Oil-water separation sponge and preparation and application thereof

Abstract

The present application relates to a kind of oil-water separation sponges, the oil-water separation sponges include original sponge and in-situ growth on the surface of the original sponge nickel-copper double hydroxide flower ball cluster structure, and polydimethylsiloxane on the surface of the nickel-copper double hydroxide flower ball cluster structure.The present application also provides preparation and application of the oil-water separation sponges.The present application uses a simple method to prepare a kind of superhydrophobic superoleophilic high-efficiency oil-water separation sponges, which can be widely used in the field of oily sewage treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to oil-water separation sponge and its preparation and application. BACKGROUND

[0002] With the massive discharge of oil-containing wastewater in metal processing, steel, food and other industries and life, and the frequent occurrence of oil spill accidents in oil transportation and exploitation, oil-containing wastewater pollution has caused huge economic losses and serious ecological damage. The traditional methods for treating oil-containing wastewater mainly include physical method, chemical method and biological method. Among them, the physical method has low efficiency and is greatly affected by weather environment; the chemical method and the biological method need to invest a certain amount of chemical reagents for treatment, which is easy to cause secondary pollution. And the adsorption method gradually becomes an effective method for treating offshore oil spills and industrial and living oil-containing wastewater because of its fast treatment speed, high efficiency and no secondary pollution.

[0003] Sponge as a kind of three-dimensional porous adsorption material has the advantages of high porosity, large specific surface area, low density, easy modification and treatment, etc., and has good application prospect in oil-water separation field. However, the commercial sponge has poor selectivity for oil and water, and a large amount of water is also adsorbed during oil absorption, which affects the oil absorption efficiency and separation effect, so it cannot be directly used for oil-water separation. SUMMARY

[0004] In order to realize the effect of separating oil and water by sponge, the present application is made. The oil-water separation sponge prepared by the method has the advantages of fast oil absorption rate and good oil-water separation effect, and the preparation method is simple, low in cost and suitable for industrial application, which effectively solves the problems of poor adsorption and low separation efficiency of current commercial oil-water separation materials.

[0005] As an aspect of the present application, it relates to an oil-water separation sponge, which comprises a raw sponge and a nickel-copper double hydroxide flower ball cluster structure grown in situ on the surface of the raw sponge, and a polydimethylsiloxane (PDMS) on the surface of the nickel-copper double hydroxide flower ball cluster structure.

[0006] As another aspect of the present application, it relates to a method for preparing the above-mentioned oil-water separation sponge, comprising:

[0007] (1) growing nickel-copper double hydroxide (NiCu-OH) in situ on the surface of the sponge by hydrothermal synthesis method;

[0008] (2) soaking the sponge with nickel-copper double hydroxide grown in situ on the surface in a polydimethylsiloxane (PDMS) solution for surface modification.

[0009] In one embodiment, the sponge is cleaned before growing the nickel-copper double hydroxide in situ on the surface of the sponge. The sponge (1 cm x 1 cm x 1 cm) is sequentially cleaned with an acetone solution, an ethanol solution, and deionized water under ultrasonic cleaning for 10 minutes to remove impurities on the surface. The sponge is dried at 60°C for use.

[0010] In one embodiment, the hydrothermal synthesis method for growing the nickel-copper double hydroxide in situ on the surface of the sponge refers to immersing the sponge in a mixed solution of 1-10 moles of nickel nitrate hexahydrate, 0.5-1.5 moles of copper nitrate trihydrate, 30-50 moles of urea, and 20-40 moles of ammonium fluoride, and then performing a hydrothermal reaction. Preferably, the sponge is immersed in a mixed solution of 9 moles of nickel nitrate hexahydrate, 1 mole of copper nitrate trihydrate, 40 moles of urea, and 30 moles of ammonium fluoride, and then performing a hydrothermal reaction at 120°C.

[0011] In one embodiment, the polydimethylsiloxane (PDMS) solution refers to a n-hexane solution of PDMS: a-amino silane coupling agent curing cross-linking agent at a molar ratio of 10:1.

[0012] As another aspect of the present application, the use of the above-mentioned oil-water separation sponge in an oil-water separation process is disclosed.

[0013] In one embodiment, the oil-water separation refers to the oil-water separation of oily wastewater.

