A method for preparing a hydrophobic oil-absorbing sponge with high absorption capacity

Abstract

The present invention discloses a method for preparing a hydrophobic, oil-absorbing sponge with a high absorption capacity, comprising the following steps: dissolving coal tar in an organic solvent, adding maleic anhydride and reacting at high temperature, adding a polyamino compound and reacting at high temperature, removing the solvent, and washing the solid; immersing a clean melamine sponge in a diluted solution of a terminal electrophilic silane coupling agent, heating and refluxing; removing the sponge, washing, and drying; immersing the sponge in the re-dissolved solid solution, heating and refluxing; removing the sponge, washing, and drying to obtain the hydrophobic, oil-absorbing sponge. The coal tar-modified sponge exhibits strong hydrophobicity, with a saturated adsorption capacity of 74 to 187 g / g for oils and organic solvents, excellent chemical stability, and the ability to effectively separate oil / organic solvents from water. The sponge uses low-cost coal tar as a modifier, is suitable for large-scale production, and has great potential for application in oil spill treatment, preventing major accidents, and recovering oil / organic solvents.

Description

Technical Field

[0001] The invention belongs to the field of functional materials and oil-water separation, and particularly relates to a method for preparing a hydrophobic oil-absorbing sponge with high absorption capacity. Technical Background

[0002] Due to the frequent occurrence of oil and organic solvent spills, this has had a serious impact on the environment and ecosystem. Many traditional oil absorbents have been widely used in oil spill cleanup, including (1) natural inorganic materials such as activated carbon, zeolite, clay and diatomaceous earth; (2) natural organic materials or bio-based materials such as cotton fiber and rice husk, kapok fiber and sugarcane bagasse. Natural inorganic materials are characterized by low oil absorption capacity, poor oil / water selectivity and low buoyancy. Natural organic materials have relatively little impact on the removal of spilled oil and are easy to recover. However, these adsorbents have poor surface hydrophobicity, low oil absorption capacity and low buoyancy.

[0003] Compared with these methods and technologies, physical adsorption-based oil absorbents such as fabrics and sponges seem to be a more attractive approach because of their low cost, easy availability, and low density. Among them, commercial sponges are often used as strong adsorption media because they have high porosity, low density, and a large internal surface area, which can absorb various liquids (including water and oil). However, melamine sponges exhibit superhydrophilicity and superlipophilicity and cannot selectively absorb oil during oil-water separation. In order to achieve oil / water separation, superhydrophobic modification of sponges is an effective way while maintaining the ability to absorb oil. Therefore, superhydrophobic modification of melamine sponges is necessary.

[0004] In general, superhydrophobic materials can be prepared by combining micro / nanostructures and low surface energy materials. Several materials, including fluorinated compounds, fatty acids, polydimethylsiloxane, carbon nanotubes, and reduced graphene oxide, have been used to change the wettability of commercial sponges from superhydrophilic to superhydrophobic by increasing surface roughness and reducing surface energy. Although many oil-absorbing materials have been successfully prepared using these modifiers, their practical application is hampered by the high cost and use of complex equipment. Therefore, efforts should be made to seek more effective and low-cost hydrophobic alternatives to deal with oil spills from the perspective of industrial applications. Summary of the Invention

[0005] The present invention aims to provide a method for preparing a hydrophobic oil-absorbing sponge with high absorption capacity. The obtained sponge can effectively absorb oil / organic solvents floating on water and sinking under water, and has the advantages of high absorption capacity and low cost.

[0006] A method for preparing a hydrophobic oil-absorbing sponge with high absorption capacity, the method comprising the following steps:

[0007] (1) reacting coal tar dissolved in an organic solvent with maleic anhydride at 60-140° C. for 1-12 hours to obtain anhydride-treated coal tar;

[0008] (2) adding a polyamino compound having the structure of general formula I to the anhydride-treated coal tar, allowing the polyamino compound and the anhydride-treated coal tar to undergo a reflux reaction (at 50-140° C. for 1-8 hours), removing the solvent after the reaction and washing the solid to obtain an amination-treated coal tar having the structure of general formula II;

[0009] (3) immersing a clean melamine sponge in a diluted solution of a terminal electrophilic silane coupling agent having a structure of general formula III, and heating the solution at 60-140° C. for 1-6 hours; removing the sponge, washing it, and drying it to obtain a silanized sponge;

[0010] (4) Immersing the silanized sponge in a redissolved amination coal tar solution having the general formula II, reacting at 60-140° C. for 1-8 hours; removing the sponge, washing to remove unreacted coal tar components, and then drying to obtain a hydrophobic oil-absorbing sponge.

