Super-hydrophobic material for oil-water separation and preparation method thereof

Abstract

The invention belongs to the field of oily wastewater treatment, and particularly relates to a super-hydrophobic material for oil-water separation and a preparation method of the super-hydrophobic material. The super-hydrophobic material comprises a substrate, a basic coating and a hydrophobic coating, the substrate is made of paper, the basic coating comprises a polydopamine layer and a copper atom coating, and the component of the hydrophobic coating is a thiol compound. The preparation method of the super-hydrophobic material provided by the invention is simple, and the paper is modified step by step through a dip-coating method, so that the super-hydrophobic paper which is simple in process, low in manufacturing cost and easy to recover is formed.

Description

Technical Field

[0001] The invention belongs to the field of oily wastewater treatment, and in particular relates to a super-hydrophobic material for oil-water separation and a preparation method thereof. Background Art

[0002] Frequent oil spills and the continuous discharge of oily wastewater pose a great threat to the ecological environment, marine ecosystems and human health. Therefore, efficient oil-water separation methods are crucial to solving such environmental problems.

[0003] Paper has the characteristics of low production cost, biodegradability, recyclability and good mechanical properties, and has great application potential in the field of oil-water separation and filtration. In order to meet the requirements of oil-water separation, paper needs to be hydrophobicized.

[0004] The construction of artificial super-hydrophobic surfaces requires corresponding low surface energy and roughness to achieve super-hydrophobicity. Based on these two points, people usually use two methods to prepare this super-hydrophobic surface: constructing a rough structure on the surface of a material with low surface free energy; modifying a low surface energy substance on the surface of a material with a rough structure. However, what is lacking is that the micro-nanostructures formed by these two preparation methods will be irreversibly damaged under the action of external forces, thereby reducing the super-hydrophobic effect of the surface, so it is necessary to further explore the simple preparation method of super-hydrophobic coatings.

[0005] At present, there are many methods for preparing super-hydrophobic surfaces, such as sol-gel method, template method, plasma method, layer-by-layer assembly method and phase separation method, but these methods have disadvantages such as difficulty in implementation, limitation of instruments and equipment, and complicated and cumbersome preparation methods, which to some extent limit the development of super-hydrophobic paper.

[0006] Existing super-hydrophobic paper has defects such as relatively complicated preparation methods and processes, resins are not resistant to acid and alkali, making them impractical, and fluorine-containing materials are toxic and cannot be recycled. Therefore, it is of great research value and significance to prepare super-hydrophobic paper with good stability and simple and easy preparation methods. Summary of the invention

[0007] In view of the above technical problems, the present invention provides a super hydrophobic material for oil-water separation and a preparation method thereof. The preparation method is simple, and the paper is modified step by step by a dip coating method, thereby forming a super hydrophobic paper with simple process, low manufacturing cost and easy recycling.

[0008] The present invention is achieved through the following technical solutions:

[0009] A super-hydrophobic material for oil-water separation, comprising a substrate, a base coating and a hydrophobic coating; the substrate is paper, the base coating comprises a polydopamine layer and a copper atom coating, and the hydrophobic coating comprises a thiol compound.

[0010] Furthermore, the paper used for the substrate includes one or more of printing paper, offset paper, writing paper, inkjet printing paper, pre-coated paper, wrapping paper, filter paper, and drawing paper; The thiol compound is n-dodecyl mercaptan or n-octadecyl mercaptan.

[0011] Furthermore, the oil-water separation efficiency of the superhydrophobic material exceeds 90%, and the static contact angle of the superhydrophobic material to water is greater than 150°.

[0012] A method for preparing a super-hydrophobic material for oil-water separation comprises the following steps: sequentially coating a polydopamine coating, a copper atom coating and a hydrophobic coating on a substrate surface through three-step dip coating.

[0013] Furthermore, the method specifically comprises: (1) Prepare dopamine solution; (2) One-time dip coating: the substrate is immersed in the dopamine solution for a certain period of time, dopamine undergoes self-polymerization and is deposited on the surface of the substrate to form a polydopamine coating, which is then dried; (3) Secondary dip coating: the material obtained in step (2) is immersed in a solution containing copper ions, polydopamine is used as a reducing agent to reduce the copper ions to copper atoms, and polydopamine is used as an adhesive to adhere the copper atoms to the surface of the polydopamine coating to form a copper atom coating, and then dried; (4) Three-time dip coating: immersing the material obtained in step (3) in an ethanol solution of a thiol compound, so that the thiol compound and the reduced copper atoms are tightly combined to form a hydrophobic layer; drying to prepare a super hydrophobic material for oil-water separation having a surface of polydopamine coating / copper atom coating / hydrophobic layer.

