Preparation method and application of brominated polyphenylene ether mixed matrix membrane containing imine organic cage RCC3

Abstract

The present invention discloses a preparation method and application of a brominated polyphenylene ether mixed matrix membrane containing an imine-based organic cage RCC3, the preparation method comprising the following steps: weighing BPPO, dissolving it in a solvent, then adding 4-pyridine propanol and RCC3 shown in formula (I), mixing and reacting at room temperature for 12 to 36 hours to obtain a casting solution; then casting the casting solution on a clean glass plate, and vacuum drying it at 60 to 100 ° C for 12 to 36 hours to obtain a BPPO-Py-RCC3 membrane. The present invention provides the application of the brominated polyphenylene ether mixed matrix membrane containing imine-based organic cage RCC3 as an anion exchange membrane in electrodialysis separation of monovalent anions. The mixed matrix membrane prepared by the present invention enhances ion separation performance and dimensional stability, has a low swelling rate and an ion transmission window of suitable size in water and organic solvents, and has a good application effect in electrodialysis separation of monovalent anions.

Description

Technical Field

[0001] The present invention relates to the fields of high molecular polymer materials and porous materials, and in particular to a preparation method and application of a brominated polyphenylene ether mixed matrix membrane containing an imine-based organic cage RCC3. Background Art

[0002] In the industrial fields involving resource recovery, seawater desalination and wastewater treatment, there is a need for efficient separation of ions (such as Cl - / SO4 2- ) situation. Membrane separation technology has the advantages of low energy consumption and simple operating equipment, and is considered to be one of the separation technologies with the most development potential. Organic solvent-resistant ion-selective membranes directly separate valuable ions and minimize wastewater discharge into the environment, which helps reduce chemical pollution and energy consumption. Some traditional separation membranes will degrade, shed functional groups or swell in organic salt solutions, which is not conducive to ion separation. Therefore, the development of ion-selective membranes with excellent organic solvent resistance is an urgent problem to be solved.

[0003] The new porous material has the characteristics of clear pore structure, permanent pores and uniform pore size, which can better meet the requirements of ion selective separation. Porous organic cages (POCs) are assembled through van der Waals interactions between isolated molecules with fixed cavities. They have rich porosity and sub-nanometer-sized windows, showing unique structural flexibility and excellent solvent processability. RCC3 is one of the most studied POCs. It is an amine cage compound with good stability and unique tetrahedral symmetry. The effective diameter of the window is about The size is suitable for ion separation. However, the ordered arrangement and assembly of POCs on membranes remains challenging. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a brominated polyphenylene ether mixed matrix membrane containing an imine organic cage RCC3.

[0005] To solve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a brominated polyphenylene ether mixed matrix membrane containing an imine-based organic cage RCC3, comprising the following steps:

[0007] BPPO is weighed and dissolved in a solvent, and then 4-pyridine propanol and RCC3 represented by formula (I) are added, mixed, and reacted at room temperature for 12 to 36 hours to obtain a casting solution. The casting solution is then cast on a clean glass plate and vacuum-dried at 60 to 100° C. for 12 to 36 hours to obtain a BPPO-Py-RCC3 film, wherein the mass of RCC3 accounts for 7.5 to 30% of the total mass of BPPO, 4-pyridine propanol, and RCC3.

[0008]

[0009] The preparation method of the organic cage RCC3 described in the present invention refers to the document [Adv.Funct.Mater.2024,2314469].

[0010] Preferably, the solvent is N-methylpyrrolidone (NMP).

[0011] Preferably, the mass ratio of BPPO to 4-pyridinepropanol is 4-6:1, preferably 5:1.

[0012] Preferably, the reaction time is 24 h.

[0013] Preferably, the vacuum drying temperature is 80° C. and the drying time is 12 h.

[0014] In a second aspect, the present invention provides a brominated polyphenylene ether mixed matrix membrane containing an imine organic cage RCC3 obtained according to the preparation method of the first aspect.

[0015] In a third aspect, the present invention provides the use of the brominated polyphenylene ether mixed matrix membrane containing the imine organic cage RCC3 described in the second aspect as an anion exchange membrane in the electrodialysis separation of monovalent and polyvalent anions.

