Method For Preparing Porous Aromatic Framework Membranes Based on Inorganic Salt Template Method

Abstract

The present disclosure relates to the field of porous material synthesis, and particularly to a method for preparing porous aromatic framework membranes based on an inorganic salt template method. It aims at the problem of difficulty of preparation of porous aromatic framework membranes in large scale and large size. It uses alkynyl-containing building units and bromine-containing building units as raw materials and obtains continuous, dense, defect-free porous aromatic framework membranes through Sonogashira-Hagihara coupling polymerization. It specifically successfully prepares porous aromatic framework nanosheets on an inorganic salt substrate, and then produces a centimeter-scale large size continuous porous aromatic framework membrane through self-assembly. The method has mild conditions, a simple preparation process, and it is easy to operate. The prepared membranes have high yield and large area, and meet the requirements of actual industrial production.

Claims

1. A method for preparing a porous aromatic framework membrane based on an inorganic salt template method, comprising the following steps: mixing an inorganic salt template, an alkynyl-containing building unit and a bromine-containing building unit, adding solvent and triethylamine, continuing to add catalyst under nitrogen protection, mixing evenly to obtain a mixed solution; and under nitrogen protection and liquid nitrogen, letting the mixed solution undergo a freeze-vacuum-thaw cycle, then reacting at 60-150? C. for 48-96 hours, and collecting an inorganic salt layer and removing inorganic salt from the inorganic salt layer to obtain porous aromatic framework nanosheets, and then processing the porous aromatic framework nanosheets via a pressure-assisted method to obtain a porous aromatic framework membrane, wherein, the bromine-containing building unit is a bromine-containing organic monomer, the alkynyl-containing building unit is an alkynyl-containing monomer, and the numbers of bromine and alkynyl in the monomers are both greater than 1.

2. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein the bromine-containing building unit comprises 1,3,5-tribromobenzene, 1,3,5-tribromobenzene-2,4,6-triol, 1,4-dibromo-2-(methyl imidazole methyl ethyl)benzene, 1,3,5-tris(4-bromophenyl)benzene, tetrabromotetraphenylmethane, tris(4-(bromomethyl)phenyl)amine, 1,4-dibromobenzene, 2,4,6-tribromo-1,3,5-trimethylbenzene, tetra(4-bromomethylphenyl)ethylene, or 1,4-dibromo-2,5-diethylbenzene; the alkynyl-containing building unit comprises tris(4-ethynylphenyl)amine, 1,3,5-tris(4-ethynylphenyl)benzene, 5,10,15,20-tetrakis(4-ethynyl phenyl porphyrin), 1,3,5-triethynylbenzene, 1,4-diethynylbenzene, 4,4-diethynylbiphenyl, tetrakis(4-ethynylbenzene)methane, 1,3,6,8-tetraethynylpyrene, 3,3,5,5-tetraethynyl-1,1-biphenyl.

3. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein a ratio of a mass of the inorganic salt template, an amount of the alkynyl-containing building unit, and an amount of the bromine-containing building unit is (10-20) g:(0.005-0.02) mmol:(0.005-0.02) mmol.

4. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein the inorganic salt template is selected from a group consisting of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, aluminum chloride, sodium sulfate, magnesium sulfate, and potassium sulfate.

5. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein the solvent is selected from toluene, mesitylene, o-dichlorobenzene, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, dichloromethane, triethylamine, and ethylenediamine.

6. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein: if the bromine-containing building unit is selected from 1,3,5-tribromobenzene and the alkynyl-containing building unit is selected from tris(4-ethynylphenyl)amine, a reaction formula of the porous aromatic framework membrane is: ##STR00007## if the bromine-containing building unit is selected from 1,3,5-tribromobenzene-2,4,6-triol and the alkynyl-containing building unit is selected from tris(4-ethynylphenyl)amine, a reaction formula of the porous aromatic framework membrane is: ##STR00008## if the bromine-containing building unit is selected from 1,4-dibromo-2-(methyl imidazole methyl ethyl)benzene and the alkynyl-containing building unit is selected from tris(4-ethynylphenyl)amine, a reaction formula of the porous aromatic framework membrane is: ##STR00009## wherein, n?1.

7. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein a ratio of an amount of the bromine-containing building unit to a volume of triethylamine is 0.01 mmol:10-40 mL

8. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein the catalyst is composed of tetrakis(triphenylphosphine) palladium and cuprous iodide, and a mass ratio of the tetrakis(triphenylphosphine) palladium to the cuprous iodide is 10-15:2-5; a ratio of an amount of the bromine-containing building unit to a mass of the tetrakis(triphenylphosphine) palladium is 0.01 mmol:10-15 mg.

9. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein the pressure-assisted method adopts a suction filtration operation.

10. The method for preparing a porous aromatic framework membrane based on an inorganic salt template method according to claim 1, wherein a method for removing the inorganic salt comprises: washing the inorganic salt layer by sequentially using chloroform, methanol, and water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 shows Fourier transform infrared spectra of three porous aromatic framework membranes prepared in Examples 1, 5, and 9 of the present disclosure;

[0031] FIG. 2 is a scanning electron microscope characterization diagram of the porous aromatic framework membranes prepared in Examples 1, 5, and 9 of the present disclosure, wherein (a) is PAF-34M, (b) is PAF-317M, and (c) is PAF-318M;

[0032] FIG. 3 is a transmission electron microscope characterization diagram of the porous aromatic framework membranes prepared in Examples 1, 5, and 9 of the present disclosure, wherein (a) is PAF-34M, (b) is PAF-317M, and (c) is PAF-318M;

[0033] FIG. 4 shows optical photographs of the porous aromatic framework membranes prepared in Examples 1, 5, and 9 of the present disclosure, wherein (a) is PAF-34M, (b) is PAF-317M, and (c) is PAF-318M;

[0034] FIG. 5 shows the filtration performance of Congo red molecules using PAF-34M prepared in Example 1.

[0035] FIG. 6 shows Fourier transform infrared spectrum of the PAF membrane prepared in Example 13.

DETAILED DESCRIPTION OF EMBODIMENTS

[0036] Specific embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present disclosure is not limited by the specific embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present disclosure without any creative work fall within the scope of protection of the present disclosure. The raw materials used in the present disclosure, if the manufacturer is not indicated, are all conventional products that can be purchased on the market.

[0037] In order to make the content of the present disclosure easier to understand, the technical solutions of the present disclosure will be further described below in conjunction with specific embodiments, but the present disclosure is not limited thereto.

[0038] In the present disclosure, 1,4-dibromo-2-(methylimidazolemethylethyl)benzene (1,4-dibromo-2-(methyl imidazole methyl ethyl)benzene) is a product prepared according to a reference literature. The DOI number of the reference literature is: 10.1002/anie.202113682;

Example 1

[0039] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-34M is prepared, it specifically includes the following steps:

[0040] Under a protective atmosphere of nitrogen, PAF-34M is prepared by using tris(4-ethynylphenyl)amine and 1,3,5-tribromobenzene as raw materials, adding them on a NaCl substrate, and polymerizing under a catalyst to form porous aromatic framework nanosheets.

[0041] The synthesis roadmap is:

##STR00004##

[0042] The specific synthesis method is as follows:

[0043] Weigh 15 g of NaCl, 31.7 mg (0.01 mmol) of tris(4-ethynylphenyl)amine and 31.5 mg (0.01 mmol) of 1,3,5-tribromobenzene, add them into a 100 mL double-necked flask, add 10 mL of toluene and 10 mL triethylamine (TEA, Et.sub.3N), add 15 mg of tetrakis (triphenylphosphine) palladium and 5 mg of copper iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 150? C. oil bath to react for 48 hours; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-34 nanosheets, and then obtain continuous PAF-34M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

[0044] Fourier transform infrared spectrum (IR) analysis is performed on the porous aromatic framework membrane (PAF-34M) prepared in Example 1. The characteristic peaks of the CBr bond at 1075 cm.sup.?1 and 600 cm.sup.?1 disappear, and at the same time the strong absorption peak near 3300 cm.sup.?1 related to the CC stretching vibration of the alkynyl group disappears, indicating that the monomer has fully reacted; a low intensity peak is observed near 2200 cm.sup.?1, it is due to the presence of the alkynyl C?C in PAF-34M, which all proves the successful synthesis of PAF-34M.

