Carbon-based soil conditioner and preparation method thereof

Abstract

The invention belongs to the technical field of soil improvement, and relates to a carbon-based soil conditioner and a preparation method thereof. According to the carbon-based soil conditioner provided by the invention, corncob biomass charcoal is prepared by performing micro-fermentation treatment on corncob powder by adopting ammonium bicarbonate before anaerobic cracking, then performing anaerobic cracking, and finally performing treatment by adopting sodium oxalate and microwave heating, so that the adsorption performance of the obtained corncob biomass charcoal can be greatly improved; therefore, the performance of the soil conditioner prepared from the corncob biomass charcoal is improved, and the soil conditioner is more favorable for improving the water and fertilizer retention capacity of soil, improving the air permeability and water permeability of the soil, adjusting the pH value of the soil and reducing the toxicity of heavy metals and organic pollutants in the soil.

Description

Technical Field

[0001] The invention belongs to the technical field of soil improvement and relates to a carbon-based soil conditioner and a preparation method thereof. Background Art

[0002] In recent years, the country has paid more and more attention to issues such as soil remediation and environmental protection. The issue of soil pollution prevention and control has been hotly discussed by industry insiders many times, among which soil heavy metal pollution and organic pollution have attracted widespread attention.

[0003] Heavy metals and organic pollutants in soil refer to chemical substances in the soil that are harmful to humans, animals, plants, and the ecological environment. Their presence may have serious impacts on soil ecosystems and human health. Heavy metal pollution mainly comes from industrial wastewater, waste, the use of fertilizers and pesticides, mining, coal emissions, transportation and other activities. The impact of heavy metals on human health and the ecological environment is mainly reflected in their toxicity and accumulation. For example, heavy metals such as lead, cadmium, and mercury can accumulate in soil and plants, and eventually cause harm to humans through the food chain, leading to health problems such as poisoning, damage to the nervous system, and suppression of the immune system. At the same time, the accumulation of heavy metals also has a negative impact on the soil ecosystem, inhibiting the activity of soil microorganisms, reducing soil fertility, and affecting plant growth.

[0004] Organic pollutants mainly come from industrial wastewater, pesticides, fertilizers, petroleum, fuel, garbage deposits, etc. These include benzene, polycyclic aromatic hydrocarbons, volatile organic compounds, etc. The impacts of organic pollutants on humans and the environment mainly include carcinogenicity, mutagenicity, immunotoxicity, reproductive toxicity, etc. Long-term exposure to these organic pollutants to human health will increase the risk of cancer, immune system disorders, etc. Organic pollutants also harm the soil ecosystem, causing changes in soil microbial communities, reducing soil productivity, and destroying the ecological balance of the soil.

[0005] Therefore, soil conditioner products that can effectively improve the content of heavy metals and organic pollutants in the soil have also received more and more attention. Soil conditioners, also known as soil improvers, are mainly used to improve the physical, chemical and biological properties of soil to make it more suitable for plant growth. Different types of soil conditioners have different effects.

[0006] Biochar-based amino acids are based on the unique microporous structure of biochar, and are formulated with different proportions of essential amino acids for plant growth to achieve the purpose of improving soil ecological environment, increasing aggregate structure, activating loose soil, promoting the stability of soil microbial community structure, and increasing soil fertilizer utilization efficiency; in addition, biochar-based amino acids combined with the role of soil microbial flora proliferation have a significant effect on increasing crop yield and improving quality. Faced with the challenge of declining soil quality, scientific researchers and agricultural experts have been tirelessly exploring effective methods for soil improvement and conditioning. Carbon-based soil conditioners have attracted much attention as a new type of soil conditioner. It uses carbon as its main ingredient, and plays a role in improving soil structure, increasing organic matter content, and improving soil water retention and fertility, and has a significant promoting effect on soil ecological environment and crop growth. And its main ingredient, carbon, has a wide range of sources, and can make full use of waste such as straw left over from crop harvests.

[0007] Traditional preparation methods usually include the crushing, carbonization, activation and other processes of carbon materials such as biochar and charcoal. However, the biochar produced by these methods has the problems of small surface area and poor adsorption capacity, and is not suitable for targeted treatment of heavy metals and organic pollutants in the soil.

