Anti-fouling ptfef hollow fiber membrane for municipal sewage aeration and preparation method thereof

Abstract

This application relates to an antifouling PTFE hollow fiber membrane for municipal wastewater aeration and its preparation method, comprising: mixing PTFE resin powder, lubricant, and modified NaY zeolite, and allowing it to stand for aging to obtain PTFE material; pressing and extruding the PTFE material to obtain nascent PTFE hollow fibers; degreasing the nascent PTFE hollow fibers to obtain de-oiled PTFE hollow fibers; stretching the de-oiled PTFE hollow fibers to obtain PTFE stretched pipes; sintering and heat-setting the PTFE stretched pipes to obtain shaped PTFE hollow fiber membranes; subjecting the shaped PTFE hollow fiber membranes to plasma surface treatment to obtain surface-treated PTFE hollow fiber membranes; immersing the surface-treated PTFE hollow fiber membranes in a mixed solution of acrylic acid, trimethylolpropane triacrylate, and benzoyl peroxide, reacting to obtain treated PTFE hollow fiber membranes; and then washing and drying to obtain the finished product. This application can improve the mechanical strength and antifouling performance of the finished product.

Description

Technical Field

[0001] This application relates to the field of PTFE hollow fiber membrane technology, and mainly to an anti-fouling PTFE hollow fiber membrane for municipal sewage aeration and its preparation method. Background Technology

[0002] PTFE hollow fiber membranes are hollow fiber separation membranes based on polytetrafluoroethylene (PTFE). Due to their excellent chemical stability, high-temperature resistance, and good mechanical properties, PTFE hollow fiber membranes are widely used in water treatment, gas separation, and environmental engineering. However, the inherent hydrophobicity of PTFE, along with problems such as hydraulic shock, chemical corrosion, and microbial erosion encountered during long-term operation, leads to membrane fouling and a decrease in mechanical strength, severely affecting membrane flux, service life, and operating efficiency.

[0003] The hydrophobic nature of PTFE hollow fiber membranes makes it easy for organic pollutants to adsorb onto their surface, forming a fouling layer that leads to membrane pore blockage and decreased flux. Traditional cleaning methods, such as chemical cleaning and backwashing, can restore membrane flux to some extent, but long-term use can damage the membrane structure and shorten its lifespan. Furthermore, municipal wastewater has a complex composition, containing large amounts of suspended solids, colloids, dissolved organic matter, and microorganisms. These substances deposit on the membrane surface, forming complex biofilms that further exacerbate membrane fouling.

[0004] On the other hand, PTFE materials have relatively low mechanical strength, making them susceptible to hydraulic impact and chemical corrosion during long-term operation, leading to membrane rupture and damage. Especially under high-pressure conditions, insufficient mechanical strength of the membrane limits its application range.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this application is to provide an antifouling PTFE hollow fiber membrane for municipal sewage aeration and its preparation method, which aims to improve mechanical strength and antifouling performance.

[0007] The technical solution of this application is as follows: A method for preparing a fouling-resistant PTFE hollow fiber membrane for municipal wastewater aeration includes the following steps: Modified NaY zeolite was obtained by treating NaY zeolite with a coupling agent. PTFE resin powder, lubricant, and modified NaY zeolite are mixed at 1000-1200 r / min, and then allowed to stand and mature at 55-65℃ for 24-36 h to form PTFE material. PTFE material is pressed and extruded to obtain nascent PTFE hollow fibers; Nasal PTFE hollow fibers are heated at 220-260℃ to remove oil, yielding deoiled PTFE hollow fibers; Deoiled PTFE hollow fibers are stretched to obtain PTFE stretched pipes; PTFE stretched pipes are heat-set by sintering at 360-385℃ for 3-10 minutes to obtain shaped PTFE hollow fiber membranes. The shaped PTFE hollow fiber membrane is subjected to plasma surface treatment in a mixed gas of oxygen and argon to obtain a surface-treated PTFE hollow fiber membrane. Surface-treated PTFE hollow fiber membranes are immersed in a mixed solution containing acrylic acid, trimethylolpropane triacrylate, and benzoyl peroxide, and reacted at 55-65℃ for 1.5-2.5 hours to obtain treated PTFE hollow fiber membranes. After washing and drying, the PTFE hollow fiber membrane is processed to obtain a fouling-resistant PTFE hollow fiber membrane for use in municipal wastewater aeration.

