Electron-rich biochar as well as preparation method and application thereof

Abstract

The invention provides electron-rich biochar as well as a preparation method and application thereof, and belongs to the technical field of solid waste biomass utilization. The preparation method of the electron-rich biochar provided by the invention comprises the following steps: performing pyrolysis carbonization on a biomass raw material under an anaerobic condition to obtain a biochar precursor; mixing the biochar precursor, a reducing agent and water, and reducing to obtain the electron-rich biochar, the reducing agent is prepared from one or more of KHB4, NaBH4, LiBH4 and LiAlH4. The reducing agent can reduce the abundance of functional groups-NH2 / -OH on the surface of the biochar, and also can introduce electron-rich (orbital) high-energy alkyne bonds, so that the specific capacitance value of the biochar is increased, and an electron-rich soil capacitor is obtained; the reducing agent reduces a diffusion impedance layer on the surface of the biochar and charge transfer resistance in the biochar, the biochar rich in pi-electronic chemical structures is prepared, saponin substances are eliminated, and continuous cropping obstacles are effectively relieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste biomass utilization, and specifically relates to electron-rich biochar and a preparation method and application thereof. Background Art

[0002] Panax notoginseng is a large and precious Chinese medicinal material. With the expansion of the planting area of ​​Panax notoginseng, the planting process often only focuses on yield and ignores quality. The problem of continuous cropping obstacles caused by pests and diseases, pollutants, etc. during the planting of Panax notoginseng is very prominent. Continuous cropping obstacles are a serious problem faced in the crop production process. The accumulation of soil-borne pathogens and toxic substances in the rhizosphere soil is an important factor causing continuous cropping obstacles. The toxic saponins secreted by the roots of Panax notoginseng synergistically aggravate root rot by destroying the root cell wall and stimulating the growth of soil-borne pathogens. In order to cope with this situation, reasonable fertilization, crop rotation, intercropping, adding biological control agents (biological agents for pest control diseases) and additives to improve soil fertility, soil disinfection and breeding of disease-resistant varieties are used to regulate the content of saponins to control Panax notoginseng root rot. However, these methods cannot efficiently and stably regulate the saponins secreted by plants and accumulated in the soil, and continuous cropping obstacles will still recur. Summary of the invention

[0003] The purpose of the present invention is to provide an electron-rich biochar and a preparation method and application thereof. The electron-rich biochar prepared by the present invention can efficiently regulate the saponins secreted by plants and accumulated in the soil, and can effectively alleviate the obstacles of continuous cropping.

[0004] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0005] A method for preparing electron-rich biochar comprises the following steps:

[0006] The biomass raw material is pyrolyzed and carbonized under anaerobic conditions to obtain a biochar precursor;

[0007] The biochar precursor, a reducing agent and water are mixed and reduced to obtain the electron-rich biochar;

[0008] The reducing agent includes one or more of KHB4, NaBH4, LiBH4 and LiAlH4.

[0009] Preferably, the mass ratio of the reducing agent to the biochar precursor is 5:1 to 2:1.

[0010] Preferably, the temperature of the pyrolysis carbonization is 300-700° C., and the time is 12-24 hours.

[0011] Preferably, the reduction temperature is 20-40° C. and the time is 12-24 hours.

[0012] Preferably, the biomass raw material includes lignin-containing biomass and / or livestock manure.

[0013] The present invention also provides electron-rich biochar prepared by the preparation method described in the above technical solution.

[0014] The present invention also provides the use of the electron-rich biochar described in the above technical solution in degrading allelopathic substances and other pollutants.

[0015] Preferably, the pollutants include one or more of saponins, aliphatic acids and organic acids.

[0016] Preferably, the allelochemical is an allelochemical in soil.

[0017] The present invention provides a method for preparing electron-rich biochar, comprising the following steps: pyrolyzing and carbonizing a biomass raw material under anaerobic conditions to obtain a biochar precursor; mixing the biochar precursor, a reducing agent and water, and reducing the mixture to obtain the electron-rich biochar; the reducing agent comprises one or more of KHB4, NaBH4, LiBH4 and LiAlH4. The present invention pyrolyzes and carbonizes biomass raw materials under anaerobic conditions, and the obtained biochar precursor has a high specific surface area; then the biochar precursor is reacted with a reducing agent, and the reducing agent can reduce -NO2 and C=O on the surface of the biochar precursor, which can reduce the abundance of functional groups -NH2 / -OH on the surface of the biochar precursor. At the same time, the reducing agent provided by the present invention can also introduce electron-rich (orbital) high-energy alkyne bonds, so that the specific capacitance value of the obtained electron-rich biochar is increased, and finally an electron-rich soil "capacitor" is obtained, which can provide the required electrons for soil physical and chemical reactions and store electrons; at the same time, the reducing agent reduces the diffusion impedance layer on the biochar surface and the charge transfer resistance inside the biochar, and prepares biochar rich in π-electron chemical structure, which can stimulate the growth of electrotrophic microorganisms, thereby eliminating saponin substances and effectively alleviating continuous cropping obstacles.

