Stainless steel mesh oil-water separation material, its preparation method and application

Abstract

This invention relates to composite materials, specifically to stainless steel mesh oil-water separation materials, their preparation methods, and applications. In this invention, etching the stainless steel mesh using a mixed solution containing sodium hydroxide and ammonium persulfate increases the mesh's roughness and surface area. Treating the etched stainless steel mesh in oxalic acid solution significantly improves its oleophobicity and hydrophilicity. The resulting stainless steel mesh oil-water separation material exhibits excellent oil-water separation performance, enabling rapid and efficient separation of oily wastewater.

Description

Technical Field

[0001] This invention relates to composite materials, specifically to stainless steel mesh oil-water separation materials, their preparation methods, and applications. Background Technology

[0002] Oil-water separation technology is of great significance in treating oily wastewater and leaked crude oil. The most common oil-water separation technology is membrane separation, which uses superhydrophobic materials to efficiently trap water or oil, achieving oil-water separation. However, the preparation process of superhydrophobic materials is currently complex and costly.

[0003] Existing technologies include solutions for oil-water separation using superhydrophobic copper mesh; however, the oil-water separation effect of superhydrophobic copper mesh needs further improvement. Summary of the Invention

[0004] To address the problem of poor oil-water separation performance in existing oil-water separation materials, this invention provides a stainless steel mesh oil-water separation material, its preparation method, and its application.

[0005] The first aspect of this invention provides a method for preparing a stainless steel mesh oil-water separation material, comprising the following steps:

[0006] The stainless steel mesh was immersed in a mixed solution containing sodium hydroxide and ammonium persulfate;

[0007] The stainless steel mesh was removed and immersed in an oxalic acid solution to obtain a stainless steel mesh oil-water separation material.

[0008] In the mixed solution containing sodium hydroxide and ammonium persulfate, the mass concentration of sodium hydroxide is 3% to 20%, the mass concentration of ammonium persulfate is 1% to 6%, and the mass concentration of oxalic acid solution is 0.2% to 5%.

[0009] A second aspect of the present invention provides a stainless steel mesh oil-water separation material, which is obtained by the preparation method of the stainless steel mesh oil-water separation material.

[0010] The third aspect of the present invention provides the application of the stainless steel mesh oil-water separation material in oil-water separation.

[0011] A fourth aspect of the present invention provides an oil-water separation method, comprising the following steps:

[0012] The oil-water mixture is placed on one side of the stainless steel mesh oil-water separator material;

[0013] The water in the oil-water mixture is driven through the stainless steel mesh oil-water separation material under the action of driving force.

[0014] The technical solutions of the embodiments of the present invention have the following beneficial effects:

[0015] (1) The stainless steel mesh was treated sequentially with a mixed solution containing sodium hydroxide and ammonium persulfate and an oxalic acid solution to form a precipitate of ferric oxalate pentahydrate on the surface of the stainless steel mesh, which increased the oleophobicity and hydrophilicity of the stainless steel mesh oil-water separation material.

[0016] (2) Stainless steel mesh oil-water separator material can quickly and efficiently separate wastewater containing refrigeration oil, toluene, petroleum ether, paraffin oil, diethyl ether, etc., with a separation efficiency of over 99.5% and a separation throughput of over 5.0 × 10⁻⁶. 4 Increase per square meter per hour;

[0017] (3) Stainless steel mesh oil-water separation material is inexpensive, has a simple preparation method, and is suitable for industrial production. Attached Figure Description

[0018] Figure 1 This is a scanning electron microscope (SEM) image of an untreated stainless steel mesh.

[0019] Figure 2 This is a scanning electron microscope (SEM) image of the stainless steel mesh oil-water separation material in Example 9 of the present invention.

[0020] Figure 3 The infrared spectrum of the stainless steel mesh oil-water separation material in Embodiment 9 of the present invention is shown.

[0021] Figure 4 This is a surface energy spectrum analysis diagram of the stainless steel mesh oil-water separation material in Example 9 of the present invention.

