Mxene-based organic-inorganic composite hollow fiber membrane, and preparation method and application thereof

Abstract

The application provides an MXene-based organic-inorganic composite hollow fiber membrane and a preparation method and application thereof, a casting solution of the organic-inorganic composite hollow fiber membrane comprises an organic polymer, a pore-forming agent, MXene and a solvent, the mass percentage content M% of the MXene in the casting solution is 0.5% to 7.5%, and the mass percentage content P% of the organic polymer in the casting solution is 15% to 25%. The MXene and the organic polymer are compounded in a specific ratio, the obtained hollow fiber membrane has good gas permeability, mechanical strength and pressure resistance, and in particular, has high oxygen-nitrogen separation selectivity, and has a good application prospect in the fields of air separation, nitrogen enrichment, oxygen enrichment, helium preparation from natural gas and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of membrane separation technology, and in particular to an organic-inorganic composite hollow fiber membrane based on MXene and a preparation method and application thereof. BACKGROUND

[0002] Membrane separation technology has the advantages of no phase change, low energy consumption, safe operation, etc., and is a green and sustainable development technology with wide application prospects. Among them, hollow fiber membrane is a kind of efficient gas separation technology, which can realize the selective separation of different gas molecules by using special membrane materials and structural design. The characteristics of this kind of membrane are hollow fiber structure, which can realize the separation of different gases under certain pressure difference according to the size and properties of gas molecules, and is widely used in petroleum chemical industry, engine, coal mine, medical treatment and other important fields of national economy.

[0003] Generally, hollow fiber membranes require gas permeability, mechanical strength, pressure resistance, bending resistance and other properties. However, the existing hollow fiber membranes have the problems of high permeability and high selectivity, poor uniformity, etc., and it is difficult to simultaneously consider the above-mentioned properties, which limits the large-scale commercialization. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides an organic-inorganic composite hollow fiber membrane based on MXene and a preparation method and application thereof.

[0005] In a first aspect, the present application provides an organic-inorganic composite hollow fiber membrane, the casting solution of which comprises an organic polymer, a pore former, MXene and a solvent, the mass percentage content M% of the MXene in the casting solution is 0.5% to 7.5%, and the mass percentage content P% of the organic polymer in the casting solution is 15% to 25%.

[0006] MXene is a new type of two-dimensional material, which is a transition metal carbon(nitrogen) compound, and its chemical formula is M n+1 X n T X , wherein M is an early transition metal, such as titanium, vanadium, chromium, manganese, etc., X is carbon or (and) nitrogen, n is an integer 1, 2, 3, etc., T X represents its surface functional group, such as common MXene titanium carbide, niobium carbide, vanadium carbide, chromium carbide, titanium nitride, vanadium nitride, niobium nitride, chromium nitride, titanium carbonitride, niobium carbonitride, vanadium carbonitride, chromium carbonitride, titanium niobium carbide, vanadium chromium carbide (such as Ti3C2Tx, Ti2CTx, Nb2CTx, V2CTx, (Ti 0.5 ,Nb 0.5 )2CTx, (V 0.5,Cr 0.5 MXene (e.g., 3C2Tx, Ti3CNTx, Ta4C3Tx) possesses high conductivity and chemical stability, and is currently widely used in lithium / sodium-ion batteries, supercapacitors, and flat-sheet membrane materials. It is also used as a catalyst, exhibiting excellent performance in electrocatalytic water splitting and hydrogen evolution reactions. However, its application in integrated hollow fiber membranes is currently lacking. This invention discovers that adding MXene to the casting solution and co-producing it with organic polymers creates an organic-inorganic composite hollow fiber membrane. This composite hollow fiber membrane combines excellent gas permeability, mechanical strength, and pressure resistance.

[0007] According to the organic-inorganic composite hollow fiber membrane provided by the present invention, the maximum transverse dimension L (μm) and thickness d (nm) of the MXene also satisfy the following condition with respect to M and P: M / P = X * L / d, where X is a correction coefficient ranging from 0.02 to 0.25. The MXene described in this invention is not particularly limited and can be selected from one or more of the aforementioned common MXenes. The maximum transverse dimension refers to the maximum dimension in the horizontal direction perpendicular to the thickness direction.

[0008] The organic-inorganic composite hollow fiber membrane provided by the present invention comprises an organic polymer selected from one or more of polysulfone, polyethersulfone, polyimide, polyetheretherketone, and polyaryletherketone. Preferably, the number average molecular weight of the organic polymer is 50,000-80,000.

