A zirconium-based amorphous MOF membrane, a preparation method and application thereof in membrane separation

Abstract

This invention relates to a zirconium-based amorphous MOF membrane, its preparation method, and its application in membrane separation, belonging to the field of membrane material preparation and membrane separation technology. The invention first involves the application of metal ions Zr... 4+ Pre-assembled into metal clusters, followed by the preparation of aqueous solutions of ligands and oil solutions of the metal clusters, using a hydrophilic polymer porous substrate as a carrier, the carrier is alternately immersed in aqueous or deprotonated aqueous and oil solutions to obtain a series of stable zirconium-based amorphous MOF membranes for organic solvent nanofiltration, gas separation, or ion separation. This invention rapidly prepares a series of stable and porous zirconium-based amorphous MOF membranes at room temperature using a pre-processing-interface assembly method, solving the problem of difficult membrane formation of amorphous MOFs at room temperature. These membranes exhibit both high solute rejection and high organic solvent permeation flux in organic solvent nanofiltration separation, and can specifically be used for the separation of dye molecules in ethanol solvents.

Description

Technical Field

[0001] This invention belongs to the field of membrane material preparation and membrane separation technology, specifically relating to a zirconium-based amorphous MOF membrane, its preparation method, and its application in membrane separation. Background Technology

[0002] Organic solvents are a class of organic compounds widely used in daily life and production. Since the Second Industrial Revolution, the use of organic solvents in various industries has increased year by year, inevitably generating a large amount of waste organic solvents. Improper handling and indiscriminate discharge of waste organic solvents have caused serious environmental pollution. Therefore, the treatment and recycling of organic solvents has gradually become a focus of attention. Traditional methods for treating organic solvents include distillation, absorption, and extraction. These separation methods have disadvantages such as high energy consumption, high separation costs, and secondary pollution to the environment. Membrane separation technology, on the other hand, has advantages such as low energy consumption, small footprint, no phase change or chemical reaction during separation, and high separation efficiency, and has attracted widespread attention.

[0003] Organic solvent nanofiltration (OSN) technology, as an emerging membrane separation technology, can be used for the efficient separation of small organic molecules with molecular weights of 200–1000 Da in organic solvent systems, demonstrating significant advantages in organic solvent media separation and solvent recovery in chemical, pharmaceutical, and food industries. Currently, the most widely used commercial organic solvent nanofiltration membrane is a thin film composite (TFC) membrane with polyamide (PA) as the main separation layer.

[0004] Interfacial polymerization (IP) is the most commonly used method for preparing TFC membranes. Its basic principle involves dissolving two highly reactive monomers separately in two immiscible solvents (typically an aqueous solution and an organic phase), where a rapid polycondensation reaction occurs at the interface to form a dense polymer film. However, composite membranes also suffer from limitations such as low organic solvent permeation flux, susceptibility to fouling, and the "trade-off" effect.

[0005] Amorphous metal-organic frameworks (aMOFs), with abundant open sites, possess the same inorganic nodes and organic ligands as crystalline MOFs, but do not exhibit a long-range ordered crystalline structure. This means that aMOFs may possess porosity and abundant active sites comparable to crystalline MOFs due to structural defects. Furthermore, the same connectivity as crystalline MOFs, coupled with higher disorder entropy, gives aMOFs comparable or higher stability compared to crystalline MOF materials. However, existing processing methods, due to low input energy, typically tend to yield powder materials rather than continuous films. Therefore, it is necessary to develop methods for directly preparing aMOF film materials under mild conditions, leveraging their unique advantages to achieve efficient separation of target systems. Summary of the Invention

[0006] One objective of this invention is to provide a zirconium-based amorphous MOF membrane, its preparation method, and its application in membrane separation, particularly in organic solvent nanofiltration, to overcome the limitations of existing technologies. This series of amorphous MOF membranes features a simple preparation method, high stability, and excellent separation performance, enabling effective separation of small organic molecules and solvent recovery from organic solvents, thus meeting the demand for high-performance membrane materials in organic solvent nanofiltration and recovery applications. The application of zirconium-based amorphous MOF membranes with other structures prepared using the method provided by this invention is not limited to organic solvent nanofiltration; it can also be extended to gas separation or ion separation.