[0011]

[0012] in, coal tar

[0013] Among them, melamine sponge is a copolymer of formaldehyde, melamine and sodium bisulfite, R is an organic derivative group selected from alkanes, alkenes, etc.; m+n≥2; X is a hydrolyzable group selected from alkoxy, aryloxy, acyl, chloro, etc.; Y is an electrophilic group selected from vinyl, epoxy, isocyanate, cyano, etc.

[0014] The reaction route is as follows:

[0015]

[0016] In the technical solution described above, preferably, the coal tar is low-temperature coal tar, medium-temperature coal tar or high-temperature coal tar, which can be purchased from Shandong Guangxun Chemical Co., Ltd.

[0017] In the technical solution described above, preferably, in step (1), the mass of maleic anhydride is 10-100 wt.% of the mass of coal tar, preferably 10-50 wt.%.

[0018] In the technical solution described above, preferably, in step (1), the organic solvent for dissolving coal tar is one or more of dichloromethane, chloroform, toluene, tetrahydrofuran, and carbon tetrachloride.

[0019] In the technical solution described above, preferably, in step (1), the amount of the organic solvent used to dissolve the coal tar is 10-100 times the mass of the coal tar.

[0020] In the technical solution described above, preferably, in step (1), after the reaction is completed, the solvent is removed and the solid is washed; and the solid is dissolved again with an organic solvent.

[0021] In the technical solution described above, preferably, in step (1), the solvent used for washing the anhydride-treated coal tar is acetone or other solvent that can dissolve maleic anhydride but cannot dissolve coal tar.

[0022] In the technical solution described above, preferably, in step (2), the mass of the polyamino compound is 10-100% of the mass of the anhydride-treated coal tar product, preferably 40-80 wt.%.

[0023] In the technical solution described above, preferably, in step (2), the method for removing the solvent is rotary evaporation.

[0024] For the technical solution described above, preferably, in step (2), the amino compound has a structure of general formula I, that is, a small molecule or high molecular polymer with no less than one primary amine or secondary amine group, including but not limited to diethylenetriamine, triethylenetetramine, dendritic polyamidoamine, and N-(2-ethylamino)-1,3-propylenediamine.

[0025] In the technical solution described above, preferably, in step (2), the reaction temperature of the anhydride-treated coal tar and the amino compound is 70-120°C.

[0026] In the technical solution described above, preferably, in step (2), the reaction time of the anhydride-treated coal tar and the amino compound is 4-8 hours.

[0027] In the technical solution described above, preferably, in step (2), the solvent used to wash the reaction product of the anhydride-treated coal tar and the amino compound is one or more of ethanol, methanol, acetone, and water, and the anhydride-treated coal tar having the structure of general formula II is washed.

[0028] In the technical solution described above, preferably, in step (2), the clean melamine sponge is ultrasonically cleaned with one or more of ethanol, acetone, and methanol, and dried in a vacuum drying oven at 50-70° C. for 1-6 hours.

[0029] In the technical solution described above, preferably, in step (3), the silane coupling agent is diluted with a silane coupling agent diluent, and the silane coupling agent diluent is one or more of toluene, methylcyclohexane, xylene, and chloroform.

[0030] In the technical solution described above, preferably, in step (3), the volume ratio of the silane coupling agent to the silane coupling agent diluent is 1:40-1000.

[0031] In the technical solution described above, preferably, in step (3), the terminal electrophilic group Y of the silane coupling agent includes but is not limited to a vinyl group, an epoxy group, an isocyanate group, and a cyano group, and the terminal hydrolyzable group X includes but is not limited to an alkoxy group, an aryloxy group, an acyl group, and a chloro group. For example, the silane coupling agent is 3-(2,3-epoxy)propyltrimethoxysilane, vinyltriethoxysilane, γ-isocyanatepropyltrimethoxysilane, or trichlorovinylsilane.

[0032] In the technical solution described above, preferably, in step (3), the temperature for the reaction of the melamine sponge with the silane coupling agent is 90-120°C.

[0033] In the technical solution described above, preferably, in step (3), the reaction time of the melamine sponge and the silane coupling agent is 4-6 hours.

