Preparation method of sustainable hydrophilic internal support hollow fiber ultrafiltration membrane

Abstract

The invention discloses a preparation method of a sustainable hydrophilic inner support hollow fiber ultrafiltration membrane. The preparation method comprises the following steps: (1) uniformly stirring and dissolving polyethersulfone resin, bisphenol A type polysulfate resin, an organic solvent and a composite pore-forming agent, standing and defoaming to prepare a membrane casting solution; (2) coating the membrane casting solution on the surface of a crocheted tube, after coating, putting the crocheted tube into a water coagulating bath for coagulating and forming, and winding by a wire winding wheel to obtain a formed part; and (3) soaking the molded part in pure water, soaking the molded part in a glycerol aqueous solution, and airing to obtain the product. Through blending modification of polysulfate and polyethersulfone, the defects that a traditional internal support hollow fiber ultrafiltration membrane is poor in hydrophilicity and prone to pollution are overcome, the sustainable hydrophilic effect is achieved on the basis that high strength and excellent filtering performance are kept, and important application value and popularization prospects are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical fields of gene sequencing and molecular biology, and particularly relates to a preparation method of a sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane. Background Art

[0002] In the field of membrane separation technology, ultrafiltration membranes are widely used in many industries such as water treatment, food and beverage processing, biopharmaceuticals, and chemical engineering due to their efficient separation performance. As a self-supported membrane, the traditional homogeneous hollow fiber ultrafiltration membrane has certain application value, but its mechanical strength is relatively low, making it difficult to meet the requirements of some high-intensity application scenarios. Especially after the submerged membrane bioreactor (MBR) technology has gradually matured and replaced the secondary sedimentation tank in the traditional process for solid-liquid separation, higher requirements are put forward for the performance of membrane materials. The MBR process usually requires an ultrafiltration membrane of the lined membrane type to have greater mechanical strength, lower pore size requirements, and at the same time, a wide pore size distribution, larger pore size, and the ability to withstand frequent cleaning; while submerged ultrafiltration requires a smaller pore size, narrow pore size distribution, and even the filtered water quality can be directly used in the reverse osmosis (RO) system while demanding high strength. However, due to insufficient strength, ordinary homogeneous hollow fiber membranes can no longer meet the application requirements of submerged ultrafiltration modules.

[0003] With the development of technology, inner-supported hollow fiber ultrafiltration membranes have become a research hotspot due to their high mechanical strength and have been widely used in the field of water treatment. However, there are still significant membrane fouling problems in the actual use of existing inner-supported hollow fiber ultrafiltration membranes. Impurities such as suspended solids, colloids, microorganisms, and dissolved organic matter in water are easily adsorbed or deposited on the membrane surface and within the membrane pores, resulting in a decrease in membrane flux and deterioration of filtration performance. Especially for traditional inner-supported ultrafiltration membranes prepared from hydrophobic materials such as polysulfone, polyethersulfone, or polyvinylidene fluoride, their strong surface hydrophobicity and weak interaction with polar pollutants make it easier for pollutants to adhere to the membrane surface, leading to serious membrane fouling. This problem not only increases the membrane cleaning cost and maintenance workload but also significantly shortens the service life of the membrane, restricting the further promotion of ultrafiltration membrane technology in practical applications.

[0004] To solve the problem of membrane fouling and improve the anti-fouling performance of ultrafiltration membranes, researchers have tried to improve membrane materials through various methods, including hydrophilic modification of the membrane surface. As a type of polymer containing sulfate ester groups (-OSO3H), the polar groups in the molecular structure of polysulfate can form hydrogen bonds and other interactions with water molecules, thus endowing the material with good hydrophilicity. In addition, polysulfate and polyethersulfone have certain similarities in the main chain structure, side group types and distributions, etc. According to the "like dissolves like" principle, the two show good compatibility when blended. Therefore, by blending polysulfate with polyethersulfone, it is expected to significantly improve the hydrophilicity of the membrane while maintaining the basic properties of the membrane material, thereby improving its anti-fouling ability and providing a new solution for the practical application of ultrafiltration membranes. Summary of the Invention

[0005] The object of the present invention is to overcome the defects of the prior art and provide a method for preparing a sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane.

