A high uniformity nanofiltration membrane for purifying deer horn peptide

Abstract

The patent relates to a composite nanofiltration membrane for the fractional separation of amino acids, oligopeptides and polypeptides in deer antler hydrolysate, used for the purification of deer antler peptides. The method comprises the following steps: first, add polyacrylonitrile powder in an organic solvent and heat and stir to form polyacrylonitrile solution A; then, prepare a nanofiber membrane by electrospinning technology with polyacrylonitrile solution A, and then add NaOH solution for modification treatment. Next, dissolve the modified polyacrylonitrile membrane and perform ultrasonic treatment; add functional nanoparticles and surfactants to the treated solution to form polyacrylonitrile solution B; again prepare a nanofiber membrane by electrospinning technology to obtain a preliminary shaped polyacrylonitrile membrane; finally, pour piperazine (PIP) aqueous solution and trimesoyl chloride (TMC) n-hexane solution for interfacial polymerization reaction, wash and dry the treated polyacrylonitrile membrane, and finally obtain the composite nanofiltration membrane. This technical innovation will help to improve the yield of deer antler peptides in deer antler hydrolysate, optimize the performance of the membrane, expand the application prospect in the field of purification of biologically active substances, and has important practical value and market potential.

Description

Technical Field

[0001] This invention relates to the field of membrane science and technology, and in particular to a method for preparing a composite nanofiltration membrane for the efficient and precise separation of amino acids, oligopeptides and polypeptides from deer antler hydrolysates. Background Technology

[0002] Amino acids are the basic building blocks of proteins, containing amino and carboxyl groups. Oligopeptides consist of 2-20 amino acids linked by peptide bonds, while polypeptides are composed of even more amino acids. Amino acids form peptide bonds through dehydration condensation reactions, linking together to form dipeptides, and gradually forming oligopeptides and polypeptides. Structurally, oligopeptides and polypeptides are based on amino acids, with peptide bonds connecting each amino acid. Functionally, amino acids participate in metabolic regulation, oligopeptides can act as signaling molecules, and polypeptides perform more complex functions, such as insulin regulating blood glucose. They are closely interconnected; from amino acids to oligopeptides and then to polypeptides, the structure gradually becomes more complex, and the functions continuously expand.

[0003] Deer antler peptides are bioactive substances extracted from deer antlers and are one of the important active ingredients in deer antlers. Deer antler peptides are typically small molecule peptides composed of multiple amino acids, possessing various physiological activities, such as enhancing immunity, promoting tissue repair and regeneration, and contributing to bone health. Given their unique efficacy, deer antler peptides have broad application prospects in the fields of medicine and health products. Currently, the main methods for preparing deer antler peptides include enzymatic hydrolysis and lysis buffer methods, with enzymatic hydrolysis being one of the commonly used methods. Since the peptides in deer antler hydrolysate vary in size, containing oligopeptides and polypeptides with molecular weights between 180-1000 Daltons and 1000-5000 Daltons, respectively, these peptide molecules may be composed of 2-10 amino acids and 10-50 amino acids. The type of enzyme used, the hydrolysis time, and the temperature during the deer antler hydrolysis process have a significant impact on the peptide size. Membrane separation for preparing deer antler peptides offers high separation precision and mild separation conditions, which helps improve product quality and medicinal value, and can maximize the retention of the active ingredients of deer antler peptides.

[0004] The core technology of this invention lies in utilizing a nanofiltration membrane with high uniformity to purify antler peptides, thereby achieving precise separation of antler peptides with different molecular weights. By redissolving the spun nanofiber membrane for re-film formation, the pore size of the membrane can be made more uniform and precise, thus allowing for more accurate control of the membrane thickness. The advantage of this technological innovation lies in improving the separation accuracy of antler peptides, enhancing membrane uniformity, and overcoming the shortcomings of traditional membrane materials, such as low pore size and thickness uniformity and inability to adapt to environmental changes. This technology is expected to bring about a significant revolution in the field of antler peptide production, improving product quality and processing efficiency, expanding the application range of antler peptides, and possessing broad market prospects and economic benefits. Summary of the Invention

