Hydrophilic modified polyether sulfone hollow fiber ultrafiltration membrane and preparation method thereof

Abstract

The invention provides a hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane and a preparation method thereof, and the preparation method comprises the following steps: preparing a polyethersulfone hollow fiber ultrafiltration membrane: mixing sultone, aluminum chloride or tin chloride according to a set mass ratio to obtain a sultone stock solution; the method comprises the following steps: soaking a polyethersulfone hollow fiber ultrafiltration membrane in a sultone stock solution for a set time period, adding RO water to prepare a sultone solution, soaking for the set time period, transferring to an acid environment for cleaning, transferring the cleaned polyethersulfone hollow fiber ultrafiltration membrane to an alkaline environment for cleaning, and drying to obtain the polyethersulfone hollow fiber ultrafiltration membrane. Taking out the cleaned polyethersulfone hollow fiber ultrafiltration membrane, sequentially soaking the polyethersulfone hollow fiber ultrafiltration membrane with reverse osmosis water and a glycerol solution, and airing to obtain the hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane. The hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane which is high in hydrophilicity and uniform in sulfonation is obtained through sulfonation post-treatment of the polyethersulfone hollow fiber ultrafiltration membrane.

Description

Technical Field

[0001] The invention relates to the field of hollow fiber ultrafiltration membranes, and in particular to a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane and a preparation method thereof. Background Art

[0002] Hollow fiber ultrafiltration membrane refers to a membrane technology used to separate, filter and concentrate liquids. Its working principle is to separate different components in the solution through tiny pores on the membrane. When pressure is applied to the membrane, the solutes in the solution (such as macromolecules, suspended matter or bacteria) will be retained by the pores on the membrane, while water molecules can pass through these pores to achieve separation and concentration.

[0003] Polyethersulfone can be used as a hollow fiber ultrafiltration membrane material with excellent performance due to its high temperature tolerance, good chemical stability and good mechanical strength. It has been promoted and applied in many application scenarios such as electronics, medicine, electrophoretic paint, beverages, food chemicals, medical treatment, wastewater treatment and recycling. Although polyethersulfone hollow fiber ultrafiltration membrane has many advantages, it has a strong surface hydrophobicity, which makes charged pollutants easily adsorbed on the membrane surface and thus forms membrane pollution, which reduces membrane performance and shortens service life. Therefore, the development of a highly hydrophilic, high-throughput, and pollution-resistant polyethersulfone hollow fiber membrane has become an important research direction recently.

[0004] The prior art hydrophilically modifies the polyethersulfone hollow fiber ultrafiltration membrane by chemically or physically modifying the polyethersulfone surface, or by introducing hydrophilic additives into the polyethersulfone material. Specifically, the methods include: 1. grafting hydrophilic functional groups on the membrane surface to chemically modify the membrane surface; 2. blending polyethersulfone with a hydrophilic polymer to form a stable blending system to achieve physical bulk modification. However, most of the solutions have the disadvantages of complicated manufacturing process, high material cost and high process flow requirements, which makes it difficult to carry out large-scale industrial mass production of these solutions, thus still limiting the application of polyethersulfone hollow fiber ultrafiltration membranes. Summary of the invention

[0005] The purpose of the present invention is to provide a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane and a preparation method thereof, which has the advantages of simple formula materials, low production cost and simple process operation, is easy to be industrially mass-produced and promoted, and can be widely used in many fields such as household water purification, seawater desalination and industrial wastewater treatment.

[0006] To achieve the above objectives, the present technical solution provides a method for preparing a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane, comprising the following steps: S1: preparing a film casting liquid: mixing and dissolving a polyethersulfone polymer, a non-solvent, a film casting solvent and a film casting aid to obtain a film casting liquid; S2: preparing the core liquid: mixing and dissolving the core liquid solvent and the core liquid non-solvent to obtain the core liquid; S3: preparing a polyethersulfone hollow fiber ultrafiltration membrane: injecting a casting liquid and a core liquid into the same spinneret to extrude a hollow tubular liquid membrane, and curing, cleaning and drying the hollow tubular liquid membrane to obtain a polyethersulfone hollow fiber ultrafiltration membrane; S4: preparing a sultone stock solution: mixing sultone and aluminum chloride or tin chloride in a set ratio to obtain a sultone stock solution; S5: Preparation of hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane: soak the polyethersulfone hollow fiber ultrafiltration membrane in a sultone stock solution for a set period of time, then add RO water to prepare a sultone solution and continue soaking for a set time, then transfer to an acidic environment and an alkaline environment for cleaning, take out and dry to obtain a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane.

