Super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane and application

Abstract

The invention belongs to the technical field of oil-water separation materials, and particularly relates to a super-hydrophobic melamine sponge prepared on the basis of tannic acid and polydimethylsiloxane and application of the super-hydrophobic melamine sponge, namely tannic acid is introduced to generate a rough structure on the surface of the sponge, and then polydimethylsiloxane is used for modification. The hydrophobic angle of tannic acid, polydimethylsiloxane and melamine in the prepared super-hydrophobic sponge is as high as 154.8 degrees. Wherein the oil absorption capacity is the most remarkable performance, and the oil absorption capacity of the modified sponge can be kept 94.61% of that of the original sponge. Meanwhile, the separation efficiency of various oil-water mixtures / organic solvents exceeds 97.04%. In acid / alkaline solution, salt solution and mechanical pressing tests, the sponge shows excellent corrosion resistance and pressure resistance. Therefore, the excellent performance of the super-hydrophobic melamine sponge prepared based on the tannic acid and the polydimethylsiloxane is expected to further expand the application of a functional adsorption composite material in the field of oil-water separation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil-water separation materials, and particularly relates to a super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane and application thereof. BACKGROUND

[0002] Oil-water separation is an important technical requirement in the fields of environment and industry. Traditional methods have many limitations and are difficult to meet the requirements of high efficiency, stability and economy. Melamine sponge has become a potential oil-water separation material due to its unique three-dimensional porous structure and high specific surface area, but its hydrophilicity and limited adsorption performance limit the actual application effect. It is of great significance to develop efficient, stable and economical oil-water separation materials.

[0003] Three-dimensional melamine sponge has become an ideal skeleton in the field of oil-water separation due to its high open porosity of 99%, high specific surface area brought by three-dimensional through network, light weight, elasticity and compressible and resilient mechanical stability. Melamine sponge is mainly divided into original melamine foam, compressed melamine foam, flexible / semi-rigid / hard foam and functionalized modified sponge. However, the surface of original melamine sponge is rich in polar amino and hydroxyl groups, which shows both hydrophilicity and lipophilicity, and cannot selectively adsorb oil-water mixture. Therefore, it is particularly necessary to impart super-hydrophobicity and super-oleophilicity to the surface through surface modification, while retaining the advantages of low density, acid and alkali resistance and temperature resistance of melamine matrix, which can further improve the separation efficiency and service life. SUMMARY

[0004] The application aims to provide a super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane. By loading tannic acid on the surface of melamine sponge to construct a rough structure, and then modifying with polydimethylsiloxane, the super-hydrophobicity / super-oleophilicity is realized, and excellent oil-water separation performance and stability are exhibited.

[0005] The preparation method of the super-hydrophobic melamine sponge based on tannic acid and polydimethylsiloxane mainly includes the following steps: (1) 0.4-0.6 g of tannic acid and 0.25-1.0 g of 3-aminopropyltriethoxysilane are respectively dissolved in 200 mL of Tris buffer and 50 mL of ethanol. Then the two solutions are mixed. Then the pretreated melamine sponge is added, and stirred for 6-18 h. The melamine sponge is taken out, washed with deionized water and ethanol for 30 min to obtain a sample of tannic acid@melamine sponge. Finally, it is dried at 60℃ for 12 h.

[0006] The pretreated melamine sponge is obtained by ultrasonicating melamine sponge in ethanol, acetone and deionized water for 1 h respectively and then drying at 60℃, and the single volume is 1*1*1 cm³ and the input amount is 4.

[0007] (2) A certain amount of polydimethylsiloxane is added to n-hexane at 25 °C and stirred to prepare a polydimethylsiloxane solution with a concentration of 0.0125-0.05 w%. Then, the sponge obtained above is completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25 °C for 30-70 min. After drying in an oven at 180 °C for 2 hours, a superhydrophobic tannic acid@polydimethylsiloxane@melamine sponge is prepared.

[0008] The superhydrophobic melamine sponge based on tannic acid and polydimethylsiloxane prepared by the above method is applied to oil (organic solvent or oil compound) water separation.

[0009] The beneficial effects of the present application are: 1. Superhydrophobicity and high adsorption capacity: the hydrophobic angle of the modified sponge is as high as 155.0°, and the absorption capacity of various organic solvents and oil compounds is 73.0 to 180.7 times the weight of the sponge itself, and the hydrophobicity is maintained after 19 absorption-desorption cycles.

