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CN-122006519-A - Preparation method and product of self-polarized piezoelectric hollow fiber membrane in membrane forming process

CN122006519ACN 122006519 ACN122006519 ACN 122006519ACN-122006519-A

Abstract

The invention discloses a preparation method and a product of a self-polarized piezoelectric hollow fiber membrane in a membrane forming process, and belongs to the technical field of water treatment membranes. The invention takes polyvinylidene fluoride as a matrix material, lamellar ferroelectric material is introduced as a structure inducer, pore-forming agent is assisted, uniformly dispersed spinning solution is formed in an organic solvent system, and non-solvent induced phase separation synchronous induction technology is adopted for spinning forming. The spinning solution is acted by high-strength fluid shearing force at the slit of the spinning nozzle, so that lamellar ferroelectric materials are regularly oriented and arranged along the flowing direction, the ordered structure not only stabilizes and enriches the beta crystal form of polyvinylidene fluoride, but also guides dipole moment in the molecular chain of polyvinylidene fluoride to realize oriented arrangement, and spontaneous polarization of the beta crystal is synchronously induced in the film wire forming process. The method can prepare the polyvinylidene fluoride hollow fiber ultrafiltration membrane with high beta-crystal content and piezoelectric activity without the subsequent stretching or high-pressure polarization steps.

Inventors

  • ZHANG YANG
  • SUN PENG
  • SHI QIANG
  • WANG JUN

Assignees

  • 天津工业大学

Dates

Publication Date
20260512
Application Date
20260416

Claims (10)

  1. 1. The preparation method of the self-polarized piezoelectric hollow fiber membrane in the membrane forming process is characterized by comprising the following steps of: (1) Adding an amphiphilic block copolymer, a pore-forming agent and polyvinylidene fluoride into a lamellar ferroelectric material solution, and heating, stirring, standing and defoaming to obtain a spinning solution doped with lamellar ferroelectric material, wherein the amphiphilic block copolymer is a polyoxyethylene-polyoxypropylene-polyoxyethylene copolymer; (2) Spinning forming is carried out on the spinning solution based on the doped lamellar ferroelectric material obtained in the step (1) by adopting a non-solvent induced phase separation synchronous induction technology, and spontaneous polarization of beta crystals is synchronously completed in the spinning forming process, so that the self-polarized piezoelectric hollow fiber membrane is obtained.
  2. 2. The preparation method of the self-polarized piezoelectric hollow fiber membrane in the membrane forming process of claim 1, wherein the preparation method is characterized in that the lamellar ferroelectric material in the lamellar ferroelectric material solution in the step (1) is subjected to fluorosilane grafting modification before use by heating and refluxing the lamellar ferroelectric material in H 2 O 2 to prepare a hydroxylated lamellar ferroelectric material, dispersing the hydroxylated lamellar ferroelectric material in a mixed system of ethanol and water, adding 1H, 2H-perfluoro decyl trimethoxysilane solution for condensation, washing with ethanol and vacuum drying to obtain the fluorosilane grafted modified lamellar ferroelectric material.
  3. 3. The method for preparing a piezoelectric hollow fiber membrane self-polarizing in a membrane forming process according to claim 1, wherein the lamellar ferroelectric material in the lamellar ferroelectric material solution in step (1) is at least one selected from bismuth titanate, barium titanate, indium selenide, bismuth tungstate and bismuth strontium tantalate.
  4. 4. The method for preparing a self-polarizing piezoelectric hollow fiber membrane in a membrane forming process according to claim 1, wherein in the step (1), the spinning solution of the doped lamellar ferroelectric material has a lamellar ferroelectric material ratio of 0.5-1.5 wt%, an amphiphilic block copolymer ratio of 2wt%, a pore-forming agent ratio of 5wt%, and a polyvinylidene fluoride ratio of 20wt%.
  5. 5. The method of claim 1, wherein the pore-forming agent in step (1) is polyethylene glycol.
  6. 6. The method for preparing a self-polarizing piezoelectric hollow fiber membrane in a membrane forming process according to claim 1, wherein the temperature in the heating and stirring process in the step (1) is 40-70 ℃, the rotating speed is 200-400 rpm, and the time is 4-5 h.
  7. 7. The method for producing a piezoelectric hollow fiber membrane self-polarizing in a membrane forming process according to claim 1, wherein the solvent of the lamellar ferroelectric material solution in step (1) is at least one selected from the group consisting of N-methylpyrrolidone, N-dimethylformamide, dimethylsulfoxide and dimethylacetamide.
  8. 8. The method for preparing the self-polarized piezoelectric hollow fiber membrane in the membrane forming process according to claim 1, wherein the parameters of the spinning forming process in the step (2) comprise 0.3-1.4 mm of inner diameter of a spinneret, 0.5-1.8 mm of outer diameter of the spinneret, 60-80 ℃ of feed liquid kettle temperature, 0.3-0.5 kPa of air pressure of the feed liquid kettle, 1-3 cm of distance between the spinneret and a coagulating bath, 1.5-3 mL/min of core liquid speed of the spinneret, 4-6 mL/min of liquid opening speed and 7-9 m/min of reel stretching speed.
  9. 9. The method for preparing a self-polarizing piezoelectric hollow fiber membrane in a membrane forming process according to claim 1, wherein in the step (2), pure water is used as a core liquid and a coagulation bath when spinning forming is performed by a non-solvent induced phase separation synchronous induction technique with a spinning liquid doped with lamellar ferroelectric materials.
  10. 10. The self-polarizing piezoelectric hollow fiber membrane according to any one of claims 1 to 9, wherein the self-polarizing piezoelectric hollow fiber membrane is prepared by a preparation method of the self-polarizing piezoelectric hollow fiber membrane in a membrane forming process.

