A microporous membrane with long-acting antibacterial function and a preparation method thereof

Abstract

This invention discloses a microporous membrane with long-lasting antibacterial function and its preparation method, belonging to the field of water treatment technology. The invention employs a phase inversion method, which requires minimal equipment and is easy to operate, avoiding the complex equipment needs and stringent operating conditions of traditional high-temperature melt extrusion or solution spinning processes. By in-situ polymerizing and modifying antibacterial powders within the microporous membrane structure, the long-lasting antibacterial effect and mechanical properties of the microporous membrane are significantly improved, solving problems such as easy loss of antibacterial components, effect attenuation, and insufficient interfacial bonding strength in traditional physically mixed antibacterial membranes.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a microporous membrane with long-lasting antibacterial function and its preparation method. Background Technology

[0002] Membrane separation technology utilizes membranes with selective permeability as the separation medium. By applying or having one or more driving forces on both sides of the membrane, a certain component in the raw material selectively and preferentially permeates through the membrane, thereby achieving the separation of the mixture and realizing the extraction, concentration, and purification of products. Microporous membranes are the core component of membrane separation technology, with pore sizes typically ranging from 0.1 to 10 μm. They can effectively retain pollutants such as bacteria, viruses, and colloidal particles, and are widely used in drinking water purification, wastewater treatment, and seawater desalination pretreatment. Commonly used membrane materials include polymers such as polyvinylidene fluoride, polyethersulfone, and polyacrylonitrile. With increasingly stringent water treatment standards and the continuous expansion of application fields, the performance requirements for microporous membranes are also increasing, especially in terms of stability and reliability during long-term operation.

[0003] However, existing microporous membrane technologies face severe challenges from biofouling in practical applications. While traditional microporous membranes can physically trap bacteria and other microorganisms, the membrane surface easily becomes a site for bacterial adhesion and reproduction, leading to biofilm fouling. This results in a sharp decline in membrane flux, reduced separation efficiency, and increased cleaning frequency, severely impacting the operating efficiency and lifespan of the membrane system.

[0004] Chinese patent document CN114247308A discloses a PVDF ultrafiltration membrane formulation and its preparation method with antibacterial properties. This addresses the problem that existing PVDF ultrafiltration membranes are prone to self-fouling and bacterial growth during long-term water filtration, resulting in poor purification and water pollution. The proposed solution comprises the following components in the following weight percentages: 12-22% polyvinylidene fluoride powder, 0-30% polyvinylpyrrolidone, 60-80% N,N-dimethylacetamide, and 0.3-1.2% levofloxacin; the polyvinylidene fluoride powder is PVDF powder dried under vacuum for 12 hours. This PVDF membrane exhibits high antifouling ability and improves its treatment efficiency in water treatment, effectively ensuring water quality. However, the antibacterial agent levofloxacin used in this patent is directly blended with the membrane material to prepare the antibacterial membrane, which suffers from weak adhesion to the membrane substrate, easy loss during use, and rapid attenuation of the antibacterial effect. Summary of the Invention

[0005] The main objective of this invention is to propose a microporous membrane with long-lasting antibacterial function and its preparation method. By in-situ polymerization of modified antibacterial powder on a membrane substrate, the prepared microporous membrane has long-lasting antibacterial properties.

[0006] To achieve the above objectives, this invention proposes a method for preparing a microporous membrane with long-lasting antibacterial function, comprising the following steps:

[0007] Modified antibacterial powder was dispersed in N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, polyvinylidene fluoride and polyvinylpyrrolidone were pretreated and dissolved in N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were then mixed evenly, and azobisisobutyronitrile was added. The mixture was heated to react, and after the reaction was completed, it was cooled. The reaction solution was placed in a vacuum environment to degas and then evenly spread on a nonwoven fabric. The nonwoven fabric was immersed in deionized water, and the resulting membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0008] Preferably, the mass ratio of the modified antibacterial powder, pretreated polyvinylidene fluoride, and polyvinylpyrrolidone is 4-8:100:40-50.

