Preparation method of an antibacterial filter membrane

Abstract

The present application relates to the field of filter membranes, and specifically discloses a preparation method of an antibacterial filter membrane, which comprises the following steps: S1. Stir and mix cyclodextrin and verbena extract, filter, let the filtrate stand, crystallize, perform suction filtration, dry the crystals, and then add tetrapod-like zinc oxide whiskers, polyamide, pore-forming additives and a solvent and stir and mix to obtain a casting solution; S2. Uniformly scrape and coat the casting solution on the surface of a macroporous organic membrane to form a coating, let it stand at room temperature, and then immerse it in deionized water to obtain a filter membrane. After the cyclodextrin and the verbena extract are mixed, anthraquinone and flavonoid compounds in the verbena extract can be selectively extracted to form inclusion compounds, and the above compounds are slowly released, which can improve the antibacterial effect of the filter membrane for a long time. The tetrapod-like zinc oxide whiskers overlap with each other to form a three-dimensional network framework, thereby locking the cyclodextrin inclusion compound in the framework structure, reducing the loss of the cyclodextrin inclusion compound, and further improving the persistence of the antibacterial effect of the filter membrane.

Description

Technical Field

[0001] The present invention relates to the field of filter membranes, and more particularly, to a method for preparing an antibacterial filter membrane. Background Art

[0002] In recent years, membrane separation technology has been highly valued by many countries in the world and has been widely used in food, medicine, biology, water treatment, chemical industry, petroleum and other fields, generating huge economic and social benefits.

[0003] Filter membranes are usually made into filter elements for use in actual work scenarios. After repeated use, the filter membranes are easily adhered by microorganisms in the water, and then colonize, multiply, form colonies and then develop into microbial membranes, thereby clogging the membrane pores, affecting the separation performance of the filter membrane, causing secondary contamination of the object reagent to be separated next time, and even shortening the service life of the filter membrane. Therefore, how to improve the antibacterial properties of filter membranes has become a hot research topic in this field. Summary of the Invention

[0004] In order to improve the antibacterial effect of the filter membrane, the present application provides a method for preparing an antibacterial filter membrane.

[0005] The present application provides a method for preparing an antibacterial filter membrane using the following technical solution:

[0006] A method for preparing an antibacterial filter membrane comprises the following steps:

[0007] S1. 3-5 parts of cyclodextrin and 15-20 parts of verbena extract in parts by weight are stirred at 40-50 ° C for 10-12h, filtered, and the filtrate is allowed to stand at 4-8 ° C, crystallized, filtered, and the crystals are dried at 40-50 ° C, and then 5-8 parts of tetrapod-shaped zinc oxide whiskers, 15-25 parts of polyamide, 4-6 parts of pore-forming additives and 65-75 parts of solvent are added and stirred to obtain a casting solution;

[0008] S2. The casting solution is evenly scraped onto the surface of the macroporous organic membrane to form a coating, which is allowed to stand at room temperature for 1-2 minutes. The membrane is then immersed in deionized water at 25-35°C for 20-30 minutes to obtain a filter membrane.

[0009] By adopting the above technical solution, the verbena extract is rich in anthraquinones and flavonoids, which have good antibacterial effects. After mixing cyclodextrin and the verbena extract, the above compounds can be selectively extracted to form an inclusion complex. On the one hand, the introduction of impurities is reduced, thereby reducing the impact on the separation effect of the filter membrane. On the other hand, the above compounds are slowly released, which can improve the antibacterial effect of the filter membrane in a long-lasting manner.

[0010] The tetrapod-like zinc oxide whiskers have a three-dimensional tetrapod-like structure. After being mixed with other components of the filter membrane, the tetrapod-like zinc oxide whiskers overlap with each other to form a three-dimensional network framework, thereby locking the cyclodextrin inclusion compound within the framework structure. When using the filter membrane for separation, the loss of the cyclodextrin inclusion compound can be reduced, and the persistence of the antibacterial effect of the filter membrane can be improved.

[0011] Preferably, in the step S1, before stirring the cyclodextrin and the verbena extract, the cyclodextrin is pretreated. The cyclodextrin pretreatment steps are as follows: Mix cyclodextrin, diethanolamine, and tetrahydrofuran with a mass ratio of 1:(90 - 100):(200 - 250), stir and react at 50 - 60 °C for 5 - 6 h, carry out condensation reflux, after 5 h, precipitate the product in an acetone solution, separate, and dry.

