Modification method and application of balsa wood charcoal

Abstract

The invention relates to a modification method and application of cork wood charcoal. According to the biochar preparation method provided by the invention, cork wood biochar is prepared through anaerobic dry distillation, and relatively stable biochar is obtained by controlling the carbonization degree. Different phosphates are adopted to modify the balsa wood biochar, and the modified biochar suitable for balsa wood planting is found by comparing the modification effects and effects of different phosphates. In combination with a mode of hole application of the biochar, the utilization efficiency of the biochar can be remarkably improved, and the cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of biochar preparation, and in particular to a balsa wood biochar modification method and application thereof. Background Art

[0002] Biochar is a solid substance made by pyrolyzing biomass (such as plant residues, wood chips, etc.) in a low-oxygen environment. It has a highly porous structure and carbon content, so it is widely used in soil improvement and environmental governance. It can also be used as a filter material to absorb heavy metals, pesticides and other pollutants in water; biochar can also be used as a filler to improve the performance of plastics, rubber and other composite materials; biochar can be used to produce environmentally friendly building materials, such as carbon-negative concrete and thermal insulation materials.

[0003] Traditional biochar preparation includes traditional kiln method, pyrolysis method, gasification method, hydrothermal carbonization and microwave pyrolysis, etc. However, the efficacy of biochar produced by these methods is relatively low. Biochar is in great demand for soil improvement, but due to the low efficacy of existing biochar, the effect in improving soil is not obvious, and a large amount of biochar is required, which not only increases the cost but also causes waste of biochar. Balsa wood will produce a lot of scraps from felling to log processing. Balsa wood has a light density and is an ideal material for preparing biochar. Traditional biochar processing methods are generally difficult to control the degree of carbonization, resulting in unstable carbon structure, and the improvement effect after application to the soil is not obvious.

[0004] In view of this, it is urgent to modify its specificity in order to maximize its application. Therefore, it is necessary to find a method to modify biochar to improve its efficacy. Summary of the invention

[0005] In order to solve or partially solve the problems existing in the related art, on the one hand, the present application provides a method for modifying balsa wood biochar, and the modification method comprises the following steps:

[0006] 1) crushing the balsa branches and drying them to obtain balsa wood chips, and then crushing them again by anaerobic dry distillation and pyrolysis to obtain balsa wood biochar chips;

[0007] 2) mixing the balsa wood biochar fragments and phosphate in the above 1) in a mass ratio of 1-5:1, soaking them in deionized water for a certain period of time and then drying them to obtain dried balsa wood biochar fragments;

[0008] The phosphate is diammonium phosphate;

[0009] 3) performing secondary anaerobic dry distillation on the dried balsa wood biochar fragments obtained in 2) to obtain modified balsa wood biochar.

[0010] Furthermore, the drying temperature in 1) is 70° C. and the drying time is 48 hours.

[0011] Furthermore, the specific operation of anaerobic distillation is: putting the balsa wood chips into a carbonization furnace; the temperature of the carbonization furnace is increased at a rate of 3-5°C / min, and the temperature is maintained at 400°C for 2-3h.

[0012] Furthermore, the specific operation of the secondary anaerobic distillation is: putting the dried balsa wood biochar fragments obtained in 2) into a carbonization furnace; the temperature of the carbonization furnace is increased to 400° C. at a temperature climbing rate of 3-5° C. / min and maintained for 1-2 hours.

[0013] Furthermore, the certain time period in 2) is 72 hours.

[0014] On the other hand, the present application also provides a method for applying balsa wood biochar on soil, the application method comprising the following steps:

[0015] (1) Determine the position according to the certain row spacing and plant spacing, dig a hole at the corresponding site, loosen the soil completely, sprinkle dazomethane fungicide, cover it for a certain period of time, and then exhaust it;

[0016] (2) After the balsa wood has established its roots, biochar is applied by hole application; the amount of biochar applied is 60-120 g;

[0017] The specific steps of the hole-fertilization method are as follows: dig a hole with a diameter of 8-12 cm and a depth of 8-12 cm 15-20 cm away from the seedling;

[0018] The biochar is the modified balsa wood biochar prepared by the above-mentioned modification method.