[0009] Preferably, the preparation method of the modified antibacterial powder includes the following steps:

[0010] (1) Disperse graphene oxide in water, then add copper sulfate pentahydrate and stir until completely dissolved, add NaOH aqueous solution and mix evenly, then transfer to a high-pressure reactor for hydrothermal reaction to obtain antibacterial powder;

[0011] (2) The composite powder was dispersed in an aqueous ethanol solution, γ-glycidoxypropyltrimethoxysilane was added, and the mixture was heated to obtain an epoxidized antibacterial powder.

[0012] (3) Linalool and juniper alcohol are added to N,N-dimethylformamide, epoxidized antibacterial powder and triethylamine are added, and the mixture is heated under a nitrogen atmosphere to obtain modified antibacterial powder.

[0013] Preferably, in step (1), the mass ratio of graphene oxide to copper sulfate pentahydrate is 5-10:3-5; the concentration of the NaOH aqueous solution is 1-3 mol / L; the hydrothermal reaction temperature is 180-200℃; and the reaction time is 10-12 h.

[0014] Preferably, in step (2), the mass ratio of the composite powder to γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.03-0.05; the heating temperature is 30-50℃ and the heating time is 4-6h.

[0015] Preferably, in step (3), the mass ratio of linalool, juniper alcohol, and epoxidized antibacterial powder is 0.02-0.04:0.01-0.03:1; the heating temperature is 50-80℃, and the heating time is 4-6h.

[0016] The preparation of the modified antibacterial powder of this invention first involves the in-situ growth of copper oxide on graphene through a hydrothermal reaction, which prevents the agglomeration of copper oxide. Then, active epoxy groups are introduced on the surface of the antibacterial powder. The epoxy groups react with the hydroxyl groups on the antibacterial active molecules linalool and juniper alcohol, thereby fixing the antibacterial active molecules on the antibacterial powder and endowing it with multiple antibacterial mechanisms, which is beneficial to further improve the antibacterial performance of the antibacterial powder. At the same time, the linalool molecule introduced contains carbon-carbon double bonds, which is beneficial to the subsequent reaction with pretreated polyvinylidene fluoride.

[0017] Preferably, the pretreated polyvinylidene fluoride is alkali-treated polyvinylidene fluoride, and its preparation method is as follows: polyvinylidene fluoride powder is placed in an aqueous sodium hydroxide solution, N,N-dimethylformamide is added, the mixture is heated and stirred, cooled, filtered, the solid is collected and washed until the filtrate is neutral, and dried to obtain pretreated polyvinylidene fluoride; the concentration of the aqueous sodium hydroxide solution is 10-30 wt%, and the heating temperature is 50-80℃.

[0018] Under alkaline conditions and heating, the fluorine atoms on the PVDF molecular chain react to form C=C double bonds, which can polymerize with the carbon-carbon double bonds on the modified antibacterial powder. This increases the bonding strength between PVDF and the modified antibacterial powder, allowing it to be used for a long time even under high impact and giving the microporous membrane long-lasting antibacterial properties.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1) This invention provides a microporous membrane with long-lasting antibacterial function and its preparation method. The preparation process adopts the phase inversion method, which has low equipment requirements and is easy to operate. It avoids the complex equipment requirements and harsh operating conditions of traditional high-temperature melt extrusion or solution spinning processes. By introducing modified antibacterial powder into the microporous membrane structure, the long-lasting antibacterial effect and mechanical properties of the microporous membrane are significantly improved, and the problems of easy loss of antibacterial components, effect decay and insufficient interfacial bonding strength of traditional physically mixed antibacterial membranes are solved.

