Hydrophobic and lipophilic modified sponge, preparation method and application thereof in oil-water separation
By in-situ polymerization of covalent organic polymers on the surface of porous sponges to form hydrophobic and oleophilic modified sponges, the problems of environmental pollution and insufficient durability in existing technologies are solved, and efficient oil-water separation is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANCHANG UNIV
- Filing Date
- 2024-10-12
- Publication Date
- 2026-05-19
AI Technical Summary
Among existing oil-water separation technologies, superhydrophobic modified wood sponges pose environmental pollution risks and have insufficient oil absorption capacity and durability, while the oil-water separation performance of magnetic fly ash@PDMS sponge materials is difficult to sustain.
A hydrophobic and oleophilic modified sponge is formed by in-situ polymerization of covalent organic polymers on the surface of porous sponge. By growing covalent organic polymers on the surface of the porous sponge skeleton, a rough structure is formed, which improves hydrophobicity and acid and alkali resistance, and avoids the use of fluorine.
It improves the oil absorption capacity and property stability of porous sponges, achieves efficient oil-water separation, and maintains good separation performance in complex environments.
Smart Images
Figure CN119240857B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oil-water separation technology, and in particular to a hydrophobic and oleophilic modified sponge, its preparation method, and its application in oil-water separation. Background Technology
[0002] With the rapid development of industry, the discharge of oily wastewater is constantly increasing, and the frequent oil spills during oil extraction and transportation have a very serious impact on the ecological environment. In addition, oil-water mixtures do not only include clearly stratified oil-water mixtures, but sometimes also oil-water emulsions and a small amount of oil dissolved in water. For example, in the rare earth extraction and separation process, the increased hydrophilicity of the organic phase after saponification, as well as the entrainment of extractants and diluents and incomplete phase separation, can lead to the presence of oil pollutants in rare earth raffinate and back-extraction liquid, affecting the subsequent compliance with emission standards and the quality of rare earth products.
[0003] Chinese invention patent CN116619504A discloses a method for preparing a superhydrophobic modified wood sponge for long-term oil-water separation. This method involves treating the surface of the wood sponge with a fluorosilane / pyrrole solution followed by a ferric chloride solution to grow superhydrophobic polypyrrole nanomaterials. However, the addition of fluorine-containing substances has a significant environmental impact. Chinese invention patent CN113332965A discloses a magnetic fly ash@PDMS sponge material for oil-water separation. However, this material can only adsorb six times its own weight in cyclohexane during oil-water separation, resulting in unsustainable oil-water separation performance and poor durability. Therefore, there is an urgent need to provide a solution to improve these problems. Summary of the Invention
[0004] The purpose of this invention is to provide a hydrophobic and oleophilic modified sponge, its preparation method, and its application in oil-water separation. This invention utilizes a covalent organic polymer with acid and alkali resistance and low density to grow on the surface of a porous sponge, thereby obtaining a modified sponge material with hydrophobic and oleophilic properties. This method does not require the introduction of fluorine or other polluting elements, and can greatly improve the oil absorption capacity of the porous sponge itself, as well as its durability and property stability during oil-water separation.
[0005] In a first aspect, the present invention provides a hydrophobic and oleophilic modified sponge, comprising a porous sponge and a covalent organic polymer polymerized in situ on the skeletal surface of the porous sponge, wherein the loading of the covalent organic polymer on the modified sponge is 10-15%; wherein the covalent organic polymer comprises pyromellitic trimethylolpropane and 4,4'-diaminodiphenylmethane copolymerized.
[0006] The hydrophobic and oleophilic modified sponge provided by this invention forms a covalent organic polymer (COF) through in-situ polymerization on the surface of a porous sponge. This reduces the surface hydrophilicity, while the in-situ polymerization of COF on the porous sponge surface enhances the bonding strength between the two. Furthermore, the microscopically rough structure of the COF surface increases the contact angle between the material surface and water, thereby improving hydrophobicity. In addition, COF exhibits good acid and alkali resistance and low density, which improves the stability and durability of the modified sponge during use.
[0007] Optionally, the porous sponge includes at least one of melamine sponge, polyurethane sponge, cellulose sponge, and silicone sponge.
