Poly (ether) sulfuryl block copolymer integrated nanofiltration membrane as well as preparation method and application thereof

Abstract

The invention relates to a poly (ether) sulfuryl block copolymer integrated nanofiltration membrane and a preparation method and application thereof, and belongs to the technical field of high polymer materials, and the preparation method comprises the following steps: adding an additive with reaction active sites into a membrane casting solution, adding another substance capable of carrying out a cross-linking reaction with the additive in the membrane casting solution into a coagulating bath, and carrying out a cross-linking reaction with the additive in the membrane casting solution to obtain the poly (ether) sulfuryl block copolymer integrated nanofiltration membrane. Preparing a flat sheet membrane through a non-solvent induced phase separation technology; the compact hollow fiber nanofiltration membrane is integrally prepared on line by using a double-layer spinning nozzle through dry spraying and wet spinning by taking a membrane casting solution added with a monomer with reaction activity as an inner layer and taking a solution containing another substance capable of being subjected to cross-linking reaction with the monomer with reaction activity in the membrane casting solution as an outer layer. The method disclosed by the invention has the characteristics of simple process, simplicity and convenience in operation, short preparation period and environmental friendliness, and compared with a traditional membrane preparation process, the method is more favorable for preparing the high-flux and high-interception nanofiltration membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a method for preparing an integrated nanofiltration membrane of poly(ether)sulfone-based block copolymer. Background Art

[0002] Due to rapid urbanization and industrialization, the problem of water pollution has become increasingly serious and has become a new problem threatening human health. The nanofiltration membrane separation technology has the advantages of simple operation, low operating pressure, good water production quality, etc., and can achieve precise screening of divalent ions and monovalent ions, selective separation between molecules and ions, and selective separation between different molecules, etc. With its excellent screening performance, nanofiltration membranes are widely used in the fields of sewage treatment, seawater desalination, food processing, and biomedicine. At present, the non-solvent induced phase separation method (NIPS) is usually used in industry to prepare nanofiltration membranes. This method has the advantages of simple membrane preparation process and low equipment investment; however, the separation accuracy of the nanofiltration membrane prepared only by the one-step phase inversion method is low, and it is difficult to be efficiently utilized in the field of water treatment.

[0003] Chemical modification of the membrane surface by surface crosslinking can further reduce the pore size of the membrane and improve the membrane density, thereby achieving precise screening of small molecules / ions. However, these additional membrane preparation steps involve more reaction steps, which complicate the membrane preparation process and are not easy for industrial production. In order to simplify the membrane preparation steps and save costs, some researchers have combined crosslinking with phase inversion and developed a membrane preparation method with great industrial potential. Chinese Patent CN117815944A discloses a method for preparing a high-performance polysulfone-based block copolymer nanofiltration membrane. In this method, a polysulfone-based block copolymer is blended with functional materials rich in active functional groups such as cyclodextrin and polyethyleneimine to prepare a casting solution, and the casting solution is scraped into a liquid membrane. The liquid membrane is immersed in an organic solution containing a crosslinking agent for crosslinking reaction, and then the membrane is immersed in a coagulation bath rich in water for phase inversion and solidification into a membrane. This method has a simple process, greatly simplifies the membrane preparation process, and the obtained membrane has excellent permeation and separation performance. However, this method immerses the liquid membrane in an organic solvent for crosslinking reaction and then immerses it in a coagulation bath rich in water for phase inversion and solidification into a membrane. The operation steps are time-consuming and prone to membrane defects.

[0004] To further simplify the membrane preparation process, reduce the use of organic solvents, and improve the membrane preparation stability, there is an urgent need for a new membrane preparation process in which a substance capable of crosslinking with an additive in the casting solution is added to the coagulation bath for crosslinking and phase inversion to be carried out simultaneously, making the membrane preparation process more simple and efficient. Summary of the Invention

[0005] The object of the present invention is to provide a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane, a preparation method thereof and an application thereof. It aims to generate a thin and dense cross-linked skin layer on the membrane surface while the nascent liquid membrane is immersed in a non-solvent for curing through a cross-linking reaction, avoiding the traditional secondary treatment process, thereby simplifying the process and making the membrane preparation process more efficient.

