A high-stability mixed matrix membrane, a preparation method and application thereof

Abstract

The application provides a mixed matrix membrane with high stability, a preparation method and application. The method adopts a phase inversion method, uses prepared UiO-66 and cellulose acetate with excellent chemical stability as raw materials to prepare a support layer membrane, and then synthesizes a polyamide active layer by polymerization of acyl chloride monomers and amine monomers on the support layer membrane, so that the required mixed matrix membrane is obtained. The prepared mixed matrix membrane has high desalination performance and high stability, and has a wide application prospect in the fields of seawater desalination and wastewater purification.

Description

Technical Field

[0001] This invention relates to the field of semipermeable membranes and their preparation technology, specifically to a high-stability mixed matrix membrane, its preparation method, and its application. Background Technology

[0002] One of the major challenges facing the world today is the scarcity of freshwater resources. To address this scarcity, sustainable water management methods are needed, including water reuse and wastewater treatment. Ways to alleviate water shortages include wastewater treatment, reasonable pricing of agricultural products, improved water treatment technologies, and seawater desalination. In fact, seawater desalination has become one of the main methods for addressing freshwater shortages globally. However, seawater contains large amounts of heavy metal ions, which are harmful to human health. These ions can strongly interact with biomolecules such as proteins and enzymes, causing them to lose their function and potentially accumulating in human organs, leading to chronic poisoning. Membrane separation technology is a rapidly developing new separation technology in recent decades. Compared to traditional separation methods, membrane separation technology has advantages such as high efficiency and energy saving, high separation efficiency, and no secondary pollution, thus attracting much attention in the field of water treatment. In the field of seawater treatment, membrane separation technology has become one of the main tools for seawater desalination and desalination.

[0003] Hybrid matrix membranes possess characteristics such as ultra-high specific surface area, ultra-high porosity, and high selectivity, making them highly suitable for the performance requirements of water treatment membranes. However, they are prone to degradation and corrosion when used in seawater. Therefore, how to further improve the stability of hybrid matrix membranes while maintaining high desalination performance has become a current research hotspot. Summary of the Invention

[0004] To address the technical problem of poor stability of mixed matrix membranes, this invention provides a highly stable mixed matrix membrane, its preparation method, and its applications. The method employs a phase inversion approach, using UiO-66 and cellulose acetate, which has excellent chemical stability, as raw materials to prepare a support layer membrane, thereby improving the stability of the mixed matrix membrane. This method has broad application prospects in wastewater purification and seawater desalination.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] A method for preparing a high-stability hybrid matrix membrane, characterized by comprising the following steps:

[0007] S1: Dissolve metal-organic framework powder in organic solvent A, add cellulose acetate, stir to obtain a support layer casting solution; use the support layer casting solution as a coating to form a film, then place it in deionized water for phase inversion, and dry to obtain a support layer film;

[0008] S2: Dissolve the acyl chloride monomer in organic solvent B to obtain a core layer solution; dissolve the amine monomer in deionized water to obtain a shell layer solution;

[0009] S3: The core layer solution and shell layer solution are loaded into a coaxial static spraying device as coatings, and electrostatic spraying technology is used to electrostatically spray the support layer film surface. After drying, a mixed matrix film is obtained.

[0010] Furthermore, the metal-organic framework used in step S1 is UiO-66; the preparation method of the UiO-66 powder includes the following steps:

[0011] S1.1: Dissolve the carboxylic acid organic ligand and zirconium salt separately in organic solvent C, then mix the two solutions and add an inhibitor to obtain a mixed solution of metal-organic framework;

[0012] S1.2: The mixed solution of metal-organic frameworks was subjected to a hydrothermal reaction. After the reaction was completed, the solution was centrifuged and dried to obtain UiO-66 powder.

[0013] Further, in step S1.1, the carboxylic acid organic ligand is one or more of terephthalic acid, amino-terephthalic acid, and fumaric acid; the zirconium salt is zirconium tetrachloride; the molar ratio of the carboxylic acid organic ligand to the zirconium salt is 1:1; the organic solvent C is one or more of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the amount added is 15-30 mL; the inhibitor is acetic acid, and the amount added is 4-8 mL.

