Filtering membrane as well as preparation method and application thereof

Abstract

The invention belongs to the field of membrane materials, and particularly discloses a filtering membrane and a preparation method and application thereof, the filtering membrane comprises a base membrane and a hydrophobic coating arranged on the base membrane; the hydrophobic coating contains composite microspheres; the composite microsphere comprises a lignin nanosphere and a polydopamine layer coated on the surface of the lignin nanosphere; the surface of the polydopamine layer is grafted with an SR group; sulfur atoms in the SR group are connected with the polydopamine layer through chemical bonds; r in the SR group is selected from C10-C30 alkyl groups. According to the filtering membrane, the hydrophobic coating is introduced, so that the filtering membrane has super-hydrophobicity, the super-hydrophobic surface enables the filtering membrane to have the synergistic effect of scale prevention and deoxidation, meanwhile, mass transfer of dissolved oxygen to the metal surface is effectively blocked through the gas membrane layer between solid-liquid interfaces, and the corrosion rate is obviously reduced physically.

Description

Technical Field

[0001] This invention belongs to the field of membrane material technology, specifically relating to a filter membrane, its preparation method, and its application. Background Technology

[0002] High-voltage direct current transmission is a key technology for building new power systems and achieving energy optimization. As its core equipment, the converter valve generates a large amount of heat during operation and must rely on a closed internal cooling water system for precise cooling to ensure its safety and reliability. However, this cooling system has long faced three stubborn challenges: (1) Scaling problem: When the cooling water flows through the valve body, it is heated, causing the dissolved inorganic salts (such as calcium and magnesium salts) in the water to become supersaturated and precipitate, adhering to the surface of pipes and components to form scale. The scale layer not only significantly reduces the heat transfer efficiency, causing the valve body to overheat, but may also cause local corrosion, seriously threatening the safety of the system; (2) Microbial growth problem: The suitable temperature of the cooling system provides an ideal growth environment for microorganisms (such as bacteria and algae). Microorganisms multiply in large numbers and secrete extracellular polymers to form biological slime. Biological slime not only blocks precision flow channels, but its metabolic products also aggravate the under-deposit corrosion of system materials, which is one of the main causes of equipment failure; (3) Dissolved oxygen corrosion problem: Dissolved oxygen in the water is the primary factor causing electrochemical corrosion of metal materials such as carbon steel and copper in the system. Continuous oxygen corrosion can lead to equipment perforation, corrosion products peeling off and clogging of the system, and the scaling process can be further aggravated by the catalytic effect of corrosion products (such as iron ions).

[0003] Currently, the conventional solution to the above problems mainly involves adding chemical agents to the cooling water, such as scale inhibitors, bactericides, and oxygen scavengers. However, this "chemical approach" has significant drawbacks: First, the continuous addition of chemical agents leads to high operating costs and requires strict monitoring of water quality; second, there is a risk of secondary pollution caused by excessive dosage or decomposition products; more importantly, some bactericides (such as oxidizing bactericides) may react antagonistically with corrosion inhibitors and scale inhibitors, thereby reducing the overall treatment effect.

[0004] Therefore, there is an urgent need in this field to develop a solution that can solve at least one of the above-mentioned technical problems, so as to fundamentally break through the existing technical bottlenecks and provide a green, long-lasting, and reliable integrated protection solution for converter valves and even a wider range of industrial cooling systems. Summary of the Invention

[0005] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide a filter membrane that is superhydrophobic, can prevent scale in water treatment, and remove dissolved oxygen in water, thereby solving the problems of secondary pollution, low efficiency and single function of the existing converter valve cooling system using chemical agents and single-function membrane technology.

[0006] The second objective of this invention is to provide a method for preparing a filter membrane.

[0007] The third objective of this invention is to provide a water cooling system.

[0008] The fourth objective of this invention is to provide the application of the above-mentioned filter membrane in the field of water treatment.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a filter membrane comprising a base membrane and a hydrophobic coating disposed on the base membrane; the hydrophobic coating comprising composite microspheres; The composite microspheres include lignin nanospheres and a polydopamine layer coating the surface of the lignin nanospheres; the surface of the polydopamine layer is grafted with SR groups; The sulfur atom in the SR group is chemically bonded to the polydopamine layer; the R in the SR group is selected from C. 10 ~C 30 Alkyl groups.

