A durable oil-water separation material and preparation method thereof

Abstract

This invention discloses a durable oil-water separation material and its preparation method, relating to the field of oil-water separation technology. The method includes the following steps: S1, cleaning and drying a metal substrate and a positive electrode; S2, preparing an electrolyte containing a metal salt, and using the metal substrate obtained in S1 as the negative electrode for electrodeposition; S3, mixing an organic ligand and a soluble metal additive in a solvent to prepare a metal-organic framework (MOF) precursor solution, then placing the electrodeposited metal substrate into the MOF precursor solution and performing a solvothermal reaction. After the reaction is complete, the durable oil-water separation material is obtained. The durable oil-water separation material provided by this invention has good reusability and durability, while also exhibiting high efficiency in oil-water separation.

Description

Technical Field

[0001] This invention relates to the field of oil-water separation technology, specifically to a durable oil-water separation material and its preparation method. Background Technology

[0002] With rapid industrialization, approximately 3.2 billion tons of oil enter water bodies globally each year, forming oily wastewater that seriously threatens human health. Oily wastewater mainly originates from oil extraction, oil processing, and machinery manufacturing. Current technologies for treating oily wastewater have some shortcomings, such as low treatment efficiency, secondary pollution, and poor antifouling performance, and further improvements are needed. Membrane separation technology is a widely recognized high-efficiency oil-water separation technology with advantages such as high separation efficiency, low chemical usage, simple operation, and excellent chemical and mechanical stability. Oil-water separation is a wetting behavior between phase interfaces, influenced by the wettability (hydrophobic, hydrophilic, or amphiphilic) of the membrane. The surface wettability of the membrane is affected by its chemical composition and surface microstructure. Inorganic porous metal membrane materials have significant advantages in mechanical properties, permeability, adsorption, and chemical characteristics. For example, stainless steel mesh (SSM) has advantages such as chemical corrosion resistance, high mechanical strength, high permeability, and large specific surface area, and is widely used in the field of oily wastewater treatment.

[0003] Metal-organic frameworks (MOFs) are widely used in gas storage, separation, sensing, and catalysis due to their advantages such as large pore size, adjustable pore size, large specific surface area, and abundant active sites. MOFs such as ZIF-67, ZIF-8, UiO-66, and HKUST-1 possess special wettability and ease of modification, and are widely used in the preparation of oil-water separation materials. MOFs are highly sensitive to water; hydrophobic MOFs can enhance material stability, while superhydrophilic MOFs can improve molecular diffusion. Studies have found that Zn / Zr bimetallic organic framework-modified cotton fabric oil-water separation materials exhibit superhydrophobicity, with a water contact angle of 161° and an oil-water separation efficiency greater than 98%. Obaid et al. prepared a superhydrophilic Cr-soc-MOF-1 membrane, which can achieve highly efficient treatment of oily wastewater (separation efficiency 99.9%; water flux 7.4 × 10⁻⁶). 3 L·m -2 ·h -1 However, the oil-water separation materials prepared by the aforementioned methods have poor mechanical and chemical stability, making it difficult to achieve long-term oil-water separation.

[0004] Studies have shown that electrochemically assisted methods can prepare continuous and stable coating materials on substrate materials to enhance their oil-water separation performance. Zou et al. deposited a superhydrophobic composite coating of ZIF-67 and 1-dodecyl mercaptan on a copper mesh using electrodeposition, achieving an oil-water separation efficiency of over 98% after modification. Chinese patent CN 201710122979.3 discloses a one-step electrodeposition method for preparing a superhydrophobic / oleophilic oil-water separation membrane. It uses a pretreated copper sheet and a metal mesh as the anode and cathode, respectively. Under constant current, ultrasonic electrodeposition is performed using a mixed solution containing nickel ion aqueous solution, long-chain alkyl thiol ethanol solution, and dopamine as the electrolyte. This yields a superhydrophobic / oleophilic oil-water separation membrane at the cathode. However, the membrane obtained by this patent exhibits poor durability and stability. Chinese patent CN201610180066.2 discloses a method for preparing a superhydrophilic oil-water separation membrane. It uses a conductive metal mesh as the cathode and nickel foil as the anode, uniformly loading Ni grains onto the conductive metal mesh. While the membrane obtained by this method has good oil-water separation performance, its durability is poor. Summary of the Invention

[0005] To address at least one of the aforementioned problems, this invention proposes a durable oil-water separation material and its preparation method. The prepared oil-water separation material exhibits high oil-water separation efficiency, good durability, and can be reused multiple times.

