An anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative and its preparation method and application

Abstract

The present invention discloses an anti-biofouling ultrafiltration membrane containing a natural antibacterial material derivative, and its preparation method and application. The preparation method of the anti-biofouling ultrafiltration membrane of the present invention is as follows: (1) synthesizing an antibacterial material capsaicin derivative and transforming the membrane matrix through atom transfer radical polymerization (ATRP); (2) combining the capsaicin derivative with the transformed membrane matrix through an esterification reaction to obtain an antibacterial polymer; (3) subjecting the above polymer to non-solvent induced phase separation (NIPS) to prepare an anti-biofouling ultrafiltration membrane. The process of the present invention is simple, easy to operate, and cost-controlled, and can achieve large-scale industrial production. The anti-biofouling ultrafiltration membrane prepared by the present invention uses a natural antibacterial material derivative. While ensuring safety and friendliness to the environment and humans, it exhibits excellent ability to resist the growth and proliferation of microorganisms on the membrane surface and has good application prospects in water treatment processes.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of environmental functional materials, and in particular to an anti-biological pollution ultrafiltration membrane containing a natural antibacterial material derivative, and a preparation method and application thereof. Background Art

[0002] Drinking water safety is one of the greatest challenges facing humanity today. Membrane technology holds significant advantages in water treatment due to its safety, reliability, cost-effectiveness, and low energy consumption. However, the widespread problem of membrane biofouling has hindered its development. This is because microorganisms in water, particularly bacteria, attach, grow, and multiply on the membrane surface, forming a biofilm. This can lead to a sharp drop in membrane flux, damage the membrane structure, and shorten its service life. Therefore, measures must be taken to address membrane biofouling.

[0003] At present, the biofouling problem existing in the filtration process is generally resisted by modifying the membrane. The hydrophilic modification of the membrane can reduce the attachment of microorganisms, but as time goes on, the generation of biofilm is inevitable. Inorganic nanomaterials (silver, copper, zinc, etc.) are used to be coated on the membrane surface or to be blended with the membrane to obtain anti-biofouling properties. However, the low bonding strength of inorganic nanomaterials and membrane causes elution, which not only sharply reduces the anti-biofouling performance of the membrane, but also causes serious harm to the environment and humans. Introducing positively charged quaternary ammonium salts in the filter membrane has a more significant bactericidal effect, but it has problems such as large toxicity and high price. Introducing photosensitive materials (photodynamic method) or photothermal materials (photothermal method) in the membrane matrix to suppress the growth of microorganisms can not be used in large-scale water treatment processes because the external conditions required are too harsh. Therefore, it is very important to select a safe, efficient and antibacterial material that can be stably combined with the membrane matrix material to construct an anti-biofouling filter membrane. Summary of the Invention

[0004] To address the aforementioned technical issues in the prior art, the present invention aims to provide an anti-biofouling ultrafiltration membrane containing a natural antimicrobial material derivative, as well as its preparation method and application. The functional additive employed in the present method is a natural antimicrobial material—a capsaicin derivative—which covalently bonds to the modified membrane matrix via esterification, resists detachment from the membrane surface over time, and exhibits a long-lasting antimicrobial effect, excellent safety, and amenable to scalable production and application.

[0005] The technical solution employed in the present invention is as follows: First, a derivative of a natural antimicrobial material, a capsaicin derivative, is synthesized using a simple method. Second, tert-butyl methacrylate is grafted onto the membrane matrix P(VDF-CTFE) via atom transfer radical polymerization, which hydrolyzes to produce P(VDF-CTFE)-g-PMAA with carboxyl groups. Next, the capsaicin derivative and P(VDF-CTFE)-g-PMAA undergo an esterification reaction under a DCC / DMAP catalytic system to form an antimicrobial polymer. Finally, a safe and highly effective anti-biofouling ultrafiltration membrane is obtained using nonsolvent-induced phase separation (NIPS).

