Multilayer antibacterial super-hydrophobic membrane as well as preparation method and application thereof

Abstract

The invention relates to a multilayer antibacterial super-hydrophobic membrane as well as a preparation method and application thereof, and belongs to the technical field of membrane materials. The multi-layer antibacterial super-hydrophobic membrane integrating supporting, filtering, antibacterial and super-hydrophobic properties is prepared by alkalifying the fiber braided tube and attaching the flat membrane, then using the strong oxidant to enhance the stability, adding the antibacterial nanoparticles to form the antibacterial layer, then coating the fluorosilane to establish a super-hydrophobic effect, and finally performing high-temperature curing, so that the multi-layer antibacterial super-hydrophobic membrane integrating the supporting, filtering, antibacterial and super-hydrophobic properties is prepared. The multilayer antibacterial super-hydrophobic membrane solves the problems that a traditional membrane material is low in flux and easy to cause membrane pollution and membrane infiltration in a membrane distillation technology, and can be applied to a process for preparing pure water from desulfurization wastewater and other industrial wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of membrane materials, in particular to a multi-layer antibacterial super-hydrophobic membrane and a preparation method and application thereof. Background Art

[0002] With the rapid growth of the global population and the continuous development of industry, the shortage of fresh water resources has become a global problem that needs to be solved urgently. Using seawater desalination to solve the shortage of fresh water is currently a more effective way. Among many technologies, membrane distillation technology uses the vapor pressure difference on both sides of the membrane as a driving force to allow water vapor to pass through the membrane material for desalination. It can also use high-concentration, highly polluted salt water and low-grade thermal energy such as industrial waste heat to improve the resource utilization rate of sewage and wastewater. However, traditional hydrophobic membranes have low flux and face serious problems such as membrane pollution and membrane infiltration, which seriously restricts the further development of membrane distillation technology.

[0003] For example, the Chinese patent with authorization announcement number CN111359442B and invention name "A PTFE composite membrane for MABR and its preparation method", the composite membrane includes a hydrophobic hollow fiber porous support tube membrane and a hydrophilic polytetrafluoroethylene porous flat membrane wrapping layer arranged on the surface of the hydrophobic hollow fiber porous support tube membrane. Although the prior art has disclosed the use of fiber braided tube and flat membrane structure, the composite membrane is an affinity membrane rather than a hydrophobic membrane. After being immersed in seawater for a long time, membrane pollution will occur, resulting in the problem of membrane material infiltration failure.

[0004] Existing commercial membrane modules generally use the method of regular cleaning of membrane materials to alleviate membrane fouling problems. The membrane fouling problem cannot be completely solved, which significantly reduces the life cycle of membrane materials. It is necessary to improve the antifouling performance of membrane materials from the perspective of the material itself. However, the composition of pollutants in complex seawater environments is complex, and the effectiveness of traditional antifouling modifications is short. It is necessary to explore and develop new antifouling technologies for the membrane material itself. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a multi-layer antibacterial super-hydrophobic film and a preparation method and application thereof, which has antibacterial properties and a super-hydrophobic surface, and improves the service life in practical applications.

[0006] The technical solution of the present invention is as follows:

[0007] The invention discloses a multi-layer antibacterial super-hydrophobic membrane, comprising a fiber braided tube that plays a supporting role, a flat membrane solidified at high temperature on the upper surface of the fiber braided tube, antibacterial particles attached to the upper surface of the flat membrane to form an antibacterial layer, and the antibacterial layer is coated with a low surface energy modifier to form a super-hydrophobic layer located on the top layer.

[0008] Furthermore, the thickness of the multi-layer antibacterial superhydrophobic membrane is 0.2-0.3 mm, wherein the thickness of the braided fiber tube is 0.1-0.2 mm, and the thickness of the flat membrane is 0.05-0.1 mm.

[0009] Another object of the present invention is to disclose a method for preparing a multi-layer antibacterial super-hydrophobic film, comprising the following steps:

[0010] S1: alkalinizing the fiber weave with an alkaline solution, then rinsing with deionized water and drying;

[0011] S2: Wrap the flat plate on the outer wall of the fiber braided tube treated in step S1, ensuring that its coverage rate is 30% to 50% of the outer wall area of ​​the fiber braided tube, and then sinter the fiber braided tube wrapped with the flat plate membrane at a high temperature to make the flat plate membrane adhere to the outer wall of the fiber braided tube.