[0010] 2. High separation efficiency: the separation efficiency of various oil-water mixtures is greater than 97.0%, which can realize rapid and continuous oil-water separation.

[0011] 3. Stability and reusability: after treatment in different pH solutions, salt solutions and different temperatures for 12 h, the hydrophobic angle remains above 150°, with excellent acid and alkali resistance, salt solution stability and high temperature resistance; under the mechanical pressing test of a 500 g weight, it shows good elastic deformation and recovery ability, and the hydrophobicity is basically stable within a certain number of pressing times.

[0012] 4. Self-cleaning performance: it can effectively resist the attachment of solid suspended particles, prevent pore blockage, and maintain separation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The flowchart of the superhydrophobic melamine sponge prepared by the present application.

[0014] Figure 2 The FT-IR spectra of the original sponge and the modified sponge tannic acid@polydimethylsiloxane@melamine sponge in Example 1.

[0015] Figure 3 The XPS images of the original sponge, tannic acid@melamine sponge and tannic acid@polydimethylsiloxane@melamine sponge in Example 1.

[0016] Figure 4FESEM images of the original melamine sponge (ac), tannic acid@melamine sponge (df), and the superhydrophobic melamine sponge obtained in Example 1 (gi).

[0017] Figure 5 Images showing the selectivity of the original melamine sponge (top), the superhydrophobic melamine sponge (bottom left), and the cross-section of the superhydrophobic sponge (bottom right) obtained in Example 1 to oil and water.

[0018] Figure 6 This is the water contact angle image of the superhydrophobic melamine sponge obtained in Example 1.

[0019] Figure 7 This is a picture of the silver mirror phenomenon of the superhydrophobic melamine sponge obtained in Example 1 in water.

[0020] Figure 8 These are images of the superhydrophobic melamine sponge obtained in Example 1 and the original sponge in water.

[0021] Figure 9 These are images of the super-hydrophobic melamine sponge obtained in Example 1 adsorbing n-hexane and chloroform (stained with Sudan Red II).

[0022] Figure 10 Graph showing the adsorption capacity of the super-hydrophobic melamine sponge obtained in Example 1 for different organic solvents or oils.

[0023] Figure 11 This is a comparison chart of the adsorption capacity of the superhydrophobic melamine sponge obtained in Example 1 after 19 cycles of adsorption of chloroform and n-hexane.

[0024] Figure 12 Graph showing the separation efficiency of the superhydrophobic melamine sponge obtained in Example 1 for different organic solvent / water mixtures.

[0025] Figure 13 The change trend of the water contact angle of the superhydrophobic melamine sponge obtained in Example 1 when immersed in solutions with different pH values ​​and salt concentrations is shown.

[0026] Figure 14 The following is a trend of change in the water contact angle of the superhydrophobic melamine sponge obtained in Example 1 when immersed in deionized water at different temperatures.

[0027] Figure 15 Schematic diagram of the compression cycle of the superhydrophobic melamine sponge obtained in Example 1 and the changing trend of the water contact angle.

[0028] Figure 16 This is a self-cleaning performance test of the superhydrophobic melamine sponge obtained in Example 1. DETAILED DESCRIPTION

[0029] The application will be further described in connection with the following examples, but is not limited thereto. Example 1

[0030] (1) 0.5 g of tannic acid and 0.5 g of 3-aminopropyltriethoxysilane were dissolved in 200 mL of Tris buffer and 50 mL of ethanol, respectively. The above two solutions were mixed. Then, the pretreated melamine sponge was added, and after stirring for 12 h, the melamine sponge was taken out and washed with deionized water and ethanol for three times, respectively, to obtain a sample of tannic acid@melamine sponge, which was dried at 60°C for 12 h.

[0031] The method for pretreating the melamine sponge was as follows: the melamine sponge was ultrasonically treated in ethanol, acetone and deionized water for 1 h, respectively, and then dried at 60°C to obtain a single volume of 1*1*1 cm³, and the amount of the melamine sponge was 4.

[0032] (2) The polydimethylsiloxane was added to n-hexane at 25°C and stirred uniformly to prepare a 0.025wt% polydimethylsiloxane solution. Then, the sponge obtained above was completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25°C for 50 minutes. After drying in an oven at 180°C for 2 hours, a super-hydrophobic sponge, tannic acid@polydimethylsiloxane@melamine sponge, was prepared.