[0008] Acrylic acid undergoes graft polymerization on the surface of the PTFE membrane, while TMPTA connects adjacent polyacrylic acid chains to form a hydrophilic three-dimensional cross-linked network of polyacrylic acid.

[0009] Furthermore, the lubricant includes one or a mixture of two or more of toluene, white oil, and acetone.

[0010] Furthermore, the preparation of modified NaY zeolite includes the following steps: NaY zeolite is mixed with an organic solvent to obtain a NaY zeolite suspension; Add a coupling agent to the NaY zeolite suspension; then stir the reaction at 35-45℃ for 6-12 hours. After the reaction was completed, the solid product was washed and dried to obtain modified NaY zeolite.

[0011] Furthermore, the weight ratio of the surface-treated PTFE hollow fiber membrane, acrylic acid, trimethylolpropane triacrylate, and benzoyl peroxide is 1:(1.2-1.5):(0.02-0.06):(0.01-0.02).

[0012] Furthermore, the pressing process includes: pressing PTFE material into a hollow cylindrical blank at a temperature of 50-55℃; Extrusion includes: extruding a hollow cylindrical preform at a temperature of 58-62℃ to form nascent PTFE hollow fibers.

[0013] Furthermore, the deoiling process includes: deoiling the nascent PTFE hollow fibers at a temperature of 215-225°C for 1-3 hours, then deoiling them at a temperature of 235-245°C for 0.5-1.5 hours, and finally deoiling them at a temperature of 255-265°C until the weight is stable.

[0014] Furthermore, during stretching, the temperature of the stretching section is 260~360℃, the longitudinal stretching is 150-250%, and the transverse stretching is 80-120%.

[0015] Furthermore, the washing process for treating PTFE hollow fiber membranes includes: soaking in an alkaline solution for 1-3 hours, soaking in an acidic solution for 1-3 hours, and soaking in water for 2-4 hours.

[0016] This application also provides a fouling-resistant PTFE hollow fiber membrane for municipal wastewater aeration.

[0017] Furthermore, by weight, the PTFE resin is 95-105 parts, the lubricant is 10-20 parts, and the modified NaY zeolite is 5-10 parts.

[0018] Compared with the prior art, this application has the following beneficial effects: 1. Modified NaY zeolite and surface-grafted polyacrylic acid hydrophilic network construct a dual protective gradient of "adsorption-resistance". Modified NaY zeolite directionally captures macromolecular pollutants such as heavy metal ions, ammonia nitrogen, and humic acid through molecular sieve effect and electrostatic adsorption, achieving "internal interception"; the hydrophilic network forms an "external protective layer" with a three-dimensional cross-linked structure. Its high hydrophilicity generates a hydration layer effect, inhibiting the adhesion of proteins and bacteria through steric hindrance and electrostatic repulsion. The two complement each other to form an "internal adsorption and external resistance" structure, which avoids the easy saturation and failure of a single adsorption layer and overcomes the long-term pollution accumulation defects of pure hydrophilic networks, achieving highly efficient anti-pollution in municipal sewage aeration.

[0019] 2. After modification with a silane coupling agent, NaY zeolite forms a strong interfacial chemical bond with the PTFE matrix. Its rigid nanofiller properties inhibit PTFE molecular chain slippage through the "pinning effect," enhancing its resistance to deformation. The hydrophilic polyacrylic acid network forms a three-dimensional interpenetrating network through TMPTA crosslinking. The flexible segments can absorb tensile energy, disperse stress concentration, and avoid localized fracture. Together with the PTFE matrix, these two components form a "rigid-tough" composite structure. The tertiary chemical bonding system ensures that the adsorption sites remain stable and do not detach during severe deformations such as stretching and sintering, significantly improving the tensile strength and mechanical impact resistance of the membrane.