[0014] Furthermore, the pH of the dopamine solution in step (1) is 8.5-8.8; the concentration of the dopamine solution is 0.2-0.8 g / L; and the pH of the dopamine solution is adjusted using Tris-HCl buffer solution and deionized water.

[0015] Furthermore, in step (2), the substrate is immersed in the dopamine solution for 10-30 h at a temperature of 30-45°C; and the drying condition is: drying in an oven at 40-70°C for 1-2 h.

[0016] Furthermore, in step (3), the solution containing copper ions is a copper acetate solution, a copper chloride solution or an anhydrous copper sulfate solution; The concentration of copper ions in the copper ion-containing solution is 20-50 mM, and the immersion time is 3-5 h; the drying condition is: drying in an oven at 40-70 °C for 1-2 h.

[0017] Furthermore, in step (4), the thiol compound is n-dodecyl mercaptan; The concentration of n-dodecyl mercaptan in the ethanol solution of the thiol compound is 1-5 mM; the immersion time is 4-8 h; and the drying conditions are: drying in an oven at 40-70 °C for 1-2 h.

[0018] The invention discloses an application of a super-hydrophobic material for oil-water separation, wherein the super-hydrophobic material is used for preparing waterproof packaging materials, moisture-proof labels, paper ground films, outdoor waterproof advertisements, separation of oily wastewater, and recovery of leaked crude oil.

[0019] Beneficial technical effects of the present invention: The super-hydrophobic material provided by the present invention is to form due low surface energy and surface roughness structure of dopamine, copper and thiol compounds on the surface of paper fiber by dip coating, so as to achieve the effect of super-hydrophobicity. Wherein dopamine needs to be oxidatively polymerized into polydopamine in an environment with a room temperature of 30 to 45 ° C, so that polydopamine, as an intermediate, is well attached to the surface of paper by copper elements, so that the surface roughness of paper is increased. Finally, low surface energy is obtained by modification of thiol compounds, so that paper is finally made to have good super-hydrophobic properties. The paper surface hydrophobicity obtained by the method is good, and the super-hydrophobic coating is stable and uniform, and oil-water separation can be effectively performed, and the preparation conditions are mild.

[0020] The preparation method of the super hydrophobic material provided by the present invention is simple, and the raw materials used are cheap and easily available; the base paper used is relatively cheap in the market, and the base paper is converted into a hydrophobic material through a simple three-step dipping process, and the hydrophobic material has broad application prospects.

[0021] The final super-hydrophobic material (modified paper) prepared by the present invention is easy to recycle and pollution-free. Several drugs used in the experiment are non-toxic and harmless in small amounts and are easy to handle.

[0022] The super hydrophobic material prepared by the present invention is resistant to acid and alkali. Since n-dodecyl mercaptan can combine with metal to form a metal protective film on the surface of the material, the acid and alkali resistance of the material is increased. In addition, the long-chain hydrocarbon structure of n-dodecyl mercaptan makes the surface of the material have good hydrophobicity. This hydrophobicity makes it difficult to be destroyed in certain acid and alkali environments, thereby showing a certain acid and alkali corrosion resistance.

[0023] The super-hydrophobic material provided by the present invention has a good hydrophobic effect, which can reach a hydrophobic effect of more than 150°, so that its final oil-water separation efficiency can reach more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a SEM image of the surface of the super-hydrophobic material prepared in Example 2 of the present invention (magnification ratio 200um); Figure 2 This is a SEM image of the surface of the super-hydrophobic material prepared in Example 2 of the present invention (magnification ratio 3.0 um); Figure 3 Schematic diagram of the contact angle of the coating prepared in Example 1 of the present invention; Figure 4 Schematic diagram of the contact angle of the coating prepared in Example 2 of the present invention; Figure 5 Schematic diagram of the contact angle of the coating prepared in Example 3 of the present invention; Figure 6 Schematic diagram of the contact angle of the coating prepared in Example 4 of the present invention; Figure 7 Schematic diagram of the contact angle of the coating prepared in Example 5 of the present invention; Figure 8 Schematic diagram of the contact angle of the coating obtained in Example 6 of the present invention; Fig. 9 Schematic diagram of the contact angle of the coating prepared in Example 7 of the present invention; Fig.10 Schematic diagram of the contact angle of the coating prepared in Example 8 of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. Those skilled in the art can fully understand the present invention without the description of these details.