[0009] The organic-inorganic composite hollow fiber membrane provided by the present invention uses a solvent selected from one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide mixed with water.

[0010] According to the organic-inorganic composite hollow fiber membrane provided by the present invention, the pore-forming agent is selected from one or more of polyethylene glycol and polyvinyl alcohol, and the mass percentage of the pore-forming agent in the casting solution is 2% to 5%.

[0011] The organic-inorganic composite hollow fiber membrane of the present invention has an outer diameter of 0.25-0.38 mm and a wall thickness of 0.06-0.10 mm.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned organic-inorganic composite hollow fiber membrane.

[0013] The preparation method provided by this invention includes the following steps:

[0014] (1) Mix the raw materials of the casting solution, and obtain the casting solution after heating, stirring and vacuum degassing;

[0015] (2) The obtained casting solution is added to a pressure tank, the spinning head is connected, and the air compressor is used to extrude the film under a certain spinning pressure P0. The hollow fiber membrane preform is obtained by wet spinning process.

[0016] In the wet spinning process, the core liquid is a mixture of solvent A and solvent B, the core liquid temperature is T1, and the core liquid pressure is P;

[0017] (3) The obtained hollow fiber membrane blank is sequentially passed through an air layer and a coagulation bath to obtain a hollow fiber membrane filament; wherein the air layer gap is L, the coagulation bath is a mixture of solvent A and solvent B, the coagulation bath temperature is T2, and the coagulation bath depth is H;

[0018] (4) After the obtained hollow fiber membrane filament is collected, it is immersed in solvent C for solvent replacement, the replacement time is t, and then dried at a temperature T3.

[0019] Further, the solvent A is at least one of methanol, ethanol, n-butanol, and isobutanol, the solvent B is at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide; the core liquid temperature T1 is 30-60℃, the core liquid pressure P is 0.03-0.06 MPa; and the spinning pressure P0 is 0.5-1 MPa.

[0020] Further, the air layer gap L is in the range of 10-30 cm, the coagulation bath temperature T2 is 60-90℃, and the coagulation bath depth H is in the range of 40-120 cm.

[0021] Further, the solvent C is one or more of ethanol, n-hexane, n-heptane, and glycerol aqueous solution, the temperature T3 is in the range of 60-100℃, and the replacement time t satisfies t=Z*H / L, wherein Z is a correction coefficient in the range of 8-30.

[0022] In a third aspect, the application provides the use of the above-mentioned organic-inorganic composite hollow fiber membrane in gas separation. The organic-inorganic composite hollow fiber membrane of the application can be used for oxygen / nitrogen separation, helium / methane separation, hydrogen / carbon dioxide separation, etc.

[0023] Further, the hollow fiber membrane of the application has high oxygen / nitrogen separation selectivity and has good application prospects in the fields of air separation, nitrogen enrichment, oxygen enrichment, and helium production from natural gas, etc.

[0024] The application provides an organic-inorganic composite hollow fiber membrane based on MXene and a preparation method and application thereof. By compounding MXene and organic polymer at a specific ratio, the obtained hollow fiber membrane has good gas permeability, mechanical strength, and pressure resistance, and in particular has high oxygen / nitrogen separation selectivity, and has good application prospects in the fields of air separation, nitrogen enrichment, oxygen enrichment, and helium production from natural gas, etc. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A scanning electron microscope image of MXene nanosheets used in Example 1 of the present application;

[0026] Figure 2 A cross-sectional scanning electron microscope image of the MXene-based organic-inorganic composite hollow fiber membrane prepared in Example 1 of the present application, with a low-magnification image on the left and a high-magnification image on the right. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0028] If a specific technology or condition is not specified in the embodiments, it is performed according to the technology or condition described in the literature in the art or according to the product manual. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be purchased through a regular channel.

[0029] Example 1

[0030] This embodiment provides an organic-inorganic composite hollow fiber membrane, and the casting solution thereof is composed of the following components:

[0031] Organic polymer: polysulfone (number average molecular weight Mw is 50000), mass percentage is 15%;

[0032] Pore-forming agent: polyethylene glycol, mass percentage is 2%;

[0033] MXene: titanium carbide, L = 20 μm, D = 10 nm, the scanning electron microscope image thereof is shown in Figure 1 , mass percentage is 7.5%;

[0034] Solvent: a mixture of N,N-dimethylacetamide and water in a mass ratio of 10:1, mass percentage is 75.5%.

