Lignin hydrophobic modifier, modified hydrophobic sponge and preparation method and application thereof
By loading the lignin hydrophobic modifier on the surface of the sponge, the problem that existing sponges cannot selectively remove oil in oil-water separation is solved, and the hydrophobicity of the sponge and the efficient adsorption of oil is achieved, which is suitable for cleaning of offshore oil spills.
Patent Information
- Application Number
- CN202311533554.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-17
- Publication Date
- 2025-05-20
AI Technical Summary
Existing polymer sponges cannot selectively remove oil in oil-water separation, and society’s dependence on petroleum energy has led to an increase in demand for alternatives.
The lignin hydrophobic modifier is prepared by the reaction of enzymatic lignin, diisocyanate compounds and long-chain fatty alcohols, and is loaded to the skeleton surface of the sponge by immersion coating, giving the sponge hydrophobic and lipophilic properties.
The hydrophobicity improvement of the sponge surface is achieved, its adsorption ability to oil is improved, and it can effectively selectively remove oil from the oil-water mixture, which is suitable for the cleaning and recovery of offshore oil spills.
Smart Images
Figure CN120020169A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of hydrophobic sponges, and particularly relates to a lignin hydrophobic modifier, a modified hydrophobic sponge obtained from the lignin hydrophobic modifier, and a preparation method and application thereof. Background Art
[0002] The frequent occurrence of oil spill accidents has brought catastrophic impacts to the marine environment and ecological systems. Therefore, the treatment of oil spills has received increasing attention worldwide. Traditional methods for treating crude oil spills include in-situ combustion, chemical treatment with dispersants, oil-water separation, filtration, bioremediation, photocatalysis, etc. Among these methods, the oil-water separation method has become one of the most feasible methods for treating crude oil spills due to its advantages of high efficiency and low cost.
[0003] In recent years, three-dimensional network cross-linked sponges with a polymer backbone have been widely studied in oil-water separation due to their advantages such as low cost, porosity, and high specific surface area. However, due to their amphiphilic nature, sponges cannot selectively remove oil from oil-water mixtures. To achieve oil-water separation, hydrophobically modifying the sponge while maintaining its oil absorption capacity is a very effective approach.
[0004] In today's society, fossil energy is becoming increasingly depleted. As the second most abundant renewable resource in nature, lignin is regarded as a potential substitute for fossil energy. From the lignin structure model, it can be found that there are a large number of hydroxyl groups on the lignin molecule. Based on this property, lignin molecules can react with other functional molecules, providing a prerequisite for the preparation of high-value lignin-based materials. Summary of the Invention
[0005] The present invention provides a lignin hydrophobic modifier, which is obtained by reacting enzymatic lignin, diisocyanate compounds, and long-chain fatty alcohols, and then is loaded onto the surface of the sponge skeleton by a simple impregnation coating method, endowing the surface of the sponge with hydrophobic and oleophilic properties.
[0006] One of the purposes of the present invention is to provide a lignin hydrophobic modifier, and the structural formula is:
[0007]
[0008] In formula (I), R is one of alkylene, arylene, cycloalkylene, and n is an integer from 9 to 21;
[0009] Preferably, R is one of hexamethylene, methylphenyl trimethylcyclohexyl methanediphenyl methanedicyclohexyl and n is an integer from 11 to 17.
[0010] Another object of the present invention is to provide a method for preparing the lignin hydrophobic modifier described in one of the objects of the present invention, comprising: reacting enzymatically hydrolyzed lignin, a diisocyanate compound, and a long-chain fatty alcohol under the action of a catalyst to obtain the lignin hydrophobic modifier.
[0011] According to the present invention, the method for preparing the lignin hydrophobic modifier specifically comprises the following steps:
[0012] (a) Adding a diisocyanate compound and a catalyst to the enzymatically hydrolyzed lignin solution, and heating for reaction;
[0013] (b) Adding dropwise the long-chain fatty alcohol solution and continuing to heat for reaction;
[0014] (c) Adding an acid solution to the mixed solution obtained after the reaction in step (b) to precipitate a solid precipitate;
[0015] (d) After washing and drying the obtained solid precipitate, the lignin hydrophobic modifier is obtained.