[0012] S3: soaking the membrane material obtained after high-temperature sintering in step S2 in a strong oxidant solution for 1-2 hours, then taking it out and rinsing it with deionized water;

[0013] S4: the membrane material after the soaking treatment in step S3 is soaked again in an antibacterial nanoparticle solution at a temperature of 30-45° C., and then dried to form an antibacterial layer on the surface of the flat membrane;

[0014] S5: soaking the membrane material forming the antibacterial layer after the treatment in step S4 in a fluorosilane coupling agent solution at a temperature of 30-45° C. for 0.5-1 h to form a super hydrophobic layer on the antibacterial surface;

[0015] S6: placing the film material formed into the super hydrophobic layer after the treatment in step S5 in an oven at 120-150° C. for curing for 0.5-1 h and then cooling to obtain a multi-layer super hydrophobic antibacterial film.

[0016] Furthermore, in step S1, the fiber braided tube is a glass fiber braided tube, a polylactic acid fiber braided tube or a polyester fiber braided tube.

[0017] Furthermore, in step S1, the alkaline solution is a sodium hydroxide or potassium hydroxide solution, the concentration of the alkaline solution is 3-5wt%, the alkalization time is 2-4h, the drying temperature is 90-130°C, and the drying time is 10-40min.

[0018] Furthermore, in step S2, the material of the flat membrane is polyvinylidene fluoride or polytetrafluoroethylene, the pore size is 0.1-0.5 μm, the high temperature sintering temperature is 300-330° C., and the time is 2-5 min.

[0019] Furthermore, in step S3, the strong oxidant used is potassium permanganate or sodium permanganate with a concentration of 3-5wt%.

[0020] Furthermore, the antibacterial nanoparticles in step S4 are silica-coated silver nanoparticles with a concentration of 0.2-0.6 wt %.

[0021] Furthermore, in step S5, the fluorosilane coupling agent is perfluorooctyltrichlorosilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane or triethoxysilane, and the concentration of the fluorosilane coupling agent is 1-3 vol%.

[0022] The invention discloses application of a multi-layer antibacterial super-hydrophobic membrane in seawater desalination treatment or membrane distillation.

[0023] The present invention has the following beneficial effects:

[0024] 1. The present invention tightly wraps the soft and poorly supported flat membrane on the outer surface of the fiber braided tube with good structural strength. This design makes up for the limitation of the insufficient rigidity of the flat membrane material itself. In this way, not only the technical difficulties of flat membrane assembly packaging are overcome, but also the creep resistance and overall mechanical strength of the membrane material are significantly improved. The present invention is specially optimized for the extreme challenges faced by the seawater direct hydrogen production system and the salt lake water hydrogen production system. Under the actual marine environment operating conditions, the system is frequently subjected to the impact of seawater fluctuations, the creep deformation of the membrane material due to long-term stress, and the pollution problems caused by microbial attachment. These factors will seriously restrict the performance and service life of traditional membrane materials. The present invention effectively resists these adverse effects through the above-mentioned improvement measures, ensures efficient and stable operation in high-salinity and high-corrosive environments, and provides a high-performance membrane material solution for the field of hydrogen production from seawater and salt lake water.

[0025] 2. The present invention uses silver nanoparticles wrapped in silica as the core component of the antibacterial layer, and utilizes the sustained release mechanism of silver ions. The silver ions are continuously and slowly released, and have a long-term antibacterial effect. At the same time, the introduction of nano-silica particles is helpful for the subsequent coating and cross-linking of fluorosilicone coupling agents, so that the surface of the membrane material has antibacterial function;

[0026] 3. The hydrophobicity of membrane materials is crucial during the operation of seawater direct hydrogen production systems and salt lake water hydrogen production systems. Once infiltrated, chloride ions will pass through the membrane material into the electrolyzer, causing problems such as electrode corrosion and reduced hydrogen purity. The present invention uses a fluorosilane coupling agent as a super-hydrophobic layer. The agent can form a low surface energy surface and build a super-hydrophobic barrier on the surface of the membrane material, which greatly reduces the wetting problem of the membrane material during the application process, making the membrane material have a significant hydrophobic effect and improving the durability and self-cleaning ability of the material.