[0012] By adopting the above technical solution, hydroxyl groups are introduced onto the cyclodextrin, increasing the polarity of the cyclodextrin surface. After mixing, the surface free energy of the filter membrane can be increased, reducing the adhesion force between the filter membrane surface and bacteria and increasing the adhesion free energy, thereby improving the anti-bacterial adhesion performance of the filter membrane, making it difficult for bacteria to colonize on the filter membrane surface and inhibiting the growth of bacteria on the filter membrane, and further improving the antibacterial performance of the filter membrane.

[0013] Preferably, in the step S1, before adding the tetrapod-like zinc oxide whiskers, the tetrapod-like zinc oxide whiskers are pretreated. The tetrapod-like zinc oxide whisker pretreatment steps are as follows: Add the tetrapod-like zinc oxide whiskers to an aqueous solution of potassium sodium tartrate and stir for 10 - 30 min. The molar ratio of potassium sodium tartrate to the tetrapod-like zinc oxide whiskers is (0.1 - 1):100. Then, while stirring, add an aqueous solution of copper chloride with an equimolar amount to potassium sodium tartrate; then continue to stir for 30 - 60 min, then filter, wash, and dry, and then heat to 270 - 300 °C in a hydrogen atmosphere and hold for 40 - 60 min, and cool to room temperature.

[0014] By adopting the above technical solution, nano-copper particles are uniformly deposited on the surface of the tetrapod-like zinc oxide whiskers, further improving the antibacterial effect of the filter membrane. Moreover, the nano-copper particles can be evenly dispersed in the filter membrane with the help of the tetrapod-like zinc oxide whiskers. Compared with adding nano-copper particles alone, the problems caused by the agglomeration of nano-copper particles can be reduced. On the other hand, the nano-copper particles and the tetrapod-like zinc oxide whiskers are firmly combined. When using the filter membrane for separation, the loss of nano-copper particles can be reduced, which is beneficial to improving the persistence of the antibacterial performance of the filter membrane.

[0015] Preferably, in the step S1, the crystals are dried at 40 - 50 °C, and then 5 - 8 parts by weight of pretreated tetrapod-like zinc oxide whiskers, 3 - 5 parts of dodecylguanidine monohydrochloride, 15 - 25 parts of polyamide, 4 - 6 parts of pore-forming additives, and 65 - 75 parts of solvent are added and stirred and mixed to obtain a casting solution.

[0016] By adopting the above technical solution, dodecylguanidine monohydrochloride is a high molecular polymer. When bacteria adhere to the filter membrane, it can block the respiratory channels of bacteria, causing the bacteria to suffocate and die, thereby improving the antibacterial performance of the filter membrane.

[0017] Preferably, in the step S1, the crystals are dried at 40 - 50 °C, and then a mixture obtained by adding 3 - 4 parts by weight of polyhexamethylene guanidine propionate and 5 - 8 parts of pretreated tetrapod zinc oxide whiskers, 3 - 5 parts of dodecylguanidine monohydrochloride, 15 - 25 parts of polyamide, 4 - 6 parts of pore-forming additive, and 65 - 75 parts of solvent are stirred and mixed to obtain a casting solution.

[0018] By adopting the above technical solution, polyhexamethylene guanidine propionate has chelating properties for metal nanoparticles. It can form positive charges on the surface of the nano copper particles attached to the tetrapod zinc oxide whiskers. Through electrostatic interaction, it can inhibit the aggregation between nano copper particles and promote the uniform dispersion of the tetrapod zinc oxide whiskers, thereby promoting the construction of a three-dimensional framework. On the other hand, polyhexamethylene guanidine propionate and dodecylguanidine monohydrochloride are used in combination. The guanidine group has high activity. Since it is positively charged in an aqueous solution, it can adsorb negatively charged bacteria, thereby inhibiting the division function of bacteria and causing the bacteria to lose their reproductive ability, further improving the antibacterial effect of the filter membrane.

[0019] Preferably, in the step S1, 3 - 5 parts by weight of cyclodextrin and 15 - 20 parts of verbena extract are stirred at 40 - 50 °C under ultrasonic conditions for 10 - 12 h.

[0020] By adopting the above technical solution, ultrasonic treatment can improve the yield and encapsulation rate of the cyclodextrin inclusion complex.

[0021] Preferably, the frequency of the ultrasonic wave is 40 - 50 KHZ.

[0022] By adopting the above technical solution, using the above ultrasonic frequency can improve the yield and encapsulation rate of the cyclodextrin inclusion complex.

