Biochar modified melamine foam material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of adsorption materials, in particular to a charcoal modified melamine foam material as well as a preparation method and application thereof. The preparation method comprises the following steps: by taking melamine foam as a matrix, adding an alkali-activated charcoal dispersion liquid into the matrix, and loading alkali-activated charcoal through the matrix, so as to form a precursor; and sequentially adding hexadecane and dopamine hydrochloride into the precursor, and activating and modifying the alkali-activated biochar through hexadecane and dopamine hydrochloride by adopting an impregnation method to obtain the biochar modified melamine foam material. The prepared biochar modified melamine foam material has excellent super-hydrophobicity and super-lipophilicity, when the biochar modified melamine foam material is in contact with water, due to the fact that the surface of the biochar modified melamine foam material has a rough structure, and the surface energy is further reduced after cetane is soaked and covered, the biochar modified melamine foam material has excellent super-hydrophobicity and super-lipophilicity, and the biochar modified melamine foam material has excellent super-hydrophobicity and super-lipophilicity. The structures are difficult to wet by water and cannot enter the grid structures of the material, so that the hydrophobic and oleophylic effects are finally achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption materials, and in particular to a biochar-modified melamine foam material, a preparation method thereof, and applications thereof. Background Art

[0002] Oily produced water from energy extraction, such as oil and natural gas, has reached 250 million barrels per day. Oily wastewater is also discharged from processes such as washing, rinsing, mixing, and pasteurization in the food processing and dairy industries. Cutting oil, a highly mixed mixture of oil, water, and additives (such as surfactants, heavy metals, and biocides) in the metalworking industry, as well as sudden offshore oil well blowouts and cruise ship oil spills, all generate large quantities of oily wastewater. The oil in these wastewaters cannot be incinerated and is highly toxic. If not effectively treated, it will not only have a serious impact on the aquatic environment but also result in a waste of oil resources. The types and properties of oily wastewater are complex. In today's world of scarce water resources and growing environmental awareness, the effective treatment and recycling of oily wastewater is a pressing challenge in environmental science and engineering.

[0003] There are several methods for treating oily wastewater: chemical methods (in-situ combustion, coagulation, salting-out, etc.), physical methods (adsorption, fences, filtration, etc.), and biological methods (primarily degradation). In-situ combustion, when used to treat oil spills, not only impacts the surrounding environment but also produces harmful combustion products, resulting in a significant waste of crude oil resources. Coagulation, while using a coagulant to condense the oil film into lumps for recovery, can recover the crude oil, but its high cost makes it unsuitable for large-scale application. Dispersion, using the dispersant's inherent toxicity to promote rapid separation of the oil layer, fails to fundamentally resolve the problem and can produce significant side effects. Biodegradation, while non-toxic, is less effective on large oil films and cannot quickly remove the oil. Because the fence method requires appropriate meteorological conditions, and climate change at sea can be significant, it should only be used in emergencies. Adsorption, on the other hand, offers advantages such as simplicity, low cost, and no secondary pollution, making it a promising treatment method for oil spills.

[0004] At present, the adsorption method for treating crude oil leakage pollution mainly depends on the adsorption material, which mainly includes natural organic materials, inorganic materials and synthetic polymer materials. However, the adsorption materials used in the current adsorption method have the problems of limited adsorption capacity and high recovery difficulty. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a biochar-modified melamine foam material and a preparation method and application thereof, thereby solving the technical problem of limited adsorption performance of existing hydrophobic adsorption materials.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The first object of the present invention is to provide a method for preparing a biochar-modified melamine foam material, comprising the following steps: S1. Using melamine foam as a matrix, adding an alkali-activated biochar dispersion into the matrix, and loading the alkali-activated biochar through the matrix to form a precursor.

[0007] S2. Hexadecane and dopamine hydrochloride are sequentially added to the precursor, and the alkali-activated biochar is activated and modified by the hexadecane and dopamine hydrochloride using an impregnation method to obtain a biochar-modified melamine foam material.

