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CN-121988181-A - Polyester amide composite nanofiltration membrane and preparation method and application thereof

CN121988181ACN 121988181 ACN121988181 ACN 121988181ACN-121988181-A

Abstract

The invention relates to the technical field of nanofiltration membrane preparation, in particular to a polyester amide composite nanofiltration membrane, and a preparation method and application thereof. The invention takes a porous support membrane as a substrate, and utilizes a polyol aqueous phase monomer solution and an organic phase monomer solution to form an initial polyester active layer on the surface of the substrate, wherein the initial polyester active layer is usually loose in structure or uneven in pore size distribution. And immersing the initial polyester active layer in an aqueous solution containing an amine monomer for embedding grafting, and performing heat treatment to obtain the polyester amide composite nanofiltration membrane assembled by the embedded small molecular amine. The polyester amide composite nanofiltration membrane can maintain stable separation performance in a long-term chlorine contact process when being applied to water treatment, and the service life of the membrane is prolonged. Meanwhile, the polyester film grafted by the amine shows the characteristic of a polyester amide composite nanofiltration film, the aperture of the polyester film is reduced, and the interception of small molecular organic matters can be improved.

Inventors

  • LIU YANLING
  • FAN KAIMING
  • XIA SHENGJI

Assignees

  • 同济大学

Dates

Publication Date
20260508
Application Date
20260213

Claims (10)

  1. 1. The preparation method of the polyester amide composite nanofiltration membrane is characterized by comprising the following steps of: Taking a porous support film as a substrate, sequentially placing an aqueous phase monomer solution and an organic phase monomer solution in the substrate, and carrying out interfacial polymerization reaction on the aqueous phase monomer solution and the organic phase monomer solution on the surface of the substrate to form an initial polyester active layer, wherein the aqueous phase monomer solution is prepared by mixing a polyalcohol compound and an alkali solution, and the organic phase monomer is an acyl chloride compound; immersing the initial polyester active layer in an aqueous solution containing an amine monomer, and then performing heat treatment to enable the amine monomer to permeate into the initial polyester active layer, and performing grafting reaction with acyl chloride groups remained in the organic phase monomer to form a compact polyester amide active layer, thereby obtaining the polyester amide composite nanofiltration membrane, wherein the amine monomer is piperazine.
  2. 2. The method for preparing the polyesteramide composite nanofiltration membrane according to claim 1, wherein the mass concentration of the aqueous solution containing the amine monomer is 0.2wt% to 2.0wt%.
  3. 3. The method for preparing the polyesteramide composite nanofiltration membrane according to claim 1, wherein the mass concentration of the polyalcohol compound in the aqueous monomer solution is 1.0wt% to 10.0wt%; The mass concentration of the organic phase monomer solution is 0.05-0.5 wt%, and the solvent of the organic phase monomer solution is n-hexane or cyclohexane.
  4. 4. The method for preparing a polyesteramide composite nanofiltration membrane according to claim 3, wherein the polyalcohol compound is at least one selected from erythritol, xylitol, glucose, sucrose and beta-cyclodextrin, and the organic phase monomer is trimesoyl chloride.
  5. 5. The method for preparing the polyesteramide composite nanofiltration membrane according to claim 1, wherein the mass concentration of the alkali solution is 0.1wt% to 2wt%.
  6. 6. The method for preparing the polyesteramide composite nanofiltration membrane according to claim 1, wherein the heat treatment temperature is 60 ℃, the time is 1 min-20 min, and the time of interfacial polymerization reaction is 60 s-600 s.
  7. 7. The method for preparing a polyesteramide composite nanofiltration membrane according to claim 1, wherein the substrate has a molecular weight cut-off of 20kDa.
  8. 8. The polyester amide composite nanofiltration membrane is characterized in that the polyester amide composite nanofiltration membrane is prepared by the preparation method of the polyester amide composite nanofiltration membrane according to any one of claims 1-7.
  9. 9. The polyesteramide composite nanofiltration membrane of claim 8, wherein the polyesteramide composite nanofiltration membrane has a molecular weight cutoff of 229da to 754da.
  10. 10. Use of a polyester amide composite nanofiltration membrane in water treatment and purification, wherein the polyester amide composite nanofiltration membrane is the polyester amide composite nanofiltration membrane of claim 8.