[0027] The present invention provides a super-hydrophobic material for oil-water separation and a preparation method thereof. The super-hydrophobic material is specifically hydrophobic paper, which is used to solve the technical defects in the prior art that the preparation process and procedure are relatively complicated, the fluorine-containing polymer is harmful to human health, and it is not conducive to paper recycling.

[0028] The preparation method adopted by the present invention is a dip coating method. The prepared super hydrophobic material comprises a base coating and a hydrophobic coating. The base coating comprises a polydopamine layer and a copper atom coating, and the hydrophobic coating is n-dodecyl mercaptan.

[0029] In order to illustrate the present invention in more detail, a super hydrophobic paper and a preparation method thereof provided by the present invention are specifically described below in conjunction with embodiments.

[0030] Embodiment 1: A method for preparing a super-hydrophobic material for oil-water separation, comprising: Take a cut filter paper, first rinse the filter paper with deionized water, adjust the pH of 1.5 M Tris-HCl buffer solution to about 8.5 with deionized water, then dissolve dopamine in the solution to form a dopamine solution with a concentration of 0.2 g / L, and immerse the filter paper in the above solution. Soak for 12 hours, then take out the filter paper and dry it in a 65 °C oven for 1~2 hours.

[0031] The dried paper with polydopamine coating on the surface was immersed in an anhydrous copper sulfate solution with a copper ion concentration of 40 mM, left to soak at room temperature for 4 hours, and then taken out and dried in an oven at 65 °C for 1-2 hours; The paper modified with dopamine and copper sulfate was immersed in a 2 mM dodecanethiol solution, left to soak for 6 h, and then taken out and dried in an oven at 65 °C for 1-2 h.

[0032] Embodiment 2: A method for preparing a super-hydrophobic material for oil-water separation, comprising: Take a cut filter paper, first rinse the filter paper with deionized water, adjust the pH of 1.5 M Tris-HCl buffer solution to about 8.5 with deionized water, then dissolve dopamine in the solution to form a dopamine solution with a concentration of 0.8 g / L, and immerse the filter paper in the above solution. Soak for 24 hours, then take out the filter paper and dry it in a 65 °C oven for 1~2 hours.

[0033] The dried paper with polydopamine coating on the surface was immersed in an anhydrous copper sulfate solution with a copper ion concentration of 40 mM, left to soak at room temperature for 4 hours, and then taken out and placed in an oven at 65°C for drying for 1-2 hours.

[0034] The paper modified with dopamine and copper sulfate was immersed in a 2 mM dodecanethiol solution, left to soak for 6 hours, and then taken out and dried in an oven at 65°C for 1 to 2 hours.

[0035] Figure 1This is a SEM image of the surface of the super-hydrophobic material prepared in Example 2 (magnification ratio 200 um). It can be seen from the image that many fine particles are attached to the surface of the paper and are relatively uniform. Figure 2 This is a SEM image (magnification ratio 3.0 um) of the surface of the super-hydrophobic material prepared in Example 2. As can be seen from the image, flower-like clusters of substances are produced on the surface, which is a manifestation of good adhesion of n-dodecyl mercaptan on the surface.

[0036] Embodiment 3: A method for preparing a super-hydrophobic material for oil-water separation, comprising: Take a cut filter paper, first rinse the filter paper with deionized water, adjust the pH of 1.5 M Tris-HCl buffer solution to about 8.5 with deionized water, then dissolve dopamine in the solution to form a dopamine solution with a concentration of 0.8 g / L, and immerse the filter paper in the above solution. Soak for 24 hours, then take out the filter paper and dry it in a 65 °C oven for 1~2 hours.

[0037] The dried paper with polydopamine coating on the surface was immersed in an anhydrous copper sulfate solution with a copper ion concentration of 20 mM, left to soak at room temperature for 4 hours, and then taken out and placed in an oven at 65°C for drying for 1-2 hours.

[0038] The above-mentioned paper modified with dopamine and copper sulfate was immersed in a 2 mM dodecanethiol solution, left to soak for 6 hours, and then taken out and dried in an oven at 65°C for 1-2 hours.

[0039] Embodiment 4: A method for preparing a super-hydrophobic material for oil-water separation, comprising: Take a cut filter paper, first rinse the filter paper with deionized water, adjust the pH of 1.5 M Tris-HCl buffer solution to about 8.5 with deionized water, then dissolve dopamine in the solution to form a dopamine solution with a concentration of 0.8 g / L, and immerse the filter paper in the above solution. Soak for 12 hours, then take out the filter paper and dry it in a 65 °C oven for 1~2 hours.