[0005] To address the complexities of fractionating amino acids, oligopeptides, and polypeptides, this invention provides a method for preparing a hydrophilic nanofiltration composite membrane for fractionating amino acids, oligopeptides, and polypeptides. The method is characterized by hydrophilic modification of the polyacrylonitrile membrane through adjusting the spinning solution ratio and using an alkaline solution. Simultaneously, ultrasonic treatment optimizes the dispersibility of the polyacrylonitrile solution to better dissolve functional particles. A surfactant is added to reduce the surface tension of the solution. The redissolved nanofiber membrane solution is then spun. The resulting polyacrylonitrile membrane exhibits higher structural uniformity and mechanical strength, enhancing its physical properties. The electrospun polyacrylonitrile membrane containing titanium dioxide nanoparticles can be used to prepare antibacterial materials, such as medical supplies and food packaging materials, reducing bacterial growth and improving its resistance to environmental impacts, making it more suitable for demanding applications. Furthermore, it improves the hydrophilicity and antifouling properties of the polyacrylonitrile membrane, provides more controllable water flux, and retains a good rejection rate for polypeptides.

[0006] The purpose of this invention is to provide a method for preparing a highly uniform nanofiltration membrane for purifying deer antler peptides.

[0007] 1. The method for preparing the composite nanofiltration membrane of the present invention includes the following key steps:

[0008] Polyacrylonitrile powder is added to one or more organic solvents and heated and stirred until completely dissolved to form polyacrylonitrile solution A. Polyacrylonitrile solution A is then electrospinned to form a nanofiber membrane, creating a uniform nanofiber network structure. After the nanofiber membrane is prepared, NaOH is added for modification. The modified polyacrylonitrile nanofiber membrane is dissolved, and the resulting solution is ultrasonically treated. Titanium dioxide nanoparticles are added to the ultrasonically treated polyacrylonitrile solution A, along with the surfactant sodium dodecyl sulfate (SDS), and the mixture is stirred thoroughly to form polyacrylonitrile solution B. Polyacrylonitrile solution B is then electrospinned to form a membrane. The membrane is dried under constant temperature conditions to obtain a pre-formed polyacrylonitrile membrane. An interfacial polymerization reaction is carried out on the membrane using a PIP aqueous solution and a TMC n-hexane solution. The interfacially treated polyacrylonitrile membrane is cleaned to remove residual reagents and then dried to obtain the final composite nanofiltration membrane.

[0009] 2. As a further preferred embodiment of the present invention, in the step of forming polyacrylonitrile solution A, the ratio of polyacrylonitrile powder to organic solvent is 8-12 g / 100 ml; the organic solvent is one or more of DMF, DMAc, methanol or butanol; the stirring time is 20-30 minutes, the heating temperature is 80-90°C, the stirring speed is 300-500 rpm, the stirring time is 2-3 hours, and the formed polyacrylonitrile solution A is cooled to room temperature and stirred for another 10-15 minutes.

[0010] 3. As a further preferred embodiment of the present invention, in the step of forming a nanofiber membrane from polyacrylonitrile solution A by electrospinning, polyacrylonitrile solution A is loaded into a syringe, the needle diameter of the syringe is selected to be 0.2-0.5 mm; the spinning voltage is 15-25 kV; the injection rate is 0.5-1.5 mL / h; and the spinning distance is 10-20 cm.

[0011] 4. As a further preferred embodiment of the present invention, in the step of adding NaOH for modification, the NaOH alkaline solution is 1 mol / L, the stirring time is 2 hours, and the temperature is 60°C;

[0012] 5. As a further preferred embodiment of the present invention, in the step of dissolving the modified polyacrylonitrile nanofiber membrane, the ratio of the modified nanofiber membrane to the organic solvent is 10-15 g / 100 mL; the heating temperature is 80-90 ℃, the stirring speed is 300-500 rpm, the stirring time is 1-2 hours, and after cooling to room temperature, stirring is continued for 10-15 minutes.