[0010] In some embodiments of the present invention, the number of carbon atoms in R is selected from any value of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or a range formed by any two.

[0011] In some embodiments of the present invention, R is selected from C. 15 ~C 20 Alkyl groups.

[0012] In some embodiments of the present invention, R is C. 18 Alkyl groups.

[0013] In some embodiments of the present invention, the hydrophobic coating further contains an antibacterial agent and a binder.

[0014] In some embodiments of the present invention, the antibacterial agent is selected from at least one of chitosan quaternary ammonium salt and chitosan.

[0015] In some embodiments of the present invention, the adhesive is selected from at least one of polyvinylpyrrolidone, polyacrylamide, sodium carboxymethyl cellulose, and guar gum.

[0016] In some embodiments of the present invention, the mass ratio of the composite microspheres to the antibacterial agent in the hydrophobic coating is 1:(0.3~0.5); in some embodiments of the present invention, the mass ratio of the composite microspheres to the antibacterial agent in the hydrophobic coating is any value of 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5 or a range formed by any two of these values.

[0017] In some embodiments of the present invention, the mass ratio of the composite microspheres to the binder in the hydrophobic coating is 1:(1.5~2.5); in some embodiments of the present invention, the mass ratio of the composite microspheres to the binder in the hydrophobic coating is any value or a range formed by any two of the following: 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5.

[0018] In some embodiments of the present invention, the base film includes at least one of polyacrylonitrile base film, polyethersulfone base film, and polysulfone base film.

[0019] In some embodiments of the present invention, the composite microspheres are prepared by a method comprising the following steps: The lignin nanosphere dispersion was polymerized with dopamine hydrochloride to obtain lignin nanospheres coated with a polydopamine layer. The composite microspheres are obtained by grafting RSH onto the polydopamine-coated lignin nanospheres. The R in RSH is selected from C. 10 ~C 30 Alkyl groups.

[0020] This invention uses a polymerization reaction to polymerize dopamine hydrochloride in situ on the surface of lignin nanospheres to form a polydopamine layer. Then, through a grafting reaction, RSH is dehydrogenated and grafted onto the surface of the polydopamine layer, thereby forming composite microspheres.

[0021] In some embodiments of the present invention, the lignin nanosphere dispersion is prepared by dissolving lignin in an organic solvent, then adding water dropwise, and then heating and evaporating to remove the organic solvent.

[0022] In some embodiments of the present invention, the volume ratio of organic solvent to water is (5~8):3; in some embodiments of the present invention, the volume ratio of organic solvent to water is any value of 5:3, 6:3, 7:3, 8:3 or a range formed by any two of them.

[0023] In some embodiments of the present invention, the temperature of the heating and evaporation is 70~90°C.

[0024] In some embodiments of the present invention, the heating and evaporation process takes 5 to 10 hours.

[0025] In some embodiments of the present invention, the organic solvent includes ethyl acetate.

[0026] In some embodiments of the present invention, the step of causing the lignin nanosphere dispersion to undergo a polymerization reaction with dopamine hydrochloride specifically involves: mixing dopamine hydrochloride with the lignin nanosphere dispersion, then adding alkali solution to adjust the pH to 8-10, adding a pH buffer, and obtaining the lignin nanospheres coated with the polydopamine layer after the reaction.

[0027] In some embodiments of the present invention, the pH buffer is a Tris buffer solution.

[0028] In some embodiments of the present invention, the polymerization reaction time is 18 to 30 hours; in some embodiments of the present invention, the polymerization reaction time is any value of 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, or a range formed by any two of these values.

[0029] In some embodiments of the present invention, the temperature of the grafting reaction is 35~50°C; in some embodiments of the present invention, the temperature of the grafting reaction is any value of 35°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C or a range formed by any two of them.

