A magnetically functionalized two-dimensional material orientation-doped hybrid matrix film and its preparation method

Abstract

This invention discloses a magnetically functionalized two-dimensional material orientation-doped hybrid matrix film and its preparation method. The method involves doping a hexagonal boron nitride (h-BN) material loaded with iron(III) oxide (Fe3O4) and polyethyleneimine (PEI) into a polyether block polyamide (Pebax-1657) under a magnetic field environment, thereby preparing a hybrid matrix film with controllable two-dimensional material doping orientation. This invention utilizes amino-rich PEI loaded onto h-BN to facilitate the dissolution and diffusion of CO2 within the film, while simultaneously loading Fe3O4 onto h-BN, thereby achieving the control of the doping orientation of the two-dimensional material using a magnetic field, thus improving the gas separation performance of the hybrid matrix film.

Description

Technical Field

[0001] This invention discloses a magnetically functionalized two-dimensional material orientation-doped hybrid matrix film and its preparation method, belonging to the field of film preparation and application technology. Background Technology

[0002] With the continuous advancement of science and technology and industry, the greenhouse effect caused by excessive CO2 emissions has become a global environmental problem. Therefore, the importance of CO2 capture technology is self-evident. Membrane separation technology has advantages such as low energy consumption, high separation efficiency, low cost, and ease of coupling and scale-up. Therefore, the development of CO2 separation membranes with high permeability and high selectivity is crucial.

[0003] Gas separation membranes mainly fall into two categories: polymer membranes and inorganic membranes. Traditional polymer membranes exhibit good film-forming performance but suffer from a trade-off between permeation flux and selectivity. Inorganic membranes offer higher permeation flux and selectivity but suffer from lower film-forming success rates and higher preparation costs. Therefore, hybrid matrix membranes, which combine inorganic nanomaterials with traditional polymer membranes, can combine the advantages of both and overcome the trade-off effect of polymer membranes.

[0004] This invention prepares an amino-functionalized magnetic two-dimensional material. Amino functionalization by loading PEI improves the interfacial compatibility of h-BN and simultaneously facilitates the dissolution and diffusion of CO2 within the membrane. By loading magnetic material Fe3O4 onto h-BN, the doping orientation of the two-dimensional material can be controlled by a magnetic field. This material is then incorporated into Pebax membranes, and mixed matrix membranes with different orientations are prepared using magnetic fields in different directions, thereby obtaining mixed matrix membranes with varying separation performance. Summary of the Invention

[0005] To address the trade-off effect of permeability and selectivity in existing Pebax membranes, this invention proposes a method for preparing hybrid matrix membranes with magnetically modulated doping orientation of magnetically functionalized two-dimensional materials.

[0006] To achieve the above objectives, this invention prepares a hybrid matrix membrane with magnetically functionalized two-dimensional material orientation doping. The magnetism of the two-dimensional material is achieved by loading Fe3O4, and the amino functionalization is achieved by loading PEI. The adsorption of CO2 by the amino groups on the surface-functionalized PEI can enhance its permeation flux. By controlling the orientation of the magnetic two-dimensional material in a magnetic field, horizontal doping of the two-dimensional material can effectively reduce the permeation flux of N2, thereby improving the CO2 / N2 selectivity. The adsorption of CO2 by the amino groups of PEI loaded on the vertically doped two-dimensional material can maximize the dissolution and diffusion of CO2 within the membrane, thereby further improving the CO2 permeation performance of the hybrid matrix membrane.

[0007] The technical solution of this invention:

[0008] A method for preparing a magnetically functionalized two-dimensional material orientation-doped hybrid matrix film includes the following steps:

[0009] (1) Preparation of magnetic two-dimensional materials: Hexagonal boron nitride (h-BN) and ferrous sulfate heptahydrate (FeSO4·7H2O) were dispersed in water. After mechanical stirring, ammonia was added to create an alkaline environment for the reaction. After the reaction was completed, the mixture was washed with water and the solid and liquid were separated. The separated solid was dried to obtain the Fe3O4-loaded magnetic h-BN material, i.e., the magnetic two-dimensional material.

[0010] (2) Preparation of magnetically functionalized two-dimensional materials: The Fe3O4-loaded magnetic h-BN material obtained in step (1) was dispersed with polyethyleneimine (PEI) in anhydrous methanol solvent. After mechanical stirring, solid-liquid separation was performed. The separated solid was dried to obtain the amino-magnetically functionalized h-BN material loaded with PEI and Fe3O4, i.e., the magnetically functionalized two-dimensional material.

