Preparation method of oil-water separation surface with bionic staggered wetting characteristics

Abstract

The present invention discloses a method for preparing a surface with bionic staggered wetting characteristics for oil-water separation, belonging to the technical field of surface wetting modification of metallic copper foam. The method comprises pre-treating the copper foam; performing preliminary surface treatment of the copper foam by laser processing; preparing a micro-nano double-layer hierarchical structure: immersing the copper foam treated with preliminary laser processing in a silver nitrate solution for oxidation deposition for a preset time; preparing a first bionic staggered wetting surface: immersing the copper foam treated with oxidation deposition in an ethanol solution containing n-dodecyl mercaptan for a preset time to obtain a modified copper foam. Laser processing the surface of the modified copper foam obtains a surface with a micron-scale circular pit array structure; preparing a second bionic staggered wetting surface: spraying a hydrophobic spray on the surface of the copper foam treated with oxidation deposition to obtain the modified copper foam. Laser processing the surface of the modified copper foam obtains a surface with a micron-scale circular convex hull array structure. The bionic surface prepared by the present invention has excellent oil-water emulsion separation ability.

Description

Technical Field

[0001] The invention relates to the technical field of metal material surface modification, in particular to a method for preparing an oil-water separation surface with bionic staggered wetting characteristics. Background Art

[0002] Today, effective methods for separating oil and water from emulsions are urgently needed for two main reasons: First, oily wastewater from industries such as machining, oil extraction, and fuel production poses an increasingly severe threat to the ecological environment and human health; second, water-containing fuel not only degrades fuel quality but also causes severe engine corrosion. Due to the small, variable, and stable size of emulsion droplets, traditional separation methods struggle to achieve efficient oil-water separation.

[0003] In recent years, biomimetic oil-water separation surfaces have received widespread attention due to their excellent separation efficiency. However, traditional biomimetic oil-water separation surfaces have the following common problems: 1. To achieve high-efficiency separation, the separation pore size is usually much smaller than the emulsion droplet size, resulting in low separation flux, and the small pore size is easily clogged by the emulsion droplets; 2. During the continuous separation process, a "filter cake" will form on the surface, causing the separation flux to decrease. Obviously, increasing the pore size can significantly increase the separation flux, but this will inevitably lead to a decrease in separation efficiency or even separation failure. Therefore, in the field of emulsion oil-water separation, the difficulty of achieving both high efficiency and high flux is one of the important bottlenecks. Summary of the Invention

[0004] To address the technical issues existing in the prior art, this application proposes a method for preparing an oil-water separation surface with staggered wetting properties, which can resolve at least one of these issues. By leveraging the water-collecting mechanism of desert beetles in nature and combining the advantages of laser etching in adjusting the diameter and spacing of pits (convex hulls), this method creates a biomimetic oil-water separation surface with staggered wetting properties. This biomimetic oil-water separation surface has the advantages of low cost, simple fabrication, and high emulsion separation efficiency.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The method for preparing a bionic staggered wetting property oil-water separation surface comprises the following steps:

[0007] S1 pre-treats the copper foam: the copper foam is sequentially placed in dilute hydrochloric acid, acetone, and deionized water under ultrasonic vibration at room temperature, and then dried;

[0008] S2 laser processing: performing laser etching processing on the upper and lower surfaces of the copper foam pretreated in step S1;

[0009] S3: preparing a micro-nano double-layer hierarchical structure: immersing the copper foam obtained in S2 in a silver nitrate solution for oxidation deposition to obtain a micro-nano double-layer hierarchical structure and vacuum drying at a first preset temperature;

[0010] S4: preparing modified copper foam: performing surface modification on the micro-nano double-layer hierarchical structure obtained in step S3 to obtain modified copper foam;

[0011] S5 Preparation of bionic staggered wetting surface: The modified copper foam is laser etched to obtain a bionic staggered wetting surface.

[0012] A further improvement of the technical solution of the present invention is that the specific operations of step S4 and step S5 are to immerse the micro-nano double-layer hierarchical structure obtained in step S3 in an ethanol solution containing n-dodecanethiol, and vacuum dry it at a second preset temperature to obtain a modified copper foam, and the surface of the modified copper foam is laser etched to obtain a micron-scale circular pit array structure surface, wherein the micron-scale circular pit array structure surface is a first bionic staggered wetting surface.

[0013] A further improvement of the technical solution of the present invention is that the specific operations of step S4 and step S5 are to spray a hydrophobic spray on the surface of the micro-nano double-layer hierarchical structure obtained in step S3, and vacuum dry it at a third preset temperature to obtain a modified copper foam, and the modified copper foam is laser etched to obtain a micron-scale circular convex hull array structure surface, which is a second bionic staggered wetting surface.

[0014] The technical solution of the present invention is further improved in that: in step S1, the copper foam thickness is 3 mm, the porosity is 95-120 PPI, the copper foam laser processing power in step S2 is 13-16 W, the line filling spacing is 0.01 mm, the laser processing speed is 400-800 mm / s, the laser processing line spacing is 0.01 mm, the processing frequency is 20 kHz, the front and back sides of the pretreated copper foam are laser processed once each, and the silver nitrate concentration in step S3 is 0.035-0.088 mol / L.

[0015] A further improvement of the technical solution of the present invention is that in the preparation of the micro-nano double-layer hierarchical structure in step S3, the oxidation deposition time of the copper foam in the silver nitrate solution is 3-5 minutes, the first preset temperature is 70-80°C, and the drying time is 60-80 minutes.

[0016] A further improvement of the technical solution of the present invention is: the preparation method of the n-dodecyl mercaptan solution is as follows: 1-4 g of n-dodecyl mercaptan is added to 100 mL of ethanol to obtain a prefabricated solution, and the prefabricated solution is ultrasonically dispersed at room temperature for 2-10 minutes.

