A diatomite-based janus membrane, its preparation method and application

Abstract

A diatomite-based Janus film and a preparation method and application thereof, relate to the technical field of functional films, and solve the problems of complex preparation method and unstable material performance of the Janus film in the prior art.The preparation method of the diatomite-based Janus film comprises the following steps: (1) reacting diatomite, an organic solvent, a catalyst and a silane coupling agent to obtain silane-modified diatomite; (2) reacting the modified diatomite with a polymer to prepare a diatomite / polymer solution, and drying the diatomite / polymer solution into a film to obtain a diatomite / polymer composite film; and (3) performing steam fumigation treatment on one side of the diatomite / polymer composite film by using an oxidizing agent to obtain a diatomite / polymer Janus film.The porous structure of the silane-modified diatomite is utilized to form a large number of pore channels in the film, and the application of the Janus film in oil-water separation is ensured; through the oxidation reaction treatment, the hydrophilic side of the Janus film has the characteristics of being oil-repellent under water, and the hydrophobic side has the characteristics of being water-repellent under oil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional film, in particular to a diatomite-based Janus film and a preparation method and application thereof. BACKGROUND

[0002] At present, water pollution has become one of the major environmental challenges facing the world. With the acceleration of industrialization and urbanization, the sources of water pollution are increasing, including agricultural wastewater, industrial wastewater, domestic sewage and plastic pollution. Water pollution not only seriously endangers the ecological environment, but also directly affects human drinking water safety, food safety and health, therefore, developing water treatment and water pollution control technology has become the focus of current research.

[0003] Membrane separation technology is a high-efficiency, energy-saving and environmentally friendly separation technology, which has made remarkable progress in water treatment, gas separation, food processing, chemical engineering and other fields. Among them, Janus membrane is a kind of membrane material with special structure, which has two opposite surfaces, one side has hydrophilic or hydrophobic property, and the other side has opposite property. There are two preparation strategies for existing Janus membrane, one is to composite two polymer films with different properties by physical method, such as Chinese patent document CN110039863A, which uses hot pressing and bonding method to prepare double-sided heterogeneous micro-nano composite fiber membrane, uses centrifugal spinning or electrospinning technology to prepare hydrophilic CA fiber membrane and hydrophobic PVDF fiber membrane, and uses SiO2 coating and plasma grafting treatment technology to make PVDF fiber membrane have super-hydrophobic property, and under the condition of hot pressing (90-130℃) or dopamine, polyurethane bonding, the hydrophilic CA fiber membrane and super-hydrophobic PVDF fiber membrane are pasted to prepare single-sided super-hydrophobic and single-sided hydrophilic Janus micro-nano fiber membrane, although this method can be used for oil-water separation, but its preparation method is complex, the separation efficiency needs to be improved, and it does not have the ability of oil-water emulsion separation; Chinese patent document CN113774559A provides a PU(CA / PU)CA nanofiber Janus membrane with CA / PU blended nanofiber as transition interlayer, the application of transition interlayer improves the thermal stability and interface compatibility of the membrane to some extent, but there are problems of insufficient membrane delamination and low uniformity. The other strategy is to modify both sides or one side of the film with different wetting properties, such as Chinese patent document CN111871001A, which first modifies the substrate by immersing it in an aqueous solution containing acid organic matter and water-soluble iron salt, so that it has super-hydrophilic property, and then modifies one side of the substrate with polydimethylsiloxane under the protection of water, so that the prepared Janus material has one side super-hydrophilic and the other side super-hydrophobic, showing asymmetric wetting property, which can realize water directional transmission in air or oil, but the prepared Janus membrane is not easy to control, and the performance stability of the material is poor.