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

[0007] A method for preparing a sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane, comprising the following steps:

[0008] (1) Stir and dissolve polyethersulfone resin, bisphenol A polysulfate resin, organic solvent and composite pore-forming agent uniformly at 75-90 °C, and prepare a casting solution after standing and degassing; the composite pore-forming agent is composed of polyethylene glycol, polyvinylpyrrolidone and saturated lithium chloride solution mixed;

[0009] (2) After passing the casting solution prepared in step (1) through a filter screen, extrude and coat it on the surface of the crocheted tube together with the core liquid through a spinning spinneret, walk vertically downward in the air for 3-40 cm after coating, and then enter the water coagulation bath to solidify and form, and wind it with a winding wheel to obtain a formed part;

[0010] (3) Immerse the formed part prepared in step (2) in pure water at a room temperature of 15-35 °C for 40-60 h, then immerse it in a glycerol aqueous solution with a glycerol mass percentage of 10-35% for 10-15 h, and then dry it to obtain a sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane.

[0011] In a preferred embodiment of the present invention, in the composite pore-forming agent, the mass ratio of polyethylene glycol, polyvinylpyrrolidone and saturated lithium chloride solution is 4:5:2.

[0012] Further preferably, the polyethylene glycol is polyethylene glycol-400.

[0013] In a preferred embodiment of the present invention, the specifications of the crocheted tube are: outer diameter 1.9 mm, inner diameter 0.8 mm.

[0014] In a preferred embodiment of the present invention, the molecular weight of the bisphenol A polysulfate resin is 30,000 - 60,000.

[0015] More preferably, the molecular weight of the bisphenol A polysulfate resin is 50,000.

[0016] In a preferred embodiment of the present invention, the organic solvent is selected from dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0017] More preferably, the organic solvent is dimethylacetamide.

[0018] In a preferred embodiment of the present invention, in step (2), after coating, it walks vertically downward in the air for 12 cm.

[0019] In a preferred embodiment of the present invention, in the casting solution, the content of the polyethersulfone resin is 12 - 25 wt%, the content of the bisphenol A polysulfate resin is 2 - 10 wt%, and the content of the composite pore-forming agent is 10 - 12 wt%.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The contact angle of the ultrafiltration membrane prepared by the present invention is less than 45 degrees, far lower than the contact angles of traditional polyethersulfone membranes or polyvinylidene fluoride membranes (usually around 60 - 80 degrees), showing excellent hydrophilic properties. This enhanced hydrophilicity stems from the strong interaction formed between the sulfate ester groups in the polysulfate molecular structure and water molecules.

[0022] 2. Due to the significant improvement in the hydrophilicity of the membrane surface, pollutants are not easily attached to the membrane surface or within the membrane pores, making the ultrafiltration membrane prepared by the present invention have excellent anti-fouling properties. Compared with traditional hydrophobic membrane materials, the membrane of the present invention can reduce the occurrence of membrane fouling, lower the cleaning frequency and maintenance cost, and at the same time extend the service life of the membrane.

[0023] 3. The filtration pore size of the ultrafiltration membrane prepared by the present invention is controlled within the range of 0.05 - 0.1 μm, which can effectively intercept impurities such as suspended solids, colloids, and microorganisms in water, meeting the requirements of high-precision filtration. At the same time, the tensile strength of the membrane filaments is greater than 200 N, which can withstand the mechanical stress during the operation of the submerged ultrafiltration module, showing good durability.