[0021] 2) The preparation of the modified antibacterial powder of this invention firstly involves hydrothermal reaction to allow copper oxide to grow in situ on graphene, forming a uniformly dispersed composite structure. This prevents the agglomeration of copper oxide and facilitates synergistic antibacterial action with graphene. Then, epoxy groups are introduced onto the surface of the antibacterial powder, which facilitates the reaction with the hydroxyl groups on the subsequent antibacterial active molecules linalool and juniper alcohol, fixing the antibacterial active molecules onto the antibacterial powder. This avoids the defects of easy detachment in traditional physical mixing and provides carbon-carbon double bonds for subsequent interaction with pretreated polyvinylidene fluoride. By modifying the antibacterial powder and pretreating polyvinylidene fluoride, the bonding strength between polyvinylidene fluoride and the modified powder can be improved, forming a chemical cross-linked network structure. This gives the microporous membrane good mechanical properties and chemical stability, avoids interfacial loosening caused by handling agents, ensures the stability and reliability of the membrane system, and endows the microporous membrane with long-lasting antibacterial function. Detailed Implementation

[0022] To avoid unnecessary details, unless otherwise specified, all items used in the following examples are commercially available products, and all methods used are conventional methods unless otherwise specified.

[0023] The sources of some of the raw materials used in this invention are as follows:

[0024] Graphene oxide, with a single-layer sheet diameter of 50-500 nm, was purchased from Shanghai Maoguo Nanotechnology Co., Ltd.

[0025] Example 1

[0026] A method for preparing a microporous membrane with long-lasting antibacterial function includes the following steps:

[0027] (1) Disperse 8g of graphene oxide in 200mL of water, then add 4.5g of copper sulfate pentahydrate and stir until completely dissolved. Add 150mL of 2mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 200℃ for 12h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h and grind to obtain antibacterial powder.

[0028] (2) Disperse 8g of composite powder in 120mL of 50wt% ethanol aqueous solution, add 0.32g of γ-glycidyl etheroxypropyltrimethoxysilane, heat at 40℃ for 4h, filter, collect solid product, wash and dry to obtain epoxidized antibacterial powder;

[0029] (3) Add 0.24g linalool and 0.16g juniper alcohol to 150mL N,N-dimethylformamide, add 8g epoxidized antibacterial powder and 0.1g triethylamine, and heat the mixture at 60℃ for 5h under nitrogen atmosphere. After the reaction is completed, collect the solid product, wash and dry it to obtain the modified antibacterial powder.

[0030] (4) Place 100g of polyvinylidene fluoride powder in a 10wt% sodium hydroxide aqueous solution, add 5mL of N,N-dimethylformamide, heat and stir at 50℃ for 6h, cool, filter, collect the solids, wash until the filtrate is neutral, and dry to obtain pretreated polyvinylidene fluoride.

[0031] (5) 3.3g of modified antibacterial powder was dispersed in 50mL of N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, 50g of pretreated polyvinylidene fluoride and 20g of polyvinylpyrrolidone were dissolved in 350mL of N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were mixed evenly, and 0.7g of azobisisobutyronitrile was added. The mixture was heated at 60℃ for 6h. After the reaction was completed, the mixture was cooled. The reaction solution was placed in a vacuum environment to degas and spread evenly on a nonwoven fabric. It was left in the air for 20s. Then, the nonwoven fabric was immersed in deionized water. The obtained membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0032] Example 2

[0033] A method for preparing a microporous membrane with long-lasting antibacterial function includes the following steps:

[0034] (1) Disperse 5g of graphene oxide in 200mL of water, then add 3g of copper sulfate pentahydrate and stir until completely dissolved. Add 120mL of 1mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 200℃ for 10h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h and grind to obtain antibacterial powder.

[0035] (2) Disperse 8g of composite powder in 120mL of 50wt% ethanol aqueous solution, add 0.24g of γ-glycidyl etheroxypropyltrimethoxysilane, heat at 40℃ for 4h, filter, collect solid product, wash and dry to obtain epoxidized antibacterial powder;

[0036] (3) Add 0.16g linalool and 0.08g juniper alcohol to 150mL N,N-dimethylformamide, add 8g epoxidized antibacterial powder and 0.1g triethylamine, and heat the mixture at 50℃ for 6h under a nitrogen atmosphere. After the reaction is complete, collect the solid product, wash and dry it to obtain the modified antibacterial powder.

