A super-hydrophilic foam copper separation membrane and a super-hydrophobic foam copper separation membrane based on a two-dimensional MOF structure, and a preparation method and application thereof

Abstract

The application relates to an oil-water separation membrane, in particular to a super-hydrophilic foam copper separation membrane and a super-hydrophobic foam copper separation membrane based on a two-dimensional MOF structure and a preparation method and application thereof, and comprises the following steps: S1, foam copper pretreatment; S2, oxidation treatment; S3, synthesis of MOF@foam copper; and synthesis of PDMS@MOF@foam copper. Compared with the prior art, the application solves the problems that the foam copper prepared by electrochemical oxidation in the prior art is seriously chemically corroded, the recyclable rate is low, the foam copper prepared by electrodeposition or vapor modification has a complex process, high cost and low separation efficiency, the in-situ synthesis MOF method is used to realize the foam copper which is simple to operate, low in cost, good in stability, high in oil-water separation efficiency and recyclable.

Description

TECHNICAL FIELD

[0001] The application relates to an oil-water separation membrane, in particular to a super-hydrophilic foam copper separation membrane and a super-hydrophobic foam copper separation membrane based on a two-dimensional MOF structure and a preparation method and application thereof. BACKGROUND

[0002] The frequent occurrence of offshore oil spill accidents and the indiscriminate discharge of industrial oil-containing wastewater have caused huge economic losses and serious environmental pollution. It is reported that the annual discharge of oily wastewater in China is as high as 70 billion tons, containing lubricating oil, volatile phenol, lipids, organophosphorus compounds and other components, and has characteristics such as wide source, high difficulty in treatment, non-degradability and great harm. In addition, the rapid growth of population and economy leads to an increasing demand for clean water, especially in water resource shortage areas, and the demand for clean water is a big challenge to the current ecological environment. Therefore, how to effectively separate oil-water mixture has become a current research hotspot.

[0003] Common oil-water separation technologies include chemical flocculation, flotation, gravity separation, adsorption method, coalescence method and the like, but all have the disadvantages of low separation efficiency, high cost, secondary pollution and the like, which limit their wide application. Therefore, in order to better treat oil-containing wastewater, it is urgent to develop high-performance oil / water mixture separation technology.

[0004] In recent years, membrane separation technology based on special wetting materials is considered to be the most effective method for treating oil-water mixture due to its high separation performance, recyclability and excellent oil-water selectivity, and especially three-dimensional porous metal materials have a wide application prospect after oil-water separation without the need for mechanical treatment to absorb oil or water. Among them, foam copper is considered to be an ideal substrate because its surface is easy to produce ordered microstructure, thereby producing roughness and forming special wettability. For example, Chen prepared super-hydrophobic foam copper containing nanostructure by anodic oxidation and electrostatic assembly of carbon nanotubes, which is suitable for oil-water separation. Rong et al. prepared Cu3(PO4)2·H2O nanosheet coating using an in-situ self-sacrificial template method, and obtained super-hydrophobic foam copper after vapor modification. Hou et al. grew Cu-HHTP MOF structure on foam copper, and carried out hydrophobic modification with octadecanethiol, and the obtained foam copper was used for separating multiphase liquid.

[0005] At present, most of the researches adopt the method of electrochemical oxidation to rapidly construct array nanoneedle rough structure on the surface of foam copper, which effectively realizes oil-water separation, but the modified foam copper prepared has serious chemical corrosion, loses metal toughness, has low recyclability, cannot meet the needs of large-scale continuous separation in actual industrial production application, and the electro-deposition or vapor modification method is complicated to operate, has the disadvantages of complex process, high cost and low separation efficiency. SUMMARY

[0006] The present application aims to solve at least one of the above problems by providing a two-dimensional MOF structure-based super-hydrophilic foam copper separation membrane and a super-hydrophobic foam copper separation membrane, a preparation method and application, to solve the problems of severe chemical corrosion, low recyclability of foam copper prepared by electrochemical oxidation, complex process, high cost and low separation efficiency of foam copper prepared by electrodeposition or vapor modification.