[0006] The technical solutions adopted in the present invention are as follows:

[0007] A method for preparing an anti-biofouling ultrafiltration membrane containing a natural antibacterial material derivative comprises the following steps:

[0008] 1) Capsaicin derivatives were synthesized using 3,5-dimethylphenol and hydroxymethyl acrylamide as raw materials via Friedel-Crafts alkylation reaction;

[0009] 2) introducing a monomer containing an ester group and grafting it onto the membrane matrix material through atom transfer radical polymerization, and then performing a hydrolysis reaction in an acidic solution to convert the ester group of the monomer on the membrane matrix material into a carboxyl group to obtain a modified membrane matrix;

[0010] 3) dissolving the capsaicin derivative obtained in step 1) and the modified membrane matrix and catalyst obtained in step 2) in a polar solvent, and then subjecting them to an esterification reaction at room temperature to obtain an antibacterial polymer;

[0011] 4) The antimicrobial polymer obtained in step 3) is dissolved in a polar solvent, heated and stirred to form a membrane-forming solution, centrifuged to remove bubbles, and then allowed to stand. The solution is then scraped onto a clean glass plate using a doctor blade to form a liquid film. The film is then placed in deionized water to achieve phase inversion. The water is then changed 1-3 times to remove residual solvent on the membrane surface, thereby obtaining an anti-biofouling ultrafiltration membrane.

[0012] Furthermore, in step 1), 3,5-dimethylphenol and hydroxymethyl acrylamide are used as raw materials, ethanol is used as solvent, and concentrated sulfuric acid is used as a catalyst. The raw materials and the catalyst are added to the solvent to carry out a Friedel-Crafts alkylation reaction. The reaction temperature is 30-40°C and the reaction time is 45-50h. After the reaction is completed, the product is filtered and washed with deionized water several times during the process. It is then recrystallized with ethanol to finally obtain the target product, a capsaicin derivative.

[0013] Furthermore, the molar ratio of the 3,5-dimethylphenol and hydroxymethyl acrylamide is 1:1.5-3, preferably 1:2; the ratio of the volume of the concentrated sulfuric acid to the amount of 3,5-dimethylphenol is 20-40:1, preferably 30-35:1, the unit of volume is ml, and the unit of amount of substance is mol; the mass concentration of the concentrated sulfuric acid is 95-98%.

[0014] Furthermore, in step 2), the specific process of introducing the ester-containing monomer into the membrane matrix material through atom transfer radical polymerization is as follows: the membrane matrix material, catalyst, ligand and ester-containing monomer are added to a polar solvent, reacted at 70-90°C for 20-30h under a nitrogen atmosphere, cooled to room temperature after the reaction, and diluted with acetone. The diluted product is dropped into a mixed solution of water and methanol (volume ratio of 1:2), and then filtered to remove impurities such as solvent and catalyst. In this process, the filtrate is washed with deionized water several times until the filtrate has no color, and the product is collected and freeze-dried to obtain P(VDF-CTFE)-g-PtBMA;

[0015] The membrane matrix material is P(VDF-CTFE), the ester-containing monomer is tert-butyl methacrylate, the catalyst is CuCl, the ligand is N,N,N',N,'N"-pentamethyldiethylenetriamine PMDETA, and the polar solvent is N-methylpyrrolidone NMP.

[0016] Furthermore, the molar ratio of the chlorine content of the P(VDF-CTFE), CuCl, PMDETA and tert-butyl methacrylate is 1:0.5-2:0.5-2:10-30, preferably 1:1:1:20.

[0017] Furthermore, the process of the hydrolysis reaction in step 2) is: placing the membrane matrix material grafted with a monomer containing an ester group in an acidic solution and reacting at 80-90°C for 5-20 hours; wherein the acid of the acidic solution is p-toluenesulfonic acid monohydrate, the solvent is toluene, and the mass ratio of p-toluenesulfonic acid monohydrate to the membrane matrix material grafted with a monomer containing an ester group is 1 to 2:1, preferably 1.5 to 1.7:1.

[0018] Furthermore, in step 3), the catalyst is N,N-dicyclohexyl carbonate diimide DCC / 4-dimethylaminopyridine DMAP, and the molar ratio of DCC to DMAP is 1.5 to 3:1, preferably 2:1;

[0019] The polar solvent is N,N-dimethylformamide DMF;

[0020] The molar ratio of the carboxyl content of the modified membrane matrix, the hydroxyl content of the capsaicin derivative and DMAP is 1:0.5-2:0.5-2:0.5-2, preferably 1:1:1:1.

[0021] Furthermore, the esterification reaction time in step 3) is 40-60 hours, preferably 45-50 hours.