[0007] It should be noted that this scheme performs sulfonation treatment on the polyethersulfone hollow fiber ultrafiltration membrane after preparation. Different from the method of sulfonating the raw materials and then making the membrane, the degree of sulfonation can be more accurately controlled to ensure that the modification of the membrane surface is more uniform, and the post-sulfonation preparation method is also simpler and easier to operate.

[0008] It should be noted that aluminum chloride or tin chloride is used as a catalyst in this scheme. The reaction formula for sulfonation treatment of the polyethersulfone hollow fiber ultrafiltration membrane and sultone stock solution in this scheme is described below using aluminum chloride as a catalyst as follows:

[0009] Specifically, the sultone in the sultone solution reacts with aluminum chloride to obtain a sulfonic acid intermediate, and the sulfonic acid intermediate reacts with polyethersulfone or polysulfone in the polyethersulfone hollow fiber ultrafiltration membrane to achieve sulfonation treatment of the polyethersulfone hollow fiber ultrafiltration membrane.

[0010] In the step of "preparing casting liquid", the polyethersulfone polymer is selected as a polyether polymer or a polyethersulfone polymer, the casting solvent is selected as at least one of N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone, and the casting aid is selected as at least one of polyethylene glycol and polyvinylpyrrolidone.

[0011] In some embodiments, the non-solvent in the film casting solution is selected as diethylene glycol.

[0012] Specifically, step "S1 prepares casting liquid" includes the following steps: placing polyethersulfone polymer, non-solvent, casting solvent and casting aid in a dissolution kettle and mixing under set conditions to obtain casting liquid, wherein the set conditions are at a temperature of 40~60°C and a rotation speed of 100r / min, stirring and dissolving for 24~48 hours and cooling to 20~30°C, and then vacuum degassing for 8~12 hours at a pressure of -0.09~0.08MPa.

[0013] In the step of "preparing the core liquid", the core liquid solvent is selected as one of N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone, and the core liquid non-solvent is selected as one of water and ethanol.

[0014] Specifically, step "S2 prepares the core liquid" includes the following steps: placing the core liquid solvent and the core liquid non-solvent in a stirring kettle to obtain the core liquid under set conditions, wherein the set conditions are stirring and mixing at a speed of 100 r / min for 4 hours, and vacuum degassing at a pressure of -0.05 MPa for 2 to 4 hours.

[0015] In the step of "preparing polyethersulfone hollow fiber ultrafiltration membrane", the casting liquid and the core liquid are respectively injected into the same spinneret through the casting liquid channel and the core liquid channel through a gear pump, and a hollow tubular liquid membrane is extruded through the casting liquid port and the core liquid port of the same spinneret. The hollow tubular liquid membrane is sequentially passed through an air section, a coagulation tank, and a soaking tank to obtain hollow fiber membrane filaments. The hollow fiber membrane filaments are sequentially soaked in water and glycerol and then dried to obtain a polyethersulfone hollow fiber ultrafiltration membrane.

[0016] Specifically, the hollow tubular liquid membrane passes through the air section height and enters the coagulation tank for solidification, and then is immersed in a constant temperature to remove the solvent to obtain the hollow fiber membrane filaments, and the hollow fiber membrane filaments are immersed in water and glycerol in turn and then dried in the air to obtain the polyethersulfone hollow fiber ultrafiltration membrane.

[0017] In the step of "preparing a sultone stock solution", the mass ratio of sultone to aluminum chloride or tin chloride is 4:3 to 100:1.

[0018] In the step of "preparing a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane", the polyethersulfone hollow fiber ultrafiltration membrane is placed in a reaction tank and injected with a sultone stock solution, and is placed in a constant temperature environment of 50-80°C and soaked for 0.5-24 hours. Subsequently, RO water is added to prepare a sultone solution and the solution is placed in a constant temperature environment of 50-80°C and soaked for 2-24 hours. The polyethersulfone hollow fiber ultrafiltration membrane obtained by soaking is transferred to a 0.1M-2M HCl aqueous solution and soaked for 2-24 hours. Subsequently, the polyethersulfone hollow fiber ultrafiltration membrane is transferred to a 1M NaOH aqueous solution and soaked for 2-24 hours. After that, it is washed with reverse osmosis water and soaked for 24 hours. Then, it is soaked in a 30% to 50% glycerol solution for 8-24 hours and dried in air to obtain a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane.