[0016] Preferably, the monovalent anion is Cl- and the polyvalent anion is SO4 2- .

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention prepares a brominated polyphenylene ether mixed matrix membrane containing imine-based organic cages (RCC3). The prepared mixed matrix membrane has subnanostructured windows. Furthermore, the RCC3 grafted onto the brominated polyphenylene ether via chemical crosslinking enhances chemical stability, resulting in enhanced ion separation performance and dimensional stability. The optimized mixed matrix membrane exhibits low swelling rates and appropriately sized ion transmission windows in both water and organic solvents. This results in the membrane possessing suitable ion channels, reducing ion transmission resistance, and promoting electrodialysis performance. The membrane demonstrates excellent application in electrodialysis separation of monovalent and polyvalent anions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 They are SEM images of CC3 and RCC3 prepared in Example 1 of the present invention, respectively, wherein ab is the SEM image of CC3 dispersed in NMP, and cd is the SEM image of RCC3 dispersed in NMP.

[0020] Figure 2 They are the surface and cross-sectional SEM images of the mixed matrix membranes prepared in Examples 1-5 of the present invention, a, b, c, d are the SEM surface images of BPPO-Py-CC3-7.5, BPPO-Py-RCC3-7.5, BPPO-Py-RCC3-15 and BPPO-Py-RCC3-30, respectively; e, f, g, h are the SEM cross-sectional images of BPPO-Py-CC3-7.5, BPPO-Py-RCC3-7.5, BPPO-Py-RCC3-15 and BPPO-Py-RCC3-30, respectively.

[0021] Figure 3 This is a physical picture of the BPPO-Py-RCC3-15 film prepared in Example 3 of the present invention, which shows the overall appearance of the film, with uniform color and smooth surface.

[0022] Figure 4 CC3 and RCC3 prepared in Example 1 of the present invention 1 H NMR images.

[0023] Figure 5 This is a graph of the membrane surface resistance of the anion exchange membrane prepared in Examples 1-5 of the present invention before and after immersion in 60% ethanol, 60% DMSO and 60% DMAc solutions for 2 days; the graph shows the stability of the membrane in 60% ethanol, 60% DMSO and 60% DMAc solutions. After immersion, the resistance increases slightly but the overall change is not significant, indicating that the membrane has good resistance to organic solvents.

[0024] Figure 6 The liquid absorption rate and swelling rate of the membranes prepared in Examples 1-5 of the present invention in water, 60% ethanol, 60% DMSO and 60% DMAc solutions; compared with BPPO-Py, the BPPO-Py-RCC3 membrane shows lower water content and swelling rate in organic solvents, which is mainly attributed to its cross-linked structure reducing its water content and swelling rate.

[0025] Figure 7 This is embodiment 2 of the present invention ( Figure 7 a) and 5( Figure 7 b) Cl of the prepared membrane - / SO4 2- Selectivity; The results show that BPPO-Py-RCC3 membrane has high selectivity for Cl ions. Figure 7 It shows that with the increase of RCC3 content, the Cl - / SO4 2- The selectivity was significantly improved, highlighting the key role of RCC3 in optimizing the membrane's ion separation performance.

[0026] Figure 8 Schematic diagram of the electrodialysis device used in Example 7 of the present invention. DETAILED DESCRIPTION

[0027] To further illustrate the technical solution of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0028] Example 1:

[0029] Preparation of organic cage CC3: Weigh 1g of 1,3,5-trimethylbenzene into a round-bottom flask, slowly add 20mL of dichloromethane dropwise, and then add the catalyst, 40μL of trifluoroacetic acid, to obtain solution ①. Weigh 1g of (1R,2R)-1,2-cyclohexanediamine and dissolve it in 20mL of dichloromethane to obtain solution ②. Then, add solution ② dropwise to solution ① and let it stand at room temperature for 4 days. The crude product CC3 is collected by rotary evaporation and then centrifuged and washed with 95% ethanol / 5% dichloromethane (v / v). CC3 is obtained as a white powder.