[0018] After the electron-rich biochar is applied to the soil, the conductivity and effective N, P and K are observed to increase significantly, which can alleviate the problem of continuous cropping obstacles and effectively prevent the recurrence of continuous cropping obstacles; at the same time, the electron-rich biochar can also increase the soil phosphatase and sucrase activities, as well as plant height, average leaf width and chlorophyll content; by increasing the soil pH value, effective P, K and organic matter content, reducing the content of chemical substances vanillic acid and eugenol, further alleviating continuous cropping obstacles. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 Capacitance diagrams of biochar W350-M and W350 obtained in Example 1;

[0021] Figure 2 This is a graph showing the removal capacity of biochar W350-M and W350 obtained in Example 1 for ginsenoside Rb1;

[0022] Figure 3 This is a graph showing the changes in the rhizosphere fungal community structure of Soil-2 soil mediated by biochar W350-M and W350 obtained in Example 1;

[0023] Figure 4 This is a graph showing the changes in the rhizosphere fungal community structure of Soil-3 soil mediated by biochar W350-M and W350 obtained in Example 1;

[0024] Figure 5 This is a graph showing the changes in the rhizosphere bacterial community structure of Soil-2 soil mediated by biochar W350-M and W350 obtained in Example 1;

[0025] Figure 6 This is a graph showing the changes in the rhizosphere bacterial community structure of Soil-3 soil mediated by biochar W350-M and W350 obtained in Example 1;

[0026] Figure 7 Capacitance diagrams of biochar W700-M and W700 obtained in Example 2;

[0027] Figure 8 This is the removal capacity of biochar W700-M and W700 obtained in Example 2 for ginsenoside Rb1;

[0028] Fig. 9 This is a graph showing the changes in the rhizosphere fungal community structure of Soil-2 soil mediated by biochar W700-M and W700 obtained in Example 2;

[0029] Fig.10 This is a graph showing the changes in the rhizosphere fungal community structure of Soil-3 soil mediated by biochar W700-M and W700 obtained in Example 2;

[0030] Fig.11 This is a graph showing the changes in the rhizosphere bacterial community structure of Soil-2 mediated by biochar W700-M and W700 obtained in Example 2;

[0031] Fig.12 This is a diagram showing the changes in the rhizospheric bacterial community structure of Soil-3 mediated by biochar W700-M and W700 obtained in Example 2. DETAILED DESCRIPTION

[0032] The present invention provides a method for preparing electron-rich biochar, comprising the following steps:

[0033] The biomass raw material is pyrolyzed and carbonized under anaerobic conditions to obtain a biochar precursor;

[0034] The biochar precursor, a reducing agent and water are mixed and reduced to obtain the electron-rich biochar;

[0035] The reducing agent includes one or more selective reducing agents such as KHB4, NaBH4, LiBH4 and LiAlH4.

[0036] In the present invention, unless otherwise specified, all preparation raw materials are preferably commercially available products well known to those skilled in the art.

[0037] The present invention performs pyrolysis carbonization on biomass raw materials under anaerobic conditions to obtain a biochar precursor. In the present invention, the biomass raw materials include lignin-containing biomass and / or livestock manure; the lignin-containing biomass includes straw or fruit shell, and in a specific embodiment, it can be corn straw.

[0038] In the present invention, the biomass raw material further includes pretreatment before use; the pretreatment includes washing and screening; the washing is water washing; the screening is screening through a 40-mesh sieve to obtain biomass particles.

[0039] In the present invention, the temperature of the pyrolysis carbonization is 300-700°C, and in a specific embodiment, it can be 350°C, 400°C, 500°C or 650°C; the time is 12-24h, and in a specific embodiment, it can be 16h, 18h or 20h.

[0040] In the present invention, the biochar precursor is also ground, washed and dried; the particle size of the biochar precursor is 50 to 120 meshes, and in a specific embodiment, it can be 80 meshes or 100 meshes; the washing is water washing; and the drying is freeze drying.