[0022] Furthermore, the polar solvent in step 4) is N,N-dimethylformamide (DMF), and the thickness of the liquid film is 200-400 μm.

[0023] The present invention also provides an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative, and an application of an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative in the field of water treatment. The application scenario is preferably to filter water bodies containing microorganisms such as Escherichia coli.

[0024] As described above, the method for preparing an anti-biofouling ultrafiltration membrane containing a natural antibacterial material derivative of the present invention has the following advantages over the prior art:

[0025] (1) The anti-biological contamination ultrafiltration membrane containing natural antibacterial material derivatives prepared by the present invention adopts the method of covalently bonding the antibacterial material with the modified membrane matrix, which does not have the risk of material leakage and has a long action time.

[0026] (2) The antibacterial material used in the anti-biological contamination ultrafiltration membrane containing natural antibacterial material derivatives prepared by the present invention is non-toxic and harmless, and will not bring potential harm to the environment and human health.

[0027] (3) The anti-biofouling ultrafiltration membrane containing natural antibacterial material derivatives prepared by the present invention exhibits excellent resistance to microbial growth and proliferation when filtering water containing microorganisms such as Escherichia coli.

[0028] (4) The anti-biological contamination ultrafiltration membrane containing natural antibacterial material derivatives prepared by the present invention adopts a simple process, has controllable cost, has low requirements for conditions during use, and is suitable for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a complete flow chart for the synthesis of antibacterial polymers in Example 1 of the present invention.

[0030] Figure 2 The nuclear magnetic resonance hydrogen spectra of P(VDF-CTFE), P(VDF-CTFE)-g-PtBMA, P(VDF-CTFE)-g-PMAA and the antibacterial polymer in Example 1 are ( 1 HNMR);

[0031] Figure 3 FT-IR spectra of P(VDF-CTFE), P(VDF-CTFE)-g-PtBMA, P(VDF-CTFE)-g-PMAA and the antibacterial polymer in Example 1;

[0032] Figure 4 Scanning electron microscopy (SEM) images of the surface (a) and cross-section (b) of the control membrane (M1) and the surface (c) and cross-section (d) of the anti-biofouling ultrafiltration membrane (MA) in Example 1;

[0033] Figure 5 The changes in cell activity after adding capsaicin derivatives and their polymers (PA) in Example 2;

[0034] Figure 6 The colony growth of M0 (a), M1 (b), and MA (c) after oscillation and coating with LB medium in Example 2, and the colony distribution of M0 (d), M1 (e), and MA (f) after oscillation under a scanning electron microscope;

[0035] Figure 7 The flux decrease rate when M1 and MA filtered water containing E. coli in Example 2 and the degree of flux recovery after simple flushing. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0037] Example 1

[0038] In this embodiment, the overall synthetic route is as follows Figure 1 As shown. First, a capsaicin derivative is obtained by Friedel-Crafts alkylation reaction. Then, the membrane matrix is ​​modified by atom transfer radical polymerization (ATRP) and hydrolysis reaction. Then, the capsaicin derivative and the modified membrane matrix are combined by esterification reaction to obtain an antimicrobial polymer (PA). Finally, an anti-biofouling ultrafiltration membrane is obtained by non-solvent-induced phase separation. The specific steps are as follows:

[0039] (1) Synthesis of antibacterial capsaicin derivatives: First, 18.3 g (0.15 mol) of 3,5-dimethylphenol and 30.3 g (0.30 mol) of hydroxymethyl acrylamide were placed in a 250 ml round-bottom flask containing 100 ml of ethanol and completely dissolved by magnetic stirring. After slowly adding 5 ml of concentrated sulfuric acid, the temperature was raised to 35 ° C and the reaction was continued for 48 hours. After the reaction was completed, the product was vacuum filtered and washed with deionized water and ethanol several times during the process. Finally, the target product, capsaicin derivative, was obtained by recrystallization from ethanol.

