Preparation method of silver nanowire-loaded ultrafiltration membrane
By loading silver nanowires on the surface of the ultrafiltration membrane and using ultraviolet light to form chemical bond connections, the problem of ultrafiltration membrane pollution and insufficient binding force of nanomaterials is solved, and the anti-pollution performance and durability of the membrane are significantly improved.
Patent Information
- Application Number
- CN202510239369.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2025-04-29
AI Technical Summary
Ultrafiltration membranes are easily contaminated during long-term operation, resulting in a decrease in flux, an increase in cleaning frequency and a shortened service life. In addition, traditional nanoparticle modification methods have problems such as insufficient binding force and loss of nanomaterials.
The ultrafiltration membrane preparation method is adopted to load silver nanowires, and the bonding force between the nanomaterial and membrane is enhanced by loading silver nanowires on the surface of the ultrafiltration membrane and forming a stable chemical bond connection using ultraviolet irradiation.
Effectively inhibit microbial adhesion and growth, reduce the frequency of membrane pollution, improve the anti-pollution performance and durability of membranes, and reduce the risk of secondary pollution in water bodies.
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Figure CN119896974A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of water treatment, and in particular to a method for preparing a silver nanowire-loaded ultrafiltration membrane. Background Art
[0002] Ultrafiltration membranes have become an important material in the field of water treatment due to their high separation capacity and wide applicability. However, membrane fouling is the main challenge faced by ultrafiltration membranes in long-term operation. Pollution includes adsorption and blockage of organic matter, microorganisms and inorganic substances on the membrane surface, which will lead to decreased membrane flux, increased cleaning frequency and shortened service life, thus significantly increasing operating costs and energy consumption. Therefore, how to effectively inhibit membrane fouling and improve the membrane's anti-fouling performance has become an urgent problem to be solved.
[0003] In recent years, nanomaterials have attracted wide attention for their unique physical and chemical properties in membrane separation technology. Common nanomaterials include nanosilver, carbon nanotubes, titanium dioxide, etc. These materials are usually combined with membrane materials through surface coating, surface grafting, blending and other methods. However, in traditional nanoparticle modification methods, due to the weak binding force between nanoparticles and membrane substrates, they are easily detached due to external forces such as hydraulic impact during water treatment, which not only leads to a decrease in membrane performance, but also may cause environmental problems such as the loss of nanomaterials and secondary pollution of water bodies. Summary of the invention
[0004] In view of the shortcomings of the prior art, the present invention provides a method for preparing a silver nanowire-loaded ultrafiltration membrane to solve the problems raised in the above background technology.
[0005] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a method for preparing a silver nanowire-loaded ultrafiltration membrane, comprising the following steps: S1, preparation of silver nanowire Ag NWs precursor solution; S2, purifying and dispersing the prepared silver nanowire Ag NWs precursor solution to obtain a silver nanowire Ag NWs dispersion; S3, using the silver nanowire Ag NWs dispersion as the basis for subsequent loading materials to pre-treat the polyvinylidene fluoride PVDF ultrafiltration membrane; S4, the pre-treated polyvinylidene fluoride PVDF ultrafiltration membrane is subjected to ultraviolet irradiation treatment; S5, loading silver nanowires Ag NWs based on polyvinylidene fluoride PVDF ultrafiltration membrane; S6, after the loading is completed, the membrane is cleaned and post-processed to obtain a silver nanowire loaded ultrafiltration membrane; S7. Perform performance test on the silver nanowire loaded ultrafiltration membrane to complete the preparation.
[0006] Further optimizing the technical solution, in step S1, preparing the silver nanowire precursor solution comprises: Prepare solution A; Prepare solution B; The solution A and the solution B are mixed and stirred to obtain a silver nanowire Ag NWs precursor solution.
[0007] To further optimize the technical solution, the preparation process of solution A includes: Weigh 1.50 g of polyvinyl pyrrolidone (PVP) and dissolve it in 30 mL of ethylene glycol. After PVP is completely dissolved, add 1.53 g of silver nitrate (AgNO3) and heat with magnetic stirring to completely dissolve it to obtain a solution system with uniform distribution of silver ions, thus preparing a uniform and transparent solution A. The preparation process of the solution B comprises: Dissolve 0.48 g of copper chloride dihydrate CuCl2·2H2O in 20 mL of ethylene glycol to obtain solution B; The solution A and the solution B are mixed and stirred, including: 2 mL of solution B was added dropwise into solution A, stirred evenly, and then transferred into a reactor to react at 175 °C for 5 h to obtain a silver nanowire Ag NWs precursor solution.