[0006] The technical solution of this invention is: a durable oil-water separation material, comprising the following steps:

[0007] S1. Clean and dry the metal substrate and the positive electrode; the metal elements contained in the metal substrate and the metal elements contained in the positive electrode are different;

[0008] S2. Prepare an electrolyte containing a metal salt, and use the metal substrate obtained in S1 as the negative electrode for electrodeposition; wherein the metal salt contains the same type of metal element as the positive electrode.

[0009] S3. The organic ligand and soluble metal additive are mixed in a solvent to prepare a metal-organic framework material precursor solution. Then, the electrodeposited metal substrate is placed in the metal-organic framework material precursor solution and subjected to a solvothermal reaction. After the reaction is completed, a durable oil-water separation material is obtained. The organic ligand is one of 2-aminoterephthalic acid, 2,5-dihydroxyterephthalic acid, terephthalic acid, and trimesic acid.

[0010] The durable oil-water separation material of this invention can be applied to the separation of conventional oil-water mixtures as well as the separation of oil-water emulsions. The difference lies in the mesh size of the metal substrate required for the separation of conventional oil-water mixtures, typically 200-1000 mesh. Under this mesh size condition, the durable oil-water separation material of this invention can effectively separate oil-water mixtures while ensuring a high water flux. Of course, in practical applications, metal substrates with higher mesh sizes can also be used for the separation of oil-water mixtures; however, the higher the mesh size, the lower the water flux. For oil-water emulsions, a relatively high mesh size of the metal substrate is required, typically set at 2000-2800 mesh.

[0011] In one embodiment of the present invention, in step S1, the cleaning and drying steps of the metal substrate and the positive electrode are as follows: the metal substrate and the positive electrode are ultrasonically washed sequentially with a dilute acid solution, a small molecule alcohol, and water, and then dried after washing. This cleaning process is mainly to remove oil, oxide layers, etc., from the surface of the metal substrate and the positive electrode, so as to improve the effect of subsequent electrodeposition.

[0012] Furthermore, the dilute acid solution is one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution with a concentration of 0.3~1.0M; the small molecule alcohol is one of methanol or ethanol.

[0013] In one embodiment of the present invention, in S1, the metal substrate is one of stainless steel wire mesh, iron mesh, copper mesh, titanium mesh, nickel mesh, copper foam, and iron foam, and the positive electrode is one of copper, iron, titanium, zirconium, and nickel; in S2, the metal salt is one of soluble copper salt, soluble iron salt, soluble titanium salt, soluble zirconium salt, and soluble nickel salt; in S3, the soluble metal additive is one of copper nitrate, zirconium chloride, ferric chloride, chromium nitrate, and bismuth nitrate.

[0014] In one embodiment of the present invention, in S2, the power source for electrodeposition is a constant voltage DC power source with a voltage of 2~5V and a time of 1~5min.

[0015] In one embodiment of the present invention, in step S2, the concentration of the metal salt is 0.5~1.5 mol / L.

[0016] In one embodiment of the present invention, in step S3, the molar ratio of the organic ligand to the soluble metal additive is 1:0.25~1.0; the concentration of the soluble metal additive is 2~18 mg / mL; and the solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, anhydrous ethanol, and anhydrous methanol, or a mixture of one of N,N-dimethylformamide, N,N-dimethylacetamide, anhydrous ethanol, and anhydrous methanol with water.

[0017] In one embodiment of the present invention, the temperature of the solvothermal reaction is 100~180℃, the electrodeposited metal substrate is immersed in the metal-organic framework material precursor solution, and the reaction time is 6~12h.

[0018] Another object of the present invention is to disclose a durable oil-water separation material, which is prepared by any of the methods described above. Beneficial effects

[0019] (1) The present invention uses a simple electrodeposition method to deposit a uniform and dense metal element layer on the substrate material. The metal element is oxidized into metal oxide through hydrothermal reaction. The unsaturated metal coordination sites promote the growth of MOF crystals by binding with the groups of organic ligand reagents of carboxylic acid or pyridine, forming an interlocked micro-nano structure of metal oxide and MOF. This stable and robust structure improves the durability of oil-water separation material. After multiple oil-water separation cycles and sandpaper abrasion, it still maintains excellent underwater superoleophobicity and high water flux, has good reusability and durability, and also has certain antibacterial properties.

[0020] (2) The oil-water separation material of the present invention has superhydrophilicity and underwater superoleophobicity. The contact angle of water in the air is close to 0° and the contact angle of oil underwater is greater than 150°. The separation performance of oily wastewater is higher than 98%.