[0020] 3. The dynamic adsorption of modified NaY zeolite and the static impedance of the polyacrylic acid network form a "dynamic-static" synergistic effect. The hydrophilic network delays the formation of the fouling layer through the hydration layer, while the modified NaY zeolite continuously captures pollutants and reduces their concentration. The pH sensitivity of the polyacrylic acid chains and the ion exchange capacity of zeolite form a pH-adaptive synergy, adapting to the common pH range of municipal wastewater. The antioxidant TMPTA and the adsorption capacity of zeolite work together to reduce oxidative damage, ensuring long-term stable operation of the membrane under complex operating conditions. Detailed Implementation

[0021] To facilitate understanding of this application, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of this application.

[0022] This application also provides a method for preparing a fouling-resistant PTFE hollow fiber membrane for municipal wastewater aeration, comprising the following steps: Step 1: Preparation of modified NaY zeolite, including the following steps: Commercially available NaY zeolite was dried in a vacuum drying oven at 120-130℃ for 2-4 hours to remove adsorbed moisture.

[0023] The dried NaY zeolite was dispersed in anhydrous ethanol at a solid-liquid ratio of 1:(8-12) (g / mL) and ultrasonically dispersed for 20-60 minutes to form a uniform NaY zeolite suspension.

[0024] While stirring, silane coupling agent KH-570 was added dropwise to the NaY zeolite suspension, with the mass ratio of KH-570 to NaY zeolite being 1:(8-12).

[0025] Continue stirring the reaction at 35-45℃ for 6-12 hours.

[0026] After the reaction is complete, the solid product is separated by centrifugation.

[0027] The solid product was washed three times with anhydrous ethanol to remove unreacted KH-570.

[0028] The washed solid product was dried in a vacuum drying oven at 55-65℃ for 12-36 hours to obtain modified NaY zeolite.

[0029] Step 2: Mixing and maturation: Mix PTFE resin powder, lubricant, and modified NaY zeolite at 1000-1200 r / min for 20-40 min, and then let it stand and mature at 55-65℃ for 24-36 h to fully mix the resin powder, lubricant, and modified NaY zeolite to form PTFE material.

[0030] Lubricants include one or a mixture of two or more of toluene, white oil, and acetone.

[0031] By weight, PTFE resin is 95-105 parts, lubricant is 10-20 parts, and modified NaY zeolite is 5-10 parts.

[0032] Step 3: Paste extrusion: PTFE material is poured into a cylindrical compact press with a mandrel, and pressed into a hollow cylindrical blank at a temperature of 50-55℃.

[0033] The hollow cylindrical preform is then extruded through a press at a temperature of 58-62℃ to form nascent PTFE hollow fibers.

[0034] Step 4: Oil removal: Nascent PTFE hollow fibers are heated at 220-260℃ to remove oil and lubricant, preventing defects during subsequent stretching. This yields deoiled PTFE hollow fibers.

[0035] Specifically, maintain at 215-225℃ for 1-3 hours, at 235-245℃ for 0.5-1.5 hours, and at 255-265℃ until the lubricant is completely removed (until the weight is stable).

[0036] Step 5: Axial tension: A rotating screw is used to achieve stepless stretching through a gradual change in screw diameter. Specifically, deoiled PTFE hollow fibers enter from the smallest end of the screw and exit from the largest end, achieving longitudinal stretching by utilizing the difference in linear velocity on the screw surface; transverse stretching is achieved by restricting the length change in the calendering direction. This yields stretched PTFE tubing.

[0037] Temperature of the stretching section: 260~360℃, longitudinal stretching: 150-250%, transverse stretching: 80-120%.

[0038] Step 6: Heat setting: PTFE stretched pipes are sintered and heat-set at 360-385℃ for 3-10 minutes to obtain shaped PTFE hollow fiber membranes.

