A sulfonic acid covalent organic framework-amide composite membrane and its preparation and application

Abstract

The present invention relates to a sulfonic acid covalent organic framework-amide composite membrane and its preparation and application. A substrate material is impregnated with a 1,3,5-trimesoyl chloride (TMC) solution, then immersed in a mixed solution of tris(2-aminoethyl)amine (TREN) and sulfonic acid COF nanosheets, reacted, and dried to obtain the sulfonic acid covalent organic framework-amide composite membrane. The sulfonic acid covalent organic framework-amide composite membrane is synthesized using an interfacial polymerization method, which is simple to operate. The resulting membrane material exhibits excellent separation performance and has promising application prospects in pervaporation ethanol dehydration and the separation and purification of other miscible azeotropic mixtures.

Description

Technical Field

[0001] The present invention belongs to the field of functional membranes, and in particular relates to a sulfonic acid covalent organic framework-amide composite membrane and a preparation method and application thereof. Background Art

[0002] Membrane separation technology, characterized by high energy efficiency, low carbon emissions, and extensive design flexibility, has become an effective and sustainable technology for alleviating global water shortages, environmental remediation, and resource recovery. The key to membrane separation technology lies in the selection of membrane materials. High-performance membrane materials should exhibit high rejection rates, high permeability, and long-term operational stability under harsh real-world conditions.

[0003] Covalent organic frameworks (COFs) are a class of crystalline porous polymers constructed from organic building blocks through covalent bonds. They exist in two- or three-dimensional structures. Two-dimensional COFs, in particular, have become promising membrane separation materials due to their inherent porosity, uniform pores, tunable pore size, and excellent chemical stability. Covalent organic framework membranes with tunable, ordered channels and free organic groups hold great promise for molecular separations due to the synergistic effects of their physical and chemical microenvironments.

[0004] The intrinsic pore size of COFs is mostly 1-2 nm, which belongs to the micropore range. For miscible azeotropic mixtures (such as water / alcohol, alcohol / ether, ester / alkanes, etc.), relying solely on COFs pores is not sufficient to achieve effective separation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a sulfonic acid covalent organic framework-amide composite membrane and its preparation and application.

[0006] The present invention provides a method for preparing a sulfonic acid covalent organic framework-amide composite membrane, comprising:

[0007] The substrate material is immersed in a 1,3,5-trimethylenediamine (TMC) solution and then immersed in a mixed solution of tris(2-aminoethyl)amine (TREN) and sulfonic acid group COF nanosheets, reacted, and dried to obtain a sulfonic acid group covalent organic framework-amide composite membrane.

[0008] Furthermore, the base material includes a polyacrylonitrile film.

[0009] Preferably, the solvent of the TMC solution includes chloroform; and the concentration of the TMC solution is 0.1-3 wt%.

[0010] Preferably, the mixed solution of TREN and sulfonic acid COF nanosheets: sulfonic acid COF nanosheet aqueous dispersion and TREN solution are mixed and stirred; wherein the concentration of the TREN solution is 1-10 mg mL -1.

[0011] Furthermore, the mixed solution of tris(2-aminoethyl)amine TREN and sulfonic acid COF nanosheets comprises: taking a TpSO3H-CON aqueous dispersion and preparing a TREN solution, adjusting the pH to 7-8; mixing the TpSO3H-CON dispersion and the TREN solution, and stirring for 3-5 hours; wherein the concentration of the prepared TREN solution is 1-10 mg mL -1 ; The volume ratio of TpSO3H-CON aqueous dispersion and TREN solution is 2:1.

[0012] Furthermore, the sulfonic acid COF nanosheets are prepared by interfacial polymerization using an aqueous solution containing 2,5-diaminobenzenesulfonic acid, 1,3,5-trialdehyde phloroglucinol, and n-octanoic acid as raw materials to obtain the sulfonic acid COF nanosheets Tp-SO3H-CON.

