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CN-121972015-A - Composite ultrafiltration membrane based on blending modification and surface modification, and preparation method and application thereof

CN121972015ACN 121972015 ACN121972015 ACN 121972015ACN-121972015-A

Abstract

The invention relates to the technical field of membrane separation, in particular to a composite ultrafiltration membrane based on blending modification and surface modification, and a preparation method and application thereof. The method comprises the steps of preparing a polydopamine functional multi-wall carbon nano tube through oxidation crosslinking self-polymerization and adhesiveness of a dopamine compound in an aqueous solution, dissolving a film-forming polymer, a pore-forming agent and the prepared polydopamine functional multi-wall carbon nano tube in an organic solvent, preparing a blend membrane through a non-solvent induced phase separation method after degassing, sequentially and alternately immersing the prepared blend membrane into a tannic acid solution and an aluminum salt solution, and forming a tannic acid-aluminum ion metal phenolic network layer on the surface of the blend membrane through a coordination-driven layer-by-layer self-assembly method to obtain the composite ultrafiltration membrane. The composite ultrafiltration membrane prepared by the invention has high flux, high selectivity and excellent anti-pollution performance, and is particularly suitable for treating and recycling wastewater containing organic macromolecules such as proteins, colloids and the like.

Inventors

  • WANG QIWEI
  • CUI JIAYI
  • CAO LIN
  • ZHANG PENG
  • DU WENBO
  • YANG JUNJIE
  • Cai Xiaoye

Assignees

  • 暨南大学

Dates

Publication Date
20260505
Application Date
20260123

Claims (10)

  1. 1. The preparation method of the composite ultrafiltration membrane based on blending modification and surface modification is characterized by comprising the following steps of: (1) Dispersing carbon nano tubes in water to obtain a dispersion liquid, adding dopamine compounds, carrying out polymerization reaction, and filtering to obtain filter residues to obtain the polydopamine functionalized multi-wall carbon nano tubes; (2) Adding a film-forming polymer, a pore-forming agent and the polydopamine functionalized multi-wall carbon nano tube in the step (1) into an organic solvent, uniformly dispersing, preparing a film casting solution, and preparing a blend film; (3) And (3) soaking the blending film in the step (2) in a tannic acid solution and an aluminum salt solution in sequence to obtain the composite ultrafiltration film based on blending modification and surface modification.
  2. 2. The preparation method of the dopamine compound, according to claim 1, is characterized in that the dopamine compound in the step (1) is at least one of dopamine hydrochloride, dopamine methyl ester hydrochloride and 6-hydroxydopamine hydrochloride, the carbon nanotubes are at least one of multi-wall carbon nanotubes, single-wall carbon nanotubes and double-wall carbon nanotubes, the mass ratio of the carbon nanotubes to the dopamine compound is 1:1-1:3, and the mass volume ratio of the carbon nanotubes to water in the step (1) is 0.25-1:1 g/L.
  3. 3. The process according to claim 1, wherein in the step (1), the pH of the dispersion is adjusted to be alkaline before the dopamine compound is added, the polymerization in the step (1) is carried out in a stirring state at a stirring rate of 500 to 800 r/min for a polymerization time of 6 to 24 h.
  4. 4. The method according to claim 1, wherein the film-forming polymer in the step (2) is at least one of polyethersulfone, polysulfone, polyvinylidene fluoride and polyacrylonitrile, and the pore-forming agent is at least one of polyvinylpyrrolidone, polyethylene glycol and polyethylene oxide.
  5. 5. The method according to claim 1, wherein the organic solvent in the step (2) is at least one of N, N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide and N, N-dimethylformamide, and the concentration of the film-forming polymer in the casting solution is 10-20 wt%, the concentration of the pore-forming agent is 0.5-5 wt%, and the concentration of the polydopamine-functionalized multi-walled carbon nanotube is 0.1-1 wt%.
  6. 6. The method according to claim 1, wherein in the step (2), the preparation of the casting solution comprises the steps of: adding the porogen and the polydopamine functionalized multi-wall carbon nano tube in the step (1) into an organic solvent, uniformly dispersing by ultrasonic, then adding a film forming polymer, and stirring for 4-8 h at the temperature of 40-80 ℃ to obtain a casting solution.
  7. 7. The method of claim 1, wherein the preparing a blend film of step (2) comprises the steps of: And standing the casting solution for defoaming for 12-48 h hours to obtain defoamed casting solution, and preparing the blend membrane by a submerged precipitation phase inversion method.
  8. 8. The preparation method of the tannic acid film according to claim 1, wherein the concentration of the tannic acid solution in the step (3) is 0.1-1 g/L, the soaking time of the blend film in the tannic acid solution is 10-300 s, the aluminum salt solution is a solution obtained by uniformly mixing aluminum salt with water, the aluminum salt is at least one of aluminum trichloride hexahydrate, aluminum sulfate, aluminum nitrate and alum, the mass-volume ratio of the aluminum salt to the water is 0.01-0.1:1 g/L, and the soaking time of the blend film in the aluminum salt solution is 10-300 s.
  9. 9. A composite ultrafiltration membrane based on blend modification and surface modification made by the method of any of claims 1-8.
  10. 10. The use of the composite ultrafiltration membrane based on blending modification and surface modification in wastewater treatment and reuse according to claim 9.