[0023] Preferably, the preparation method of the verbena extract is as follows: Verbena is crushed, and then eight times the weight of 80 (v / v)% ethanol solution is added, heated to boiling, and refluxed for 3 h. After filtration, the filter residue is continued to be added with eight times the weight of 80 (v / v)% ethanol solution, heated to boiling, and refluxed for 3 h, and then the verbena extract is obtained by filtration.

[0024] In summary, the present application has the following beneficial effects:

[0025] 1. Since this application uses verbena extract, cyclodextrin, and tetrapod zinc oxide whiskers, after mixing cyclodextrin and verbena extract, anthraquinone and flavonoid compounds in the verbena extract can be selectively extracted to form inclusion compounds, which can slow-release the above compounds and can continuously and lastingly improve the antibacterial effect of the filter membrane. The tetrapod zinc oxide whiskers overlap with each other to form a three-dimensional network framework, thereby locking the cyclodextrin inclusion compound within the framework structure, reducing the loss of the cyclodextrin inclusion compound, and further improving the durability of the antibacterial effect of the filter membrane.

[0026] 2. In this application, it is preferably to uniformly deposit nano copper particles on the surface of the tetrapod zinc oxide whiskers. While further improving the antibacterial effect of the filter membrane, it reduces the problems caused by the agglomeration of nano copper particles. On the other hand, it can reduce the loss of nano copper particles, which is beneficial to improving the durability of the antibacterial performance of the filter membrane.

[0027] 3. In this application, it is preferably to use a compound of polyhexamethylene guanidine propionate and dodecyl guanidine monohydrochloride. On the one hand, it promotes the dispersion of the tetrapod zinc oxide whiskers, thereby promoting the construction of the three-dimensional framework. On the other hand, it inhibits the splitting function of bacteria and viruses, making bacteria and viruses lose their reproductive ability, and further improving the antibacterial effect of the filter membrane. Specific Embodiments

[0028] The following further elaborates on this application with reference to the examples.

[0029] Information source Cyclodextrin β-Cyclodextrin Polyamide Relative molecular mass: 200,000 - 300,000 Dodecylguanidine monohydrochloride Content: 70%

[0030] It should be noted that (v / v)% refers to volume percentage.

[0031] Unless otherwise specified, the raw materials used in the following embodiments can be obtained from ordinary commercial sources.

[0032] Preparation Example of Verbena Extract

[0033] Preparation of verbena extract: Crush verbena, pass through a 10-mesh sieve, then add eight times the weight of 80 (v / v)% ethanol solution, heat to boiling, reflux for 3 h, filter, and continue to add eight times the weight of 80 (v / v)% ethanol solution to the filter residue, heat to boiling, reflux for 3 h, and filter to obtain verbena extract.

[0034] Examples

[0035] Example 1

[0036] This application discloses a preparation method of an antibacterial filter membrane, including the following steps:

[0037] S1. Stir 3 parts of cyclodextrin and 15 parts of verbena extract by weight for 12 h at 40 °C under ultrasonic conditions. The ultrasonic frequency is 40 KHZ. Filter, let the filtrate stand at 4 °C, crystallize, filter by suction, dry the crystals at 40 °C, and then add 5 parts of tetrapod zinc oxide whiskers, 15 parts of polyamide, 4 parts of pore-forming additive and 65 parts of solvent and stir to mix to obtain a casting solution. The pore-forming additive is polyethylene glycol and the solvent is dimethyl sulfoxide;

[0038] S2. Uniformly scrape the casting solution on the surface of a macroporous organic membrane to form a 20-μm-thick coating. Let it stand at room temperature for 1 min, and then immerse it in deionized water at 25 °C for 20 min to obtain a filter membrane.

[0039] Example 2

[0040] S1. Stir 5 parts of cyclodextrin and 20 parts of verbena extract by weight for 10 h at 50 °C under ultrasonic conditions. The ultrasonic frequency is 50 KHZ. Filter, let the filtrate stand at 8 °C, crystallize, filter by suction, dry the crystals at 50 °C, and then add 8 parts of tetrapod zinc oxide whiskers, 25 parts of polyamide, 6 parts of pore-forming additive and 75 parts of solvent and stir to mix to obtain a casting solution. The pore-forming additive is polyethylene glycol and the solvent is dimethyl sulfoxide;

[0041] S2. Uniformly scrape the casting solution on the surface of a macroporous organic membrane to form a 20-μm-thick coating. Let it stand at room temperature for 2 min, and then immerse it in deionized water at 35 °C for 30 min to obtain a filter membrane.

