Block poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane and preparation method thereof

Abstract

The invention provides a preparation method of a block poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, which comprises the following steps: adding acid into biphenyl and N-methyl-4-piperidone to react to obtain a first product; adding acid into biphenyl and 2, 2, 2-trifluoroacetophenone to react, so as to obtain a second product; adding the second product into the first product, and carrying out condensation polymerization to obtain a PBTbBP block polymer; dissolving the PBTbBP block polymer in a solvent, and defoaming to obtain a membrane casting solution; spinning the membrane casting solution and the core solution to obtain membrane filaments; and immersing the membrane filaments in a coagulating bath, and carrying out phase separation. According to the preparation method, biphenyl, a hydrophobic trifluoroacetophenone monomer and a hydrophilic N-methyl piperidone monomer are subjected to superacid catalysis Friedel-Crafts reaction and are subjected to step-by-step copolymerization to obtain the amphiphilic block polymer PBTbBP. The membrane has efficient mass transfer channels and excellent membrane surface hydrophilicity, and the separation capacity of dye molecules and salt ions and the water permeability are improved.

Description

Technical Field

[0001] The present invention relates to the field of material technology, in particular to a segmented poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane and a preparation method thereof. Background Art

[0002] Loose nanofiltration (LNF) is a pressure-driven membrane separation technology with a separation scale between ultrafiltration (UF) and reverse osmosis (RO). Its core feature is a molecular weight cutoff (MWCO) range of 500 to 2000 Da. LNF membranes offer larger pore sizes and higher permeate flux, enabling selective separations at lower operating pressures. LNF is particularly well-suited for systems that require the permeation of small molecules (such as monovalent salts) while retaining large molecules or high-valent ions. Widely used in wastewater treatment, resource recovery, and drinking water safety, it has become a crucial deep water treatment technology.

[0003] Currently, commercialized loose nanofiltration membranes are polyamide rolled composite nanofiltration membranes obtained by interfacial polymerization on the surface of a flat base membrane. These membranes have drawbacks such as complex membrane assembly preparation, difficulty in cleaning, and a long fluid flow path. Hollow fiber loose nanofiltration membranes (HF-LNF) combine the advantages of loose nanofiltration and hollow fiber membranes. Their self-supporting structure offers advantages such as high packing density, strong pollution resistance, high recovery rate, and low replacement cost, making them a hot topic in the field of loose nanofiltration membrane research.

[0004] In recent years, researchers have successfully constructed HF-LNF membranes with multiple functional properties by introducing novel functional materials such as nanocomposites and zwitterionic polymers. These membranes not only exhibit excellent molecular weight rejection selectivity (rejection rates of over 90% for small organic molecules between 200 and 1000 Da) but also possess significant salt ion permeability and anti-fouling properties. These breakthroughs have not only promoted the innovative development of HF-LNF membrane technology but also provided new insights for its application in the pharmaceutical, food, and chemical industries.

[0005] Using thin film composite technology, functional layers are constructed by coating, layer-by-layer assembly or interfacial polymerization on the surface of a porous support. Although this method can integrate new functional materials, the curvature effect of the hollow fiber ultrafiltration base membrane makes it difficult to uniformly construct the selection layer, resulting in obvious defects in the structural integrity and long-term operational stability of the nanofiltration separation layer. The traditional non-solvent induced phase separation method (NIPS) is used for direct preparation through a single-step spinning process. Current research focuses on introducing organic / inorganic nanomaterials into traditional polymer matrices, and constructing a separation membrane layer with both loose structure and surface charge characteristics by delaying the phase separation process. Although this process has the advantage of simplified process, it is limited by the inherent characteristics of traditional polymer materials, and it is difficult to achieve a significant breakthrough in membrane performance.

[0006] Therefore, how to achieve precise control of the nanofiltration layer, systematically explore the membrane structure-performance correlation mechanism, and then establish an efficient and simple preparation method to break through the bottleneck of dye / salt system separation performance has become an important topic in this field with both theoretical research value and practical application prospects. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a block poly (biphenyl-trifluoroacetophenone-biphenyl-piperidone) bicontinuous hollow fiber loose nanofiltration membrane. The bicontinuous structure of the membrane provided by the present invention improves the membrane's permeation flux and the separation efficiency of dye molecules / salt ions.

[0008] The present invention provides a method for preparing a block poly (biphenyl-trifluoroacetophenone-biphenyl-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, comprising the following steps:

[0009] A) reacting biphenyl with N-methyl-4-piperidone to obtain a first product;

[0010] Biphenyl reacts with 2,2,2-trifluoroacetophenone with acid to obtain a second product;

[0011] B) adding the second product to the first product for polycondensation to obtain a PBTbBP block polymer;

[0012] C) dissolving the PBTbBP block polymer in a solvent and degassing to obtain a casting solution;

[0013] D) spinning the casting solution and the core solution to obtain membrane filaments;

[0014] E) Immerse the membrane filaments in a coagulation bath to allow phase separation to occur.