[0017] A further improvement of the technical solution of the present invention is that the copper foam is immersed in an ethanol solution containing n-dodecyl mercaptan for 8-12 hours, then taken out and vacuum dried at a second preset temperature of 60-70° C. for 30-40 minutes to obtain a modified copper foam.

[0018] A further improvement of the technical solution of the present invention is that: during the spraying of the hydrophobic spray, the hydrophobic spray is sprayed 1-3 times at a distance of 10-20 cm vertically from the center of the copper foam, and vacuum dried for 30-40 minutes at a third preset temperature of 60-70°C to obtain a modified copper foam.

[0019] A further improvement of the technical solution of the present invention is that the circular pits of the first bionic staggered wetting surface are arranged at equal intervals, the diameter of the circular pits is 0.2-0.6 mm, the circular pit spacing is 1-3 mm, the laser processing frequency is 20 kHz, the processing power is 0.8-2 W, the processing speed is 400-800 mm / s, the processing line spacing is 0.01 mm, the line filling spacing is 0.01 mm, and the laser processing is performed 1-2 times.

[0020] A further improvement of the technical solution of the present invention is that the circular convex hulls of the second bionic staggered wetting surface are arranged at equal intervals, the diameter of the circular convex hulls is 0.2-0.6 mm, the spacing between the circular convex hulls is 1-3 mm, the laser processing frequency is 20 kHz, the processing power is 0.8-2 W, the processing speed is 400-800 mm / s, the processing line spacing is 0.01 mm, the line filling spacing is 0.01 mm, and the laser processing is performed 1-2 times.

[0021] Due to the adoption of the above technical solution, the technical effects achieved by the present invention are as follows:

[0022] The present invention utilizes a porous copper foam, which is harmless to the human body, safe, and environmentally friendly, simple to manufacture, and amenable to large-scale production and processing. Furthermore, the copper foam exhibits excellent mechanical strength and stable performance, and its micro- and nanoscale pores facilitate the separation of micro- and nanoscale oil and water droplets. Upon oxidation and deposition in a silver nitrate solution, the copper foam forms a micron-scale maple leaf-like structure on its surface. This micron-scale maple leaf-like structure is extremely beneficial for increasing the surface roughness of the copper foam and reducing its pores. Smaller pores facilitate efficient oil-water emulsion separation. By leveraging the water-collecting mechanism on the back of a desert beetle and combining the advantages of laser etching in adjusting the diameter and spacing of circular pits (convex hulls), a first and second bionic interlaced wetting surface were fabricated. The bionic staggered wetting characteristics oil-water separation surface with appropriate circular pit diameter (circular convex hull diameter) and circular pit spacing (circular convex hull spacing) can realize the aggregation and screening of tiny droplets in the emulsifier, achieving better oil-water separation effect. Moreover, after multiple oil-water emulsion separations, the bionic staggered wetting characteristics oil-water separation surface still maintains excellent separation effect and has excellent recyclability and recoverability.

[0023] The preparation method described in this application is easy to operate and low-cost. Through selective laser processing, it can achieve the selective separation of oil-in-water emulsions and water-in-oil emulsions. Compared with previous methods that modify copper foam alone, the biomimetic staggered wetting properties of the oil-water separation surface have stronger oil-water separation capabilities and have strong application prospects in the treatment of oily wastewater in real-world applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flowchart of the method for preparing a biomimetic staggered wetting property oil-water separation surface;

[0025] Figure 2 A flow chart of a method for preparing a first and a second biomimetic staggered wetting surface;

[0026] Figure 3 A flowchart illustrating the application process;

[0027] Figure 4 a is the optical image of the original copper foam surface;

[0028] Figure 4 b is the optical image of the copper foam surface after preliminary laser etching;

[0029] Figure 4 c is an optical image of the copper foam surface with nano-double-layer hierarchical structure;

[0030] Figure 5 The third surface optical image in one embodiment of the present application;

[0031] Figure 6 This is the eighth surface optical image in one embodiment of the present application;

[0032] Figure 7 ab are optical images of the circular pit structures and circular convex hull structures on the third and eighth surfaces in the embodiment of the present application;

[0033] Figure 8 ab are equivalent measurement diagrams of the water contact angle in air of the first bionic staggered wetting surface and equivalent characterization diagrams of the water contact angle in air of the second bionic staggered wetting surface in the embodiment of this application;

[0034] Figure 9 a is a histogram of the separation efficiency of water-in-oil emulsion on the first surface, the second surface, the third surface, the fourth surface and the fifth surface;

[0035] Figure 9 b is a histogram of the separation flux of water-in-oil emulsion on the first surface, the second surface, the third surface, the fourth surface and the fifth surface;

[0036] Figure 10 a is a histogram of the oil-in-water emulsion separation efficiency on the sixth, seventh, eighth, ninth and tenth surfaces;

[0037] Figure 10 b is a histogram of the oil-in-water emulsion separation flux on the sixth surface, the seventh surface, the eighth surface, the ninth surface, and the tenth surface;

[0038] Figure 11 a is a bar graph showing the change in contact angle of a water droplet in the air around the circular pit on the third surface after different times of separation of the water-in-oil emulsion;

[0039] Figure 11 b is a bar graph showing the change in contact angle of an oil droplet in water around the circular convex hull on the eighth surface after different times of separation of the oil-in-water emulsion. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] In the detailed description that follows, reference may be made to the various drawings that form part of this application and illustrate specific embodiments of the present application. In the drawings, similar reference numerals describe substantially similar components in different figures. Each specific embodiment of the present application is described below in sufficient detail to enable a person of ordinary skill in the art to implement the technical solutions of the present application. It should be understood that other embodiments may be utilized or that structural, logical, or electrical changes may be made to the embodiments of the present application.