[0004] Therefore, in order to solve the above problems, researchers try to combine the two strategies, explore new composite materials and advanced preparation process, and develop a one side hydrophobic and the other side hydrophilic two-sided asymmetric wet Janus composite membrane. SUMMARY

[0005] In order to solve the problem of complex preparation method and poor material performance stability of the prior art Janus membrane, the present application provides a diatomite-based Janus membrane and its preparation method and application. The technical scheme of the present application is as follows:

[0006] A preparation method of a diatomite-based Janus membrane, comprising the following steps:

[0007] S1: weigh diatomite, organic solvent, catalyst, silane coupling agent into the reactor for reaction, after the reaction is completed, the reaction liquid is filtered, washed and filtered again to obtain silane modified diatomite;

[0008] S2: weigh the polymer, surfactant, dispersant and solvent into the reactor, stir to form a uniform polymer solution, continue to add the silane modified diatomite prepared in S1, stir to obtain a uniform diatomite / polymer solution, coat the diatomite / polymer solution on a coating machine to form a thin film, immerse the thin film in a precipitator and stand still, and then dry to obtain a diatomite / polymer composite membrane;

[0009] S3: oxidizing agent steam fumigation treatment is performed on one side of the diatomite / polymer composite membrane prepared in S2 to obtain a diatomite / polymer Janus membrane;

[0010] Further, the organic solvent is one or a combination of at least two of toluene, xylene, cyclohexane and cyclohexanone;

[0011] Further, the catalyst is one or a combination of at least two of N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, N,N,N',N'-tetramethylalkylene diamine, triethylamine and N,N-dimethylbenzylamine;

[0012] Further, the silane coupling agent is one or a combination of at least two of 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane;

[0013] Further, the polymer is one or a combination of at least two of polylactic acid (PLA), polybutylene adipate / terephthalate (PBAT), thermoplastic elastomer (TPEE), nylon, nylon elastomer, ethylene-vinyl acetate copolymer (EVA), polyurethane elastomer, polysulfone, polyethersulfone and polyacrylonitrile; diesters

[0014] ​Further, the surfactant is one or a combination of at least two of cetyltrimethylammonium bromide (CTAB), sodium dodecyl benzene sulfonate (SDBS), polysorbate (Tween) and sorbitan fatty acid ester (Span);

[0015] Further, the dispersant is one or a combination of at least two of polyethylene glycol, polyvinylpyrrolidone and polyvinyl alcohol;

[0016] Further, the solvent is one or a combination of at least two of chloroform, tetrahydrofuran, dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and hexafluoroisopropanol;

[0017] Further, the precipitant is any one of water, ethanol, water-dimethylformamide mixture, water-dimethyl sulfoxide mixture, ethanol-tetrahydrofuran mixture and ethanol-chloroform mixture;

[0018] Further, the oxidant is one or a combination of at least two of hydrogen peroxide and peracetic acid;

[0019] Further, the diatomite-based Janus film has a porous structure with two sides asymmetric, one side is a hydrophobic layer and the other side is a hydrophilic layer, and the thickness is 5-500 μm;

[0020] Further, the reaction temperature in S1 is 60℃, and the reaction time is 6h;

[0021] Further, the drying temperature in S2 is 50℃;

[0022] Further, the heating temperature in S3 is 80℃;

[0023] Further, the diatomite particle size is 5-50 μm;

[0024] Further, the specific surface area of the diatomite is greater than or equal to 30 m 2 g -1 ;

[0025] Further, the mass ratio of the diatomite to the silane coupling agent is 1-20:1;

[0026] Further, the mass ratio of the polymer, surfactant, dispersant and diatomite is 1-20:0.05-0.5:0.01-1:1.

[0027] A diatomite-based Janus film prepared by the above preparation method.

[0028] An application of the above diatomite-based Janus film, applied to oil-water separation.

[0029] Compared with the prior art, the present invention solves the problems of complex Janus membrane preparation process and poor material performance stability in the prior art, and has the following specific beneficial effects:

[0030] 1. The present invention combines silane-modified diatomaceous earth with a polymer to prepare a polymer / diatomaceous earth composite membrane. Due to the hydrophobicity of the thiol-modified diatomaceous earth, the prepared diatomaceous earth / polymer composite membrane exhibits hydrophobicity. An oxidation reaction converts the hydrophobic thiol groups on one side of the diatomaceous earth / polymer composite membrane into hydrophilic sulfonic acid groups, thereby transforming the polymer / diatomaceous earth composite membrane from being hydrophobic on both sides to a biaxially asymmetrically wettable diatomaceous earth-based Janus membrane with one side being hydrophobic and the other side being hydrophilic. The hydrophilic side of this diatomaceous earth-based Janus membrane exhibits underwater oleophobicity, while the hydrophobic side exhibits underwater hydrophobicity.