[0008] Secondly, the present invention also provides a method for preparing a hydrophobic and oleophilic modified sponge, comprising: impregnating and modifying a porous sponge in a copolymerization solution, and then separating and drying it to obtain a modified sponge; wherein the solute in the copolymerization solution includes pyromellitic methyl ether and 4,4'-diaminodiphenylmethane.
[0009] Optionally, when the porous sponge is modified by impregnation in a copolymerization solution, the pyromellitic methyl ether and the 4,4'-diaminodiphenylmethane undergo in-situ polymerization growth on the surface of the porous sponge under the catalysis of a catalyst.
[0010] Optionally, the porous sponge includes at least one of melamine sponge, polyurethane sponge, cellulose sponge, and silicone sponge.
[0011] Optionally, the molar ratio of the pyromellitic methyl ether to the 4,4'-diaminodiphenylmethane is 1:(1-2).
[0012] Optionally, the catalyst includes at least one of acetic acid, formic acid, and benzenesulfonic acid.
[0013] Optionally, the molar concentration of the catalyst in the copolymerization solution is 3-6 mol / L.
[0014] Optionally, the solvent in the copolymerization solution includes at least one of 1,4-dioxane and mesitylene.
[0015] Optionally, at 110-130°C and under catalyst catalysis, the pyromellitic trimethylolpropane and the 4,4'-diaminodiphenylmethane are polymerized and grown in situ on the surface of a porous sponge.
[0016] Optionally, the modified sponge is obtained by washing after separation and drying in a vacuum environment at 50-70℃.
[0017] Optionally, before immersing the porous sponge in the copolymerization solution for modification, the porous sponge is pre-immersed and cleaned with an ethanol solution and deionized water and then dried.
[0018] Thirdly, the present invention also provides an application of hydrophobic and oleophilic modified sponge in oil-water separation.
[0019] Optionally, the hydrophobic and oleophilic modified sponge can be immersed in the oil-water mixture to be separated for adsorption separation.
[0020] Optionally, the oil-water mixture to be separated includes one of the following: a mixture of organic solvent and water, a mixture of oil and water, rare earth raffinate, and rare earth back-extraction solution. Attached Figure Description
[0021] Figure 1 Here is a SEM image of the modified sponge prepared in Example 1 of this invention;
[0022] Figure 2 The FT-IR spectrum of the modified sponge prepared in Example 1 of this invention;
[0023] Figure 3 The diagram shows the state changes of the modified sponge prepared in Example 1 of this invention during oil-water separation of an organic solvent and water mixture.
[0024] Figure 4 The image shows the changes in oil droplets before and after the modified sponge prepared in Example 1 of this invention was used for oil-water separation of a kerosene emulsion in water.
[0025] Figure 5 The image shows the changes in oil droplets before and after the modified sponge prepared in Example 1 of this invention was used for oil-water separation of kerosene-in-water emulsion.
[0026] Figure 6 The modified sponge prepared in Example 1 of this invention is used in mixed organic phases (P) with saponification degrees of 0%, 30%, and 50%. 507 -Diagram showing the changes in oil droplets before and after the separation of an emulsion of kerosene and water;
[0027] Figure 7 This is a characterization diagram of the surface hydrophobicity of the modified sponge prepared in Example 1 of the present invention.
[0028] Figure 8 The modified sponge prepared in Example 1 of this invention is characterized by its surface hydrophobicity after being treated in acid, alkali and salt environments for 3 days. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.
[0030] This invention provides a hydrophobic and oleophilic modified sponge, comprising a porous sponge and a covalent organic polymer polymerized in situ on the skeletal surface of the porous sponge. In fact, porous sponges possess high porosity and both hydrophobic and oleophilic properties; however, after polymerizing the covalent organic polymer on the skeletal surface of the porous sponge, the surface roughness of the porous sponge skeleton can be greatly increased, thereby enhancing hydrophobicity while retaining oleophilicity.
[0031] In fact, the loading of modified sponge on porous sponge is 10-15%, which can be uniformly dispersed on the surface of the porous sponge skeleton, thereby improving the hydrophobicity of the porous sponge.