[0042] A method for preparing a bionic staggered wetting property oil-water separation surface, such as Figure 1 As shown, the following steps are included:

[0043] S1 pre-treats the copper foam: the copper foam is sequentially placed in dilute hydrochloric acid, acetone, and deionized water under ultrasonic vibration at room temperature, and then dried;

[0044] S2 laser processing: performing laser etching processing on the upper and lower surfaces of the copper foam pretreated in step S1;

[0045] S3: preparing a micro-nano double-layer hierarchical structure: immersing the copper foam obtained in S2 in a silver nitrate solution for oxidation deposition to obtain a micro-nano double-layer hierarchical structure and vacuum drying at a first preset temperature;

[0046] S4: preparing modified copper foam: performing surface modification on the micro-nano double-layer hierarchical structure obtained in step S3 to obtain modified copper foam;

[0047] S5 Preparation of bionic staggered wetting surface: The modified copper foam is laser etched to obtain a bionic staggered wetting surface.

[0048] The present application will be further described below with reference to the embodiments:

[0049] Figure 2 The flowchart of the method for preparing the oil-water separation surface with bionic staggered wetting characteristics in the embodiment of the present application is schematically shown; Figure 3 The schematic diagram of the preparation of the biomimetic staggered wetting characteristics oil-water separation surface in the embodiment of the present application is shown schematically. Figure 2 and Figure 3 As shown, the specific preparation method of the bionic staggered wetting characteristic oil-water separation surface is as follows:

[0050] S101, pre-treating the copper foam: placing the copper foam in dilute hydrochloric acid, acetone, and deionized water in sequence under ultrasonic vibration at room temperature, and drying;

[0051] S102, laser processing: preliminary treatment of the copper foam surface by laser processing;

[0052] S103, preparing a micro-nano double-layer hierarchical structure: preparing a silver nitrate aqueous solution of a preset concentration, ultrasonically vibrating, immersing the copper foam treated with the preliminary laser processing in the silver nitrate solution for oxidation deposition for a preset time to obtain a micro-nano double-layer hierarchical structure, and placing the copper foam after oxidation deposition under vacuum at a high temperature for a preset time;

[0053] S104, preparing a first biomimetic staggered wetting surface: immersing the copper foam treated with oxidation deposition in an ethanol solution containing n-dodecyl mercaptan, taking it out after soaking for a preset time, and vacuum drying it at a high temperature for a preset time to obtain a modified copper foam, and laser processing the surface of the modified copper foam to obtain a surface with a micron-scale circular pit array structure;

[0054] S105, preparing a second bionic staggered wetting surface: spraying a hydrophobic spray on the copper foam treated with oxidation deposition, vacuum drying it at high temperature for a preset time to obtain a modified copper foam, and laser processing the surface of the modified copper foam to obtain a micron-scale circular convex hull array structure surface.

[0055] The present application adopts a metallic copper foam with a porous structure, which has excellent mechanical strength and stable performance. The unique three-dimensional structure and micro-nano pores of the copper foam itself are conducive to the separation of oil and water. At the same time, the double-layer bionic hierarchical structure formed by silver particles on the surface of the copper foam greatly reduces the pores on the surface of the copper foam, which is beneficial to the screening and interception of tiny droplets in the emulsion. Moreover, the spike-shaped micro-nano bionic structure composed of silver particles is conducive to improving the demulsification ability of the oil-water separation surface with bionic staggered wetting characteristics for the emulsion. In the first bionic staggered wetting surface, the hydrophilic micron-scale circular pit structure can capture the water droplets of the oil-in-water emulsion and gradually gather into larger water droplets that are blocked by the bionic staggered wetting characteristics oil-water separation surface, while the oil can freely penetrate the surface and can efficiently separate the oil-in-water emulsion. On the second biomimetic staggered wetting surface, the oleophilic, micron-scale circular convex structures capture oil droplets in the oil-in-water emulsion and gradually aggregate them into larger droplets, which are then blocked by the biomimetic staggered wetting oil-water separation surface. Water can freely permeate the surface, effectively separating the oil-in-water emulsion. This biomimetic staggered wetting oil-water separation surface achieves both high-efficiency and high-throughput oil-water separation by leveraging the unique emulsion aggregation properties at pre-set locations on the interface. Furthermore, thanks to its unique biomimetic structure, the staggered wetting oil-water separation surface maintains high separation efficiency and flux even after multiple oil-water emulsion separations, demonstrating excellent recyclability and reusability.

[0056] In some embodiments of the present application, the copper foam was initially laser processed at a power of 13-16 W, a line fill spacing of 0.01 mm, a laser processing speed of 400-800 mm / s, a laser processing line spacing of 0.01 mm, and a processing frequency of 20 kHz. The pretreated copper foam was laser etched once on both the front and back sides. Laser processing of the copper foam increased its surface roughness, facilitating the adhesion of Ag nanoparticles to the copper foam surface during silver nitrate modification.

[0057] In some embodiments of the present application, the concentration of dilute hydrochloric acid is 0.5-1 mol / L, and the concentration of silver nitrate is 0.035-0.088 mol / L.

[0058] In some embodiments of the present application, during the preparation of the micro-nano bilayer hierarchical structure, the silver nitrate solution oxidation deposition time is 3-5 minutes, and the vacuum drying temperature is 70-80°C for 60-80 minutes. The oxidation deposition time of the copper foam after the initial laser treatment in the silver nitrate solution has a significant impact on its surface morphology. Only within this deposition time range can the optimal biomimetic maple leaf structure and the optimal surface porosity for oil-water emulsion separation be achieved.