[0027] 4. The present invention has a flat membrane fixed on the surface of the fiber braided tube and the surface of the flat membrane is coated with an antibacterial layer and a hydrophobic layer to construct a high-performance membrane material that integrates support, filtration, antibacterial and super-hydrophobic properties. The membrane is suitable for the application environment of direct hydrogen production system from seawater, salt lake water hydrogen production system, desulfurization wastewater and other industrial wastewater to produce pure water.

[0028] 5. In the preparation method of the present invention, the fiber braided tube is subjected to alkalization treatment to enhance the stability and corrosion resistance of the fiber braided tube. High-temperature sintering ensures a firm bond between the flat membrane and the fiber braided tube, so that the entire multi-layer antibacterial superhydrophobic membrane can maintain good stability and durability in different water quality environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the present invention;

[0030] Figure 2 is the surface morphology of the unmodified membrane;

[0031] Figure 3 This is a surface morphology diagram of the membrane of Example 1 of the present invention.

[0032] The reference numerals in the figure represent:

[0033] 1. Fiber braided tube; 2. Flat membrane; 3. Antibacterial layer; 4. Super hydrophobic layer. DETAILED DESCRIPTION

[0034] The following is combined with Figure 1-3 The present invention is further described with reference to the following preferred embodiments. The embodiments are only provided to illustrate the present invention rather than to limit the scope of the present invention.

[0035] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources;

[0036] The quantitative tests in the following examples were repeated three times, and the results were averaged.

[0037] The experimental methods in the following embodiments are conventional methods unless otherwise specified.

[0038] Example 1

[0039] This embodiment provides a method for preparing a multi-layer antibacterial super-hydrophobic film, comprising the following steps:

[0040] S1: The glass fiber braided tube was alkalized with a 3wt% sodium hydroxide solution for 2h. After the treatment, it was washed with deionized water and dried at 90°C for 40min.

[0041] S2: evenly wrap a polytetrafluoroethylene (PTFE) flat membrane 2 with a pore size of 0.15 μm onto the outer wall of the glass fiber braided tube treated in step S1, ensuring that its coverage is 50% of the outer wall area of ​​the fiber braided tube 1, and sintering treatment is performed at a high temperature of 330° C. for 2 minutes to attach the flat membrane 2 to the glass fiber braided tube;

[0042] S3: immersing the membrane material obtained after high-temperature sintering in step S2 in a 3wt% potassium permanganate solution for 2 hours, then taking it out and rinsing it with deionized water for multiple times;

[0043] S4: soaking the membrane material after the soaking treatment in step S3 in a 0.4wt% aqueous solution of silica-coated silver nanoparticles at a temperature of 35° C. for 2 hours each time, and then drying for 10 minutes. Repeat this step 3 times until an antibacterial layer 3 is formed on the membrane surface;

[0044] S5: immersing the membrane material forming the antibacterial layer after the treatment in step S4 into a 3 vol% FOTS ethanol solution at a temperature of 35° C. and allowing to stand for 1 hour to form a super hydrophobic layer 4;

[0045] S6: placing the membrane material formed into the super hydrophobic layer after the treatment in step S5 in an oven at 120° C. for curing for 1 hour and then cooling to obtain a multi-layer super hydrophobic antibacterial membrane.

[0046] Example 2

[0047] This embodiment provides a method for preparing a multi-layer antibacterial super-hydrophobic film, comprising the following steps:

[0048] S1: The polylactic acid fiber braided tube was alkalized with a 5wt% sodium hydroxide solution for 4 hours. After the treatment, it was washed with deionized water and dried at 130°C for 10 minutes.

