Preparation method and application of double-sided super-hydrophobic and super-oleophylic copper mesh

Abstract

The invention relates to the technical field of functional materials and oil-water separation, in particular to a preparation method and application of a double-sided super-hydrophobic-super-oleophylic copper mesh. The method comprises the following steps: ultrasonically cleaning a copper mesh substrate with diluted hydrochloric acid, acetone and the like; taking the pretreated copper mesh as a cathode and a graphite flake as an anode, performing electrochemical deposition in a carbon-containing electrolyte at a constant low voltage of 2.0-3.5 V, and controlling the area ratio of the cathode to the anode to be 1: 1-1: 4; after deposition, cleaning and drying to obtain the copper mesh coated with diamond-like carbon films on both sides, wherein the water contact angles on both sides exceed 150 degrees and the copper mesh is resistant to acid, alkali and salt; the copper net is applied to material characterization, wetting and oil-water separation performance testing. According to the invention, the metal-based oil-water separation net realizes double-sided super-hydrophobic and super-oleophylic effects and has bidirectional and reversible separation capability.

Description

Technical Field

[0001] The present invention relates to the technical field of functional materials and oil-water separation, and in particular to a preparation method and application of a double-sided super-hydrophobic-super-oleophilic copper mesh. Background Art

[0002] The increasing pollution problems of industrial oily wastewater and marine oil spills necessitate the development of efficient, environmentally friendly, and durable oil-water separation materials. Traditional separation technologies (such as gravity sedimentation, flotation, and adsorption) are inefficient when treating emulsified or highly viscous oils and are prone to secondary contamination. While effective, membrane separation technology suffers from membrane fouling, poor stability, and complex preparation processes.

[0003] Superhydrophobic materials, due to their special wettability (superhydrophobic, superoleophilic or superhydrophilic, superoleophobic), show great potential in the field of oil-water separation. Metal mesh (such as copper mesh) as a porous substrate has the advantages of low cost, high porosity, and good flexibility, making it an ideal candidate for oil-water separation filter material. However, in the existing technology, the superhydrophobic layer constructed on the surface of copper mesh by chemical etching or solution immersion has problems such as fragile structure, poor durability, poor corrosion resistance, and difficulty in achieving uniform double-sided modification.

[0004] Electrochemical deposition technology, with its uniform and highly controllable film formation, is an effective means of constructing stable superhydrophobic surfaces. Diamond-like carbon (DLC) films, with their high hardness, chemical inertness, corrosion resistance, and exceptional wettability, are ideal coatings for enhancing copper mesh performance. However, existing metal-based oil-water separation meshes still struggle to achieve uniform, highly durable superhydrophobic and superoleophilic coatings on both sides, particularly with bidirectional, reversible separation capabilities. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method and application of a double-sided super-hydrophobic-super-oleophilic copper mesh, so as to solve the problem of how to make a metal-based oil-water separation mesh achieve double-sided super-hydrophobicity and super-oleophilicity, and have bidirectional and reversible separation capabilities.

[0006] In a first aspect, the present invention discloses a method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh, comprising the following steps:

[0007] S1, ultrasonically clean the copper mesh substrate with dilute hydrochloric acid, acetone, ethanol, and deionized water in sequence to remove surface contaminants;

[0008] S2, electrochemical deposition, using a pretreated copper mesh as the cathode and a graphite sheet as the anode in a carbon-containing electrolyte, electrochemical deposition is performed at a constant low voltage. During the deposition process, the area ratio of the cathode to the anode is controlled at 1:1 to 1:4;

[0009] S3, after the deposition is completed, the copper mesh is taken out, cleaned and dried to obtain a super-hydrophobic-super-oleophilic copper mesh with diamond-like carbon (DLC) film uniformly covered on both sides.

[0010] Specifically, the carbon-containing electrolyte in S2 is an ionic liquid with a molar ratio of choline chloride to ethylene glycol of 1:2.

[0011] Specifically, the constant low voltage in S2 is 2.0V-3.5V.

[0012] More specifically, the constant low voltage is 2.75V.

[0013] Specifically, the deposition time in S2 is 10-30 minutes.

[0014] More specifically, the deposition time is 15 minutes.

[0015] Optimally, the cathode to anode area ratio in S2 is 1:3 to 1:4.

