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CN-121972034-A - Electrodialysis membrane of chitosan modified MXene as well as preparation method and application thereof

CN121972034ACN 121972034 ACN121972034 ACN 121972034ACN-121972034-A

Abstract

The invention relates to the technical field of membrane separation, in particular to an electrodialysis membrane of chitosan modified MXene, and a preparation method and application thereof. The invention provides a preparation method of an electrodialysis membrane of chitosan modified MXene, which comprises the following steps of mixing MXene nanosheet dispersion liquid and chitosan solution, reacting under the protection of inert gas, centrifugally washing the reacted mixed solution, and performing suction filtration membrane formation and drying treatment on the obtained dispersion liquid. The electrodialysis membrane prepared by the method limits chitosan molecules to MXene nano-sheet layers to form a two-dimensional domain-limited channel structure, and the channel regulates ion migration behaviors through space dimensions and chemical environments, so that divalent magnesium ions are blocked from migrating under the action of a direct current electric field, and monovalent lithium ions can migrate preferentially, so that Li + /Mg 2+ is separated selectively.

Inventors

  • TANG YUANHUI
  • SONG HONGZHI

Assignees

  • 中国矿业大学(北京)

Dates

Publication Date
20260505
Application Date
20260318

Claims (10)

  1. 1. The preparation method of the chitosan modified MXene electrodialysis membrane is characterized by comprising the steps of mixing MXene nanosheet dispersion liquid and chitosan solution, reacting under the protection of inert gas, centrifugally washing the reacted mixed solution, and performing suction filtration and membrane forming on the obtained dispersion liquid and then drying.
  2. 2. The method for preparing the chitosan modified MXene electrodialysis membrane according to claim 1, wherein the mass ratio of the chitosan to the MXene nanosheets is (5-15) 1; and/or the concentration of the MXene nano-sheet dispersion liquid is 0.1-0.5 mg/mL, and the mass fraction of the chitosan solution is 5-20%.
  3. 3. The preparation method of the chitosan modified MXene electrodialysis membrane according to claim 1 or 2, wherein the reaction temperature is 20-25 ℃, the reaction time is 12-36 h, the reaction is performed under magnetic stirring, and the rotating speed of the magnetic stirring is 300-800 r/min; and/or the suction filtration film is carried out on the nylon substrate by a vacuum auxiliary suction filtration method; And/or the temperature of the drying treatment is 60-120 ℃, the drying treatment time is 8-24 hours, and the drying treatment is carried out in a vacuum drying oven.
  4. 4. The method for preparing the chitosan modified MXene electrodialysis membrane according to claim 1, wherein the preparation method of the MXene nanosheet dispersion liquid comprises the steps of mixing deionized water, concentrated hydrochloric acid, liF and MAX, performing constant-temperature reaction, washing a product obtained by the reaction with deionized water, performing first centrifugation treatment to obtain a clay-like precipitate, adding deionized water into the clay-like precipitate, performing ultrasonic stripping under the protection of inert gas, performing second centrifugation treatment to obtain the MXene nanosheet solution, and adding deionized water to prepare the nanosheet dispersion liquid with the required concentration.
  5. 5. The method for preparing the chitosan modified MXene electrodialysis membrane according to claim 4, wherein the dosage ratio of deionized water, concentrated hydrochloric acid, liF and MAX is (20-40) mL (80-120) mL (5-10) g (3-7) g; and/or the temperature of the constant-temperature reaction is 30-70 ℃, and the time of the constant-temperature reaction is 20-40 h; And/or, the rotating speed of the first centrifugal treatment is 3000-4000 r/min, the time of the first centrifugal treatment is 3-5 min, the supernatant is poured off, deionized water is added for washing, and the centrifugal washing is repeated so that the pH value of the supernatant is more than 6; and/or the ultrasonic stripping power is 150-300W, and the ultrasonic stripping time is 30-60 min; And/or the rotating speed of the second centrifugal treatment is 5000-6000 r/min, the time of the second centrifugal treatment is 0.5-2 h, and the concentration of the MXene nano-sheet solution is 10-20 mg/mL.
  6. 6. The method for preparing the chitosan-modified MXene electrodialysis membrane according to claim 1, wherein the method for preparing the chitosan solution is characterized in that chitosan is dissolved in acetic acid water solution and stirred until the chitosan is completely uniform.
  7. 7. An electrodialysis membrane for modifying MXene by chitosan, which is characterized by being prepared by the preparation method according to any one of claims 1-6.
  8. 8. The chitosan modified MXene electrodialysis membrane according to claim 7, wherein the electrodialysis membrane has a thickness of 1-5 μm.
  9. 9. Use of the electrodialysis membrane of chitosan modified MXene according to claim 7 or 8 or the electrodialysis membrane of chitosan modified MXene prepared by the preparation method of any one of claims 1 to 6 for electrodialysis separation of lithium magnesium in neutral or weakly alkaline salt lake brine.
  10. 10. The use according to claim 9, characterized in that the current density in the electrodialysis process is 1-20 mA cm -2 ; And/or in the electrodialysis process, 100~200 mL 0.3~0.5 mol.L -1 Na 2 SO 4 solution is arranged in electrode chambers at two sides, 100-200 mL of salt lake brine simulated liquid is arranged in a raw material chamber, the salt lake brine simulated liquid comprises 0.1 mol.L -1 and 1.0 mol.L -1 MgCl 2 of mixed solution, 100~200 mL 0.1mol.L -1 HCl solution is arranged in a concentration chamber, and the flow rate of the solution in each chamber in a membrane stack is 30-70 mL/min.

