of the doctor blade, and then the machine was started to obtain the wet film). After the solvent was evaporated at room temperature, it was placed in an oven for heat crosslinking at 80 °C for 10 h to obtain the PDMS membrane.
[0064] The obtained ZIF-8 / PDMS membrane had a permeation flux of 1339 g m -2 h -1 -1
[0065] Preparation of eZIF-8 / PDMS mixed matrix membrane
[0066] (1): Preparation of eZIF-8: 0.3 g ZIF-8 powder was dispersed in 50 mL water, ultrasonic treatment, heated to 40℃, ready for use; 0.15 g tannic acid was dissolved in 50 mL water, stirred until the tannic acid was completely dissolved, to get 3 g / L tannic acid solution; 0.05 g sodium hydroxide was dissolved in 25 mL anhydrous ethanol, to get a concentration of 2 g / L sodium hydroxide solution. The tannic acid solution and sodium hydroxide solution were slowly poured into the ZIF-8 solution, stirred at 40℃ for 15 min, centrifuged and washed twice with ethanol, dried in an oven at 80℃ for 8h, and eZIF-8 powder was obtained.
[0067] (2): Preparation of eZIF-8 / PDMS mixed matrix membrane: 0.855 g PDMS was dissolved in 5 mL n-heptane; then 0.1283 g eZIF-8 was added, and stirring was continued for 5 h. 92 μL (0.0855 g) tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g dibutyltin dilaurate was added for catalytic reaction for 20 min, to obtain a casting solution; then the casting solution was poured onto a PVDF hydrophobic base membrane pretreated by soaking in 20 wt% ethanol aqueous solution for 2 h for blade coating experiment (the PVDF membrane was fixed on the surface of the blade coating machine in advance, and the thickness of the blade was set to 50 μm, and the blade coating speed was 40 mm / s. After the casting solution was poured onto the surface of the PVDF membrane in front of the blade, the machine was started to obtain a wet membrane). After the solvent evaporated at room temperature, an eZIF-8 / PDMS mixed matrix membrane was obtained.
[0068] The obtained eZIF-8 / PDMS membrane had a permeation flux of 3905 g m-2h-1 for 1 wt% butanol / water at 40℃, a flow rate of 180 mL / min, and a vacuum degree of less than 200 Pa, and a separation factor of 30.5. -2 h -1
[0069] Preparation of eZIF-8@PANI / PDMS mixed matrix membrane
[0070] (1): Preparation of eZIF-8: 0.3 g ZIF-8 powder was dispersed in 50 mL water, ultrasonic treatment, heated to 40 °C, ready for use; 0.15 g tannic acid was dissolved in 50 mL water, stirred until the tannic acid was completely dissolved, to obtain a 3 g / L tannic acid solution; 0.05 g sodium hydroxide was dissolved in 25 mL anhydrous ethanol to obtain a 2 g / L sodium hydroxide solution. The tannic acid solution and sodium hydroxide solution were slowly poured into the ZIF-8 solution, stirred at 40 °C for 15 min, centrifuged after the reaction, washed twice with ethanol, dried in an oven at 80 °C for 8 h, and dried to obtain eZIF-8 powder.
[0071] (2): Preparation of eZIF-8@PANI: 0.1 g polyaniline sheet was weighed and added to 100 mL anhydrous ethanol, ultrasonic stirring for 30 min, and the uniform dispersion was collected for 24 h, marked as solution A; 0.05 g eZIF-8 was weighed and added to 100 mL anhydrous ethanol, ultrasonic dispersion for 30 min, marked as solution B. Then solution B was poured into A, stirred for 1.5 h, then centrifuged (10000 rpm, 8 min), washed twice with ethanol, and dried to obtain eZIF-8@PANI.
[0072] (3): Preparation of eZIF-8@PANI / PDMS mixed matrix membrane: 0.855 g PDMS was dissolved in 5 mL n-heptane; then 0.1283 g eZIF-8@PANI was added, and stirring was continued for 5 h. 92 μL (0.0855 g) tetraethyl orthosilicate was added for crosslinking for 20 min, and 0.0086 g dibutyltin dilaurate was added for catalytic reaction for 20 min to obtain a casting solution; then the casting solution was poured onto a PVDF hydrophobic base membrane pretreated by soaking in a 20 wt% ethanol aqueous solution for 2 h for blade coating experiments (the PVDF membrane was fixed on the surface of the blade coater in advance, and the thickness of the blade was set to 50 μm, and the blade coating rate was 40 mm / s. After the casting solution was poured onto the surface of the PVDF membrane in front of the blade, the machine was started to obtain a wet membrane). After the solvent evaporated at room temperature, the eZIF-8@PANI / PDMS mixed matrix membrane was obtained.