[0021] (3) The oil-water separation material of the present invention has strong mechanical stability and antifouling performance. It can maintain superhydrophilic properties and efficient oil-water separation performance in strong acid, strong alkali, organic solvents, as well as in high temperature and low temperature environments. It is suitable for oily wastewater treatment in complex environments.

[0022] (4) Using the method of the present invention, the base material can be selected from a variety of metal meshes and foam metals, which greatly expands the selection range, increases the range of materials to be selected, and has a wider range of applications.

[0023] (5) The positive electrode of the present invention can be recycled and reused after cleaning, which reduces the preparation cost to a certain extent and maximizes the utilization of resources.

[0024] (6) The synthesis method provided by the present invention is easy to operate, the reaction is thorough, and the reagents are environmentally friendly. The electrodeposition metal-assisted MOF growth method makes the surface functional structure of the oil-water separation material more stable and robust, and can achieve reusability and durability, with good prospects for industrial application. Attached Figure Description

[0025] Figure 1 This is a microstructure diagram of the product of Example 1; wherein, Figure 1 (a1) is a SEM image magnified 500 times by SSM. Figure 1(a2) is a SEM image magnified 1000 times by SSM. Figure 1 (a3) is a SEM image of the SSM cross-section magnified 1000 times; Figure 1 Image (b1) is a Cu / SSM SEM image magnified 500 times. Figure 1 Image (b2) is a Cu / SSM SEM image magnified 1000 times. Figure 1 (b3) is a SEM image of the Cu / SSM cross-section magnified 1000 times; Figure 1 (c1) is a 500x magnified (front) SEM image of the surface of copper oxide grown on Cu-MOFs / SSM. Figure 1 (c2) is a 1000x magnified (reverse) SEM image of the surface of Cu-MOFs / SSM-grown MOFs. Figure 1 (c3) in the image is a SEM image of the cross-section of Cu-MOFs / SSM magnified 1000 times;

[0026] Figure 2 The XRD pattern of the product in Example 1;

[0027] Figure 3 The graph shows the test results of the water contact angle and underwater oil contact angle of the oil-water separation material of the product in Example 1; Figure 3 (a1) in the figure represents the water contact angle of the SSM. Figure 3 (a2) in the figure represents the underwater oil contact angle of the SSM. Figure 3 (b1) in the figure represents the water contact angle of Cu / SSM. Figure 3 (b2) in the figure represents the underwater oil contact angle of Cu / SSM. Figure 3 (c1) in the figure represents the water contact angle of Cu-MOFs / SSM. Figure 3 (c2) in the figure represents the underwater oil contact angle of the Cu-MOFs / SSM oil-water separation material.

[0028] Figure 4 The graph shows the test results of the durable oil-water separation material prepared in Example 1 for separating oil-water mixtures.

[0029] Figure 5 The graph shows the test results of the durable oil-water separation material prepared in Example 2 for separating oil-water mixtures.

[0030] Figure 6 The graph shows the test results of the durable oil-water separation material prepared in Example 3 for separating oil-water mixtures.

[0031] Figure 7 The figure shows the separation test results of the durable oil-water separation material prepared in Example 4 on oil-water emulsion.

[0032] Figure 8The images shown are micrographs and photographs of the durable oil-water separation material prepared in Example 1 before and after oil-water emulsion separation.

[0033] Figure 9 The figure shows the stability and tolerance test results of the durable oil-water separation material prepared in Example 1; where, Figure 9 (a) in the figure shows the results of the acid-base stability test. Figure 9 Figure (b) shows the results of the organic solvent resistance test. Figure 9 (c) in the figure shows the results of the high and low temperature stability test. Figure 9 (d) in the figure shows the results of the UV aging resistance test;

[0034] Figure 10 The graph shows the test results of the recyclability of the durable oil-water separation materials prepared in Example 1 and Comparative Example 1. Figure 10 (a) shows the test results of the durable oil-water separation material Cu-MOFs / SSM in Example 1. Figure 10 (b) in the figure shows the test results of the oil-water separation material in Comparative Example 1;

[0035] Figure 11 The graph shows the test results of the recyclability of the durable oil-water separation materials prepared in Example 2 and Comparative Example 1. Figure 11 (a) shows the test results of the durable oil-water separation material Cu-MOFs / SSM in Example 2. Figure 11 (b) in the figure shows the test results of the oil-water separation material in Comparative Example 1;

[0036] Figure 12 The graph shows the test results of the recyclability of the durable oil-water separation materials prepared in Example 3 and Comparative Example 2. Figure 12 (a) shows the test results of the durable oil-water separation material Cu-MOFs / SSM in Example 3. Figure 12 (b) in the figure shows the test results of the oil-water separation material in Comparative Example 2;

