A two-dimensional covalent organic framework material containing hydrophilic groups and hydrophobic groups, and a preparation method and application thereof
By preparing two-dimensional covalent organic framework materials containing hydrophilic and hydrophobic groups, the problem of separating water and heavy water was solved by utilizing the difference in kinetic properties between water and heavy water, achieving a highly efficient separation effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG NORMAL UNIV
- Filing Date
- 2023-10-28
- Publication Date
- 2026-07-24
Smart Images
Figure CN117430769B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of covalent organic framework materials technology, specifically relating to a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups, its preparation method and application, which is particularly suitable for separating water and heavy water. Background Technology
[0002] Covalent organic frameworks (COFs) are a class of porous and crystalline materials, primarily linked by strong covalent bonds. Due to their unique properties, such as ordered and tunable pore structure, permanent porosity, large specific surface area, ability to be post-modified with active groups, and high thermal and chemical stability, these materials have wide applications in various fields including gas adsorption and storage, separation, catalysis, and optoelectronics.
[0003] The separation of water isotopes is among the most difficult isotopes to separate and has received considerable attention in recent years. The physical properties of water isotopes are very similar, and this similarity presents a significant obstacle to separating water and heavy water using traditional distillation and electrolysis methods. The chemical exchange equilibrium of H₂O, HDO, and D₂O at 298 K indicates that these three substances always coexist when water and heavy water are mixed. Therefore, it is difficult to separate water isotopes using methods based on thermodynamic equilibrium. Since the discovery of heavy water in 1931, the effective separation of water and heavy water has been considered a "century-old problem."
[0004] The pore structure and interaction sites of covalent organic framework materials are very attractive for studying isotope separation mechanisms. However, while COFs have great applications in the separation of gaseous isotopes, their application in the separation of water isotopes is still under exploration. Summary of the Invention
[0005] The purpose of this invention is to provide a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups, its preparation method and application. This covalent organic framework material addresses the important challenge of separating water and heavy water by leveraging its high adsorption capacity for water and heavy water and the large difference in their kinetic diffusion coefficients.
[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows.
[0007] The two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups of the present invention has the following structural formula:
[0008] .
[0009] The method for preparing the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups of the present invention includes the following steps:
[0010] Step 1: Place trialdehyde-resorcinol and 1,4-diamino-2,5-difluorobenzene in a reaction vessel and mix thoroughly to obtain the first mixture;
[0011] Step 2: Under an inert atmosphere, add dioxane and mesitylene to the first mixture, mix thoroughly by ultrasonication, then add acetic acid to obtain the second mixture; place the reaction vessel in liquid nitrogen at 77 K for freezing, degas after freezing, then seal the reaction vessel and thaw.
[0012] Step 3: Place the reaction vessel at 120°C. o After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain a dark red powder, which is a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups.
[0013] The ratio of the trialdehyde phloroglucinol: 1,4-diamino-2,5-difluorobenzene: dioxane: mesitylene: acetic acid is 0.3 mmol: 0.45 mmol: 1.5 mL: 1.5 mL: 0.5 mL.
[0014] Preferably, the inert atmosphere is nitrogen.
[0015] Preferably, the ultrasound time is 20 minutes.
[0016] Preferably, the acetic acid concentration is 3 M.
[0017] Preferably, the drying temperature is 120°C. o C, drying time is 3 days.
[0018] Preferably, the filtration is performed by vacuum filtration using a membrane filter with a nylon membrane as the filter membrane.
[0019] Preferably, the washing process involves washing with dioxane, repeated multiple times, until the supernatant is colorless.
[0020] The present invention relates to the application of a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups in the separation of water and heavy water.
[0021] The principle of this invention is as follows: Two-dimensional covalent organic frameworks (COFs) possess a hydrophobic skeleton, an appropriate density of hydrophilic sites, and one-dimensional open channels, significantly reducing the diffusion and desorption energy barriers of water. This invention regulates the adsorption and desorption capacity of water by introducing appropriate hydrophilic and hydrophobic groups, and controls its surface area by rationally adjusting the number of fluorine atoms (with the same number of hydroxyl groups, more fluorine atoms result in a smaller specific surface area). The covalent organic framework material of this invention does not show a significant difference in water vapor adsorption capacity between water and heavy water, but exhibits differences in kinetic performance. These differences can be identified by calculating the diffusion coefficient using a formula, thus enabling the separation of water and heavy water.
[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0023] The covalent organic framework material containing hydrophilic and hydrophobic groups of the present invention has the advantages of large specific surface area, small pore size, good thermal stability, high adsorption capacity for both water and heavy water, and large difference in the kinetic diffusion coefficients of water and heavy water.
[0024] The present invention provides a method for preparing covalent organic framework materials containing hydrophilic and hydrophobic groups, which involves reacting trialdehyde phloroglucinol with 1,4-diamino-2,5-difluorobenzene via a Schiff base and enol tautomerism reaction. The method is simple and easy to operate.