[0008] Therefore, in view of the problems existing in traditional preparation methods, there is an urgent need for a carbon-based soil conditioner with strong adsorption capacity for heavy metals and organic pollutants, which can solve the soil pollution problem while enabling crop cultivation to achieve a more environmentally friendly cycle. Summary of the invention

[0009] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a carbon-based soil conditioner and a preparation method thereof.

[0010] The first aspect of the present invention provides a carbon-based soil conditioner, which comprises the following components by weight percentage:

[0011] Corn cob biochar 85-99%;

[0012] Fulvic acid 1-5%;

[0013] Polyglutamic acid 0.1-1.0%;

[0014] Glycine 0.1-0.3%;

[0015] Leucine 0.1-0.3%;

[0016] Proline 0.01-0.14%;

[0017] Tyrosine 0.01-0.14%;

[0018] Phenylalanine 0.01-0.11%.

[0019] Preferably, the carbon-based soil conditioner comprises the following components by weight percentage:

[0020] Corn cob biochar 90-97%;

[0021] Fulvic acid 2-4%;

[0022] Polyglutamic acid 0.3-0.8%;

[0023] Glycine 0.1-0.2%;

[0024] Leucine 0.1-0.2%;

[0025] Proline 0.04-0.10%;

[0026] Tyrosine 0.04-0.10%;

[0027] Phenylalanine 0.04-0.08%.

[0028] More preferably, the carbon-based soil conditioner comprises the following components by weight percentage:

[0029] Corn cob biochar 96%;

[0030] Fulvic acid 3%;

[0031] Polyglutamic acid 0.5%;

[0032] Glycine 0.15%;

[0033] Leucine 0.15%;

[0034] Proline 0.07%;

[0035] Tyrosine 0.07%;

[0036] Phenylalanine 0.06%.

[0037] Preferably, the corn cob biomass charcoal is biomass charcoal obtained by carbonizing corn cobs.

[0038] More preferably, the method for preparing corncob biochar comprises the following steps:

[0039] (1) corn cob pretreatment: the corn cob is crushed and passed through a 40-100 mesh sieve, then water is added and stirred evenly, and then the mixture is allowed to stand, filtered, and dried to obtain corn cob powder. The corn cob powder is then mixed with an ammonium bicarbonate solution having a mass concentration of 4% to 10% at a ratio of 1 g: (1-2) mL, and treated with micro-oxygen at room temperature for 5-7 days to obtain micro-fermented corn cob powder;

[0040] (2) Pyrolysis of corn cob powder: Pyrolyze the corn cob powder obtained in step (1) at 500-700° C. for 1-3 h to obtain corn cob biomass charcoal powder;

[0041] (3) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (2) and oxalate with a mass concentration of 5%-10% are mixed at a ratio of 1g:(0.5-1)mL, and microwave heating is used to obtain the corn cob biomass charcoal after drying.

[0042] Preferably, the pH value of the ammonium bicarbonate solution in step (1) is in the range of 7-8.

[0043] Preferably, in the pyrolysis environment of the corncob powder in step (2), the oxygen content is ≤100 ppm.

[0044] Preferably, the power of the microwave heating in step (3) is 800-1600 W, and the microwave heating time is 30-120 s.

[0045] Preferably, the oxalate in step (3) is one of sodium oxalate, ammonium oxalate and potassium oxalate; further preferably, the oxalate in step (3) is sodium oxalate.

[0046] The second aspect of the present invention provides a method for preparing a carbon-based soil conditioner, comprising: mixing the components according to a ratio to provide the desired carbon-based soil conditioner.

[0047] Preferably, the mixing condition is to first weigh the prepared corn cob biomass charcoal and corn cob biomass charcoal, weigh the weights of other components in proportion, and assemble and mix them uniformly in sequence.

