HOF-21 (at) SA membrane for dehydration of organic solvent based on amine regulation

Abstract

The invention relates to an amine regulation-based HOF-21 (at) SA membrane for dehydration of an organic solvent, and belongs to the field of pervaporation separation membranes. A coordination reaction and hydrogen bond assembly are integrated in a gradual decoupling mode, a hydrogen bond organic framework (HOF-21) with a controllable particle size is prepared, and the hydrogen bond organic framework (HOF-21) and a hydrophilic sodium alginate (SA) base material are uniformly blended according to a certain proportion to prepare a membrane casting solution. Polyacrylonitrile (PAN) is used as a supporting material, the interface bonding strength of the separation layer and the supporting layer is regulated and controlled, and the compact composite membrane is prepared through spin coating. The proper pore size of the HOF-21 provides a precise size screening effect, and the separation performance of the membrane on an organic solvent / water is improved; the small-particle-size HOF-21 nano-particles obtained through amine regulation and control are good in dispersion in a solvent and excellent in compatibility with SA. The super-hydrophilic membrane prepared by the invention has high separation performance and wide application prospect.

Description

Technical Field

[0001] The invention relates to a high-separation performance super-hydrophilic membrane, in particular to a mixed matrix organic solvent dehydration membrane and application thereof in ethanol / water separation, belonging to the technical field of membrane preparation. Background Art

[0002] Membrane separation technology has become one of the most important means in modern green separation science. It has the functions of separation, concentration, purification and refining, and has the characteristics of high efficiency, energy saving, environmental protection, molecular filtration, simple process and easy control. Compared with traditional separation methods such as azeotropic distillation and extractive distillation, pervaporation (PV) is an efficient, simple and environmentally friendly ethanol dehydration membrane technology. It can effectively separate azeotropes. PV membranes are generally divided into inorganic membranes, organic membranes and mixed matrix membranes. Mixed matrix membranes have attracted much attention due to their advantages such as easy processing and adjustable permeability. The separation performance of hybrid membranes is improved by designing polymers and inorganic fillers. In recent years, new membrane materials for organic dehydration have been developed to increase the molecular transport between inorganic and organic.

[0003] Sodium alginate is a water-soluble natural polysaccharide with good film-forming properties. The hydroxyl groups in the molecular chain have certain hydrophilicity and are the most commonly used pervaporation membrane materials. However, the selective adsorption capacity of hydroxyl groups for ethanol and water is poor, and the separation factor of the pervaporation membrane using pure SA as the separation layer is low. In recent years, many studies have introduced MOFs and other materials as fillers into SA to construct mixed matrix membranes, which has a good effect on breaking the "trade-off effect", but still face problems such as the inability to achieve high separation factors and permeation fluxes, and the low bonding strength between the separation layer and the support layer, which reduces the long-term stability of the membrane. For example: a mixed matrix pervaporation membrane and its application in methanol / dimethyl carbonate separation. Chinese invention application 202310513621.9, the three-dimensional framework of the prepared MOF-801 is composed of Zr6O4(OH)4 secondary building units and fumaric acid organic linkers. Although it has good hydrothermal stability, it forms interconnected tetrahedrons and octahedral cavities with a theoretical triangular window of 3.6 Å. In this space group, the two crystallographically independent tetrahedral cavities have slightly different sizes, with diameters of 5.6 Å and 4.8 Å, respectively. The kinetic diameter of water is 2.9 Å, and that of organic solvents (ethanol is 4.3 Å, isopropanol is 7.5 Å, and dimethyl carbonate is 7.1 Å) is limited in the separation of organic solvents / water. Experimental results show that MOF-801 has poor compatibility with SA. Therefore, it is necessary to select nanofillers that have good compatibility with the SA matrix and a large size screening range.