[0022] Figure 5 The diagram shows the contact angle analysis of the untreated stainless steel mesh and the oil-water separation material of the stainless steel mesh in Example 9 of this invention.

[0023] Figure 6 The contact angle analysis diagrams are shown for the stainless steel mesh oil-water separation materials in Examples 13, 15, 18, and 22 of this invention.

[0024] Figure 7 These are photographs of the oil-water separators used in Examples 23 to 27 of this invention.

[0025] Figure 8 The figures show the oil-water separation experimental results of the stainless steel mesh oil-water separation material in Examples 23 to 27 of this invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] The first aspect of this invention provides a method for preparing a stainless steel mesh oil-water separation material, comprising the following steps:

[0028] The stainless steel mesh was immersed in a mixed solution containing sodium hydroxide and ammonium persulfate;

[0029] The stainless steel mesh was removed and immersed in an oxalic acid solution to obtain a stainless steel mesh oil-water separation material.

[0030] In the mixed solution containing sodium hydroxide and ammonium persulfate, the mass concentration of sodium hydroxide is 3% to 20%, the mass concentration of ammonium persulfate is 1% to 6%, and the mass concentration of oxalic acid solution is 0.2% to 5%.

[0031] In practice, sodium hydroxide and ammonium persulfate are first dissolved together in a solvent. The stainless steel mesh is then completely immersed in the mixed solution containing sodium hydroxide and ammonium persulfate for etching. After etching, the etched stainless steel mesh is immersed in an oxalic acid solution for treatment, and finally dried to obtain the stainless steel mesh oil-water separation material. Etching the stainless steel mesh using a mixed solution containing sodium hydroxide and ammonium persulfate increases the mesh's roughness and surface area. Treating the etched stainless steel mesh in an oxalic acid solution significantly improves its oleophobicity and hydrophilicity. The resulting stainless steel mesh oil-water separation material exhibits excellent oil-water separation performance, enabling rapid and efficient separation of oily wastewater.

[0032] In some embodiments, in the mixed solution containing sodium hydroxide and ammonium persulfate, the mass ratio of ammonium persulfate to sodium hydroxide is 20:80 to 40:60. Preferably, the mass ratio of ammonium persulfate to sodium hydroxide is 20:80 to 30:70.

[0033] In some embodiments, in the mixed solution containing sodium hydroxide and ammonium persulfate, the mass concentration of sodium hydroxide is 8% to 15%, and the mass concentration of ammonium persulfate is 3% to 5%. Preferably, in the mixed solution containing sodium hydroxide and ammonium persulfate, the mass concentration of sodium hydroxide is 12%, and the mass concentration of ammonium persulfate is 3.5%.

[0034] In some embodiments, the oxalic acid solution has a mass concentration of 0.5% to 3%. Preferably, the oxalic acid solution has a mass concentration of 1%.

[0035] In some embodiments, the stainless steel mesh has an aperture of 800 to 3000 mesh. Preferably, the stainless steel mesh has an aperture of 1400 to 2000 mesh.

[0036] In some embodiments, the stainless steel mesh is immersed in a mixed solution containing sodium hydroxide and ammonium persulfate at 20–70°C for 1–72 hours. Preferably, the stainless steel mesh is immersed in a mixed solution containing sodium hydroxide and ammonium persulfate at 40–60°C for 18–36 hours.

[0037] In some embodiments, the stainless steel mesh is removed and immersed in an oxalic acid solution at 20–70°C for 1–10 hours to obtain a stainless steel mesh oil-water separation material.

[0038] In some embodiments, the solvents for the mixed solution containing sodium hydroxide and ammonium persulfate, and the oxalic acid solution, are one or more selected from water, ethanol, dimethylformamide, and dimethylacetamide, respectively. Preferably, the solvents for the mixed solution containing sodium hydroxide and ammonium persulfate, and the oxalic acid solution, are one or two selected from water and ethanol, respectively.