[0016] According to a specific embodiment of the present invention, in the method for preparing the lignin hydrophobic modifier:
[0017] The enzymatically hydrolyzed lignin used can be the enzymatically hydrolyzed lignin commonly used in the art. For example, in the enzymatically hydrolyzed lignin used, the lignin content is ≥90 wt%, the residual sugar content is ≤5 wt%, the ash content is ≤5 wt%, and the phenolic hydroxyl group content is ≥10 wt%;
[0018] The diisocyanate compound used can be the diisocyanate compound commonly used in the art. Preferably, the diisocyanate compound is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, methylene diphenyl diisocyanate, and methylene dicyclohexyl diisocyanate;
[0019] The long-chain fatty alcohol is selected from fatty alcohols having 10 to 22 carbon atoms, preferably at least one of dodecanol, tetradecanol, hexadecanol, and octadecanol;
[0020] The catalyst is selected from at least one of triethanolamine, dibutyltin dilaurate, stannous octoate, and 1,4-diazabicyclooctane;
[0021] The acid solution is selected from at least one of inorganic acid solutions, preferably at least one of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution; the concentration of the acid solution is not particularly limited and can be selected within a relatively wide range. For example, an acid solution with a concentration of 0.1 to 5 M can be selected;
[0022] The addition amount of the acid solution is not particularly limited, as long as it can cause the lignin hydrophobic modifier to precipitate from the solution. For example, the addition amount of the acid solution is more than 2 times the volume of the mixed solution, preferably 3 - 5 times;
[0023] The molar ratio of the enzymatically hydrolyzed lignin to the diisocyanate compound is 1:(0.1 - 1), preferably 1:(0.5 - 1), where the enzymatically hydrolyzed lignin is calculated based on the hydroxyl groups in the enzymatically hydrolyzed lignin;
[0024] The molar ratio of the diisocyanate compound to the long-chain fatty alcohol is 1:(0.5 - 1.5), preferably 1:(0.5 - 1);
[0025] The addition amount of the catalyst is 0.01 - 2 wt% of the total amount of the enzymatically hydrolyzed lignin, the diisocyanate compound, and the long-chain fatty alcohol, preferably 0.05 - 0.5 wt%;
[0026] The concentration of the enzymatically hydrolyzed lignin solution is not particularly limited and can be selected within a relatively wide range. Specifically, the concentration of the enzymatically hydrolyzed lignin solution is 1 - 10 wt%, preferably 5 - 8 wt%;
[0027] The concentration of the long-chain fatty alcohol solution is not particularly limited and can be selected within a relatively wide range. Specifically, the concentration of the long-chain fatty alcohol solution is 1 - 20 wt%, preferably 8 - 15 wt%;
[0028] The solvents in the enzymatically hydrolyzed lignin solution and the long-chain fatty alcohol solution are the same or different, and are each independently selected from at least one of dimethyl sulfoxide and tetrahydrofuran.
[0029] According to the specific embodiments of the present invention, in the preparation method of the lignin hydrophobic modifier:
[0030] The reaction conditions in step (a) are to react at 20 - 50 °C for 2 - 4 h;
[0031] The reaction conditions in step (b) are to react at 20 - 50 °C for 2 - 4 h;
[0032] The dropping rate of the long-chain fatty alcohol solution in step (b) is 0.1 - 1 mL / min;
[0033] The drying temperature in step (d) is 40 - 60 °C.
[0034] Specifically, the lignin hydrophobic modifier can be prepared as follows:
[0035] Step 1, add a certain amount of enzymatically hydrolyzed lignin powder to solvent A and stir well until completely dissolved;
[0036] Step 2: Add a certain amount of long-chain carbon alcohol to solvent B and stir well until completely dissolved.
[0037] Step 3: Under the conditions of 20 - 50 °C, stirring, and condensation reflux, add the enzymatic hydrolysis lignin solution from Step 1 to a three-necked flask, add a certain amount of diisocyanate compound and catalyst, and react for 2 - 4 h.
[0038] Step 4: Keeping the above reaction conditions unchanged, slowly drip the long-chain carbon alcohol solution from Step 2 into the three-necked flask at a certain rate and continue to react for 2 - 4 h.
[0039] Step 5: Let the reaction mixture stand, cool to room temperature, and pour it into an acid solution to precipitate the reaction product.
[0040] Step 6: Filter the precipitated reaction mixture by suction and wash it repeatedly with deionized water until the filtrate is neutral.
[0041] Step 7: Vacuum dry the lignin hydrophobic modifier at 40 - 60 °C until constant weight to obtain the lignin hydrophobic modifier.