[0007] This invention employs a pre-assembled metal cluster-ligand deprotonation strategy and utilizes interfacial polymerization to rapidly prepare a series of stable zirconium-based amorphous MOF films at room temperature. The preparation steps are as follows:

[0008] (1) Pre-processing of metal ions: Pre-processing of metal ions Zr 4+ Pre-assembled as Zr6O4(OH)4(COOPh) 12 Metallic clusters (Zr6 clusters);

[0009] (2) Preparation of aqueous and oil phase solutions: Dissolve carboxylic acid organic ligands in deionized water to obtain an aqueous phase solution, and dissolve the metal cluster obtained in step (1) in an organic solvent that is immiscible with water to obtain an oil phase solution; add sodium hydroxide to the aqueous phase solution, with the molar ratio of organic ligands to sodium hydroxide being 1:2, to obtain a deprotonated aqueous phase solution;

[0010] (3) Selection of carrier: Use a hydrophilic polymer porous bottom membrane as the carrier;

[0011] (4) Preparation of a series of amorphous MOF membranes: The support described in step (3) is soaked in an aqueous solution or a deprotonated aqueous solution. After the support is taken out, the aqueous solution remaining on the front side of the support is removed by an air knife. Then, the oil solution is slowly poured onto the front side of the support for interface assembly. Then, the oil solution is poured out from the front side of the support to remove the oil solution. Finally, the front and back sides of the support are cleaned and dried to obtain a stable zirconium-based amorphous MOF membrane.

[0012] Furthermore, step (1) pre-assembles Zr6O4(OH)4(COOPh) 12 The method for metal clusters (Zr6 clusters) is as follows:

[0013] 10–20 mL of a n-butanol solution containing 80 wt.% zirconium butoxide (Zr(OBu)4) and 80–120 g of benzoic acid (C6H5COOH) were added to 250–350 mL of n-propanol and sonicated for 10–30 min. The resulting mixture was heated under reflux overnight to obtain a clear solution. Excess solvent was removed by vacuum distillation at 50–70 °C. The resulting solid was then thoroughly washed with n-propanol and dried under vacuum at room temperature to obtain Zr6O4(OH)4(COOPh). 12 Metal clusters (Zr6 clusters).

[0014] Furthermore, in step (2), zirconium-based amorphous MOF membranes of the aUiO-66 series were prepared using aqueous solutions of different carboxylic acid organic ligands:

[0015] aUiO-66 membrane: Prepare an aqueous solution of disodium terephthalate with a concentration of 0.2-0.6 wt% as the aqueous phase solution; prepare an oil phase solution of 1-octanol of Zr6 clusters with a concentration of 0.2-0.6 wt%.

[0016] aUiO-66-SO3 membrane: Prepare an aqueous solution of 2-sulfonic acid monosodium terephthalate with a concentration of 0.2-0.6 wt% as the aqueous phase solution; prepare a 1-octanol solution of Zr6 cluster with a concentration of 0.2-0.6 wt% as the oil phase solution;

[0017] aUiO-66-NH2 membrane: Prepare an aqueous solution of disodium 2-aminoterephthalate with a concentration of 0.4-0.6 wt% according to the molar ratio of 2-aminoterephthalic acid and sodium hydroxide of 1:2 as the aqueous phase solution; prepare a 1-octanol solution of Zr6 cluster with a concentration of 0.05-0.2 wt% as the oil phase solution;

[0018] aUiO-66-F4 membrane: Prepare an aqueous solution of tetrafluoroterephthalic acid with a concentration of 0.1-0.4 wt% as the aqueous phase solution; prepare a 1-octanol solution of Zr6 cluster with a concentration of 1-3 wt% as the oil phase solution.

[0019] Furthermore, in step (3), a hydrophilic polymer porous substrate is used as a carrier, and the polymer porous substrate is polyethersulfone (PES).

[0020] Furthermore, before use, the carrier is first soaked in isopropanol for 10-20 minutes; then it is soaked in deionized water for 20-30 hours, with the deionized water being replaced every 6-12 hours during this period.

[0021] Further, step (4) a. Preparation of UiO-66 series zirconium-based amorphous MOF films

[0022] Preparation of aUiO-66 membrane: At 10–35℃, the carrier was fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it was soaked in an aqueous solution of disodium terephthalate. After 4–8 hours, the aqueous solution was poured out of the mold, and the excess aqueous solution on the front side of the carrier was blown away with an air knife. The 1-octanol solution of Zr6 clusters was slowly poured onto the front side of the carrier for interfacial assembly. After 1–10 minutes, the oil phase solution on the front side of the carrier was poured out. The carrier was removed from the mold, the front side of the carrier was washed with 1-octanol, the back side of the carrier was washed with deionized water, and dried in an oven at 40–60℃.

