Janus sponge with rapid oil-water separation capability and preparation method thereof
By designing a superhydrophobic outer layer and a superhydrophilic internal structure for Janus sponge, the problems of slow oil absorption rate and high cost of traditional oil-absorbing sponges are solved, achieving a fast, efficient, and environmentally friendly oil-water separation effect.
Patent Information
- Application Number
- CN202511819195.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-04
- Publication Date
- 2026-01-30
AI Technical Summary
Traditional oil-absorbing sponges have a slow oil absorption rate when dealing with high-viscosity oils, and the overall hydrophobic modification is costly and has potential negative environmental impacts.
A Janus sponge was designed with a superhydrophobic outer layer and a superhydrophilic inner structure. Asymmetric wettability was formed through local modification, and the strong capillary force of the superhydrophilic interior was used to drive the rapid absorption of oil.
It achieves rapid oil absorption, reduces costs and environmental impact, while maintaining high-efficiency oil-water separation, with an oil absorption rate increased by about 2 times and a separation efficiency of over 99%.
Smart Images
Figure CN121422936A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of functional materials, in particular to a Janus sponge with rapid oil-water separation capability and a preparation method thereof. BACKGROUND
[0002] With the development of industry and the increase of offshore crude oil exploitation activities, the discharge of oily wastewater and oil spill accidents occur frequently, which poses a serious threat to the ecological environment and human health. Therefore, it is crucial to develop materials and technologies with high efficient oil-water separation capability.
[0003] Porous sponge material is an important material with oil-water separation capability, such as polyurethane sponge and melamine sponge, which is widely used as the matrix of oil absorption material due to its high porosity, large specific surface area and excellent elasticity. Traditional oil absorption sponge is usually modified by overall hydrophobization to have superhydrophobic / superoleophilic properties, so as to selectively absorb oil. However, such overall hydrophobic sponge has the following inherent defects: (1) Limited oil absorption rate: for high viscosity oils (such as crude oil and heavy oil), the penetration and diffusion resistance of oil molecules in the hydrophobic porous network is large, resulting in slow oil absorption rate.
[0004] (2) Large consumption of modifying agent: in order to achieve overall hydrophobicity, the entire sponge body needs to be modified, which requires a large amount of low surface energy substances (such as silane and fluoride), resulting in high cost and potential negative impact on the environment.
[0005] In order to solve the above-mentioned inherent defects, the existing technology provides a Janus material, i.e. a material with different physical or chemical properties on both sides, which provides a new idea to solve the above-mentioned problems. If a Janus sponge with asymmetric wetting structure can be designed, it is expected to significantly improve the oil absorption efficiency while maintaining high selective adsorption. SUMMARY
[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a Janus sponge with rapid oil-water separation capability and a preparation method thereof, which can solve the problems described in the background art.
[0007] The technical solution for achieving the purpose of the present application is: a Janus sponge with rapid oil-water separation capability, comprising a three-dimensional porous elastic matrix, the three-dimensional porous elastic matrix comprising a Janus structure, the internal network structure of the Janus structure forming superhydrophilicity, the outer layer of the Janus structure forming a superhydrophobic layer with a predetermined thickness, and the superhydrophobic layer being formed by modifying the surface layer of the three-dimensional porous elastic matrix with a low surface energy substance.
[0008] Further, the predetermined thickness is 1-5 mm.
[0009] Furthermore, the preset thickness is 1mm, 3mm, or 5mm.
[0010] Furthermore, the three-dimensional porous elastic matrix is any one of polyurethane sponge, melamine sponge, and cellulose sponge.
[0011] Furthermore, the low surface energy material is one or more of the following: long-chain alkylsilanes, fluoroalkylsilanes, stearic acid, and polydimethylsiloxane.
[0012] A method for preparing Janus sponge with rapid oil-water separation capability includes the following steps: Step 1: Select any one of polyurethane foam, melamine foam and cellulose foam as the three-dimensional porous elastic matrix, pre-treat the three-dimensional porous elastic matrix to obtain the pre-treated three-dimensional porous elastic matrix. Step 2: Construct an initial superhydrophobic layer on the outer layer of the pretreated three-dimensional porous elastic matrix; Step 3: Prepare a solution of a low surface energy substance; Step 4: Using a local immersion method or surface coating method, only the outer layer of the pretreated three-dimensional porous elastic matrix is brought into contact with the low surface energy solution. By controlling the immersion depth or coating thickness, it is ensured that only the area of the pretreated three-dimensional porous elastic matrix with a preset thickness is modified, thereby obtaining the final superhydrophobic layer and forming a superhydrophilic structure inside the pretreated three-dimensional porous elastic matrix.
[0013] Furthermore, in step 1, the pretreatment includes sequential ultrasonic cleaning and drying.
