Straw biochar, preparation method and application thereof

Abstract

The present application relates to the field of agricultural science and technology, and particularly relates to a straw biochar, a preparation method and application. The preparation method of the straw biochar comprises the following steps: firstly crushing corn straw, bagging, placing in a pit, covering with soil on the upper layer, and performing fermentation treatment for 1-3 months, washing, drying at 80-85 DEG C, secondly crushing, and obtaining pretreated straw; performing carbonization treatment on the pretreated straw, obtaining a carbonized sample; performing activation treatment on the carbonized sample, and obtaining the straw biochar. The cellulose, cellulose, and hemicellulose components in the pretreated straw are significantly reduced compared with the original corn straw; and the BET specific surface area and total pore volume of the straw biochar prepared by the present application are significantly higher than those of the straw biochar prepared by carbonization and mixed alkali activation of the original straw, indicating that the soil microbial flora pretreatment is a method capable of effectively improving the performance of the corn straw biochar.

Description

Technical Field

[0001] This invention relates to the field of agricultural science and technology, specifically to a straw biochar, its preparation method, and its application. Background Technology

[0002] Straw, as an important renewable resource, has an annual output of up to 900 million tons and is characterized by its wide distribution and abundant reserves. In terms of composition, straw is mainly composed of lignocellulose, in which cellulose, hemicellulose, and lignin are intertwined through complex chemical bonds and physical interactions, forming a highly dense lignocellulose structure. This unique structural characteristic makes straw difficult to degrade in the natural environment, and also poses a significant challenge to its industrial utilization.

[0003] Pretreatment technology plays a crucial role in the resource utilization of straw. Currently, mainstream pretreatment technologies are mainly divided into three categories: physical, chemical, and biological technologies. Physical pretreatment technologies include methods such as mechanical grinding, crushing, and steam explosion. While these technologies are simple to operate, they generally suffer from high energy consumption and low processing efficiency. Chemical pretreatment technologies mainly employ acid-base treatment and organic solvent extraction. Although the treatment effect is relatively good, they face problems such as high processing costs and the potential generation of toxic and harmful byproducts. Biological pretreatment technologies mainly rely on the action of specific microorganisms or enzymes. While environmentally friendly, they have significant drawbacks such as long processing cycles and low efficiency.

[0004] In the field of straw biochar preparation, existing technologies generally produce biochar with poor performance, mainly due to small specific surface area and underdeveloped pore structure. Therefore, there is an urgent need to develop a method for preparing straw biochar. Summary of the Invention

[0005] To address the above problems, this invention provides straw biochar, its preparation method, and its application.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing straw biochar includes the following steps:

[0008] The corn stalks are first crushed, placed in a pit, covered with soil, and fermented for 1 to 3 months. They are then washed, dried at 80℃ to 85℃, and crushed a second time to obtain pretreated stalks.

[0009] The pretreated straw was carbonized to obtain carbonized samples.

[0010] The carbonized sample was activated to obtain straw biochar.

[0011] Preferably, the size after the first grinding is 10-20 mesh; and the size after the second grinding is 70-90 mesh.

[0012] Preferably, the soil is garden soil; the thickness of the covering soil is 19cm to 21cm.

[0013] Preferably, the microbial community in the soil includes Chitinophaga, Rhizobium, Gluconobacter, Sphingobium, Parapedobacter, Sphingomonas, Flavobacterium, Pseudomonas, Unclassified Rhizobiaceae, Sphingobacterium, Pseudoxanthomonas, Enterobacter, Pantoea, Brevundimonas, Devosia, Brucella, Endobacterium, Agrobacterium, Stenotrophomonas, Olivibacter, Meyerozyma, Hannaella, Harzia, Neoschizothecium, Sphaeronaemella, Exophiala, Aspergillus, Alternaria, Phoma, Cyphellophora, Candida, Kurtzmaniella, Geotrichum, Phialophora, Fusarium, Unclassified Dipodascaceae, Stemphylium, Unclassified, Papiliotrema and Unclassified Fungi .

[0014] Preferably, the pit has a length of 1.1m to 1.3m, a width of 0.7m to 0.9m, and a height of 0.2m to 0.3m.

[0015] Preferably, the washing is performed using deionized water.