[0014] Further, in step S1.2, the parameters of the hydrothermal reaction are: temperature: 100-150℃, reaction time: 12-24h; the parameters of the centrifugation are: rotation speed: 7000-9000r / min, centrifugation time per cycle: 5-8min, number of centrifugations: not less than 2; the drying temperature is 60-90℃, and the drying time is 10-16h.

[0015] Further, in step S1, the organic solvent A is one or more combinations of N,N-dimethylformamide, γ-valerolactone, and N-methylpyrrolidone; the mass fraction of cellulose acetate in the support layer casting solution is 9-18%; and the mass fraction of the metal-organic framework powder in the support layer casting solution is 0.2-0.8%.

[0016] Further, in step S1, a coating machine is used for coating, the advance speed of the coating machine is 5-15 mm / s; the phase transformation time is 12-16 h; the drying condition is natural drying, and the drying time is 3-6 h.

[0017] Further, in step S2, the acyl chloride monomer is one of 1,3,5-benzenetricarboxyl chloride, 5-chloropentanoyl chloride, isophthaloyl chloride, and 2,6-dichloro-5-fluoronicotinamide chloride; the organic solvent B is one or more combinations of n-hexane, methane, propane, and heptane; the mass fraction of the acyl chloride monomer in the core layer solution is 0.1-0.5%; the amine monomer is one of m-phenylenediamine, 1,1-dimethylethylenediamine, 1,2-dimethylethylenediamine, and p-phenylenediamine; the mass fraction of the amine monomer in the shell layer solution is 1-5%.

[0018] Further, in step S3, the coaxial electrostatic spraying device includes a core layer syringe containing a core layer solution, a shell layer syringe containing a shell layer solution, a coaxial needle for connecting the core layer syringe and the shell layer syringe, and a receiving device for fixing the support layer film; the process parameters of the electrostatic spraying are: the advance speed of the core layer syringe: 1-2 mL / h, the advance speed of the shell layer syringe: 1-2 mL / h, the spraying voltage: 12-20 kV, the spraying distance: 10-20 cm, and the spraying time: 10-50 min.

[0019] Highly stable hybrid matrix membranes prepared by any of the above preparation methods.

[0020] The application of the aforementioned high-stability hybrid matrix membrane is characterized by its use in wastewater purification and seawater desalination.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. This invention uses cellulose acetate and UiO-66 to prepare the support layer membrane. The cellulose acetate does not degrade in seawater and is not easily corroded by seawater. It has strong chlorine resistance and stability during use. The UiO-66 nanomaterial synthesized by this invention through hydrothermal reaction is a porous metal nanoframework material with excellent specific surface area, water flux, porosity and mechanical stability. Using both as the support layer filler of the mixed matrix membrane can significantly improve its stability and extend its service life.

[0023] 2. This invention synthesizes a polyamide active layer on a support membrane via an in-situ reaction. On one hand, the support membrane provides stable structural support for the polyamide active layer, enabling it to remain stable under high pressure, thereby improving membrane separation efficiency. On the other hand, the support layer's excellent chlorine resistance and stability prevent damage to the active layer, especially in environments containing chlorine or other oxidants, thus extending membrane lifespan. Furthermore, the high water flux of the support membrane reduces clogging of the active layer, maintaining its high-efficiency performance.

[0024] 3. This invention uses a phase inversion-interfacial polymerization combined method to prepare a hybrid matrix membrane. This method is simple and can control the thickness and pore structure of the polyamide active layer. The prepared hybrid matrix membrane exhibits a thumb-shaped asymmetric structure and has excellent filtration performance. It can be used in a wide range of fields such as environmental protection, drug sustained release, and energy storage.

[0025] 4. The cellulose acetate in this invention is a biomass material, conforming to the principles of green chemistry, possessing renewability and environmental friendliness, and aligning with the national sustainable development strategy. Furthermore, it has low preparation costs and is easy to mass-produce, showing broad application prospects. Attached Figure Description

[0026] Figure 1 This is a SEM image of the UiO-66 particles prepared in Example 1 of the present invention;

[0027] Figure 2 This is a TEM image of the UiO-66 particles prepared in Example 1 of the present invention;

[0028] Figure 3 (A) is a SEM image of the surface of the cellulose acetate support layer membrane prepared in Example 1 of the present invention;