[0019] In some embodiments, the sultone solution contains 1-20% sultone, 0.1-15% aluminum chloride or 0.1-15% tin chloride.

[0020] The preparation method of the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane provided in this scheme has the advantages of simple formula, low material and production cost, simple process operation, and easy large-scale production. It can be widely used in the fields of household water purification, seawater desalination, and industrial wastewater treatment.

[0021] In the second aspect, the present invention provides a hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane prepared according to the preparation method of the hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane, wherein a sulfonic acid functional group is grafted on the surface of the polyethersulfone hollow fiber ultrafiltration membrane. It should be noted that the hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane prepared by the present invention has strong hydrophilicity, strong negative charge, strong pollution resistance, and high flux and organic matter retention.

[0022] Compared with the prior art, this technical solution has the following characteristics and beneficial effects: This scheme is to react the polyethersulfone hollow fiber ultrafiltration membrane with a sultone solution after the membrane is formed to achieve post-sulfonation, without changing the membrane formation mechanism and membrane formation process of the polyethersulfone hollow fiber ultrafiltration membrane. The sulfonic acid functional group is grafted on the polyethersulfone hollow fiber ultrafiltration membrane through the sulfonation post-treatment process, thereby improving the hydrophilicity of the polyethersulfone hollow fiber ultrafiltration membrane. In addition, this scheme ingeniously uses the sultone solution obtained by sultone configuration to sulfonate the polyethersulfone hollow fiber ultrafiltration membrane, which has the advantages of simple process, simple formula and high controllability. The polyethersulfone hollow fiber ultrafiltration membrane sulfonated in this way has the advantages of high hydrophilicity and uniform distribution, and can be widely promoted and applied in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 and Figure 2 This is a membrane fiber morphology picture of the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane prepared in Example 1 of the present scheme.

[0024] Figure 3 It is a comparison chart of the sulfonation degree of the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane prepared in Example 1 and Comparative Example 1.

[0025] Figure 4 It is a comparison chart of the membrane flux of the hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane prepared in Example 3 and Comparative Example 2 changing with time. DETAILED DESCRIPTION

[0026] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0027] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0028] Embodiment 1 1. Preparation of polyethersulfone hollow fiber ultrafiltration membrane: Prepare casting film liquid: according to weight proportion, take 18 parts of polyethersulfone, 30 parts of diethylene glycol as non-solvent, 2 parts of polyethylene glycol and 50 parts of N, N-dimethylformamide in a reaction kettle and stir and dissolve them at a temperature of 50°C. After 24 hours, vacuum degassing is performed for 12 hours to obtain a homogeneous casting film liquid; Prepare the core liquid: according to the weight ratio, take 80 parts of N, N-dimethylformamide and 20 parts of water in a reaction kettle, stir and dissolve them at room temperature for 4 hours to obtain the core liquid; Preparation of polyethersulfone hollow fiber ultrafiltration membrane: The feed liquid and the core liquid are respectively injected into a spinneret through the casting liquid channel and the core liquid channel through a gear pump, and a hollow tubular liquid membrane is extruded through the casting liquid port and the core liquid port of the spinneret. Then, the liquid membrane passes through an air gap of 10 cm, passes through two coagulation baths in succession, and is wound on a winding wheel, and phase changes to form a hollow fiber ultrafiltration membrane filament. The inner and outer diameters of the polyethersulfone hollow fiber ultrafiltration membrane filament obtained after post-treatment are 0.7 / 1.3 mm.

[0029] 2. Sulfonation treatment of polyethersulfone hollow fiber ultrafiltration membrane: 1) Prepare a sultone stock solution, wherein the mass ratio of sultone to AlCl3 is 100:1; 2) Place the polyethersulfone hollow fiber ultrafiltration membrane into the reaction tank and inject the prepared sultone stock solution; keep the temperature at 60°C and soak for 0.5 hours; 3) Add RO water to prepare a sultone solution, in which the mass ratio of sultone is 10% and the mass ratio of AlCl3 is 0.1%, keep the temperature at 60℃, and soak for 8 hours; 4) Prepare 0.1M HCl aqueous solution, transfer the sulfonated membrane fibers into it, and soak for 12 hours; 5) Prepare 1M sodium hydroxide solution to clean the membrane fibers and soak for 24 hours; 6) Wash and soak in reverse osmosis water for 24 hours; 7) Take out the membrane fibers, soak them in 50% glycerol solution for 12 hours, and dry them in the air.

