Self-crosslinking ultrafiltration membrane and preparation method thereof

Abstract

The present invention discloses a self-crosslinking ultrafiltration membrane, which comprises: an active monomer mixture, and the active monomer mixture reacts with 4, 4 '-dichlorodiphenyl sulfone to obtain a self-crosslinking pre-crosslinking transition layer; the pre-crosslinking transition layer forms an asymmetric structure layer on the surface of the non-woven fabric through a non-solvent phase inversion process; and immersing the asymmetric structure layer into a phosphorus pentoxide / methanesulfonic acid mixed solution, and carrying out a cross-linking reaction to obtain the cross-linked polysulfone ultrafiltration membrane containing the phenyl sulfone group. Wherein the active monomer mixture is formed by mixing side phenyl bisphenol A, sulfonated bisphenol A and bisphenol A according to a certain proportion. The invention also discloses a preparation method of the self-crosslinking ultrafiltration membrane. Through molecular structure design, the swelling effect caused by solvent permeation is inhibited, the original mechanical strength and thermal stability of the material are maintained, meanwhile, the chemical stability of the material in an organic solvent environment is remarkably improved, the service life of the membrane is prolonged, and the reliability of separation performance is ensured.

Description

Technical Field

[0001] This invention relates to a self-crosslinking ultrafiltration membrane and its preparation method. Background Technology

[0002] With the increasing demand for industrial wastewater treatment, the efficient separation of organic solvent wastewater has become a significant challenge in the environmental protection field. Ultrafiltration membranes, which are resistant to organic solvents, play a crucial role in the industrial and pharmaceutical sectors, particularly in organic solvent recovery, drug concentration, and the separation of biomolecules. In the pharmaceutical industry, they can efficiently separate solvents and solutes at room temperature, avoiding degradation of heat-sensitive drugs and significantly reducing energy consumption and solvent loss. In the industrial sector, these membrane materials, with their corrosion resistance and high-temperature resistance, are suitable for environments with strong acids, strong alkalis, and organic solvents, and are widely used in water treatment, food processing, and chemical separation. Their core advantages lie in energy saving and environmental protection, gentle operation, and compatibility with complex systems, providing a reliable solution for the purification and resource recovery of high-value-added products.

[0003] Polysulfone materials are widely used as ultrafiltration membrane materials due to their excellent mechanical strength and thermal stability. However, their molecular structure lacks cross-linking stability, making them prone to solvent permeation and swelling in organic solvent environments (especially during long-term operation at high temperatures). This leads to increased membrane pore size and a significant reduction in separation accuracy. Furthermore, prolonged contact with organic solvents accelerates material aging, reduces mechanical strength, and shortens service life. Conventional modification methods such as blending or surface coating can partially improve performance, but their effectiveness is limited and they are costly. These drawbacks severely restrict the application of ultrafiltration membranes in organic solvent enrichment scenarios such as petrochemicals and biopharmaceuticals, necessitating the development of novel solutions to expand the application scope of ultrafiltration technology.

[0004] Therefore, to address the problem of insufficient solvent resistance in existing polysulfone ultrafiltration membranes, a self-crosslinking ultrafiltration membrane and its preparation method are provided. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a self-crosslinking ultrafiltration membrane and its preparation method. Through molecular structure design, controllable crosslinking points are introduced into the polysulfone backbone to form a three-dimensional network structure, which suppresses the swelling effect caused by solvent permeation. While maintaining the original mechanical strength and thermal stability of the material, it significantly improves its chemical stability in organic solvent environments, extends membrane life, and ensures the reliability of separation performance.

[0006] The technical solution to achieve the above objectives is: One embodiment of the present invention is a self-crosslinking ultrafiltration membrane, comprising: a mixture of active monomers, The active monomer mixture is reacted with 4,4'-dichlorodiphenyl sulfone to obtain a self-crosslinkable pre-crosslinked transition layer; The pre-crosslinked transition layer forms an asymmetric structure layer on the surface of the nonwoven fabric through a non-solvent phase conversion process; The asymmetric structure layer is immersed in a mixed solution of phosphorus pentoxide / methanesulfonic acid to undergo a cross-linking reaction, resulting in a cross-linked polysulfone ultrafiltration membrane containing sulfone groups. in, The active monomer mixture is composed of side-phenyl bisphenol A, sulfonated bisphenol A, and bisphenol A polysulfone mixed in a certain proportion.