[0042] A third object of the present invention is to provide a modified hydrophobic sponge, comprising a sponge and the lignin hydrophobic modifier described in one of the objects of the present invention or the lignin hydrophobic modifier obtained by the preparation method described in the second object of the present invention.
[0043] A fourth object of the present invention is to provide a preparation method of the modified hydrophobic sponge described in the third object of the present invention, comprising: immersing the sponge in a lignin hydrophobic modifier solution, taking it out after sufficient infiltration, squeezing out the excess liquid, and drying to obtain the hydrophobic modified sponge.
[0044] According to the present invention, in the preparation method of the modified hydrophobic sponge, the concentration of the lignin hydrophobic modifier solution is 1 - 10 wt%, preferably 3 - 5 wt%; the solvent in the lignin hydrophobic modifier solution is an organic solvent, preferably tetrahydrofuran.
[0045] Specifically, the modified hydrophobic sponge can be prepared by the following process:
[0046] Step 1: Add the dried lignin hydrophobic modifier to tetrahydrofuran and stir until completely dissolved.
[0047] Step 2: Immerse the polyurethane sponge in the modifier solution for 10 - 30 minutes to fully infiltrate the sponge.
[0048] Step 3: Take the sponge out of the solution, squeeze out the excess liquid, and place it in a ventilated place to fully volatilize the organic solvent to obtain the hydrophobic modified sponge.
[0049] The fifth object of the present invention is to provide an application of the modified hydrophobic sponge described in the third object of the present invention or the modified hydrophobic sponge obtained by the preparation method described in the fourth object of the present invention in the cleaning and recovery of offshore oil spills.
[0050] The beneficial effects of the present invention are as follows:
[0051] In the technical solution adopted by the present invention, the phenolic hydroxyl groups and alcoholic hydroxyl groups in the enzymatically hydrolyzed lignin can undergo a condensation reaction with the alcoholic hydroxyl groups of long-chain carbon alcohols under the action of a catalyst through diisocyanate to obtain a hydrophobic compound with a benzene ring and a long carbon chain structure, and then it is loaded onto the surface of the sponge skeleton by a simple impregnation and coating method, endowing the surface of the sponge with hydrophobic and oleophilic properties. Description of the Drawings
[0052] Figure 1 Photos of the wetting of water and kerosene dropped on the modified sponges obtained in Example 4 and Comparative Example 2;
[0053] Figure 2 Photo of the water contact angle of the modified sponge obtained in Comparative Example 1;
[0054] Figure 3 Photo of the water contact angle of the modified sponge obtained in Example 4. Detailed Embodiments
[0055] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.
[0056] If there is no special limitation on the raw materials used in the examples and comparative examples, they are all disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.
[0057] Example 1
[0058] Preparation of lignin hydrophobic modifier:
[0059] Step 1, add 1 g of enzymatically hydrolyzed lignin powder (hydroxyl value 110 mg / g) to 19 g of dimethyl sulfoxide, and stir well until completely dissolved.
[0060] Step 2, add 1.3 g of octadecanol to 7.4 g of dimethyl sulfoxide, and stir well until completely dissolved.
[0061] Step 3, under the conditions of 40 °C, stirring, and condensation reflux, add the enzymatically hydrolyzed lignin solution in Step 1 into a three-necked flask, add 1 g of hexamethylene diisocyanate and 0.006 g of dibutyltin dilaurate, and react for 2 h.
[0062] Step 4, keeping the above reaction conditions unchanged, slowly add the long-chain carbon alcohol solution in Step 2 into the three-necked flask at a certain rate, finish the addition within half an hour, and continue to react for 2 h.
[0063] Step 5, let the reaction mixture stand still, cool it to room temperature, and pour it into a 1 M dilute hydrochloric acid solution to precipitate the reaction product.
[0064] Step 6, filter the precipitated reaction mixture by suction, and wash it repeatedly with deionized water until the filtrate is neutral.
[0065] Step 7, vacuum dry the lignin hydrophobic modifier at 40 °C until constant weight.
[0066] Example 2
[0067] Preparation of lignin hydrophobic modifier:
[0068] Step 1, add 2 g of enzymatically hydrolyzed lignin powder (hydroxyl value 120 mg / g) into 26 g of tetrahydrofuran, and stir well until completely dissolved.
[0069] Step 2, add 1.7 g of cetyl alcohol into 15 g of tetrahydrofuran, and stir well until completely dissolved.