[0040] (2) Modification of the membrane matrix material P(VDF-CTFE): First, 1.5 g of P(VDF-CTFE) (chlorine content of 2.4 mmol) and 238 mg of CuCl (2.4 mmol) were placed in a 100 ml Schlenk flask, and vacuum nitrogen was circulated three times to maintain a nitrogen environment to prevent the catalyst from being oxidized. Then, 25 ml of NMP, which had been bubbling nitrogen for 30 minutes, was transferred to the Schlenk flask, and the membrane matrix material and catalyst were completely dissolved by magnetic stirring. After that, 7.64 ml of tBMA (48 mmol) and 0.5 ml of PMDETA (2.4 mmol) were transferred to the container respectively after bubbling nitrogen for 30 minutes. The system temperature was then raised to 80 °C by oil bath heating, and the nitrogen environment was maintained throughout the reaction process. After 24 h, the reaction was terminated by exposing the system to air to reach room temperature, and then 5 ml of acetone was added for dilution. The diluted product was dropped into a mixed solution of water and methanol (volume ratio of 1:2), and then filtered to remove impurities such as solvent and catalyst. During this process, the product was washed with deionized water several times until the filtrate was colorless, and the product P(VDF-CTFE)-g-PtBMA was collected and freeze-dried, and finally weighed for later use.

[0041] H NMR spectra of membrane matrix material P(VDF-CTFE) and product P(VDF-CTFE)-g-PtBMA ( 1 HNMR) respectively as Figure 2 (a) with Figure 2 As shown in (b), compared with Figure 2 (a) P(VDF-CTFE), such as Figure 2 The H NMR spectrum shown in (b) shows new peaks at 1.44 ppm and 1.83 ppm, indicating that the ATRP reaction has successfully occurred.

[0042] (3) Hydrolysis reaction of membrane matrix material: 2.5g of P(VDF-CTFE)-g-PtBMA was placed in a 250ml round-bottom flask containing 50ml of toluene, and after dissolving it by magnetic stirring, 4.0g of p-toluenesulfonic acid monohydrate (TSA) was added, and the oil bath temperature was raised to 85℃ for 10h. The product was then dropped into a mixed solution of water and ethanol (volume ratio of 1:2) to finally obtain the product P(VDF-CTFE)-g-PMAA. The H NMR spectrum of the product P(VDF-CTFE)-g-PMAA ( 1 HNMR) Figure 2 As shown in (c), along with the disappearance of the tert-butyl peak at 1.44 ppm, a new peak belonging to the carboxyl group appeared at 12.36 ppm, indicating that the hydrolysis reaction was successful.

[0043] (4) Synthesis of antibacterial polymer (PA): 1.10 g P(VDF-CTFE)-g-PMAA (carboxyl content 12 mmol) and 3.43 g capsaicin derivative (hydroxyl content 12 mmol) were dissolved in a 100 ml round-bottom flask containing 15 ml DMF at 0°C. After adding 4.94 g DCC (24 mmol) and 1.46 g DMAP (12 mmol), the mixture was reacted at room temperature for 48 h. After the reaction was completed, the mixture was filtered, freeze-dried, and weighed to obtain the antibacterial polymer (PA). H NMR spectrum of the antibacterial polymer (PA) ( 1 H NMR) Figure 2 As shown in (d), the carboxyl peak at 12.36 ppm and the hydroxyl peak at 9.64 ppm completely disappeared, while the other characteristic peaks of the two reactants were retained.

[0044] The infrared spectra (FT-IR) of P(VDF-CTFE) (P1), P(VDF-CTFE)-g-PtBMA (T1), P(VDF-CTFE)-g-PMAA (A1) and antibacterial polymer (PA) in Example 1 are summarized in Figure 3 In. Figure 3 As shown, compared with P(VDF-CTFE) (P1), P(VDF-CTFE)-g-PtBMA (T1) has a peak at 1728 cm -1 A new peak of carbon-oxygen double bond belonging to ester group appeared at 1714cm -1 A new peak belonging to the carbon-oxygen double bond in the carboxyl group appeared at the above. The above verified the successful occurrence of ATRP reaction and hydrolysis, which also means the successful transformation of the membrane matrix material. In addition, Figure 3 The infrared spectrum of antibacterial polymer (PA) is shown in Figure 1. -1 A new peak of carbon-oxygen double bond belonging to ester group appeared at . Here, antibacterial material was successfully reacted with modified membrane matrix to synthesize antibacterial polymer (PA).