[0023] Preparation of aUiO-66-SO3 membrane: At 10-35℃, the support was fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it was soaked in an aqueous solution of 2-sulfonic acid monosodium terephthalate. After 4-8 hours, the aqueous solution was poured out of the mold, and the excess aqueous solution on the front side of the support was blown away with an air knife. The 1-octanol solution of Zr6 cluster was slowly poured onto the front side of the support for interfacial assembly. After 1-10 minutes, the oil phase solution on the front side of the support was poured out. The support was removed from the mold, the front side of the support was washed with 1-octanol, the back side of the support was washed with deionized water, and dried in an oven at 40-60℃.

[0024] Preparation of aUiO-66-NH2 membrane: At 10-35℃, the carrier was fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it was soaked in an aqueous solution of disodium 2-aminoterephthalate. After 4-8 hours, the aqueous solution was poured out of the mold, and the excess aqueous solution on the front side of the carrier was blown away with an air knife. The 1-octanol solution of Zr6 cluster was slowly poured onto the front side of the carrier for interface assembly. After 1-20 minutes, the oil phase solution on the front side of the carrier was poured out. The carrier was removed from the mold, the front side of the carrier was washed with 1-octanol, the back side of the carrier was washed with deionized water, and dried in an oven at 40-60℃.

[0025] aUiO-66-F4 membrane: At 10-35℃, the carrier is fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it is soaked in tetrafluoroterephthalic acid aqueous solution. After 4-8 hours, the aqueous phase solution is poured out of the mold, and the excess aqueous phase solution on the front side of the carrier is blown away with an air knife. The 1-octanol solution of Zr6 cluster is slowly poured onto the front side of the carrier for interface assembly. After 1-30 minutes, the oil phase solution on the front side of the carrier is poured out. The carrier is removed from the mold, the front side of the carrier is washed with 1-octanol, the back side of the carrier is washed with deionized water, and dried in an oven at 40-60℃.

[0026] Another object of the present invention is to provide the application of the above-mentioned series of amorphous MOF membranes in nanofiltration separation, gas separation, and ion separation of organic solvents, preferably for the separation of dye molecules in ethanol solvents. The present invention has the following beneficial effects:

[0027] This invention rapidly prepares a series of stable and porous amorphous MOF membranes at room temperature using a pre-processing-interface assembly method, solving the problem that amorphous MOFs are difficult to form at room temperature. The membranes exhibit both high solute rejection rate and high organic solvent permeation flux in organic solvent nanofiltration separation. Attached Figure Description

[0028] Figure 1 Figure a shows the N2 adsorption isotherms (Fig. a) and pore size distribution (Fig. b) of aUiO-66 3 min and aUiO-66 5 min prepared in Examples 2 and 3 at 77 K.

[0029] Figure 2 XRD patterns of aUiO-66 prepared in Examples 1-6;

[0030] Figure 3 SEM images of the aUiO-66 films prepared in Examples 1-6; (a) SEM image of the product of Example 1; (b) SEM image of the product of Example 2; (c) SEM image of the product of Example 3; (d) SEM image of the product of Example 4; (e) SEM image of the product of Example 5; (f) SEM image of the product of Example 6;

[0031] Figure 4 Comparison of organic solvent nanofiltration separation performance of aUiO-66 membrane in Examples 1-3. The left and right vertical axes in the figure represent the ethanol solvent permeation flux P and the Congo red solute rejection rate R, respectively, and the calculation formulas are formula (1) and formula (2) in the specific implementation method.

[0032] Figure 5Comparison of organic solvent nanofiltration separation performance of aUiO-66-SO3, aUiO-66-NH2, and aUiO-66-F4 membranes in Examples 4-6. The left and right vertical axes in the figure represent the ethanol solvent permeation flux P and the Congo red solute rejection rate R, respectively, and the calculation formulas are formula (1) and formula (2) in the specific implementation embodiments. Detailed Implementation

[0033] To more clearly illustrate the advantages and technical solutions of this invention, the invention is further described below in conjunction with specific embodiments and accompanying drawings. Unless otherwise specified, the reagents, methods, and equipment used in this invention are all conventional reagents, methods, and equipment in this technical field. All raw materials used in this invention are commercially available.