[0007] The object of the present application is achieved by the following technical solutions:

[0008] The present application discloses a preparation method of a two-dimensional MOF structure-based super-hydrophilic foam copper separation membrane, comprising the following steps:

[0009] S1: Foam copper pretreatment: clean the foam copper to remove impurities and oxides on the surface, and dry it for later use;

[0010] S2: Oxidation treatment: place the foam copper treated in step S1 in a mixed solution of (NH4)2S2O8 and NaOH to grow Cu(OH)2 nanowires, and clean and remove unreacted components after the reaction is complete;

[0011] S3: Synthesis of MOF@foam copper: place the foam copper with Cu(OH)2 nanowires grown in step S2 in a ligand solution to react, obtain MOF@foam copper, and dry it after washing away the excess solution for later use;

[0012] The ligand solution is obtained by dissolving 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP) in a N,N-dimethylformamide (DMF) / water mixed solution.

[0013] Using HHTP as a monomer, MOF is directly synthesized on the surface of foam copper, which has super-hydrophilic properties and can be used as a "water removal type" separation membrane to quickly separate oil-water mixtures, and the method is simple and environmentally friendly.

[0014] Preferably, in step S1, the cleaning is performed by sequentially using 5-15wt% HCl (wt% is mass percentage), water, acetone and ethanol for 20-30min, and each cleaning is repeated at least 3 times.

[0015] Preferably, in step S2, the amount ratio of (NH4)2S2O8, NaOH and water in the mixed solution is 1-5g:5-20g:50-200mL; the reaction time is 1-2h; and the cleaning is performed by washing with water.

[0016] Preferably, in step S3, the ratio of 2,3,6,7,10,11-hexahydroxytriphenyl, N,N dimethylformamide and water in the ligand solution is 0.015-0.050 g: 5-20 mL: 50-200 mL; the ligand solution is mixed uniformly by ultrasonic for 10-30 min; the reaction condition is: normal temperature for 60-90 min; and the excess solution is removed by soaking in ethanol for 3-15 min.

[0017] The second aspect of the present application discloses a super-hydrophilic foam copper separation membrane based on a two-dimensional MOF structure, which is obtained by the preparation method described in any of the above, and the super-hydrophilic foam copper separation membrane (MOF@foam copper) has super-hydrophilicity and super-oleophobicity.

[0018] The third aspect of the present application discloses an application of the super-hydrophilic foam copper separation membrane based on a two-dimensional MOF structure described above in oil-water separation, and the MOF@foam copper separation membrane is applied to rapid "water-removing type" oil-water separation.

[0019] The fourth aspect of the present application discloses a preparation method of a super-hydrophobic foam copper separation membrane based on a two-dimensional MOF structure, comprising the following steps:

[0020] Synthesis of PDMS@MOF@foam copper: the MOF@foam copper is immersed in a reaction solution for reaction, and after being taken out, solidification and drying are performed;

[0021] The MOF@foam copper is prepared by any of the preparation methods described above, or the MOF@foam copper is selected from the super-hydrophilic foam copper separation membrane described above.

[0022] The reaction solution is obtained by dissolving polydimethylsiloxane (PDMS) and a curing agent (all kinds of conventional commercially available silane coupling agents can be used) in ethyl acetate.

[0023] The foam copper with super-hydrophobicity and super-oleophilicity can be prepared by coating PDMS modification on the surface of the hydrophilic foam copper, and the foam copper is used as an "oil-removing type" separation membrane to rapidly separate various oil-water mixtures.

[0024] Preferably, the ratio of polydimethylsiloxane, a curing agent and ethyl acetate in the reaction solution is 5-8 g: 0.5-0.8 g: 50-80 mL; and the reaction solution is mixed uniformly by ultrasonic for 10-30 min.

[0025] Preferably, the reaction condition is: temperature 60-120℃, time 1-2 h; and the solidification condition is: 80-100℃, time 1-2 h, so as to ensure complete solidification of PDMS.

[0026] The fifth aspect of the present application discloses a super-hydrophobic foam copper separation membrane based on two-dimensional MOF structure, which is obtained by the preparation method described in any of the above, and the super-hydrophobic foam copper separation membrane (PDMS@MOF@foam copper) has super-hydrophobic super-oleophilic property.

