Preparation method and use of hollow fiber nanofiltration membrane with hydrophobic microporous membrane as support membrane

Abstract

A preparation method and use of a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane, relating to the technical field of membranes. A hydrophobic base membrane having strong chemical resistance is provided as a support membrane. In the preparation process, first, the base membrane undergoes diazotization treatment with polyaniline to achieve hydrophilic modification, the modified membrane is then immersed in a polyamine aqueous phase solution, and excess water on the surface is removed by using an air knife; then, the membrane is immersed into an oil phase solution containing polyacyl chloride, so as to form a nanofiltration functional layer; and finally, by means of cleaning with an oil phase solvent and heat treatment, unreacted monomers are removed and the structure of the membrane is stabilized.

Description

Preparation method of hollow fiber nanofiltration membrane with hydrophobic microporous membrane as support membrane and use thereof Technical Field

[0001] The present invention belongs to the field of membrane technology, and in particular relates to a preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane and application thereof. Background Art

[0002] Nanofiltration, a membrane separation technology, has been widely used in water treatment, food processing, pharmaceuticals, and chemical industries. Nanofiltration membranes are primarily used to remove multivalent ions and small organic molecules from water while retaining monovalent ions and water molecules.

[0003] Traditional nanofiltration membranes primarily utilize flat or spiral-wound structures. Hollow fiber nanofiltration membranes have attracted significant attention in recent years due to their high surface area to volume ratio, lower pressure loss, and ease of modularization and scalable production. However, hollow fiber nanofiltration membranes currently have shortcomings in chemical stability and flux performance, limiting their application in some harsh conditions. Technical issues

[0004] Traditional nanofiltration membrane support materials, such as polyethersulfone and polysulfone, while exhibiting good separation performance under normal conditions, are susceptible to chemical degradation in extreme solvent environments, impacting their service life and stability. Furthermore, the preparation of these materials requires the use of large amounts of organic solvents, which not only increases production costs but also poses environmental concerns. Technical Solutions

[0005] In response to the above-mentioned problems existing in the prior art, the purpose of the present invention is to design and provide a technical solution for a preparation method of a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane and its use. It provides a hydrophobic base membrane with strong chemical resistance as a support layer, and through a special surface modification technology, it gives the nanofiltration membrane excellent chemical stability and high flux performance. This new nanofiltration membrane is not only suitable for conventional water treatment applications, but can also operate stably in more harsh chemical environments, providing new possibilities for the further development and application of nanofiltration technology.

[0006] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized by comprising the following steps:

[0007] 1) mixing at least one polyaniline monomer with a hydrochloric acid solution to obtain a solution A; mixing sodium nitrite with the hydrochloric acid solution to obtain a solution B, wherein the temperature of the solutions A and B are controlled at 0-5° C. and the pH is 1;

[0008] 2) Providing a hydrophobic base film with strong chemical resistance, wetting the base film with ethanol and immersing it in solution A, removing it and removing excess water; then immersing the base film in solution B to complete the hydrophilic modification of the base film;

[0009] 3) mixing at least one polyamine monomer with deionized water to obtain an aqueous phase solution; mixing at least one polyacyl chloride monomer with an organic solvent to obtain an oil phase solution;

[0010] 4) Immerse the modified base film in the aqueous solution and remove excess water after taking it out:

[0011] 5) Immersing the base membrane immersed in step 4) in the oil phase solution, taking it out and drying it in an oven to obtain a hollow fiber nanofiltration membrane.

[0012] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 1): the polyaniline monomer is at least one of p-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, benzyl diamine and 2,2'-benzidine disulfonic acid, the content of the polyaniline monomer in solution A is 0.4-1.1% (w / v), preferably 0.5-0.7% (w / v); the content of sodium nitrite in solution B is twice the molar amount of the amine monomer.

[0013] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 2), the hydrophobic base membrane with strong chemical resistance is polyphenylene sulfide or polytetrafluoroethylene.

[0014] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 2), the basement membrane is immersed in solution A for 5 to 15 minutes, preferably 8 to 10 minutes; and the basement membrane is then immersed in solution B for 2 to 5 minutes.

[0015] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 3), the polyamine monomer is at least one of piperazine, m-phenylenediamine, and triethylenetetramine.

[0016] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 3), the polyacyl chloride monomer is at least one of trimesoyl chloride, terephthaloyl chloride and isophthaloyl chloride.

[0017] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 3), the organic solvent is at least one of hexane, cyclohexane, and Isopar-G.