[0040] The dried paper with polydopamine coating on the surface was immersed in an anhydrous copper sulfate solution with a copper ion concentration of 40 mM, left to soak at room temperature for 4 hours, and then taken out and placed in an oven at 65°C for drying for 1-2 hours.

[0041] The paper modified with dopamine and copper sulfate was immersed in a 5 mM dodecanethiol solution, left to soak for 6 h, and then taken out and dried in an oven at 65 °C for 1-2 h.

[0042] Embodiment 5: A method for preparing a super-hydrophobic material for oil-water separation, comprising: Take a cut filter paper, first rinse the filter paper with deionized water, adjust the pH of 1.5 M Tris-HCl buffer solution to about 8.5 with deionized water, then dissolve dopamine in the solution to form a dopamine solution with a concentration of 2 g / L, and immerse the filter paper in the above solution. Soak for 24 hours, then take out the filter paper and dry it in a 65 °C oven for 1-2 hours.

[0043] The dried paper with polydopamine coating on the surface was immersed in an anhydrous copper sulfate solution with a copper ion concentration of 40 mM, left to soak at room temperature for 4 hours, and then taken out and placed in an oven at 65°C for drying for 1-2 hours.

[0044] The above-mentioned paper modified with dopamine and copper sulfate was immersed in a 2 mM n-dodecyl mercaptan solution, left to soak for 6 hours, taken out and placed in an oven at 65°C for drying for 1-2 hours.

[0045] Embodiment 6: A method for preparing a superhydrophobic material for oil-water separation, comprising: Take a cut filter paper, first rinse the filter paper with deionized water, adjust the pH of the ammonia water to about 8.5 with deionized water, then dissolve dopamine in the solution to form a dopamine solution with a concentration of 0.8 g / L, and immerse the filter paper in the above solution. Soak for 24 hours, then take out the filter paper and dry it in an oven at 65 °C for 1-2 hours.

[0046] The dried paper with polydopamine coating on the surface was immersed in an anhydrous copper sulfate solution with a copper ion concentration of 40 mM, left to soak at room temperature for 4 hours, and then taken out and placed in an oven at 65°C for drying for 1-2 hours.

[0047] The paper modified with dopamine and copper sulfate was immersed in a 2 mM dodecanethiol solution, left to soak for 6 hours, and then taken out and dried in an oven at 65°C for 1 to 2 hours.

[0048] Embodiment 7: A method for preparing a superhydrophobic material for oil-water separation, comprising: Take a cut filter paper, first rinse the filter paper with deionized water, adjust the pH of 1.5 M Tris-HCl buffer solution to about 8.5 with deionized water, then dissolve dopamine in the solution to form a dopamine solution with a concentration of 0.8 g / L, and immerse the filter paper in the above solution. Soak for 24 hours, then take out the filter paper and dry it in a 65 °C oven for 1~2 hours.

[0049] The dried paper with polydopamine coating on the surface was immersed in a 40 mM copper chloride solution, left to soak at room temperature for 4 hours, and then taken out and dried in an oven at 65°C for 1 to 2 hours.

[0050] The paper modified with dopamine and copper sulfate was immersed in a 2 mM n-octadecyl mercaptan solution, left to soak for 6 hours, and then taken out and dried in an oven at 65°C for 1-2 hours.

[0051] Example 8: A method for preparing a superhydrophobic material for oil-water separation, comprising: taking a cut piece of printing paper, first rinsing the filter paper with deionized water, adjusting the pH of a 1.5 M Tris-HCl buffer solution to about 8.5 with deionized water, then dissolving dopamine in the solution to form a dopamine solution with a concentration of 0.8 g / L, and immersing the filter paper in the above solution. Soak for 24 hours, then take out the filter paper, and dry it in an oven at 65°C for 1 to 2 hours.

[0052] The dried paper with polydopamine coating on the surface was immersed in a copper acetate solution with a copper ion concentration of 40 mM, left to soak at room temperature for 4 hours, and then taken out and placed in an oven at 65°C for drying for 1 to 2 hours.

[0053] The paper modified with dopamine and copper sulfate was immersed in a 2 mM n-octadecyl mercaptan solution, left to soak for 6 hours, and then taken out and dried in an oven at 65°C for 1-2 hours.