[0025] The two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups of the present invention is applied to the separation of water and heavy water and has a very good separation effect. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is the infrared spectrum of CPOF-2F-3O prepared in Example 1 of this invention;
[0028] Figure 2 This is the X-ray diffraction pattern of CPOF-2F-3O prepared in Example 1 of this invention;
[0029] Figure 3 The images show scanning electron microscope (left) and transmission electron microscope (right) images of CPOF-2F-3O prepared in Example 1 of this invention.
[0030] Figure 4 The images show the N2 adsorption diagram (left) and pore distribution diagram (right) of CPOF-2F-3O prepared in Example 1 of this invention.
[0031] Figure 5 This is the TGA curve of CPOF-2F-3O prepared in Example 1 of this invention in an air atmosphere;
[0032] Figure 6 This is the adsorption diagram (left) of water and heavy water of CPOF-2F-3O prepared in Example 1 of this invention, and the calculated Q. st Curve (right);
[0033] Figure 7 This is a dynamic adsorption diagram of water in CPOF-2F-3O prepared in Example 1 of this invention;
[0034] Figure 8 This is a dynamic adsorption diagram of heavy water in CPOF-2F-3O prepared in Example 1 of this invention;
[0035] Figure 9 The diffusion coefficient of CPOF-2F-3O prepared in Example 1 of this invention is that of water (left) and heavy water (right) at a relative humidity of 40%. Detailed Implementation
[0036] To further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.
[0037] The two-dimensional covalent organic framework material (CPOF-2F-3O) containing hydrophilic and hydrophobic groups of the present invention has the following structural formula:
[0038] .
[0039] The two-dimensional covalent organic framework material (CPOF-2F-3O) containing hydrophilic and hydrophobic groups of the present invention is prepared by using trialdehyde phloroglucinol and 1,4-diamino-2,5-difluorobenzene.
[0040] The synthesis route diagram is as follows:
[0041] .
[0042] The preparation method of the two-dimensional covalent organic framework material (CPOF-2F-3O) containing hydrophilic and hydrophobic groups of the present invention includes the following steps:
[0043] Step 1: Place trialdehyde-resorcinol and 1,4-diamino-2,5-difluorobenzene in a reaction vessel and mix thoroughly to obtain the first mixture;
[0044] Step 2: Under an inert atmosphere, add dioxane and mesitylene to the first mixture, mix thoroughly by ultrasonication, and then add acetic acid (preferably dropwise) to obtain the second mixture; place the reaction vessel in liquid nitrogen at 77 K for freezing, seal the reaction vessel after freezing, then degas and thaw;
[0045] Step 3: Place the reaction vessel at 120°C. o After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain a dark red powder, which is a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups.
[0046] In the above technical solution, the ratio of trialdehyde phloroglucinol: 1,4-diamino-2,5-difluorobenzene: dioxane: mesitylene: acetic acid is 0.3 mmol: 0.45 mmol: 1.5 mL: 1.5 mL: 0.5 mL; preferably, the inert atmosphere is nitrogen, the ultrasonic time is 20 min, the acetic acid concentration is 3 M, and the drying temperature is 120 °C. o C. The drying time is 3 days. The filtration is carried out by vacuum filtration using a membrane filter with a nylon membrane as the filter membrane. The washing is carried out by washing with dioxane, and the process is repeated multiple times until the supernatant is colorless.
[0047] The application of the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups in the separation of water and heavy water is specifically based on the difference in diffusion coefficients between water and heavy water.
[0048] The terminology used in this invention generally has the meanings commonly understood by those skilled in the art, unless otherwise stated.
[0049] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to embodiments.
[0050] In the following embodiments, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, apparatus, instruments, equipment, etc., used in the following embodiments are commercially available.
[0051] Example 1
[0052] Weigh 63 mg (0.3 mmol) of trialdehyde phloroglucinol and 64.9 mg (0.45 mmol) of 1,4-diamino-2,5-difluorobenzene into a glass tube. Connect the tube to a T-connector and purge with inert gas three times, changing the gas every 10 minutes. Add 1.5 mL of dioxane and 1.5 mL of trimethylbenzene to the glass tube using a syringe, sonicate for 20 minutes, and finally add 0.5 mL of 3 M acetic acid dropwise to the glass tube. Freeze the glass tube in liquid nitrogen at 77 K and perform a freeze-degassing-thawing process. Seal the tube while frozen and finally place it at 120 °C. o The reaction was carried out in an oven at C for 3 days. After the reaction was completed, it was cooled to room temperature. The product was then subjected to vacuum filtration using a membrane filter with a nylon membrane as the filter membrane, and washed with dioxane repeatedly until a colorless supernatant was obtained, finally yielding a dark red powder. The dark red powder was then heated at 120°C. o Vacuum drying at C for 12 h yielded the activated product, CPOF-2F-3O, with a yield of 78%.