[0013] 6. As a further preferred embodiment of the present invention, in the step of ultrasonic treatment of the dissolved solution, the dissolved solution is placed in the container of the ultrasonic treatment device, ensuring that the liquid level does not exceed two-thirds of the container; the frequency of the ultrasonic treatment device is 20-40 kHz, and the power is 200-400 watts; the treatment time is 10-20 minutes; during the treatment, the solution temperature is maintained at 30-40°C; a magnetic stirrer is used to initially stir at a stirring speed of 200-400 rpm for 10-15 minutes; then the solution is transferred to a high-speed stirring device and stirred at a stirring speed of 1000-1500 rpm for 30-45 minutes; after stirring, the solution is allowed to stand for 5-10 minutes.

[0014] 7. As a further preferred embodiment of the present invention, in the step of forming polyacrylonitrile solution B, the proportion of titanium dioxide nanoparticles added is 0.5-1 wt%; the proportion of SDS added is 1-2 wt%.

[0015] 8. As a further preferred embodiment of the present invention, the temperature of the constant temperature drying oven is set to 45-55°C; the drying time is 10-15 minutes.

[0016] 9. As a further preferred embodiment of the present invention, in the interfacial polymerization reaction step, the mass concentration of the PIP solution is 0.025–0.125 wt%. The wetting time for the polyacrylonitrile nanofiber membrane is 2–3 minutes.

[0017] 10. As a further preferred embodiment of the present invention, in the interfacial polymerization reaction step, the mass fraction of the TMC n-hexane solution is 0.1-0.2 wt%, the amount added is 2 mL, and the interfacial polymerization time is 20-60 seconds.

[0018] 11. As a further preferred embodiment of the present invention, in the cleaning and drying steps, the polyacrylonitrile membrane after interface treatment is rinsed with deionized water 3 to 4 times, then soaked for 12 to 15 hours to remove residual reagents, and then dried at room temperature for more than 12 hours.

[0019] This invention provides a method for preparing a highly uniform nanofiltration membrane for purifying deer antler peptides, wherein the highly uniform nanofiltration membrane has a peptide rejection rate of 90%.

[0020] The beneficial effects of this invention are:

[0021] 1. The beneficial effects of this patent lie in the combination of ultrasonic treatment, the addition of nanoparticles and surfactants, and electrospinning technology, which significantly improves the uniformity and antifouling performance of polyacrylonitrile membranes. This innovative technology not only enhances the adhesion between the separation layer and the base membrane, but also improves the integrity of the separation layer, enhances its performance stability, and optimizes its microstructure.

[0022] 2. By dissolving the spun nanofiber membrane, the polyacrylonitrile molecules constituting the membrane are uniformly dispersed in the solvent. During the re-film formation process, by controlling the film formation conditions, these molecules are rearranged and redistributed, avoiding local aggregation or uneven distribution, eliminating original defects and inhomogeneities, and allowing for more precise control of the final membrane thickness. Under suitable temperature and concentration conditions, the disordered state transforms into an ordered membrane phase, resulting in a more uniform formed membrane, enhanced adhesion between the separation layer and the base membrane, and improved resistance to environmental influences, making it more suitable for harsh application environments.

[0023] This method has relatively low implementation costs, simple processes, and is suitable for large-scale industrial production. It provides a more efficient, economical, and environmentally friendly new approach for the preparation of polyacrylonitrile membranes, and has high practical value and broad market potential. Detailed Implementation

[0024] The technical solutions of the present invention are further illustrated below with reference to specific embodiments. These embodiments should not be construed as limiting the technical solutions.