[0042] Example 3

[0043] S1. Stir 4 parts of cyclodextrin and 17 parts of verbena extract by weight for 11 h at 45 °C under ultrasonic conditions. The ultrasonic frequency is 45 KHZ. Filter, let the filtrate stand at 6 °C, crystallize, filter by suction, dry the crystals at 45 °C, and then add 7 parts of tetrapod zinc oxide whiskers, 20 parts of polyamide, 5 parts of pore-forming additive and 70 parts of solvent and stir to mix to obtain a casting solution. The pore-forming additive is polyethylene glycol and the solvent is dimethyl sulfoxide;

[0044] S2. Uniformly scrape the casting solution on the surface of a macroporous organic membrane to form a 20-μm-thick coating. Let it stand at room temperature for 2 min, and then immerse it in deionized water at 30 °C for 25 min to obtain a filter membrane.

[0045] Example 4

[0046] The difference from Example 1 is that in step S1, the cyclodextrin is pretreated before stirring the cyclodextrin and the verbena extract.

[0047] S1. The cyclodextrin pretreatment step is as follows: Mix cyclodextrin, diethanolamine, and tetrahydrofuran with a mass ratio of 1:90:200, stir and react at 50°C for 6 hours, carry out condensation reflux, after 5 hours, precipitate the product into an acetone solution with a straw, separate, and dry;

[0048] Mix 3 parts of pretreated cyclodextrin and 15 parts of verbena extract by weight under the conditions of 40°C and ultrasonic stirring for 12 hours. The ultrasonic frequency is 40KHZ, filter, let the filtrate stand at 4°C, crystallize, carry out suction filtration, dry the crystals at 40°C, then add 5 parts of tetrapod-like zinc oxide whiskers, 15 parts of polyamide, 4 parts of pore-forming additive, and 65 parts of solvent and stir and mix to obtain a casting solution. Among them, the pore-forming additive uses polyethylene glycol and the solvent uses dimethyl sulfoxide.

[0049] Example 5

[0050] The difference from Example 1 is that the tetrapod-like zinc oxide whiskers are pretreated before adding the tetrapod-like zinc oxide whiskers.

[0051] S1. The pretreatment step of the tetrapod-like zinc oxide whiskers is as follows: Add the tetrapod-like zinc oxide whiskers to an aqueous solution of potassium sodium tartrate and stir for 10 minutes. The molar ratio of potassium sodium tartrate to the tetrapod-like zinc oxide whiskers is 0.1:100, and then while stirring, add an aqueous solution of copper chloride with an equimolar amount to potassium sodium tartrate; then continue to stir for 30 minutes, filter, wash, and dry, then heat up to 270°C in a hydrogen atmosphere and hold for 60 minutes, and cool to room temperature;

[0052] Mix 3 parts of cyclodextrin and 15 parts of verbena extract by weight under the conditions of 40°C and ultrasonic stirring for 12 hours. The ultrasonic frequency is 40KHZ, filter, let the filtrate stand at 4°C, crystallize, carry out suction filtration, dry the crystals at 40°C, then add 5 parts of pretreated tetrapod-like zinc oxide whiskers, 15 parts of polyamide, 4 parts of pore-forming additive, and 65 parts of solvent and stir and mix to obtain a casting solution. Among them, the pore-forming additive uses polyethylene glycol and the solvent uses dimethyl sulfoxide.

[0053] Example 6

[0054] The difference from Example 5 is that dodecylguanidine monohydrochloride is added to the filter membrane.

[0055] S1. The pretreatment step of the tetrapod-like zinc oxide whiskers is as follows: Add the tetrapod-like zinc oxide whiskers to an aqueous solution of potassium sodium tartrate and stir for 10 minutes. The molar ratio of potassium sodium tartrate to the tetrapod-like zinc oxide whiskers is 0.1:100, and then while stirring, add an aqueous solution of copper chloride with an equimolar amount to potassium sodium tartrate; then continue to stir for 30 minutes, filter, wash, and dry, then heat up to 270°C in a hydrogen atmosphere and hold for 60 minutes, and cool to room temperature;

[0056] 3 parts of cyclodextrin and 15 parts of verbena extract by weight are stirred at 40 °C under ultrasonic conditions for 12 h. The ultrasonic frequency is 40 KHZ. After filtration, the filtrate is left standing at 4 °C for crystallization, suction filtration, and the crystals are dried at 40 °C. Then, 5 parts of pretreated tetrapod-like zinc oxide whiskers, 3 parts of dodecylguanidine monohydrochloride, 15 parts of polyamide, 4 parts of pore-forming additive and 65 parts of solvent are added and stirred and mixed to obtain a casting solution. Among them, the pore-forming additive is polyethylene glycol and the solvent is dimethyl sulfoxide.