[0033] Figure 2 The FTIR spectra of the original melamine sponge and the modified sponge. In the spectrum of the original melamine sponge, the absorption bands at 809, 1573 and 3374 cm -1 nearby were attributed to the bending of triazine ring, C-N stretching and N-H stretching, respectively; the strong bending absorption peaks at 1326 and 1442 cm -1 were -CH- bending. These absorption band groups verified the chemical composition of the melamine sponge. New peaks appeared in the modified sponge. For the sample of tannic acid@melamine sponge, since the skeleton was the same, its spectrum was similar to that of the melamine sponge. Due to the presence of the tannic acid coating, the absorption peak of C-N (1573 cm -1 ) stretching vibration shifted to 1544 cm -1 ; a new absorption peak between 1050 and 1150 cm -1 appeared, which was the C-O group. In addition, the absorption peaks at 1257 and 2970 cm -1 were Si-CH3 stretching vibration peaks, and the absorption peak at 1026 cm -1 was the Si-O-Si bond absorption peak, indicating the successful coating of polydimethylsiloxane. This proved the successful preparation of the tannic acid@polydimethylsiloxane@melamine sponge sponge.

[0034] The image results of XPS are shown in Figure 3 The new peaks at binding energy 102.08 eV and 152.08 eV correspond to Si 2p and Si 2s, respectively, which prove that the polydimethylsiloxane as the binder has been effectively loaded on the tannin acid@polydimethylsiloxane@melamine sponge. In contrast, the original melamine sponge only appears C 1s, N 1s and O 1s characteristic peaks at 284.80 eV, 398.99 eV and 532.06 eV, which is consistent with the literature reports.

[0035] Figure 4 The surface morphology of the original melamine sponge, tannin acid@polydimethylsiloxane and tannin acid@polydimethylsiloxane@melamine sponge was analyzed by FESEM. The skeleton of the original melamine sponge is smooth and flat, showing a three-dimensional interconnected network shape. It is this special structure that makes it exhibit high oil absorption capacity and elasticity. Compared with the smooth surface of the original melamine sponge substrate, in Figure 4 (d-f), obvious particle adhesion is observed on the surface of the tannin acid-melamine sponge, which indicates that a rough surface morphology is obtained and the rough structure of the sponge is successfully constructed. As Figure 4 (g-i) shows that after loading polydimethylsiloxane, the sponge surface presents an obvious layered structure, and the polydimethylsiloxane is uniformly attached to the surface of the tannin acid particles. And it can be clearly observed that the modified tannin acid@polydimethylsiloxane@melamine sponge still shows an intact three-dimensional interconnected structure, which indicates that the porous structure of the sponge is well maintained during the manufacturing process and is not damaged, which can greatly retain the oil absorption capacity of the sponge.

[0036] The hydrophobic performance of the prepared tannin acid@polydimethylsiloxane@melamine sponge was explored by water contact angle (WCA). As Figure 5 shown, the original melamine sponge is a hydrophilic / oil-absorbing sponge, and the water contact angle is 0°. Through the modification of the surface of the melamine sponge, it is changed into a tannin acid@polydimethylsiloxane@melamine sponge with hydrophobic ability. From Figure 5 it can be observed that the water droplets on the surface of the modified sponge are at rest, while the oil droplets are still being absorbed. In addition, the prepared sponge is cut in the middle, and the water droplets can still be placed on the sponge, which indicates that the inside and outside of the sponge are successfully modified. Therefore, the water contact angle test was carried out on the tannin acid@polydimethylsiloxane@melamine sponge, and the WCA was 155.0° (Fig. 6). Figure 6 In addition, the tannin acid@polydimethylsiloxane@melamine sponge is a superhydrophobic sponge. At the same time, this also means that the above preparation method is feasible, and this result further indicates that the rough structure constructed by nanoparticles and the low surface energy material coated on the solid substrate can prepare superhydrophobic materials.