[0013] The preparation of the sulfonic acid COF nanosheets includes: using an aqueous solution of 2,5-diaminobenzenesulfonic acid as the aqueous phase, mixing 1,3,5-trialdehyde phloroglucinol and n-octanoic acid, adding the mixture to the aqueous phase as the upper layer after ultrasonication, and reacting at room temperature for 24-72 hours (with the consumption of amine monomers and the growth of TpSO3H-CON in the bottom aqueous phase, the color of the aqueous phase solution gradually changes from purple to deep red). After the reaction, the two phases are separated and dialyzed to obtain the sulfonic acid COF nanosheets Tp-SO3H-CON.

[0014] The solvent water in the aqueous solution of 2,5-diaminobenzenesulfonic acid is ultrapure water; the ultrasonic time is 25-35 minutes; the dialysis treatment is 12-24 hours, and the molecular weight of the dialysis bag is 1000 Da.

[0015] The volume ratio of the solvent ultrapure water and n-octanoic acid in the aqueous solution of 2,5-diaminobenzenesulfonic acid is 100-150:50-100.

[0016] The molar ratio of the 2,5-diaminobenzenesulfonic acid to 1,3,5-trialdehyde phloroglucinol is (2.8-3.2):2.

[0017] The substrate material is immersed in the 1,3,5-trimesoyl chloride TMC solution for 5-15 minutes.

[0018] The reaction time is 3-6 minutes.

[0019] The drying is performed at 35-45°C.

[0020] The invention provides a sulfonic acid covalent organic framework-amide composite membrane prepared by the method.

[0021] The present invention provides an application of the sulfonic acid covalent organic framework-amide composite membrane in pervaporation and separation and purification of miscible azeotropic mixtures, such as pervaporation ethanol dehydration.

[0022] This invention uses a secondary interfacial polymerization method to prepare a sulfonic acid covalent organic framework-amide composite membrane ((SO3H)CON-TNC). The resulting (SO3H)CON-TNC membrane exhibits excellent pervaporation performance and maintains good stability during long-term operation. Compared to other membrane materials, this method is simple to operate. The resulting "secondary interfacial" assembly method for (SO3H)CON-TNC membranes has promising applications in pervaporation ethanol dehydration and other applications.

[0023] Beneficial effects

[0024] The present invention adopts "secondary interface" assembly to prepare the synthesis of sulfonic acid covalent organic framework-amide composite membrane. The method is simple to operate and has good long-term operation stability. It has good application prospects in pervaporation ethanol dehydration and separation and purification of other miscible azeotropic mixtures.

[0025] This invention provides a method for synthesizing a sulfonic acid covalent organic framework-amide composite membrane for pervaporation and explores the differences in the performance of the resulting sulfonic acid covalent organic framework-amide composite membrane under different reaction conditions. The method is simple to operate, and the resulting sulfonic acid covalent organic framework-amide composite membrane has a wide range of applications, including promising applications in pervaporation ethanol dehydration and the separation and purification of other miscible azeotropic mixtures.

[0026] The present invention proposes a covalent organic framework-amide composite membrane for pervaporation manufactured using a primary interface plus secondary interface polymerization strategy. The prepared sulfonic acid covalent organic framework-amide composite membrane has a high water permeation flux and can perform efficient pervaporation alcohol-water separation, thereby achieving more low-energy and efficient ethanol separation and purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : The Fourier transform infrared spectra of Tp-SO3H nanosheets and TNC films obtained in the examples;

[0028] Figure 2 : is the Fourier transform infrared spectrum of the (SO3H) CON-TNC film obtained in Example;

[0029] Figure 3 This is the powder C13 NMR spectrum of the Tp-SO3H nanosheet film obtained in the example;

[0030] Figure 4 is the X-ray diffraction spectrum of Tp-SO3H nanosheets obtained in the embodiment;

[0031] Figure 5 is the X-ray diffraction spectrum of the (SO3H) CON-TNC film obtained in Example;

[0032] Figure 6 is the X-ray photoelectron spectrum of the (SO3H) CON-TNC film obtained in Example;

[0033] Figure 7 This is the thermogravimetric analysis diagram of the (SO3H) CON-TNC film obtained in the example;