Example 2

[0045] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-34M is prepared, it specifically includes the following steps:

[0046] Weigh 10 g of NaCl, 15.8 mg (0.005 mmol) of tris(4-ethynylphenyl)amine and 15.7 mg (0.005 mmol) of 1,3,5-tribromobenzene, add them into a 100 mL double-necked flask, add 5 mL of toluene and 5 mL of triethylamine (TEA, Et.sub.3N), add 10 mg of tetrakis (triphenylphosphine) palladium and 2 mg of copper iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 60? C. oil bath to react for 96 hours; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-34 nanosheets, and then obtain continuous PAF-34M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 3

[0047] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-34M is prepared, it specifically includes the following steps:

[0048] Weigh 30 g of NaCl, 31.7 mg (0.02 mmol) of tris(4-ethynylphenyl)amine and 31.5 mg (0.02 mmol) of 1,3,5-tribromobenzene, add them into a 100 mL double-necked flask, add 40 mL of toluene and 40 mL triethylamine (TEA, Et.sub.3N), add 15 mg (0.013 mmol) tetrakis (triphenylphosphine) palladium and 5 mg (0.013 mmol) copper iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 100? C. oil bath to react for 2 days; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-34 nanosheets, and then obtain continuous PAF-34M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 4

[0049] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-34M is prepared, it specifically includes the following steps:

[0050] Weigh 20 g of NaCl, 31.7 mg (0.01 mmol) of tris(4-ethynylphenyl)amine and 31.5 mg (0.01 mmol) of 1,3,5-tribromobenzene, add them into a 100 mL double-necked flask, add 20 mL of N,N-Dimethylformamide (DMF) and 20 mL triethylamine (TEA, Et.sub.3N), add 13.8 mg (0.012 mmol) tetrakis (triphenylphosphine) palladium and 2.3 mg (0.012 mmol) copper iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 100? C. oil bath to react for 2 days; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-34 nanosheets, and then obtain continuous PAF-34M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 5

[0051] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-317M is prepared, it specifically includes the following steps:

[0052] Under a protective atmosphere of nitrogen, PAF-317M is prepared by using tris(4-ethynylphenyl)amine and 1,3,5-tribromobenzene-2,4,6-triol as raw materials, adding them to a substrate, and polymerizing under a catalyst to firm porous aromatic framework nanosheets (PAF-317).

[0053] The specific synthesis roadmap is:

##STR00005##

[0054] The specific synthesis method is as follows:

[0055] Weigh 15 g of NaCl, 31.7 mg (0.01 mmol) of tris(4-ethynylphenyl)amine and 36.3 mg (0.01 mmol) of 1,3,5-tribromobenzene-2,4,6-triol, add them into a 100 mL double-necked flask, add 10 mL of toluene and 10 mL of triethylamine (TEA, Et.sub.3N), add 15 mg of tetrakis (triphenylphosphine) palladium and 5 mg of copper iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 150? C. oil bath to react for 48 hours; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-317 nanosheets, and then obtain continuous PAF-317M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

[0056] Fourier transform infrared spectrum (IR) analysis is performed on the porous aromatic framework membrane (PAF-317M) prepared in Example 5. The characteristic peaks of the CBr bond at 1075 cm.sup.?1 and 600 cm.sup.?1 disappear, and at the same time the strong absorption peak near 3300 cm.sup.?1 related to the CC stretching vibration of the alkynyl group disappears, indicating that the monomer has fully reacted; a low intensity peak is observed near 2200 cm.sup.?1, it is due to the presence of the alkynyl C?C in PAF-34M, and the broad stretching vibration peak of OH at 3500 cm.sup.?1 is still retained, which all proves the successful synthesis of PAF-317M.

Example 6

[0057] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-317M is prepared, it specifically includes the following steps:

[0058] Weigh 10 g of NaCl, 15.8 mg (0.005 mmol) of tris(4-ethynylphenyl)amine and 18.2 mg (0.005 mmol) of 1,3,5-tribromobenzene-2,4,6-triol, add them into a 100 mL double-necked flask, add 10 mL of toluene and 5 mL of triethylamine (TEA, Et.sub.3N), add 10 mg of tetrakis (triphenylphosphine) palladium and 2 mg of copper iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 60? C. oil bath to react for 96 hours; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-317 nanosheets, and then obtain continuous PAF-317M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 7

[0059] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-317M is prepared, it specifically includes the following steps:

[0060] Weigh 20 g of NaCl, 63.4 mg (0.02 mmol) of tris(4-ethynylphenyl)amine and 72.6 mg (0.02 mmol) of 1,3,5-tribromobenzene-2,4,6-triol, add them into a 100 mL double-necked flask, add 15 mL of toluene and 15 mL of triethylamine (TEA, Et.sub.3N), add 15 mg (0.013 mmol) of tetrakis (triphenylphosphine) palladium and 5 mg (0.013 mmol) of cuprous iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 100? C. oil bath to react for 2 days; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-317 nanosheets, and then obtain continuous PAF-317M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 8

[0061] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-317M is prepared, it specifically includes the following steps:

[0062] Weigh 20 g of NaCl, 31.7 mg (0.01 mmol) of tris(4-ethynylphenyl)amine and 36.3 mg (0.01 mmol) of 1,3,5-tribromobenzene-2,4,6-triol, add them into a 100 mL double-necked flask, add 20 mL N,N-Dimethylformamide (DMF) and 20 mL triethylamine (TEA, Et.sub.3N), and add 13.8 mg (0.012 mmol) tetrakis (triphenylphosphine) palladium and 2.3 mg (0.012 mmol) of cuprous iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 100? C. oil bath to react for 48 h; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-317 nanosheets, and then obtain continuous PAF-317M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 9

[0063] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-318M is prepared, it specifically includes the following steps:

[0064] PAF-318M is prepared by using 1,4-dibromo-2-(methylimidazolemethylethyl)benzene and tris(4-ethynylphenyl)amine as raw materials, adding them to a substrate, and polymerizing under a catalyst to form porous aromatic framework nanosheets.

[0065] The specific synthesis roadmap is:

##STR00006##

[0066] The specific synthesis method is as follows:

[0067] Weigh 15 g of NaCl, 31.7 mg (0.01 mmol) of tris(4-ethynylphenyl)amine and 62.6 mg (0.01 mmol) of 1,4-dibromo-2-(methylimidazolemethylethyl)benzene, add them into a 100 mL double-neck flask, add 10 mL toluene and 10 mL triethylamine (TEA, Et.sub.3N), add 15 mg tetrakis (triphenylphosphine) palladium and 5 mg (0.012 mmol) cuprous iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 150? C. oil bath to react for 48 h; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-318 nanosheets, and then obtain continuous PAF-318M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

[0068] Fourier transform infrared spectrum (IR) analysis is performed on the porous aromatic framework membrane (PAF-318M) prepared in Example 9. The characteristic peaks of the CBr bond at 1075 cm.sup.?1 and 600 cm.sup.?1 disappear, and at the same time the strong absorption peak near 3300 cm.sup.?1 related to the CC stretching vibration of the alkynyl group disappears, indicating that the monomer has fully reacted; the characteristic stretching vibration peak at 1451 cm.sup.?1 is attributed to the C?N bond in the imidazole ring, and the characteristic stretching vibration peak at 1398 cm.sup.?1 is attributed to the CH bond in the imidazole ring, the characteristic stretching vibration peak at 1109 cm.sup.?1 is attributed to the CN bond in the imidazole ring, which shows that the imidazole functional group is not destroyed during the polymerization process; a low-intensity peak is observed near 2200 cm.sup.?1, this is due to the presence of alkynyl group C?C in PAF-318M, which all proves the successful synthesis of PAF-318M.

Example 10

[0069] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-318M is prepared, it specifically includes the following steps:

[0070] Weigh 10 g of NaCl, 15.8 mg (0.005 mmol) of tris(4-ethynylphenyl)amine and 31.3 mg (0.005 mmol) of 1,4-dibromo-2-(methylimidazolemethylethyl)benzene, add them into a 100 mL double-neck flask, add 10 mL of toluene and 5 mL of triethylamine (TEA, Et.sub.3N), add 10 mg of tetrakis (triphenylphosphine) palladium and 2 mg of cuprous iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 60? C. oil bath to react for 96 hours; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-318 nanosheets, and then obtain continuous PAF-318M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 11

[0071] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-318M is prepared, it specifically includes the following steps:

[0072] Weigh 20 g of NaCl, 63.4 mg (0.02 mmol) of tris(4-ethynylphenyl)amine and 125.2 mg (0.02 mmol) of 1,4-dibromo-2-(methylimidazolemethylethyl)benzene, add them into a 100 mL double-neck flask, add 15 mL of toluene and 15 mL of triethylamine (TEA, Et.sub.3N), add 15 mg (0.013 mmol) of tetrakis (triphenylphosphine) palladium and 5 mg (0.013 mmol) of cuprous iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 100? C. oil bath to react for 2 days; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-318 nanosheets, and then obtain continuous PAF-318M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 12