[0006] On the one hand, the preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane provided by the present invention adopts the following technical scheme:

[0007] The preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane includes the following steps:

[0008] S1. Take 15-28 wt.% of poly(ether)sulfone-block-polyethyleneimine block copolymer and 3-15 wt.% of active additive and blend and dissolve them in 57-82 wt.% of organic solvent to obtain a uniform casting solution;

[0009] S2. Take the casting solution prepared in step S1. After the casting solution is degassed, use a doctor blade to scrape it into a flat membrane. Immerse the liquid flat membrane in a 0.1-2 wt% cross-linking agent solution for 5-30 s to carry out a cross-linking reaction, forming a cross-linked skin layer on the surface of the flat membrane, and finally forming a cross-linked membrane. Immerse the cross-linked membrane in a non-solvent coagulation bath to elute the solvent and cure it into a membrane to obtain a flat nanofiltration membrane;

[0010] Or take the casting solution prepared in step S1. After the casting solution is degassed, use it as the inner layer feed solution for hollow fiber spinning; take a 0.1-2 wt.% cross-linking agent solution as the outer layer feed solution for hollow fiber spinning; extrude through a double-layer spinneret. After the extruded membrane filaments pass through an air bath, immerse them in a non-solvent coagulation bath to cure and obtain a hollow fiber nanofiltration membrane.

[0011] Preferably, the active additive in step S1 is a polymer with an amino group, including at least one of polyethyleneimine, polyallylamine, and polyvinylamine.

[0012] Preferably, the organic solvent in step S1 is at least one of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, sulfolane, and ethylene glycol.

[0013] Preferably, the cross-linking agent in the cross-linking agent solution in steps S2 and S3 includes at least one of formaldehyde, trioxane, paraformaldehyde, glutaraldehyde, and adipaldehyde, and the solvent in the cross-linking agent solution is at least one of water, methanol, and ethanol.

[0014] Preferably, the non-solvent coagulation bath in steps S2 and S3 includes 0-70 wt.% of organic solvent and 30-100 wt.% of at least one of water, methanol, or ethanol.

[0015] On the other hand, a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane prepared according to the above-mentioned preparation method.

[0016] Another method, an application of a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane prepared according to the above-mentioned preparation method in high-efficiency desalination, monovalent / divalent salt separation, and removal of micro-pollutants.

[0017] In summary, the present invention includes the following beneficial technical effects:

[0018] 1. In the present invention, by synchronizing the cross-linking reaction with non-solvent induced phase separation, a one-step film formation is achieved, avoiding the complex processes of traditional secondary surface modification (such as post-crosslinking, interfacial polymerization, etc.), significantly shortening the preparation cycle, reducing the industrial production cost. At the same time, a thin and dense cross-linked skin layer is directly formed during the phase inversion process, endowing the membrane with excellent separation accuracy.

[0019] 2. The present invention supports the preparation of two forms of flat nanofiltration membranes and hollow fiber nanofiltration membranes, and both have the feasibility of large-scale production. The double-layer spinneret design enables the coordinated reaction of the inner and outer layer feed liquids, improving the membrane performance consistency, and is applicable to fields such as water treatment, resource recovery, and biomedicine. Specific Embodiments

[0020] The following further elaborates the present invention in conjunction with embodiments.

[0021] Embodiments

[0022] Example 1

[0023] A preparation method of a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane, comprising the following steps:

[0024] 1). Take 15 wt.% of polysulfone-block-polyethyleneimine block copolymer (PSf-b-PEI), 3 wt.% of polyethyleneimine (PEI), and 82 wt.% of N-methyl-2-pyrrolidone and blend them, stir at 60 °C for 6 h to obtain a homogeneous casting solution;

[0025] 2). Take the casting solution prepared in step 1), let it stand for defoaming, use a stainless steel scraper with a slit thickness of 200 μm to scrape a flat membrane, immerse the glass plate with the liquid flat membrane in a 0.5 wt.% glutaraldehyde (GA) solution for a cross-linking reaction for 5 s, the cross-linking reaction is synchronized with the phase inversion, take out the formed cross-linked skin layer and immerse it in a deionized water coagulation bath to elute the solvent and solidify into a membrane to obtain a flat nanofiltration membrane.