[0008] Furthermore, during the loading process, 25 mL to 35 mL of alkali-activated biochar dispersion was added to the 1 cm × 1 cm × 1 cm melamine foam. The concentration of the alkali-activated biochar dispersion was 3 mg mL -1 ~7 mg·mL -1 .

[0009] Furthermore, the volume ratio of hexadecane to alkali-activated biochar dispersion is 3 mL:25 mL to 35 mL.

[0010] Furthermore, during the activation modification process, hexadecane was first added to the precursor, and the mixture was stirred and activated for 10 to 14 hours. Then, dopamine hydrochloride was added, and the pH was adjusted to 8 to 9, and the activation modification was carried out for 24 hours.

[0011] Furthermore, the method for preparing the alkali-activated biochar dispersion comprises the following steps: Pomegranate peel biochar was prepared by hydrothermal reaction at 200 ℃ using pomegranate peel powder as raw material. The pomegranate peel biochar was soaked in a NaOH solution and subjected to alkali modification under stirring conditions to obtain alkali-activated biochar, which was then dispersed in water to form an alkali-activated biochar dispersion.

[0012] Furthermore, during the hydrothermal reaction, the mass volume ratio of pomegranate peel powder and water was 1 g:8 mL~12 mL, and the hydrothermal reaction time was 8 h~10 h.

[0013] Furthermore, the concentration of NaOH solution is 1 mol·L -1 ~2 mol·L -1 The alkali modification time is 2 h to 3 h.

[0014] The second object of the present invention is to provide a biochar-modified melamine foam material, which is prepared by the above-mentioned preparation method of the biochar-modified melamine foam material.

[0015] The third object of the present invention is to provide the use of the above-mentioned biochar-modified melamine foam material as an adsorption material in oil-water separation.

[0016] The beneficial effect of the present invention is that, compared with the prior art, The present invention provides a preparation method of a biochar-modified melamine foam material. The method comprises the following steps: using melamine foam as a matrix, loading alkali-activated biochar on the matrix, and modifying the alkali-activated biochar by dopamine hydrochloride and hexadecane using an impregnation method and hexadecane as a cross-linking agent. The biochar can form micrometer-scale and nanometer-scale rough structures on the surface of the melamine foam. These rough structures and hydrophobic functional groups on the surface of the biochar can provide the material with excellent oil absorption capacity. Loading the long-chain organic substance hexadecane on the surface of the rough structure can further reduce the surface energy of the material and improve the hydrophobicity of the material, thereby forming a super-hydrophobic-super-oleophilic pomegranate peel biochar-modified melamine foam. In addition, the biochar particles can be firmly fixed on the surface of the melamine foam through cross-linking of the hexadecane functional groups, thereby improving the recyclability and stability of the material in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a scanning electron microscope image of PSB@MF prepared in Example 1 of the present invention.

[0018] Figure 2 Graph showing the hydrophobic properties of PSB@MF prepared in Examples 1 to 3 of the present invention.

[0019] Figure 3 Graph showing the adsorption capacity per unit volume of PSB@MF for ten oils and organic solvents of different properties according to Example 1 of the present invention. DETAILED DESCRIPTION

[0020] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0022] Currently, adsorption methods for treating crude oil spills rely heavily on the adsorbent material, which primarily includes natural organic materials, inorganic materials, and synthetic polymers. However, these materials suffer from limited adsorption capacity and are difficult to recycle. Therefore, finding a hydrophobic adsorbent with high adsorption capacity, strong hydrophobicity / lipophilicity, good stability, and easy recycling is crucial for the successful application of oil-water separation methods.

[0023] Based on this, on the one hand, the present invention provides a method for preparing a biochar-modified melamine foam material, comprising the following steps: S1. Using melamine foam as a matrix, adding an alkali-activated biochar dispersion into the matrix, and loading the alkali-activated biochar through the matrix to form a precursor.

