Composite modified activated carbon and preparation method thereof

Abstract

The invention relates to the field of coal activated carbon, in particular to composite modified activated carbon and a preparation method thereof. The coal and the biomass material are selected to be compounded in the raw materials, the defects of the coal and the biomass material can be effectively overcome by adjusting the proportion of the coal and the biomass material, the coal serves as an activated carbon substrate, the biomass material is embedded in the coal, and activation is conducted through the activating agent, so that the finally obtained composite modified activated carbon has the high specific surface area and the good pore structure; the method is suitable for various environment restoration applications.

Description

Technical Field

[0001] The invention relates to the field of coal-based activated carbon, and in particular to a composite modified activated carbon and a preparation method thereof. Background Art

[0002] As an efficient and multifunctional adsorption material, activated carbon plays a vital role in environmental protection and industrial production, and is widely used in many key fields such as water treatment, air purification, and gas adsorption. Traditional activated carbon preparation mainly relies on natural resources such as coal, charcoal or coconut shells. Among them, coal, as one of the main raw materials for activated carbon, has the advantages of relatively stable sources and mature preparation processes. However, activated carbon prepared from pure coal often has limitations in specific surface area and pore structure, which limits its adsorption efficiency and application range. Specifically, the pore distribution of coal-activated carbon may not be uniform enough, and the room for improvement of specific surface area is limited, which makes it difficult to meet the growing environmental protection needs and the requirements of high-performance adsorption materials.

[0003] At the same time, biomass materials have received widespread attention in recent years as potential raw materials for the preparation of activated carbon. Biomass resources are abundant, low-cost, and highly renewable, which is in line with the concept of sustainable development. However, when biomass raw materials are used alone to prepare activated carbon, their adsorption performance is often low. This is mainly because the chemical composition and physical structure of biomass raw materials are relatively complex, and it is difficult to accurately control the pore structure and specific surface area during the preparation process, resulting in limited adsorption efficiency and selectivity of activated carbon. Faced with these challenges, researchers are constantly exploring new preparation methods and modification technologies to improve the performance of activated carbon.

[0004] Therefore, it is necessary to invent an activated carbon with a larger specific surface area and better adsorption performance. Summary of the invention

[0005] In view of the above existing technical problems, a composite modified activated carbon and a preparation method thereof are provided. The composite modified activated carbon prepared by the method not only increases the specific surface area of ​​the activated carbon, but also increases its adsorption efficiency in environmental remediation. The raw materials and additives used in the preparation method of the invention are environmentally friendly materials, which conforms to the concept of green chemistry.

[0006] The present invention discloses a composite modified activated carbon, which is composed of the following components in parts by weight: 15~35 parts of biomass material; 35~55 parts of coal; 2~5 parts of activator; Wherein, the activators are zinc oxide and sodium hydroxide.

[0007] Preferably, the biomass material is wood chips, rice husks, straw or bamboo.

[0008] Preferably, the mass ratio of zinc oxide to sodium hydroxide is 1:(0.8-1.5).

[0009] The present invention also discloses a composite modified activated carbon and a preparation method thereof, the method comprising the following steps: S1 Raw material processing: The biomass material and the coal are crushed, ground and screened to obtain biomass material powder and coal powder; S2 mixed carbonization: putting the coal powder obtained in step S1 into a reactor, raising the temperature of the reactor and stirring it to perform the first step of carbonization, and after the first step of carbonization is completed, adding the biomass material powder obtained in step S1 into the reactor, and continuing the second step of carbonization to obtain a carbonized mixture; S3 mixture activation: adding an activator to the carbonized mixture obtained in step S2, heating the reactor and stirring it to perform an activation reaction, and obtaining an activated mixture after the activation reaction is completed; S4 cooling treatment: the activated mixture obtained in step S3 is cooled, washed and filtered with an eluent after cooling, and the filter cake is collected, and the collected filter cake is placed in a drying oven for drying, and after the drying is completed, a composite modified activated carbon is obtained.

[0010] Preferably, in the S1 raw material processing step, the mesh size used for the crushing, grinding and screening is 100-200 mesh.

[0011] Preferably, in the S2 mixed carbonization step, the reactor is heated to 500-800° C.; the first step carbonization lasts for 1-2 hours; and the second step carbonization lasts for 2-4 hours.