[0035] This embodiment also provides a preparation method of the above-mentioned organic-inorganic composite hollow fiber membrane, which comprises the following steps:

[0036] (1) mixing the organic polymer, pore-forming agent, MXene and solvent in a formula amount, and obtaining a casting solution after heating stirring and vacuum degassing;

[0037] (2) adding the obtained casting solution into a pressure tank, connecting a spinning head, and extruding under 0.5 MPa by using an air compressor to obtain a hollow fiber membrane green body by using a wet spinning process;

[0038] In the wet spinning process, the core liquid is a mixture of solvent A (methanol) and solvent B (N,N-dimethylacetamide) in a volume ratio of 1:1, the core liquid temperature T1 is 30°C, and the core liquid pressure P is 0.03 MPa;

[0039] (3) The obtained hollow fiber membrane blank is sequentially passed through an air layer and a coagulation bath to obtain a hollow fiber membrane filament; wherein the air layer gap L is 10 cm, the coagulation bath is a mixture of solvent A (methanol) and solvent B (N,N-dimethylacetamide) in a volume ratio of 1:1, the coagulation bath temperature T2 is 60°C, and the coagulation bath depth H is 40 cm;

[0040] (4) The obtained hollow fiber membrane filament is collected and immersed in solvent C (n-hexane) for solvent replacement, the replacement time t is 40 h, and then dried at a temperature T3 = 60°C.

[0041] The outer diameter of the organic-inorganic composite hollow fiber membrane obtained in this example is 0.25 mm, and the wall thickness is 0.06 mm. The cross-sectional scanning electron microscope image is shown in Figure 2 The left side is a low magnification image, and the right side is a high magnification image.

[0042] Example 2

[0043] This example provides an organic-inorganic composite hollow fiber membrane, and the casting solution thereof is as follows:

[0044] Organic polymer: polyether sulfone (number average molecular weight Mw is 80000), mass percentage content is 25%;

[0045] Pore-forming agent: polyethylene glycol, mass percentage content is 5%;

[0046] MXene: vanadium carbide, L = 1 pm, D = 1 nm, mass percentage content is 0.5%;

[0047] Solvent: a mixture of N,N-dimethylacetamide and water in a mass ratio of 10:1, mass percentage content is 69.5%.

[0048] This example also provides a preparation method of the above-mentioned organic-inorganic composite hollow fiber membrane, comprising the following steps:

[0049] (1) Mix the formula amount of organic polymer, pore-forming agent, MXene and solvent, heat and stir, and vacuum degassing to obtain a casting solution;

[0050] (2) Put the obtained casting solution into a pressure tank, connect a spinning head, use an air compressor to extrude at 1 MPa, and use a wet spinning process to obtain a hollow fiber membrane blank;

[0051] In the wet spinning process, the core liquid is a mixture of solvent A (n-butanol) and solvent B (N,N-dimethylformamide) in a volume ratio of 1:1, the core liquid temperature T1 is 60°C, and the core liquid pressure P is 0.06 MPa;

[0052] (3) The obtained hollow fiber membrane blank is sequentially passed through an air layer and a coagulation bath to obtain a hollow fiber membrane filament; wherein the air layer gap L is 30 cm, the coagulation bath is a mixture of solvent A (n-butanol) and solvent B (N,N-dimethylformamide) in a volume ratio of 1:1, the coagulation bath temperature T2 is 90°C, and the coagulation bath depth H is 120 cm;

[0053] (4) The obtained hollow fiber membrane filament is collected and immersed in solvent C (n-heptane) for solvent replacement, the replacement time t is 100 h, and then dried at a temperature T3 = 100°C.

[0054] The outer diameter of the organic-inorganic composite hollow fiber membrane obtained in this example is 0.33 mm, and the wall thickness is 0.10 mm.

[0055] Example 3

[0056] This example provides an organic-inorganic composite hollow fiber membrane, and the casting solution thereof is composed of:

[0057] Organic polymer: polysulfone (number average molecular weight Mw is 50000), polyaryletherketone (number average molecular weight Mw is 60000), mass ratio of 1:1, total mass percentage content is 20%;

[0058] Pore-forming agent: polyvinyl alcohol, mass percentage content is 4%;

[0059] MXene: niobium carbide, L = 10 μm, D = 5 nm, mass percentage content is 4%;

[0060] Solvent: a mixture of N,N-dimethylformamide and water in a mass ratio of 10:1, mass percentage content is 72%.