[0024] S2. Hexadecane and dopamine hydrochloride are sequentially added to the precursor, and the alkali-activated biochar is activated and modified by the hexadecane and dopamine hydrochloride using an impregnation method to obtain a biochar-modified melamine foam material.

[0025] It should be noted that the present invention uses melamine foam as a matrix, loads alkali-activated biochar through the matrix, and uses an impregnation method. Dopamine hydrochloride is polymerized under weak alkaline conditions to form an intermediate adhesion layer, and the alkali-activated biochar is modified by dopamine hydrochloride and hexadecane, wherein the biochar can form micron-scale and nano-scale rough structures on the surface of the melamine foam. These rough structures and the hydrophobic functional groups on the surface of the biochar can provide the material with excellent oil absorption capacity; loading the long-chain organic substance hexadecane on the surface of the rough structure can further reduce the surface energy of the material and improve the hydrophobicity of the material, thereby forming a super-hydrophobic-super-oleophilic pomegranate peel biochar modified melamine foam, and the biochar particles can be firmly fixed on the surface of the melamine foam through cross-linking of the hexadecane functional groups, thereby improving the recyclability of the material and the stability in complex environments.

[0026] In some embodiments, during the loading process, 25 mL to 35 mL of alkali-activated biochar dispersion was added to 1 cm × 1 cm × 1 cm melamine foam, and the concentration of the alkali-activated biochar dispersion was 3 mg mL -1 ~7 mg·mL -1 .

[0027] It should be noted that to further improve the performance of the biochar-modified melamine foam, the melamine foam required pretreatment before use. The melamine foam was ultrasonically cleaned with anhydrous ethanol and then deionized water for 3 hours, followed by oven drying at 40°C. During the loading process, ultrasonic treatment was used to fully disperse the alkali-activated biochar in the alkali-activated biochar dispersion within the melamine foam's lattice structure.

[0028] In some embodiments, the volume ratio of hexadecane to the alkali-activated biochar dispersion is 3 mL: 25 mL to 35 mL. It should be noted that the hydrophobic nature of hexadecane significantly reduces the surface energy of the foam, forming a hydrophobic barrier that prevents water penetration. Compared with other hydrophobic agents, hexadecane is low-cost, safe, and environmentally friendly.

[0029] In some embodiments, the mass volume ratio of dopamine hydrochloride to alkali-activated biochar dispersion is 0.15 g to 0.2 g: 30 mL.

[0030] In some embodiments, during the activation modification process, hexadecane is first added to the precursor and stirred for activation for 10 to 14 hours. Dopamine hydrochloride is then added, and the pH is adjusted to 8 to 9, followed by activation modification for 24 hours. It should be noted that dopamine hydrochloride forms an intermediate adhesion layer through polymerization, optimizing the hydrophobic modification effect and enhancing the mechanical and chemical stability of the melamine foam.

[0031] In some embodiments, the method for preparing the alkali-activated biochar dispersion comprises the following steps: Step 1: Using pomegranate peel powder as raw material, a hydrothermal reaction is performed at 200° C. to prepare pomegranate peel biochar.

[0032] Step 2: soaking the pomegranate peel biochar in a NaOH solution, performing alkali modification under stirring conditions to obtain alkali-activated biochar, and dispersing the alkali-activated biochar in water to form an alkali-activated biochar dispersion.

[0033] It should be noted that pomegranate peel powder is prepared by grinding the pomegranate peel and then passing it through a 100-mesh sieve. Before grinding, the pomegranate peel is rinsed three times with distilled water to remove impurities and then dried in a 50°C oven until it is completely dry. After alkaline modification, the modified solution undergoes solid-liquid separation to obtain a solid product. The solid product is then filtered and washed until the solution is neutral, dried in an oven at 105°C until it is completely dry, and further ground in a mortar. Alkaline modification of biochar removes surface hydrophilic groups, modulates surface chemistry and pore structure, reduces polarity, and enhances binding capacity.