[0031] 2. Because the silane-modified diatomaceous earth has a porous structure with nano- and micron-scale dimensions and is evenly dispersed within the Janus membrane, a large number of pore channels are formed in the diatomaceous earth-based Janus membrane. The presence of these pores ensures that the diatomaceous earth-based Janus membrane can achieve efficient screening and filtration in oil-water separation. It is particularly suitable for treating liquids with high viscosity and complex components, such as oily wastewater and oil-water emulsions. It also reduces membrane fouling and clogging problems that may occur during the separation process, thereby achieving more efficient and economical oil-water separation. The diatomaceous earth-based Janus membrane prepared by this invention has an efficiency of over 99% for both oil-water separation and oil-water emulsion separation.

[0032] 3. Since diatomaceous earth itself has excellent chemical corrosion resistance, thermal stability and high temperature resistance, the present invention uses silane-modified diatomaceous earth as the base material, which not only enhances the structural stability of the diatomaceous earth-based Janus membrane in terms of microstructure, but also significantly improves the overall physical properties of the diatomaceous earth-based Janus membrane, enabling the diatomaceous earth-based Janus membrane to effectively cope with complex separation tasks in the long term. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a characterization graph of the water contact angle of the hydrophilic side of the diatomaceous earth / polysulfone composite Janus membrane prepared in Example 1;

[0034] Figure 2 This is a water contact angle characterization diagram of the hydrophobic side of the diatomaceous earth / polysulfone composite Janus membrane prepared in Example 1;

[0035] Figure 3 This is a schematic diagram of an oil-water separation device;

[0036] Figure 4 This is a characterization diagram of the underwater chloroform contact angle of the hydrophilic side of the diatomaceous earth / polysulfone composite Janus membrane prepared in Example 1. DETAILED DESCRIPTION

[0037] In order to make the technical solutions of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the specification of the present application. It should be noted that the following embodiments are only used to better understand the technical solutions of the present application, and should not be understood as a limitation of the present application.

[0038] Example 1.

[0039] S1: 50 g of diatomite with a particle size of 20 μm, 500 g of toluene, 0.5 g of triethylamine and 5 g of 3-mercaptopropylmethyldimethoxysilane were weighed into a reactor, and reacted at 60°C for 6 h. After the reaction was completed, the reaction solution was filtered, washed with ethanol and then filtered again, and then dried at 60°C to obtain 51.8 g of silane-modified diatomite;

[0040] S2: 50 g of polysulfone, 0.2 g of Span 80, 2 g of polyvinylpyrrolidone and 400 g of DMF were weighed into a reactor, stirred and dissolved, and then 5 g of the silane-modified diatomite prepared in S1 was added, and mechanically stirred at 60°C for 2 h at a stirring speed of 200 rpm to obtain a uniform diatomite / polymer solution. 10 g of the diatomite / polymer solution was weighed and coated on a coating machine to form a thin film with a thickness of 100 μm. The thin film was immersed in water and left to stand for 10 min, and then dried at 50°C to obtain a diatomite / polysulfone composite film with a thickness of 96 μm;

[0041] S3: Hydrogen peroxide was added to a fumigation device, and the temperature was raised to 80°C to vaporize it. The diatomite / polymer composite film was subjected to hydrogen peroxide vapor fumigation treatment for 10 min on one side to convert part or all of the mercapto groups on the surface to sulfonic acid groups, thereby preparing a diatomite / polysulfone composite Janus film. The side subjected to the hydrogen peroxide vapor fumigation treatment is the hydrophilic side, and the other side is the hydrophobic side. Figure 1 is a water contact angle characterization diagram of the hydrophilic side of the diatomite / polysulfone composite Janus film, and the contact angle of the hydrophilic side is 52°; Figure 2 is a water contact angle characterization diagram of the hydrophobic side of the diatomite / polysulfone composite Janus film, and the contact angle of the hydrophobic side is 126°.

[0042] Example 2.