[0027] The sixth aspect of the present application discloses an application of the super-hydrophobic foam copper separation membrane based on two-dimensional MOF structure in oil-water separation, and the PDMS@MOF@foam copper separation membrane is applied to rapid 'oil-removing' oil-water separation.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The foam copper has the advantages of low price, environmental protection, excellent chemical stability and the like, and by in-situ synthesis of hydrophilic MOF structure on the surface and coating of polydimethylsiloxane, the chemical composition and nanostructure of the metal surface are adjusted and modified, so that the foam copper can obtain good super-hydrophilic super-oleophobic property or super-oleophilic super-hydrophobic property, and the membrane pollution is reduced. The hydrophilic foam copper is suitable for separating oil with a density smaller than water as a 'water-removing' separation membrane, and the hydrophobic foam copper can be used as an 'oil-removing' separation membrane, and the foam copper obtained by the method has important significance and application value for different density oils. Moreover, the separation process is carried out only under the action of gravity, and the required equipment and cost are simple, and the operation is convenient and feasible.

[0030] The super-hydrophobic foam copper formed by the method has a copper hydroxide nanowire-MOF nanowhisker hierarchical structure, and the in-situ manufacturing of the mushroom-shaped structure is conducive to the construction of the rough structure and the formation of a special wetting surface.

[0031] (1) The surface modification method and the required equipment are simple, low in cost, green and environmentally friendly, and short in time consumption;

[0032] (2) The MOF structure is conducive to improving the hydrophilicity and underwater oleophobicity of the separation membrane, the hydrophilic foam copper has a water droplet contact angle of 0° in air, and the separation effect of the 'water-removing' separation membrane on different oil-water mixtures reaches 99.1%, and the water flux is as high as 135.06 kL·m -2 ·h -1 .

[0033] (3) The PDMS hydrophobic foam copper separation membrane obtained finally has good separation efficiency for various oil-water mixtures (n-hexane, petroleum ether, cyclohexane, chloroform and kerosene), and the separation efficiency is more than 99.7%.

[0034] (4) The hydrophilic MOF@foam copper and the hydrophobic PDMS@MOF@foam copper have excellent recycling characteristics, and the separation effect on n-hexane still remains more than 99% after continuous separation for 20 times. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Synthetic scheme of the process;

[0036] Figure 2 Contact angle test diagram of the super-hydrophobic foam copper separation membrane prepared in Example 2;

[0037] Figure 3 Scanning electron microscope diagram of the foam copper, wherein (a) is a scanning electron microscope diagram of the original foam copper, (b) is a scanning electron microscope diagram of the foam copper treated by oxidation, (c) is a scanning electron microscope diagram of the MOF@foam copper, and (d) is a scanning electron microscope diagram of the PDMS@MOF@foam copper;

[0038] Figure 4 Oil-water separation performance test diagram of the hydrophilic MOF@foam copper, wherein (a) is the separation performance for different kinds of oil-water mixed liquids, and (b) is the cyclic separation performance for n-hexane-water mixed liquid;

[0039] Figure 5 Oil-water separation performance test diagram of the hydrophobic PDMS@MOF@foam copper, wherein (a) is the separation performance for different kinds of oil-water mixed liquids, and (b) is the cyclic separation performance for n-hexane-water mixed liquid. DETAILED DESCRIPTION

[0040] The application will be described in detail below with reference to the drawings and specific embodiments. The embodiments are implemented on the premise of the technical scheme of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples.

[0041] In the following examples, if not specifically stated, the reagents used are conventional commercially available reagents, and the methods used are conventional means in the art.

[0042] A modification method and application of a foam copper surface separation membrane based on a two-dimensional MOF structure for rapid oil-water separation, the method comprising the following steps:

[0043] S1: Foam copper pretreatment: the foam copper to be treated is sequentially cleaned in 5-15wt% HCl, water, acetone and ethanol for 20-30 minutes to remove impurities and oxides on the surface, and is dried for standby use.

[0044] S2: The pretreated foam copper is grown with Cu(OH)2nanowires in a good mixed solution of (NH4)2S2O8 and NaOH, after reaction for 1-2 hours, the sample is thoroughly washed with water to remove unreacted components, and the amount ratio of (NH4)2S2O8, NaOH and water is (1-5) g:(5-20) g:(50-200) mL.