[0039] Step 7: Surface treatment: The shaped PTFE hollow fiber membrane is treated with plasma at a power of 80-120W for 3-10 minutes in a mixed gas of oxygen and argon (volume ratio 1:(0.8-1.2)) and a vacuum degree of 5-10Pa to obtain a surface-treated PTFE hollow fiber membrane.

[0040] Step 8: Immerse the surface-treated PTFE hollow fiber membrane in a mixed solution of acrylic acid (AA) and trimethylolpropane triacrylate (TMPTA), then add benzoyl peroxide (BPO) and react at 55-65℃ for 1.5-2.5 hours under nitrogen protection (flow rate 45-55 mL / min).

[0041] Acrylic acid undergoes graft polymerization on the PTFE membrane surface, while TMPTA connects adjacent polyacrylic acid chains to form a three-dimensional cross-linked network. The membrane is then removed to obtain the treated PTFE hollow fiber membrane.

[0042] The weight ratio of surface-treated PTFE hollow fiber membrane, acrylic acid, trimethylolpropane triacrylate, and benzoyl peroxide is 1:(1.2-1.5):(0.02-0.06):(0.01-0.02).

[0043] Step 9: Post-processing: The PTFE hollow fiber membrane was soaked in 0.1M NaOH solution for 1-3 hours, in 0.1M HCl solution for 1-3 hours, and in deionized water for 2-4 hours to remove residual acrylic acid and unreacted monomers.

[0044] Then, it is placed in a vacuum drying oven and dried at 55-65℃ for 24-36 hours to obtain a pollution-resistant PTFE hollow fiber membrane for municipal sewage aeration.

[0045] Modified NaY zeolite, after surface modification with the silane coupling agent KH-570, forms an adsorption core possessing both ion exchange capacity and chemical bonding properties. This adsorption layer is uniformly dispersed within a PTFE matrix, enabling the targeted capture of typical pollutants in municipal wastewater—such as heavy metal ions, ammonia nitrogen, and humic acid—through molecular sieve effects and electrostatic adsorption, achieving "internal retention" of pollutants. Simultaneously, a surface-grafted hydrophilic polyacrylic acid network forms an "external protective layer" through a three-dimensional cross-linked structure. Its high hydrophilicity imparts a hydration layer effect to the membrane surface, inhibiting the adhesion of pollutants such as proteins and bacteria through steric hindrance and electrostatic repulsion, forming a dual "adsorption-resistance" protective gradient. These two elements spatially form a complementary "internal adsorption, external resistance" structure, avoiding the problem of easy saturation and failure of a single adsorption layer while overcoming the pollution accumulation defects of a pure hydrophilic network during long-term operation.

[0046] Modified NaY zeolite forms a strong interfacial bond with the PTFE matrix through chemical bonding, ensuring that adsorption sites do not detach or aggregate during severe deformation processes such as stretching and sintering. Meanwhile, the hydrophilic polyacrylic acid network forms a three-dimensional network through TMPTA crosslinking. This network not only covalently anchors to the active sites on the plasma-pretreated membrane surface but also forms secondary chemical bonds with the modified NaY zeolite surface through crosslinking points. This three-tiered chemical bonding system of "matrix-adsorption layer-hydrophilic network" ensures that the adsorption layer and hydrophilic network maintain structural stability under long-term hydraulic scouring and chemical cleaning conditions, avoiding functional degradation in the "adsorption-desorption" cycle and achieving long-lasting antifouling performance.

[0047] During wastewater aeration, the dynamic adsorption capacity of modified NaY zeolite and the static impedance capacity of the polyacrylic acid network form a synergistic "dynamic-static" effect. Modified NaY zeolite continuously captures pollutants in flowing wastewater through ion exchange and molecular sieve effects, reducing pollutant concentration; while the hydrophilic network of polyacrylic acid reduces the initial adhesion of pollutants to the membrane surface through the hydration layer effect, delaying the formation of a fouling layer. Over time, this creates a dynamic protection logic of "impedance first, adsorption later"—in the initial stage, the impedance effect of the hydrophilic network dominates, reducing pollutant adhesion; in the later stages of operation, the continuous capture by the adsorption layer dominates, reducing pollutant concentration. This synergy enables the membrane to maintain high flux and low pollution characteristics during long-term operation, making it particularly suitable for municipal wastewater aeration scenarios with large fluctuations in pollution load.