[0073] The obtained eZIF-8@PANI / PDMS membrane had a permeation flux of 3219 g m -2 h -1 -1 of 1 wt% butanol / water under the conditions of 40 °C, flow rate 400 mL / min, and vacuum degree less than 200 Pa, and a separation factor of 47.9. The addition of PANI sheet improved the hydrophobicity of the filler and the membrane; but it also increased the permeation resistance of the molecules in the membrane to some extent.
Claims
1. A ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film, characterized in that, The hybrid matrix membrane is prepared by the following method: (1) Disperse ZIF-8 powder in a solvent, sonicate, heat to 20-70 °C, add 0.5-4 g / L tannic acid solution and catalyst, stir at 30-70 °C for 10-30 min, centrifuge to collect the precipitate after the reaction, wash with ethanol, and dry to obtain eZIF-8 powder; the catalyst is one or more of hydrochloric acid, sodium hydroxide or potassium iodide; the mass ratio of tannic acid, ZIF-8 powder and catalyst in the tannic acid solution is 1:1-3:0.1-3; (2) Add polyaniline sheets to anhydrous ethanol A, sonicate and stir, collect the uniform dispersion in the upper layer to obtain solution A; add the eZIF-8 powder from step (1) to anhydrous ethanol B, sonicate and stir to obtain solution B; mix solution B with solution A, stir and react for 0.5-6 h, centrifuge to collect the precipitate, wash with ethanol and dry to obtain eZIF-8@PANI; the mass ratio of polyaniline sheets to eZIF-8 powder is 10:1-20; (3) Dissolve polydimethylsiloxane in a non-polar solvent, stir to dissolve, add the eZIF-8@PANI obtained in step (2), continue stirring for 3-8 h, mix evenly, add tetraethyl orthosilicate for crosslinking for 10-30 min, add dibutyltin dilaurate for catalytic reaction for 8-20 min, and obtain casting solution; pour the casting solution onto a hydrophobic substrate and perform a scraping experiment to obtain a wet film, and after the solvent in the casting solution in the wet film evaporates, obtain an eZIF-8@PANI / PDMS mixed matrix film; the mass ratio of polydimethylsiloxane, eZIF-8@PANI, tetraethyl orthosilicate and dibutyltin dilaurate is 100:5-20:5-15:1-3; (4) Dissolve γ-mercaptopropyltriethoxysilane in anhydrous ethanol and sonicate to obtain solution C. Immerse the eZIF-8@PANI / PDMS mixed matrix membrane described in step (3) in solution C and perform grafting reaction at 20-75℃ for 1-8 h. After drying at room temperature, perform thermal crosslinking at 60-120℃ for 6-12 h to obtain the ZIF-8 grafted polyaniline-doped PDMS mixed matrix membrane.
2. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, The solvent mentioned in step (1) is water, methanol, ethanol or DMF.
3. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, The volume of anhydrous ethanol A in step (2) is 500-2000 ml / g based on the mass of the polyaniline sheet.
4. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, The volume of anhydrous ethanol B in step (2) is 400-5000 ml / g based on the mass of eZIF-8.
5. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, The nonpolar solvent mentioned in step (3) is one or more of n-heptane, n-hexane, chloroform or toluene.
6. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, The hydrophobic bottom membrane mentioned in step (3) is one or more of polyvinylidene fluoride ultrafiltration membrane, polysulfone ultrafiltration membrane, or polytetrafluoroethylene ultrafiltration membrane.
7. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, The hydrophobic substrate described in step (3) is first pretreated by soaking and cleaning it in a 20wt% ethanol aqueous solution for 1-5 hours.
8. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, In step (3), the wet film thickness in the scraping experiment is 30-100 μm and the scraping speed is 30-50 mm / s.
9. The ZIF-8 grafted polyaniline-doped PDMS hybrid matrix film as described in claim 1, characterized in that, The mass fraction of γ-mercaptopropyltriethoxysilane in solution C in step (4) is 1-4 wt%.
10. The application of the ZIF-8 grafted polyaniline-doped PDMS hybrid matrix membrane as described in claim 1 in butanol separation.