[0057] Example 7

[0058] The difference from Example 6 is that polyhexamethylene guanidine propionate is added to the filter membrane.

[0059] S1. The pretreatment step of tetrapod-like zinc oxide whiskers is as follows: The tetrapod-like zinc oxide whiskers are added to an aqueous solution of sodium potassium tartrate and stirred for 10 min. The molar ratio of sodium potassium tartrate to tetrapod-like zinc oxide whiskers is 0.1:100. Then, an aqueous solution of copper chloride with an equimolar amount to sodium potassium tartrate is added while stirring. After that, stirring is continued for 30 min, followed by filtration, washing, drying, and then heating to 270 °C in a hydrogen atmosphere and holding for 60 min, and cooling to room temperature.

[0060] 3 parts of cyclodextrin and 15 parts of verbena extract by weight are stirred at 40 °C under ultrasonic conditions for 12 h. The ultrasonic frequency is 40 KHZ. After filtration, the filtrate is left standing at 4 °C for crystallization, suction filtration, and the crystals are dried at 40 °C. Then, a mixture obtained by mixing 3 parts of polyhexamethylene guanidine propionate and 5 parts of pretreated tetrapod-like zinc oxide whiskers, 3 parts of dodecylguanidine monohydrochloride, 15 parts of polyamide, 4 parts of pore-forming additive and 65 parts of solvent are added and stirred and mixed to obtain a casting solution. Among them, the pore-forming additive is polyethylene glycol and the solvent is dimethyl sulfoxide.

[0061] Example 8

[0062] The present application discloses a preparation method of an antibacterial filter membrane, which includes the following steps:

[0063] S1. The pretreatment step of cyclodextrin is as follows: Cyclodextrin, diethanolamine and tetrahydrofuran with a mass ratio of 1:90:200 are mixed and stirred at 50 °C for a reaction of 6 h with condensation reflux. After 5 h, the product is precipitated into an acetone solution with a pipette, separated and dried.

[0064] The pretreatment steps of the tetrapod-like zinc oxide whiskers are as follows: Add the tetrapod-like zinc oxide whiskers into an aqueous solution of potassium sodium tartrate and stir for 10 min. The molar ratio of potassium sodium tartrate to tetrapod-like zinc oxide whiskers is 0.1:100. Then, while stirring, add an aqueous solution of copper chloride with an equimolar amount to potassium sodium tartrate. After that, continue stirring for 30 min, then filter, wash, and dry. Then, heat up to 270 °C in a hydrogen atmosphere and keep it warm for 60 min, and cool to room temperature;

[0065] Mix 3 parts of pretreated cyclodextrin and 15 parts of verbena extract by weight under the conditions of 40 °C and ultrasonic stirring for 12 h. The ultrasonic frequency is 40 KHZ. Filter, and let the filtrate stand at 4 °C for crystallization, then perform suction filtration. Place the crystals in a dryer at 40 °C. Then, add 3 parts of polyhexamethylene guanidine propionate, 5 parts of pretreated tetrapod-like zinc oxide whiskers, 3 parts of dodecylguanidine monohydrochloride, 15 parts of polyamide, 4 parts of pore-forming additive, and 65 - 75 parts of solvent and stir to mix, obtaining a casting solution. Among them, the pore-forming additive uses polyethylene glycol, and the solvent uses dimethyl sulfoxide;

[0066] S2. Uniformly scrape the casting solution on the surface of a macroporous organic membrane to form a 20 - μm - thick coating. Let it stand at room temperature for 1 min, and then immerse it in deionized water at 25 °C for 20 min to obtain a filter membrane.

[0067] Example 9

[0068] This application discloses a preparation method of an antibacterial filter membrane, including the following steps:

[0069] The pretreatment steps of cyclodextrin are as follows: Mix cyclodextrin, diethanolamine, and tetrahydrofuran with a mass ratio of 1:100:250, stir and react at 60 °C for 5 h with condensation reflux. After 5 h, precipitate the product into an acetone solution with a pipette, separate, and dry;

[0070] The pretreatment steps of the tetrapod-like zinc oxide whiskers are as follows: Add the tetrapod-like zinc oxide whiskers into an aqueous solution of potassium sodium tartrate and stir for 30 min. The molar ratio of potassium sodium tartrate to tetrapod-like zinc oxide whiskers is 1:100. Then, while stirring, add an aqueous solution of copper chloride with an equimolar amount to potassium sodium tartrate; after that, continue stirring for 60 min, then filter, wash, and dry. Then, heat up to 300 °C in a hydrogen atmosphere and keep it warm for 40 min, and cool to room temperature;

