A method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh

Abstract

This invention discloses a method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh. The method includes the following steps: Step 1, using stainless steel mesh as a substrate, ultrasonically cleaning it sequentially in acetone, anhydrous ethanol, and deionized water, and then drying it; Step 2, immersing the cleaned and dried stainless steel mesh in a mixed solution of solution A and solution B for coating; Step 3, adding an oxidant to the mixed solution and carrying out an in-situ oxidation reaction under acidic conditions; Step 4, cleaning and drying the modified stainless steel mesh to obtain a hydrophilic / underwater superoleophobic stainless steel mesh. The stainless steel mesh prepared by this method exhibits a hydrophilic / underwater superoleophobic wetting morphology, good stability and durability in harsh environments, and can separate oil-water mixtures and high-concentration water-in-oil emulsions with ultra-high permeability and good oil removal rate. The preparation method of this invention is simple, low-cost, and can be used in large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of oily wastewater treatment technology, and relates to a method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh, specifically a method for preparing a hydrophilic / underwater superoleophobic coating. Background Technology

[0002] With the rapid development of various industries, the discharge of oily wastewater is increasing year by year. The generation and discharge of large amounts of oily wastewater pose a significant threat to the ecological environment and, through bioaccumulation in the food chain, also threaten human life. Therefore, it is urgent to rationally treat and dispose of oily wastewater. Filtration separation technology is widely recognized as an effective technology for separating liquids on demand based on droplet size, not only because it is simple to operate, low-cost, and produces no secondary pollution, but also because of the high-efficiency filtration achieved through its screening mechanism during the separation process. However, in the long-term oil-water separation process, oil pollution is inevitable, leading to blockage of the filter media's water passages, resulting in reduced throughput and shortened service life.

[0003] Hydrophilic-underwater superoleophobic wetting materials allow the aqueous phase to pass through at appropriate pore sizes while repelling the oil phase, effectively controlling dirt adhesion and offering significant advantages in oil-water separation. Compared to other polymer membranes and fabrics, metal mesh possesses excellent mechanical strength and a larger pore size, resulting in wear resistance and ultra-high permeation flux. Furthermore, metal mesh is inexpensive, easy to process, and can be mass-produced for practical industrial applications.

[0004] CN118949713 A discloses a method for preparing a stainless steel mesh capable of separating oil-water mixtures and oil-in-water emulsions. This method involves two complex hydrophilic modification steps, with the hydrothermal reaction increasing the difficulty and cost of industrial application. CN 113082853 B discloses a three-dimensional Janus stainless steel mesh capable of separating emulsified oil and water and its preparation method. However, the dopamine and polyethyleneimine used in this method are expensive and cannot be mass-produced in practical applications, further increasing the difficulty and cost of industrial application. Summary of the Invention

[0005] To address the aforementioned shortcomings and deficiencies of existing technologies, this invention provides a method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh. The stainless steel mesh prepared by this method exhibits a hydrophilic / underwater superoleophobic wetting morphology, demonstrates excellent stability and durability in harsh environments, and, in oil-water separation applications, can separate oil-water mixtures and high-concentration oil-in-water emulsions with extremely high permeability and excellent oil removal rates. The preparation method of this invention is simple, low-cost, and can be used in large-scale industrial production.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh includes the following steps:

[0008] Step 1: Using stainless steel mesh as the substrate, ultrasonically clean it in acetone, anhydrous ethanol, and deionized water in sequence, and then dry it.

[0009] The cleaning time is 20–60 minutes;

[0010] The copper mesh has a size of 2-5cm × 2-5cm and a mesh size of 200-500.

[0011] Step 2: Immerse the cleaned and dried stainless steel mesh from Step 1 into a mixed solution of Solution A and Solution B for coating, wherein:

[0012] Solution A is a mixed solution of tannic acid (TA) and Tris-HCl, with concentrations of TA and Tris-HCl of 1.5–2.5 wt% and 1.15–1.25 wt%, respectively.

[0013] Solution B is a homogeneous solution of tetraethyl orthosilicate (TEOS) and ethanol, with the concentration of tetraethyl orthosilicate being 3.5–4.0 wt%.

