COF biomimetic membrane with artificial water channel as well as preparation method and application of COF biomimetic membrane

Abstract

The invention belongs to the field of new material membrane separation, and relates to a covalent organic framework (COF) biomimetic membrane with an artificial water channel and a preparation method and application thereof. The preparation method comprises the following steps: (1) preparing a TpPa-2 nanosheet solution or a TpPa-SO3H nanosheet solution; (2) synthesizing an HC6 artificial water channel; and (3) performing ultrasonic mixing on the ethanol / hydrocolloid suspension of the artificial water channel and the COF nanosheets respectively, and depositing the mixture on an ultrafiltration membrane substrate through a vacuum-assisted self-assembly technology to prepare the COF biomimetic membrane with the artificial water channel. The obtained biomimetic membrane has excellent ion separation performance and can be used in the fields of seawater desalination and the like.

Description

Technical Field

[0001] The present invention belongs to the field of new material membrane separation, and relates to a COF biomimetic membrane with artificial water channels, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of the world economy, the global water resources are facing serious shortages, which also restricts the further development of human society. To alleviate this problem, obtaining fresh water resources from seawater or brackish water through reverse osmosis technology has gradually become the mainstream choice. Currently, most of the membrane materials used in reverse osmosis technology are polymer reverse osmosis membranes such as polyamide, and there are serious trade-off limitations between their selectivity and permeability.

[0003] Inspired by biological aquaporin proteins, artificial water channels can be used for efficient water molecule transport. In addition, the preparation of biomimetic membranes based on artificial water channels by integrating artificial water channels into a polymer matrix has been studied. However, the upper structure of discrete artificial water channels has poor film-forming ability, which makes it difficult to prepare membranes with high-density channels and uniformly incorporated artificial water channels. However, only a few artificial water channel molecules are successfully incorporated into the membrane matrix, and the limitation between the selectivity and permeability of the membrane is broken.

[0004] Covalent organic frameworks (COFs) are a class of crystalline materials with an ordered porous structure formed by covalently bonding elements such as C, H, O, and N. They have the characteristics of good chemical stability, regular and ordered pore structures, and large specific surface areas, and have broad application prospects in fields such as seawater desalination. Summary of the Invention

[0005] The present invention proposes an assisted self-assembly method for preparing a COF biomimetic membrane with artificial water channels, which combines artificial water channels with COF to solve the problem of poor film-forming ability of artificial water channels. Through this method, a COF biomimetic membrane with artificial water channels with fewer defects can be prepared, so as to achieve excellent separation performance in fields such as seawater desalination and desalination. The specific technical solution is as follows:

[0006] A preparation method of a COF biomimetic membrane with artificial water channels, comprising the following steps:

[0007] (1) Prepare a COF nanosheet suspension;

[0008] (2) Synthesize HC6 artificial water channel molecules;

[0009] (3) Ultrasonically mix the ethanol / water colloidal suspension of HC6 artificial water channel molecules and the COF nanosheet suspension respectively, and deposit them on an ultrafiltration membrane substrate through vacuum-assisted self-assembly technology to prepare a COF biomimetic membrane with artificial water channels.

[0010] Further, the COF nanosheet suspension is a TpPa-2 nanosheet suspension or a TpPa-SO 3 H nanosheet suspension.

[0011] Further, in step (3), the ultrafiltration membrane substrate is made of polyacrylonitrile (PAN).

[0012] Further, the specific preparation of the TpPa-2 nanosheet suspension in step (1) is as follows: Mix 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) with mesitylene until dissolved to obtain an organic phase solution; Mix 2,5-dimethyl-p-phenylenediamine (Pa-2), p-toluenesulfonic acid, and sodium dodecyl sulfate with deionized water until dissolved to obtain an aqueous phase solution; Slowly add the organic phase solution to the aqueous phase solution; React under static conditions at 18 °C for 3 days. After the reaction, remove the organic phase solution, and dialyze the obtained aqueous phase solution in deionized water for 3 days to obtain a TpPa-2 nanosheet suspension.

[0013] Further, the specific preparation of the TpPa-SO 3 H nanosheet suspension in step (1) is as follows: Mix 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) with n-octanoic acid until dissolved to obtain an organic phase solution, and then mix 1,4-phenylenediamine-2-sulfonic acid (Pa-SO 3 H) and Na 2 CO 3 with deionized water until dissolved to obtain an aqueous phase solution. Then, drop the organic phase solution onto the aqueous phase solution as the top layer, and react under static conditions at 16 °C for 4 days. After the reaction, remove the organic phase solution, and dialyze the obtained aqueous phase solution in deionized water for 3 days to obtain a TpPa-SO 3 H nanosheet suspension.

