Method for preparing modified biochar from mulberry branches and application thereof

Abstract

The application discloses a method for preparing modified biochar from mulberry branches and application thereof. The method comprises the following steps: A, raw material preparation: crushing the mulberry branches to 1-2 mm, and screening the crushed mulberry branches to obtain mulberry branch powder; B, soaking: soaking the mulberry branch powder in a potassium silicate solution, mixing and oscillating, and then drying to obtain a potassium silicate-soaked biomass mixture; C, anaerobic pyrolysis: performing pyrolysis treatment in a nitrogen atmosphere, and then drying to obtain silicate-modified biochar. The silicate-modified mulberry branch biochar prepared by the method has the beneficial effects that on one hand, the raw material source and application of the biochar are expanded, the cost of agricultural waste treatment is reduced, the resource utilization and reduction utilization of the mulberry branch waste can be realized, and the utilization value of the biochar is greatly improved; on the other hand, the prepared modified biochar can be used for relieving the continuous cropping obstacles of grapes, and has important significance for the development of sustainable agriculture.

Description

Technical Field

[0001] This invention relates to a method for preparing modified biochar and its application, specifically a method for preparing modified biochar from mulberry branches and its application. Background Technology

[0002] Continuous cropping obstacle refers to the phenomenon where, even under normal management conditions, the yield and quality of a crop or its closely related species decline when planted continuously in the same field, resulting in severe pest and disease problems. Continuous cropping leads to a decrease in available soil nutrients, an imbalance in nutrient ratios, a decline in soil enzyme activity, changes in the microbial community and its functions, and an exacerbation of pests and diseases. The decline in crop yield and quality is the ultimate result and manifestation of the above-mentioned harms, making the mitigation or elimination of continuous cropping obstacle a major and challenging issue in the planting process.

[0003] The application of organic and inorganic amendments is frequently reported to alleviate continuous cropping obstacles in crops. Biochar, a carbon-rich product of biomass pyrolysis under low-oxygen conditions, typically possesses a microporous structure, large surface area, abundant active functional groups, high pH value, and cation exchange capacity. Various methods, such as mineral impregnation, can enhance the multiple capabilities of biochar. Exogenous silicates can enhance plant resistance to abiotic and biotic stresses through various mechanisms, such as forming physical barriers in plant cell walls, regulating nutrient absorption and metabolism, strengthening plant defense systems, and altering the forms of heavy metals.

[0004] Modified biochar can alter the abundance and diversity of soil microbial communities, particularly stimulating rhizosphere growth-promoting bacteria. Generally, modified biochar alleviates continuous cropping soil obstacles primarily due to the inherent adsorption properties of biochar (e.g., porous structure) and its ability to enhance nutrient uptake by plants. Current biochar modification techniques include surface oxidation and functionalization. Surface oxidation, such as acid- or alkali-impregnated biochar, has limited impact on soil quality; while functionalization is expensive and has high production costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and application for preparing modified biochar from mulberry branches, which can not only reduce the resource utilization and volume reduction of mulberry branch waste to reduce production costs, but also alleviate the impact of crop continuous cropping obstacles.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for preparing modified biochar from mulberry branches, comprising the following steps:

[0007] A. Raw material preparation: Crush mulberry branches to 1-2mm and sieve the crushed mulberry branches to obtain mulberry branch powder;

[0008] B. Impregnation: Mulberry twig powder is soaked in potassium silicate solution and mixed and shaken. After drying, a potassium silicate impregnated biomass mixture is obtained.

[0009] C. Anaerobic pyrolysis: Pyrolysis is carried out under a nitrogen atmosphere, followed by drying to obtain silicate-modified biochar.

[0010] Further, in step B, the silicate solution is a 10-30% potassium silicate solution, and the mass ratio of mulberry twig powder to potassium silicate solution is 1:(10-20).

[0011] Furthermore, the soaking time in step B is 36-48 hours.

[0012] Furthermore, in step B, the mulberry twig powder is mixed with potassium silicate solution and then shaken at a speed of 150-200 r / min for 48 h.

[0013] Furthermore, the pyrolysis process involves introducing nitrogen gas into a tubular furnace for anaerobic protection and then heating it.

[0014] Furthermore, the pyrolysis treatment is carried out at a temperature of 400-650℃ for 4-6 hours, with a heating rate of 8-12℃ / min and a nitrogen flow rate of 0.1-0.4L / min.

