A kind of HOF-21@SA membrane based on amine regulation for organic solvent dehydration

Abstract

The patent relates to an amine-regulated HOF-21@SA membrane for organic solvent dehydration, and belongs to the field of pervaporation separation membranes. A step-by-step decoupling method is used to integrate coordination reaction and hydrogen bonding assembly, and a particle size controllable hydrogen-bonded organic framework (HOF-21) is prepared, and is uniformly blended with a hydrophilic sodium alginate (SA) substrate at a certain proportion to prepare a casting solution. With polyacrylonitrile (PAN) as a support material, the interface bonding strength of the separation layer and the support layer is regulated, and a dense composite membrane is prepared by spin coating. The suitable pore size of HOF-21 provides precise size screening effect, and improves the separation performance of the membrane for organic solvent / water; the small particle size HOF-21 nanoparticles obtained by amine regulation are well dispersed in the solvent, and have excellent compatibility with SA. The super-hydrophilic membrane prepared by the application has high separation performance, and has wide application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to an amine-regulated HOF-21@SA membrane for organic solvent dehydration, in particular to a mixed-matrix organic solvent dehydration membrane and application thereof in ethanol / water separation, and belongs to the technical field of membrane preparation. BACKGROUND

[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 level filtration, simple process and easy control. Compared with traditional azeotropic distillation and extractive distillation separation methods, pervaporation (PV) is a high-efficiency, 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 are attracting much attention due to their easy processing and adjustable permeation performance. 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 molecular transport between inorganic and organic.

[0003] Sodium alginate is a water-soluble natural polysaccharide with good film-forming property. The hydroxyl groups in the molecular chain have certain hydrophilicity, and it is one of 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 MOF and the like as fillers into SA to construct mixed-matrix membranes, which can effectively break the trade-off effect, but still face problems such as the inability to achieve high separation factor and high permeation flux, the low bonding strength between the separation layer and the support, and the reduced 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 MOF-801 prepared thereby is composed of Zr6O4(OH)4 secondary building units and fumaric acid organic linkers. Although it has good hydrothermal stability, it forms interconnected tetrahedra and octahedral cavities with a theoretical triangular window of 3.6 Å. In this space group, 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 the kinetic diameter of organic solvents (ethanol is 4.3 Å, isopropyl alcohol is 7.5 Å, and dimethyl carbonate is 7.1 Å). The separation range of organic solvent / water is limited, and the compatibility between MOF-801 and SA is poor, as verified by experiments. Therefore, it is necessary to select a nano-filler that has good compatibility with the SA matrix and a large size screening range.

[0004] Currently, hydrogen-bonded organic frameworks (HOFs) offer a new dimension and bright prospects for the development of multifunctional materials. They can be readily self-assembled from corresponding organic molecules with different functional sites, such as hydrogen bonds between carboxyl and amino groups and weak π··π interactions between aromatic groups to stabilize the framework. HOF materials are easy to process directly and have excellent biomolecular compatibility, making them materials with considerable potential for industrial and biomedical applications. HOF-21 is a material composed of [Cu2(ade)4(H2O)2]. 4+ (ade represents adenine) and SiF6 2− The porous material is assembled by anions through hydrogen bonding, and its crystal pore size is 3.6 Å.

[0005] This invention employs a stepwise decoupling approach to integrate coordination reactions and hydrogen bonding assembly, preparing a hydrogen-bonded organic framework (HOF-21) with controllable particle size. HOF-21 is then uniformly blended with a hydrophilic sodium alginate (SA) substrate in a specific ratio to prepare a casting solution. Using polyacrylonitrile (PAN) as the support material, and by controlling the interfacial bonding strength between the separation layer and the support, a dense composite membrane is obtained through spin coating. Summary of the Invention

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

[0007] To achieve the above objectives, the present invention provides the following technical solution: The amine-regulated HOF-21@SA membrane for organic solvent dehydration comprises a pretreated support and a separation layer. 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, wherein the filling amount of HOF-21 in the separation layer is 0.5~3.0 wt%.