[0045] (5) Construction of anti-biofouling ultrafiltration membrane: Three membranes were prepared by non-solvent-induced phase separation, namely, membrane M0 containing only membrane matrix P (VDF-CTFE), membrane M1 with pore-forming material polyethylene glycol (PEG) added to M0, and anti-biofouling ultrafiltration membrane MA. The preparation methods of the three membranes all include the following steps: First, using DMF as a solvent, the three membrane materials for preparing ultrafiltration membranes are dispersed in the solvent respectively, and magnetically stirred at 300 rpm / min at 60°C for 24 hours to obtain a membrane-forming solution. Then, the membrane-forming solution is placed in a centrifuge and centrifuged at a low speed of 3000 rpm / min for 20 minutes to remove bubbles. After standing for a period of time, the membrane-forming solution is poured onto a clean glass plate of a scraping machine and converted into a liquid film with a thickness of 300 μm using a scraping knife at a speed of 30 cm / min. After scraping, it is allowed to stand for 60 seconds and then placed in deionized water for 24 hours to achieve the purpose of phase inversion. After that, the water was changed every 24 hours for a total of three times to remove the residual solvent on the membrane surface, and the obtained membrane was stored in deionized water for further use. According to this method, membranes M0, M1 and MA can be obtained.

[0046] The membrane material for preparing membrane M0 is the membrane matrix P (VDF-CTFE) of Example 1. When the membrane matrix P (VDF-CTFE) is dispersed in DMF solvent, the mass fraction of the membrane matrix P (VDF-CTFE) is 15% and the mass fraction of the DMF solvent is 85%.

[0047] The membrane material for preparing membrane MA is the antibacterial polymer (PA) in Example 1. When the antibacterial polymer (PA) is dispersed in DMF solvent, the mass fraction of the antibacterial polymer (PA) is 15% and the mass fraction of the DMF solvent is 85%.

[0048] The membrane materials for preparing membrane M1 are membrane matrix P (VDF-CTFE) and pore-forming material polyethylene glycol PEG (molecular weight 2000). The process of preparing the membrane-building solution is: 15% by mass of P (VDF-CTFE) and 3% by mass of PEG are mixed together, 82% by mass of DMF is added, and magnetic stirring is carried out at 60°C and 300 rpm / min for 24 hours to obtain the membrane-building solution.

[0049] Scanning electron microscopy (SEM) images of the surface and cross section of membrane M1 are shown in Figure 2. Figure 4 In (a) and (b), scanning electron microscopy (SEM) images of the surface and cross section of the anti-biofouling ultrafiltration membrane MA are shown in Figure 2. Figure 4 Compared with M1, the pore size and arrangement of MA surface are more uniform, and the cross section has finger-like through-holes, which are beneficial for the precise screening of pollutants and the increase of flux.

[0050] Example 2

[0051] In this example, the biosafety of the antibacterial material and its polymer (PA) and the anti-biofouling properties of the membrane MA were characterized.

[0052] Biosafety analysis of the capsaicin derivative and its polymer PA of Example 1: First, human liver cancer cells were subcultured and used for safety testing at the third generation. Then, 200 μl of cells were seeded into 96-well plates and incubated for 24 hours. A blank control without any material was used, and the cells were exposed to different concentrations of the capsaicin derivative and its polymer PA. After 24 hours, the absorbance of the cells at 450 nm at different sample concentrations was observed using a microplate reader to determine cell viability. Figure 5 As shown, compared with the blank control without adding any materials, the increase in the concentration of capsaicin derivatives and their polymers (PA) did not significantly affect the cell activity, and the absorbance at a wavelength of 450 nm was stable at around 3.45. Figure 5 The middle Cap corresponds to the detection result of capsaicin derivatives. This shows that capsaicin derivatives and their polymers have good biosafety, so there is no need to worry about the harm of this anti-biofouling ultrafiltration membrane to the environment and humans during and after use.

