Oil-water separation membrane and preparation method thereof

Abstract

The invention discloses an oil-water separation membrane and a preparation method thereof, the oil-water separation membrane comprises a punching substrate material and nanowires, the punching substrate material is a copper foil provided with array micropores, the array micropores are formed by laser processing, and the array micropores are formed by regularly arranging a plurality of micropores; the nanowire is a copper hydroxide nanowire; the punching substrate material is divided into a substrate area, a micropore edge area and a micropore wall area; the nanowires are distributed in the substrate area, the micropore edge area and the micropore wall area. The oil-water separation membrane disclosed by the invention has long-acting super-hydrophilicity and underwater super-oleophobicity and is high in oil-water separation efficiency; efficient and stable separation of various oil-water mixtures such as n-octane, methylbenzene and soybean oil can be realized, and the separation efficiency is higher than 99%.

Description

Technical Field

[0001] The present invention belongs to the field of functional materials, and in particular relates to an oil-water separation membrane and a preparation method thereof. Background Art

[0002] Oil spills from marine oil tankers and drilling platforms, as well as the discharge of oily wastewater from industrial and domestic sources, have caused severe oil pollution in the aquatic environment. This not only poses a direct threat to human health but also impacts environmental protection, biodiversity, and economic sustainability. Traditional methods for oil-water separation, including absorption, skimming, centrifugation, biodegradation, and in-situ combustion, are used to recover oil-containing wastewater. However, these methods are associated with high costs, complex separation processes, and the potential for secondary pollution. Therefore, the development of new oil-water separation methods is crucial.

[0003] In recent years, with the continuous advancement of biomimetic theory and precision manufacturing technology, biomimetic surfaces with extreme wetting phenomena have attracted increasing attention and are expected to become a new approach to solving the oil-water separation problem. For example, Patent 1 (CN105688447A) discloses an oil-water separation filter screen produced by laser processing on a hydrophilic film; Patent 2 (CN107158754A) discloses a method for preparing a copper mesh with oil-water separation function, which produces a super-hydrophobic copper mesh with surface through-holes and surface micro-nanostructures; and Patent 3 (CN113368538A) discloses a flexible copper mesh with a deposited aluminum oxide nanocoating. Among the above-mentioned prior arts, Patent 1 separates oil and water by improving the physical structure and performance of the substrate itself; Patent 2 forms a super-hydrophobic copper mesh by covering the surface of the copper mesh with a hydrophobic agent, but the hydrophobic agent only exists on the surface of the copper mesh, and the properties of the hollow part inside the mesh of the copper mesh do not change; Patent 3 improves the filtering performance of the copper mesh by setting an aluminum oxide nano-coating on the surface of the copper mesh, while the properties of the mesh inside and the lower surface of the copper mesh do not change; the oil-water separation membranes of the above-mentioned prior arts will result in low oil-water separation efficiency and poor stability.

[0004] Patent 4 (CN112626518A) discloses a multifunctional bionic titanium-based surface, which uses a titanium alloy as a substrate. After laser drilling and other treatments, TiO2 nanowires are formed on the titanium alloy substrate, thereby obtaining a superhydrophilic / underwater superoleophobic surface; however, when preparing this bionic titanium-based surface, it is necessary to heat react in high-temperature and high-pressure water for 8-10 hours to form a titanium dioxide structure. When a thin film substrate is treated in a high-temperature and high-pressure environment, the substrate will be severely deformed, making it impossible to form an oil-water separation membrane. In addition, the preparation conditions are energy-intensive and the preparation time is long, which poses a production safety hazard and is not conducive to improving production efficiency. Summary of the Invention

[0005] In order to improve the separation stability and separation efficiency of the oil-water separation membrane and reduce the preparation cost of the oil-water separation membrane, the present invention provides the following technical solutions:

[0006] An oil-water separation membrane comprises a perforated base material and nanowires, wherein the perforated base material is a copper foil provided with an array of micropores, the array of micropores being formed by laser processing and consisting of a plurality of micropores arranged in a regular pattern; the nanowires are copper hydroxide nanowires; the perforated base material is divided into a base region, a micropore edge region, and a micropore wall region; the nanowires are distributed in the base region, the micropore edge region, and the micropore wall region.