[0045] S3: Synthesis of MOF@Cu: Dissolve 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP) powder in a mixed solution of N,N-dimethylformamide (DMF) and water, and ultrasonic for 20-30 minutes to obtain a uniformly mixed solution. Submerge the foam copper obtained in S2 in the solution at room temperature for 60-90 minutes. The mass or volume ratio of HHTP, DMF and water is (0.015-0.050) g:(5-20) mL:(50-200) mL. Uniform mixing means that the solution is a homogeneous phase dispersion liquid without solid precipitation. The separation membrane obtained after the reaction is called MOF@foam copper, and is soaked in ethanol for 3-15 minutes and dried for standby.

[0046] The separation membrane is a super-hydrophilic and super-oleophobic foam copper surface separation membrane based on a two-dimensional MOF structure, and is applied to rapid "water-removing type" oil-water separation.

[0047] A modification method and application of a foam copper surface separation membrane based on a two-dimensional MOF structure for rapid oil-water separation, the method comprising the following steps:

[0048] S1: Foam copper pretreatment: The foam copper to be treated is sequentially cleaned in 5-15 wt% HCl, water, acetone and ethanol for 20-30 minutes to remove impurities and oxides on the surface, and is dried for standby.

[0049] S2: Growth of Cu(OH)2 nanowires in a good mixed solution of (NH4)2S2O8 and NaOH after pretreatment of the foam copper, and the sample is washed with water to remove unreacted components after reaction for 1-2 hours. The amount ratio of (NH4)2S2O8, NaOH and water is (1-5) g:(5-20) g:(50-200) mL.

[0050] S3: Synthesis of MOF@Cu: Dissolve 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP) powder in a mixed solution of N,N-dimethylformamide (DMF) and water, and ultrasonic for 20-30 minutes to obtain a uniformly mixed solution. Submerge the foam copper obtained in S2 in the solution at room temperature for 60-90 minutes. The mass or volume ratio of HHTP, DMF and water is (0.015-0.050) g:(5-20) mL:(50-200) mL. Uniform mixing means that the solution is a homogeneous phase dispersion liquid without solid precipitation. The separation membrane obtained after the reaction is called MOF@foam copper, and is soaked in ethanol for 3-15 minutes and dried for standby.

[0051] S4: Synthesis of PDMS@MOF@foam copper: Dissolve polydimethylsiloxane (PDMS) and curing agent in ethyl acetate solution, ultrasonic for 10-30 minutes to obtain a uniformly mixed solution, the mass or volume ratio of PDMS, curing agent and ethyl acetate is (5-8) g:(0.5-0.8) g:(50-80) mL; immerse the MOF@foam copper obtained in S3 in the above solution, take out after sufficient reaction at 60-120℃ for 1-2 hours, then transfer the foam copper to an oven at 80-100℃ for 1-2 hours to ensure that the PDMS is completely cured. After drying, the superhydrophobic superoleophilic PDMS@MOF@foam copper separation membrane is obtained, which is used for rapid oil-water separation.

[0052] The separation membrane is a superhydrophobic superoleophilic foam copper surface separation membrane based on two-dimensional MOF structure, which is applied to rapid "oil removal type" oil-water separation.

[0053] As in the above steps, the adjustment of each parameter within the limited range obtains a separation membrane with similar performance, and appropriate adjustment and combination can be made to obtain a suitable scheme. The following examples 1-test example 1, example 2-test example 2 take two sets of data as examples for specific description and test.

[0054] Example 1

[0055] This example relates to the preparation of a foam copper surface separation membrane based on two-dimensional MOF structure with superhydrophilic superoleophobic properties, and the specific process is shown in Figure 1 S1-S3, which includes the following steps:

[0056] 1) Foam copper pretreatment: The foam copper to be treated is sequentially cleaned in 10wt% HCl, deionized water, acetone and ethanol for 20 minutes to remove impurities and oxides on the surface, and is dried for standby.

