Preparation method of oil-resistant hydrogel modified stainless steel mesh separation membrane

Abstract

The application discloses a preparation method of an oil-resistant hydrogel modified stainless steel mesh separation membrane, and discloses the oil-resistant hydrogel modified stainless steel mesh separation membrane and the preparation method thereof. The preparation method comprises the following steps: taking a stainless steel mesh as a base film, adding a certain amount of acrylic acid, an ester monomer, an initiator, a physical crosslinking agent, a chemical crosslinking agent and a catalyst solution into water to form a prepolymerization solution, then immersing the stainless steel mesh into the prepolymerization solution, and forming a double-crosslinked hydrogel coating through in-situ free radical polymerization to obtain the hydrogel modified stainless steel mesh separation membrane. The separation membrane has the oil-resistant performance and long-term stable emulsion separation performance. Moreover, the preparation condition is mild, the energy consumption is low, and the separation membrane is easy to be produced on a large scale.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel preparation technology, specifically relating to a method for preparing a hydrogel-modified stainless steel mesh separation membrane for oil-water emulsion separation. Background Technology

[0002] Oil extraction and refining, cosmetics production, maritime shipping, and textile and leather manufacturing processes generate large quantities of oil-water emulsions. Direct discharge without treatment poses a serious threat to the ecological environment and human health. Oil-water emulsions are dispersion systems where one liquid is dispersed into another in the form of small droplets. They possess a stable core-shell structure, making them very difficult to treat. Membrane separation technology, as a representative of physical treatment technologies, offers advantages such as low energy consumption, high efficiency, and no secondary pollution, making it one of the most effective methods for treating oily wastewater. However, under long-term operating conditions, oil contamination can clog the pores of the separation membrane, leading to a rapid decline in membrane flux and separation efficiency, severely impacting the membrane's lifespan. Therefore, developing an oil-water separation membrane method with high-efficiency oil-resistant properties is extremely necessary. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing an oil-resistant hydrogel-modified stainless steel mesh separation membrane, so as to improve the oil resistance of the oil-water separation membrane.

[0004] To achieve the above objectives, the present invention provides an oil-resistant hydrogel-modified stainless steel mesh separation membrane, which is prepared by the following steps: using a stainless steel mesh as the base membrane, a certain amount of acrylic acid, ester monomers, initiator, physical crosslinking agent, chemical crosslinking agent, and catalyst solution are added to water to form a prepolymerization solution. Subsequently, the stainless steel mesh is immersed in the prepolymerization solution, and a double crosslinked hydrogel coating is formed through in-situ free radical polymerization, thereby obtaining an oil-resistant hydrogel-modified stainless steel mesh separation membrane.

[0005] Furthermore, the stainless steel mesh is 1000 mesh, and it needs to be ultrasonically cleaned for 30 minutes each in acetone, ethanol, and deionized water.

[0006] Furthermore, the ester monomers include hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0007] Furthermore, the mass ratio of ester monomers to acrylic acid is 1:1 to 8, and the mass fraction of monomers is 5 to 15 wt%.

[0008] Furthermore, the physical crosslinking agent is ferric chloride, and the concentration of the physical crosslinking agent is 0.5–1 mg / mL; the chemical crosslinking agent is N,N-methylenebisacrylamide, and the concentration of the chemical crosslinking agent is 0.5–1 mg / mL.

[0009] Furthermore, the initiator is potassium persulfate or ammonium persulfate, with an initiator concentration of 1–2 mg / mL; the catalyst is N,N,N,N-tetramethylethylenediamine.

[0010] Furthermore, the in-situ free radical polymerization temperature was 50 °C, and the polymerization time was 3–8 h.

[0011] The hydrogel-modified stainless steel mesh separation membrane and its preparation method provided by this invention have the following beneficial effects:

[0012] (1) In this invention, two monomers are used for in-situ polymerization on a stainless steel mesh. To improve the hydrophilicity and roughness of the stainless steel mesh, the ester monomers used contain hydrophilic hydroxyl groups and hydrophobic ester groups. By controlling the mass ratio of ester monomers to acrylic monomers to be 1:1 to 8, as the molecular weight of the copolymer increases, a micromicelle structure can be formed, thereby improving the roughness and hydrophilicity of the hydrogel coating. Therefore, the hydrogel-modified stainless steel mesh separation membrane has underwater superhydrophilic and superoleophobic properties. By utilizing the size control effect and wetting and coalescence effect of this separation material, efficient separation of oil-in-water emulsions can be achieved. Furthermore, due to the strong hydrophilicity of the hydrogel, a hydration layer can be formed to protect the separation material from oil contamination.

