A method for preparing a high permeability hollow fiber ultrafiltration membrane with a twisted structure alloy

Abstract

The application relates to the field of high-molecular polymer materials, and particularly discloses a preparation method of a high-penetration alloy hollow fiber ultrafiltration membrane with a twist structure, which comprises the following steps: (1) preparation of a twist structure-containing polyarylether sulfone; (2) preparation of a casting solution; and (3) preparation of the alloy hollow fiber ultrafiltration membrane.The high-penetration alloy hollow fiber ultrafiltration membrane prepared by the method adopts twist structure-containing rigid S-PAES, hydrophobic fluorine-containing S-PAES is blended with hydrophilic PVP, after the casting solution is solidified into a hollow fiber membrane form, specific hydrophilic holding post-processing is adopted, chemical reactions between groups are used to form stable covalent structures between the hydrophilic polymers, and the hydrophilic durability of the alloy ultrafiltration membrane is maintained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular polymer materials, and particularly relates to a preparation method of a high-permeability twisted-structure-containing alloy hollow fiber ultrafiltration membrane, and belongs to the field of membrane technology. BACKGROUND

[0002] Hollow fiber membranes are new membrane technology products formed by the cross of functional fiber materials and separation membrane technology, and are one of the new membrane technology products with the fastest development, the largest scale and the highest output value in the field of separation membranes. The hollow fiber membranes are widely used in the fields of petroleum chemical industry, medicine, biology, energy and the like, and are one of the common key technologies for solving the global water resource crisis, environmental pollution, human organ diseases and other major problems.

[0003] Compared with flat membranes, hollow fiber membranes have unique advantages such as simplified membrane module, high membrane area, self-supporting structure and easy handling. Among them, the hollow fiber ultrafiltration membrane technology has been widely applied and developed in the field of water treatment. However, in the actual operation process, the ultrafiltration membrane will be blocked by pollution along with the limitation of water quality and other conditions. Therefore, the membrane needs to be cleaned, and the loss caused by frequent cleaning has become a major obstacle to the further popularization and application of ultrafiltration technology. At present, the membrane materials of the ultrafiltration membrane mainly include polysulfone (PS), polyether sulfone (PES), polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF), and the single-component ultrafiltration membrane has certain defects in the use process, such as low flux, low molecular retention rate and easy pollution.

[0004] From the perspective of molecular design, designing new special materials for ultrafiltration membranes is one of the important means to achieve high flux, high molecular retention rate and anti-pollution performance. Among them, polyarylether sulfone is an important high-performance engineering plastic. If specific functional unit segments such as twisted structures are introduced into the main chain structure of polyether sulfone, the flux of the ultrafiltration membrane can be improved. For example, constructing a self-microporous structure as the base material of the ultrafiltration membrane. It is reported that the self-microporous material is a material with a large number of micropores (pore size less than 2 nm) itself, and the microporosity comes from the rigid and twisted structure in its molecular chain segment. During the membrane forming process, the dense arrangement of the polymer chain is prevented due to the twisted structure of the main chain, thereby generating a large number of micropores (Progress in Polymer Science, 137 (2023), 101636). Currently, such materials have been studied and applied in gas separation and organic solvent separation, fully embodying the superiority of the membrane structure and its performance. Generally, the self-microporous material itself has strong hydrophobicity. In order to overcome the defects of hydrophobicity and easy pollution in practical application, the membrane material must be modified while maintaining the original advantages such as heat resistance, chemical stability and high mechanical strength.

[0005] Currently, the main methods for hydrophilic modification of ultrafiltration membrane materials are as follows: (1) chemical modification. The modification is achieved by copolymerization, grafting, plasma surface polymerization and interfacial polycondensation. Such chemical modification is valued for its long-term stability, although the film forming and hydrophilic modification and reaction conditions are often harsh and the cost is high. (2) Physical modification. The modification is achieved by blending modification of the base and surface coating modification. Surface coating modification is a common method in physical modification, which is simple and easy to operate, but there are still characteristics such as the hydrophilic layer being easy to peel off or even fall off from the bottom layer material, resulting in the difficulty of maintaining the hydrophilicity of the membrane material. The polymer blending method is relatively simple and has good operability, and is one of the most commonly used important methods (Journal of Membrane Science, 586 (2019), 53-83). SUMMARY

[0006] The technical problem to be solved by the present application is to provide a preparation method of a high-penetration twist-structure-containing alloy hollow fiber ultrafiltration membrane.