[0011] (3) Preparation of oriented doped mixed matrix film of magnetically functionalized two-dimensional material: Pebax was dissolved in a mixture of ethanol and water, and a uniform Pebax casting solution was obtained after heating and reflux. The magnetically functionalized two-dimensional material obtained in step (2) was added to the Pebax casting solution, stirred, and then ultrasonically treated to remove microbubbles in the casting solution, while ensuring uniform dispersion of the magnetically functionalized two-dimensional material. The casting solution was poured into an ultra-flat glass plate and placed in an oven to remove some of the solvent. The glass plate containing the casting solution was then placed in a uniform magnetic field generated by two opposing magnets, and oriented under natural conditions for a period of time, while the solvent evaporated and was removed.

[0012] The mixed matrix membrane can be obtained in either a horizontally or vertically oriented manner as required. When a horizontally oriented mixed matrix membrane is required, the magnet for the horizontally oriented mixed matrix membrane is placed perpendicular to the direction of the casting liquid glass plate. When a vertically oriented mixed matrix membrane is required, the magnet for the vertically oriented mixed matrix membrane is placed in the same direction as the casting liquid glass plate.

[0013] Furthermore, in step (1), the mass ratio of hexagonal boron nitride h-BN to ferrous sulfate heptahydrate FeSO4·7H2O is 1:7-1:3.

[0014] Furthermore, in step (1), ammonia water needs to be added in small amounts multiple times until the pH is 10-12.

[0015] Furthermore, in step (1), the entire dispersion system is placed in an oil bath and reacted at 60-90℃ for 3-6 hours.

[0016] Furthermore, in steps (1) and (2), the solid-liquid separation is preferably performed using a vacuum filter.

[0017] Furthermore, in step (2), the mass ratio of the Fe3O4-loaded magnetic h-BN material to polyethyleneimine (PEI) is 1:3 to 3:1.

[0018] Furthermore, in step (2), the magnetic two-dimensional material and PEI are mixed and stirred in anhydrous methanol for 12-36 hours.

[0019] Furthermore, in step (3), Pebax needs to be kept at a mass concentration of 3-10% in the casting solution.

[0020] Furthermore, in step (3), the temperature of the reflux heating is 70-90℃, and the reflux heating time is 3-5h.

[0021] Furthermore, in step (3), the amount of magnetically functionalized two-dimensional material added is 1-30% of the total mass of the casting solution.

[0022] Furthermore, in step (3), the ultrasonic dispersion time is 0.5-3h to ensure uniform dispersion.

[0023] Furthermore, in step (3), the casting solution needs to be dried in an oven at 30-60℃ for 0.5-3 hours to evaporate some of the solvent.

[0024] Furthermore, in step (3), a circular magnet with a strength of 0.4-0.8T should be selected and placed on the left or right vertical side or the top or bottom side of the casting liquid for orientation.

[0025] Furthermore, in step (3), the solvent continues to evaporate in the fume hood for about 24-72 hours until a film is formed.

[0026] Compared with existing technologies, the advantages of this invention are that it prepares amino-functionalized and Fe3O4-supported magnetically functionalized two-dimensional nanomaterials and incorporates them into commercially available Pebax membranes via magnetic field orientation. The amino functionalization provided by PEI offers higher solubility of CO2 in the rubbery polymer membrane, enhancing CO2 permeation performance in the Pebax membrane. The magnetism of Fe3O4 allows for magnetic field manipulation of the orientation of the two-dimensional material within the membrane. Horizontally doped two-dimensional materials effectively reduce N2 permeation flux, thereby improving CO2 / N2 selectivity. The adsorption of CO2 by the amino groups of PEI supported on the surface of the vertically doped two-dimensional material maximizes CO2 diffusion within the membrane, further enhancing the CO2 permeation performance of the mixed matrix membrane. Attached Figure Description

[0027] Figure 1The hysteresis loop is the magnetic functionalized two-dimensional material mf-BN in Example 1.

[0028] Figure 2 The Fourier transform infrared curves of different materials in Example 1 are shown.

[0029] Figure 3 This is a cross-sectional scanning electron microscope image of the horizontally oriented doped mixed matrix film of the magnetically functionalized two-dimensional material in Example 1.

[0030] Figure 4 This is a cross-sectional scanning electron microscope image of the vertically oriented doped mixed matrix film of the magnetically functionalized two-dimensional material in Example 2.