[0034] Figure 8 The pervaporation water permeation of the TNC membrane and (SO3H)CON-TNC membrane obtained in the examples and the corresponding water / ethanol separation factors;

[0035] Figure 9 The pervaporation water permeation of the TNC membrane and (SO3H)CON-TNC membrane obtained in the examples at different temperatures and the corresponding water / ethanol separation factors. DETAILED DESCRIPTION

[0036] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0037] Example 1

[0038] The preparation of Tp-SO3H nanosheets involves the following steps: 2,5-Diaminobenzenesulfonic acid (DABA, 141 mg, 0.75 mmol) was dissolved in 150 mL of ultrapure water and poured into a beaker as the aqueous phase. TFP (105 mg, 0.50 mmol) was dissolved in 100 mL of n-octanoic acid and sonicated for 30 minutes. The mixture was then slowly added to the beaker as the top layer. The reaction was allowed to proceed at room temperature for 72 hours. As the amine monomers were consumed and TpSO3H-CON formed in the bottom aqueous phase, the color of the aqueous phase gradually changed from purple to deep red. After the reaction, the two phases were separated, and the TpSO3H-CON aqueous phase was dialyzed against ultrapure water for 24 hours (dialysis bag with a molecular weight of 1000 Da). This yielded Tp-SO3H nanosheets, designated TpSO3H-CON.

[0039] The Fourier transform infrared spectrum of TpSO3H-CON obtained in this example is as follows Figure 1 As shown in the FT-IR spectrum of the covalent organic framework, the -1The characteristic stretching vibration absorption peak of C-N bond appears at 1575 cm -1 The characteristic stretching vibration absorption peak of the C=C bond appears at , indicating the successful synthesis of the covalent organic framework membrane and the occurrence of enol-keto structural interconversion.

[0040] The NMR spectrum of TpSO3H-CON obtained in this example is as follows Figure 3 As shown, the characteristic peaks at 185, 147, and 105 ppm correspond to the carbon atom chemical shifts of ketone (-C=O), ketoamide (-C-NH-), and exocyclic carbon (C=C), respectively, indicating the successful synthesis of the covalent organic framework membrane and the generation of enol-keto structural interconversion.

[0041] The powder X-ray diffraction pattern of TpSO3H-CON obtained in this example is as follows Figure 4 As shown in the figure, the XRD spectrum of TpSO3H-CON shows obvious diffraction peaks at 2θ = 4.7° and 27.1°, corresponding to the (100) and (001) crystal planes, respectively. The XRD test results match well with the simulated image of the AA stacking of the covalent organic framework, indicating that the obtained covalent organic framework film has a high degree of crystallinity.

[0042] Example 2

[0043] The preparation of TNC polyamide membrane is as follows: prepare 0.15 wt% 1,3,5-benzene trimesoyl chloride (TMC) chloroform solution and 5 mmol mL-1 tris(2-aminoethyl)amine (TREN) aqueous solution. Then immerse the polyacrylonitrile support base membrane in 0.15 wt% TMC chloroform solution for 10 minutes and then remove it. Then immerse the polyacrylonitrile base membrane soaked in TMC solution in TREN aqueous solution. React for 5 minutes and transfer to a 40 ℃ oven to obtain a TNC membrane, which is denoted as TNC. The Fourier transform infrared spectrum of the TNC membrane obtained in this example is shown as follows: Figure 1 As shown, at 1266 cm -1 The characteristic stretching vibration absorption peak of -C-NH bond appears at 1643cm -1 The characteristic absorption peak at 2867 cm is the stretching vibration peak of the C=O bond. -1 The characteristic absorption peak is attributed to the stretching vibration of the -CH2 bond on the TREN monomer. The -NH2 bond of the TREN monomer (3380 cm -1 ) The stretching vibration absorption peak disappears, indicating that the acyl chloride and amino group undergo condensation reaction to form an amide bond.