[0014] The volume ratio of solution A to solution B is 10:2 to 10:5;

[0015] The pH of the mixed solution is 8-9;

[0016] The coating time is 20–60 minutes;

[0017] Step 3: Add an oxidizing agent to the mixed solution from Step 2, and carry out an in-situ oxidation reaction under acidic conditions, wherein:

[0018] Under the aforementioned acidic conditions, the pH value is 4–6;

[0019] The in-situ oxidation reaction was carried out at room temperature on an air shaker for 5 to 8 hours at a speed of 120 to 150 rpm.

[0020] The oxidant is one of NaClO solution, NaClO3 and NaIO4, and the amount added is 3 to 5 wt% of solution A;

[0021] Step 4: Clean and dry the modified stainless steel mesh from Step 3 to obtain a hydrophilic / underwater superoleophobic stainless steel mesh, wherein:

[0022] The cleaning method is as follows: use ethanol and deionized water to wash away the unreacted solution on the surface of the modified stainless steel mesh;

[0023] The drying temperature is 60–80°C, and the time is 1–3 hours;

[0024] The hydrophilic / underwater superoleophobic stainless steel mesh exhibits underwater superoleophobic effects on dodecane, gasoline, diesel, etc.

[0025] This invention employs a one-step coating method to deposit TA and SiO2 particles onto the surface of a stainless steel mesh, constructing a hydrophilic surface. The in-situ oxidation of TA is combined with the hydrolytic condensation of TEOS to enhance the adhesion and hydrophilicity of the TA-SiO2 coating. TA, used in this invention, is a naturally occurring plant polyphenol, abundant, inexpensive, and biodegradable; it contains abundant catechol or gallic acid groups, enabling the formation of smooth, light-colored coatings on various substrates. The introduction of an oxidant enhances the stability of the TA coating. Compared to the more commonly used NaIO4, NaClO3, ultimately chosen in this invention, is inexpensive and possesses good oxidizing ability for the TA coating. Tetraethyl orthosilicate is inexpensive and readily available; under alkaline conditions, its hydrolytic condensation forms nano-silica rich in hydroxyl groups, while also exhibiting good hydrophilicity, combining with TA through hydrogen bonding to form a hydrophilic hybrid layer. Stainless steel mesh has good mechanical properties, is inexpensive, and easy to process. Its micron-sized pores have extremely high permeability. Special wetting materials prepared with stainless steel mesh as a base have good corrosion resistance and good impact resistance in continuous oil-water separation processes, making it suitable for large-scale industrial applications.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) This invention uses a one-step coating method to deposit TA and SiO2 particles onto the surface of a stainless steel mesh to construct a hydrophilic surface. The in-situ oxidation of TA is combined with the hydrolytic condensation of TEOS to enhance the adhesion and hydrophilicity of the TA-SiO2 coating.

[0028] (2) The hydrophilic / underwater superoleophobic stainless steel mesh prepared by this invention has an ultra-high permeability and exhibits excellent separation performance for oil-water mixtures and high-concentration oil-in-water emulsions through multilayer stacking. It has good stability and durability in harsh environments and demonstrates good shock resistance and recyclability in continuous oil-water separation processes.

[0029] (3) The preparation process of the hydrophilic stainless steel mesh obtained by the present invention is simple, the reaction conditions are mild, the materials used are inexpensive, and it is ready for industrial application. Attached Figure Description

[0030] Figure 1 The diagram shows the water contact angle of the modified stainless steel mesh in air over time.

[0031] Figure 2 The contact angle diagrams of the modified stainless steel mesh under different oils underwater are shown.

[0032] Figure 3 Figures showing the water contact angle and underwater diesel contact angle of T2T stainless steel mesh in solutions with different pH values;

[0033] Figure 4 Figures showing the water contact angle and underwater diesel contact angle of T2T stainless steel mesh after immersion in salt solution for 7 days.

[0034] Figure 5 Figures showing the water contact angle and underwater diesel contact angle of T2T stainless steel mesh after 7 consecutive days of hydraulic scouring.