[0034] In the following examples, a series of amorphous MOF membranes were subjected to organic solvent nanofiltration tests. The testing apparatus used was a dead-end filtration device, and the detailed parameters were as follows: the effective filtration area of ​​the membrane was 1.77 × 10⁻⁶. -4 m -2 The device was sealed with an O-ring. The test solution was an ethanol solution of Congo red with a concentration of 100 ppm and a volume of 50 mL. The test solution was added to the test device at 25±10℃ and 0.2 MPa pressure. After pre-pressurizing for 30 min to obtain a stable flux, the pure solvent permeation flux and the Congo red solute rejection rate were tested.

[0035] The formula for calculating solvent permeation flux (P) is:

[0036]

[0037] In formula (1), ΔV is the volume of the permeate solution (L), and S is the effective membrane area (m²). -2 ), where t is the filtration time (h) and ΔP is the transmembrane pressure (MPa).

[0038] The formula for calculating the solute rejection ratio (R) is:

[0039]

[0040] In formula (2), C p and C f These represent the concentrations of the solute in the permeate and feed solutions, respectively.

[0041] Example 1:

[0042] (1) Pre-processing of metal ions

[0043] Zr 4+ Pre-processed to Zr6O4(OH)4(COOPh) 12Cluster (Zr6 cluster): 15 mL of n-butanol solution containing 80 wt.% zirconium butoxide (Zr(OBu)4) and 100 g of benzoic acid (C6H5COOH) were added to 300 mL of n-propanol and sonicated for 20 min. The resulting mixture was heated under reflux overnight to obtain a clear solution. Excess solvent was removed by vacuum distillation at 60 °C. The obtained solid was thoroughly washed with n-propanol and dried under vacuum at room temperature to obtain Zr6O4(OH)4(COOPh). 12 Metal clusters (Zr6 clusters), with a product yield of approximately 63%.

[0044] (2) Preparation of aqueous and oil phase solutions

[0045] A 0.5 wt% disodium terephthalate aqueous solution was prepared as the deprotonated aqueous phase solution, with a molar ratio of disodium terephthalate to sodium hydroxide of 1:2. A 0.2 wt% Zr6 cluster 1-octanol solution was prepared as the oil phase solution.

[0046] (3) Selection of carrier

[0047] PES carrier was selected. Before use, it was soaked in isopropanol for 15 minutes and then immersed in deionized water for 24 hours. During this period, the deionized water was changed every 12 hours.

[0048] (4) Preparation of amorphous MOF membranes

[0049] Preparation of aUiO-66 membrane: At 25°C, the PES support, which had been treated with isopropanol and deionized water, was fixed in the middle of a mold consisting of an O-ring and a circular plate with the same radius of 3.5 cm and sealed. The PES support treated in step (3) was soaked in the deprotonated aqueous solution obtained in step (2). After 6 h, the aqueous solution was poured out of the mold and the excess aqueous solution on the front side of the support was blown away with an air knife. The oil phase solution in step (2) was slowly poured onto the front side of the support for interface assembly. After 1 min, the oil phase solution on the front side of the support was poured out. The support was taken out of the mold, the front side of the support was washed with 1-octanol, the back side of the support was washed with deionized water, and dried in an oven at 60°C. The resulting aUiO-66 membrane was labeled as aUiO-661min.

[0050] The amorphous aUiO-66 membrane prepared by the above method was subjected to dead-end filtration tests for organic solvent nanofiltration, and its ethanol flux was 87.4 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 82.3%.

[0051] Example 2:

[0052] (1) Synthesize Zr6O4(OH)4(COOPh) according to step (1) of Example 1. 12 cluster;

[0053] (2) Prepare the deprotonated aqueous phase solution and oil phase solution according to step (2) of Example 1;

[0054] (3) Select a carrier according to step (3) of Example 1;

[0055] (4) Preparation of amorphous MOF membranes

[0056] Preparation of aUiO-66 membrane: At 25°C, the PES support, which had been treated with isopropanol and deionized water, was fixed in the middle of a mold consisting of an O-ring and a circular plate with the same radius of 3.5 cm and sealed. The PES support treated in step (3) was soaked in the deprotonated aqueous solution obtained in step (2). After 6 h, the aqueous solution was poured out of the mold and the excess aqueous solution on the front side of the support was blown away with an air knife. The oil phase solution in step (2) was slowly poured onto the front side of the support for interface assembly. After 3 min, the oil phase solution on the front side of the support was poured out. The support was taken out of the mold, the front side of the support was washed with 1-octanol, the back side of the support was washed with deionized water, and dried in an oven at 60°C. The resulting aUiO-66 membrane was labeled as aUiO-663min.