[0013] (2) In this invention, ferric chloride forms a complex with acrylic acid in the polymer chain to form a physical crosslinking network, and N,N-methylenebisacrylamide can also form a chemical crosslinking network with the copolymer segments. This dual crosslinking network not only effectively improves the mechanical strength of the hydrogel coating, but also prevents the hydrogel coating from swelling during long-term underwater application. Therefore, the hydrogel-modified stainless steel mesh separation membrane has long-term stable emulsion separation performance.

[0014] (3) This invention uses stainless steel mesh as raw material, which is abundant and low in cost. The in-situ polymerization method is adopted in the preparation process, which has a mild reaction temperature, low energy consumption, and is easy to produce on a large scale. In addition, the preparation and use of hydrogel-modified stainless steel mesh separation membrane are non-toxic and harmless, environmentally friendly, easy to clean and store, and have a long service life. Attached Figure Description

[0015] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly introduced below. The following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope.

[0016] Figure 1 The wettability test diagram of the hydrogel-modified stainless steel mesh separation membrane provided by the present invention;

[0017] Figure 2 The emulsion separation apparatus with hydrogel-modified stainless steel mesh separation membrane provided by the present invention, as well as optical photographs of the emulsion and the separated filtrate, are also included.

[0018] Figure 3 The present invention provides an anti-oil adhesion performance for a hydrogel-modified stainless steel mesh separation membrane. Detailed Implementation

[0019] The specific embodiments of the present invention are described below with reference to examples, but the present invention is not limited to the following examples.

[0020] Example 1

[0021] Hydroxypropyl acrylate and acrylic acid were added to 10 mL of water at a mass ratio of 1:1 to prepare a 5 wt% aqueous solution. Then, 5 mg of ferric chloride, 20 mg of potassium persulfate, 5 mg of N,N-methylenebisacrylamide, and 10 µL of N,N,N,N-tetramethylethylenediamine solution were added to the aqueous solution to form a prepolymerization solution. The stainless steel mesh was then cut into 3×3 cm pieces. 2 The stainless steel mesh was then ultrasonically cleaned sequentially in acetone, ethanol, and deionized water for 30 min each. Afterward, the pre-cleaned stainless steel mesh was immersed in a prepolymerization solution and polymerized in situ at 50°C for 8 hours. After the reaction, the stainless steel mesh was removed and rinsed with deionized water to remove any unattached polymer. Finally, the desired oil-resistant hydrogel-modified stainless steel mesh separation membrane was obtained. The hydrogel-modified stainless steel mesh separation membrane exhibited superoleophobic properties underwater, with a contact angle of 150°. When filtering an oil-in-water emulsion of n-hexane and water, the filtration efficiency was 97.56%, and even after 10 repetitions, the separation efficiency remained above 95%.

[0022] Example 2

[0023] Hydroxyethyl methacrylate and acrylic acid were added to 10 mL of water at a mass ratio of 1:4 to prepare a 10 wt% aqueous solution. Then, 10 mg of ferric chloride, 10 mg of potassium persulfate, 10 mg of N,N-methylenebisacrylamide, and 10 µL of N,N,N,N-tetramethylethylenediamine solution were added to the aqueous solution to form a prepolymerization solution. Finally, stainless steel mesh was cut into 3×3 cm pieces. 2 The stainless steel mesh was then ultrasonically cleaned sequentially in acetone, ethanol, and deionized water for 30 min each. Afterward, the pre-cleaned stainless steel mesh was immersed in a prepolymerization solution and polymerized in situ at 50°C for 5 hours. After the reaction, the stainless steel mesh was removed and rinsed with deionized water to remove any unattached polymer. Finally, the desired oil-resistant hydrogel-modified stainless steel mesh separation membrane was obtained. The hydrogel-modified stainless steel mesh separation membrane exhibited superoleophobic properties underwater, with a contact angle of 152°. When filtering an oil-in-water emulsion of n-hexane and water, the filtration efficiency was 98.25%, and even after 15 repetitions, the separation efficiency remained above 95%.