[0030] The prepared hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane was characterized for performance, and its main performance parameters were: the outer diameter of the membrane was 1.3 mm, the inner diameter was 0.7 mm, the retention rate of polyethylene glycol with a molecular weight of 10,000 Dalton was 91%, the contact angle was 40-45°, and the pure water flux was about 650 LMH / bar@25°C. The hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane obtained in Example 1 was characterized for morphology, and the following was obtained: Figure 1 and Figure 2 The shape shown.

[0031] Embodiment 2 1. Preparation of polyethersulfone hollow fiber ultrafiltration membrane: Prepare casting film liquid: according to weight proportion, take 18 parts of polyethersulfone, 30 parts of non-solvent, 2 parts of dimethylacetamide and 50 parts of polyvinylpyrrolidone in a reaction kettle and stir and dissolve at a temperature of 50°C. After 24 hours, vacuum degassing is performed for 12 hours to obtain a homogeneous casting film liquid; Prepare the core liquid: according to the weight ratio, take 80 parts of N-methylpyrrolidone and 20 parts of ethanol in a reaction kettle, stir and dissolve them at room temperature for 4 hours to obtain the core liquid; Preparation of polyethersulfone hollow fiber ultrafiltration membrane: The feed liquid and the core liquid are respectively injected into a spinneret through the casting liquid channel and the core liquid channel through a gear pump, and a hollow tubular liquid membrane is extruded through the casting liquid port and the core liquid port of the spinneret. Then, the liquid membrane passes through an air gap of 10 cm, passes through two coagulation baths in succession, and is wound on a winding wheel, and phase changes to form a hollow fiber ultrafiltration membrane filament. The inner and outer diameters of the polyethersulfone hollow fiber ultrafiltration membrane filament obtained after post-treatment are 0.7 / 1.3 mm.

[0032] 2. Sulfonation treatment of polyethersulfone hollow fiber ultrafiltration membrane: 1) Prepare a sultone stock solution, wherein the mass ratio of sultone to SnCl2 is 15:2; 2) Place the polyethersulfone hollow fiber ultrafiltration membrane into the reaction tank and inject the prepared sultone stock solution; keep the temperature at 60°C and soak for 0.5 hours; 3) Add RO water to prepare a sultone solution, in which the mass ratio of sultone is 15% and the mass ratio of SnCl2 is 2%, keep the temperature at 60℃, and soak for 8 hours; 4) Prepare 0.1M HCl aqueous solution, transfer the sulfonated membrane fibers into it, and soak for 12 hours; 5) Prepare 1M sodium hydroxide solution to clean the membrane fibers and soak for 24 hours; 6) Wash and soak in reverse osmosis water for 24 hours; 7) Take out the membrane fibers, soak them in 50% glycerol solution for 12 hours, and dry them in the air.

[0033] The performance of the prepared hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane was characterized, and its main performance parameters were: the outer diameter of the membrane fiber was 1.3 mm, the inner diameter was 0.7 mm, the retention rate of polyethylene glycol with a molecular weight of 10,000 Dalton was 90%, the contact angle was 30~35°, and the pure water flux was about 600LMH / bar@25°C.

[0034] Embodiment 3 1. Preparation of polyethersulfone hollow fiber ultrafiltration membrane: the same as in Example 1; 2. Sulfonation treatment of polyethersulfone hollow fiber ultrafiltration membrane: 1) Prepare a sultone stock solution, wherein the mass ratio of sultone to SnCl2 is 30:1; 2) Place the polyethersulfone hollow fiber ultrafiltration membrane into the reaction tank and inject the prepared sultone stock solution; keep the temperature at 60°C and soak for 0.5 hours; 3) Add RO water to prepare a sultone solution, in which the mass ratio of sultone is 15%, the mass ratio of SnCl2 is 0.5%, the temperature is kept at 60℃, and soak for 8 hours; 4) Prepare 0.5M HCl aqueous solution, transfer the sulfonated membrane fibers into it, and soak for 24 hours; 5) Prepare 1M sodium hydroxide solution to clean the membrane fibers and soak for 24 hours; 6) Wash and soak in reverse osmosis water for 24 hours; 7) The membrane fibers were taken out, immersed in a 50% glycerol solution for 12 hours, and air-dried to obtain a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane.