[0057] The amorphous aUiO-66 membrane prepared by the above method was subjected to dead-end filtration tests for organic solvent nanofiltration, and its ethanol flux was 54.86 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 99.2%.

[0058] Example 3:

[0059] (1) Synthesize Zr6O4(OH)4(COOPh) according to step (1) of Example 1. 12 cluster;

[0060] (2) Prepare the deprotonated aqueous phase solution and oil phase solution according to step (2) of Example 1;

[0061] (3) Select a carrier according to step (3) of Example 1;

[0062] (4) Preparation of amorphous MOF membranes

[0063] Preparation of aUiO-66 membrane: At 25°C, the PES support, which had been treated with isopropanol and deionized water, was fixed in the middle of a mold consisting of an O-ring and a circular plate with the same radius of 3.5 cm and sealed. The PES support treated in step (3) was soaked in the deprotonated aqueous solution obtained in step (2). After 6 h, the aqueous solution was poured out of the mold and the excess aqueous solution on the front side of the support was blown away with an air knife. The oil phase solution in step (2) was slowly poured onto the front side of the support for interface assembly. After 5 min, the oil phase solution on the front side of the support was poured out. The support was taken out of the mold, the front side of the support was washed with 1-octanol, the back side of the support was washed with deionized water, and dried in an oven at 60°C. The resulting aUiO-66 membrane was labeled as aUiO-665min.

[0064] The amorphous aUiO-66 membrane prepared by the above method was subjected to dead-end filtration tests for organic solvent nanofiltration, and its ethanol flux was 51.2 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 98.5%.

[0065] Example 4:

[0066] (1) Synthesize Zr6O4(OH)4(COOPh) according to step (1) of Example 1. 12 cluster;

[0067] (2) Preparation of aqueous and oil phase solutions

[0068] Prepare an aqueous solution of 0.4 wt% sodium 2-sulfonic acid terephthalate as the aqueous phase solution; prepare a 0.4 wt% solution of 1-octanol of Zr6 cluster as the oil phase solution.

[0069] (3) Selection of carrier

[0070] PES carriers were selected and treated with isopropanol for 15 minutes before use, and then soaked in deionized water for 24 hours, with the water changed every 12 hours during the period.

[0071] (4) Preparation of amorphous MOF membranes

[0072] Preparation of aUiO-66-SO3 membrane: At 25°C, the PES carrier, which has been soaked in isopropanol and deionized water, is fixed in the middle of a mold consisting of an O-ring and a circular plate with the same radius of 3.5 cm and sealed. The PES carrier treated in step (3) is soaked in the 2-sulfonic acid monosodium terephthalate aqueous solution in step (2). After 6 h, the aqueous solution is poured out of the mold and the excess aqueous solution on the front side of the carrier is blown away with an air knife. The oil phase solution in step (2) is slowly poured onto the front side of the carrier for interface assembly. After 1 min, the oil phase solution on the front side of the carrier is poured out. The carrier is taken out of the mold, the front side of the carrier is washed with 1-octanol, the back side of the carrier is washed with deionized water, and dried in an oven at 60°C.

[0073] The amorphous aUiO-66-SO3 membrane prepared by the above method was subjected to dead-end filtration tests for organic solvent nanofiltration, and its ethanol flux was 41.01 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 94.6%.

[0074] Example 5:

[0075] (1) Synthesize Zr6O4(OH)4(COOPh) according to step (1) of Example 1. 12 cluster.

[0076] (2) Preparation of aqueous and oil phase solutions

[0077] Prepare an aqueous solution of 0.5 wt% disodium 2-aminoterephthalate with a molar ratio of 1:2 for 2-aminoterephthalic acid and sodium hydroxide, as the deionized aqueous phase solution; prepare a 0.1 wt% solution of 1-octanol containing Zr6 clusters, as the oil phase solution.

