Mof-loaded hollow fiber membrane composite membrane, method of making and use thereof

Abstract

The application discloses a MOFs loaded hollow fiber membrane composite membrane, a preparation method and application thereof, and belongs to the technical field of porous membrane preparation. The specific method is as follows: (1) placing the cleaned hollow fiber membrane and polyethylene imine in water, uniformly mixing, and then placing in a hydrothermal reaction kettle, heating to 100-150 DEG C, and reacting for 5-72 hours; the product after the reaction is completed is washed and dried to obtain an ammoniated hollow fiber membrane; (2) immersing the ammoniated hollow fiber membrane in a metal organic framework material precursor solution, and carrying out a loading reaction for 1-48 hours under a suitable reaction temperature; taking out the composite membrane after the reaction, washing and drying to obtain a metal organic framework material loaded hollow fiber membrane composite membrane. The ammoniated modification treatment of the hollow fiber membrane is carried out by introducing the polyethylene imine with high branching degree, and the branched polyethylene imine can be used for wrapping, complexing and stabilizing the metal organic framework material. The prepared composite membrane can be used for gas adsorption or gas separation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of porous membrane preparation, and particularly relates to a MOFs loaded hollow fiber membrane composite membrane, a preparation method and application thereof. BACKGROUND

[0002] Gas separation technology is a technology for separating each component in a mixed gas. Compared with traditional separation technology with high energy consumption and high cost, membrane separation technology of mixed gas has been widely concerned since its advent, and is applied more and more in the fields of energy, chemical production, environment and the like. However, the gas separation performance of a polymer thin film is restricted by two parameters of permeability and selectivity.

[0003] As a new type of nanomaterial, metal organic framework (MOFs) has a wide application prospect in the field of gas separation membrane due to many advantages such as adjustable structure, accurate pore size, controllable chemical function and large specific surface area. MOF membranes with high flux and good gas selectivity can maximize the economic and technical advantages of the membranes. However, MOFs are difficult to be processed by traditional solvent or thermal technology, and the existing methods are mostly used for preparing MOF membranes on a rigid inorganic substrate. In order to break through the technical bottleneck of large-scale membrane preparation difficulty and poor flexibility of membrane module processing and manufacturing, it is a key scientific research problem to prepare a composite membrane material by taking a flexible polymer as a substrate.

[0004] Hollow fiber membrane is a membrane with a self-supporting structure and a fiber shape, has a large packing density per unit volume, a large specific surface area, low cost, a simple preparation process, flexibility and processability, and is a good substrate for preparing a gas separation composite membrane material. However, the composite membrane material prepared by an in-situ growth method generally has problems such as agglomeration of nanofillers and phase separation of nanometer particles-polymer, which leads to poor membrane performance, poor continuity and poor permeability. Therefore, it is of great significance to solve the problem of surface interface combination between the MOF layer and the hollow fiber membrane substrate and to develop a general preparation method of a MOFs loaded hollow fiber membrane composite membrane. SUMMARY

[0005] The application aims at the deficiencies in the prior art and provides a MOFs loaded hollow fiber membrane composite membrane, a preparation method and application thereof.

[0006] The specific technical scheme adopted by the application is as follows:

[0007] In a first aspect, the application provides a preparation method of a MOFs loaded hollow fiber membrane composite membrane, and specifically as follows: soaking an ammoniated hollow fiber membrane in a metal organic framework precursor solution, carrying out a loading reaction for 1-48 hours at a suitable reaction temperature; taking out the composite membrane after the reaction, and obtaining a metal organic framework loaded hollow fiber membrane composite membrane after cleaning and drying;

[0008] The aminated hollow fiber membrane is prepared by using polyethyleneimine, and the preparation method is as follows: the cleaned hollow fiber membrane and polyethyleneimine are mixed in water, and then the mixture is placed in a hydrothermal reactor and heated to 100-150 DEG C for 5-72 hours; the product after the reaction is completed is washed and dried to obtain the aminated hollow fiber membrane.

[0009] Preferably, the hollow fiber membrane is a polyvinylidene fluoride hollow fiber microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane or a high filtration membrane.

[0010] Preferably, the polyethyleneimine is branched polyethyleneimine with a molecular weight distribution of 600-20000 g / mol.

[0011] Preferably, the mass ratio of the hollow fiber membrane, polyethyleneimine and water is 1:(2.5-10):(10-50).

[0012] Preferably, when the metal-organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane is prepared, the metal-organic framework material precursor solution is prepared as follows: aluminum hydroxide is dissolved in formic acid to obtain a mixed solution, wherein the concentration of aluminum hydroxide is 7-10 g / L; the loading reaction is controlled at a temperature of 80-150 DEG C.