[0004] At present, hydrogen-bonded organic framework (HOF) materials provide a new dimension and bright prospects for the development of multifunctional materials. They can be easily self-assembled from corresponding organic molecules with different functional sites, such as hydrogen bonds between carboxyl and amine groups and weak π···π interactions of aromatic groups to stabilize the framework. HOF materials are easy to process directly and have excellent compatibility with biomolecules, making them a material with great potential for industrial and biomedical applications. HOF-21 is a kind of [Cu2(ade)4(H2O)2] 4+ (ade stands for adenine) and SiF6 2− The porous material is assembled by anions through hydrogen bonding forces, and its crystal pore diameter is 3.6 Å.

[0005] The present invention adopts a step-by-step decoupling method to integrate coordination reaction and hydrogen bond assembly to prepare a hydrogen bond organic framework (HOF-21) with controllable particle size, and uniformly blends HOF-21 with a hydrophilic sodium alginate (SA) substrate in a certain proportion to prepare a casting solution. With polyacrylonitrile (PAN) as the supporting material, the interface bonding strength between the separation layer and the supporting layer is regulated, and a dense composite membrane is obtained by spin coating. Summary of the invention

[0006] The technical problem to be solved by the present invention is to prepare an amine-regulated HOF-21@SA membrane for dehydration of organic solvents, and select HOF-21 with excellent hydrothermal stability and suitable pore size as filler to realize a pervaporation membrane for efficient separation of organic solvents / water.

[0007] In order to achieve the above object, the present invention provides the following technical solution: the pervaporation membrane comprises a pretreated support and a separation layer for pervaporation separation. The pretreated support is formed by modifying the surface of polyacrylonitrile (PAN) with catechol (CT), polyethyleneimine (PEI) and KH560. The separation layer comprises a sodium alginate film-forming matrix and HOF-21 doped in the sodium alginate film-forming matrix, and the filling amount of the HOF-21 in the separation layer is 0.5-3.0 wt%.

[0008] The present invention also provides a method for preparing an amine-regulated HOF-21@SA membrane for dehydration of an organic solvent, the method comprising the following steps: (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, add appropriate amount of diethylamine, and stir at room temperature. Centrifuge, wash, and dry to obtain HOF-21 nanoparticles for use.

[0009] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and shake it in a water bath at room temperature, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution and heat it, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0010] (3) Preparation of composite membrane: Weigh a certain mass fraction of the HOF-21 nanoparticles prepared in step (1) and place them in deionized water. Ultrasonicate until they are miscible with water to obtain a dispersion. Add sodium alginate powder with a mass concentration of 3%. Stir at room temperature until dissolved. Let stand at a constant temperature to remove bubbles, then take out for use. Then spin-coat the sodium alginate solution after standing on the surface of the pre-treated support polyacrylonitrile ultrafiltration membrane fixed on the silicon wafer in step (2). After drying, soak in calcium chloride solution for cross-linking and rinse with deionized water 3 times. Preferably, the amount of diethylamine used in step (1) is 0.003-0.07 mol.

[0011] Preferably, the water bath oscillation speed in step (2) is 60-100 rpm, and the time is 30-50 min; the pretreated support layer is a hydrophilic membrane; and the thickness of the pretreated support layer is 50-400 μm.

[0012] Preferably, the concentration of the calcium chloride solution in step (3) is 0.2-0.7 M, and the soaking time is 10-30 min.

[0013] Preferably, in step (3), a high-precision coating apparatus is used to spin-coat the casting solution, and the spin-coating process is performed by step-by-step speed increase for 60 s, wherein the time and speed sequence is 20 s-1000 r and 40 s-1300 r.

[0014] Preferably, the high-performance pervaporation ethanol dehydration composite membrane according to claim 1 is characterized in that the amount of HOF-21 nanoparticles added in step (3) is 0.5-3.0 wt%, and the thickness of the selective layer is 18-23 μm.