[0034] In some embodiments, during the hydrothermal reaction, the mass volume ratio of pomegranate peel powder to water is 1 g:8 mL to 12 mL, and the hydrothermal reaction time is 8 h to 10 h.

[0035] In some embodiments, the concentration of the NaOH solution is 1 mol·L -1 ~2 mol·L -1 The alkali modification time is 2h~3h.

[0036] On the other hand, the present invention provides a biochar-modified melamine foam material, which is prepared by the above-mentioned method for preparing the biochar-modified melamine foam material.

[0037] Biochar-modified melamine foam material has excellent superhydrophobicity and superoleophilicity, and its contact angle can reach 175°. When the biochar-modified melamine foam material comes into contact with water, due to the rough structure on the surface of the biochar-modified melamine foam material and the surface energy is further reduced after being coated with hexadecane, it is difficult for water to wet these structures and cannot enter the grid structure of the material, ultimately achieving the hydrophobic and oleophilic effects, easily realizing the oil-water separation of the oil-water mixture, and relying on the huge spatial structure inside the grid to store the separated oil, and finally transporting the adsorbed oil out of the oil-water mixture system.

[0038] The following is further described through specific examples.

[0039] Example 1 A method for preparing a biochar-modified melamine foam material comprises the following steps: S1. Use pomegranate peel as raw material, rinse it three times with distilled water to remove impurities, dry it in a 50℃ oven for 4 h, dry it until there is no moisture inside, then crush it and pass it through a 100-mesh sieve to obtain pomegranate peel powder; weigh 5.0 g of pomegranate peel powder, add it to a beaker filled with 50 mL of deionized water, and stir it ultrasonically for 30 min; pour 40 mL of the mixture into a hydrothermal synthesis reactor with a polytetrafluoroethylene liner, seal the hydrothermal reactor, and carry out hydrothermal reaction at 200℃ for 8 h; after the hydrothermal reaction is completed, obtain the reaction solution, centrifuge the reaction solution to separate the solid product, and wash it with distilled water; place the solid product in an oven and dry it to constant weight. The oven temperature is set to 105℃ to obtain pomegranate peel biochar.

[0040] S2, soak the pomegranate peel biochar in 1 mol·L -1 The mixture was placed in a NaOH solution and stirred at a constant temperature for 2 h to obtain an alkali-modified solution. The alkali-modified solution was subjected to solid-liquid separation to obtain a solid product. The solid product was filtered and washed until the solution was neutral, and then dried in an oven at 105°C until there was no moisture inside. The solid product was further ground in a mortar to obtain alkali-activated biochar. Water was added to the alkali-activated biochar, and ultrasonic treatment was performed for 60 min to fully disperse the biochar in the water to obtain an alkali-activated biochar dispersion. The concentration of the alkali-activated biochar dispersion was 7 mg·mL -1 .

[0041] S3. Cut melamine foam (MF) into blocks of 1 cm × 1 cm × 1 cm, ultrasonically clean them with anhydrous ethanol and deionized water for 3 h, and dry them in an oven at 40 °C. Then, add 30 mL of biochar alkali-activated biochar dispersion and ultrasonically treat them for 40 min to allow the biochar to fully diffuse into the MF grid structure to form a precursor.

[0042] S4. Add 3 mL of hexadecane to the precursor to activate the carboxyl groups on the biochar surface. After constant temperature stirring for 12 hours, add 0.192 g of dopamine hydrochloride and adjust the solution pH to approximately 8.5. Allow to react for 24 hours. Remove the precursor and squeeze out the air and liquid inside the MF. Finally, dry it to obtain a biochar-modified melamine foam material, named PSB@MF.