[0071] 5 parts of pretreated cyclodextrin and 20 parts of verbena extract by weight are stirred for 10 h at 50 °C under ultrasonic conditions, the ultrasonic frequency is 50 KHZ, filtered, the filtrate is left standing at 8 °C, crystallized, suction filtered, the crystals are dried at 50 °C, and then 4 parts of polyhexamethylene guanidine propionate and 8 parts of the mixture obtained by mixing pretreated tetrapod-like zinc oxide whiskers, 5 parts of dodecylguanidine monohydrochloride, 25 parts of polyamide, 6 parts of pore-forming additive and 75 parts of solvent are stirred and mixed to obtain a casting solution, wherein the pore-forming additive is polyethylene glycol and the solvent is dimethyl sulfoxide;

[0072] S2. The casting solution is evenly scrape-coated on the surface of a macroporous organic membrane to form a 20-μm-thick coating, left standing at room temperature for 2 min, and then immersed in deionized water at 35 °C for 30 min to obtain a filter membrane.

[0073] Example 10

[0074] This application discloses a preparation method of an antibacterial filter membrane, which includes the following steps:

[0075] S1. The cyclodextrin pretreatment step is: mixing cyclodextrin, diethanolamine and tetrahydrofuran with a mass ratio of 1:95:220, stirring and reacting at 55 °C for 6 h, with condensation reflux, after 5 h, precipitating the product into an acetone solution with a pipette, separating and drying;

[0076] The pretreatment step of tetrapod-like zinc oxide whiskers is: adding tetrapod-like zinc oxide whiskers to an aqueous solution of sodium potassium tartrate and stirring for 20 min, the molar ratio of sodium potassium tartrate to tetrapod-like zinc oxide whiskers is 0.5:100, and then adding an aqueous solution of copper chloride with an equimolar amount to sodium potassium tartrate while stirring; then continue stirring for 50 min, then filter, wash, dry, and then heat up to 280 °C in a hydrogen atmosphere and hold for 50 min, and cool to room temperature;

[0077] 4 parts of pretreated cyclodextrin and 17 parts of verbena extract by weight are stirred for 11 h at 45 °C under ultrasonic conditions, the ultrasonic frequency is 45 KHZ, filtered, the filtrate is left standing at 7 °C, crystallized, suction filtered, the crystals are dried at 45 °C, and then 4 parts of polyhexamethylene guanidine propionate and 7 parts of the mixture obtained by mixing pretreated tetrapod-like zinc oxide whiskers, 4 parts of dodecylguanidine monohydrochloride, 20 parts of polyamide, 5 parts of pore-forming additive and 70 parts of solvent are stirred and mixed to obtain a casting solution, wherein the pore-forming additive is polyethylene glycol and the solvent is dimethyl sulfoxide;

[0078] S2. The casting solution is evenly scrape-coated on the surface of a macroporous organic membrane to form a 20-μm-thick coating, left standing at room temperature for 2 min, and then immersed in deionized water at 30 °C for 25 min to obtain a filter membrane.

[0079] Example 11

[0080] The difference from Example 4 is that diethanolamine is replaced with ethanol.

[0081] Example 12

[0082] The difference from Example 6 is that dodecylguanidine monohydrochloride is replaced with sodium dodecylbenzenesulfonate.

[0083] Example 13

[0084] The difference from Example 7 is that dodecylguanidine monohydrochloride is replaced with sodium dodecylbenzenesulfonate.

[0085] Example 14

[0086] The difference from Example 7 is that polyhexamethylene guanidine propionate is replaced with guanidine hydrochloride.

[0087] Comparative Example

[0088] Comparative Example 1

[0089] The difference from Example 1 is that a filter membrane without adding cyclodextrin, verbena extract and tetrapod-like zinc oxide whiskers is used as a blank control group.

[0090] Comparative Example 2

[0091] The difference from Example 1 is that cyclodextrin is not added to the filter membrane.

[0092] Comparative Example 3

[0093] The difference from Example 1 is that tetrapod-like zinc oxide whiskers are replaced with calcium sulfate whiskers.

[0094] Performance Detection Test

[0095] (1) Antibacterial Performance Test (characterized by antibacterial rate): The antibacterial performances of Examples 1 - 14 and Comparative Examples 1 - 3 were tested according to the standard GB / T20944.3 - 2008 "Evaluation of Antibacterial Properties of Textiles - Part 3: Oscillation Method". The test strain was Staphylococcus aureus. The test results are shown in Table 1 below.