[0037] The original melamine sponge and the modified tannin@polydimethylsiloxane@melamine sponge were placed in water. The original sponge quickly absorbed water after contacting the water surface and thus sank to the bottom of the water. However, the modified sponge remained on the water surface after contacting the water surface. In addition, when the modified sponge was pressed into the water by applying an external force, a silver mirror phenomenon was clearly observed on the surface of the sponge, which is due to the trapping of air between the nanometer rough structure of the sponge and the water after the external force is applied into the water. The generation of the air layer effectively inhibits the absorption of water by the sponge. Figure 7 Figure 8

[0038] As examples, n-hexane and chloroform were used to simulate light oil and heavy oil in practical applications. The oil-water separation process is shown in Figure 9 When the tannin@polydimethylsiloxane@melamine sponge sponge touches the surface of the oil-containing wastewater, n-hexane is quickly absorbed by the prepared sponge within a few seconds. Due to the presence of capillary force, the organic solvent is absorbed into the prepared sponge and stored in the three-dimensional skeletal structure of the sponge. Similarly, for organic solvents with a density greater than water, when the modified sponge touches the chloroform at the bottom of the water, it is also quickly absorbed by the tannin@polydimethylsiloxane@melamine sponge sponge. In addition, the adsorbed chloroform can be maintained inside the sponge, and when the sponge is pulled out of the water, no droplets will fall off.

[0039] The modified sponge was saturated with 20 mL of oil or organic solvent (ligroin, n-octane, n-hexane, acetone, toluene, DMF, chloroform, carbon tetrachloride) and the mass before and after adsorption was measured. The adsorption capacity can be calculated according to the following equation: Q=(m1-m0) / m0 Where m0, m1 are the mass of the modified sponge before and after adsorption, and Q is the adsorption capacity.

[0040] The test results are shown in Figure 10 The modified sponge showed excellent adsorption capacity, with an adsorption capacity of 73.0 (ligroin) to 180.7 (carbon tetrachloride) times its own weight.

[0041] The prepared tannin@polydimethylsiloxane@melamine sponge not only has excellent oil absorption capacity, but also has great value in the field of oil pollution cleaning. Here, n-hexane and chloroform were chosen as adsorption solvents to evaluate the reusability of the sponge. As Figure 11 ​​As shown, the modified sponge adsorption capacity remained above 90.0% of the initial value after 19 cycles, which verified that the tannic acid-polydimethylsiloxane-melamine sponge had a reusable value in practical applications. Notably, after 19 adsorption-desorption cycles, the hydrophobic properties of the tannic acid-polydimethylsiloxane-melamine sponge were greatly reduced, and the water contact angle decreased from 155.0° to 146.8°.

[0042] Deionized water and organic solvents (n-hexane, chloroform, n-octane, acetone, toluene, DMF, and petroleum ether, carbon tetrachloride) were mixed at a volume ratio of 1:1, and the modified sponge was used to adsorb the organic solvents. The mass of the deionized water before and after separation was measured, and the oil-water separation efficiency was calculated using the following equation: η = m b / m a where m a and m b are the masses of the deionized water before and after separation, respectively, and η is the oil-water separation efficiency.

[0043] The test results are shown in Table 2. Figure 12 The mass of the water before and after gravity separation was used to specifically evaluate the oil-water separation efficiency of the functional sponge phenolic resin-silicon dioxide-stearic acid-melamine sponge. The separation efficiency of the phenolic resin-silicon dioxide-stearic acid-melamine sponge for petroleum ether / water, n-hexane / water, n-octane / water, toluene / water, acetone / water, DMF / water, carbon tetrachloride / water, and chloroform / water was greater than 97.0%, and the oil-water separation efficiency was very high.

[0044] The tannic acid-polydimethylsiloxane-melamine sponge was placed in hydrochloric acid solutions, sodium hydroxide solutions, and saturated sodium chloride salt solutions with different pH values, respectively. Due to the superhydrophobicity of the tannic acid-polydimethylsiloxane-melamine sponge, it floated above the solution. After 12 hours, the tannic acid-polydimethylsiloxane-melamine sponge still floated on the surface of the solution. After drying the sponge, the water contact angle test was performed to evaluate the hydrophobic properties of the sponge, and the results are shown in Table 3. Figure 13 The data in the figure show that the water contact angle of the sponge in solutions with pH = 2-13 and salt solutions with 0.75-2.75% decreased to different degrees, but were close to 150° or greater than 150°, still maintaining superhydrophobic properties. This indicates that the prepared sponge has excellent acid and alkali resistance and salt resistance.

