Preparation and application method of MABR membrane with high mass transfer efficiency

Abstract

The invention relates to the technical field of water treatment materials, in particular to a preparation and application method of a high-mass-transfer-efficiency MABR membrane, and the preparation and application method comprises the following steps: (1) preparing a core layer spinning solution; (2) preparing a sheath spinning solution to obtain a sheath spinning solution; (3) performing coaxial electrostatic spinning to obtain a fiber membrane precursor; (4) obtaining a fiber membrane base membrane; (5) hydrophobizing the gas side surface to obtain a gas side modified fiber membrane; (6) carrying out hydrophilic modification on a water side to obtain an MABR crude membrane; and (7) drying to obtain the MABR membrane with high mass transfer efficiency. Through collaborative design of the components and the process, the problem that high air permeability, high strength and a stable hydrophilic interface of a traditional MABR film are difficult to realize at the same time is effectively solved.

Description

Preparation and application method of a high mass transfer efficiency MABR membrane Technical Field

[0001] This invention relates to the field of water treatment materials technology, specifically to a method for preparing and applying a high mass transfer efficiency MABR membrane. Background Technology

[0002] MABR membranes, the core component of membrane aerated biofilm reactors, are specialized functional membranes that achieve bubble-free aeration. Their core principle is that oxygen is supplied to one side of the membrane (gas side), and through the selective permeability of the membrane material, it diffuses through the membrane wall in the form of molecules, directly supplying the microbial membrane growing on the other side (water side). This mass transfer method achieves ultra-high mass transfer efficiency of oxygen from the gas phase to the biofilm, while avoiding the significant energy loss caused by oxygen escaping in the form of bubbles in traditional aeration.

[0003] From a materials science perspective, an ideal MABR membrane needs to simultaneously satisfy several mutually restrictive performance characteristics: high permeability to ensure mass transfer rate, sufficient mechanical strength to maintain structure, suitable hydrophilicity to regulate biofilm adhesion, and chemical and biological stability under long-term operation. Currently, the homogeneous dense membranes or composite membranes widely used in MABR membrane materials cannot simultaneously achieve high gas selectivity and high permeability, which directly limits oxygen mass transfer efficiency and affects the system's treatment capacity and operating energy consumption. The mechanical strength and durability of MABR membrane materials are often insufficient, making it difficult to withstand the physical and hydraulic shocks in the water treatment environment over a long period. In addition, issues such as biofilm growth regulation and the long-term stability of the surface modification layer further increase the complexity of operation and maintenance and the risk of performance degradation.

[0004] CN 103182254 A discloses a composite membrane for MABR and its preparation method. The composite membrane is composed of a porous membrane and a levodopa composite layer laminated on the surface of the porous membrane. The steps are as follows: (1) Preparation of levodopa solution: Levodopa is prepared into a levodopa solution with a concentration of 0.05~3g / L; (2) Coating: The levodopa solution is uniformly coated on the outer surface of the membrane; (3) Heat treatment: The composite membrane is heat treated. The advantages of the MABR composite membrane prepared by this invention are: the prepared membrane has high oxygen permeability, good surface hydrophilicity and biocompatibility, and large membrane surface roughness. However, this invention does not focus on mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying a high mass transfer efficiency MABR membrane. Through the synergistic design of components and processes, it effectively solves the problem that traditional MABR membranes cannot simultaneously achieve high air permeability, high strength and stable hydrophilic interface.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a high mass transfer efficiency MABR membrane, comprising the following steps: (1) preparing a core layer spinning solution: dissolving thermoplastic polyurethane in N,N-dimethylformamide to form a thermoplastic polyurethane solution with a mass fraction of 12%-16%; adding surface-modified nano-titanium silicate zeolite to the thermoplastic polyurethane solution, and obtaining a uniform and stable core layer spinning solution after ultrasonic dispersion; (2) preparing a sheath layer spinning solution: dissolving thermoplastic polyurethane and amphiphilic block copolymer in a mass ratio of 8:2-7:3 in a mixed solvent of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran, wherein the total mass fraction of the thermoplastic polyurethane and the amphiphilic block copolymer is 10%-14%. %, to obtain sheath spinning solution; (3) Coaxial electrospinning: using a coaxial electrospinning device, the core spinning solution obtained in step (1) is used as the inner spinning solution, and the sheath spinning solution obtained in step (2) is used as the outer spinning solution, spinning is performed and collected on the receiving device to obtain the fiber membrane precursor; (4) Fiber membrane base membrane: (4.1) The fiber membrane precursor obtained in step (3) is placed in a mixed organic solvent vapor environment composed of acetone and ethanol for steam treatment for 5-15 minutes at a temperature of 25-35℃; (4.2) The fiber membrane treated in step (4.1) is placed between two layers of high porosity buffer pads and steamed at 60-70℃ at 0.05-0.15℃. Hot pressing was performed for 10-20 minutes under MPa conditions; then the pressure was released and heat-set at 60-70℃ for 20-30 minutes to obtain the fiber membrane base; (5) Hydrophobic treatment of the gas side surface: the gas side surface of the fiber membrane base obtained in step (4) was subjected to low-temperature plasma or ultraviolet treatment, followed by chemical vapor deposition to obtain the gas side modified fiber membrane; (6) Hydrophilic modification of the water side: the gas side modified fiber membrane obtained in step (5) was flipped so that the water side was facing up, and dopamine biomimetic coating treatment and polyethyleneimine crosslinking treatment were performed in sequence to obtain the MABR rough membrane; (7) Drying: the rough membrane was vacuum dried at 40-50℃ to obtain the high mass transfer efficiency MABR membrane.

[0007] The technical mechanism of this invention lies in constructing a core-sheath fiber structure using coaxial electrospinning. The hydrophobic core layer primarily provides mechanical support and forms continuous channels for gas diffusion. The introduction of nanoparticles aims to moderately enhance mechanical properties and mass transfer pathways; excessive addition may lead to excessively high viscosity of the spinning solution or fiber defects. The hydrophilically modified sheath layer constitutes the interfacial basis for biofilm adhesion. The addition of amphiphilic copolymers regulates surface energy; too low a proportion results in insufficient hydrophilic modification, while too high a proportion may affect the uniformity of the spinning solution and fiber formation. Subsequent controllable solvent vapor-induced fusion is a crucial step. The mixed vapors of acetone and ethanol require precise control of the ratio and processing time to induce slight melting and adhesion at fiber contact points, significantly improving the integrity and mechanical strength of the membrane while avoiding excessive dissolution that could lead to pore collapse and decreased permeability. Buffered hot-pressing further consolidates this three-dimensional network structure and improves dimensional stability under moderate pressure and temperature; excessive pressure or temperature can irreversibly compress the pores.