[0018] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 3): the content of the polyamine monomer in the aqueous phase solution is 0.2-2% (w / v), preferably 0.5-1.5% (w / v), more preferably 1-1.2% (w / v); the content of the polyacyl chloride monomer in the oil phase solution is 0.05-0.5% (w / v), preferably 0.1-0.4% (w / v), more preferably 0.1-0.2% (w / v).

[0019] The method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is characterized in that in step 4), the immersion time is 1 to 10 minutes, preferably 4 to 6 minutes; and in step 5), the immersion time is 0.5 to 5 minutes, preferably 1 to 3 minutes.

[0020] The hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane is used in the fields of water treatment, food processing, pharmaceuticals, and chemical industry, preferably in harsh chemical environments. Beneficial effects

[0021] The above-mentioned method for preparing a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane can prepare a hollow fiber nanofiltration membrane with high flux, high retention rate and high stability, without the need for complex post-processing, simplifying the preparation process, saving energy and resources, and reducing costs and pollution. The preparation method of the present invention utilizes polyvalent aniline diazotization of the intermediate layer hydrophilic modified polyphenylene sulfide or polytetrafluoroethylene microporous membrane, which helps to form a thinner, more uniform and denser active layer, thereby improving the performance of the nanofiltration membrane and significantly increasing the flux; the preparation method of the present invention utilizes the condensation reaction of polyvalent acyl chloride and polyvalent aniline to form a polyamide active layer on the surface and pores of the polyphenylene sulfide or polytetrafluoroethylene microporous membrane. The active layer has good separation performance and chemical stability, and can effectively remove pollutants such as organic matter, multivalent ions, microorganisms, viruses, etc. in water, while retaining monovalent ions and nutrients in the water. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Type your figure caption description paragraph here. Best Mode for Carrying Out the Invention

[0023] Type here the best mode description paragraph of the invention. Modes for Carrying Out the Invention

[0024] The present invention is described clearly and completely below with reference to specific embodiments. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention. Example

[0025] 1) Mix p-phenylenediamine monomer with hydrochloric acid solution to obtain 0.25% (w / v) solution A; mix sodium nitrite with hydrochloric acid solution to obtain 0.15% (w / v) solution B. Control the temperature of solution A and solution B at 0-5°C.

[0026] 2) After the polyphenylene sulfide (PPS) base membrane was moistened with ethanol, it was immersed in solution A for 5 minutes, removed and excess water was removed, and then immersed in solution B for 2 minutes to complete the hydrophilic modification of the base membrane;

[0027] 3) Mixing piperazine monomer with deionized water to obtain a 0.5% (w / v) aqueous solution; mixing trimesoyl chloride monomer with cyclohexane to obtain a 0.05% (w / v) oil solution;

[0028] 4) immersing the polyphenylene sulfide (PPS) base film modified in step 2) in the aqueous solution for 2 minutes, then removing the film and removing excess water;

[0029] 5) The base membrane immersed in step 4) was immersed in the oil phase solution for 0.5 minutes, then taken out and dried in a 55° C. oven for 4 minutes to obtain a hollow fiber nanofiltration membrane. Example

[0030] 1) Mix diphenylamine monomer with hydrochloric acid solution to obtain 0.7% (w / v) solution A; mix sodium nitrite with hydrochloric acid solution to obtain 0.15% (w / v) solution B. Control the temperature of solution A and solution B between 0 and 5°C.

[0031] 2) After the polytetrafluoroethylene (PTFE) base membrane is moistened with ethanol, it is immersed in solution A for 10 minutes, removed and excess water is removed, and then immersed in solution B for 4 minutes to complete the hydrophilic modification of the base membrane;

[0032] 3) Mixing triethylenetetramine monomer with deionized water to obtain a 2% (w / v) aqueous solution; mixing isophthaloyl chloride monomer with n-hexane to obtain a 0.15% (w / v) oil solution;

[0033] 4) immersing the modified polytetrafluoroethylene (PTFE) base membrane in the aqueous solution for 3 minutes, then removing it and removing excess water;

[0034] 5) The base membrane immersed in step 4) was immersed in the oil phase solution for 1 minute, then taken out and dried in a 60° C. oven for 3 minutes to obtain a hollow fiber nanofiltration membrane. Example

[0035] 1) Mix 9,9-bis(4-aminophenyl)fluorene monomer with hydrochloric acid solution to obtain 1% (w / v) solution A; mix sodium nitrite with hydrochloric acid solution to obtain 0.2% (w / v) solution B. Control the temperature of solution A and solution B between 0 and 5°C.