[0078] (3) Selection of carrier

[0079] PES carrier was selected. Before use, it was soaked in isopropanol for 15 minutes and then immersed in deionized water for 24 hours, with the water changed every 12 hours.

[0080] (4) Preparation of amorphous MOF membranes

[0081] Preparation of aUiO-66-NH2 membrane: At 25°C, the PES carrier, which has been soaked in isopropanol and deionized water, is fixed in the middle of a mold consisting of an O-ring and a circular plate with the same radius of 3.5 cm and sealed. The PES carrier treated in step (3) is soaked in the 2-aminoterephthalate disodium aqueous solution in step (2). After 6 h, the aqueous solution is poured out of the mold and the excess aqueous solution on the front side of the carrier is blown away with an air knife. The oil phase solution in step (2) is slowly poured onto the front side of the carrier for interface assembly. After 10 min, the oil phase solution on the front side of the carrier is poured out. The carrier is taken out of the mold, the front side of the carrier is washed with 1-octanol, the back side of the carrier is washed with deionized water, and dried in an oven at 60°C.

[0082] The amorphous aUiO-66-NH2 membrane prepared by the above method was subjected to dead-end filtration tests for organic solvent nanofiltration, and its ethanol flux was 35.06 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 81.91%.

[0083] Example 6

[0084] (1) Synthesize Zr6O4(OH)4(COOPh) according to step (1) of Example 1. 12 cluster.

[0085] (2) Preparation of aqueous and oil phase solutions

[0086] Prepare an aqueous solution of tetrafluoroterephthalic acid with a concentration of 0.3 wt% as the aqueous phase solution; prepare a 1 wt% Zr6 solution in 1-octanol as the oil phase solution.

[0087] (3) Selection of carrier

[0088] PES carrier was selected. Before use, it was soaked in isopropanol for 15 minutes and then immersed in deionized water for 24 hours, with the water changed every 12 hours.

[0089] (4) Preparation of amorphous MOF membranes

[0090] Preparation of aUiO-66-F4 membrane: At 25°C, the PES carrier, which had been soaked in isopropanol and deionized water, was fixed in the middle of a mold consisting of an O-ring and a circular plate with the same radius of 3.5 cm and sealed. The PES carrier treated in step (3) was soaked in the tetrafluoroterephthalic acid aqueous solution in step (2). After 6 h, the aqueous phase solution was poured out of the mold and the excess aqueous phase solution on the front side of the carrier was blown away with an air knife. The oil phase solution in step (2) was slowly poured onto the front side of the carrier for interface assembly. After 5 min, the oil phase solution on the front side of the carrier was poured out. The carrier was taken out of the mold, the front side of the carrier was washed with 1-octanol, the back side of the carrier was washed with deionized water, and dried in an oven at 60°C.

[0091] The amorphous aUiO-66-F4 membrane prepared by the above method was subjected to dead-end filtration tests for organic solvent nanofiltration, and its ethanol flux was 26.65 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 95.07%.

[0092] Figure 1 The N2 adsorption isotherms and pore size distribution of aUiO-66 prepared in Examples 2 and 3 at 77 K for 3 min and 5 min are shown. The adsorption capacity of UiO-66 (prepared according to reference J. Am. Chem. Soc. 2008, 130, 42, 13850–13851) is 826.69 cm⁻¹. 3 g -1 The specific surface area of ​​BET is 719.6 m². 2 g -1 The adsorption capacity of aUiO-66 obtained by interfacial polymerization for 3 min was 401.6 cm⁻¹. 3 g -1 The specific surface area of ​​BET is 309.1 m². 2 g -1 The adsorption capacity of aUiO-66 obtained by interfacial polymerization for 5 min was 213.3 m. 3 g -1 The specific surface area of ​​BET is 311.2 m². 2 g -1 The pore size distribution range of UiO-66 is... The pore size distribution of aUiO-66 obtained by interfacial polymerization for 3 minutes is as follows: The pore size distribution of aUiO-66 obtained by interfacial polymerization for 5 min is as follows: The results show that aUiO-66 prepared by the pre-processing-interface assembly method has good porosity.

[0093] Figure 2 The images show the XRD patterns of the aUiO-66 films prepared in Examples 1-6. The results show that the aUiO-66, aUiO-66-SO3, aUiO-66-NH2, and aUiO-66-F4 films prepared by the pre-processing-interface assembly method do not have the Bragg peaks corresponding to crystalline MOF materials, but instead exhibit an amorphous state.