[0034] For the technical solution described above, preferably, in step (3), the washing solvent for the reaction product of the melamine sponge and the silane coupling agent is one or more of toluene, dichloromethane, chloroform, tetrahydrofuran, and carbon tetrachloride, and the reaction product of the melamine sponge and the silane coupling agent is ultrasonically cleaned by toluene, dichloromethane, chloroform, tetrahydrofuran, and carbon tetrachloride.

[0035] In the technical solution described above, preferably, in step (3), the drying temperature of the reaction product of the melamine sponge and the silane coupling agent after washing is 50-130° C. and the drying time is 1-6 hours.

[0036] In the technical solution described above, preferably, in step (4), the reaction temperature of the silanized sponge and the amination coal tar is 80-140°C.

[0037] In the technical solution described above, preferably, in step (4), the reaction time of the silanized sponge and the amination coal tar is 4-8 hours.

[0038] For the technical solution described above, preferably, in step (4), the solvent used for washing the reaction product of the silanized sponge and the amination coal tar is one or more of toluene, dichloromethane, chloroform, tetrahydrofuran, and carbon tetrachloride, and the reaction product of the silanized sponge and the amination coal tar is ultrasonically cleaned using one or more of toluene, dichloromethane, chloroform, tetrahydrofuran, and carbon tetrachloride.

[0039] In the technical solution described above, preferably, in step (4), the drying temperature after washing the reaction product of the silanized sponge and the amination coal tar is 50-130° C. and the drying time is 1-6 h.

[0040] The present invention also relates to a hydrophobic oil-absorbing sponge with high absorption capacity prepared by the above method.

[0041] Beneficial effects:

[0042] The method for preparing the hydrophobic oil-absorbing sponge with high absorption capacity of the present invention has the following advantages over the existing method for preparing the melamine sponge with oil absorption performance:

[0043] (1) The melamine sponge selected is a commercial product with low price and rich pore structure, which provides favorable conditions for adsorbing oil spills and organic solvents;

[0044] (2) The sponge is modified by using low-cost coal tar as a modifier, which has a wide source and low cost, and can therefore be prepared on a large scale;

[0045] (3) This method does not require complex equipment and uses the bridging effect of a silane coupling agent to covalently graft coal tar onto the sponge, which is not easy to fall off. The prepared sponge has good recycling performance, good mechanical durability, and strong chemical stability. It has great application potential in the field of oil / organic solvent and water separation to avoid major accidents in oil spill treatment and recovery of oil / organic solvents.

[0046] (4) The coal tar modified sponge has strong hydrophobicity (contact angle of 152.1°), and the saturated adsorption capacity of oils and organic solvents reaches 74-187 g / g, which can effectively separate oil / organic solvents and water. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is the infrared spectrum of the product after the reaction of coal tar and polyethyleneimine in Example 1.

[0048] Figure 2 This is the static water contact angle of the coal tar modified sponge prepared in Example 2.

[0049] Figure 3(a) is the compressive stress-strain curve of the coal tar-modified sponge prepared in Example 2 under different strains; (b) is the stress-strain curve of the coal tar-modified sponge prepared in Example 2 at the 1st, 10th, 50th and 100th cycle compression.

[0050] Figure 4 The static water contact angle of the sponge modified with silane coupling agent and further modified with coal tar prepared in Example 3.

[0051] Figure 5 (a) is the water contact angle of the silane coupling agent-modified sponge prepared in Example 3 and the silane coupling agent and coal tar-modified sponge after being immersed in aqueous solutions of pH = 1 and pH = 12 for 24 h; (b) is the water contact angle of the coal tar-modified sponge prepared in Example 3 after being immersed in four 1.5 M salt solutions and artificial seawater for 24 h.

[0052] Figure 6 Figure 4 shows the absorption of organic solvents above and below the surface by the coal tar-modified sponge prepared in Example 4. Photos of floating oil (0.1 g coal tar and 1 mL toluene) before (a) and after (b) absorption by the sponge, and photos of sinking oil (0.1 g coal tar and 1 mL chloroform) before (c) and after (d) selective absorption by the coal tar-modified sponge.

[0053] Figure 7 The absorption capacity of the coal tar modified sponge prepared in Example 4 after 10 absorptions and squeezes was obtained. The coal tar modified sponge was first immersed in n-heptane for 1 minute, the sponge was taken out and weighed immediately, and then the process was repeated 9 times to calculate the absorption capacity.