[0031] Figure 5 The graph shows a comparison of the gas separation performance of different membranes in Examples 1-4. Detailed Implementation

[0032] The present invention will be further described below with reference to specific examples.

[0033] Example 1:

[0034] Preparation of magnetic two-dimensional materials: 0.2 g of h-BN powder was added to a 100 mL reagent bottle at room temperature. 80 mL of deionized water was added to the bottle as a reaction solvent, and the mixture was mechanically stirred for 40 minutes for dispersion. After uniform dispersion, 1.39 g of FeSO4·7H2O powder was slowly added to the h-BN suspension. After mechanical stirring for 15 minutes, the mixture was sonicated for 40 minutes to form a uniform suspension. Ammonia water was added dropwise to the suspension in small amounts until the pH value of the suspension was approximately 11 as measured by pH paper. The oil bath temperature was adjusted to 90℃, and the dispersion was placed in it and reacted with stirring for 6 hours. After the reaction was completed, the solid and liquid phases were separated using a vacuum filtration flask. The solid phase was washed 6 times with deionized water and then dried in a 60℃ forced-air oven for 24 hours to obtain the Fe3O4-loaded magnetic h-BN two-dimensional material, which was named m-BN.

[0035] Preparation of magnetically functionalized two-dimensional materials: 1 g of m-BN prepared in (1) was poured into a 200 mL flask at room temperature, and 100 mL of anhydrous methanol was added to the flask as a reaction solvent. 1.5 mL of PEI with a molecular weight of 800 was added to the reaction system. The mechanical stirrer was turned on and set to a speed of 400 r / min, and stirred for 24 h. After the reaction was completed, the solid and liquid phases were separated by vacuum filtration. The separated solid phase was placed in a 60 °C forced-air oven and dried for 24 h to obtain the PEI-loaded magnetic h-BN two-dimensional material. It was named mf-BN.

[0036] To prepare a horizontally oriented doped hybrid matrix film of magnetically functionalized two-dimensional materials, 0.90 g of Pebax was weighed and added to a 100 mL flask. 8.73 mL of water and 25.80 mL of anhydrous ethanol were added to the flask. The oil bath temperature was set to 80 °C, and the flask was heated under reflux for 4 hours until a homogeneous Pebax casting solution was formed. After the solution cooled, 20% of the mass of mf-BN was weighed and added to the casting solution. The mixture was stirred for 2 hours and then sonicated for 3 hours to completely remove micro-bubbles and ensure complete dispersion of mf-BN. The temperature of the forced-air drying oven was set to 40 °C, and the casting solution was poured into an ultra-flat glass plate and dried for 2 hours to remove some of the solvent. The dispersion system was then removed and placed in an approximately uniform magnetic field provided by two circular magnets with a magnetic field strength of 0.6 T. By adjusting the position of the magnets to be perpendicular to the direction of the casting solution glass plate, the film was oriented in a fume hood for 24 hours. A horizontally oriented hybrid matrix film, denoted as mf-BN-H, was obtained.

[0037] Example 2:

[0038] The main steps are the same as in Example 1. In the preparation of the magnetic two-dimensional material, the amount of FeSO4·7H2O powder added is changed to 0.6g. Additionally, a vertically oriented hybrid matrix film of the magnetic functionalized two-dimensional material is prepared. The difference lies in that the position of the magnet is adjusted to be in the same direction as the glass plate of the casting solution, and the orientation is carried out in a fume hood for 24 hours. The vertically oriented hybrid matrix film is obtained and denoted as mf-BN-V.

[0039] Example 3:

[0040] The main steps are the same as in Example 1. An unoriented mixed matrix membrane was prepared, the difference being that a casting solution with a mass concentration of 20% after ultrasonication was taken and dried in a 40°C forced-air oven for 24 hours until the solvent was completely removed. An unoriented mixed matrix membrane was then obtained.

[0041] Example 4:

[0042] The main steps are the same as in Example 1. In addition, a pure Pebax membrane was prepared, the difference being that the casting solution was not doped with mf-BN, and the ultrasonicated casting solution was directly dried in a 40℃ forced-air oven for 24 hours until the solvent was completely removed. A pure Pebax membrane was obtained.

