Straw biochar, preparation method and application

Abstract

The invention relates to the field of agricultural science and technology, in particular to straw biochar as well as a preparation method and application thereof. The preparation method of the straw biochar comprises the following steps: crushing corn straws for the first time, bagging the crushed corn straws, placing the bagged corn straws in a pit, performing fermentation treatment on the upper-layer covering soil for 1-3 months, washing, drying at the temperature of 80-85 DEG C, and performing secondary crushing to obtain pretreated straws; carbonizing the pretreated straw to obtain a carbonized sample; and activating the carbonized sample to obtain the straw biochar. Cellulose, cellulose and hemicellulose components in the pretreated straw are remarkably reduced compared with those in original corn straw; the BET specific surface area and the total pore volume of the straw biochar prepared by the method are obviously higher than those of straw biochar prepared from original straw through carbonization and mixed alkali activation, and it is indicated that soil microbial flora pretreatment is a method capable of effectively improving the performance of the corn straw biochar.

Description

Technical Field

[0001] The present invention relates to the field of agricultural science and technology, and particularly relates to a straw biochar, a preparation method and an application thereof. Background Art

[0002] As an important renewable resource, the annual output of straw is as high as 900 million tons, which is characterized by wide distribution and rich 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 special structural characteristic makes it difficult for straw to be degraded in the natural environment, and also brings great challenges to its industrial utilization.

[0003] In the process of straw resource utilization, pretreatment technology plays a key role. Currently, the mainstream pretreatment technologies are mainly divided into three categories: physical technology, chemical technology and biological technology. Physical pretreatment technologies include methods such as mechanical grinding, crushing, and steam explosion. Although these technologies are simple to operate, they generally have the disadvantages of high energy consumption and low treatment efficiency. Chemical pretreatment technologies mainly use means such as acid-base treatment and organic solvent extraction. Although the treatment effect is good, they face problems such as high treatment costs and easy generation of toxic and harmful by-products. Biological pretreatment technologies mainly rely on the action of specific microorganisms or biological enzymes. Although they are environmentally friendly, they have obvious deficiencies such as long treatment cycles and low efficiency.

[0004] In the field of straw biochar preparation, the biochars prepared by existing technologies generally have problems with poor performance. This is mainly manifested in the small specific surface area and underdeveloped pore structure. Therefore, there is an urgent need to develop a preparation method for straw biochar. Summary of the Invention

[0005] To solve the above problems, the present invention provides a straw biochar, a preparation method and an application thereof.

[0006] The present invention is realized through the following technical solutions: A preparation method for straw biochar, comprising the following steps: First, crush corn straw, place it in a pit, cover the upper layer with soil and carry out fermentation treatment for 1 to 3 months, wash it, dry it at 80°C to 85°C, and then carry out a second crushing to obtain pretreated straw.

[0007] Carry out carbonization treatment on the pretreated straw to obtain a carbonized sample.

[0008] Carry out activation treatment on the carbonized sample to obtain straw biochar.

[0009] Preferably, the size after the first crushing is 10 mesh to 20 mesh; the size after the second crushing is 70 mesh to 90 mesh.

[0010] Preferably, the soil is garden soil; the thickness of the covering soil is 19 cm to 21 cm.

[0011] Preferably, the microbial flora 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 .

[0012] Preferably, the size of the pit is 1.1 m to 1.3 m in length, 0.7 m to 0.9 m in width, and 0.2 m to 0.3 m in height.

[0013] Preferably, the washing is performed using deionized water.

[0014] Preferably, the steps of the carbonization treatment are as follows: heating the pretreated straw to a carbonization temperature of 500 °C at a heating rate of 10 °C / min in nitrogen, holding for 60 min, and cooling to room temperature to obtain a carbonized sample.

[0015] Preferably, the steps of the activation treatment are as follows: mixing NaOH and KOH in a mass ratio of 1:1 to prepare an alkali activator, mixing the carbonized sample with the alkali activator in a mass ratio of 1:4, activating at 700 °C for 60 min, cooling to room temperature after the reaction is completed, pickling with an HCl solution, then washing with deionized water until neutral, and drying at 80 °C to a constant weight to obtain straw biochar.

[0016] The straw biochar prepared by the described preparation method.