[0008] This invention employs a functional partitioning design on both sides of the MABR membrane to precisely adapt to the working interface requirements of the MABR: On the gas side (i.e., the side of the MABR membrane that comes into contact with air after assembly), a high-density active site is first introduced onto the fiber surface through low-temperature plasma or ultraviolet treatment; subsequently, low-pressure chemical vapor deposition allows fluorinated silane precursors to undergo chemical adsorption and self-assembly at the active sites, forming a robust and uniform superhydrophobic interface layer. This hydrophobic layer effectively prevents backflow of liquid water into the membrane pores and gas chambers during operation, ensuring the continuous unobstructed flow of gas diffusion channels. On the water side (i.e., the side of the MABR membrane that comes into contact with water after assembly and is used for microbial attachment), a robust hydrophilic polymer network is constructed on the fiber surface through a sequential reaction of dopamine biomimetic coating and polyethyleneimine crosslinking. This hydrophilic layer provides an ideal attachment interface for microorganisms, promoting rapid and uniform biofilm formation, while its chemical crosslinking structure ensures stability in long-term aqueous environments.

[0009] Preferably, in step (1), the surface-modified nano-titanium silicate zeolite is obtained by treating nano-titanium silicate zeolite with an average particle size of 80-180 nm with a silane coupling agent; the amount of nano-titanium silicate zeolite added is 15%-30% of the mass of thermoplastic polyurethane.

[0010] The selection of an average particle size of 80-180 nanometers is based on a balance between spinning process and functionalization: too small a particle size easily leads to severe agglomeration, making uniform dispersion in the spinning solution difficult; too large a particle size significantly affects the continuity and uniformity of the fiber structure, and may even block the inner channels of the coaxial spinneret. Surface pretreatment with a silane coupling agent aims to convert the hydrophilic hydroxyl groups on the surface of the nano-titanium silicate zeolite into organic groups more compatible with the TPU matrix, thereby enhancing the interfacial bonding between the inorganic particles and the organic polymer. This treatment is crucial to prevent particles from detaching from the fiber interior during spinning or subsequent use; weak interfacial bonding will become mechanical defects and may block mass transfer micropores.

[0011] Strictly limiting the addition amount to 15%-30% of the thermoplastic polyurethane mass is crucial for balancing the reinforcing effect and process feasibility. Below this range, the reinforcing effect of nanoparticles on the fiber and the potential optimization of mass transfer pathways are not significant; while exceeding 30% significantly increases the viscosity of the spinning solution, making nanoparticles more prone to aggregation, leading to instability in the spinning process, uneven fiber diameter, and even fiber breakage. This optimal range ensures that the modifying effect of nanoparticles is maximized without excessively sacrificing the spinnability of the spinning solution and the quality of fiber formation, laying the foundation for the subsequent construction of core-sheath fibers with ideal mechanical properties and internal microstructure.

[0012] Preferably, in step (2), the amphiphilic block copolymer is a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer with a hydrophilic-lipophilic balance value of 12-18; in the mixed solvent, the mass ratio of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran is 6:1.8-2.2:1.8-2.2.

[0013] The use of polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymers with an HLB value of 12-18 is based on a precise match between their molecular structure and functional requirements. Within this range, the hydrophobic polypropylene glycol (PPO) mesoblocks possess sufficient length and proportion to achieve good thermodynamic compatibility with the thermoplastic polyurethane matrix through hydrophobic interactions and chain segment entanglement. This is a prerequisite for preventing phase separation during spinning solution storage or solvent evaporation and ensuring uniform fiber composition. Simultaneously, the hydrophilic polyethylene glycol (PEG) end chains possess sufficient proportion and migration ability to effectively accumulate on the fiber surface during fiber formation, providing the fiber with appropriate intrinsic hydrophilicity. HLB values ​​below 12 indicate insufficient PEG segment proportions and weak surface hydrophilic modification effects; values ​​above 18 indicate excessively short PPO segments, significantly reducing compatibility with thermoplastic polyurethane and potentially leading to unstable blends or spinning difficulties.

[0014] Preferably, in step (3), the process parameters for coaxial electrospinning are as follows: core spinning voltage: 18-22 kV, sheath spinning voltage: 16-20 kV, total spinning solution propulsion speed: 1.5-2.0 mL / h, wherein the flow rate ratio of the core spinning solution to the sheath spinning solution is 1:1-1.5, the vertical distance between the spinneret and the receiving device is 16-20 cm, the ambient temperature is controlled at 22-28℃, and the relative humidity is controlled at 45%-55%.

[0015] The dual-gradient voltage setting (18-22 kV for the core layer and 16-20 kV for the sheath layer) is the core driving force for forming a stable coaxial jet and a specific fiber morphology. Applying a voltage slightly higher than that to the sheath layer creates an outward electric field gradient between the inner and outer spinning solutions. This gradient helps overcome the interfacial tension between the two fluid layers, promoting a more stable and uniform flow of the sheath fluid around the core layer, and guiding the composite jet towards the receiving device for stable "whipping" stretching. If the voltage difference is too large, the jet whipping may be too violent or the sheath wrapping may be unstable; if the voltage is too low, the electric field force will be insufficient to fully stretch the jet, easily resulting in coarse fibers or droplets.

[0016] The overall propulsion velocity and the core-sheath flow rate ratio together determine the material output per unit time and the geometric characteristics of the core-sheath structure. A lower propulsion velocity ensures that the jet has sufficient time to be sufficiently stretched and refined under a given electric field, resulting in smaller diameter fibers, and allows for sufficient solvent evaporation, preventing fiber adhesion during reception. Setting the sheath flow rate to be equal to or slightly higher than the core flow rate provides sufficient sheath material to form a complete and continuous coating layer, preventing core material exposure. An imbalance in the ratio (such as an excessively high core flow rate) will directly lead to incomplete sheath coating, compromising the intended function of the core-sheath structure.

[0017] The receiving distance is a spatial parameter that balances fiber refinement, solvent evaporation, and deposition state. This distance needs to be long enough to allow the jet to undergo sufficient stretching and refinement in the electric field, and to allow most of the solvent to evaporate, ensuring that the fibers are deposited in a solid form. If the distance is too short, insufficient solvent evaporation can easily lead to fiber fusion and adhesion, and reduced porosity; if the distance is too long, the electric field strength weakens, the jet may become unstable, and the deposition efficiency will decrease.