[0024] 4. After the ultrafiltration membrane prepared by the present invention operates in the simulated feed liquid for half a year and one year, the contact angle remains basically unchanged (for example, in Example 1, the contact angle changes from 35° to 36°), indicating that the hydrophilicity of the membrane has excellent sustainability. This characteristic enables the membrane to maintain stable filtration performance and anti-fouling ability during long-term use, significantly superior to the defect that the contact angle of traditional hydrophobic membrane materials gradually increases after operation. Description of the Drawings

[0025] Figure 1 This is a scanning electron microscope photograph of the sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane prepared in Example 1 of the present invention. Detailed Description of the Invention

[0026] The technical solutions of the present invention will be further described and illustrated below through specific embodiments in conjunction with the drawings.

[0027] Example 1

[0028] (1) 1200 g of polyethersulfone resin (model 6020), 800 g of bisphenol A polysulfonate resin (molecular weight 50000), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution were added to a reaction kettle, and stirred at high speed at 80 °C until dissolved uniformly, then left to stand for defoaming for 24 h to obtain a casting solution.

[0029] (2) After passing the casting solution prepared in step (1) through a filter screen, it was extruded and coated on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning spinneret. The discharge rate was 130 mL / s. After coating, it walked vertically downward in the air for 12 cm, and then entered a water coagulation bath at 25 °C for solidification and forming, and was wound by a winding wheel to obtain a formed part.

[0030] (3) The formed part prepared in step (2) was soaked in pure water at room temperature of 15 - 35 °C for 48 h, then soaked in a glycerol aqueous solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dried to obtain the Figure 1 sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane as shown.

[0031] The outer diameter of the sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane prepared in this example was 2.2 mm, the membrane layer thickness was 0.15 mm, the pure water flux was 1068 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore size was 0.09 μm, the contact angle was 35°, and the tensile strength was 208 N. The simulated feed liquid operation test showed that the contact angle was 36° after running for half a year and 36° after running for one year.

[0032] Example 2

[0033] (1) Add 1400 g of polyethersulfone resin (model 6020), 600 g of bisphenol A polysulfonate resin (molecular weight 50000), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution into a reaction kettle, stir and dissolve uniformly at high speed at 80 °C, and stand for defoaming for 24 h to obtain a casting solution.

[0034] (2) After passing the casting solution prepared in step (1) through a filter screen, extrude and coat it on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning nozzle. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and forming, and is wound by a winding wheel to obtain a formed part.

[0035] (3) Immerse the formed part prepared in step (2) in pure water at a room temperature of 15 - 35 °C for 48 h, then immerse it in a glycerol aqueous solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dry it to obtain a sustainable hydrophilic inner - supported hollow fiber ultrafiltration membrane.

[0036] The outer diameter of the sustainable hydrophilic inner - supported hollow fiber ultrafiltration membrane prepared in this example is 2.2 mm, the membrane layer thickness is 0.15 mm, the pure water flux is 932 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore diameter is 0.08 μm, the contact angle is 37°, and the tensile strength is 209 N. The simulated feed liquid operation test shows that the contact angle is 37° after running for half a year and 37° after running for one year.

[0037] Example 3

[0038] (1) Add 1600 g of polyethersulfone resin (model 6020), 400 g of bisphenol A polysulfonate resin (molecular weight 50000), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution into a reaction kettle, stir and dissolve uniformly at high speed at 80 °C, and stand for defoaming for 24 h to obtain a casting solution.

[0039] (2) After passing the casting solution prepared in step (1) through a filter screen, extrude and coat it on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning nozzle. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and forming, and is wound by a winding wheel to obtain a formed part.

[0040] (3) The formed parts obtained in step (2) are soaked in pure water at a room temperature of 15 - 35°C for 48 h, then soaked in an aqueous glycerol solution with a glycerol mass percentage of 10 - 35% for 12 h, and then air-dried to obtain a sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane.