[0053] The physicochemical properties of CPOF-2F-3O prepared in Example 1 were tested, and the results are as follows.
[0054] Figure 1 This is the infrared spectrum of CPOF-2F-3O, from... Figure 1 It can be seen that at 1580 cm -1 The location corresponds to C=C and 1260 cm. -1 The infrared characteristic absorption peak corresponding to CN indicates that they exist in the form of keteneamine, and CPOF-2F-3O was synthesized.
[0055] Figure 2 This is the X-ray diffraction pattern of CPOF-2F-3O, from... Figure 2 It can be seen that CPOF-2F-3O has high crystallinity.
[0056] Figure 3 These are scanning electron microscope (SEM) images (left) and transmission electron microscope (TEM) images (right) of CPOF-2F-3O, from... Figure 3 The irregular morphology of CPOF-2F-3O can be observed.
[0057] Figure 4 The left image shows the N2 adsorption isotherm and pore distribution curve (right image) of CPOF-2F-3O at 77 K. Figure 4 It can be seen that the specific surface area of CPOF-2F-3O is 1091 m². 2 g -1 The aperture size is 1.8 nm.
[0058] Figure 5This is a thermogravimetric diagram of CPOF-2F-3O in air. Figure 5 It can be seen that weight loss begins at 304 ℃, indicating that COF-301 has high thermal stability.
[0059] Figure 6 The adsorption diagrams (left) of CPOF-2F-3O in water and heavy water at 298 K and 313 K, and the calculated Q. st Curve (right), from Figure 6 It can be seen that both water and heavy water have high adsorption capacity. The Qst calculated by the water vapor adsorption curve is close to the adsorption enthalpy of water, which also indicates that the interaction force between water and the pores is small, and water can pass through the pores quickly. The Qst of water and heavy water differs by 2.5 KJ / mol.
[0060] Figure 7 The tests were conducted using a Dynamic Water Adsorption Spectrometer (DVS), and the adsorption curves of dynamic water were measured at 298 K to evaluate its kinetic performance. Figure 7 It can be seen that the sample adsorbs quickly at a relative humidity of 40%, with an adsorption capacity of 0.3 g / g.
[0061] Figure 8 The tests were conducted using a Dynamic Water Adsorption Spectrometer (DVS), measuring the adsorption curves of dynamic heavy water at 298 K to evaluate its kinetic performance. Figure 8 It can be seen that the adsorption capacity of the sample at a relative humidity of 40% is 0.4 g / g, which is somewhat different from that of water.
[0062] Figure 9 The calculation of the diffusion coefficients of water (left) and heavy water (right) at a relative humidity of 40% was performed using a single humidity test conducted by a Dynamic Water Adsorption Spectrometer (DVS). Figure 9 It can be seen that heavy water is adsorbed faster than water, and the diffusion coefficient of heavy water is also greater than that of water. This difference in diffusion can be used to separate water from heavy water.
[0063] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the embodiments. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups, characterized in that, The structure is as follows: 。 2. The method for preparing the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 1, characterized in that, Includes the following steps: Step 1: Place trialdehyde-resorcinol and 1,4-diamino-2,5-difluorobenzene in a reaction vessel and mix thoroughly to obtain the first mixture; Step 2: Under an inert atmosphere, add dioxane and mesitylene to the first mixture, mix thoroughly by ultrasonication, then add acetic acid to obtain the second mixture; place the reaction vessel in liquid nitrogen at 77 K for freezing, degas after freezing, then seal the reaction vessel and thaw. Step 3: Place the reaction vessel at 120°C. o After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain a dark red powder, which is a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups. The ratio of the trialdehyde phloroglucinol: 1,4-diamino-2,5-difluorobenzene: dioxane: mesitylene: acetic acid is 0.3 mmol: 0.45 mmol: 1.5 mL: 1.5 mL: 0.5 mL.
3. The method for preparing the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 2, characterized in that, The inert atmosphere is nitrogen.
4. The method for preparing the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 2, characterized in that, The ultrasound duration is 20 minutes.
5. The method for preparing a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 2, characterized in that, The acetic acid concentration is 3 M.
6. The method for preparing the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 2, characterized in that, The drying temperature is 120°C. o C, drying time is 3 days.
7. The method for preparing a two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 2, characterized in that, The filtration is performed by vacuum filtration using a membrane filter with a nylon membrane as the filter membrane.
8. The method for preparing the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 2, characterized in that, The washing process involves washing with dioxane, repeated multiple times, until the supernatant is colorless.
9. The application of the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups according to claim 1, or the two-dimensional covalent organic framework material containing hydrophilic and hydrophobic groups prepared by the preparation method according to any one of claims 2-8, in the separation of water and heavy water.