[0043] Example 2 A method for preparing a biochar-modified melamine foam material comprises the following steps: S1. Use pomegranate peel as raw material, rinse it three times with distilled water to remove impurities, dry it in a 50℃ oven for 4 h, dry it until there is no moisture inside, then crush it and pass it through a 100-mesh sieve to obtain pomegranate peel powder; weigh 5.0 g of pomegranate peel powder, add it to a beaker filled with 50 mL of deionized water, and stir it ultrasonically for 30 min; pour 40 mL of the mixture into a hydrothermal synthesis reactor with a polytetrafluoroethylene liner, seal the hydrothermal reactor, and carry out hydrothermal reaction at 200℃ for 8 h; after the hydrothermal reaction is completed, obtain the reaction solution, centrifuge the reaction solution to separate the solid product, and wash it with distilled water; place the solid product in an oven and dry it to constant weight. The oven temperature is set to 105℃ to obtain pomegranate peel biochar.

[0044] S2, soak the pomegranate peel biochar in 1 mol·L -1 The mixture was placed in a NaOH solution and stirred at a constant temperature for 2 h to obtain an alkali-modified solution. The alkali-modified solution was subjected to solid-liquid separation to obtain a solid product. The solid product was filtered and washed until the solution was neutral, and then dried in an oven at 105 °C until there was no moisture inside. The solid product was further ground in a mortar to obtain alkali-activated biochar. Water was added to the alkali-activated biochar, and ultrasonic treatment was performed for 60 min to fully disperse the biochar in the water to obtain an alkali-activated biochar dispersion. The concentration of the alkali-activated biochar dispersion was 5 mg·mL -1 .

[0045] S3. Cut melamine foam (MF) into blocks of 1 cm × 1 cm × 1 cm, ultrasonically clean them with anhydrous ethanol and deionized water for 3 h, and dry them in an oven at 40 °C. Then, add 30 mL of biochar alkali-activated biochar dispersion and ultrasonically treat them for 40 min to allow the biochar to fully diffuse into the MF grid structure to form a precursor.

[0046] S4. Add 3 mL of hexadecane to the precursor to activate the carboxyl groups on the biochar surface. After constant temperature stirring for 12 hours, add 0.192 g of dopamine hydrochloride and adjust the solution pH to approximately 8.5. Allow to react for 24 hours. Remove the precursor and squeeze out the air and liquid inside the MF. Finally, dry it to obtain a biochar-modified melamine foam material, named PSB@MF.

[0047] Example 3 A method for preparing a biochar-modified melamine foam material comprises the following steps: S1. Use pomegranate peel as raw material, rinse it three times with distilled water to remove impurities, dry it in a 50℃ oven for 4 h, dry it until there is no moisture inside, then crush it and pass it through a 100-mesh sieve to obtain pomegranate peel powder; weigh 5.0 g of pomegranate peel powder, add it to a beaker filled with 50 mL of deionized water, and stir it ultrasonically for 30 min; pour 40 mL of the mixture into a hydrothermal synthesis reactor with a polytetrafluoroethylene liner, seal the hydrothermal reactor, and carry out hydrothermal reaction at 200℃ for 8 h; after the hydrothermal reaction is completed, obtain the reaction solution, centrifuge the reaction solution to separate the solid product, and wash it with distilled water; place the solid product in an oven and dry it to constant weight. The oven temperature is set to 105℃ to obtain pomegranate peel biochar.

[0048] S2, soak the pomegranate peel biochar in 1 mol·L -1 The mixture was placed in a NaOH solution and stirred at a constant temperature for 2 h to obtain an alkali-modified solution. The alkali-modified solution was subjected to solid-liquid separation to obtain a solid product. The solid product was filtered and washed until the solution was neutral, and then dried in an oven at 105 °C until there was no moisture inside. The solid product was further ground in a mortar to obtain alkali-activated biochar. Water was added to the alkali-activated biochar, and ultrasonic treatment was performed for 60 min to fully disperse the biochar in the water to obtain an alkali-activated biochar dispersion. The concentration of the alkali-activated biochar dispersion was 3 mg·mL -1 .

