Biomass-based activated carbon and method for preparing the same

Abstract

The application discloses a biomass-based activated carbon and a preparation method thereof, and belongs to the technical field of activated carbon materials. The biomass-based activated carbon is prepared from 7-8 parts of crop residues and 1.5-2.5 parts of dried sponge gourd core as carbon-based solid materials, and is prepared through the steps of soaking in an activated water solution, microwave hydrothermal treatment carbonization and twice physical activation treatment. The biomass-based activated carbon has the characteristics of higher specific surface area, more abundant pore structure and surface functional groups, and excellent adsorption capacity. In the whole preparation process, the production raw materials are green and safe, waste gas resources are reused, the environment is protected, and the corrosion of the raw materials to the production equipment is small. The biomass-based activated carbon is suitable for popularization and application in the fields of food processing and pharmaceutical manufacturing.

Description

Technical Field

[0001] This invention relates to a biomass-based activated carbon and its preparation method, belonging to the technical field of activated carbon materials. Background Technology

[0002] Activated carbon is prepared from carbon-containing raw materials such as wood, coal, and petroleum coke through pyrolysis and activation processing. It possesses a well-developed pore structure and a large specific surface area, making it suitable as both a purification material and an activated carbon carrier. It is widely used in environmental protection, food processing, pharmaceuticals, and chemical industries. For activated carbon applications in food processing and pharmaceuticals, the raw materials must be non-toxic and contain few impurities. Furthermore, the carbonization and activation processes must not introduce substances harmful to human health. Activation processes include physical and chemical activation. Physical activation uses oxidizing gases as activating agents, offering advantages such as being more environmentally friendly, safer, and reducing equipment wear; however, the activated carbon's performance is relatively low. Chemical activation uses chemical reagents such as phosphoric acid, zinc chloride, and potassium hydroxide as activating agents, resulting in higher activated carbon performance, but it presents problems such as secondary environmental pollution, poor safety of activating agent residues, and strong equipment corrosion. Therefore, there is a need to find a green, safe, and more active activated carbon and its preparation method to better suit the food processing and pharmaceutical industries. Summary of the Invention

[0003] To address at least one problem existing in the prior art, the present invention provides a biomass-based activated carbon and its preparation method. The biomass-based activated carbon has characteristics such as higher specific surface area, richer pore structure and surface functional groups, excellent adsorption capacity, green and safe raw materials in the entire preparation process, and reuse of waste gas resources, which is environmentally friendly. The raw materials have low corrosiveness to production equipment, making it suitable for promotion and application in the fields of food processing and pharmaceutical manufacturing.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a biomass-based activated carbon, which is prepared by using 7-8 parts of agricultural crop residue and 1.5-2.5 parts of dried loofah pulp as raw materials as carbon-based solid materials, and by soaking in an activated aqueous solution, carbonizing by microwave hydrothermal treatment, and undergoing two physical activation treatments.

[0005] Preferably, the crop residue is one or more of sugarcane residue, corn stalks, and corn cobs.

[0006] Preferably, ultrasonic-assisted soaking is also used during the soaking in the activated aqueous solution.

[0007] Preferably, the activated aqueous solution is an aqueous solution containing hydrogen peroxide and citric acid.

[0008] Preferably, in the activated aqueous solution, the mass ratio of water, hydrogen peroxide, and citric acid is 100:20-25:8-12.

[0009] Preferably, the mass ratio of the activated aqueous solution to the carbon-based solid material is 5 to 6:1.

[0010] Preferably, the two physical activation treatments consist of an initial activation with water vapor followed by a secondary activation by the combination of water vapor and carbon dioxide.

[0011] This invention also provides a method for preparing biomass-based activated carbon, comprising the following steps:

[0012] (1) Crush agricultural residues and dried loofah pulp to form carbon-based solid materials;

[0013] (2) The carbon-based solid material is immersed in an activated aqueous solution and ultrasonically treated, and then carbonized by microwave hydrothermal treatment under a nitrogen atmosphere to form an activated precursor material.

[0014] (3) The precursor material is first activated by steam, and then activated a second time by combining steam and carbon dioxide to form biomass-based activated carbon.

[0015] Preferably, the specific steps of the preparation method of the biomass-based activated carbon are as follows:

[0016] (1) First, mix and crush the crop residue and dried loofah pulp, then wash with water and vacuum dry to obtain carbon-based solid material;

[0017] (2) The carbon-based solid material is soaked in an activated aqueous solution, ultrasonically treated during soaking, and then carbonized by microwave hydrothermal treatment under a nitrogen atmosphere. The solid and liquid are separated and washed with water to obtain the activated precursor material.

