A method for preparing superhydrophilic and oleophobic stainless steel mesh

Abstract

This invention belongs to the field of metal surface treatment technology, specifically relating to a method for preparing a superhydrophilic and oleophobic stainless steel mesh. To develop a simple, mild, and environmentally friendly method for preparing superhydrophilic and oleophobic stainless steel mesh, this invention first performs electrochemical etching on the stainless steel mesh to obtain a rough surface. Then, the etched stainless steel mesh is immersed in a chitosan-sodium perfluorooctanoate solution to graft hydrophilic and hydrophobic groups onto the surface of the stainless steel mesh, resulting in a superhydrophilic and oleophobic stainless steel mesh. The preparation process of this invention is simple, the reagents used are environmentally friendly, and the prepared stainless steel mesh exhibits excellent superhydrophilic and oleophobic properties, making it suitable for oil-water separation applications and large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of metal surface treatment technology, and specifically relates to a method for preparing a superhydrophilic and oleophobic stainless steel mesh. Background Technology

[0002] Stainless steel mesh has a wide range of uses in daily life, but since the main component of stainless steel mesh is iron, it is easily corroded in the air, which affects the service life of stainless steel mesh and may cause certain safety hazards.

[0003] In the process of global industrialization, with the gradual increase in oil consumption, the amount of oily wastewater generated daily has also increased rapidly, causing enormous damage to the environment and seriously affecting the survival of plants, animals, and even humans worldwide. Although methods such as centrifugal sedimentation and settling tanks can be used to separate oil and water, these methods require significant manpower, material resources, and time, making them difficult to use on a large scale. Therefore, to achieve better oil-water separation results, superwetting materials have received widespread attention and application.

[0004] Currently, the main superwetting materials capable of oil-water separation are superhydrophobic and superhydrophilic materials. However, these materials all have some shortcomings. For example, when using superhydrophobic materials for oil-water separation, the water in the oil-water mixture is generally at the bottom while the oil is at the top, making efficient oil-water separation difficult. On the other hand, superhydrophilic materials are easily contaminated by oil during oil-water separation, losing their superhydrophilic properties. Stainless steel mesh, as a substrate, has advantages such as good stability and long service life compared to other hydrophilic and oleophobic materials. Therefore, the preparation and application of superhydrophilic and oleophobic stainless steel mesh have received attention. However, current methods for preparing superhydrophilic and oleophobic stainless steel mesh all have some drawbacks, such as complex manufacturing processes, the need for high-temperature conditions, and the use of toxic reagents that harm the environment. Therefore, developing a simple, mild, and environmentally friendly method for preparing superhydrophilic and oleophobic stainless steel mesh has significant application value. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a superhydrophilic and oleophobic stainless steel mesh. The preparation process of this invention is simple, the reagents used are environmentally friendly, and the prepared stainless steel mesh has good superhydrophilic and oleophobic properties, which can be used for the efficient separation of oil-water mixtures.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] This invention provides a method for preparing a superhydrophilic and oleophobic stainless steel mesh, the method comprising the following steps:

[0008] S1. Using NaCl solution as the electrolyte solution, stainless steel mesh as the anode, and copper as the cathode, the stainless steel mesh is subjected to electrochemical etching treatment to form a rough structure on the surface of the stainless steel mesh.

[0009] S2. The etched stainless steel mesh is immersed in a chitosan-sodium perfluorooctanoate solution to graft hydrophilic and hydrophobic groups onto the surface of the stainless steel mesh. Finally, after washing and drying, a superhydrophilic and oleophobic stainless steel mesh is obtained.

[0010] This invention prepares superhydrophilic and oleophobic materials using a combination of electrochemical etching and surface modification. Chitosan provides the hydrophilic amino and hydroxyl groups, while sodium perfluorooctanoate provides the oleophobic fluorocarbon chains. The stainless steel mesh prepared by this invention exhibits excellent superhydrophilic and oleophobic properties, with a water contact angle of approximately 0° and an oil contact angle exceeding 120°.

[0011] The reagents used in this invention are all environmentally friendly, such as NaCl and sodium perfluorooctanoate, and will not cause harm to the environment or human health. Furthermore, the experimental conditions of this invention are mild, and are generally conducted at room temperature, ensuring experimental safety. The experimental apparatus and conditions required for this invention are simple and easy to implement, facilitating large-scale industrial production and demonstrating promising industrial development prospects.

[0012] Preferably, the electrochemical etching process is carried out at a temperature of 20–30°C and a current density of 0.5–2 A / cm². 2 The etching time is 15 to 25 minutes.

[0013] Preferably, the concentration of the NaCl solution is 0.1–1 mol / L.

[0014] Preferably, the chitosan-sodium perfluorooctanoate solution is prepared by: using acetic acid as a solvent, first dissolving chitosan in acetic acid, then adding sodium perfluorooctanoate to the solution, and stirring until well mixed.