[0007] To solve the above problems, the present application adopts the following technical scheme:

[0008] A preparation method of a high-penetration twist-structure-containing alloy hollow fiber ultrafiltration membrane, comprising the following steps:

[0009] (1) Preparation of twist-structure-containing polyarylether sulfone

[0010] A twisted structure-containing polyarylether sulfone S-PAES (VI) is obtained by solvent co-condensation of 4,4'-difluorodiphenyl sulfone monomer (I), 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer (II) and 3,3,3',3'-tetramethyl-2,2',3,3'-tetrahydro-1,1'-spirobi[indan]-6,6'-diol monomer (III); wherein the ratio of the total amount of substance of monomer (II) and monomer (III) to the amount of substance of monomer (I) is 1:1, and the molar ratio of monomer (III) to monomer (II) is m:100-m=100%-5%:0%-95%; the number average molecular weight Mn of the twisted structure-containing polyarylether sulfone S-PAES is 50000-150000;

[0011]

[0012]

[0013]

[0014]

[0015] (2) Preparation of casting solution

[0016] S-PAES, polyvinylpyrrolidone PVP, solvent and additives are placed in a batching container in sequence, and then each component is fully stirred and dissolved at a temperature of 20-110°C for 12-36 hours until a homogeneous solution is formed. After filtration through a stainless steel filter screen, vacuum or static defoaming, the blended polymer casting solution is prepared by placing and aging.

[0017] (3) Preparation of alloy hollow fiber ultrafiltration membrane

[0018] 1) The alloy casting solution prepared in step (2) is extruded through a spinneret by a metering pump, and after passing through an air gap of 1-20 cm, it is vertically immersed into a gel bath at 20-80°C for phase separation and solidification. The winding speed of the yarn guide wheel is 5-20 m / min, and the core liquid is pure water or an aqueous solution containing 5-50% organic solvent by mass concentration, forming a nascent hollow fiber ultrafiltration membrane;

[0019] 2) The hollow fiber ultrafiltration membrane prepared in step 1) is immersed in deionized water at 10-30°C for 24-48 hours for setting, and rinsed with clean water to remove residual solvents and additives, forming a set ultrafiltration membrane;

[0020] 3) soaking the shaped ultrafiltration membrane prepared in step 2) in a post-treatment solution with a mass concentration of 0.1-20% at 25-85°C for 0.5-36 hours to perform a hydrophilic retention treatment, thereby obtaining a S-PAES / PVP alloy hollow fiber ultrafiltration membrane with permanent hydrophilicity.

[0021] Further, in step (1), the molar ratio of the monomer (III) and the monomer (II) is m:100-m=80%-30%:20%-70%; preferably: 70%:30%.

[0022] Further, in step (2), the raw materials are weighed according to the following proportions: S-PAES 5-30 parts, polyvinylpyrrolidone PVP 0.1-25 parts, additives 0-25 parts, and solvent 30-95 parts.

[0023] Further, in step (2), the raw materials are weighed according to the following proportions: S-PAES 15-25 parts, PVP 1-10 parts, additives 0.5-10 parts, and solvent 50-80 parts.

[0024] Further, the intrinsic viscosity of the S-PAES / PVP is in the range of 0.5-1.0; and the grade of the PVP is one of K85, K90, or K120, or any combination thereof.

[0025] Further, the solvent used is one or more of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP).

[0026] Further, the additive used is one or more of pure water, polyethylene glycol, oxalic acid, and water-soluble inorganic salt; and the water-soluble inorganic salt is at least one of lithium chloride and lithium nitrate.

[0027] Further, in step 3), the post-treatment reagent includes hydrogen peroxide and persulfate; the persulfate includes one or more of sodium persulfate, ammonium persulfate, and potassium persulfate; the mass concentration of the post-treatment reagent is 0.1-20%, preferably 1-10%; the post-treatment temperature is in the range of 20-95°C, preferably 25-90°C; and the post-treatment time is 0.5-48 hours, preferably 1-24 hours.