[0018] (3) The precursor material is first activated in a steam atmosphere, then some steam is released and carbon dioxide is introduced to form a mixture of steam and carbon dioxide with a volume ratio of 15-25:75-85 for secondary activation. Then it is washed with water and vacuum dried to obtain biomass-based activated carbon.

[0019] Preferably, in step (2), the soaking time is 4 to 6 hours and the soaking temperature is 40 to 50°C.

[0020] Preferably, in step (2), the ultrasonic frequency is 30 to 40 kHz.

[0021] Preferably, in step (2), the microwave hydrothermal treatment conditions are as follows: at a microwave power of 2500-3000MHz, the temperature is increased to 180-200℃ at a rate of 5-10℃ / min and then held for 60-120min.

[0022] Preferably, in step (3), the initial activation conditions are: heating to 850-900°C at a rate of 10-15°C / min and holding at that temperature for 60-90min.

[0023] Preferably, in step (3), the conditions for secondary activation are: heating to 800-850°C at a rate of 2-5°C / min and holding at that temperature for 30-60min.

[0024] The beneficial effects of this invention are as follows: 1) This invention uses agricultural residues such as sugarcane residue, corn stalks, or corn cobs, along with dried loofah pulp, as biomass-based materials. Through hydrothermal treatment using hydrogen peroxide and citric acid as reaction media, the biomass-based activated carbon obtained through physical activation not only possesses a high specific surface area and excellent adsorption capacity but is also green and safe, suitable for food processing and pharmaceutical applications, and enables the reuse of waste resources; 2) This invention uses dried loofah pulp as a component of the carbon-based solid material, which can promote the solubility of hydrogen peroxide and citric acid in the carbon-based solid material, thus benefiting the carbon-based solid material... The carbonization of raw materials and the activation of precursor materials are used to prepare biomass-based activated carbon with better performance; 3) In the preparation process of this invention, the process of ultrasonic-assisted soaking, microwave hydrothermal carbonization, steam primary activation, and steam and carbon dioxide combined secondary activation are coupled to improve the specific surface area, porosity and adsorption capacity of biomass-based activated carbon prepared by physical activation with gas activators; 4) The biomass-based activated carbon of this invention has higher specific surface area, richer pore structure and surface functional groups, and excellent adsorption capacity, and can be widely used in food processing and pharmaceutical fields. Detailed Implementation

[0025] The following is a clear and complete description of the technical solutions in the implementation of this invention. The described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents, instruments, or components used that do not specify the manufacturer are all conventional products that can be purchased commercially.

[0026] Example 1

[0027] A biomass-based activated carbon and its preparation method, the specific steps of which are as follows:

[0028] (1) First, mix and crush 7.5 parts of sugarcane residue and 2 parts of dried loofah pulp until they can pass through a 50-mesh sieve. Then wash with deionized water and vacuum dry at 65°C until constant weight to obtain carbon-based solid material.

[0029] (2) The carbon-based solid material was soaked in 52 parts of an activated aqueous solution composed of water, hydrogen peroxide and citric acid in a mass ratio of 100:22:10. The soaking temperature was 45℃ and the soaking time was 5h. During the soaking, the material was ultrasonically treated at a frequency of 35kHz. Then, it was carbonized by microwave hydrothermal treatment under a nitrogen atmosphere. The temperature was raised to 190℃ at a rate of 7.5℃ / min under a microwave power of 2800MHz and held for 90min. The solid and liquid were separated to remove the liquid. The material was then washed twice with deionized water to obtain the activated precursor material.

[0030] (3) The precursor material is first activated in a steam atmosphere, heated to 880°C at a rate of 12.5°C / min and held for 75 min. Then, some steam is released and carbon dioxide is introduced to form a mixture of steam and carbon dioxide in a volume ratio of 20:80. The material is then activated a second time, heated to 820°C at a rate of 3.5°C / min and held for 45 min. The material is then washed three times with deionized water and then vacuum dried at 65°C until constant weight is obtained to obtain biomass-based activated carbon.

[0031] Example 2

[0032] A biomass-based activated carbon and its preparation method, the specific steps of which are as follows:

[0033] (1) First, mix and crush 7 parts of corn stalks and 1.5 parts of dried loofah pulp until they can pass through a 40-mesh sieve. Then wash with deionized water and vacuum dry at 60°C until constant weight to obtain carbon-based solid material.