[0041] After obtaining the biochar precursor, the present invention mixes the biochar precursor, a reducing agent and water, performs reduction, and obtains the electron-rich biochar. In the present invention, the reducing agent includes one or more of KHB4, NaBH4, LiBH4 and LiAlH4, and in a specific embodiment, it can be KHB4. The reducing agent of the present invention can reduce the abundance of the functional group -NH2 / -OH on the surface of the biochar precursor, and at the same time, the reducing agent can also introduce electron-rich (orbital) high-energy alkyne bonds, so that the specific capacitance value of the biochar precursor is increased, and finally an electron-rich soil "capacitor" is obtained, which can provide the required electrons for the physical and chemical reactions of the soil and store electrons; at the same time, the reducing agent reduces the diffusion impedance layer on the surface of the biochar and the charge transfer resistance inside the biochar, and prepares biochar rich in π-electron chemical structure, which can stimulate the growth of electrotrophic microorganisms, thereby eliminating saponin substances and effectively alleviating continuous cropping obstacles. After the electron-rich biochar is applied to the soil, the present invention observes that the electrical conductivity and the effective N, P and K are significantly increased, which can alleviate the problem of continuous cropping obstacles; at the same time, the electron-rich biochar can also increase the soil phosphatase and sucrase activities, as well as the plant height, average leaf width and chlorophyll content; by increasing the soil pH value, effective P, K and organic matter content, reducing the content of chemical substances vanillic acid and eugenol, further alleviating the problem of continuous cropping obstacles.

[0042] In the present invention, the mass ratio of the reducing agent to the biochar precursor is 2 to 5:1, and in a specific embodiment, it can be 4:1 or 3:1.

[0043] In the present invention, a reducing agent and water are first mixed to obtain a reducing agent aqueous solution; the concentration of the reducing agent in the reducing agent aqueous solution is 5 to 20 wt %, and in a specific embodiment, it can be 10 wt % or 15 wt %;

[0044] In the present invention, the reduction temperature is 20-40°C, and in a specific embodiment, it can be 25°C or 30°C; the reduction time is 12-24h, and in a specific embodiment, it can be 14h or 16h.

[0045] In the present invention, after the reduction is completed, the obtained mixed solution is subjected to solid-liquid separation in sequence; the obtained solid phase is washed and dried in sequence to obtain the electron-rich biochar; the solid-liquid separation method is centrifugation; the washing is water washing; the present invention has no special limitation on the drying conditions.

[0046] The present invention also provides electron-rich biochar prepared by the preparation method described in the above technical solution.

[0047] The present invention also provides the use of the electron-rich biochar described in the above technical solution in degrading allelopathic substances and organic compound pollutants.

[0048] In the present invention, the organic pollutants include one or more of saponins, aliphatic acids and organic acids.

[0049] In the present invention, the allelopathic substances are allelopathic substances in soil; and the organic compound pollutants are antibiotic pollutants.

[0050] In order to further illustrate the present invention, the electron-rich biochar provided by the present invention and its preparation method and application are described in detail below in combination with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1

[0052] Corn stalks were pyrolyzed and carbonized in a muffle furnace under anaerobic conditions at 350°C. The carbonized biochar was ground, passed through a 50-mesh sieve, washed with water, and freeze-dried (4°C) to obtain a biochar precursor, which was recorded as W350.

[0053] 10 g of the above biochar precursor was mixed with 500 mL of a 5 wt% aqueous solution of KHB4, placed on a magnetic stirrer in a constant temperature reactor at 20°C for 24 h, and the obtained product was washed and dried in sequence to obtain electron-rich biochar, recorded as W350-M.

[0054] Example 2

[0055] Corn stalks were pyrolyzed and carbonized in a muffle furnace under anaerobic conditions at 700 °C, and the carbonized biochar was ground, passed through a 50-mesh sieve, washed with water, and freeze-dried to obtain a biochar precursor, which was recorded as W700.

[0056] 10 g of the above biochar precursor was mixed with 500 mL of a 5 wt% aqueous solution of KHB4, placed on a magnetic stirrer in a constant temperature reactor at 20°C for 24 h, and the obtained product was washed and dried in sequence to obtain electron-rich biochar, recorded as W700-M.