[0016] Specifically, the cathode in S2 is a copper mesh with a pore size of 75 microns and a copper wire diameter of 45 microns, and the anode is a high-purity graphite sheet.

[0017] Specifically, the DLC films on both sides of the copper mesh have a micro-nano composite rough structure, and the water contact angles on both sides are greater than 150°. After being immersed in a pH 1-13 aqueous solution and 3.5% salinity salt water for 30 days, the water contact angles are still greater than 150°.

[0018] In the second aspect, the present invention discloses an application of a double-sided super-hydrophobic-super-oleophilic copper mesh, a preparation method applied to the above-mentioned double-sided super-hydrophobic-super-oleophilic copper mesh, material characterization, wetting performance testing, and oil-water separation performance testing.

[0019] The beneficial effects of the present invention are:

[0020] The present invention solves the problem of how to make a metal-based oil-water separation net achieve double-sided super-hydrophobicity and super-oleophilicity, as well as bidirectional and reversible separation capabilities. The metal-based oil-water separation net (such as a copper net) is uniformly covered with a diamond-like carbon (DLC) film on both sides, presenting a micro-nano composite rough structure, achieving double-sided super-hydrophobicity (water contact angles are greater than 150°, and super-hydrophobicity is maintained for aqueous solutions with different pH values ​​and simulated seawater) and super-oleophilicity (contact angles for various oils are close to 0°). As a separation filter material, the separation efficiency for various oil-water mixtures is as high as over 99.5%, and both sides can serve as effective separation surfaces, with bidirectional and reversible separation capabilities, which can adapt to different working conditions. At the same time, it has excellent cyclic stability (efficiency remains above 90% after 20 repeated separations), oil stain resistance, and strong adsorption. The preparation method is simple, environmentally friendly, and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Shown are Raman spectra of DLC films deposited at different area ratios.

[0022] Figure 2 Shown are transmission electron microscopy (TEM) images and electron diffraction patterns of DLC films.

[0023] Figure 3 Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:1.

[0024] Figure 4 Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:2.

[0025] Figure 5 Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:3.

[0026] Figure 6 Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:4.

[0027] Figure 7 Shown are SEM comparison images of the copper sheet and the copper mesh under the same deposition conditions (area ratio 1:4).

[0028] Figure 8 Shown is a schematic diagram of the principle of DLC deposition on copper sheets and copper mesh at different anode and cathode area ratios.

[0029] Figure 9 Shown are the contact angles of the copper mesh after deposition of different anode sizes and the difference in contact angles between the front and back surfaces.

[0030] Figure 10 Shown are the contact angle diagrams of aqueous solutions with different pH values ​​on copper grids.

[0031] Figure 11 Shown are contact angle diagrams of copper meshes immersed in salt water for different times.

[0032] Figure 12 Shown are photographs of oil droplets (penetration) and water droplets (spherical) on the surface of a copper mesh.

[0033] Figure 13 Shown is a sequence diagram of the oil absorption capacity test of the super-hydrophobic copper mesh.

[0034] Figure 14 Shown is a test diagram of the hydrophobic performance of a super-hydrophobic copper mesh under oil (water droplets rolling in oil).

[0035] Figure 15 Shown is a photo of the oil-water separation effect.

[0036] Figure 16 Shown is a graph showing the separation efficiency of copper mesh for different types of oil.

[0037] Figure 17 Shown are the results of the repetitive separation experiment (cyclic stability) of copper mesh deposited with different anode areas.

[0038] Figure 18 Shown is a comparison of the results of repetitive separation experiments on the front and back sides of the copper mesh. DETAILED DESCRIPTION

[0039] To facilitate understanding of the present invention, the present invention will be described more fully below in conjunction with the specific embodiments. Preferred embodiments of the present invention are provided in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0041] Example 1: This example provides a method for preparing a double-sided super-hydrophobic and super-oleophilic copper mesh, and the specific steps are as follows:

[0042] Step 1: Take a 1 cm × 1 cm square copper mesh (copper wire diameter 45 μm, pore size 75 μm), and ultrasonically clean it with dilute HCl (to remove oxides on the surface of the copper sheet), acetone (to clean oil stains on the surface of the copper sheet), ethanol and deionized water (to remove residual debris on the surface of the copper mesh) for 5 minutes each, and place it in air to dry.