[0034] (2) The carbon-based solid material was soaked in 51 parts of an activated aqueous solution composed of water, hydrogen peroxide and citric acid in a mass ratio of 100:20:8. The soaking temperature was 40℃ and the soaking time was 6h. During the soaking, the material was ultrasonically treated at a frequency of 30kHz. Then, it was carbonized by microwave hydrothermal treatment under a nitrogen atmosphere. The temperature was increased to 200℃ at a rate of 5℃ / min under a microwave power of 2500MHz and held for 120min. The solid and liquid were separated to remove the liquid. The material was then washed twice with deionized water to obtain the activated precursor material.

[0035] (3) The precursor material is first activated in a steam atmosphere, heated to 850°C at a rate of 10°C / min and held for 90 min. Then, some steam is released and carbon dioxide is introduced to form a mixture of steam and carbon dioxide in a volume ratio of 15:75. The material is then activated a second time, heated to 800°C at a rate of 2°C / min and held for 60 min. The material is then washed three times with deionized water and then vacuum dried at 60°C until constant weight is obtained to obtain biomass-based activated carbon.

[0036] Example 3

[0037] A biomass-based activated carbon and its preparation method, the specific steps of which are as follows:

[0038] (1) First, mix and crush 4 parts of sugarcane residue, 4 parts of corn stalks and 2.5 parts of dried loofah pulp, so that they can pass through a 45-mesh sieve. Then wash with deionized water and vacuum dry at 70°C until constant weight to obtain carbon-based solid material.

[0039] (2) The carbon-based solid material was soaked in 52.5 parts of an activated aqueous solution composed of water, hydrogen peroxide and citric acid in a mass ratio of 100:25:12. The soaking temperature was 50℃ and the soaking time was 4h. During the soaking, the material was ultrasonically treated at a frequency of 40kHz. Then, it was carbonized by microwave hydrothermal treatment under a nitrogen atmosphere. The temperature was raised to 180℃ at a rate of 10℃ / min under a microwave power of 3000MHz and held for 60min. The solid and liquid were separated to remove the liquid. The material was then washed twice with deionized water to obtain the activated precursor material.

[0040] (3) The precursor material is first activated in a steam atmosphere, heated to 900°C at a rate of 15°C / min and held for 60 min. Then, some steam is released and carbon dioxide is introduced to form a mixture of steam and carbon dioxide in a volume ratio of 25:75. The material is then activated a second time, heated to 850°C at a rate of 5°C / min and held for 30 min. The material is then washed three times with deionized water and then vacuum dried at 70°C until constant weight is obtained to obtain biomass-based activated carbon.

[0041] Example 4

[0042] A biomass-based activated carbon and its preparation method, the specific steps of which are as follows:

[0043] (1) First, mix and crush 5 parts of sugarcane residue, 2 parts of corn cob and 2.5 parts of dried loofah pulp, so that they can pass through a 50-mesh sieve. Then wash with deionized water and vacuum dry at 70°C until constant weight to obtain carbon-based solid material.

[0044] (2) The carbon-based solid material was soaked in 52 parts of an activated aqueous solution composed of water, hydrogen peroxide and citric acid in a mass ratio of 100:20:12. The soaking temperature was 40℃ and the soaking time was 4h. During the soaking, the material was ultrasonically treated at a frequency of 30kHz. Then, it was carbonized by microwave hydrothermal treatment under a nitrogen atmosphere. The temperature was raised to 180℃ at a rate of 10℃ / min under a microwave power of 2500MHz and held for 60min. The solid and liquid were separated to remove the liquid. The material was then washed twice with deionized water to obtain the activated precursor material.

[0045] (3) The precursor material is first activated in a steam atmosphere, heated to 850°C at a rate of 15°C / min and held for 60 min. Then, some steam is released and carbon dioxide is introduced to form a mixture of steam and carbon dioxide in a volume ratio of 25:75. The material is then activated a second time, heated to 800°C at a rate of 5°C / min and held for 30 min. The material is then washed three times with deionized water and then vacuum dried at 70°C until constant weight is obtained to obtain biomass-based activated carbon.

[0046] Example 5

[0047] A biomass-based activated carbon and its preparation method, the specific steps of which are as follows:

[0048] (1) First, mix and crush 8 parts of sugarcane residue and 1.5 parts of dried loofah pulp until they can pass through a 50-mesh sieve. Then wash with deionized water and vacuum dry at 60°C until constant weight to obtain carbon-based solid material.