[0037] Figure 13 The image shows the durability test results of the durable oil-water separation materials prepared in Example 1 and Comparative Example 1. Figure 13 Figure (a) shows the experimental results of the durable oil-water separation material of Example 1 after repeated friction. Figure 13 (b) in the figure shows the test results of the oil-water separation material of Comparative Example 1 after multiple frictions;

[0038] Figure 14 The graph shows the durability test results of the durable oil-water separation materials prepared in Example 2 and Comparative Example 1. Figure 14 Figure (a) shows the experimental results of the durable oil-water separation material of Example 2 after repeated friction. Figure 14 (b) in the figure shows the test results of the oil-water separation material of Comparative Example 1 after multiple frictions;

[0039] Figure 15 The image shows the durability test results of the oil-water separation materials prepared in Example 3 and Comparative Example 2. Figure 15 Figure (a) shows the experimental results of the durable oil-water separation material of Example 3 after multiple friction cycles. Figure 15 (b) in the figure shows the test results of the oil-water separation material of Comparative Example 2 after multiple frictions;

[0040] Figure 16 This is a graph showing the antibacterial test results of the durable oil-water separation material prepared in Example 1; Figure 16 (a) shows the growth of *E. coli* in culture medium from 1 to 30 days after the addition of Cu-MOFs / SSM. Figure 16 (b) is a magnified view of the growth of Escherichia coli in the culture medium after Cu-MOFs / SSM were added on day 30; Figure 16 (c) shows the growth of E. coli in the culture medium from 1 to 30 days after the addition of SSM. Figure 16 (b) is a magnified view of the growth of E. coli in the culture medium after adding SSM on day 30; Figure 16 (e) in the figure shows the growth of E. coli in blank culture medium from 1 to 30 days. Figure 16 (f) is a magnified view of the growth of Escherichia coli in the blank culture medium on day 30. Detailed Implementation

[0041] The specific embodiments of the present invention will now be clearly and completely described with reference to examples and accompanying drawings. Obviously, the described examples are only some embodiments of the present invention, and not all embodiments.

[0042] Example 1: A method for preparing a durable oil-water separation material, comprising the following steps: (Cu-MOFs / SSM)

[0043] S1. Cut the 400-mesh stainless steel wire mesh (SSM) and the positive electrode copper mesh into squares with a diameter of 4*4cm. Then prepare a 0.5M hydrochloric acid solution and ultrasonically clean them sequentially with hydrochloric acid solution, ethanol and water, respectively, for 30 minutes each time, and then dry them.

[0044] S2. Prepare a 1M copper sulfate pentahydrate aqueous solution as the electrolyte. Connect the treated stainless steel wire mesh to the negative electrode and the copper mesh to the positive electrode. Start electrodeposition under a constant voltage of 5V for 5 minutes. After the reaction is completed, clean the stainless steel wire mesh and dry it to obtain the Cu / SSM material.

[0045] S3. Prepare a mixed solvent of ethanol and water with a volume ratio of 1:1, then add copper nitrate and trimesic acid with a mass ratio of 1:3 and dissolve them. The concentration of copper nitrate is 4.5 mg / mL. After mixing evenly, add 50 mL of the solution to the reaction vessel, then add the stainless steel wire mesh obtained in S2. After reacting at 120℃ for 8 hours, remove the stainless steel wire mesh and clean it to obtain the durable oil-water separation material Cu-MOFs / SSM.

[0046] Example 2: A method for preparing a durable oil-water separation material, comprising the following steps: (Zn-MOFs / SSM)

[0047] S1. Cut the 400-mesh stainless steel wire mesh as the substrate and the positive electrode zinc sheet (Zn) into squares with a diameter of 4*4cm. Then prepare a 0.5M hydrochloric acid solution and clean them with hydrochloric acid solution, ethanol and water in sequence by ultrasonic cleaning for 30 minutes each time, and then dry them.

[0048] S2. Prepare a 1M zinc nitrate aqueous solution as the electrolyte. Connect the treated stainless steel wire mesh to the negative electrode and the zinc sheet to the positive electrode. Start electrodeposition under a constant voltage of 3V. The reaction time is 3.5min. After the reaction is completed, clean the stainless steel wire mesh and dry it to obtain the Zn / SSM material.

[0049] S3. Prepare a mixed solvent of ethanol and water with a volume ratio of 1:1, then add copper nitrate and trimesic acid with a molar ratio of 1:3 and dissolve them. The concentration of copper nitrate is 4.5 mg / mL. After mixing evenly, pour it into the inner liner of the reaction vessel, then add the stainless steel wire mesh obtained in S2. React at 120℃ for 8 hours to obtain the durable oil-water separation material Zn-MOFs / SSM.