[0015] Finally, the present invention provides an application of the HOF-21@SA mixed matrix pervaporation membrane obtained by the preparation method according to claim 1 in separating organic solvents / water, wherein water permeates the pervaporation membrane and the organic solvent is retained. The particle size of the HOF-21 obtained by the preparation method is in the range of 50-200 nm and the pore size is 3.5 Å. The water contact angle of the organic solvent dehydration superhydrophilic membrane is 16.1° and the permeation flux is 2200 kg·m -2 ·h -1 , the separation factor was 2467, and after 120 h of continuous use, the permeate flux was 2100 kg·m -2 ·h -1 , the separation factor is 2325.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The coordination reaction and hydrogen bond assembly were integrated by diethylamine stepwise decoupling to prepare a hydrogen bond organic framework (HOF-21) with controllable particle size. The small-sized HOF-21 nanoparticles prepared by amine regulation had a particle size range of 50~200 nm, were well dispersed in the solvent, and had excellent compatibility with SA. The pore size of HOF-21 nanoparticles was 3.5 Å, the kinetic diameter of water was 2.9 Å, and the kinetic particle size of organic solvents (ethanol was 4.3 Å, isopropanol was 7.5 Å, and dimethyl carbonate was 7.1 Å) was larger. Therefore, the appropriate pore size of HOF-21 provided a precise size screening effect for organic solvents / water, thereby improving the separation performance of the membrane for organic solvents / water. Composite membranes with a dense separation layer and a porous support layer usually face the challenge of low bonding strength between the two layers, resulting in low long-term stability of the membrane. Reasonable treatment of defects between the two layers is the key to optimizing membrane structure and related properties. By depositing catechol (CT) and polyethyleneimine (PEI) on the support layer and then grafting KH560, the bonding strength between the mixed matrix layer and the support layer can be improved. At the same time, after the double-layer interface is optimized, the free volume performance and anti-swelling performance of the membrane are optimized, and the long-term stability is improved. The super-hydrophilic membrane prepared by the present invention has high separation performance and has a wide range of uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 : SEM surface image of HOF-21 nanoparticles in Example 3; Figure 2 : (a) pure sodium alginate casting solution and (b) images of the casting solution in Example 3; Figure 3 : SEM surface images of (a) PAN support, (b) pretreated PAN, (c) pure sodium alginate membrane, and (d) mixed matrix membrane containing HOF-21; DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with specific embodiments. Example

[0020] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, and stirred at room temperature. The HOF-21 nanoparticles were centrifuged, washed, and dried for use.

[0021] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0022] (3) Preparation of composite membrane: Weigh 0.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to drain the bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0023] The pore size of HOF-21 is 0.35 nm and the particle size is 300 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 19.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a 90% ethanol / water solution system at a temperature of 75 °C. The vacuum degree is maintained at about 450 Pa during the reaction. The separation factor and flux are 1745 and 1600.4 g / (m 2 ·h), after 120 h of continuous use, the separation factor and flux were 1746 and 1658.7 g / (m 2 h). Example

[0024] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, 0.004 mol diethylamine was added, and stirred at room temperature. The HOF-21 nanoparticles were obtained by centrifugation, washing, and drying for use.

[0025] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0026] (3) Preparation of composite membrane: Weigh 1.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to remove bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0027] The pore size of HOF-21 is 0.35 nm and the particle size is 150 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 21 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a 90% ethanol / water solution system at a temperature of 75°C. During the reaction, the vacuum degree is maintained at about 450Pa. The separation factor and flux are 2245 and 1900.7 g / (m 2 ·h), after 120h of continuous use, the separation factor and flux were 2205 and 1901.7 g / (m 2 h). Example

[0028] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, 0.005 mol diethylamine was added, and stirred at room temperature. The HOF-21 nanoparticles were obtained by centrifugation, washing, and drying for use.

[0029] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0030] (3) Preparation of composite membrane: Weigh 2.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to drain the bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0031] The pore size of HOF-21 is 0.35 nm and the particle size is 50 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 21 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a 90% ethanol / water solution system at a temperature of 75°C. During the reaction, the vacuum degree is maintained at about 450 Pa. The separation factor and flux are 2467 and 2000 g / (m 2 After 120 h of continuous use, the separation factor and flux were 2432 and 1980 g / (m 2 h). Example

[0032] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, and stirred at room temperature. The HOF-21 nanoparticles were centrifuged, washed, and dried for use.