[0015] In some specific embodiments, the temperature of the reaction of biphenyl with N-methyl-4-piperidone in step A) is 8-12° C. and the time is 0.5-1.5 h;

[0016] The temperature for the acid addition reaction of biphenyl and 2,2,2-trifluoroacetophenone is 20-30° C., and the time is 8-12 minutes.

[0017] In some specific embodiments, the acid comprises trifluoromethanesulfonic acid and / or trifluoroacetic acid;

[0018] The polycondensation reaction temperature is 10°C and the time is 7 to 10 hours;

[0019] In some specific embodiments, the

[0020] The molar ratio of the total molar amount of 2,2,2-trifluoroacetophenone and N-methyl-4-piperidone to biphenyl is 1.1:1;

[0021] The molar ratio of trifluoromethanesulfonic acid to biphenyl is 10:1;

[0022] The molar ratio of trifluoroacetic acid to biphenyl was 0.8:1.

[0023] In some specific embodiments, the solvent in step C) is

[0024] N-methylpyrrolidone; the concentration of PBTbBP block polymer in the solvent is 14 to 20 wt%;

[0025] The dissolving is performed by stirring, the stirring temperature is 70 to 90° C., and the stirring time is 10 to 14 hours; and the degassing time is 2 to 3 hours.

[0026] In some specific embodiments, the extrusion rate of the casting solution in step D) is 2 mL min -1 .

[0027] In some specific embodiments, the core liquid is water; the rate of the water is 2-3 mL min -1 ; Drying distance 5cm, using water as gel bath, spinning is carried out at 20-30℃.

[0028] In some specific embodiments, after step E), the membrane fibers are further immersed in a 10% ethanol aqueous solution for 10 to 12 hours, and then placed in glycerol for wet storage.

[0029] The present invention provides a segmented poly (biphenyl-trifluoroacetophenone-biphenyl-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, characterized in that it is prepared by the preparation method described in any one of the above technical solutions.

[0030] The present invention provides a method for separating dye molecules and salt ions, which adopts the double-continuous hollow fiber loose nanofiltration membrane described in the above technical solution.

[0031] Compared with the prior art, the present invention provides a method for preparing a block poly(biphenyl-trifluoroacetophenone-biphenyl-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, comprising the following steps: A) reacting biphenyl with N-methyl-4-piperidone by acid addition to obtain a first product; reacting biphenyl with 2,2,2-trifluoroacetophenone by acid addition to obtain a second product; B) adding the second product to the first product for polycondensation to obtain a PBTbBP block polymer; C) dissolving the PBTbBP block polymer in a solvent and degassing to obtain a casting solution; D) spinning the casting solution and core solution to obtain membrane filaments; E) immersing the membrane filaments in a coagulation bath to cause phase separation. The present invention obtains the amphiphilic block polymer PBTbBP by step-by-step copolymerization of biphenyl, a hydrophobic trifluoroacetophenone monomer, and a hydrophilic N-methylpiperidone monomer via a superacid-catalyzed Friedel-Crafts reaction. The bicontinuous hollow fiber membranes prepared using the NIPS method exhibit delayed phase separation of the block polymers, resulting in a uniform bicontinuous pore structure. The resulting hollow fiber membranes possess efficient mass transfer channels and excellent surface hydrophilicity, effectively enhancing the separation capacity of dye molecules and salt ions, as well as water permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Flow chart of the preparation of the PBTbBP hollow fiber membrane of the present invention;

[0033] Figure 2 The morphology and actual photos of the hollow fiber membranes (a) PBTbBP-5 (b) PBTbBP-10 and (c) PBTbBP-15 of the present invention;

[0034] Figure 3 This is a photo of the block polymer precipitating in water. DETAILED DESCRIPTION

[0035] The present invention provides a block poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane and a preparation method thereof. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It should be pointed out in particular that all similar replacements and modifications are obvious to those skilled in the art and they all fall within the scope of protection of the present invention. The methods and applications of the present invention have been described through preferred embodiments. Relevant personnel can obviously modify or appropriately change and combine the methods and applications of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0036] This patent addresses the low permeability and poor separation efficiency of HF-LNF membranes prepared using the NIPS method using traditional polymer materials. By synthesizing a block polymer with ordered affinity-dissipation segments, this method delays phase separation to produce a bicontinuous structure membrane. A block poly(biphenyl-trifluoroacetophenone-piperidone) polymer (PBTbBP) was successfully synthesized using a step-by-step method, and a bicontinuous hollow fiber loose nanofiltration membrane was prepared using a one-step NIPS method. This provides a method for preparing high-performance hollow fiber membranes.

[0037] The present invention provides a method for preparing a segmented poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, comprising the following steps:

[0038] A) reacting biphenyl with N-methyl-4-piperidone to obtain a first product;

[0039] Biphenyl reacts with 2,2,2-trifluoroacetophenone with acid to obtain a second product;

[0040] B) adding the second product to the first product for polycondensation to obtain a PBTbBP block polymer;

[0041] C) dissolving the PBTbBP block polymer in a solvent and degassing to obtain a casting solution;

[0042] D) spinning the casting solution and the core solution to obtain membrane filaments;

[0043] E) Immerse the membrane filaments in a coagulation bath to allow phase separation to occur.