[0057] Test Example 1

[0058] 10 mg of the biochar precursor W350 and the electron-rich biochar W350-M obtained in Example 1 were mixed with 1 mL of 0.5% acetic acid solution and 10 mg of chitosan, respectively, and ultrasonically treated for 2 h to obtain an electrode film liquid; 10 μL of the above electrode film liquid was taken to prepare an electrode film, and the working electrode was obtained after drying; a platinum wire and a saturated calomel electrode were used as a counter electrode and a reference electrode, respectively, and a phosphate buffered saline solution was used as an electrolytic solution. A CHI760 constant position instrument was used to study the capacitance characteristics and electron transfer capacity of the biochar by cyclic voltammetry at room temperature. The results are as follows: Figure 1 shown.

[0059] Figure 1The capacitance diagram of biochar W350-M and W350 obtained in Example 1 is shown in FIG. Figure 1 It can be seen that the capacitance value of W350-M is 89.5μF / cm 2 The capacitance value of W350, which is not electron-enriched, increased by 14.6 μF / cm 2 .

[0060] In addition, the specific surface area of ​​the biochar precursor obtained in Example 1 was measured to be 4.98 mg / cm 2 .

[0061] A 100 mg / L ginsenoside solution was prepared in a brown glass bottle, and 25 mg of W350 and W350-M obtained in Example 1 were added respectively, and then placed in a constant temperature oscillator at 25°C and 150 rpm to study the removal of ginsenoside Rb1. The reaction was continued for 0.08 to 84 h. After the reaction, solid-liquid separation was performed, and the obtained supernatant was passed through a 0.45 μm aqueous phase syringe filter and transferred to a brown sample bottle. High performance liquid chromatography (HPLC, Agilent, 1260infinity) was used to determine the concentration of ginsenoside Rb1 remaining in the system. The above experiments were repeated 3 times to ensure repeatability. In order to distinguish the degradation and adsorption of ginsenoside Rb1, methanol extraction was performed after biochar adsorption, and then the extracted samples were analyzed by HPLC to determine the concentration of ginsenoside Rb1. The difference between total removal and actual adsorption represents the degradation of ginsenoside Rb1 by biochar. The results are shown in FIG. Figure 2 shown.

[0062] Figure 2 The removal capacity of biochar W350-M and W350 obtained in Example 1 for ginsenoside Rb1 is shown in FIG. Figure 2 It can be seen that at 84 h, the removal rate of ginsenoside Rb1 by W350 was about 11.89%, while the removal rate of ginsenoside Rb1 by W350-M was about 31.4%. KBH4 enhanced the physical and chemical removal of ginsenoside Rb1 by biochar.

[0063] Test Example 2

[0064] According to the standard soil sampling method, soil samples under different conditions were collected, including soil without crops (soil-0) and soil planted with Panax notoginseng for 2 years (soil-2) and 3 years (soil-3). After removing plant residues and roots, the soil samples were stored in a refrigerator at 4°C. Then 10g of soil sample was mixed with 0.5g of W350 and W350-M obtained in Example 1, respectively, and incubated at 25°C for 7d, and sterile water was added every day to maintain the soil moisture at 35%. Alpha and Beta diversity were analyzed, and the application of W350 and W350-M was tested to affect the changes in the structure of soil microbial communities under continuous cropping of Panax notoginseng. The results are shown below.

[0065] Figure 3 The graph of the change in the rhizosphere fungal community structure of Soil-2 soil mediated by biochar W350-M and W350 obtained in Example 1 is shown in Figure 1. Figure 3 It can be seen that the application of biochar reduced the abundance of pathogenic fungi in Soil-2. The inhibitory effect of W350-M on pathogenic fungi was more significant than that of W350.

[0066] Figure 4 The diagram of the change of rhizosphere fungal community structure of Soil-3 soil mediated by biochar W350-M and W350 obtained in Example 1 is shown in Figure 1. Figure 4 It can be seen that the application of biochar reduced the abundance of pathogenic fungi in Soil-3. The use of W350-M reduced the pathogenic fungi in soil-3 by 9.08%.

[0067] Figure 5 The diagram of the change of rhizosphere bacterial community structure of Soil-2 soil mediated by biochar W350-M and W350 obtained in Example 1 is shown in Figure 1. Figure 5 It can be seen that the application of biochar increased the abundance of electroactive bacteria in Soil-2. The promoting effect of W350-M on electroactive bacteria was more significant than that of W350.

[0068] Figure 6 The diagram of the change of rhizosphere bacterial community structure of Soil-3 soil mediated by biochar W350-M and W350 obtained in Example 1 is shown in Figure 1. Figure 6 It can be seen that the application of biochar increased the abundance of electroactive bacteria in Soil-3. The application of W350-M increased the abundance of electroactive bacteria in soil-3 by 13.68%.