[0061] This example also provides a preparation method of the above-mentioned organic-inorganic composite hollow fiber membrane, comprising the following steps:

[0062] (1) Mix the formula amount of organic polymer, pore-forming agent, MXene and solvent, heat and stir, and vacuum degassing to obtain a casting solution;

[0063] (2) Put the obtained casting solution into a pressure tank, connect a spinning head, use an air compressor to extrude at 0.7 MPa, and use a wet spinning process to obtain a hollow fiber membrane blank;

[0064] In the wet spinning process, the core liquid is a mixture of solvent A (ethanol) and solvent B (dimethyl sulfoxide) in a volume ratio of 1:1, the core liquid temperature T1 is 45℃, and the core liquid pressure P is 0.05 MPa;

[0065] (3) The obtained hollow fiber membrane blank is sequentially passed through an air layer and a coagulation bath to obtain a hollow fiber membrane filament; wherein the air layer gap L is 20 cm, the coagulation bath is a mixture of solvent A (ethanol) and solvent B (dimethyl sulfoxide) in a volume ratio of 1:1, the coagulation bath temperature T2 is 75℃, and the coagulation bath depth H is 90 cm;

[0066] (4) After the obtained hollow fiber membrane filament is collected, it is immersed in solvent C (ethanol) for solvent replacement, the replacement time t is 80 h, and then dried at a temperature T3 = 80℃.

[0067] The outer diameter of the organic-inorganic composite hollow fiber membrane obtained in this example is 0.3 mm, and the wall thickness is 0.08 mm.

[0068] Example 4

[0069] This example provides an organic-inorganic composite hollow fiber membrane, and the casting solution thereof is composed of:

[0070] Organic polymer: polysulfone (number average molecular weight Mw is 50000), mass percentage content is 15%;

[0071] Pore-forming agent: polyethylene glycol, mass percentage content is 2%;

[0072] MXene: titanium carbide, L = 1 μm, D = 20 nm, mass percentage content is 7.5%;

[0073] Solvent: a mixture of N,N-dimethylacetamide and water in a mass ratio of 10:1, mass percentage content is 75.5%.

[0074] This example also provides a preparation method of the above-mentioned organic-inorganic composite hollow fiber membrane, comprising the following steps:

[0075] (1) Mix the formula amount of organic polymer, pore-forming agent, MXene and solvent, heat and stir, and vacuum degassing to obtain a casting solution;

[0076] (2) Put the obtained casting solution into a pressure tank, connect a spinning head, use an air compressor to extrude at 0.85 MPa, and use a wet spinning process to obtain a hollow fiber membrane blank;

[0077] In the wet spinning process, the core liquid is a mixture of solvent A (methanol) and solvent B (N,N-dimethylacetamide) in a volume ratio of 1:1, the core liquid temperature T1 is 30℃, and the core liquid pressure P is 0.03 MPa;

[0078] (3) The obtained hollow fiber membrane blank is sequentially passed through an air layer and a coagulation bath to obtain a hollow fiber membrane filament; wherein the air layer gap L is 10 cm, the coagulation bath is a mixture of solvent A (methanol) and solvent B (N,N-dimethylacetamide) in a volume ratio of 1:1, the coagulation bath temperature T2 is 60°C, and the coagulation bath depth H is 40 cm;

[0079] (4) The obtained hollow fiber membrane filament is collected and immersed in solvent C (n-hexane) for solvent replacement, the replacement time t is 40 h, and then dried at a temperature T3 = 60°C.

[0080] The outer diameter of the organic-inorganic composite hollow fiber membrane obtained in this example is 0.38 mm, and the wall thickness is 0.095 mm.

[0081] Comparative Example 1

[0082] This comparative example provides a hollow fiber membrane, which is different from Example 1 in that the casting solution does not contain MXene, and the amounts of organic polymer, pore-forming agent and solvent are proportionally enlarged so that the total is 100%.

[0083] Comparative Example 2

[0084] This comparative example provides a hollow fiber membrane, which is different from Example 1 in that the MXene is replaced by ceramic particles with an average particle size of 10 nm.

[0085] Performance test

[0086] The hollow fiber membranes obtained in each example and comparative example are respectively tested in terms of gas permeability, mechanical strength and pressure resistance.