[0044] The block poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane provided by the present invention first uses TFSA as a catalyst to perform two groups of Friedel-Crafts polycondensation reactions in CH2Cl2 solvent:

[0045] Biphenyl is reacted with N-methyl-4-piperidone with an acid to obtain a first product; biphenyl is reacted with 2,2,2-trifluoroacetophenone with an acid to obtain a second product; the second product is added to the first product for a condensation reaction to obtain a PBTbBP block polymer; in some specific embodiments, the acid includes trifluoromethanesulfonic acid and / or trifluoroacetic acid.

[0046] According to the present invention, the molar ratio of the total molar amount of 2,2,2-trifluoroacetophenone and N-methyl-4-piperidone to biphenyl is 1.1:1;

[0047] The molar ratio of trifluoromethanesulfonic acid to biphenyl is 10:1;

[0048] The molar ratio of trifluoroacetic acid to biphenyl was 0.8:1.

[0049] In some specific embodiments, the temperature for the acid addition reaction of biphenyl and N-methyl-4-piperidone is 8-12°C, specifically 8°C, 9°C, 10°C, 11°C, and 12°C; the time is 0.5-1.5h, specifically 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, and 1.5h.

[0050] The temperature for the acid addition reaction of biphenyl and 2,2,2-trifluoroacetophenone of the present invention is 20-30°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C;

[0051] The time is 8 to 12 minutes; specifically 8 minutes, 9 minutes, 10 minutes, 11 minutes, and 12 minutes.

[0052] The two reaction systems are blended and polycondensed to produce a brown, high-viscosity solution. The high-viscosity liquid is then poured into deionized water to produce a white solid PBTbBP block polymer. By optimizing the reaction temperature, reaction time, and monomer feed ratio, a series of block copolymers with precisely controlled hydrophilic segment content ranging from 0 to 100 mol% can be obtained. The polycondensation reaction temperature is 10°C, and the reaction time is 7 to 10 hours; specifically, 7 hours, 8 hours, 9 hours, or 10 hours can be used.

[0053] The PBTbBP block polymer is dissolved in a solvent and degassed to obtain a casting solution.

[0054] In some specific embodiments, the solvent is N-methylpyrrolidone; the concentration of the PBTbBP block polymer in the solvent is 14-20 wt%; specifically, it can be 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%.

[0055] The dissolving is stirring dissolving, and the stirring temperature is 70-90°C, specifically 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C.

[0056] The stirring time is 10 to 14 hours, specifically 10 hours, 11 hours, 12 hours, 13 hours, or 14 hours.

[0057] The degassing method of the present invention is vacuum degassing; the vacuum degree of the vacuum degassing is -0.1 MPa; the degassing time is 2 to 3 hours, and the vacuum filtration degassing is performed for 2 to 3 hours until the bubbles in the solution disappear.

[0058] Spinning the casting solution and the core solution to obtain membrane filaments;

[0059] In some specific embodiments, the extrusion rate of the casting solution in step D) is 2 mL min -1 .

[0060] In some specific embodiments, the core liquid is water; the rate of the water is 2-3 mL min -1 ; Drying distance 5cm, using water as gel bath, spinning is carried out at 20-30℃; specifically, it can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃.

[0061] In some specific embodiments, after step E), the membrane fibers are further immersed in a 10% ethanol aqueous solution for 10 to 12 hours, and then placed in glycerol for wet storage.

[0062] The present invention can apply the PBTbBP hollow fiber membrane to the separation of dye / water system and drug / water system.

[0063] The present invention provides a segmented poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, which is prepared by the preparation method described in any one of the above technical solutions.

[0064] The present invention provides a method for separating dye molecules and salt ions, which adopts the double-continuous hollow fiber loose nanofiltration membrane described in the above technical solution.

[0065] The invention provides a method for preparing a block poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, comprising the following steps: A) reacting biphenyl with N-methyl-4-piperidone by adding acid to obtain a first product; and reacting biphenyl with 2,2,2-trifluoroacetophenone by adding acid to obtain a second product; B) adding the second product to the first product, performing a polycondensation reaction, and obtaining a PBTbBP block polymer; C) dissolving the PBTbBP block polymer in a solvent, degassing, and obtaining a casting solution; D) spinning the casting solution and a core solution to obtain membrane filaments; and E) immersing the membrane filaments in a coagulation bath to cause phase separation, thereby obtaining the membrane.

[0066] The present invention synthesizes an amphiphilic block polymer (PBTbBP) by stepwise copolymerization of biphenyl, a hydrophobic trifluoroacetophenone monomer, and a hydrophilic N-methylpiperidone monomer via a superacid-catalyzed Friedel-Crafts reaction. A bicontinuous hollow fiber membrane is prepared using the NIPS method. The ordered microphase separation of the block polymers results in delayed phase separation, forming a uniform bicontinuous pore structure. The resulting hollow fiber membrane exhibits efficient mass transfer channels and excellent membrane surface hydrophilicity, effectively enhancing the separation capacity of dye molecules and salt ions, as well as water permeability.