[0048] The invention provides a carbon-based soil conditioner, wherein the corn cob biomass charcoal used is prepared by first using ammonium bicarbonate micro-fermentation to treat corn cob powder before anaerobic pyrolysis, then performing anaerobic pyrolysis, and finally treating with sodium oxalate and performing microwave heating, which can greatly improve the adsorption performance of the obtained corn cob biomass charcoal, thereby improving the performance of the soil conditioner prepared from the corn cob biomass charcoal, and is more conducive to improving the soil's water and fertilizer retention capacity, improving soil air permeability and water permeability, regulating soil pH, and reducing the toxicity of heavy metals and organic pollutants in the soil.

[0049] The present invention firstly uses ammonium bicarbonate to treat corn cob powder for micro-fermentation, which is beneficial to improving the adsorption capacity of corn cob biomass charcoal. This is because ammonium bicarbonate can effectively destroy the structure of corn cobs, so that they can be more fully carbonized under anaerobic conditions, and ammonium bicarbonate decomposes at high temperatures to form a large number of voids in the corn cob biomass charcoal, thereby increasing the specific surface area of ​​the obtained corn cob biomass charcoal, which is beneficial to improving the adsorption capacity of the corn cob biomass charcoal.

[0050] Then, the fermented corn cob powder is subjected to anaerobic pyrolysis to obtain corn cob biomass charcoal powder, and finally the corn cob biomass charcoal powder is subjected to microwave treatment, which can effectively improve its adsorption performance. In addition, the present invention also mixes the corn cob biomass charcoal powder with sodium oxalate solution before microwave treatment, and finds that the combination of the two can further improve the adsorption capacity of corn cob biomass charcoal. The present invention believes that this is because microwave treatment can promote the pyrolysis and carbonization process of biomass charcoal, making the pore structure of biomass charcoal more developed and the surface area increased. This increases the surface area of ​​biomass charcoal in contact with the adsorbed substance and improves the adsorption efficiency. In an aerobic environment, microwave treatment can also increase the active functional groups on the surface of biomass charcoal, such as hydroxyl (-OH), carboxyl (-COOH), etc. These functional groups have good affinity for adsorbing certain substances, thereby enhancing the adsorption capacity. Adding sodium oxalate can promote chemical changes in biomass charcoal during microwave treatment and increase its surface ion exchange capacity. The ions in sodium oxalate can react chemically with the functional groups on the surface of biomass charcoal, change the surface charge properties, and enhance the adsorption capacity of biomass charcoal for ionic substances.

[0051] Beneficial effects of the present invention

[0052] The invention provides a carbon-based soil conditioner, wherein the corn cob biomass charcoal used is prepared by first using ammonium bicarbonate micro-fermentation to treat corn cob powder before anaerobic pyrolysis, then performing anaerobic pyrolysis, and finally treating with sodium oxalate and performing microwave heating, which can greatly improve the adsorption performance of the obtained corn cob biomass charcoal, thereby improving the performance of the soil conditioner prepared from the corn cob biomass charcoal, and is more conducive to improving the soil's water and fertilizer retention capacity, improving soil air permeability and water permeability, regulating soil pH, and reducing the toxicity of heavy metals and organic pollutants in the soil. DETAILED DESCRIPTION

[0053] The present invention is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention.

[0054] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0055] The fulvic acid, polyglutamic acid, glycine, leucine, proline, tyrosine and phenylalanine are all commonly used amino acid components.

[0056] Example 1

[0057] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0058] Corn cob biochar 96%;

[0059] Fulvic acid 3%;

[0060] Polyglutamic acid 0.5%;

[0061] Glycine 0.15%;

[0062] Leucine 0.15%;

[0063] Proline 0.07%;

[0064] Tyrosine 0.07%;

[0065] Phenylalanine 0.06%.

[0066] The method for preparing corncob biochar comprises the following steps:

[0067] (1) Corn cob pretreatment: The corn cob is crushed and passed through a 40-mesh sieve, then water is added and stirred, and then the mixture is allowed to stand, filtered, and dried to obtain corn cob powder. The corn cob powder is then mixed with a 6% ammonium bicarbonate solution at a ratio of 1 g:2 mL, and treated with micro-oxygen at room temperature for 7 days to obtain micro-fermented corn cob powder.