[0054] In order to illustrate the effect of the drag-reducing and wear-resistant super-hydrophobic coating provided by the present application, the following tests were performed: Hydrophilic and hydrophobic contact angle test: The materials prepared in Examples 1 to 8 were tested for super hydrophobic contact angle using a surface contact angle measuring instrument. The contact angle photos of each modified paper obtained are shown in FIG. Figure 3-10 As shown, it can be seen that the modified papers prepared in Examples 1-8 all have superhydrophobic properties, and the static contact angles to water are all greater than 150°.

[0055] Oil-water separation test: The materials prepared in Examples 1-8 were tested for oil-water separation using an oil-water separation device, and the test results showed that the separation efficiency of the eight examples reached more than 90%, as shown in Table 1. This proves that the modified paper has good performance.

[0056] Table 1 shows the oil-water separation test results of the materials prepared by Examples 1-8

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A super hydrophobic material for oil-water separation, characterized in that: The super hydrophobic material comprises a substrate, a base coating and a hydrophobic coating; the substrate is paper, the base coating comprises a polydopamine layer and a copper atom coating, and the hydrophobic coating is composed of a thiol compound.

2. The super hydrophobic material for oil-water separation according to claim 1, characterized in that: The paper used for the substrate includes one or more of printing paper, offset paper, writing paper, inkjet printing paper, pre-coated paper, wrapping paper, filter paper, and drawing paper; The thiol compound is one or more of n-dodecyl mercaptan and n-octadecyl mercaptan.

3. The super hydrophobic material for oil-water separation according to claim 1, characterized in that: The oil-water separation efficiency of the super hydrophobic material exceeds 90%, and the static contact angle of the super hydrophobic material to water is greater than 150°.

4. A method for preparing a super-hydrophobic material for oil-water separation, for preparing the super-hydrophobic material according to any one of claims 1 to 3, characterized in that: The method sequentially coats a polydopamine coating, a copper atom coating and a hydrophobic coating on the surface of a substrate through three-step dip coating.

5. A method for preparing a super-hydrophobic material for oil-water separation according to claim 4, characterized in that, The method specifically comprises: (1) Prepare dopamine solution; (2) One-time dip coating: the substrate is immersed in the dopamine solution for a certain period of time, dopamine undergoes self-polymerization and is deposited on the surface of the substrate to form a polydopamine coating, which is then dried; (3) Secondary dip coating: the material obtained in step (2) is immersed in a solution containing copper ions, polydopamine is used as a reducing agent to reduce the copper ions to copper atoms, and polydopamine is used as an adhesive to adhere the copper atoms to the surface of the polydopamine coating to form a copper atom coating, and then dried; (4) Three-time dip coating: immersing the material obtained in step (3) in an ethanol solution of a thiol compound, so that the thiol compound and the reduced copper atoms are tightly combined to form a hydrophobic layer; drying to prepare a super hydrophobic material for oil-water separation having a surface of polydopamine coating / copper atom coating / hydrophobic layer.

6. A method for preparing a super-hydrophobic material for oil-water separation according to claim 5, characterized in that: The pH of the dopamine solution in step (1) is 8.5-8.8; the concentration of the dopamine solution is 0.2-0.8 g / L; the pH of the dopamine solution is adjusted using Tris-HCl buffer solution and deionized water.

7. A method for preparing a super-hydrophobic material for oil-water separation according to claim 5, characterized in that: In step (2), the substrate is immersed in the dopamine solution for 10-30 h at a temperature of 30-45°C; the drying condition is: drying in an oven at 40-70°C for 1-2 h.

8. A method for preparing a super-hydrophobic material for oil-water separation according to claim 5, characterized in that: In step (3), the solution containing copper ions is a copper acetate solution, a copper chloride solution or an anhydrous copper sulfate solution; The concentration of copper ions in the copper ion-containing solution is 20-50 mM, and the immersion time is 3-5 h; the drying condition is: drying in an oven at 40-70 °C for 1-2 h.

9. A method for preparing a super-hydrophobic material for oil-water separation according to claim 5, characterized in that: In step (4), the thiol compound is n-dodecyl mercaptan; The concentration of n-dodecyl mercaptan in the ethanol solution of the thiol compound is 1-5 mM; the immersion time is 4-8 h; and the drying conditions are: drying in an oven at 40-70 °C for 1-2 h.

10. The use of a super hydrophobic material for oil-water separation according to claims 1-3, characterized in that: The super-hydrophobic material is used for preparing waterproof packaging materials, moisture-proof labels, paper ground films, outdoor waterproof advertisements, separation of oily wastewater, and recovery of leaked crude oil.

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