[0028] Further, the intrinsic viscosity of the S-PAES is in the range of 0.7-0.9.

[0029] Further, the intrinsic viscosity of the S-PAES / PVP casting solution is in the range of 0.4-1.0, preferably 0.7-0.9.

[0030] Compared with the prior art, the high-permeability twisted structure-containing alloy hollow fiber membrane prepared by the application has the following advantages:

[0031] 1) The high-permeability alloy hollow fiber ultrafiltration membrane described in the application adopts rigid S-PAES containing a twisted structure. Due to the special spiro-indane twisted structure and rigid structure in the main chain, the stacking of part of the polymer molecular chain segments at the molecular scale is hindered during the membrane forming process, so that the alloy ultrafiltration membrane has micropores by itself, and the water flux is significantly improved.

[0032] 2) The high-permeability alloy hollow fiber ultrafiltration membrane described in the application adopts hydrophobic fluorine-containing S-PAES and hydrophilic PVP blending. Based on the high molecular weight and good compatibility of the two, chain segment entanglement at the molecular level can be formed, and the thermodynamic stability of the binary blending system is strengthened. Therefore, it has good thermal, mechanical and chemical stability, and also has good anti-pollution ability.

[0033] 3) The high-permeability alloy hollow fiber ultrafiltration membrane described in the application adopts a certain concentration of sodium persulfate solution to treat the solid-state ultrafiltration membrane after phase transition, so that chemical reactions occur between the groups on the hydrophilic PVP molecular chain to form stable covalent structures, effectively inhibiting the excessive swelling of PVP and the loss of PVP molecules during use, and ensuring the long-term hydrophilicity of the membrane. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 SEM cross-sectional structure diagram of the S-PAES / PVP alloy hollow fiber ultrafiltration membrane prepared in Example 1;

[0035] Figure 2 SEM external surface structure diagram of the S-PAES / PVP alloy hollow fiber ultrafiltration membrane prepared in Example 1;

[0036] Figure 3 SEM internal surface structure diagram of the S-PAES / PVP alloy hollow fiber ultrafiltration membrane prepared in Example 1. DETAILED DESCRIPTION

[0037] In order to further illustrate the technical solutions of the application, the preferred embodiments of the application are described below in combination with specific examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the application, and are not a limitation on the claims of the application.

[0038] Example 1:

[0039] 1) Preparation of polymer:

[0040] Into a 250 mL three-necked round flask equipped with a water separator, 50.8041 g (200 mmol) of 4,4'-difluorodiphenyl sulfone monomer, 20.1768 g (60 mmol) of 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer and 43.1779 g (140 mmol) of 3,3,3',3'-tetramethyl-2,2',3,3'-tetrahydro-1,1'-spirobis[indan]-6,6'-diol monomer were added one by one with DMAc (500 mL) as solvent, 56 g of K2CO3 and 200 mL of toluene were added as catalyst and water carrying agent respectively. Under N2 atmosphere, the reaction was carried out at 155°C for 12 h and then at 165°C for 12 h. When the solution was cooled to room temperature, it was poured into 400 mL of ethanol, and the precipitate was flocculated under high speed stirring. After separation by suction filtration, a white solid was obtained, which was repeatedly washed with ethanol and water, and dried at 80°C under vacuum for 20 h to obtain 208.1 g of poly(arylene ether sulfone) containing twisted structure (S-PAES) with a number average molecular weight Mn = 129200.

[0041] 2) Preparation of casting solution:

[0042] 200 g of S-PAES and 40 g of PVP (K90) were weighed into a mixed solvent of 860 g of DMAc and 30 g of pure water, and stirred at 60°C for 24 h to form a homogeneous casting solution. The casting solution was filtered through a stainless steel filter screen and placed in a tank at a temperature of 60°C for vacuum degassing for 6 h, and then sealed for use. The intrinsic viscosity was measured to be 0.83.