[0007] Preferably, the nanowires in the base region are distributed in a network pattern; the nanowires in the micropore edge region and the micropore wall region are entangled, stacked and bundled with each other; and the growth direction of the nanowires in the micropore wall region is perpendicular to the wall of the micropore.

[0008] A method for preparing an oil-water separation membrane, the method being used to prepare the above-mentioned oil-water separation membrane, comprising the following steps:

[0009] S1. Selecting a substrate material, initially cleaning the substrate material, and drying it with protective gas to obtain a clean substrate material;

[0010] S2, preparing a nanowire growth liquid that can react with the base material, stirring the nanowire growth liquid uniformly and cooling it to room temperature;

[0011] S3, setting laser processing parameters, and processing the array micropores on the surface of the clean base material according to the laser processing parameters to obtain the perforated base material;

[0012] S4, pre-treating the perforated base material to obtain a pre-treated base material; the pre-treating comprises performing a secondary cleaning on the perforated base material, and after the secondary cleaning, drying the base material again with the protective gas;

[0013] S5. placing the pretreated base material in the nanowire growth solution at room temperature and pressure, and setting a nanowire growth time to allow the nanowires to grow in the pretreated base material to obtain a nanowire base material;

[0014] S6. Wash the nanowire base material three times and then dry it naturally to obtain the oil-water separation membrane.

[0015] Preferably, the secondary cleaning is used to remove oxides in the perforated base material.

[0016] Preferably, the secondary cleaning comprises sequentially performing ultrasonic cleaning on the perforated base material using dilute hydrochloric acid, anhydrous ethanol, and deionized water.

[0017] Preferably, the first cleaning comprises sequentially performing ultrasonic cleaning on the substrate material using acetone, anhydrous ethanol and deionized water; and the third cleaning comprises sequentially rinsing the nanowire substrate material using flowing anhydrous ethanol and deionized water.

[0018] Preferably, step S3 further comprises clamping and fixing the clean base material with a hollow fixture, so that the surface of the laser processing area in the clean base material is flat and wrinkle-free, and the laser processing area is always suspended.

[0019] Preferably, the pretreated substrate material is placed in the nanowire growth liquid in a vertical manner.

[0020] Preferably, the nanowire growth liquid is a mixture of sodium hydrogen peroxide solution and ammonium sulfate solution; the concentration of the sodium hydroxide is 0.625M to 1.875M, and the concentration of the ammonium persulfate is 0.0325M to 0.0975M.

[0021] Preferably, the configuration of the nanowire growth liquid includes the following steps:

[0022] S21. Weighing sodium hydroxide solid and ammonium persulfate solid according to the growth solution parameters;

[0023] S22, prepare sodium hydroxide solution, stir evenly and cool to room temperature;

[0024] S23, dissolving the ammonium persulfate solid in the sodium hydroxide solution to prepare a mixed solution of the sodium hydroxide solution and ammonium persulfate, and stirring the mixed solution to obtain the nanowire growth solution.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The superhydrophilic oil-water separation membrane provided by the present invention has long-lasting superhydrophilicity and underwater superoleophobicity, and has high oil-water separation efficiency; it can achieve efficient and stable separation of various oil-water mixtures such as n-octane, toluene, and soybean oil, with a separation efficiency of more than 99%;

[0027] (2) In the method for preparing the oil-water separation membrane of the present invention, an array of micropores is formed on a substrate by laser drilling, and the nanowire self-growth process is combined to obtain an oil-water separation membrane. This method is simple, efficient, and has the advantages of low manufacturing cost.

[0028] (3) The present invention uses picosecond ultraviolet laser to process array micropores. The shorter pulse width of the laser reduces the thermal effect, and the shorter wavelength increases the absorption rate, ensuring the processing quality of the micropores. Compared with nanosecond lasers and femtosecond lasers, the cost performance is high.