[0035] The prepared hydrophilic modified polyethersulfone hollow fiber ultrafiltration membrane was characterized: its main performance parameters are: the outer diameter of the membrane fiber is 1.3mm, the inner diameter is 0.7mm, the retention of polyethylene glycol with a molecular weight of 10,000 Dalton is 90%, the contact angle is 30~35°, and the pure water flux is about 700LMH / bar@25℃.

[0036] Embodiment 4 1. Preparation of polyethersulfone hollow fiber ultrafiltration membrane: the same as in Example 1; 2. Sulfonation treatment of polyethersulfone hollow fiber ultrafiltration membrane: 1) Prepare a sultone stock solution, wherein the mass ratio of sultone to AlCl3 is 20:1; 2) Place the polyethersulfone hollow fiber ultrafiltration membrane into the reaction tank and inject the prepared sultone stock solution; keep the temperature at 60°C and soak for 0.5 hours; 3) Add RO water to prepare a sultone solution, including 20% ​​sultone and 1% AlCl, keep the temperature at 60℃, and soak for 8 hours; 4) Prepare 0.1M HCl aqueous solution, transfer the sulfonated membrane fibers into it, and soak for 24 hours; 5) Prepare 1M sodium hydroxide solution to clean the membrane fibers and soak for 24 hours; 6) Wash and soak in reverse osmosis water for 24 hours; 7) The membrane fibers were taken out, immersed in a 50% glycerol solution for 12 hours, and air-dried to obtain a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane.

[0037] The prepared hollow fiber membrane was characterized, and its main performance parameters were: the outer diameter of the membrane fiber was 1.3 mm, the inner diameter was 0.7 mm, the retention rate of polyethylene glycol with a molecular weight of 10,000 Dalton was 90%, the contact angle was 30~35°, and the pure water flux was about 700LMH / bar@25°C.

[0038] Embodiment 5 1. Preparation of polyethersulfone hollow fiber ultrafiltration membrane: the same as in Example 1; 2. Sulfonation treatment of polyethersulfone hollow fiber ultrafiltration membrane: 1) Prepare a sultone stock solution, wherein the mass ratio of sultone to SnCl2 is 10:1; 2) Place the polyethersulfone hollow fiber ultrafiltration membrane into the reaction tank and inject the prepared sultone stock solution; keep the temperature at 70°C and soak for 0.5 hours; 3) Add RO water to prepare a sultone solution, in which the mass ratio of sultone is 20% and the mass ratio of SnCl2 is 2%, keep the temperature at 70℃, and soak for 8 hours; 4) Prepare 0.5M HCl aqueous solution, transfer the sulfonated membrane fibers into it, and soak for 24 hours; 5) Prepare 1M sodium hydroxide solution to clean the membrane fibers and soak for 24 hours; 6) Wash and soak in reverse osmosis water for 24 hours; 7) The membrane fibers were taken out, immersed in a 50% glycerol solution for 12 hours, and dried in air to characterize the prepared hollow fiber membrane. Its main performance parameters were as follows: the outer diameter of the membrane fibers was 1.3 mm, the inner diameter was 0.7 mm, the retention rate of polyethylene glycol with a molecular weight of 10,000 Daltons was 92%, the contact angle was 30-35°, and the pure water flux was about 750 LMH / bar@25°C.

[0039] Comparative Example 1 1. Preparation of polyethersulfone hollow fiber ultrafiltration membrane: Prepare the casting solution: according to the weight ratio, take 18 parts of polyethersulfone, 30 parts of diethylene glycol as a non-solvent, 2 parts of polyethylene glycol and 50 parts of N, N-dimethylformamide in a reaction kettle at a temperature of 50 ℃, stirred and dissolved, after 24 hours, vacuum degassing for 12 hours, to obtain a homogeneous casting film feed liquid; prepare the core liquid: according to the weight ratio, take 80 parts of N, N-dimethylformamide and 20 parts of water in the reactor in turn, stir and dissolve at room temperature for 4 hours, and obtain the core liquid; prepare the polyethersulfone hollow fiber ultrafiltration membrane: the feed liquid and the core liquid are respectively injected into a spinneret through the casting film liquid channel and the core liquid channel through a gear pump, and a hollow tubular liquid membrane is extruded through the casting film liquid port and the core liquid port of the spinneret. Then, the liquid membrane passes through an air gap of 10cm and passes through two coagulation baths successively, and then is wound on a winding wheel, and phase changes to form a hollow fiber ultrafiltration membrane silk. The inner and outer diameters of the polyethersulfone hollow fiber ultrafiltration membrane silk obtained after post-treatment are 0.7 / 1.3mm.