[0030] Preparation of the imine-containing organic cage RCC3: Disperse 1 g of CC3 in a mixture of dichloromethane and methanol (v:v = 1:1). Once the solution becomes clear, add 0.5 g of sodium borohydride as a reducing agent. The mixture reacts at room temperature for 15 hours. Then, add 1 mL of water and stir at room temperature for 9 hours. After the reaction, remove the solvent by rotary evaporation, wash with deionized water to remove impurities, and extract with two 15 mL portions of dichloromethane. The organic phase is collected and dried under vacuum to yield RCC3 as a white solid powder.

[0031] Characterization of organic cages: SEM images of prepared CC3 and RCC3, 1 H NMR, the results are shown in the attached figure.

[0032] Preparation of BPPO-Py membrane: 1 g of BPPO and 0.2 g of 4-pyridine propanol were dissolved in 30 mL of NMP. The mixture was stirred at room temperature for 24 h, poured onto a clean glass plate, and dried under vacuum at 80°C for 24 h. (BPPO, benzyl substitution degree 0.55, was obtained from Shandong Tianwei Co., Ltd.)

[0033] BPPO-Py membrane performance: Parameters such as the ion exchange capacity, surface resistance, water absorption and swelling rate, SEM images, and monovalent selectivity of the prepared membrane are shown in the accompanying figures. The prepared anion exchange membrane was used primarily for comparative testing. (Test method reference: Small 2024, 20, 2306313).

[0034] Example 2:

[0035] The preparation process of CC3 and RCC3 is the same as that in Example 1.

[0036] Preparation of BPPO-Py-CC3-0.075 membrane: Weigh 1 g of BPPO and 0.2 g of 4-pyridine propanol and dissolve them in 15 mL of NMP solvent to obtain a BPPO-Py solution; pour 7.5 wt% (CC3 / (BPPO+Py+CC3)) of CC3 into 15 mL of NMP and ultrasonically disperse it for 30 minutes, then add it to the BPPO-Py solution, stir at room temperature for 24 hours, pour the casting liquid onto a clean glass plate, and vacuum dry it at 80°C for 24 hours.

[0037] The BPPO-Py-CC3-7.5 membrane performance parameters, including ion exchange capacity, membrane surface resistance, water absorption and swelling rate, SEM images, and monovalent selectivity, are shown in the attached figure. The prepared composite matrix membrane was primarily used for comparative testing.

[0038] Example 3:

[0039] The preparation process of CC3 and RCC3 is the same as that in Example 1.

[0040] Preparation of BPPO-Py-RCC3-0.075 membrane: Weigh 1 g of BPPO and 0.2 g of 4-pyridine propanol and dissolve them in 15 mL of NMP solvent to obtain a BPPO-Py solution; pour 7.5 wt% (RCC3 / (BPPO+Py+RCC3)) of RCC3 into 15 mL of NMP and ultrasonically disperse it for 30 minutes, then add it to the BPPO-Py solution, stir at room temperature for 24 hours, pour the casting liquid onto a clean glass plate, and vacuum dry it at 80°C for 24 hours.

[0041] The performance of BPPO-Py-RCC3-7.5 membrane: ion exchange capacity, membrane surface resistance, water absorption and swelling rate, SEM image and unit price selectivity are shown in the attached figure.

[0042] Example 4:

[0043] The preparation process of CC3 and RCC3 is the same as that in Example 1.

[0044] Preparation of BPPO-Py-RCC3-0.15 membrane: Weigh 1 g of BPPO and 0.2 g of 4-pyridine propanol and dissolve them in 15 mL of NMP solvent to obtain a BPPO-Py solution; pour RCC3 with a mass ratio of 15 wt% (RCC3 / (BPPO+Py+RCC3)) into 15 mL of NMP and ultrasonically disperse it for 30 minutes, then add it to the BPPO-Py solution, stir at room temperature for 24 hours, pour the casting liquid onto a clean glass plate, and vacuum dry it at 80°C for 24 hours.

[0045] The performance test of BPPO-Py-RCC3-15 membrane is the same as that in Example 2.

[0046] Example 5:

[0047] The preparation process of CC3 and RCC3 is the same as that in Example 1.