[0044] Example 3

[0045] Preparation of (SO3H)CON-TNC membrane, the specific steps are as follows:

[0046] Prepare a mixed solution of TREN and TpSO3H-CON, take 10 mL of TpSO3H-CON aqueous dispersion; the prepared concentration is 1 mg mL -1 Then 10 mL of TpSO3H-CON aqueous dispersion and 5 mL of 1 mg mL -1 The TREN solutions were mixed and stirred for 5 hours.

[0047] The polyacrylonitrile support substrate membrane was immersed in a 0.15 wt% TMC chloroform solution for 10 minutes and then picked up. The polyacrylonitrile substrate membrane soaked in TMC solution was then immersed in a mixed solution of TREN and TpSO3H-CON. The membrane was reacted for 5 minutes and then transferred to a 40 °C oven for drying to obtain a (SO3H) CON-TNC membrane, which was recorded as (SO3H) CON-TNC-1.

[0048] The Fourier transform infrared spectrum of (SO3H) CON-TNC-1 obtained in this example is as follows Figure 2 As shown, at 1244 cm -1 and 1630 cm -1 The characteristic peaks are the stretching vibration absorption peaks of -C-NH- bond and C=O bond in TpSO3H-CON. -1 The stretching vibration absorption peak of -CH2 bond appears at 3067 cm -1 -NH3 appeared + The infrared absorption peak of the bond indicates that TpSO3H-CON is protonated with TREN and undergoes condensation reaction with acyl chloride.

[0049] The powder X-ray diffraction pattern of (SO3H) CON-TNC-1 obtained in this example is as follows Figure 5 As shown in Figure 3, obvious diffraction peaks appear at 2θ = 4.7° and 27.0°, corresponding to the (100) and (001) crystal planes, respectively. The XRD test results match well with the simulated image of AA stacking of the covalent organic framework, indicating that the obtained (SO3H) CON-TNC film has a high degree of crystallinity.

[0050] The X-ray photoelectron spectrum of (SO3H)CON-TNC-1 obtained in this example is shown in Figure 6. The N 1s photoelectron spectrum of (SO3H)CON-TNC-1 deconvoluted into two separate peaks at 399.6-399.8 eV and 401.6-401.7 eV, which were attributed to the amide N(-C-HN-) and the quaternary ammonium salt N + (-NH3 + ), indicating that TpSO3H-CON and TREN undergo protonation.

[0051] Example 4

[0052] The preparation of (SO3H) CON-TNC membrane was as follows: a mixed solution of TREN and TpSO3H-CON was prepared, 10 mL of TpSO3H-CON aqueous dispersion was taken; the concentration was 2 mg mL -1 10 mL of TpSO3H-CON aqueous dispersion and 5 mL of 2 mg mL -1 The TREN solution was mixed and stirred for 5 hours.

[0053] The polyacrylonitrile support substrate membrane was immersed in a 0.15 wt% TMC chloroform solution for 10 minutes and then picked up. The polyacrylonitrile substrate membrane soaked in TMC solution was then immersed in a mixed solution of TREN and TpSO3H-CON. The membrane was reacted for 5 minutes and then transferred to a 40 °C oven for drying to obtain a (SO3H) CON-TNC membrane, which was recorded as (SO3H) CON-TNC-2.

[0054] The Fourier transform infrared spectrum of (SO3H) CON-TNC-2 obtained in this example is as follows Figure 2 As shown, at 1244 cm -1 and 1630 cm -1 The characteristic peaks are the stretching vibration absorption peaks of -C-NH- bond and C=O bond in TpSO3H-CON. -1 The stretching vibration absorption peak of -CH2 bond appears at 3067 cm -1 -NH3 appeared + The infrared absorption peak of the bond indicates that TpSO3H-CON is protonated with TREN and undergoes condensation reaction with acyl chloride.

[0055] The powder X-ray diffraction pattern of (SO3H) CON-TNC-2 obtained in this example is as follows Figure 5 As shown in Figure 3, obvious diffraction peaks appear at 2θ = 4.7° and 27.0°, corresponding to the (100) and (001) crystal planes, respectively. The XRD test results match well with the simulated image of AA stacking of the covalent organic framework, indicating that the obtained (SO3H) CON-TNC film has a high degree of crystallinity.