[0029] Figure 3 (B) is a Zr element distribution diagram on the surface of the cellulose acetate support layer membrane prepared in Example 1 of the present invention;

[0030] Figure 4 (A) is a SEM image of the cross-section of the cellulose acetate support layer membrane prepared in Example 1 of the present invention;

[0031] Figure 4 (B) is a Zr element distribution diagram of the cross section of the cellulose acetate support layer membrane prepared in Example 1 of the present invention;

[0032] Figure 5 This is a SEM image of the hybrid matrix membrane prepared in Example 1 of the present invention;

[0033] Figure 6 This is a SEM image of the hybrid matrix membrane prepared in Example 2 of the present invention;

[0034] Figure 7 This is a SEM image of the hybrid matrix membrane prepared in Example 3 of the present invention;

[0035] Figure 8 The image shows the surface AFM pattern of the hybrid matrix membrane prepared in Example 1 of this invention.

[0036] Figure 9 The image shows the surface AFM pattern of the hybrid matrix membrane prepared in Example 2 of this invention.

[0037] Figure 10 This is an AFM image of the surface of the hybrid matrix membrane prepared in Example 3 of the present invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0039] Example 1

[0040] The method for preparing the high desalination performance hybrid matrix membrane described in this embodiment includes the following steps:

[0041] S1: Dissolve 0.233g zirconium tetrachloride in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution A; dissolve 0.166g terephthalic acid in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution B; mix solution A and solution B and add 5mL acetic acid as an inhibitor, stir at room temperature for 1h to obtain a metal-organic framework mixed solution.

[0042] The metal-organic framework mixture was transferred to a 30 mL reactor and subjected to a high-temperature hydrothermal reaction at 120 °C for 16 h. After the reaction, the supernatant was discarded and the mixture was centrifuged. N,N-dimethylformamide was added, and the mixture was centrifuged at 9000 r / min for 6 min. The supernatant was then discarded again, methanol was added, and the mixture was centrifuged at 9000 r / min for 6 min. After the reaction, the resulting milky white precipitate was dried in a 70 °C oven for 12 h. The resulting milky white nanoparticles were identified as UiO-66.

[0043] Figure 1 , Figure 2 The images show SEM and TEM images of the UiO-66 particles prepared in this embodiment. It can be clearly seen from the images that the UiO-66 synthesized by the hydrothermal method exhibits an octahedral rhombic structure. This structure gives it characteristics such as high specific surface area, excellent porosity and stability, and acid resistance. It is one of the best choices as a mixed matrix membrane filler, enabling the mixed matrix membrane to exhibit excellent performance in water treatment, gas separation and other fields.

[0044] S2: Dissolve 0.05g UiO-66 in 8.45g N-methylpyrrolidone, ultrasonically disperse for 30min, add 1.5g cellulose acetate, stir at room temperature for 6h, and let stand for 12h to obtain a homogeneous support layer casting solution.

[0045] The casting solution for the support layer was poured onto the glass plate of the coating machine, and the coating was carried out using a coating rod at a speed of 5 mm / s. After the coating was completed, the glass plate was placed in deionized water for 12 hours to allow for phase inversion precipitation, thereby obtaining the cellulose acetate support layer membrane.

[0046] Figure 3 (A) and (B) are SEM images and Zr element distribution diagrams of the cellulose acetate support layer membrane prepared in this embodiment, respectively. It can be seen from the figures that UiO-66 is uniformly dispersed on the surface of the support layer membrane. Figure 4 (A) and (B) are SEM images and Zr element distribution diagrams of the cross-section of the cellulose acetate support membrane prepared in this embodiment, respectively. It can be seen from the figures that UiO-66 is uniformly dispersed inside the support membrane, and the support membrane exhibits a porous structure. This porous structure ensures high water flux while also having excellent heavy metal ion removal and desalination performance.

[0047] S3: Dissolve 0.02 g of 1,3,5-benzenetricarboxyl chloride in 9.98 g of n-hexane and stir at room temperature for 3 h to obtain the core layer solution. Dissolve 0.2 g of m-phenylenediamine in 9.8 g of deionized water and stir at room temperature for 3 h to obtain the shell layer solution.

