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CN-121975166-A - Imidazolium functional polyimide anion exchange membrane for recovering diffusion dialysis acid and preparation method thereof

CN121975166ACN 121975166 ACN121975166 ACN 121975166ACN-121975166-A

Abstract

The invention relates to an imidazolium functional polyimide anion exchange membrane for recovering diffusion dialysis acid and a preparation method thereof, belonging to the technical field of high-molecular functional membrane materials. The method comprises the steps of firstly preparing self-microporous polyimide PI-6B containing a hexabenzyl structural unit through polycondensation reaction of dianhydride monomer BPA-2a and aromatic diamine monomer, then carrying out bromomethylation modification on the self-microporous polyimide PI-6B by adopting liquid bromine to obtain brominated polyimide PI-6B-Br, and then carrying out nucleophilic substitution reaction on an imidazole compound to introduce an imidazolium cation functional group into a polymer main chain to obtain the imidazolium functional polyimide anion exchange membrane. The obtained anion exchange membrane has higher ion exchange capacity, higher acid dialysis coefficient and excellent acid/salt separation factor, and has good application prospect in the field of waste acid diffusion dialysis recovery.

Inventors

  • LIN XIAOCHENG
  • Shen Senbin
  • YANG LAN

Assignees

  • 福州大学

Dates

Publication Date
20260505
Application Date
20260317

Claims (10)

  1. 1. A process for preparing an imidazolium-functionalized polyimide anion exchange membrane for the recovery of diffusion dialysis acids, comprising the steps of: s1, preparing dianhydride monomer BPA-2a: (1) 3-methyl catechol is used as a raw material, and is subjected to condensation reaction with acetone under an acidic condition to prepare a methylated tetrahydroxy monomer TTSBI-M; (2) Making TTSBI-M and 4, 5-dichlorophthalonitrile undergo the nucleophilic substitution reaction under the alkaline condition so as to obtain an intermediate BPN-2a; (3) Carrying out hydrolysis reaction on the BPN-2a in an alkaline alcohol-water system to generate a tetracarboxylic acid intermediate, and then carrying out dehydration cyclization reaction on acetic anhydride to obtain dianhydride monomer BPA-2a; S2, preparing polyimide PI-6B: Adding the dianhydride monomer BPA-2a and 2,3,5, 6-tetramethyl-1, 4-phenylenediamine into m-cresol, performing polycondensation reaction under the condition of the existence of a catalyst and the protection of inert gas, and separating out a polymer after high-temperature imidization reaction to obtain polyimide PI-6B containing a hexabenzyl structural unit; S3, bromomethylation modification: under the protection of inert gas, dissolving the PI-6B in an aromatic organic solvent, heating to 120-150 ℃, dropwise adding a mixed solution formed by bromine and the organic solvent, carrying out bromomethylation reaction on benzyl on a polyimide molecular chain to obtain brominated polyimide PI-6B-Br, and preparing a polyimide base film by a solvent pouring method; s4, imidazolium functionalization: And immersing the polyimide base film in an organic solution containing an imidazole compound, and carrying out nucleophilic substitution reaction at the temperature of 30-60 ℃ to enable bromomethyl groups to react with the imidazole compound to generate imidazolium cationic groups, so as to obtain the imidazolium functionalized polyimide anion exchange film.
  2. 2. The process according to claim 1, wherein the catalyst in S2 is quinoline.
  3. 3. The process of claim 1, wherein the brominated polyimide PI-6B-Br has a bromination of 30-90%.
  4. 4. The process according to claim 1, wherein the solvent in S3 for dissolving PI-6B-Br is any one of N, N-dimethylformamide, chloroform and N-methylpyrrolidone.
  5. 5. The method according to claim 1, wherein the imidazole compound in S4 is any one of 1-methylimidazole, 2-methylimidazole and 1, 2-dimethylimidazole.
  6. 6. The method of claim 1, wherein the concentration of the organic solution containing the imidazole compound in S4 is 0.2-2 mol L -1 .
  7. 7. The method of claim 1, wherein the nucleophilic substitution reaction time in S4 is 1 to 5 hours.
  8. 8. The method of claim 1, wherein the thickness of the anion exchange membrane is 30-60 μm.
  9. 9. The polyimide anion exchange membrane according to any one of claims 1 to 8, wherein the anion exchange membrane comprises a polyimide skeleton containing a hexabenzyl structural unit and an imidazolium cation functional group.
  10. 10. Use of a polyimide anion exchange membrane according to claim 9 in the recovery of diffusion dialysis acids.