[0019] Furthermore, the row spacing is 4 meters and the plant spacing is 3.5 meters.

[0020] Furthermore, the size of the pit is: 45-55 cm in diameter and 48-53 cm in depth.

[0021] Furthermore, in (1), the covering time is 10-15 days; and the exhaust time is 8-12 days.

[0022] On the other hand, the present application also provides an application of balsa wood biochar in improving soil, and the balsa wood biochar is prepared by the above-mentioned balsa wood biochar modification method.

[0023] Beneficial Effects

[0024] 1) Process for preparing balsa wood biochar by anaerobic dry distillation;

[0025] Anaerobic distillation is carried out under oxygen-deficient conditions, which reduces carbon oxidation losses and allows biomass to be more efficiently converted into stable carbon forms, thereby increasing the carbon retention rate of balsa wood biochar. Due to the oxygen-deficient environment, anaerobic distillation reduces the production of harmful gases (such as carbon monoxide and other volatile organic compounds), and the emissions are cleaner than traditional combustion or pyrolysis methods. The combustible gases and liquid byproducts (such as bio-oil) produced during the anaerobic distillation process can be collected for energy production, improving the resource utilization efficiency of the overall process. Compared with high-temperature pyrolysis, anaerobic distillation is carried out at lower temperatures, so the energy consumption is lower and it is more energy-efficient. The process is able to process a variety of biomass raw materials, including agricultural waste and forestry residues, and has a wide range of applications. The biochar generated by anaerobic distillation has a more stable structure and can exist in the soil for a long time, providing continuous soil improvement and carbon sequestration effects.

[0026] 2) Phosphate-modified balsa wood biochar: Since the exchangeable aluminum content in the soil will increase significantly during the balsa wood planting process, and the increase in exchangeable aluminum content will limit the availability of phosphorus in the soil, phosphate-modified balsa wood biochar can significantly increase the availability of phosphorus in the soil while inhibiting the further increase of exchangeable aluminum content.

[0027] 3) This application uses soil in situ sterilization technology to remove the residual effects of soil microorganisms, prompting balsa wood to re-recruit microbial groups, build new interactions, and increase balsa wood biomass accumulation;

[0028] 4) The present application adopts the biochar hole application measure during soil cultivation, and applies the biochar in a fixed position to accurately supply nutrients, which can save the application of charcoal and save costs.

[0029] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present application will become more apparent by describing in more detail the exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0031] Figure 1 This is a scanning electron microscope image of balsa wood biochar.

[0032] Figure 2 This is the scanning electron microscope mapping of ammonium dihydrogen phosphate modified balsa wood biochar;

[0033] A: Scanning electron microscope image;

[0034] B: electron image of element distribution;

[0035] C: Total element distribution spectrum.

[0036] Figure 3 This is the scanning electron microscopy mapping of potassium dihydrogen phosphate modified balsa wood biochar;

[0037] A: Scanning electron microscope image;

[0038] B: electron image of element distribution;

[0039] C: Total element distribution spectrum.

[0040] Figure 4 This is a comparison of scanning electron microscope images of biochar prepared from different materials;

[0041] A: Scanning electron micrograph of balsa wood biochar;

[0042] B: Scanning electron micrograph of banyan biochar;

[0043] C: Scanning electron micrograph of rubber tree biochar;

[0044] D: Scanning electron micrograph of rice straw biochar.

[0045] Figure 5 The effect of biochar and soil sterilization on the plant height of balsa wood in soils of different sources; P (balsa wood planted) and N (balsa wood not planted) in the figure represent the soil source (Source); S (sterilization) and L (unsterilized) represent the sterilization treatment (Sterilization); BioC (biochar), BioK (biochar modified with potassium dihydrogen phosphate), BioN (biochar modified with ammonium dihydrogen phosphate) and CK (control) represent the biochar addition treatment (Biochar). In the figure, *, *, ** represent significant differences between different experimental treatments at the p<0.05, 0.01, 0.001 levels; the same below.

