Silver ion antibacterial PVDF hydrophilic filter membrane and preparation method thereof
By combining low-polymerization degree cellulose solution and two-dimensional montmorillonite, silver ion antibacterial agents are loaded, solving the problem of filter membranes being susceptible to microbial contamination. This results in a filter membrane with high efficiency in antibacterial activity and high water throughput, suitable for water treatment, food, and pharmaceutical fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-29
- Publication Date
- 2026-04-10
AI Technical Summary
Existing filter membranes are susceptible to microbial contamination during use, leading to decreased permeate flux and shortened membrane life. This is especially critical in pharmaceutical production where strict microbial control is required, making the uniform distribution of silver ions a key challenge.
A modified PVDF filter membrane is impregnated with a low-polymerization-degree cellulose solution, combined with two-dimensional montmorillonite and a silane coupling agent, and loaded with silver ion antibacterial agent by vacuum filtration or spraying to form intermolecular hydrogen bonds, thereby improving the bonding strength and antibacterial effect.
It achieves high hydrophilicity, antibacterial properties, and high water flow rate of PVDF filter membranes, inhibits bacterial growth, extends membrane life, and reduces production costs.
Smart Images
Figure BDA0004365688410000081 
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Abstract
Description
Technical Field
[0001] This application relates to the field of antibacterial filter membranes, and in particular to a silver ion antibacterial PVDF hydrophilic filter membrane and its preparation method. Background Technology
[0002] Pressure-driven membrane separation technologies (reverse osmosis, nanofiltration, ultrafiltration, and microfiltration) are widely used for concentration and separation in water treatment, food, pharmaceutical, chemical, and biotechnology fields due to their simple processes, purely physical filtration, and low energy consumption. However, membrane fouling can occur during operation. With increasing usage time, the permeate flux continuously declines, even altering the membrane's solute selectivity, leading to a reduced membrane lifespan and severely hindering the application and development of membrane technology. Membrane fouling is an extremely complex problem, with fouling in membrane systems primarily including inorganic, colloidal, organic, and biological fouling. Due to the powerful reproductive and metabolic capabilities of microorganisms, it is difficult to control and reduce fouling simply by lowering the concentration of microorganisms in the raw water; therefore, biological fouling is often more severe than inactive colloidal, organic, and inorganic fouling.
[0003] When stored, microorganisms can grow and alter the permeability of the filter membrane, affecting its use and reducing its shelf life. At the same time, if the microbial content is high when using the filter membrane, it can easily affect the liquid separated by the membrane. This is especially true in the pharmaceutical industry, where the control of microorganisms is particularly stringent.
[0004] In related technologies, silver ions are used to modify filter membranes for antibacterial purposes. However, how to achieve a large and uniform distribution of silver ions on the filter membrane is a key technological breakthrough that needs to be achieved. Summary of the Invention
[0005] To improve the antibacterial effect on filter membranes, this application provides a silver ion antibacterial PVDF hydrophilic filter membrane and its preparation method.
[0006] This application provides a silver ion antibacterial PVDF hydrophilic filter membrane and its preparation method, which adopts the following technical solution:
[0007] A method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane, characterized by comprising the following steps:
[0008] S1, Preparation of silver ion antibacterial agent: It is obtained by reacting two-dimensional montmorillonite solution with silver complex, and the silver complex is formed by complexing nano-silver nitrate with inorganic complex;
[0009] S2, Cellulose-modified PVDF filter membrane: Enzymatically processed cellulose is dissolved in trifluoroacetic acid by heating to obtain an enzymatically processed cellulose solution; the PVDF filter membrane is immersed in the enzymatically processed cellulose solution, then removed and vacuum dried, and then treated with anhydrous ethanol to obtain a cellulose-modified PVDF filter membrane.
[0010] S3, Preparation of silver ion antibacterial PVDF hydrophilic filter membrane: The silver ion antibacterial agent prepared in S1 is loaded onto the cellulose-modified PVDF filter membrane by suction filtration or spraying.