[0045] Temperature tests were performed on the tannic acid-polydimethylsiloxane-melamine sponge. Figure 14Since superhydrophobic sponges are used in real life, seawater or oily wastewater has different temperatures, so temperature testing is necessary. Tannic acid @ polydimethylsiloxane @ melamine sponges were placed in aqueous solutions at different temperatures (-20, 0, 20, 40, 60, 80, and 100 °C). After 12 hours, the water contact angles of the tannic acid @ polydimethylsiloxane @ melamine sponges were measured, as shown in Figure 2. Figure 2 .15. This means that the functional tannic acid@polydimethylsiloxane@melamine sponge still has superhydrophobic properties at different temperatures.

[0046] In addition, since the functional sponge tannic acid @ polydimethylsiloxane @ melamine sponge needs to have stable mechanical properties, it was evaluated by applying a 500 g weight. After the weight was applied, the sponge immediately produced elastic deformation and was highly compressed. When the weight was removed, the sponge immediately recovered its shape, as shown in Figure 2. Figure 15 (a) This shows that the modified tannic acid@polydimethylsiloxane@melamine sponge still has the high elasticity of the original sponge, and the modification has not changed the three-dimensional structure of the sponge. The number of mechanical pressing times is continuously increased and the water contact angle is tested. The test results are shown as follows Figure 15 (b) As the number of mechanical compressions increases, the hydrophobicity of the tannic acid@polydimethylsiloxane@melamine sponge changes. At 60 compressions, the sponge changes from superhydrophobic to hydrophobic. This demonstrates that the tannic acid@polydimethylsiloxane@melamine sponge possesses both corrosion resistance and high temperature resistance, as well as high mechanical properties.

[0047] The water conditions in oceans and rivers are complex and are usually accompanied by various solid suspended particles. These particles can easily clog the pores of the separation material, resulting in a decrease in separation efficiency. Therefore, testing whether the functional material has self-cleaning properties can also be used to determine its superhydrophobic properties. Therefore, using gravel as the experimental object, the self-cleaning properties of the prepared tannic acid @ polydimethylsiloxane @ melamine sponge were tested. Figure 16 As shown in (a), due to the strong hydrophilicity of the original sponge, the dripping water is directly adsorbed by the sponge, making it impossible to wash away the sand. However, the tannic acid@polydimethylsiloxane@melamine sponge has excellent superhydrophobicity. The dripping water droplets have low adhesion to the sponge surface. The water droplets can easily roll down the inclined sponge surface without leaving any traces, thus washing away the sand ( Figure 16 (b)). Example 2

[0048] (1) Dissolve 0.4 g of tannic acid and 0.5 g of 3-aminopropyltriethoxysilane in 200 mL of Tris buffer and 50 mL of ethanol, respectively. Mix the two solutions. Then add the pretreated melamine sponge and stir for 12 h. Remove the melamine sponge and rinse it repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0049] (2) The preparation steps of tannic acid@polydimethylsiloxane@melamine sponge are the same as those in Example 1.

[0050] The water contact angle of the modified sponge is 154°, the adsorption capacities for n-hexane and chloroform are 73.2 g / g and 159.4 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 97.2%. Example 3

[0051] (1) Dissolve 0.6 g of tannic acid and 0.5 g of 3-aminopropyltriethoxysilane in 200 mL of Tris buffer and 50 mL of ethanol, respectively. Mix the two solutions. Then add the pretreated melamine sponge and stir for 12 h. Remove the melamine sponge and rinse it repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0052] (2) The preparation steps of tannic acid@polydimethylsiloxane@melamine sponge are the same as those in Example 1.

[0053] The water contact angle of the modified sponge is 154°, the adsorption capacities for n-hexane and chloroform are 72.8 g / g and 158.5 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 98.2%. Example 4

[0054] (1) Dissolve 0.5 g of tannic acid and 0.4 g of 3-aminopropyltriethoxysilane in 200 mL of Tris buffer and 50 mL of ethanol, respectively. Mix the two solutions. Then add the pretreated melamine sponge and stir for 12 h. Remove the melamine sponge and rinse it repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0055] (2) The preparation steps of tannic acid@polydimethylsiloxane@melamine sponge are the same as those in Example 1.