[0067] It should be understood that the expression "one or more of" includes individually each of the items recited after the expression and various combinations of two or more of the recited items, unless otherwise apparent from the context and usage. The expression "and / or" in conjunction with three or more recited items should be understood to have the same meaning, unless otherwise apparent from the context.

[0068] The terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, e.g., not excluding other unrecited elements or steps, unless otherwise specifically stated or understood from the context.

[0069] In this application, the term "and / or" describes the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0070] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0071] It should be understood that the order of steps or the order in which certain actions are performed are not important as long as the present invention remains operable. Additionally, two or more steps or actions may be performed simultaneously.

[0072] The use of any and all examples or exemplary language, such as "such as" or "including," herein is intended merely to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0073] In addition, the numerical ranges and parameters used to define the present invention are approximate values. The relevant numerical values in the specific examples have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual testing methods. Therefore, unless otherwise expressly stated, all ranges, amounts, values, and percentages used in this disclosure should be understood to be modified by the word "about." As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specified value or range.

[0074] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0075] Some cases are described in the embodiments and comparative examples of the present invention, wherein the embodiments illustrate certain implementations of the present invention. However, this does not mean that the effects of the present invention can only be achieved in these cases.

[0076] To further illustrate the present invention, a block poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane and a preparation method thereof provided by the present invention are described in detail below with reference to examples.

[0077] Example 1: (a) Synthesis of PBTbBP-10 Block Polymer

[0078] 1. System a: 0.8 g of biphenyl and 0.646 g of N-methyl-4-piperidone monomer were mixed into a three-necked condensation flask, and 5.2 mL of dichloromethane solvent was added. The mixture was stirred at 10°C for 0.5 h.

[0079] Use a constant pressure dropping funnel to add 0.5 mL of TFA to the system at a constant rate for about 1 min.

[0080] 4.8 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 5 min.

[0081] After the acid was added, the mixture was stirred at 200 rps for 1.5 h;

[0082] 2. System b: 7.2 g of biphenyl and 9.45 g of 2,2,2-trifluoroacetophenone monomer were mixed into a round-bottom flask, and 46.8 mL of dichloromethane solvent was added. The mixture was stirred at 25°C for 10 min.

[0083] 43.22 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 30 min.

[0084] After the acid was added, the mixture was stirred at 200 rps for 10 min.

[0085] 3. Mix systems a and b and stir for 8 h to obtain a brown viscous liquid.

[0086] 4. Add 200 mL of water to the system, and a white solid polymer will precipitate. Stir and soak for 60 minutes to terminate the reaction.

[0087] 5. Cut the polymer into powder and pour it into ethanol, stirring and washing it three times, each time for 2 hours; then pour the powder into deionized water and stir and wash it three times;

[0088] 6. Place the cleaned powder in an 80℃ forced air oven and dry for 24 hours, then bag it and place it in a dryer.

[0089] (b) Preparation of PBTbBP-10 hollow fiber loose membrane

[0090] 1. Dissolve 2g of PBTbBP-10 polymer in 8g of N-methylpyrrolidone solution and stir at 80°C for 12h to form a uniform casting solution;

[0091] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0092] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , with water as the core liquid at a rate of 2 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0093] 4. Soak the membrane in a 10% ethanol / water mixture for 12 hours, and then store it in glycerol ( Figure 3 b).

[0094] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 130 L m -2 h - 1 bar -1 , the retention rate was 99.5%, and the NaCl retention rate was 7.4%.

[0095] Example 2: (a) Synthesis of PBTbBP-5 Block Polymer

[0096] 1. System a: 0.4 g biphenyl and 0.323 g N-methyl-4-piperidone monomer were mixed into a three-necked condensation flask, and 2.6 mL dichloromethane solvent was added. Stir at 10°C for 0.5 h.

[0097] Use a constant pressure dropping funnel to add 0.25 mL of TFA to the system at a constant rate for about 0.5 min.

[0098] 2.4 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 2.5 min.

[0099] After the acid was added, the mixture was stirred at 200 rps for 1.5 h;

[0100] 2. System b: 7.6 g of biphenyl and 9.975 g of 2,2,2-trifluoroacetophenone monomer were mixed into a round-bottom flask, and 49.4 mL of dichloromethane solvent was added. The mixture was stirred at 25°C for 10 min.

[0101] 45.62 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 30 min.

[0102] After the acid was added, the mixture was stirred at 200 rps for 10 min.

[0103] 3. Mix systems a and b and stir for 8 h to obtain a brown viscous liquid.

[0104] 4. Add 200 mL of water to the system, and a white solid polymer will precipitate. Stir and soak for 60 minutes to terminate the reaction.