[0048] Regarding the combination of modified NaY zeolite and surface-grafted polyacrylic acid hydrophilic network: 1. After modification with KH-570, NaY zeolite exhibits surface-grafted organic segments that can form a "core-shell" micro-region nesting with the hydrophilic network of polyacrylic acid. The zeolite core provides adsorption sites, while the outer organic segments are cross-linked with the polyacrylic acid chains through covalent or hydrogen bonds, forming a gradient structure of "adsorption core-hydrophilic shell." This nesting not only enhances the dispersion stability of zeolite in the PTFE matrix but also strengthens the electrostatic adsorption of positively charged pollutants (such as NH4⁺ and heavy metal ions) through interfacial charge regulation (e.g., the negative charge on the zeolite surface synergistically with the negative charge of the carboxylate group in polyacrylic acid).

[0049] 2. The molecular sieve channels (nanoscale) of modified NaY zeolite and the macroscopic pores (micrometer scale) of PTFE hollow fiber membrane form a "micro-macro" pore coupling. Some pollutants are screened and adsorbed by the zeolite channels, while small molecules that are not adsorbed are blocked by the hydration layer of the hydrophilic network, achieving a dual screening effect of "size-charge".

[0050] 3. The carboxyl group (-COO⁻) of the polyacrylic acid chain is pH sensitive. Under acidic or neutral conditions (common pH 6-8 in municipal wastewater), it can dissociate and become negatively charged, enhancing the electrostatic adsorption of cationic pollutants. Meanwhile, the ion exchange capacity of modified NaY zeolite may be weakened under alkaline conditions. At this time, the electrostatic effect of the hydrophilic network can compensate for the adsorption capacity, forming a pH-adaptive synergy.

[0051] 4. While the PTFE matrix itself possesses excellent antioxidant properties, the introduction of modified NaY zeolite and a hydrophilic network may introduce new oxidation risks (such as catalytic oxidation by metal ions in the zeolite). However, TMPTA in the polyacrylic acid crosslinking network acts as an antioxidant, capturing free radicals and reducing the damage to the adsorption sites of the modified NaY zeolite caused by oxidation reactions. Simultaneously, the adsorption capacity of the modified NaY zeolite can remove oxidizing substances (such as residual chlorine) from the water, protecting the hydrophilic network from oxidative degradation.

[0052] 5. The hydrophilic network of polyacrylic acid reduces initial bacterial adhesion through the hydration layer, while modified NaY zeolite has the ability to adsorb bacterial metabolites (such as polysaccharides and proteins), which can reduce the accumulation of these substances on the membrane surface, thereby inhibiting biofilm formation. The two work synergistically to achieve a double insurance against bioadhesion through "physical resistance + chemical adsorption".

[0053] 6. After modification with KH-570, the organic segments grafted onto the surface of NaY zeolite form chemical bonds (such as Si-OC bonds) with the PTFE matrix, allowing the zeolite to be uniformly dispersed in the matrix as a rigid nanofiller. Its high hardness (Mohs hardness 5-6) effectively inhibits the slippage of PTFE molecular chains, enhancing the matrix's resistance to deformation through the "pinning effect" and directly improving tensile strength. Furthermore, the grafted polyacrylic acid forms a three-dimensional cross-linked network through TMPTA, and its flexible segments can absorb energy during stretching, dispersing stress concentration through segment movement and preventing localized fracture. The cross-linked network and PTFE molecular chains form an "interpenetrating network," enhancing the overall toughness of the matrix. Simultaneously, through chemical bonding with the zeolite surface, it forms a secondary reinforcement, creating a "rigid-tough" composite structure.