[0015] Further, the preparation method of the chitosan-sodium perfluorooctanoate solution is as follows: dissolve 0.1-0.5g of chitosan in 1% acetic acid, then add 10-30mL of 0.1mol / L sodium perfluorooctanoate aqueous solution dropwise to the solution, and stir to mix well to obtain the solution.

[0016] Preferably, the soaking time is 3-5 hours.

[0017] Preferably, the stainless steel mesh comprises 304 stainless steel mesh.

[0018] Preferably, the stainless steel mesh is pretreated by sanding and polishing and ultrasonic cleaning before etching to remove surface oxides and oil contaminants, resulting in a smooth and clean stainless steel mesh with a smooth surface.

[0019] Furthermore, the stainless steel mesh was polished sequentially using two different grades of sandpaper: 500 grit and 1000 grit.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] This invention discloses a method for preparing a superhydrophilic and oleophobic stainless steel mesh. First, the stainless steel mesh is subjected to electrochemical etching to obtain a rough-surfaced mesh. Then, the etched stainless steel mesh is immersed in a chitosan-sodium perfluorooctanoate solution to graft hydrophilic and hydrophobic groups onto the surface of the stainless steel mesh, resulting in a superhydrophilic and oleophobic stainless steel mesh. The preparation process of this invention is simple, the reagents used are environmentally friendly, and the prepared stainless steel mesh exhibits excellent superhydrophilic and oleophobic properties, making it suitable for oil-water separation applications and large-scale industrial production. Attached Figure Description

[0022] Figure 1 The images show the measured water contact angle and oil contact angle of the superhydrophilic and oleophobic stainless steel mesh surface in Example 1 (left image shows water contact angle, right image shows oil contact angle).

[0023] Figure 2 The graphs show the measured water contact angle and oil contact angle of an untreated stainless steel mesh surface (left graph shows the water contact angle, right graph shows the oil contact angle).

[0024] Figure 3 The images show the measured water contact angle and oil contact angle of the superhydrophilic and oleophobic stainless steel mesh surface in Example 2 (left image shows water contact angle, right image shows oil contact angle).

[0025] Figure 4 The images show the measured water contact angle and oil contact angle of the superhydrophilic and oleophobic stainless steel mesh surface in Example 3 (left image shows water contact angle, right image shows oil contact angle). Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0028] Example 1: A method for preparing a superhydrophilic and oleophobic stainless steel mesh

[0029] The method includes the following steps:

[0030] (1) Surface pretreatment: First, polish the 304 stainless steel mesh with 500-grit and 1000-grit sandpaper, and then place it in an ultrasonic cleaner for 20 minutes to remove the oxide film and oily contaminants on the surface of the stainless steel mesh.

[0031] (2) Etching: Dissolve 3g of sodium chloride in 500mL of deionized water to obtain a 0.1mol / L sodium chloride solution. Place the stainless steel mesh treated in step (1) into the electrochemical etching system, using the stainless steel mesh as the anode and copper as the cathode for electrochemical etching. The etching current density is maintained at 0.5A / cm. 2 Etch at room temperature for 15 minutes. After etching, rinse the stainless steel mesh with deionized water and anhydrous ethanol in sequence, and then dry it at 80°C for 20 minutes.

[0032] (3) Modification: The dried stainless steel mesh from step (2) is placed in a chitosan-sodium perfluorooctanoate solution (0.3g of chitosan is dissolved in a certain amount of 1% acetic acid to prepare a 2mg / mL chitosan solution, and then 20mL of 0.1mol / L sodium perfluorooctanoate aqueous solution is added dropwise to the solution and stirred for 1h to obtain a uniform solution) and soaked for 5h. Then the stainless steel mesh is taken out and rinsed with anhydrous ethanol. After rinsing, it is dried at room temperature for 4h to obtain a superhydrophilic and oleophobic stainless steel mesh.

[0033] (4) Measurement: The water contact angle and oil (kerosene) contact angle of the prepared superhydrophilic oleophobic stainless steel mesh were measured. Figure 1 It can be seen that the superhydrophilic and oleophobic stainless steel mesh of this embodiment has a water contact angle of approximately 0°, exhibiting superhydrophilicity, and an oil contact angle of 120°, exhibiting superoleophobicity. In contrast, the untreated stainless steel mesh has a water contact angle of 50° and an oil contact angle of 90°. Figure 2 ).

[0034] Example 2: A method for preparing a superhydrophilic and oleophobic stainless steel mesh

[0035] The method includes the following steps:

[0036] (1) Surface pretreatment: First, polish the 304 stainless steel mesh with 500-grit and 1000-grit sandpaper, and then place it in an ultrasonic cleaner for 20 minutes to remove the oxide film and oily contaminants on the surface of the stainless steel mesh.

[0037] (2) Etching: Dissolve 6g of sodium chloride in 500mL of deionized water to obtain a 0.2mol / L sodium chloride solution. Place the stainless steel mesh treated in step (1) into the electrochemical etching system, and perform electrochemical etching with the stainless steel mesh as the anode and copper as the cathode. The etching current density is maintained at 0.8A / cm. 2 Etch at room temperature for 20 minutes. After etching, rinse the stainless steel with deionized water and anhydrous ethanol in sequence, and then dry it at 80°C for 20 minutes.