[0070] Step 3, under the conditions of 30 °C, stirring, and condensation reflux, add the enzymatically hydrolyzed lignin solution in Step 1 into a three-necked flask, add 3.1 g of isophorone diisocyanate and 0.034 g of triethanolamine, and react for 4 h.
[0071] Step 4, keeping the above reaction conditions unchanged, slowly add the long-chain carbon alcohol solution in Step 2 into the three-necked flask at a certain rate, finish the addition within half an hour, and continue to react for 4 h.
[0072] Step 5, let the reaction mixture stand still, cool it to room temperature, and pour it into a 1 M dilute hydrochloric acid solution to precipitate the reaction product.
[0073] Step 6, filter the precipitated reaction mixture by suction, and wash it repeatedly with deionized water until the filtrate is neutral.
[0074] Step 7, vacuum dry the lignin hydrophobic modifier at 40 °C until constant weight.
[0075] Example 3
[0076] Preparation of lignin hydrophobic modifier:
[0077] Step 1: Add 2 g of enzymatically hydrolyzed lignin powder (hydroxyl value 120 mg / g) to a mixed solvent of 20 g of tetrahydrofuran and 3 g of dimethyl sulfoxide, and stir thoroughly until completely dissolved.
[0078] Step 2: Add 1.48 g of tetradecanol to a mixed solvent of 5 g of tetrahydrofuran and 5 g of dimethyl sulfoxide, and stir thoroughly until completely dissolved.
[0079] Step 3: Under the conditions of 25 °C, stirring, and reflux condensation, add the enzymatically hydrolyzed lignin solution in Step 1 to a three-necked flask, add 1.72 g of toluene diisocyanate and 0.004 g of 1,4-diazabicyclooctane, and react for 4 h.
[0080] Step 4: Keep the above reaction conditions unchanged, and add the long-chain carbon alcohol solution in Step 2 dropwise to the three-necked flask at a certain rate, finish dropping within half an hour, and continue to react for 4 h.
[0081] Step 5: Let the reaction mixture stand, cool to room temperature, and pour it into a 1 M dilute hydrochloric acid solution to precipitate the reaction product.
[0082] Step 6: Filter the precipitated reaction mixture by suction, and wash it repeatedly with deionized water until the filtrate is neutral.
[0083] Step 7: Vacuum-dry the lignin hydrophobic modifier at 40 °C until constant weight.
[0084] Example 4
[0085] Preparation of Hydrophobic Modified Sponge:
[0086] Step 1: Add 1 g of the lignin hydrophobic modifier prepared in Example 1 to 19 g of tetrahydrofuran, stir until completely dissolved, and obtain a modifier solution.
[0087] Step 2: Immerse the polyurethane sponge into the modifier solution obtained in Step 1, soak for 15 minutes to fully infiltrate the sponge.
[0088] Step 3: Take out the sponge from the solution, squeeze out the excess liquid, and place it in a ventilated place to fully volatilize the organic solvent to obtain a hydrophobic modified sponge.
[0089] Example 5
[0090] Preparation of Hydrophobic Modified Sponge:
[0091] Step 1: Add 1 g of the lignin hydrophobic modifier prepared in Example 2 to 32 g of tetrahydrofuran, stir until completely dissolved, and obtain a modifier solution.
[0092] Step 2: Immerse the polyurethane sponge into the modifier solution obtained in Step 1, soak for 30 minutes to fully infiltrate the sponge.
[0093] Step 3: Take out the sponge from the solution, squeeze out the excess liquid, and place it in a ventilated place to allow the organic solvent to fully volatilize, obtaining a hydrophobically modified sponge.
[0094] Example 6
[0095] Preparation of hydrophobically modified sponge:
[0096] Step 1: Add 1 g of the lignin hydrophobically modified agent prepared in Example 3 to 24 g of tetrahydrofuran, and stir until completely dissolved to obtain a modified agent solution.
[0097] Step 2: Immerse the polyurethane sponge into the modified agent solution obtained in Step 1, soak for 20 minutes to fully wet the sponge.
[0098] Step 3: Take out the sponge from the solution, squeeze out the excess liquid, and place it in a ventilated place to allow the organic solvent to fully volatilize, obtaining a hydrophobically modified sponge.
[0099] Comparative Example 1
[0100] Preparation of hydrophobically modified sponge:
[0101] Step 1: Add 1 g of enzymatically hydrolyzed lignin to 19 g of tetrahydrofuran, and stir until completely dissolved to obtain an enzymatically hydrolyzed lignin solution.