[0048] The core layer solution was loaded into the core layer syringe of the coaxial electrostatic spraying device, and the shell layer solution was loaded into the shell layer syringe of the same device. The core layer syringe and shell layer syringe were connected via a coaxial needle. The cellulose acetate support membrane was then fixed onto a roller receiving device. The injection speed was controlled by an automatic supply pump. The spraying voltage was set to 20kV, the injection speed of the core layer syringe was 1.5mL / h, the injection speed of the shell layer syringe was 1mL / h, and the spraying distance was 10cm. Coaxial electrostatic spraying was then performed. After 45 minutes of electrostatic spraying, the membrane was removed from the roller receiving device and allowed to air dry for 2 hours to obtain the mixed matrix membrane.

[0049] The performance of the mixed matrix membrane prepared in Example 1 and the commercially available nanofiltration membrane were tested at 0.1 MPa using aqueous solutions of Na2SO4, MgSO4, MgCl2, CaCl2, and NaCl, respectively. The results are shown in Table 1 below:

[0050] Table 1 Performance test table of the hybrid matrix membrane prepared in Example 1

[0051]

[0052] As can be seen from the table, the hybrid matrix membrane prepared in this embodiment shows varying degrees of improvement in permeation flux and removal rate compared to commercially available nanofiltration membranes, especially with a permeation flux of up to 22.5 L / m³ for Na₂SO₄. 2 The desalination rate is as high as 97.28%.

[0053] Example 2

[0054] The method for preparing the high desalination performance hybrid matrix membrane described in this embodiment includes the following steps:

[0055] S1: Dissolve 0.233g zirconium tetrachloride in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution A; dissolve 0.166g terephthalic acid in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution B; mix solution A and solution B and add 5mL acetic acid as an inhibitor, stir at room temperature for 1h to obtain a metal-organic framework mixed solution.

[0056] The metal-organic framework mixture was transferred to a 30 mL reactor and subjected to a high-temperature hydrothermal reaction at 120 °C for 16 h. After the reaction, the supernatant was discarded and the mixture was centrifuged. N,N-dimethylformamide was added, and the mixture was centrifuged at 9000 r / min for 6 min. The supernatant was then discarded again, methanol was added, and the mixture was centrifuged at 9000 r / min for 6 min. After the reaction, the resulting milky white precipitate was dried in a 70 °C oven for 12 h. The resulting milky white nanoparticles were identified as UiO-66.

[0057] S2: Dissolve 0.05g UiO-66 in 8.45g N-methylpyrrolidone, ultrasonically disperse for 30min, add 1.5g cellulose acetate, stir at room temperature for 6h, and let stand for 12h to obtain a homogeneous support layer casting solution.

[0058] The casting solution for the support layer was poured onto the glass plate of the coating machine, and the coating was carried out using a coating rod at a speed of 5 mm / s. After the coating was completed, the glass plate was placed in deionized water for 12 hours to allow for phase inversion precipitation, thereby obtaining the cellulose acetate support layer membrane.

[0059] S3: Dissolve 0.02 g of 1,3,5-benzenetricarboxyl chloride in 9.98 g of n-hexane and stir at room temperature for 3 h to obtain the core layer solution. Dissolve 0.2 g of m-phenylenediamine in 9.8 g of deionized water and stir at room temperature for 3 h to obtain the shell layer solution.

[0060] The core layer solution was loaded into the core layer syringe of the coaxial electrostatic spraying device, and the shell layer solution was loaded into the shell layer syringe of the same device. The core layer syringe and shell layer syringe were connected via a coaxial needle. The cellulose acetate support membrane was fixed to the roller receiving device. The injection speed was controlled by an automatic supply pump. The spraying voltage was set to 20kV, the injection speed of the core layer syringe was 1.5mL / h, the injection speed of the shell layer syringe was 1mL / h, and the spraying distance was 10cm. Coaxial electrostatic spraying was then performed. After 30 minutes of electrostatic spraying, the membrane was removed from the roller receiving device and allowed to air dry for 2 hours to obtain the mixed matrix membrane.

[0061] Example 3

[0062] The method for preparing the high desalination performance hybrid matrix membrane described in this embodiment includes the following steps:

[0063] S1: Dissolve 0.233g zirconium tetrachloride in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution A; dissolve 0.166g terephthalic acid in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution B; mix solution A and solution B and add 5mL acetic acid as an inhibitor, stir at room temperature for 1h to obtain a metal-organic framework mixed solution.