[0016] Preferably, the carbonization process involves heating the pretreated straw in nitrogen at a rate of 10°C / min to a carbonization temperature of 500°C, holding the temperature for 60 minutes, and then cooling it to room temperature to obtain a carbonized sample.

[0017] Preferably, the activation treatment step is as follows: NaOH and KOH are mixed in a mass ratio of 1:1 to prepare an alkaline activator, the carbonized sample is mixed with the alkaline activator in a mass ratio of 1:4, activated at 700℃ for 60 min, after the reaction is completed, cooled to room temperature, acid-washed with HCl solution, washed with deionized water until neutral, and dried at 80℃ to a fixed weight to obtain straw biochar.

[0018] The straw biochar prepared by the method described above.

[0019] The application of straw biochar in environmental remediation, soil improvement or energy storage.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention provides a method for preparing straw biochar, comprising the following steps: corn stalks are first crushed, bagged, placed in a pit, covered with soil, and fermented for 1-3 months; then washed, dried at 80-85℃, and crushed a second time to obtain pretreated straw; the pretreated straw is then carbonized to obtain a carbonized sample; and the carbonized sample is then activated to obtain straw biochar. This invention involves burying crushed corn stalks in soil, utilizing soil microbial flora to ferment the corn stalks to obtain pretreated straw, followed by carbonization and activation to obtain high-performance corn straw biochar. Experimental results show that the cellulose, cellulose, and hemicellulose components in the pretreated straw are significantly reduced compared to the original corn stalks; and the BET specific surface area and total pore volume of the straw biochar prepared by this invention are significantly higher than those prepared from the original straw through carbonization and mixed alkali activation. This indicates that the soil microbial flora pretreatment method of this invention is an effective way to improve the performance of corn straw biochar.

[0022] Furthermore, compared to traditional pretreatment technologies, this invention establishes a straw pretreatment process system that enables large-scale, low-cost processing, which can effectively improve the physicochemical properties of subsequent straw-derived biochar. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The present invention describes the preparation process of straw biochar. Figure 1 In the diagram, A represents corn straw; B represents pretreated straw obtained by pretreating straw with soil microbial flora; and C represents straw biochar.

[0025] Figure 2 This diagram illustrates the changes in bacterial communities during the pretreatment of straw according to the present invention.

[0026] Figure 3 This is a diagram showing the changes in the fungal community during the pretreatment of straw according to the present invention.

[0027] Figure 4 This is a diagram showing the changes in the lignocellulose components in corn stalks according to the present invention.

[0028] Figure 5 This is a comparison diagram of the original corn stalk biochar and the high-performance corn stalk biochar of this invention; Figure 5In the figures, a is a comparison of the BET specific surface area of ​​the straw biochar prepared in Comparative Example 1 and the straw biochar prepared in Example 5; b is a comparison of the pore size distribution of the straw biochar prepared in Comparative Example 1 and the straw biochar prepared in Example 5; c is a scanning electron microscope image of the straw biochar prepared in Example 1; and d is a scanning electron microscope image of the straw biochar prepared in Example 5. Detailed Implementation

[0029] To facilitate understanding of the present invention, a more comprehensive description is provided below, along with preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this invention and in its specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0031] The beneficial effects of the present invention will be illustrated below through specific embodiments.

[0032] The corn stalks used in this invention come from the experimental field of Jilin Agricultural University, and the variety is "Jinongyu 1801".

[0033] Example 1: A method for preparing straw biochar

[0034] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 10 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm × 60.0cm. Then, the nylon bags containing 4.9kg of straw were buried flat in a pit with dimensions of 1.1m × 0.7m × 0.2m, and covered with 19cm of garden soil for fermentation treatment for 1 month. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 80℃. The straw was then crushed a second time to a size of 70 mesh, thus obtaining pretreated straw.

[0035] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0036] (3) Activation process: NaOH and KOH were uniformly mixed at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample was uniformly mixed with MA at a mass ratio of 1:4, thoroughly ground, and placed in a horizontal tube furnace. Activation was carried out at 700℃ for 60 min. After the reaction was completed, the mixture was cooled to room temperature, acid-washed with 1% (v / v) dilute HCl solution, and then washed with deionized water until neutral. The mixture was then dried in an 80℃ constant temperature drying oven to a fixed weight, which yielded straw biochar. The preparation process is as follows: Figure 1 As shown.

