Nitrogen-doped porous carbon as well as preparation method and application thereof
By leveraging the synergistic effect of biomass, melamine, and metal activators, nitrogen-doped porous carbon materials were prepared, solving the problem of pore structure collapse during the pyrolysis of biomass carbon and achieving highly efficient heavy metal ion adsorption.
Patent Information
- Application Number
- CN202511328109.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2025-12-09
AI Technical Summary
Existing biomass carbon produces tar-like substances and amorphous carbon during pyrolysis, which hinders the formation of pore structures, resulting in a reduction in specific surface area and failing to meet the requirements for large-capacity heavy metal ion adsorption.
By mixing biomass, melamine, and metal activators in a specific ratio, and then subjecting the mixture to high-temperature carbonization and acid etching, nitrogen-doped porous carbon materials are prepared, thereby enhancing their specific surface area and heavy metal ion adsorption capacity.
The prepared nitrogen-doped porous carbon material has a good specific surface area and heavy metal ion adsorption capacity, and can effectively adsorb heavy metal ions in water.
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Figure CN121085272A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of inorganic non-metallic materials, and in particular to a nitrogen-doped porous carbon, its preparation method, and its uses. Background Technology
[0002] With the continuous advancement of human industrialization, industrial production generates a large amount of inadequately treated industrial wastewater. Heavy metal ions, carried by this wastewater, enter lakes and oceans, and subsequently, through bioaccumulation and the food chain, ultimately enter the human body. This poses a significant threat to the natural environment and human health. Therefore, the remediation of heavy metal pollution in water bodies has become a current research hotspot.
[0003] Heavy metal ions are difficult to degrade and highly toxic. Currently, heavy metal ions in wastewater are mainly treated through physical adsorption. Biochar, however, has attracted much attention due to its unique surface structure, economic efficiency, environmental friendliness, simple processing, and ability to efficiently adsorb heavy metal pollutants from water bodies.
[0004] Biomass carbon typically has a high carbon content, well-developed pore structure, and abundant surface functional groups, and has been widely used in energy and environmental fields, including pollutant adsorption. However, during pyrolysis, it produces a large amount of tar-like substances and amorphous carbon, which hinders the formation of pore structures and reduces specific surface area. Consequently, its adsorption capacity for heavy metals such as copper and cadmium is generally low, failing to meet the requirements for high-capacity adsorption in porous structures. Therefore, doping with nitrogen atoms can not only improve its surface chemical properties, thus obtaining unique and excellent physicochemical properties, but also increase its specific surface area and enhance its adsorption effect on heavy metal ions in water. Therefore, modifying biomass carbon to improve its performance is an urgent problem to be solved.
[0005] The problem this solution aims to solve is: how to provide a nitrogen-doped porous carbon material that differs from existing technologies. Summary of the Invention
[0006] The purpose of this application is to provide a nitrogen-doped porous carbon material. The nitrogen-doped porous carbon material is obtained by the combined action of various biomass, melamine, and metal activators, followed by high-temperature carbonization and acid etching. The porous carbon material prepared in this application has a good specific surface area and good heavy metal ion adsorption capacity in practical applications.
[0007] To achieve the above objectives, this application discloses a method for preparing nitrogen-doped porous carbon, which involves mixing biomass, melamine, and a metal activator in a mass ratio of 3:1 to 2:3 to 5 and immersing the mixture in pure water for 12 to 24 hours, followed by freeze drying, high-temperature carbonization, acid etching, and cleaning to obtain nitrogen-doped porous carbon. The biomass is selected from at least one of bamboo powder, sugarcane bagasse, and straw; The metal activator is selected from at least one of sodium carbonate, potassium carbonate, calcium carbonate, zinc carbonate, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, iron carbonate, zinc chloride, zinc oxide, zinc acetate, sodium acetate, potassium acetate, or calcium acetate.
[0008] Preferably, the metal activator is selected from at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium acetate, and potassium acetate.
[0009] Preferably, the biomass includes large-particle-size biomass and small-particle-size biomass, wherein the particle size of the large-particle-size biomass is 25-35 mesh; The particle size of the small-diameter biomass is 60-70 mesh; The mass ratio of large-particle-size biomass to small-particle-size biomass is 8–10:1.
[0010] Preferably, the biomass includes at least bamboo powder, and the bamboo powder has a particle size of 60-70 mesh.
[0011] Preferably, the small-particle-size biomass is bamboo powder, and the particle size of the bamboo powder is 60-70 mesh; The large-particle-size biomass is sugarcane bagasse and / or straw, and the particle size of the large-particle-size biomass is 25-35 mesh.
[0012] Preferably, the acid etching solution used in the acid etching process is selected from aqueous solutions of hydrochloric acid, sulfuric acid, or acetic acid.