[0046] The left picture shows the effect of different soil sources on the height of balsa wood;

[0047] The middle figure shows the effect of soil sterilization on the plant height of balsa wood;

[0048] The right figure shows the effect of biochar addition on balsa plant height;

[0049] Figure 6 is the effect of biochar and soil sterilization on balsa wood biomass on soils of different origins;

[0050] The left figure shows the effect of different soil sources on balsa wood biomass;

[0051] The middle figure shows the effect of soil sterilization on balsa wood biomass;

[0052] The right figure shows the effect of biochar addition on balsa wood biomass.

[0053] Figure 7 is the effect of biochar and soil sterilization on the fungal community structure in soils from different sources;

[0054] A: Differences in soil fungal community structure under different experimental treatments;

[0055] B: Soil fungal species composition under biochar and soil sterilization

[0056] Figure 8 is the effect of biochar and soil sterilization on fungal functional groups in soils from different sources;

[0057] Fig. 9 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0058] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0059] Balsa wood (Ochroma lagopus) has a special market demand and is a composite sandwich panel material commonly used in large wind turbine blades. However, the rapid growth of balsa wood is bound to cause changes in soil carbon components, imbalance of microbial flora, soil nutrient limitation, etc. The cultivation of soil carbon pools (for example, applying biochar, improving soil biodiversity, etc.) can not only enhance the "sink" of the soil, but also improve soil fertility, increase production and generate income. As the number of years of balsa wood planting increases, the intensity and direction of balsa wood-soil interaction will also change, becoming a key factor restricting the growth of balsa wood.

[0060] Since the traditional biochar preparation method has no obvious effect after being applied to the soil, the anaerobic distillation method can prepare biochar with different degrees of carbonization as needed. A large amount of nutrient elements will be exhausted during the planting process of balsa wood, and chemical fertilizers are usually applied to increase production, but this will aggravate soil acidification, nutrient loss, etc. The present invention uses phosphate-modified balsa wood biochar to achieve the effect of slow nutrient release. However, previous inventions simply introduced a single preparation scheme and did not compare the modification effects of different phosphates, lacking verification of the efficacy of modified biochar. The application technology of biochar is usually mixed in when plowing the field. This method is not suitable for balsa wood plantations. The present invention adopts a more efficient hole application method to improve the efficient utilization of biochar and nutrients. During the growth of balsa wood, the microbial flora in the soil will be changed, forming an "ecological memory" in the soil. When balsa wood is planted again, it is not conducive to the growth of seedlings. This application adopts a chemical sterilization scheme to eliminate the influence of the residual effect of soil microorganisms. The application of modified biochar can regulate the ecological functions of the soil, effectively improve the efficiency of balsa wood seedlings in recruiting beneficial bacteria, and promote the establishment and growth of balsa wood seedlings.

[0061] The balsa wood biochar is prepared by anaerobic distillation technology, and the degree of carbonization is controlled to obtain relatively stable biochar. The balsa wood biochar is modified by different phosphates, and the modification effects and functions of different phosphates are compared to find the modified biochar suitable for balsa wood planting. In combination with soil sterilization technology, the accumulated microbial legacy effects in balsa wood plantations are removed to provide a more suitable environment for the later cultivation of balsa wood. The use of hole-applied biochar can significantly improve the utilization efficiency of biochar and save costs. This invention aims to obtain a highly effective biochar by modifying balsa wood biochar with phosphate, which can improve the soil, especially in combination with soil sterilization to remove the legacy effects of soil microorganisms. The construction of a new bacterial community can significantly promote the establishment and growth of balsa wood seedlings.

[0062] Example 1 Preparation of balsa wood biochar

[0063] (1) Balsa branches were collected from a balsa plantation in Menglun Town, Xishuangbanna, Yunnan Province, and crushed into 5-10 cm flakes using a crusher; the flakes were dried in an oven at 70°C for 48 hours.