[0054] Figure 8 The absorption capacity of the coal tar-modified sponge prepared in Example 5 for various organic solvents and oils was shown. The coal tar-modified sponge was immersed in an organic solvent and silicone oil for 1 minute, then immediately removed and weighed to calculate its adsorption capacity. DETAILED DESCRIPTION

[0055] The present invention aims to provide a method for preparing a hydrophobic oil-absorbing sponge with high absorption capacity. The amino compound has a general structure of formula I, wherein R is an organic derivative group, that is, a small molecule or high molecular polymer with no less than one primary amine or secondary amine, including but not limited to diethylenetriamine, triethylenetetramine, dendritic polyamide amine, and N-(2-ethylamino)-1,3-propylenediamine; the amination coal tar has a general structure of formula II, that is, coal tar obtained by reacting a compound having a general structure of formula I with anhydride-treated coal tar; the terminal electrophilic silane coupling agent has a general structure of formula III, wherein R is an organic derivative group, X is a hydrolyzable group, including but not limited to an alkoxy group, an aryloxy group, an acyl group, and a chloro group, and Y is an electrophilic group, including but not limited to a vinyl group, an epoxy group, an isocyanate group, and a cyano group.

[0056]

[0057] in, coal tar

[0058] The reaction route is as follows:

[0059]

[0060] The following specific embodiments are provided to further illustrate the present invention and should not be construed as limiting the present invention in any manner.

[0061] Example 1

[0062] 1 g of coal tar (medium-temperature coal tar from Shandong Guangxun Chemical Co., Ltd.) was fully dissolved in 60 ml of toluene, 1 g of maleic anhydride was added, and the mixture was reacted at 120°C for 6 h. The solvent was removed by rotary evaporation, and the solid was washed with acetone to obtain anhydride-treated coal tar. The anhydride-treated coal tar solid was dissolved in 60 mL of toluene again, 0.5 g of N-(2-ethylamino)-1,3-propylenediamine was added, and the mixture was reacted at 120°C for 6 h. After removing the solvent, the solid was washed with ethanol to obtain amination-treated coal tar. Then, a melamine sponge (1*1*2 cm 3 , purchased from Xuxian sound insulation and heat preservation building materials) was ultrasonically cleaned three times with ethanol and acetone in sequence, and placed in a 60°C drying oven to constant weight; then immersed in 100mL of vinyltrimethoxysilane (purchased from Aladdin) dilution (the volume ratio of toluene to vinyltrimethoxysilane was 450:1), and refluxed at 110°C for 6h; the sponge was taken out, washed with toluene three times, and dried in a 110°C drying oven to constant weight; the sponge was immersed in a solution of ammoniated coal tar redissolved with 60mL of toluene, and refluxed at 120°C for 6h; the sponge was taken out, washed with toluene and dichloromethane in sequence, and dried in a 110°C drying oven to constant weight to obtain a hydrophobic oil-absorbing sponge.

[0063] from Figure 1 It can be seen that after anhydride treatment, coal tar 1771cm-1 The C=O peak of the anhydride appeared, but disappeared after amination. -1 and 1699cm -1 The NH peak at the bottom and the C=O peak of amide further illustrate the successful preparation of amination coal tar.

[0064] Example 2

[0065] 2 g of coal tar (medium-temperature coal tar from Shandong Guangxun Chemical Co., Ltd.) was fully dissolved in 80 mL of toluene, 1.5 g of maleic anhydride was added, and the mixture was reacted at 120°C for 8 h. The solvent was removed by rotary evaporation, and the solid was washed with acetone to obtain anhydride-treated coal tar. The solid was dissolved in 80 mL of toluene again, 1 g of diethylenetriamine was added, and the mixture was reacted at 120°C for 4 h. After removing the solvent, the solid was washed with methanol to obtain amination-treated coal tar. Then, a melamine sponge (1*1*2 cm 3 , purchased from Xuxian sound insulation and heat preservation building materials) was ultrasonically cleaned three times with ethanol and acetone in sequence, placed in a 60°C drying oven to constant weight, immersed in 100mL of vinyltriethoxysilane (purchased from Inokai) solution diluted with chloroform (the volume ratio of chloroform to vinyltriethoxysilane is 400:9), and refluxed at 80°C for 5h; the sponge was taken out, washed with chloroform three times, and dried in a 70°C drying oven to constant weight; the sponge was immersed in a solution of ammoniated coal tar redissolved in 80mL of toluene, and refluxed at 120°C for 6h; the sponge was taken out, washed with toluene and dichloromethane in sequence, and dried in a 110°C drying oven to constant weight to obtain a hydrophobic oil-absorbing sponge.