[0049] S2: evenly wrap the flat membrane 2 with a pore size of 0.1 μm and made of polyvinylidene fluoride (PVDF) to the outer wall of the polylactic acid fiber braided tube treated in step S1, ensuring that its coverage is 30% of the outer wall area of ​​the fiber braided tube 1, and sintering treatment is performed at a high temperature of 300° C. for 5 minutes to make the flat membrane 2 attached to the glass fiber braided tube;

[0050] S3: immersing the membrane material obtained after high-temperature sintering in step S2 in a 5wt% sodium permanganate solution for 1 hour, then taking it out and rinsing it with deionized water for multiple times;

[0051] S4: soaking the membrane material after the soaking treatment in step S3 in a 0.5wt% aqueous solution of silica-coated silver nanoparticles at a temperature of 30° C. for 3 hours each time, and then drying for 10 minutes. Repeat this step 3 times to form an antibacterial layer 3 on the surface of the flat membrane 2;

[0052] S5: immersing the film material forming the antibacterial layer after the treatment in step S4 into a 1 vol% triethoxysilane (POTS) anhydrous ethanol solution at a temperature of 30° C. and allowing to stand for 1 hour to form a super hydrophobic layer 4;

[0053] S6: placing the film material formed into the super hydrophobic layer after the treatment in step S5 in a 150° C. oven for curing for 0.5 h and then cooling to obtain a multi-layer super hydrophobic antibacterial film.

[0054] Example 3

[0055] This embodiment provides a method for preparing a multi-layer antibacterial super-hydrophobic film, comprising the following steps:

[0056] S1: The polyester fiber braided tube was alkalized with a 4 wt % potassium hydroxide solution for 3 h. After the treatment, it was washed with deionized water and dried at 120° C. for 20 min.

[0057] S2: evenly wrap the flat membrane 2 with a pore size of 0.3 μm and made of polyvinylidene fluoride (PVDF) to the outer wall of the polyester fiber braided tube treated in step S1, ensuring that its coverage is 40% of the outer wall area of ​​the fiber braided tube 1, and sintering treatment is performed at a high temperature of 320° C. for 4 minutes to make the flat membrane 2 adhere to the glass fiber braided tube;

[0058] S3: immersing the membrane material obtained after high-temperature sintering in step S2 in a 4 wt % sodium permanganate solution for 1.5 hours, then taking it out and rinsing it with deionized water for multiple times;

[0059] S4: soaking the membrane material after the soaking treatment in step S3 in a 0.6wt% aqueous solution of silica-encapsulated silver nanoparticles at a temperature of 45° C. for 4 hours each time, and then drying for 10 minutes. Repeat this step 3 times until an antibacterial layer 3 is formed on the membrane surface;

[0060] S5: immersing the membrane material forming the antibacterial layer after the treatment in step S4 into a 2 vol% 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FOTS) anhydrous ethanol solution at a temperature of 30° C. and allowing to stand for 1 hour to form a super hydrophobic layer 4;

[0061] S6: placing the film material formed into the super hydrophobic layer after the treatment in step S5 in an oven at 130° C. for curing for 1 hour and then cooling to obtain a multi-layer super hydrophobic antibacterial film.

[0062] Performance Testing:

[0063] 1. Hydrophobic performance test

[0064] A contact angle measuring instrument was used to test the contact angle of the multilayer antibacterial superhydrophobic film prepared in Examples 1-3 of the present invention in accordance with GB / T 30693-2014 "Standard for Testing the Contact Angle of Plastic Film and Water". Each film material exhibits significantly different contact angle characteristics due to its unique surface morphology, highlighting the direct influence of the surface structure on the wetting properties. The results are shown in Table 1. The surface contact angle of the multilayer antibacterial superhydrophobic film prepared in Examples 1-3 of the present invention is significantly improved compared with the unmodified film material.

[0065] Table 1 Film surface contact angle data

[0066]

[0067] 2. Surface morphology characterization

[0068] The unmodified membrane material and the multilayer antibacterial super-hydrophobic membrane prepared in Example 1 of the present invention were immersed in seawater at the same time, and the antibacterial properties of the membrane material surface were analyzed by observing the growth of microorganisms on the membrane surface.

[0069] like Figure 2 As shown, the multilayer antibacterial super-hydrophobic film prepared in Example 1 of the present invention has certain antibacterial properties, and the microorganisms on the surface of the film are significantly reduced.