[0043] 3) Preparation of hollow fiber ultrafiltration membrane:

[0044] Spinning process conditions: phase inversion process was used, the air gap was 2 cm, the spinning speed was 8 m / min, the gel bath temperature was 60°C, the composition of the coagulation bath was water, and the core liquid was pure water. The casting solution was extruded through the spinneret, passed through a 2 cm air gap, and then vertically immersed in a 60°C gel bath to separate and solidify, and then introduced into the receiving tank through a winding wheel with a speed of 12 m / min, and the core liquid was pure water, to form the primary hollow fiber ultrafiltration membrane. The primary hollow fiber membrane was immersed in deionized water at 25°C for 48 h for setting, and then washed with clean water. After washing, the membrane was immersed in an 8% sodium persulfate solution for 5 h at 80°C for hydrophilic retention treatment, to obtain the hollow fiber ultrafiltration membrane.

[0045] 4) Characterization of hollow fiber ultrafiltration membrane:

[0046] Property test: SEM was used to observe the cross-sectional morphology of the membrane, which showed a sponge-like structure with dense inner and outer skin layers. The inner diameter of the membrane was about 900 μm, and the outer diameter was about 1500 μm. The breaking strength of the membrane was 21.2 MPa.

[0047] Performance test: temperature is 25℃, transmembrane pressure difference is 0.1 MPa, bovine serum albumin (BSA) is the pollution simulation object: 1000 mg / L. The pure water flux of the membrane is 530 L / (m 2 ·h), and the membrane flux is 201 L / (m 2 ·h) after 4 hours of BSA filtration. The rejection rate of BSA is 92.1%. (Test method, see literature report Journal of Membrane Science 659 (2022) 120779).

[0048] Example 2:

[0049] 1) Preparation of polymer: the same preparation process as in Example 1 is adopted.

[0050] 2) Preparation of casting solution:

[0051] 240 grams of S-PAES is weighed into 890 grams of DMAc solvent, stirred at 60℃ for 24 hours to form a homogeneous casting solution. The casting solution is filtered through a stainless steel filter screen and placed in a tank at a temperature of 60℃ for vacuum degassing for 6 hours, and then sealed for use. The intrinsic viscosity is 0.78.

[0052] 3) Preparation of hollow fiber ultrafiltration membrane:

[0053] Spinning process conditions: phase inversion process is adopted, air gap is 2 cm, spinning speed is 12 m / min, gel bath temperature is 60℃, coagulation bath composition is water, and core liquid is pure water. The casting solution is extruded through the spinneret, passes through a 2 cm air gap, and then vertically immerses into a 60℃ gel bath to separate and solidify, and then is introduced into a wire collecting tank at a speed of 12 m / min, the core liquid composition is pure water, and a nascent hollow fiber ultrafiltration membrane is formed. The nascent hollow fiber membrane is immersed in deionized water at 25℃ for 48 hours for setting, and then is washed with clean water. After washing, the membrane is immersed in an 8% sodium persulfate solution for 5 hours at 80℃ for hydrophilic retention treatment, and a hollow fiber ultrafiltration membrane is obtained.

[0054] 4) Characterization of hollow fiber ultrafiltration membrane:

[0055] Property test: SEM is used to observe the cross-sectional morphology of the membrane, which presents a sponge-like structure with dense inner and outer skin layers. The inner diameter of the membrane is about 900 μm, and the outer diameter of the membrane is about 1500 μm. The breaking strength of the membrane is 191 MPa.

[0056] Performance test: temperature is 25℃, transmembrane pressure difference is 0.1 MPa, bovine serum albumin (BSA) is the pollution simulation object: 1000 mg / L. The pure water flux of the membrane is 378 L / (m 2• h) with a membrane flux of 158 L / (m2·h) after 4 hours of BSA filtration. 2 • h). The rejection rate of BSA was 95.1%. (Test method: see the literature report Journal of Membrane Science 659 (2022) 120779).

[0057] Example 3:

[0058] 1) Preparation of the polymer: the same preparation process as in Example 1 was used.