[0035] Figure 6 This is a diagram of an oil-water separation device;

[0036] Figure 7 Flux diagrams for separating pure water, oil-water mixtures, and high-concentration oil-in-water solutions using T2T stainless steel mesh with different stacking layers;

[0037] Figure 8 Oil removal rate diagrams for oil-water mixtures and high-concentration oil-in-water emulsions separated by T2T-stainless steel mesh with different stacking layers;

[0038] Figure 9 The parameters (pure water flux, oil-water mixture flux, and oil removal rate) for the separation of oil-water mixtures in a cyclic test using 3-layer T2T stainless steel mesh are shown in the figure.

[0039] Figure 10 Separation parameters (pure color flux, oil-in-water emulsion flux, and oil removal) for high-concentration oil-in-water emulsion separation in a cyclic test using 3-layer T2T stainless steel mesh. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0041] Example 1

[0042] (1) Cut the 300-mesh stainless steel mesh into 4cm×4cm pieces, and clean it by ultrasonic cleaning in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence to remove dust, oil and other impurities from the surface of the metal mesh. Then place it in a 60℃ constant temperature drying oven to dry for 2 hours to obtain a clean stainless steel mesh after pretreatment.

[0043] (2) Prepare solution A with a concentration of 2 wt% tannic acid (TA) and 1.21 wt% Tris-HCl, with a pH of 8.5. Prepare homogenized solution B with a concentration of 3.8 wt% tetraethyl orthosilicate (TEOS) and ethanol. Mix solutions A and B at a volume ratio of 10:3, then quickly immerse a clean stainless steel mesh in the mixture and perform a hydrophilic coating in an ultrasonic field for 30 minutes.

[0044] (3) Adjust the pH of the mixed solution to 5 and react it at room temperature on an air shaker for 6 hours, maintaining the shaker speed between 120 and 150 rpm. Wash the modified stainless steel mesh with ethanol and deionized water to remove any unreacted solution from the surface. Then dry it in a constant temperature drying oven at 60°C for 2 hours to obtain the modified TT-stainless steel mesh.

[0045] Example 2

[0046] (1) Cut the 300-mesh stainless steel mesh into 4cm×4cm pieces, and clean it by ultrasonic cleaning in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence to remove dust, oil and other impurities from the surface of the metal mesh. Then place it in a 60℃ constant temperature drying oven to dry for 2 hours to obtain a clean stainless steel mesh after pretreatment.

[0047] (2) Prepare solution A with a concentration of 2 wt% tannic acid (TA) and 1.21 wt% Tris-HCl, with a pH of 8.5. Prepare homogenized solution B with a concentration of 3.8 wt% tetraethyl orthosilicate (TEOS) and ethanol. Mix solutions A and B at a volume ratio of 10:3, then quickly immerse a clean stainless steel mesh in the mixture and perform a hydrophilic coating in an ultrasonic field for 30 minutes.

[0048] (3) Add 4 wt% NaClO solution (of solution A) to the mixed solution and adjust the pH of the mixed solution to 5. Perform an in-situ oxidation reaction at room temperature on an air shaker for 6 hours, maintaining the shaker speed between 120 and 150 rpm. Wash the modified stainless steel mesh with ethanol and deionized water to remove any unreacted solution from the surface. Then dry it in a constant temperature drying oven at 60℃ for 2 hours to obtain the modified T1T-stainless steel mesh.

[0049] Example 3

[0050] (1) Cut the 300-mesh stainless steel mesh into 4cm×4cm pieces, and clean it by ultrasonic cleaning in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence to remove dust, oil and other impurities from the surface of the metal mesh. Then place it in a 60℃ constant temperature drying oven to dry for 2 hours to obtain a clean stainless steel mesh after pretreatment.

[0051] (2) Prepare solution A with a concentration of 2 wt% tannic acid (TA) and 1.21 wt% Tris-HCl, with a pH of 8.5. Prepare homogenized solution B with a concentration of 3.8 wt% tetraethyl orthosilicate (TEOS) and ethanol. Mix solutions A and B at a volume ratio of 10:3, then quickly immerse a clean stainless steel mesh in the mixture and perform a hydrophilic coating in an ultrasonic field for 30 minutes.

[0052] (3) Add 4 wt% NaClO3 to the mixed solution, adjust the pH of the mixed solution to 5, and carry out an in-situ oxidation reaction for 6 hours at room temperature on an air shaker, maintaining the shaker speed between 120 and 150 rpm. Wash the modified stainless steel mesh with ethanol and deionized water to remove any unreacted solution from the surface. Then dry it in a constant temperature drying oven at 60℃ for 2 hours to obtain the modified T2T-stainless steel mesh.