[0102] Step 2: Immerse the polyurethane sponge into the enzymatically hydrolyzed lignin solution obtained in Step 1, soak for 15 minutes to fully wet the sponge.
[0103] Step 3: Take out the sponge from the solution, squeeze out the excess liquid, and place it in a ventilated place to allow the organic solvent to fully volatilize, obtaining a hydrophobically modified sponge.
[0104] Comparative Example 2
[0105] Preparation of modified sponge:
[0106] Step 1: Immerse the polyurethane sponge into 20 g of tetrahydrofuran, soak for 15 minutes to fully wet the sponge.
[0107] Step 2: Take out the sponge from the solution, squeeze out the excess liquid, and place it in a ventilated place to allow the organic solvent to fully volatilize, obtaining a modified sponge.
[0108] Comparative Example 3
[0109] Preparation of hydrophobically modified sponge:
[0110] Step 1: Add 1 g of enzymatically hydrolyzed lignin powder (hydroxyl value 110 mg / g) to 19 g of dimethyl sulfoxide, and stir thoroughly until completely dissolved.
[0111] Step 2, under the conditions of 40 °C, stirring, and reflux condensation, add the enzymatically hydrolyzed lignin solution in Step 1 to a three-necked flask, add 1 g of hexamethylene diisocyanate and 0.006 g of dibutyltin dilaurate, and react for 2 h.
[0112] Step 3, let the reaction mixture stand, cool to room temperature, and pour it into a 1 M dilute hydrochloric acid solution to precipitate the reaction product.
[0113] Step 4, filter the precipitated reaction mixture by suction, and wash it repeatedly with deionized water until the filtrate is neutral, and dry it in vacuo at 40 °C to constant weight to obtain the enzymatically hydrolyzed lignin modifier.
[0114] Step 5, add 1 g of the enzymatically hydrolyzed lignin modifier to 19 g of tetrahydrofuran, and stir until completely dissolved.
[0115] Step 6, immerse the polyurethane sponge into 20 g of the enzymatically hydrolyzed lignin modifier tetrahydrofuran solution, soak for 15 minutes to fully wet the sponge.
[0116] Step 7, take out the sponge from the solution, squeeze out the excess liquid, and place it in a ventilated place to fully volatilize the organic solvent to obtain the hydrophobic modified sponge.
[0117] Figure 1 Pictures of the polyurethane sponge after being soaked in tetrahydrofuran solvent (Comparative Example 2) and lignin hydrophobic modifier solution (Example 4) are given. From Figure 1 it can be seen that the appearance of the polyurethane sponge soaked in tetrahydrofuran in Comparative Example 2 has no change, and both water and kerosene can completely wet it; while for the polyurethane sponge soaked in the lignin hydrophobic modifier in Example 4, the sponge is brown, kerosene can completely wet it, but water droplets can remain spherical on it, indicating that the modified sponge has good hydrophobicity.
[0118] Use a contact angle measuring instrument to measure the water contact angles of the modified polyurethane sponges obtained in Comparative Examples 1-3 and Examples 4-5. The specific test results are shown in Table 1.
[0119] Table 1. Water contact angles of modified polyurethane sponges
[0120] Number Water contact angle (°) Example 4 152 Example 5 145 Example 6 142 Comparative Example 1 102 Comparative Example 2 0 Comparative Example 3 105
[0121] From Table 1 and Figure 2 、 3It can be seen that after the polyurethane sponge in Comparative Example 1 was soaked in the tetrahydrofuran solution of enzymatically hydrolyzed lignin, the water contact angle could reach 102°, also showing a certain degree of hydrophobicity. This is because there are a large number of benzene ring structures on the skeleton of enzymatically hydrolyzed lignin. The water contact angle after the reaction of enzymatically hydrolyzed lignin with diisocyanate is basically the same as that of enzymatically hydrolyzed lignin, with little change. In the technical solution provided by the present invention, after the enzymatically hydrolyzed lignin is grafted and modified with long-chain fatty alcohol, the hydrophobicity of the polyurethane sponge is greatly improved, and the water contact angle can reach more than 140°, showing high hydrophobicity, which is beneficial to the modified sponge for the cleaning and recovery of offshore oil spills.