[0037] (4) Place 100g of polyvinylidene fluoride powder in a 30wt% sodium hydroxide aqueous solution, add 5mL of N,N-dimethylformamide, heat and stir at 50℃ for 6h, cool, filter, collect the solids, wash until the filtrate is neutral, and dry to obtain pretreated polyvinylidene fluoride.

[0038] (5) 2g of modified antibacterial powder was dispersed in 50mL of N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, 50g of pretreated polyvinylidene fluoride and 23g of polyvinylpyrrolidone were dissolved in 350mL of N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were mixed evenly, and 0.6g of azobisisobutyronitrile was added. The mixture was heated at 60℃ for 4h. After the reaction was completed, the mixture was cooled. The reaction solution was placed in a vacuum environment to degas and spread evenly on a nonwoven fabric. It was left in the air for 20s. Then, the nonwoven fabric was immersed in deionized water. The obtained membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0039] Example 3

[0040] A method for preparing a microporous membrane with long-lasting antibacterial function includes the following steps:

[0041] (1) Disperse 10g of graphene oxide in 200mL of water, then add 5g of copper sulfate pentahydrate and stir until completely dissolved. Add 180mL of 3mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 180℃ for 12h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h and grind to obtain antibacterial powder.

[0042] (2) Disperse 8g of composite powder in 120mL of 50wt% ethanol aqueous solution, add 0.4g of γ-glycidyl etheroxypropyltrimethoxysilane, heat at 40℃ for 4h, filter, collect solid product, wash and dry to obtain epoxidized antibacterial powder;

[0043] (3) Add 0.32g linalool and 0.24g juniper alcohol to 150mL N,N-dimethylformamide, add 8g epoxidized antibacterial powder and 0.1g triethylamine, and heat the mixture at 80℃ for 4h under nitrogen atmosphere. After the reaction is completed, collect the solid product, wash and dry it to obtain the modified antibacterial powder.

[0044] (4) Place 100g of polyvinylidene fluoride powder in a 30wt% sodium hydroxide aqueous solution, add 5mL of N,N-dimethylformamide, heat and stir at 50℃ for 6h, cool, filter, collect the solids, wash until the filtrate is neutral, and dry to obtain pretreated polyvinylidene fluoride.

[0045] (5) 4g of modified antibacterial powder was dispersed in 50mL of N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, 50g of pretreated polyvinylidene fluoride and 25g of polyvinylpyrrolidone were dissolved in 350mL of N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were mixed evenly, and 0.9g of azobisisobutyronitrile was added. The mixture was heated at 60℃ for 6h. After the reaction was completed, the mixture was cooled. The reaction solution was placed in a vacuum environment to degas and spread evenly on a nonwoven fabric. It was left in the air for 20s. Then, the nonwoven fabric was immersed in deionized water. The obtained membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0046] Comparative Example 1

[0047] A method for preparing a microporous membrane with long-lasting antibacterial function is the same as in Example 1, except that the polyvinylidene fluoride is not pretreated. The method specifically includes the following steps:

[0048] (1) Disperse 8g of graphene oxide in 200mL of water, then add 4.5g of copper sulfate pentahydrate and stir until completely dissolved. Add 150mL of 2mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 200℃ for 12h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h and grind to obtain antibacterial powder.

[0049] (2) Disperse 8g of composite powder in 120mL of 50wt% ethanol aqueous solution, add 0.32g of γ-glycidyl etheroxypropyltrimethoxysilane, heat at 40℃ for 4h, filter, collect solid product, wash and dry to obtain epoxidized antibacterial powder;

[0050] (3) Add 0.24g linalool and 0.16g juniper alcohol to 150mL N,N-dimethylformamide, add 8g epoxidized antibacterial powder and 0.1g triethylamine, and heat the mixture at 60℃ for 5h under nitrogen atmosphere. After the reaction is completed, collect the solid product, wash and dry it to obtain the modified antibacterial powder.