[0064] The metal-organic framework mixture was transferred to a 30 mL reactor and subjected to a high-temperature hydrothermal reaction at 120 °C for 16 h. After the reaction, the supernatant was discarded and the mixture was centrifuged. N,N-dimethylformamide was added, and the mixture was centrifuged at 9000 r / min for 6 min. The supernatant was then discarded again, methanol was added, and the mixture was centrifuged at 9000 r / min for 6 min. After the reaction, the resulting milky white precipitate was dried in a 70 °C oven for 12 h. The resulting milky white nanoparticles were identified as UiO-66.

[0065] S2: Dissolve 0.05g UiO-66 in 8.45g N-methylpyrrolidone, ultrasonically disperse for 30min, add 1.5g cellulose acetate, stir at room temperature for 6h, and let stand for 12h to obtain a homogeneous support layer casting solution.

[0066] The casting solution for the support layer was poured onto the glass plate of the coating machine, and the coating was carried out using a coating rod at a speed of 5 mm / s. After the coating was completed, the glass plate was placed in deionized water for 12 hours to allow for phase inversion precipitation, thereby obtaining the cellulose acetate support layer membrane.

[0067] S3: Dissolve 0.02 g of 1,3,5-benzenetricarboxyl chloride in 9.98 g of n-hexane and stir at room temperature for 3 h to obtain the core layer solution. Dissolve 0.2 g of m-phenylenediamine in 9.8 g of deionized water and stir at room temperature for 3 h to obtain the shell layer solution.

[0068] The core layer solution was loaded into the core layer syringe of the coaxial electrostatic spraying device, and the shell layer solution was loaded into the shell layer syringe of the same device. The core layer syringe and shell layer syringe were connected via a coaxial needle. The cellulose acetate support membrane was fixed to the roller receiving device. The injection speed was controlled by an automatic supply pump. The spraying voltage was set to 20kV, the injection speed of the core layer syringe was 1.5mL / h, the injection speed of the shell layer syringe was 1mL / h, and the spraying distance was 10cm. Coaxial electrostatic spraying was then performed. After 15 minutes of electrostatic spraying, the membrane was removed from the roller receiving device and allowed to air dry for 2 hours to obtain the mixed matrix membrane.

[0069] The only difference between Examples 1, 2, and 3 is that the electrostatic spraying time is gradually shortened; all other operations are the same. Figure 5 , Figure 6 , Figure 7 The images show SEM images of the mixed matrix films prepared at different spraying times in Examples 1, 2, and 3, respectively. As can be seen from the images, the quantity and thickness of the polyamide synthesized on the surface of the support film increase with increasing electrostatic spraying time. At 15 min of electrospraying, the polyamide synthesized on the surface of the mixed matrix composite film is distributed in granular and rod-like shapes. At 45 min of electrospraying, the polyamide synthesized on the surface of the mixed matrix composite film is uniformly distributed in clusters and is well-adhered to the surface of the cellulose acetate support layer film.

[0070] Figure 8 , Figure 9 , Figure 10 The images show the surface AFM images of the mixed matrix films prepared under different spraying times in Examples 1, 2, and 3, respectively. When the electrostatic spraying time is 15 min, the mean square roughness of the mixed matrix film is 63.278 nm. When the electrostatic spraying time is 30 min, the mean square roughness of the mixed matrix film is 75.538 nm. When the electrostatic spraying time is 45 min, the mean square roughness of the mixed matrix film is 90.515 nm. It can be seen that as the electrostatic spraying time increases, more polyamide is synthesized on the surface of the mixed matrix film, and the surface roughness is also greater.

[0071] Example 4

[0072] The method for preparing the high desalination performance hybrid matrix membrane described in this embodiment includes the following steps:

[0073] S1: Dissolve 0.233g zirconium tetrachloride in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution A; dissolve 0.166g terephthalic acid in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution B; mix solution A and solution B and add 5mL acetic acid as an inhibitor, stir at room temperature for 1h to obtain a metal-organic framework mixed solution.