[0105] 5. Cut the polymer into powder and pour it into ethanol, stirring and washing it three times, each time for 2 hours; then pour the powder into deionized water and stir and wash it three times;

[0106] 6. Place the cleaned powder in an 80℃ forced air oven and dry for 24 hours, then bag it and place it in a dryer.

[0107] (b) Preparation of PBTbBP-5 hollow fiber loose membrane

[0108] 1. Dissolve 2g of PBTbBP-5 polymer in 8g of N-methylpyrrolidone solution and stir at 80°C for 12h to form a uniform casting solution;

[0109] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0110] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-5 casting solution extrusion rate of 2 mL min -1 , with water as the core liquid at a rate of 2 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0111] 4. Soak the membrane in a 10% ethanol / water mixture for 12 hours, and then store it in glycerol ( Figure 3 a).

[0112] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 57 L m -2h - 1 bar -1 , the Congo red retention rate was 99.5%, and the NaCl retention rate was 5.7%.

[0113] Example 3: (a) Synthesis of PBTbBP-15 Block Polymer

[0114] 1. System a: 1.2 g of biphenyl and 0.969 g of N-methyl-4-piperidone monomer were mixed into a three-necked condensation flask, and 7.8 mL of dichloromethane solvent was added. The mixture was stirred at 10°C for 0.5 h.

[0115] 0.75 mL of TFA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 1.5 min.

[0116] 7.2 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 7.5 min.

[0117] After the acid was added, the mixture was stirred at 200 rps for 1.5 h;

[0118] 2. System b: 6.8 g of biphenyl and 8.925 g of 2,2,2-trifluoroacetophenone monomer were mixed into a round-bottom flask, and 49.4 mL of dichloromethane solvent was added. The mixture was stirred at 25°C for 10 min.

[0119] 40.8 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 30 min.

[0120] After the acid was added, the mixture was stirred at 200 rps for 10 min.

[0121] 3. Mix systems a and b and stir for 8 h to obtain a brown viscous liquid.

[0122] 4. Add 200 mL of water to the system, and a white solid polymer will precipitate. Stir and soak for 60 minutes to terminate the reaction.

[0123] 5. Cut the polymer into powder and pour it into ethanol, stirring and washing it three times, each time for 2 hours; then pour the powder into deionized water and stir and wash it three times;

[0124] 6. Place the cleaned powder in an 80℃ forced air oven and dry for 24 hours, then bag it and place it in a dryer.

[0125] (b) Preparation of PBTbBP-15 hollow fiber loose membrane

[0126] 1. Dissolve 2g of PBTbBP-15 polymer in 8g of N-methylpyrrolidone solution and stir at 80°C for 12h to form a uniform casting solution;

[0127] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0128] 3. The membrane was prepared using a hollow fiber spinning machine, with a PBTbBP-15 casting solution extrusion rate of 2 mL min -1 , with water as the core liquid at a rate of 2 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0129] 4. Soak the membrane in a 10% ethanol / water mixture for 12 hours, and then store it in glycerol ( Figure 3 c).

[0130] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10,000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 64.3 L m -2 h -1 bar -1 , the Congo red retention rate was 98.6%, and the NaCl retention rate was 10.7%.

[0131] Example 4: Synthesis of PBTbBP-10 Block Polymer (System a Pre-crosslinking Time Control)

[0132] 1. System a: 0.8 g of biphenyl and 0.646 g of N-methyl-4-piperidone monomer were mixed into a three-necked condensation flask, and 5.2 mL of dichloromethane solvent was added. The mixture was stirred at 10°C for 0.5 h.

[0133] Use a constant pressure dropping funnel to add 0.5 mL of TFA to the system at a constant rate for about 1 min.

[0134] 4.8 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 5 min.

[0135] After the acid was added, the mixture was stirred at 200 rps for 1 h;

[0136] 2. System b: 7.2 g of biphenyl and 9.45 g of 2,2,2-trifluoroacetophenone monomer were mixed into a round-bottom flask, and 46.8 mL of dichloromethane solvent was added. The mixture was stirred at 25°C for 10 min.

[0137] 43.22 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 30 min.

[0138] After the acid was added, the mixture was stirred at 200 rps for 10 min.

[0139] 3. Mix systems a and b and stir for 8 h to obtain a brown viscous liquid.

[0140] 4. Add 200 mL of water to the system, and a white solid polymer will precipitate. Stir and soak for 60 minutes to terminate the reaction.

[0141] 5. Cut the polymer into powder and pour it into ethanol, stirring and washing 3 times, each time for 2 hours; then pour the powder into deionized water and stir and wash 3 times; (a white solid powder is obtained, and the precipitated solution is clear)

[0142] 6. Place the cleaned powder in an 80℃ forced air oven and dry for 24 hours, then bag it and place it in a dryer.

[0143] Example 5: Synthesis of PBTbBP-10 Block Polymer (System a Pre-crosslinking Time Control)

[0144] 1. System a: 1.2 g of biphenyl and 0.969 g of N-methyl-4-piperidone monomer were mixed into a three-necked condensation flask, and 7.8 mL of dichloromethane solvent was added. The mixture was stirred at 10°C for 0.5 h.