[0043] S1: 50 g of diatomite with a particle size of 20 μm, 500 g of toluene, 0.5 g of triethylamine and 5 g of 3-mercaptopropylmethyldimethoxysilane were weighed into a reactor, and reacted at 60°C for 6 h. After the reaction was completed, the reaction solution was filtered, washed with ethanol and then filtered again, and then dried at 60°C to obtain 51.8 g of silane-modified diatomite;

[0044] S2: 40 g of PLA, 10 g of PBAT, 2 g of polyethylene glycol 400, and 400 g of chloroform were weighed and added to the reactor, stirred and dissolved, and 10 g of silane-modified diatomaceous earth prepared in S1 was added. The mixture was mechanically stirred at 60°C for 2 h at a stirring speed of 200 rpm to obtain a uniform diatomaceous earth / polymer solution. 10 g of the diatomaceous earth / polymer solution was weighed and applied by knife coating on a coater to form a film with a thickness of 100 μm. The film was immersed in an ethanol-chloroform mixture with a mass ratio of ethanol to chloroform of 8:2 and allowed to stand for 10 min. The film was then dried at 50°C to obtain a diatomaceous earth / PLA / PBAT composite film with a thickness of 96 μm.

[0045] S3: Hydrogen peroxide was added to a fumigation device and heated to 80°C to vaporize it. One side of the diatomaceous earth / polymer composite membrane was subjected to hydrogen peroxide vapor fumigation for 10 minutes, partially or completely converting the thiol groups on its surface into sulfonic acid groups. This produced a diatomaceous earth / PLA / PBAT composite Janus membrane. The hydrophilic side treated with hydrogen peroxide vapor exhibited a contact angle of 40°; the hydrophobic side exhibited a contact angle of 131°.

[0046] Example 3.

[0047] S1: 50 g of 40 μm diatomaceous earth, 500 g of toluene, 0.5 g of triethylamine, and 20 g of 3-mercaptopropylmethyldimethoxysilane were weighed and added to a reactor. The mixture was reacted at 60° C. for 6 h. After the reaction, the reaction solution was filtered, washed with ethanol, filtered again, and then dried at 60° C. to obtain 51.8 g of silane-modified diatomaceous earth.

[0048] S2: Weigh 50g of nylon elastomer ( 4012), 0.2g Span 80, 2g polyvinyl pyrrolidone and 400g chloroform were added to the reactor and stirred to dissolve, and 20g of silane-modified diatomaceous earth prepared by S1 was added, and mechanical stirring was carried out at 60°C for 2h at a stirring speed of 200rpm to obtain a uniform diatomaceous earth / polymer solution; 10g of the diatomaceous earth / polymer solution was weighed and coated on a coater to form a film with a thickness of 100μm, and the film was immersed in an ethanol-chloroform mixture and allowed to stand for 10min, wherein the mass ratio of ethanol to chloroform was 8:2, and then dried at 50°C to obtain a diatomaceous earth / nylon elastomer composite film with a thickness of 96μm;

[0049] S3: Hydrogen peroxide was added into the fumigation device, and the temperature was raised to 80°C to make it vaporize. One side of the diatomite / polymer composite film was treated with hydrogen peroxide vapor for 10 min, so that the sulfhydryl group on the surface of the diatomite / polymer composite film was partially or completely converted into sulfonic acid group, thereby obtaining a diatomite / nylon elastomer composite Janus film. The side treated with hydrogen peroxide vapor was the hydrophilic side, and the contact angle thereof was 38°; the other side was the hydrophobic side, and the contact angle thereof was 136°.

[0050] Example 4.

[0051] S1: 50 g of diatomite with a particle size of 20 μm, 500 g of toluene, 0.5 g of triethylamine and 25 g of 3-mercapto propyl methyl dimethoxy silane were weighed into a reactor, and reacted at 60°C for 6 h. After the reaction was completed, the reaction solution was filtered, washed with ethanol and then filtered again, and then dried at 60°C to obtain 51.8 g of silane-modified diatomite;

