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CN-122006531-A - COF film subjected to crown etherification based on ice crystal template induction and preparation method and application thereof

CN122006531ACN 122006531 ACN122006531 ACN 122006531ACN-122006531-A

Abstract

The application discloses a crown etherification COF film based on ice crystal template induction and a preparation method and application thereof, belonging to the technical field of film separation materials, the crown etherification COF film based on the ice crystal template induction is internally provided with a nano pore canal structure which is formed by directional freezing of the ice crystal template and is continuously and orderly arranged along the film thickness direction, and the crown ether structure is introduced into the nano pore canal. The preparation raw materials of the crown etherification COF film based on the induction of the ice crystal template comprise reaction monomers and aqueous polar solvents, and the nano pore canal structure which is communicated in the film thickness direction and orderly arranged is constructed inside the covalent organic framework film by the directional freezing construction strategy of the ice crystal template, so that a continuous directional ion transmission channel is formed. Compared with the traditional disordered porous membrane, the structure can obviously reduce the bending degree of an ion transmission path, improve the ion transmembrane transmission efficiency and improve the lithium isotope separation effect.

Inventors

  • WANG JIXIAN
  • Bi Wentuan

Assignees

  • 合肥综合性国家科学中心能源研究院(安徽省能源实验室)

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The ice crystal template-induced crown etherification COF film is characterized in that a crown ether structure is introduced into the nano pore canal through directional freezing of the ice crystal template to form the nano pore canal structure which is continuously and orderly arranged along the film thickness direction.
  2. 2. The ice crystal template-induced crown etherification COF film according to claim 1, wherein the ice crystal template-induced crown etherification COF film preparation raw material comprises a reaction monomer and an aqueous polar solvent, the reaction monomer comprises a crown ether functional monomer, an aromatic aldehyde group monomer and an aromatic amino group monomer, and the molar ratio of the crown ether functional monomer to the aromatic aldehyde group monomer to the aromatic amino group monomer is 1 (1.5-7): 3-10.5, wherein the crown ether functional monomer contains amino groups and/or aldehyde groups.
  3. 3. The ice crystal template-induced crown etherification COF film according to claim 2, wherein the aromatic aldehyde group monomer is an aromatic compound having at least two aldehyde group functional groups and the aromatic amino group monomer is an aromatic compound having at least two amino group functional groups.
  4. 4. The ice crystal template-induced crown etherification COF film according to claim 2, wherein the aqueous polar solvent is a composite solvent composed of water and an organic solvent, wherein the volume ratio of the water to the organic solvent is (1-4): (1-4), and the organic solvent is at least one of dimethyl sulfoxide, absolute ethyl alcohol, methanol and acetonitrile.
  5. 5. The ice crystal template-induced crown etherification COF film according to claim 1, wherein the ice crystal template-induced crown etherification COF film is a continuous self-supporting film structure or is supported on a substrate to form a composite film structure.
  6. 6. A method for preparing a ice crystal template-induced crown etherification COF film, which is used for preparing the ice crystal template-induced crown etherification COF film according to any one of claims 1 to 5, comprising the steps of: s1, adding a reaction monomer into an aqueous polar solvent, uniformly stirring to obtain a COF precursor solution, adding a catalyst, stirring at 20-50 ℃ for reaction for 4-24 hours, and performing vacuum defoaming to obtain a gel precursor solution; S2, placing the gel precursor solution on a die or a substrate, transferring the die or the substrate into a cooling device for directional freezing treatment along the vertical direction of the die or the substrate, removing the ice crystal template through freeze drying, and finally performing heat treatment to obtain the crown etherification COF film based on the induction of the ice crystal template.
  7. 7. The preparation method of the ice crystal template-induced crown etherification COF film is characterized in that the mass fraction of the reaction monomer in the COF precursor solution is 0.5-3.0%, and the molar ratio of the catalyst to the aromatic aldehyde group monomer in the reaction monomer is 0.5-8:1.
  8. 8. The preparation method of the ice crystal template-induced crown etherification COF film is characterized in that the directional freezing treatment temperature is-10 ℃ to-80 ℃, the freezing rate is 0.1 ℃ per minute to 10 ℃ per minute, and the temperature gradient is 1 ℃ per cm to 20 ℃ per cm.
  9. 9. The preparation method of the ice crystal template-induced crown etherification COF film is characterized in that the heat treatment temperature is 60-120 ℃ and the heat treatment time is 12-72 h.
  10. 10. Use of a ice crystal template-induced crown etherification COF film according to any one of claims 1 to 5 for lithium isotope separation.