[0094] Figure 3 The images show SEM images of the aUiO-66 membranes prepared in Examples 1-6. The results show that the aUiO-66, aUiO-66-SO3, aUiO-66-NH2, and aUiO-66-F4 membranes prepared by the pre-processing-interface assembly method are continuous membrane materials without obvious defects.

[0095] Figure 4 The organic solvent nanofiltration separation performance of the aUiO-66 membranes prepared in Examples 1-3 is shown. The ethanol flux of the aUiO-66 membrane obtained in Example 1 is 87.4 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 82.3%; the ethanol flux of the aUiO-66 membrane obtained in Example 2 was 54.86 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 99.2%; the ethanol flux of the aUiO-66 membrane obtained in Example 3 was 51.2 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 98.5%. The results indicate that the aUiO-66 membrane prepared by pre-processing-interface assembly exhibits good porosity and stability, maintaining a high permeation flux of ethanol solvent while also achieving a high rejection rate for Congo red.

[0096] Figure 5 This is a comparison chart of the organic solvent nanofiltration separation performance of the aUiO-66-SO3, aUiO-66-NH2, and aUiO-66-F4 membranes in Examples 4-6. The ethanol flux of the aUiO-66-SO3 membrane obtained in Example 4 was 41.01 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 94.6%; the ethanol flux of the aUiO-66-NH2 membrane obtained in Example 5 was 35.06 L / m³. -2 h -1 MPa -1 The rejection rate for Congo red was 81.91%; the ethanol flux of the aUiO-66-F4 membrane obtained in Example 6 was 26.65 L / m³.-2 h -1 MPa -1 The rejection rate for Congo red was 95.07%. The results indicate that the amorphous MOF membrane obtained by interfacial polymerization of organic ligands with different functional groups exhibits good nanofiltration performance for organic solvents.

Claims

1. A method for preparing a zirconium-based amorphous MOF film, comprising the following steps: (1) Pre-processing of metal ions: Pre-processing of metal ions Zr 4+ Pre-assembled as Zr6O4(OH)4(COOPh) 12 Metal clusters; (2) Preparation of aqueous and oil phase solutions: Dissolve carboxylic acid organic ligands in deionized water to obtain an aqueous phase solution, and dissolve the metal clusters obtained in step (1) in an organic solvent that is immiscible with water to obtain an oil phase solution; (3) Selection of carrier: Use a hydrophilic polymer porous bottom membrane as the carrier; (4) Preparation of aUiO-66 membrane: At 10~35 ℃, the carrier described in step (3) is fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it is soaked in an aqueous solution of disodium terephthalate. After 4~8 h, the aqueous solution is poured out of the mold, and the excess aqueous solution on the front side of the carrier is blown away with an air knife. 12 The 1-octanol solution of the metal clusters was slowly poured onto the front side of the support for interfacial assembly. After 1 to 10 minutes, the oil phase solution on the front side of the support was poured out. The support was removed from the mold, the front side of the support was washed with 1-octanol, the back side of the support was washed with deionized water, and then dried in an oven at 40 to 60 °C. Preparation of aUiO-66-SO3 membrane: At 10~35 ℃, the carrier described in step (3) was fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it was soaked in an aqueous solution of 2-sulfonic acid monosodium terephthalate. After 4~8 h, the aqueous solution was poured out of the mold, and the excess aqueous solution on the front side of the carrier was blown away with an air knife. Zr6O4(OH)4(COOPh) 12 The 1-octanol solution of the metal clusters was slowly poured onto the front side of the support for interfacial assembly. After 1 to 10 minutes, the oil phase solution on the front side of the support was poured out. The support was removed from the mold, the front side of the support was washed with 1-octanol, the back side of the support was washed with deionized water, and then dried in an oven at 40 to 60 °C. Preparation of aUiO-66-NH2 membrane: At 10~35 ℃, the carrier described in step (3) was fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it was soaked in an aqueous solution of disodium 2-aminoterephthalate. After 4~8 h, the aqueous solution was poured out of the mold, and the excess aqueous solution on the front side of the carrier was blown away with an air knife. Zr6O4(OH)4(COOPh) 12 The 1-octanol solution of the metal cluster was slowly poured onto the front side of the support for interfacial assembly. After 1-20 min, the oil phase solution on the front side of the support was poured out. Remove the carrier from the mold, wash the front side of the carrier with 1-octanol, wash the back side of the carrier with deionized water, and dry it in an oven at 40~60 ℃. aUiO-66-F4 membrane: At 10~35 ℃, the carrier described in step (3) is fixed in the middle of a mold consisting of an O-ring and a circular plate of the same radius and sealed. Then, it is soaked in tetrafluoroterephthalic acid aqueous solution. After 4~8 h, the aqueous solution is poured out of the mold, and the excess aqueous solution on the front side of the carrier is blown away with an air knife; Zr6O4(OH)4(COOPh) 12 The 1-octanol solution of the metal clusters was slowly poured onto the front side of the support for interfacial assembly; after 1-30 min, the oil phase solution on the front side of the support was poured off. Remove the carrier from the mold, wash the front side of the carrier with 1-octanol, wash the back side of the carrier with deionized water, and dry it in an oven at 40~60 ℃.