Description

Imidazolium functional polyimide anion exchange membrane for recovering diffusion dialysis acid and preparation method thereof Technical Field The invention belongs to the technical field of polymer functional membrane materials, and particularly relates to an imidazolium functional polyimide anion exchange membrane for recovering diffusion dialysis acid and a preparation method thereof. Background The acid substances are important raw materials which are indispensable in the industrial production processes of metallurgy, electroplating, chemical industry, steel pickling, electronic manufacturing and the like, and are widely applied to the technological links of metal surface treatment, mineral leaching, pickling rust removal, chemical synthesis and the like. In actual industrial operation, a large amount of acid liquor is converted into a waste acid solution containing metal ions after use, for example, a hydrochloric acid or sulfuric acid system containing metal ions such as Fe 2+、Zn2+、Cu2+. If the waste acid is directly discharged without treatment, serious environmental pollution can be caused, and waste of acid resources can be caused. Therefore, the realization of high-efficiency recovery and resource utilization of the waste acid has important environmental and economic significance. At present, the waste acid treatment method mainly comprises a neutralization precipitation method, an evaporation concentration method, an extraction method, a membrane separation method and the like. The neutralization precipitation method is simple in process, a large amount of salt-containing sludge is produced, secondary pollution is caused, the evaporation concentration method is high in energy consumption and operation cost, and the extraction method has organic solvent loss and safety risks. In contrast, the diffusion dialysis technology is a membrane separation technology taking concentration difference as driving force, utilizes an anion exchange membrane to realize the selective separation of acid and metal salt, does not need an external electric field or high temperature condition, has the advantages of low energy consumption, simple equipment structure, stable operation and the like, and has good application prospect in the field of waste acid recycling. However, the core of diffusion dialysis technology is the performance of anion exchange membranes. The conventional anion exchange membrane generally has the problems of limited free volume, discontinuous ion transmission channels, low acid permeation rate, insufficient long-term stability under a strong acid environment and the like. Therefore, it is of great importance to develop an anion exchange membrane with high acid permeation rate, high separation selectivity and good structural stability. Disclosure of Invention The invention aims to provide an imidazolium functionalized polyimide anion exchange membrane and a preparation method thereof, which are used for solving the problem that mass transfer efficiency and structural stability of the existing anion exchange membrane are difficult to consider in the diffusion dialysis process. According to the invention, a polyimide with a hexabenzyl structure and a larger intrinsic free volume is used as a framework material, a benzyl bromide active site is introduced through liquid bromination, and an imidazolium cation functional group is introduced through quaternization of an imidazole compound, so that an anion exchange membrane structure with a continuous ion transmission channel is constructed. In order to achieve the above purpose, the invention adopts the following technical scheme: A method for preparing an imidazolium-functionalized polyimide anion exchange membrane for diffusion dialysis acid recovery, comprising the steps of: s1, preparing dianhydride monomer BPA-2a: (1) 3-methyl catechol is used as a raw material, and is subjected to condensation reaction with acetone under an acidic condition to prepare a methylated tetrahydroxy monomer TTSBI-M; (2) Making TTSBI-M and 4, 5-dichlorophthalonitrile undergo the nucleophilic substitution reaction under the alkaline condition so as to obtain an intermediate BPN-2a; (3) Carrying out hydrolysis reaction on the BPN-2a in an alkaline alcohol-water system to generate a tetracarboxylic acid intermediate, and then carrying out dehydration cyclization reaction on acetic anhydride to obtain dianhydride monomer BPA-2a; S2, preparing polyimide PI-6B: Adding the dianhydride monomer BPA-2a and the aromatic diamine monomer into an organic solvent (m-cresol), carrying out polycondensation reaction in the presence of a catalyst (quinoline; anhydrous toluene) and under the protection of inert gas, and separating out a polymer after high-temperature imidization reaction to obtain polyimide PI-6B containing a hexabenzyl structural unit; S3, bromomethylation modification: Under the protection of inert gas, dissolving the PI-6B in an aromatic organic solvent (chlorobenzene)