[0007] Preferably, in the active monomer mixture, the molar ratio of bisphenol A to sulfonated bisphenol A is between 1 and 100, and the molar percentage of sulfonated bisphenol A among the three monomers is between 1 and 50%.

[0008] Preferably, the pre-crosslinked transition layer is a self-crosslinkable sulfonated polysulfone copolymer containing side phenyl groups obtained by reacting the active monomer mixture with 4,4'-dichlorodiphenyl sulfone, wherein the molar ratio of the active monomer mixture to 4,4'-dichlorodiphenyl sulfone is 1:1.

[0009] Preferably, the asymmetric structural layer is formed on the surface of a nonwoven fabric by forming a porous ultrafiltration membrane with a solution of a self-crosslinkable sulfonated polysulfone copolymer containing side phenyl groups through a solvent-free phase inversion process, wherein the pore size ranges from 0.001 to 1 μm.

[0010] A method for preparing a self-crosslinking ultrafiltration membrane according to a second aspect of the present invention includes: Step S1: Mix the three monomers, side-phenyl bisphenol A, sulfonated bisphenol A and bisphenol A polysulfone, in a certain proportion to form an active monomer mixture. Step S2: The active monomer mixture is heated and stirred with potassium carbonate at a temperature range of 80-110°C, then refluxed and distilled. Step S3: 4,4'-dichlorodiphenyl sulfone is added to the active monomer mixture after heating and reaction, and the temperature is raised to 150-160℃ to react to the target viscosity. After washing with pure water, a self-crosslinkable sulfonated polysulfone copolymer containing side phenyl groups is obtained, namely the pre-crosslinked transition layer. Step S4, the pre-crosslinked transition layer forms a porous ultrafiltration membrane, i.e. an asymmetric structure layer, on the surface of the nonwoven fabric through a non-solvent phase conversion process; Step S5: Immerse the asymmetric structure layer in a mixed solution of phosphorus pentoxide / methanesulfonic acid at a reaction temperature between 40-100°C to carry out a crosslinking reaction and obtain a crosslinked polysulfone ultrafiltration membrane containing sulfone groups.

[0011] Preferably, in step S1, the molar ratio of bisphenol A to sulfonated bisphenol A is between 1 and 100, and the molar percentage of sulfonated bisphenol A among the three monomers is between 1 and 50%.

[0012] Preferably, in step S2, the molar ratio of the active monomer mixture to potassium carbonate is 1:1.1-1.3.

[0013] Preferably, in step S3, the molar ratio of the active monomer mixture to 4,4'-dichlorodiphenyl sulfone is 1:1.

[0014] Preferably, in step S4, the pore size of the porous ultrafiltration membrane is between 0.001 and 1 μm.

[0015] Compared with the prior art, the beneficial effects of the present invention are: the sulfone-based cross-linked chemical structure prepared by the present invention effectively prevents the penetration of organic solvents, significantly reduces the swelling rate, enhances the separation accuracy and flux stability, maintains high mechanical strength, and extends service life. In addition, this technology expands the application potential of ultrafiltration membranes in the treatment of organic solvent wastewater in chemical, pharmaceutical and other fields, and provides an economical and feasible solution for the efficient separation of industrial wastewater. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the chemical structure of the cross-linked polysulfone ultrafiltration membrane containing sulfone groups in this invention; Figure 2 This is a schematic diagram of the chemical structure of the self-crosslinkable sulfonated polysulfone copolymer containing side phenyl groups in this invention; Figure 3 This is a schematic diagram of the chemical structure of the lateral phenyl bisphenol A in this invention; Figure 4 This is a schematic diagram of the chemical structure of sulfonated bisphenol A in this invention; Figure 5 This is a schematic diagram of the chemical structure of bisphenol A in this invention; Figure 6 This is a schematic diagram of the chemical structure of 4,4'-dichlorodiphenyl sulfone in this invention; Figure 7 This is a flowchart of a self-crosslinking ultrafiltration membrane preparation method according to the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] A self-crosslinking ultrafiltration membrane, the chemical structure of its crosslinking network being, for example Figure 1 As shown, it includes: a mixture of active monomers. A mixture of active monomers was reacted with 4,4'-dichlorodiphenyl sulfone to obtain a self-crosslinkable pre-crosslinked transition layer; The pre-crosslinked transition layer forms an asymmetric structure layer on the surface of the nonwoven fabric through a non-solvent phase inversion process; The asymmetric structure layer is immersed in a mixed solution of phosphorus pentoxide / methanesulfonic acid to carry out a cross-linking reaction, resulting in a cross-linked polysulfone ultrafiltration membrane containing sulfone groups. in, The active monomer mixture is a mixture of p-phenyl bisphenol A, sulfonated bisphenol A, and bisphenol A polysulfone in a certain proportion. The chemical structures of p-phenyl bisphenol A, sulfonated bisphenol A, and bisphenol A are as follows: Figure 3-5 As shown, the molar ratio of bisphenol A to sulfonated bisphenol A ranges from 1 to 100, and the molar percentage of sulfonated bisphenol A among the three monomers ranges from 1 to 50%.