Description

Polyester amide composite nanofiltration membrane and preparation method and application thereof Technical Field The invention relates to the technical field of nanofiltration membrane preparation, in particular to a polyester amide composite nanofiltration membrane, and a preparation method and application thereof. Background With the rise of the demand of people for high-quality drinking water, the conventional water treatment process is difficult to cope with the raw water body with complex and high removal rate requirements, and the advanced treatment process is generated. The membrane technology is applied to a plurality of drinking water treatment plants due to high efficiency, energy conservation and environmental protection. Nanofiltration is taken as a novel separation process, can effectively remove small molecular organic matters in water, allows partial beneficial mineral salt ions to permeate, has excellent water/solute selective separation performance, and is considered as one of the best production modes of high-quality drinking water. The nanofiltration membrane widely applied at the present stage is mostly a composite nanofiltration membrane, and the preparation process is simple and convenient, has low cost and can be flexibly designed and produced according to the needs. Chlorine is an oxidant and a disinfectant commonly used for water treatment, has low cost and wide application, and is commonly used for raw water pretreatment, nanofiltration membrane cleaning, degradation-resistant organic matter oxidation and produced water disinfection. However, most commercial nanofiltration membranes currently sold in the market and used in drinking water plants are polyamide nanofiltration membranes, the polyamide nanofiltration membranes are prepared by interfacial polymerization of diamine monomers and acyl chloride monomers, the active layer of the polyamide nanofiltration membranes contains reaction sites which are easily attacked by active chlorine, and the polyamide nanofiltration membranes are difficult to clean by NaClO solution with high cleaning efficiency when the membranes are polluted. During long-term operation, pollutants and microorganisms can be accumulated on the surface of the membrane, and the flux is recovered by using a chlorine cleaning agent, so that the risk of damaging the membrane is increased. In addition, the polyamide nanofiltration membrane has poor chemical stability, and the oxidation-reduction potential of the inlet water is strictly controlled by an additional monitoring and processing method, so that the running cost of the nanofiltration process is greatly increased. While researchers have attempted to improve chlorine resistance to nanofiltration membrane surface modification, surface grafting and surface coating are often not suitable for practical applications at the expense of nanofiltration membrane water flux or retention. For this reason, researchers have tried to replace amine monomers with polyhydroxy compounds to prepare polyester nanofiltration membranes, which have reduced chlorine attack sites on the active layer, improved chemical stability of chlorine, and enhanced anti-pollution ability due to a large number of hydrophilic groups on the surface. However, the prepared polyester nanofiltration membrane has large pore diameter and is difficult to effectively intercept small molecular organic matters because of low reactivity of hydroxyl and acyl chloride groups. Disclosure of Invention In order to solve the technical problems, the invention provides a polyester amide composite nanofiltration membrane, a preparation method and application thereof, and the aperture of the polyester membrane is reduced to improve the interception capability of the polyester membrane to organic matters on the premise of not losing the advantage of chlorine resistance. The invention takes a porous support membrane as a substrate, and utilizes a polyol aqueous phase monomer solution and an organic phase monomer solution to form an initial polyester active layer on the surface of the substrate, wherein the initial polyester active layer is usually loose in structure or uneven in pore size distribution. Then taking piperazine as an amine monomer, immersing an initial polyester active layer in an aqueous solution containing the amine monomer for embedded grafting, and performing heat treatment to obtain the high-performance chlorine-resistant polyester amide composite nanofiltration membrane assembled by embedded amine. The polyester amide composite nanofiltration membrane can maintain stable separation performance in a long-term chlorine contact process when being applied to water treatment, and the service life of the membrane is prolonged. Meanwhile, the polyester film shows the characteristic of a polyester amide composite nanofiltration membrane after piperazine grafting, the pore diameter of the polyester film is reduced, and the interception of small molecular organic