[0074] The metal-organic framework mixture was transferred to a 30 mL reactor and subjected to a high-temperature hydrothermal reaction at 120 °C for 16 h. After the reaction, the supernatant was discarded and the mixture was centrifuged. N,N-dimethylformamide was added, and the mixture was centrifuged at 9000 r / min for 6 min. The supernatant was then discarded again, methanol was added, and the mixture was centrifuged at 9000 r / min for 6 min. After the reaction, the resulting milky white precipitate was dried in a 70 °C oven for 12 h. The resulting milky white nanoparticles were identified as UiO-66.

[0075] S2: Dissolve 0.05g UiO-66 in 8.45g N-methylpyrrolidone, ultrasonically disperse for 30min, add 1.5g cellulose acetate, stir at room temperature for 6h, and let stand for 12h to obtain a homogeneous support layer casting solution.

[0076] The casting solution for the support layer was poured onto the glass plate of the coating machine, and the coating was carried out using a coating rod at a speed of 5 mm / s. After the coating was completed, the glass plate was placed in deionized water for 12 hours to allow for phase inversion precipitation, thereby obtaining the cellulose acetate support layer membrane.

[0077] S3: Dissolve 0.02 g of 1,3,5-benzenetricarboxyl chloride in 9.98 g of n-hexane and stir at room temperature for 3 h to obtain the core layer solution. Dissolve 0.2 g of m-phenylenediamine in 9.8 g of deionized water and stir at room temperature for 3 h to obtain the shell layer solution.

[0078] The core layer solution was loaded into the core layer syringe of the coaxial electrostatic spraying device, and the shell layer solution was loaded into the shell layer syringe of the same device. The core layer syringe and shell layer syringe were connected via a coaxial needle. The cellulose acetate support membrane was fixed to the roller receiving device. The injection speed was controlled by an automatic supply pump. The spraying voltage was set to 20kV, the injection speed of both the core and shell layer syringes was 1mL / h, and the spraying distance was 10cm. Coaxial electrostatic spraying was then performed. After 45 minutes of electrostatic spraying, the membrane was removed from the roller receiving device and allowed to air dry for 2 hours to obtain the mixed matrix membrane.

[0079] Example 5

[0080] The method for preparing the high desalination performance hybrid matrix membrane described in this embodiment includes the following steps:

[0081] S1: Dissolve 0.233g zirconium tetrachloride in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution A; dissolve 0.166g terephthalic acid in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution B; mix solution A and solution B and add 5mL acetic acid as an inhibitor, stir at room temperature for 1h to obtain a metal-organic framework mixed solution.

[0082] The metal-organic framework mixture was transferred to a 30 mL reactor and subjected to a high-temperature hydrothermal reaction at 120 °C for 16 h. After the reaction, the supernatant was discarded and the mixture was centrifuged. N,N-dimethylformamide was added, and the mixture was centrifuged at 9000 r / min for 6 min. The supernatant was then discarded again, methanol was added, and the mixture was centrifuged at 9000 r / min for 6 min. After the reaction, the resulting milky white precipitate was dried in a 70 °C oven for 12 h. The resulting milky white nanoparticles were identified as UiO-66.

[0083] S2: Dissolve 0.05g UiO-66 in 8.45g N-methylpyrrolidone, ultrasonically disperse for 30min, add 1.5g cellulose acetate, stir at room temperature for 6h, and let stand for 12h to obtain a homogeneous support layer casting solution.

[0084] The casting solution for the support layer was poured onto the glass plate of the coating machine, and the coating was carried out using a coating rod at a speed of 5 mm / s. After the coating was completed, the glass plate was placed in deionized water for 12 hours to allow for phase inversion precipitation, thereby obtaining the cellulose acetate support layer membrane.

[0085] S3: Dissolve 0.02 g of 1,3,5-benzenetricarboxyl chloride in 9.98 g of n-hexane and stir at room temperature for 3 h to obtain the core layer solution. Dissolve 0.2 g of m-phenylenediamine in 9.8 g of deionized water and stir at room temperature for 3 h to obtain the shell layer solution.