[0048] Preparation of BPPO-Py-RCC3-0.3 membrane: Weigh 1 g of BPPO and 0.2 g of 4-pyridine propanol and dissolve them in 15 mL of NMP solvent to obtain a BPPO-Py solution; pour RCC3 with a mass ratio of 30 wt% (RCC3 / (BPPO+Py+RCC3)) into 15 mL of NMP and ultrasonically disperse it for 30 minutes, then add it to the BPPO-Py solution, stir at room temperature for 24 hours, pour the casting liquid onto a clean glass plate, and vacuum dry it at 80°C for 24 hours.

[0049] The performance test of BPPO-Py-RCC3-30 membrane is the same as that in Example 2.

[0050] Example 6:

[0051] The membranes prepared in Examples 1-5 were tested for organic solvent resistance, and the results are shown in the accompanying figures. The membranes were first cut into 3 cm × 3 cm pieces and then immersed in a solution of 60% (v / v) ethanol, 60% (v / v) DMAc, and 60% (v / v) DMSO for 90 days. Before- and after-images were taken to observe morphological changes. The membranes were then cut into 1 cm × 4 cm pieces and oven-dried for 24 hours. The weight and dimensions were measured and recorded. The membranes were then immersed in ethanol, DMAc, and DMSO for 24 hours, and the weight and dimensions were again measured and recorded. The liquid absorption and swelling ratios were calculated according to the formula to evaluate dimensional stability in organic solvents. The membranes were then cut into 2 cm × 2 cm pieces and immersed in a solution of 60% ethanol, 60% DMAc, and 60% DMSO for 2 days. The surface resistance of the membranes was then measured, and the organic solvent resistance of the membranes was evaluated by comparing the before- and after-images.

[0052] Example 7:

[0053] exist Figure 8In the ED device shown, the anion exchange membrane is the membrane prepared in Example 1-5, and the cation exchange membrane is FUJI-CEM, purchased from Fuji Corporation, Japan. -2 Under the current density of , by measuring Cl - and SO4 2- The ion selectivity was evaluated by measuring the concentration changes of ions. The two middle compartments were filled with 80 mL of a mixed solution of 0.05 M NaCl and 0.05 M Na2SO4, and 0.3 M Na2SO4 was pumped into the electrode compartment. The Cl in DC at different time intervals was measured by anion chromatography (Thermo Scientific ICS-5000+). - and SO4 2- ion concentration. Calculate Cl according to the formula - / SO4 2- Selective.

Claims

1. A method for preparing a brominated polyphenylene ether mixed matrix membrane containing imine-based organic cages RCC3, characterized by: The preparation method comprises the following steps: BPPO is weighed and dissolved in a solvent. 4-Pyridinepropanol and RCC3 represented by formula (I) are then added. The mixture is reacted at room temperature for 12 to 36 hours to obtain a casting solution. The casting solution is then cast onto a clean glass plate and vacuum-dried at 60 to 100°C for 12 to 36 hours to obtain a BPPO-Py-RCC3 film, in which the mass of RCC3 accounts for 7.5-30% of the total mass of BPPO, 4-Pyridinepropanol, and RCC3.

2. The preparation method according to claim 1, wherein: The solvent is N-methylpyrrolidone.

3. The preparation method according to claim 1, wherein: The mass ratio of BPPO to 4-pyridinepropanol is 4-6:

1.

4. The preparation method according to claim 3, wherein: The mass ratio of BPPO to 4-pyridinepropanol is 5:

1.

5. The preparation method according to claim 1, wherein: The reaction time is 24 h.

6. The preparation method according to claim 1, wherein: The vacuum drying temperature was 80 °C and the drying time was 12 h.

7. A brominated polyphenylene ether mixed matrix membrane containing imine organic cage RCC3 prepared according to the preparation method according to any one of claims 1 to 6.

8. Use of the brominated polyphenylene ether mixed matrix membrane containing imine organic cage RCC3 as claimed in claim 7 as an anion exchange membrane in electrodialysis separation of monovalent and polyvalent anions.

9. The use according to claim 8, characterized in that: The monovalent anion is Cl - , the polyvalent anion is SO4 2- .

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