[0036] 2) After the polytetrafluoroethylene (PTFE) base membrane is moistened with ethanol, it is immersed in solution A for 12 minutes, removed and excess water is removed, and then immersed in solution B for 6 minutes to complete the hydrophilic modification of the base membrane;

[0037] 3) Mix m-phenylenediamine monomer with deionized water to obtain a 2% (w / v) aqueous solution; mix trimesoyl chloride monomer with Isopar-G to obtain a 0.2% (w / v) oil solution;

[0038] 4) immersing the modified polytetrafluoroethylene (PTFE) base membrane in the aqueous solution for 4 minutes, then removing the membrane and removing excess water;

[0039] 5) The base membrane immersed in step 4) was immersed in the oil phase solution for 2 minutes, then taken out and placed in a 60° C. oven to dry for 3 minutes to obtain a hollow fiber nanofiltration membrane. Example

[0040] 1) Mix 2,2'-benzidine disulfonic acid monomer with hydrochloric acid solution to obtain 0.5% (w / v) solution A; mix sodium nitrite with hydrochloric acid solution to obtain 0.12% (w / v) solution B. Control the temperature of solution A and solution B between 0 and 5°C.

[0041] 2) After the polyphenylene sulfide (PPS) base membrane was moistened with ethanol, it was immersed in solution A for 15 minutes, removed and excess water was removed, and then immersed in solution B for 7 minutes to complete the hydrophilic modification of the base membrane;

[0042] 3) Mix piperazine monomer with deionized water to obtain a 3% (w / v) aqueous solution; mix trimesoyl chloride monomer with n-hexane to obtain a 0.2% (w / v) oil solution;

[0043] 4) immersing the polyphenylene sulfide (PPS) base film modified in step 2) in the aqueous solution for 3 minutes, then removing the film and removing excess water;

[0044] 5) The base membrane immersed in step 4) was immersed in the oil phase solution for 1.5 minutes, then taken out and dried in a 60° C. oven for 3 minutes to obtain a hollow fiber nanofiltration membrane. Example

[0045] 1) Mix p-phenylenediamine monomer with hydrochloric acid solution to obtain 1% (w / v) solution A; mix sodium nitrite with hydrochloric acid solution to obtain 0.3% (w / v) solution B. Control the temperature of solution A and solution B between 0 and 5°C.

[0046] 2) After the polyphenylene sulfide (PPS) base membrane was moistened with ethanol, it was immersed in solution A for 15 minutes, removed and excess water was removed, and then immersed in solution B for 7 minutes to complete the hydrophilic modification of the base membrane;

[0047] 3) Mixing triethylenetetramine with deionized water to obtain a 3% (w / v) aqueous solution; mixing trimesoyl chloride monomer with cyclohexane to obtain a 0.2% (w / v) oil solution;

[0048] 4) immersing the polyphenylene sulfide (PPS) base film modified in step 2) in the aqueous solution for 4 minutes, then removing the film and removing excess water;

[0049] 5) The base membrane immersed in step 4) was immersed in the oil phase solution for 2 minutes, then taken out and placed in a 60° C. oven to dry for 3 minutes to obtain a hollow fiber nanofiltration membrane. Example

[0050] 1) Mix diphenylamine monomer with hydrochloric acid solution to obtain 1% (w / v) solution A; mix sodium nitrite with hydrochloric acid solution to obtain 0.2% (w / v) solution B. Control the temperature of solution A and solution B between 0 and 5°C.

[0051] 2) After the polytetrafluoroethylene (PTFE) base membrane is moistened with ethanol, it is immersed in solution A for 20 minutes, removed and excess water is removed, and then immersed in solution B for 10 minutes to complete the hydrophilic modification of the base membrane;

[0052] 3) Piperazine was mixed with deionized water to obtain a 4% (w / v) aqueous solution; trimesoyl chloride monomer was mixed with Isopar-G to obtain a 0.25% (w / v) oil solution;

[0053] 4) immersing the modified polytetrafluoroethylene (PTFE) base membrane in the aqueous solution for 5 minutes, then removing the membrane and removing excess water;

[0054] 5) The base membrane immersed in step 4) was immersed in the oil phase solution for 2 minutes, then taken out and placed in a 60° C. oven to dry for 3 minutes to obtain a hollow fiber nanofiltration membrane.