[0056] The water contact angle of the modified sponge is 152°, the adsorption capacities for n-hexane and chloroform are 70.6 g / g and 151.6 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 97.3%. Example 5

[0057] (1) 0.5 g tannic acid and 0.6 g 3-aminopropyltriethoxysilane were dissolved in 200 mL Tris buffer and 50 mL ethanol, respectively. The two solutions were mixed. Then the pretreated melamine sponge was added, and stirred for 12 h. The melamine sponge was taken out and washed repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0058] (2) The preparation procedure of tannic acid@polydimethylsiloxane@melamine sponge was the same as that of Example 1.

[0059] The water contact angle of the modified sponge was 153°, and the adsorption capacities of n-hexane and chloroform were 74.9 g / g and 161.3 g / g, respectively. The separation efficiency of n-hexane / water mixture was 98.4%. Example 6

[0060] (1) 0.5 g tannic acid and 0.5 g 3-aminopropyltriethoxysilane were dissolved in 200 mL Tris buffer and 50 mL ethanol, respectively. The two solutions were mixed. Then the pretreated melamine sponge was added, and stirred for 6 h. The melamine sponge was taken out and washed repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0061] (2) The preparation procedure of tannic acid@polydimethylsiloxane@melamine sponge was the same as that of Example 1.

[0062] The water contact angle of the modified sponge was 145°, and the adsorption capacities of n-hexane and chloroform were 67.5 g / g and 153.9 g / g, respectively. The separation efficiency of n-hexane / water mixture was 95.6%. Example 7

[0063] (1) 0.5 g tannic acid and 0.5 g 3-aminopropyltriethoxysilane were dissolved in 200 mL Tris buffer and 50 mL ethanol, respectively. The two solutions were mixed. Then the pretreated melamine sponge was added, and stirred for 18 h. The melamine sponge was taken out and washed repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0064] (2) The preparation procedure of tannic acid@polydimethylsiloxane@melamine sponge was the same as that of Example 1.

[0065] The water contact angle of the modified sponge was 151°, and the adsorption capacities of n-hexane and chloroform were 72.5 g / g and 162.4 g / g, respectively, and the separation efficiency of n-hexane / water mixture was 97.4%. Example 8

[0066] (1) The preparation steps of tannic acid@melamine sponge were the same as those of Example 1.

[0067] (2) A certain amount of polydimethylsiloxane was added to n-hexane at 25 °C and stirred uniformly to prepare a 0.0125wt% polydimethylsiloxane solution. Then, the sponge obtained above was completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25 °C for 50 minutes. After drying in an oven at 180 °C for 2 hours, the super-hydrophobic sponge tannic acid@polydimethylsiloxane@melamine sponge was prepared.

[0068] The water contact angle of the modified sponge was 151°, and the adsorption capacities of n-hexane and chloroform were 72.5 g / g and 162.4 g / g, respectively, and the separation efficiency of n-hexane / water mixture was 97.4%. Example 9

[0069] (1) The preparation steps of tannic acid@melamine sponge were the same as those of Example 1.

[0070] (2) A certain amount of polydimethylsiloxane was added to n-hexane at 25 °C and stirred uniformly to prepare a 0.05wt% polydimethylsiloxane solution. Then, the sponge obtained above was completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25 °C for 50 minutes. After drying in an oven at 180 °C for 2 hours, the super-hydrophobic sponge tannic acid@polydimethylsiloxane@melamine sponge was prepared.

[0071] The water contact angle of the modified sponge was 151°, and the adsorption capacities of n-hexane and chloroform were 72.5 g / g and 162.4 g / g, respectively, and the separation efficiency of n-hexane / water mixture was 97.4%. Example 10

[0072] (1) The preparation steps of tannic acid@melamine sponge were the same as those of Example 1.

[0073] (2) A certain amount of polydimethylsiloxane was added to n-hexane at 25 °C and stirred uniformly to prepare a 0.025wt% polydimethylsiloxane solution. Then, the sponge obtained above was completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25 °C for 30 minutes. After drying in an oven at 180 °C for 2 hours, the super-hydrophobic sponge tannic acid@polydimethylsiloxane@melamine sponge was prepared.

[0074] The water contact angle of the modified sponge is 152°, the adsorption capacity for n-hexane and chloroform is 74.2 g / g and 160.7 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 97.4%. Example 11

[0075] (1) The preparation steps of tannic acid@melamine sponge are the same as those in Example 1.

