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CN-121550846-B - Composite nanofiltration membrane and preparation method and application thereof

CN121550846BCN 121550846 BCN121550846 BCN 121550846BCN-121550846-B

Abstract

The invention relates to a composite nanofiltration membrane and a preparation method and application thereof, wherein the preparation method of the composite nanofiltration membrane comprises the following steps of preparing a water-soluble polymer modified by quaternary ammonium salt, a cross-linking agent and water into a pretreatment liquid, preparing a polyamine, an anionic surfactant and an organic acid into an organic acid phase solution, wherein the organic acid is saturated fatty acid with 5-7 carbon atoms, placing the pretreatment liquid on the surface of a support membrane, forming a positively charged intermediate layer through a cross-linking reaction, sequentially placing the organic acid phase solution and an oil phase solution containing polybasic acyl chloride on the surface of the positively charged intermediate layer far away from the support membrane, and forming a separation layer through heat treatment to obtain the composite nanofiltration membrane. The composite nanofiltration membrane prepared by the preparation method can have the performance of high water flux and high retention rate when being applied to water treatment.

Inventors

  • SHI YINGYING
  • CHEN KEKE
  • CHENG XIN
  • Pan Eryi
  • PAN QIAOMING

Assignees

  • 蓝星（杭州）膜工业有限公司
  • 杭州水处理技术研究开发中心有限公司

Dates

Publication Date
20260508
Application Date
20260123

Claims (10)

  1. 1. The preparation method of the composite nanofiltration membrane is characterized by comprising the following steps of: preparing a quaternary ammonium salt modified water-soluble polymer, a cross-linking agent and water into a pretreatment liquid; Preparing polyamine, an anionic surfactant and an organic acid into an organic acid phase solution, wherein the organic acid is saturated fatty acid with 5-7 carbon atoms; placing the pretreatment liquid on the surface of a support film, and forming a positively charged intermediate layer through a crosslinking reaction; And sequentially placing the organic acid phase solution and the oil phase solution containing the polybasic acyl chloride on the surface of the positively charged intermediate layer, which is far away from the support membrane, and forming a separation layer through heat treatment to obtain the composite nanofiltration membrane.
  2. 2. The method for preparing the composite nanofiltration membrane according to claim 1, wherein the mass fraction of the quaternary ammonium salt modified water-soluble polymer in the pretreatment liquid is 0.1% -2%; and/or the quaternary ammonium salt modified water-soluble polymer is selected from at least one of chitosan quaternary ammonium salt, quaternized cellulose or quaternized polyethyleneimine.
  3. 3. The method for preparing a composite nanofiltration membrane according to claim 1, wherein the mass fraction of the crosslinking agent in the pretreatment liquid is 0.1% -2%; and/or the cross-linking agent is selected from dialdehydes, wherein the dialdehydes are selected from at least one of glutaraldehyde, glyoxal, malondialdehyde or glyoxal.
  4. 4. The method for preparing a composite nanofiltration membrane according to claim 1, wherein the mass fraction of the anionic surfactant in the organic acid phase solution is 0.02% -0.5%; And/or the anionic surfactant is selected from at least one of sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium dodecyl benzene sulfonate or sodium dioctyl sulfosuccinate.
  5. 5. The method for preparing a composite nanofiltration membrane according to claim 1, wherein the organic acid is at least one selected from n-valeric acid, n-caproic acid, isocaproic acid or heptanoic acid.
  6. 6. The method for preparing a composite nanofiltration membrane according to claim 1, wherein the mass fraction of the polyamine in the organic acid phase solution is 0.1% -2%; and/or the polyamine is selected from at least one of piperazine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, N-dimethyl-m-phenylenediamine, trimellitic amine, cyclohexanediamine, ethylenediamine, triethanolamine, polyethyleneimine, polyetheramine, aniline, m-toluidine, o-toluidine, p-nitroaniline or m-fluoroaniline.
  7. 7. The method for preparing the composite nanofiltration membrane according to claim 1, wherein the mass fraction of the polybasic acyl chloride in the oil phase solution containing the polybasic acyl chloride is 0.05% -0.2%; and/or the polybasic acyl chloride is selected from at least one of trimesoyl chloride, terephthaloyl chloride or isophthaloyl chloride.
  8. 8. The method according to any one of claims 1 to 7, wherein in the step of forming the positively charged intermediate layer by a crosslinking reaction, the crosslinking reaction temperature is 25 ℃ to 40 ℃ and the crosslinking reaction time is 1min to 10min; and/or sequentially placing the organic acid phase solution and the oil phase solution containing the polybasic acyl chloride on the surface of the positively charged intermediate layer far away from the support membrane, wherein the specific steps are that firstly, the organic acid phase solution is placed on the surface of the positively charged intermediate layer far away from the support membrane, after standing for 30-180 seconds, the excessive organic acid phase solution is removed, then, the oil phase solution containing the polybasic acyl chloride is placed on the surface of the positively charged intermediate layer far away from the support membrane, and after standing for 20-60 seconds, the excessive oil phase solution containing the polybasic acyl chloride is removed; And/or, in the step of forming the separation layer by heat treatment, the heat treatment temperature is 60 ℃ to 110 ℃ and the heat treatment time is 3min to 10min.
  9. 9. A composite nanofiltration membrane prepared by the method of preparing a composite nanofiltration membrane as claimed in any one of claims 1 to 8.
  10. 10. Use of the composite nanofiltration membrane of claim 9 in a water treatment plant.