[0086] The core layer solution was loaded into the core layer syringe of the coaxial electrostatic spraying device, and the shell layer solution was loaded into the shell layer syringe of the same device. The core layer syringe and shell layer syringe were connected via a coaxial needle. The cellulose acetate support membrane was fixed to the roller receiving device. The injection speed was controlled by an automatic supply pump. The spraying voltage was set to 20kV, the injection speed of the core layer syringe was 2mL / h, the injection speed of the shell layer syringe was 1mL / h, and the spraying distance was 10cm. Coaxial electrostatic spraying was performed. After 45 minutes of electrostatic spraying, the membrane was removed from the roller receiving device and allowed to air dry for 2 hours to obtain the mixed matrix membrane.

[0087] Example 6

[0088] The method for preparing the high desalination performance hybrid matrix membrane described in this embodiment includes the following steps:

[0089] S1: Dissolve 0.233g zirconium tetrachloride in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution A; dissolve 0.166g terephthalic acid in 10g N,N-dimethylformamide and sonicate for 30min to obtain homogeneous solution B; mix solution A and solution B and add 5mL acetic acid as an inhibitor, stir at room temperature for 1h to obtain a metal-organic framework mixed solution.

[0090] The metal-organic framework mixture was transferred to a 30 mL reactor and subjected to a high-temperature hydrothermal reaction at 120 °C for 16 h. After the reaction, the supernatant was discarded and the mixture was centrifuged. N,N-dimethylformamide was added, and the mixture was centrifuged at 9000 r / min for 6 min. The supernatant was then discarded again, methanol was added, and the mixture was centrifuged at 9000 r / min for 6 min. After the reaction, the resulting milky white precipitate was dried in a 70 °C oven for 12 h. The resulting milky white nanoparticles were identified as UiO-66.

[0091] S2: Dissolve 0.05g UiO-66 in 8.45g N-methylpyrrolidone, ultrasonically disperse for 30min, add 1.5g cellulose acetate, stir at room temperature for 6h, and let stand for 12h to obtain a homogeneous support layer casting solution.

[0092] The casting solution for the support layer was poured onto the glass plate of the coating machine, and the coating was carried out using a coating rod at a speed of 5 mm / s. After the coating was completed, the glass plate was placed in deionized water for 12 hours to allow for phase inversion precipitation, thereby obtaining the cellulose acetate support layer membrane.

[0093] S3: Dissolve 0.02 g of 1,3,5-benzenetricarboxyl chloride in 9.98 g of n-hexane and stir at room temperature for 3 h to obtain the core layer solution. Dissolve 0.2 g of m-phenylenediamine in 9.8 g of deionized water and stir at room temperature for 3 h to obtain the shell layer solution.

[0094] The core layer solution was loaded into the core layer syringe of the coaxial electrostatic spraying device, and the shell layer solution was loaded into the shell layer syringe of the same device. The core layer syringe and shell layer syringe were connected via a coaxial needle. The cellulose acetate support membrane was fixed to the roller receiving device. The injection speed was controlled by an automatic supply pump. The spraying voltage was set to 20kV, the injection speed of the core layer syringe was 1mL / h, the injection speed of the shell layer syringe was 2mL / h, and the spraying distance was 10cm. Coaxial electrostatic spraying was performed. After 45 minutes of electrostatic spraying, the membrane was removed from the roller receiving device and allowed to air dry for 2 hours to obtain the mixed matrix membrane.

[0095] The only difference between Examples 4, 5, and 6 is the different propulsion speeds of the core-layer syringe and the shell-layer syringe; all other steps are the same. The above three examples improved the propulsion speed of the syringe, thereby altering the microstructure, thickness, and properties of the resulting hybrid matrix membrane. The influence of the propulsion speed on the properties of the resulting hybrid matrix membrane was verified by studying the flux and removal rate of the hybrid matrix membrane.

[0096] The performance of the mixed matrix membranes prepared in Examples 1, 4, 5, and 6 was tested at 0.1 MPa using aqueous solutions of Na₂SO₄, MgSO₄, MgCl₂, CaCl₂, and NaCl, respectively. The results are shown in Table 2 below.

[0097] Table 2. Performance comparison of the hybrid matrix membranes prepared in Examples 1, 4, 5, and 6.

[0098]

[0099] As can be seen from Table 2, under the condition of a certain spraying time, the effect of different propulsion speeds of the core layer and shell layer syringes on the synthesis of polyamide active layer was tested and analyzed. It was found that the mixed matrix membrane with the best membrane flux and removal rate was obtained when the propulsion speed of the core layer syringe was 1.5 mL / h and the propulsion speed of the shell layer syringe was 1 mL / h.