[0025] Example 1

[0026] 8g of polyacrylonitrile powder was added to 100mL of DMF organic solvent and stirred at 85℃ and 400rpm for 2.5 hours to form polyacrylonitrile solution A. The solution was then cooled to room temperature and stirred for another 12 minutes. Polyacrylonitrile solution A was loaded into a syringe with a needle diameter of 0.3mm, and nanofiber membranes were fabricated by electrospinning at a spinning voltage of 20kV, an injection rate of 1mL / h, and a spinning distance of 15cm. The nanofiber membranes were then placed in a 1mol / L NaOH alkaline solution and stirred at 60℃ for 2 hours for modification. The modified nanofiber membranes were redissolved in DMF at a ratio of 12wt%, stirred at 85℃ and 400rpm for 1.5 hours, cooled to room temperature, and stirred for another 12 minutes. The dissolved solution was placed in an ultrasonic treatment device (frequency 30kHz, power 300W) and treated at 35℃ for 15 minutes, while simultaneously being initially stirred with a magnetic stirrer at 300rpm for 12 minutes. Then, it was transferred to a high-speed stirrer and stirred at 1200rpm for 40 minutes, followed by standing for 8 minutes to obtain the treated polyacrylonitrile solution A. 0.8wt% titanium dioxide nanoparticles and 1.5wt% SDS were added to this solution and stirred thoroughly to form polyacrylonitrile solution B. A membrane was then formed using electrospinning technology and dried in a constant-temperature drying oven at 50℃ for 12 minutes to obtain a pre-formed polyacrylonitrile membrane. The membrane was then immersed in a 0.05wt% PIP aqueous solution for 2.5 minutes, followed by the dropwise addition of 2 mL of a 0.15wt% TMC n-hexane solution. The interfacial polymerization time was 40 s. Finally, the membrane was rinsed three times with deionized water and soaked for 13 hours to remove residual reagents. It was then dried at room temperature for 13 hours to obtain the composite nanofiltration membrane.

[0027] Pore ​​size uniformity: The pore size distribution of the membrane was measured by mercury intrusion porosimetry. The coefficient of variation of the pore size was 9%, and the ratio of the maximum pore size to the minimum pore size was 1.35.

[0028] Thickness uniformity: The thickness was measured using laser interferometry. The film surface was divided into 1cm×1cm squares, and 100 points were measured. The thickness deviation rate was ±3.5%, and the standard deviation of the thickness was 6 nm.

[0029] Purification effect of deer antler peptides: The separation efficiency of deer antler peptides with a molecular weight of more than 1000 Da reached 90%, the yield was 85%, and the throughput was 50 L / (m²・h).

[0030] Example 2

[0031] 8g of polyacrylonitrile powder was added to 100mL of DMF organic solvent and stirred at 300rpm for 3 hours at 80℃ to form polyacrylonitrile solution A. The solution was cooled to room temperature and stirred for another 15 minutes. The mixture was then placed in an ultrasonic treatment device (frequency 20kHz, power 200W) and treated at 30℃ for 20 minutes, while simultaneously being initially stirred at 200rpm for 15 minutes with a magnetic stirrer. The mixture was then transferred to a high-speed stirrer and stirred at 1000rpm for 45 minutes. After standing for 10 minutes, the treated polyacrylonitrile solution A was obtained. 0.5wt% titanium dioxide nanoparticles and 1wt% SDS were added to this solution and stirred thoroughly to form polyacrylonitrile solution B. This solution was then used to form a film using electrospinning technology and dried in a constant temperature drying oven at 45℃ for 15 minutes to obtain a pre-formed polyacrylonitrile film. The membrane was immersed in a 0.025 wt% PIP aqueous solution for 3 min, then 2 mL of a 0.1 wt% TMC n-hexane solution was added dropwise. The interfacial polymerization time was 60 seconds. Finally, the membrane was rinsed 4 times with deionized water and soaked for 15 hours to remove residual reagents. The membrane was then dried at room temperature for 15 hours to obtain the final composite nanofiltration membrane.

[0032] Pore ​​size uniformity: Measured by mercury porosimetry, the pore size variation coefficient is 20%, and the ratio of the maximum pore size to the minimum pore size is 1.9.