[0039] In some embodiments, the stainless steel mesh is industrial-grade stainless steel mesh or non-industrial-grade stainless steel mesh. Preferably, the stainless steel mesh is industrial-grade stainless steel mesh.

[0040] In some embodiments, the sodium hydroxide is industrial-grade sodium hydroxide or non-industrial-grade sodium hydroxide. Preferably, the sodium hydroxide is industrial-grade sodium hydroxide.

[0041] In some embodiments, the ammonium persulfate is industrial-grade or non-industrial-grade ammonium persulfate. Preferably, the ammonium persulfate is industrial-grade ammonium persulfate.

[0042] In some embodiments, the oxalic acid is industrial-grade oxalic acid or non-industrial-grade oxalic acid. Preferably, the oxalic acid is industrial-grade oxalic acid.

[0043] It should be noted that stainless steel mesh, sodium hydroxide, ammonium persulfate, and oxalic acid are commonly used materials in this field and there are no special restrictions.

[0044] A second aspect of the present invention provides a stainless steel mesh oil-water separation material, which is obtained by the preparation method of the stainless steel mesh oil-water separation material.

[0045] The third aspect of the present invention provides the application of the stainless steel mesh oil-water separation material in oil-water separation.

[0046] A fourth aspect of the present invention provides an oil-water separation method, comprising the following steps:

[0047] The oil-water mixture is placed on one side of the stainless steel mesh oil-water separator material;

[0048] The water in the oil-water mixture is driven through the stainless steel mesh oil-water separation material under the action of driving force.

[0049] In some embodiments, the oil in the oil-water mixture is one or more of engine oil, toluene, petroleum ether, paraffin oil, and diethyl ether.

[0050] In some embodiments, the driving force is gravity or pressure. For example, an oil-water mixture is placed on the stainless steel mesh oil-water separator, allowing water in the mixture to pass through the separator under its own weight. Alternatively, an oil-water mixture is placed on one side of the stainless steel mesh oil-water separator, and pressure is applied to the mixture, causing water to pass through.

[0051] The following are some typical embodiments. In the following embodiments, all raw materials used are commercially available products.

[0052] Examples 1 to 12

[0053] 3g of sodium hydroxide and 1g of ammonium persulfate were fully dissolved in 96g of water to obtain a mixed solution. A stainless steel mesh with a 1400-mesh aperture was immersed in the mixed solution for etching at 40℃ for 24 hours to obtain an etched stainless steel mesh. Then, 1g of oxalic acid was fully dissolved in 99g of water to obtain an oxalic acid solution. The etched stainless steel mesh was immersed in the oxalic acid solution for 4 hours at 40℃ to obtain a stainless steel mesh oil-water separation material.

[0054] By changing parameters such as the amount of sodium hydroxide, the amount of ammonium persulfate, the etching time, the amount of oxalic acid, and the oxalic acid treatment time, different stainless steel mesh oil-water separation materials were obtained using the same steps.

[0055] The specific parameters of Examples 1 to 12 are shown in Table 1.

[0056] Table 1 Specific parameters of Examples 1 to 12

[0057]

[0058] Surface analysis of untreated stainless steel mesh and the stainless steel mesh oil-water separation material obtained in Example 9 was performed using scanning electron microscopy (SEM). The analysis results of the untreated stainless steel mesh are as follows: Figure 1 As shown, the surface of the untreated stainless steel mesh is generally smooth. The analysis results of the oil-water separation material of the stainless steel mesh obtained in Example 9 are as follows: Figure 2As shown, after etching with a mixed solution containing sodium hydroxide and ammonium persulfate and treatment with oxalic acid, the stainless steel surface mainly exhibits an irregular polygonal structure with obvious boundaries between the polygons. The surface of the irregular polygons presents a rough, uneven structure. In Examples 1 to 12, with the change in the composition of sodium hydroxide and ammonium persulfate, the overall roughness of the obtained stainless steel mesh morphology increases with the increase of the concentration of both.

