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CN-116272428-B - Selective layer material for reverse osmosis membrane and preparation method and application thereof

CN116272428BCN 116272428 BCN116272428 BCN 116272428BCN-116272428-B

Abstract

The invention discloses a selective layer material for a reverse osmosis membrane, and a preparation method and application thereof. The selective layer material is self-polymerized microporous polymer obtained by the dehydration condensation reaction copolymerization of aromatic diamine and dianhydride. The preparation method comprises the steps of pre-polymerizing a mixed reaction system containing aromatic diamine, dianhydride and solvent, and then heating to perform dehydration condensation reaction to obtain the selective layer material. And mixing the selective layer material with a casting solution solvent to form polymer casting solution, and applying the polymer casting solution to a base film to perform film forming treatment to obtain the reverse osmosis film with the selective layer. The selective layer material and the reverse osmosis membrane prepared by the method have the selectivity of 99% to NaCl, can resist chlorine 15000ppm & h under the active chlorine concentration of 500ppm, have high mass transfer efficiency and good separation effect, and have important application values in the fields of high-purity water equipment such as sea water desalination, food and the like, membrane separation and medical treatment.

Inventors

  • LIU DIXIN
  • FANG WANGXI
  • JIN JIAN

Assignees

  • 中国科学院苏州纳米技术与纳米仿生研究所

Dates

Publication Date
20260512
Application Date
20230327

Claims (10)

  1. 1. A method for preparing a reverse osmosis membrane, comprising: Mixing a selective layer material for a reverse osmosis membrane with a casting solution solvent to form a polymer casting solution, wherein the selective layer material is a self-polymerized microporous polymer obtained by carrying out dehydration condensation reaction on aromatic diamine and dianhydride, the dianhydride is selected from any one or more than two of 3,3', 4' -diphenyl sulfone tetracarboxylic dianhydride, 3', 4' -benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride and 4,4' - (hexafluoroisopropylidene) diphthalic anhydride, the aromatic diamine is selected from any one or more than two of 2.3,5,6-tetramethyl-1, 4-phenylenediamine, bis (4-aminophenyl) sulfone, 3, 5-diaminobenzoic acid and Tacrogol base diamine monomers, the dianhydride and the aromatic diamine are not simultaneously one type, the specific surface area of the self-polymerized microporous polymer is more than 200m 2 g -1 , and the pore size distribution is 4-7 a, the preparation method of the selective layer material comprises the steps of heating the mixed solvent containing aromatic diamine and the dianhydride to a mixed solvent for carrying out dehydration reaction for 1-250 h at a temperature of 1-18 ℃ with the aromatic diamine, and a dehydration reaction time of 1-250 h to obtain an aromatic diamine-18; applying the polymer casting solution to a base film, and performing film forming treatment to obtain a reverse osmosis film with a selective layer; The thickness of the selection layer is 200-700 nm, the selectivity of the reverse osmosis membrane to NaCl is more than 90%, and the reverse osmosis membrane can resist chlorine 12000 ppm-h at an active chlorine concentration of 500 ppm.
  2. 2. The method according to claim 1, wherein the casting solution solvent is one or a combination of tetrahydrofuran and N, N-dimethylformamide.
  3. 3. The method of claim 1, wherein the concentration of the polymer casting solution is 2-6wt%.
  4. 4. The method of claim 1, wherein the film forming process is performed at a temperature of 20 to 30 ℃.
  5. 5. The method of claim 1, wherein the film forming process comprises a rotary evaporation coating process at a rotational speed of 3000-5000 r/min for a time of 20-50 s.
  6. 6. The method of claim 1, wherein the carrier film is an ultrafiltration film.
  7. 7. The method of claim 1, wherein the reverse osmosis membrane has a NaCl selectivity of 95% or more.
  8. 8. The method of claim 1, wherein the dehydration condensation reaction time is 4 to 6 hours.
  9. 9. The method of claim 1, wherein the solvent is ultra-dry N, N-dimethylpyrrolidone.
  10. 10. Use of a reverse osmosis membrane produced by the production method of any one of claims 1 to 9 in the field of sea water desalination equipment, food equipment, porous adsorption material production, membrane separation or medical treatment.