2. The method for preparing a zirconium-based amorphous MOF film as described in claim 1, characterized in that: Step (1) involves adding 10-20 mL of a n-butanol solution containing 80 wt% Zr(OBu)4 and 80-120 g of benzoic acid to 250-350 mL of n-propanol, and sonicating for 10-30 min. The resulting mixture is then heated under reflux overnight to obtain a clear solution. The solution is then heated to 50-70 °C. o Excess solvent was removed by vacuum distillation, and the resulting solid was then thoroughly washed with n-propanol and dried under vacuum at room temperature to obtain Zr6O4(OH)4(COOPh). 12 Metal clusters.

3. The method for preparing a zirconium-based amorphous MOF film as described in claim 1, characterized in that: The aUiO-66 series of zirconium-based amorphous MOF membranes were prepared using aqueous solutions of different carboxylic acid organic ligands. Preparation of aUiO-66 membrane: Prepare an aqueous solution of disodium terephthalate with a concentration of 0.2~0.6 wt% as the aqueous phase solution; prepare a Zr6O4(OH)4(COOPh) solution with a concentration of 0.2~0.6 wt%. 12 A 1-octanol solution of a metal cluster is used as the oil phase solution. Preparation of aUiO-66-SO3 membrane: Prepare an aqueous solution of 0.2~0.6 wt% sodium 2-sulfonic acid terephthalate as the aqueous phase solution; prepare a Zr6O4(OH)4(COOPh) solution of 0.2~0.6 wt% 12 A 1-octanol solution of a metal cluster is used as the oil phase solution. Preparation of aUiO-66-NH2 membrane: A 0.4–0.6 wt% aqueous solution of disodium 2-aminoterephthalate was prepared as the aqueous phase solution at a molar ratio of 1:2 for 2-aminoterephthalic acid and sodium hydroxide; a 0.05–0.2 wt% Zr6O4(OH)4(COOPh) solution was prepared. 12 A 1-octanol solution of a metal cluster is used as the oil phase solution. Preparation of aUiO-66-F4 membrane: Prepare an aqueous solution of tetrafluoroterephthalic acid with a concentration of 0.1~0.4 wt% as the aqueous phase solution; prepare a Zr6O4(OH)4(COOPh) solution with a concentration of 1~3 wt%. 12 A 1-octanol solution of a metal cluster is used as the oil phase solution.

4. The method for preparing a zirconium-based amorphous MOF film as described in claim 1, characterized in that: In step (3), a hydrophilic polymer porous membrane is used as a carrier; in step (4), the carrier is first soaked in isopropanol for 10-20 minutes before use, and then soaked in deionized water for 20-30 hours, during which time the deionized water is replaced every 6-12 hours.

5. The method for preparing a zirconium-based amorphous MOF film as described in claim 4, characterized in that: The porous polymer substrate is polyethersulfone.

6. A zirconium-based amorphous MOF membrane, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 5.

7. The application of the zirconium-based amorphous MOF membrane according to claim 6 in membrane separation, characterized in that: It is used in nanofiltration separation of organic solvents, gas separation, or ion separation.

8. The application of a zirconium-based amorphous MOF membrane as described in claim 7 in membrane separation, characterized in that: It is used in nanofiltration separation of organic solvents.

9. The application of a zirconium-based amorphous MOF membrane as described in claim 8 in membrane separation, characterized in that: It is used for the separation of dye molecules in ethanol solvent.

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