[0033] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0034] (3) Preparation of composite membrane: Weigh 0.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to drain the bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0035] The pore size of HOF-21 is 0.35 nm and the particle size is 300 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 19.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a 90% isopropanol / water solution system at a temperature of 60°C. The vacuum degree is maintained at about 450 Pa during the reaction. The separation factor and flux are 3345 and 1600.7 g / (m 2 After 80 h of continuous use, the separation factor and flux were 3245 and 1580.7 g / (m 2 h). Example

[0036] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, 0.004 mol diethylamine was added, and stirred at room temperature. The HOF-21 nanoparticles were obtained by centrifugation, washing, and drying for use.

[0037] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0038] (3) Preparation of composite membrane: Weigh 1.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to remove bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0039] The pore size of HOF-21 is 0.35 nm and the particle size is 150 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 20.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a 90% isopropanol / water solution system at a temperature of 60°C. The vacuum degree is maintained at about 450 Pa during the reaction. The separation factor and flux are 4500 and 1800 .7 g / (m 2 After 80 h of continuous use, the separation factor and flux were 4359 and 1900.7 g / (m 2 h). Example

[0040] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, 0.005 mol diethylamine was added, and stirred at room temperature. The HOF-21 nanoparticles were obtained by centrifugation, washing, and drying for use.

[0041] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0042] (3) Preparation of composite membrane: Weigh 2.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to drain the bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0043] The pore size of HOF-21 is 0.35 nm and the particle size is 50 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 20.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a 90% isopropanol / water solution system at a temperature of 60°C. The vacuum degree is maintained at about 450Pa during the reaction. The separation factor and flux are 3800 and 1500.7 g / (m 2 After 80 h of continuous use, the separation factor and flux were 3810 and 1501.2 g / (m 2 h). Example

[0044] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, and stirred at room temperature. The HOF-21 nanoparticles were centrifuged, washed, and dried for use.

[0045] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0046] (3) Preparation of composite membrane: Weigh 0.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to drain the bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0047] The pore size of HOF-21 is 0.35 nm and the particle size is 300 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 19.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a dimethyl carbonate / water solution system with a mass fraction of 90%. The temperature is 15°C. The vacuum degree is maintained at about 450 Pa during the reaction. The separation factor and flux are 745 and 900.7 g / (m 2 After 100 h of continuous use, the separation factor and flux were 725 and 900.7 g / (m 2 h). Example

[0048] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, 0.004 mol diethylamine was added, and stirred at room temperature. The HOF-21 nanoparticles were obtained by centrifugation, washing, and drying for use.

[0049] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0050] (3) Preparation of composite membrane: Weigh 1.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to remove bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0051] The pore size of HOF-21 is 0.35 nm and the particle size is 150 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 21.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a dimethyl carbonate / water solution system with a mass fraction of 90%. The temperature is 15°C. The vacuum degree is maintained at about 450 Pa during the reaction. The separation factor and flux are 827 and 900 g / (m 2 After 100 h of continuous use, the separation factor and flux were 834 and 909.5 g / (m 2 h). Example

[0052] (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method was used to integrate coordination reaction and hydrogen-bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, 0.005 mol diethylamine was added, and stirred at room temperature. The HOF-21 nanoparticles were obtained by centrifugation, washing, and drying for use.

[0053] (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and oscillate in a water bath at room temperature, with a water bath oscillation speed of 100 rpm for 45 min, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then put the membrane into a certain mass fraction of KH560 solution for heating, wash the membrane, dry it and store it, and obtain a dense super-hydrophilic PAN.

[0054] (3) Preparation of composite membrane: Weigh 2.5 wt% of the HOF-21 powder reserved in step (1) and place it in deionized water, weigh it, and ultrasonicate it until it can be miscible with water to obtain a dispersion, add sodium alginate powder, the mass concentration of the sodium alginate solution is 3%, stir it at room temperature until it dissolves, let it stand at a constant temperature to drain the bubbles, and then take it out for use; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in 0.2 M calcium chloride solution for cross-linking for 15 minutes, and rinse it with deionized water 3 times. Dry it for use.