[0040] 2. Sulfonation treatment of polyethersulfone hollow fiber ultrafiltration membrane: prepare sulfuric acid aqueous solution, in which the concentration of sulfuric acid is 40%; the concentration of acetic acid is 2%, and stir evenly; put the polyethersulfone membrane filaments into the reaction tank, inject the prepared sulfuric acid mixed solution, put the polyethersulfone membrane filaments into the reaction tank, inject the prepared sulfuric acid mixed solution; prepare 1M sodium hydroxide solution to clean the membrane filaments, soak for 24 hours, and drain the sulfuric acid mixed solution; wash and soak with reverse osmosis water for 24 hours; take out the membrane filaments, soak in 50% glycerol solution for 12 hours, and dry in the air to obtain a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane.

[0041] The prepared hollow fiber membrane was characterized, and its main performance parameters were: the outer diameter of the membrane fiber was 1.3 mm, the inner diameter was 0.7 mm, the retention rate of polyethylene glycol with a molecular weight of 10,000 Dalton was 91%, the contact angle was 50~55°, and the pure water flux was about 550LMH / bar@25°C.

[0042] Comparative Example 2 1. Preparation of polyethersulfone hollow fiber ultrafiltration membrane: Prepare the casting solution: according to the weight ratio, take 18 parts of polyethersulfone, 30 parts of diethylene glycol as a non-solvent, 2 parts of polyethylene glycol and 50 parts of N, N-dimethylformamide in a reaction kettle at a temperature of 50 o C, stirred and dissolved, after 24 hours, vacuum degassing for 12 hours to obtain a homogeneous film casting solution; Prepare the core liquid: according to the weight ratio, take 80 parts of dimethylformamide and 20 parts of water in a reaction kettle, stir and dissolve them at room temperature for 4 hours to obtain the core liquid; Preparation of polyethersulfone hollow fiber ultrafiltration membrane: The feed liquid and the core liquid are respectively injected into a spinneret through the casting liquid channel and the core liquid channel through a gear pump, and a hollow tubular liquid membrane is extruded through the casting liquid port and the core liquid port of the spinneret. Then, the liquid membrane passes through an air gap of 10 cm, passes through two coagulation baths in succession, and is wound on a winding wheel, and phase changes to form a hollow fiber ultrafiltration membrane filament. The inner and outer diameters of the polyethersulfone hollow fiber ultrafiltration membrane filament obtained after post-treatment are 0.7 / 1.3 mm.

[0043] The prepared hollow fiber membrane was characterized, and its main performance parameters were: the outer diameter of the membrane fiber was 1.3 mm, the inner diameter was 0.7 mm, the retention rate of polyethylene glycol with a molecular weight of 10,000 Dalton was 90%, the contact angle was 70~76°, and the pure water flux was about 400LMH / bar@25°C.

[0044] Performance comparison test 1: The polyethersulfone hollow fiber ultrafiltration membranes of Example 1 and Comparative Example 1 were compared for sulfonation degree, wherein the sulfonation degree was tested by a standard titration method and calculated by the following formula: DS=0.232 M (NaOH) x V (NaOH) / (W-0.08M (NaOH) x V (NaOH)) x 100%.

[0045] The obtained schematic diagram of the comparison of the sulfonation degree of Example 1 and Comparative Example 1 is as follows: Figure 3 As shown by Figure 3 It can be seen that the sulfonation degree of the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane obtained in Example 1 is higher than that in Comparative Example 2, but the molding time is longer.

[0046] Performance comparison test 2: The membrane fibers obtained in Example 3 and Comparative Example 2 were made into 2-inch modules, and a membrane fouling comparison experiment was conducted under a constant flux scheme using industrial wastewater as raw water. The relationship between the membrane flux and time of raw water passing through Example 3 and Comparative Example 2 is shown in the figure. Figure 4 As shown in the figure, the flux decline rate of the sulfonated modified membrane is slower than that of the unmodified membrane. The modified membrane achieved a higher flux recovery rate, and during the RO water washing process, the unmodified membrane only recovered to 94LMH at the end of the experiment, while the modified membrane could recover to 123LMH.