[0037] Example 2: A method for preparing straw biochar

[0038] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 20 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm × 60.0cm. Then, the nylon bags containing 5.0kg of straw were buried flat in a pit with dimensions of 1.2m × 0.8m × 0.25m, and covered with 20cm of garden soil for fermentation treatment for 1 month. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 85℃. The straw was then crushed a second time to a size of 80 mesh, thus obtaining pretreated straw.

[0039] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0040] (3) Activation process: NaOH and KOH are mixed uniformly at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample is mixed uniformly with MA at a mass ratio of 1:4, ground thoroughly, and placed in a horizontal tube furnace. It is activated at 700℃ for 60 min. After the reaction is completed, it is cooled to room temperature, acid-washed with 1% dilute HCl solution, and then washed with deionized water until neutral. It is then dried in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0041] Example 3: A method for preparing straw biochar

[0042] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 20 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm×60.0cm. Then, the nylon bags containing 5.1kg of straw were buried flat in a pit with dimensions of 1.3m×0.9m×0.3m, and covered with 21cm of garden soil for fermentation for 1 month. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 85℃. The straw was then crushed a second time to a size of 90 mesh, thus obtaining pretreated straw.

[0043] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0044] (3) Activation process: NaOH and KOH are mixed uniformly at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample is mixed uniformly with MA at a mass ratio of 1:4, ground thoroughly, and placed in a horizontal tube furnace. It is activated at 700℃ for 60 min. After the reaction is completed, it is cooled to room temperature, acid-washed with 1% dilute HCl solution, and then washed with deionized water until neutral. It is then dried in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0045] Example 4: A method for preparing straw biochar

[0046] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 10 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm × 60.0cm. Then, the nylon bags containing 4.9kg of straw were buried flat in a pit with dimensions of 1.1m × 0.7m × 0.2m, and covered with 19cm of garden soil for fermentation treatment for 2 months. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 80℃. The straw was then crushed a second time to a size of 70 mesh, thus obtaining pretreated straw.

[0047] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0048] (3) Activation process: NaOH and KOH are mixed uniformly at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample is mixed uniformly with MA at a mass ratio of 1:4, ground thoroughly, and placed in a horizontal tube furnace. It is activated at 700℃ for 60 min. After the reaction is completed, it is cooled to room temperature, acid-washed with 1% dilute HCl solution, and then washed with deionized water until neutral. It is then dried in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0049] Example 5: A method for preparing straw biochar

[0050] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 20 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm×60.0cm. Then, the nylon bags containing 5.0kg of straw were buried flat in a pit with dimensions of 1.2m×0.8m×0.25m, and covered with 20cm of garden soil for fermentation treatment for 2 months. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 85℃. The straw was then crushed a second time to a size of 80 mesh, thus obtaining pretreated straw.

[0051] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0052] (3) Activation process: NaOH and KOH are mixed uniformly at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample is mixed uniformly with MA at a mass ratio of 1:4, ground thoroughly, and placed in a horizontal tube furnace. It is activated at 700℃ for 60 min. After the reaction is completed, it is cooled to room temperature, acid-washed with 1% dilute HCl solution, and then washed with deionized water until neutral. It is then dried in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0053] Example 6: A method for preparing straw biochar

[0054] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 20 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm×60.0cm. Then, the nylon bags containing 5.1kg of straw were buried flat in a pit with dimensions of 1.3m×0.9m×0.3m, and covered with 21cm of garden soil for fermentation treatment for 2 months. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 85℃. The straw was then crushed a second time to a size of 90 mesh, thus obtaining pretreated straw.

[0055] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0056] (3) Activation process: NaOH and KOH are mixed uniformly at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample is mixed uniformly with MA at a mass ratio of 1:4, ground thoroughly, and placed in a horizontal tube furnace. It is activated at 700℃ for 60 min. After the reaction is completed, it is cooled to room temperature, acid-washed with 1% dilute HCl solution, and then washed with deionized water until neutral. It is then dried in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0057] Example 7: A method for preparing straw biochar

[0058] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 10 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm × 60.0cm. Then, the nylon bags containing 4.9kg of straw were buried flat in a pit with dimensions of 1.1m × 0.7m × 0.2m, and covered with 19cm of garden soil for fermentation for 3 months. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 80℃. The straw was then crushed a second time to a size of 70 mesh, thus obtaining pretreated straw.