[0050] Example 3: A method for preparing a durable oil-water separation material, comprising the following steps: (Zn-UiO66 / SSM)

[0051] S1. Cut the 400-mesh stainless steel wire mesh as the substrate and the zinc sheet as the positive electrode into squares with a diameter of 4*4cm. Then prepare a 0.5M sulfuric acid solution and ultrasonically clean them in sequence with sulfuric acid solution, ethanol and water, respectively, for 30 minutes each time, and then dry them.

[0052] S2. Prepare a 1M zinc nitrate aqueous solution as the electrolyte. Connect the treated stainless steel wire mesh to the negative electrode and the zinc sheet to the positive electrode. Start electrodeposition under a constant voltage of 3V. The reaction time is 3.5min. After the reaction is completed, clean the stainless steel wire mesh and dry it to obtain the Zn / SSM material.

[0053] S3. Add zirconium chloride and 2-aminoterephthalic acid in a mass ratio of 1:1 to N,N-dimethylformamide solvent and dissolve them. The concentration of zirconium chloride is 2 mg / mL. After mixing evenly, add 50 mL of the solution to the reaction vessel, and then add the stainless steel wire mesh obtained in S2. After reacting at 180℃ for 12 h, remove the stainless steel wire mesh and clean it to obtain the durable oil-water separation material Zn-MOFs / SSM.

[0054] Example 4: The difference between this example and Example 1 is that the substrate used is a 2200-mesh stainless steel wire mesh, and all other aspects are the same.

[0055] Comparative Example 1: The difference from Example 1 is that step S2 is not included, but all other steps are the same.

[0056] Comparative Example 2: The difference from Example 3 is that step S3 is not included, but all other steps are the same.

[0057] To further illustrate the performance and effect of the durable oil-water separation material prepared according to the embodiments of the present invention, specific test examples are given below.

[0058] 1. SEM testing: The durable oil-water separation material and its intermediates prepared in Example 1 were subjected to SEM testing. The final results are as follows: Figure 1 As shown.

[0059] Figure 1 (a) is the SEM image of the original stainless steel wire mesh (SSM), where (a1) is the SEM image of SSM magnified 500 times, (a2) is the SEM image of SSM magnified 1000 times, and (a3) ​​is the SEM image of the cross-section of SSM magnified 1000 times. Figure 1 (b) is the SEM image of the stainless steel wire mesh Cu / SSM after electrodeposition in S2, (b1) is the SEM image magnified 500 times, (b2) is the SEM image magnified 1000 times, and (b3) is the SEM image of the cross section magnified 1000 times. Figure 1 In the image, (c) is a SEM image of the durable oil-water separation material Cu-MOFs / SSM prepared in Example 1, (c1) is a SEM image of the surface on which the copper oxide is grown (front side) magnified 500 times, (c2) is a SEM image of the surface on which the MOFs are grown (back side) magnified 1000 times, and (c3) is a SEM image of the cross-section magnified 1000 times.

[0060] As can be seen from the figure, the original SSM surface is relatively smooth; after electrodeposition, copper nanoparticles are uniformly deposited on the surface and in the pores of Cu / SSM, creating nucleation sites for the subsequent growth of MOFs; the durable oil-water separation material Cu-MOFs / SSM exhibits a typical MOF structure with a polyhedral morphology on one side and a flower-like copper oxide structure on the other side, indicating that MOFs and metal oxides have been successfully combined into the surface and pore structure of stainless steel wire mesh, forming an interlocked micro-nano structure of "MOFs-copper oxide".

[0061] 2. XRD pattern: The durable oil-water separation material and its intermediates prepared in Example 1 were subjected to XRD tests. The final results are as follows. Figure 2 As shown.

[0062] from Figure 2 It can be seen that for the electrodeposited Cu / SSM material, the characteristic peak at 2θ = 42.44° indicates the presence of Cu crystals; for the durable oil-water separation material Cu-MOFs / SSM, the characteristic peaks at 2θ = 17.86, 24.52, 35.6, 36.7, 38.4, and 39.48 also indicate the presence of Cu(OH)2 crystals, and the characteristic peaks at 2θ = 7.02°, 9.82°, and 11.96° also indicate the presence of MOFs, indicating that MOFs and copper oxides were successfully modified on the surface of the stainless steel wire mesh.

[0063] 3. Contact Angle Test: The durable oil-water separation material and its intermediates prepared in Example 1 were used, with water and cyclohexane as the liquid phases. The water contact angle and underwater oil contact angle were measured using a fully automated contact angle meter. The final results are as follows: Figure 3 As shown.