[0049] (2) The carbon-based solid material was soaked in 52 parts of an activated aqueous solution composed of water, hydrogen peroxide and citric acid in a mass ratio of 100:25:8. The soaking temperature was 50℃ and the soaking time was 6h. During the soaking, the material was ultrasonically treated at a frequency of 40kHz. Then, it was carbonized by microwave hydrothermal treatment under a nitrogen atmosphere. The temperature was raised to 200℃ at a rate of 5℃ / min under a microwave power of 3000MHz and held for 120min. The solid and liquid were separated to remove the liquid. The material was then washed twice with deionized water to obtain the activated precursor material.

[0050] (3) The precursor material is first activated in a steam atmosphere, heated to 900°C at a rate of 10°C / min and held for 90 min. Then, some steam is released and carbon dioxide is introduced to form a mixture of steam and carbon dioxide in a volume ratio of 15:75. The material is then activated a second time, heated to 850°C at a rate of 2°C / min and held for 60 min. The material is then washed three times with deionized water and then vacuum dried at 75°C until constant weight is obtained to obtain biomass-based activated carbon.

[0051] Comparative Example 1

[0052] A biomass-based activated carbon and its preparation method differ from Example 1 in that it does not contain dried loofah pulp, contains 9.5 parts of sugarcane residue, and is otherwise identical.

[0053] Comparative Example 2

[0054] A biomass-based activated carbon and its preparation method differ from Example 1 in that the activation aqueous solution is composed of water and hydrogen peroxide in a mass ratio of 100:22, while the rest are exactly the same.

[0055] Comparative Example 3

[0056] A biomass-based activated carbon and its preparation method differ from Example 1 in that the activation aqueous solution is composed of water and citric acid in a mass ratio of 100:10, while the rest are exactly the same.

[0057] Comparative Example 4

[0058] A biomass-based activated carbon and its preparation method differ from Example 1 in that: in step (2), ultrasonic treatment is not performed during soaking and microwave treatment is not performed during hydrothermal treatment, but the rest are exactly the same.

[0059] Comparative Example 5

[0060] A biomass-based activated carbon and its preparation method differ from Example 1 in that: in step (2), ultrasonic treatment is not performed during soaking; after soaking, the carbon is carbonized by ultrasonic hydrothermal treatment under a nitrogen atmosphere, and then carbonized by microwave hydrothermal treatment under a nitrogen atmosphere. The temperature is raised to 190°C at a rate of 7.5°C / min under an ultrasonic power of 35 kHz and held for 90 min. The solid and liquid are separated to remove the liquid, and then washed twice with deionized water to obtain the activated precursor material. The rest is exactly the same.

[0061] Comparative Example 6

[0062] A biomass-based activated carbon and its preparation method differ from Example 1 in that: in step (3), the activation precursor is first activated in a steam atmosphere, heated to 880°C at a rate of 12.5°C / min and kept at that temperature for 120 min, then washed three times with deionized water, and then vacuum dried at 65°C until constant weight is obtained to obtain biomass-based activated carbon. The rest is exactly the same.

[0063] Comparative Example 7

[0064] A biomass-based activated carbon and its preparation method differ from Example 1 in that: in step (3), the activation precursor is first activated in a carbon dioxide atmosphere, heated to 880°C at a rate of 12.5°C / min and kept at that temperature for 120 min, then washed three times with deionized water, and then vacuum dried at 65°C until constant weight is obtained to obtain biomass-based activated carbon. The rest is exactly the same.

[0065] Comparative Example 8

[0066] A biomass-based activated carbon and its preparation method differ from Example 1 in that: in step (3), the activation precursor is first activated in a mixed gas atmosphere of water vapor and carbon dioxide in a volume ratio of 20:80, heated to 880°C at a rate of 12.5°C / min and held for 120 min, then washed three times with deionized water, and then vacuum dried at 65°C until constant weight is obtained to obtain biomass-based activated carbon. The rest is exactly the same.

[0067] Comparative Example 9

[0068] A biomass-based activated carbon and its preparation method differ from Example 1 in that: in step (3), the activation precursor material is first activated in a steam atmosphere, heated to 880°C at a rate of 12.5°C / min and held for 75 min, then activated a second time in a carbon dioxide atmosphere, heated to 820°C at a rate of 3.5°C / min and held for 45 min, then washed three times with deionized water, and then vacuum dried at 65°C until constant weight is obtained to obtain biomass-based activated carbon. The rest is exactly the same.