[0014] As another aspect of the present application, an oil-water separation method using the above-mentioned oil-water separation sponge is disclosed.

[0015] The present application uses a simple method to prepare a high-efficiency oil-water separation sponge with super-hydrophobic and super-oleophilic properties, which can be widely used in the field of oily wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a scanning electron microscope image of a sponge prepared in Example 1 of the present application. Figure 1 FIG. 2 is a scanning electron microscope image of a sponge prepared in Example 2 of the present application.

[0017] FIG. 3 is a schematic diagram of the contact angle of the surface of the sponge prepared in Example 2 of the present application with water droplets in air. Figure 2 FIG. 4 is a scanning electron microscope image of a sponge prepared in Example 3 of the present application.

[0018] FIG. 5 is a schematic diagram of the contact angle of the surface of the sponge prepared in Example 3 of the present application with water droplets in air. Figure 3 FIG. 6 is a schematic diagram of the contact angle of the surface of the sponge prepared in Example 3 of the present application with water droplets in air.

[0019] Appendix Figure 4 This is a diagram illustrating the oil absorption effect of the sponge prepared in Example 2 of the present invention. As can be seen from the diagram, the sponge can adsorb and separate the oil phase from the oil-water mixture.

[0020] Appendix Figure 5 This is a diagram showing the oil-water emulsion separation effect of the sponge prepared in Example 2 of the present invention. As can be seen from the figure, the emulsion contained many oil droplets before oil-water emulsion separation, and almost no residual oil droplets remained after separation by the sponge, proving that most of the oil droplets were adsorbed by the sponge. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] The inventors accidentally discovered that by controlling the microstructure and chemical composition of the sponge surface, a sponge with superhydrophobic and superoleophilic properties can be prepared. This sponge can selectively adsorb oil, and water cannot wet the sponge, thus achieving efficient oil-water separation.

[0023] This invention first prepares a sponge with a multi-level rough structure by growing a nickel-copper double hydroxide on the surface of a sponge through a hydrothermal reaction. This multi-level structure not only effectively improves the poor wettability of commercial sponges but also increases the specific surface area, allowing for the capture and aggregation of more oil droplets. Then, polydimethylsiloxane is used to modify it for superhydrophobicity, thereby obtaining a superhydrophobic and superoleophilic composite sponge with a multi-level structure. This method is simple and easy to implement, and the prepared composite sponge exhibits a high oil absorption rate and good oil-water separation effect, making it highly valuable for engineering applications in the treatment of oily wastewater.

[0024] Example 1

[0025] Selection of optimal conditions:

[0026] In the hydrothermal synthesis method for in-situ growth of nickel-copper double hydroxide on the surface of a sponge, the sponge is immersed in a mixed solution of 1-10 parts (in moles) of nickel nitrate hexahydrate, 0.5-1.5 parts of copper nitrate trihydrate, 30-50 parts of urea and 20-40 parts of ammonium fluoride for hydrothermal reaction.

[0027] Three of the proposed solutions are recorded below:

[0028] Option 1: 1 part nickel nitrate hexahydrate, 0.5 parts copper nitrate trihydrate, 30 parts urea, and 20 parts ammonium fluoride (see attached) Figure 1 a);

[0029] Option 2: 9 parts (in moles) of nickel nitrate hexahydrate, 1 part of copper nitrate trihydrate, 40 parts of urea, and 30 parts of ammonium fluoride (see attached) Figure 1 b);

[0030] Option 3: 10 parts (in moles) of nickel nitrate hexahydrate, 1.5 parts of copper nitrate trihydrate, 50 parts of urea, and 40 parts of ammonium fluoride (with accompanying...) Figure 1 c).

[0031] The results showed that, under different concentration conditions, nickel-copper double hydroxides with flower-like structures could be grown on the surface of the sponge. Among them, the structure grown by Scheme 2 was more uniform in the original sponge skeleton.