[0018] Environmental temperature and humidity control are crucial for maintaining the repeatability of the entire physical process. Temperature primarily affects the solvent evaporation rate; relative humidity control is particularly critical. Excessive humidity can interfere with the dissipation of charge on the jet surface and may cause water vapor to condense on the jet surface, resulting in beaded defects or uneven diameters on the fiber surface. Insufficient humidity may cause the spinneret to become clogged or the jet to solidify prematurely due to excessive solvent evaporation, affecting fiber continuity.

[0019] Preferably, in step (4.1), the volume ratio of acetone to ethanol in the mixed organic solvent vapor is 6:4-8:2, and the relative humidity of the environment is controlled at 60%-75% during the vapor treatment process.

[0020] By utilizing the selective swelling and softening effect of solvent vapor on the fiber surface, adjacent fibers can be locally fused at the contact point, thereby significantly enhancing the bonding force between fibers and the overall structural integrity of the membrane without damaging the main morphology of the fiber body and the three-dimensional network pores.

[0021] The volume ratio of acetone to ethanol plays a decisive role here. Acetone is a good solvent for thermoplastic polyurethane, with strong dissolving and penetrating abilities, and is the main driving force for inducing the loosening, migration, and fusion of polymer segments on the fiber surface; while ethanol has a weaker dissolving ability for thermoplastic polyurethane and mainly acts as a regulator. When the ratio is biased towards acetone (e.g., 8:2), the fusion force of the vapor is strong and the treatment efficiency is high, but the risk of over-fusion increases, easily leading to excessive swelling, adhesion, or even local dissolution of fibers, resulting in a significant decrease in porosity and membrane brittleness. When the ratio is biased towards ethanol (e.g., 6:4), the treatment is more gentle and causes less damage to the pore structure, but there may be a risk of insufficient fusion strength. The preferred ratio is 6:4-8:2, which is a precise balance achieved between pursuing sufficient interfacial fusion strength and striving to maintain high porosity and fiber morphology. Exceeding this range will break this balance, either resulting in a loose and easily damaged membrane due to insufficient fusion, or pore collapse and a sharp drop in air permeability due to excessive fusion. Maintaining a relative humidity of 60%-75% is a crucial environmental parameter that works synergistically with solvent vapor. While water molecules themselves do not dissolve TPU, their presence significantly affects the condensation behavior, diffusion rate, and plasticizing effect of mixed solvent vapors on the fiber surface. In a moderately humid environment, water vapor competes with acetone and ethanol vapors for adsorption on the fiber surface. This competition creates a microscopic buffering mechanism: it moderately slows down the initial attack rate and local concentration of the strong solvent (acetone) on the thermoplastic polyurethane fiber surface, resulting in a smoother and more uniform swelling effect, thus preventing excessive fiber dissolution or morphological collapse due to excessively high local solvent concentrations. Simultaneously, this humidity range ensures sufficient water molecules to participate, promoting moderate condensation and spreading of solvent vapors on the fiber surface, while strictly avoiding excessive water vapor condensation that may occur at excessively high humidity levels (e.g., >75%). The presence of excessive liquid water can severely interfere with or even block the effective contact between solvent vapors and the polymer, leading to fusion process failure and potentially causing subsequent problems.

[0022] Preferably, in step (4.2), the high-porosity buffer pad is a silicone sponge or a non-woven polyester pad with a porosity greater than 90%.

[0023] Preferably, the low-temperature plasma or ultraviolet treatment time is 30-120 s; the chemical vapor deposition is carried out in a closed container, specifically under the following conditions: liquid perfluorooctyltriethoxysilane precursor is placed at the bottom of the container, and its amount is 0.05-0.2 mL / cm² relative to the gas-side surface area of ​​the fiber membrane substrate. 2 After the container containing the precursor and membrane is evacuated to a pressure ≤ 1000 Pa, it is sealed and then placed in an environment of 50-70℃ for deposition reaction, with a processing time of 60-180 minutes.

[0024] Surface activation modification can be performed using low-temperature plasma or ultraviolet (UV) treatment. Low-temperature plasma treatment is carried out in an oxygen or air atmosphere, with a treatment power of 50-300 W, a chamber pressure of 10-100 Pa, and a treatment time of 30-120 seconds. UV treatment uses UV light sources with dominant wavelengths of 184 nm and 254 nm, in an air or oxygen atmosphere, with a lamp intensity of 10-30 mW / cm². 2 The distance between the lamp and the membrane surface is 5-15 cm, and the processing time is 30-120 seconds.

[0025] Preferably, in step (6), the dopamine biomimetic coating treatment is performed by applying a dopamine Tris-HCl buffer solution with a concentration of 1.5-2.5 mg / mL at a coating amount of 2-3 g / mL. 2 The solution is coated onto the water-side surface and reacted at room temperature in the dark for 6-12 hours. The Tris-HCl buffer solution has a concentration of 8-12 mM and a pH of 8.2-8.8. The polyethyleneimine crosslinking treatment involves applying a polyethyleneimine aqueous solution with a concentration of 1.0-2.0 g / L, a pH of 8.5-9.0, and a molecular weight of 5000-10000 at a coating amount of 1-2 g / mM. 2 The coating is applied to a dopamine-treated surface and reacted at room temperature for 4-8 hours.

[0026] The present invention also discloses a high mass transfer efficiency MABR membrane, which is prepared by the above method.

[0027] The present invention also discloses an application of the high mass transfer efficiency MABR membrane, comprising the following steps: (a) Assembly and biofilm inoculation: The MABR membrane of claim 9 is assembled into a module and immersed in an inoculation solution with an activated sludge concentration of 2000-5000 mg / L, and soaked at 15-30℃ for 24-48 hours, during which the mixture is intermittently aerated or stirred; (b) Start-up and operation gas supply: The inoculated membrane module is placed in the main reactor of wastewater treatment, and oxygen-containing gas is introduced into the gas side of the membrane module to control the absolute pressure in the membrane cavity to 8-20 kPa; (c) Biofilm thickness control: The growth of biofilm on the membrane surface is controlled by performing physical flushing operations periodically.

[0028] Preferably, operational safety is ensured by: recording and maintaining a constant absolute pressure value inside the membrane cavity as described in step (b); monitoring and maintaining a constant water pressure at the immersion depth of the membrane module; and ensuring that the difference between the absolute pressure value inside the membrane cavity and the water pressure is always less than or equal to 50% of the measured value of the underwater bubble point pressure of the MABR membrane.