[0043] Step 2, prepare the electrolyte: mix choline chloride and ethylene glycol in a molar ratio of 1:2, heat to 60°C and stir until it becomes a transparent liquid.

[0044] In step 3, the cleaned copper mesh was used as the cathode, and high-purity graphite sheets of 1cm×1cm, 2cm×2cm, 3cm×3cm, and 4cm×4cm were selected as the anodes, with a fixed distance of 5mm between the two electrodes. Among the four anodes, the copper mesh deposited with the 4cm×4cm high-purity graphite sheet exhibited the best superhydrophobicity and oil-water separation capabilities, and achieved the best results in this application.

[0045] Step 4: Immerse the electrode system in the electrolyte, connect a DC power supply (Elektro-Automatik, EA-PS9080-402U, Germany), apply a constant voltage of 2.75 V at room temperature, and deposit for 15 minutes.

[0046] Step 5: After the deposition is complete, remove the copper mesh, rinse it with deionized water, and dry it. The resulting sample needs to be placed in air for about 10 days before performance testing.

[0047] The copper mesh prepared by the above-mentioned preparation method of double-sided super-hydrophobic-super-oleophilic copper mesh has the following characteristics: surface morphology, both sides are covered with uniform DLC film. The film presents a micro-nano composite rough structure (such as needle-shaped, snowflake-shaped or granular structure) with hierarchical characteristics; this structure is the basis of super-hydrophobicity. When the anode and cathode area ratio is 1:3 to 1:4, the morphology of the front and back surfaces is highly consistent. Chemical structure, the DLC film is sp 2 (graphite phase) and sp 3 (Diamond phase) An amorphous structure of mixed carbon bonds, which may contain nano-diamond clusters and nano-graphite clusters. It has wettability. Super hydrophobicity, the water contact angles on both sides are greater than 150°, reaching the super hydrophobic level. Key advantages: This super hydrophobicity has excellent durability and corrosion resistance. The contact angles of aqueous solutions with different pH values ​​(1-13) are maintained above 155°. After immersion in simulated seawater with a salinity of 3.5% for 30 days, the water contact angle is still greater than 150°. Super oleophilicity, the contact angle for a variety of oils (such as gasoline, kerosene, glycerin, and cooking oil) is close to 0°, showing super oleophilic properties. Oil-water separation performance, as a separation filter material, the copper mesh has the following outstanding properties. High efficiency: The separation efficiency of a variety of oil-water mixtures (oil-water volume ratio 1:1) is as high as over 99.5%. Bidirectionality and reversibility: Both the front and back sides of the copper mesh can be used as effective separation surfaces, and there is no obvious difference in separation efficiency. Bidirectional and reversible separation can be achieved to meet the needs of different working conditions. This is the key advantage of the present invention compared to single-sided modified materials. Cyclic stability: After 20 repeated oil-water separation cycles, the separation efficiency can still be maintained at more than 90% (preferably a sample prepared with an anode and cathode area ratio of 1:4). In contrast, the sample with an area ratio of 1:1 has poor cyclic stability. Oil resistance, it can still maintain super hydrophobicity in an oily environment, and water droplets can roll on the tilted copper mesh surface in the oil, indicating excellent oil resistance. Strong adsorption, it has strong adsorption capacity for oil droplets.

[0048] Example 2: This example provides an application of a double-sided super-hydrophobic-super-oleophilic copper mesh, and performs performance tests in terms of material characterization, wetting, and oil-water separation. The specific steps are as follows.

[0049] Material characterization and wetting performance testing:

[0050] Step 1, SEM (refer to Figure 3-7) and observed the morphologies of the front and back surfaces of samples with different area ratios. The results showed that at an area ratio of 1:1, the front surface exhibited needle-like / snowflake-like structures, while the back surface was less abundant and uneven. At 1:2, the front surface had a more uniform structure, while the back surface was primarily granular. At 1:3, leaf-like structures appeared on both the front and back surfaces, but the back surface was still slightly less granular. At 1:4, the morphologies of both surfaces were highly consistent, with both surfaces exhibiting granular and micro-nanostructures. Under the same conditions (1:4), the difference between the front and back surfaces of the copper sheet was minimal, demonstrating that increasing the anode area facilitates electric field penetration and double-sided deposition.