[0053] Example 4

[0054] (1) Cut the 300-mesh stainless steel mesh into 4cm×4cm pieces, and clean it by ultrasonic cleaning in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence to remove dust, oil and other impurities from the surface of the metal mesh. Then place it in a 60℃ constant temperature drying oven to dry for 2 hours to obtain a clean stainless steel mesh after pretreatment.

[0055] (2) Prepare solution A with a concentration of 2 wt% tannic acid (TA) and 1.21 wt% Tris-HCl, with a pH of 8.5. Prepare homogenized solution B with a concentration of 3.8 wt% tetraethyl orthosilicate (TEOS) and ethanol. Mix solutions A and B at a volume ratio of 10:3, then quickly immerse a clean stainless steel mesh in the mixture and perform a hydrophilic coating in an ultrasonic field for 30 minutes.

[0056] (3) Add 4 wt% NaIO4 to the mixed solution, adjust the pH of the mixed solution to 5, and carry out an in-situ oxidation reaction for 6 hours at room temperature on an air shaker, maintaining the shaker speed between 120 and 150 rpm. Wash the modified stainless steel mesh with ethanol and deionized water to remove any unreacted solution from the surface. Then dry it in a constant temperature drying oven at 60°C for 2 hours to obtain the modified T3T-stainless steel mesh.

[0057] Performance testing:

[0058] (1) Hydrophilic and oleophobic properties test

[0059] The water contact angle (WCA) in air of the stainless steel meshes prepared in Examples 1-4 and the original stainless steel meshes changes over time as follows: Figure 1As shown, the original stainless steel mesh had a water contact angle of 128.73°. After modification, the water contact angle decreased, with the initial water contact angles of TT-stainless steel mesh, T1T-stainless steel mesh, T2T-stainless steel mesh, and T3T-stainless steel mesh being 104.2°, 92.62°, 66.56°, and 88°, respectively. The original stainless steel mesh maintained a water contact angle above 118° after 45 minutes, while water droplets on the surfaces of TT-stainless steel mesh, T1T-stainless steel mesh, T2T-stainless steel mesh, and T3T-stainless steel mesh were completely spread on the material surface at 43.3 minutes, 27.3 minutes, 19.25 minutes, and 37.8 minutes, respectively. The above analysis shows that after modification with the TA-SiO2 hydrophilic coating, the surface of the stainless steel mesh changed from hydrophobic to hydrophilic. Furthermore, a comparison of the hydrophilicity of the TA-SiO2 coating with three different oxidants and air oxidation showed that the coating after in-situ oxidation with NaClO3 exhibited better hydrophilicity. Therefore, in subsequent implementation schemes, the T2T-stainless steel mesh obtained by the NaClO3 oxide coating in Example 3 is selected.

[0060] The underwater oil contact angle (UWOCA) of the T2T-stainless steel mesh prepared in Example 3 and the original stainless steel mesh is as follows: Figure 2 As shown, the original stainless steel mesh exhibits underwater oil-water contact angles of 26.37°, 34.55°, and 89.48° for dodecane, gasoline, and diesel, respectively, demonstrating underwater oleophilicity. However, after modification, the surface of the T2T-stainless steel mesh shows underwater contact angles of 153.54°, 153.1°, and 154.9° for these oils, exhibiting underwater superoleophobicity.

[0061] (2) Testing of chemical stability

[0062] The chemical stability of the material was evaluated by simulating harsh environmental treatment. The T2T-stainless steel mesh prepared in Example 3 was immersed in solutions with pH values ​​of 1, 3, 5, 7, 9, 11, and 13 for 24 hours, and then its water contact angle in air and its contact angle with underwater diesel fuel were measured. Simultaneously, the T2T-stainless steel mesh prepared in Example 3 was immersed in a 1 mol / L NaCl solution for 1–7 days to measure its hydrophilicity and underwater oleophobicity. The water contact angle and underwater oil contact angle of the T2T-stainless steel mesh after immersion in solutions with different pH values ​​and salt solutions are shown below. Figure 3 and Figure 4 As shown. (Through) Figure 3 and Figure 4 It can be seen that T2T stainless steel mesh can still maintain hydrophilicity and underwater oleophobicity after treatment with acidic, alkaline and salt solutions, indicating that T2T stainless steel mesh has good chemical stability.