[0012] Preferably, in the S2 mixed carbonization step, both the first carbonization step and the second carbonization step require reactor stirring, and the stirring speed of the reactor is 1000-2000 rpm.

[0013] Preferably, in the S3 mixture activation step, the reactor needs to be heated to 800-1000° C.; the activation reaction time is 2-3 h.

[0014] Preferably, in the S4 cooling treatment step, the eluent is a mixed solution of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is 1:(1-1.5); the number of washing times is 3-5 times; the drying temperature of the drying oven is 80-100°C; and the drying time is 10-15h.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a composite modified activated carbon, in which biomass materials and coal are selected as raw materials for composite modification. This is because biomass materials have rich organic matter and good chemical activity, which can improve the pore structure of activated carbon, and coal provides a relatively stable carbon-based skeleton. By properly adjusting the ratio of coal to biomass, the best composite effect can be achieved, which not only increases the specific surface area of ​​activated carbon, but also improves its adsorption efficiency in environmental remediation. The adsorption efficiency of the prepared activated carbon in water treatment can reach more than 90%.

[0016] The present invention also provides a method for preparing composite modified activated carbon. In the S2 mixed carbonization step, the coal is first carbonized, and then the biomass material is added for carbonization. Through this process, the organic components in the raw materials are partially removed, providing a suitable pore structure for subsequent activation treatment. In the S3 mixture activation process, two activators, zinc oxide and sodium hydroxide, are added to further open the micropores in the mixture, increase the specific surface area of ​​the mixture, and improve the adsorption performance. DETAILED DESCRIPTION

[0017] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0018] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0019] Example 1: A composite modified activated carbon, consisting of the following components in parts by weight: 15 parts of biomass material; 35 parts of coal; 2 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:0.5.

[0020] A method for preparing composite modified activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material and coal are crushed, ground and screened respectively to obtain biomass material powder and coal powder, and the mesh number of the sieve used for screening is 100 meshes.

[0021] S2 mixed carbonization: put the coal powder obtained in step S1 into the reactor, raise the reactor temperature to 500°C, stir at a speed of 1000rpm to carry out the first step of carbonization, the first step of carbonization time is 1h, after the first step of carbonization is completed, add the biomass material powder obtained in step S1 into the reactor, maintain 500°C, stir at a speed of 1000rpm to continue the second step of carbonization, the second carbonization time is 2h, and obtain a carbonized mixture.

[0022] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:0.5 to the carbonized mixture obtained in step S2, increase the temperature of the reactor from the original 500°C to 800°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2 hours, and an activated mixture is obtained after the activation reaction is completed.

[0023] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1. The mixture is washed and filtered three times, and the filter cakes are collected and placed in a drying oven for drying. The drying temperature of the drying oven is 80°C and the drying time is 10 hours. After drying, the composite modified activated carbon is obtained.

[0024] Example 2: A composite modified activated carbon, consisting of the following components in parts by weight: 20 parts of biomass material; 40 parts of coal; 2.5 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:0.7.

[0025] A method for preparing composite modified activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material and coal are crushed, ground and screened respectively to obtain biomass material powder and coal powder, and the mesh number of the sieve used for screening is 150 meshes.

[0026] S2 mixed carbonization: put the coal powder obtained in step S1 into the reactor, raise the reactor temperature to 550°C, stir at a speed of 1200rpm to carry out the first step of carbonization, the first step of carbonization time is 1.2h, after the first step of carbonization is completed, add the biomass material powder obtained in step S1 into the reactor, maintain 550°C, stir at a speed of 1200rpm to continue the second step of carbonization, the second carbonization time is 2.5h, and obtain a carbonized mixture.

[0027] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:0.7 to the carbonized mixture obtained in step S2, raise the temperature of the reactor from the original 550°C to 850°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2.2h, and an activated mixture is obtained after the activation reaction is completed.

[0028] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.1. The mixture is washed and filtered 4 times, and the filter cakes are collected and placed in a drying oven for drying. The drying temperature of the drying oven is 85°C and the drying time is 11 hours. After drying, the composite modified activated carbon is obtained.

[0029] Example 3: A composite modified activated carbon, consisting of the following components in parts by weight: 25 parts of biomass material; 45 parts of coal; 3 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.