[0054] The present application will be further described below through specific embodiments.

[0055] Example 1 A method for preparing a fouling-resistant PTFE hollow fiber membrane for municipal wastewater aeration includes the following steps: Step 1: Preparation of modified NaY zeolite, including the following steps: Commercially available NaY zeolite was dried in a vacuum drying oven at 120°C for 2 hours to remove adsorbed moisture.

[0056] The dried NaY zeolite was dispersed in anhydrous ethanol at a solid-liquid ratio of 1:10 (g / mL) and ultrasonically dispersed for 30 minutes to form a uniform NaY zeolite suspension.

[0057] While stirring, silane coupling agent KH-570 was added dropwise to the NaY zeolite suspension, with a mass ratio of KH-570 to NaY zeolite of 1:10.

[0058] Continue stirring and reacting at 40°C for 8 hours.

[0059] After the reaction is complete, the solid product is separated by centrifugation.

[0060] The solid product was washed three times with anhydrous ethanol to remove unreacted KH-570.

[0061] The washed solid product was dried in a vacuum drying oven at 60°C for 24 hours to obtain modified NaY zeolite.

[0062] Step 2: Mixing and maturation: 100 kg of PTFE resin powder (commercially available, Teflon® PTFE NXT75 was selected in this example), 15 kg of lubricant (acetone), and 8 kg of modified NaY zeolite were mixed at 1000 r / min for 30 min, and then allowed to stand and mature at 60°C for 24 h to fully mix the resin powder, lubricant, and modified NaY zeolite to form PTFE material.

[0063] Step 3: Paste extrusion: PTFE material is poured into a cylindrical press with a mandrel, and pressed into a hollow cylindrical blank at a temperature of 50°C.

[0064] The hollow cylindrical preform is then extruded through a press at a temperature of 60°C to form nascent PTFE hollow fibers.

[0065] Step 4: Oil removal: Nascent PTFE hollow fibers are heated at 220-260℃ to remove oil and lubricant, preventing defects during subsequent stretching. This yields deoiled PTFE hollow fibers.

[0066] Specifically, maintain at 220°C for 2 hours, 240°C for 1 hour, and 260°C until the lubricant is completely removed (until the weight stabilizes).

[0067] Step 5: Axial tension: A rotating screw is used to achieve stepless stretching through a gradual change in screw diameter. Specifically, deoiled PTFE hollow fibers enter from the smallest end of the screw and exit from the largest end, achieving longitudinal stretching by utilizing the difference in linear velocity on the screw surface; transverse stretching is achieved by restricting the length change in the calendering direction. This yields stretched PTFE tubing.

[0068] Temperature of the stretching section: 330℃, longitudinal stretching: 200%, transverse stretching: 100%.

[0069] Step 6: Heat setting: PTFE stretched pipes were heat-set by sintering at 380℃ for 5 minutes to obtain shaped PTFE hollow fiber membranes.

[0070] Step 7: Surface treatment: The shaped PTFE hollow fiber membrane was treated with plasma power of 100W for 5 minutes in a mixture of oxygen and argon gas (volume ratio 1:1) at a vacuum degree of 10Pa.

[0071] Step 8: Immerse the shaped PTFE hollow fiber membrane in a mixed solution of acrylic acid (AA) and trimethylolpropane triacrylate (TMPTA), then add benzoyl peroxide (BPO), and react at 60°C for 2 hours under nitrogen protection (flow rate 50 mL / min).

[0072] Acrylic acid undergoes graft polymerization on the surface of the PTFE membrane, while TMPTA connects adjacent polyacrylic acid chains to form a three-dimensional cross-linked network. This process yields a treated PTFE hollow fiber membrane.

[0073] The weight ratio of the shaped PTFE hollow fiber membrane, acrylic acid, trimethylolpropane triacrylate, and benzoyl peroxide is 1:1.4:0.02:0.015.