[0032] Specifically, the covalent organic polymer includes trimesin and 4,4'-diaminodiphenylmethane copolymerized. In fact, by copolymerizing trimesin and 4,4'-diaminodiphenylmethane on the surface of the porous sponge's framework, in-situ polymerization can be effectively utilized using the active groups present in the porous sponge itself. This effectively improves the bonding strength of the covalent organic polymer on the porous sponge and prevents the covalent organic polymer from detaching during the compression process of the modified sponge.
[0033] In some embodiments, the porous sponge in the modified sponge serves as the elastic matrix, and at least one of melamine sponge, polyurethane sponge, cellulose sponge, and silicone sponge can be selected. In practice, the porous sponge is chosen from sponge materials with hydrophilic and oleophilic properties. Furthermore, commercially available conventional products can be used to facilitate the selection of raw materials and reduce reaction costs.
[0034] This invention also provides a method for preparing a hydrophobic and oleophilic modified sponge, comprising: impregnating a porous sponge in a copolymer solution for modification, followed by separation and drying to obtain the modified sponge. In fact, by impregnating the porous sponge in the copolymer solution, the sponge's water-absorbing properties allow it to absorb the copolymer solution into its interior, thereby facilitating the uniform formation of the covalent organic polymer within the copolymer solution on the surface of the porous sponge's framework.
[0035] In fact, the solutes in the copolymerization solution include pyromellitic methyl ether and 4,4'-diaminodiphenylmethane. When the porous sponge is impregnated in the copolymerization solution, pyromellitic methyl ether and 4,4'-diaminodiphenylmethane undergo a condensation reaction on the surface of the porous sponge. The aldehyde group in pyromellitic methyl ether condenses with the amino group in 4,4'-diaminodiphenylmethane to form an imine bond, thereby forming a stable covalent organic polymer on the surface of the porous sponge's framework.
[0036] In some embodiments, when the porous sponge is immersed in the copolymerization solution, pyromellitic methyl ether and 4,4'-diaminodiphenylmethane undergo in-situ polymerization on the surface of the porous sponge under the catalysis of a catalyst. In fact, adding a catalyst can effectively promote the copolymerization reaction, thereby facilitating the formation of covalent organic polymers on the surface of the porous sponge. Specifically, the catalyst can be at least one of acetic acid, formic acid, and benzenesulfonic acid.
[0037] In some embodiments, the molar ratio of pyromellitic methyl ether to 4,4'-diaminodiphenylmethane in the copolymerization solution is 1:(1-2), effectively placing an excess of 4,4'-diaminodiphenylmethane, which is beneficial for the in-situ copolymerization of the covalent organic polymer on the porous sponge surface. Furthermore, the molar concentration of the catalyst in the copolymerization solution is 3-6 mol / L, which is beneficial for catalyzing the copolymerization reaction, and the solvent in the copolymerization solution includes at least one of 1,4-dioxane and mesitylene.
[0038] In some embodiments, a porous solution is immersed in a copolymerization solution, and pyromellitic methyl ether and 4,4'-diaminodiphenylmethane undergo in-situ polymerization on the surface of a porous sponge at 110-130°C under the catalysis of a catalyst. In fact, conducting the reaction at 110-130°C promotes the formation of covalent organic polymers while reducing the generation of byproducts.
[0039] In some embodiments, before immersing the porous sponge in the copolymerization solution for modification, the porous sponge is pre-washed with ethanol solution and deionized water and then dried. This helps to improve the cleanliness of the porous sponge and the number of active sites on the surface of the porous sponge skeleton. Furthermore, after the porous sponge is immersed and modified, it is separated and cyclically washed with N,N-dimethylformamide and acetone, and then dried in a vacuum environment at 50-70°C to obtain the modified sponge.
[0040] This invention also provides an application of any of the above-mentioned modified sponges in oil-water separation. By immersing the modified sponge in the oil-water mixture to be separated and bringing it into contact with the oil phase, the oil phase in the mixture can be adsorbed, thereby separating the oil phase components from the water phase components. Specifically, the oil-water mixture to be separated includes one of the following: a mixture of organic solvent and water, a mixture of oil and water, rare earth raffinate, and rare earth back-extraction solution.