[0043] Gas permeation tests showed that the hybrid matrix membrane based on magnetically functionalized two-dimensional material mf-BN doped in this example, under the test conditions of 20 wt% doping, 25 °C, and 2 bar, achieved a CO2 permeation flux of 113.02 Barrer and a CO2 / N2 selectivity of 74.21. The hybrid matrix membrane with horizontal doping of magnetically functionalized two-dimensional material mf-BN achieved a CO2 permeation flux of 114.70 Barrer and a CO2 / N2 selectivity of 83.88. The hybrid matrix membrane with horizontal doping of magnetically functionalized two-dimensional material mf-BN achieved a CO2 permeation flux of 139.80 Barrer and a CO2 / N2 selectivity of 76.81.

Claims

1. A method for preparing a magnetic functionalized two-dimensional material oriented doped mixed matrix membrane, characterized in that, Comprising the following steps: Step (1) preparation of magnetic two-dimensional material: hexagonal boron nitride h-BN and ferrous sulfate heptahydrate FeSO4·7H2O are dispersed in water; after mechanical stirring, ammonia water is added to create an alkaline environment for reaction; after the reaction is completed, washing with water and solid-liquid separation are performed; the separated solid is dried to obtain Fe3O4-loaded magnetic h-BN material, i.e. magnetic two-dimensional material; Step (2) preparation of magnetic functionalized two-dimensional material: the Fe3O4-loaded magnetic h-BN material obtained in step (1) is dispersed with polyethyleneimine PEI in anhydrous methanol solvent, and after mechanical stirring, solid-liquid separation is performed; the separated solid is dried to obtain PEI and Fe3O4-loaded amino magnetic functionalized h-BN material, i.e. magnetic functionalized two-dimensional material; Step (3) preparation of magnetic functionalized two-dimensional material oriented doped mixed matrix membrane: Pebax is dissolved in a mixture of ethanol and water, and after heating and refluxing, a uniform Pebax casting solution is obtained; the magnetic functionalized two-dimensional material obtained in step (2) is added to the Pebax casting solution, stirred and then ultrasonically treated to remove microbubbles in the casting solution and ensure uniform dispersion of the magnetic functionalized two-dimensional material; the casting solution is poured into a super-flat glass plate and placed in an oven to remove part of the solvent; the glass plate containing the casting solution is then placed in a uniform magnetic field generated by two opposite magnets, and oriented for a period of time under natural conditions, while the solvent is volatilized and removed; According to the requirements, a horizontally oriented or vertically oriented mixed matrix membrane is obtained; when a horizontally oriented mixed matrix membrane is required, the horizontally oriented mixed matrix membrane is placed vertically to the direction of the casting solution glass plate; when a vertically oriented mixed matrix membrane is required, the vertically oriented mixed matrix membrane is placed in the same direction as the casting solution glass plate.

2. The method of claim 1, wherein the method is characterized by: In step (1), the mass ratio of hexagonal boron nitride h-BN to ferrous sulfate heptahydrate FeSO4·7H2O is 1:7-1:

3.

3. The method of claim 1, wherein the method is characterized by: In step (1), ammonia water needs to be added in small amounts multiple times until the pH is 10-12; the entire dispersion system is placed in an oil bath and reacted at 60-90℃ for 3-6h; in steps (1) and (2), vacuum filtration is used for solid-liquid separation.

4. The method of claim 1, wherein the method is characterized by: In step (2), the mass ratio of Fe3O4-loaded magnetic h-BN material to polyethyleneimine PEI is 1:3-3:

1.

5. The method of claim 1, wherein the method is characterized by: In step (2), the magnetic two-dimensional material and PEI are mixed and stirred in anhydrous methanol for 12-36h.

6. The method of claim 1, wherein the method is characterized by: In step (3), Pebax needs to have a mass concentration of 3-10% in the casting solution.

7. The method of claim 1, wherein the method is characterized by: In step (3), the amount of magnetic functionalized two-dimensional material added is 1-30% of the total mass of the casting solution.

8. The method of claim 1, wherein the method is characterized by: In step (3), the heating reflux temperature is 70-90℃, and the heating reflux time is 3-5h; the ultrasonic dispersion time is 0.5-3h to ensure uniform dispersion; the casting solution needs to be first dried in an oven at 30-60℃ for 0.5-3h to volatilize part of the solvent.

9. The method of claim 1, wherein the method is characterized by: In the step (3), a circular magnet with a strength of 0.4-0.8T is placed on the vertical side or the same direction side of the casting solution; in the step (3), the solvent is volatilized in the fume hood for 24-72h until the film is formed.

10. A magnetic functional two-dimensional material oriented doped mixed matrix film prepared by the method of any one of claims 1-9.

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