Description

COF film subjected to crown etherification based on ice crystal template induction and preparation method and application thereof Technical Field The invention belongs to the technical field of membrane separation materials, and particularly relates to a crown etherification COF membrane based on ice crystal template induction and a preparation method and application thereof. Background The stable isotopes of lithium mainly comprise 6 Li and 7 Li, and the two isotopes have significant differences in nuclear reaction characteristics, so that the lithium isotopes have important application values in the fields of nuclear energy engineering, nuclear material preparation and related high-end technologies. The 6 Li can be used as an important raw material for tritium proliferation reaction, can be widely applied to a fusion reactor tritium self-sustaining system, and 7 Li is used in the fields of reactor coolant, chemical control systems and related nuclear engineering due to the fact that the absorption cross section of the 7 Li is low. With the continued development of nuclear energy technologies, particularly controlled nuclear fusion technologies, the demand for high abundance lithium isotope materials continues to increase, and the importance of lithium isotope separation technologies is becoming increasingly prominent. However, since the relative mass difference between 6 Li and 7 Li is small, the chemical properties are highly similar, so that the distribution behavior difference in a solution system or a solid-phase system is very limited, and the lithium isotope separation process has high technical difficulty. The existing lithium isotope separation technology mainly comprises an amalgam method, an ion exchange method, a chemical exchange method and an extraction separation method based on coordination molecules such as crown ether and the like. The amalgam method has the problems of poor process safety, low separation coefficient, complex flow and high energy consumption, and the separation method based on crown ether molecules has certain selectivity to lithium ions, but depends on a liquid phase extraction system, has poor repeated use performance and is difficult to realize continuous operation. In recent years, membrane separation technology has been attracting attention because of its advantages such as simplified flow, low energy consumption, and easy implementation of continuous operation. However, most of the existing polymer membranes or inorganic membranes have disordered pore structures, and the ion transmission process in the membranes mainly depends on random diffusion behavior, so that small differences among lithium isotopes are difficult to effectively amplify, and further improvement of separation efficiency is limited. On the other hand, the covalent organic framework material (COF) has the characteristics of strong structural designability, uniform pore size distribution and good crystallinity, and provides a new material basis for constructing an ordered ion transmission channel. However, there is still a lack of a membrane material system capable of stably fixing a lithium ion recognition unit in a membrane structure and simultaneously constructing a nano-pore structure penetrating through the membrane in a membrane thickness direction, thereby limiting the application of the membrane material system in continuous membrane separation of lithium isotopes. Therefore, the separation membrane material which not only has an ordered nano pore structure, but also can introduce a lithium ion selective recognition unit into the pore and form a continuous through mass transfer channel along the film thickness direction is developed, and has important significance for improving the lithium isotope separation efficiency and realizing continuous membrane separation. Disclosure of Invention The invention aims to provide a crown etherification COF membrane based on ice crystal template induction so as to solve the problem of low separation efficiency of the existing membrane material for lithium isotope separation. The second object of the present invention is to provide a method for producing the above-mentioned ice crystal template-induced crown etherification COF film. The third object of the present invention is the use of the above-described ice crystal template-induced crown etherified COF film. In order to achieve the above object, the first aspect of the present invention provides a ice crystal template-induced crown etherification COF film, wherein the ice crystal template-induced crown etherification COF film has a nano-pore structure formed by directional freezing of the ice crystal template, wherein the nano-pore structure is continuously and orderly arranged along the film thickness direction, and the crown ether structure is introduced into the nano-pore. The preparation raw materials of the ice crystal template-based induced crown etherification COF film comprise reaction monomers