[0057] 2) The pretreated foam copper grows Cu(OH)2nanowires in a good mixed solution of (NH4)2S2O8and NaOH, reacts for 1 hour, then washes the sample thoroughly with deionized water to remove unreacted components, and the amount of (NH4)2S2O8, NaOH and water is 2.5g, 10g and 100mL respectively.

[0058] 3) Synthesis of MOF@Cu: Dissolve 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP) powder in a mixed solution of N,N-dimethylformamide (DMF) and deionized water, and ultrasonic for 20 minutes to obtain a uniformly mixed solution. Submerge the foam copper treated in step 2 in the solution at room temperature for 60 minutes. The mass or volume of HHTP, DMF and deionized water is 35 mg, 10 mL and 100 mL, respectively. Uniform mixing means that the solution is a homogeneous phase dispersion liquid without solid precipitation. The separation membrane obtained after the reaction is called MOF@foam copper, which is soaked in ethanol for 5 minutes and dried for standby.

[0059] 4) MOF@foam copper for oil-water separation process: configure 40 mL of oil-water mixed solution, and the volume ratio of oil and water is 1:1. Fix the superhydrophilic MOF@foam copper prepared and dried in step 3) in a self-made separation device, wet the membrane with 5 mL of deionized water first, then pour the oil-water mixed solution into the device, use a stopwatch to record the time required for water to completely permeate the membrane, and measure the mass of water before and after oil-water separation.

[0060] Example 2

[0061] This example relates to the preparation of a separation membrane based on a two-dimensional MOF structure, PDMS coated foam copper surface with superhydrophobic superoleophilic properties, and the specific process is shown in Figure 1 , which comprises the following steps:

[0062] In this example, steps 1)-3) are the same as in example 1.

[0063] 4) Synthesis of PDMS@MOF@foam copper: dissolve hydroxyl-terminated PDMS (Sylgard 184A) and curing agent (Sylgard 184B) in ethyl acetate solution, and ultrasonic for 10 minutes to obtain a uniformly mixed solution. The mass or volume of PDMS, curing agent and ethyl acetate is 5 g, 0.5 g and 50 mL, respectively. Submerge the foam copper treated in step 3) in the above solution and put it in a shaker. Set the shaker parameters to temperature 25°C and rotation speed 150 r / min. After 60 minutes of reaction, take out the foam copper, and then transfer it to an oven at 80°C for 1 hour to ensure complete curing of the PDMS. After drying, the superhydrophobic superoleophilic Cu-HHTP metal organic framework loaded foam copper separation membrane is obtained, which is used for rapid oil-water separation.

[0064] 5) Superhydrophobic and superoleophilic PDMS@MOF@copper foam for oil-water separation: Prepare a 40 mL oil-water mixture with a 1:1 volume ratio of oil to water. Fix the superhydrophobic PDMS@MOF@copper foam obtained in step 4) after preparation and drying in a self-made separation device. First, wet the membrane with 5 mL of oil, then pour in the oil-water mixture. Use a stopwatch to record the time required for the oil to completely permeate through the membrane, and measure the mass of water before and after oil-water separation.

[0065] The contact angle of the superhydrophobic copper foam prepared in Example 2 was tested, such as... Figure 2 As shown, the contact angle is 151.7°, indicating that the modified PDMS@MOF@copper foam has good hydrophobicity.

[0066] Scanning electron microscopy (SEM) tests were performed on the copper foam in each step of Examples 1 and 2, such as... Figure 3 As shown, (a) is a scanning electron microscope (SEM) image of the original untreated copper foam in Example 1; (b) is a scanning electron microscope (SEM) image of the copper foam after oxidation treatment in Example 1. It can be seen that a large number of copper hydroxide nanowires have grown on the oxidized copper foam, which are vertically arranged and intersecting each other, providing space for the subsequent growth of CuMOF; (c) is a scanning electron microscope (SEM) image of the MOF@copper foam synthesized in Example 1. There are mushroom-shaped structures with large heads on a single cylinder, which further constructs a rough structure, which is beneficial for building a superhydrophobic surface; (d) is a scanning electron microscope (SEM) image of the hydrophobic PDMS@MOF@copper foam obtained by modification in Example 2. The mushroom-shaped structure is covered by a soft polymer layer, but the introduction of PDMS does not affect the arrangement of copper hydroxide and MOF crystals.