[0051] (4) 3.3g of modified antibacterial powder was dispersed in 50mL of N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, 50g of polyvinylidene fluoride and 20g of polyvinylpyrrolidone were dissolved in 350mL of N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were mixed evenly, and 0.7g of azobisisobutyronitrile was added. The mixture was heated at 60℃ for 6h. After the reaction was completed, the mixture was cooled. The reaction solution was placed in a vacuum environment to degas and spread evenly on a nonwoven fabric. It was left in the air for 20s. Then, the nonwoven fabric was immersed in deionized water. The obtained membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0052] Comparative Example 2

[0053] A method for preparing a microporous membrane with long-lasting antibacterial function is the same as in Example 1, except that linalool is not added to the modified antibacterial powder. The method specifically includes the following steps:

[0054] (1) Disperse 8g of graphene oxide in 200mL of water, then add 4.5g of copper sulfate pentahydrate and stir until completely dissolved. Add 150mL of 2mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 200℃ for 12h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h and grind to obtain antibacterial powder.

[0055] (2) Disperse 8g of composite powder in 120mL of 50wt% ethanol aqueous solution, add 0.32g of γ-glycidyl etheroxypropyltrimethoxysilane, heat at 40℃ for 4h, filter, collect solid product, wash and dry to obtain epoxidized antibacterial powder;

[0056] (3) Add 0.4g of juniper alcohol to 150mL of N,N-dimethylformamide, add 8g of epoxidized antibacterial powder and 0.1g of triethylamine, and heat the mixture at 60℃ for 5h under a nitrogen atmosphere. After the reaction is completed, collect the solid product, wash and dry it to obtain the modified antibacterial powder.

[0057] (4) Place 100g of polyvinylidene fluoride powder in a 10wt% sodium hydroxide aqueous solution, add 5mL of N,N-dimethylformamide, heat and stir at 50℃ for 6h, cool, filter, collect the solids, wash until the filtrate is neutral, and dry to obtain pretreated polyvinylidene fluoride.

[0058] (5) 3.3g of modified antibacterial powder was dispersed in 50mL of N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, 50g of pretreated polyvinylidene fluoride and 20g of polyvinylpyrrolidone were dissolved in 350mL of N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were mixed evenly, and 0.7g of azobisisobutyronitrile was added. The mixture was heated at 60℃ for 6h. After the reaction was completed, the mixture was cooled. The reaction solution was placed in a vacuum environment to degas and spread evenly on a nonwoven fabric. It was left in the air for 20s. Then, the nonwoven fabric was immersed in deionized water. The obtained membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0059] Comparative Example 3

[0060] A method for preparing a microporous membrane with long-lasting antibacterial function is the same as in Example 1, except that the antibacterial powder is not modified. The method specifically includes the following steps:

[0061] (1) Disperse 8g of graphene oxide in 200mL of water, then add 4.5g of copper sulfate pentahydrate and stir until completely dissolved. Add 150mL of 2mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 200℃ for 12h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h and grind to obtain antibacterial powder.

[0062] (2) Place 100g of polyvinylidene fluoride powder in a 10wt% sodium hydroxide aqueous solution, add 5mL of N,N-dimethylformamide, heat and stir at 50℃ for 6h, cool, filter, collect the solids, wash until the filtrate is neutral, and dry to obtain pretreated polyvinylidene fluoride.

[0063] (3) Disperse 3.3g of antibacterial powder in 50mL of N,N-dimethylacetamide to obtain an antibacterial powder dispersion. Then, dissolve 50g of pretreated polyvinylidene fluoride and 20g of polyvinylpyrrolidone in 350mL of N,N-dimethylacetamide to obtain a casting solution. Mix the antibacterial powder dispersion and the casting solution evenly, add 0.7g of azobisisobutyronitrile, and heat at 60℃ for 6h. After the reaction is completed, cool the solution, place it in a vacuum environment to degas and spread it evenly on a nonwoven fabric. Let it stay in the air for 20s, then immerse the nonwoven fabric in deionized water. Clean the obtained membrane material to obtain a microporous membrane with long-lasting antibacterial function.