[0013] Preferably, the acid etching solution is a mixed acid solution of hydrochloric acid and acetic acid, and the concentration of hydrochloric acid in the mixed acid solution is 0.1-1 mol / L and the concentration of acetic acid is 0.1-1 mol / L.
[0014] In addition, this application also discloses a nitrogen-doped porous carbon, which is prepared using the above-described method for preparing nitrogen-doped porous carbon.
[0015] In addition, this application also discloses the use of nitrogen-doped porous carbon as described above in the preparation of metal ion adsorbents.
[0016] In addition, this application also discloses the use of nitrogen-doped porous carbon as described above in the preparation of water purification agents.
[0017] The beneficial effects of this application are: The nitrogen-doped porous carbon material provided in this application is obtained by the combined action of various biomass and melamine, metal activators, and high-temperature carbonization and acid etching. The porous carbon material prepared in this application has a good specific surface area and good heavy metal ion adsorption capacity in practical applications. Attached Figure Description
[0018] Figure 1The figures show the nitrogen adsorption-desorption curves and pore size distribution of the nitrogen-doped porous carbon material prepared in Example 1. Figure 2 The nitrogen adsorption-desorption curves and pore size distribution diagrams of the nitrogen-doped porous carbon material prepared in Example 6 are shown. Figure 3 The nitrogen adsorption-desorption curves and pore size distribution diagrams of the nitrogen-doped porous carbon material prepared in Comparative Example 1 are shown. Detailed Implementation
[0019] The present application will be clearly and completely described below with reference to its embodiments. It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0020] Before demonstrating the embodiments, the preparation and acquisition methods of the raw materials involved in the embodiments shall be explained as follows: The bamboo was purchased from Fuzhou Sizhu Bamboo and Wood Industry Co., Ltd. Melamine was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Potassium carbonate was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. The sugarcane was purchased from Shantou Pumpkin Cart Food Co., Ltd. The straw was purchased from Rongen Technology Co., Ltd. in Lingshou County. Crush the bamboo, sugarcane, and straw separately and sieve them for later use.
[0021] Example 1 Bamboo powder (particle size 65±5 mesh), melamine and potassium carbonate were weighed in a mass ratio of 3:1:3 and soaked in an aqueous solution for 12 hours. The soaked mixture was freeze-dried and then pyrolyzed at 700℃ under a nitrogen atmosphere (nitrogen flow rate 0.1 L / min) at a heating rate of 10℃ / min for 2 hours to obtain the pyrolysis product. The pyrolysis product was then first acid-washed with 0.3mol / L hydrochloric acid and then washed with ultrapure water to obtain nitrogen-doped porous carbon.
[0022] Example 2 Bamboo powder (particle size 30±5 mesh), melamine and potassium carbonate were weighed in a mass ratio of 3:1.5:4 and soaked in an aqueous solution for 24 hours. The soaked mixture was freeze-dried and then pyrolyzed at 650°C under a nitrogen atmosphere (nitrogen flow rate 0.05 L / min) at a heating rate of 8°C / min for 1.5 hours to obtain the pyrolysis product. The pyrolysis product was then first acid-washed with 0.1 mol / L hydrochloric acid and then washed with ultrapure water to obtain nitrogen-doped porous carbon.
[0023] Example 3 Bamboo powder (particle size 45±5 mesh), melamine and potassium carbonate were weighed in a mass ratio of 3:2:5 and soaked in an aqueous solution for 16 hours. The soaked mixture was freeze-dried and then pyrolyzed at 750°C under a nitrogen atmosphere (nitrogen flow rate 0.15 L / min) at a heating rate of 5°C / min for 3 hours to obtain the pyrolysis product. The pyrolysis product was then first acid-washed with 1 mol / L hydrochloric acid and then washed with ultrapure water to obtain nitrogen-doped porous carbon.
[0024] Example 4 The method is basically the same as in Example 1, except that a mixture of sodium carbonate and potassium acetate of the same mass is used instead of potassium carbonate, and the mass ratio of sodium carbonate to potassium acetate in the mixture is 1:1.
[0025] Example 5 The method is basically the same as in Example 1, except that a mixture of sodium carbonate and zinc acetate of the same mass is used instead of potassium carbonate, and the mass ratio of sodium carbonate to zinc acetate in the mixture is 1:1.
[0026] Example 6 The method is basically the same as in Example 1, except that a mixture of sodium carbonate, potassium acetate and potassium carbonate of the same mass is used to replace potassium carbonate, and the mass ratio of sodium carbonate, potassium acetate and potassium carbonate in the mixture is 1:1:2.
[0027] Example 7 The method is basically the same as in Example 1, except that the same mass of bagasse (particle size 65±5 mesh) is used instead of bamboo powder.