[0015] Furthermore, the preferred pyrolysis temperature is 600℃, and the preferred time is 3 hours.

[0016] Furthermore, the heating rate during the pyrolysis process is 10℃ / min, and the nitrogen flow rate is 0.2L / min.

[0017] Furthermore, the drying temperature in steps B and C is 80-105℃.

[0018] Application of modified biochar prepared from mulberry branches according to the above method in alleviating grape continuous cropping obstacles.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The silicate-modified mulberry branch biochar synthesized by the impregnation-pyrolysis method in this invention can significantly increase the specific surface area and other physicochemical properties, and has a stronger adsorption capacity. It can promote the growth of grape seedlings in continuously cropped soil and stimulate the increase of the population of Pseudomonas rhizosphere in grapes.

[0021] Biochar is produced by heating crop and forestry waste at high temperatures under anaerobic conditions, causing it to decompose into porous carbon. It has advantages such as a large specific surface area, high selectivity, and fast adsorption rate. In addition, the silicates in modified biochar regulate plant nutrient absorption and induce the growth of plant rhizosphere growth-promoting bacteria. Therefore, modified mulberry branch biochar can stimulate grape growth and alleviate soil continuous cropping obstacles.

[0022] This invention makes full use of the biomass resources of mulberry tree branches. The silicate-modified mulberry branch biochar prepared by it expands the source and use of biochar raw materials, reduces the cost of agricultural waste treatment, and realizes the resource utilization and volume reduction of mulberry branch waste, greatly improving the utilization value of biochar. On the other hand, the prepared modified biochar can be used to alleviate the obstacles of continuous cropping of grapes, which is of great significance to the development of sustainable agriculture. Attached Figure Description

[0023] Figure 1 A schematic diagram showing the change in grapevine height after the addition of modified biochar;

[0024] Figure 2 A schematic diagram showing the change in stem diameter of grapes after the addition of modified biochar;

[0025] Figure 3 This is a schematic diagram showing the abundance changes of Pseudomonas species in rhizosphere soil. Detailed Implementation

[0026] The present invention discloses a method for preparing modified biochar from mulberry branches. Using mulberry branches as raw material, the method modifies the biochar with potassium silicate solution and then prepares it through anaerobic pyrolysis. This method aims to significantly increase the specific surface area and growth-promoting capacity of the biochar, thereby mitigating the impact of continuous cropping on grape growth. The method and application of the present invention for preparing modified biochar from mulberry branches will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1:

[0028] The method for preparing modified biochar from mulberry branches in this embodiment includes the following steps:

[0029] A. Raw material preparation: Select mulberry branches as biomass raw material, crush the mulberry branches to 1-2mm, and sieve the crushed mulberry branches to obtain mulberry branch powder;

[0030] B. Impregnation: Soak mulberry twig powder in a 10-30% potassium silicate solution (the mass ratio of mulberry twig powder to potassium silicate solution is 1:10-20, and the soaking time is 36-48h), mix it in a shaker at a speed of 150-200r / min, filter it (time is 48h), and dry it in an oven (drying temperature is 80-105℃) to obtain the potassium silicate impregnated biomass mixture.

[0031] C. Anaerobic pyrolysis: Pyrolysis is carried out under a nitrogen atmosphere at a temperature of 400-650℃ for 4-6 hours. The heating rate during pyrolysis is 8-12℃ / min, and the nitrogen flow rate is 0.1-0.4L / min. After pyrolysis, the mixture is cooled to room temperature, then washed and dried at a temperature of 80-105℃. The dried product is silicate-modified biochar. The preferred pyrolysis temperature is 600℃, and the preferred time is 3 hours.

[0032] Example 2:

[0033] The method for preparing modified biochar from mulberry branches in this embodiment includes the following steps:

[0034] A. Raw material preparation: Select mulberry branches as biomass raw material, crush the mulberry branches to 1-2mm, and pass the crushed mulberry branches through a 2mm sieve to obtain mulberry branch powder;

[0035] B. Impregnation: Soak 10g of mulberry twig powder in 100mL of 20% potassium silicate solution for 48h, then shake on a shaker at 180r / min for 48h, and dry in an oven at 105℃ to obtain potassium silicate impregnated biomass mixture.