[0014] Furthermore, ultrasonic cleaning was performed using acetone, ethanol, and deionized water.
[0015] Furthermore, in step 3, the solvent of the solution is ethanol, n-hexane, or toluene.
[0016] The beneficial effects of this invention are as follows: This invention utilizes the asymmetric wettability of the anus structure to selectively repel water and capture oil, achieving rapid oil absorption, improving the oil absorption capacity of plastics, saving costs and maintaining environmental performance, and also improving oil-water separation efficiency. Attached Figure Description
[0017] Figure 1 This is a schematic flowchart of the preparation method of the present invention; Figure 2 The diagram shows the structure and oil absorption process of the Janus sponge of this invention: (a) integral superhydrophilic sponge; (b) integral superhydrophobic sponge; (c) Janus sponge; (d) Janus sponge oil absorption process. Figure 3 The wetting properties of the Janus sponge prepared for Example 1 are shown in (a) a cross-section of the Janus sponge, where the dark part is wetted by water and the light part is not wetted by water; and (b) the water droplet contact angle on the surface of the Janus sponge. Figure 4 The images show the effects of treating oil slicks on the water surface: (a) Janus sponge; (b) overall hydrophobic sponge. Figure 5 The bar charts show the time required for each example and comparative example to absorb 10 mL of oil: (a) absorption of high-viscosity crude oil (~200 mPa·s); (b) absorption of low-viscosity pump oil (~50 mPa·s). Detailed Implementation
[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: like Figures 1-5 As shown, a Janus sponge with rapid oil-water separation capability includes a three-dimensional porous elastic matrix. The three-dimensional porous elastic matrix includes a Janus structure. The internal network structure of the Janus structure forms superhydrophilicity, and the outer layer of the Janus structure forms a superhydrophobic layer of a predetermined thickness. The superhydrophobic layer is estimated to be formed by modifying the surface of the three-dimensional porous elastic matrix with a low surface energy material.
[0019] It is understood that the preset thickness is 1-5 mm, meaning that the outer layer of the Janus structure forms a superhydrophobic layer with a thickness of 1-5 mm. This preset thickness can be 1 mm, 3 mm, or 5 mm.
[0020] For example, the three-dimensional porous elastic matrix is any one of polyurethane foam, melamine foam, and cellulose foam.
[0021] For example, the low surface energy material is one or more of long-chain alkylsilanes, fluoroalkylsilanes, stearic acid, and polydimethylsiloxane.
[0022] This invention also provides a method for preparing Janus sponge with rapid oil-water separation capability, comprising the following steps: Step 1: Select any one of polyurethane foam, melamine foam and cellulose foam as the three-dimensional porous elastic matrix, pretreat the three-dimensional porous elastic matrix to obtain the pretreated three-dimensional porous elastic matrix.
[0023] The pretreatment process includes sequential ultrasonic cleaning and drying; that is, ultrasonic cleaning is followed by drying to obtain a pretreated three-dimensional porous elastic matrix. The purpose of ultrasonic cleaning is to remove surface impurities from the three-dimensional porous elastic matrix.
[0024] It is understandable that acetone, ethanol, and deionized water can be used for ultrasonic cleaning.
[0025] Step 2: Construct an initial superhydrophobic layer on the outer layer of the pretreated three-dimensional porous elastic matrix.
[0026] Step 3: Prepare a solution of a low surface energy substance, using ethanol, n-hexane, or toluene as the solvent.
[0027] Step 4: Using a local immersion or surface coating method, only the outer layer of the pretreated three-dimensional porous elastic matrix is brought into contact with the low surface energy solution. By precisely controlling the immersion depth or coating thickness, it is ensured that only a 1-5 mm thick area of the outer layer of the pretreated three-dimensional porous elastic matrix is modified. This results in the final superhydrophobic layer and the formation of a superhydrophilic structure within the pretreated three-dimensional porous elastic matrix.
[0028] Understandably, during the construction process, since the interior of the three-dimensional porous elastic matrix is not modified by low surface energy materials, the inherent hydrophilicity of the three-dimensional porous elastic matrix is preserved, thus forming a superhydrophilic structure inside.
[0029] The Janus sponge prepared by the above method can be used to treat marine oil spills, industrial oily wastewater, or domestic oil pollution.
[0030] This invention possesses a synergistic effect of asymmetric wettability: it utilizes the asymmetric wettability of the Janus structure. The superhydrophobic properties of the outer layer allow it to selectively "repel" water while "capturing" oil (oil can wet the superhydrophobic outer layer). Once the oil phase breaks through the superhydrophobic thin layer, it immediately enters the superhydrophilic internal network. Compared to the superhydrophobic outer layer, the internal superhydrophilic porous network structure has a larger surface energy, providing stronger capillary forces, thereby generating strong Laplace pressure as a driving force to rapidly "draw" the oil into the sponge's interior.