[0029] (4) The present invention uses a digital galvanometer to drive the laser beam to process the array microholes, so that the microhole processing is high in precision and speed, and the diameter and spacing of the microholes can be flexibly adjusted according to needs, and the scanning speed and number of scans can be flexibly adjusted according to the thickness of the substrate material;

[0030] (5) The present invention chooses to grow copper hydroxide nanowires on the surface of copper foil, and the obtained oil-water separation membrane has a large specific surface area, and the network structure of the oil-water separation membrane also significantly increases the level of surface micro-nano structure; and the rich hydroxyl hydrophilic groups on the surface of the oil-water separation membrane comprehensively ensure the long-term superhydrophilicity and underwater superoleophobicity of the oil-water separation membrane in terms of structure and material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a typical morphology diagram of the oil-water separation membrane of the present invention;

[0032] Figure 2 This is a diagram of the dynamic contact process between the oil-water separation membrane and the base material, and between the perforated base material and the droplets of the present invention;

[0033] Figure 3 This is a diagram of the process of oil-water separation by the oil-water separation membrane and the perforated base material of the present invention;

[0034] Figure 4 This is a flow chart of the method for preparing the oil-water separation membrane of the present invention;

[0035] Figure 5 It is a processing diagram of the preparation method of the oil-water separation membrane of the present invention;

[0036] Figure 6 1 is a diagram of the elements and contents of the edges of the array micropores in the perforated substrate material and the pretreated substrate material of the present invention. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Example 1:

[0039] An oil-water separation membrane, such as Figure 1 and Figure 5As shown in (e), it includes a perforated base material and nanowires, wherein the perforated base material is a base material provided with array micropores, and the array micropores are formed by laser drilling; the base material is copper foil, and the nanowires are copper hydroxide nanowires; the perforated base material is divided into a base area, a micropore edge area and a micropore wall area, and the nanowires are distributed in the base area, the micropore edge area and the micropore wall area. The array micropores refer to a plurality of micropores arranged in a certain pattern on the base material. The base area refers to an area on the copper foil where no micropores are formed, such as Figure 1 (c) A region shown; the micropore edge region refers to the collection of each micropore edge region, such as Figure 1 (c) shown in region B; the micropore wall region refers to the collection of the inner wall of each micropore and the hollow pore area of ​​each micropore, Figure 1 Region C as described in (c).

[0040] Specifically, the nanowires in the base region are in a mesh form, such as Figure 1 As shown in area A in (c), since the base area is basically not affected by laser drilling, it belongs to the nanowires grown on the surface of the original copper foil. The nanowires appear to be mesh-like, with random growth directions, and the nanowires are independent and separated from each other, as shown in Figure 1. Figure 1 (d) As shown. The nanowires in the micropore edge region are entangled, stacked and bundled, as shown in FIG. Figure 1 As shown in region B in (c), the edge of the micropore is the heat-affected zone formed by laser drilling, and the growth direction of the nanowires gradually changes from "upward to the right - vertically upward - upward to the left". The nanowires in the micropore wall area are also entangled, stacked, and bundled, as shown in Figure 2. Figure 1 As shown in region C in (c), the nanowire growth direction in the micropore wall region is perpendicular to the pore wall and extends toward the center of the micropore.

[0041] The diameter of the array micropores is 50 to 150 microns, and the spacing is 100 to 300 microns; the thickness of the perforated base material is 30 to 50 microns; and the width of the nanowires is 100 to 150 nanometers. The nanowire width is a result-oriented range value. To achieve this result, the concentration of the growth liquid must be within the preferred range, and different growth liquid concentrations must correspond to different growth times. Further, as Figure 1 As shown in (a), the array micropores are arranged according to a designed spacing rule, and the array micropores have good consistency in size and roundness; and the copper hydroxide nanowires covering the periphery of the array micropores are also very uniform, and the overall surface uniformity and consistency are high.

[0042] Furthermore, the oil-water separation membrane in this technical solution has superhydrophilicity in air and superoleophobicity underwater. Specifically, the water contact angle of the oil-water separation membrane in air is 0°, and the oil contact angle underwater is 154°.