[0066] from Figure 2 It can be seen that the sponge modified with coal tar has super hydrophobicity, with a static contact angle of 156.1°. Figure 3 The results show that the compressed sponge can recover its original shape under strains of 20% to 80%. Even after 100 cycles of continuous compression at a high compression strain of 80%, only slight plastic deformation (5.5%) is observed, indicating its good mechanical durability.

[0067] Example 3

[0068] 1 g of coal tar (medium-temperature coal tar from Shandong Guangxun Chemical Co., Ltd.) was fully dissolved in 100 ml of chloroform, maleic anhydride was added and reacted at 70°C for 12 h, the solvent was removed by rotary evaporation, and the solid was washed with acetone to obtain anhydride-treated coal tar; the solid was dissolved in 150 mL of tetrahydrofuran, 0.5 g of dendrimer polyamide amine was added, and the reaction was carried out at 70°C for 6 h. After removing the solvent, the solid was washed with acetone and water to obtain amino-treated coal tar; then melamine sponge (MS) (1*1*2 cm 3, purchased from Xuxian sound insulation and heat preservation building materials) was ultrasonically cleaned three times with ethanol and acetone in sequence, placed in a 60°C drying oven to constant weight, immersed in 100mL of 3-(2,3-epoxy)propyltrimethoxysilane (purchased from Inokai) solution diluted with toluene (the volume ratio of 3-(2,3-epoxy)propyltrimethoxysilane to toluene is 3:1000), and refluxed at 120°C for 4h; the sponge was taken out, washed with toluene three times, and dried in a 110°C drying oven to constant weight to obtain MS-EP; the sponge was immersed in a solution of ammoniated coal tar redissolved in 100mL of chloroform, and refluxed at 70°C for 6h; the sponge was taken out, washed with toluene and chloroform three times in sequence, and placed in a 110°C drying oven to constant weight to obtain a hydrophobic oil-absorbing sponge (MS-EP-APT).

[0069] from Figure 4 It can be seen that the static contact angle of the sponge modified with silane coupling agent is 114.6°, and the static contact angle of the sponge further modified with coal tar reaches 141.2°. Figure 5 The water contact angle of MS-EP was 0° in both strong acid and strong alkaline solutions, while the water contact angle of MS-EP-APT remained virtually unchanged under these conditions. Furthermore, the water contact angle of MS-EP-APT remained unchanged after immersion in 1.5M NaCl, MgCl₂, KCl, CaCl₂ solutions, or artificial seawater for 24 hours, demonstrating superior chemical stability.

[0070] Example 4

[0071] 1 g of coal tar (medium-temperature coal tar from Shandong Guangxun Chemical Co., Ltd.) was fully dissolved in 90 ml of toluene, maleic anhydride was added and reacted at 120°C for 5 h, the solvent was removed by rotary evaporation, and the solid was washed with acetone to obtain anhydride-treated coal tar; the solid was dissolved in 90 mL of toluene again, 1 g of triethylenetetramine was added, and the reaction was continued at 120°C for 6 h, the solvent was removed, and the solid was washed with acetone and methanol to obtain amination-treated coal tar; a melamine sponge (1*1*2 cm 3 , purchased from Xuxian sound insulation and heat preservation building materials) was ultrasonically cleaned three times with ethanol and acetone in sequence, placed in a 60°C drying oven to constant weight, immersed in 100mL of γ-isocyanatepropyltrimethoxysilane (purchased from Aladdin) solution diluted with toluene (the volume ratio of toluene to γ-isocyanatepropyltrimethoxysilane is 450:1), and refluxed at 120°C for 5h; the sponge was taken out, washed with toluene three times, and then immersed in an amination coal tar solution redissolved with 90mL of toluene, and refluxed at 120°C for 6h; the sponge was taken out, washed with toluene and dichloromethane three times in sequence, and placed in a 110°C drying oven to constant weight to obtain a hydrophobic oil-absorbing sponge.

[0072] from Figure 6It can be seen that the prepared sponge has excellent adsorption properties for both above-water and underwater organic solvents. Figure 7 Taking n-heptane as an example, the prepared sponge still retained 91% of its initial absorption capacity after 10 absorption-squeezing cycles, indicating that it has good recycling performance.