[0064] In the picture, Figure 3 a1, b1, and c1 represent the water contact angles (WCA) of unmodified stainless steel wire mesh (SSM), electrodeposited stainless steel wire mesh (Cu / SSM), and durable oil-water separation material (Cu-MOFs / SSM), respectively. Figure 3 a2, b2, and c2 in the figure represent the underwater oil contact angles (UWOCA) of the SSM, Cu / SSM, and Cu-MOFs / SSM oil-water separation materials, respectively, indicating that the durable oil-water separation material Cu-MOFs / SSM prepared in Example 1 of this invention has superhydrophilic and underwater superoleophobic properties.

[0065] 4. Oil-water separation test: Cyclohexane, petroleum ether, n-octane, toluene, and n-hexane organic solvents were used to prepare different oil-water mixtures (cyclohexane-water, petroleum ether-water, n-hexane-water, toluene-water, and n-octane-water) at a volume ratio of 1:1. These oil-water mixtures were thoroughly mixed. The mixtures were then subjected to oil-water separation tests using the durable oil-water separation materials prepared in Examples 1-3. The final results are as follows: Figures 4-6 As shown.

[0066] Using sodium dodecyl sulfate as a surfactant, 1 ml of each of six oils—cyclohexane, n-octane, petroleum ether, 1,2-dichloroethane, n-hexane, and diesel—was mixed with 99 ml of pure water and 0.1 g of sodium dodecyl sulfate. After ultrasonic mixing for 30 minutes, different oil-water emulsions were obtained. After standing for half an hour, the durable oil-water separation material prepared in Example 4 was used to test the oil-water separation of the emulsions. The final results are as follows: Figure 7 As shown in the figure. Take 1-2 drops of the oil-water emulsion before and after separation, place them on a glass slide, and observe the distribution of oil droplets within the droplets under a microscope at 30µm magnification. The final results are shown in the figure. Figure 8 As shown.

[0067] Figure 4 , Figure 5 and Figure 6 The figures show the separation efficiency of the durable oil-water separation materials prepared in Examples 1-3 for oil-water mixtures. As can be seen from the figures, the durable oil-water separation materials prepared in these examples have high separation efficiency for oil-water mixtures, with separation efficiencies exceeding 99% for various organic solvents, and a high water flux of over 20,000 L·m⁻¹. -2 ·h -1 For some organic solvents, such as petroleum ether, the water separation flux can exceed 30,000 L·m⁻¹. -2 ·h -1 This demonstrates that the durable oil-water separation material prepared according to the embodiments of the present invention can quickly and effectively separate oil-water mixtures, making it suitable for large-scale industrial application.

[0068] Figure 7 The image shows the separation test results of the durable oil-water separation material prepared in Example 4 on the oil-water emulsion. Figure 8 Microscopic images and photographs of each emulsion before and after separation are provided. From Figure 7 It can be seen that the durable oil-water separation material prepared in Example 4 has a good separation effect on emulsions, with a separation efficiency of over 98%, a fast separation speed, and a water flux of up to 800 L·m -2 ·h -1 That's all. From Figure 8As can be seen, in the oil-water emulsion before separation, the oil droplets are relatively evenly distributed in the water and have a small particle size (left image), making them difficult to remove using conventional methods; in the aqueous phase after separation, there are basically no oil droplets, indicating that the separation is relatively thorough (right image); from the actual photograph (middle image), it can also be seen that it has a good separation effect on emulsions composed of various organic solvents and water.

[0069] 5. Stability and Durability Tests: The durable oil-water separation material Cu-MOFs / SSM prepared in Example 1 was subjected to the following tests:

[0070] Acid-base stability tests were conducted by preparing aqueous solutions with different pH values ​​using hydrochloric acid and sodium hydroxide. The durable oil-water separator was then immersed in these solutions for 48 hours. After immersion, the Cu-MOFs / SSM durable oil-water separator was removed, and its underwater oil contact angle was tested according to the method in Test Example 3. Its separation efficiency for cyclohexane oil-water mixtures was tested according to the method in Test Example 4. The final results are as follows: Figure 9 As shown in (a) in the figure.

[0071] Organic solvent resistance testing involved immersing the durable oil-water separator in an organic solvent for 48 hours. After immersion, the Cu-MOFs / SSM durable oil-water separator was removed, and its underwater oil contact angle was tested according to the method in Test Example 3. Its separation efficiency for cyclohexane oil-water mixtures was tested according to the method in Test Example 4. The final results are as follows: Figure 9 As shown in (b) of the diagram.