[0056] The X-ray photoelectron spectrum of (SO3H)CON-TNC-2 obtained in this example is shown in Figure 6. The N 1s photoelectron spectrum of (SO3H)CON-TNC-1 is deconvoluted into two separate peaks at 399.6-399.8 eV and 401.6-401.7 eV, which are attributed to the amide N(-C-HN-) and the quaternary ammonium salt N + (-NH3 +), indicating that TpSO3H-CON and TREN undergo protonation.

[0057] Example 5

[0058] The (SO3H) CON-TNC membrane was prepared by preparing a mixed solution of TREN and TpSO3H-CON, taking 10 mL of TpSO3H-CON aqueous dispersion; -1 10 mL of TpSO3H-CON aqueous dispersion and 5 mL of 4 mg mL -1 The TREN solution was mixed and stirred for 5 hours.

[0059] The polyacrylonitrile support membrane was immersed in a 0.15 wt% TMC chloroform solution for 10 minutes and then removed. The TMC-soaked polyacrylonitrile membrane was then immersed in a mixed solution of TREN and TpSO₃H-CON. The membrane reacted for 5 minutes and then dried in a 40°C oven to produce the (SO₃H)CON-TNC membrane, designated (SO₃H)CON-TNC-3.

[0060] The Fourier transform infrared spectrum of (SO3H) CON-TNC-3 obtained in this example is as follows Figure 2 As shown, at 1244 cm -1 and 1630 cm -1 The characteristic peaks are the stretching vibration absorption peaks of -C-NH- bond and C=O bond in TpSO3H-CON. -1 The stretching vibration absorption peak of -CH2 bond appears at 3067 cm -1 -NH3 appeared + The infrared absorption peak of the bond indicates that TpSO3H-CON is protonated with TREN and undergoes condensation reaction with acyl chloride.

[0061] The powder X-ray diffraction pattern of (SO3H)CON-TNC-3 obtained in this example is as follows Figure 5 As shown in Figure 3, obvious diffraction peaks appear at 2θ = 4.7° and 27.0°, corresponding to the (100) and (001) crystal planes, respectively. The XRD test results match well with the simulated image of AA stacking of the covalent organic framework, indicating that the obtained (SO3H) CON-TNC film has a high degree of crystallinity.

[0062] The X-ray photoelectron spectrum of (SO3H)CON-TNC-3 obtained in this example is shown in Figure 6. The N 1s photoelectron spectrum of (SO3H)CON-TNC-1 deconvoluted into two separate peaks at 399.6-399.8 eV and 401.6-401.7 eV, which were attributed to the amide N(-C-HN-) and the quaternary ammonium salt N + (-NH3 + ), indicating that TpSO3H-CON and TREN undergo protonation.

[0063] Example 6

[0064] The (SO3H) CON-TNC membrane was prepared by preparing a mixed solution of TREN and TpSO3H-CON, taking 10 mL of TpSO3H-CON aqueous dispersion; and preparing a concentration of 6 mg mL -1 10 mL of TpSO3H-CON aqueous dispersion and 5 mL of 6 mg mL -1 The TREN solution was mixed and stirred for 5 hours.

[0065] The polyacrylonitrile support membrane was immersed in a 0.15 wt% TMC chloroform solution for 10 minutes and then removed. The TMC-soaked polyacrylonitrile membrane was then immersed in a mixed solution of TREN and TpSO₃H-CON. The membrane reacted for 5 minutes and then dried in a 40°C oven to produce the (SO₃H)CON-TNC membrane, designated (SO₃H)CON-TNC-4.

[0066] The Fourier transform infrared spectrum of (SO3H)CON-TNC-4 obtained in this example is shown in Figure 2. -1 and 1630 cm -1 The characteristic peaks are the stretching vibration absorption peaks of -C-NH- bond and C=O bond in TpSO3H-CON. -1 The stretching vibration absorption peak of -CH2 bond appears at 3067 cm -1 -NH3 appeared + The infrared absorption peak of the bond indicates that TpSO3H-CON is protonated with TREN and undergoes condensation reaction with acyl chloride.