[0041] Example 1
[0042] This embodiment 1 provides a method for preparing a hydrophobic and oleophilic modified sponge, including the following steps:
[0043] S1. Soak a melamine sponge with a specification of 1cm×1cm×1cm in an ethanol solution and ultrasonically clean it. After three cycles, take out the melamine sponge, rinse it three times with deionized water, and then transfer it to a 60℃ oven to dry to constant weight.
[0044] S2. 32.4 mg (0.2 mmol) of 1,3,5-benzenetriformaldehyde (TFB) and 39.6 mg (0.2 mmol) of 4,4'-diaminodiphenylmethane (MDA) were added to 15 mL of 1,4-dioxane and ultrasonically mixed and dissolved to obtain a copolymer solution.
[0045] S3. After cleaning and drying, the melamine sponge was immersed in the copolymerization solution and ultrasonically mixed for 10 min. Then, 2 mL of acetic acid was added as a catalyst, and the reaction was carried out at 120 °C for 24 h. The sponge was then removed and washed three times with N,N-dimethylformamide and acetone. After drying in a vacuum drying oven at 60 °C for 12 h and maintaining constant weight, the hydrophobic and oleophilic modified sponge (TFB-MDA@MS) was obtained. The loading of the covalent organic polymer formed by the copolymerization of 1,3,5-benzenetriformaldehyde and 4,4'-diaminodiphenylmethane on the modified sponge was calculated to be 13.33%.
[0046] Performance testing
[0047] The TFB-MDA@MS prepared in Example 1 was characterized by SEM as follows: Figure 1 As shown, chemical bond analysis was performed using FT-IR spectroscopy, and the FT-IR spectrum is shown below. Figure 2 As shown. From Figure 2 As can be seen from both MS and TFB-MDA@MS, the range is 3400-3200cm. -1 The presence of a relatively broad stretching vibration peak is due to the stretching vibration of the secondary amine (NH), while TFB-MDA@MS and TFB-MDA show a peak at 1620 cm⁻¹. -1 The presence of a vibrational stretching peak at the point indicates the successful polymerization of TFB-MDA on melamine sponge, which is attributed to the C=N reaction that occurs during the Schiff base reaction.
[0048] Detection Example 1
[0049] The modified sponge (TFB-MDA@MS) prepared in Example 1 was subjected to oil-water separation of an organic solvent and water mixture, including the following steps:
[0050] J1. After adding 5 mL of chloroform to Sudan III for staining, it is mixed with 100 mL of deionized water. The chloroform settles to the bottom of the mixture, thus obtaining the oil-water mixture to be separated.
[0051] J2. The modified sponge is immersed in the oil-water mixture to be separated. When the modified sponge is in the aqueous phase, a silver mirror phenomenon is formed on its surface. When the modified sponge comes into contact with chloroform, it rapidly absorbs the chloroform.
[0052] J3. After the modified sponge that has absorbed chloroform is removed from the liquid surface, the chloroform does not drip, thus obtaining clean deionized water free of chloroform, achieving oil-water separation of the organic solvent and water mixture.
[0053] In fact, during oil-water separation in test example 1, if Figure 3 As shown, from Figure 3 It is evident that when the modified sponge comes into contact with chloroform, it can rapidly absorb the chloroform, causing the red chloroform to spread quickly into the modified sponge, and there is no dripping after adsorption.
[0054] Detection Example 2
[0055] The modified sponge (TFB-MDA@MS) prepared in Example 1 was subjected to adsorption performance stability tests, including: saturated adsorption-extrusion cycle adsorption tests were conducted on the modified sponge for chloroform and kerosene, and the saturated adsorption capacity of the modified sponge at the 1st, 5th, 10th, 15th, 20th, 25th, 30th, and 35th cycles was calculated, as well as the retention rate of saturated adsorption at the 5th, 10th, 15th, 20th, 25th, 30th, and 35th cycles compared to the 1st cycle. The results are shown in Table 1 below.
[0056] Table 1. Stability Test of Adsorption Performance of Modified Sponge
[0057]
[0058] As can be seen from Table 1, the modified sponge prepared by the present invention has good performance stability during oil phase component adsorption and extrusion desorption, and the COF structure on the surface of the modified sponge has good elasticity and stability.