[0017] The application of the straw biochar in environmental remediation, soil improvement or energy storage.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing straw biochar, which comprises the following steps: crushing corn straw for the first time, bagging it, placing it in a pit, covering the upper layer with soil for fermentation treatment for 1 to 3 months, washing, drying at 80°C to 85°C, and performing secondary crushing to obtain pretreated straw; carbonizing the pretreated straw to obtain a carbonized sample; and activating the carbonized sample to obtain straw biochar. In the present invention, after crushing corn straw, it is buried in the soil, and the soil microbial flora is used to ferment the corn straw to obtain pretreated straw, and then carbonization and activation treatments are carried out to obtain high-performance corn straw biochar. The experimental results show that the cellulose, hemicellulose components in the pretreated straw of the present invention 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 invention are significantly higher than those of the original straw prepared into straw biochar by carbonization and mixed alkali activation, indicating that the soil microbial flora pretreatment of the present invention is a method that can effectively improve the performance of corn straw biochar.

[0019] In addition, compared with the traditional pretreatment technology, the present invention has established a straw pretreatment process technology system that can be carried out in large quantities and at low cost, which can effectively improve the physical and chemical properties of the subsequent straw-derived biochar. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 is the preparation process of the straw biochar of the present invention; Figure 1 in which, A is a diagram of corn straw; B is a diagram of pretreated straw obtained by pretreating straw with soil microbial flora; C is a diagram of straw biochar.

[0022] Figure 2 is a diagram of the change of bacterial community during the pretreatment process of the straw of the present invention.

[0023] Figure 3 is a diagram of the change of fungal community during the pretreatment process of the straw of the present invention.

[0024] Figure 4 is a diagram of the change of lignocellulose components in the corn straw of the present invention.

[0025] Figure 5 is a comparison diagram of the original corn straw biochar and the high-performance corn straw biochar of the present invention; Figure 5In it, a is the comparison chart 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 the comparison chart of the pore size distribution of the straw biochar prepared in Comparative Example 1 and the straw biochar prepared in Example 5; c is the scanning electron microscope test chart of the straw biochar prepared in Comparative Example 1; d is the scanning electron microscope test chart of the straw biochar prepared in Example 5. Detailed implementation mode

[0026] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in the present invention. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] The beneficial effects of the present invention are illustrated below through specific embodiments.

[0029] The corn straw used in the present invention comes from the experimental field of Jilin Agricultural University, and the variety is "Jinongyu 1801".

[0030] Example 1. A preparation method of straw biochar (1) Pretreatment of straw by soil microbial flora: After the collected corn straw is first crushed to 10 meshes, it is divided and packed into 80-mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. Then, the nylon bags filled with 4.9 kg of straw are buried flat in the pit. The size of the pit is 1.1 m × 0.7 m × 0.2 m, and the upper layer is covered with 19 cm of garden soil for fermentation treatment for 1 month. After the treatment period ends, the samples are taken out, washed with deionized water to remove soluble substances and soil residues, and then dried at 80 °C and subjected to a second crushing. The size after the second crushing is 70 meshes to obtain pretreated straw.

[0031] (2) Carbonization process: The pretreated straw is put into a horizontal tube furnace, nitrogen is injected into the tube for protection, the heating rate is 10 °C / min, the carbonization temperature of 500 °C is reached, and it is kept warm for 60 min. After cooling to room temperature, a carbonized sample is obtained.

[0032] (3) Activation process: Prepare the alkali activator MA by uniformly mixing NaOH and KOH at a mass ratio of 1:1. Uniformly mix the carbonized sample and MA at a mass ratio of 1:4, fully grind them, place them in a horizontal tube furnace, activate at 700 °C for 60 min, cool to room temperature after the reaction is completed, pickle with 1% (volume fraction) dilute HCl solution, then wash with deionized water until neutral, and place in an 80 °C constant temperature drying oven to dry to a constant weight, which is the straw biochar. The preparation process is as Figure 1 shown.

[0033] Example 2. A method for preparing straw biochar (1) Pretreat the straw with soil microbial flora: After the collected corn straw is first crushed to 20 mesh, it is divided into 80-mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. Then, the nylon bags filled with 5.0 kg of straw are buried flat in a pit with a size of 1.2 m × 0.8 m × 0.25 m, and the upper layer is covered with 20 cm of garden soil for fermentation treatment for 1 month. After the treatment period ends, take out the sample, wash the soluble substances and soil residues with deionized water, then dry at 85 °C, and perform the second crushing. The size after the second crushing is 80 mesh to obtain the pretreated straw.

[0034] (2) Carbonization process: Put the pretreated straw into a horizontal tube furnace, inject nitrogen into the tube for protection, with a heating rate of 10 °C / min, reach the carbonization temperature of 500 °C, and keep warm for 60 min. After cooling to room temperature, obtain the carbonized sample.