[0030] In some embodiments of the present invention, the grafting reaction time is 10-30 h; in some embodiments of the present invention, the grafting reaction time is any value of 10 h, 12 h, 14 h, 15 h, 18 h, 20 h, 22 h, 24 h, 26 h, 28 h, 30 h, or a range formed by any two of these values.

[0031] In some embodiments of the present invention, the water contact angle of the filter membrane is not less than 150°; in some embodiments of the present invention, the water contact angle of the filter membrane is 150°~160°.

[0032] In some embodiments of the present invention, the antibacterial rate of the filter membrane is not less than 99%.

[0033] In some embodiments of the present invention, the filter membrane has an inhibition rate of not less than 99% against Escherichia coli.

[0034] In some embodiments of the present invention, the filter membrane has an inhibition rate of not less than 99% against Staphylococcus aureus.

[0035] In some embodiments of the present invention, the filtration membrane has a removal rate of dissolved oxygen in water of not less than 90%.

[0036] The filter membrane of this invention has superhydrophobic, antibacterial and physical deoxygenation properties, and can simultaneously achieve scale prevention, microbial inhibition and corrosion protection. It is particularly suitable for key fields such as high voltage DC transmission converter valves, chemical circulating cooling systems and precision instrument cooling devices. It can simultaneously achieve scale prevention, antibacterial and physical deoxygenation of cooling water, and the raw materials are green and the preparation process is simple. The second aspect of the present invention provides a method for preparing the filter membrane described in the first aspect of the present invention, comprising the following steps: The filter membrane is prepared by loading the raw materials for the hydrophobic coating onto the surface of the base membrane and then heat-curing it.

[0037] In some embodiments of the present invention, the raw materials for preparing the hydrophobic coating include composite microspheres.

[0038] In some embodiments of the present invention, the raw materials for preparing the hydrophobic coating also include antibacterial agents and binders.

[0039] In some embodiments of the present invention, the raw materials for preparing the hydrophobic coating also include a solvent.

[0040] In some embodiments of the present invention, the solvent includes water and ethanol.

[0041] In some embodiments of the present invention, the volume ratio of water to ethanol is 1:(0.8~1.2); in some embodiments of the present invention, the volume ratio of water to ethanol is any value of 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2 or a range formed by any two of them.

[0042] In some embodiments of the present invention, the raw materials for preparing the hydrophobic coating refer to the mixture of composite microspheres, antibacterial agent, binder and solvent, followed by ultrasonication.

[0043] In some embodiments of the present invention, the load is achieved by immersion or coating.

[0044] In some embodiments of the present invention, the step of loading the substrate film surface with the raw materials for preparing the hydrophobic coating specifically involves immersing the substrate film in a mixture of raw materials for preparing the hydrophobic coating, and then lifting it out.

[0045] In some embodiments of the present invention, the lifting and extraction speed is 1~5 mm / s; in some embodiments of the present invention, the lifting and extraction speed is any value of 1 mm / s, 2 mm / s, 3 mm / s, 4 mm / s, 5 mm / s, or a range formed by any two of them.

[0046] In some embodiments of the present invention, the step of loading the substrate film surface with the raw materials for preparing the hydrophobic coating specifically involves coating the substrate film surface with a mixture of raw materials for preparing the hydrophobic coating.

[0047] In some embodiments of the present invention, the preparation method further includes a drying step; the drying step is located before the heat treatment curing step and after the step of loading the raw materials for preparing the hydrophobic coating onto the surface of the base film.

[0048] In some embodiments of the present invention, the drying temperature is 40~60°C; in some embodiments of the present invention, the drying temperature is any value of 40°C, 45°C, 50°C, 55°C, 60°C, or a range formed by any two of them.

[0049] In some embodiments of the present invention, the drying time is 20 to 40 minutes; in some embodiments of the present invention, the drying time is any value of 20 minutes, 30 minutes, 40 minutes, or a range formed by any two of them.

[0050] In some embodiments of the present invention, the temperature during heat treatment curing is 90~110°C; in some embodiments of the present invention, the temperature during heat treatment curing is any value of 90°C, 95°C, 100°C, 105°C, 110°C, or a range formed by any two of them.