[0073] Example 5

[0074] 1 g of coal tar (medium-temperature coal tar from Shandong Guangxun Chemical Co., Ltd.) was fully dissolved in 90 ml of toluene, maleic anhydride was added and reacted at 120°C for 7 h, the solvent was removed by rotary evaporation, and the solid was washed with acetone to obtain anhydride coal tar; the solid was dissolved in 100 mL of chloroform, 1 g of N-(2-ethylamino)-1,3-propylenediamine was added, and the reaction was carried out at 70°C for 6 h. After removing the solvent, the solid was washed with acetone and methanol to obtain amination coal tar; then a melamine sponge (1*1*2 cm 3 , purchased from Xuxian sound insulation and heat preservation building materials) was ultrasonically cleaned three times with ethanol and acetone in sequence, placed in a 60°C drying oven to constant weight, immersed in 100mL of trichlorovinylsilane (purchased from Aladdin) solution diluted with toluene (the volume ratio of toluene to trichlorovinylsilane is 500:1), and refluxed at 120°C for 6h; the sponge was taken out, washed with toluene three times, and then immersed in a solution of ammoniated coal tar redissolved in 90mL of toluene, and refluxed at 110°C for 6h; the sponge was taken out, washed with toluene three times, and placed in a 110°C drying oven to constant weight to obtain a hydrophobic oil-absorbing sponge.

[0075] from Figure 8 It can be seen that the prepared sponge has an adsorption capacity of 74 to 187 g / g.

[0076] Anyone skilled in the art will be able to utilize the above-disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or to modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention that do not depart from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a hydrophobic oil-absorbing sponge with high absorption capacity, characterized in that: The method comprises the following steps: (1) reacting coal tar dissolved in an organic solvent with maleic anhydride at 60-140° C. for 1-12 hours to obtain anhydride-treated coal tar; (2) adding a polyamino compound having a structure of the general formula I to the anhydride-treated coal tar, reacting the polyamino compound with the anhydride-treated coal tar at 50-140° C. for 1-8 hours, removing the solvent and washing the solid to obtain an amination-treated coal tar having a structure of the general formula II; (3) immersing a clean melamine sponge in a diluted solution of a terminal electrophilic silane coupling agent having a structure of general formula III, heating the solution at 60-140° C. for 1-6 hours; removing the sponge, washing it, and drying it to obtain a silanized sponge; (4) immersing the sponge in an amination coal tar solution and reacting at 60-120° C. for 1-8 hours; removing the sponge, washing, and drying it to obtain a hydrophobic oil-absorbing sponge; in, coal tar Wherein, R is an organic derivative group; m+n≥2; X is selected from hydrolyzable groups; Y is selected from electrophilic groups.

2. The method according to claim 1, characterized in that In step (3), X is selected from alkoxy, aryloxy, acyl, and chloro groups, and Y is selected from vinyl, epoxy, isocyanate, and cyano groups.

3. The method according to claim 1, characterized in that In step (1), the mass of maleic anhydride is 10-100% of the mass of coal tar; in step (2), the mass of the polyamino compound is 10-100% of the mass of anhydride-treated coal tar.

4. The method according to claim 1, wherein In step (1), the organic solvent for dissolving coal tar is one or more of dichloromethane, chloroform, toluene, tetrahydrofuran, and carbon tetrachloride.

5. The method according to claim 1, wherein The polyamino compound is a small molecule or high molecular polymer with no less than one primary amine or secondary amine group.

6. The method according to claim 1, characterized in that The polyamino compounds include diethylenetriamine, triethylenetetramine, dendritic polyamidoamine, and N-(2-ethylamino)-1,3-propylenediamine.

7. The method according to claim 1, characterized in that In step (3), the silane coupling agent is diluted with a silane coupling agent diluent, wherein the volume ratio of the silane coupling agent to the silane coupling agent diluent is 1:40-1000, and the silane coupling agent diluent is one or more of toluene, methylcyclohexane, xylene, and chloroform.

8. The method according to claim 1, characterized in that In step (2), after the reaction of the anhydride-treated coal tar and the polyamino compound is completed, the solvent is removed by rotary evaporation, and the solid is washed with one or more of ethanol, acetone, methanol, and water.

9. The method according to claim 1, characterized in that In step (3), the clean melamine sponge is ultrasonically cleaned with one or more of ethanol, acetone, and methanol, and then dried. The drying conditions are: drying at 50-70° C. for 1-6 hours.

10. The method according to claim 1, characterized in that In steps (3) and (4), the washing solvent is one or more of toluene, dichloromethane, chloroform, tetrahydrofuran, and carbon tetrachloride, and the drying conditions are: drying at 50-130° C. for 1-6 hours.

11. A hydrophobic oil-absorbing sponge with high absorption capacity prepared by the method according to any one of claims 1 to 10.

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