[0074] Step 9: Post-processing: The PTFE hollow fiber membrane was soaked in 0.1M NaOH solution for 2 hours, 0.1M HCl solution for 2 hours, and deionized water for 2 hours to remove residual acrylic acid and unreacted monomers.

[0075] Then, it is placed in a vacuum drying oven and dried at 60°C for 24 hours to obtain a pollution-resistant PTFE hollow fiber membrane for municipal sewage aeration.

[0076] Performance testing: 1. Hydrophilicity: Referring to GB / T 30693-2014 "Measurement of the contact angle between plastic film and water", deionized water was dropped onto the outer side of the anti-fouling PTFE hollow fiber membrane used for municipal sewage aeration, and the contact angle of the water droplet on its surface was measured. The contact angles at 5 different locations were measured and the average value was taken.

[0077] 2. Flux: The hollow fiber membrane is assembled into a membrane module, and pure water is used as feed water. The test is carried out under a pressure of 0.1 MPa. The volume of pure water passing through a unit area of ​​membrane per unit time is recorded, and the pure water flux is calculated.

[0078] 3. Anti-fouling: The hollow fiber membrane module is installed on the membrane filtration device, and pure water is used as the feed water. The test is carried out under a pressure of 0.1 MPa. The volume of pure water passing through the unit area of ​​the membrane per unit time is recorded, and the pure water flux is calculated. This is the initial flux.

[0079] Then filter with BSA solution (concentration 1g / L) for 2 hours.

[0080] Backwash with deionized water for 30 minutes. Once the flux stabilizes, record the flux value. This is the flux after backwashing.

[0081] Antifouling performance is expressed as flux recovery rate (FRR), which is calculated as: FRR = (flux after backwashing / initial flux) × 100%.

[0082] 4. Mechanical strength: Referring to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", the hollow fiber film is cut into strips of a certain length, fixed on the fixture of the universal testing machine, and stretched at a certain tensile speed until the sample breaks. The tensile strength is recorded.

[0083] Test results: 1. Hydrophilicity: Water contact angle is 45°.

[0084] 2. Flux: The pure water flux is 450 L / (m²). 2 ·h).

[0085] 3. Pollution resistance: FRR is 95%.

[0086] 4. Mechanical strength: Tensile strength is 27.5 MPa.

[0087] Comparative Example 1 The difference from Example 1 is that the modified NaY zeolite is replaced with NaY zeolite.

[0088] Test results: 1. Hydrophilicity: Water contact angle is 80°.

[0089] 2. Flux: Pure water flux is 400 L / (m²) 2 ·h).

[0090] 3. Pollution resistance: FRR is 86%.

[0091] 4. Mechanical strength: Tensile strength is 19.5 MPa.

[0092] Comparative Example 2 The difference from Example 1 is that step 8 is omitted.

[0093] Test results: 1. Hydrophilicity: Water contact angle is 100°.

[0094] 2. Flux: The pure water flux is 405 L / (m²). 2 ·h).

[0095] 3. Pollution resistance: FRR is 82%.

[0096] 4. Mechanical strength: Tensile strength is 22MPa.

[0097] Comparative Example 3 The difference from Example 1 is that the modified NaY zeolite and step 8 are omitted.

[0098] Test results: 1. Hydrophilicity: Water contact angle is 105°.

[0099] 2. Flux: Pure water flux is 300 L / (m²). 2 ·h).

[0100] 3. Pollution resistance: FRR is 75%.

[0101] 4. Mechanical strength: Tensile strength is 16.5 MPa.

[0102] Comparative Example 3 omitted modified NaY zeolite and step 8. According to the test data, the antifouling PTFE hollow fiber membrane of Example 1 for municipal sewage aeration has good hydrophilicity, high flux, high antifouling performance, and good mechanical properties. All aspects of its performance are significantly improved compared with Comparative Example 3.