[0014] Further, step (2) is specifically as follows: Dissolve hexyl isocyanate and histamine in a mixed solution of tetrahydrofuran, ethyl acetate, and acetonitrile, and reflux at 80 °C for 3 hours; After the reaction, remove the organic solvent, and dissolve the obtained crude product in ethanol; Slowly add n-hexane to the ethanol solution of the crude product by ultrasonic treatment and precipitate white powder to obtain the HC6 product.

[0015] Further, step (3) is specifically as follows: Dissolve HC6 in a mixed solvent of ethanol and water to obtain a colloidal suspension of HC6; Ultrasonically mix the colloidal suspension of HC6 with COF nanosheets evenly, and prepare a COF biomimetic membrane with artificial water channels by vacuum-assisted self-assembly technology.

[0016] Further, the mass ratio of HC6 to COF in the biomimetic membrane is 10:4 to 19.

[0017] A COF biomimetic membrane with artificial water channels, where the mass ratio of HC6 to COF in the biomimetic membrane is 1:1.3.

[0018] Application of a COF biomimetic membrane with artificial water channels. As a reverse osmosis separation membrane, it can be used for separation tests with different salt solutions in the separation of brackish water. That is, under pressure drive, the salt solution is passed through the COF biomimetic membrane with artificial water channels, and the salt solution concentration after the permeate passes through the biomimetic membrane is analyzed.

[0019] Advantages of the present invention:

[0020] (1) Combining artificial water channels with COF solves the problem of poor film-forming ability of artificial water channels;

[0021] (2) Using artificial water channels as intercalants can adjust the interlayer space of COF nanosheets, improving the transport and selectivity of water molecules;

[0022] (3) The biomimetic membrane of the present invention can be successfully prepared by a simple preparation method and has strong repeatability. Description of the drawings

[0023] Figure 1 is the surface morphology diagram of the COF biomimetic membrane with artificial water channels of the present invention;

[0024] Figure 2 is the cross-sectional diagram of the COF biomimetic membrane with artificial water channels of the present invention;

[0025] Figure 3 is the separation performance diagram of the COF biomimetic membrane with artificial water channels in Examples 1 to 5 of the present invention. Detailed implementation manners

[0026] In order to make the purpose, technical solutions and technical effects of the present invention clearer, the following further elaborates on the present invention in combination with the drawings of the specification and examples.

[0027] The preparation method of the COF biomimetic membrane with artificial water channels of the present invention includes the following steps:

[0028] (1) Prepare a suspension of TpPa-2 nanosheets or a suspension of TpPa-SO 3 H nanosheets;

[0029] (2) Synthesize HC6 artificial water channel molecules;

[0030] (3) Ultrasonically mix the ethanol / water colloidal suspension of HC6 artificial water channel molecules and the suspension of COF nanosheets. The suspension of COF nanosheets uses the suspension of TpPa-2 nanosheets or TpPa-SO prepared in step (1) 3H nanosheet suspension is deposited on an ultrafiltration membrane substrate, such as polyacrylonitrile (PAN), by vacuum-assisted self-assembly technology to prepare an artificial water channel COF biomimetic membrane, such as Figure 1 and Figure 2 shown.

[0031] Example 1

[0032] In this example, the preparation method of the COF biomimetic membrane with artificial water channels specifically includes the following steps:

[0033] (1) Preparation of TpPa-2 nanosheet suspension:

[0034] 21.1 mg of 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) is mixed with 100 mL of mesitylene until dissolved to obtain an organic phase solution; 20.4 mg of 2,5-dimethyl-p-phenylenediamine (Pa-2), 51.6 mg of p-toluenesulfonic acid, and 230.7 mg of sodium dodecyl sulfate are mixed with 100 mL of deionized water until dissolved to obtain an aqueous phase solution; the organic phase solution is slowly added to the aqueous phase solution. React at 18 °C under static conditions for 3 days. After the reaction, the organic phase solution is removed, and the obtained aqueous phase solution is dialyzed in deionized water for 3 days to obtain a TpPa-2 nanosheet suspension.

[0035] (2) Synthesis of HC6 artificial water channel molecules:

[0036] 2.6 g of hexyl isocyanate and 2.3 g of histamine are dissolved in a mixed solution of 140 mL of tetrahydrofuran, 70 mL of ethyl acetate, and 140 mL of acetonitrile, and refluxed at 80 °C for 3 hours. After the reaction, the organic solvent is removed, and the obtained crude product is dissolved in ethanol. n-Hexane is slowly added to the ethanol solution of the crude product by ultrasonic treatment, and a white powder is precipitated to obtain the HC6 product.