[0030] A method for preparing composite modified activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material and coal are crushed, ground and screened respectively to obtain biomass material powder and coal powder, and the mesh number of the sieve used for screening is 200 meshes.

[0031] S2 mixed carbonization: put the coal powder obtained in step S1 into the reactor, raise the reactor temperature to 600°C, stir at a speed of 1400rpm to carry out the first step of carbonization, the first step of carbonization time is 1.4h, after the first step of carbonization is completed, add the biomass material powder obtained in step S1 into the reactor, maintain 600°C, stir at a speed of 1400rpm to continue the second step of carbonization, the second carbonization time is 3h, and obtain a carbonized mixture.

[0032] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1 to the carbonized mixture obtained in step S2, raise the temperature of the reactor from the original 600°C to 900°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2.4h, and after the activation reaction is completed, an activated mixture is obtained.

[0033] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.2. The mixture is washed and filtered 5 times, and the filter cakes are collected and placed in a drying oven for drying. The drying temperature of the drying oven is 90°C and the drying time is 12h. After drying, the composite modified activated carbon is obtained.

[0034] Example 4: A composite modified activated carbon, consisting of the following components in parts by weight: 30 parts of biomass material; 50 parts of coal; 4 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2.

[0035] A method for preparing composite modified activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material and coal are crushed, ground and screened respectively to obtain biomass material powder and coal powder, and the mesh number of the sieve used for screening is 200 meshes.

[0036] S2 mixed carbonization: put the coal powder obtained in step S1 into the reactor, raise the reactor temperature to 650°C, stir at a speed of 1600rpm to carry out the first step of carbonization, the first step of carbonization time is 1.6h, after the first step of carbonization is completed, add the biomass material powder obtained in step S1 into the reactor, maintain 650°C, stir at a speed of 1600rpm to continue the second step of carbonization, the second carbonization time is 3.5h, and obtain a carbonized mixture.

[0037] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2 to the carbonized mixture obtained in step S2, raise the temperature of the reactor from the original 650°C to 950°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2.6h, and an activated mixture is obtained after the activation reaction is completed.

[0038] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.3. The mixture is washed and filtered 5 times, and the filter cakes are collected and placed in a drying oven for drying. The drying temperature of the drying oven is 95°C and the drying time is 13h. After drying, the composite modified activated carbon is obtained.

[0039] Example 5: A composite modified activated carbon, consisting of the following components in parts by weight: 35 parts of biomass material; 55 parts of coal; 5 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.5.

[0040] A method for preparing composite modified activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material and coal are crushed, ground and screened respectively to obtain biomass material powder and coal powder, and the mesh number of the sieve used for screening is 200 meshes.

[0041] S2 mixed carbonization: put the coal powder obtained in step S1 into the reactor, raise the reactor temperature to 700°C, stir at a speed of 1800rpm to carry out the first step of carbonization, the first step of carbonization time is 1.8h, after the first step of carbonization is completed, add the biomass material powder obtained in step S1 into the reactor, maintain 700°C, stir at a speed of 1800rpm to continue the second step of carbonization, the second carbonization time is 4h, and obtain a carbonized mixture.

[0042] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2 to the carbonized mixture obtained in step S2, increase the temperature of the reactor from the original 650°C to 950°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2.8h, and an activated mixture is obtained after the activation reaction is completed.

[0043] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.4. The mixture is washed and filtered 5 times, and the filter cakes are collected and placed in a drying oven for drying. The drying temperature of the drying oven is 100°C and the drying time is 14 hours. After drying, the composite modified activated carbon is obtained.

[0044] Example 6: A composite modified activated carbon, consisting of the following components in parts by weight: 30 parts of biomass material; 50 parts of coal; 4 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2.

[0045] A method for preparing composite modified activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material and coal are crushed, ground and screened respectively to obtain biomass material powder and coal powder, and the mesh number of the sieve used for screening is 200 meshes.

[0046] S2 mixed carbonization: put the coal powder obtained in step S1 into the reactor, raise the reactor temperature to 800°C, stir at a speed of 2000rpm to carry out the first step of carbonization, the first step of carbonization time is 2h, after the first step of carbonization is completed, add the biomass material powder obtained in step S1 into the reactor, maintain 800°C, stir at a speed of 2000rpm to continue the second step of carbonization, the second carbonization time is 4h, and obtain a carbonized mixture.