[0052] S2: 50 g of polyurethane elastomer (2392ARE), 0.3 g of Tween 60, 5 g of polyethylene glycol 200 and 400 g of chloroform were weighed into a reactor, stirred and dissolved, and then 20 g of the silane-modified diatomite prepared in S1 was added, and mechanically stirred at 60°C for 2 h at a stirring speed of 200 rpm to obtain a uniform diatomite / polymer solution; 10 g of the diatomite / polymer solution was coated on a coating machine by blade coating to form a thin film with a thickness of 100 μm, the thin film was immersed in an ethanol-chloroform mixture for 10 min, and then dried at 50°C, wherein the mass ratio of ethanol to chloroform was 8:2, to obtain a diatomite / polyurethane elastomer composite film with a thickness of 96 μm;

[0053] S3: Hydrogen peroxide was added into the fumigation device, and the temperature was raised to 80°C to make it vaporize. One side of the diatomite / polymer composite film was treated with hydrogen peroxide vapor for 30 min, so that the sulfhydryl group on the surface of the diatomite / polymer composite film was partially or completely converted into sulfonic acid group, thereby obtaining a diatomite / polyurethane elastomer composite Janus film. The side treated with hydrogen peroxide vapor was the hydrophilic side, and the contact angle thereof was 21°; the other side was the hydrophobic side, and the contact angle thereof was 140°. The following table is the water contact angle of the Janus films prepared in Examples 1-4:

[0054] hydrophilic side contact angle hydrophobic side contact angle Example 1 52° 126° Example 2 40° 131° Example 3 38° 136° Example 4 21° 140°

[0055] Oil-water separation test:

[0056] (1) The diatomite / poly sulfone composite Janus film prepared in Example 1 was placed in a beaker containing 100 mL of water, and the water level was marked. After 10 min, the water level was found to be 98 mL, indicating that the diatomite / poly sulfone composite Janus film had a water absorption rate of 2% (2 mL / 100 mL). Figure 3White oil and deionized water were mixed into an oil-water mixture with a volume ratio of 20:80 between the two glass containers in the separation device, and the oil-water separation was performed using the hydrophilic side of the Janus membrane. The separation efficiency was calculated by chromatographic analysis. The experimental results showed that the separation efficiency of the oil-water mixture was 99.92%.

[0057] The separation efficiency in the oil-water separation test can be calculated according to the formula (1) shown in the formula (1);

[0058] The separation efficiency (%) = (1-Cp / C0) x 100% (1);

[0059] Wherein, C0(mg / mL) is the oil content before separation; Cp(mg / mL) is the oil content in the filtrate after separation.

[0060] (2) Add 3.8% of the total weight of the mixed surfactant of Tween 20 and Tween 80 to the mixture system of white oil and deionized water with a volume ratio of 10:90, and emulsify to prepare an oil-in-water emulsion. The diatomite / poly sulfone composite Janus membrane prepared in Example 1 is placed between the two glass containers in the separation device as shown in Figure 3 The oil-water emulsion is poured into the device as shown in Figure 3 The oil-water emulsion is poured into the device as shown in

[0061] (3) The diatomite / poly sulfone composite Janus membrane prepared in Example 1 is placed between the two glass containers in the separation device as shown in Figure 3 The oil-water mixture is poured into the device as shown in Figure 3 The oil-water mixture is poured into the device as shown in Figure 4 The contact angle of the diatomite / poly sulfone composite Janus membrane hydrophilic side under water chloroform is shown in the figure, and the contact angle is 153°.

[0062] (4) Add 3.8% of the total weight of the mixed surfactant of Span 20 and Span 80 to the mixture system of chloroform and deionized water with a volume ratio of 90:10, and emulsify to prepare an oil-in-water emulsion. The diatomite / poly sulfone composite Janus membrane prepared in Example 1 is placed between the two glass containers in the separation device as shown in Figure 3 The oil-in-water emulsion is poured into the device as shown in Figure 3The Janus membrane is used in the device to separate oil-water emulsion, and the separation efficiency is calculated by chromatographic analysis.