[0035] (3) Activation process: Prepare the alkali activator MA by uniformly mixing NaOH and KOH at a mass ratio of 1:1. Uniformly mix the carbonized sample and MA at a mass ratio of 1:4, fully grind them, place them in a horizontal tube furnace, activate at 700 °C for 60 min, cool to room temperature after the reaction is completed, pickle with 1% (volume fraction) dilute HCl solution, then wash with deionized water until neutral, and place in an 80 °C constant temperature drying oven to dry to a constant weight, which is the straw biochar.

[0036] Example 3. A method for preparing straw biochar (1) Pretreat the straw with soil microbial flora: After the collected corn straw is first crushed to 20 mesh, it is divided into 80-mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. Then, the nylon bags filled with 5.1 kg of straw are buried flat in a pit with a size of 1.3 m × 0.9 m × 0.3 m, and the upper layer is covered with 21 cm of garden soil for fermentation treatment for 1 month. After the treatment period ends, take out the sample, wash the soluble substances and soil residues with deionized water, then dry at 85 °C, and perform the second crushing. The size after the second crushing is 90 mesh to obtain the pretreated straw.

[0037] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The temperature was raised at a rate of 10°C / min to a carbonization temperature of 500°C, and the temperature was kept for 60 min. After cooling to room temperature, a carbonized sample was obtained.

[0038] (3) Activation process: NaOH and KOH were uniformly mixed in a mass ratio of 1:1 to prepare the alkaline activator MA. The carbonized sample was uniformly mixed with MA in a mass ratio of 1:4, and after being fully ground, it was placed in a horizontal tube furnace and activated at 700°C for 60 min. After the reaction was completed, it was cooled to room temperature, acid-washed with a 1% volume fraction dilute HCl solution, and then washed with deionized water until neutral, and placed in a constant temperature drying oven at 80°C to dry to a fixed weight, which was the straw biochar.

[0039] Example 4: A method for preparing straw biochar (1) Pretreatment of corn stalks with soil microorganisms: The collected corn stalks were crushed into 10 meshes for the first time and then packed into 80 mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. Then the nylon bags containing 4.9 kg of corn stalks were buried flat in a pit with a size of 1.1 m × 0.7 m × 0.2 m, and covered with 19 cm of farmland soil for fermentation treatment for 2 months. After the treatment period, the samples were taken out, the soluble substances and soil residues were washed with deionized water, and then dried at 80 ° C and crushed for the second time. The size after the second crushing was 70 mesh, and the pretreated corn stalks were obtained.

[0040] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The temperature was raised at a rate of 10°C / min to a carbonization temperature of 500°C, and the temperature was kept for 60 min. After cooling to room temperature, a carbonized sample was obtained.

[0041] (3) Activation process: NaOH and KOH were uniformly mixed in a mass ratio of 1:1 to prepare the alkaline activator MA. The carbonized sample was uniformly mixed with MA in a mass ratio of 1:4, and after being fully ground, it was placed in a horizontal tube furnace and activated at 700°C for 60 min. After the reaction was completed, it was cooled to room temperature, acid-washed with a 1% volume fraction dilute HCl solution, and then washed with deionized water until neutral, and placed in a constant temperature drying oven at 80°C to dry to a fixed weight, which was the straw biochar.

[0042] Example 5: A method for preparing straw biochar (1) Pretreatment of corn stalks with soil microorganisms: The collected corn stalks were crushed into 20 meshes for the first time and then packed into 80 mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. Then the nylon bags containing 5.0 kg of corn stalks were buried flat in a pit with a size of 1.2 m × 0.8 m × 0.25 m, and covered with 20 cm of farmland soil for fermentation treatment for 2 months. After the treatment period, the samples were taken out, the soluble substances and soil residues were washed with deionized water, and then dried at 85 ° C and crushed for the second time. The size after the second crushing was 80 mesh, and the pretreated corn stalks were obtained.

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

[0044] (3) Activation process: NaOH and KOH were uniformly mixed in a mass ratio of 1:1 to prepare the alkaline activator MA. The carbonized sample was uniformly mixed with MA in a mass ratio of 1:4, and after being fully ground, it was placed in a horizontal tube furnace and activated at 700°C for 60 min. After the reaction was completed, it was cooled to room temperature, acid-washed with a 1% volume fraction dilute HCl solution, and then washed with deionized water until neutral, and placed in a constant temperature drying oven at 80°C to dry to a fixed weight, which was the straw biochar.

