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CN-122006532-A - Preparation method of glass fiber porous membrane-assisted fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane and electrochemical cleaning method thereof

CN122006532ACN 122006532 ACN122006532 ACN 122006532ACN-122006532-A

Abstract

The invention discloses a preparation method of a fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane assisted by a glass fiber porous membrane and an electrochemical cleaning method thereof, and relates to a preparation method of an ultrafiltration/oil-water separation dual-functional composite membrane and an electrochemical cleaning method thereof. The method solves the problems of low mechanical strength, insufficient anti-pollution performance and difficult compromise between flux and retention rate of the existing polymer membrane, and the problems of weak interface bonding, unstable structure, low operating pressure and complex preparation process still exist when the membrane performance is improved by adding inorganic filler or surface modification, and the problem of poor treatment effect on complex dye wastewater. Electrochemical cleaning, namely applying cleaning voltage to generate electrodynamic force to drive charged pollutants to separate. The invention is used for preparing the fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane assisted by the glass fiber porous membrane and electrochemical cleaning thereof.

Inventors

  • SUN XIAOWEI
  • WU ZHIBO
  • YU YUNWU
  • FANG YANFENG
  • LIU PENG
  • LIU XIN
  • WANG LIHUA
  • MA YING

Assignees

  • 沈阳建筑大学

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. The preparation method of the fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane assisted by the glass fiber porous membrane is characterized by comprising the following steps of: 1. Weighing: weighing 100 parts of fluorine-containing block copolymer, 10 parts to 40 parts of branched polyethylenimine, 0.5 part to 1 part of N- (beta-aminoethyl) -gamma-aminopropyl triethoxysilane, 200 parts to 800 parts of water-soluble polar organic solvent and 0.5 part to 2 parts of purified water according to parts by mass; 2. Preparing a casting solution: Stirring and mixing the weighed fluorine-containing block copolymer, branched polyethyleneimine, N- (beta-aminoethyl) -gamma-aminopropyl triethoxysilane and a water-soluble polar organic solvent for 6-12 hours at room temperature, then dropwise adding the weighed purified water, and continuously stirring for 20-40 minutes to obtain a casting solution; 3. Preparation of double functions: spin-coating the casting solution on one side surface of the glass fiber porous membrane and fully soaking, and then placing the glass fiber porous membrane in a deionized water coagulation bath to obtain the ultrafiltration/oil-water separation dual-function composite membrane.
  2. 2. The preparation method of the glass fiber porous membrane-assisted fluorine-containing block copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane is characterized in that the structural formula of the fluorine-containing block copolymer in the step one is that Wherein n=5 to 20, m=5 to 20.
  3. 3. The preparation method of the glass fiber porous membrane-assisted fluorine-containing block copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane is characterized in that the fluorine-containing block copolymer in the first step is specifically prepared by the following steps: (1) Preparation of fluorine-terminated low molecular weight oligomers: ① Respectively drying phenolphthalein, 4 '-difluorodiphenyl sulfone and anhydrous potassium carbonate in vacuum, and then mixing to obtain a dried raw material A, wherein the molar ratio of the phenolphthalein to the 4,4' -difluorodiphenyl sulfone is 1 (1.2-1.5), and the mass ratio of the phenolphthalein to the anhydrous potassium carbonate is 1mmol (0.2902-0.3455) g; ② Injecting anhydrous NMP and anhydrous toluene into the dried raw material A, heating to 110-120 ℃ under the protection of nitrogen, removing water by using a water separator, heating to 130-140 ℃ to evaporate toluene when no water is separated from the water separator, then reacting at 165-175 ℃, sampling during the reaction, monitoring the molecular weight by gel permeation chromatography, and stopping reacting when the number average molecular weight reaches 2000-3000 to obtain fluorine-terminated low molecular weight oligomer; the volume ratio of the anhydrous NMP to the anhydrous toluene is 1 (0.5-0.8), and the total volume ratio of the mass of the dried raw material A to the anhydrous NMP and the anhydrous toluene is 1g (2.5-6) mL; (2) Preparation of hydroxy-terminated low molecular weight oligomers: ① Respectively carrying out vacuum drying on hexafluorobisphenol A, decafluorobiphenyl and anhydrous potassium carbonate, and then mixing to obtain a dried raw material B, wherein the molar ratio of hexafluorobisphenol A to decafluorobiphenyl is (1.2-1.5): 1, and the mass ratio of hexafluorobisphenol A to anhydrous potassium carbonate is 1mmol (0.2902-0.3455) g; ② Injecting anhydrous NMP and anhydrous toluene into the dried raw material B, heating to 110-120 ℃ under the protection of nitrogen, removing water by using a water separator, heating to 130-140 ℃ to evaporate toluene when no water is separated from the water separator, then reacting at 150-155 ℃, sampling during the reaction, monitoring the molecular weight by gel permeation chromatography, and stopping the reaction when the number average molecular weight reaches 2000-3000 to obtain a hydroxyl-terminated low molecular weight oligomer; the volume ratio of the anhydrous NMP to the anhydrous toluene is 1 (0.5-0.8), and the total volume ratio of the mass B of the dried raw material to the anhydrous NMP and the anhydrous toluene is 1g (2.5-6) mL; (3) Synthesis of Block copolymer: Under the protection of nitrogen, mixing the fluorine-terminated low molecular weight oligomer and the hydroxyl-terminated low molecular weight oligomer, heating to 165-170 ℃ in an oil bath, then reacting for 6-12 hours at 165-170 ℃, cooling to room temperature after the reaction is finished, pouring the reaction solution into deionized water for precipitation, and finally crushing, filtering, washing and vacuum drying the precipitate to obtain the fluorine-containing segmented copolymer.
  4. 4. The preparation method of the glass fiber porous membrane-assisted fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane is characterized in that the vacuum drying in the step (1) ① and the step (2) ① is carried out at the temperature of 100-120 ℃ for 12-24 hours.
  5. 5. The preparation method of the glass fiber porous membrane-assisted fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane is characterized in that the molecular weight of the branched polyethylenimine in the step one is 1800-10000.
  6. 6. The preparation method of the glass fiber porous membrane-assisted fluorine-containing block copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-function composite membrane is characterized in that the water-soluble polar organic solvent in the first step is one or a mixture of a plurality of N-methylpyrrolidone, N-dimethylformamide and N, N-dimethylacetamide.
  7. 7. The preparation method of the glass fiber porous membrane-assisted fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-function composite membrane is characterized in that the stirring speed in the second step is 200-500 r/min.
  8. 8. The preparation method of the fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane assisted by the glass fiber porous membrane, which is disclosed in claim 1, is characterized in that in the third step, according to the coating amount of 6 g/square decimeter-12 g/square decimeter, casting solution is spin-coated on one side surface of the glass fiber porous membrane and fully soaked, and then the glass fiber porous membrane is placed in a deionized water coagulating bath for 24-48 h under the condition that the temperature is 20-40 ℃.
  9. 9. The preparation method of the glass fiber porous membrane-assisted fluorine-containing block copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane is characterized in that the average pore diameter of the glass fiber porous membrane in the step three is 0.3-0.5 mu m.
  10. 10. The electrochemical cleaning method of the glass fiber porous membrane-assisted fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane prepared by the method is characterized by comprising the following steps of: And applying a cleaning voltage of 5-10 volts to the polluted ultrafiltration/oil-water separation dual-function composite membrane to generate electrodynamic force to drive charged pollutants attached to the surface and in the membrane pores to separate, so as to recover the membrane flux.