[0076] (2) A certain amount of polydimethylsiloxane was added to n-hexane at 25°C and stirred to prepare a 0.025 wt% polydimethylsiloxane solution. The sponge obtained above was then completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25°C for 70 minutes. After drying in an oven at 180°C for 2 hours, a superhydrophobic sponge, tannic acid@polydimethylsiloxane@melamine sponge, was prepared.

[0077] The water contact angle of the modified sponge is 151°, the adsorption capacities for n-hexane and chloroform are 68.4 g / g and 173.6 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 97.6%. Example 12

[0078] (1) Dissolve 0.5 g of tannic acid and 0.25 g of 3-aminopropyltriethoxysilane in 200 mL of Tris buffer and 50 mL of ethanol, respectively. Mix the two solutions. Then add the pretreated melamine sponge and stir for 12 h. After removing the melamine sponge, rinse it repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0079] (2) The experimental steps of tannic acid@polydimethylsiloxane@melamine sponge are the same as those in Example 1.

[0080] The water contact angle of the modified sponge is 150°, the adsorption capacities for n-hexane and chloroform are 63.7 g / g and 165.3 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 95.2%. Example 13

[0081] (1) Dissolve 0.5 g of tannic acid and 1.0 g of 3-aminopropyltriethoxysilane in 200 mL of Tris buffer and 50 mL of ethanol, respectively. Mix the two solutions. Then add the pretreated melamine sponge and stir for 12 h. Remove the melamine sponge and rinse it repeatedly with deionized water and ethanol for 30 min. The obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0082] (2) The experimental procedure of tannic acid@polydimethylsiloxane@melamine sponge is the same as Example 1.

[0083] The water contact angle of the modified sponge is 145°, the adsorption capacity of n-hexane and chloroform is 52.8 g / g and 151.6 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 93.4%. Comparative Example 1

[0084] (1) A certain amount of polydimethylsiloxane was added to n-hexane at 25 °C and stirred uniformly to prepare a 0.025wt% polydimethylsiloxane solution. Then, the melamine sponge was completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25 °C for 50 minutes. After drying in an oven at 180 °C for 2 hours, the superhydrophobic sponge polydimethylsiloxane@melamine sponge was prepared.

[0085] The water contact angle of the modified sponge is 140°, the adsorption capacity of n-hexane and chloroform is 41.3 g / g and 78.4 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 94.1%. Comparative Example 2

[0086] (1) 0.5 g of tannic acid and 0.5 g of 3-aminopropyltriethoxysilane were dissolved in 200 mL of Tris buffer and 50 mL of ethanol, respectively. The two solutions were mixed. Then, the pretreated melamine sponge was added and stirred for 12 h. After taking out the melamine sponge, it was repeatedly washed with deionized water and ethanol for 30 min, and the obtained sample tannic acid@melamine sponge was dried at 60 °C for 12 h.

[0087] The water contact angle of the modified sponge is 135°, the adsorption capacity of n-hexane and chloroform is 42.1 g / g and 76.3 g / g, respectively, and the separation efficiency of n-hexane / water mixture is 93.4%. Comparative Example 3

[0088] (1) 0.5 g of gallic acid and 0.5 g of 3-aminopropyltriethoxysilane were dissolved in 200 mL of Tris buffer and 50 mL of ethanol, respectively. The two solutions were mixed. Then, the pretreated melamine sponge was added and stirred for 12 h. After taking out the melamine sponge, it was repeatedly washed with deionized water and ethanol for 30 min, and the obtained sample gallic acid@melamine sponge was dried at 60 °C for 12 h.

[0089] (2) A certain amount of polydimethylsiloxane was added to n-hexane at 25 °C and stirred uniformly to prepare a 0.025 wt% polydimethylsiloxane solution. Then, the sponge obtained above was completely immersed in the dispersed polydimethylsiloxane solution and stirred at 25 °C for 50 minutes. After drying in an oven at 180 °C for 2 hours, a superhydrophobic tannic acid@polydimethylsiloxane@melamine sponge was prepared.

[0090] The water contact angle of the modified sponge was 148°, the adsorption capacity for n-hexane and chloroform was 61.7 g / g and 142.7 g / g, respectively, and the n-hexane / water mixture separation efficiency was 96.3%. Comparative Example 4

[0091] (1) 0.5 g of tannic acid and 0.5 g of 3-aminopropyltriethoxysilane were dissolved in 200 mL of Tris buffer and 50 mL of ethanol, respectively. The two solutions were mixed. Then, the pretreated melamine sponge was added and stirred for 12 h. After taking out the melamine sponge, it was washed repeatedly with deionized water and ethanol for 30 min. The obtained sample, tannic acid@melamine sponge, was dried at 60 °C for 12 h.