[0059] In some embodiments of the present application, the preparation method of the n-dodecanethiol solution is as follows: 1-4 g of n-dodecanethiol is added to 100 mL of ethanol to obtain a prefabricated solution, and the prefabricated solution is ultrasonically dispersed at room temperature for 2-10 min.

[0060] In some examples of this application, a first biomimetic staggered wetting surface was prepared by immersing copper foam in an ethanol solution containing n-dodecanethiol for 8-12 hours, then removing it and drying it at 60-70°C under vacuum for 30-40 minutes. The n-dodecanethiol modification time significantly affects surface wettability; only within this time range can an optimal superhydrophobic surface be achieved.

[0061] In some embodiments of the present application, the first bionic staggered wetting surface has circular pits of the same size and arranged at equal intervals. In the laser-etched circular pit array, the circular pit diameter is 0.2-0.6 mm, the circular pit spacing is 1-3 mm, the laser processing frequency is 20 kHz, the processing power is 0.8-2 W, and the processing speed is 400-800 mm / s. The processing line spacing is 0.01 mm, the line filling spacing is 0.01 mm, and the laser processing is 1-2 times. In the laser processing preparation of the micron-scale circular pit array structure surface, a circular pit array surface structure is obtained on the copper foam surface under laser etching. The circular pit part has superhydrophilicity due to the change in roughness and surface energy under laser etching, and the part around the circular pit remains superhydrophobic. In the oil-in-water emulsion separation process, the superhydrophilic circular pits are conducive to capturing and collecting tiny water droplets in the emulsion and forming larger water droplets, preventing the water droplets from penetrating the bionic staggered wetting characteristics oil-water separation surface, which is conducive to achieving the separation of oil-in-water emulsions.

[0062] In some embodiments of the present application, the hydrophobic spray is applied 1-3 times at a distance of 10-20 cm vertically from the center of the copper foam, and then dried under vacuum at 60-70°C for 30-40 minutes. After modification by the hydrophobic spray, the surface energy of the copper foam is effectively reduced by its unique functional groups, forming a hydrophobic surface.

[0063] In some embodiments of the present application, in the second bionic staggered wetting surface, the circular convex hull array structure surface is laser processed, the circular convex hulls are of the same size and are arranged at equal intervals, the circular convex hull diameter is 0.2-0.6 mm, the circular convex hull spacing is 1-3 mm, the laser processing frequency is 20 kHz, the processing power is 0.8-2 W, and the processing speed is 400-800 mm / s. The processing line spacing is 0.01 mm, the line filling spacing is 0.01 mm, and the laser processing is 1-2 times. In the laser processing of the micron-scale circular convex hull array, a circular convex hull array surface structure is obtained on the copper foam surface under laser etching. The part around the circular convex hull has underwater superoleophobicity due to the change in surface roughness and surface energy caused by laser etching, and the circular convex hull still has superoleophilicity. In the process of separating oil-in-water emulsions, the superoleophilic circular convex hulls are conducive to capturing and collecting tiny oil droplets in the emulsion and forming larger oil droplets, preventing the oil droplets from passing through the bionic staggered wetting surface, which is conducive to achieving the separation of oil-in-water emulsions.

[0064] This application is inspired by the water collection mechanism on the back of desert beetles, and combines the advantages of lasers in preparing micro-nano structures. By laser etching, a micron-scale circular pit and circular convex hull array surface structure is prepared on the surface of modified copper foam to form a bionic staggered wetting surface. The present invention uses a metallic copper foam with a porous structure, which has excellent mechanical strength and more stable performance. The micron-scale porosity is conducive to the separation of micron-scale oil droplets and water droplets. By soaking in a silver nitrate solution, a maple leaf-shaped structure is formed on the surface of the copper foam skeleton. While improving the surface roughness, the pores on the copper foam surface are greatly reduced, ensuring the realization of oil-water emulsion separation. At the same time, the spike-like structure formed by the silver particles is conducive to improving the demulsification ability of the oil-water separation surface with bionic staggered wetting characteristics. The emulsion droplets are small in size and variable in size. To solve this problem, we propose two methods for preparing oil-water separation surfaces with staggered wetting characteristics, which can achieve both high efficiency and high throughput emulsion oil-water separation. These staggered wetting oil-water separation surfaces enable interfacial behavior that aggregates small droplets into larger ones, ultimately intercepting and separating these droplets. These two staggered wetting oil-water separation surfaces achieve high separation flux while maintaining high separation efficiency for oil-water emulsions. This holds great promise for practical application in oil-water separation of oily wastewater.

[0065] The above describes the process of the method for preparing a biomimetic staggered wetting oil-water separation surface proposed in this application through multiple embodiments. The following specific examples verify the technical advantages of the method for preparing a biomimetic staggered wetting oil-water separation surface proposed in this application.

[0066] To investigate the influence of factors such as circular dimple size and spacing on the separation efficiency and flux of oil-water emulsions on biomimetic staggered wetting surfaces, five different first biomimetic staggered wetting surfaces were fabricated on a 2×2 cm copper foam surface. The first biomimetic staggered wetting surface is a circular dimple array structure composed of different dimple diameters and dimple spacings. Within the dimple array structure, circular dimples of equal size are spaced evenly apart. The dimple diameters are 0.2 mm, 0.4 mm, and 0.6 mm, and the dimple spacings are 1 mm, 2 mm, and 3 mm.

[0067] Example 1

[0068] The first biomimetic staggered wetting surface composed of a circular pit array with a circular pit diameter of 0.4 mm and a circular pit spacing of 1 mm is named the first surface. The preparation method of the first surface includes the following steps:

[0069] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0070] Laser processing of copper foam: Copper foam with a size of 2 × 2 cm was initially laser processed to increase the surface roughness of the copper foam. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0071] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L. The deposition time was 4 minutes. After oxidation deposition, the copper foam was vacuum dried at 70°C for 70 minutes.