Claims
1. A lignin hydrophobic modifier having the structural formula: In the formula (I), R is one of an alkylene group, an arylene group and a cycloalkylene group, and n is an integer of 9 to 21.
2. The lignin hydrophobic modifier according to claim 1, characterized in that In the formula (I), R is one of hexamethylene, methylphenylene, trimethylcyclohexyl, methanediphenyl and methanedicyclohexyl, and n is an integer of 11-17.
3. A method for preparing the lignin hydrophobic modifier according to claim 1 or 2, comprising: The enzymatically hydrolyzed lignin, diisocyanate compounds and long-chain fatty alcohols are reacted under the action of a catalyst to obtain the lignin hydrophobic modifier.
4. The preparation method according to claim 3, characterized in that: The preparation method specifically comprises the following steps: (a) adding a diisocyanate compound and a catalyst to an enzymatically hydrolyzed lignin solution and heating the solution for reaction; (b) adding the long-chain fatty alcohol solution dropwise and continuing the heating reaction; (c) adding an acid solution to the mixed solution obtained after the reaction in step (b) to precipitate a solid precipitate; (d) washing and drying the obtained solid precipitate to obtain the lignin hydrophobic modifier.
5. The preparation method according to claim 4, characterized in that: The enzymatically hydrolyzed lignin has a phenolic hydroxyl content of ≥10 wt%; and / or The diisocyanate compound is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, methane diphenyl diisocyanate and methane dicyclohexyl diisocyanate; and / or, The long-chain fatty alcohol is selected from fatty alcohols having 10 to 22 carbon atoms, preferably at least one of lauryl alcohol, tetradecanol, hexadecanol and octadecyl alcohol; and / or, The catalyst is selected from at least one of triethanolamine, dibutyltin dilaurate, stannous octoate, and 1,4-diazabicyclooctane; and / or, The acid solution is selected from at least one of inorganic acid solutions, preferably at least one of hydrochloric acid solution, sulfuric acid solution and nitric acid solution; and / or, The amount of the acid solution added is more than 2 times the volume of the mixed solution, preferably 3 to 5 times; and / or, The molar ratio of the enzymatically hydrolyzed lignin to the diisocyanate compound is 1:(0.1-1), preferably 1:(0.5-1), wherein the enzymatically hydrolyzed lignin is calculated based on the hydroxyl groups in the enzymatically hydrolyzed lignin; and / or, The molar ratio of the diisocyanate compound to the long-chain fatty alcohol is 1:(0.5-1.5), preferably 1:(0.5-1); and / or, The amount of the catalyst added is 0.01-2 wt %, preferably 0.05-0.5 wt % of the total amount of enzymatically hydrolyzed lignin, diisocyanate compounds, and long-chain fatty alcohols; and / or, The concentration of the enzymatic lignin solution is 1 to 10 wt%, preferably 5 to 8 wt%; and / or, The concentration of the long-chain fatty alcohol solution is 1 to 20 wt%, preferably 8 to 15 wt%; and / or, The solvent in the enzymatic lignin solution and the solvent in the long-chain fatty alcohol solution are the same or different, and are independently selected from at least one of dimethyl sulfoxide and tetrahydrofuran.
6. The preparation method according to claim 4, characterized in that: The reaction conditions in step (a) are 20-50° C. for 2-4 hours; and / or, The reaction conditions in step (b) are 20-50° C. for 2-4 hours; and / or, The dripping speed of the long-chain fatty alcohol solution in step (b) is 0.1-1 mL / min; and / or, The drying temperature in step (d) is 40-60°C.
7. A modified hydrophobic sponge, comprising a sponge and the lignin hydrophobic modifier according to claim 1 or 2 or the lignin hydrophobic modifier obtained by the preparation method according to any one of claims 3 to 6.
8. A method for preparing the modified hydrophobic sponge according to claim 7, comprising: The sponge is immersed in the lignin hydrophobic modifier solution, taken out after being fully soaked, and the excess liquid is squeezed out, and the hydrophobic modified sponge is obtained after drying.
9. The preparation method according to claim 8, characterized in that: The concentration of the lignin hydrophobic modifier solution is 1 to 10 wt%, preferably 3 to 5 wt%; and / or, The solvent in the lignin hydrophobic modifier solution is an organic solvent, preferably tetrahydrofuran.
10. Use of the modified hydrophobic sponge according to claim 7 or the modified hydrophobic sponge obtained by the preparation method according to claim 8 or 9 in cleaning and recovering oil spills at sea.