[0051] In some embodiments of the present invention, the heat treatment curing time is 1.5 to 3 hours; in some embodiments of the present invention, the heat treatment curing time is any value of 1.5 hours, 2 hours, 2.5 hours, 3 hours, or a range formed by any two of them.

[0052] A third aspect of the present invention provides a water cooling system including a filter assembly; the filter assembly is provided with the filter membrane described in the first aspect of the present invention.

[0053] In some embodiments of the present invention, the water cooling system is a water cooling system for high-voltage direct current transmission converter valves, a circulating cooling system for chemical production, a medical cold chain cooling system, or a water cooling system for precision instruments.

[0054] The fourth aspect of the present invention provides the application of the filter membrane described in the first aspect of the present invention in the field of water treatment.

[0055] The beneficial effects of the present invention are as follows: the filter membrane of the present invention has superhydrophobicity (i.e., water contact angle not less than 150°) by introducing a hydrophobic coating. The superhydrophobic surface gives the filter membrane a synergistic effect of scale prevention and deoxygenation. At the same time, the spherical structure of the composite microspheres can extend the penetration path of the corrosive medium and significantly reduce the corrosion rate.

[0056] Furthermore, this invention utilizes the intrinsic antibacterial properties of antibacterial agents and lignin nanospheres to achieve broad-spectrum and highly efficient inhibition of microbial growth through a dual mechanism of physical cell disruption and positive charge adsorption. It is also environmentally friendly, produces no harmful byproducts, and effectively avoids performance degradation caused by biofouling.

[0057] The filter membrane of this invention, by adjusting the composition of the hydrophobic coating, can achieve a close combination and mutual promotion of three major functions on the base membrane: the superhydrophobic surface provides a clean interface for deoxygenation, the antibacterial properties ensure the long-term stability of the superhydrophobic and deoxygenation functions, and through the positive synergy between the functions, the protective effect and service life are significantly improved. Attached Figure Description

[0058] Figure 1 The image shows the XRD pattern of lignin nanospheres@polydopamine / octadecyl mercaptan from Example 1.

[0059] Figure 2 The ultraviolet transmission curves of the films in Example 2 and Comparative Examples 1-2 after UV radiation are shown.

[0060] Figure 3 The images show the gloss test results of the films of Example 2, Comparative Example 1, and Comparative Example 2 after UV radiation.

[0061] Figure 4 The water contact angle test diagrams are for the deoxygenation filter membrane in Example 2 and the antibacterial membranes in Comparative Examples 1-2.

[0062] Figure 5 The graph shows the dissolved oxygen concentration test results of the deoxygenation filtration membrane in Example 2 and the antibacterial membrane in Comparative Example 1. Detailed Implementation

[0063] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0064] Example 1 This example provides a method for preparing composite microspheres, specifically including the following steps: Step (1), the preparation steps of the lignin nanosphere aqueous dispersion are as follows: 0.36 g of lignin is dissolved in 90 mL of ethyl acetate (EA) under continuous stirring. During the mixing process, 210 mL of deionized water is added dropwise until the final volume ratio of water to EA is 7:3, resulting in a mixed solution. Subsequently, the mixed solution is heated to 80℃ and stirred continuously for 8 h to promote the evaporation of EA, thereby obtaining the lignin nanosphere aqueous dispersion.

[0065] Step (2), the preparation steps of lignin nanospheres@polydopamine are as follows: 0.2 g of dopamine hydrochloride is dissolved in the lignin nanosphere aqueous dispersion obtained in step (1) under continuous stirring. During the reaction, 2 mol / L NaOH solution is added dropwise to adjust the pH to 9, and Tris buffer (i.e., Tris buffer) is added as a pH buffer. After purification and drying, lignin nanospheres@polydopamine are obtained.

[0066] Step (3): The preparation steps of lignin nanospheres@polydopamine / octadecyl mercaptan are as follows: 1 g of octadecyl mercaptan was dissolved in 100 mL of ethanol at 40 °C by stirring to prepare an ethanol solution of octadecyl mercaptan; 50 mg of lignin nanospheres@polydopamine prepared in step (2) was dispersed in 100 mL of water to obtain an aqueous dispersion of lignin nanospheres@polydopamine; then the ethanol solution of octadecyl mercaptan was added to the aqueous dispersion of lignin nanospheres@polydopamine and stirred for 24 h. After centrifugation, washing, and drying, the composite microspheres in this example were obtained, denoted as lignin nanospheres@polydopamine / octadecyl mercaptan.