[0029] Preferably, the physical flushing operation is at least one of the following methods (1)-(3): Method (1) Hydraulic flushing: Perform high-intensity hydraulic circulation 1-2 times a day for 30-60 minutes each time, during which the liquid linear velocity on the membrane surface is not less than 0.25 m / s by increasing the power of the circulation pump; Method (2) Pneumatic burst flushing: Every 6-12 hours, increase the gas pressure supplied to the membrane chamber to 1.5-2.0 times the operating pressure in step (b) within 2 minutes, maintain the pressure for 3-5 minutes, and then restore it to the operating pressure; Method (3) Backwashing maintenance: Every 7-14 days of operation, remove the membrane module from the main reactor or lower the reactor liquid level below the membrane module, inject clean water or treated water in reverse from the liquid side interface of the membrane module, and at the same time introduce gas at a pressure of 5-10 kPa from the gas side for 10-20 minutes.

[0030] Compared with existing technologies, the advantages of this invention are as follows: 1. From a compositional perspective, this invention uses surface-modified nano-titanium silicate zeolite and hydrophobic thermoplastic polyurethane to form the core layer, which introduces reinforcing points while maintaining the hydrophobic continuous phase required for gas diffusion; the sheath layer is formed by thermoplastic polyurethane and amphiphilic block copolymers with specific hydrophilic-lipophilic balance values, providing a compatible and controllable substrate for subsequent modification. This material division of labor between the core and sheath layers decouples and optimizes the membrane's support and mass transfer functions and surface interface functions, essentially avoiding the mutual constraints between permeability, strength, and surface properties of a single homogeneous material.

[0031] 2. From a process perspective, this invention utilizes coaxial electrospinning to achieve in-situ one-time molding of core-sheath fibers, laying the structural foundation; subsequent controllable solvent vapor fusion and buffered hot pressing strengthen fiber connections, maintain the integrity and dimensional stability of the high-porosity network structure, and balance the contradiction between reinforcement and porosity preservation; finally, sequential surface modification with dopamine and polyethyleneimine constructs a robust hydrophilic coating on the complex fiber surface through chemical crosslinking. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The following will describe this application in detail with reference to the embodiments.

[0033] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0034] Unless otherwise specified, in the following examples and comparative examples, the surface-modified nano-titanium silicate zeolite was obtained by modifying nano-titanium silicate zeolite with an average particle size of 80-180 nm with silane coupling agent KH570: Nano-titanium silicate zeolite powder with an average particle size of 100 nm was dispersed in a mixed solvent of ethanol and water (volume ratio 9:1), and ultrasonically treated to form a uniform suspension; then, the pH of the suspension was adjusted to a weakly acidic environment of 4.5 with acetic acid, and KH570 equivalent to 4% of the zeolite mass was slowly added dropwise under continuous mechanical stirring, and the reaction was continued in a constant temperature water bath at 60°C for 6 hours; after the reaction was completed, the solid product was collected by centrifugation, and thoroughly washed with ethanol and deionized water in sequence to remove physically adsorbed impurities; finally, the washed product was vacuum dried at 80°C for 12 hours, and after grinding and sieving, the surface-modified nano-titanium silicate zeolite powder was obtained.

[0035] Example 1 A method for preparing a high mass transfer efficiency MABR membrane, comprising the following steps: (1) Preparing a core layer spinning solution: dissolving thermoplastic polyurethane in N,N-dimethylformamide to form a thermoplastic polyurethane solution with a mass fraction of 14%; adding 22.5% by mass of surface-modified nano-titanium silicate zeolite to the thermoplastic polyurethane solution, and obtaining a uniform and stable core layer spinning solution after ultrasonic dispersion; (2) Preparing a sheath layer spinning solution: mixing thermoplastic polyurethane with a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (Pluronic acid) with an HLB equilibrium value of 15. F127) was dissolved in a mixed solvent of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran in a mass ratio of 6:2:2 at a mass ratio of 7.5:2.5. The total mass fraction of the thermoplastic polyurethane and the amphiphilic block copolymer was 12% to obtain the sheath spinning solution; (3) Coaxial electrospinning: Using a coaxial electrospinning device, the core spinning solution obtained in step (1) was used as the inner spinning solution, and the sheath spinning solution obtained in step (2) was used as the outer spinning solution for spinning. The spinning process parameters were: core spinning voltage 20 kV, sheath spinning voltage 18 kV, total spinning solution propulsion speed 1.75 mL / h, wherein the flow rate ratio of the core spinning solution to the sheath spinning solution was 1:1.25, and the vertical distance between the spinneret and the receiving device was 18. cm, ambient temperature controlled at 25℃, relative humidity controlled at 50%, after spinning for 7 hours, it is collected on the receiving device to obtain the fiber membrane precursor; (4) Fiber membrane base membrane: (4.1) The fiber membrane precursor obtained in step (3) is placed in a mixed organic solvent vapor environment composed of acetone and ethanol with a volume ratio of 7:3 for steam treatment for 10 minutes, the temperature is 30℃, and the relative humidity is controlled at 67.5%; (4.2) The fiber membrane after step (4.1) is placed between two layers of silicone sponge with a porosity greater than 90%, and hot-pressed at 65℃ and 0.10 MPa for 15 minutes; then the pressure is released, and the fiber membrane base membrane is obtained by heat setting at 65℃ for 25 minutes; (5) Hydrophobic treatment of the gas side surface: The gas side surface of the fiber membrane base membrane obtained in step (4) is subjected to low-temperature plasma treatment in an oxygen atmosphere, the treatment power is 175 W, and the treatment chamber pressure is 55 Pa, processing time 75 seconds; followed by chemical vapor deposition, specifically: liquid perfluorooctyltriethoxysilane precursor placed at the bottom of the container, its amount relative to the gas-side surface area of ​​the fiber membrane substrate being 0.125 mL / cm². 2The container containing the precursor and membrane was pumped to a pressure of 500 Pa and sealed. It was then placed in an environment of 60°C for deposition reaction for 120 minutes to obtain an air-side modified fiber membrane. (6) Water-side hydrophilic modification: The air-side modified fiber membrane obtained in step (5) was flipped so that its water side was facing up. Dopamine biomimetic coating treatment and polyethyleneimine crosslinking treatment were performed in sequence to obtain a MABR rough membrane. The dopamine biomimetic coating treatment was performed by coating a 2.0 mg / mL dopamine Tris-HCl buffer solution (buffer concentration of 10 mM, pH value of 8.5) at a coating amount of 2.5 g / m. 2 The coating was applied to the water-side surface and reacted for 9 hours at room temperature in the dark. The polyethyleneimine crosslinking treatment was performed by applying a 1.5 g / L aqueous solution of polyethyleneimine with a pH of 8.75 and a molecular weight of 6000 at a coating amount of 1.5 g / m³. 2 The coating was applied to a dopamine-treated surface and reacted at room temperature for 6 hours; (7) Drying: The MABR rough membrane obtained in step (6) was vacuum dried at 45°C for 9 hours to obtain the high mass transfer efficiency MABR membrane.