[0047] In addition, the performance tests of the hollow fiber ultrafiltration membranes of Example 1 to Comparative Example 2 were conducted on an ultrafiltration membrane testing device. The diameter of the membrane assembly was 15-100 mm, the length was 200-400 mm, and the effective membrane area was 0.09-2.5 m 2 Since the dense selective layer is located on the outside of the hollow fiber membrane, the raw solution circulates through the outer cavity side of the membrane module at a membrane inlet pressure of 1 bar, and the produced water flows out from the inner cavity side of the membrane module. First, deionized water is used as the raw water solution to obtain the pure water permeability PWP of the composite membrane: Where F is the permeation flux (l / m 2 h), ΔP is the transmembrane pressure drop (bar), Q is the volume permeation flow rate (l / h), A is the effective membrane filtration area (m 2 ).

[0048] After about 1 hour of deionized water rinsing, the membrane flux reached a constant, and the hollow fiber membrane was filtered with various raw aqueous solutions, including different organic standard solutions to estimate the pore size, characterize the charge properties and evaluate the retention rate. The flux and retention rate of each raw aqueous solution were measured accordingly. The solute retention rate R (%) was calculated according to the following formula: Where: C p is the retention molecular content in the permeate (mg / L); C f is the retention molecule content in the test solution (mg / L).

[0049] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A method for preparing a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane, characterized in that: The following steps are involved: S1: preparing a film casting liquid: mixing and dissolving a polyethersulfone polymer, a non-solvent, a film casting solvent and a film casting aid to obtain a film casting liquid; S2: preparing the core liquid: mixing and dissolving the core liquid solvent and the core liquid non-solvent to obtain the core liquid; S3: preparing a polyethersulfone hollow fiber ultrafiltration membrane: injecting a casting liquid and a core liquid into the same spinneret to extrude a hollow tubular liquid membrane, and curing, cleaning and drying the hollow tubular liquid membrane to obtain a polyethersulfone hollow fiber ultrafiltration membrane; S4: preparing a sultone stock solution: mixing sultone and aluminum chloride or tin chloride in a set ratio to obtain a sultone stock solution; S5: Preparation of hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane: soak the polyethersulfone hollow fiber ultrafiltration membrane in a sultone stock solution for a set period of time, then add RO water to prepare a sultone solution and continue soaking for a set time, then transfer to an acidic environment and an alkaline environment for cleaning, take out and dry to obtain a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane.

2. The method for preparing the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane according to claim 1, characterized in that: The polyethersulfone polymer is selected as one of polyether polymer or polyethersulfone polymer, the casting solvent is selected as at least one of N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone, and the casting aid is selected as at least one of polyethylene glycol and polyvinylpyrrolidone.

3. The method for preparing the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane according to claim 1, characterized in that: The core liquid solvent is selected as one of N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone, and the core liquid non-solvent is selected as one of water and ethanol.

4. The method for preparing the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane according to claim 1, characterized in that: The mass ratio of sultone to aluminum chloride or tin chloride is 4:3~100:

1.

5. The method for preparing the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane according to claim 1, characterized in that: The polyethersulfone hollow fiber ultrafiltration membrane is placed in a reaction tank and injected with sultone stock solution, and is placed in a constant temperature environment of 50-80°C and soaked for 0.5-24 hours. Subsequently, RO water is added to prepare a sultone solution and the solution is placed in a constant temperature environment of 50-80°C and soaked for 2-24 hours. The polyethersulfone hollow fiber ultrafiltration membrane obtained by soaking is transferred to a 0.1M-2M HCl aqueous solution and soaked for 2-24 hours. Subsequently, it is transferred to a 1M NaOH aqueous solution and soaked for 2-24 hours, and then washed with reverse osmosis water, soaked for 24 hours, and then soaked in a 30%-50% glycerol solution for 8-24 hours, and dried in air to obtain a hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane.

6. The method for preparing the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane according to claim 1, characterized in that: The sultone solution contains 1-20% sultone, 0.1-15% aluminum chloride or 0.1-15% tin chloride.

7. A hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane, characterized in that: The membrane is prepared according to the method for preparing the hydrophilically modified polyethersulfone hollow fiber ultrafiltration membrane according to any one of claims 1 to 6.

8. The polyethersulfone hollow fiber ultrafiltration membrane according to claim 7, characterized in that: Applied in household water purification, seawater desalination and industrial wastewater treatment.

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