[0067] In the lignin nanospheres@polydopamine / octadecyl mercaptan composite microspheres prepared in this example, the lignin nanospheres serve as the core, and their surface is coated with a polydopamine layer. The benzoquinone structure of the polydopamine layer reacts chemically with the thiol groups of octadecyl mercaptan, thereby grafting C onto the surface of the polydopamine layer. 18 H 37 -S- group.

[0068] Example 2 This example provides a method for preparing a superhydrophobic antibacterial and deoxygenating filter membrane, which specifically includes the following steps: Step (1): Accurately weigh 50 mg of lignin nanospheres@polydopamine / octadecyl mercaptan prepared in Example 1, 20 mg of hydroxypropyltrimethylammonium chloride chitosan (HACC), and 100 mg of polyvinylpyrrolidone (PVP), and add them together to 100 mL of a mixed solvent composed of deionized water and anhydrous ethanol in a volume ratio of 1:1 to obtain a mixture. Stir the mixture at 500 rpm for 1 h, and then sonicate it at 400 W for 30 min to obtain a uniform and stable milky white coating solution.

[0069] Step (2): Cut the polyacrylonitrile base film (i.e., PAN base film) into 10 cm × 15 cm size, immerse it in anhydrous ethanol and ultrasonically clean it for 15 min, take it out and rinse it with deionized water, and let it air dry for later use.

[0070] Step (3): Using a laboratory stretcher, the pretreated PAN base film is completely immersed in the coating solution prepared in step (1) and left to stand for 5 min. Then, it is vertically stretched out of the liquid surface at a constant speed of 2 mm / s. Then, it is placed in a 50℃ forced-air drying oven for pre-drying for 30 min, and then transferred to a 100℃ vacuum drying oven for heat treatment for 2 h to allow the coating to fully crosslink and cure, thus obtaining the superhydrophobic antibacterial deoxygenating filter membrane in this example.

[0071] Comparative Example 1 The only difference between the preparation method of the antibacterial film in this example and that in Example 2 is that the microspheres added in this example are lignin nanospheres.

[0072] Comparative Example 2 The only difference between the preparation method of the antibacterial film in this example and that in Example 2 is that lignin nanospheres@polydopamine / octadecyl mercaptan composite microspheres were not added in this example.

[0073] Performance testing The lignin nanospheres@polydopamine / octadecyl mercaptan composite microspheres prepared in Example 1 were tested using XRD (Bruker D8 Advance, Germany). Specifically, the test method involved scanning at a speed of 10° / min within a 2θ range of 10°–80°, and Cu Kα radiation was used to study the crystal structure of the samples. The specific test results are shown below. Figure 1 As shown, the broad diffraction peaks from 10° to 30° originate from amorphous lignin, while the diffraction peak intensities at this position of lignin nanospheres@polydopamine / octadecyl mercaptan composite microspheres are lower. This can be attributed to the reduced diffraction peak intensity caused by the coating of polydopamine and the grafting of octadecyl mercaptan.

[0074] Example 2 (i.e.,) was tested using an accelerated climate testing machine (Xenotest Beta LM Atlas). Figure 2 In Example 2), the films of Comparative Example 1 and Comparative Example 2 were subjected to UV radiation tests. The films were exposed to UV radiation (200-600 nm, 65 W / m). 2 (in) . Specific test results are as follows: Figure 2 As shown. In the initial stage, the film of Comparative Example 2 exhibited high UV transmittance, indicating its poor UV resistance. After 168 h of UV aging, the UV transmittance of the film of Comparative Example 2 decreased significantly, indicating severe yellowing due to UV damage. The UV transmittance curves of the films of Comparative Example 1 and Example 2 showed the least change after the UV aging experiment, which is attributed to the excellent UV resistance of lignin.