[0068] (2) Pyrolysis of corn cob powder: Pyrolyze the corn cob powder obtained in step (1) at 600° C. for 2 h to obtain corn cob biomass charcoal powder;

[0069] (3) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (2) and oxalate with a mass concentration of 8% are mixed at a ratio of 1 g:0.6 mL, and microwave heating is used to obtain the corn cob biomass charcoal after drying.

[0070] The pH value range of the ammonium bicarbonate solution in step (1) is 7.5.

[0071] In step (2), the corncob powder pyrolysis environment has an oxygen content of ≤100 ppm.

[0072] The power of the microwave heating in step (3) is 1200 W, and the microwave heating time is 60 s.

[0073] The oxalate in step (3) is sodium oxalate.

[0074] Example 2

[0075] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0076] Corn cob biochar 96%;

[0077] Fulvic acid 3%;

[0078] Polyglutamic acid 0.5%;

[0079] Glycine 0.15%;

[0080] Leucine 0.15%;

[0081] Proline 0.07%;

[0082] Tyrosine 0.07%;

[0083] Phenylalanine 0.06%.

[0084] The method for preparing corncob biochar comprises the following steps:

[0085] The corncob is crushed and passed through a 40-mesh sieve, and then water is added and stirred evenly, and then allowed to stand, filtered, and dried to obtain corncob powder. The corncob powder is pyrolyzed at 600° C. for 2 hours to obtain the corncob biomass charcoal.

[0086] The corncob powder pyrolysis environment has an oxygen content of ≤100 ppm.

[0087] Example 3

[0088] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0089] Corn cob biochar 96%;

[0090] Fulvic acid 3%;

[0091] Polyglutamic acid 0.5%;

[0092] Glycine 0.15%;

[0093] Leucine 0.15%;

[0094] Proline 0.07%;

[0095] Tyrosine 0.07%;

[0096] Phenylalanine 0.06%.

[0097] The method for preparing corncob biochar comprises the following steps:

[0098] (1) Corn cob pretreatment: The corn cob is crushed and passed through a 40-mesh sieve, then water is added and stirred, and then the mixture is allowed to stand, filtered, and dried to obtain corn cob powder. The corn cob powder is then mixed with a 6% ammonium bicarbonate solution at a ratio of 1 g:2 mL, and treated with micro-oxygen at room temperature for 7 days to obtain micro-fermented corn cob powder.

[0099] (2) Pyrolysis of corn cob powder: Pyrolyze the corn cob powder obtained in step (1) at 600° C. for 2 h to obtain the corn cob biochar.

[0100] The pH value range of the ammonium bicarbonate solution in step (1) is 7.5.

[0101] In step (2), the corncob powder pyrolysis environment has an oxygen content of ≤100 ppm.

[0102] Example 4

[0103] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0104] Corn cob biochar 96%;

[0105] Fulvic acid 3%;

[0106] Polyglutamic acid 0.5%;

[0107] Glycine 0.15%;

[0108] Leucine 0.15%;

[0109] Proline 0.07%;

[0110] Tyrosine 0.07%;

[0111] Phenylalanine 0.06%.

[0112] The method for preparing corncob biochar comprises the following steps:

[0113] (1) Corn cob pretreatment: The corn cob is crushed and passed through a 40-mesh sieve, then water is added and stirred, and then the mixture is allowed to stand, filtered, and dried to obtain corn cob powder. The corn cob powder is pyrolyzed at 600° C. for 2 h to obtain corn cob biomass charcoal powder;

[0114] (2) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (1) and oxalate with a mass concentration of 8% are mixed at a ratio of 1 g:0.6 mL, and the mixture is heated by microwave and dried to obtain the corn cob biomass charcoal.

[0115] The corncob powder pyrolysis environment in step (1) has an oxygen content of ≤100 ppm.

[0116] The power of the microwave heating in step (2) is 1200 W, and the microwave heating time is 60 s.

[0117] The oxalate in step (2) is sodium oxalate.

[0118] Example 5

[0119] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0120] Corn cob biochar 96%;

[0121] Fulvic acid 3%;

[0122] Polyglutamic acid 0.5%;

[0123] Glycine 0.15%;

[0124] Leucine 0.15%;

[0125] Proline 0.07%;

[0126] Tyrosine 0.07%;

[0127] Phenylalanine 0.06%.