[0064] (2) Then, the balsa wood biochar was prepared in a carbonization furnace by anaerobic retorting and pyrolysis, with a programmed temperature rise rate of 3-5°C / min, and the temperature was raised to 400°C and maintained for 2-3h;

[0065] (3) The prepared biochar is further crushed. The crushed biochar has a larger specific surface area, which is convenient for the preparation of modified biochar in the later stage.

[0066] (4) The balsa wood biochar fragments prepared in the early stage were soaked in the phosphate solution at a mass ratio of balsa wood biochar fragments to phosphate of 1-5:1 for more than 72 hours, then dried in an oven at 70°C and then soaked in deionized water. After that, the anaerobic retorting method was used, with a temperature climbing rate of 3-5°C / min and maintained at 400°C for 1-2 hours. Potassium dihydrogen phosphate and ammonium dihydrogen phosphate were used as phosphates.

[0067] (5) Scanning electron microscopy structure of modified balsa wood biochar

[0068] Scanning electron microscope images of balsa wood biochar and modified biochar. The porous structure of balsa wood is the preferred material for preparing biochar ( Figure 1 ); phosphorus in ammonium dihydrogen phosphate modified balsa wood biochar is uniformly adsorbed on the carbon surface ( Figure 2 ), and the phosphorus distribution in biochar modified with potassium dihydrogen phosphate is better ( Figure 3 ).

[0069] Comparative Example 1 Preparation of biochar from different raw materials

[0070] Banyan tree, rubber tree branches and rice straw were collected and prepared into biochar according to the method of Example 1 to compare the differences of biochar prepared from the three materials.

[0071] Compared with biochar made from banyan and rubber tree materials, biochar made from balsa wood has a larger pore structure and a stronger adsorption effect. Compared with biochar made from rice straw, the physical structure of balsa wood biochar is more solid and stable due to its lignified structure ( Figure 4 ), can maintain a more complete void structure in the soil to better improve the soil. It is more convenient for later biochar modification.

[0072] Comparative Example 2 Screening of phosphate required for phosphate-modified balsa wood biochar

[0073] Two phosphates, ammonium dihydrogen phosphate and potassium dihydrogen phosphate, were used to modify balsa wood biochar. Too high a phosphate ratio would lead to incomplete binding with biochar and precipitation, while too low a ratio would be detrimental to improving the efficacy of biochar. Based on the preliminary experiments, to ensure the maximum binding of phosphate and biochar, a balsa wood biochar: phosphate mass ratio of 1:1 was selected, deionized water was added, and soaked for 72 hours. Then it was dried in an oven at 70°C for 36 hours. The anaerobic retort method was used, the temperature climbing rate was set to 3°C / min, and 400°C was maintained for 1 hour. Compared with the biochar modified with potassium dihydrogen phosphate, the elements in the biochar modified with ammonium dihydrogen phosphate were more evenly distributed on the surface of the biochar, and the modification effect of ammonium dihydrogen phosphate was better, which was more suitable for phosphate-modified biochar.

[0074] Example 2 Modified biochar potted plant experiment

[0075] To explore the efficacy of modified balsa wood biochar, a pot experiment was conducted.

[0076] 1) Soil source: soil from a plantation where balsa wood had been planted for 4 years; the adjacent soil where balsa wood had not been planted served as a control.

[0077] 2) Soil sterilization, using dazomethane for sterilization, and non-sterilized soil as a control;

[0078] 3) Biochar addition treatment: unmodified balsa wood biochar, potassium dihydrogen phosphate modified balsa wood biochar, ammonium dihydrogen phosphate modified balsa wood biochar, and no biochar added control;

[0079] The experiment adopted a full factorial design (soil source, soil sterilization and biochar addition), with 5 replicates and a total of 80 samples. The balsa wood growth period was from June 20, 2024 to October 20, 2024, when the balsa wood biomass was harvested, for a total of 4 months. The biochar efficacy was evaluated by measuring the height and biomass of the balsa wood.