[0008] Further optimizing the technical solution, in step S2, purification is performed, including: After cooling, the Ag NWs precursor solution was transferred to a 100 mL beaker, and 20 mL of deionized water and 80 mL of acetone were added. The solution was stirred and allowed to stand for 1 h to allow the Ag NWs to settle to the bottom of the beaker. The upper layer of impurity-containing solution was sucked off, and the silver nanowires Ag NWs precipitation at the bottom was retained, and the above steps were repeated 3 times to remove impurities and unreacted precursors; Dispersion, including: Ethanol was added to the purified silver nanowires Ag NWs, and the mixture was centrifuged at 4000 r / min for 5 min. The centrifugation was repeated 2-3 times, and the obtained silver nanowires Ag NWs were dispersed in 30 mL of ethanol for later use to obtain a silver nanowire Ag NWs dispersion.
[0009] To further optimize the technical solution, the silver nanowire Ag NWs dispersion is characterized to verify whether its morphology, size and purity meet the requirements, and the characterization results are used to evaluate the preparation quality of the silver nanowires Ag NWs.
[0010] To further optimize the technical solution, in step S3, the pre-processing includes: The polyvinylidene fluoride (PVDF) ultrafiltration membrane was immersed in benzophenone BP / methanol solutions with mass fractions of 0.1%, 0.5%, 1.0%, 1.5%, and 2.0%, respectively; The membrane was left to stand for 90 min to allow benzophenone BP to be evenly adsorbed on the membrane surface; Dry the membrane surface in a ventilated environment to prepare for subsequent UV irradiation treatment.
[0011] To further optimize the technical solution, in step S4, ultraviolet irradiation treatment is performed, including: The polyvinylidene fluoride (PVDF) ultrafiltration membrane is placed under an ultraviolet light source. The ultraviolet light excites the benzophenone (BP) molecules to produce free radicals, which react with the membrane surface to form stable active groups, ensuring uniform activation of the membrane surface.
[0012] To further optimize the technical solution, in step S5, 20 mL of silver nanowire Ag NWs dispersion with concentrations of 0.05%, 0.1%, 0.3%, 0.6%, and 1.0% are respectively added to the watch glass to cover the membrane surface and keep it evenly distributed. After sealing the watch glass, the ultraviolet lamp is turned on again for irradiation, and the irradiation time is 15, 30, 45, 50, and 75 min, respectively, to firmly attach the silver nanowires Ag NWs to the membrane surface by ultraviolet induced reaction.
[0013] Further optimizing the technical solution, in step S6, the cleaning and post-treatment of the membrane includes: The polyvinylidene fluoride (PVDF) ultrafiltration membrane loaded with silver nanowires is rinsed with a methanol aqueous solution to remove the unbound silver nanowires Ag NWs and residual chemical reagents on the surface; The washed membrane was immersed in clean water for 1 h to balance the surface chemical properties and then dried naturally to constant weight.
[0014] To further optimize the technical solution, in step S7, the performance test includes water permeability, antibacterial performance and mechanical stability test.
[0015] Compared with the prior art, the present invention provides a method for preparing a silver nanowire-loaded ultrafiltration membrane, which has the following beneficial effects: The preparation method of the ultrafiltration membrane loaded with silver nanowires effectively inhibits the attachment and growth of microorganisms on the membrane surface by loading silver nanowires on the ultrafiltration membrane surface, thereby significantly reducing the frequency of membrane pollution. The silver nanowires are connected to the ultrafiltration membrane substrate by a stable chemical bond by ultraviolet irradiation, which significantly enhances the binding force between the nanomaterial and the membrane. Compared with traditional surface coating or blending methods, the problem of silver nanowires falling off under external forces such as hydraulic impact is avoided, thereby improving the durability of the membrane and reducing the risk of secondary pollution of the water body. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0017] Figure 1 A schematic diagram of a process for preparing a silver nanowire-loaded ultrafiltration membrane proposed in the present invention; Figure 2 This is a flow chart of the preparation of silver nanowires in a method for preparing a silver nanowire-loaded ultrafiltration membrane proposed by the present invention; Figure 3 This is a diagram of the PVP nucleation reaction mechanism in the polyol method of the preparation method of the silver nanowire-loaded ultrafiltration membrane proposed by the present invention; Figure 4 This is a SEM image of Ag NWs prepared by a polyol method in a method for preparing a silver nanowire-loaded ultrafiltration membrane proposed in the present invention. DETAILED DESCRIPTION
[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.