[0008] This invention also provides a method for preparing an amine-regulated HOF-21@SA membrane for organic solvent dehydration, specifically including the following steps:

[0009] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of copper nitrate trihydrate and adenine were coordinated to form a Cu-ade complex, which was dissolved in 500 ml of a mixed solvent of acetonitrile and water in a ratio of 1:1. 0.076 mol of ammonium hexafluorosilicate and an appropriate amount of diethylamine were added and the mixture was stirred at room temperature. After the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles.

[0010] (2) Pretreatment of the support: soak the hydrophilic support in deionized water to remove impurities on the support; dissolve CT and PEI in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, and place the support PAN in the buffer solution for water bath oscillation at room temperature, then deposit on the surface of the PAN; clean the membrane with water and ethanol, then immerse the membrane in a KH560 aqueous solution for heating, cleaning, drying and preservation, to obtain a dense and super-hydrophilic PAN;

[0011] (3) Preparation of the composite membrane: weigh a certain mass fraction of HOF-21 nanoparticles prepared in step (1) and place in deionized water, and ultrasonic to form a uniform and stable dispersion liquid, then add sodium alginate powder, stir at room temperature until dissolved, and then take out after constant temperature standing and bubble removal; then spin-coat the sodium alginate solution after standing on the surface of the polyacrylonitrile ultrafiltration membrane support prepared in step (2); after drying, immerse in a calcium chloride solution for crosslinking, and then rinse with deionized water for 3 times; and then dry for use.

[0012] Preferably, the amount of diethylamine used in step (1) is 0.003-0.07 mol.

[0013] Preferably, the water bath oscillation speed in step (2) is 60-100 rpm, and the time is 30-50 min; the pretreated support is a hydrophilic membrane; and the thickness of the pretreated support is 50-400 μm.

[0014] Preferably, the concentration of the calcium chloride solution in step (3) is 0.2-0.7 M, and the immersion time is 10-30 min.

[0015] Preferably, the spin-coating of the sodium alginate solution in step (3) is performed by using a high-precision spin coater, and the spin-coating process is stepwise speed-up spin-coating for 60 s, and the time and speed sequence is 20 s-1000 r, 40 s-1300 r.

[0016] Preferably, according to the preparation method of claim 2, 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.

[0017] The application finally provides an application of the membrane of claim 1 in organic solvent dehydration, characterized in that the flux of the composite membrane is 1300 g·m -2 ·h -1 The separation factor is above 600 and has a certain stability.

[0018] Compared with the prior art, the present application has the beneficial effects that:

[0019] The hydrogen-bonded organic framework (HOF-21) with controllable particle size is prepared by gradually decoupling the coordination reaction and hydrogen bonding assembly with diethylamine. The small particle size HOF-21 nanoparticles prepared by amine regulation have a particle size range of 50-200 nm, are well dispersed in solvents, and have excellent compatibility with SA. The nanoparticle pore size of HOF-21 is 3.5 Å, and the kinetic diameter of water is 2.9 Å. The kinetic particle size of organic solvents (ethanol is 4.3 Å, isopropanol is 7.5 Å, and dimethyl carbonate is 7.1 Å) is larger. Therefore, the suitable pore size of HOF-21 provides an accurate size screening effect for organic solvent / water, thereby improving the separation performance of the membrane for organic solvent / water. The composite membrane with a dense separation layer and a porous support often faces 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 the structure and related performance of the membrane. By depositing catechol (CT) and polyethyleneimine (PEI) on the support and then grafting KH560, the bonding strength of the mixed matrix layer and the support can be improved. At the same time, after optimizing the double-layer interface, 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 application has high separation performance and wide application. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 : SEM surface image of HOF-21 nanoparticles in Example 3;

[0022] Figure 2 : (a) picture of pure sodium alginate casting solution and (b) picture of casting solution in Example 3;

[0023] Figure 3 : (a) PAN support, (b) pretreated PAN, (c) pure sodium alginate membrane, and (d) SEM surface image of mixed matrix membrane containing HOF-21. DETAILED DESCRIPTION

[0024] The present application will be further described below in combination with specific embodiments.

[0025] Example 1

[0026] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate was added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0027] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then deposited on the surface of PAN; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0028] (3) Preparation of composite membrane: 0.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and the solution was stirred at room temperature until dissolved, and then the bubbles were removed after constant temperature standing, and the solution was taken out for standby; then the sodium alginate solution after standing was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after drying, it was soaked in a 0.2 M calcium chloride solution for crosslinking for 15 min, and then washed with deionized water for 3 times; and then dried for standby.