[0055] The beneficial effects of the present invention are further demonstrated below by corresponding performance test data, as shown in Tables 1 and 2. The flux in Table 1 was measured at a pressure of 0.1 MPa using deionized water as the permeation medium, and the retention rate was measured at a pressure of 0.1 MPa using a 200 mg / L bovine serum albumin solution as the permeation medium. The flux in Table 2 was measured at a pressure of 0.6 MPa using deionized water as the permeation medium, and the retention rate in Table 2 was measured at a pressure of 0.6 MPa using a 2000 mg / L sodium sulfate solution as the permeation medium.

[0056] Table 1 Performance test table of modified hollow fiber base membranes prepared in Examples 1-6

[0057] Example Flux (LMH / bar) Bovine serum albumin retention (%) 133694.5231895.6330995.8429096.4529897.3628597.0

[0058] Table 2 Performance test table of hollow fiber nanofiltration membranes prepared in Examples 1-6

[0059] Example Flux (LMH / bar) Sodium sulfate rejection (%) 19.697.5211.395.636.898.849.497.257.698.3610.296.7

[0060] Table 1-2 shows that the hollow fiber nanofiltration membranes prepared in Examples 1-6 exhibit high flux and retention rates, demonstrating excellent separation performance. Furthermore, for the composite membrane prepared in Example 3, after 72 hours of operation in a pure n-hexane solvent environment, its flux attenuation was minimal and it maintained a high retention rate for dye molecules.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents. Industrial Applicability

[0062] Type your industrial applicability description paragraph here. Sequence Listing Free Content

[0063] Type your sequence listing free description paragraph here.

Claims

1. A preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane, characterized in that It includes the following steps: 1) Mix at least one polyaniline monomer with a hydrochloric acid solution to obtain solution A; Mix sodium nitrite with a hydrochloric acid solution to obtain solution B, control the temperatures of solution A and solution B at 0 - 5°C, and pH = 1; 2) Provide a hydrophobic substrate membrane with strong chemical resistance. After wetting the substrate membrane with ethanol, immerse it in solution A, take it out and remove the excess moisture; then immerse the above substrate membrane in solution B to complete the hydrophilic modification of the substrate membrane; 3) Mix at least one polyamine monomer with deionized water to obtain an aqueous solution; mix at least one polyacyl chloride monomer with an organic solvent to obtain an oil-phase solution; 4) Immerse the substrate membrane modified in step 2) in the aqueous solution, take it out and remove the excess moisture: 5) Immerse the substrate membrane immersed in step 4) in the oil-phase solution, take it out and place it in an oven for drying to obtain a hollow fiber nanofiltration membrane.

2. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 1): The polyaniline monomer is at least one of p-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, benzidine, and 2,2'-benzidine disulfonic acid. The content of the polyaniline monomer in solution A is 0.4 - 1.1%, preferably 0.5 - 0.7%; the content of sodium nitrite in solution B is twice the molar amount of the amine monomer.

3. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 2): The hydrophobic substrate membrane with strong chemical resistance is polyphenylene sulfide or polytetrafluoroethylene.

4. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 2): The time for the substrate membrane to be immersed in solution A is 5 - 15 min, preferably 8 - 10 min; the time for the substrate membrane to be immersed in solution B again is 2 - 5 min.

5. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 3): The polyamine monomer is at least one of piperazine, m-phenylenediamine, and triethylenetetramine.

6. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 3): The polyacyl chloride monomer is at least one of trimesoyl chloride, terephthaloyl chloride, and isophthaloyl chloride.

7. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 3): The organic solvent is at least one of hexane, cyclohexane, and Isopar-G.

8. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 3): The content of the polyamine monomer in the aqueous solution is 0.2 - 2% (w / v), preferably 0.5 - 1.5% (w / v), more preferably 1 - 1.2% (w / v); the content of the polyacyl chloride monomer in the oil-phase solution is 0.05 - 0.5% (w / v), preferably 0.1 - 0.4% (w / v), more preferably 0.1 - 0.2% (w / v).

9. The preparation method of a hollow fiber nanofiltration membrane using a hydrophobic microporous membrane as a support membrane according to claim 1, characterized in that In step 4): The immersion time is 1 - 10 min, preferably 4 - 6 min; in step 5) the immersion time is 0.5 - 5 min, preferably 1 - 3 min; the drying temperature is 55 - 65°C, and the drying time is 2 - 4 min.

10. The application of a hollow fiber nanofiltration membrane with a hydrophobic microporous membrane as a support membrane according to claim 1 in the fields of water treatment, food processing, pharmaceuticals, and chemical engineering, preferably in applications in harsh chemical environments.