[0059] The stainless steel mesh oil-water separation material obtained in Example 9 was characterized using Fourier Transform Infrared Spectroscopy (FTIR), and the test results are as follows: Figure 3 As shown. In the infrared spectrum, 1700 cm⁻¹ -1 The peak at 3450 cm⁻¹ is the characteristic absorption peak of the carbonyl group (C=O). -1 The absorption peak at that location is a hydroxyl absorption peak. Through analysis... Figure 3 Analysis revealed that the carbonyl and hydroxyl groups on the surface of the stainless steel mesh increased after etching and oxalic acid treatment, indicating that the surface of the stainless steel mesh exhibited more polar groups after etching and oxalic acid treatment. The main processes for introducing carbonyl and hydroxyl groups into the stainless steel mesh are as follows:

[0060] The stainless steel mesh is first etched in an ammonium persulfate solution containing sodium hydroxide, forming a black ferric hydroxide (FeO(OH)) on the surface. The specific process is as follows:

[0061] Fe+2NaOH+(NH4)2S2O4→FeO(OH)↓+Na2SO4+NH3↑+H2O;

[0062] Ferric hydroxide reacts with oxalic acid to form ferric oxalate precipitate (Fe2(C2O4)3). The reaction process is as follows:

[0063] FeO(OH)+H2C2O4→Fe2(C2O4)3↓+H2O.

[0064] Ferric oxalate adheres to the surface of the stainless steel mesh in the form of a precipitate, and forms a pentahydrate ferric oxalate precipitate (Fe2(C2O4)3·5H2O) in the presence of water. The surface of this precipitate has high hydrophilicity.

[0065] X-ray photoelectron spectroscopy (XPS) analysis was performed on the stainless steel mesh oil-water separation material obtained in Example 9. The results, after peak separation and fitting, are as follows: Figure 4 As shown. From Figure 4 As can be seen, the energy spectrum of the treated stainless steel mesh shows strong C=O bond, CC bond, and C-OH energy spectrum signals. This indicates that a large number of polar groups other than metal elements were formed on the stainless steel surface, the stainless steel mesh surface was successfully etched, and a large amount of Fe2(C2O4)3·5H2O was formed.

[0066] Contact angle tests were performed on the untreated stainless steel mesh and the stainless steel mesh oil-water separation material obtained in Example 9. The results are as follows: Figure 5 As shown, on the surface of the untreated stainless steel mesh, water can exist stably in a hemispherical droplet shape, and the droplets do not change significantly after being placed for 0.5 hours. When water droplets are dropped onto the surface of the stainless steel mesh oil-water separation material obtained in Example 9, the droplets penetrate the surface within 2 seconds and cannot form stable droplets. Moreover, the underwater oil contact angle of the stainless steel mesh oil-water separation material obtained in Example 9 can reach 161°. Its high oleophobicity mainly comes from two aspects: First, a large amount of Fe2(C2O4)3·5H2O precipitate is formed on the surface of the stainless steel mesh after oxalic acid treatment. The accumulation of this precipitate increases the roughness of the stainless steel surface, forming a lotus leaf effect and increasing the oleophobicity; Second, Fe2(C2O4)3·5H2O contains a large amount of water of crystallization, which can form a hydration layer with free water molecules, further increasing the oleophobicity of the stainless steel.

[0067] Examples 13 to 17

[0068] 12g of sodium hydroxide and 3.5g of ammonium persulfate were dissolved in 84.5g of water to prepare a mixed solution of 12% sodium hydroxide and 3.5% ammonium persulfate. A stainless steel mesh was then immersed in this mixed solution and etched at 40℃ for 24 hours to obtain the etched stainless steel mesh. Next, 0.2g of oxalic acid was dissolved in 99.8g of water to obtain an oxalic acid solution. The etched stainless steel mesh was then immersed in the oxalic acid solution at 40℃ for 4 hours to obtain a stainless steel mesh oil-water separation material.