[0059] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0060] (3) Activation process: NaOH and KOH are mixed uniformly at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample is mixed uniformly with MA at a mass ratio of 1:4, ground thoroughly, and placed in a horizontal tube furnace. It is activated at 700℃ for 60 min. After the reaction is completed, it is cooled to room temperature, acid-washed with 1% dilute HCl solution, and then washed with deionized water until neutral. It is then dried in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0061] Example 8: A method for preparing straw biochar

[0062] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 20 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm × 60.0cm. Then, the nylon bags containing 5.0kg of straw were buried flat in a pit with dimensions of 1.2m × 0.8m × 0.25m, and covered with 20cm of garden soil for fermentation treatment for 3 months. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 85℃. The straw was then crushed a second time to a size of 80 mesh, thus obtaining pretreated straw.

[0063] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0064] (3) Activation process: NaOH and KOH are mixed uniformly at a mass ratio of 1:1 to prepare the alkali activator MA. The carbonized sample is mixed uniformly with MA at a mass ratio of 1:4, ground thoroughly, and placed in a horizontal tube furnace. It is activated at 700℃ for 60 min. After the reaction is completed, it is cooled to room temperature, acid-washed with 1% dilute HCl solution, and then washed with deionized water until neutral. It is then dried in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0065] Example 9: A method for preparing straw biochar

[0066] (1) Soil microbial community pretreatment of straw: The collected corn straw was first crushed to 20 mesh and then packaged into 80 mesh nylon bags with dimensions of 100.0cm×60.0cm. Then, the nylon bags containing 5.1kg of straw were buried flat in a pit with dimensions of 1.3m×0.9m×0.3m, and covered with 21cm of garden soil for fermentation treatment for 3 months. After the treatment period, the samples were taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 85℃. The straw was then crushed a second time to a size of 90 mesh, thus obtaining pretreated straw.

[0067] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The heating rate was 10℃ / min, and the carbonization temperature was 500℃. The temperature was held for 60min. After cooling to room temperature, the carbonized sample was obtained.

[0068] (3) Activation process: Prepare a mixed alkali activator MA by uniformly mixing NaOH and KOH at a mass ratio of 1:1. Mix the carbonized sample with MA at a mass ratio of 1:4, grind thoroughly, place in a horizontal tube furnace, and activate at 700℃ for 60 min. After the reaction is complete, cool to room temperature, wash with 1% dilute HCl solution, wash with deionized water until neutral, and dry in an 80℃ constant temperature drying oven to a fixed weight, which is straw biochar.

[0069] Comparative Example 1: A method for preparing straw biochar

[0070] Corn stalks were directly subjected to steps (2) and (3) in Example 5 to obtain straw biochar.