[0087] The test method is as follows:

[0088] Gas separation performance: The prepared hollow fiber membrane filament is sealed with epoxy resin, and gas separation performance test is performed using gas chromatography.

[0089] Pressure resistance test: One end of the prepared hollow fiber membrane filament is sealed, and the other end is connected to high-pressure gas, and the pressure resistance performance is tested. When the filament can maintain 30 min without damage under a certain pressure, the pressure at this time is determined as the pressure resistance.

[0090] Mechanical strength test: The prepared hollow fiber membrane filament is cut to a certain length, and the mechanical tensile property test is performed using a universal testing machine.

[0091] The test results are as follows:

[0092]

[0093] From the above results, it can be seen that the organic-inorganic composite hollow fiber membrane prepared in the embodiments has good oxygen / nitrogen selectivity, mechanical strength and pressure resistance, and embodiments 1-3 are more superior than embodiment 4.

[0094] It should be noted that the endpoints of the ranges and any values disclosed in this document are not limited to the precise values stated. The ranges and values should be interpreted as approximately between the stated values. For numeric values, the endpoints of each range, the endpoints of each range and individual point values, and individual point values can be combined with each other to form one or more new numeric ranges, which should be considered as specifically disclosed herein.

[0095] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", or "some specific embodiments" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the description of the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0096] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An organic-inorganic composite hollow fiber membrane, characterized by, The casting solution of the organic-inorganic composite hollow fiber membrane comprises an organic polymer, a pore-forming agent, MXene, and a solvent, the mass percentage content M% of the MXene in the casting solution is 0.5% to 7.5%, and the mass percentage content P% of the organic polymer in the casting solution is 15% to 25%; The MXene has a maximum transverse size L of microns, a thickness d of nanometers, and M and P satisfy: M / P=X*L / d, wherein X is a correction factor, and the range of X is 0.02 to 0.25; The pore-forming agent is selected from one or more of polyethylene glycol and polyvinyl alcohol, and the mass percentage content of the pore-forming agent in the casting solution is 2% to 5%; the organic-inorganic composite hollow fiber membrane has an outer diameter of 0.25 to 0.38 mm and a wall thickness of 0.06 to 0.10 mm.

2. The organic-inorganic composite hollow fiber membrane according to claim 1, characterized by, The organic polymer is selected from one or more of polysulfone, polyethersulfone, polyimide, polyether ether ketone, and polyaryletherketone.

3. The organic-inorganic composite hollow fiber membrane according to claim 1 or 2, characterized by, The solvent is a mixture of one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide and water.

4. The method for producing an organic-inorganic composite hollow fiber membrane according to any one of claims 1 to 3, characterized by, The method comprises the following steps: (1) mixing raw materials of the casting solution, and obtaining the casting solution after heating, stirring, and vacuum degassing; (2) adding the obtained casting solution into a pressure tank, connecting a spinning head, extruding under a certain spinning pressure P0 by using an air compressor, and obtaining a hollow fiber membrane green body by using a wet spinning process; In the wet spinning process, the core liquid is a mixture of solvent A and solvent B, the core liquid temperature is T1, and the core liquid pressure is P; (3) sequentially passing the obtained hollow fiber membrane green body through an air layer and a coagulation bath to obtain a hollow fiber membrane yarn; wherein the air layer gap is L, the coagulation bath is a mixture of solvent A and solvent B, the coagulation bath temperature is T2, and the coagulation bath depth is H; (4) collecting the obtained hollow fiber membrane yarn, immersing it in solvent C for solvent replacement for t hours, and then drying at a temperature T3; The solvent A is at least one of methanol, ethanol, n-butanol, and isobutanol, the solvent B is at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide, the core liquid temperature T1 is 30°C to 60°C, and the core liquid pressure P is 0.03 MPa to 0.06 MPa; the spinning pressure P0 is 0.5 to 1 MPa; The air layer gap L is 10 cm to 30 cm, the coagulation bath temperature T2 is 60°C to 90°C, and the coagulation bath depth H is 40 cm to 120 cm; The solvent C is one or more of ethanol, n-hexane, n-heptane, and a glycerol aqueous solution, the temperature T3 is 60°C to 100°C, and the replacement time t satisfies: t=Z*H / L, wherein Z is a correction factor, and the range of Z is 8 to 30.

5. Application of the organic-inorganic composite hollow fiber membrane in gas separation.

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