[0037] (3) Preparation of COF biomimetic membrane with artificial water channels:

[0038] 10 mg of HC6 is dissolved in a mixed solution of ethanol and water to obtain a colloidal suspension of HC6; the colloidal suspension of HC6 is ultrasonically mixed evenly with the suspension containing 4 mg of TpPa-2 nanosheets, and a COF biomimetic membrane with artificial water channels is prepared by vacuum-assisted self-assembly technology, where the mass ratio of HC6:COF is 5:2.

[0039] The rejection rate of the biomimetic membrane for 3000 ppm NaCl solution is 70.4%, and the water flux is 24.6 L m -2 h -1 bar -1 .

[0040] Example 2

[0041] In this embodiment, the preparation method of the COF biomimetic membrane with artificial water channels specifically includes the following steps:

[0042] (1) The preparation of the TpPa-2 nanosheet suspension is the same as that in Example 1 and will not be elaborated here;

[0043] (2) The synthesis of the HC6 artificial water channel molecule is the same as that in Example 1 and will not be elaborated here;

[0044] (3) Preparation of the COF biomimetic membrane with artificial water channels:

[0045] Dissolve 10 mg of HC6 in a mixed solution of ethanol and water to obtain a colloidal suspension of HC6; ultrasonically mix the HC6 colloidal suspension with the suspension containing 10 mg of TpPa-2 nanosheets evenly, and prepare the COF biomimetic membrane with artificial water channels by vacuum-assisted self-assembly technology, where the mass ratio of HC6:COF is 1:1.

[0046] The rejection rate of the 3000 ppm NaCl solution using this biomimetic membrane is 90.1%, and the water flux is 18.5 L m -2 h -1 bar -1 .

[0047] Example 3

[0048] In this embodiment, the preparation method of the COF biomimetic membrane with artificial water channels specifically includes the following steps:

[0049] (1) The preparation of the TpPa-2 nanosheet suspension is the same as that in Example 1 and will not be elaborated here;

[0050] (2) The synthesis of the HC6 artificial water channel molecule is the same as that in Example 1 and will not be elaborated here;

[0051] (3) Preparation of the COF biomimetic membrane with artificial water channels:

[0052] Dissolve 10 mg of HC6 in a mixed solution of ethanol and water to obtain a colloidal suspension of HC6; ultrasonically mix the HC6 colloidal suspension with the suspension containing 13 mg of TpPa-2 nanosheets evenly, and prepare the COF biomimetic membrane with artificial water channels by vacuum-assisted self-assembly technology, where the mass ratio of HC6:COF is 1:1.3.

[0053] The rejection rate of the 3000 ppm NaCl solution using this biomimetic membrane is 94.7%, and the water flux is 17.8 L m -2 h -1 bar -1 .

[0054] Example 4

[0055] In this example, the preparation method of the COF biomimetic membrane with artificial water channels specifically includes the following steps:

[0056] (1) Preparation of TpPa-SO 3 H nanosheet suspension:

[0057] Mix 21.1 mg of 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) with 20 mL of n-caprylic acid until dissolved to obtain an organic phase solution. Then, mix 28.3 mg of 1,4-phenylenediamine-2-sulfonic acid (Pa-SO 3 H) and 23.8 mg of Na 2 CO 3 with 30 mL of deionized water until dissolved to obtain an aqueous phase solution. Then, add the organic phase solution dropwise onto the aqueous phase solution as the top and react under static conditions at 16 °C for 4 days. After the reaction, remove the organic phase solution, and dialyze the obtained aqueous phase solution in deionized water for 3 days to obtain the TpPa-SO 3 H nanosheet suspension.

[0058] (2) The synthesis of the HC6 artificial water channel molecule is the same as that in Example 1 and will not be elaborated here;

[0059] (3) Preparation of the COF biomimetic membrane with artificial water channels:

[0060] Dissolve 10 mg of HC6 in a mixed solution of ethanol and water to obtain a colloidal suspension of HC6; ultrasonically mix the colloidal suspension of HC6 with the suspension containing 16 mg of TpPa-SO 3 H nanosheets uniformly, and prepare the COF biomimetic membrane with artificial water channels by vacuum-assisted self-assembly technology, where the mass ratio of HC6:COF is 1:1.6.

[0061] The rejection rate of the 3000 ppm NaCl solution using this biomimetic membrane is 95.1%, and the water flux is 14.1 L m -2 h -1 bar -1 .

[0062] Example 5

[0063] In this example, the preparation method of the COF biomimetic membrane with artificial water channels specifically includes the following steps:

[0064] (1) The preparation of the TpPa-SO 3 H nanosheet suspension is the same as that in Example 4 and will not be elaborated here;

[0065] (2) The synthesis of HC6 artificial water channel molecules is the same as in Example 1 and will not be described in detail here;

[0066] (3) Preparation of COF biomimetic membrane with artificial water channels:

[0067] 10 mg HC6 was dissolved in a mixed solution of ethanol and water to obtain a colloidal suspension of HC6; the HC6 colloidal suspension was evenly mixed with a suspension containing 19 mg by ultrasonic mixing, and a COF biomimetic membrane with artificial water channels was prepared by vacuum-assisted self-assembly technology, wherein the mass ratio of HC6:COF was 1:1.9.