[0049] S3. Cut melamine foam (MF) into blocks of 1 cm × 1 cm × 1 cm, ultrasonically clean them with anhydrous ethanol and deionized water for 3 h, and dry them in an oven at 40 °C. Then, add 30 mL of biochar alkali-activated biochar dispersion and ultrasonically treat them for 40 min to allow the biochar to fully diffuse into the MF grid structure to form a precursor.

[0050] S4. Add 3 mL of hexadecane to the precursor to activate the carboxyl groups on the biochar surface. After constant temperature stirring for 12 hours, add 0.192 g of dopamine hydrochloride and adjust the solution pH to approximately 8.5. Allow to react for 24 hours. Remove the precursor and squeeze out the air and liquid inside the MF. Finally, dry it to obtain a biochar-modified melamine foam material, named PSB@MF.

[0051] The results of the biochar-modified melamine foam material PSB@MF prepared in Examples 1 to 3 were tested.

[0052] Figure 1 This is a scanning electron microscope image of PSB@MF prepared in Example 1 of the present invention. Figure 1 As shown in the figure, the PSB@MF material forms micron-scale and nano-scale rough structures. These rough structures and the hydrophobic functional groups on the biochar surface can provide the material with excellent oil absorption capacity.

[0053] Figure 2 The hydrophobic performance diagram of PSB@MF prepared in Examples 1 to 3 of the present invention is shown in FIG. Figure 2 As shown in Figure 2, when the concentration of alkali-activated biochar dispersion is 7 mg·mL -1 The biochar-modified melamine foam material has excellent superhydrophobicity and superoleophilicity, and its contact angle can reach 175°. When the biochar-modified melamine foam material comes into contact with water, due to the rough structure on the surface of the biochar-modified melamine foam material, and the surface energy is further reduced after being coated with hexadecane, it is difficult for water to wet these structures and cannot enter the grid structure of the material, ultimately achieving a hydrophobic and oleophilic effect.

[0054] The biochar-modified melamine foams prepared in Examples 1 to 3 were used as adsorbents for oil-water separation. 10 mL of each organic solvent (dimethyl sulfoxide, N,N-dimethylformamide, epichlorohydrin, isopropyl alcohol, triethylamine, carbon tetrachloride, tetraethyl orthosilicate, xylene, gasoline, and vegetable oil) was mixed with 5 mL of deionized water to prepare different oil-water mixed solutions. The mass of the PSB@MF was measured before adsorption. The PSB@MF was immersed in the oil-water mixed solution and squeezed to remove the air. After adsorption for 1 minute, the PSB@MF was removed and weighed after adsorption. The mass change before and after adsorption was calculated, and the adsorption capacity was used to characterize the adsorption performance of the material.

[0055] The adsorption capacity of the material Q (g g -1 )Calculation formula: .

[0056] and are the masses of the self-repairing hydrophobic foam before and after adsorption, respectively.

[0057] Table 1 Adsorption capacity of PSB@MF for ten different organic solvents Figure 3 Adsorption capacity of PSB@MF for ten oils and organic solvents of different properties in Example 1 of the present invention. Figure 3 In the chart, the horizontal axis 1 is DMSO, 2 is DMF, 3 is ECH, 4 is IPA, 5 is TEA, 6 is CCl4, 7 is TEOS, 8 is xylene, 9 is gasoline, and 10 is vegetable oil. Figure 3 As shown, PSB@MF has a high adsorption capacity for DMF, CCl4, and TEOS. This is due to the extremely high porosity of PSB@MF and the capillary effect formed between the 3D grid structure and the organic solvent. The greater the viscosity of the oil, the stronger the intermolecular forces. During the adsorption process, the oil and organic solvent filled in the 3D grid structure can restrain the oil and organic solvent outside the grid structure through strong intermolecular forces. During the separation process, the oil and organic solvent in the grid structure will carry some of the oil and organic solvent outside the grid structure and separate it from the oil-water mixture system, ultimately achieving efficient oil-water separation.