[0047] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2 to the carbonized mixture obtained in step S2, raise the temperature of the reactor from the original 800°C to 1000°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 3 hours, and after the activation reaction is completed, an activated mixture is obtained.

[0048] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.5, washed and filtered 5 times, the filter cakes are combined and collected, and the collected filter cakes are placed in a drying oven for drying. The drying temperature of the drying oven is 95°C and the drying time is 13h. After drying, the composite modified activated carbon is obtained.

[0049] Example 7: The activator in Example 4 is adjusted to sodium hydroxide, the proportions of other raw material components remain unchanged, and the preparation method is also the same as that of Example 4.

[0050] Example 8: The activator in Example 4 is adjusted to zinc oxide, the proportions of other raw material components remain unchanged, and the preparation method is also the same as that of Example 4.

[0051] Example 9: The biomass material in Example 4 is replaced with rice husks, and the proportions of other raw material components remain unchanged. The preparation method is also the same as that of Example 4.

[0052] Example 10: The biomass material in Example 4 is replaced with straw, and the proportions of other raw material components remain unchanged. The preparation method is also the same as that of Example 4.

[0053] Example 11: The biomass material in Example 4 is replaced with bamboo, and the proportions of other raw material components remain unchanged. The preparation method is also the same as that of Example 4.

[0054] Example 12: A composite modified activated carbon, consisting of the following components in parts by weight: 30 parts of biomass material; 50 parts of coal; 4 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2.

[0055] A method for preparing composite modified activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material and coal are crushed, ground and screened respectively to obtain biomass material powder and coal powder, and the mesh number of the sieve used for screening is 200 meshes.

[0056] S2 mixed carbonization: put the coal powder and biomass material powder obtained in step S1 into a reactor, raise the reactor temperature to 650°C, stir at a speed of 1600rpm for carbonization, and the carbonization time is 5.1h to obtain a carbonized mixture.

[0057] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2 to the carbonized mixture obtained in step S2, raise the temperature of the reactor from the original 650°C to 950°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2.6h, and an activated mixture is obtained after the activation reaction is completed.

[0058] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.3. The mixture is washed and filtered 5 times, and the filter cakes are collected and placed in a drying oven for drying. The drying temperature of the drying oven is 95°C and the drying time is 13h. After drying, the composite modified activated carbon is obtained.

[0059] Example 13: A coal-based activated carbon, comprising the following components in parts by weight: 50 parts of coal; 4 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2.

[0060] A method for preparing coal-based activated carbon, the method comprising the following steps: S1 Raw material processing: The coal is crushed, ground and screened to obtain coal powder, and the mesh size of the sieve used for screening is 200 meshes.

[0061] S2 mixed carbonization: put the coal powder obtained in step S1 into a reactor, raise the reactor temperature to 650°C, stir at a speed of 1600rpm for carbonization, and the carbonization time is 5.1h to obtain a carbonized mixture.

[0062] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2 to the carbonized mixture obtained in step S2, raise the temperature of the reactor from the original 650°C to 950°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2.6h, and an activated mixture is obtained after the activation reaction is completed.

[0063] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.3, washed and filtered 5 times, the filter cakes are combined and collected, and the collected filter cakes are placed in a drying oven for drying. The drying temperature of the drying oven is 95°C and the drying time is 13h. After drying, coal-based activated carbon is obtained.

[0064] Example 14: A biomass activated carbon, consisting of the following components in parts by weight: 30 parts of biomass material; 4 parts of activator; wherein, the biomass material is sawdust, and the activator is composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2.

[0065] A method for preparing biomass activated carbon, the method comprising the following steps: S1 Raw material processing: The biomass material is crushed, ground and screened to obtain biomass material powder, and the mesh size of the sieve used for screening is 200 meshes.

[0066] S2 mixed carbonization: add the biomass material powder obtained in step S1 into the reactor, raise the reactor temperature to 650°C, stir at a speed of 1600 rpm for carbonization, and the carbonization time is 5.1 h to obtain a carbonized mixture.

[0067] S3 mixture activation: add an activator composed of zinc oxide and sodium hydroxide in a mass ratio of 1:1.2 to the carbonized mixture obtained in step S2, raise the temperature of the reactor from the original 650°C to 950°C, maintain the original stirring speed, and carry out the activation reaction. The reaction time of the activation reaction is 2.6h, and an activated mixture is obtained after the activation reaction is completed.