[0068] The biomimetic membrane has a rejection rate of 95.6% for 3000 ppm NaCl solution and a water flux of 10.5 L m -2 h -1 bar -1 .

[0069] like Figure 3 Shown are the results of separation performance tests of the COF biomimetic membranes with artificial water channels prepared in Examples 1 to 5.

[0070] The above is only a preferred implementation case of the present invention and does not limit the present invention in any form. Although the implementation process of the present invention is described in detail above, for those familiar with the art, they can still modify the technical solutions recorded in the above examples, or replace some of the technical features therein with equivalents. All modifications, equivalent replacements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a COF biomimetic membrane with artificial water channels, characterized in that: The following steps are involved: (1) Preparation of COF nanosheet suspension; (2) Synthesis of HC6 artificial water channel molecule; (3) The ethanol / water colloidal suspension of HC6 artificial water channel molecules was ultrasonically mixed with the COF nanosheet suspension, and then deposited on the ultrafiltration membrane substrate by vacuum-assisted self-assembly technology to prepare an artificial water channel COF bionic membrane.

2. The method for preparing a COF biomimetic membrane having an artificial water channel according to claim 1, characterized in that: The COF nanosheet suspension is a TpPa-2 nanosheet suspension or a TpPa-SO3H nanosheet suspension.

3. The method for preparing a COF biomimetic membrane having an artificial water channel according to claim 1, characterized in that: In step (3), the ultrafiltration membrane substrate is made of polyacrylonitrile (PAN).

4. The method for preparing a COF biomimetic membrane having an artificial water channel according to claim 2, characterized in that: Step (1) preparing the TpPa-2 nanosheet suspension comprises: mixing 2,4,6-trihydroxybenzene-1,3,5-triformaldehyde (Tp) and mesitylene until dissolved to obtain an organic phase solution; mixing 2,5-dimethyl-p-phenylenediamine (Pa-2), p-toluenesulfonic acid and sodium dodecyl sulfate with deionized water until dissolved to obtain an aqueous phase solution; The organic phase solution was slowly added to the aqueous phase solution; the reaction was carried out at 18°C ​​static conditions for 3 days. After the reaction was completed, the organic phase solution was removed, and the obtained aqueous phase solution was dialyzed in deionized water for 3 days to obtain a TpPa-2 nanosheet suspension.

5. The method for preparing a COF biomimetic membrane having an artificial water channel according to claim 1, characterized in that: Step (1) preparing the TpPa-SO3H nanosheet suspension is specifically as follows: 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) is mixed with octanoic acid until dissolved to obtain an organic phase solution, and 1,4-phenylenediamine-2-sulfonic acid (Pa-SO3H) and Na2CO3 are mixed with deionized water until dissolved to obtain an aqueous phase solution, and then the organic phase solution is added dropwise onto the aqueous phase solution as the top, and reacted at 16°C under static conditions for 4 days. After the reaction is completed, the organic phase solution is removed, and the obtained aqueous phase solution is dialyzed in deionized water for 3 days to obtain the TpPa-SO3H nanosheet suspension.

6. The method for preparing a COF biomimetic membrane having an artificial water channel according to claim 1, characterized in that: Step (2) is specifically as follows: dissolving hexyl isocyanate and histamine in a mixture of tetrahydrofuran, ethyl acetate and acetonitrile, and reacting under reflux at 80° C. for 3 hours; after the reaction, removing the organic solvent, and dissolving the obtained crude product in ethanol; slowly adding n-hexane to the ethanol solution of the crude product by ultrasound, and precipitating a white powder to obtain the HC6 product.

7. The method for preparing a COF biomimetic membrane having an artificial water channel according to claim 1, characterized in that: Step (3) is specifically as follows: dissolving HC6 in a mixed solvent of ethanol and water to obtain a colloidal suspension of HC6; uniformly mixing the HC6 colloidal suspension with COF nanosheets by ultrasonic mixing, and preparing a COF bionic membrane with artificial water channels by vacuum-assisted self-assembly technology.

8. The method for preparing a COF biomimetic membrane having an artificial water channel according to claim 1, characterized in that: The mass ratio of HC6 to COF in the bionic membrane is 10:4~19.

9. A COF biomimetic membrane with artificial water channels prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The mass ratio of HC6 to COF in the bionic membrane is 1:1.

3.

10. An application of the COF biomimetic membrane with artificial water channels as claimed in claim 9, characterized in that: As a reverse osmosis separation membrane.

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