[0011] By adopting the above technical solution and immersing the cellulose in a low-polymerization-degree cellulose solution, cellulose molecules are uniformly coated on the surface and inner wall of the PVDF filter membrane. The modified PVDF filter membrane has good hydrophilicity and contains a large number of hydroxyl groups on its surface, which facilitates the formation of intermolecular hydrogen bonds with two-dimensional montmorillonite, thereby improving the bonding strength of the two-dimensional montmorillonite and making it less likely for silver ions and two-dimensional montmorillonite to be washed away by the liquid during use. At the same time, silver ions are loaded onto the two-dimensional montmorillonite, so that a large number of silver ions are loaded on the filter membrane. The surface of two-dimensional montmorillonite has a negative charge and a strong ability to load positively charged silver ions, which effectively inhibits bacterial growth. Meanwhile, montmorillonite is inexpensive and has good application prospects.
[0012] Optionally, the enzymatically processed cellulose is dissolved in trifluoroacetic acid at 80-100℃ to obtain a 50-90 g / L enzymatically processed cellulose solution; the PVDF filter membrane is immersed in the enzymatically processed cellulose solution for 30-60 seconds, and then vacuum dried at 80-100℃ until the humidity in the drying oven is 0-20%, to obtain a cellulose-modified PVDF filter membrane.
[0013] By adopting the above technical solution, the enzymatic cellulose dissolves quickly at 80-100℃, and is not easily destroyed by high temperature. The enzymatic cellulose is prepared by using glucose molecules catalyzed by cellulosylphosphatase, resulting in enzymatic cellulose with a low degree of polymerization of 10-30. This facilitates the uniform dispersion of enzymatic cellulose on the PVDF filter membrane. The cellulose solution on the PVDF surface is easy to flow, which is not conducive to the cellulose's fixation on the membrane surface. Therefore, it is necessary to dry the filter membrane to a humidity of 0-20%. When the drying temperature is too high, the enzymatic cellulose is easily decomposed, and when the drying temperature is too low, the drying efficiency is poor.
[0014] Optionally, in step S2, the vacuum-dried cellulose-modified PVDF filter membrane is soaked in anhydrous ethanol for 4-8 hours.
[0015] By adopting the above technical solution, anhydrous ethanol participates in the crystallization of enzymatically synthesized cellulose, thereby increasing the crystallinity of cellulose. Therefore, soaking the modified PVDF filter membrane in anhydrous ethanol for a specific time can effectively increase the water flow. At the same time, the presence of crystals increases the surface roughness, increases the effective area, and improves the adhesion strength of silver ion antibacterial agents.
[0016] Optionally, the two-dimensional montmorillonite solution is prepared by dispersing solid montmorillonite in a solvent, followed by stirring or ultrasonic crushing and centrifugation to obtain the supernatant solution.
[0017] By adopting the above technical solution, the preparation method of two-dimensional montmorillonite solution is simple, the raw material price is low, and the production cost is low after it is put into production.
[0018] Optionally, the solvent is water or an alcohol solvent.
[0019] By adopting the above technical solution, the cost of water-based solvents is low, and alcohol-based solvents facilitate the dispersion of montmorillonite in alcohol solvents.
[0020] Optionally, when the silver ion antibacterial agent is loaded onto the PVDF filter membrane by spraying, a silane coupling agent is added to the silver ion antibacterial agent.
[0021] By adopting the above technical solution, silane coupling agents effectively improve the bonding strength of silver ion antibacterial agents on the filter membrane.
[0022] Optionally, the silane coupling agent is KH-550.
[0023] By adopting the above technical solution, KH-550 raw materials are readily available, and the bonding strength of silver ion antibacterial agents on the filter membrane can be enhanced.
[0024] A silver ion antibacterial PVDF hydrophilic filter membrane is prepared by the above-mentioned method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane.
[0025] By adopting the above technical solutions, PVDF filter membranes possess the characteristics of high hydrophilicity and high water flow, while also exhibiting good antibacterial effects and good antibacterial durability.
[0026] In summary, this application includes at least one of the following beneficial technical effects:
[0027] 1. By immersing the PVDF filter membrane in a low-polymerization-degree cellulose solution, cellulose molecules are uniformly coated on the surface and inner wall of the PVDF filter membrane. The modified PVDF filter membrane has good hydrophilicity and its surface contains a large number of hydroxyl groups, which facilitates the formation of intermolecular hydrogen bonds with two-dimensional montmorillonite, thereby improving the bonding strength of the two-dimensional montmorillonite and preventing silver ions and two-dimensional montmorillonite from being washed away by the liquid during use. At the same time, silver ions are loaded onto the two-dimensional montmorillonite, so that a large number of silver ions are loaded on the filter membrane. The two-dimensional montmorillonite surface has a negative charge and a strong ability to load positively charged silver ions, which effectively inhibits bacterial growth. In addition, montmorillonite is inexpensive and has good application prospects.