[0070] In summary, the multi-layer antibacterial super-hydrophobic film prepared by the present invention has a high contact angle, which ensures that water droplets can quickly slide down the membrane surface, reduces the phenomenon of liquid adhesion and retention on the membrane surface, and the multi-layer antibacterial super-hydrophobic film prepared by the present invention can effectively inhibit the growth of microorganisms and prevent filter membrane pollution due to its attached antibacterial layer 3. The present invention is a high-performance membrane material integrating support, filtration, antibacterial and super-hydrophobic properties, and is suitable for a variety of specific working conditions and durable application environments.

[0071] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A multi-layer antibacterial super-hydrophobic film, characterized in that: The invention comprises a fiber braided tube (1) having a supporting function, a flat membrane (2) being solidified at high temperature on the upper surface of the fiber braided tube (1), antibacterial particles being attached to the upper surface of the flat membrane (2) to form an antibacterial layer (3), and the antibacterial layer (3) being coated with a low surface energy modifier to form a super hydrophobic layer (4) located on the top layer.

2. A multi-layer antibacterial super-hydrophobic film according to claim 1, characterized in that: The thickness of the multi-layer antibacterial super-hydrophobic membrane is 0.2-0.3 mm, wherein the thickness of the braided fiber tube (1) is 0.1-0.2 mm, and the thickness of the flat membrane (3) is 0.05-0.1 mm.

3. The method for preparing a multi-layer antibacterial super-hydrophobic film according to claim 1, characterized in that: The following steps are involved: S1: using an alkaline solution to alkalize the fiber braided tube (1), then rinsing it with deionized water and drying it; S2: Wrap the flat membrane (2) on the outer wall of the fiber braided tube (1) treated in step S1, ensuring that its coverage rate is 30% to 50% of the outer wall area of ​​the fiber braided tube (1), and then sinter the fiber braided tube (1) wrapped with the flat membrane (2) at a high temperature to make the flat membrane (2) adhere to the outer wall of the fiber braided tube (1). S3: soaking the membrane material obtained after high-temperature sintering in step S2 in a strong oxidant solution for 1-2 hours, then taking it out and rinsing it with deionized water; S4: soaking the membrane material after the soaking treatment in step S3 again in an antibacterial nanoparticle solution at a temperature of 30-45° C., and then drying it, so that an antibacterial layer (3) is formed on the surface of the flat membrane (2); S5: soaking the membrane material forming the antibacterial layer after the treatment in step S4 in a fluorosilane coupling agent solution at a temperature of 30-45° C. for 0.5-1 h to form a super hydrophobic layer (4) on the surface of the antibacterial layer (3); S6: placing the film material formed into the super hydrophobic layer after the treatment in step S5 in an oven at 120-150° C. for curing for 0.5-1 h and then cooling to obtain a multi-layer super hydrophobic antibacterial film.

4. The preparation method according to claim 3, characterized in that: In step S1, the fiber braided tube (1) is a glass fiber braided tube, a polylactic acid fiber braided tube or a polyester fiber braided tube.

5. The preparation method according to claim 3, characterized in that: In step S1, the alkaline solution is a sodium hydroxide or potassium hydroxide solution, the concentration of the alkaline solution is 3-5wt%, the alkalization time is 2-4h, the drying temperature is 90-130°C, and the drying time is 10-40min.

6. The preparation method according to claim 3, characterized in that: In step S2, the material of the flat membrane (2) is polyvinylidene fluoride or polytetrafluoroethylene, the pore size is 0.1-0.5 μm, the high temperature sintering temperature is 300-330° C., and the time is 2-5 min.

7. The preparation method according to claim 3, characterized in that: In step S3, the strong oxidant used is potassium permanganate or sodium permanganate with a concentration of 3-5 wt%.

8. The preparation method according to claim 3, characterized in that: In step S4, the antibacterial nanoparticles are silica-coated silver nanoparticles with a concentration of 0.2-0.6 wt %.

9. The preparation method according to claim 3, characterized in that: In step S5, the fluorosilane coupling agent is perfluorooctyltrichlorosilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane or triethoxysilane, and the concentration of the fluorosilane coupling agent is 1-3 vol%.

10. Use of the multi-layer antibacterial super-hydrophobic membrane according to any one of claims 1 to 8 in the production of pure water from industrial wastewater such as seawater desalination, membrane distillation, and desulfurization wastewater.

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