Description

Selective layer material for reverse osmosis membrane and preparation method and application thereof Technical Field The invention relates to a reverse osmosis membrane material, in particular to a selective layer material with high selectivity for a reverse osmosis membrane, and a preparation method and application thereof, and belongs to the technical field of reverse osmosis membrane materials. Background Polyamide Reverse Osmosis (RO) membranes have achieved commercial success in desalination, but inherent drawbacks of materials such as intolerance to active chlorine have prevented RO membrane permeation from being used in water treatment, and improving chemical stability has important implications for membrane separation. For many years, a great deal of researches are carried out to improve the permeation selectivity and chemical stability of the polyamide membrane by means of monomer selection, interfacial polymerization process regulation and control, post-treatment, nano material compounding and the like, but the polyamide membrane is limited by the chemical composition and the preparation method, and the other type of cellulose acetate material and polyester material which are applied more also have the problems of poor selectivity, poor acid and alkali resistance and the like. The method is characterized in that the method is used for jumping out of the existing material system, and searching for a membrane material with excellent chemical stability and excellent selectivity is still a very serious challenge in the field of membrane separation modification. Therefore, by designing the molecular structure of the microporous polymer material, the problem of poor chlorine resistance, oxidation resistance and acid-base resistance of the traditional reverse osmosis membrane is fundamentally solved, so that the characteristics of excellent chemical stability, high specific surface area and high free volume are exerted, and the preparation of the novel oxidation-resistant acid-base-resistant polymer desalination membrane with excellent water permeability and selectivity is a direction of long-standing efforts of researchers in the industry. Disclosure of Invention The invention mainly aims to provide a selective layer material for a reverse osmosis membrane with high selectivity and a preparation method thereof, so as to solve the problem of insufficient chemical stability of the reverse osmosis membrane in the prior art. It is still another object of the present invention to provide a method for preparing a reverse osmosis membrane using the selective layer material. In order to achieve the purpose of the invention, the technical scheme adopted by the invention comprises the following steps: The embodiment of the invention provides a selective layer material for a reverse osmosis membrane, which is an autopolymicroporous polymer obtained by the copolymerization of aromatic diamine and dianhydride (also called as 'tetracarboxylic anhydride matters') through dehydration condensation reaction. Wherein the dianhydride comprises any one or more than two of 3,3', 4' -diphenyl sulfone tetracarboxylic dianhydride, 3', 4' -benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, 4' - (hexafluoroisopropylidene) diphthalic anhydride and the like. The embodiment of the invention provides a preparation method of a selective layer material for a reverse osmosis membrane, which comprises the following steps: the mixed reaction system containing aromatic diamine, dianhydride and solvent is prepolymerized, and then the temperature is raised to carry out dehydration condensation reaction, so as to obtain the selective layer material for the reverse osmosis membrane. The embodiment of the invention also provides a preparation method of the reverse osmosis membrane, which comprises the following steps: mixing the selective layer material for the reverse osmosis membrane with a casting solution solvent to form polymer casting solution; and (3) applying the polymer casting solution to a base film, and performing film forming treatment to obtain the reverse osmosis film with the selective layer. Correspondingly, the embodiment of the invention also provides the reverse osmosis membrane with the selective layer, which is prepared by the preparation method. The embodiment of the invention also provides the selective layer material for the reverse osmosis membrane or application of the reverse osmosis membrane in the fields of sea water desalination equipment, food equipment, porous adsorption material preparation, membrane separation, medical treatment and the like. Compared with the prior art, the invention has the beneficial effects that: 1) The selective layer material provided by the invention is self-polymerized microporous polyimide polymer with rigid main chain, has no hydrogen atoms on the amide bond of the polymer, lacks active chlorine attack sites, has strong chemical stability of the rigid main chain, and