[0145] 0.75 mL of TFA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 1.5 min.

[0146] Use a constant pressure dropping funnel to drop 5 mL of TFSA into the system at a constant rate for about 5 minutes;

[0147] After the acid was added, the mixture was stirred at 200 rps for 1.5 h;

[0148] 2. System b: 6.8 g of biphenyl and 8.925 g of 2,2,2-trifluoroacetophenone monomer were mixed into a round-bottom flask, and 49.4 mL of dichloromethane solvent was added. The mixture was stirred at 25°C for 10 min.

[0149] 40.8 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 30 min.

[0150] After the acid was added, the mixture was stirred at 200 rps for 10 min.

[0151] 3. Mix systems a and b and stir for 6 h to obtain a brown viscous liquid.

[0152] 4. Add 200 mL of water to the system, and a white solid polymer will precipitate. Stir and soak for 60 minutes to terminate the reaction.

[0153] 5. Cut the polymer into powder and pour it into ethanol, stirring and washing 3 times, each time for 2 hours; then pour the powder into deionized water and stir and wash 3 times; (a white solid powder is obtained, and the precipitated solution is clear)

[0154] 6. Place the cleaned powder in an 80℃ forced air oven and dry for 24 hours, then bag it and place it in a dryer.

[0155] Example 6: Preparation of PBTbBP-10 Hollow Fiber Loose Membrane (Polymer Concentration Control)

[0156] 1. Dissolve 1.6 g of PBTbBP-10 polymer in 8.4 g of N-methylpyrrolidone solution and stir at 80°C for 12 h to form a uniform casting solution;

[0157] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0158] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , with water as the core liquid at a rate of 2 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0159] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0160] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10,000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 147 L m -2 h - 1 bar -1 , the retention rate was 99%, and the NaCl retention rate was 5.7%.

[0161] Example 7: Preparation of PBTbBP-10 Hollow Fiber Loose Membrane (Polymer Concentration Control)

[0162] 1. Dissolve 1.8 g of PBTbBP-10 polymer in 8.2 g of N-methylpyrrolidone solution and stir at 80°C for 12 h to form a uniform casting solution;

[0163] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0164] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , with water as the core liquid at a rate of 2 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0165] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0166] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10,000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 136 L m -2 h - 1 bar -1 , the retention rate was 99.2%, and the NaCl retention rate was 5.1%.

[0167] Example 8: Preparation of PBTbBP-10 Hollow Fiber Loose Membrane (Core Liquid Flow Rate Control)

[0168] 1. Dissolve 1.6 g of PBTbBP-10 polymer in 8.4 g of N-methylpyrrolidone solution and stir at 80°C for 12 h to form a uniform casting solution;

[0169] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0170] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , using water as the core liquid at a rate of 3 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0171] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0172] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10,000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 162 L m -2 h - 1 bar -1 , the retention rate was 99%, and the NaCl retention rate was 3.2%.

[0173] Example 9: Preparation of PBTbBP-10 hollow fiber loose membrane (Separation system exploration)

[0174] 1. Dissolve 1.6 g of PBTbBP-10 polymer in 8.4 g of N-methylpyrrolidone solution and stir at 80°C for 12 h to form a uniform casting solution;

[0175] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0176] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , using water as the core liquid at a rate of 4 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0177] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0178] The membrane was packaged into a 17cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of VB12 / NaCl aqueous solution (50ppm / 10000ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 123L m -2 h - 1 bar -1 , the retention rate was 56.7%, and the NaCl retention rate was 4.5%.

[0179] Example 10: Preparation of PBTbBP-10 hollow fiber loose membrane (Separation system exploration)

[0180] 1. Dissolve 1.6 g of PBTbBP-10 polymer in 8.4 g of N-methylpyrrolidone solution and stir at 80°C for 12 h to form a uniform casting solution;

[0181] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0182] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , using water as the core liquid at a rate of 4 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0183] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0184] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of a Rhodamine B / NaCl aqueous solution (50 ppm / 10,000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 112 L m - 2 h -1 bar -1, the retention rate was 99%, and the NaCl retention rate was 7.6%.

[0185] Comparative Example 1: Synthesis of PBTbBP-10 Block Polymer (Pre-crosslinking Time Control of System a)

[0186] 1. System a: 1.2 g of biphenyl and 0.969 g of N-methyl-4-piperidone monomer were mixed into a three-necked condensation flask, and 7.8 mL of dichloromethane solvent was added. The mixture was stirred at 10°C for 0.5 h.

[0187] 0.75 mL of TFA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 1.5 min.

[0188] Use a constant pressure dropping funnel to drop 5 mL of TFSA into the system at a constant rate for about 5 minutes;

[0189] After the acid was added, the mixture was stirred at 200 rps for 2 h;

[0190] 2. System b: 6.8 g of biphenyl and 8.925 g of 2,2,2-trifluoroacetophenone monomer were mixed into a round-bottom flask, and 49.4 mL of dichloromethane solvent was added. The mixture was stirred at 25°C for 10 min.