[0038] (3) Modification: The dried stainless steel mesh from step (2) is placed in a chitosan-sodium perfluorooctanoate solution (0.1g of chitosan is dissolved in a certain amount of 1% acetic acid, and then 10mL of 0.1mol / L sodium perfluorooctanoate aqueous solution is added dropwise to the solution and stirred for 1h to obtain a uniform solution) and soaked for 5h. Then the stainless steel mesh is taken out and rinsed with anhydrous ethanol. After rinsing, it is dried at room temperature for 4h to obtain a superhydrophilic and oleophobic stainless steel mesh.

[0039] (4) Measurement: The water contact angle and oil contact angle of the prepared superhydrophilic and oleophobic stainless steel mesh were measured. Figure 3 It can be seen that the water contact angle of this superhydrophilic and oleophobic stainless steel mesh is still 0°, while the oil contact angle reaches 124°, exhibiting superhydrophilic and oleophobic properties.

[0040] Example 3: A method for preparing a superhydrophilic and oleophobic stainless steel mesh

[0041] The method includes the following steps:

[0042] (1) Surface pretreatment: First, polish the 304 stainless steel mesh with 500-grit and 1000-grit sandpaper, and then place it in an ultrasonic cleaner for 20 minutes to remove the oxide film and oily contaminants on the surface of the stainless steel mesh.

[0043] (2) Etching: Dissolve 9g of sodium chloride in 500mL of deionized water to obtain a 0.3mol / L sodium chloride solution. Place the stainless steel mesh treated in step (1) into the electrochemical etching system, and perform electrochemical etching with the stainless steel mesh as the anode and copper as the cathode. The etching current density is maintained at 1A / cm. 2 Etching was performed at room temperature for 23 minutes. After etching, the stainless steel was rinsed with deionized water and anhydrous ethanol, and then dried at 80°C for 20 minutes.

[0044] (3) Modification: The dried stainless steel mesh from step (2) is placed in a chitosan perfluorooctanoic acid sodium solution (0.5g of chitosan is dissolved in a certain amount of 1% acetic acid, and then 30mL of 0.1mol / L perfluorooctanoic acid sodium aqueous solution is added dropwise to the solution and stirred for 1h to obtain a uniform solution) and soaked for 5h. Then the stainless steel mesh is taken out and rinsed with anhydrous ethanol. After rinsing, it is dried at room temperature for 4h to obtain a superhydrophilic and oleophobic stainless steel mesh.

[0045] (4) Measurement: The water contact angle and oil contact angle of the prepared superhydrophilic and oleophobic stainless steel mesh were measured. Figure 4 It can be seen that the water contact angle of this superhydrophilic and oleophobic stainless steel mesh is still 0°, while the oil contact angle reaches 128°, thus exhibiting superhydrophilic and oleophobic properties.

[0046] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a superhydrophilic and oleophobic stainless steel mesh, characterized in that, Includes the following steps: S1. Using NaCl solution as the electrolyte, a stainless steel mesh as the anode, and copper as the cathode, an electrochemical etching process is performed on the stainless steel mesh to create a rough surface structure. The electrochemical etching process is carried out at a temperature of 20~30℃ and a current density of 0.5~2A / cm². 2 The etching time is 15~25 minutes; S2. The etched stainless steel mesh is immersed in a chitosan-sodium perfluorooctanoate solution to graft both hydrophilic and hydrophobic groups onto the surface of the stainless steel mesh. Finally, after washing and drying, a superhydrophilic and oleophobic stainless steel mesh is obtained. The chitosan-sodium perfluorooctanoate solution is prepared by dissolving 0.1~0.5g of chitosan in 1% acetic acid, and then adding 10~30mL of 0.1mol / L sodium perfluorooctanoate aqueous solution dropwise to the solution and stirring until well mixed.

2. The method for preparing a superhydrophilic and oleophobic stainless steel mesh according to claim 1, characterized in that, The concentration of the NaCl solution is 0.1~1 mol / L.

3. The method for preparing a superhydrophilic and oleophobic stainless steel mesh according to claim 1, characterized in that, The soaking treatment time is 3-5 hours.

4. The method for preparing a superhydrophilic and oleophobic stainless steel mesh according to claim 1, characterized in that, The stainless steel mesh includes 304 stainless steel mesh.

5. The method for preparing a superhydrophilic and oleophobic stainless steel mesh according to claim 1, characterized in that, Before etching, the stainless steel mesh is pretreated by sanding and polishing and ultrasonic cleaning to remove surface oxides and oil contaminants, resulting in a smooth and clean stainless steel mesh.

6. The method for preparing a superhydrophilic and oleophobic stainless steel mesh according to claim 5, characterized in that, The stainless steel mesh was polished using two different grades of sandpaper, 500 grit and 1000 grit.

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