Description

Electrodialysis membrane of chitosan modified MXene as well as preparation method and application thereof Technical Field The invention relates to the technical field of membrane separation, in particular to an electrodialysis membrane of chitosan modified MXene, and a preparation method and application thereof. Background Under the large premise that the global energy transformation promotes the explosion of lithium demand and the prominent attribute of lithium resource strategy, the contradiction of supply and demand that the Chinese 'resource endowment is mainly a salt lake but has high external dependence' is superimposed, and the technological breakthrough and policy driving promote the lithium extraction of the salt lake to go from the technological attack to the large-scale industrial application, thereby becoming a core path for guaranteeing the autonomous controllability of lithium resources, reducing the cost, enhancing the efficiency and being green and low-carbon. The prior art for extracting lithium from salt lakes takes a salt pan concentration precipitation method, an adsorption method, a membrane separation method and an extraction method as cores, wherein the membrane separation method has wide application due to the advantages of high separation efficiency, no chemical addition, good environmental protection, automatic controllability and the like. In recent years, two-dimensional material MXene is widely applied to the field of membrane separation due to the unique layered structure and good ion transmission performance. Aiming at the actual demands of electrodialysis separation systems in the process of extracting lithium from salt lakes, the existing membrane materials still have a plurality of technical problems to be solved urgently in application. Firstly, in a neutral or weakly alkaline salt lake brine environment, li + and Mg 2+ coexist and have similar migration characteristics, and the migration of Mg 2+ is difficult to be effectively inhibited by the existing electrodialysis membrane under the action of a direct current electric field, so that the further improvement of the lithium-magnesium separation efficiency is limited. Secondly, salt lake brine generally has high salinity and complex ion composition, and in the electrodialysis operation process, the membrane material needs to be in an environment of combined action of a direct current electric field and high ionic strength for a long time, and the structural stability and the applicability of the existing MXene-based membrane material under the condition still need to be further improved. In addition, the existing preparation methods of the MXene membrane are mostly aimed at meeting the requirements of diffusion dialysis or pressure-driven separation processes, and are not designed systematically according to the matching relation among electric field intensity, ion migration paths and membrane structural parameters in electrodialysis working conditions, so that the separation efficiency and the operation stability are difficult to be considered. CN118371133a discloses a method for positively modifying MXene by Polyethylenimine (PEI) and preparing a composite membrane by vacuum suction filtration, wherein the composite membrane is mainly based on diffusion dialysis principle, and the separation of H + and metal ions in an acidic system is realized. Meanwhile, the structural design and application scene of the membrane are mainly oriented to an acidic separation system, and the problems that Li + and Mg 2+ and other 1-valent and 2-valent cations coexist and have similar migration characteristics in the high-salt and high-magnesium-lithium ratio condition in the neutral or weak alkaline salt lake brine environment are not optimally designed. In addition, the long-term operation stability of the composite membrane under the condition of a direct current electric field is less studied, and the applicability of the composite membrane under the electrodialysis working condition is still to be further explored. Therefore, aiming at the actual requirement of electrodialysis separation of lithium ions and magnesium ions in the process of extracting lithium from salt lakes, development of a novel MXene-based membrane material with a structure and a preparation method which are both suitable for an electrically driven separation process is still needed. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, the embodiment of the invention provides a preparation method of an electrodialysis membrane of chitosan modified MXene. The preparation method of the chitosan modified MXene electrodialysis membrane comprises the following steps: And mixing the MXene nanosheet dispersion liquid and the chitosan solution, reacting under the protection of inert gas, centrifugally washing the reacted mixed solution, and performing suction filtration on th