[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0020] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments. Embodiment 1:
[0021] Reference Figure 1 to Figure 3 , which is the first embodiment of the present invention, provides a method for preparing a silver nanowire-loaded ultrafiltration membrane, comprising the following steps: S1. Preparation of silver nanowire Ag NWs precursor solution.
[0022] In this embodiment, the silver nanowire precursor solution is prepared, including: Preparation of solution A: Weigh 1.50 g of polyvinyl pyrrolidone (PVP) and dissolve it in 30 mL of ethylene glycol. After the PVP is completely dissolved, add 1.53 g of silver nitrate (AgNO3) and heat with magnetic stirring to completely dissolve it to obtain a solution system with uniform distribution of silver ions, thus preparing a uniform and transparent solution A.
[0023] Prepare solution B: Dissolve 0.48 g of cupric chloride dihydrate (CuCl2·2H2O) in 20 mL of ethylene glycol to obtain solution B.
[0024] 2 mL of solution B was added dropwise into solution A, stirred evenly, and then transferred into a reactor to react at 175 °C for 5 h to obtain a silver nanowire Ag NWs precursor solution.
[0025] This step ensures the production of high-quality silver nanowires by controlling solution composition and temperature conditions.
[0026] Existing silver nanowires are mainly prepared by the polyol method. The typical growth mechanism of Ag NWs synthesized by the polyol method can be summarized as follows: (1) AgNO3 is reduced to silver atoms by ethylene glycol. Once the concentration of silver atoms reaches the supersaturation value, nucleation begins and silver nanoparticles are generated; (2) Silver nanoparticles form silver seeds through uniform nucleation, among which twin particles become the most abundant morphology due to their relatively low surface energy; (3) Using PVP as a capping agent, silver nanorods continue to grow into nanowires.
[0027] S2. Purify and disperse the prepared silver nanowire Ag NWs precursor solution to obtain a silver nanowire Ag NWs dispersion.
[0028] In this embodiment, purification is performed, including: After cooling, the Ag NWs precursor solution was transferred to a 100 mL beaker, and 20 mL of deionized water and 80 mL of acetone were added. The solution was stirred and allowed to stand for 1 h to allow the Ag NWs to settle to the bottom of the beaker. The upper layer of impurity-containing solution was sucked off, and the silver nanowires Ag NWs precipitation at the bottom was retained, and the above steps were repeated 3 times to remove impurities and unreacted precursors; Dispersion, including: Ethanol was added to the purified silver nanowires Ag NWs, and the mixture was centrifuged at 4000 r / min for 5 min. The centrifugation was repeated 2-3 times, and the obtained silver nanowires Ag NWs were dispersed in 30 mL of ethanol for later use to obtain a silver nanowire Ag NWs dispersion.
[0029] The centrifugation and multiple washing steps in this step ensure the high purity of the silver nanowires while preserving their linear structure.
[0030] S3. Pre-treat the polyvinylidene fluoride (PVDF) ultrafiltration membrane using the silver nanowire (Ag NWs) dispersion as the basis for subsequent loading.
[0031] In this embodiment, the pre-processing includes: The polyvinylidene fluoride (PVDF) ultrafiltration membrane was immersed in benzophenone BP / methanol solutions with mass fractions of 0.1%, 0.5%, 1.0%, 1.5%, and 2.0%, respectively; The membrane was left to stand for 90 min to allow benzophenone BP to be evenly adsorbed on the membrane surface; Dry the membrane surface in a ventilated environment to prepare for subsequent UV irradiation treatment.
[0032] This step provides active sites for subsequent surface modification through the selective adsorption of BP.
[0033] S4. The pre-treated polyvinylidene fluoride PVDF ultrafiltration membrane is subjected to ultraviolet irradiation treatment.
[0034] In this embodiment, the ultraviolet irradiation treatment is performed, including: The polyvinylidene fluoride (PVDF) ultrafiltration membrane is placed under an ultraviolet light source. The ultraviolet light excites the benzophenone (BP) molecules to produce free radicals, which react with the membrane surface to form stable active groups, ensuring uniform activation of the membrane surface.