Description

Preparation method of glass fiber porous membrane-assisted fluorine-containing segmented copolymer high-pressure-resistant high-flux ultrafiltration/oil-water separation dual-functional composite membrane and electrochemical cleaning method thereof Technical Field The invention relates to a preparation method of an ultrafiltration/oil-water separation dual-functional composite membrane and an electrochemical cleaning method thereof. Background The ultrafiltration membrane is used as a separation medium based on a screening mechanism, and has been widely applied to the fields of drinking water purification, wastewater reuse, food concentration, biological product separation, pharmaceutical industry and the like by virtue of the characteristics of high efficiency, energy conservation, simple operation and the like. The core performance indexes mainly comprise retention rate, water permeability flux, mechanical strength, pollution resistance and long-term running stability. At present, common ultrafiltration membranes are mostly made of organic polymer materials by a phase inversion method or a composite preparation technology. Although these material systems are well established, several general challenges remain in practical use. The operating pressure is an important factor affecting the performance index and the operation efficiency of the ultrafiltration membrane, and in the biomedical field (such as protein concentration) with high requirements on the mildness of the product, medium and low pressures (0.1-0.4 MPa) are generally adopted to maintain the bioactivity, and in the water quality purification field, the allowable higher pressure (such as 0.3-0.5 MPa) can be used for pursuing the water production efficiency. Ultrafiltration membranes of different materials and structures have different mechanical strengths, for example, a polyvinylidene fluoride (PVDF) hollow fiber membrane has a maximum water inlet pressure of 0.3MPa, whereas regenerated cellulose composite membranes may withstand higher pressures. The operation pressure of the traditional ultrafiltration membrane is generally lower (0.1-0.5 MPa), so that the operation pressure is improved, and the method has important significance in expanding the application field boundary of the ultrafiltration technology for treating high-difficulty and high-added-value materials. Studies have shown that when treating very high concentration salt solutions (20000 mg/L to 70000 mg/L), it may be more preferable to raise the operating pressure to 1.0 MPa. The coiled ultrafiltration membrane with the highest operating pressure of 1.5MPa is specially used for separating and concentrating industrial processes of high-concentration and high-viscosity special materials in the fields of biological medicine, food industry, special chemical industry and the like, and is an important technical supplement. The pressure resistance limit of the ultrafiltration membrane is improved to be more than 1MPa, and the ultrafiltration membrane mainly aims to solve the technical challenge that the conventional ultrafiltration membrane (usually <0.5 MPa) cannot be qualified: 1. The high viscosity and high solid content of the material should be dealt with. When handling high viscosity or high solids content materials such as fermentation broths, concentrated juice, high concentration proteins, etc., higher operating pressures are required to overcome flow resistance, maintaining reasonable membrane flux and concentration efficiency. 2. And the operating pressure and the limiting separation efficiency are improved. For some systems with molecular weights close to the membrane aperture, the improvement of pressure is helpful to enhance the separation driving force, and the higher recovery rate and separation precision of the target product are obtained. 3. Simplifying the process flow. For certain high-salt wastewater, moderately increasing the pressure may reduce the number of process stages, realizing single-stage efficient concentration, thereby reducing the complexity of the system and the total investment. 4. Single function and faces the challenge of treating complex dye wastewater. The dye wastewater has complex components and often contains various assistants, salts, heavy metals and organic solvents, and forms multiple challenges for the ultrafiltration membrane. However, the traditional polymer membrane has low mechanical strength, insufficient anti-pollution performance and difficult compromise of flux and retention rate. In the prior art, the membrane performance is usually improved by adding inorganic filler or surface modification, but the defects of weak interface bonding, unstable structure, low operation pressure, complex preparation process and the like still exist, and the treatment effect on complex dye wastewater is poor. Therefore, the development of the composite ultrafiltration membrane with high flux, high interception, strong mechanical property and pollution