[0045] Example 6: A method for preparing straw biochar (1) Pretreatment of corn stalks with soil microorganisms: The collected corn stalks were crushed into 20 meshes for the first time and then packed into 80 mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. The nylon bags containing 5.1 kg of corn stalks were then buried flat in a pit with a size of 1.3 m × 0.9 m × 0.3 m. The top layer was covered with 21 cm of farmland soil for fermentation treatment for 2 months. After the treatment period, the samples were taken out, the soluble substances and soil residues were washed with deionized water, and then dried at 85 ° C and crushed for the second time. The size after the second crushing was 90 mesh, and the pretreated corn stalks were obtained.

[0046] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The temperature was raised at a rate of 10°C / min to a carbonization temperature of 500°C, and the temperature was kept for 60 min. After cooling to room temperature, a carbonized sample was obtained.

[0047] (3) Activation process: Prepare the alkali activator MA by uniformly mixing NaOH and KOH at a mass ratio of 1:1. Uniformly mix the carbonized sample and MA at a mass ratio of 1:4, fully grind them, place them in a horizontal tube furnace, activate at 700 °C for 60 min, cool to room temperature after the reaction is completed, wash with 1% (by volume) dilute HCl solution, then wash with deionized water until neutral, and place in an 80 °C constant temperature drying oven to dry to a constant weight, which is the straw biochar.

[0048] Example 7. A method for preparing straw biochar (1) Pretreat the straw with soil microbial flora: After the collected corn straw is first crushed to 10 mesh, it is packed into 80-mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. Then, the nylon bags filled with 4.9 kg of straw are buried flat in a pit with a size of 1.1 m × 0.7 m × 0.2 m, and the upper layer is covered with 19 cm of garden soil for fermentation treatment for 3 months. After the treatment period ends, take out the sample, wash the soluble substances and soil residues with deionized water, then dry at 80 °C, and perform the second crushing. The size after the second crushing is 70 mesh to obtain the pretreated straw.

[0049] (2) Carbonization process: Put the pretreated straw into a horizontal tube furnace, inject nitrogen into the tube for protection, with a heating rate of 10 °C / min, reach the carbonization temperature of 500 °C, and keep the temperature for 60 min. After cooling to room temperature, the carbonized sample is obtained.

[0050] (3) Activation process: Prepare the alkali activator MA by uniformly mixing NaOH and KOH at a mass ratio of 1:1. Uniformly mix the carbonized sample and MA at a mass ratio of 1:4, fully grind them, place them in a horizontal tube furnace, activate at 700 °C for 60 min, cool to room temperature after the reaction is completed, wash with 1% (by volume) dilute HCl solution, then wash with deionized water until neutral, and place in an 80 °C constant temperature drying oven to dry to a constant weight, which is the straw biochar.

[0051] Example 8. A method for preparing straw biochar (1) Pretreat the straw with soil microbial flora: After the collected corn straw is first crushed to 20 mesh, it is packed into 80-mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. Then, the nylon bags filled with 5.0 kg of straw are buried flat in a pit with a size of 1.2 m × 0.8 m × 0.25 m, and the upper layer is covered with 20 cm of garden soil for fermentation treatment for 3 months. After the treatment period ends, take out the sample, wash the soluble substances and soil residues with deionized water, then dry at 85 °C, and perform the second crushing. The size after the second crushing is 80 mesh to obtain the pretreated straw.

[0052] (2) Carbonization process: The pretreated straw was placed in a horizontal tube furnace, and nitrogen was injected into the tube for protection. The temperature was raised at a rate of 10°C / min to a carbonization temperature of 500°C, and the temperature was kept for 60 min. After cooling to room temperature, a carbonized sample was obtained.

[0053] (3) Activation process: NaOH and KOH were uniformly mixed in a mass ratio of 1:1 to prepare the alkaline activator MA. The carbonized sample was uniformly mixed with MA in a mass ratio of 1:4, and after being fully ground, it was placed in a horizontal tube furnace and activated at 700°C for 60 min. After the reaction was completed, it was cooled to room temperature, acid-washed with a 1% volume fraction dilute HCl solution, and then washed with deionized water until neutral, and placed in a constant temperature drying oven at 80°C to dry to a fixed weight, which was the straw biochar.

[0054] Example 9: A method for preparing straw biochar (1) Pretreatment of corn stalks with soil microorganisms: The collected corn stalks were crushed into 20 meshes for the first time and then packed into 80 mesh nylon mesh bags with a size of 100.0 cm × 60.0 cm. The nylon bags containing 5.1 kg of corn stalks were then buried flat in a pit with a size of 1.3 m × 0.9 m × 0.3 m. The top layer was covered with 21 cm of farmland soil for fermentation treatment for 3 months. After the treatment period, the samples were taken out, the soluble substances and soil residues were washed with deionized water, and then dried at 85 ° C and crushed for the second time. The size after the second crushing was 90 mesh, and the pretreated corn stalks were obtained.