[0053] Static antibacterial experiment was used to test the anti-biofouling performance of the membrane: the membrane sample was washed with PBS after being immersed in E. coli solution for 24 hours, and the solution obtained after shaking was coated on solid LB medium, and the growth of E. coli was observed overnight. Figure 6 As shown in (a), the density of E. coli in the LB culture medium of M0 is very high, indicating that there are a large number of E. coli adsorbed, grown and reproduced on the surface of M0. This is probably because the pore-free M0 provides more adsorption sites. Figure 6 As shown in (b), the density of E. coli in the LB medium of M1 is slightly lower, indicating that after adding the pore-forming agent PEG, a considerable amount of E. coli still grows and reproduces on the surface of M1. Figure 6 As shown in (c), the density of E. coli in the LB medium of MA is extremely low, which indicates that MA has a good anti-biofouling effect. On the other hand, in order to obtain a more intuitive phenomenon, the membrane samples fixed with glutaraldehyde after being removed from the E. coli solution were observed by scanning electron microscopy. The scanning electron microscopy observation results of the membrane samples M0, M1 and MA fixed with glutaraldehyde after being removed from the E. coli solution are shown as follows: Figure 6 As shown in Figures 6(d), 6(e), and 6(f), consistent with the results of the LB medium coating experiment, M0 was densely covered with E. coli, M1 was slightly covered with E. coli, and MA was almost completely covered with E. coli. This indicates that compared with untreated M0 and M1 with polyethylene glycol added, the modified MA has a better anti-biofouling effect.

[0054] Similarly, the anti-biofouling properties of the membrane were investigated using a dynamic antibacterial experiment: First, E. coli was washed and diluted to 500 mL using 0.9 wt% NaCl (the concentration of E. coli was the OD value measured using a UV spectrophotometer). 600 =0.1). Using a dead-end filtration device, dead-end filtration was performed at room temperature and 1.5 psi. The membrane's pure water flux was first tested for 30 minutes, then the flux change over 120 minutes while filtering a bacterial solution. After a simple rinse, the membrane's pure water flux was measured again for 30 minutes. The flux change trend and the degree of flux recovery after rinsing were observed, thereby evaluating the membrane's anti-biofouling effect. The results are shown in Figure 1. Figure 7 As shown, Figure 7 The first 30 minutes are the test results of filtered pure water, the middle 120 minutes are the test results of filtered bacterial solution, and the last 30 minutes are the test results of filtered pure water. Figure 7 In the process of filtering the bacterial solution, the flux of M1 dropped to 74% and 45% in the first ten minutes and the first twenty minutes, respectively, while the flux of MA dropped to 85% and 66% under the same circumstances. After two hours of filtering the E. coli solution, the flux of M1 dropped to 23%, while the flux of MA only dropped to 50%. After a simple flushing of the membrane, the pure water flux of M1 recovered to 53%, while the pure water flux of MA recovered to 72%. The dynamic antibacterial experiment shows that compared with M1 with the addition of the pore-forming agent PEG, MA can effectively kill microorganisms attached to the surface and prevent their proliferation. Therefore, it is superior in both resisting flux reduction and flux recovery.

[0055] The anti-biofouling ultrafiltration membrane containing a natural antimicrobial material derivative prepared by this invention overcomes the problems of other membranes, such as the short anti-fouling duration, the environmental impact of material shedding, and the harsh operating conditions that preclude large-scale production and application. By simply synthesizing a natural antimicrobial material derivative, modifying the membrane matrix material, and covalently bonding the two through esterification to form an antimicrobial polymer, and then using non-solvent-induced phase separation, a safe and highly effective anti-biofouling ultrafiltration membrane is achieved.

[0056] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative, characterized in that The following steps are involved: 1) Capsaicin derivatives were synthesized using 3,5-dimethylphenol and hydroxymethyl acrylamide as raw materials via Friedel-Crafts alkylation reaction; 2) Through atom transfer radical polymerization, a monomer containing an ester group is introduced and grafted onto the membrane matrix material, and then a hydrolysis reaction is carried out in an acidic solution to convert the ester group of the monomer on the membrane matrix material into a carboxyl group to obtain a modified membrane matrix; 3) dissolving the capsaicin derivative obtained in step 1), the modified membrane matrix obtained in step 2), and the catalyst in a polar solvent, and then subjecting the mixture to an esterification reaction at room temperature to obtain an antibacterial polymer; 4) The antimicrobial polymer obtained in step 3) is dissolved in a polar solvent, heated and stirred to form a membrane-forming solution, centrifuged to remove bubbles, and then allowed to stand. The solution is then scraped onto a clean glass plate using a doctor blade to form a liquid membrane. The membrane is then placed in deionized water to achieve phase inversion. The water is then changed 1-3 times to remove residual solvent from the membrane surface, thereby obtaining an anti-biofouling ultrafiltration membrane.

2. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 1, characterized in that In step 1), 3,5-dimethylphenol and hydroxymethyl acrylamide are used as raw materials, ethanol is used as solvent, and concentrated sulfuric acid is used as a catalyst. The raw materials and catalyst are added to the solvent to carry out a Friedel-Crafts alkylation reaction. The reaction temperature is 30-40°C and the reaction time is 45-50 hours. After the reaction is completed, the product is filtered and washed with deionized water several times during the process. It is then recrystallized with ethanol to finally obtain the target product, a capsaicin derivative.

3. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 2, characterized in that The molar ratio of 3,5-dimethylphenol to hydroxymethyl acrylamide is 1:1.5-3; the ratio of the volume of the concentrated sulfuric acid to the amount of substance of 3,5-dimethylphenol is 20-40:1, the unit of volume is ml, and the unit of amount of substance is mol; the mass concentration of the concentrated sulfuric acid is 95-98%.

4. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 3, characterized in that The molar ratio of the 3,5-dimethylphenol and hydroxymethyl acrylamide is 1:2; the ratio of the volume of the concentrated sulfuric acid to the amount of substance of 3,5-dimethylphenol is 30-35:1, the unit of volume is ml, and the unit of amount of substance is mol.

5. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 1, characterized in that In step 2), the ester-containing monomer is introduced and grafted onto the membrane matrix material through an atom transfer radical polymerization reaction. The specific process is as follows: the membrane matrix material, catalyst, ligand, and ester-containing monomer are added to a polar solvent, reacted at 70-90° C. for 20-30 hours under a nitrogen atmosphere, washed to remove impurities after the reaction, and freeze-dried to obtain P(VDF-CTFE)-g-PtBMA; The membrane matrix material is P(VDF-CTFE), the ester-containing monomer is tert-butyl methacrylate, the catalyst is CuCl, the ligand is N,N,N',N,'N''-pentamethyldiethylenetriamine PMDETA, and the polar solvent is N-methylpyrrolidone NMP; The molar ratio of the chlorine content of the P(VDF-CTFE), CuCl, PMDETA and tert-butyl methacrylate is 1:0.5-2:0.5-2:10-30.

6. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 5, characterized in that The molar ratio of the chlorine content of the P(VDF-CTFE), CuCl, PMDETA and tert-butyl methacrylate is 1:1:1:

20.

7. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 1, characterized in that The hydrolysis reaction process in step 2) is as follows: placing the membrane matrix material grafted with the monomer containing an ester group in an acidic solution and reacting at 80-90° C. for 5-20 hours; wherein the acid in the acidic solution is p-toluenesulfonic acid monohydrate, the solvent is toluene, and the mass ratio of p-toluenesulfonic acid monohydrate to the membrane matrix material grafted with the monomer containing an ester group is 1-2:

1.

8. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 7, characterized in that The mass ratio of p-toluenesulfonic acid monohydrate to the membrane matrix material grafted with the ester group-containing monomer is 1.5-1.7:

1.

9. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 1, characterized in that In step 3), the catalyst is N,N-dicyclohexyl carbonate diimide DCC / 4-dimethylaminopyridine DMAP, and the molar ratio of DCC to DMAP is 1.5-3:1; The polar solvent is N,N-dimethylformamide DMF; The molar ratio of the carboxyl content of the modified membrane matrix, the hydroxyl content of the capsaicin derivative, and DMAP is 1:0.5-2:0.5-2:0.5-2.

10. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 9, characterized in that In step 3), the molar ratio of DCC to DMAP is 2:1; The molar ratio of the carboxyl content of the modified membrane matrix, the hydroxyl content of the capsaicin derivative, and DMAP is 1:1:1:

1.

11. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 1, characterized in that The esterification reaction time in step 3) is 40-60 hours.

12. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 11, characterized in that The esterification reaction time in step 3) is 45-50 hours.

13. The method for preparing an anti-biological contamination ultrafiltration membrane containing a natural antibacterial material derivative according to claim 1, characterized in that The polar solvent in step 4) is N,N-dimethylformamide (DMF), and the thickness of the liquid film is 200-400 μm.

14. An anti-biofouling ultrafiltration membrane containing a natural antibacterial material derivative prepared by the method according to any one of claims 1 to 13.

15. Use of the anti-biofouling ultrafiltration membrane containing the natural antibacterial material derivative according to claim 14 in the field of water treatment.

16. The use according to claim 15, characterized in that The application scenario is to filter water bodies containing Escherichia coli microorganisms.

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