[0031] This invention also features a rapid oil absorption rate: compared to the overall hydrophobic sponge relying on the slow diffusion of the oil phase in the hydrophobic porous structure environment, this invention utilizes the strong capillary force generated by the internal superhydrophilic network to provide an additional and stronger driving force for the transport of oil (especially high viscosity oil), thereby achieving a significant improvement in the oil absorption rate.
[0032] This invention is cost-effective and environmentally friendly: by modifying only the outer 1-5mm thickness of the sponge with hydrophobicity, compared with overall modification, it can save 50%-90% of low surface energy modifiers, significantly reducing material costs and minimizing the environmental impact of chemical use.
[0033] This invention has the advantages of high selectivity and high oil-water separation efficiency: the superhydrophobic outer layer effectively blocks water molecules from entering, ensuring the material's excellent selective oil absorption capacity, and the separation efficiency can reach over 99%.
[0034] Example 1: Long-chain alkylsilane Janus sponge Janus sponge was prepared using the following steps: 1. Take a piece of commercial melamine sponge (2cm × 2cm × 2cm), ultrasonically clean it with acetone, ethanol and deionized water for 10 minutes each, and dry it at 60℃ for later use.
[0035] 2. Prepare a 1.0 wt% octadecyltrimethoxysilane (OTS) ethanol solution. Using a local immersion method, vertically immerse the melamine sponge into the OTS solution, controlling the immersion depth to 3 mm, and let it stand for 1 minute.
[0036] 3. Remove the melamine sponge and heat-treat it in an 80 ℃ oven for 2 hours to allow OTS to firmly cross-link onto the sponge skeleton, forming a superhydrophobic outer layer with a thickness of approximately 3 mm. The unmodified internal area retains its original hydrophilicity, ultimately yielding the Janus sponge.
[0037] The octadecyltrimethoxysilane Janus sponge prepared by this example has a superhydrophobic outer layer with a water droplet contact angle of 151° and an oil droplet contact angle of 0°, and a superhydrophilic inner layer with a water droplet and oil droplet contact angle of 0°.
[0038] Example 2: Janus stearate sponge Janus sponge was prepared using the following steps: 1. Take a piece of commercial polyurethane foam (2 cm × 2 cm × 2 cm) and clean and dry it as in Example 1.
[0039] 2. Prepare a 2.0 wt% mixed ethanol solution of methyltrimethoxysilane and stearic acid.
[0040] 3. Using the surface coating method, the above mixed ethanol solution is uniformly brushed onto all the outer surfaces of the polyurethane foam. By controlling the number of brushings and the concentration of the mixed ethanol solution, the thickness of the modified layer is made to be about 3 mm.
[0041] 4. Heat treatment at 100 ℃ for 1.5 hours yields Janus sponge with an outer superhydrophobic layer and an inner superhydrophilic layer.
[0042] The stearic acid Janus sponge prepared in Example 2 has a superhydrophobic outer layer with a water droplet contact angle of 153° and an oil droplet contact angle of 0°, and a superhydrophilic inner layer with a water droplet and oil droplet contact angle of 0°.
[0043] Example 3: Polydimethylsiloxane Janus sponge Janus sponge was prepared using the following steps: 1. Take a piece of commercial melamine sponge (2 cm × 2 cm × 2 cm) and clean and dry it as in Example 1.
[0044] 2. Prepare a toluene solution of cross-linked polydimethylsiloxane (PDMS, with a main agent to curing agent ratio of 10:1) with a concentration of 0.5 wt%.
[0045] 3. Using the local immersion method, the pretreated melamine sponge is vertically immersed in the toluene solution, with the immersion depth controlled at 2 mm, and left to stand for 1 minute.
[0046] 4. Heat treat at 80 ℃ for 3 hours to allow PDMS to fully crosslink and cure, forming a superhydrophobic outer layer with uniform thickness.
[0047] The octadecyltrimethoxysilane Janus sponge prepared in Example 3 has a superhydrophobic outer layer with a water droplet contact angle of 150° and an oil droplet contact angle of 0°, and a superhydrophilic inner layer with a water droplet and oil droplet contact angle of 0°.
[0048] Comparative Example 1: Original Superhydrophilic Sponge Take a raw melamine sponge of the same size and material as in Example 1 (without any hydrophobic modification). It is hydrophilic overall, and both its outer and inner layers are superhydrophilic. Its water droplet and oil droplet contact angles are both 0°.
[0049] Comparative Example 2: Overall Superhydrophobic Sponge Using the same melamine sponge and cross-linked PDMS solution as in Example 1, but instead of a complete immersion modification, the entire sponge was completely immersed in the cross-linked PDMS solution, then removed and heat-treated to prepare a monolithic superhydrophobic sponge. The monolithic superhydrophobic sponge prepared in Comparative Example 1 exhibits superhydrophobicity in both its outer and inner layers, with a water droplet contact angle of 152° and an oil droplet contact angle of 0°.