[0036] Example 2 A method for preparing a high mass transfer efficiency MABR membrane, comprising the following steps: (1) Preparing the core layer spinning solution: dissolving thermoplastic polyurethane in N,N-dimethylformamide to form a thermoplastic polyurethane solution with a mass fraction of 12%; adding 15% by mass of surface-modified nano-titanium silicate zeolite to the thermoplastic polyurethane solution, and obtaining a uniform and stable core layer spinning solution after ultrasonic dispersion; (2) Preparing the sheath layer spinning solution: mixing thermoplastic polyurethane with a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (Pluronic acid) with an HLB equilibrium value of 12. F127) was dissolved in a mixed solvent of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran in a mass ratio of 6:1.8:1.8 at a mass ratio of 8:2. The total mass fraction of the thermoplastic polyurethane and the amphiphilic block copolymer was 10% to obtain the sheath spinning solution; (3) Coaxial electrospinning: Using a coaxial electrospinning device, the core spinning solution obtained in step (1) was used as the inner spinning solution and the sheath spinning solution obtained in step (2) was used as the outer spinning solution for spinning. The spinning process parameters were: core spinning voltage 18 kV, sheath spinning voltage 16 kV, total spinning solution feed speed 1.5 mL / h, wherein the flow rate ratio of the core spinning solution to the sheath spinning solution was 1:1, and the vertical distance between the spinneret and the receiving device was 16. cm, the ambient temperature is controlled at 22℃, the relative humidity is controlled at 45%, and the fiber is collected on the receiving device after 6 hours of spinning to obtain the fiber membrane precursor; (4) Fiber membrane base membrane: (4.1) The fiber membrane precursor obtained in step (3) is placed in a mixed organic solvent vapor environment composed of acetone and ethanol with a volume ratio of 6:4 for 5 minutes of steam treatment, the temperature is 25℃, and the relative humidity is controlled at 60%; (4.2) The fiber membrane after step (4.1) is placed between two layers of silicone sponge with a porosity greater than 90%, and hot-pressed at 60℃ and 0.05 MPa for 10 minutes; then the pressure is released, and the fiber membrane base membrane is obtained by heat setting at 60℃ for 20 minutes; (5) Hydrophobic treatment of the gas side surface: the gas side surface of the fiber membrane base membrane obtained in step (4) is subjected to ultraviolet treatment. In the air atmosphere, ultraviolet light sources with a main wavelength of 184 nm and 254 nm are used, and the lamp intensity is 10 mW / cm 2 The distance between the lamp and the membrane surface was 15 cm, and the treatment time was 30 seconds. Subsequently, chemical vapor deposition was performed under the following conditions: liquid perfluorooctyltriethoxysilane precursor was placed at the bottom of the container, and its amount relative to the gas-side surface area of ​​the fiber membrane substrate was 0.05 mL / cm². 2The container containing the precursor and membrane was pumped to a pressure of 1000 Pa and sealed. It was then placed in a 50°C environment for deposition reaction for 60 minutes to obtain an air-side modified fiber membrane. (6) Water-side hydrophilic modification: The air-side modified fiber membrane obtained in step (5) was flipped so that its water side faced upward. Dopamine biomimetic coating treatment and polyethyleneimine crosslinking treatment were performed in sequence to obtain a MABR rough membrane. The dopamine biomimetic coating treatment was performed by coating a 1.5 mg / mL dopamine Tris-HCl buffer solution (buffer concentration of 8 mM, pH value of 8.2) at a coating amount of 2.0 g / m. 2 The coating was applied to the water-side surface and reacted for 6 hours at room temperature in the dark. The polyethyleneimine crosslinking treatment involved applying a 1.0 g / L aqueous solution of polyethyleneimine with a pH of 8.5 and a molecular weight of 5000 at a coating amount of 1.0 g / m³. 2 Coated onto a dopamine-treated surface and reacted at room temperature for 4 hours; (7) Drying: The MABR rough membrane obtained in step (6) was vacuum dried at 40°C for 6 hours to obtain the high mass transfer efficiency MABR membrane.

[0037] Example 3 A method for preparing a high mass transfer efficiency MABR membrane, comprising the following steps: (1) Preparing a core layer spinning solution: dissolving thermoplastic polyurethane in N,N-dimethylformamide to form a thermoplastic polyurethane solution with a mass fraction of 16%; adding 30% by mass of surface-modified nano-titanium silicate zeolite to the thermoplastic polyurethane solution, and obtaining a uniform and stable core layer spinning solution after ultrasonic dispersion; (2) Preparing a sheath layer spinning solution: mixing thermoplastic polyurethane with a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (Pluronic acid) with an HLB equilibrium value of 18. F127) was dissolved in a mixed solvent of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran in a mass ratio of 6:2.2:2.2 at a mass ratio of 7:3. The total mass fraction of the thermoplastic polyurethane and the amphiphilic block copolymer was 14% to obtain the sheath spinning solution; (3) Coaxial electrospinning: using a coaxial electrospinning device, the core spinning solution obtained in step (1) was used as the inner spinning solution, and the sheath spinning solution obtained in step (2) was used as the outer spinning solution for spinning. The spinning process parameters were: core spinning voltage 22 kV, sheath spinning voltage 20 kV, total spinning solution propulsion speed 2.0 mL / h, wherein the flow rate ratio of the core spinning solution to the sheath spinning solution was 1:1.5, and the vertical distance between the spinneret and the receiving device was 20. cm, ambient temperature controlled at 28℃, relative humidity controlled at 55%, after spinning for 6 hours, it is collected on the receiving device to obtain the fiber membrane precursor; (4) Fiber membrane base membrane: (4.1) The fiber membrane precursor obtained in step (3) is placed in a mixed organic solvent vapor environment composed of acetone and ethanol with a volume ratio of 8:2 for steam treatment for 15 minutes, the temperature is 35℃, and the relative humidity is controlled at 75%; (4.2) The fiber membrane after step (4.1) is placed between two layers of silicone sponge with a porosity greater than 90%, and hot-pressed at 70℃ and 0.15 MPa for 20 minutes; then the pressure is released, and the fiber membrane base membrane is obtained by heat setting at 70℃ for 30 minutes; (5) Hydrophobic treatment of the gas side surface: The gas side surface of the fiber membrane base membrane obtained in step (4) is subjected to low-temperature plasma treatment in an oxygen atmosphere, the treatment power is 300 W, and the treatment chamber pressure is 100 Pa, processing time was 120 seconds; subsequently, chemical vapor deposition was performed under the following conditions: liquid perfluorooctyltriethoxysilane precursor was placed at the bottom of the container, and its amount was 0.2 mL / cm² relative to the gas-side surface area of ​​the fiber membrane substrate. 2The container containing the precursor and membrane was pumped to a pressure of 100 Pa and sealed. It was then placed in a 70°C environment for deposition reaction for 180 minutes to obtain an air-side modified fiber membrane. (6) Water-side hydrophilic modification: The air-side modified fiber membrane obtained in step (5) was flipped so that its water side was facing up. Dopamine biomimetic coating treatment and polyethyleneimine crosslinking treatment were performed in sequence to obtain a MABR rough membrane. The dopamine biomimetic coating treatment was performed by coating a 2.5 mg / mL dopamine Tris-HCl buffer (buffer concentration of 12 mM, pH value of 8.8) at a coating amount of 3.0 g / m. 2 The coating is applied to the water-side surface and reacted at room temperature in the dark for 12 hours. The polyethyleneimine crosslinking treatment is performed by applying a 2.0 g / L polyethyleneimine aqueous solution with a pH of 9.0 and a molecular weight of 10000 at a coating amount of 2.0 g / m³. 2 The coating is applied to the dopamine-treated surface and reacted at room temperature for 8 hours; (7) Drying: The MABR rough membrane obtained in step (6) is vacuum dried at 50°C for 12 hours to obtain the high mass transfer efficiency MABR membrane.