[0051] Step 2, Raman (refer to Figure 1 ), all samples showed characteristic peaks at 1360cm-1 (D peak) and 1570cm-1 (G peak), confirming the DLC structure. When the anode area increases, the G peak broadens and moves to a lower wave number, indicating that sp 3 The content increases and the film quality improves. Other peaks (1200cm-1, 1750cm-1) indicate the presence of sp 3 Vibration and surface oxidation.

[0052] Step 3, TEM (refer to Figure 2 ): It is confirmed that the DLC film is an amorphous carbon matrix, in which nanocrystal clusters with interplanar spacing of 0.205 nm (corresponding to diamond (111)) and 0.336 nm (corresponding to graphite (002)) are embedded, which is further supported by electron diffraction rings.

[0053] Step 4, contact angle (reference Figure 9-12 ), and 67° (hydrophilic) for pure copper mesh; after deposition, as the anode area increases, the contact angle increases significantly (1:1-123°, 1:2-132°, 1:3-145°, 1:4-157°). Key point: Increasing the anode area significantly reduces the difference in contact angle between the front and back surfaces (reference Figure 9 ), improve uniformity.

[0054] The above steps yielded the following results: Super hydrophobicity, with an area ratio of 1:3 and 1:4, and a water contact angle of >150° (super hydrophobicity). Corrosion resistance, with a pH 1-13 solution contact angle of >155° (reference Figure 10 After immersion in 3.5% saline for 30 days, the contact angle is still >150° (reference Figure 11 It has super lipophilicity, and the contact angle to various oils (gasoline, kerosene, glycerin, cooking oil) is ≈0° (reference Figure 12 ). With oil resistance, water droplets can roll on the surface of the copper mesh tilted in oil (reference Figure 14 ). It has strong adsorption properties and can strongly absorb underwater oil droplets (reference Figure 13 ).

[0055] Performance test of oil-water separation:

[0056] Step 1: Sandwich the prepared copper mesh between two transparent glass tubes.

[0057] Step 2: Prepare the sample as an oil-water mixture (oil:water=1:1v / v). Oils include gasoline, kerosene, glycerin, and cooking oil (which can be dyed for easier observation, such as red for oil and blue for water).

[0058] Step 3: Pour the mixed liquid into the upper end of the device and rely on gravity or slight pressure to make the mixed liquid pass through the copper mesh.

[0059] Step 4, calculate the separation efficiency: η = (M1 / M2) * 100%, where M1 is the mass of the oil collected after separation, and M2 is the mass of the initial oil in the mixed liquid.

[0060] The above steps yield the following results (refer to Figure 15-18 ): With high efficiency, the separation efficiency of all samples (especially the area ratio of 1:4) for various oils is >99.5%. With bidirectional and reversible properties, the separation efficiency is as high as 99.5% or more with no significant difference when the front or back of the same copper mesh is facing up. Figure 18 ). It has cyclic stability and the separation efficiency is still >90% after 20 cycles of separation experiments on samples with an area ratio of 1:4 (reference Figure 17 The sample with an area ratio of 1:1 failed after only 5 cycles. The water was effectively intercepted above the copper mesh, and the oil quickly passed through the copper mesh into the collection container below, achieving a clear separation effect (reference Figure 15 ).

[0061] By optimizing electrochemical deposition parameters, specifically controlling the anode-cathode area ratio to 1:4, this method successfully fabricated a DLC super-hydrophobic-super-oleophilic film with a micro-nano roughened structure uniformly on both sides of a copper mesh. This method is simple, environmentally friendly, and low-cost. The resulting copper mesh exhibits excellent double-sided super-hydrophobicity (resistant to extreme pH and saltwater corrosion) and super-oleophilicity, enabling efficient (>99.5%), bidirectional / reversible separation of various oil-water mixtures and demonstrating excellent cycling stability (>90% after 20 cycles).

[0062] Figure 1 Shown are Raman spectra of DLC films deposited at different area ratios.

[0063] Figure 2 Shown are transmission electron microscopy (TEM) images and electron diffraction patterns of DLC films, showing an amorphous matrix and diamond / graphite nanocrystal clusters.