[0072] Preparation of the first biomimetic staggered wetting surface: The copper foam treated with the oxidative deposition treatment was immersed in an ethanol solution containing n-dodecyl mercaptan for 10 hours, then removed and vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to obtain a surface structured with a micron-scale circular pit array. The circular pits had a diameter of 0.4 mm and a pitch of 1 mm. The laser etching power was 1.2 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0073] In the first surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0074] Figure 9 a and Figure 9 b shows the separation efficiency and separation flux of the oil-in-water emulsion of the first surface, respectively. The separation efficiency and separation flux of the oil-in-water emulsion composed of toluene and water on the first surface are 92% and 2891 Lm, respectively. -2 h -1 .

[0075] Example 2

[0076] The first biomimetic staggered wetting surface composed of a circular pit array with a circular pit diameter of 0.2 mm and a circular pit spacing of 2 mm is named the second surface. The preparation method of the second surface includes the following steps:

[0077] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0078] Laser processing of copper foam: Copper foam with a size of 2 × 2 cm was initially laser processed to increase the surface roughness of the copper foam. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0079] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L. The deposition time was 4 minutes. After oxidation deposition, the copper foam was vacuum dried at 70°C for 70 minutes.

[0080] Preparation of the first biomimetic staggered wetting surface: The copper foam treated with the oxidative deposition treatment was immersed in an ethanol solution containing n-dodecyl mercaptan for 10 hours, then removed and vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to obtain a surface structured with a micron-scale circular pit array. The circular pits had a diameter of 0.2 mm and a pitch of 2 mm. The laser etching power was 1.2 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0081] In the second surface, the copper foam film is 3 mm thick and has a porosity of 95 PPI.

[0082] Figure 9 a and Figure 9 b shows the separation efficiency and separation flux of the oil-in-water emulsion of the second surface, respectively. The separation efficiency and separation flux of the oil-in-water emulsion composed of toluene and water on the second surface are 98.2% and 2773Lm, respectively. -2 h -1 .

[0083] Example 3

[0084] The first biomimetic staggered wetting surface composed of a circular pit array with a circular pit diameter of 0.4 mm and a circular pit spacing of 2 mm is named the third surface. The preparation method of the third surface includes the following steps:

[0085] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in sequence, and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt.

[0086] Laser processing of copper foam: Copper foam with a size of 2 × 2 cm was initially laser processed to increase the roughness of the copper foam surface. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0087] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L. The deposition time was 4 minutes. After oxidation deposition, the copper foam was vacuum dried at 70°C for 70 minutes.

[0088] Preparation of the first biomimetic staggered wetting surface: The copper foam treated with the oxidative deposition treatment was immersed in an ethanol solution containing n-dodecanethiol for 10 hours, then removed and vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to obtain a surface structured with a micron-scale circular pit array. The circular pits had a diameter of 0.4 mm and a pitch of 2 mm. The laser etching power was 1.2 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0089] In the third surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0090] Figure 9 a and Figure 9 b schematically shows the separation efficiency and separation flux of the oil-in-water emulsion of the third surface. The separation efficiency and separation flux of the oil-in-water emulsion composed of toluene and water on the third surface are 99.5% and 3212 Lm -2 h -1 .

[0091] Example 4

[0092] The first preset bionic staggered wetting property oil-water separation surface composed of a circular pit array with a circular pit diameter of 0.6 mm and a circular pit spacing of 2 mm is named the fourth surface. The preparation method of the fourth surface includes the following steps:

[0093] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0094] Laser processing of copper foam: Copper foam with a size of 2 × 2 cm was initially laser processed to increase the surface roughness of the copper foam. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0095] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L and the deposition time was 4 min. After oxidation deposition, it was vacuum dried at 70°C for 70 min.

[0096] To prepare the first biomimetic staggered wetting surface, the copper foam treated with the oxidative deposition treatment was immersed in an ethanol solution containing n-dodecyl mercaptan for 10 hours. The foam was then removed and vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched to create a surface with a micron-scale circular pit array structure. The pits had a diameter of 0.6 mm and a pitch of 2 mm. The laser etching power was 1.2 W, the processing speed was 500 mm / s, the line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0097] In the fourth surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0098] Figure 9 a and Figure 9 b schematically shows the separation efficiency and separation flux of the oil-in-water emulsion of the fourth surface. The separation efficiency and separation flux of the oil-in-water emulsion composed of toluene and water on the fourth surface are 97.5% and 3614Lm -2 h -1 .

[0099] Example 5

[0100] The first biomimetic staggered wetting surface composed of a circular pit array with a circular pit diameter of 0.4 mm and a circular pit spacing of 3 mm is named the fifth surface. The preparation method of the fifth surface includes the following steps:

[0101] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0102] Laser processing of copper foam: Copper foam with a size of 2 × 2 cm was initially laser processed to increase the surface roughness of the copper foam. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0103] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L. The deposition time was 4 minutes. After oxidation deposition, the copper foam was vacuum dried at 70°C for 70 minutes.

[0104] Preparation of the first biomimetic staggered wetting surface: The copper foam treated with the oxidative deposition treatment was immersed in an ethanol solution containing n-dodecyl mercaptan for 10 hours, then removed and vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to obtain a surface structured with a micron-scale circular pit array. The circular pits had a diameter of 0.4 mm and a pitch of 3 mm. The laser etching power was 1.2 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0105] In the fifth surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0106] Figure 9 a and Figure 9 b shows the oil-in-water emulsion separation efficiency and separation flux of the fifth surface, respectively. The separation efficiency and separation flux of the oil-in-water emulsion composed of toluene and water on the fifth surface are 98.6% and 3200 Lm, respectively. -2 h -1 .