[0069] Test Example 3

[0070] The capacitance characteristics, electron transfer capacity and removal capacity of ginsenoside Rb1 of W700 and W700-M obtained in Example 2 were tested according to the method shown in Test Example 1. The results are shown below.

[0071] Figure 7 The capacitance diagram of biochar W700-M and W700 obtained in Example 2 is shown in FIG. Figure 7 It can be seen that the capacitance value of W700-M is 387.70μF / cm 2 , compared with the capacitance value of 89.45 μF / cm of the biochar W350-M prepared in Example 1 2 In comparison, the capacitance value has increased nearly 5 times.

[0072] In addition, the specific surface area of ​​the biochar precursor obtained in Example 2 was measured to be 257.15 mg / cm 2 .

[0073] Figure 8 The removal capacity of biochar W700-M and W700 obtained in Example 2 for ginsenoside Rb1 is shown in FIG. Figure 8 It can be seen that the removal rate of ginsenoside Rb1 by W700 at 84h is 29.1mg / g, which is about twice that of the biochar W350 obtained in Example 1, mainly because the biochar formed at a higher pyrolysis temperature has a good porous structure; the removal rate of ginsenoside Rb1 by W700-M at 84h is 64.1mg / g, which is twice that of the unmodified W700.

[0074] Test Example 4

[0075] The effect of applying W700 and W700-M obtained in Example 2 on the structure of soil microorganisms in continuous cropping of Panax notoginseng was tested according to the method shown in Test Example 2. The results are shown below.

[0076] Fig. 9 The diagram of the change of rhizosphere fungal community structure of Soil-2 soil mediated by biochar W700-M and W700 obtained in Example 2 is shown in Figure 2. Fig. 9 It can be seen that the application of biochar reduced the abundance of pathogenic fungi in Soil-2. The fungal inhibitory effect was more significant than that of the biochar applied in Example 1, and the inhibitory effect was further enhanced after KHB4 reduction.

[0077] Fig.10 The graph of the change in the rhizosphere fungal community structure of Soil-3 mediated by biochar W700-M and W700 obtained in Example 2 is shown in Figure 2. Fig.10 It can be seen that the application of biochar reduced the abundance of pathogenic fungi in Soil-3. Compared with the soil without biochar application, the use of W700-M reduced the pathogenic fungi in soil-3 by 17.18%.

[0078] Fig.11 The diagram of the change of rhizosphere bacterial community structure of Soil-2 mediated by biochar W700-M and W700 obtained in Example 2 is shown in Figure 2. Fig.11 It can be seen that the application of biochar increased the abundance of electroactive bacteria in Soil-2. After the application of W700-M in Soil-2 soil, the abundance of electroactive bacteria increased by 77.61%, among which the abundance of Klebsiella increased by 24.93%.

[0079] Fig.12 The diagram of the change of rhizosphere bacterial community structure of Soil-3 soil mediated by biochar W700-M and W700 obtained in Example 2 is shown in Figure 2. Fig.12 It can be seen that the application of biochar increased the abundance of electroactive bacteria in Soil-3. The application of W700-M to Soil-3 soil increased the abundance of electroactive bacteria by 34.78%.

[0080] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing electron-rich biochar, characterized in that: The following steps are involved: The biomass raw material is pyrolyzed and carbonized under anaerobic conditions to obtain a biochar precursor; The biochar precursor, a reducing agent and water are mixed and reduced to obtain the electron-rich biochar; The reducing agent includes one or more of KHB4, NaBH4, LiBH4 and LiAlH4.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the reducing agent to the biochar precursor is 2 to 5:

1.

3. The preparation method according to claim 1, characterized in that: The temperature of the pyrolysis carbonization is 300-700° C., and the time is 12-24 hours.

4. The preparation method according to claim 1, characterized in that: The reduction temperature is 20-40° C. and the time is 12-24 hours.

5. The preparation method according to claim 1, characterized in that: The biomass raw material includes lignin-containing biomass and / or livestock manure.

6. The electron-rich biochar prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the electron-rich biochar according to claim 6 in degrading allelopathic substances and organic compound pollutants.

8. The use according to claim 7, characterized in that: The allelopathic substances include one or more of saponins, aliphatic acids and organic acids.

9. The use according to claim 7, characterized in that: The allelochemicals are allelochemicals in the soil.

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