[0073] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method. In this example, a porous aromatic framework membrane PAF-318M is prepared, it specifically includes the following steps:

[0074] Weigh 20 g of NaCl, 31.7 mg (0.01 mmol) of tris(4-ethynylphenyl)amine and 62.6 mg (0.01 mmol) of 1,4-dibromo-2-(methylimidazolemethylethyl)benzene, add them into a 100 mL double-neck flask, add 20 mL of N,N-dimethylformamide (DMF) and 20 mL of triethylamine (TEA, Et.sub.3N), and add 13.8 mg (0.012 mmol) of tetrakis (triphenylphosphine) palladium and 2.3 mg (0.012 mmol) of copper iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 100? C. oil bath to react for 48 h; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively to obtain PAF-318 nanosheets, and then obtain continuous PAF-318M after suction filtration, and dry it in an oven at 100? C. for 10 hours.

Example 13

[0075] A method for preparing a porous aromatic framework membrane based on an inorganic salt template method, it specifically includes the following steps:

[0076] Weigh 20 g of CaCl.sub.2, 0.01 mmol of 1,3,5-triethynylbenzene and 0.01 mmol of 2,4,6-tribromo-1,3,5-hydroxybenzene into a 100 mL double-necked flask, add 10 mL of toluene and 10 mL of triethylamine (TEA, Et.sub.3N), add 13.8 mg (0.012 mmol) of tetrakis (triphenylphosphine) palladium and 2.3 mg (0.012 mmol) of cuprous iodide under nitrogen protection to obtain a mixed solution. After ultrasonicating the mixed solution for 5 minutes, perform a freeze-pumping operation under nitrogen protection and liquid nitrogen, and undergo a freeze-vacuum-thaw cycle, then place it in a 100? C. oil bath to react for 48 hours; collect the NaCl layer, and then wash it with chloroform, methanol, and water respectively, followed by suction filtration and dry it in an oven at 100? C. for 10 hours to obtain a porous aromatic framework membrane prepared based on the inorganic salt template method. The Fourier transform infrared characterization in FIG. 6 shows that the PAF membrane prepared in Example 13 was successfully synthesized.

[0077] Next, we characterize the morphology of the porous aromatic framework membrane prepared in the above example. In FIG. 2, the scanning electron microscope of PAF-34M, PAF-317M, and PAF-318M shows that the surfaces of the three membranes are continuous and uniform, with no obvious holes or crack-like defects, and all have lamellar morphologies. The transmission electron microscopy characterization in FIG. 3 also shows a continuous and uniform film surface without obvious defects. As shown in FIG. 4, the optical photos confirm the successful synthesis of large-size PAF continuous membranes, this is a huge breakthrough in the field of PAF membrane synthesis.

[0078] Congo red dye is an azo dye that is highly toxic and carcinogenic. Since Congo red dye has an aromatic nitro-complex benzene ring structure and is difficult to biodegrade, it would be of great benefit to human health if Congo red dye is effectively removed from wastewater. In order to verify that the membrane has a separation effect, a PAF-34 membrane was selected to measure the separation performance of the membrane by filtrating 100 mg/L Congo red aqueous solution for three filtration tests. The filtration test lasted for 6 hours in each cycle test, during which the ultraviolet-visible (UV-Vis) spectrum of the collected permeation fluid was measured every two hours to analyze the interception effect of the PAF-34 membrane on Congo red molecules. The results in FIG. 5 prove that at 0.2 MPa, the three permeation fluxes are 239.5 L/m.sup.2hMPa, 250.0 L/m.sup.2hMPa, and 247.5 L/m.sup.2hMPa respectively. The interception rate (rejection rate) of each filtration test remains above 99.99%. The high interception rate and high water permeation amount shows that the PAF continuous membrane synthesized based on this method has excellent separation performance.

[0079] Obviously, those skilled in the art can make various changes and modifications to the present disclosure without departing from the spirit and scope of the present disclosure. In this way, if these modifications and variations of the present disclosure fall within the scope of the claims of the present disclosure and equivalent technologies, the present disclosure is also intended to include these modifications and variations.