[0069] Comparative Example 10

[0070] A biomass-based activated carbon and its preparation method differ from Example 1 in that: in step (3), the activation precursor is first activated in a carbon dioxide atmosphere, heated to 880°C at a rate of 12.5°C / min and held for 75 min, then some water vapor is released and carbon dioxide is introduced to achieve a mixed gas with a water vapor to carbon dioxide volume ratio of 20:80 for secondary activation, heated to 820°C at a rate of 3.5°C / min and held for 45 min, then washed three times with deionized water, and then vacuum dried at 65°C until constant weight is obtained to obtain biomass-based activated carbon. The rest is exactly the same.

[0071] Comparative Example 11

[0072] A biomass-based activated carbon and its preparation method, the specific steps of which are as follows:

[0073] (1) First, mix and crush 8 parts of sugarcane residue and 1.5 parts of dried loofah pulp until they can pass through a 50-mesh sieve. Then wash with deionized water and vacuum dry at 60°C until constant weight to obtain carbon-based solid material.

[0074] (2) The carbon-based solid material was heated to 750°C at a rate of 5°C / min under a nitrogen atmosphere and held for 120 min to obtain the activated precursor material.

[0075] (3) The activated precursor material was then soaked in 52 parts of an activated aqueous solution composed of water, hydrogen peroxide and citric acid in a mass ratio of 100:25:8. The soaking temperature was 50℃ and the soaking time was 6h. During soaking, the material was ultrasonically treated at a frequency of 40kHz to separate the solid and liquid and remove the liquid. The material was then activated for the first time in a water vapor atmosphere. The temperature was raised to 900℃ at a rate of 10℃ / min and held for 90min. Then, some water vapor was released and carbon dioxide was introduced to achieve a mixed gas with a water vapor and carbon dioxide volume ratio of 15:75. The material was then activated for the second time. The temperature was raised to 850℃ at a rate of 2℃ / min and held for 60min. The material was then washed three times with deionized water and then vacuum dried at 75℃ until constant weight was obtained to obtain biomass-based activated carbon.

[0076] Comparative Example 12

[0077] A biomass-based activated carbon and its preparation method, the specific steps of which are as follows:

[0078] (1) First, mix and crush 7.5 parts of sugarcane residue and 2 parts of dried loofah pulp until they can pass through a 50-mesh sieve. Then wash with deionized water and vacuum dry at 65°C until constant weight to obtain carbon-based solid material.

[0079] (2) The carbon-based solid material was soaked in 52 parts of an activated aqueous solution composed of water, hydrogen peroxide and citric acid in a mass ratio of 100:22:10. The soaking temperature was 45℃ and the soaking time was 5h. During the soaking, the material was ultrasonically treated at a frequency of 35kHz. Then, it was hydrothermally carbonized under a nitrogen atmosphere. The temperature was raised to 190℃ at a rate of 7.5℃ / min and held for 90min. The solid and liquid were separated to remove the liquid. The material was then washed twice with deionized water to obtain the activated precursor material.

[0080] (3) The precursor material was first microwave activated in a steam atmosphere. The temperature was raised to 880°C at a rate of 12.5°C / min at a microwave power of 2800MHz and held for 75min. Then, some steam was released and carbon dioxide was introduced to achieve a mixed gas with a volume ratio of 20:80 between steam and carbon dioxide. The material was then microwave activated a second time. The temperature was raised to 820°C at a rate of 3.5°C / min at a microwave power of 2800MHz and held for 45min. The material was then washed three times with deionized water and then vacuum dried at 65°C until constant weight was obtained to obtain biomass-based activated carbon.

[0081] Performance testing

[0082] The biomass-based activated carbon prepared in Examples 1-5 and Comparative Examples 1-12 were subjected to BET and iodine adsorption value tests. The BET test was performed using a fully automated specific surface area analyzer according to the GB212-2001 standard, and the iodine adsorption value was determined according to the standard GB / T12496.8-2015. The test results are shown in Table 1.

[0083] Table 1 Performance of Biomass-Based Activated Carbon

[0084]

[0085]

[0086] The data in Table 1 show that the biomass-based activated carbon prepared in Examples 1-5 of the present invention has a higher specific surface area, richer pore structure and surface functional groups, and excellent adsorption capacity. The raw materials used in the entire preparation process are green and safe, and waste gas resources can be reused, which is environmentally friendly. The raw materials have low corrosiveness to the production equipment and are suitable for promotion and application in the fields of food processing and pharmaceutical manufacturing.