[0029] The pore size of HOF-21 is 0.35 nm, and the particle size is 300 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 19.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a 90% mass fraction ethanol / water solution system, the temperature is 75 ℃, the vacuum degree is maintained at about 450 Pa during the reaction process, and the separation factor and flux are 1745 and 1600.4 g / (m 2 ·h) respectively, and after continuous use for 120 h, the separation factor and flux are 1746 and 1658.7 g / (m 2 ·h) respectively.

[0030] Example 2

[0031] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate and 0.004 mol of diethylamine were added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0032] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then the PAN surface was deposited; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0033] (3) Preparation of composite membrane: 1.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and the solution was stirred at room temperature until dissolved, and then the solution was taken out after standing for a while; then the standing sodium alginate solution was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer. After drying, it was immersed in a 0.2 M calcium chloride solution for crosslinking for 15 min, and then washed with deionized water for 3 times. Dry for standby.

[0034] The pore size of HOF-21 is 0.35 nm, and the particle size is 150 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 21 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a 90% mass fraction ethanol / water solution system, the temperature is 75°C, the vacuum degree is maintained at about 450 Pa during the reaction process, and the separation factor and flux are 2245 and 1900.7 g / (m 2 ·h) respectively, and after continuous use for 120 h, the separation factor and flux are 2205 and 1901.7 g / (m 2 ·h) respectively.

[0035] Example 3

[0036] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate and 0.005 mol of diethylamine were added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0037] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then the PAN surface was deposited; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0038] (3) Preparation of composite membrane: 2.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and the solution was stirred at room temperature until it was dissolved; after constant temperature standing and bubble removal, the sodium alginate solution was taken out for standby; then the sodium alginate solution after standing was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after drying, it was immersed in a 0.2 M calcium chloride solution for crosslinking for 15 min, and then washed with deionized water for 3 times; and then dried for standby.

[0039] The pore size of HOF-21 is 0.35 nm, and the particle size is 50 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 21 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a 90% mass fraction ethanol / water solution system, the temperature is 75°C, the vacuum degree is maintained at about 450 Pa during the reaction process, and the separation factor and flux are 2467 and 2000 g / (m 2 ·h), respectively. After continuous use for 120 h, the separation factor and flux are 2432 and 1980 g / (m 2 ·h), respectively.

[0040] Example 4

[0041] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate was added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0042] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then deposited on the surface of PAN; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0043] (3) Preparation of composite membrane: 0.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion liquid, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and the solution was stirred at room temperature until dissolved, and then the bubbles were removed after constant temperature standing, and the solution was taken out for standby; then the standing sodium alginate solution was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after air drying, crosslinking was carried out in 0.2 M calcium chloride solution for 15 min, and then washed with deionized water for 3 times; and air dried for standby.

[0044] The pore size of HOF-21 is 0.35 nm, and the particle size is 300 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 19.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a 90% mass fraction isopropyl alcohol / water solution system, the temperature is 60℃, the vacuum degree is maintained at about 450 Pa during the reaction process, and the separation factor and flux are 3345 and 1600.7 g / (m 2 ·h), respectively. After continuous use for 80 h, the separation factor and flux are 3245 and 1580.7 g / (m 2 ·h), respectively.

[0045] Example 5

[0046] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate and 0.004 mol of diethylamine were added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0047] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then the PAN surface was deposited; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0048] (3) Preparation of composite membrane: 1.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and the solution was stirred at room temperature until it was dissolved; after constant temperature standing and bubble removal, the standing sodium alginate solution was taken out for standby; then the sodium alginate solution was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after air drying, crosslinking was performed in a 0.2 M calcium chloride solution for 15 min, and then the membrane was washed with deionized water for 3 times; and the membrane was air dried for standby.

[0049] The pore size of HOF-21 is 0.35 nm, and the particle size is 150 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 20.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a 90% mass fraction isopropyl alcohol / water solution system, the temperature is 60°C, the vacuum degree is maintained at about 450 Pa during the reaction, and the separation factor and flux are 4500 and 1800.7 g / (m 2 ·h), respectively. After continuous use for 80 h, the separation factor and flux are 4359 and 1900.7 g / (m 2 ·h), respectively.