[0059] 2) Preparation of the casting solution:

[0060] 200 grams of S-PAES and 70 grams of PVP (K90) were weighed into a mixed solvent of 800 grams of DMAc and 30 grams of pure water, stirred at 60°C for 24 hours to form a homogeneous casting solution. The casting solution was filtered through a stainless steel filter screen and placed in a tank at a temperature of 60°C for vacuum degassing for 6 hours, and then sealed for use. The intrinsic viscosity was measured to be 0.81

[0061] 3) Preparation of the hollow fiber ultrafiltration membrane:

[0062] Spinning process conditions: phase inversion process was used, with an air gap of 5 cm, a spinning speed of 12 m / min, and a gel bath temperature of 60°C. The casting solution was extruded through the spinneret, passed through a 5 cm air gap, and then vertically immersed in a 60°C gel bath to solidify the phase, and then introduced into the coagulation bath at a speed of 12 m / min. The core liquid was pure water, and the nascent hollow fiber ultrafiltration membrane was formed. The nascent hollow fiber membrane was immersed in deionized water at 25°C for 48 hours for setting, and then washed with clean water. After washing, the membrane was immersed in an 8% sodium persulfate solution at 80°C for 5 hours for hydrophilic retention treatment, and the hollow fiber ultrafiltration membrane was obtained.

[0063] 4) Characterization of the hollow fiber ultrafiltration membrane:

[0064] Property test: SEM was used to observe the cross-sectional morphology of the membrane, which showed a sponge-like structure with dense inner and outer skin layers. The inner diameter of the membrane was about 900 μm, and the outer diameter was about 1500 μm. The breaking strength of the membrane was 19.1 MPa.

[0065] Performance test: the temperature was 25°C, the transmembrane pressure difference was 0.1 MPa, and bovine serum albumin (BSA) was used as the pollution simulation object at a concentration of 1000 mg / L. The pure water flux of the membrane was measured to be 378 L / (m 2 • h) after 4 hours of BSA filtration. 2• h). The rejection rate for BSA was 94.8%. (Test method: see literature report Journal of Membrane Science 659 (2022) 120779).

[0066] Example 4:

[0067] 1) Preparation of polymer: The same preparation process as in Example 1 was used.

[0068] 2) Preparation of casting solution:

[0069] 200 grams of S-PAES and 40 grams of PVP (K30) were weighed into a mixed solvent of 860 grams of DMAc and 30 grams of pure water, stirred at 60°C for 24 hours to form a homogeneous casting solution. The casting solution was filtered through a stainless steel filter screen and placed in a tank at a temperature of 60°C for vacuum degassing for 6 hours, and then sealed for use. The intrinsic viscosity was measured to be 0.75.

[0070] 3) Preparation of hollow fiber ultrafiltration membrane:

[0071] Spinning process conditions: The phase inversion process was used, with an air gap of 2 cm, a spinning speed of 12 m / min, and a gel bath temperature of 60°C. The casting solution was extruded through the spinneret, passed through a 2 cm air gap, and then vertically immersed in a 25°C gel bath to solidify the phase, and then introduced into the coagulation bath at a speed of 12 m / min. The core liquid was pure water, and the nascent hollow fiber ultrafiltration membrane was formed. The nascent hollow fiber membrane was immersed in deionized water at 25°C for 48 hours for setting, and then washed with clean water. After washing, the membrane was immersed in an 8% sodium persulfate solution and reacted at 80°C for 5 hours for hydrophilic retention treatment, and the hollow fiber ultrafiltration membrane was obtained.

[0072] 4) Characterization of hollow fiber ultrafiltration membrane:

[0073] Property test: SEM was used to observe the cross-sectional morphology of the membrane, which showed a sponge-like structure with dense inner and outer skin layers. The inner diameter of the membrane was about 900 μm, and the outer diameter was about 1500 μm. The breaking strength of the membrane was 20.8 MPa.

[0074] Performance test: The temperature was 25°C, the transmembrane pressure difference was 0.1 MPa, and bovine serum albumin (BSA) was used as the pollution simulation object at a concentration of 1000 mg / L. The pure water flux of the membrane was measured to be 401 L / (m 2 • h), and the membrane flux was 180 L / (m 2• h). The rejection rate for BSA was 97.1%. (Test method: see literature report Journal of Membrane Science 659 (2022) 120779).

[0075] Example 5:

[0076] 1) Preparation of polymer: The same preparation process as in Example 1 was used.

