Super-hydrophobic fiber membrane with pleated structure and preparation method

Abstract

This invention discloses a superhydrophobic fiber membrane with a wrinkled structure and its preparation method. The preparation method is as follows: immersing a polypropylene fiber membrane in a methanol solution of a photoinitiator; removing it and irradiating it under a UV lamp; then immersing it in a methanol solution of an amino monomer and irradiating it under a UV lamp; then immersing it in a hexane solution of an acyl chloride, removing it, and then immersing it in a methanol solution of a hydroxyl monomer for interfacial polymerization; removing it; drying it; immersing it in a hexane solution of a long-chain alkylchlorosilane, removing it, and drying it to obtain a superhydrophobic fiber membrane with a wrinkled surface structure. The method of this invention is simple, easy to implement, and operates under mild conditions, requiring no precision instruments. It offers fast separation speed, high efficiency, and good reusability. When used to separate water-in-oil emulsions containing surfactants, the wrinkled structure on the fiber membrane surface increases the contact area between the superhydrophobic surface and the emulsion, promoting the coalescence and demulsification of microemulsions, and achieving a water retention rate of over 99%.

Description

Technical Field

[0001] This invention belongs to the field of superhydrophobic fiber membrane preparation, and particularly relates to a superhydrophobic fiber membrane with a pleated structure, its preparation method, and its application in oil-water separation. Background Technology

[0002] With the continuous expansion of industrial production, oil-water emulsions generated in industries such as petroleum extraction, chemicals, and pharmaceuticals, if not properly separated, will result in resource waste and adverse effects on the environment and human health. Therefore, the efficient separation and recovery of emulsion products has attracted widespread attention. Traditional oil-water separation technologies, including gravity separators, skimmers, and flotation, suffer from drawbacks such as low efficiency, high energy consumption, and large footprint. Furthermore, they are not ideal for separating water-in-oil emulsions with a diameter less than 20 μm.

[0003] In recent years, the unique wettability of superhydrophobic materials has attracted widespread attention. Superhydrophobic surfaces exhibit a contact angle greater than 150° and a roll-off angle less than 10° with water droplets, making them highly valuable for oil-water separation due to their special selectivity towards oil and water. Superhydrophobic materials can be prepared by controlling the micro / nano structure and surface energy of solid surfaces. Chinese patent CN108939952A discloses a method for preparing a superhydrophobic fiber membrane. This method first prepares a nanofiber membrane through electrospinning, then polymerizes it using spray deposition and ultraviolet irradiation to generate polyaniline micro / nanoparticles which are loaded onto the fiber membrane surface. Further surface etching is then performed to obtain a superhydrophobic nanofiber membrane for oil-water separation. This technology suffers from drawbacks such as cumbersome preparation processes and expensive equipment. Chinese patent CN104988737A discloses a method for preparing a superhydrophobic textile. Polyester fiber fabric is sequentially immersed in different buffer solutions, and nanoparticles generated by dopamine polymerization are deposited onto the fiber surface adhered with polydopamine. Finally, the fibers are treated with a fluorine-containing low surface energy modifier to obtain the superhydrophobic textile. The above-mentioned technologies have the drawbacks of using raw materials containing fluorine and producing products with poor stability. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a superhydrophobic fiber membrane with a pleated structure.

[0005] The second objective of this invention is to provide a method for preparing a superhydrophobic fiber membrane with a pleated structure.

[0006] The third objective of this invention is to provide an application of a superhydrophobic fiber membrane with a pleated structure in oil-water separation.

[0007] The technical solution of this invention is summarized as follows:

[0008] A method for preparing a superhydrophobic fiber membrane with a wrinkled structure includes the following steps:

[0009] (1) Immerse the polypropylene fiber membrane in a methanol solution of photoinitiator with a concentration of 0.1wt%-10wt% for 1h-12h; remove it and irradiate it under a UV lamp for 1min-3min;

[0010] (2) Immerse the fiber membrane obtained in step (1) in a methanol solution of amine monomers with a concentration of 0.5wt%-5wt% and irradiate it under a UV lamp for 3min-15min; remove it and immerse it in a hexane solution of acyl chlorides with a concentration of 0.01wt%-0.5wt% for 3min-10min; remove it and immerse it in a methanol solution of hydroxyl monomers with a concentration of 0.1wt%-1wt% for 3min-10min to carry out interfacial polymerization; remove it and dry it.

[0011] (3) Immerse the fiber membrane obtained in step (2) in a hexane solution of long-chain alkyl chlorosilane with a concentration of 0.1wt%-5wt% for 6-12 hours, take it out, dry it, and obtain a superhydrophobic fiber membrane with a wrinkled surface.