[0067] Comparative Example

[0068] Using the same foamed copper as in Examples 1 and 2 and undergoing the pretreatment in step 1), the contact angle of the unmodified original foamed copper surface is almost 0. Water droplets quickly penetrate through it after being dropped on it, and it has the same wettability to both the oil and water phases, making it impossible to selectively separate the oil-water mixture.

[0069] Test Example 1

[0070] The MOF@foamed copper obtained in Example 1 was subjected to various oil-water mixture separation processes, as follows:

[0071] A mixture of n-hexane, petroleum ether, cyclohexane, chloroform, kerosene, and water was prepared sequentially, with 20 mL of each oil and 20 mL of water. Hexane, petroleum ether, cyclohexane, and kerosene are light oils and float on top of the water, while chloroform is a heavy oil and lies below the water. The MOF@copper foam prepared in Example 1 was fixed between two glass tubes. The membrane was first wetted with 10 mL of deionized water, and then the five oil-water mixtures were poured in sequentially for membrane separation. The water permeation time and the mass of water before and after oil-water separation were recorded. The separation results are shown below.Figure 4 The results are shown. Figure 4 (a) is the separation performance of the hydrophilic MOF@foam copper prepared in Example 1 for different types of oil-water mixtures, Figure 4 (b) is the cyclic separation performance of the separation membrane for n-hexane-water mixture.

[0072] Test Example 2

[0073] The superhydrophobic superoleophilic PDMS@MOF foam copper obtained in Example 2 above was subjected to separation of various oil-water mixtures and n-hexane cyclic separation test, and the steps were the same as in Test Example 1. Figure 5 (a) is the separation performance of the hydrophobic foam copper prepared in Example 2 for different types of oil-water mixtures, Figure 5 (b) is the cyclic separation performance of the separation membrane for n-hexane-water mixture.

[0074] The results show that:

[0075] The superhydrophilic foam copper surface separation membrane obtained by modification in Example 1 has good hydrophilic performance, with a water droplet contact angle of 0° in air, and good separation efficiency for various oil-water mixtures, with separation efficiencies of n-hexane, petroleum ether, cyclohexane, chloroform and kerosene mixtures being 99.80, 99.77, 99.54, 99.56, 99.45%, respectively, and water fluxes being 128.15±6.28, 125.81±9.67, 120.11±13.31, 62.11±2.95, 124.74±11.37 kL·m -2 ·h -1 respectively. The oil-water separation speed is fast, and the water content in the filtrate is low, with high selectivity. After 20 cycles of separation, the separation efficiency of the hydrophilic foam copper for n-hexane is maintained at 99.4%, indicating excellent cyclic use characteristics.

[0076] The foam copper modified in Example 2 has superhydrophobic superoleophilic properties, with a water droplet contact angle of 151.7° in air, and separation efficiencies of n-hexane, petroleum ether, cyclohexane, chloroform and kerosene mixtures being 99.88, 99.89, 99.80, 99.78, 99.77%, respectively, and water fluxes being 68.58±1.35, 60.27±3.81, 63.74±5.90, 106.23±4.18, 62.20±5.01 kL·m -2 ·h -1 respectively. The oil-water separation speed is fast, and the oil content in the filtrate is low, with high selectivity. After 20 cycles of separation, the separation efficiency of the hydrophobic foam copper for n-hexane is still 99.3%, with excellent cyclic use characteristics.

[0077] The foam copper based on the two-dimensional MOF structure has excellent hydrophilicity and underwater oleophobic wetting performance, and can be used as a "water-removing type" oil-water separation membrane; after coating with polydimethylsiloxane (PDMS), the foam copper has superhydrophobic and superoleophilic properties, and the transformation from hydrophilicity to hydrophobicity is completed, so that the foam copper can be used as an "oil-removing type" oil-water separation membrane. Therefore, by in-situ synthesizing the MOF structure on the foam copper and coating the polydimethylsiloxane for hydrophobic modification, various oil-water mixtures can be effectively separated, and good separation effects are obtained for light oil and heavy oil; the in-situ synthesis method has the advantages of simplicity, low cost and environmental protection; the foam copper surface separation membrane obtained after hydrophilic / hydrophobic modification can quickly and efficiently separate oil and water, solves the environmental problems caused by oil pollution, and the green and environmentally-friendly preparation technology meets the sustainable development goal, and has good economic and social benefits.