[0041] The outer diameter of the sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane prepared in this example is 2.2 mm, the membrane layer thickness is 0.15 mm, and the pure water flux is 915 L / m 2 ·h (test temperature 25°C, test pressure 0.1 MPa), the average pore size is 0.07 μm, the contact angle is 39°, and the tensile strength is 210 N. The simulated feed liquid operation test shows that the contact angle is 39° after running for half a year and 39° after running for one year.

[0042] Example 4

[0043] (1) 1800 g of polyethersulfone resin (model 6020), 200 g of bisphenol A poly sulfate ester resin (molecular weight 50000), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution are added to a reaction kettle, stirred and dissolved evenly at high speed at 80°C, and left to stand for defoaming for 24 h to prepare a casting solution.

[0044] (2) After the casting solution prepared in step (1) passes through a filter screen, it is extruded and coated on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning spinneret. The discharge rate is 130 mL / s. After coating, it travels vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25°C for solidification and forming, and is wound by a winding wheel to obtain a formed part.

[0045] (3) The formed parts obtained in step (2) are soaked in pure water at a room temperature of 15 - 35°C for 48 h, then soaked in an aqueous glycerol solution with a glycerol mass percentage of 10 - 35% for 12 h, and then air-dried to obtain a sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane.

[0046] The outer diameter of the sustainable hydrophilic inner-supported hollow fiber ultrafiltration membrane prepared in this example is 2.2 mm, the membrane layer thickness is 0.15 mm, and the pure water flux is 904 L / m 2 ·h (test temperature 25°C, test pressure 0.1 MPa), the average pore size is 0.06 μm, the contact angle is 40°, and the tensile strength is 210 N. The simulated feed liquid operation test shows that the contact angle is 40° after running for half a year and 40° after running for one year.

[0047] Example 5

[0048] (1) Add 2500 g of polyethersulfone resin (model 6020), 1000 g of bisphenol A polysulfonate resin (molecular weight of 50000), 5400 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution into a reaction kettle, stir and dissolve uniformly at high speed at 80 °C, and stand for defoaming for 24 h to obtain a casting solution.

[0049] (2) After passing the casting solution prepared in step (1) through a filter screen, extrude and coat it on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning nozzle. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and molding, and is wound by a winding wheel to obtain a molded part.

[0050] (3) Immerse the molded part prepared in step (2) in pure water at a room temperature of 15 - 35 °C for 48 h, then immerse it in a glycerol aqueous solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dry it to obtain a sustainable hydrophilic inner - supported hollow fiber ultrafiltration membrane.

[0051] The outer diameter of the sustainable hydrophilic inner - supported hollow fiber ultrafiltration membrane prepared in this example is 2.2 mm, the membrane layer thickness is 0.15 mm, the pure water flux is 733 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore size is 0.05 μm, the contact angle is 40°, and the tensile strength is 210 N. The simulated feed liquid operation test shows that the contact angle is 40° after running for half a year and 40° after running for one year.

[0052] Comparative Example 1

[0053] (1) Add 2000 g of polyethersulfone resin (model 6020), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution into a reaction kettle, stir and dissolve uniformly at high speed at 80 °C, and stand for defoaming for 24 h to obtain a casting solution.

[0054] (2) After passing the casting solution prepared in step (1) through a filter screen, extrude and coat it on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning nozzle. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and molding, and is wound by a winding wheel to obtain a molded part.

[0055] (3) The formed parts obtained in step (2) are soaked in pure water at a room temperature of 15 - 35 °C for 48 h, then soaked in an aqueous glycerol solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dried to obtain the inner - supported hollow - fiber ultrafiltration membrane.

[0056] The outer diameter of the inner - supported hollow - fiber ultrafiltration membrane prepared in this comparative example is 2.2 mm, the membrane layer thickness is 0.15 mm, and the pure - water flux is 689 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore size is 0.03 μm, the contact angle is 69°, and the tensile strength is 215 N. The simulated feed - liquid operation test shows that the contact angle is 72° after running for half a year and 75° after running for one year.