[0028] Example 8 The method is basically the same as in Example 1, except that a mixture of bamboo powder (particle size 65±5 mesh) and sugarcane bagasse (particle size 65±5 mesh) of the same mass is used to replace the bamboo powder, and the mass ratio of bamboo powder to sugarcane bagasse is 1:9.
[0029] Example 9 The method is basically the same as in Example 1, except that a mixture of bamboo powder (particle size 65±5 mesh) and sugarcane bagasse (particle size 30±5 mesh) of the same mass is used to replace the bamboo powder, and the mass ratio of bamboo powder to sugarcane bagasse is 1:9.
[0030] Example 10 The method is basically the same as in Example 1, except that a mixture of bamboo powder (particle size 30±5 mesh) and sugarcane bagasse (particle size 65±5 mesh) of the same mass is used to replace the bamboo powder, and the mass ratio of bamboo powder to sugarcane bagasse is 1:9.
[0031] Example 11 The method is basically the same as in Example 1, except that an aqueous solution of acetic acid is used instead of hydrochloric acid solution, and the mass of acetic acid in the aqueous solution of acetic acid is 0.3 mol / L.
[0032] Example 12 The method is basically the same as in Example 1, except that a mixed aqueous solution of hydrochloric acid and acetic acid is used instead of the hydrochloric acid solution, and the mass of acetic acid in the solution is 0.15 mol / L and the mass of hydrochloric acid is 0.15 mol / L.
[0033] Example 13 The method is basically the same as in Example 8, except that a mixed aqueous solution of hydrochloric acid and acetic acid is used instead of the hydrochloric acid solution, and the mass of acetic acid in the solution is 0.15 mol / L and the mass of hydrochloric acid is 0.15 mol / L.
[0034] Example 14 The method is basically the same as in Example 9, except that a mixed aqueous solution of hydrochloric acid and acetic acid is used instead of the hydrochloric acid solution, and the mass of acetic acid in the solution is 0.15 mol / L and the mass of hydrochloric acid is 0.15 mol / L.
[0035] Comparative Example 1 Bamboo powder (particle size 65±5 mesh) and potassium carbonate were weighed at a mass ratio of 3:3 and soaked in an aqueous solution for 12 hours. The soaked mixture was freeze-dried and then pyrolyzed at 700℃ under a nitrogen atmosphere (nitrogen flow rate 0.1 L / min) at a heating rate of 10℃ / min for 2 hours to obtain the pyrolysis product. The pyrolysis product was then first acid-washed with 0.3mol / L hydrochloric acid and then washed with ultrapure water to obtain nitrogen-doped porous carbon.
[0036] Comparative Example 2 Bamboo powder (particle size 65±5 mesh) and melamine were weighed at a mass ratio of 3:1 and soaked in an aqueous solution for 12 hours. The soaked mixture was freeze-dried and then pyrolyzed at 700℃ under a nitrogen atmosphere (nitrogen flow rate 0.1 L / min) at a heating rate of 10℃ / min for 2 hours to obtain the pyrolysis product. The pyrolysis product was then first acid-washed with 0.3mol / L hydrochloric acid and then washed with ultrapure water to obtain nitrogen-doped porous carbon.
[0037] Performance testing: Adsorption experiment: Prepare a 100 mg / L Pb solution using lead nitrate. 2+ For the stock solution, weigh 10 mg of porous carbon and add 40 mL of 100 mg / L Pb. 2+The solution was placed in a constant temperature shaker at 25℃ / 120 rpm for 24 h. The solution was then filtered through a 0.45 μm aqueous syringe filter, and the Pb content in the filtrate was determined by ICP-OES. 2+ concentration.
[0038] The nitrogen adsorption and desorption isotherms of the samples were tested using a fully automated specific surface area and porosity analyzer (Quantachrome Autosorb IQ3), and the specific surface area data of the samples were calculated using methods such as the BET method and the BJH method. Test conditions: nitrogen adsorption (77K), degassing temperature 300℃, degassing for 6 h.