[0043] The super-hydrophilic oil-water separation membrane of the present invention has the characteristics of a large specific surface area. Due to the nanowire network structure grown on the surface of the perforated base material, the layering of the micro-nanostructure on the surface of the oil-water separation membrane is significantly increased. At the same time, due to the use of copper hydroxide nanowires, the surface of the oil-water separation membrane contains abundant hydroxyl hydrophilic groups, which can achieve long-term super-hydrophilicity of the oil-water separation membrane. The long-term super-hydrophilicity and underwater super-oleophobicity of the oil-water separation membrane are comprehensively guaranteed in terms of structure and materials. It can also achieve efficient and stable separation of various oil-water mixtures such as n-octane, toluene, and soybean oil, with a separation efficiency exceeding 99%.

[0044] like Figure 2 and Figure 3 As shown, the oil-water separation membrane of the present invention exhibits super-hydrophilicity compared to the original base material or the perforated base material, and has higher separation efficiency and better separation stability for oil-water mixture. Figure 2 This is a diagram of the dynamic contact process between the oil-water separation membrane of the present invention and the original base material, and between the perforated base material and the droplets; Figure 3 This is a diagram of the process of oil-water separation using the oil-water separation membrane and the perforated base material of the present invention.

[0045] Figure 2 The vertical distance between the middle droplet and the original substrate material, the perforated substrate material and the surface of the oil-water separation membrane of the present invention is about 20 cm, and the water droplet is allowed to fall freely and contact the surface of the above materials. Figure 2 (a) shows the contact process between the droplet and the original substrate surface. During this process, the droplet begins to compress after contacting the original substrate surface, showing a "spherical-gourd-pancake" evolution, followed by a central bulge and a triangular cross-section, and finally stabilizes in an up-and-down fluctuation. Figure 2 (b) shows the dynamic contact process between the droplet and the perforated substrate. In this process, the compression and expansion process of the droplet after landing on the perforated substrate is almost the same as that of the original surface, but the droplet gradually spreads as it approaches a steady state after expansion, and the final contact area is larger. Figure 2 (c) shows the dynamic contact process between the droplet and the oil-water separation membrane of the present invention. Although the droplet is compressed during the contact process with the oil-water separation membrane, there is no expansion phenomenon. The surface of the oil-water separation membrane shows a spherical-gourd-pancake contour compression evolution, followed by rapid spreading, and finally the contour disappears completely, showing good dynamic wettability. Figure 2From the comparison of (a) to (c), it can be seen that although the perforated base material can enhance the hydrophilicity of the base material compared to the original base material, it cannot achieve super hydrophilicity. The oil-water separation membrane described in the present invention has excellent super hydrophilicity and enables the droplets to be completely spread on its surface.

[0046] right Figure 3 When conducting comparative analysis, Figure 3 (a) is a perforated substrate. After the oil is poured into the upper glass tube, it directly passes through the perforated substrate. After the water is poured in, the oil that has not yet passed through the perforated substrate is lifted up by the water. Although the water does not pass through the perforated substrate at the beginning, it gradually penetrates the perforated substrate as the water is poured in. As a result, the oil-water mixture is still in the beaker at the bottom after separation, and the separation of light oil and water cannot be achieved. Figure 3 (b) shows the oil-water separation membrane of the present invention. When oil is initially poured in, it is retained in the upper glass tube by the membrane due to its superhydrophilicity. Even after all the oil has been poured in, it still cannot pass through the membrane. However, after water is poured in, its greater density rapidly sinks below the oil and passes through the membrane. As water continues to be poured in, it completely passes through the membrane, while the oil is retained in the upper portion and remains stable. This demonstrates that the oil-water separation membrane of the present invention can effectively separate oil and water.

[0047] In summary, the oil-water separation membrane of the present invention can more stably and effectively separate oil and water.