[0063] In conclusion, the silane modified diatomite is compounded with polymer to prepare a polymer / diatomite composite membrane, and further through oxidation reaction, the hydrophobic sulfhydryl on one side of the diatomite / polymer composite membrane is converted into hydrophilic sulfonic acid group, so that the polymer / diatomite composite membrane is changed from two sides hydrophobic into one side hydrophobic and the other side hydrophilic two sides asymmetric wetting diatomite-based Janus membrane. The porous structure of the nanoscale and microscale size of the silane modified diatomite enables a large number of pore channels to be formed in the diatomite-based Janus membrane, and further ensures that the diatomite-based Janus membrane realizes efficient screening and filtering effect in oil-water separation, so as to realize more efficient and economical oil-water separation.

[0064] It can be understood that the present application is described by some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to the features and embodiments without departing from the spirit and scope of the present application. In addition, under the guidance of the present application, the features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are within the scope of the present application.

Claims

1. A method for preparing a diatomite-based Janus membrane, characterized in that, The method comprises the following steps: S1: weigh diatomite, organic solvent, catalyst, silane coupling agent, and add them into a reactor for reaction; after the reaction, the reaction solution is filtered, washed, and filtered again to obtain silane-modified diatomite; S2: weigh polymer, surfactant, dispersant, and solvent, and add them into a reactor to form a uniform polymer solution by stirring; continue to add the silane-modified diatomite prepared in S1 to obtain a uniform diatomite / polymer solution; the diatomite / polymer solution is coated into a thin film on a coating machine, and the thin film is immersed in a precipitant and left to stand; after drying, a diatomite / polymer composite film is obtained; S3: one side of the diatomite / polymer composite film prepared in S2 is subjected to oxidant vapor fumigation treatment to obtain a diatomite / polymer Janus film; The organic solvent is one or a combination of at least two of toluene, xylene, cyclohexane, and cyclohexanone; The catalyst is one or a combination of at least two of N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, N,N,N',N'-tetramethylalkylene diamine, triethylamine, and N,N-dimethylbenzylamine; The silane coupling agent is one or a combination of at least two of 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane; The polymer is one or a combination of at least two of polylactic acid, polybutylene adipate / terephthalate Diester , polyester elastomer, nylon, nylon elastomer, ethylene-vinyl acetate copolymer, polyurethane elastomer, polysulfone, polyethersulfone, and polyacrylonitrile. The surfactant is one or a combination of at least two of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, polysorbate, and sorbitan fatty acid ester; The dispersant is one or a combination of at least two of polyethylene glycol, polyvinylpyrrolidone, and polyvinyl alcohol; The solvent is one or a combination of at least two of chloroform, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, and hexafluoroisopropanol; The precipitant is any one of water, ethanol, a water-dimethylformamide mixture, a water-dimethyl sulfoxide mixture, an ethanol-tetrahydrofuran mixture, and an ethanol-chloroform mixture; The oxidant is one or a combination of at least two of hydrogen peroxide and peroxyacetic acid.

2. The method of claim 1, wherein the diatomaceous earth-based Janus membrane is prepared by the steps of: The diatomite-based Janus film has a thickness of 5-500 μm.

3. The method of claim 1, wherein the diatomaceous earth-based Janus membrane is prepared by the steps of: The reaction temperature in S1 is 60°C, and the reaction time is 6 h.

4. The method of claim 1, wherein the diatomaceous earth-based Janus membrane is prepared by the steps of: The drying temperature in S2 is 50°C.

5. The method of claim 1, wherein the diatomaceous earth-based Janus membrane is prepared by the steps of: The heating temperature in S3 is 80°C.

6. The method of claim 1, wherein the diatomaceous earth-based Janus membrane is prepared by the steps of: The diatomite has a particle size of 5-50 μm, and a specific surface area of 30 m 2 g -1 .

7. The method of claim 1, wherein the diatomaceous earth-based Janus membrane is prepared by the steps of: The mass ratio of diatomite to silane coupling agent is 1-20:

1.

8. The method of claim 1, wherein the diatomaceous earth-based Janus membrane is prepared by the steps of: The mass ratio of polymer, surfactant, dispersant, and diatomite is 1-20:0.05-0.5:0.01-1:

1.

9. A diatomite-based Janus membrane, characterized in that, Prepared by the preparation method in any one of claims 1-8.

10. Use of the diatomaceous earth-based Janus membrane according to claim 9, characterized in that, Applied to oil-water separation.

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