[0013] Preferably, when the metal-organic framework ZIF-8 loaded hollow fiber membrane composite membrane is prepared, the metal-organic framework material precursor solution is prepared as follows: zinc nitrate is dissolved in methanol, and then 2-methylimidazole is added to obtain a mixed solution; the concentration ratio of zinc nitrate and 2-methylimidazole in the mixed solution is (1-3):3; the loading reaction is controlled at a temperature of 20-30 DEG C.

[0014] Preferably, when the metal-organic framework UiO-66 loaded hollow fiber membrane composite membrane is prepared, the metal-organic framework material precursor solution is prepared as follows: zirconium tetrachloride and 1,4-benzenedicarboxylic acid are dissolved in dimethylacetamide to obtain a mixed solution; then an acetic acid solution is added to control the mixed solution to be acidic; the concentration ratio of zirconium tetrachloride and 1,4-benzenedicarboxylic acid in the mixed solution is (7-10):7.

[0015] Preferably, the composite membrane after the reaction is ultrasonically cleaned in methanol or N,N-dimethylformamide solvent for 1-3 minutes, and then washed, soaked and dried with ethanol to obtain the metal-organic framework material loaded hollow fiber membrane composite membrane.

[0016] In a second aspect, the application provides a MOFs loaded hollow fiber membrane composite membrane prepared by the preparation method of the first aspect.

[0017] In a third aspect, the present application provides a use of the MOFs loaded hollow fiber membrane composite membrane in the second aspect in gas separation.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] (1) The substrate used in the present application is a polyvinylidene fluoride hollow fiber membrane substrate, which has the advantages of flexibility, self-supporting, low cost, simple preparation process, etc., and is suitable for use as a general substrate material for preparing composite membrane materials. The stability and specific surface area of the hollow fiber membrane material prepared according to the embodiment after amination of polyethyleneimine are improved, and a large number of long carbon chains and amino groups grafted on the surface of the hollow fiber membrane can provide sites for the continuous growth of MOFs.

[0020] (2) The pore space formed by the branched polyethyleneimine on the surface of the hollow fiber membrane can also be used to wrap, complex and stabilize the metal organic framework material. The MOFs loaded hollow fiber membrane composite membrane prepared by the present application solves the problem of interfacial bonding between the MOF layer and the polymer substrate, and improves the stability of the composite membrane material.

[0021] (3) The preparation method provided by the present application is simple to operate, easy to scale up, and suitable for loading various metal organic framework materials on hollow fiber membranes. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Surface scanning electron microscope image (a) and cross-sectional scanning electron microscope image (b) of the hollow fiber membrane after amination of polyethyleneimine prepared in Example 1;

[0023] Figure 2 Surface scanning electron microscope image of the metal organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane prepared in Example 1;

[0024] Figure 3 Nitrogen isothermal adsorption-desorption curve of the metal organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane prepared in Example 1;

[0025] Figure 4 Surface scanning electron microscope image of the metal organic framework ZIF-8 loaded hollow fiber membrane composite membrane prepared in Example 2;

[0026] Figure 5 Surface scanning electron microscope image of the metal organic framework UiO-66 loaded hollow fiber membrane composite membrane prepared in Example 3.

[0027] Figure 6 Surface scanning electron microscope image of the metal organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane prepared in the comparative example; DETAILED DESCRIPTION

[0028] The present application will be further described and explained with reference to the drawings and specific embodiments. The technical features of each embodiment of the present application can be combined with each other without conflict, as long as they are applicable.

[0029] Example 1

[0030] This embodiment provides a metal-organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane, and the specific preparation method is as follows:

[0031] (1) Preparation of the hollow fiber membrane after polyethyleneimine amination:

[0032] The polyvinylidene fluoride hollow microfiltration fiber membrane was washed with deionized water and dried at room temperature. 1.00 g of the washed polyvinylidene fluoride hollow fiber membrane, 2.50 g of branched polyethyleneimine with a molecular weight of 600 g / mol, and 10 ml of deionized water were placed in an autoclave, heated to 120℃ for 24 h, and the product after the reaction was washed with deionized water and dried to obtain the hollow fiber membrane after polyethyleneimine amination.

[0033] (2) Preparation of the metal-organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane:

[0034] 0.40 g of aluminum hydroxide and 56 ml of formic acid were weighed and stirred in a reaction bottle at room temperature to prepare a clear Al(HCOO)3 metal-organic framework precursor solution.

[0035] The hollow fiber membrane after polyethyleneimine amination prepared in step (1) was immersed in the above Al(HCOO)3 metal-organic framework precursor solution, and the mixed solution was heated to 100℃ and stirred for 48 hours. The composite membrane after the reaction was taken out, washed with methanol or N,N-dimethylformamide solvent for 1-3 minutes by ultrasonic cleaning, then washed and soaked with ethanol, and dried in a vacuum drying oven at 60℃ to obtain the metal-organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane.