[0092] (2) A certain amount of polymethylphenylsiloxane was added to n-hexane at 25 °C and stirred uniformly to prepare a 0.025 wt% polymethylphenylsiloxane solution. Then, the sponge obtained above was completely immersed in the dispersed polymethylphenylsiloxane solution and stirred at 25 °C for 50 minutes. After drying in an oven at 180 °C for 2 hours, a superhydrophobic tannic acid@polymethylphenylsiloxane@melamine sponge was prepared.

[0093] The water contact angle of the modified sponge was 141°, the adsorption capacity for n-hexane and chloroform was 46.1 g / g and 91.8 g / g, respectively, and the n-hexane / water mixture separation efficiency was 94.2%. Comparative Example 5

[0094] (1) 0.5 g of tannic acid and 0.5 g of N-(2-aminoethyl)-3-aminopropyltriethoxysilane were dissolved in 200 mL of Tris buffer and 50 mL of ethanol, respectively. The two solutions were mixed. Then, the pretreated melamine sponge was added and stirred for 12 h. After taking out the melamine sponge, it was washed with deionized water and ethanol three times, respectively. The obtained sample, tannic acid@melamine sponge, was dried at 60 °C for 12 h.

[0095] (2) The experimental procedure of tannic acid@polydimethylsiloxane@melamine sponge was the same as that of Example 1.

[0096] The water contact angle of the modified sponge is 143°, the adsorption capacity of n-hexane and chloroform is 42.8 g / g and 93.5 g / g respectively, and the separation efficiency of n-hexane / water mixture is 92.1%.

[0097] The above embodiments are only preferred examples for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art based on the present application are within the protection scope of the present application. The protection scope of the present application is subject to the claims.

Claims

1. A super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane, characterized in that: The super-hydrophobic melamine sponge is prepared by introducing tannic acid to generate a rough structure on the sponge surface, and then modifying the sponge with polydimethylsiloxane to obtain a super-hydrophobic melamine sponge based on tannic acid and polydimethylsiloxane.

2. The super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane according to claim 1, characterized in that, The preparation method of the super hydrophobic melamine sponge comprises the following steps: (1) Tannic acid and 3-aminopropyltriethoxysilane were dissolved in buffer and ethanol, respectively, and mixed. The pretreated melamine sponge was added and stirred for 6-18 h. The sponge was then rinsed with deionized water and ethanol for 30 min to obtain a tannic acid-loaded melamine sponge. The sponge was then dried at 60 °C for 1 h. (2) Polydimethylsiloxane was stirred evenly in n-hexane to prepare a polydimethylsiloxane solution. The tannic acid-loaded melamine sponge was completely immersed in the dispersed polydimethylsiloxane solution, stirred at 25 °C for 30-70 min, and then dried in an oven at 180 °C for 2 h to obtain a superhydrophobic sponge.

3. The super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane according to claim 2, characterized in that, The mass ratio of the tannic acid to 3-aminopropyltriethoxysilane is 0.4-0.6:0.25-1.

0.

4. The super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane according to claim 2, characterized in that, The concentration of the tannic acid in the buffer solution is 0.2-0.3 g / ml; the concentration of the 3-aminopropyltriethoxysilane in the ethanol is 0.5-2.0 g / ml.

5. The super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane according to claim 2, characterized in that, The pretreated melamine sponge is obtained by ultrasonically treating the melamine sponge in ethanol, acetone and deionized water for 1 hour respectively and then drying it at 60°C. The volume of each melamine sponge is 1*1*1 cm³, and the input amount is 4.

6. The super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane according to claim 2, characterized in that, The concentration of the polydimethylsiloxane solution is 0.0125-0.05w%.

7. An application of the super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane according to claim 1, characterized in that: The super-hydrophobic melamine sponge is used for oil-water separation.

8. The use of the super-hydrophobic melamine sponge prepared based on tannic acid and polydimethylsiloxane according to claim 7, characterized in that: The oil-water separation is the separation of organic solvents or oil compounds from water.

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