[0032] Example 2

[0033] (1) Preparation process and identification characteristics of oil-water separation sponge

[0034] First, the polyurethane sponge was cut into 1×1×1 cm cubes and ultrasonically cleaned in acetone, ethanol, and deionized water for ten minutes each. It was then dried in a 60℃ oven for 24 hours to obtain a clean polyurethane sponge. Next, 9 parts (molar amounts) of nickel nitrate hexahydrate, 1 part of copper nitrate trihydrate, 40 parts of urea, and 30 parts of ammonium fluoride were dissolved in 180 ml of deionized water and magnetically stirred at room temperature for 30 minutes to prepare a mixed solution. This mixed solution and the clean sponge were then poured into a 200 ml polytetrafluoroethylene liner and placed in a reaction vessel for hydrothermal reaction at 120℃ for 6 hours. Afterward, the sponge was removed, ultrasonically cleaned in deionized water for 5 minutes, and dried in a drying oven for later use. Finally, 1 g of… PDMS and 0.1g of curing agent were dissolved in 100ml of n-hexane and magnetically stirred for 30 minutes. The prepared sponge was then immersed in the PDMS solution for 30 minutes, followed by drying in a drying oven for 6 hours to obtain the oil-water separation sponge of this invention. The surface color of the sponge changed from intrinsic white to a uniform light blue. Furthermore, SEM morphology observation showed that the intrinsic sponge consisted of a smooth, porous skeleton (see attached image). Figure 2 a) Its pores are interconnected and have a diameter of approximately 500 μm; after surface microstructure construction and hydrophobic coating, the pore walls of this oil-water separation sponge have numerous flower-shaped clusters (see attached image). Figure 2 (b and 2c). In addition, attached... Figure 3 a indicates that the water contact angles of the intrinsic sponge and the superhydrophobic functional sponge are 120° and 154°, respectively, proving that the surface of the oil-water separation sponge after hydrophobic modification has superhydrophobic properties.

[0035] (2) Application of oil-water separation sponges

[0036] Appendix Figure 4 This demonstrates the separation process of oil-water two-phase mixtures using an oil-water separating sponge. When oil floats on the water surface, the superhydrophobic sponge directly contacts the oil, adsorbing it and removing it from the water. When oil sinks, the superhydrophobic sponge can immerse itself in the water, repelling the water and adsorbing only the oil, thus carrying it away from the water. On average, each gram of sponge can absorb 30-40 grams of oil. (Attached)Figure 5 Results of using the sponge to separate diesel / water emulsion are shown. The oil / water emulsion before separation appears milky white and opaque, while the filtrate after separation appears transparent, and high magnification images show that the small oil droplets in the emulsion have been adsorbed by the sponge prepared by the present application. In addition, the results prove that the separation efficiency of the sponge for different oil / water emulsions is all above 90%.

Claims

1. An oil-water separating sponge, characterized in that, The oil-water separation sponge includes a raw sponge and a nickel-copper double hydroxide flower cluster structure grown in situ on the surface of the raw sponge, as well as polydimethylsiloxane on the surface of the nickel-copper double hydroxide flower cluster structure. The method for preparing the water-separated sponge includes the following steps: (1) Soak the sponge in a mixed solution of 1-10 parts nickel nitrate hexahydrate, 0.5-1.5 parts copper nitrate trihydrate, 30-50 parts urea and 20-40 parts ammonium fluoride, and perform a hydrothermal reaction; (2) The sponge with in-situ grown nickel-copper double hydroxide was immersed in a polydimethylsiloxane solution for surface modification; The polydimethylsiloxane solution refers to a hexane solution with a PDMS:α-aminosilane coupling agent curing crosslinking agent molar ratio of 10:

1.

2. The water-separating sponge according to claim 1, characterized in that, Before growing nickel-copper double hydroxide on the surface of the sponge in situ, the sponge is first cleaned: the sponge is ultrasonically cleaned for ten minutes in sequence with acetone solution, ethanol solution and deionized water to remove impurities on the surface; it is then dried at 60°C for later use.

3. The water-separating sponge according to claim 1, characterized in that, The specific step (1) is as follows: soak the sponge in a mixed solution of 9 parts nickel nitrate hexahydrate, 1 part copper nitrate trihydrate, 40 parts urea and 30 parts ammonium fluoride, and perform a hydrothermal reaction at 120 degrees Celsius.

4. The application of the oil-water separation sponge as described in claim 1 in the oil-water separation process.

5. The application according to claim 4, characterized in that, The oil-water separation refers to the separation of oil from oily wastewater.

6. An oil-water separation method, characterized in that, The method uses the oil-water separation sponge described in claim 1.

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