Description

Composite ultrafiltration membrane based on blending modification and surface modification, and preparation method and application thereof Technical Field The invention relates to the technical field of membrane separation, in particular to a composite ultrafiltration membrane based on blending modification and surface modification, and a preparation method and application thereof. Background With the global population growth and industrial development, the increase of the discharge amount of industrial wastewater seriously jeopardizes the water environment health, aggravates the water resource shortage crisis and jeopardizes the health development of human society, so the separation and purification technology aiming at wastewater treatment is gradually and widely focused. The treatment and recycling of the electroplating wastewater are important ways for solving the shortage of industrial water and are also important requirements for green development of the electroplating industry in China. The electroplating effluent has the advantages of multiple sources, large volume, complex components, large water quality fluctuation, high pollution degree, poor effect of a single wastewater treatment mode, high energy consumption, high cost and low removal rate. Therefore, finding an economic, efficient and environment-friendly technology for sustainable water production of electroplating effluent is a difficult problem to be solved in the current electroplating industry in China. The membrane separation technology has the advantages of simple operation flow, stable water quality and the like, and is more and more concerned and researched in wastewater treatment application. The ultrafiltration membrane technology is used as a physical separation process taking pressure as a driving force, and has the advantages of simple operation, low energy consumption, no phase change and the like, thereby showing great application potential in the field of water treatment. Among them, polyethersulfone (PES) is widely used as an ultrafiltration membrane material due to its excellent mechanical strength, thermal stability and film forming property. However, the inherent hydrophobicity of PES makes it very difficult to meet two key challenges in practical applications, namely, the fact that the membrane surface is easily polluted by organic matters such as proteins, the flux is drastically reduced and is difficult to recover, and the membrane life is shortened, and the fact that the ubiquitous "flux-selectivity trade-off effect", namely, the high rejection rate, is often at the expense of the permeation flux of water. Studies show that hydrophilic modification of separation membranes is a key to improving the anti-pollution capability of separation membranes, and the main hydrophilic modification methods at present comprise blending modification technology and surface modification technology. The blending modification is to uniformly disperse hydrophilic filler into the casting film liquid in a dissolving or dispersing form, and then prepare the blending film by adopting a blade coating and phase inversion method. The blending modification method has the advantages of wide filler source, low cost, easy amplification and the like, however, the compatibility among different polymers needs to be considered when introducing new modification materials into the original casting film liquid system, which can influence the phase separation and the film pore structure in the film forming process, thereby influencing the related performance of the ultrafiltration film. CN108771978 a discloses a preparation method of a modified ultrafiltration membrane by blending nano cellulose crystals, and the modified ultrafiltration membrane is prepared by introducing nano cellulose crystals, so that the anti-pollution performance and the pure water flux are remarkably improved. However, if the process is controlled improperly, the nanocellulose crystals may still agglomerate, which affects the uniformity of the film. The surface modification is to modify the surface of the membrane after the membrane is formed so as to improve the surface property of the membrane, achieve the purposes of enhancing the anti-fouling performance, improving the separation efficiency and the like, and has the defects that the modification can cause the blocking of surface pore channels and cause the reduction of the membrane flux. CN120079271a discloses an amino acid derivative polymeric membrane material and a preparation method thereof, and the functional membrane material with high selectivity, good biocompatibility and stability is prepared through copolymerization of amino acid derivative and polyether, spin coating film formation, surface modification and crosslinking treatment. However, the surface modification strategy adopted by the method has the risks of weak bonding force between the modification layer and the base film and easy occurrence of radical falling or