[0067] The powder X-ray diffraction pattern of (SO3H)CON-TNC-4 obtained in this example is as follows Figure 5As shown in Figure 3, obvious diffraction peaks appear at 2θ = 4.7° and 27.0°, corresponding to the (100) and (001) crystal planes, respectively. The XRD test results match well with the simulated image of AA stacking of the covalent organic framework, indicating that the obtained (SO3H) CON-TNC film has a high degree of crystallinity.

[0068] The X-ray photoelectron spectrum of (SO3H)CON-TNC-4 obtained in this example is shown in Figure 6. The N 1s photoelectron spectrum of (SO3H)CON-TNC-1 deconvoluted into two separate peaks at 399.6-399.8 eV and 401.6-401.7 eV, which were attributed to the amide N(-C-HN-) and the quaternary ammonium salt N + (-NH3 + ), indicating that TpSO3H-CON and TREN undergo protonation.

[0069] Example 7

[0070] The preparation of (SO3H) CON-TNC membrane was as follows: prepare a mixed solution of TREN and TpSO3H-CON, take 10 mL of TpSO3H-CON aqueous dispersion; prepare a concentration of 10 mg mL -1 The TREN solution was adjusted to pH 7-8. 10 mL of TpSO3H-CON aqueous dispersion and 5 mL of 10 mg mL -1 The TREN solution was mixed and stirred for 5 hours.

[0071] The polyacrylonitrile support membrane was immersed in a 0.15 wt% TMC chloroform solution for 10 minutes and then removed. The TMC-soaked polyacrylonitrile membrane was then immersed in a mixed solution of TREN and TpSO₃H-CON. The membrane reacted for 5 minutes and then dried in a 40°C oven to produce the (SO₃H)CON-TNC membrane, designated (SO₃H)CON-TNC-5.

[0072] The Fourier transform infrared spectrum of (SO3H) CON-TNC-5 obtained in this example is as follows Figure 2 As shown, at 1244 cm -1 and 1630 cm -1 The characteristic peaks are the stretching vibration absorption peaks of -C-NH- bond and C=O bond in TpSO3H-CON. -1 The stretching vibration absorption peak of -CH2 bond appears at 3067 cm -1 -NH3 appeared + The infrared absorption peak of the bond indicates that TpSO3H-CON is protonated with TREN and undergoes condensation reaction with acyl chloride.

[0073] The powder X-ray diffraction pattern of (SO3H)CON-TNC-5 obtained in this example is as follows Figure 5 As shown in Figure 3, obvious diffraction peaks appear at 2θ = 4.7° and 27.0°, corresponding to the (100) and (001) crystal planes, respectively. The XRD test results match well with the simulated image of AA stacking of the covalent organic framework, indicating that the obtained (SO3H) CON-TNC film has a high degree of crystallinity.

[0074] The X-ray photoelectron spectrum of (SO3H)CON-TNC-5 obtained in this example is shown in Figure 6. The N 1s photoelectron spectrum of (SO3H)CON-TNC-1 deconvoluted into two separate peaks at 399.6-399.8 eV and 401.6-401.7 eV, which were attributed to the amide N(-C-HN-) and the quaternary ammonium salt N + (-NH3 + ), indicating that TpSO3H-CON and TREN undergo protonation.

[0075] Thermogravimetric analysis of the COF films obtained in Examples 3 to 7 is shown in FIG. Figure 7 As shown in the figure, the thermal decomposition temperatures of (SO3H)CON-TNC-1, 2, 3, 4, and 5 under N2 atmosphere were 370, 365, 368, 363, and 362°C, respectively. The (SO3H)CON-TNC membranes exhibited excellent thermal stability. The TNC membranes experienced a weight loss of approximately 13% at 193°C, while the (SO3H)CON-TNC membranes experienced a weight loss of only 8%-10%. Prior to the thermal decomposition temperature, the weight loss rate of the TNC membranes was much greater than that of the (SO3H)CON-TNC membranes. The (SO3H)CON-TNC membranes ultimately retained a higher mass than the TNC membranes. These experimental results fully demonstrate that TpSO3H-CON has been successfully incorporated into the membranes.