[0050] Example 3 The Janus sponges prepared in Examples 1-3 were compared with Comparative Example 1 (original superhydrophilic sponge) and Comparative Example 2 (monolithic superhydrophobic sponge) to test their oil absorption rate and saturated oil absorption capacity. The test oils were high-viscosity crude oil (~200 mPa·s) and low-viscosity pump oil (~50 mPa·s). The Janus sponges, original superhydrophilic sponges, and monolithic superhydrophobic sponges were placed in oil layers floating on the water surface.
[0051] The results showed that the original sponge absorbed both oil and water simultaneously and quickly sank to the bottom, failing to achieve oil-water separation. The Janus sponge and the monolithic superhydrophobic sponge, on the other hand, selectively absorbed oil without absorbing water. For high-viscosity crude oil, the Janus sponge reached oil saturation within 60 seconds, while the monolithic hydrophobic sponge in Comparative Example 1 required over 120 seconds; their final saturation oil absorption capacities were similar. This indicates that the Janus sponge of this invention maintains a high oil absorption capacity while increasing the oil absorption rate by approximately two times. Furthermore, for low-viscosity pump oil, the Janus sponge still has advantages, but the difference is narrowing. This demonstrates the unique acceleration effect of this invention for high-viscosity fluids.
[0052] The establishment of Comparative Examples 1 and 2, by forming a stark contrast with the present invention, powerfully demonstrates that: The necessity of asymmetric Janus structure: a simple monolithic hydrophilic sponge (Comparative Example 1) cannot achieve oil-water separation; a simple monolithic superhydrophobic sponge (Comparative Example 2) has insufficient oil absorption dynamics and consumes a lot of materials.
[0053] The synergistic effect of this invention is that only by combining the selectivity (superhydrophobicity) of the outer layer with the strong driving force (superhydrophilic capillary force) of the interior can the multiple goals of rapid, efficient, selective oil absorption and economic and environmental protection be achieved simultaneously.
[0054] The embodiments disclosed in this specification are merely illustrative of one aspect of the invention, and the scope of protection of the invention is not limited to these embodiments. Any other functionally equivalent embodiments fall within the scope of protection of the invention. Those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the scope of protection of the claims of this invention.
Claims
1. A Janus sponge with rapid oil-water separation capability, characterized in that, The Janus structure comprises an inner network structure forming super-hydrophilicity and an outer layer forming a super-hydrophobic layer with a preset thickness.
2. The Janus sponge with rapid oil-water separation capability according to claim 1, characterized in that, The preset thickness is 1-5 mm.
3. The Janus sponge with rapid oil-water separation ability according to claim 2, characterized in that, The preset thickness is 1 mm, or 3 mm, or 5 mm.
4. The Janus sponge with rapid oil-water separation ability according to claim 1, characterized in that, The three-dimensional porous elastic matrix is any one of polyurethane sponge, melamine sponge and cellulose sponge.
5. The Janus sponge with rapid oil-water separation ability according to claim 1, wherein, The low surface energy substance is a combination of one or more of long-chain alkyl silane, fluorinated alkyl silane, stearic acid and polydimethylsiloxane.
6. A method for preparing the Janus sponge with rapid oil-water separation ability according to any one of claims 1-5, characterized in that, The method comprises the following steps: Step 1: any one of polyurethane sponge, melamine sponge and cellulose sponge is selected as the three-dimensional porous elastic matrix, and the three-dimensional porous elastic matrix is pretreated to obtain a pretreated three-dimensional porous elastic matrix; Step 2: an initial super-hydrophobic layer is formed on the outer layer of the pretreated three-dimensional porous elastic matrix; Step 3: a solution of low surface energy substance is prepared; Step 4: a local immersion method or a surface coating method is used to make only the outer layer of the pretreated three-dimensional porous elastic matrix contact the low surface energy solution, and by controlling the immersion depth or coating thickness, it is ensured that only the area with the preset thickness of the pretreated three-dimensional porous elastic matrix is modified, thereby obtaining a final super-hydrophobic layer and forming a super-hydrophilic structure in the interior of the pretreated three-dimensional porous elastic matrix.
7. The method for preparing Janus sponge with rapid oil-water separation capability according to claim 6, characterized in that, In step 1, the pretreatment comprises ultrasonic cleaning and drying in sequence.
8. The method for preparing Janus sponge with rapid oil-water separation capability according to claim 6, characterized in that, Acetone, ethanol and deionized water are used for ultrasonic cleaning.
9. The method for preparing Janus sponge with rapid oil-water separation capability according to claim 6, characterized in that, In step 3, the solvent of the solution is ethanol, n-hexane or toluene.