[0064] Comparative Example 4

[0065] A method for preparing a microporous membrane with long-lasting antibacterial function is similar to that in Example 1, except that linalool and juniper alcohol are physically mixed, and specifically includes the following steps:

[0066] (1) Disperse 8g of graphene oxide in 200mL of water, then add 4.5g of copper sulfate pentahydrate and stir until completely dissolved. Add 150mL of 2mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 200℃ for 12h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h and grind to obtain antibacterial powder.

[0067] (2) Disperse 8g of composite powder in 120mL of 50wt% ethanol aqueous solution, add 0.32g of γ-glycidyl etheroxypropyltrimethoxysilane, heat at 40℃ for 4h, filter, collect solid product, wash and dry to obtain epoxidized antibacterial powder;

[0068] (3) Mix 0.24g linalool, 0.16g juniper alcohol and 8g epoxidized antibacterial powder evenly to obtain modified antibacterial powder;

[0069] (4) Place 100g of polyvinylidene fluoride powder in a 10wt% sodium hydroxide aqueous solution, add 5mL of N,N-dimethylformamide, heat and stir at 50℃ for 6h, cool, filter, collect the solids, wash until the filtrate is neutral, and dry to obtain pretreated polyvinylidene fluoride.

[0070] (5) 3.3g of modified antibacterial powder was dispersed in 50mL of N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, 50g of pretreated polyvinylidene fluoride and 20g of polyvinylpyrrolidone were dissolved in 350mL of N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were mixed evenly, and 0.7g of azobisisobutyronitrile was added. The mixture was heated at 60℃ for 6h. After the reaction was completed, the mixture was cooled. The reaction solution was placed in a vacuum environment to degas and spread evenly on a nonwoven fabric. It was left in the air for 20s. Then, the nonwoven fabric was immersed in deionized water. The obtained membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0071] Comparative Example 5

[0072] A method for preparing a microporous membrane with long-lasting antibacterial function is similar to that in Example 1, except that graphene oxide and copper oxide are physically mixed, and specifically includes the following steps:

[0073] (1) Add 4.5g of copper sulfate pentahydrate to 200mL of water and stir until completely dissolved. Add 150mL of 2mol / L NaOH aqueous solution and mix evenly. Then transfer to a high-pressure reactor and carry out hydrothermal reaction at 200℃ for 12h. After the reaction is completed, cool, filter, centrifuge to collect the solid, wash and calcine at 500℃ for 2h, grind and then mix evenly with 8g of graphene oxide to obtain antibacterial powder.

[0074] (2) Disperse 8g of composite powder in 120mL of 50wt% ethanol aqueous solution, add 0.32g of γ-glycidyl etheroxypropyltrimethoxysilane, heat at 40℃ for 4h, filter, collect solid product, wash and dry to obtain epoxidized antibacterial powder;

[0075] (3) Add 0.24g linalool and 0.16g juniper alcohol to 150mL N,N-dimethylformamide, add 8g epoxidized antibacterial powder and 0.1g triethylamine, and heat the mixture at 60℃ for 5h under nitrogen atmosphere. After the reaction is completed, collect the solid product, wash and dry it to obtain the modified antibacterial powder.

[0076] (4) Place 100g of polyvinylidene fluoride powder in a 10wt% sodium hydroxide aqueous solution, add 5mL of N,N-dimethylformamide, heat and stir at 50℃ for 6h, cool, filter, collect the solids, wash until the filtrate is neutral, and dry to obtain pretreated polyvinylidene fluoride.

[0077] (5) 3.3g of modified antibacterial powder was dispersed in 50mL of N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, 50g of pretreated polyvinylidene fluoride and 20g of polyvinylpyrrolidone were dissolved in 350mL of N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were mixed evenly, and 0.7g of azobisisobutyronitrile was added. The mixture was heated at 60℃ for 6h. After the reaction was completed, the mixture was cooled. The reaction solution was placed in a vacuum environment to degas and spread evenly on a nonwoven fabric. It was left in the air for 20s. Then, the nonwoven fabric was immersed in deionized water. The obtained membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function.