[0058] Hydrophobic and oleophilic melamine foam has a wide range of applications, including oil-water separation and environmental treatment, as well as building sound insulation and thermal insulation. Its broad application has brought more business opportunities and economic benefits to related industries. The research and development and production of this foam material has also promoted the upgrading and development of related industries and driven the coordinated development of upstream and downstream enterprises in the industry chain. As an environmentally friendly material, this hydrophobic and oleophilic melamine foam is recyclable and reusable, meeting current societal requirements for environmental protection and sustainable development. Its application not only helps reduce environmental pollution but also promotes the development of a circular economy, bringing long-term economic and social benefits.

[0059] The above description is merely a preferred embodiment of the present invention, and the above specific embodiment is not intended to limit the present invention. Various variations and modifications are possible within the technical scope of the present invention. Any modifications, alterations, or equivalent substitutions made by a person skilled in the art based on the above description are within the scope of protection of the present invention.

Claims

1. A method for preparing a biochar-modified melamine foam material, characterized in that: The following steps are involved: Melamine foam is used as a matrix, an alkali-activated biochar dispersion is added to the matrix, and the alkali-activated biochar is loaded through the matrix to form a precursor; Hexadecane and dopamine hydrochloride are sequentially added to the precursor, and the alkali-activated biochar is activated and modified by the hexadecane and dopamine hydrochloride using an impregnation method to obtain a biochar-modified melamine foam material.

2. The method for preparing the biochar-modified melamine foam material according to claim 1, wherein: During the loading process, 25 mL to 35 mL of alkali-activated biochar dispersion was added to 1 cm × 1 cm × 1 cm melamine foam. The concentration of the alkali-activated biochar dispersion was 3 mg mL -1 ~7 mg·mL -1 .

3. The method for preparing the biochar-modified melamine foam material according to claim 1, wherein: The volume ratio of hexadecane to alkali-activated biochar dispersion is 3:25-35.

4. The method for preparing the biochar-modified melamine foam material according to claim 1, wherein: The mass volume ratio of dopamine hydrochloride and alkali-activated biochar dispersion is 0.15 g~0.2 g:30 mL.

5. The method for preparing the biochar-modified melamine foam material according to claim 1, wherein: During the activation modification process, hexadecane was first added to the precursor and stirred for activation for 10 to 14 hours. Then, dopamine hydrochloride was added and the pH was adjusted to 8 to 9, and the activation modification was carried out for 24 hours.

6. The method for preparing the biochar-modified melamine foam material according to claim 1, wherein: The method for preparing the alkali-activated biochar dispersion comprises the following steps: Pomegranate peel biochar was prepared by hydrothermal reaction at 200 ℃ using pomegranate peel powder as raw material. The pomegranate peel biochar was soaked in a NaOH solution and subjected to alkali modification under stirring conditions to obtain alkali-activated biochar, which was then dispersed in water to form an alkali-activated biochar dispersion.

7. The method for preparing the biochar-modified melamine foam material according to claim 6, wherein: During the hydrothermal reaction, the mass volume ratio of pomegranate peel powder to water is 1 g:8 mL~12 mL, and the hydrothermal reaction time is 8 h~10 h.

8. The method for preparing the biochar-modified melamine foam material according to claim 6, wherein: The concentration of NaOH solution is 1 mol·L -1 ~2 mol·L -1 The alkali modification time is 2 h to 3 h.

9. A biochar-modified melamine foam material, characterized in that: The biochar-modified melamine foam is prepared by the preparation method of the biochar-modified melamine foam material according to any one of claims 1 to 8.

10. Use of the biochar-modified melamine foam material according to claim 9 as an adsorption material in oil-water separation.

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