[0063] (3) Mechanical stability test

[0064] The mechanical stability of the metal mesh was tested using a hydraulic scouring test. The T2T-stainless steel mesh prepared in Example 3 was placed in an aqueous solution on an air shaker at room temperature. The shaker speed was set to 200 rpm. The hydrophilicity and underwater oleophobicity of the T2T-stainless steel mesh after hydraulic scouring for 1–7 days were measured. Figure 5 As shown, after 7 days of strong water scouring, the water contact angle of the T2T-stainless steel mesh fluctuated around 60°, while the oil contact angle remained above 150°, maintaining good hydrophilicity and underwater superoleophobicity, indicating that the modified metal mesh has excellent mechanical stability.

[0065] (4) Oil-water separation efficiency test

[0066] The oil-water separation efficiency and throughput of the metal mesh were tested using a dead-end filter. The T2T-stainless steel mesh prepared in Example 3 was fixed onto the dead-end filter device. Figure 6 Before separation, the metal mesh was wetted with deionized water. Diesel and water were mixed at a volume ratio of 1:9 to form a mixture, which was stirred for 30 minutes with an electric stirrer at 1500 rpm to form an oil-water mixture. The oil-water mixture was stabilized for 1 hour before being used for separation. A high-concentration oil-in-water emulsion was formed by stirring 10 g / L diesel and 200 mg / L sodium dodecyl sulfonate with an electric stirrer at 1500 rpm for 1 hour. The emulsion was stabilized for 12 hours before being used for separation. 200 mL of oil-water solution and oil-in-water emulsion were separated under gravity. The oil concentration in the filtrate was determined by ultraviolet spectrophotometry, and the specific experimental method was based on the Chinese national standard "Determination of Petroleum by Ultraviolet Spectrophotometry in Water" (HJ 970-2018). The oil removal rate (R) was calculated according to formula (1). The flux (J) was calculated by taking 100 mL of filtrate during the solution separation process, as shown in formula (2).

[0067]

[0068] In the formula, R is the oil removal rate (%), c0 is the initial concentration of the emulsion (mg / L), and c1 is the concentration of the filtrate (mg / L).

[0069]

[0070] In the formula, J is the membrane flux (L·m -2 ·h -1 T is the sampling time (h), and A is the effective area of ​​the membrane (4.15 × 10⁻⁶). -4 m 2 ).

[0071] Example 3 shows the separation efficiency and throughput of stainless steel meshes with different numbers of stacked layers for oil-water mixtures and high-concentration oil-in-water emulsions as follows: Figure 7 Table 1 and Figure 8As shown in Table 2. From Figure 7-8 As shown in Table 1-2, with the increase in the number of metal mesh layers, the flux of pure water, oil-water mixture, and oil-in-water emulsion gradually decreases, while the oil removal rate gradually increases. This is because the randomly stacked metal mesh forms some irregular capillary channels with special wettability. When oil droplets enter these channels, they are subjected to capillary forces and adhesive forces generated by the capillary channels and wettability. Some oil droplets with a particle size smaller than the average pore size of the mesh are intercepted, causing demulsification. Eventually, they aggregate into large oil droplets that are intercepted by the metal mesh, successfully separating the high-concentration emulsion. Large-diameter oil droplets in the oil-water mixture are successfully screened by the mesh under the effect of size interception. However, the multi-layered mesh also reduces the original porosity of the metal mesh, narrowing the water passage and resulting in a decrease in flux. According to the separation parameters, when the metal mesh is stacked to two layers or more, the separation efficiency of the oil-water mixture reaches 99%, but the separation parameter of the emulsion is lower at 80.01% when there are two layers. When the number of metal mesh layers is 3, the oil removal rate of the emulsion rapidly increases to 95.63%, which is not much different from the oil removal rate when the number of layers is 4, and the flux parameters are also basically the same. Therefore, a 3-layer metal mesh is ultimately used to separate oil-water mixtures and high-concentration oil-in-water emulsions.