[0107] Figure 4 a schematically shows the optical image of the original copper foam surface. Figure 4 b schematically shows the optical image of the copper foam surface after preliminary laser etching. Figure 4 c shows a schematic optical image of the copper foam surface with a hierarchical micro-nano double-layer structure. The original copper foam surface exhibits a smooth, porous network. After initial laser treatment, the surface roughness of the copper foam increases significantly. After oxidation and deposition in a silver nitrate solution, the tiny pores on the copper foam surface are fully filled.

[0108] Figure 5The third surface optical image in the embodiment of the present application is schematically shown. The third surface has a surface structure of a micron-scale circular pit array. The circular pits have a diameter of 0.4 mm, a spacing of 2 mm, and are of the same size and arranged at equal intervals.

[0109] Figure 7 a schematically shows an optical image of a circular pit in the third surface of an embodiment of the present application, where the Ag nanoparticles on the surface of the copper foam are laser etched away to expose the copper foam skeleton.

[0110] Figure 8 (a) Schematic representation of the surface wettability equivalent of the first biomimetic staggered wetting surface. After hydrophobic modification with n-dodecanethiol, the surface becomes superhydrophobic due to the reduced surface energy. The contact angle of a water droplet on the surface in the area not subjected to the second laser processing is greater than 150°. After the second laser processing, the laser-etched area becomes superhydrophilic due to the increased surface roughness and changed surface energy. The contact angle of a water droplet on the surface in air is 0°.

[0111] Combine Figure 9 a and Figure 9 The oil-in-water emulsion separation efficiency and separation flux bar graphs of the first, second, third, fourth and fifth surfaces shown in b show that the diameter of the circular pits and the distance between the circular pits have a great influence on the oil-in-water emulsion separation efficiency and separation flux. Among them, the third surface has the best oil-in-water emulsion separation efficiency and excellent separation flux. The separation efficiency reaches 99.5%. While ensuring good separation efficiency, it has an excellent separation flux in comparison, with a separation flux of 3212 Lm -2 h -1 The fourth surface has the best separation flux and excellent separation efficiency for oil-in-water emulsion separation, with separation efficiency and separation flux of 97.5% and 3614 Lm -2 h -1 .

[0112] Figure 11 Figure a schematically shows the change in the water contact angle in air around the circular pits on the third surface after different oil-in-water emulsion separations. The third surface demonstrates excellent reusability. After multiple oil-water separation experiments, the area surrounding the circular pits on the third surface demonstrates superhydrophobicity, with the surface's water contact angle in air remaining above 150° after 10 oil-water separations.

[0113] To investigate the influence of factors such as the size and spacing of circular convex hulls on the emulsifier separation efficiency and flux of an oil-water separation surface with biomimetic staggered wetting, five different second biomimetic staggered wetting surfaces were fabricated on a 2×2 cm copper foam surface. The second biomimetic staggered wetting surface consists of a circular convex hull array structure composed of different circular convex hull diameters and spacings. Within the circular convex hull array structure, circular convex hulls of identical size are spaced evenly apart. The circular convex hull diameters are 0.2 mm, 0.4 mm, and 0.6 mm, and the circular convex hull spacings are 1 mm, 2 mm, and 3 mm.

[0114] Example 6

[0115] The second preset bionic staggered wetting property oil-water separation surface with a circular convex hull diameter of 0.4 mm and a circular convex hull spacing of 1 mm is named the sixth surface. The preparation method of the sixth surface includes the following steps:

[0116] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0117] Laser processing of copper foam: Copper foam with a size of 2 × 2 cm was initially laser processed to increase the roughness of the copper foam surface. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0118] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L. The deposition time was 4 minutes. After oxidation deposition, the copper foam was vacuum dried at 70°C for 70 minutes.

[0119] To prepare a second biomimetic staggered wetting surface, a hydrophobic spray was sprayed onto the copper foam surface treated with oxidative deposition. The surface was then vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to create a surface with a micron-scale circular convex hull array structure. The hull diameter was 0.4 mm, the hull spacing was 1 mm, and the laser etching power was 1.2 W. The processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0120] In the sixth surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0121] Figure 10 a and Figure 10b shows the separation efficiency and separation flux of the water-in-oil emulsion of the sixth surface. The separation efficiency and separation flux of the water-in-oil emulsion composed of water and toluene on the sixth surface are 98.5% and 3258 Lm, respectively. -2 h -1 .

[0122] Example 7

[0123] The second preset bionic staggered wetting property oil-water separation surface with a circular convex hull diameter of 0.2 mm and a circular convex hull spacing of 2 mm is named the seventh surface. The preparation method of the seventh surface includes the following steps:

[0124] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0125] Laser processing of copper foam: Copper foam with a size of 2×2 cm was preliminarily laser processed to increase the rough structure of the copper foam surface. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0126] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L. The deposition time was 4 minutes. After oxidation deposition, the copper foam was vacuum dried at 70°C for 70 minutes.

[0127] To prepare a second biomimetic staggered wetting surface, a hydrophobic spray was sprayed onto the copper foam surface treated with oxidative deposition. The surface was then vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to create a surface with a micron-scale circular convex hull array structure. The hull diameter was 0.2 mm, the hull spacing was 2 mm, and the laser etching power was 1.2 W. The processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0128] In the seventh surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0129] Figure 10 a and Figure 10 b shows the separation efficiency and separation flux of the oil-in-water emulsion of the seventh surface. The separation efficiency and separation flux of the oil-in-water emulsion composed of water and toluene on the seventh surface are 97.5% and 4256 Lm, respectively. -2 h -1 .