[0033] Thickness uniformity: Using laser interferometry, 100 points were measured according to the above grid. The thickness deviation rate was ±9%, and the standard deviation of the thickness was 15 nm.

[0034] Purification effect of deer antler peptide: For the separation of deer antler peptide with a molecular weight of 1800 Da or above, the separation efficiency is 88%, the yield is 82%, and the throughput is 35 L / (m²・h).

[0035] Example 3

[0036] 8g of polyacrylonitrile powder was added to 80mL of methanol organic solvent and stirred at 500rpm for 2 hours at 90℃ to form polyacrylonitrile solution A. The solution was cooled to room temperature and stirred for another 10 minutes. Polyacrylonitrile solution A was then loaded into a syringe with a needle diameter of 0.5mm, and nanofiber membranes were fabricated by electrospinning at a spinning voltage of 25kV, an injection rate of 1.5mL / h, and a spinning distance of 20cm. The nanofiber membranes were then placed in a 1mol / L NaOH alkaline solution and stirred at 60℃ for 2 hours for modification. The modified nanofiber membranes were redissolved in methanol at a ratio of 15wt%, stirred at 500rpm for 1 hour at 90℃, cooled to room temperature, and then stirred for another 10 minutes. The dissolved solution was placed in an ultrasonic treatment device (frequency 40 kHz, power 400 W) and treated at 40℃ for 10 minutes, while simultaneously being initially stirred with a magnetic stirrer at 400 rpm for 10 minutes. Then, it was transferred to a high-speed stirrer and stirred at 1500 rpm for 30 minutes, followed by standing for 5 minutes to obtain the treated polyacrylonitrile solution A. 1 wt% titanium dioxide nanoparticles and 2 wt% SDS were added to this solution and stirred thoroughly to form polyacrylonitrile solution B. A membrane was then formed using electrospinning technology and dried in a constant temperature drying oven at 55℃ for 10 minutes to obtain a pre-formed polyacrylonitrile membrane. The membrane was then immersed in a 0.125 wt% PIP aqueous solution for 2 minutes, followed by the addition of 2 mL of a 0.2 wt% TMC n-hexane solution. The interfacial polymerization time was 20 s. Finally, the membrane was rinsed three times with deionized water and soaked for 12 hours to remove residual reagents. It was then dried at room temperature for 12 hours to obtain the final composite nanofiltration membrane.

[0037] Pore ​​size uniformity: The coefficient of variation of pore size was 8% as measured by mercury porosimetry, and the ratio of the maximum pore size to the minimum pore size was 1.3.

[0038] Thickness uniformity: Using laser interferometry, 100 points were measured in a grid pattern, and the thickness deviation rate was ±3%, with a standard deviation of 5 nm.

[0039] Purification effect of deer antler peptide: For the separation of deer antler peptide with a molecular weight of 800 Da or above, the separation efficiency is 92%, the yield is 88%, and the throughput is 55 L / (m²・h).