[0048] Example 2:

[0049] A method for preparing the oil-water separation membrane as described in Example 1, Figure 4-5 As shown, it includes the following steps:

[0050] S1. Select a base material, clean the base material for the first time, and blow dry it with protective gas to obtain a clean base material; wherein the base material is copper foil, such as Figure 5 (a) shows; this step is used to remove oil and dust on the surface of the base material;

[0051] S2. preparing a nanowire growth liquid that can react with the base material, stirring the nanowire growth liquid uniformly and cooling it to room temperature; wherein the nanowire growth liquid refers to a mixed solution that can react with the clean base material to grow nanowires;

[0052] S3, setting laser processing parameters, and processing the array micropores on the surface of the clean base material according to the laser processing parameters to obtain a perforated base material, such as Figure 5 (b) to (c)

[0053] S4, pre-treating the punched base material to obtain a pre-treated base material, such as Figure 5 (d) As shown; the pretreatment includes performing a secondary cleaning on the perforated base material, and drying with the protective gas after the secondary cleaning to remove oxides in the perforated base material and to protect the surface of the pretreated base material;

[0054] S5. At room temperature and pressure, placing the pretreated base material in the nanowire growth solution and setting the nanowire growth time to allow the nanowire to grow in the pretreated base material to obtain a nanowire base material, such as Figure 5 (e) As shown; the nanowire growth time is determined according to the nanowire width and the growth solution concentration, and the nanowire growth time can be set to 3 to 10 minutes;

[0055] S6. Washing the nanowire base material three times and then air-drying the nanowire base material to obtain the oil-water separation membrane. The three washes remove residual sodium hydroxide and ammonium persulfate on the surface of the nanowire base material to stop the continued growth of the nanowires. The three washes control the growth time of the nanowires.

[0056] The primary cleaning step involves ultrasonically cleaning the substrate material using acetone, anhydrous ethanol, and deionized water in sequence. The secondary cleaning step involves ultrasonically cleaning the perforated substrate material using dilute hydrochloric acid, anhydrous ethanol, and deionized water in sequence. The tertiary cleaning step involves rinsing the nanowire substrate material using flowing anhydrous ethanol and deionized water in sequence. Preferably, the protective gas is nitrogen to prevent oxidation of the copper foil.

[0057] In particular, the secondary cleaning is one of the key steps of the present invention. During the laser processing of micropores, the edges of the micropores become heat-affected zones, and the splashing materials during the drilling process are deposited at the edges of each micropore in the array micropores, thereby forming more oxides at the edges of each micropore and the inner wall of the micropores, covering the micropore wall area and the micropore edge area, thereby preventing the nanowires from growing normally in these areas. The present invention uses dilute hydrochloric acid to ultrasonically clean the perforated base material, which can greatly reduce the presence of oxides; then, anhydrous ethanol and deionized water are used for ultrasonic cleaning to remove the dilute hydrochloric acid components remaining on the surface, and the perforated base material is quickly blown dry with nitrogen to avoid continued oxidation of the perforated base material exposed to the air after the oxides are removed. Figure 6 As shown, Figure 6 (a) Represents the element types and contents at the edges of array microholes in the perforated substrate material; Figure 6 (b) shows the element types and contents at the edges of the array micropores in the pretreated substrate material obtained after secondary cleaning; Figure 6As shown in Figures a and b, the perforated and pretreated substrates contain only copper and oxygen. However, after secondary cleaning, the oxygen content of the pretreated substrate drops from 12.2% to 1.9%, demonstrating that secondary cleaning significantly reduces the oxide content in the perforated substrate. Therefore, secondary cleaning allows the nanowires to cover a wider area, further improving the hydrophilicity of the oil-water separation membrane.

[0058] The nanowire growth liquid is preferably a mixed solution of sodium hydroxide and ammonium persulfate, the concentration of the sodium hydroxide is preferably 0.625M to 1.875M, and the concentration of the ammonium persulfate is preferably 0.0325M to 0.0975M.