[0077] 2) Preparation of casting solution:

[0078] 240 grams of S-PAES and 50 grams of PVP (K120) were weighed into a mixed solvent of 1000 grams of DMAc and 24 grams of pure water, then 6 grams of LiNO3 was added, stirred at 60°C for 24 hours to form a homogeneous casting solution. The casting solution was filtered through a stainless steel filter screen and placed in a tank at a temperature of 60°C for vacuum degassing for 6 hours, and then sealed for use. The intrinsic viscosity was measured to be 0.88.

[0079] 3) Preparation of hollow fiber ultrafiltration membrane:

[0080] Spinning process conditions: phase inversion process was used, air gap was 10 cm, spinning speed was 12 m / min, gel bath temperature was 60°C, coagulation bath composition was water, and core liquid was pure water. The casting solution was extruded through the spinneret, passed through a 10 cm air gap, then vertically immersed in a 80°C gel bath to solidify, then introduced into the yarn tank through a winding wheel at a speed of 12 m / min, the core liquid composition was pure water, and the primary hollow fiber ultrafiltration membrane was formed. The primary hollow fiber membrane was immersed in deionized water at 25°C for 48 hours for setting, and then washed with clean water. After washing, the membrane was immersed in an 8% sodium persulfate solution and reacted at 80°C for 5 hours for hydrophilic retention treatment, and the hollow fiber ultrafiltration membrane was obtained.

[0081] 4) Characterization of hollow fiber ultrafiltration membrane:

[0082] Property test: SEM was used to observe the cross-sectional morphology of the membrane, which showed a sponge-like structure with dense inner and outer skin layers; the inner diameter of the membrane was about 900 μm; the outer diameter of the membrane was about 1500 μm. The breaking strength of the membrane was 21.4 MPa.

[0083] Performance test: the temperature was 25°C, the transmembrane pressure difference was 0.1 MPa, and bovine serum albumin (BSA) was used as the pollution simulation object: 1000 mg / L. The pure water flux of the membrane was measured to be 413 L / (m 2 • h), and the membrane flux was 260 L / (m 2• h). The rejection rate for BSA was 94.6%. (Test method: see literature report Journal of Membrane Science 659 (2022) 120779).

[0084] Example 6:

[0085] 1) Preparation of polymer: The same preparation process as in Example 1 was used.

[0086] 2) Preparation of casting solution:

[0087] 200 grams of S-PAES and 40 grams of PVP (K90) were weighed into a mixed solvent of 860 grams of DMAc and 30 grams of pure water, stirred at 60°C for 24 hours to form a homogeneous casting solution. The casting solution was filtered through a stainless steel filter screen and placed in a tank at a temperature of 60°C for vacuum degassing for 6 hours, and then sealed for use. The intrinsic viscosity was measured to be 0.83.

[0088] 3) Preparation of hollow fiber ultrafiltration membrane:

[0089] Spinning process conditions: The phase inversion process was used, with an air gap of 5 cm, a spinning speed of 12 m / min, and a gel bath temperature of 60°C. The casting solution was extruded through the spinneret, passed through a 5 cm air gap, and then vertically immersed in a 60°C gel bath to solidify the phase, and then introduced into the coagulation bath at a speed of 12 m / min. The core liquid was pure water, and the nascent hollow fiber ultrafiltration membrane was formed. The nascent hollow fiber membrane was immersed in deionized water at 25°C for 48 hours for setting, and then washed with clean water. After washing, the membrane was immersed in an 8% sodium persulfate solution at 80°C for 5 hours for hydrophilic retention treatment, and a hollow fiber ultrafiltration membrane was obtained.

[0090] 4) Characterization of hollow fiber ultrafiltration membrane:

[0091] Property test: SEM was used to observe the cross-sectional morphology of the membrane, which showed a sponge-like structure with dense inner and outer skin layers. The inner diameter of the membrane was about 900 μm, and the outer diameter was about 1500 μm. The breaking strength of the membrane was 18.3 MPa.