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

[0056] (3) Activation process: NaOH and KOH were mixed in a mass ratio of 1:1 to prepare a mixed alkaline activator MA. The carbonized sample was mixed with MA in a mass ratio of 1:4, and after being fully ground, it was placed in a horizontal tube furnace and activated at 700°C for 60 min. After the reaction was completed, it was cooled to room temperature, acid-washed with a 1% volume fraction dilute HCl solution, and then washed with deionized water until neutral, and placed in a constant temperature drying oven at 80°C to dry to a fixed weight, which was the straw biochar.

[0057] Comparative Example 1: A method for preparing straw biochar The corn straw is directly subjected to steps (2) and (3) in Example 5 to obtain straw biochar.

[0058] Experimental Example 1 The changes in soil microbial flora during the pretreatment process in Example 2, Example 5, and Example 8 were detected respectively, and the results are as follows: Figure 2 and Figure 3As shown, it indicates that the richness of bacteria and fungi related to lignocellulose degradation has increased. The bacteria and fungi mentioned 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 . It shows the feasibility of using soil microbial flora to pretreat straw. Subsequently, the lignocellulose components of the pretreated straw in Example 2, Example 5, and Example 8 were measured. The results are as Figure 4 shown. The relative content of cellulose in the original corn straw is 36.75%, the relative content of hemicellulose is 22.44%, and the relative content of lignin is 22.55%. In the pretreated straw, the cellulose component decreased to 30.02%, the hemicellulose component decreased to 18.75%, and the lignin component decreased by 17.80%, verifying the effectiveness of the soil microbial flora in pretreating straw. Comparing the straw biochar prepared in Example 5 of the present invention with the straw biochar obtained in Comparative Example 1, the results are as Figure 5 shown. The BET specific surface area of the straw biochar prepared in Example 5 reached 2483.43 m 2 / g, which was effectively increased by 18.97% compared with 2087.48 m 2 / g of the straw biochar obtained in Comparative Example 1. The total pore volume of the straw biochar prepared in Example 5 reached 1.4589 cm 3 / g, which was effectively increased by 19.08% compared with 1.2251 cm 3 / g of the straw biochar obtained in Comparative Example 1.

[0059] It should be noted that the present invention conducted the above same experiments on Example 1, Example 3, Example 4, Example 6, Example 7, and Example 9. Among them, the richness of bacteria and fungi related to lignocellulose degradation has increased, and the relative contents of cellulose, hemicellulose, and lignin in the pretreated straw have all decreased compared with the original corn straw. Compared with the straw biochar obtained in Comparative Example 1, the BET specific surface area and the total pore volume have both increased significantly.

[0060] In summary, soil microbial flora pretreatment is a method that can effectively improve the performance of corn straw biochar.

[0061] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0062] The embodiments described above merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. For those of ordinary skill in the art, without departing from the concept of the present invention, several variations and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of straw biochar, characterized in that, It includes the following steps: First, crush the corn straw and place it in a pit. Cover the upper layer with soil and conduct fermentation treatment for 1 to 3 months. Then wash it and dry it at 80°C to 85°C. Next, conduct a second crushing to obtain pretreated straw; Conduct carbonization treatment on the pretreated straw to obtain a carbonized sample; Conduct activation treatment on the carbonized sample to obtain straw biochar.

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

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

4. The preparation method according to claim 1, characterized in that, The microbial flora 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 。 5. The preparation method according to claim 1, characterized in that, The size of the pit is 1.1 m to 1.3 m in length, 0.7 m to 0.9 m in width, and 0.2 m to 0.3 m in height.

6. The preparation method according to claim 1, characterized in that The washing is carried out using deionized water.

7. The preparation method according to claim 1, wherein, The steps of the carbonization treatment are as follows: Heat the pretreated straw in nitrogen at a heating rate of 10°C / min to the carbonization temperature of 500°C, keep it warm for 60 min, and then cool it to room temperature to obtain a carbonized sample.

8. The preparation method according to claim 1, wherein The steps of the activation treatment are as follows: Mix NaOH and KOH according to a mass ratio of 1:1 to prepare an alkali activator. Mix the carbonized sample with the alkali activator according to a mass ratio of 1:4, activate it at 700°C for 60 min. After the reaction is completed, cool it to room temperature, wash it with HCl solution for pickling, then wash it with deionized water until neutral, and dry it at 80°C to a constant weight to obtain straw biochar.

9. A straw biochar prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the straw biochar as claimed in claim 9 in environmental remediation, soil improvement or energy storage.

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