[0191] 40.8 mL of TFSA was added dropwise to the system at a constant rate using a constant pressure dropping funnel for approximately 30 min.

[0192] After the acid was added, the mixture was stirred at 200 rps for 10 min.

[0193] 3. Mix systems a and b and stir for 6 h to obtain a brown viscous liquid.

[0194] 4. Add 200 mL of water to the system, and a white solid polymer will precipitate. Stir and soak for 60 minutes to terminate the reaction.

[0195] 5. Cut the polymer into powder and pour it into ethanol, stirring and washing 3 times, each time for 2 hours; then pour the powder into deionized water and stir and wash 3 times; (a white solid powder is obtained, and the precipitation solution is turbid)

[0196] 6. Place the cleaned powder in an 80℃ forced air oven and dry for 24 hours, then bag it and place it in a dryer.

[0197] Comparative Example 2: Preparation of PBTbBP-10 hollow fiber loose membrane (polymer concentration control)

[0198] 1. Dissolve 1g of PBTbBP-10 polymer in 9g of N-methylpyrrolidone solution and stir at 80°C for 12h to form a uniform casting solution;

[0199] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0200] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , with water as the core liquid at a rate of 2 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0201] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0202] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10,000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 163 L m -2 h - 1 bar -1 , the retention rate was 78%, and the NaCl retention rate was 1.5%.

[0203] Comparative Example 3: Preparation of PBTbBP-10 hollow fiber loose membrane (polymer concentration control)

[0204] 1. Dissolve 3g of PBTbBP-10 polymer in 7g of N-methylpyrrolidone solution and stir at 80°C for 12h to form a uniform casting solution;

[0205] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0206] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , with water as the core liquid at a rate of 2 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0207] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0208] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 98 L m -2 h - 1 bar -1 , the retention rate was 99%, and the NaCl retention rate was 10.4%.

[0209] Comparative Example 4: Preparation of PBTbBP-10 hollow fiber loose membrane (core liquid flow rate control)

[0210] 1. Dissolve 1.6 g of PBTbBP-10 polymer in 8.4 g of N-methylpyrrolidone solution and stir at 80°C for 12 h to form a uniform casting solution;

[0211] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0212] 3. The membrane was prepared using a hollow fiber spinning machine, with the PBTbBP-10 casting solution extrusion rate of 2 mL min -1 , using water as the core liquid at a rate of 4 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0213] 4. Soak the membrane fibers in a 10% ethanol / water mixture for 12 hours, and then place them in glycerol for wet storage.

[0214] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 177 L m -2 h - 1 bar -1 , the retention rate was 96.4%, and the NaCl retention rate was 1.5%.

[0215] Comparative Example 5: (a) Synthesis of Random Copolymer (Biphenyl-Trifluoroacetophenone-Piperidone) (PBcoTP)

[0216] 1. 8 g of biphenyl, 9.45 g (97%) of trifluoroacetophenone monomer, and 0.646 g (10%) of N-methylpiperidone monomer were mixed into a three-necked condenser flask, and 52 mL of dichloromethane solvent was added. The mixture was stirred at 20°C for 0.5 h.

[0217] 2. Use a constant pressure dropping funnel to add 4 mL of trifluoroacetic acid to the system at a constant rate for about 5 minutes;

[0218] 3. Use a constant pressure dropping funnel to add 48 mL of trifluoromethanesulfonic acid to the system at a constant rate for about 0.5 h.

[0219] 4. After adding the acid, stir at 200 rps for 7 hours;

[0220] 5. Add 200 mL of water to the system to precipitate the polymer, stir and soak for 60 minutes to terminate the reaction;

[0221] 6. Cut the polymer into powder and pour it into ethanol solution, stirring and washing 3 times, each time for 2 hours; then pour the powder into deionized water and stir and wash 3 times;

[0222] 7. Place the cleaned powder in an 80℃ forced air oven and dry for 24 hours, then bag it and place it in a dryer.

[0223] (b) Preparation of PBcoTP hollow fiber membrane

[0224] 1. Dissolve 1.6 g of PBcoTP polymer in 8.4 g of N-methylpyrrolidone solution and stir at 80°C for 12 h to form a uniform casting solution;

[0225] 2. Vacuum filter and degas for 2-3 hours until the bubbles in the solution disappear;

[0226] 3. The membrane fibers were prepared using a hollow fiber spinning machine, and the PBcoTP casting solution extrusion rate was 2 mL min -1 , using water as the core liquid at a rate of 3 mL min -1 , dry length 5cm, water as gel bath, spinning at 25℃.

[0227] 4. Soak the membrane in a 10% ethanol / water mixture for 12 hours, and then store it in glycerol ( Figure 3 a).

[0228] The membrane was packaged into a 17 cm single membrane assembly and connected to a nanofiltration cross-flow system to test the separation performance of Congo red / NaCl aqueous solution (50 ppm / 10,000 ppm). After 30 minutes of stable operation and 30 minutes of testing, the water permeability of the membrane reached 10.9 L m -2 h -1 bar -1 The Congo red retention rate was 99%, and the NaCl retention rate was 12.5%.