[0069] A series of stainless steel mesh oil-water separation materials can be obtained by changing the concentration of oxalic acid solution, and their specific parameters are shown in Table 2.

[0070] Table 2 Specific parameters of Examples 13 to 17

[0071]

[0072] The stainless steel mesh oil-water separation materials obtained in Examples 13 to 17 were analyzed using SEM. The surface of the obtained stainless steel mesh oil-water separation materials generally exhibited a rough structure. As the amount of oxalic acid increased, the roughness of the surface of the stainless steel mesh oil-water separation materials first increased and then decreased. Among them, the roughness was the highest when the oxalic acid concentration was 1%.

[0073] The stainless steel mesh oil-water separation materials obtained in Examples 13 to 17 were characterized using infrared spectroscopy. Analysis revealed that as the concentration of oxalic acid increased, the oil-water separation material obtained at 1700 cm⁻¹... -1 3450cm -1The absorption peak at the point also gradually became stronger, indicating that the number of polar groups on the surface of the stainless steel mesh increased with the increase of oxalic acid concentration.

[0074] XPS characterization of the stainless steel mesh oil-water separation materials obtained in Examples 13 to 17 revealed that the signals of C=O bonds, CC bonds, and C-OH bonds increased with the increase of oxalic acid content in the solution.

[0075] Underwater oil contact angle tests were conducted on the stainless steel mesh oil-water separation materials obtained in Examples 13 to 17. The results showed that the underwater oil contact angle varied within the range of 155° to 161°. Specifically, the underwater oil contact angle of the stainless steel mesh oil-water separation material in Example 13 was as follows: Figure 6 As shown, the contact angle is 155°. The underwater oil contact angle of the stainless steel mesh oil-water separator material in Example 15 is as follows. Figure 6 As shown, the contact angle is 159°.

[0076] Examples 18 to 22

[0077] 12g of sodium hydroxide and 3.5g of ammonium persulfate were dissolved in 84.5g of water to prepare a mixed solution of 12% sodium hydroxide and 3.5% ammonium persulfate. A stainless steel mesh was then placed in this mixed solution and etched at 40°C for 24 hours to obtain the etched stainless steel mesh. The etched stainless steel mesh was then treated in a 1% oxalic acid solution at 40°C for 1 hour to obtain the stainless steel mesh oil-water separation material.

[0078] A series of stainless steel mesh oil-water separation materials can be obtained by changing the treatment time of oxalic acid solution, and their specific parameters are shown in Table 3.

[0079] Table 3 Specific parameters of Examples 18 to 22

[0080]

[0081] The stainless steel mesh oil-water separation materials obtained in Examples 18 to 22 were analyzed using SEM. The surface of the obtained stainless steel mesh oil-water separation materials showed an overall rough structure. As the treatment time of oxalic acid solution increased, the roughness first increased, and after 4 hours of treatment, the roughness remained basically unchanged.

[0082] The stainless steel mesh oil-water separation materials obtained in Examples 18 to 22 were characterized using infrared spectroscopy. Analysis revealed that as the treatment time with oxalic acid solution increased, the resulting stainless steel mesh at 1700 cm⁻¹ decreased. -1 3450cm -1 The absorption peak at that point also initially increases, then remains unchanged.

[0083] XPS characterization of the stainless steel mesh oil-water separation materials obtained in Examples 18 to 22 revealed that the signals of C=O bonds, CC bonds, and C-OH bonds increased with the increase of oxalic acid solution treatment time.

[0084] Underwater oil contact angle characterization was performed on the stainless steel mesh oil-water separation materials obtained in Examples 18 to 22. It was found that the contact angle initially increased; the contact angle reached its maximum of 161° after 4 hours of oxalic acid treatment (Example 9); with further increase in treatment time, the contact angle showed a decreasing trend. A photograph of the underwater oil contact angle of the stainless steel mesh oil-water separation material of Example 18 is shown below. Figure 6 As shown, the contact angle is 157°; underwater oil contact angle photograph of the stainless steel mesh oil-water separation material in Example 22 is shown below. Figure 6 As shown, the contact angle is 159°.