[0059] Detection Example 3
[0060] The modified sponge (TFB-MDA@MS) prepared in Example 1 was subjected to oil-water separation of a kerosene emulsion, including the following steps:
[0061] J1. Kerosene and deionized water were ultrasonically mixed at a volume ratio of 1:10 for 1 hour to obtain a milky white kerosene-in-water emulsion.
[0062] J2. The modified sponge is immersed in a water-in-kerosene emulsion and shaken. After adsorption and separation, a transparent aqueous solution is obtained.
[0063] This demonstrates that the modified sponge prepared in Example 1 has a good separation effect on water-in-kerosene emulsions, and the changes in the emulsion before separation and the transparent aqueous solution after separation were observed using an optical microscope. Figure 4 As shown, from Figure 4 During the separation process, distinct organic phase droplets were observed within the emulsion at a size of 100 μm, but these droplets were no longer observable at the same scale after separation. Furthermore, by measuring the kerosene content before and after separation using a UV spectrophotometer, the separation efficiency of the modified sponge for kerosene was calculated to be 98.35%.
[0064] Detection Example 4
[0065] The modified sponge (TFB-MDA@MS) prepared in Example 1 was subjected to oil-water separation of a water-in-kerosene emulsion, including the following steps:
[0066] J1. Kerosene and deionized water were ultrasonically mixed at a volume ratio of 10:1 for 1 hour to obtain a milky white kerosene-in-water emulsion.
[0067] J2. The modified sponge is immersed in a kerosene-in-water emulsion and shaken. After adsorption and separation, a transparent aqueous solution is obtained.
[0068] This demonstrates that the modified sponge prepared in Example 1 has a good separation effect on kerosene-in-water emulsions, and the changes in the emulsion before separation and the transparent aqueous solution after separation were observed using an optical microscope. Figure 5 As shown, from Figure 5 During the separation process, distinct organic phase droplets were observed within the emulsion at a size of 100 μm, but these droplets were no longer observable at the same scale after separation. Furthermore, by measuring the kerosene content before and after separation using a UV spectrophotometer, the separation efficiency of the modified sponge for kerosene was calculated to be 99.08%.
[0069] Case 5
[0070] The modified sponge (TFB-MDA@MS) prepared in Example 1 was used in mixed organic phases (P) with saponification degrees of 0%, 30%, and 50%. 507 The separation of an emulsion of kerosene and water includes the following steps:
[0071] J1, P 507 A mixture with kerosene at a volume ratio of 1:1 was prepared to obtain a mixture with a saponification degree of 0%. The mixture was then ultrasonically mixed with water at a volume ratio of 1:10 for 1 hour to obtain an emulsion with a saponification degree of 0%.
[0072] J2. A sodium hydroxide solution with a concentration of 0.01 mol / L was added dropwise to a mixture with a saponification degree of 0%. After shaking at a constant temperature of 25°C for 30 min, the mixture was allowed to stand and the organic phase was separated to obtain an organic phase with a saponification degree of 30%. The organic phase was then ultrasonically treated with water at a volume ratio of 1:10 for 1 h to obtain an emulsion with a saponification degree of 30%.
[0073] J3. Add 0.01 mol / L sodium hydroxide solution dropwise to the mixture with a saponification degree of 0%. After shaking at 25°C for 30 min, let it stand to separate the layers and take the organic phase to obtain an organic phase with a saponification degree of 50%. Then, sonicate the organic phase and water at a volume ratio of 1:10 for 1 h to obtain an emulsion with a saponification degree of 50%.
[0074] J4. The modified sponge was immersed in emulsions with a saponification degree of 0%, 30%, and 50%, respectively, and a transparent aqueous solution was obtained after shaking adsorption separation.
[0075] Before separation, oil droplets in emulsions with 0% saponification, 30% saponification, and 50% saponification were observed using an optical microscope at a scale of 100 μm. Figure 6 As shown in (a1), (b1), and (c1), and after separation, the oil droplets in the emulsion were observed under an optical microscope at the same scale as shown in (a1), (b1), and (c1). Figure 4 As shown in (a2), (b2), and (c2).