[0040] Example 4

[0041] Nine g of polyacrylonitrile powder was added to 110 mL of butanol organic solvent and stirred at 350 rpm for 2.8 hours at 82 °C to form polyacrylonitrile solution A. The solution was cooled to room temperature and stirred for another 13 minutes. Polyacrylonitrile solution A was then loaded into a syringe with a needle diameter of 0.4 mm, and nanofiber membranes were fabricated by electrospinning at a spinning voltage of 18 kV, an injection rate of 1.2 mL / h, and a spinning distance of 18 cm. Subsequently, the nanofiber membranes were placed in a 1 mol / L NaOH alkaline solution and stirred at 60 °C for 2 hours for modification. The modified nanofiber membranes were redissolved in butanol at a ratio of 13 wt%, stirred at 350 rpm for 1.8 hours at 82 °C, cooled to room temperature, and stirred for another 13 minutes. The dissolved solution was placed in an ultrasonic treatment device (frequency 35 kHz, power 350 W) and treated at 38°C for 18 minutes, while simultaneously being initially stirred with a magnetic stirrer at 350 rpm for 13 minutes. Then, it was transferred to a high-speed stirrer and stirred at 1300 rpm for 35 minutes, followed by standing for 7 minutes to obtain the treated polyacrylonitrile solution A. 0.6 wt% titanium dioxide nanoparticles and 1.8 wt% SDS were added to this solution and stirred thoroughly to form polyacrylonitrile solution B. This solution was then used to form a film using electrospinning technology and dried in a constant temperature drying oven at 52°C for 13 minutes to obtain a pre-formed polyacrylonitrile film. The membrane was immersed in a 0.08 wt% PIP aqueous solution for 2.8 min, then 2 mL of a 0.18 wt% TMC n-hexane solution was added dropwise. The interfacial polymerization time was 50 s. Finally, the membrane was rinsed three times with deionized water and soaked for 14 hours to remove residual reagents. The membrane was then dried at room temperature for 14 hours to obtain the final composite nanofiltration membrane.

[0042] Pore ​​size uniformity: Measured by mercury porosimetry, the coefficient of variation of pore size is 9.5%, and the ratio of the maximum pore size to the minimum pore size is 1.38.

[0043] Thickness uniformity: Using laser interferometry, 100 points were measured in a grid pattern, and the thickness deviation rate was ±3.8%, with a standard deviation of 6.5 nm.

[0044] Purification effect of deer antler peptides: The separation efficiency of deer antler peptides with a molecular weight of more than 1100 Da reached 89%, the yield was 86%, and the throughput was 48 L / (m²・h).

[0045] Example 5

[0046] 11 g of polyacrylonitrile powder was added to 90 mL of a mixed organic solvent (DMF and methanol volume ratio 1:1) and stirred at 450 rpm for 2.2 hours at 88 °C to form polyacrylonitrile solution A. The solution was cooled to room temperature and stirred for another 11 minutes. Polyacrylonitrile solution A was then loaded into a syringe with a needle diameter of 0.35 mm, and nanofiber membranes were fabricated by electrospinning at a spinning voltage of 22 kV, an injection rate of 0.8 mL / h, and a spinning distance of 12 cm. The nanofiber membranes were then placed in a 1 mol / L NaOH alkaline solution and stirred at 60 °C for 2 hours for modification. The modified nanofiber membranes were redissolved in the mixed organic solvent at a ratio of 14 wt%, stirred at 450 rpm for 1.2 hours at 88 °C, cooled to room temperature, and stirred for another 11 minutes. The dissolved solution was placed in an ultrasonic treatment device (frequency 32 kHz, power 320 W) and treated at 32°C for 16 minutes, while simultaneously being initially stirred with a magnetic stirrer at 320 rpm for 11 minutes. It was then transferred to a high-speed stirrer and stirred at 1400 rpm for 32 minutes, followed by standing for 6 minutes to obtain the treated polyacrylonitrile solution A. 0.9 wt% titanium dioxide nanoparticles and 1.6 wt% SDS were added to this solution and stirred thoroughly to form polyacrylonitrile solution B. This solution was then used to form a film using electrospinning technology and dried in a constant-temperature drying oven at 53°C for 11 minutes to obtain a pre-formed polyacrylonitrile film. The membrane was immersed in a 0.1 wt% PIP aqueous solution for 2.2 min, then 2 mL of a 0.16 wt% TMC n-hexane solution was added dropwise. The interfacial polymerization time was 30 s. Finally, the membrane was rinsed 4 times with deionized water and soaked for 13.5 hours to remove residual reagents. The membrane was then dried at room temperature for 13.5 hours to obtain the final composite nanofiltration membrane.

[0047] Pore ​​size uniformity: The coefficient of variation of pore size was 8.5% as measured by mercury porosimetry, and the ratio of the maximum pore size to the minimum pore size was 1.32.