[0036] C. Anaerobic pyrolysis: The biomass mixture from step B is placed in a tube furnace and nitrogen gas is introduced for anaerobic protection. The temperature is increased at a rate of 10℃ / min and the nitrogen flow rate is 0.2L / min. The modified mulberry branch biochar is obtained by pyrolysis at 500℃ for 4 hours.

[0037] D. The modified mulberry branch biochar from step C is dried in an oven at 80°C, crushed in a mortar, and passed through a 40-mesh sieve to obtain silicate-modified mulberry branch biochar.

[0038] Based on the experimental data from Example 2, a comparison was made with the preparation process of unmodified biochar, and the following results were obtained:

[0039] The preparation process of unmodified biochar involves drying mulberry twig powder directly at 105℃ without soaking it in potassium silicate solution, then taking 10g of mulberry twig powder and placing it in a tube furnace. The heating rate is 10℃ / min, the nitrogen flow rate is 0.2L / min, and the powder is pyrolyzed at 500℃ for 4h to obtain unmodified biochar.

[0040] The changes in the physicochemical properties of the modified biochar are shown in Table 1.

[0041] Table 1 Physicochemical properties of modified mulberry branch biochar

[0042]

[0043] The letters in the table represent significant differences.

[0044] Example 3:

[0045] The application of modified biochar prepared from mulberry branches according to the above method in alleviating grape continuous cropping obstacles is described in the following experimental process and results:

[0046] Soil from the top 10-20cm of the Summer Black grapevines, within 1m of the plant after 8 years of continuous cropping, was collected, sieved, and dried for later use. Potted plants were used, with 2kg of soil per pot. Three treatments were set up, with four replicates per group. The three treatments were as follows: (1) soil without biochar as the control (CK); (2) soil with 1% (by weight) biochar (B); (3) soil with 1% (by weight) modified biochar (GB). Before potting, the biochar or modified biochar was mixed evenly with the soil. Two-year-old Summer Black cuttings with uniform growth were planted in pots and placed in a greenhouse for routine management. Two months later, the grapevine height and stem diameter were measured. Changes in the plant rhizosphere growth-promoting bacteria—Pseudomonas—in the rhizosphere soil were detected using real-time quantitative PCR.

[0047] The results showed that, compared with the control, the addition of modified biochar significantly increased the height and stem diameter of grapevines and stimulated an increase in the abundance of Pseudomonas aeruginosa. Figure 1 , Figure 2 and Figure 3 ).

Claims

1. A method for preparing modified biochar from mulberry branches, characterized by, The method comprises the following steps: A. Raw material preparation: crush mulberry branches to 1-2 mm, and sieve the crushed mulberry branches to obtain mulberry branch powder; B. Immersion: immerse the mulberry branch powder in a potassium silicate solution, mix and shake, and then dry to obtain a potassium silicate-impregnated biomass mixture; In step B, the potassium silicate solution is 10-30%, the mass ratio of the mulberry branch powder to the potassium silicate solution is 1:(10-20), and the immersion time is 36-48 h; C. Anaerobic pyrolysis: perform pyrolysis treatment under a nitrogen atmosphere, and then dry to obtain a silicate-modified biochar; The pyrolysis treatment is performed at a temperature of 400-650℃ for 4-6 h, the heating rate during the pyrolysis treatment is 8-12℃ / min, and the nitrogen flow rate is 0.1-0.4 L / min; In step B, the mulberry branch powder is mixed with the potassium silicate solution, and then shaken at a speed of 150-200 r / min for 48 h.

2. The method of claim 1, wherein the mulberry branch is prepared by the following steps of: The pyrolysis treatment is performed by introducing nitrogen into a tube furnace to perform anaerobic protection and heating.

3. The method of claim 2, wherein the mulberry branch is prepared by the steps of: The pyrolysis treatment is performed at a temperature of 600℃ for 3 h.

4. The method of claim 3, wherein the mulberry branch is prepared by the steps of: The pyrolysis treatment is performed at a heating rate of 10℃ / min and a nitrogen flow rate of 0.2 L / min.

5. The method of claim 4, wherein the mulberry branch is prepared by the steps of: The drying temperature in steps B and C is 80-105℃.

6. Use of a mulberry branch-modified biochar prepared by the method of any one of claims 1-5 in relieving grape continuous cropping obstacles.

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