[0087] Compared with Comparative Example 1, Examples 1-5 illustrate that adding dried loofah pulp to agricultural residues as a component of carbon-based solid materials can increase the solubility of hydrogen peroxide and citric acid in the carbon-based solid materials, providing more favorable conversion conditions for the carbonization of carbon-based solid materials and the activation of activation precursors, which helps to form a stable porous structure, thereby increasing the specific surface area and porosity of activated carbon and improving the specific surface area and adsorption effect of biomass-based activated carbon.

[0088] Compared with Comparative Examples 4 and 5, Examples 1 to 5 illustrate that: when carbon-based solid materials are soaked in an activation aqueous solution, ultrasonic assistance is used, and when hydrothermal treatment is performed, microwave synergy is used. This can optimize the internal structure of carbon-based materials, so as to obtain excellent pore structure and higher specific surface area during the activation process, and promote the bonding of its surface with more abundant functional groups, thereby improving its activity performance and also improving production efficiency.

[0089] Compared with Comparative Examples 6-10, Examples 1-5 illustrate that the coupled physical activation method of primary activation with water vapor and secondary activation with the combination of water vapor and carbon dioxide can generate a more developed pore structure and more abundant surface functional groups, thereby improving the specific surface area and adsorption effect of biomass-based activated carbon.

[0090] Compared with Comparative Examples 11 and 12, Examples 1 to 5 illustrate that soaking the carbon-based solid material in an activated aqueous solution and then performing hydrothermal carbonization followed by two physical activations—primary activation with steam and secondary activation with a combination of steam and carbon dioxide—is beneficial for the formation of a porous structure and increases the specific surface area and porosity of the activated carbon.

[0091] In summary, this invention uses agricultural residues such as sugarcane residue, corn stalks, or corn cobs, along with dried loofah pulp, as biomass-based materials. Hydrothermal carbonization is performed using hydrogen peroxide and citric acid as reaction media, with microwave synergy. This results in biomass-based activated carbon that possesses not only a high specific surface area and excellent adsorption capacity, but is also green and safe, making it suitable for food processing and pharmaceutical applications.

[0092] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit and essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0093] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A biomass-based activated carbon, characterized by, The material is prepared by using 7-8 parts of crop residue and 1.5-2.5 parts of dried loofah pulp as raw materials as carbon-based solids, and is obtained by soaking in activated aqueous solution, carbonization by microwave hydrothermal treatment, and two physical activation treatments. Ultrasonic assisted soaking is also used during the immersion in the activated aqueous solution; The two physical activation treatments consist of an initial activation with water vapor, followed by a secondary activation by the combination of water vapor and carbon dioxide. The activated aqueous solution is an aqueous solution containing hydrogen peroxide and citric acid.

2. The biomass-based activated carbon according to claim 1, characterized in that, In the activated aqueous solution, the mass ratio of water, hydrogen peroxide, and citric acid is 100:20~25:8~12.

3. The biomass-based activated carbon of claim 1, wherein, The mass ratio of the activated aqueous solution to the carbon-based solid material is 5~6:

1.

4. The biomass-based activated carbon of claim 1, wherein, The crop residue is one or more of sugarcane residue, corn stalks, and corn cobs.

5. A method of producing a biomass-based activated carbon according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Crush agricultural residues and dried loofah pulp to form carbon-based solids; (2) The carbon-based solid material is immersed in an activated aqueous solution and ultrasonically treated, and then carbonized by microwave hydrothermal treatment under a nitrogen atmosphere to form an activated precursor material. (3) The precursor material is first activated by steam, and then activated a second time by a combination of steam and carbon dioxide to form biomass-based activated carbon.

6. The method for preparing biomass-based activated carbon according to claim 5, characterized in that, In step (2), the soaking time is 4~6h, the soaking temperature is 40~50℃, and the ultrasonic frequency is 30~40kHz; Microwave hydrothermal treatment conditions: At a microwave power of 2500~3000MHz, the temperature is increased to 180~200℃ at a rate of 5~10℃ / min and then held for 60~120min.

7. The method for preparing biomass-based activated carbon according to claim 5, characterized in that, In step (3), the conditions for initial activation are: heating to 850-900℃ at a rate of 10-15℃ / min and holding for 60-90min; the conditions for secondary activation are: heating to 800-850℃ at a rate of 2-5℃ / min and holding for 30-60min.

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