[0080] Treatment group 1: soil without balsa wood planting; no soil sterilization; no biochar addition;

[0081] Treatment group 2: soil without balsa wood; no soil sterilization; addition of unmodified balsa wood biochar;

[0082] Treatment group 3: soil without balsa wood; no soil sterilization; addition of potassium dihydrogen phosphate modified balsa wood biochar;

[0083] Treatment group 4: soil without balsa wood; no soil sterilization; addition of ammonium dihydrogen phosphate modified balsa wood biochar;

[0084] Treatment group 5: soil without balsa wood plantation; dazomethane sterilization; no biochar added;

[0085] Treatment group 6: soil without balsa wood; dazomethane sterilization; addition of unmodified balsa wood biochar;

[0086] Treatment group 7: soil without balsa wood; dazomethan sterilization; balsa wood biochar modified with potassium dihydrogen phosphate;

[0087] Treatment group 8: soil without balsa wood; dazomethan sterilization; addition of ammonium dihydrogen phosphate modified balsa wood biochar;

[0088] Treatment 9 consisted of soil from a plantation planted with balsa wood for 4 years; no soil sterilization; no biochar addition;

[0089] Treatment 10: soil from a plantation with balsa wood for 4 years; no soil sterilization; unmodified balsa wood biochar added;

[0090] Treatment 11: soil from a plantation where balsa wood was grown for 4 years; no soil sterilization; addition of potassium dihydrogen phosphate-modified balsa wood biochar;

[0091] Treatment 12 consisted of soil from a plantation where balsa wood had been grown for 4 years; no soil sterilization; and addition of ammonium dihydrogen phosphate-modified balsa wood biochar;

[0092] Treatment 13: soil from a plantation planted with balsa wood for 4 years; sterilized with dazomethane; no biochar added;

[0093] Treatment 14 consisted of soil from a plantation where balsa wood had been grown for 4 years; sterilized with dazomethane; and added with unmodified balsa wood biochar;

[0094] Treatment 15 consisted of soil from a plantation where balsa wood had been grown for 4 years; dazomethane sterilization; and balsa wood biochar modified with potassium dihydrogen phosphate.

[0095] Treatment 16 consisted of soil from a plantation where balsa wood had been grown for 4 years; sterilized with dazomethon; and modified with ammonium dihydrogen phosphate-modified balsa wood biochar;

[0096] The experimental results showed that compared with the soil planted with balsa wood (treatment group 9), the height of balsa wood in the soil without balsa wood (treatment group 1) was significantly higher by 47%; compared with the soil planted with balsa wood but not sterilized (treatment group 9), the sterilized soil (treatment group 13) significantly increased the height of balsa wood by 52%; compared with the treatment of planting balsa wood but not adding biochar (treatment group 9), the application of biochar (treatment group 10) increased the height of balsa wood by 6%; the application of biochar modified by ammonium dihydrogen phosphate (treatment group 12) could significantly increase the height by 133%; the sterilization and application of biochar modified by ammonium dihydrogen phosphate (treatment group 16) could significantly increase the height by 81% ( Figure 5 ). Compared with soil planted with balsa wood (treatment group 9), the balsa wood biomass in soil without balsa wood (treatment group 1) was significantly higher by 83%; compared with soil planted with balsa wood but not sterilized (treatment group 9), sterilized soil (treatment group 13) significantly increased balsa wood biomass by 190%; compared with soil planted with balsa wood but not sterilized (treatment group 9), application of biochar (treatment group 10) significantly increased balsa wood biomass by 35%; application of biochar modified with diammonium phosphate (treatment group 12) significantly increased it by 282%; sterilization and application of biochar modified with diammonium phosphate (treatment group 16) significantly increased it by 238% ( Figure 6 ).

[0097] Example 3 Application of modified biochar

[0098] Determine the position according to the row spacing and plant spacing (4 meters * 3.5 meters), dig a circular pit with a diameter of about 50 cm and a depth of about 50 cm at the corresponding site, loosen the soil completely, sprinkle the dazomethane fungicide, then cover it with a black film, seal it and maintain it for 10-15 days to achieve a complete sterilization effect. In addition, remove the film to vent for about 10 days to remove the steam generated in the soil and better plant the balsa seedlings.