[0059] In step S5, the pretreated substrate material is placed vertically in the nanowire solution to ensure that the nanowires grown on the upper and lower surfaces of the pretreated substrate material are consistent. Specifically, the pretreated substrate material is clamped using a placement fixture and placed vertically at a 90-degree angle into the nanowire growth solution. This vertical placement ensures that both surfaces of the pretreated substrate material are exposed to the same growth environment, preventing the pretreated substrate material from sinking to the bottom of the container containing the nanowire growth solution, which could lead to inconsistent growth on the upper and lower surfaces of the resulting oil-water separation membrane, thereby affecting separation performance. Furthermore, in step S6, the pretreated substrate material is hung at a 90-degree angle for drying.

[0060] The oil-water separation membrane obtained by the preparation method of the present invention is as follows Figure 5 As shown in (d) to (e), the oil-water separation membrane has an array of micropores, and copper hydroxide nanowires are present between the array micropores and inside each micropore; and the oil-water separation membrane appears blue.

[0061] The process flow for preparing the oil-water separation membrane using the above method is simple, and the growth of nanowires can be completed at room temperature and pressure, which greatly shortens the process flow and makes the manufacturing process safe and efficient. Moreover, since the nanowires can be formed in the perforated base material at room temperature and pressure, the thinner base material will not be deformed, which also greatly reduces the manufacturing cost of the oil-water separation membrane.

[0062] Example 3:

[0063] This embodiment differs from embodiment 2 in that the laser processing parameters include the array microhole diameter and array microhole spacing as well as laser parameters.

[0064] like Figure 5As shown in (c), the array micropore spacing refers to the center-to-center distance between adjacent micropores, including the horizontal spacing Δx between adjacent micropores in the horizontal direction and the vertical spacing Δy between adjacent micropores in the vertical direction. Laser parameters shown include laser pulse width, wavelength, laser scanning trajectory diameter d, and other parameters. In this embodiment, laser processing is performed using a picosecond UV laser device with a digital galvanometer. The laser beam emitted by the laser device is collimated and amplified by a 3x beam expander and focused onto the surface of the clean substrate material by a telecentric field lens with a focal length of 167 mm.

[0065] like Figure 5 As shown in (a) to (c), a picosecond ultraviolet laser with a pulse width of 10ps and a wavelength of 355nm is used for laser processing. The laser beam is collimated and amplified by a beam expander and focused on the surface of the substrate material by a telecentric field mirror with a focal length of 167mm. The digital galvanometer then drives the processing laser beam to scan along a circular path to form microholes. After a microhole is formed, the digital galvanometer jumps the processing laser beam to another hole position for continued processing until all microholes in the processing area are processed, thus forming an array of microholes.

[0066] Furthermore, step S3 also includes using a hollow fixture to clamp and fix the clean base material to ensure that the surface of the laser processing area in the clean base material is flat and wrinkle-free, and the laser processing area is always suspended. By placing it in the air, it can be avoided that after the micropores penetrate, the processing laser beam interacts with the material on the bottom surface of the clean base material, thereby deteriorating the quality of the micropores, thereby reducing the quality of the oil-water separation membrane. The clamping of the hollow fixture ensures that the surface of the laser processing area is flat and wrinkle-free, so that the entire processing area is at the laser focus position, ensuring the consistency of the array micropore processing. As a preferred embodiment, the hollow fixture contains a magnet, and the material of the hollow fixture is selected to be iron. When fixing, the clean base material is placed on the hollow fixture, and then the clean base material is clamped and fixed by the magnet.

[0067] Furthermore, the thickness and size of the substrate material can be determined based on the size of the oil-water separation membrane and application requirements. Once the substrate material is sized, it can be initially cut from large-scale, mass-produced raw material, such as copper foil. For example, if the diameter of the effective oil-water separation area of ​​the desired oil-water separation membrane is 20 cm, while ensuring convenient clamping with a hollow fixture and taking into account the principle of economy, the diameter of the laser-processed area of ​​the array micropores can be designed to be 22 cm, resulting in an overall diameter of the substrate material of 35 cm.