[0076] from Figure 6 As can be seen, oil droplets are difficult to observe in the aqueous solution after separation. After separating emulsions with saponification degrees of 0%, 30%, and 50% by ultraviolet spectrophotometer, the separation efficiencies are 92.02%, 88.55%, and 84.05%, respectively.
[0077] Case 6
[0078] The modified sponge (TFB-MDA@MS) prepared in Example 1 was tested for acid resistance, alkali resistance, and salt resistance, including the following steps: The water contact angle of the modified sponge in its initial state was measured in advance, such as... Figure 7 As shown; the modified sponge was immersed in hydrochloric acid solution (pH=1), sodium hydroxide solution (pH=13), and 5wt.% sodium chloride aqueous solution for three days respectively. Afterwards, the modified sponge was removed, washed with ethanol, and dried. The changes in the water contact angle of the modified sponge after immersion in acidic, alkaline, and saline environments were measured. Figure 8 As shown.
[0079] from Figure 7 and Figure 8As can be seen from the results, the modified sponge prepared in Example 1 has a water contact angle of 147.7° in its initial state, which indicates that the modified sponge has good hydrophobicity. Furthermore, after being soaked in acidic, alkaline, and salt solutions, the water contact angle remains stable at over 140°, indicating that the modified sponge can maintain chemical stability in complex acid and alkaline environments and has good acid, alkali, and salt resistance.
[0080] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.
Claims
1. A method for preparing a hydrophobic and oleophilic modified sponge, characterized in that, include: The modified sponge was obtained by wetting and modifying the porous sponge in a copolymer solution containing pyromellitic methyl ether, 4,4'-diaminodiphenylmethane and a catalyst, followed by separation and drying. The modified sponge includes a porous sponge and a covalent organic polymer polymerized in situ on the skeletal surface of the porous sponge. The loading of the covalent organic polymer on the modified sponge is 10%-15%. The covalent organic polymer is grown in situ on the surface of the porous sponge by the in-situ polymerization of pyromellitic aldehyde and 4,4'-diaminodiphenylmethane under the catalysis of a catalyst.
2. The preparation method according to claim 1, characterized in that, The porous sponge includes at least one of melamine sponge, polyurethane sponge, cellulose sponge, and silicone sponge.
3. The preparation method according to claim 1, characterized in that, The porous sponge includes at least one of melamine sponge, polyurethane sponge, cellulose sponge, and silicone sponge.
4. The preparation method according to claim 1, characterized in that, The molar ratio of the pyromellitic methyl ether to the 4,4'-diaminodiphenylmethane is 1:(1-2).
5. The preparation method according to claim 1, characterized in that, The catalyst includes at least one of acetic acid, formic acid, and benzenesulfonic acid.
6. The preparation method according to claim 1, characterized in that, The molar concentration of the catalyst in the copolymerization solution is 3-6 mol / L.
7. The preparation method according to claim 1, characterized in that, The solvent in the copolymerization solution includes at least one of 1,4-dioxane and mesitylene.
8. The preparation method according to claim 1, characterized in that, At 110-130℃ and under catalyst catalysis, the pyromellitic trimethylolpropane and the 4,4'-diaminodiphenylmethane undergo in-situ polymerization growth on the surface of a porous sponge.
9. The preparation method according to claim 1, characterized in that, After separation, the product is washed and dried in a vacuum environment at 50-70℃ to obtain the modified sponge.
10. The preparation method according to claim 1, characterized in that, Before the porous sponge is impregnated and modified in the copolymerization solution, it is pre-washed and dried using ethanol solution and deionized water.
11. A hydrophobic and oleophilic modified sponge prepared by the preparation method according to any one of claims 1 to 10.
12. The application of a hydrophobic and oleophilic modified sponge prepared by any one of claims 1 to 10 in oil-water separation.
13. The application according to claim 12, characterized in that, A hydrophobic and oleophilic modified sponge is immersed in the oil-water mixture to be separated for adsorption separation; the oil-water mixture to be separated includes one of the following: a mixture of organic solvent and water, a mixture of oil and water, rare earth raffinate, and rare earth back-extraction solution.