[0012] Preferably, the polypropylene fiber membrane is a polypropylene fiber membrane with a pore size of 0.1μm-10μm.

[0013] Preferably, the photoinitiator is benzophenone, 4-methylbenzophenone, 2,4-dihydroxybenzophenone, 4,4'-bis(N,N-dimethylamino)benzophenone or 2-isopropylthioxanthraphenone.

[0014] Preferably, the amino monomer is N-methylallylamine, diallylamine, 5-hexen-1-amine, or 4-penten-1-amine.

[0015] Preferably, the acyl chloride is pyromellitic chloride, terephthaloyl chloride, or isophthaloyl chloride.

[0016] Preferably, the hydroxy monomer is 3,4-dihydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid, 4-hydroxybenzoic acid, salicylic acid, or aminosalicylic acid.

[0017] Preferably, the long-chain alkylchlorosilane is octyltrichlorosilane, decyltrichlorosilane, dodecyltrichlorosilane, or octadecyltrichlorosilane.

[0018] A superhydrophobic fiber membrane with a wrinkled structure was prepared by the above preparation method.

[0019] The above-mentioned application of a superhydrophobic fiber membrane with a pleated structure in the field of oil-water separation.

[0020] Advantages of this invention:

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The preparation method of the present invention has low requirements for the matrix material, and can directly modify the polypropylene fiber membrane. The preparation method is simple and easy to implement, the conditions are mild, and no precision instruments are required. The superhydrophobic fiber membrane prepared is free of fluorine-containing materials, has fast oil-water separation speed, high efficiency and good reusability.

[0023] (2) The method of the present invention grows a wrinkle-like micro-nano structure on the surface of polypropylene fiber membrane by covalent grafting, so that the fiber membrane has superhydrophobic properties and its stability is better than that of micro-nano structures constructed on the fiber surface by deposition method.

[0024] (3) The superhydrophobic polypropylene fiber membrane prepared by the present invention can be used to separate water-in-oil emulsions containing surfactants. The wrinkled structure on the surface of the fiber membrane can increase the contact area between the superhydrophobic surface and the emulsion, promote the aggregation and demulsification of micro emulsions, and the water retention rate can reach more than 99%.

[0025] (4) The superhydrophobic polypropylene fiber membrane prepared by the present invention has good solvent resistance, can separate emulsions of various organic systems, and can be reused. Attached Figure Description

[0026] Figure 1 The image shows a scanning electron microscope (SEM) image of the surface of a superhydrophobic fiber membrane with a wrinkled structure prepared in Example 1. Image a is a 10,000x SEM image; image b is a 20,000x SEM image.

[0027] Figure 2 This diagram illustrates the contact angle of a water droplet on the surface of a wrinkled superhydrophobic fiber membrane prepared in Example 1. Where a represents the static contact angle of the water droplet on the surface; and b represents the dynamic contact angle of the water droplet on the surface.

[0028] Figure 3 The separation results of a water / dichloromethane emulsion containing Span 80 surfactant using a superhydrophobic fiber membrane with a wrinkled structure prepared in Example 1 are shown. In the figures, a represents the observation results of the emulsion before separation using a polarizing microscope; b represents the observation results of the organic phase after separation using a polarizing microscope. Detailed Implementation

[0029] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments.

[0030] Example 1

[0031] A method for preparing a superhydrophobic fiber membrane with a wrinkled structure includes the following steps:

[0032] (1) Immerse a polypropylene fiber membrane with a pore size of 1 μm in a methanol solution of benzophenone with a concentration of 1 wt% for 12 h; take it out and irradiate it under a UV lamp for 3 min under UV light wavelength of 315 nm-400 nm.

[0033] (2) Immerse the fiber membrane obtained in step (1) in a methanol solution of N-methylallylamine with a concentration of 5 wt%, and irradiate it for 15 min under a UV lamp with a UV wavelength of 315 nm-400 nm; remove it, and then immerse it in a hexane solution of pyromellitic trimethylol chloride with a concentration of 0.5 wt% for 10 min; remove it, and then immerse it in a methanol solution of 3,4-dihydroxybenzoic acid with a concentration of 1 wt% for 10 min to carry out interfacial polymerization; remove it; and dry it.

[0034] (3) The fiber membrane obtained in step (2) is immersed in a hexane solution of octadecyltrichlorosilane with a concentration of 5 wt% for 12 h, taken out and dried to obtain a superhydrophobic fiber membrane with a wrinkled surface.

[0035] Tests showed that the water droplet contact angle on the surface of the superhydrophobic fiber membrane with a pleated structure was 154° and the roll-off angle was 6°.