[0103] Comparative Examples 1 and 2 disrupted the synergy between the modified NaY zeolite and the surface-grafted polyacrylic acid hydrophilic network, resulting in a significant performance difference between the antifouling PTFE hollow fiber membranes of Comparative Examples 1 and 2 used for municipal wastewater aeration and those of Example 1. This demonstrates that the synergy between the modified NaY zeolite and the surface-grafted polyacrylic acid hydrophilic network in the system is indispensable.

[0104] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of this application.

Claims

1. A method for preparing a pollution-resistant PTFE hollow fiber membrane for municipal wastewater aeration, characterized in that, Includes the following steps: Modified NaY zeolite was obtained by treating NaY zeolite with a coupling agent. PTFE resin powder, lubricant, and modified NaY zeolite are mixed at 1000-1200 r / min, and then allowed to stand and mature at 55-65℃ for 24-36 h to form PTFE material. PTFE material is pressed and extruded to obtain nascent PTFE hollow fibers; Nasal PTFE hollow fibers are heated at 220-260℃ to remove oil, yielding deoiled PTFE hollow fibers; Oil-free PTFE hollow fibers are stretched to obtain PTFE stretched pipes; PTFE stretched pipes are heat-set by sintering at 360-385℃ for 3-10 minutes to obtain shaped PTFE hollow fiber membranes. The shaped PTFE hollow fiber membrane is subjected to plasma surface treatment in a mixed gas of oxygen and argon to obtain a surface-treated PTFE hollow fiber membrane. Surface-treated PTFE hollow fiber membranes are immersed in a mixed solution containing acrylic acid, trimethylolpropane triacrylate, and benzoyl peroxide, and reacted at 55-65℃ for 1.5-2.5 hours to obtain treated PTFE hollow fiber membranes. After washing and drying, the PTFE hollow fiber membrane is processed to obtain a fouling-resistant PTFE hollow fiber membrane for use in municipal wastewater aeration.

2. The method for preparing the anti-fouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 1, characterized in that, Lubricants include one or a mixture of two or more of toluene, white oil, and acetone.

3. The method for preparing the anti-fouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 1, characterized in that, The preparation of modified NaY zeolite includes the following steps: NaY zeolite is mixed with an organic solvent to obtain a NaY zeolite suspension; Add a coupling agent to the NaY zeolite suspension; then stir the reaction at 35-45℃ for 6-12 hours. After the reaction was completed, the solid product was washed and dried to obtain modified NaY zeolite.

4. The method for preparing the anti-fouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 1, characterized in that, The weight ratio of surface-treated PTFE hollow fiber membrane, acrylic acid, trimethylolpropane triacrylate, and benzoyl peroxide is 1:(1.2-1.5):(0.02-0.06):(0.01-0.02).

5. The method for preparing the anti-fouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 1, characterized in that, Suppression includes: PTFE material is pressed into hollow cylindrical blanks at a temperature of 50-55℃. Extrusion includes: extruding a hollow cylindrical preform at a temperature of 58-62℃ to form nascent PTFE hollow fibers.

6. The method for preparing the anti-fouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 1, characterized in that, Oil removal includes: Nascent PTFE hollow fibers are de-oiled at 215-225℃ for 1-3 hours, then at 235-245℃ for 0.5-1.5 hours, and finally at 255-265℃ until weight is stable.

7. The method for preparing the anti-fouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 1, characterized in that, During stretching, the temperature of the stretching section is 260~360℃, the longitudinal stretching is 150-250%, and the transverse stretching is 80-120%.

8. The method for preparing the anti-fouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 1, characterized in that, The washing process for PTFE hollow fiber membranes includes: soaking in an alkaline solution for 1-3 hours, soaking in an acidic solution for 1-3 hours, and soaking in water for 2-4 hours.

9. A PTFE hollow fiber membrane for municipal sewage aeration prepared by the method of preparing the PTFE hollow fiber membrane for municipal sewage aeration according to any one of claims 1-8.

10. The antifouling PTFE hollow fiber membrane for municipal wastewater aeration according to claim 9, characterized in that, By weight, PTFE resin is 95-105 parts, lubricant is 10-20 parts, and modified NaY zeolite is 5-10 parts.