[0038] The difference between Comparative Example 1 and Example 1 is only in the following aspects: (1) Preparation of core spinning solution: thermoplastic polyurethane and polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (Pluronic F127) with an HLB equilibrium value of 12-18 are dissolved together in a mixed solvent of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran in a mass ratio of 6:2:2. The total mass fraction of the thermoplastic polyurethane and the amphiphilic block copolymer is 12%, and a sheath spinning solution is obtained; (2) Preparation of sheath spinning solution: thermoplastic polyurethane is dissolved in N,N-dimethylformamide to form a thermoplastic polyurethane solution with a mass fraction of 14%; 22.5% by mass of surface-modified nano-titanium silicate zeolite is added to the thermoplastic polyurethane solution, and after ultrasonic dispersion, a uniform and stable core spinning solution is obtained.

[0039] The only difference between Comparative Example 2 and Example 1 is that no surface-modified nano-titanium silicon zeolite was added to the core spinning solution.

[0040] The only difference between Comparative Example 3 and Example 1 is that the polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer was not added.

[0041] The only difference between Comparative Example 4 and Example 1 is that the amount of polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer added is 2:1.

[0042] The only difference between Comparative Example 5 and Example 1 is that the HLB value of the polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer is 20.

[0043] The only difference between Comparative Example 6 and Example 1 is that in step (4.1), the volume ratio of acetone to ethanol in the mixed organic solvent vapor is 6:5.

[0044] The only difference between Comparative Example 7 and Example 1 is that in step (4.1), the volume ratio of acetone to ethanol in the mixed organic solvent vapor is 6:1.

[0045] The only difference between Comparative Example 8 and Example 1 is that in step (4.1), the relative humidity is controlled at 50%.

[0046] The only difference between Comparative Example 9 and Example 1 is that in step (4.1), the relative humidity is controlled at 80%.

[0047] The only difference between Comparative Example 10 and Example 1 is that in step (4.2), hot pressing is performed for 10 minutes at 75°C and 0.18 MPa.

[0048] The only difference between Comparative Example 11 and Example 1 is that in step (5), the ratio of the liquid perfluorooctyltriethoxysilane precursor to the gas-side surface area of ​​the fiber membrane substrate is 0.3 mL / cm². 2 .

[0049] The only difference between Comparative Example 12 and Example 1 is that in step (6), the polyethyleneimine aqueous solution was not used.

[0050] Performance testing: Porosity: The overall porosity was measured using a porosimeter (target 65%-75%); Mechanical properties: Using a universal testing machine, the tensile strength, elongation at break, and Young's modulus in both dry and wet conditions were measured according to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets". The durability in a water-containing environment was evaluated with a focus on the following (target: wet tensile strength ≥ 5.0 MPa, elongation at break ≥ 150%).

[0051] Bubble point pressure: Using a bubble point pressure gauge, refer to ASTM F316-03 standard to determine the bubble point pressure of the membrane underwater (to verify its water ingress prevention capability, target 15-30 kPa).

[0052] Oxygen mass transfer coefficient (KLa): In deionized water, using online dissolved oxygen monitoring, air or oxygen is introduced into the membrane cavity, and the KLa value is calculated by measuring the change curve of dissolved oxygen in the liquid phase over time (target 0.8-1.2 h). -1 ).

[0053] Gas permeability and selectivity factor: Using a gas permeameter, the permeation flux of the membrane to pure oxygen and pure nitrogen was measured under dry conditions, and the ideal separation factor of oxygen / nitrogen was calculated (target 2.8-3.8).

[0054] Surface hydrophilicity: The static water contact angle of the membrane surface was measured using a contact angle meter (target <70°).

[0055] Table 1 Test Results of Examples and Comparative Examples

[0056] Examples 1-3 utilize coaxial electrospinning technology to prepare composite fibers with both a hydrophobic reinforcing core layer and a hydrophilic functional sheath layer in a single process, providing a stable structural foundation for the membrane. Subsequent controlled solvent vapor treatment combined with buffered hot-pressing ensures strong connections between the fibers, significantly improving the overall strength and durability of the membrane while maintaining a high porosity structure that facilitates gas diffusion. In subsequent processes, asymmetric surface modification of both sides of the base membrane—superhydrophobic and superhydrophilic—achieves an ideal state of efficient water blocking and oxygen mass transfer on the gas side, and stable adhesion promotion on the water side. Therefore, the MABR membrane prepared in this invention comprehensively achieves high permeability, good mechanical properties, suitable hydrophilicity, and long-term operational stability.