[0035] This step ensures uniform activation of the membrane surface and improves the adhesion of subsequent silver nanowires by controlling the UV light intensity and irradiation time (e.g., 20-30 min).
[0036] S5. Silver nanowires (Ag NWs) are loaded based on polyvinylidene fluoride (PVDF) ultrafiltration membrane.
[0037] In this embodiment, 20 mL of silver nanowire Ag NWs dispersion with concentrations of 0.05%, 0.1%, 0.3%, 0.6%, and 1.0% were added to the watch glass, respectively, to cover the membrane surface and keep it evenly distributed. After sealing the watch glass, the ultraviolet lamp was turned on again for irradiation. The irradiation time was 15, 30, 45, 50, and 75 min, respectively, and the silver nanowires Ag NWs were firmly attached to the membrane surface by ultraviolet induced reaction.
[0038] In this step, precise control of the intensity and time of ultraviolet irradiation is key, which not only ensures the stable loading of silver nanowires but also avoids the destruction of their morphology.
[0039] S6. After the loading is completed, the membrane is cleaned and post-treated to obtain a silver nanowire-loaded ultrafiltration membrane.
[0040] In this embodiment, the cleaning and post-treatment of the membrane includes: The polyvinylidene fluoride (PVDF) ultrafiltration membrane loaded with silver nanowires is rinsed with a methanol aqueous solution to remove the unbound silver nanowires Ag NWs and residual chemical reagents on the surface; The washed membrane was immersed in clean water for 1 h to balance the surface chemical properties and then dried naturally to constant weight.
[0041] This step ensures the purification and stability of the membrane.
[0042] S7. Perform performance test on the silver nanowire loaded ultrafiltration membrane to complete the preparation.
[0043] In this embodiment, the performance tests include water permeability, antibacterial performance and mechanical stability tests.
[0044] By adjusting the loading amount and distribution density of silver nanowires, the use effect of the ultrafiltration membrane can be optimized to meet the needs in different environments. Embodiment 2:
[0045] Reference Figure 4 , which is the second embodiment of the present invention, this embodiment characterizes the silver nanowire Ag NWs dispersion to verify whether its morphology, size and purity meet the requirements, and the characterization results are used to evaluate the preparation quality of the silver nanowire Ag NWs.
[0046] The morphology of Ag NWs was characterized by cold field emission scanning electron microscopy (SEM, HITACHI S-4800). First, the dispersed Ag NWs were dropped on a single crystal silicon wafer, placed in a vacuum drying oven for 1 h, and then adhered to the sample stage with conductive tape and placed inside the instrument for vacuum gold spraying for testing.
[0047] Scanning electron microscope characterization and analysis of Ag NWs. The polyol method for synthesizing Ag NWs is simple and has high repeatability. In principle, the method reduces silver ions into atoms or atomic clusters, which continuously aggregate and grow along a specific direction to synthesize Ag NWs. SEM image of Ag NWs prepared by the polyol method. From the SEM image, it can be seen that AgNWs presents uniform dispersion, linear uniformity, and cross-linked network morphology. The length of Ag NWs is several microns and the diameter is about ten nanometers. Embodiment three:
[0048] In Example 1 and Example 2, the reagents / consumables used for the preparation and characterization of the silver nanowire-loaded ultrafiltration membrane are shown in Table 1-1.
[0049] Table 1-1
[0050] The instruments required for the preparation and characterization of silver nanowires are shown in Table 1-2.
[0051] Table 1-2
[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.
Claims
1. A method for preparing a silver nanowire-loaded ultrafiltration membrane, characterized in that: The following steps are involved: S1, preparation of silver nanowire Ag NWs precursor solution; S2, purifying and dispersing the prepared silver nanowire Ag NWs precursor solution to obtain a silver nanowire Ag NWs dispersion; S3, using the silver nanowire Ag NWs dispersion as the basis for subsequent loading materials to pre-treat the polyvinylidene fluoride PVDF ultrafiltration membrane; S4, the pre-treated polyvinylidene fluoride PVDF ultrafiltration membrane is subjected to ultraviolet irradiation treatment; S5, loading silver nanowires Ag NWs based on polyvinylidene fluoride PVDF ultrafiltration membrane; S6, after the loading is completed, the membrane is cleaned and post-processed to obtain a silver nanowire loaded ultrafiltration membrane; S7. Perform performance test on the silver nanowire loaded ultrafiltration membrane to complete the preparation.
2. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 1, characterized in that: In the step S1, preparing a silver nanowire precursor solution comprises: Prepare solution A; Prepare solution B; The solution A and the solution B are mixed and stirred to obtain a silver nanowire Ag NWs precursor solution.
3. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 2, characterized in that: The preparation process of the solution A comprises: Weigh 1.50 g of polyvinyl pyrrolidone (PVP) and dissolve it in 30 mL of ethylene glycol. After PVP is completely dissolved, add 1.53 g of silver nitrate (AgNO3) and heat with magnetic stirring to completely dissolve it to obtain a solution system with uniform distribution of silver ions, thus preparing a uniform and transparent solution A. The preparation process of the solution B comprises: Dissolve 0.48 g of copper chloride dihydrate CuCl2·2H2O in 20 mL of ethylene glycol to obtain solution B; The solution A and the solution B are mixed and stirred, including: 2 mL of solution B was added dropwise into solution A, stirred evenly, and then transferred into a reactor to react at 175 °C for 5 h to obtain a silver nanowire Ag NWs precursor solution.
4. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 1, characterized in that: In the step S2, purification is performed, including: After cooling, the Ag NWs precursor solution was transferred to a 100 mL beaker, and 20 mL of deionized water and 80 mL of acetone were added. The solution was stirred and allowed to stand for 1 h to allow the Ag NWs to settle to the bottom of the beaker. The upper layer of impurity-containing solution was sucked off, and the silver nanowires Ag NWs precipitation at the bottom was retained, and the above steps were repeated 3 times to remove impurities and unreacted precursors; Dispersion, including: Ethanol was added to the purified silver nanowires Ag NWs, and the mixture was centrifuged at 4000 r / min for 5 min. The centrifugation was repeated 2-3 times, and the obtained silver nanowires Ag NWs were dispersed in 30 mL of ethanol for later use to obtain a silver nanowire Ag NWs dispersion.
5. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 4, characterized in that: The silver nanowire Ag NWs dispersion is characterized to verify whether its morphology, size and purity meet the requirements, and the characterization results are used to evaluate the preparation quality of the silver nanowires Ag NWs.
6. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 1, characterized in that: In step S3, the pre-processing includes: The polyvinylidene fluoride (PVDF) ultrafiltration membrane was immersed in benzophenone BP / methanol solutions with mass fractions of 0.1%, 0.5%, 1.0%, 1.5%, and 2.0%, respectively; The membrane was left to stand for 90 min to allow benzophenone BP to be evenly adsorbed on the membrane surface; Dry the membrane surface in a ventilated environment to prepare for subsequent UV irradiation treatment.
7. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 1, characterized in that: In the step S4, ultraviolet irradiation treatment is performed, including: The polyvinylidene fluoride (PVDF) ultrafiltration membrane is placed under an ultraviolet light source. The ultraviolet light excites the benzophenone (BP) molecules to produce free radicals, which react with the membrane surface to form stable active groups, ensuring uniform activation of the membrane surface.
8. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 1, characterized in that: In the step S5, 20 mL of silver nanowire AgNWs dispersion with concentrations of 0.05%, 0.1%, 0.3%, 0.6%, and 1.0% are respectively added to the watch glass to cover the surface of the film and keep it evenly distributed. After sealing the watch glass, the ultraviolet lamp is turned on again for irradiation. The irradiation time is 15, 30, 45, 50, and 75 min, respectively, and the silver nanowires Ag NWs are firmly attached to the film surface by ultraviolet induced reaction.
9. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 1, characterized in that: In step S6, the cleaning and post-treatment of the membrane includes: The polyvinylidene fluoride (PVDF) ultrafiltration membrane loaded with silver nanowires is rinsed with a methanol aqueous solution to remove the unbound silver nanowires Ag NWs and residual chemical reagents on the surface; The washed membrane was immersed in clean water for 1 h to balance the surface chemical properties and then dried naturally to constant weight.
10. The method for preparing a silver nanowire-loaded ultrafiltration membrane according to claim 1, characterized in that: In step S7, the performance test includes water permeability, antibacterial performance and mechanical stability test.