[0028] 2. By soaking the cellulose in wastewater ethanol, the crystallization of cellulose is enhanced through the participation of anhydrous ethanol in the enzymatic crystallization process, thereby increasing the crystallinity of the cellulose and effectively improving the water flow of the modified PVDF filter membrane. At the same time, the presence of crystals increases the surface roughness, expands the effective area, enhances the adhesion strength of the silver ion antibacterial agent, and improves the antibacterial durability. Detailed Implementation
[0029] Preparation method of enzymatic cellulose: The enzymatic cellulose with a low degree of polymerization is prepared by using glucose molecules catalyzed by cellulosylphosphatase. After drying, the enzymatic cellulose with a degree of polymerization of 20 is obtained.
[0030] Preparation of two-dimensional montmorillonite aqueous solution: The two-dimensional montmorillonite solution was prepared by the following method: solid montmorillonite was dispersed in a solvent, and after stirring or ultrasonic crushing, the supernatant was collected by centrifugation to obtain the two-dimensional montmorillonite solution. Specifically, 1 g of solid montmorillonite was dispersed in 1 L of deionized water, and after ultrasonic crushing, the supernatant was collected by centrifugation to obtain the two-dimensional montmorillonite solution. Then, 0.5 L of N-methylpyrrolidone was added, and after ultrasonic mixing, the two-dimensional montmorillonite aqueous solution was obtained.
[0031] Preparation of silver complex: The silver complex is formed by complexing nano-silver nitrate with an inorganic complex. The specific steps are as follows: Dissolve silver nitrate in deionized water, then add sodium sulfite, controlling the molar ratio of sodium sulfite to silver nitrate to be 1.2:1, and react at 10℃ for 2 hours to obtain the silver complex.
[0032] Example 1
[0033] A method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane includes the following steps:
[0034] S1, Preparation of silver ion antibacterial agent: 1.5 L of the prepared two-dimensional montmorillonite aqueous solution was mixed with 1.5 g of silver complex;
[0035] S2, Cellulose-modified PVDF filter membrane: 50g of enzymatically synthesized cellulose with a degree of polymerization of 20 was dissolved in 1L of trifluoroacetic acid at 80℃ to obtain an enzymatically synthesized cellulose solution; the enzymatically synthesized cellulose was dissolved in trifluoroacetic acid at 80℃ to obtain a 50g / L enzymatically synthesized cellulose solution; the PVDF filter membrane was immersed in the enzymatically synthesized cellulose solution for 30s, and then vacuum dried at 80℃ until the humidity in the drying oven reached 20% to obtain a cellulose-modified PVDF filter membrane; the vacuum-dried cellulose-modified PVDF filter membrane was immersed in anhydrous ethanol for 4h, and finally vacuum dried at 80℃ until the humidity in the drying oven reached 20% to obtain a cellulose-modified PVDF filter membrane.
[0036] S3, Preparation of silver ion antibacterial PVDF hydrophilic filter membrane: The silver ion antibacterial agent obtained in S1 is loaded onto the cellulose-modified PVDF filter membrane obtained in step S2 by vacuum filtration. 0.15 L of the silver ion antibacterial agent is poured into a 0.1 m... 2 The cellulose-modified PVDF filter membrane was filtered and then dried in an oven at 80°C to obtain an antibacterial cellulose-modified PVDF filter membrane.
[0037] Example 2
[0038] A method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane includes the following steps:
[0039] S1, Preparation of silver ion antibacterial agent: 1.5 L of the prepared two-dimensional montmorillonite aqueous solution was mixed with 1.5 g of silver complex;
[0040] S2, Cellulose-modified PVDF filter membrane: 50g of enzymatically synthesized cellulose with a degree of polymerization of 20 was dissolved in 1L of trifluoroacetic acid at 80℃ to obtain an enzymatically synthesized cellulose solution; the enzymatically synthesized cellulose was dissolved in trifluoroacetic acid at 100℃ to obtain a 90g / L enzymatically synthesized cellulose solution; the PVDF filter membrane was immersed in the enzymatically synthesized cellulose solution for 60s, and then vacuum dried at 100℃ until the humidity in the drying oven was 2% to obtain a cellulose-modified PVDF filter membrane; the vacuum-dried cellulose-modified PVDF filter membrane was immersed in anhydrous ethanol for 8h, and finally vacuum dried at 100℃ until the humidity in the drying oven was 2% to obtain a cellulose-modified PVDF filter membrane.