Description

Preparation method and product of self-polarized piezoelectric hollow fiber membrane in membrane forming process Technical Field The invention belongs to the technical field of water treatment membranes, and particularly relates to a preparation method and a product of a self-polarized piezoelectric hollow fiber membrane in a membrane forming process. Background With the acceleration of industrialization and urban processes, the problem of water pollution is increasingly serious, and water quality safety has become one of the core issues of great social concern. Among a plurality of separation means, the membrane separation technology becomes a research hot spot in the field of water treatment due to the advantages of high efficiency, energy conservation, simple operation, environmental friendliness and the like, and has wide application prospects in aspects of drinking water purification, sewage treatment, reuse and the like. Among them, hollow fiber membranes are important in membrane separation technology because of their high packing density, good mechanical strength, low manufacturing cost, and easy realization of modularization and automation operation, and are widely used in water treatment processes of multiple levels such as microfiltration, ultrafiltration and even nanofiltration. However, membrane fouling problems are always a core bottleneck that limits long-term stable operation and extended service life of hollow fiber membranes. Adsorption and deposition of contaminants on the membrane surface or in the pores not only results in reduced flux and increased energy consumption, but also increases the frequency of cleaning and the cost of operation and maintenance. In order to cope with the membrane pollution challenge, researchers have conducted a great deal of research from material modification, structural optimization to process control and the like. For example, patent CN115920670a discloses a preparation method of an anti-pollution hydrophilic hollow fiber membrane, which is to introduce nano TiO 2 seed crystal into a base membrane, construct a titanium crystal layer on the surface of the membrane and compound with a hydrophilic polymer to form a functional anti-pollution coating. However, the method is complicated in steps, and the functional layer is at risk of stripping under the condition of long-term back flushing or strong acid-base cleaning, so that the stability is insufficient. For another example, patent CN119588165A devised an anti-fouling hollow fiber membrane module with a specific geometry, and by optimizing the surface gradient of the sealant layer and the sub-aeration pipes, the gravity and the air flow are used to cooperate to promote the falling of pollutants. Although the thought has a certain innovation, the anti-pollution performance of the anti-pollution device excessively depends on structural parameters, engineering adaptability is poor, the anti-pollution device is easily influenced by factors such as installation errors, operation fluctuation and the like in practical application, and a stable and reliable anti-pollution effect is difficult to realize. Under the background, the development of a novel hollow fiber membrane with high-efficiency separation performance and continuous anti-pollution capability becomes a key direction of current research. In recent years, piezoelectric materials have shown great potential in the field of membrane pollution control due to their unique force-electrical coupling characteristics. The piezoelectric effect refers to that when some crystal materials deform under the action of external force, polarization phenomenon is generated inside the crystal materials, so that potential difference is formed on the surfaces of the materials. The electric potential can drive local electrochemical reaction or change surface charge distribution, and realize the functions of electric drive rejection, degradation or self-cleaning of pollutants. Polyvinylidene fluoride (PVDF) is a typical piezoelectric polymer whose piezoelectric properties are derived mainly from the relative content of the β crystal form. Therefore, increasing the proportion of β crystal forms in PVDF membranes and inducing spontaneous polarization thereof is a core strategy to construct separation membranes with piezoelectric responsiveness. Although research has been attempted to improve the beta-crystal content and the piezoelectric performance by post-treatment means (such as mechanical stretching, high-pressure polarization and the like), for example, a stretching-polarization combined process is adopted in the patent CN117886439A to prepare the PVDF piezoelectric ultrafiltration membrane, but the method has high energy consumption and complex working procedures, is unfavorable for large-scale production, and the piezoelectric phase is hydrothermally grown on the surface of the ceramic membrane as in the patent CN119926195A, and although certain piezoelectric activity is e