[0075] The gloss of Example 2 (i.e., gloss meter WGG60-Y4, purchased from KSJ Optoelectronic Instruments Co., Ltd.) was measured. Figure 3 Example 2), the 60° gloss of the films of Comparative Example 1 and Comparative Example 2 before UV radiation, after 84 hours of UV radiation, and after 168 hours of UV radiation. Specific test results are as follows: Figure 3 As shown. Initially, the gloss values ​​of the films in Example 2 and Comparative Example 1 exceeded those of the film in Comparative Example 2, indicating that the addition of lignin made the film surface smoother, thereby enhancing the surface gloss. The surface gloss of the film in Comparative Example 2 decreased significantly after 84 h and 168 h of UV aging tests, with gloss losses of 48.1% and 63%, respectively. In contrast, the gloss losses of the film in Comparative Example 1 after 84 h and 168 h of UV aging tests were 5.8% and 9.3%, respectively, while the gloss losses of the film in Example 2 after 84 h and 168 h of UV aging tests were only 4.6% and 8.1%, respectively. These results further demonstrate that the addition of lignin can give the film superior UV aging resistance.

[0076] The deoxygenation filter membrane of Example 2 (i.e., 0.5°C) was tested using a contact angle meter (OCA20, Dataphysics, Germany). Figure 4 The water contact angles of the antibacterial membranes in Example 2), Comparative Example 1, and Comparative Example 2 are shown in the following figures. Figure 4 As shown. In Example 2, the deoxygenation filter membrane has a water contact angle of 156.8°, and water droplets roll off its surface rapidly at an angle of less than 10°, exhibiting superhydrophobicity. This superhydrophobic surface physically blocks dissolved oxygen mass transfer, achieving deoxygenation while preventing scale buildup. In contrast, the antibacterial membrane in Comparative Example 1 has a water contact angle of 90.4°, exhibiting weak hydrophobicity, while the antibacterial membrane in Comparative Example 2 has a water contact angle of 68.2°, exhibiting hydrophilicity.

[0077] A membrane deoxygenation performance evaluation device was constructed, consisting of a feed circulation unit, a membrane module, and a vacuum system. For ease of comparison, a control group (i.e., no membrane group) without a deoxygenation filter membrane was set up. The deoxygenation filter membrane from Example 2 (i.e., the membrane-free group) was used instead. Figure 5 In Example 2) and Comparative Examples 1 and 2, the antibacterial membranes were effectively sealed in membrane modules. Saturated demineralized water with an initial dissolved oxygen concentration of 8.5 mg / L was introduced into the feed side, and the permeate side was connected to a vacuum pump to provide oxygen mass transfer driving force. The dissolved oxygen concentration of the effluent was monitored in real time using a dissolved oxygen meter. Specific test results are shown in the figure. Figure 5As shown, the deoxygenation rate was then calculated as: Deoxygenation rate = (Initial dissolved oxygen concentration - Effluent dissolved oxygen concentration) / Initial dissolved oxygen concentration × 100%. After treatment with the deoxygenation filter membrane in Example 2, the effluent dissolved oxygen concentration decreased to 0.5 mg / L, while after treatment with the antibacterial membrane in Comparative Example 1, the effluent dissolved oxygen concentration was 7.6 mg / L, and after treatment with the antibacterial membrane in Comparative Example 2, the effluent dissolved oxygen concentration was 8.2 mg / L. Based on this calculation, the deoxygenation rate of the deoxygenation filter membrane in Example 2 was as high as 94.1%, while the deoxygenation rate of the antibacterial membrane in Comparative Example 1 was only 10.6%, and the deoxygenation rate of the antibacterial membrane in Comparative Example 2 was only 3.5%. This result proves that the superhydrophobic layer constructed in this invention effectively blocks liquid water while removing most of the oxygen.

[0078] According to GB / T 1040.1 The test method described in the 2025 standard "Determination of Tensile Properties of Plastics" is to test the tensile strength and elongation at break of the filter membrane in Example 2. The specific test method is as follows: a 150mm×20mm sample (sampled along the blown film direction) is fixed on an Instron 5565 universal tensile testing machine at room temperature and a tensile test is performed at a tensile rate of 5mm / min. The test results are shown in Table 1.