[0041] S3, Preparation of silver ion antibacterial PVDF hydrophilic filter membrane: The silver ion antibacterial agent prepared in S1 is loaded onto the cellulose-modified PVDF filter membrane obtained in step S2 by vacuum filtration. 0.15L of silver ion antibacterial agent is poured onto 0.1m2 of cellulose-modified PVDF filter membrane. After vacuum filtration, it is dried in an oven at 80℃ to obtain the antibacterial cellulose-modified PVDF filter membrane.
[0042] Example 3
[0043] A method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane includes the following steps:
[0044] S1, Preparation of silver ion antibacterial agent: 1.5 L of the prepared two-dimensional montmorillonite aqueous solution was mixed with 1.5 g of silver complex;
[0045] S2, Cellulose-modified PVDF filter membrane: 50g of enzymatically synthesized cellulose with a degree of polymerization of 20 was dissolved in 1L of trifluoroacetic acid at 80℃ to obtain an enzymatically synthesized cellulose solution; the enzymatically synthesized cellulose was dissolved in trifluoroacetic acid at 95℃ to obtain a 70g / L enzymatically synthesized cellulose solution; the PVDF filter membrane was immersed in the enzymatically synthesized cellulose solution for 40s, and then vacuum dried at 90℃ until the humidity in the drying oven reached 12% to obtain a cellulose-modified PVDF filter membrane; the vacuum-dried cellulose-modified PVDF filter membrane was immersed in anhydrous ethanol for 6h, and finally vacuum dried at 90℃ until the humidity in the drying oven reached 12% to obtain a cellulose-modified PVDF filter membrane.
[0046] S3, Preparation of silver ion antibacterial PVDF hydrophilic filter membrane: The silver ion antibacterial agent prepared in S1 is loaded onto the cellulose-modified PVDF filter membrane obtained in step S2 by vacuum filtration. 0.15L of silver ion antibacterial agent is poured onto 0.1m2 of cellulose-modified PVDF filter membrane. After vacuum filtration, it is dried in an oven at 80℃ to obtain the antibacterial cellulose-modified PVDF filter membrane.
[0047] Example 4
[0048] The difference from Example 3 is that the silver ion antibacterial agent is applied to the cellulose-modified PVDF filter membrane by spraying, per 1m 2 Spray 0.15L of silver ion antibacterial agent.
[0049] Example 5
[0050] The difference from the previous example is that the silver ion antibacterial agent is applied to the cellulose-modified PVDF filter membrane by spraying, with 0.15L of silver ion antibacterial agent sprayed per 1m2. A silane coupling agent, KH-550, is added to the silver ion antibacterial agent, and the mass ratio of the silane coupling agent to the silver ion antibacterial agent is 0.1:1.
[0051] Comparative Example
[0052] Comparative Example 1
[0053] The difference from Example 3 is that the cellulose-modified PVDF filter membrane does not load silver ion antibacterial agent.
[0054] Comparative Example 2
[0055] The difference from Example 3 is that the PVDF filter membrane is not modified with cellulose, but is directly filtered by pouring silver ion antibacterial agent on it.
[0056] Comparative Example 3
[0057] The difference from Example 3 is that step S2 does not involve soaking in anhydrous ethanol.
[0058] Comparative Example 4
[0059] The difference from Example 3 is that a silver ion antioxidant was prepared by loading silver ions onto graphene. The preparation method of the graphene-loaded silver ion antibacterial agent is as follows:
[0060] S1, Preparation of graphene aqueous solution: 1g of graphene is dispersed in 1L of deionized water, and after ultrasonic crushing, the supernatant is separated by centrifugation to obtain graphene solution. Then, 0.5L of N-methylpyrrolidone is added, and after ultrasonic mixing, graphene aqueous solution is obtained.
[0061] S2, 1.5L of graphene aqueous solution and 1.5g of silver complex are mixed.