[0068] This embodiment uses a picosecond UV laser to process the micropore arrays. The shorter pulse width reduces thermal effects, while the shorter wavelength increases absorption, resulting in superior processing quality and cost-effectiveness for the micropore arrays. Furthermore, a digital galvanometer is used to drive the laser beam, resulting in high precision and high speed processing of the micropore arrays. The scanning speed and number of scans can be flexibly adjusted based on the thickness of the substrate material, as well as the diameter and spacing of the micropores according to different usage scenarios.

[0069] Example 4:

[0070] This embodiment differs from Embodiment 2 or 3 in that, in step S2, the nanowire growth solution is a mixture of sodium hydroxide solution and ammonium sulfate solution, and its configuration includes the following steps:

[0071] S21. Weighing sodium hydroxide solid and ammonium persulfate solid according to the growth solution parameters;

[0072] S22, prepare sodium hydroxide solution, stir evenly and cool to room temperature;

[0073] S23, dissolving the ammonium persulfate solid in the sodium hydroxide solution to prepare a mixed solution of ammonium persulfate, thereby obtaining a nanowire growth solution.

[0074] Example 5:

[0075] This embodiment uses any one of the preparation methods in Examples 2 to 4 to prepare the oil-water separation membrane of the present invention:

[0076] S1. Select a 30 μm thick copper foil as the substrate material and clean it in an ultrasonic cleaner using acetone, anhydrous ethanol, and deionized water in sequence for 20 minutes. Then blow dry with nitrogen to obtain a clean copper foil.

[0077] S2, preparing a nanowire growth liquid that reacts with the base material, stirring the nanowire growth liquid uniformly and cooling it to room temperature;

[0078] S21. Weighing sodium hydroxide solid and ammonium persulfate solid;

[0079] S22, prepare 0.625M sodium hydroxide solution, stir well and cool to room temperature;

[0080] S23, dissolving the ammonium persulfate solid in the sodium hydroxide solution to prepare a mixed growth solution containing 0.0325M ammonium persulfate;

[0081] S3. Set the array micropore diameter to 60 μm, the horizontal spacing, spacing Δx, and vertical spacing Δy to 120 μm, and the laser parameters to be: average laser power of 1.2 W, frequency of 200 kHz, scanning speed of 400 mm / s, and number of scans of 200 times; perform laser processing under the above laser processing parameters to obtain a perforated substrate material;

[0082] S4, ultrasonically cleaning the punched base material with dilute hydrochloric acid, anhydrous ethanol, and deionized water in sequence, and drying with nitrogen to obtain a pretreated base material;

[0083] S5, placing the pretreated substrate material in the nano growth solution in a manner of vertical immersion at 90 degrees, maintaining a nanowire growth time of 10 minutes to grow copper hydroxide nanowires, thereby obtaining a nanowire substrate material;

[0084] S6. The nanowire base material is rinsed with flowing anhydrous ethanol and deionized water in sequence, and hung at 90 degrees to dry naturally, thereby preparing the oil-water separation membrane of the present invention.

[0085] The diameter of the micropore array formed by the oil-water separation membrane obtained in this embodiment is approximately 67 μm. This diameter is slightly larger than the designed diameter because the laser spot itself has a certain diameter. As the center of the spot scans along the designed diameter, the radius of the spot outside the scanning path is expanded by a certain amount. The oil-water separation membrane obtained using these parameters has excellent separation performance, achieving a separation efficiency exceeding 99%.

[0086] Example 6:

[0087] This embodiment uses any one of the preparation methods in Examples 2 to 4 to prepare the oil-water separation membrane of the present invention. The difference between this embodiment and Example 5 lies in the difference in the parameters of the substrate material, the laser processing parameters, and the growth liquid parameters, specifically:

[0088] A 50 μm thick copper foil is used as the substrate material; the diameter of the array micropores in this embodiment is 100 μm; the horizontal spacing Δx and the vertical spacing Δy of the array micropores are both 200 μm; the laser parameters are: the average laser power is 0.3 W, the frequency is 50 kHz, the scanning speed is 100 mm / s, and the number of scans is 350 times. The diameter of the array micropores actually formed using the above laser parameters is about 108 μm. Figure 1 As shown in (a) and (b).