[0039] The test results are shown in Table 1: Table 1: Test Results Table
[0040] Results analysis: As can be seen from Examples 1-3, when the process parameters in the preparation of porous carbon are adjusted slightly, the specific surface area and lead ion adsorption capacity of Examples 1-3 show a certain fluctuation trend, but the fluctuation range is relatively small. Further observation of Examples 4-5 reveals that, after changing the metal activator, the specific surface area and metal ion adsorption capacity of the porous carbon prepared in Examples 4-5 showed a certain degree of decrease compared to Example 1. This may be because the activation capacity of Examples 4-5 is relatively weaker than that of Example 1. However, further observation of Example 6 shows that, after using the mixed metal activator of potassium carbonate, sodium carbonate, and potassium acetate used in Examples 1 and 4, the specific surface area of Example 6 increased, and its metal ion adsorption capacity also showed a certain degree of increase. Moreover, the specific surface area of Example 6 exceeded that of either Example 1 or Example 4. This suggests that there may be a synergistic effect between potassium carbonate, sodium carbonate, and potassium acetate to increase the specific surface area of the porous carbon and thus enhance its metal ion adsorption capacity. Further observation of Example 7 shows that when sugarcane bagasse was used to replace bamboo powder, the specific surface area and metal ion adsorption capacity of Example 7 showed a certain downward trend. However, further observation of Examples 8-10 shows that when Examples 8-10 used a mixed biomass material of bamboo powder and sugarcane compared to Example 7, the specific surface area of Examples 9-10 showed a relatively significant upward trend compared to Example 7. Even more surprisingly, the metal ion adsorption capacity of Examples 9-10 also increased significantly. It is speculated that the reason may be that the larger initial particle size of sugarcane is more conducive to the production of activated carbon with a large specific surface area. Further observation of Examples 11-14 reveals that, firstly, when acetic acid was used to replace hydrochloric acid in Example 11, the specific surface area and metal ion adsorption capacity of Example 11 decreased instead of increasing. However, further observation of Examples 12-14 shows that after acid washing with a mixture of hydrochloric acid and acetic acid, Examples 12-13 showed different degrees of improvement compared to Examples 1 and 8, while Example 14 showed a more obvious improvement compared to Example 9. It can be seen that the mixture of hydrochloric acid and acetic acid has a stronger ability to etch the biomass material and remove the metal activator used in Example 9. Finally, observation of Comparative Examples 1 and 2 shows that when either melamine or metal activator is missing in Comparative Examples 1 and 2, the specific surface area and metal ion adsorption capacity of Comparative Examples 1 and 2 show a significant decreasing trend compared to Example 1. This indicates that the two raw materials mentioned above are indispensable. Furthermore, if biomass, the core material for generating biochar, is missing during the preparation of porous carbon, it is undoubtedly impossible to obtain porous carbon materials.
[0041] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.
Claims
1. A method for preparing nitrogen-doped porous carbon, characterized in that, Biomass, melamine, and metal activator were mixed in a mass ratio of 3:1 to 2:3 to 5 and immersed in pure water for 12 to 24 hours. Then, the mixture was freeze-dried, carbonized at high temperature, acid etched, and cleaned to obtain nitrogen-doped porous carbon. The biomass is selected from at least one of bamboo powder, sugarcane bagasse, and straw; The metal activator is selected from at least one of sodium carbonate, potassium carbonate, calcium carbonate, zinc carbonate, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, iron carbonate, zinc chloride, zinc oxide, zinc acetate, sodium acetate, potassium acetate, or calcium acetate.
2. The method for preparing nitrogen-doped porous carbon according to claim 1, characterized in that, The metal activator is selected from at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium acetate, and potassium acetate.
3. The method for preparing nitrogen-doped porous carbon according to claim 1, characterized in that, The biomass includes large-particle-size biomass and small-particle-size biomass, wherein the particle size of the large-particle-size biomass is 25-35 mesh. The particle size of the small-diameter biomass is 60-70 mesh; The mass ratio of large-particle-size biomass to small-particle-size biomass is 8–10:
1.
4. The method for preparing nitrogen-doped porous carbon according to claim 1, characterized in that, The biomass includes at least bamboo powder, and the particle size of the bamboo powder is 60-70 mesh.
5. The method for preparing nitrogen-doped porous carbon according to claim 3, characterized in that, The small-particle-size biomass is bamboo powder, and the particle size of the bamboo powder is 60-70 mesh. The large-particle-size biomass is sugarcane bagasse and / or straw, and the particle size of the large-particle-size biomass is 25-35 mesh.
6. The method for preparing nitrogen-doped porous carbon according to claim 1, characterized in that, The acid etching solution used in the acid etching process is selected from aqueous solutions of hydrochloric acid, sulfuric acid, or acetic acid.
7. The method for preparing nitrogen-doped porous carbon according to claim 6, characterized in that, The acid etching solution is a mixed acid solution of hydrochloric acid and acetic acid, and the concentration of hydrochloric acid in the mixed acid solution is 0.1-1 mol / L and the concentration of acetic acid is 0.1-1 mol / L.
8. A nitrogen-doped porous carbon, characterized in that, It is prepared using the method for preparing nitrogen-doped porous carbon according to any one of claims 1 to 7.
9. The use of nitrogen-doped porous carbon as described in claim 8 for preparing metal ion adsorbents.
10. The use of nitrogen-doped porous carbon as described in claim 8 for preparing water purification agents.