[0036] See Figure 1 , Figure 2 .

[0037] Example 2

[0038] A method for preparing a superhydrophobic fiber membrane with a wrinkled structure includes the following steps:

[0039] (1) Immerse a polypropylene fiber membrane with a pore size of 0.1 μm in a methanol solution of 4-methylbenzophenone with a concentration of 0.1 wt% for 6 h; take it out and irradiate it under a UV lamp for 2 min under UV light wavelength of 315 nm-400 nm.

[0040] (2) The fiber membrane obtained in step (1) is immersed in a methanol solution of diallylamine with a concentration of 0.5 wt%, and irradiated for 10 min under a UV lamp with a UV wavelength of 315 nm-400 nm; it is then removed and immersed in a hexane solution of terephthaloyl chloride with a concentration of 0.5 wt% for 5 min, removed, and then immersed in a methanol solution of 4-amino-3-hydroxybenzoic acid with a concentration of 0.5 wt% for 5 min to carry out interfacial polymerization; it is then removed and dried;

[0041] (3) The fiber membrane obtained in step (2) is immersed in a hexane solution of octyltrichlorosilane with a concentration of 3wt% for 9 hours, taken out and dried to obtain a superhydrophobic fiber membrane with a wrinkled surface.

[0042] Tests showed that the water droplet contact angle on the surface of the superhydrophobic fiber membrane with a pleated structure was 152° and the roll-off angle was 7°.

[0043] Example 3

[0044] A method for preparing a superhydrophobic fiber membrane with a wrinkled structure includes the following steps:

[0045] (1) Immerse a polypropylene fiber membrane with a pore size of 10 μm in a methanol solution of 2,4-dihydroxybenzophenone with a concentration of 10 wt% for 1 h; take it out and irradiate it under a UV lamp for 1 min under UV light wavelength of 315 nm-400 nm.

[0046] (2) Immerse the fiber membrane obtained in step (1) in a methanol solution of 5-hexen-1-amine with a concentration of 3 wt%, and irradiate it for 3 min under a UV lamp with a UV wavelength of 315 nm-400 nm; remove it and immerse it in a hexane solution of isophthaloyl chloride with a concentration of 0.01 wt% for 3 min; remove it and immerse it in a methanol solution of 4-hydroxybenzoic acid with a concentration of 0.1 wt% for 3 min to carry out interfacial polymerization; remove it and dry it.

[0047] (3) The fiber membrane obtained in step (2) is immersed in a hexane solution of decyltrichlorosilane with a concentration of 0.1 wt% for 6 hours, taken out and dried to obtain a superhydrophobic fiber membrane with a wrinkled surface.

[0048] Tests showed that the water droplet contact angle on the surface of the superhydrophobic fiber membrane with a pleated structure was 151° and the roll-off angle was 8°.

[0049] Example 4

[0050] A method for preparing a superhydrophobic fiber membrane with a wrinkled structure includes the following steps:

[0051] (1) Immerse a polypropylene fiber membrane with a pore size of 0.1 μm in a methanol solution of 4,4'-bis(N,N-dimethylamino)benzophenone with a concentration of 2 wt% for 1 h; take it out and irradiate it under a UV lamp for 2 min under UV light wavelength of 315 nm-400 nm.

[0052] (2) Immerse the fiber membrane obtained in step (1) in a methanol solution of 4-penten-1-amine with a concentration of 0.5 wt%, and irradiate it for 10 min under a UV lamp with a UV wavelength of 315 nm-400 nm; remove it, immerse it in a hexane solution of 0.5 wt% terephthaloyl chloride with a concentration of 0.5 wt% for 5 min, remove it, and then immerse it in a methanol solution of 0.5 wt% salicylic acid with a concentration of 0.5 wt% for 5 min to carry out interfacial polymerization; remove it; and dry it.

[0053] (3) The fiber membrane obtained in step (2) is immersed in a hexane solution of dodecyltrichlorosilane with a concentration of 3wt% for 9 hours, taken out and dried to obtain a superhydrophobic fiber membrane with a wrinkled surface.

[0054] Tests showed that the water droplet contact angle on the surface of the superhydrophobic fiber membrane with a pleated structure was 154° and the roll-off angle was 7°.

[0055] Experiments have shown that when 2-isopropylthioxanthone is substituted for 4,4'-bis(N,N-dimethylamino)benzophenone in this embodiment, and all other aspects are the same as in this embodiment, the properties of the superhydrophobic fiber membrane with a wrinkled surface obtained are similar to those of the superhydrophobic fiber membrane with a wrinkled surface obtained in this embodiment.