[0078] Compared with existing separation membranes, the present application not only has the advantages of excellent porosity and special wettability of metal organic framework, but also improves the hydrophobic and oleophilic performance of the membrane through polydimethylsiloxane modification, so that the separation of different types of oil-water mixtures is realized. In addition, the present application has the advantages of simple operation method, short process time, green environmental protection and low cost, and has broad application prospect.

[0079] The above description of the embodiments is for the purpose of facilitating the understanding and use of the present application by those skilled in the art. Those skilled in the art can easily make various modifications to the embodiments, and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art according to the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method for preparing a superhydrophilic copper foam separation membrane based on two-dimensional MOF structure, characterized in that, It comprises the following steps: S1: Foam copper pretreatment: clean the foam copper to remove impurities and oxides on the surface, and dry it for standby; S2: Oxidation treatment: place the foam copper treated in step S1 in a mixed solution of (NH4)2S2O8 and NaOH to grow Cu(OH)2 nanowires, and clean to remove unreacted components after the reaction is completed; S3: Synthesis of MOF@foam copper: place the foam copper with Cu(OH)2 nanowires grown in step S2 in a ligand solution to react, obtain MOF@foam copper, and dry after washing away the excess solution for standby; The ligand solution is obtained by dissolving 2,3,6,7,10,11-hexahydroxytriphenyl in a N,N-dimethylformamide / water mixed solution.

2. The method for preparing a superhydrophilic copper foam separation membrane based on two-dimensional MOF structure according to claim 1, characterized in that, In step S2, the amount ratio of (NH4)2S2O8, NaOH and water in the mixed solution is 1-5g:5-20g:50-200mL; and the reaction time is 1-2h.

3. The method of claim 1, wherein the method is characterized by: In step S3, the amount ratio of 2,3,6,7,10,11-hexahydroxytriphenyl, N,N-dimethylformamide and water in the ligand solution is 0.015-0.050g:5-20mL:50-200mL; the ligand solution is mixed uniformly by ultrasonic for 10-30min; and the reaction condition is that the reaction is carried out at normal temperature for 60-90min.

4. A two-dimensional MOF structure-based superhydrophilic copper foam separation membrane, characterized in that, The super-hydrophilic foam copper separation membrane based on the two-dimensional MOF structure obtained by the preparation method of any one of claims 1-3 has super-hydrophilicity and super-oleophobicity.

5. The application of the super-hydrophilic foam copper separation membrane based on the two-dimensional MOF structure in claim 4 in oil-water separation.

6. A method for preparing a superhydrophobic copper foam separation membrane based on two-dimensional MOF structure, characterized in that, It comprises the following steps: Synthesis of PDMS@MOF@foam copper: immerse the MOF@foam copper in a reaction solution to react, and take it out to solidify and dry; The MOF@foam copper is prepared by the preparation method of any one of claims 1-3, or the MOF@foam copper is selected from the super-hydrophilic foam copper separation membrane in claim 4; The reaction solution is obtained by dissolving polydimethylsiloxane and a curing agent in ethyl acetate.

7. The method of claim 6, wherein the method further comprises the step of: The amount ratio of polydimethylsiloxane, a curing agent and ethyl acetate in the reaction solution is 5-8g:0.5-0.8g:50-80mL; and the reaction solution is mixed uniformly by ultrasonic for 10-30min.

8. The method of claim 6, wherein the method is characterized by: The reaction condition is that the reaction is carried out at a temperature of 60-120℃ for 1-2h; and the solidification condition is that the solidification is carried out at a temperature of 80-100℃ for 1-2h.

9. A two-dimensional MOF structure-based superhydrophobic copper foam separation membrane, characterized in that, The super-hydrophobic foam copper separation membrane obtained by the preparation method of any one of claims 6-8 has super-hydrophobicity and super-oleophilicity.

10. The application of the super-hydrophobic foam copper separation membrane based on the two-dimensional MOF structure in claim 9 in oil-water separation.

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