[0055] The pore size of HOF-21 is 0.35 nm and the particle size is 50 nm. The thickness of the support layer after pretreatment is 50 μm. The thickness of the HOF-21@SA membrane selection layer is 21.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used to separate a dimethyl carbonate / water solution system with a mass fraction of 90%. The temperature is 15°C. The vacuum degree is maintained at about 450 Pa during the reaction. The separation factor and flux are 627 and 769 g / (m 2 After 100 h of continuous use, the separation factor and flux were 627 and 759.8 g / (m 2 h).

Claims

1. A HOF-21@SA membrane based on amine regulation for dehydration of organic solvents, characterized in that: The pervaporation membrane includes a pretreated support and a separation layer for pervaporation separation. The pretreated support is formed by modifying the surface of polyacrylonitrile (PAN) with catechol (CT), polyethyleneimine (PEI) and KH560. The separation layer includes a sodium alginate film-forming matrix and HOF-21 doped in the sodium alginate film-forming matrix, and the filling amount of HOF-21 in the separation layer is 0.5-3.0 wt%; the preparation method includes the following steps: (1) Preparation of hydrogen-bonded organic framework (HOF) nanoparticles: A step-by-step decoupling method is used to integrate coordination reaction and hydrogen bond assembly to replace the traditional layered method to prepare HOF-21 nanomaterials. The substances involved in the amine-regulated HOF-21 synthesis step are as follows: 500 ml acetonitrile / water (1:1), 0.065 mol Cu-ade solution containing copper nitrate trihydrate and adenine, 0.076 mol ammonium hexafluorosilicate, add appropriate amount of diethylamine, and stir at room temperature. Centrifuge, wash and dry to obtain HOF-21 nanoparticles for use; (2) Pretreatment of the support layer: Soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in tris(hydroxymethyl)aminomethane buffer solution (PH=8.5), place the support PAN in the buffer solution and shake it in a water bath at room temperature, and then deposit it on the PAN surface. Wash the membrane with water and ethanol, then heat it in a certain mass fraction of KH560 solution, wash the membrane, dry it, and store it to obtain a dense super-hydrophilic PAN; (3) Preparation of composite membrane: Weigh a certain mass fraction of the HOF-21 nanoparticles reserved in step (1) and place them in deionized water. Ultrasonicate until they are miscible with water to obtain a dispersion. Add sodium alginate powder with a mass concentration of 3%. Stir at room temperature until dissolved. Let it stand at a constant temperature to remove bubbles, then take it out for use. Then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane that has been pretreated in step (2) fixed on the silicon wafer. After drying, soak it in a calcium chloride solution for cross-linking, and rinse it with deionized water 3 times. Let it dry for use.

2. According to claim 1, it is characterized in that The amount of diethylamine used in step (1) is 0.003-0.07 mol.

3. According to claim 1, it is characterized in that In step (2), the water bath oscillation speed is 60-100 rpm for 30-50 min; the pretreated support layer is a hydrophilic membrane; and the thickness of the pretreated support layer is 50-400 μm.

4. The method according to claim 1, characterized in that The concentration of the calcium chloride solution in step (3) is 0.2-0.7M, and the immersion time is 10-30 min.

5. The method according to claim 1, characterized in that In step (3), a high-precision coating apparatus is used to spin-coat the casting solution. The spin-coating process is performed by step-by-step speed increase for 60 s, and the time and speed sequence is 20 s-1000 r and 40 s-1300 r.

6. The high performance pervaporation ethanol dehydration composite membrane according to claim 1, characterized in that In step (3), the amount of HOF-21 nanoparticles added is 0.5-3.0 wt%, and the thickness of the selective layer is 18-23 μm.

7. An application of the HOF-21@SA mixed matrix pervaporation membrane obtained by the preparation method according to claim 1 in separating organic solvents / water, characterized in that: Water permeates the pervaporation membrane and the organic solvent is retained.

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