[0130] Example 8

[0131] The second preset bionic staggered wetting property oil-water separation surface with a circular convex hull diameter of 0.4 mm and a circular convex hull spacing of 2 mm is named the eighth surface. The preparation method of the eighth surface includes the following steps:

[0132] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0133] Laser processing of copper foam: Copper foam with a size of 2×2 cm was preliminarily laser processed to increase the rough structure of the copper foam surface. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0134] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L. The deposition time was 4 minutes. After oxidation deposition, the copper foam was vacuum dried at 70°C for 70 minutes.

[0135] To prepare a second biomimetic staggered wetting surface, a hydrophobic spray was sprayed onto the copper foam surface treated with oxidative deposition. The surface was then vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to create a surface with a micron-scale circular convex hull array structure. The hull diameter was 0.4 mm, the hull spacing was 2 mm, and the laser etching power was 1.2 W. The processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0136] In the eighth surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0137] Figure 10 a and Figure 10 b shows the separation efficiency and separation flux of the water-in-oil emulsion of the eighth surface. The separation efficiency and separation flux of the water-in-oil emulsion composed of water and toluene on the eighth surface are 99.3% and 3458 Lm, respectively. -2 h -1 .

[0138] Example 9

[0139] The second preset bionic staggered wetting property oil-water separation surface with a circular convex hull diameter of 0.6 mm and a circular convex hull spacing of 2 mm is named the ninth surface. The preparation method of the ninth surface includes the following steps:

[0140] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0141] Laser processing of copper foam: Copper foam with a size of 2×2 cm was preliminarily laser processed to increase the rough structure of the copper foam surface. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0142] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L and the deposition time was 4 min. After oxidation deposition, it was vacuum dried at 70°C for 70 min.

[0143] To prepare a second biomimetic staggered wetting surface, a hydrophobic spray was sprayed onto the copper foam surface treated with oxidative deposition. The surface was then vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to create a surface with a micron-scale circular convex hull array structure. The hull diameter was 0.6 mm, the hull spacing was 2 mm, and the laser etching power was 1.2 W. The processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0144] In the ninth surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0145] Figure 10 a and Figure 10 b schematically shows the separation efficiency and separation flux of the ninth surface for the oil-in-water emulsion. The ninth surface has a separation efficiency and separation flux of 97.9% and 3192 Lm3 for the oil-in-water emulsion composed of water and toluene, respectively. -2 h -1 .

[0146] Example 10

[0147] The second preset bionic staggered wetting property oil-water separation surface with a circular convex hull diameter of 0.4 mm and a circular convex hull spacing of 3 mm is named the tenth surface. The preparation method of the tenth surface includes the following steps:

[0148] Pre-treat the copper foam: soak it in acetone, distilled water, and ethanol in turn and ultrasonically vibrate it for ten minutes to remove the surface oxide film and dirt;

[0149] Laser processing of copper foam: Copper foam with a size of 2×2 cm was preliminarily laser processed to increase the rough structure of the copper foam surface. The laser processing power was 14 W, the processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line filling spacing was 0.01 mm, the processing frequency was 20 kHz, and the front and back sides were processed once.

[0150] Preparation of micro-nano double-layer hierarchical structure: copper foam was immersed in silver nitrate solution for oxidation deposition. The concentration of silver nitrate solution was 0.05 mol / L and the deposition time was 4 min. After oxidation deposition, it was vacuum dried at 70°C for 70 min.

[0151] To prepare a second biomimetic staggered wetting surface, a hydrophobic spray was sprayed onto the copper foam surface treated with oxidative deposition. The surface was then vacuum-dried at 60°C for 35 minutes to produce a modified copper foam. The modified copper foam was then laser-etched again to create a surface with a micron-scale circular convex hull array structure. The hull diameter was 0.4 mm, the hull spacing was 3 mm, and the laser etching power was 1.2 W. The processing speed was 500 mm / s, the processing line spacing was 0.01 mm, the line fill spacing was 0.01 mm, and the processing frequency was 20 kHz.

[0152] In the tenth surface, the copper foam film has a thickness of 3 mm and a porosity of 95 PPI.

[0153] Figure 10 a and Figure 10 b shows the separation efficiency and separation flux of the water-in-oil emulsion of the tenth surface. The separation efficiency and separation flux of the water-in-oil emulsion composed of water and toluene on the tenth surface are 96% and 4389 Lm, respectively. -2 h -1 .

[0154] Figure 6 The optical image of the eighth surface in the embodiment of the present application is schematically shown. The eighth surface has a micron-scale circular convex hull array surface structure. The circular convex hulls have a diameter of 0.4 mm, a spacing of 2 mm, and are of the same size and arranged at equal intervals.

[0155] Figure 7 b schematically shows an optical image of a circular convex hull in the eighth surface in an embodiment of the present application. The Ag nanoparticles around the circular convex hull on the copper foam surface are laser etched to expose the copper foam skeleton.

[0156] Figure 8b shows a schematic representation of the surface wettability of the second biomimetic staggered wetting surface. After hydrophobic spray modification, the copper foam surface becomes superhydrophobic due to changes in surface energy and surface roughness. The contact angle of a water droplet on the surface in the area not subjected to the second laser processing is greater than 150°. After the second laser processing, the laser-etched area becomes superhydrophilic due to increased surface roughness and changes in surface energy, with a contact angle of 0° between the water droplet and the surface.

[0157] Combine Figure 10 a and Figure 10 b shows the bar graph of the separation efficiency and separation flux of the oil-in-water emulsion of the sixth, seventh, eighth, ninth and tenth surfaces. We found that the diameter of the circular convex hull and the distance between the circular convex hulls have a great influence on the separation efficiency and separation flux of the oil-in-water emulsion. Among them, the eighth surface has the best separation efficiency and excellent separation flux of the oil-in-water emulsion. The separation efficiency reaches 99.3%. While ensuring good separation efficiency, it has an excellent separation flux, which reaches 3458 Lm -2 h -1 The tenth surface has the best separation flux and excellent separation efficiency for oil-in-water emulsion separation, with separation efficiency and separation flux of 96% and 4389 Lm respectively. -2 h -1 .