[0036] Figure 1 (a) and Figure 1 (b) are the scanning electron microscope images and cross-sectional scanning electron microscope images of the hollow fiber membrane after polyethyleneimine amination prepared in this embodiment. According to Figure 1 As can be seen from (a), dense polyethyleneimine particles appear on the surface of the hollow fiber membrane after polyethyleneimine amination, according to Figure 1 As can be seen from (b), the hollow fiber membrane still maintains a good self-supporting structure.

[0037] Figure 2The scanning electron microscope image of the hollow fiber membrane composite membrane supported by the metal-organic framework Al(HCOO)3 prepared in this embodiment shows that the Al(HCOO)3 metal-organic framework is firmly wrapped in polyethyleneimine.

[0038] Nitrogen adsorption tests were performed on the metal-organic framework Al(HCOO)3-supported hollow fiber membrane composite membrane prepared in Example 1. The results are as follows: Figure 3 As shown.

[0039] from Figure 3 As can be seen from the data, the desorption curve of the hollow fiber membrane composite supported by Al(HCOO)3 metal-organic framework material is very close to the adsorption curve, proving that the adsorption process is reversible under all circumstances, indicating that the hollow fiber membrane composite supported by Al(HCOO)3 metal-organic framework material has a very good gas permeability.

[0040] Compared to hollow fiber membranes, the composite membrane material forms a thinner Al(HCOO)3 metal-organic framework film on the surface of the hollow fiber membrane. This structure is beneficial for gas permeation and gas adsorption. At the same time, the hollow fiber membrane can provide attachment sites for Al(HCOO)3, providing a more easily processed means for metal-organic framework materials with precise pore structures and gas adsorption and separation potential that are difficult to process.

[0041] Example 2

[0042] This embodiment provides a metal-organic framework ZIF-8 supported hollow fiber membrane composite membrane, and the specific preparation method is as follows:

[0043] 0.30 g of zinc nitrate was added to 11.3 mL of methanol, and then 660 mg of 2-methylimidazole was added to the methanol solution to prepare the ZIF-8 metal-organic framework precursor solution.

[0044] The hollow fiber membrane after polyethyleneimine amination prepared in step (1) of Example 1 was immersed in the above ZIF-8 metal-organic framework precursor solution and stirred at room temperature (25°C) for 1 hour. The composite membrane after reaction was taken out, ultrasonically cleaned in methanol or N,N-dimethylformamide solvent for 1 to 3 minutes, then cleaned and immersed in ethanol, and dried in a vacuum drying oven at 60°C to obtain the metal-organic framework ZIF-8 supported hollow fiber membrane composite membrane.

[0045] Figure 4 The scanning electron microscope image of the hollow fiber membrane composite membrane loaded with ZIF-8 metal-organic framework prepared in this embodiment shows that the ZIF-8 metal-organic framework is firmly wrapped in polyethyleneimine.

[0046] Example 3

[0047] The present embodiment provides a kind of metal organic framework UiO-66 loaded hollow fiber membrane composite membrane, specific preparation method is as follows:

[0048] 0.30g ZrCl4 and 0.21g 1,4-benzenedicarboxylic acid are dissolved in 10mL DMF. Then, 2.25mL acetic acid and 0.15mL deionized water are added to the above solution under stirring to prepare a UiO-66 metal organic framework precursor solution.

[0049] The polyethyleneimine-ammoniated hollow fiber membrane prepared in step (1) of Example 1 is immersed in the above-mentioned UiO-66 metal organic framework precursor solution, and the mixed solution is transferred to a Teflon-lined high-pressure reaction kettle (20mL). The reaction kettle is kept at 120℃ for 24 hours. After cooling to room temperature, the reacted composite membrane is taken out, ultrasonically cleaned in methanol or N,N-dimethylformamide solvent for 1-3 minutes, then washed and soaked with ethanol, and dried in a vacuum drying oven at 60℃ to obtain a metal organic framework UiO-66 loaded hollow fiber membrane composite membrane.

[0050] Figure 5 The surface scanning electron microscope image of the metal organic framework UiO-66 loaded hollow fiber membrane composite membrane prepared in the present embodiment can be seen that the UiO-66 metal organic framework is tightly wrapped in the polyethyleneimine.

[0051] Comparative Example

[0052] 0.40g aluminum hydroxide and 56ml formic acid are weighed and stirred at room temperature in a reaction bottle to prepare a clear Al(HCOO)3 metal organic framework precursor solution. The untreated hollow fiber membrane is immersed therein, and heated and stirred at 100℃ for 48h. The reacted composite membrane is taken out, washed and soaked with deionized water, and then placed in a vacuum oven and kept at 60℃ for drying to obtain a metal organic framework Al(HCOO)3 loaded untreated hollow fiber membrane composite membrane.