[0050] Example 6

[0051] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate and 0.005 mol of diethylamine were added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0052] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then deposited on the surface of PAN; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0053] (3) Preparation of composite membrane: 2.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and stirring was performed at room temperature until dissolution; after constant temperature standing and bubble removal, the standing sodium alginate solution was taken out for standby; then the sodium alginate solution was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after air drying, crosslinking was performed in a 0.2 M calcium chloride solution for 15 min, and then the membrane was washed with deionized water for 3 times; and the membrane was air dried for standby.

[0054] The pore size of HOF-21 is 0.35 nm, and the particle size is 50 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 20.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a 90% mass fraction isopropyl alcohol / water solution system, the temperature is 60°C, the vacuum degree is maintained at about 450 Pa during the reaction process, and the separation factor and flux are 3800 and 1500.7 g / (m 2 ·h), respectively. After continuous use for 80 h, the separation factor and flux are 3810 and 1501.2 g / (m 2 ·h), respectively.

[0055] Example 7

[0056] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate was added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0057] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then deposited on the surface of PAN; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0058] (3) Preparation of composite membrane: 0.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and the solution was stirred at room temperature until dissolved, and then the bubbles were removed after constant temperature standing, and the solution was taken out for standby; then the sodium alginate solution after standing was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after drying, it was soaked in a 0.2 M calcium chloride solution for crosslinking for 15 min, and then washed with deionized water for 3 times; and then dried for standby.

[0059] The pore size of HOF-21 is 0.35 nm, and the particle size is 300 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 19.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a dimethyl carbonate / water solution system with a mass fraction of 90%, the temperature is 15℃, the vacuum degree is maintained at about 450 Pa during the reaction process, and the separation factor and flux are 745 and 900.7 g / (m 2 ·h), respectively. After continuous use for 100 h, the separation factor and flux are 725 and 900.7 g / (m 2 ·h), respectively.

[0060] Example 8

[0061] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate and 0.004 mol of diethylamine were added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0062] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then deposited on the surface of PAN; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 solution with a certain mass fraction and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN;

[0063] (3) Preparation of composite membrane: 1.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion liquid, sodium alginate powder was added, the sodium alginate solution had a mass concentration of 3%, and was stirred at room temperature until dissolved; after constant temperature standing and bubble removal, the standing sodium alginate solution was taken out for standby; then the sodium alginate solution after standing was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after air drying, cross-linking was performed in 0.2 M calcium chloride solution for 15 min, and then washed with deionized water for 3 times; air dried for standby.

[0064] The pore size of HOF-21 was 0.35 nm, and the particle size was 150 nm. The thickness of the pretreated support was 50 μm. The selective layer thickness of HOF-21@SA membrane was 21.5 μm. The amine-regulated HOF-21@SA membrane prepared above was used for separating a dimethyl carbonate / water solution system with a mass fraction of 90%, the temperature was 15℃, the vacuum degree was maintained at about 450 Pa during the reaction process, and the separation factor and flux were 827 and 900 g / (m 2 ·h), respectively. After continuous use for 100 h, the separation factor and flux were 834 and 909.5 g / (m 2 ·h), respectively.

[0065] Example 9

[0066] (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine was dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate and 0.005 mol of diethylamine were added, and the reaction was stirred at room temperature; after the reaction was completed, the product was centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles;

[0067] (2) Pretreatment of support: the hydrophilic support was soaked in deionized water to remove impurities on the support; CT and PEI were dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN was placed in the buffer solution and subjected to water bath oscillation at room temperature, the water bath oscillation speed was 100 rpm, and the time was 45 min, and then deposited on the surface of PAN; the membrane was washed with water and ethanol, and then the membrane was immersed in a KH560 aqueous solution and heated, and the membrane was washed, dried and stored to obtain a dense super-hydrophilic PAN.