[0048] Thickness uniformity: Using laser interferometry, 100 points were measured in a grid pattern, and the thickness deviation rate was ±3.2%, with a standard deviation of 5.5 nm.

[0049] Purification effect of deer antler peptide: For the separation of deer antler peptide with a molecular weight of 900 Da or above, the separation efficiency is 91%, the yield is 87%, and the throughput is 52 L / (m²・h).

Claims

1. A method for preparing a highly uniform nanofiltration membrane for purifying deer antler peptides, characterized in that... Includes the following steps: (1) Add polyacrylonitrile powder to one or more organic solvents, heat and stir until completely dissolved to form polyacrylonitrile solution A, wherein the ratio of polyacrylonitrile powder to organic solvent is 8-12 g / 100 mL, and the organic solvent is one or more of DMF, DMAc, methanol or butanol. The heating temperature is 80-90℃, the stirring speed is 300-500 rpm, the stirring time is 2-3 hours, and after cooling to room temperature, continue stirring for 10-15 minutes. (2) The polyacrylonitrile solution A is made into a nanofiber membrane by electrospinning technology, wherein the polyacrylonitrile solution A is loaded into a syringe, the syringe needle diameter is 0.2-0.5 mm, the spinning voltage is 15-25 kV, the injection rate is 0.5-1.5 mL / h, and the spinning distance is 10-20 cm. (3) The prepared nanofiber membrane was modified by adding NaOH solution with a concentration of 1 mol / L and stirring at 60°C for 2 hours; (4) The modified polyacrylonitrile nanofiber membrane is redissolved in an organic solvent at a ratio of 10-15g / 100mL. The heating temperature is 80-90℃, the stirring speed is 300-500 rpm, the stirring time is 1-2 hours, and after cooling to room temperature, the stirring is continued for 10-15 minutes. (5) The dissolved solution is subjected to ultrasonic treatment. The frequency of the ultrasonic treatment equipment is 20-40 kHz, the power is 200-400 watts, the treatment time is 10-20 minutes, and the solution temperature is maintained at 30-40℃ during the treatment process. (6) Add 0.5-1 wt% of titanium dioxide nanoparticles and 1-2 wt% of sodium dodecyl sulfate to the ultrasonically treated solution and stir thoroughly to form polyacrylonitrile solution B; (7) The polyacrylonitrile solution B is electrospinned to form a film, and then dried at a constant temperature of 45-55℃ for 10-15 minutes to obtain a pre-formed polyacrylonitrile film. (8) Soak the preliminarily formed polyacrylonitrile film in a piperazine aqueous solution with a mass concentration of 0.025wt% to 0.125wt% for 2 to 3 minutes, and then add 2 mL of a pyromellitic trimethylolpropionate chloride hexane solution with a mass fraction of 0.1% to 0.2wt% for 20 to 60 seconds. (9) The polyacrylonitrile membrane after interface treatment is rinsed with deionized water 3 to 4 times, then soaked for 12 to 15 hours to remove residual reagents, and then dried at room temperature for more than 12 hours to obtain a composite nanofiltration membrane.

2. The preparation method according to claim 1, characterized in that: In the step of ultrasonic treatment of the dissolved solution, the dissolved solution is placed in the container of the ultrasonic treatment equipment, ensuring that the liquid level does not exceed two-thirds of the container.

3. The preparation method according to claim 1, characterized in that: The organic solvent is DMF.

4. The preparation method according to claim 1, characterized in that: The proportion of titanium dioxide nanoparticles added is 0.8 wt%.

5. The preparation method according to claim 1, characterized in that: The piperazine aqueous solution has a mass concentration of 0.05 wt%, the pyromellitic trimethylolpropionate chloride n-hexane solution has a mass fraction of 0.15 wt%, and the interfacial polymerization time is 40 seconds.

6. The highly uniform nanofiltration membrane prepared by the method according to any one of claims 1-5, characterized in that: The nanofiltration membrane achieves a 90% rejection rate for antler peptides with a molecular weight of 1000 Da or higher.