Description

Composite nanofiltration membrane and preparation method and application thereof Technical Field The invention relates to the technical field of water treatment membranes, in particular to a composite nanofiltration membrane and a preparation method and application thereof. Background Nanofiltration membrane is used as a high-efficiency pressure driving membrane, and has unique separation performance on divalent ions and micromolecular organic matters, so that the nanofiltration membrane has been widely applied to the fields of drinking water softening, sea water desalination, wastewater reuse, material separation, concentration and the like. At present, nanofiltration membranes are mostly prepared by adopting an interfacial polymerization method. The traditional interfacial polymerization method strictly depends on a water phase-oil phase system, however, in the process of preparing the nanofiltration membrane, the interfacial polymerization is difficult to accurately regulate and control due to the fact that amine monomers in the water phase solution diffuse too fast, meanwhile, the surface spreadability of the water phase solution on the surface of a hydrophobic or charged support membrane is poor due to the fact that the formed polyamide layer has uneven thickness and structural defects, and finally, the prepared nanofiltration membrane has obvious balance effect between the retention rate and the water flux, and the performance of high water flux and high retention rate is difficult to achieve. Disclosure of Invention Based on the above, it is necessary to provide a composite nanofiltration membrane, a preparation method and application thereof, wherein the composite nanofiltration membrane prepared by the preparation method has the performance of high water flux and high retention rate when being applied to water treatment. The preparation method of the composite nanofiltration membrane comprises the following steps: preparing a quaternary ammonium salt modified water-soluble polymer, a cross-linking agent and water into a pretreatment liquid; Preparing polyamine, an anionic surfactant and an organic acid into an organic acid phase solution, wherein the organic acid is saturated fatty acid with 5-7 carbon atoms; placing the pretreatment liquid on the surface of a support film, and forming a positively charged intermediate layer through a crosslinking reaction; And sequentially placing the organic acid phase solution and the oil phase solution containing the polybasic acyl chloride on the surface of the positively charged intermediate layer, which is far away from the support membrane, and forming a separation layer through heat treatment to obtain the composite nanofiltration membrane. In one embodiment, the mass fraction of the quaternary ammonium salt modified water-soluble polymer in the pretreatment liquid is 0.1% -2%; And/or the quaternary ammonium salt modified water-soluble polymer is at least one selected from chitosan quaternary ammonium salt, quaternized cellulose and quaternized polyethyleneimine. In one embodiment, the mass fraction of the cross-linking agent in the pretreatment liquid is 0.1% -2%; and/or the cross-linking agent is selected from dialdehydes, wherein the dialdehydes are selected from at least one of glutaraldehyde, glyoxal, malondialdehyde or glyoxal. In one embodiment, the mass fraction of the anionic surfactant in the organic acid phase solution is 0.02% -0.5%; And/or the anionic surfactant is selected from at least one of sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium dodecyl benzene sulfonate or sodium dioctyl sulfosuccinate. In one embodiment, the organic acid is selected from at least one of n-valeric acid, n-caproic acid, isocaproic acid, or heptanoic acid. In one embodiment, the mass fraction of the polyamine in the organic acid phase solution is 0.1% -2%; and/or the polyamine is selected from at least one of piperazine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, N-dimethyl-m-phenylenediamine, trimellitic amine, cyclohexanediamine, ethylenediamine, triethanolamine, polyethyleneimine, polyetheramine, aniline, m-toluidine, o-toluidine, p-nitroaniline or m-fluoroaniline. In one embodiment, the mass fraction of the polyacyl chloride in the oil phase solution containing the polyacyl chloride is 0.05% -0.2%; and/or the polybasic acyl chloride is selected from at least one of trimesoyl chloride, terephthaloyl chloride or isophthaloyl chloride. In one embodiment, in the step of forming the positively charged intermediate layer through the crosslinking reaction, the crosslinking reaction temperature is 25 ℃ to 40 ℃ and the crosslinking reaction time is 1min to 10min; and/or sequentially placing the organic acid phase solution and the oil phase solution containing the polybasic acyl chloride on the surface of the positively charged intermediate layer far away from the support membrane, wherein the specific steps are that firstly, the organic acid p