[0068] (3) Preparation of composite membrane: 2.5 wt% of HOF-21 powder prepared in step (1) was weighed and placed in deionized water, weighed, ultrasonically treated to form a uniform and stable dispersion, sodium alginate powder was added, the mass concentration of the sodium alginate solution was 3%, and stirring was performed at room temperature until dissolution; after constant temperature standing and bubble removal, the standing sodium alginate solution was taken out for standby; then the standing sodium alginate solution was spin-coated on the surface of the polyacrylonitrile ultrafiltration membrane support pretreated in step (2) fixed on a silicon wafer; after air drying, crosslinking was performed in a 0.2 M calcium chloride solution for 15 min, and deionized water was used for washing 3 times; air dry for standby.

[0069] The pore size of HOF-21 is 0.35 nm, and the particle size is 50 nm. The thickness of the pretreated support is 50 μm. The selective layer thickness of HOF-21@SA membrane is 21.5 μm. The amine-regulated HOF-21@SA membrane prepared above is used for separating a dimethyl carbonate / water solution system with a mass fraction of 90%, the temperature is 15℃, the vacuum degree is maintained at about 450 Pa during the reaction process, and the separation factor and flux are 627 and 769 g / (m 2 ·h), respectively. After continuous use for 100 h, the separation factor and flux are 627 and 759.8 g / (m 2 ·h), respectively.

Claims

1. An amine-regulated HOF-21@SA membrane for dehydration of organic solvents, characterized by, The composite membrane is composed of a pretreated support and a separation layer; the pretreated support is modified on the surface of polyacrylonitrile (PAN) by catechol (CT), polyethyleneimine (PEI) and KH560; the separation layer comprises a sodium alginate film-forming matrix and amine-regulated 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%; and the preparation method of the membrane specifically comprises the following steps: (1) Preparation of amine-regulated HOF-21 nanoparticles: 0.065 mol of Cu-ade complex formed by coordination of copper nitrate trihydrate and adenine is dissolved in 500 ml of mixed solvent of acetonitrile and water in a ratio of 1:1, 0.076 mol of ammonium hexafluorosilicate and an appropriate amount of diethylamine are added, and stirring reaction is carried out at room temperature; after the reaction is completed, the product is centrifuged, washed and dried to obtain amine-regulated HOF-21 nanoparticles; (2) Pretreatment of the support: the support PAN is soaked in deionized water to remove impurities on the support; CT and PEI are dissolved in a tris-hydroxymethyl aminomethane buffer solution with a pH value of 8.5, the support PAN is placed in the buffer solution and subjected to water bath oscillation at room temperature, and then deposited on the surface of PAN; the membrane is washed with water and ethanol, and then the membrane is put into a KH560 aqueous solution for heating, washing, drying and storage to obtain a dense super-hydrophilic PAN; (3) Preparation of the composite membrane: a certain amount of HOF-21 nanoparticles prepared in step (1) is weighed and placed in deionized water, ultrasonically treated until a uniform and stable dispersion liquid is formed, sodium alginate powder is added, the mass concentration of the sodium alginate solution is 3%, stirring is carried out at room temperature until the sodium alginate is dissolved, the solution is placed at constant temperature for bubble removal, and then taken out for standby; then the sodium alginate solution after standing is spin-coated on the surface of the pretreated support polyacrylonitrile ultrafiltration membrane fixed on a silicon wafer in step (2); after air-drying, cross-linking is carried out by immersing in a calcium chloride solution, and the membrane is washed with deionized water for 3 times; and then the membrane is air-dried for standby.

2. The film of claim 1, wherein In step (1), the amount of diethylamine is 0.003-0.07 mol.

3. The film of claim 1, wherein In step (2), the water bath oscillation speed is 60-100 rpm, and the time is 30-50 min; the thickness of the pretreated support is 50-400 μm.

4. The film of claim 1, wherein In step (3), the concentration of the calcium chloride solution is 0.2-0.7 M, and the immersion time is 10-30 min.

5. The film of claim 1, wherein In step (3), the spin-coating process of the sodium alginate solution is carried out by using a high-precision spin coater, and the spin-coating process is sub-section speed-increasing spin-coating for 60 s, and the time and speed sequence are 20 s-1000 r and 40 s-1300 r.

6. The film of claim 1, wherein In step (3), the amount of HOF-21 nanoparticles added is 0.5-3.0 wt%, and the thickness of the separation layer is 18-23 μm.

7. Use of the film according to claim 1 in the dehydration of organic solvents, characterized in that, The composite membrane has certain stability.

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