[0068] S4 cooling treatment: the activated mixture obtained in step S3 is quickly cooled to 30°C and then washed and filtered with an eluent after cooling, wherein the eluent is a mixed solution of ethanol and deionized water in a volume ratio of 1:1.3, washed and filtered 5 times, the filter cakes are combined and collected, and the collected filter cakes are placed in a drying oven for drying. The drying temperature of the drying oven is 95°C and the drying time is 13h. After drying, biomass activated carbon is obtained.

[0069] The performance tests were conducted on the composite modified activated carbon prepared in Examples 1 to 9, the coal-based activated carbon prepared in Example 10, and the biomass activated carbon prepared in Example 11. The test results are shown in the following table:

[0070] It can be seen from the test data in the above table that Examples 1 to 8 are screenings of raw material ratios, activator ratios, and parameters in the preparation method, among which the composite modified activated carbon prepared in Example 4 has the best performance. Examples 4 and Examples 9 to 11 are screenings of biomass material types. It can be seen from the data that biomass materials have little effect on the performance of this composite modified activated carbon. On the whole, when the biomass materials are sawdust and bamboo, the performance is better. Example 12 adjusts the two-stage carbonization in the S2 mixed carbonization step in the preparation process to one-stage simultaneous carbonization. The performance of the composite modified activated carbon obtained is not good, and is inferior to the performance of the composite modified activated carbon prepared by two-stage carbonization. Examples 13 and 14 are coal-based activated carbon and biomass activated carbon prepared by the preparation method provided by the present invention, and their performance is worse than that of Example 4.

[0071] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A composite modified activated carbon, characterized in that: It is composed of the following components in parts by weight: 15~35 parts of biomass material; 35~55 parts of coal; 2~5 parts of activator; Wherein, the activators are zinc oxide and sodium hydroxide.

2. A composite modified activated carbon according to claim 1, characterized in that: The biomass material is wood chips, rice husks, straw or bamboo.

3. The composite modified activated carbon according to claim 1, characterized in that: The mass ratio of zinc oxide to sodium hydroxide is 1:(0.8-1.5).

4. A method for preparing composite modified activated carbon, characterized in that: The method comprises the following steps: S1 Raw material processing: The biomass material and the coal are crushed, ground and screened to obtain biomass material powder and coal powder; S2 mixed carbonization: putting the coal powder obtained in step S1 into a reactor, raising the temperature of the reactor and stirring it to perform the first step of carbonization, and after the first step of carbonization is completed, adding the biomass material powder obtained in step S1 into the reactor, and continuing the second step of carbonization to obtain a carbonized mixture; S3 mixture activation: adding an activator to the carbonized mixture obtained in step S2, heating the reactor and stirring it to perform an activation reaction, and obtaining an activated mixture after the activation reaction is completed; S4 cooling treatment: the activated mixture obtained in step S3 is cooled, washed and filtered with an eluent after cooling, and the filter cake is collected, and the collected filter cake is placed in a drying oven for drying, and after the drying is completed, a composite modified activated carbon is obtained.

5. The method for preparing a composite modified activated carbon according to claim 4, characterized in that: In the S1 raw material processing step, the mesh size used for the crushing, grinding and screening is 100-200 meshes.

6. A composite modified activated carbon and a preparation method thereof according to claim 4, characterized in that: In the S2 mixed carbonization step, the reactor is heated to 500-800° C.; the first step carbonization lasts for 1-2 hours; and the second step carbonization lasts for 2-4 hours.

7. The method for preparing a composite modified activated carbon according to claim 4, characterized in that: In the S2 mixed carbonization step, both the first carbonization step and the second carbonization step require reactor stirring, and the stirring speed of the reactor is 1000-2000 rpm.

8. The method for preparing a composite modified activated carbon according to claim 4, characterized in that: In the S3 mixture activation step, the reactor needs to be heated to 800-1000° C.; the activation reaction lasts for 2-3 hours.

9. The method for preparing a composite modified activated carbon according to claim 4, characterized in that: In the S4 cooling treatment step, the eluent is a mixed solution of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is 1:(1-1.5); the number of washing times is 3-5 times; the drying temperature of the drying oven is 80-100°C; and the drying time is 10-15h.

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