[0085] Examples 23 to 27

[0086] The stainless steel mesh oil-water separation material prepared in Example 9 was cut into 2cm × 2cm pieces for oil-water separation experiments. First, refrigeration oil was mixed with water at a ratio of 1:9 to obtain an oil-water mixture. The stainless steel mesh oil-water separation material prepared in Example 9 was used as a separation membrane and installed on a separator. The separator structure is as follows: Figure 7 As shown. 100 mL of oil-water mixture was poured into the separator from the top for oil-water separation experiment. The water flux was calculated using Formula 1, and the oil-water separation efficiency was calculated using Formula 2.

[0087] Separation flux (Flux) = V / St (1)

[0088] Where V represents the volume of water passing through the separator, in liters; S represents the effective cross-sectional area of ​​the oil-water separation material during the separation process, in square meters; and t represents the time of oil-water separation, in hours.

[0089] Separation efficiency (SE)% = (1-C) f / C0)(2)

[0090] Among them, C f C0 represents the weight of the oil after separation, while C0 represents the weight of the oil before separation.

[0091] Repeat the above separation experiment 10 times and calculate the average separation flux and separation efficiency.

[0092] By conducting separation experiments with different types of oil, a series of different separation flux and separation efficiency data can be obtained, and the specific parameters are shown in Table 4.

[0093] Table 4 Specific parameters of different oil-water mixtures

[0094] Example Oil types Oil dosage (mL) Water usage (mL) Example 23 Refrigeration oil 10 90 Example 24 Toluene 10 90 Example 25 petroleum ether 10 90 Example 26 paraffin oil 10 90 Example 27 Diethyl ether 10 90

[0095] Separation flux and separation efficiency of various oil-water mixtures, such as Figure 8 As shown. The separation flux varies depending on the type of oil; paraffin oil and refrigeration oil can have average fluxes exceeding 5.0 × 10⁻⁶. 4 The average water flux of toluene was also higher than 2.7 × 10⁻⁶ liters per square meter per hour. 4 The separation throughput was liters per square meter per hour. Although the separation flux varied considerably, the separation efficiency of all five oil-water mixtures was higher than 99.5% during the separation process.

[0096] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a stainless steel mesh oil-water separation material, characterized in that, Includes the following steps: At 40~60℃, the stainless steel mesh is immersed in a mixed solution containing sodium hydroxide and ammonium persulfate for 18~36h, so that black iron hydroxide is formed on the surface of the stainless steel mesh. The stainless steel mesh is removed and immersed in an oxalic acid solution at 20~70℃ for 4~10 hours to form a precipitate of ferric oxalate pentahydrate on the surface of the stainless steel mesh, thus obtaining an oil-water separation material for the stainless steel mesh. In the mixed solution containing sodium hydroxide and ammonium persulfate, the mass concentration of sodium hydroxide is 8%~15%, and the mass concentration of ammonium persulfate is 3%~5%; the mass concentration of the oxalic acid solution is 1%~3%. The solvent for the mixed solution containing sodium hydroxide and ammonium persulfate, and the oxalic acid solution, is water; The underwater oil contact angle of the stainless steel mesh oil-water separator is 159°~161°.

2. A stainless steel mesh oil-water separation material, characterized in that, It is obtained by the preparation method of the stainless steel mesh oil-water separation material according to claim 1.

3. The application of the stainless steel mesh oil-water separation material according to claim 2 in oil-water separation.

4. An oil-water separation method, characterized in that, Includes the following steps: The oil-water mixture is placed on one side of the stainless steel mesh oil-water separator material as described in claim 2; The water in the oil-water mixture is driven through the stainless steel mesh by a driving force.

5. The method according to claim 4, characterized in that, The oil in the oil-water mixture is one or more of the following: engine oil, toluene, petroleum ether, paraffin oil, and diethyl ether.

Images