[0024] Example 3

[0025] Hydroxypropyl methacrylate and acrylic acid were added to 10 mL of water at a mass ratio of 1:8 to prepare a 10 wt% aqueous solution. Then, 10 mg of ferric chloride, 20 mg of potassium persulfate, 10 mg of N,N-methylenebisacrylamide, and 10 µL of N,N,N,N-tetramethylethylenediamine solution were added to the aqueous solution to form a prepolymerization solution. Finally, stainless steel mesh was cut into 3×3 cm pieces. 2 The stainless steel mesh was then ultrasonically cleaned sequentially in acetone, ethanol, and deionized water for 30 min each. Afterward, the pre-cleaned stainless steel mesh was immersed in a prepolymerization solution and polymerized in situ at 50°C for 5 hours. Following the reaction, the stainless steel mesh was removed and rinsed with deionized water to remove any unattached polymer. Finally, the desired oil-resistant hydrogel-modified stainless steel mesh separation membrane was obtained. The hydrogel-modified stainless steel mesh separation membrane exhibited superoleophobic properties underwater, with a contact angle of 157°. When filtering an oil-in-water emulsion of n-hexane and water, the filtration efficiency was 99.56%, and even after 20 repetitions, the separation efficiency remained above 95%.

[0026] Example 4

[0027] Hydroxypropyl methacrylate and acrylic acid were added to 10 mL of water at a mass ratio of 1:8 to prepare a 15 wt% aqueous solution. Then, 10 mg of ferric chloride, 20 mg of potassium persulfate, 10 mg of N,N-methylenebisacrylamide, and 10 µL of N,N,N,N-tetramethylethylenediamine solution were added to the aqueous solution to form a prepolymerization solution. Finally, stainless steel mesh was cut into 3×3 cm pieces. 2 The stainless steel mesh was then ultrasonically cleaned sequentially in acetone, ethanol, and deionized water for 30 min each. Afterward, the pre-cleaned stainless steel mesh was immersed in a prepolymerization solution and polymerized in situ at 50°C for 5 hours. After the reaction, the stainless steel mesh was removed and rinsed with deionized water to remove any unattached polymer. Finally, the desired oil-resistant hydrogel-modified stainless steel mesh separation membrane was obtained. The hydrogel-modified stainless steel mesh separation membrane exhibited superoleophobic properties underwater, with a contact angle of 153°. When filtering an oil-in-water emulsion of n-hexane and water, the filtration efficiency was 98.13%, and even after 15 repetitions, the separation efficiency remained above 95%.

[0028] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations.

Claims

1. A method for preparing an oil-resistant hydrogel-modified stainless steel mesh separation membrane, characterized in that... The preparation process involves using a stainless steel mesh as the base membrane, adding a certain amount of acrylic acid, ester monomers, initiator, physical crosslinking agent, chemical crosslinking agent, and catalyst solution to water to form a prepolymerization solution. Subsequently, the stainless steel mesh is immersed in the prepolymerization solution, and a double crosslinked hydrogel coating is formed through in-situ free radical polymerization, thus obtaining a hydrogel-modified stainless steel mesh separation membrane for emulsion separation. The ester monomers are selected from one or more of hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

2. The method for preparing an oil-resistant hydrogel-modified stainless steel mesh separation membrane according to claim 1, characterized in that, The stainless steel mesh is 1000 mesh and needs to be ultrasonically cleaned for 30 minutes each in acetone, ethanol and deionized water.

3. The method for preparing an oil-resistant hydrogel-modified stainless steel mesh separation membrane according to claim 1, characterized in that, The mass ratio of the ester monomer to acrylic acid is 1:1 to 1:8; based on the total mass of the ester monomer, acrylic acid and water, the total mass fraction of the ester monomer and acrylic acid is 5 to 15 wt%.

4. The method for preparing an oil-resistant hydrogel-modified stainless steel mesh separation membrane according to claim 1, characterized in that, The physical crosslinking agent is ferric chloride, with a concentration of 0.5–1 mg / mL; the chemical crosslinking agent is N,N-methylenebisacrylamide, with a concentration of 0.5–1 mg / mL.

5. The method for preparing an oil-resistant hydrogel-modified stainless steel mesh separation membrane according to claim 1, characterized in that, The initiator is potassium persulfate or ammonium persulfate, with an initiator concentration of 1–2 mg / mL; the catalyst is N,N,N,N-tetramethylethylenediamine.

6. The method for preparing an oil-resistant hydrogel-modified stainless steel mesh separation membrane according to claim 1, characterized in that, The in-situ free radical polymerization was carried out at a temperature of 50 °C for 3–8 h.

Images