[0099] After the plants have taken root, apply biochar using the hole-fertilization method. Dig a hole with a diameter of about 10 cm and a depth of about 10 cm 15-20 cm away from the seedlings and fill it with 60-120 g of biochar.

[0100] When harvesting balsa wood, soil in the 15 cm soil layer was collected using a soil drill. Soil fungal amplicons were sequenced using high-throughput sequencing technology. Bioinformatics methods were used to analyze the data. The experimental results showed that there were significant differences in the soil fungal community structure between soils that had previously planted balsa wood and those that had not. Soil sterilization had the greatest impact on the soil fungal community structure, which could remove the impact of previous balsa wood planting; the addition of biochar had relatively little effect on non-sterilized soil, and for sterilized soil, there was no significant difference between the application of unmodified biochar and the non-addition of biochar, while there was a significant difference between the treatment with modified biochar and the treatment without biochar ( Figure 7 ). By analyzing the fungal functional groups, it was found that sterilization can significantly inhibit pathogens in the soil, while the application of biochar can significantly increase the content of mycorrhizal fungi in the soil and reduce the abundance of pathogens in the soil ( Figure 8 ).

[0101] Traditionally, biochar is applied during soil tillage and buried in field soil. However, this method can significantly increase crop yields for densely planted field crops such as rice and wheat. However, for the cultivation of large trees, the planting density is completely different from that of crops, and there is no need to apply biochar to the entire field to better protect the soil structure. In the present invention, hole application is adopted to accurately provide nutrients. This method can significantly save the application of charcoal and save costs.

[0102] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for modifying balsa wood biochar, characterized in that: The modification method comprises the following steps: 1) crushing the balsa branches and drying them to obtain balsa wood chips, and then crushing them again by anaerobic dry distillation and pyrolysis to obtain balsa wood biochar chips; 2) mixing the balsa wood biochar fragments and phosphate in the above 1) in a mass ratio of 1-5:1, soaking them in deionized water for a certain period of time and then drying them to obtain dried balsa wood biochar fragments; The phosphate is diammonium phosphate; 3) performing secondary anaerobic dry distillation on the dried balsa wood biochar fragments obtained in 2) to obtain modified balsa wood biochar.

2. The modification method according to claim 1, characterized in that: The drying temperature in 1) is 70° C. and the drying time is 48 hours.

3. The modification method according to claim 1, characterized in that: The specific operation of the anaerobic distillation is: putting the balsa wood chips into a carbonization furnace; the temperature of the carbonization furnace is increased at a rate of 3-5°C / min, and the temperature is maintained at 400°C for 2-3h.

4. The modification method according to claim 1, characterized in that: The specific operation of the secondary anaerobic distillation is: putting the dried balsa wood biochar fragments obtained in 2) into a carbonization furnace; the temperature of the carbonization furnace is increased to 400° C. at a temperature climbing rate of 3-5° C. / min and maintained for 1-2 hours.

5. The modification method according to claim 1, characterized in that: The certain time period in 2) is 72 hours.

6. A method for applying balsa wood biochar to soil, characterized in that: The steps of the application method include the following steps: (1) Determine the position according to the certain row spacing and plant spacing, dig a hole at the corresponding site, loosen the soil completely, sprinkle dazomethane fungicide, cover it for a certain period of time, and then exhaust it; (2) After the balsa wood has established its roots, biochar is applied by hole application; the amount of biochar applied is 60-120 g; The specific steps of the hole-fertilization method are: digging a hole with a diameter of 8-12 cm and a depth of 8-12 cm at a distance of 15-20 cm from the seedling; The biochar is modified balsa wood biochar prepared by the modification method according to claim 1.

7. The application method according to claim 6, characterized in that The row spacing is 4 meters and the plant spacing is 3.5 meters.

8. The application method according to claim 6, characterized in that The size of the pit is: 45-55 cm in diameter and 48-53 cm in depth.

9. The application method according to claim 6, characterized in that The covering time in (1) is 10-15 days; the exhaust time is 8-12 days.

10. An application of balsa wood biochar in improving soil, characterized in that: The balsa wood biochar is prepared by the modification method of the balsa wood biochar according to claim 1.

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