[0096] (2) Antibacterial Performance Persistence Test (characterized by antibacterial rate): The filter membranes of Example 1 and Comparative Examples 2 - 3 were washed 5 times according to the AATCC61 accelerated washing standard, and then the antibacterial performances of Example 1 and Comparative Examples 2 - 3 were tested according to the standard GB / T20944.3 - 2008 "Evaluation of Antibacterial Properties of Textiles - Part 3: Oscillation Method". The test strain was Staphylococcus aureus. The test results are shown in Table 2 below.

[0097] Table 1 Test Results of Antibacterial Performance

[0098] Bacteriostatic rate / % Example 1 85.5 Example 2 86.7 Example 3 85.8 Example 4 88.4 Example 5 90.8 Example 6 91.9 Example 7 94.1 Example 8 97.2 Example 9 98.1 Example 10 97.7 Example 11 85.9 Example 12 91.0 Example 13 92.6 Example 14 92.2 Comparative Example 1 0 Comparative Example 2 81.6 Comparative Example 3 78.4

[0099] Table 2 Results Table of Antibacterial Performance Persistence Test

[0100] Bacteriostatic rate / % Example 1 65.2 Comparative Example 2 47.3 Comparative Example 3 32.8

[0101] In summary, the following conclusions can be drawn:

[0102] 1. By combining Example 1 and Comparative Examples 1-2 and referring to Tables 1-2, it can be seen that adding cyclodextrin and verbena extract to the filter membrane together can improve the antibacterial effect and the persistence of the antibacterial effect of the filter membrane. The reason may be that: the verbena extract is rich in anthraquinone and flavonoid compounds, and anthraquinone and flavonoid compounds have good antibacterial effects. After mixing cyclodextrin and verbena extract, the above compounds can be selectively extracted to form inclusion compounds, and the slow release of the above compounds can improve the antibacterial effect of the filter membrane in a long-term and lasting manner.

[0103] 2. By combining Example 1 and Comparative Examples 1, 3 and referring to Tables 1-2, it can be seen that adding tetrapod-like zinc oxide whiskers to the filter membrane can improve the persistence of the antibacterial effect of the filter membrane. The reason may be that: tetrapod-like zinc oxide whiskers have a three-dimensional tetrapod-like structure. After mixing with other components of the filter membrane, the tetrapod-like zinc oxide whiskers overlap with each other to form a three-dimensional network framework, thereby locking the cyclodextrin inclusion compound within the framework structure. When using the filter membrane for separation, the loss of the cyclodextrin inclusion compound can be reduced, and the persistence of the antibacterial effect of the filter membrane can be improved.

[0104] 3. By combining Examples 1, 4, 11 and referring to Table 1, it can be seen that pretreating cyclodextrin can improve the antibacterial effect of the filter membrane. The reason may be that: introducing hydroxyl groups onto cyclodextrin increases the polarity of the cyclodextrin surface. After mixing, it can increase the surface free energy of the filter membrane, improve the anti-bacterial adhesion performance of the filter membrane, make it difficult for bacteria to colonize on the surface of the filter membrane, inhibit the growth of bacteria on the filter membrane, and further improve the antibacterial performance of the filter membrane.

[0105] 4. By combining Examples 1, 5 and referring to Table 1, it can be seen that pretreating tetrapod-like zinc oxide whiskers can improve the antibacterial effect of the filter membrane. The reason may be that: uniformly depositing nano-copper particles on the surface of tetrapod-like zinc oxide whiskers further improves the antibacterial effect of the filter membrane, and the nano-copper particles and tetrapod-like zinc oxide whiskers are firmly combined. When using the filter membrane for separation, the loss of nano-copper particles can be reduced, which is beneficial to improving the persistence of the antibacterial performance of the filter membrane.

[0106] 5. By combining Examples 1, 6 and referring to Table 1, it can be seen that adding dodecylguanidine monohydrochloride to the filter membrane is beneficial to improving the antibacterial effect of the filter membrane. The reason may be that: dodecylguanidine monohydrochloride is a polymer. When bacteria adhere to the filter membrane, it can block the respiratory channels of bacteria, causing the bacteria to suffocate and die, thereby improving the antibacterial performance of the filter membrane.