[0229] Comparative Example 6: This comparative example will illustrate the preparation method of poly (biphenyl-N-methylpiperidone-trifluoroacetophenone) hollow fiber ultrafiltration membrane, as follows:

[0230] 1.9108g of 2,2,2-trifluoroacetophenone, 0.5322g of N-methyl-4-piperidone, and 2.3704g of biphenyl were dissolved in 10.8mL of dichloromethane. After stirring at 0°C for 10 minutes, 0.6mL of trifluoroacetic acid was added dropwise. Stirring was continued for 20 minutes, followed by 10.7mL of trifluoromethanesulfonic acid. The temperature was then raised to 10°C over 2 hours while stirring. The reaction lasted for 25 hours. After 25 hours, the reaction product was poured into methanol for precipitation. The precipitate was washed with methanol and dried to obtain a white poly(biphenyl-N-methylpiperidone-trifluoroacetophenone) polymer. 4.6132g of the above polymer and 0.9226g of polyethylene glycol were dissolved in 17.5302g of N-methylpyrrolidone to obtain a viscous, uniform, pale yellow spinning solution. The spinning solution and the core liquid were co-extruded from the spinning nozzle. The core liquid was composed of deionized water at room temperature. -1 The spinning solution was injected into the nozzle at a rate of 1.5 mL min -1 The original silk passed through the nozzle at a rate of 100%. After a 5 cm air path, it entered an external coagulation bath composed of a non-solvent. The external coagulation bath was deionized water and the temperature of the external coagulation bath was 25 ° C. It was collected in the external coagulation bath tank by free fall. The obtained membrane silk was immersed in deionized water for at least 24 hours to remove the residual solvent, and finally a poly (biphenyl-N-methylpiperidone-trifluoroacetophenone) hollow fiber ultrafiltration membrane was obtained. The membrane silk was made into the corresponding membrane assembly, and the separation performance was tested using a membrane separation performance evaluation instrument. Its pure water flux was 71.2L m -2 h -1 bar -1 The retention rate of bovine serum albumin reached 92.0%. The membrane flux of the random copolymer was lower than that of the block copolymer.

[0231] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a segmented poly (biphenyl-trifluoroacetophenone-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, characterized in that: The steps include: A) reacting biphenyl with N-methyl-4-piperidone to obtain a first product; Biphenyl reacts with 2,2,2-trifluoroacetophenone with acid to obtain a second product; B) adding the second product to the first product for polycondensation to obtain a PBTbBP block polymer; C) dissolving the PBTbBP block polymer in a solvent and degassing to obtain a casting solution; D) spinning the casting solution and the core solution to obtain membrane filaments; E) Immerse the membrane filaments in a coagulation bath to allow phase separation to occur.

2. The preparation method according to claim 1, characterized in that Step A) the temperature of the reaction of biphenyl with N-methyl-4-piperidone by acid addition is 8-12° C. and the time is 0.5-1.5 h; The temperature for the acid addition reaction of biphenyl and 2,2,2-trifluoroacetophenone is 20-30° C., and the time is 8-12 minutes.

3. The preparation method according to claim 1, characterized in that The acid includes trifluoromethanesulfonic acid and / or trifluoroacetic acid; The temperature of the polycondensation reaction is 10° C. and the time is 7 to 10 hours.

4. The preparation method according to claim 2, characterized in that described The molar ratio of the total molar amount of 2,2,2-trifluoroacetophenone and N-methyl-4-piperidone to biphenyl is 1.1:1; The molar ratio of trifluoromethanesulfonic acid to biphenyl is 10:1; The molar ratio of trifluoroacetic acid to biphenyl was 0.8:

1.

5. The preparation method according to claim 1, characterized in that Step C) the solvent is N-methylpyrrolidone; the concentration of the PBTbBP block polymer in the solvent is 14-20 wt%; The dissolving is performed by stirring, the stirring temperature is 70 to 90° C., and the stirring time is 10 to 14 hours; and the degassing time is 2 to 3 hours.

6. The preparation method according to claim 1, characterized in that Step D) The extrusion rate of the casting solution is 2 mL min -1 .

7. The preparation method according to claim 1, characterized in that The core liquid is water; the rate of the water is 2-3 mL min -1 ; Drying distance 5cm, using water as gel bath, spinning is carried out at 20-30℃.

8. The preparation method according to claim 1, characterized in that After step E), the membrane fibers are immersed in a 10% ethanol aqueous solution for 10 to 12 hours, and then placed in glycerol for wet storage.

9. A segmented poly (biphenyl-trifluoroacetophenone-biphenyl-piperidone) bicontinuous hollow fiber loose nanofiltration membrane, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9.

10. A method for separating dye molecules / salt ions, characterized in that: The bicontinuous hollow fiber loose nanofiltration membrane according to claim 9 is used.

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