[0026] It is measured that the water permeability coefficient of the flat nanofiltration membrane prepared in Example 1 is 20.41 LMH / bar, and the rejection rate of tetracycline hydrochloride is 84.7%.

[0027] The component contents and test results of the preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane in Examples 2-7 are shown in Table 1:

[0028] Table 1 Component contents and test results of the preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane in Examples 2-7

[0029]

[0030]

[0031] Example 8

[0032] A preparation method of a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane includes the following steps:

[0033] 1) Take 18 wt.% of polyethersulfone-block-polyethyleneimine block copolymer (PES-b-PEI), 6 wt.% of polyallylamine (PAA), and 76 wt.% of N,N-dimethylformamide (DMF), mix them, and stir at 60 °C for 10 h to obtain a homogeneous casting solution;

[0034] 2) Let the casting solution obtained in step 1) stand for defoaming, use a stainless steel scraper with a slit thickness of 200 μm to scrape a flat membrane, immerse the glass plate with the liquid flat membrane in a 1 wt% trioxane (Trio) solution for a cross-linking reaction for 15 s. The cross-linking reaction is carried out synchronously with phase inversion, take out the formed cross-linked skin layer and immerse it in a deionized water coagulation bath to elute the solvent and solidify it into a membrane to obtain a flat nanofiltration membrane.

[0035] The water permeability coefficient of the flat nanofiltration membrane prepared in Example 8 is measured to be 22.35 LMH / bar, and the retention rate of tylosin tartrate is 75.28%.

[0036] The component contents and test results of the preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane in Examples 9-13 are shown in Table 2:

[0037] Table 2 Component contents and test results of the preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane in Examples 9-13

[0038]

[0039]

[0040] Example 14

[0041] A preparation method of a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane includes the following steps:

[0042] 1), Take 15 wt% of polysulfone-block-polyethyleneimine block copolymer (PSf-b-PEI), 3 wt.% of polyvinylamine (PEE), and 82 wt.% of N-methylpyrrolidone (NMP), blend them, and stir for 6 h at 60 °C to obtain a homogeneous casting solution;

[0043] 2), Let the casting solution prepared in step 1) stand for defoaming to be used as the inner layer feed solution for hollow fiber spinning; the core liquid uses 90 wt.% of NMP aqueous solution and 0.5 wt% concentration of glutaraldehyde (GA) aqueous solution as the outer layer feed solution for the hollow fiber spinning solution; use a double-layer spinneret to extrude the casting solution, the feed solution and the core liquid, and the nascent membrane filaments enter the non-solvent coagulation bath through a 5 cm air bath and are solidified into a hollow fiber nanofiltration membrane.

[0044] The water permeability coefficient of the hollow fiber nanofiltration membrane prepared in Example 14 was measured to be 27.42 LMH / bar, and the 2 rejection rate was 68.27%.

[0045] The component contents and test results of the preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane in Examples 15-20 are shown in Table 3:

[0046] Table 3 Component contents and test results of the preparation method of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane in Examples 15-20

[0047]

[0048]

[0049] Example 21

[0050] A preparation method of a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane, comprising the following steps:

[0051] 1), Take 18 wt.% of polyethersulfone-block-polyethyleneimine block copolymer (PES-b-PEI), 6 wt.% of polyethyleneimine (PEI), and 76 wt.% of N,N-dimethylacetamide (DMAc), blend them, and stir for 6 h at 60 °C to obtain a homogeneous casting solution;

[0052] 2), Let the casting solution prepared in step 1) stand for defoaming to be used as the inner layer feed solution for hollow fiber spinning; the core liquid uses 80 wt.% of DMAc aqueous solution and 1 wt.% concentration of glutaraldehyde (GA) aqueous solution as the outer layer feed solution for the hollow fiber spinning solution; use a double-layer spinneret to extrude the casting solution, the feed solution and the core liquid, and the nascent membrane filaments enter the non-solvent coagulation bath through a 5 cm air bath and are solidified into a hollow fiber nanofiltration membrane.