[0076] Example 8

[0077] Pervaporation performance test: (SO3H) CON-TNC membrane was used to test the pervaporation separation performance of water / ethanol azeotropic mixture: the pervaporation separation performance test was carried out under the experimental conditions of 60 ℃ and ethanol:water mass ratio of 90:10 wt%. The test results are shown in Figure 2. Figure 8 As shown in Figure 2, the water permeation flux of the original TNC membrane is only 1.91 kg m -2 h -1 The hydrophobic layer on the surface of the TNC membrane makes TNC have a lower water permeation flux, and the separation factor (α water / ethanol) is as small as 275.

[0078] The water permeation flux and separation factor of (SO3H)CON-TNC 1, 2, 3, 4, and 5 membranes were significantly improved, which were 7.9, 5.09, 4.76, 3.31, and 2.83 kg m, respectively. -2 h -1 The corresponding separation factors (α water / ethanol) are 299, 9312, 10585, 10697, and 11121, respectively. Among them, the (SO3H) CON-TNC-3 membrane has the highest water permeation flux and separation factor, with a separation factor of 10585 and a permeation water flux of 4.76 kg m -2 h -1 .

[0079] Example 9

[0080] The pervaporation performance test is as follows: the (SO3H) CON-TNC-3 membrane is subjected to a pervaporation separation performance test of a water / ethanol (at different temperatures) azeotropic mixture. Figure 9 As shown in Figure 2, as the temperature increases, the water permeation flux of the membrane gradually increases. Especially when the temperature reaches 60 °C, the water permeation flux of the membrane is significantly improved compared with that at lower temperatures. At 60 °C, the permeation flux can reach 4.7 kg m -2 h -1 .

Claims

1. A method for preparing a sulfonic acid covalent organic framework-amide composite membrane, comprising: The substrate material is immersed in a 1,3,5-trimethylenediamine (TMC) solution, and then immersed in a mixed solution of tris(2-aminoethyl)amine (TREN) and sulfonic acid COF nanosheets, reacted, and dried to obtain a sulfonic acid covalent organic framework-amide composite membrane; the substrate material includes a polyacrylonitrile membrane; the sulfonic acid COF nanosheets are prepared by interfacial polymerization using an aqueous solution containing 2,5-diaminobenzenesulfonic acid, 1,3,5-trialdehyde phloroglucinol, and n-octanoic acid as raw materials to obtain the sulfonic acid COF nanosheets Tp-SO3H-CON.

2. The preparation method according to claim 1, characterized in that The solvent of the TMC solution includes chloroform; the concentration of the TMC solution is 0.1-3 wt %.

3. The preparation method according to claim 1, characterized in that The mixed solution of TREN and sulfonic acid COF nanosheets: sulfonic acid COF nanosheet aqueous dispersion and TREN solution are mixed and stirred.

4. The preparation method according to claim 1, characterized in that The preparation of the sulfonic acid COF nanosheets includes: using an aqueous solution of 2,5-diaminobenzenesulfonic acid as the aqueous phase, mixing 1,3,5-trialdehyde phloroglucinol and n-octanoic acid, ultrasonically dispersing the mixture, adding the mixture to the aqueous phase as the upper layer, reacting the mixture at room temperature for 24-72 hours, separating and dialyzing the mixture to obtain the sulfonic acid COF nanosheets Tp-SO3H-CON.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the 2,5-diaminobenzenesulfonic acid to 1,3,5-trialdehyde phloroglucinol is (2.8-3.2):

2.

6. The preparation method according to claim 1, characterized in that: The substrate material is immersed in the 1,3,5-trimesoyl chloride TMC solution for 5-15 minutes; The reaction time is 3-6 minutes.

7. A sulfonic acid covalent organic framework-amide composite membrane prepared by the method according to any one of claims 1 to 6.

8. Use of the sulfonic acid covalent organic framework-amide composite membrane according to claim 7 in pervaporation and separation and purification of miscible azeotropic mixtures.

Images