[0071] Experimental Example 1

[0072] The changes in soil microbial communities during the pretreatment processes in Examples 2, 5, and 8 were detected, and the results are as follows: Figure 2 and Figure 3 As shown, the abundance of both bacteria and fungi related to lignocellulose degradation has increased, and these bacteria and fungi include... Chitinophaga, Rhizobium, Gluconobacter, Sphingobium, Parapedobacter, Sphingomonas, Flavobacterium, Pseudomonas, Unclassified Rhizobiaceae, Sphingobacterium, Pseudoxanthomonas, Enterobacter, Pantoea, Brevundimonas, Devosia, Brucella, Endobacterium, Agrobacterium, Stenotrophomonas, Olivibacter, Meyerozyma, Hannaella, Harzia, Neoschizothecium, Sphaeronaemella, Exophiala, Aspergillus, Alternaria, Phoma, Cyphellophora, Candida, Kurtzmaniella, Geotrichum, Phialophora, Fusarium, Unclassified Dipodascaceae, Stemphylium, Unclassified, Papiliotrema and Unclassified Fungi This demonstrates the feasibility of pretreating straw using soil microbial communities. Subsequently, the lignocellulose composition of the pretreated straw from Examples 2, 5, and 8 was determined, and the results are as follows: Figure 4 As shown, the relative content of cellulose in the original corn straw was 36.75%, the relative content of hemicellulose was 22.44%, and the relative content of lignin was 22.55%. In the pretreated straw, the cellulose content decreased to 30.02%, the hemicellulose content decreased to 18.75%, and the lignin content decreased by 17.80%, verifying the effectiveness of soil microbial community pretreatment of straw. The straw biochar prepared in Example 5 of this invention was compared with the straw biochar obtained in Comparative Example 1, and the results are as follows... Figure 5 As shown, the BET specific surface area of ​​the straw biochar prepared in Example 5 reached 2483.43 m². 2 / g, compared to 2087.48m³ of straw biochar obtained in Comparative Example 1. 2 / g, effectively increasing the yield by 18.97%. The total pore volume of the straw biochar prepared in Example 5 reached 1.4589 cm³. 3 / g, compared to 1.2251cm³ of straw biochar obtained in Comparative Example 1. 3 / g, effectively increasing by 19.08%.

[0073] It should be noted that the same experiments were performed on Examples 1, 3, 4, 6, 7 and 9 of the present invention. In these experiments, the abundance of bacteria and fungi related to the degradation of lignocellulose increased. The relative contents of cellulose, hemicellulose and lignin in the pretreated straw decreased compared with the original corn straw. Compared with the straw biochar obtained in Comparative Example 1, the BET specific surface area and total pore volume were significantly increased.

[0074] In conclusion, soil microbial pretreatment is an effective method to improve the performance of corn straw biochar.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. A method for preparing straw biochar, characterized in that, Includes the following steps: The corn stalks are first crushed, placed in a pit, covered with soil and fermented for 1 to 3 months, washed, dried at 80℃ to 85℃, and then crushed a second time to obtain pre-treated stalks. The pretreated straw was carbonized to obtain carbonized samples; The carbonized sample was activated to obtain straw biochar; The carbonization process is as follows: the pretreated straw is heated to a carbonization temperature of 500°C in nitrogen at a heating rate of 10°C / min, held at that temperature for 60 minutes, and then cooled to room temperature to obtain a carbonized sample. The activation process is as follows: NaOH and KOH are mixed in a mass ratio of 1:1 to prepare an alkaline activator. The carbonized sample is mixed with the alkaline activator in a mass ratio of 1:

4. The mixture is activated at 700℃ for 60 min. After the reaction is completed, the mixture is cooled to room temperature, acid-washed with HCl solution, washed with deionized water until neutral, and dried at 80℃ to a fixed weight to obtain straw biochar. The microbial community in the soil includes Chitinophaga, Rhizobium, Gluconobacter, Sphingobium, Parapedobacter,Sphingomonas,Flavobacterium,Pseudomonas,Unclassified Rhizobiaceae, Sphingobacterium, Pseudoxanthomonas, Enterobacter, Pantoea, Brevundimonas,Devosia,Brucella,Endobacterium,Agrobacterium,Stenotrophomonas, Olivibacter, Meyerozyma, Hannaella, Harzia, Neoschizothecium, Sphaeronaemella, Exophiala, Aspergillus, Alternaria, Phoma, Cyphellophora, Candida, Kurtzmaniella, Geotrichum, Phialophora, Fusarium, Unclassified Dipodascaceae, Stemphylium, Unclassified, Papiliotrema and Unclassified Fungi .

2. The preparation method according to claim 1, characterized in that, The size after the first grinding is 10-20 mesh; the size after the second grinding is 70-90 mesh.

3. The preparation method according to claim 1, characterized in that, The soil is garden soil; the thickness of the covering soil is 19cm to 21cm.

4. The preparation method according to claim 1, characterized in that, The pit measures 1.1m to 1.3m in length, 0.7m to 0.9m in width, and 0.2m to 0.3m in height.

5. The preparation method according to claim 1, characterized in that, The washing process involves using deionized water.

6. A straw biochar prepared by the preparation method according to any one of claims 1 to 5.

7. The application of straw biochar as described in claim 6 in environmental remediation, soil improvement or energy storage.

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