[0072] Table 1

[0073] 1st floor 2nd floor 3 floors 4 floors <![CDATA[Pure water flux (L·m -2 ·h -1 )]]> 480589.52 462510.92 453972.26 425190.156 <![CDATA[Oil-water mixture throughput (L·m -2 ·h -1 )]]> 173987.00 140515.22 117189.03 115086.576 <![CDATA[Oil-in-water emulsion through (L·m -2 ·h -1 )]]> 556758.43 491803.28 257938.78 208981.56

[0074] Table 2

[0075] 1st floor 2nd floor 3 floors 4 floors Oil removal rate (%) of oil-water mixture 2.38 99.57 99.98 99.98 Oil removal rate of oil-in-water emulsion (%) 68.7 80.01 95.63 97.32

[0076] (5) Cyclic performance test

[0077] use Figure 6 The separation device performs cyclic testing on a three-layer superimposed metal mesh. Figure 9 and Figure 10 These figures represent the pure water flux, oil-water flux, and oil removal rate of the T2T-stainless steel mesh prepared in Example 3 after 25 cycles of separation of a diesel / water mixture and a high-concentration water-in-diesel emulsion. During the cyclic separation, the pure water flux was consistently maintained at 6.5 × 10⁻⁶. 5 L·m -2 ·h -1 Above, the flux of oil-water mixtures and oil-in-water emulsions was maintained at 1.1 × 10⁻⁶. 5 L·m -2 ·h -1 The oil removal rate of the oil-water mixture remains above 99.4%, and the oil removal rate of the oil-in-water emulsion remains above 81%. The above analysis shows that the hydrophilic / underwater superoleophobic metal mesh of this invention has good recyclability and can be used for long-term separation of oil-water mixtures and high-concentration oil-in-water emulsions. In summary, the hydrophilic / underwater superoleophobic mesh of this invention exhibits excellent comprehensive performance.

Claims

1. A method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh, characterized in that... The method includes the following steps: Step 1: Using stainless steel mesh as the substrate, ultrasonically clean it in acetone, anhydrous ethanol, and deionized water in sequence, and then dry it. Step 2: Immerse the cleaned and dried stainless steel mesh from Step 1 into a mixed solution of Solution A and Solution B for coating. Solution A is a mixed solution of tannic acid and Tris-HCl with a pH of 8-9, and the concentrations of TA and Tris-HCl are 1.5-2.5 wt% and 1.15-1.25 wt%, respectively. Solution B is a homogeneous solution of tetraethyl orthosilicate and ethanol, with a tetraethyl orthosilicate concentration of 3.5-4.0 wt%. The volume ratio of Solution A to Solution B is 10:2 to 10:

5. Step 3: Add an oxidizing agent to the mixed solution from Step 2 and carry out an in-situ oxidation reaction under acidic conditions, wherein the oxidizing agent is NaClO3, and the amount added is 3-5 wt% of solution A; Step 4: Clean and dry the modified stainless steel mesh from Step 3 to obtain a hydrophilic / underwater superoleophobic stainless steel mesh.

2. The method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh according to claim 1, characterized in that... In step one, the cleaning time is 20-60 minutes.

3. The method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh according to claim 1, characterized in that... In step one, the copper mesh has a size of 2~5 cm × 2~5 cm and a mesh size of 200~500.

4. The method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh according to claim 1, characterized in that... In step two, the coating time is 20-60 minutes.

5. The method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh according to claim 1, characterized in that... In step three, the pH value is 4-6 under acidic conditions.

6. The method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh according to claim 1, characterized in that... In step three, the in-situ oxidation reaction is carried out at room temperature on an air shaker for 5-8 hours at a speed of 120-150 rpm.

7. The method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh according to claim 1, characterized in that... In step four, the cleaning method is as follows: use ethanol and deionized water to wash away the unreacted solution on the surface of the modified stainless steel mesh.

8. The method for preparing in-situ oxidized plant polyphenol-modified stainless steel mesh according to claim 1, characterized in that... In step four, the drying temperature is 60~80℃ and the time is 1~3 hours.

9. The application of a stainless steel mesh prepared by the method according to any one of claims 1-8 in oil-water separation.

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