[0057] Comparative Example 1 completely reversed the material composition of the core and sheath layers, resulting in the simultaneous loss of the membrane's mechanical framework, gas selectivity, and asymmetric interface function. Comparative Example 2, without the addition of nanoparticles to the core layer, directly demonstrated its crucial reinforcing role in improving the wet strength of the fiber network; the absence of this role reduced the membrane's structural stability in aqueous environments. Comparative Example 3, without the introduction of amphiphilic block copolymers into the sheath layer, resulted in the spun fiber surface being entirely dominated by hydrophobic thermoplastic polyurethane. This made it difficult for the subsequent aqueous dopamine coating treatment solution to uniformly wet and spread, failing to construct a complete and robust superhydrophilic interface. This confirmed that a moderately intrinsically hydrophilic sheath layer is an indispensable substrate for successful subsequent water-side precision modification. Comparative Examples 4 and 5, respectively, altered the proportion of amphiphilic copolymers and their hydrophilic-lipophilic balance values. The results showed that once the compatibility between the copolymer and the matrix or its enrichment state on the surface is disrupted, it directly affects the uniformity and surface energy of the sheath layer, ultimately impairing the effect and uniformity of water-side hydrophilic modification. Comparative Examples 6 and 7, by altering the ratio of acetone to ethanol in the solvent vapor, revealed the consequences of disrupting the delicate balance between inducing fiber fusion to enhance strength and avoiding over-dissolution to maintain pore size: insufficient acetone resulted in inadequate fusion strength, while excessive acetone led to pore structure collapse. Comparative Examples 8 and 9 showed that ambient relative humidity is a key synergistic factor for the uniform and gentle action of solvent vapor on the fiber surface; deviations from the preferred range resulted in uneven fusion, thus weakening the overall integrity of the membrane. Comparative Example 10 used excessively high temperature and pressure for hot-pressing, demonstrating that overly aggressive processes irreversibly compress the pore space of the fiber network, severely sacrificing the fundamental requirement of high membrane permeability. Comparative Example 11 used excessive amounts of fluorosilane precursors for vapor deposition, indicating that even surface modification requires precise control; excessive deposition, while potentially improving apparent hydrophobicity, can partially block gas mass transfer channels due to excessive coating thickness, leading to decreased oxygen mass transfer efficiency. Comparative Example 12 omitted the polyethyleneimine crosslinking step, and its results confirmed that this step is crucial for locking the dopamine coating and forming a crosslinked network to maintain the chemical and mechanical stability of the hydrophilic interface in a long-term aqueous environment. In summary, each comparative example serves as a set of control experiments, clearly and powerfully demonstrating that every material selection, every process step, and its parameter range defined in the claims of this invention is an indispensable part of the complete technical solution for this high-performance asymmetric MABR membrane.

[0058] Application Example 1: An application of the high mass transfer efficiency MABR membrane described above includes the following steps: (a) Assembly and biofilm inoculation: The MABR membrane prepared in Example 1 is assembled into a module and immersed in an inoculation solution with an activated sludge concentration of 4000 mg / L. The module is soaked at 25°C for 24 hours, during which the mixture is intermittently aerated or stirred at low intensity; (b) Start-up and gas supply: The inoculated membrane module is placed in the main wastewater treatment reactor, and oxygen-containing gas is introduced to the gas side of the membrane module, controlling the absolute pressure inside the membrane chamber to 15 kPa; Operational safety is ensured by: recording and maintaining a constant absolute pressure value inside the membrane chamber as described in step (b); monitoring and maintaining a constant water pressure at the immersion depth of the membrane module; ensuring that the difference between the absolute pressure value inside the membrane chamber and the water pressure is always less than or equal to 50% of the measured underwater bubble point pressure of the MABR membrane; (c) Biofilm thickness control: Biofilm growth on the membrane surface is controlled by performing physical flushing operations periodically; physical flushing operations are backwashing maintenance: every 10 days of operation, the membrane module is removed from the main reactor or the reactor liquid level is lowered below the membrane module, and clean water or treated water is injected in reverse from the liquid side interface of the membrane module, while gas at a pressure of 8 kPa is introduced from the gas side for 20 minutes.

[0059] Application Example 2: An application of the aforementioned high mass transfer efficiency MABR membrane includes the following steps: (a) Assembly and biofilm inoculation: The commercially available MABR membrane is assembled into a module and immersed in an inoculum solution with an activated sludge concentration of 4000 mg / L. The membrane is soaked at 25°C for 24 hours, during which the mixture is intermittently aerated or stirred at low intensity. Performance indicators of the commercially available MABR membrane: The parameters of the commercially available membrane can be set as follows: porosity 65%, wet tensile strength 3.0 MPa, bubble point pressure 12 kPa, KLa 0.4 h⁻¹ -1 The contact angle is 80°.

[0060] (b) Start-up and gas supply: Place the inoculated membrane module in the main wastewater treatment reactor, introduce oxygen-containing gas into the gas side of the membrane module, and control the absolute pressure inside the membrane chamber to 15 kPa; ensure operational safety by: recording and maintaining the absolute pressure value inside the membrane chamber as described in step (b); monitoring and maintaining the water pressure at the immersion depth of the membrane module to be constant; ensuring that the difference between the absolute pressure value inside the membrane chamber and the water pressure is always less than or equal to 50% of the measured value of the underwater bubble point pressure of the MABR membrane; (c) Biofilm thickness control: control the growth of biofilm on the membrane surface by performing physical flushing operations periodically; physical flushing operation is backwashing maintenance: every 10 days of operation, remove the membrane module from the main reactor or lower the reactor liquid level below the membrane module, inject clean water or treated effluent in reverse from the liquid side interface of the membrane module, and at the same time introduce gas at a pressure of 8 kPa from the gas side for 20 minutes.

[0061] The only difference between Application Example 3 and Application Example 1 is that it operates at a lower absolute pressure within the membrane cavity (8 kPa).

[0062] The key performance comparisons of the above application examples 1-3 after 30 days of continuous and stable operation under the same baseline sewage (simulated domestic sewage, initial COD≈350 mg / L, ammonia nitrogen≈40 mg / L, total nitrogen≈50 mg / L) are shown in Table 2.

[0063] Table 2 Comparison of key performance indicators after 30 days of continuous and stable operation in Application Examples 1-3

[0064] Commercially available membranes often sacrifice porosity and permeability to ensure sufficient mechanical strength, or use fragile structures to pursue high permeability. This invention achieves in-situ composite of a hydrophobic reinforcing core and a hydrophilic functional sheath through coaxial electrospinning of core-sheath fibers. This structure allows the core layer to focus on building a rigid gas channel with high porosity, while the sheath layer is independently optimized as an ideal biofilm attachment interface, avoiding performance compromises from the outset. Commercially available membranes are either structurally loose due to insufficient fusion, or suffer from pore collapse due to improper high temperature and pressure during post-processing. This invention uses controlled solvent vapor-induced fusion, achieving welding only at fiber contact points, followed by gentle hot pressing under the protection of buffer pads. This significantly improves the membrane's overall integrity and wet mechanical strength while perfectly preserving the high-porosity network. This allows the membrane of this invention to maintain structural integrity under actual hydraulic impact and maintain efficient gas diffusion paths over a long period. The surface modification layer of commercially available membranes often gradually detaches during operation due to weak physical bonding, leading to decreased hydrophilicity and uneven biofilm attachment. This invention constructs a stable, covalently cross-linked biomimetic coating on the surface of complex fibers through a sequential reaction of dopamine and polyethyleneimine. This not only provides a durable and uniform hydrophilic surface, promoting rapid and uniform biofilm formation in the initial stage, but more importantly, it ensures the stability of the membrane surface properties throughout the entire operating cycle, thereby avoiding abnormal biofilm proliferation, local detachment, and fluctuations in mass transfer efficiency caused by coating failure.