[0056] Performance testing

[0057] Oil-water separation test, stability test and durability test were performed on the superhydrophobic fiber membrane with a pleated structure prepared according to the present invention.

[0058] Preparation:

[0059] An aqueous mixture of dichloromethane with a mass concentration of 99% was mixed with Span80 surfactant to a final concentration of 1 g / L, and stirred under high shear to obtain emulsion 1.

[0060] An aqueous mixture of p-xylene with a mass concentration of 99% was mixed with Span80 surfactant to a final concentration of 1 g / L, and stirred under high shear to obtain emulsion 2.

[0061] A mixture of kerosene and water with a mass concentration of 99% was mixed with Span80 surfactant to a final concentration of 1 g / L, and then stirred under high shear to obtain emulsion 3.

[0062] An emulsion 4 was obtained by adding Span80 surfactant to a cyclohexane aqueous solution with a mass concentration of 99% and stirring under high shear to achieve a final concentration of 1 g / L.

[0063] An emulsion 5 was obtained by adding Span80 surfactant to a water mixture with a mass concentration of 99% n-octane to achieve a final concentration of 1 g / L, followed by high-shear stirring.

[0064] Emulsions 1-5 were separated using a superhydrophobic fiber membrane with a wrinkled structure prepared in Example 1. The water separation rates in each sample were 99.3%, 99.1%, 99.3%, 99.1%, and 99.0%, respectively.

[0065] A superhydrophobic fiber membrane with a wrinkled structure prepared in Example 1 was immersed in dichloromethane and left at room temperature for 30 days. The water droplet contact angle was 153° and the roll-off angle was 6°. It exhibits good solvent resistance.

[0066] Emulsion 1 was separated using a superhydrophobic fiber membrane with a wrinkled structure prepared in Example 1. The superhydrophobic fiber membrane with the wrinkled structure was washed with ethanol, dried, and then used to separate a second portion of emulsion 1. The separation was repeated 20 times in total. The separation efficiency of water in the emulsion remained at 99%, indicating good stability.

[0067] Experiments have shown that the superhydrophobic fiber membranes with pleated structures prepared in Examples 2, 3, and 4 have similar separation efficiency, solvent resistance, and stability to the superhydrophobic fiber membrane with pleated structures prepared in Example 1.

Claims

1. A method for preparing a superhydrophobic fiber membrane with a wrinkled structure, characterized in that, Includes the following steps: (1) Immerse the polypropylene fiber membrane in a methanol solution of photoinitiator with a concentration of 0.1wt%-10wt% for 1h-12h; take it out and irradiate it under a UV lamp for 1min-3min; (2) Immerse the fiber membrane obtained in step (1) in a methanol solution containing amine monomers with double bonds at a concentration of 0.5wt%-5wt%, and irradiate it under a UV lamp for 3min-15min. Remove the sample and immerse it in a hexane solution of acyl chloride (0.01wt%-0.5wt%) for 3-10 minutes. Remove the sample and immerse it in a methanol solution of hydroxyl monomer (0.1wt%-1wt%) for 3-10 minutes for interfacial polymerization. Remove the sample and dry it. (3) Immerse the fiber membrane obtained in step (2) in a hexane solution of long-chain alkyl chlorosilane with a concentration of 0.1wt%-5wt% for 6-12 hours, take it out, dry it, and obtain a superhydrophobic fiber membrane with a wrinkled surface. The acyl chloride is pyromellitic trimethylol chloride, terephthaloyl chloride, or isophthaloyl chloride; The long-chain alkylchlorosilane is octyltrichlorosilane, decyltrichlorosilane, dodecyltrichlorosilane, or octadecyltrichlorosilane.

2. The preparation method according to claim 1, characterized in that, The polypropylene fiber membrane is a polypropylene fiber membrane with a pore size of 0.1μm-10μm.

3. The preparation method according to claim 1, characterized in that, The photoinitiator is benzophenone, 4-methylbenzophenone, 2,4-dihydroxybenzophenone, 4,4'-bis(N,N-dimethylamino)benzophenone, or 2-isopropylthioxanthraphenone.

4. The preparation method according to claim 1, characterized in that, The amino monomer containing a double bond is N-methylallylamine, diallylamine, 5-hexen-1-amine, or 4-penten-1-amine.

5. The preparation method according to claim 1, characterized in that, The hydroxy monomer is 3,4-dihydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid, 4-hydroxybenzoic acid, salicylic acid, or aminosalicylic acid.

6. A superhydrophobic fiber membrane with a pleated structure prepared by the preparation method of any one of claims 1-5.

7. The application of a superhydrophobic fiber membrane with a pleated structure according to claim 6 in oil-water separation.

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