[0057] Comparative Example 2

[0058] (1) Add 2000 g of bisphenol A polysulfonate resin (molecular weight 50000), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution into a reaction kettle, stir and dissolve evenly at high speed at 80 °C, and stand for defoaming for 24 h to prepare the casting solution.

[0059] (2) After passing the casting solution prepared in step (1) through a filter screen, it is extruded and coated on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning spinneret. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and forming, and is wound by a winding wheel to obtain the formed parts.

[0060] (3) The formed parts obtained in step (2) are soaked in pure water at a room temperature of 15 - 35 °C for 48 h, then soaked in an aqueous glycerol solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dried to obtain the inner - supported hollow - fiber ultrafiltration membrane.

[0061] The outer diameter of the inner - supported hollow - fiber ultrafiltration membrane prepared in this comparative example is 2.2 mm, the membrane layer thickness is 0.15 mm, and the pure - water flux is 1112 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore size is 0.1 μm, the contact angle is 34°, and the tensile strength is 205 N. The simulated feed - liquid operation test shows that the contact angle is 35° after running for half a year and 37° after running for one year.

[0062] Comparative Example 3

[0063] (1) Add 2000 g of polyvinylidene fluoride resin (model FR904), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution into a reaction kettle, stir and dissolve uniformly at a high speed at 80 °C, and stand for defoaming for 24 h to obtain a casting solution.

[0064] (2) After passing the casting solution prepared in step (1) through a filter screen, extrude and coat it on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning spinneret. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and molding, and is wound by a winding wheel to obtain a molded part.

[0065] (3) Immerse the molded part prepared in step (2) in pure water at room temperature of 15 - 35 °C for 48 h, then immerse it in a glycerol aqueous solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dry it to obtain an inner - supported hollow fiber ultrafiltration membrane.

[0066] The outer diameter of the inner - supported hollow fiber ultrafiltration membrane prepared in this comparative example is 2.2 mm, the membrane layer thickness is 0.15 mm, the pure water flux is 1160 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore size is 0.2 μm, the contact angle is 75°, and the tensile strength is 220 N. The simulated feed liquid operation test shows that the contact angle is 78° after running for half a year and 82° after running for one year.

[0067] Comparative Example 4

[0068] (1) Add 1200 g of polyethersulfone resin (model 6020), 800 g of polyvinylidene fluoride resin (model FR904), 6900 g of dimethylacetamide, 400 g of polyethylene glycol - 400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution into a reaction kettle, stir and dissolve uniformly at a high speed at 80 °C, and stand for defoaming for 24 h to obtain a casting solution.

[0069] (2) After passing the casting solution prepared in step (1) through a filter screen, extrude and coat it on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning spinneret. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and molding, and is wound by a winding wheel to obtain a molded part.

[0070] (3) Immerse the molded part prepared in step (2) in pure water at room temperature of 15 - 35 °C for 48 h, then immerse it in a glycerol aqueous solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dry it to obtain an inner - supported hollow fiber ultrafiltration membrane.

[0071] The outer diameter of the inner-supported hollow fiber ultrafiltration membrane prepared in this comparative example is 2.2 mm, the membrane layer thickness is 0.15 mm, and the pure water flux is 1520 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore size is 0.4 μm, the contact angle is 72°, and the tensile strength is 218 N. The simulated feed liquid operation test shows that the contact angle is 76° after running for half a year and 80° after running for one year.

[0072] Comparative Example 5

[0073] (1) Add 1200 g of polyvinylidene fluoride resin (model FR904), 800 g of bisphenol A polysulfonate resin (molecular weight 50000), 6900 g of dimethylacetamide, 400 g of polyethylene glycol-400, 500 g of polyvinylpyrrolidone, and 200 g of saturated lithium chloride solution to the reaction kettle, stir and dissolve uniformly at high speed at 80 °C, and let stand for defoaming for 24 h to obtain a casting solution.