[0072] High and low temperature stability tests were conducted. The durable oil-water separation material Cu-MOFs / SSM from Example 1 was placed under different temperature conditions and kept at those temperatures for 24 hours. After the holding period, its underwater oil contact angle was tested according to the method in Example 3, and its separation efficiency for cyclohexane oil-water mixtures was tested according to the method in Example 4. The final results are as follows: Figure 9 As shown in (c) in the figure.

[0073] For the UV aging test, the durable oil-water separation material Cu-MOFs / SSM from Example 1 was aged under a UV lamp for 9 days. Its underwater oil contact angle was tested according to the method in Example 3, and its separation efficiency for cyclohexane oil-water mixtures was tested according to the method in Example 4. The final results are as follows: Figure 9 As shown in (d) in the figure.

[0074] from Figure 9 As shown in (a), after soaking in aqueous solutions of different pH values ​​for 48 hours, the underwater oil contact angle remained above 150°, and the oil-water separation efficiency remained above 99%. Figure 9As shown in (b), after soaking in various organic solvents for 48 hours, the underwater oil contact angle remained between 150° and 156°, and the oil-water separation efficiency remained above 99%, demonstrating excellent resistance to organic solvents; from Figure 9 As shown in (c), high and low temperatures have little effect on the contact angle and oil-water separation efficiency; the contact angle remains above 150°, and the oil-water separation efficiency remains greater than 99%. Figure 9 As shown in (d), ultraviolet light has little effect on the contact angle and oil-water separation effect. After long-term ultraviolet irradiation, the underwater oil contact angle is still greater than 151°, and the oil-water separation efficiency is higher than 98%. This indicates that the durable oil-water separation material prepared in the embodiments of the present invention has strong resistance to acids, alkalis, organic solvents, high and low temperatures, and ultraviolet light.

[0075] 6. Recycling Performance: The materials obtained in Examples 1-3 and Comparative Examples 1-3 were used to measure their separation effect on cyclohexane-water mixtures after multiple uses. The final results are as follows: Figures 10-12 As shown.

[0076] In the picture, Figure 10 (a) shows the test results of the durable oil-water separation material Cu-MOFs / SSM in Example 1. Figure 10 Figure (b) shows the test results of the oil-water separation material of Comparative Example 1. As can be seen from the figure, the separation efficiency of Cu-MOFs / SSM oil-water separation material of Example 1 is 99.2% after 20 cycles; while the performance of the oil-water separation material of Comparative Example 1 drops significantly after only one use, and its separation efficiency decreases to 0 after two uses.

[0077] Figure 11 (a) shows the test results of the durable oil-water separation material Cu-MOFs / SSM in Example 2. Figure 11 (b) shows the test results of the oil-water separation material in Comparative Example 1 (the difference between Example 1 and Example 2 is that the operation in S2 is different, while S1 and S3 are the same). As can be seen from the figure, the separation efficiency of the oil-water separation material Cu-MOFs / SSM is 99.2% after 20 cycles.

[0078] Figure 12 (a) shows the test results of the durable oil-water separation material Cu-MOFs / SSM in Example 3. Figure 12 Figure (b) shows the test results of the oil-water separation material in Comparative Example 2. As can be seen from the figure, the separation efficiency of the oil-water separation material Cu-MOFs / SSM is 99.2% after 20 cycles; while the performance of the oil-water separation material in Comparative Example 2 drops significantly after only one use, and its separation efficiency decreases to 0 after three uses.

[0079] 7. Durability Test: The oil-water separation materials prepared in Examples 1-3 and Comparative Examples 1-3 were rubbed on their surfaces 20 times and 5 times respectively with 2000-grit sandpaper. The separation effect on cyclohexane oil-water mixtures was then tested. The experimental results are as follows: Figures 13-15 As shown.

[0080] In the picture, Figure 13 Figure (a) shows the experimental results of the durable oil-water separation material of Example 1 after repeated friction. Figure 13 Figure (b) shows the test results of the oil-water separation material of Comparative Example 1 after multiple friction cycles. As can be seen from the figure, even after 20 friction cycles, the oil-water separation efficiency of the durable oil-water separation material of Example 1 is still above 99%, while the oil-water separation efficiency of the oil-water separation material of Comparative Example 1 drops to 0 after only one friction cycle.

[0081] Figure 14 Figure (a) shows the experimental results of the durable oil-water separation material of Example 2 after repeated friction. Figure 14 Figure (b) shows the test results of the oil-water separation material of Comparative Example 1 after multiple friction cycles. As can be seen from the figure, even after 20 friction cycles, the oil-water separation efficiency of the durable oil-water separation material of Example 1 is still above 99%.