[0092] Performance test: The temperature was 25°C, the transmembrane pressure difference was 0.1 MPa, and bovine serum albumin (BSA) was used as the pollution simulation object at a concentration of 1000 mg / L. The pure water flux of the membrane was measured to be 180 L / (m 2 • h) after 4 hours of BSA filtration, the membrane flux was 30 L / (m 2• h). The rejection rate for BSA was 94.0%. (Test method see reported in Journal of Membrane Science 659 (2022) 120779).

[0093]

[0094]

[0095] Table 1.

Claims

1. A method for preparing a high permeability hollow fiber ultrafiltration membrane with twisted structure alloy, comprising the following steps: (1) Preparation of poly (arylene ether sulfone) with twisted structure A poly(arylene ether sulfone) S-PAES (VI) containing a twisted structure is obtained by solvent copolymerization of 4,4'-difluorodiphenyl sulfone monomer (I), 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer (II) and 3,3,3',3'-tetramethyl-2,2',3,3'-tetrahydro-1,1'-spirobis[indan]-6,6'-diol monomer (III) in DMAc as solvent, with K2CO3 and toluene added as catalyst and water carrier respectively, under N2 atmosphere; wherein, The ratio of the total amount of substance of monomer (II) and monomer (III) to the amount of substance of monomer (I) is 1:1, the molar ratio of monomer (III) to monomer (II) is m:100-m = 100%-5%:0%-95%; the number average molecular weight Mn of the poly (arylene ether sulfone) with twisted structure S-PAES is 50000-150000; （I） (II) (III) (IV) (2) Preparation of casting solution S-PAES, polyvinylpyrrolidone PVP, solvent and additive are placed in a batching container in turn, and are fully stirred and dissolved at a temperature of 20-110℃ for 12-36 hours until a homogeneous solution is formed. After filtration through a stainless steel filter screen, vacuum or static defoaming, the blended polymer casting solution is prepared by placing and aging. The solvent used is N,N-dimethylacetamide DMAc, and the additive used is lithium nitrate; (3) Preparation of alloy hollow fiber ultrafiltration membrane 1) The blended polymer casting solution prepared in step (2) is extruded through a spinneret by a metering pump, passes through an air gap of 1-20 cm, and is vertically immersed in a gel bath at 20-80℃ for phase separation and solidification. The hollow fiber ultrafiltration membrane is formed by introducing it into a yarn tank through a winding wheel at a winding speed of 5-20 m / min, wherein the core liquid is pure water or an aqueous solution containing 5-50% organic solvent by mass concentration. 2) The hollow fiber ultrafiltration membrane prepared in step 1) is immersed in deionized water at 10-30℃ for 24-48 hours for setting, and is rinsed with clean water to remove residual solvents and additives, thereby forming a set ultrafiltration membrane. 3) The set ultrafiltration membrane prepared in step 2) is immersed in a post-treatment solution with a mass concentration of 0.1-20% at 25-85℃ for 0.5-36 hours for hydrophilic retention treatment, thereby obtaining a S-PAES / PVP alloy hollow fiber ultrafiltration membrane with permanent hydrophilicity. The post-treatment solution is sodium persulfate solution, and the post-treatment reagent has a mass concentration of 0.1-20%. The post-treatment temperature ranges from 20 to 95℃, and the post-treatment time is 0.5-48 hours.

2. The method according to claim 1, wherein in step (1), the molar ratio of monomer (III) to monomer (II) is m:100-m = 80%-30%:20%-70%.

3. The method according to claim 1, wherein in step (2), the raw materials are weighed according to the following proportions: S-PAES 5-30 parts, polyvinylpyrrolidone PVP 0.1-25 parts, additive 0-25 parts, and solvent 30-95 parts.

4. The method according to claim 3, wherein in step (2), the raw materials are weighed according to the following proportions: S-PAES 15-25 parts, PVP 1-10 parts, additive 0.5-10 parts, and solvent 50-80 parts. ​ ​ ​ 5. The method of claim 1, wherein: the S-PAES / PVP has an intrinsic viscosity in the range of 0.5-1.0; and the PVP has a grade of one or any combination of K85, K90, or K120.

6. The method of claim 1, wherein: the S-PAES has an intrinsic viscosity in the range of 0.7-0.

9.

7. The method of claim 1, wherein: the S-PAES / PVP casting solution has an intrinsic viscosity in the range of 0.4-1.0.

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