[0107] 6. Combining Example 1, Examples 6 - 7, and Examples 12 - 14 and referring to Table 1, it can be seen that adding dodecylguanidine monohydrochloride and polyhexamethylene guanidine propionate together in the filter membrane is beneficial to improving the antibacterial effect of the filter membrane. The reason may be as follows: Polyhexamethylene guanidine propionate has chelating properties for metal nanoparticles and can form positive charges on the surface of the nano - copper particles attached to the surface of the tetrapod - shaped zinc oxide whiskers. Through electrostatic interaction, it inhibits the agglomeration between the nano - copper particles and promotes the uniform dispersion of the tetrapod - shaped zinc oxide whiskers, thus promoting the construction of the three - dimensional framework. On the other hand, when polyhexamethylene guanidine propionate is used in combination with dodecylguanidine monohydrochloride, the guanidine group has high activity. Since it is positively charged in aqueous solution, it can adsorb negatively charged bacteria, thereby inhibiting the division function of bacteria and causing bacteria to lose their reproductive ability, further improving the antibacterial effect of the filter membrane.

[0108] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively according to needs, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing an antibacterial filter membrane, characterized in that: The following steps are involved: S1. 3-5 parts of cyclodextrin and 15-20 parts of verbena extract in parts by weight are stirred at 40-50 ° C for 10-12h, filtered, and the filtrate is allowed to stand at 4-8 ° C, crystallized, filtered, and the crystals are placed at 40-50 ° C to dry, and then 5-8 parts of four-needle zinc oxide whiskers, 15-25 parts of polyamide, 4-6 parts of pore-forming additives and 65-75 parts of solvent are added and stirred to obtain a casting solution. The preparation method of the verbena extract is as follows: crushing verbena, then adding eight times the weight of 80 (v / v)% ethanol solution, heating to boiling, reflux extraction for 3h, filtering, and continuing to add eight times the weight of 80 (v / v)% ethanol solution to the filter residue, heating to boiling, reflux extraction for 3h, and filtering to obtain verbena extract; S2. The casting solution is evenly scraped onto the surface of the macroporous organic membrane to form a coating, which is allowed to stand at room temperature for 1-2 minutes. The membrane is then immersed in deionized water at 25-35°C for 20-30 minutes to obtain a filter membrane.

2. The method for preparing an antibacterial filter membrane according to claim 1, wherein: In S1, the cyclodextrin is pretreated before the cyclodextrin and verbena extract are stirred. The cyclodextrin pretreatment step is: mixing cyclodextrin, diethanolamine and tetrahydrofuran in a mass ratio of 1: (90-100): (200-250), stirring and reacting at 50-60° C. for 5-6 hours, condensing and refluxing, and after 5 hours, precipitating the product in an acetone solution, separating, and drying.

3. The method for preparing the antibacterial filter membrane according to claim 1, wherein: In S1, the tetrapod-shaped zinc oxide whiskers are pretreated before being added. The tetrapod-shaped zinc oxide whiskers pretreatment step comprises: adding the tetrapod-shaped zinc oxide whiskers to an aqueous solution of potassium sodium tartrate and stirring for 10-30 minutes, wherein the molar ratio of potassium sodium tartrate to the tetrapod-shaped zinc oxide whiskers is (0.1-1):100; then, adding an aqueous solution of copper chloride in an amount equimolar to the potassium sodium tartrate while stirring; then, continuing stirring for 30-60 minutes, filtering, washing, and drying, and then heating to 270-300° C. in a hydrogen atmosphere, maintaining the temperature for 40-60 minutes, and cooling to room temperature.

4. The method for preparing the antibacterial filter membrane according to claim 3, wherein: In S1, the crystals are dried at 40-50° C., and then 5-8 parts by weight of pretreated tetrapod-shaped zinc oxide whiskers, 3-5 parts by weight of dodecylguanidine monohydrochloride, 15-25 parts by weight of polyamide, 4-6 parts by weight of a pore-forming additive, and 65-75 parts by weight of a solvent are added and stirred to obtain a casting solution.

5. The method for preparing the antibacterial filter membrane according to claim 4, characterized in that: In the S1, the crystals are dried at 40-50° C., and then a mixture of 3-4 parts by weight of polyhexamethyleneguanidine propionate and 5-8 parts by weight of pretreated tetrapod-shaped zinc oxide whiskers, 3-5 parts by weight of dodecylguanidine monohydrochloride, 15-25 parts by weight of polyamide, 4-6 parts by weight of a pore-forming additive, and 65-75 parts by weight of a solvent are added and stirred to obtain a casting solution.

6. The method for preparing an antibacterial filter membrane according to claim 1, wherein: In the above S1, 3-5 parts by weight of cyclodextrin and 15-20 parts by weight of verbena extract are stirred at 40-50° C. under ultrasonic conditions for 10-12 hours.

7. The method for preparing an antibacterial filter membrane according to claim 6, wherein: The frequency of the ultrasound is 40-50 KHZ.