[0082] Figure 15 Figure (a) shows the experimental results of the durable oil-water separation material of Example 3 after multiple friction cycles. Figure 15 Figure (b) shows the test results of the oil-water separation material of Comparative Example 2 after multiple friction cycles. As can be seen from the figure, even after 20 friction cycles, the oil-water separation efficiency of the durable oil-water separation material of Example 1 is still above 99%, while the oil-water separation efficiency of the oil-water separation material of Comparative Example 1 drops to 0 after only one friction cycle.

[0083] 8. Antibacterial Test: The durable oil-water separation material Cu-MOFs / SSM and unmodified stainless steel wire mesh SSM prepared in Example 1 were added to Escherichia coli solid culture medium and cultured for a period of time. The growth of Escherichia coli around the durable oil-water separation material, the unmodified stainless steel wire mesh, and the blank culture medium was observed. The final results are as follows: Figure 16 As shown.

[0084] In the picture, Figure 16 Images (a) and (b) show the growth of *E. coli* in the culture medium after the addition of the durable oil-water separation material Cu-MOFs / SSM. Figure 16 (c) and (d) show the growth of Escherichia coli in the culture medium after the addition of unmodified stainless steel wire mesh (SSM). Figure 16Figures (e) and (f) show the growth of the blank culture medium. As can be seen from the figure, there is a relatively obvious inhibition zone around the durable oil-water separation material Cu-MOFs / SSM, and there is no obvious E. coli contamination on its surface and surrounding area; while no E. coli inhibition zone was observed in the unmodified stainless steel wire mesh SSM and the blank culture medium, and both were severely contaminated.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a durable oil-water separation material, characterized in that, Includes the following steps: S1. Clean and dry the metal substrate and the positive electrode; the metal elements contained in the metal substrate and the metal elements contained in the positive electrode are different; S2. Prepare an electrolyte containing a metal salt, and use the metal substrate obtained in S1 as the negative electrode for electrodeposition; wherein the metal salt contains the same type of metal element as the positive electrode. S3. An organic ligand and a soluble metal additive are mixed in a solvent to prepare a metal-organic framework (MOF) precursor solution. The electrodeposited metal substrate is then placed in the MOF precursor solution and subjected to a solvothermal reaction. After the reaction, a durable oil-water separation material is obtained. The organic ligand is one of 2-aminoterephthalic acid, 2,5-dihydroxyterephthalic acid, terephthalic acid, or trimesic acid. The molar ratio of the organic ligand to the soluble metal additive is 1:0.25~1.

0. The concentration of the soluble metal additive is 2~18 mg / mL.

2. The method according to claim 1, characterized in that, In S1, the cleaning and drying steps of the metal substrate and the positive electrode are as follows: the metal substrate and the positive electrode are ultrasonically washed sequentially with a dilute acid solution, a small molecule alcohol and water, and then dried after washing; the dilute acid solution is one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution with a concentration of 0.3~1.0M; the small molecule alcohol is one of methanol or ethanol.

3. The method according to claim 1, characterized in that, The metal substrate has a mesh size of 200 to 1000.

4. The method according to claim 1, characterized in that, The metal substrate has a mesh size of 2000-2800.

5. The method according to claim 1, wherein In S1, the metal substrate is one of stainless steel wire mesh, iron mesh, copper mesh, titanium mesh, nickel mesh, copper foam, and iron foam, and the positive electrode is one of copper, iron, titanium, zirconium, and nickel; in S2, the metal salt is one of soluble copper salt, soluble iron salt, soluble titanium salt, soluble zirconium salt, and soluble nickel salt; in S3, the soluble metal additive is one of copper nitrate, zirconium chloride, ferric chloride, chromium nitrate, and bismuth nitrate.

6. The method according to claim 1, characterized in that, In S2, the power source for electrodeposition is a constant voltage DC power source with a voltage of 2~5V and a time of 1~5min.

7. The method according to claim 1, characterized in that, In S2, the concentration of the metal salt is 0.5~1.5 mol / L.

8. The method according to claim 1, characterized in that In S3, the solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, anhydrous ethanol, and anhydrous methanol, or a mixture of one of N,N-dimethylformamide, N,N-dimethylacetamide, anhydrous ethanol, and anhydrous methanol with water.

9. The method according to claim 1, characterized in that, The temperature of the solvothermal reaction is 100~180℃, and the electrodeposited metal substrate is immersed in the metal-organic framework material precursor solution for 6~12h.

10. A durable oil-water separation material, prepared by the method described in any one of claims 1 to 9.

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