[0074] (2) After passing the casting solution prepared in step (1) through a filter screen, it is extruded and coated on the surface of a crocheted tube (outer diameter 1.9 mm, inner diameter 0.8 mm) together with the core liquid (RO water) through a spinning spinneret. The discharge rate is 130 mL / s. After coating, it walks vertically downward in the air for 12 cm, and then enters a water coagulation bath at 25 °C for solidification and molding, and is wound by a winding wheel to obtain a molded part.

[0075] (3) Immerse the molded part prepared in step (2) in pure water at room temperature of 15 - 35 °C for 48 h, then immerse it in a glycerol aqueous solution with a glycerol mass percentage of 10 - 35% for 12 h, and then dry it to obtain an inner-supported hollow fiber ultrafiltration membrane.

[0076] The outer diameter of the inner-supported hollow fiber ultrafiltration membrane prepared in this comparative example is 2.2 mm, the membrane layer thickness is 0.15 mm, and the pure water flux is 1640 L / m 2 ·h (test temperature 25 °C, test pressure 0.1 MPa), the average pore size is 0.4 μm, the contact angle is 55°, and the tensile strength is 210 N. The simulated feed liquid operation test shows that the contact angle is 58° after running for half a year and 60° after running for one year.

[0077] The process ratios and performance parameters of the above examples and comparative examples are compared as shown in Table 1 below:

[0078] Table 1

[0079]

[0080] The above are only the preferred embodiments of the present invention, and thus the scope of implementation of the present invention cannot be limited thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention.

Claims

1. A method for preparing a sustainable hydrophilic internally supported hollow fiber ultrafiltration membrane, characterized in that: The steps include: (1) stirring and dissolving polyethersulfone resin, bisphenol A type polysulfate resin, organic solvent and composite pore-forming agent at 75-90° C. uniformly, and standing to degas to obtain a casting solution; the composite pore-forming agent is prepared by mixing polyethylene glycol, polyvinyl pyrrolidone and a saturated lithium chloride solution; (2) the casting liquid obtained in step (1) is filtered and then extruded onto the surface of the crochet tube together with the core liquid through a spinning spinneret. After coating, the casting liquid moves vertically downward in the air for 3-40 cm, then enters a water coagulation bath for coagulation and is wound by a winding wheel to obtain a molded part. (3) The molded part obtained in step (2) is immersed in pure water at room temperature of 15-35° C. for 40-60 hours, and then immersed in a glycerol aqueous solution with a glycerol mass percentage of 10-35% for 10-15 hours, and then dried to obtain a sustainable hydrophilic internally supported hollow fiber ultrafiltration membrane.

2. The preparation method according to claim 1, characterized in that: In the composite pore-forming agent, the mass ratio of polyethylene glycol, polyvinyl pyrrolidone and lithium chloride saturated solution is 4:5:

2.

3. The preparation method according to claim 2, characterized in that: The polyethylene glycol is polyethylene glycol-400.

4. The preparation method according to claim 1, characterized in that: The specifications of the crochet tube are: outer diameter 1.9 mm, inner diameter 0.8 mm.

5. The preparation method according to claim 1, characterized in that: The molecular weight of the bisphenol A type polysulfate resin is 30,000-60,000.

6. The preparation method according to claim 5, characterized in that: The molecular weight of the bisphenol A type polysulfate resin is 50,000.

7. The preparation method according to claim 1, characterized in that: The organic solvent is selected from dimethylformamide, dimethylacetamide and N-methylpyrrolidone.

8. The preparation method according to claim 7, characterized in that: The organic solvent is dimethylacetamide.

9. The preparation method according to claim 1, characterized in that: In the step (2), after coating, walk vertically downward in the air for 12 cm.

10. The preparation method according to any one of claims 1 to 9, characterized in that: In the casting solution, the content of the polyethersulfone resin is 12-25wt%, the content of the bisphenol A type polysulfate resin is 2-10wt%, and the content of the composite pore-forming agent is 10-12wt%.

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