[0065] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary; within the framework of this invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0066] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a high mass transfer efficiency MABR membrane, characterized in that, Includes the following steps: (1) Preparation of core spinning solution: Thermoplastic polyurethane is dissolved in N,N-dimethylformamide to form a thermoplastic polyurethane solution with a mass fraction of 12%-16%; surface-modified nano-titanium silicate zeolite is added to the thermoplastic polyurethane solution, and after ultrasonic dispersion, a uniform and stable core spinning solution is obtained; (2) Preparation of sheath spinning solution: Thermoplastic polyurethane and amphiphilic block copolymer are dissolved together in a mixed solvent of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran at a mass ratio of 8:2-7:3, and the total mass fraction of the thermoplastic polyurethane and amphiphilic block copolymer is 10%-14%, to obtain the sheath spinning solution. (3) Coaxial electrospinning: Using a coaxial electrospinning device, the core spinning solution obtained in step (1) is used as the inner spinning solution, and the sheath spinning solution obtained in step (2) is used as the outer spinning solution. Spinning is performed and the solution is collected on the receiving device to obtain the fiber membrane precursor; (4) Fiber membrane base membrane: (4.1) The fiber membrane precursor obtained in step (3) is placed in a mixed organic solvent vapor environment composed of acetone and ethanol for steam treatment for 5-15 minutes at a temperature of 25-35℃; (4.2) The fiber membrane treated in step (4.1) is placed between two layers of high porosity buffer pads and hot-pressed at 60-70℃ and 0.05-0.15 MPa for 10-20 minutes; Then release the pressure and heat-set at 60-70℃ for 20-30 minutes to obtain the fiber membrane base film; (5) Hydrophobication of the gas side surface: the gas side surface of the fiber membrane base film obtained in step (4) is subjected to low temperature plasma or ultraviolet treatment, followed by chemical vapor deposition to obtain the gas side modified fiber membrane; (6) Hydrophilic modification of the water side: the gas side modified fiber membrane obtained in step (5) is flipped so that its water side faces upward, and dopamine biomimetic coating treatment and polyethyleneimine crosslinking treatment are performed in sequence to obtain the MABR rough film; (7) Drying: the rough film is vacuum dried at 40-50℃ to obtain the high mass transfer efficiency MABR membrane.

2. The method for preparing a high mass transfer efficiency MABR membrane according to claim 1, characterized in that, In step (1), the surface-modified nano-titanium silicate zeolite is obtained by treating nano-titanium silicate zeolite with an average particle size of 80-180nm with a silane coupling agent; the amount of nano-titanium silicate zeolite added is 15%-30% of the mass of thermoplastic polyurethane.

3. The method for preparing a high mass transfer efficiency MABR membrane according to claim 1, characterized in that, In step (2), the amphiphilic block copolymer is a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer with a hydrophilic-lipophilic balance value of 12-18; in the mixed solvent, the mass ratio of N,N-dimethylformamide, N-methylpyrrolidone and tetrahydrofuran is 6:1.8-2.2:1.8-2.

2.

4. The method for preparing a high mass transfer efficiency MABR membrane according to claim 1, characterized in that, In step (3), the process parameters for coaxial electrospinning are as follows: core spinning voltage: 18-22 kV, sheath spinning voltage: 16-20 kV, total spinning solution propulsion speed: 1.5-2.0 mL / h, wherein the flow rate ratio of the core spinning solution to the sheath spinning solution is 1:1-1.5, the vertical distance between the spinneret and the receiving device is 16-20 cm, the ambient temperature is controlled at 22-28℃, and the relative humidity is controlled at 45%-55%.

5. The method for preparing a high mass transfer efficiency MABR membrane according to claim 1, characterized in that, In step (4.1), the volume ratio of acetone to ethanol in the mixed organic solvent vapor is 6:4-8:2, and the relative humidity of the environment is controlled at 60%-75% during the vapor treatment process.

6. The method for preparing a high mass transfer efficiency MABR membrane according to claim 1, characterized in that, In step (4.2), the high porosity buffer pad is a silicone sponge with a porosity greater than 90%.

7. The method for preparing a high mass transfer efficiency MABR membrane according to claim 1, characterized in that, In step (5), the low-temperature plasma or ultraviolet treatment time is 30-120 s; the chemical vapor deposition is carried out in a closed container under the following conditions: liquid perfluorooctyltriethoxysilane precursor is placed at the bottom of the container, and its amount is 0.05-0.2 mL / cm² relative to the gas-side surface area of ​​the fiber membrane substrate. 2 After the container containing the precursor and membrane is evacuated to a pressure ≤ 1000 Pa, it is sealed and then placed in an environment of 50-70℃ for deposition reaction, with a processing time of 60-180 minutes.

8. The method for preparing a high mass transfer efficiency MABR membrane according to claim 1, characterized in that, In step (6), the dopamine biomimetic coating treatment is as follows: applying a dopamine Tris-HCl buffer solution with a concentration of 1.5-2.5 mg / mL at a coating amount of 2-3 g / mL. 2 The solution is coated onto the water-side surface and reacted at room temperature in the dark for 6-12 hours. The Tris-HCl buffer solution has a concentration of 8-12 mM and a pH of 8.2-8.

8. The polyethyleneimine crosslinking treatment involves applying a polyethyleneimine aqueous solution with a concentration of 1.0-2.0 g / L, a pH of 8.5-9.0, and a molecular weight of 5000-10000 at a coating amount of 1-2 g / mM. 2 The coating is applied to a dopamine-treated surface and reacted at room temperature for 4-8 hours.

9. A high mass transfer efficiency MABR membrane, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. An application of a high mass transfer efficiency MABR membrane, characterized in that, Includes the following steps: (a) Assembly and biofilm inoculation: Assemble the high mass transfer efficiency MABR membrane of claim 9 into a module and immerse it in an inoculation solution with an activated sludge concentration of 2000-5000 mg / L. Soak it at 15-30°C for 24-48 hours. During the soaking period, intermittently aerate or stir the mixture. (b) Start-up and operation gas supply: Place the inoculated membrane module in the main wastewater treatment reactor and introduce oxygen-containing gas into the gas side of the membrane module to control the absolute pressure in the membrane cavity to 8-20 kPa. (c) Biofilm thickness control: Control the growth of biofilm on the membrane surface by performing physical flushing operations periodically.

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