[0158] Figure 11 b schematically shows a bar graph of the change in the oil contact angle in water on the surface surrounding the circular convex hull structure of the eighth surface after different times of oil-in-water emulsion separation. Chloroform was selected for testing, and it was found that the eighth surface has excellent reusability. After multiple oil-water separation experiments, the area surrounding the circular convex hull of the eighth surface was tested to have underwater superoleophobicity, and the surface oil contact angle in water remained above 150° after 10 oil-water separations.

[0159] In summary, inspired by the water-collecting mechanism on the back of desert beetles and combining the advantages of laser etching in adjusting the diameter and spacing of pits (convex hulls), a biomimetic staggered wetting oil-water separation surface was fabricated. This laser etching method offers advantages such as high automation, precise control of experimental parameters, high machining accuracy, and ease of fabricating fine microstructures. Laser etching successfully created pre-defined interfacial sites on the copper foam surface where microemulsions can aggregate, achieving both high-efficiency and high-throughput oil-water separation. This method is simple to operate and has low operating costs. It exhibits superior separation efficiency for the more difficult oil-in-water and water-in-oil emulsions. Due to its unique biomimetic structure, the staggered wetting oil-water separation surface maintains excellent separation efficiency after multiple oil-water emulsion separations, demonstrating the recyclability and recoverability of the biomimetic staggered wetting oil-water separation surface. This application has potential applications in both academic and industrial fields.

[0160] The above embodiments are for illustration purposes only and are not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the scope of the present invention. Therefore, all equivalent technical solutions should also fall within the scope of the present invention.

Claims

1. Preparation method of oil-water separation surface with bionic staggered wetting characteristics, characterized by The following steps are involved: S1 pre-treats the copper foam: copper foam with a thickness of 3 mm and a porosity of 95-120 PPI is placed in dilute hydrochloric acid, acetone, and deionized water in turn, and ultrasonically shaken at room temperature, and then dried. The concentration of the dilute hydrochloric acid is 0.5-1 mol / L. S2 laser processing: laser etching the upper and lower surfaces of the copper foam pretreated in step S1, with a laser processing power of 13-16 W, a line filling spacing of 0.01 mm, a laser processing speed of 400-800 mm / s, a laser processing line spacing of 0.01 mm, a processing frequency of 20 kHz, and laser processing of the front and back surfaces of the pretreated copper foam once each; S3: preparing a micro-nano double-layer hierarchical structure: immersing the copper foam obtained in S2 in a silver nitrate solution with a concentration of 0.035-0.088 mol / L for oxidation deposition for 3-5 minutes to obtain a micro-nano double-layer hierarchical structure, and vacuum drying the structure at a first preset temperature of 70-80° C. for 60-80 minutes. S4: preparing modified copper foam: performing surface modification on the micro-nano double-layer hierarchical structure obtained in step S3 to obtain modified copper foam; S5 Preparation of bionic staggered wetting surface: The modified copper foam is laser etched to obtain a bionic staggered wetting surface; Immersing the micro-nano double-layer hierarchical structure obtained in step S3 in an ethanol solution containing n-dodecanethiol and vacuum drying at a second preset temperature to obtain a modified copper foam, and laser etching the surface of the modified copper foam to obtain a micron-scale circular pit array structure surface, wherein the micron-scale circular pit array structure surface is a first biomimetic staggered wetting surface; The surface of the micro-nano double-layer hierarchical structure obtained in step S3 is sprayed with a hydrophobic spray, and vacuum dried at a third preset temperature to obtain a modified copper foam. The modified copper foam is laser etched to obtain a micron-scale circular convex hull array structure surface, which serves as a second bionic staggered wetting surface. The circular pits of the first bionic staggered wetting surface are arranged at equal intervals, with a diameter of 0.2-0.6mm and a spacing between circular pits of 1-3mm. The laser processing frequency is 20kHz, the processing power is 0.8-2W, the processing speed is 400-800mm / s, the processing line spacing is 0.01mm, the line filling spacing is 0.01mm, and the laser processing is performed 1-2 times; the circular convex hulls of the second bionic staggered wetting surface are arranged at equal intervals, with a diameter of 0.2-0.6mm and a spacing between circular convex hulls of 1-3mm. The laser processing frequency is 20kHz, the processing power is 0.8-2W, the processing speed is 400-800mm / s, the processing line spacing is 0.01mm, the line filling spacing is 0.01mm, and the laser processing is performed 1-2 times.

2. The method for preparing a bionic staggered wetting property oil-water separation surface according to claim 1, characterized in that: The preparation method of the n-dodecyl mercaptan solution is as follows: 1-4 g of n-dodecyl mercaptan is added to 100 mL of ethanol to obtain a prefabricated solution, and the prefabricated solution is ultrasonically dispersed at room temperature for 2-10 minutes.

3. The method for preparing a bionic staggered wetting property oil-water separation surface according to claim 2, characterized in that: The copper foam is immersed in an ethanol solution containing n-dodecyl mercaptan for 8-12 hours, taken out, and vacuum dried at a second preset temperature of 60-70° C. for 30-40 minutes to obtain a modified copper foam.

4. The method for preparing a bionic staggered wetting property oil-water separation surface according to claim 1, characterized in that: During the spraying of the hydrophobic spray, the hydrophobic spray is sprayed 1-3 times at a distance of 10-20 cm vertically from the center of the copper foam, and vacuum dried at a third preset temperature of 60-70° C. for 30-40 minutes to obtain a modified copper foam.

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