[0100] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a highly stable hybrid matrix membrane, characterized in that, Includes the following steps: S1: Dissolve metal-organic framework powder in organic solvent A, add cellulose acetate, and stir to obtain a support layer casting solution; use the support layer casting solution as a coating material to form a film, then place it in deionized water for phase inversion, and dry to obtain a support layer film; the mass fraction of cellulose acetate in the support layer casting solution is 9~18%; the mass fraction of metal-organic framework powder in the support layer casting solution is 0.2~0.8%; S2: The acyl chloride monomer is dissolved in organic solvent B to obtain a core layer solution; the amine monomer is dissolved in deionized water to obtain a shell layer solution; the mass fraction of the acyl chloride monomer in the core layer solution is 0.1~0.5%; the mass fraction of the amine monomer in the shell layer solution is 1~5%. S3: The core layer solution and shell layer solution are loaded into a coaxial static spraying device as coatings, and electrostatic spraying technology is used to electrostatically spray the support layer film surface. After drying, a mixed matrix film is obtained. In step S3, the coaxial electrostatic spraying device includes a core layer syringe containing a core layer solution, a shell layer syringe containing a shell layer solution, a coaxial needle for connecting the core layer syringe and the shell layer syringe, and a receiving device for fixing the support film; the process parameters of the electrostatic spraying are: the advance speed of the core layer syringe: 1~2mL / h, the advance speed of the shell layer syringe: 1~2mL / h, the spraying voltage: 12~20kV, the spraying distance: 10~20cm, and the spraying time: 10~50min.

2. The preparation method according to claim 1, characterized in that, The metal-organic framework used in step S1 is UiO-66; the preparation method of the UiO-66 powder includes the following steps: S1.1: Dissolve the carboxylic acid organic ligand and zirconium salt separately in organic solvent C, then mix the two solutions and add an inhibitor to obtain a mixed solution of metal-organic framework; S1.2: The mixed solution of metal-organic frameworks was subjected to a hydrothermal reaction. After the reaction was completed, the solution was centrifuged and dried to obtain UiO-66 powder.

3. The preparation method according to claim 2, characterized in that, In step S1.1, the carboxylic acid organic ligand is one or more of terephthalic acid, amino-terephthalic acid, and fumaric acid; the zirconium salt is zirconium tetrachloride; the molar ratio of the carboxylic acid organic ligand to the zirconium salt is 1:1; the organic solvent C is one or more of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the amount added is 15-30 mL; the inhibitor is acetic acid, and the amount added is 4-8 mL.

4. The preparation method according to claim 2, characterized in that, In step S1.2, the parameters of the hydrothermal reaction are: temperature: 100~150℃, reaction time: 12~24h; the parameters of the centrifugation are: rotation speed: 7000~9000r / min, centrifugation time per cycle: 5~8min, number of centrifugations: not less than 2; the drying temperature is 60~90℃, and the drying time is 10~16h.

5. The preparation method according to claim 1, characterized in that, In step S1, the organic solvent A is one or more combinations of N,N-dimethylformamide, α-valerolactone, and N-methylpyrrolidone.

6. The preparation method according to claim 1, characterized in that, In step S1, a coating machine is used for coating, and the advance speed of the coating machine is 5~15mm / s; the phase transformation time is 12~16h; the drying condition is natural drying, and the drying time is 3~6h.

7. The preparation method according to claim 1, characterized in that, In step S2, the acyl chloride monomer is one of 1,3,5-benzenetricarboxyl chloride, 5-chloropentanoyl chloride, isophthaloyl chloride, and 2,6-dichloro-5-fluoronicotinic chloride; the organic solvent B is one or more combinations of n-hexane, methane, propane, and heptane; and the amine monomer is one of m-phenylenediamine, 1,1-dimethylethylenediamine, 1,2-dimethylethylenediamine, and p-phenylenediamine.

8. A high-stability hybrid matrix membrane prepared by any one of the preparation methods of claims 1 to 7.

9. The application of the high-stability hybrid matrix membrane according to claim 8, characterized in that, Used for wastewater purification and seawater desalination.

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