[0053] Figure 6 The surface scanning electron microscope image of the metal organic framework Al(HCOO)3 loaded untreated hollow fiber membrane composite membrane prepared in the present comparative example can be seen that a layer of extremely uneven and discontinuous Al(HCOO)3 metal organic framework material film is formed on the hollow fiber membrane without polyethyleneimine ammoniation, which is due to the lack of uniform adhesion sites between the hollow fiber membrane without polyethyleneimine ammoniation and the Al(HCOO)3 metal organic framework material, and the hollow fiber membrane in the comparative example has no fixation effect on Al(HCOO)3, which leads to the easy falling off of Al(HCOO)3 from the hollow fiber membrane. Such discontinuous and uneven hollow fiber composite membrane will seriously hinder the gas permeation.

[0054] According to the above examples and comparative examples, it is illustrated that the metal organic framework material loaded hollow fiber membrane composite membrane prepared by the method provided by the present application can be applied to gas separation. The method for applying the metal organic framework material loaded hollow fiber membrane composite membrane to the field of gas separation is not particularly limited in the present application, and a method well known to those skilled in the art can be selected.

[0055] The above-described examples are only a preferred scheme of the present application, and are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical scheme obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A method for preparing a MOFs-loaded hollow fiber membrane composite membrane, characterized in that, Specifically as follows: the aminated hollow fiber membrane is immersed in a metal organic framework material precursor solution, and a loading reaction is carried out at a suitable reaction temperature for 1-48 hours; the composite membrane after the reaction is taken out, washed and dried to obtain a metal organic framework material loaded hollow fiber membrane composite membrane; The aminated hollow fiber membrane is prepared by polyethyleneimine amination, and the specific preparation method is as follows: the cleaned hollow fiber membrane and polyethyleneimine are placed in water, mixed uniformly, and then placed in a hydrothermal reaction kettle, heated to 100-150 DEG C and reacted for 5-72 hours; the product after the reaction is washed and dried to obtain the aminated hollow fiber membrane. The polyethyleneimine is branched polyethyleneimine, and the molecular weight distribution is 600-20000 g / mol.

2. The process for the preparation of MOFs supported hollow fiber membrane composite membranes according to claim 1, characterized in that, The hollow fiber membrane is a polyvinylidene fluoride hollow fiber microfiltration membrane, an ultrafiltration membrane or a nanofiltration membrane.

3. The process for the preparation of MOFs supported hollow fiber membrane composite membranes according to claim 1, characterized in that, The mass ratio of the hollow fiber membrane, the polyethyleneimine and the water is 1: (2.5-10): (10-50).

4. The process for the preparation of MOFs supported hollow fiber membrane composite membranes according to claim 1, characterized in that, When the metal organic framework Al(HCOO)3 loaded hollow fiber membrane composite membrane is prepared, the metal organic framework material precursor solution is prepared as follows: aluminum hydroxide is dissolved in formic acid to obtain a mixed solution, wherein the concentration of aluminum hydroxide is 7-10 g / L; and the loading reaction is controlled at a temperature of 80-150 DEG C.

5. The process for the preparation of MOFs supported hollow fiber membrane composite membranes according to claim 1, characterized in that, When the metal organic framework ZIF-8 loaded hollow fiber membrane composite membrane is prepared, the metal organic framework material precursor solution is prepared as follows: zinc nitrate is dissolved in methanol, and then 2-methylimidazole is added to obtain a mixed solution; the concentration ratio of zinc nitrate and 2-methylimidazole in the mixed solution is (1-3): 3; and the loading reaction is controlled at a temperature of 20-30 DEG C.

6. The process for the preparation of MOFs supported hollow fiber membrane composite membranes according to claim 1, characterized in that, When the metal organic framework UiO-66 loaded hollow fiber membrane composite membrane is prepared, the metal organic framework material precursor solution is prepared as follows: zirconium tetrachloride and 1,4-benzenedicarboxylic acid are dissolved in dimethylacetamide to obtain a mixed solution; then an acetic acid solution is added to control the mixed solution to be acidic; the concentration ratio of zirconium tetrachloride and 1,4-benzenedicarboxylic acid in the mixed solution is (7-10):

7.

7. The process for the preparation of MOFs supported hollow fiber membrane composite membranes according to claim 1, characterized in that, The composite membrane after the reaction is ultrasonically cleaned in methanol or N,N-dimethylformamide solvent for 1-3 minutes, and then cleaned, soaked and dried with ethanol to obtain the metal organic framework material loaded hollow fiber membrane composite membrane.

8. A MOFs loaded hollow fiber membrane composite membrane prepared by any one of the preparation methods of claims 1-7.

9. Application of the MOFs loaded hollow fiber membrane composite membrane of claim 8 in gas separation.

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