[0019] In the embodiments, the pre-crosslinked transition layer is obtained by reacting a mixture of active monomers with 4,4'-dichlorodiphenyl sulfone to obtain a self-crosslinkable sulfonated polysulfone copolymer containing side-phenyl groups, wherein the chemical structure of the self-crosslinkable sulfonated polysulfone copolymer containing side-phenyl groups is as follows: Figure 2 As shown, the molar ratio of the active monomer mixture to 4,4'-dichlorodiphenyl sulfone is 1:1. The chemical structure of 4,4'-dichlorodiphenyl sulfone is as follows. Figure 6 As shown.

[0020] In the embodiments, the asymmetric structure layer is formed by forming a porous ultrafiltration membrane on the surface of a nonwoven fabric through a non-solvent phase inversion process using a self-crosslinkable sulfonated polysulfone copolymer solution containing side phenyl groups, wherein the pore size ranges from 0.001 to 1 μm.

[0021] like Figure 7 As shown, a method for preparing a self-crosslinking ultrafiltration membrane includes: Step S1 involves mixing three monomers—side-phenyl bisphenol A, sulfonated bisphenol A, and bisphenol A polysulfone—in a certain proportion to form an active monomer mixture.

[0022] In the examples, the molar ratio of bisphenol A to sulfonated bisphenol A ranges from 1 to 100, and the molar percentage of sulfonated bisphenol A among the three monomers ranges from 1 to 50%.

[0023] Step S2: The active monomer mixture is heated and stirred with potassium carbonate at a temperature range of 80-110°C, then refluxed and distilled.

[0024] In the examples, the molar ratio of the active monomer mixture to potassium carbonate was 1:1.1-1.3.

[0025] Step S3: Add 4,4'-dichlorodiphenyl sulfone to the active monomer mixture after heating and reaction, heat to 150-160℃ and react to the target viscosity, wash with pure water to obtain a self-crosslinkable sulfonated polysulfone copolymer containing side phenyl groups, i.e., a pre-crosslinked transition layer.

[0026] In the examples, the molar ratio of the active monomer mixture to 4,4'-dichlorodiphenyl sulfone was 1:1.

[0027] In step S4, the pre-crosslinked transition layer forms a porous ultrafiltration membrane, i.e., an asymmetric structure layer, on the surface of the nonwoven fabric through a non-solvent phase inversion process.

[0028] In the embodiments, the pore size of the porous ultrafiltration membrane ranges from 0.001 to 1 μm.

[0029] Step S5: Immerse the asymmetric structure layer in a mixed solution of phosphorus pentoxide / methanesulfonic acid, and carry out a cross-linking reaction at a temperature range of 40-100℃ to obtain a cross-linked polysulfone ultrafiltration membrane containing sulfone groups.

[0030] Experiments showed that uncrosslinked ultrafiltration membranes completely dissolved after immersion in polar solvents such as ethanol and DMF for 10 minutes, with a weight loss rate of 100%; while crosslinked ultrafiltration membranes only lost 3% of their weight after immersion in polar solvents for 10 minutes. This indicates that the polysulfone membrane was effectively crosslinked, resulting in a significant improvement in stability.

[0031] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-crosslinking ultrafiltration membrane, characterized by, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

2. The self-crosslinking ultrafiltration membrane according to claim 1, characterized in that, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

3. The self-crosslinking ultrafiltration membrane according to claim 1, characterized in that, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

4. The self-crosslinking ultrafiltration membrane according to claim 1, characterized in that, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

5. A method for producing a self-crosslinking ultrafiltration membrane, characterized by, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups. The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

6. The method for preparing a self-crosslinking ultrafiltration membrane according to claim 5, characterized in that, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

7. The method for preparing a self-crosslinking ultrafiltration membrane according to claim 5, characterized in that, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

8. The method for preparing a self-crosslinking ultrafiltration membrane according to claim 5, characterized in that, The application relates to a preparation method of a cross-linked polysulfone ultrafiltration membrane containing benzene sulfone groups.

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