[0064] Figure 3 Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:1. Figure 4Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:2. Figure 5 Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:3. Figure 6 Shown are scanning electron microscope (SEM) images of the front and back surfaces of the copper mesh deposited at an anode-cathode area ratio of 1:4. Figure 3-6 The surface morphology evolution and double-sided uniformity improvement are demonstrated.

[0065] Figure 7 Shown is a SEM comparison of a copper sheet and a copper mesh under the same deposition conditions (area ratio 1:4), which is used to illustrate the promoting effect of the copper mesh structure on double-sided deposition.

[0066] Figure 8 Shown is a schematic diagram of the principle of DLC deposition on copper sheets and copper mesh at different anode and cathode area ratios.

[0067] Figure 9 Shown are the contact angles and the difference in contact angles between the front and back surfaces of the copper mesh after deposition of different anode sizes, which are used to demonstrate the effect of area ratio on hydrophobicity and uniformity.

[0068] Figure 10 Shown are the contact angle diagrams of aqueous solutions with different pH values ​​on the copper mesh, which are used to demonstrate acid and alkali resistance.

[0069] Figure 11 Shown are contact angle graphs of copper mesh immersed in salt water for different times to demonstrate long-term salt resistance.

[0070] Figure 12 Shown are photos of oil droplets (penetration) and water droplets (spheres) on the surface of the copper mesh, which are used to visually demonstrate the superhydrophobicity / superoleophilicity.

[0071] Figure 13 Shown is a sequence diagram of the oil absorption capacity test of the super-hydrophobic copper mesh.

[0072] Figure 14 Shown is a test diagram of the hydrophobic performance of a super-hydrophobic copper mesh under oil (water droplets rolling in oil).

[0073] Figure 15 Shown is a photo of the oil-water separation effect. It can be seen from the picture that the water is intercepted and the oil is separated.

[0074] Figure 16 Shown is a graph showing the separation efficiency of copper mesh for different types of oil.

[0075] Figure 17 Shown are the results of the repetitive separation experiment (cyclic stability) of copper mesh deposited with different anode areas.

[0076] Figure 18The figure shows the comparison of the results of repeated separation experiments on the front and back sides of the copper mesh, which is used to prove that the bidirectional separation performance is consistent.

Claims

1. A method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh, characterized in that: The following steps are involved: S1, ultrasonically clean the copper mesh substrate with dilute hydrochloric acid, acetone, ethanol, and deionized water in sequence to remove surface contaminants; S2, electrochemical deposition, using a pretreated copper mesh as the cathode and a graphite sheet as the anode in a carbon-containing electrolyte, electrochemical deposition is performed at a constant low voltage. During the deposition process, the area ratio of the cathode to the anode is controlled at 1:1 to 1:4; S3, after the deposition is completed, the copper mesh is taken out, cleaned and dried to obtain a super-hydrophobic-super-oleophilic copper mesh with diamond-like carbon (DLC) film uniformly covered on both sides.

2. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 1, wherein: The carbonaceous electrolyte in S2 is an ionic liquid with a molar ratio of choline chloride to ethylene glycol of 1:

2.

3. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 1, wherein: The constant low voltage in S2 is 2.0V-3.5V.

4. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 3, wherein: The constant low voltage is 2.75V.

5. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 1, wherein: The deposition time in S2 is 10-30 minutes.

6. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 5, wherein: The deposition time was 15 minutes.

7. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 1, wherein: The area ratio of cathode to anode in S2 is 1:3 to 1:

4.

8. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 1, wherein: In S2, the cathode is a copper mesh with a pore size of 75 μm and a copper wire diameter of 45 μm, and the anode is a high-purity graphite sheet.

9. The method for preparing a double-sided super-hydrophobic-super-oleophilic copper mesh according to claim 1, wherein: The DLC films on both sides of the copper mesh have a micro-nano composite rough structure, and the water contact angles on both sides are greater than 150°. After immersion in a pH 1-13 aqueous solution and 3.5% salinity salt water for 30 days, the water contact angle is still greater than 150°.

10. An application of a double-sided super-hydrophobic-super-oleophilic copper mesh, characterized by: The preparation method of the double-sided super-hydrophobic-super-oleophilic copper mesh according to any one of claims 1 to 9 is applied to material characterization, wetting performance testing, and oil-water separation performance testing.

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