[0053] The water permeability coefficient of the hollow fiber nanofiltration membrane prepared in Example 21 was measured to be 36.18 LMH / bar, the retention rate of vancomycin hydrochloride was 70.28%, and the retention rate of NaCl was 2.38%.

[0054] The component contents and test results of the preparation methods of the poly(ether)sulfone-based block copolymer integrated nanofiltration membranes in Examples 21-25 are shown in Table 4:

[0055] Table 4 Component contents and test results of the preparation methods of the poly(ether)sulfone-based block copolymer integrated nanofiltration membranes in Examples 21-25

[0056]

[0057]

[0058] The above are all preferred embodiments of the present invention. The protection scope of the present invention is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A method for preparing a poly(ether)sulfone-based block copolymer integrated nanofiltration membrane, characterized in that: The following steps are involved: S1, taking 15-28wt.% of poly(ether)sulfone-block-polyethyleneimine block copolymer and 3-15wt.% of active additive and dissolving them in 57-82wt.% of organic solvent to obtain a uniform casting solution; S2, taking the casting solution obtained in step S1, degassing the casting solution, and scraping it into a flat membrane with a scraper, immersing the liquid flat membrane in a 0.1-2wt.% cross-linking agent solution to undergo a cross-linking reaction for 5-30s, forming a cross-linked cortex on the surface of the flat membrane, and finally forming a cross-linked membrane, immersing the cross-linked membrane in a non-solvent coagulation bath to elute the solvent and solidify the membrane to obtain a flat nanofiltration membrane; Or take the casting solution prepared in step S1, and use it as the inner layer material solution for hollow fiber spinning after degassing; take 0.1-2wt.% crosslinking agent solution as the outer layer material solution for hollow fiber spinning; extrude it through a double-layer spinneret, and after the extruded membrane fibers are passed through an air bath, they are immersed in a non-solvent coagulation bath for solidification to obtain a hollow fiber nanofiltration membrane.

2. The method for preparing the integrated nanofiltration membrane of poly(ether)sulfone-based block copolymer according to claim 1, characterized in that: The active additive in step S1 is a polymer having an amino group, including at least one of polyethyleneimine, polyallylamine, and polyethyleneamine.

3. The method for preparing the integrated nanofiltration membrane of poly(ether)sulfone-based block copolymer according to claim 1, characterized in that: The organic solvent in step S1 is at least one of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, cyclopentane, and ethylene glycol.

4. The method for preparing the integrated nanofiltration membrane of poly(ether)sulfone-based block copolymer according to claim 1, characterized in that: The crosslinking agent in the crosslinking agent solution in steps S2 and S3 includes at least one of formaldehyde, trioxymethylene, polyformaldehyde, glutaraldehyde, and adipaldehyde, and the solvent in the crosslinking agent solution is at least one of water, methanol, and ethanol.

5. The method for preparing the integrated nanofiltration membrane of poly(ether)sulfone-based block copolymer according to claim 3, characterized in that: The non-solvent coagulation bath in steps S2 and S3 includes 0-70 wt.% of an organic solvent and 30-100 wt.% of at least one of water, methanol or ethanol.

6. An integrated nanofiltration membrane of a poly(ether)sulfone-based block copolymer obtained according to any one of the preparation methods of claims 1-5.

7. Use of the poly(ether)sulfone-based block copolymer integrated nanofiltration membrane according to claim 6 in efficient desalination, mono / divalent salt separation, and removal of micropollutants.

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