[0079] Table 1 Mechanical performance test results

[0080] As shown in Table 1, the tensile strength of Example 2 is 25.21 MPa and the elongation at break is 292.32%, which indicates that it has good mechanical properties.

[0081] According to GB / T31402-2023, Escherichia coli and Staphylococcus aureus were used as test species to test the antibacterial rate of the antimicrobial films in Example 2 and Comparative Example 2. The test results are shown in Table 2.

[0082] Table 2 Results of antibacterial rate test

[0083] Table 2 shows that the deoxygenated filtration membrane in Example 2 achieved antibacterial rates of 99.8% and 99.9% against Escherichia coli and Staphylococcus aureus, respectively, after 24 hours. The deoxygenated filtration membrane in Comparative Example 2 achieved antibacterial rates of 95.2% and 95.1% against Escherichia coli and Staphylococcus aureus, respectively, after 24 hours. This further demonstrates that Example 2, by setting a superhydrophobic surface on the PAN base membrane, effectively reduces bacterial adhesion and produces a synergistic antibacterial effect with HACCP.

[0084] In summary, the filter membrane of this invention integrates three major functions: superhydrophobic scale prevention, high-efficiency antibacterial, and physical deoxygenation, and these functions can produce a synergistic effect.

[0085] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A filtration membrane, characterized by: The filter membrane comprises a base film and a hydrophobic coating layer arranged on the base film; the hydrophobic coating layer contains composite microspheres; The composite microspheres comprise lignin nanospheres and a polydopamine layer coated on the surface of the lignin nanospheres; the polydopamine layer is grafted with SR groups on the surface; the sulfur atom in the SR group is chemically bonded to the polydopamine layer; R in the SR group is selected from C 10 ~C 30 alkyl.

2. The filtration membrane according to claim 1, characterized in that: The hydrophobic coating layer further contains a bacteriostatic agent and a binder; preferably, the bacteriostatic agent is selected from at least one of chitosan quaternary ammonium salt and chitosan; preferably, the binder is selected from at least one of polyvinylpyrrolidone, polyacrylamide, sodium carboxymethyl cellulose and guar gum.

3. The filtration membrane according to claim 2, characterized in that: In the hydrophobic coating layer, the mass ratio of the composite microspheres to the bacteriostatic agent is 1: (0.3-0.5) ; And / or, in the hydrophobic coating layer, the mass ratio of the composite microspheres to the binder is 1: (1.5-2.5).

4. The filtration membrane of claim 1, wherein: The base film comprises at least one of polyacrylonitrile base film, polyether sulfone base film and polysulfone base film.

5. The filtration membrane of claim 1, wherein: The composite microspheres are prepared by a preparation method comprising the following steps: Polymerization of a lignin nanosphere dispersion liquid with dopamine hydrochloride to obtain lignin nanospheres coated with a polydopamine layer; Grafting reaction of RSH with the lignin nanospheres coated with a polydopamine layer to obtain the composite microspheres; R in RSH is selected from C 10 ~C 30 alkyl.

6. The filtration membrane according to any one of claims 1 to 5, characterized in that: The filter membrane has at least one of the following characteristics: (a1) The water contact angle of the filter membrane is not less than 150°; (a2) The bacteriostatic rate of the filter membrane is not less than 99%; (a3) The removal rate of dissolved oxygen in water by the filter membrane is not less than 90%.

7. The method of producing a filtration membrane according to any one of claims 1 to 6, characterized by: The filter membrane is prepared by the following steps: Loading the preparation raw material of the hydrophobic coating layer on the surface of the base film, and then heat treating and solidifying to obtain the filter membrane.

8. The method of claim 7, wherein: The temperature during the heat treatment and solidification is 90-110°C; and / or the time for the heat treatment and solidification is 1.5-3h.

9. A water cooling system characterized by: The filter assembly comprises the filter membrane according to any one of claims 1-6.

10. Application of the filter membrane according to any one of claims 1-6 in the field of water treatment.

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