[0089] The nanowire growth solution contained 1.875M sodium hydroxide and 0.0975M ammonium persulfate. The nanowire growth time was 3 minutes. After the nanowire growth time expired, the nanowire copper foil was rinsed with anhydrous ethanol and then deionized water, followed by hanging in air at a 90-degree angle to air dry, thereby producing the oil-water separation membrane of the present invention.

[0090] It should be noted that the technical features in the above-mentioned embodiments 1 to 6 can be combined in any way, and the technical solutions formed by the combination all belong to the scope of protection of this application. In this article, terms such as "including", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0091] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An oil-water separation membrane comprising a perforated base material and nanowires, characterized in that: The perforated base material is a copper foil provided with an array of micropores, the array of micropores is formed by laser processing, and the array of micropores is composed of multiple micropores arranged in a regular pattern; the nanowires are copper hydroxide nanowires; the perforated base material is divided into a base area, a micropore edge area and a micropore wall area; the nanowires are distributed in the base area, the micropore edge area and the micropore wall area.

2. The oil-water separation membrane according to claim 1, wherein The nanowires in the base region are distributed in a network shape; the nanowires in the micropore edge region and the micropore wall region are mutually entangled, stacked and bundled; and the growth direction of the nanowires in the micropore wall region is perpendicular to the micropore wall.

3. A method for preparing an oil-water separation membrane, characterized in that: The method is used to prepare the oil-water separation membrane according to claim 1 or 2, comprising the following steps: S1. Selecting a substrate material, initially cleaning the substrate material, and drying it with protective gas to obtain a clean substrate material; S2, preparing a nanowire growth liquid that can react with the base material, stirring the nanowire growth liquid uniformly and cooling it to room temperature; S3, setting laser processing parameters, and processing the array micropores on the surface of the clean base material according to the laser processing parameters to obtain the perforated base material; S4, pre-treating the perforated base material to obtain a pre-treated base material; the pre-treating comprises performing a secondary cleaning on the perforated base material, and after the secondary cleaning, drying the base material again with the protective gas; S5. placing the pretreated base material in the nanowire growth solution at room temperature and pressure, and setting a nanowire growth time to allow the nanowires to grow in the pretreated base material to obtain a nanowire base material; S6. Wash the nanowire base material three times and then dry it naturally to obtain the oil-water separation membrane.

4. The preparation method according to claim 3, wherein The secondary cleaning is used to remove oxides in the perforated base material.

5. The preparation method according to claim 4, wherein The secondary cleaning comprises sequentially performing ultrasonic cleaning on the perforated base material using dilute hydrochloric acid, anhydrous ethanol, and deionized water.

6. The preparation method according to claim 5, wherein The first cleaning comprises sequentially performing ultrasonic cleaning on the substrate material using acetone, anhydrous ethanol and deionized water; the third cleaning comprises sequentially rinsing the nanowire substrate material using flowing anhydrous ethanol and deionized water.

7. The preparation method according to claim 5, wherein The step S3 further includes clamping and fixing the clean base material with a hollow fixture, so that the surface of the laser processing area in the clean base material is flat and wrinkle-free, and the laser processing area is always suspended.

8. The preparation method according to claim 7, wherein The pretreated substrate material is placed in the nanowire growth liquid in a vertical manner.

9. The preparation method according to claim 5, wherein The nanowire growth liquid is a mixture of sodium hydrogen peroxide solution and ammonium sulfate solution; the concentration of sodium hydroxide is 0.625M to 1.875M, and the concentration of ammonium persulfate is 0.0325M to 0.0975M.

10. The preparation method according to claim 9, characterized in that The configuration of the nanowire growth solution comprises the following steps: S21. Weighing sodium hydroxide solid and ammonium persulfate solid according to the growth solution parameters; S22, prepare sodium hydroxide solution, stir evenly and cool to room temperature; S23, dissolving the ammonium persulfate solid in the sodium hydroxide solution to prepare a mixed solution of the sodium hydroxide solution and ammonium persulfate, and stirring the mixed solution to obtain the nanowire growth solution.

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