[0062] experiment
[0063] The silver ion antibacterial PVDF hydrophilic filter membranes prepared in the examples and comparative examples were subjected to pure water flux testing (GB / T32360-2015) and antibacterial tests against Escherichia coli and Staphylococcus aureus (GB / T20944.3-2008). After 7 days of pure water flux testing, the antibacterial tests against E. coli and Staphylococcus aureus were conducted again (GB / T20944.3-2008). The test results are shown in Table 1.
[0064] Table 1
[0065]
[0066]
[0067] analyze
[0068] A comparison of Examples 3 and 4 shows that the filter membrane prepared by spraying has a better antibacterial effect because vacuum filtration easily removes some of the silver ion antibacterial agent, thus reducing the antibacterial effect. However, the water flow rate is reduced to some extent because after spraying, the antibacterial agent easily covers the pores, resulting in a decrease in water flow rate.
[0069] A comparison of Examples 4 and 5 shows that by adding a silane coupling agent, the adhesion effect of silver ions on the filter membrane is improved, thereby maintaining the antibacterial durability.
[0070] As can be seen from Example 3 and Comparative Example 1, the filter membrane prepared in this application has good water flow rate and good antibacterial properties.
[0071] As shown in Example 3 and Comparative Example 2, cellulose modification improves the hydrophilicity of the filter membrane and increases the water flow rate. Furthermore, the formation of intermolecular hydrogen bonds between cellulose and two-dimensional montmorillonite facilitates the loading of antibacterial agents and enhances antibacterial durability.
[0072] As shown in Example 3 and Comparative Example 3, anhydrous ethanol participates in the crystallization of cellulose, increases porosity and water flow, and also increases the loading strength of silver ion antibacterial agents, thereby improving antibacterial durability.
[0073] As shown in Example 3 and Comparative Example 4, when graphene is used to replace montmorillonite in equal amounts to prepare silver ion antibacterial agents, the antibacterial effect becomes worse, and the antibacterial durability also becomes worse.
[0074] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane, characterized in that: Includes the following steps: S1, Preparation of silver ion antibacterial agent: It is obtained by reacting two-dimensional montmorillonite solution with silver complex, and the silver complex is formed by complexing nano-silver nitrate with inorganic complex; S2, Cellulose-modified PVDF filter membrane: Enzymatically processed cellulose is dissolved in trifluoroacetic acid by heating to obtain an enzymatically processed cellulose solution; the PVDF filter membrane is immersed in the enzymatically processed cellulose solution, then removed and vacuum dried, and then treated with anhydrous ethanol to obtain a cellulose-modified PVDF filter membrane. S3, Preparation of silver ion antibacterial PVDF hydrophilic filter membrane: The silver ion antibacterial agent prepared in S1 is loaded onto the cellulose-modified PVDF filter membrane by suction filtration or spraying.
2. The method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane according to claim 1, characterized in that: Enzymatically processed cellulose is dissolved in trifluoroacetic acid at 80-100℃ to obtain a 50-90 g / L enzymatically processed cellulose solution; a PVDF filter membrane is immersed in the enzymatically processed cellulose solution for 30-60 seconds, and then vacuum dried at 80-100℃ until the humidity in the drying oven is 0-20% to obtain a cellulose-modified PVDF filter membrane.
3. The method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane according to claim 1, characterized in that: In step S2, the vacuum-dried cellulose-modified PVDF filter membrane is soaked in anhydrous ethanol for 4-8 hours.
4. The method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane according to claim 1, characterized in that: The two-dimensional montmorillonite solution is prepared by the following method: solid montmorillonite is dispersed in a solvent, and the supernatant is obtained by centrifugation after stirring or ultrasonic crushing.
5. The method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane according to claim 4, characterized in that: The solvent is water or alcohol.
6. The method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane according to claim 1, characterized in that: When silver ion antibacterial agent is loaded onto PVDF filter membrane by spraying, silane coupling agent is added to the silver ion antibacterial agent.
7. The method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane according to claim 6, characterized in that: The silane coupling agent is KH-550.
8. A silver ion antibacterial PVDF hydrophilic filter membrane, characterized in that: It is prepared by the method for preparing a silver ion antibacterial PVDF hydrophilic filter membrane according to any one of claims 1-7.