[0078] Performance testing

[0079] The test subjects were the microporous membranes with long-lasting antibacterial function obtained in each embodiment and comparative example.

[0080] Antibacterial performance: Then, each microporous membrane was fixed in the filtration device and continuously filtered with deionized water at a pressure of 0.1 MPa for 2 hours. It was then repeatedly rinsed with deionized water at a pressure of 0.05 MPa. The antibacterial performance was determined at 100h, 300h, 500h and 1000h according to GB / T37206-2018 "Test Method for Antibacterial Performance of Organic Separation Membranes".

[0081] Water flux: The microporous membrane was fixed in a beaker and pre-pressurized with deionized water at 0.1 MPa for 30 min. Then, the pure water flux (L / m³) was measured at 0.1 MPa. 2 h);

[0082] Internal pressure destruction water pressure test: Under an environment of 25±2℃, a stable water pressure was applied to one side of the microporous membrane samples prepared in Examples 1-5 and Comparative Examples 1-5, and the water pressure that was withstood when a destructive water column was generated on the surface of the microporous membrane was recorded; the test results are shown in Table 1:

[0083] Table 1 Performance test results of microporous membranes with long-lasting antibacterial function

[0084]

[0085] As can be seen from the experimental results in Table 1, the microporous membrane prepared by this invention has good long-lasting antibacterial function and mechanical properties.

[0086] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for preparing a microporous membrane with long-lasting antibacterial function, characterized in that, Includes the following steps: Modified antibacterial powder was dispersed in N,N-dimethylacetamide to obtain a modified antibacterial powder dispersion. Then, polyvinylidene fluoride and polyvinylpyrrolidone were pretreated and dissolved in N,N-dimethylacetamide to obtain a casting solution. The modified antibacterial powder dispersion and the casting solution were then mixed evenly, and azobisisobutyronitrile was added. The mixture was heated to react, and after the reaction was completed, it was cooled. The reaction solution was placed in a vacuum environment to degas and then evenly spread on a nonwoven fabric. The nonwoven fabric was immersed in deionized water, and the resulting membrane material was cleaned to obtain a microporous membrane with long-lasting antibacterial function. The preparation method of the modified antibacterial powder includes the following steps: (1) Disperse graphene oxide in water, then add copper sulfate pentahydrate and stir until completely dissolved, add NaOH aqueous solution and mix evenly, then transfer to a high-pressure reactor for hydrothermal reaction to obtain antibacterial powder; (2) The composite powder was dispersed in an aqueous ethanol solution, γ-glycidoxypropyltrimethoxysilane was added, and the mixture was heated to obtain an epoxidized antibacterial powder. (3) Linalool and juniper alcohol were added to N,N-dimethylformamide, epoxidized antibacterial powder and triethylamine were added, and the mixture was heated under a nitrogen atmosphere to obtain modified antibacterial powder; The pretreated polyvinylidene fluoride is alkali-treated polyvinylidene fluoride, and its preparation method is as follows: polyvinylidene fluoride powder is placed in an aqueous sodium hydroxide solution, N,N-dimethylformamide is added, the mixture is heated and stirred, cooled, filtered, the solid is collected and washed until the filtrate is neutral, and dried to obtain pretreated polyvinylidene fluoride.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the modified antibacterial powder, pretreated polyvinylidene fluoride, and polyvinylpyrrolidone is 4-8:100:40-50.

3. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of graphene oxide to copper sulfate pentahydrate is 5-10:3-5.

4. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the composite powder to γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.03-0.

05.

5. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of linalool, juniper alcohol, and epoxidized antibacterial powder is 0.02-0.04:0.01-0.03:

1.

6. A microporous membrane with long-lasting antibacterial function, characterized in that: It is prepared by the preparation method described in any one of claims 1-5.

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