[0128] The method for preparing corncob biochar comprises the following steps:

[0129] (1) Corn cob pretreatment: The corn cob is crushed and passed through a 40-mesh sieve, then water is added and stirred, and then the mixture is allowed to stand, filtered, and dried to obtain corn cob powder. The corn cob powder is then mixed with a 6% ammonium bicarbonate solution at a ratio of 1 g:2 mL, and treated with micro-oxygen at room temperature for 7 days to obtain micro-fermented corn cob powder.

[0130] (2) Pyrolysis of corn cob powder: Pyrolyze the corn cob powder obtained in step (1) at 600° C. for 2 h to obtain corn cob biomass charcoal powder;

[0131] (3) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (2) is heated by microwaves and dried to obtain the corn cob biomass charcoal.

[0132] The pH value range of the ammonium bicarbonate solution in step (1) is 7.5.

[0133] In step (2), the corncob powder pyrolysis environment has an oxygen content of ≤100 ppm.

[0134] The power of the microwave heating in step (3) is 1200 W, and the microwave heating time is 60 s.

[0135] Example 6

[0136] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0137] Corn cob biochar 96%;

[0138] Fulvic acid 3%;

[0139] Polyglutamic acid 0.5%;

[0140] Glycine 0.15%;

[0141] Leucine 0.15%;

[0142] Proline 0.07%;

[0143] Tyrosine 0.07%;

[0144] Phenylalanine 0.06%.

[0145] The method for preparing corncob biochar comprises the following steps:

[0146] (1) Corn cob pretreatment: The corn cob is crushed and passed through a 40-mesh sieve, then water is added and stirred, and then allowed to stand, filtered, and dried to obtain corn cob powder, which is then treated with micro-oxygen at room temperature for 7 days to obtain micro-fermented corn cob powder;

[0147] (2) Pyrolysis of corn cob powder: Pyrolyze the corn cob powder obtained in step (1) at 600° C. for 2 h to obtain corn cob biomass charcoal powder;

[0148] (3) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (2) and oxalate with a mass concentration of 8% are mixed at a ratio of 1 g:0.6 mL, and microwave heating is used to obtain the corn cob biomass charcoal after drying.

[0149] In step (2), the corncob powder pyrolysis environment has an oxygen content of ≤100 ppm.

[0150] The power of the microwave heating in step (3) is 1200 W, and the microwave heating time is 60 s.

[0151] The oxalate in step (3) is sodium oxalate.

[0152] Comparative Example 1

[0153] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0154] Corn straw biochar 96%;

[0155] Fulvic acid 3%;

[0156] Polyglutamic acid 0.5%;

[0157] Glycine 0.15%;

[0158] Leucine 0.15%;

[0159] Proline 0.07%;

[0160] Tyrosine 0.07%;

[0161] Phenylalanine 0.06%.

[0162] The method for preparing corn straw biochar comprises the following steps:

[0163] (1) Corn straw pretreatment: The corn straw was crushed and passed through a 40-mesh sieve, and then water was added and stirred, and then the mixture was allowed to stand, filtered, and dried to obtain corn straw powder. The corn straw powder was then mixed with a 6% ammonium bicarbonate solution at a ratio of 1 g:2 mL, and treated with micro-oxygen at room temperature for 7 days to obtain micro-fermented corn straw powder.

[0164] (2) Pyrolysis of corn straw powder: Pyrolyze the corn straw powder obtained in step (1) at 600° C. for 2 h to obtain corn straw biomass charcoal powder;

[0165] (3) Microwave treatment of corn straw biomass charcoal powder: The corn straw biomass charcoal powder obtained in step (2) and oxalate with a mass concentration of 8% are mixed at a ratio of 1 g:0.6 mL, and the mixture is heated by microwave and dried to obtain the corn straw biomass charcoal.

[0166] The pH value range of the ammonium bicarbonate solution in step (1) is 7.5.

[0167] In step (2), the corn stalk powder pyrolysis environment has an oxygen content of ≤100 ppm.

[0168] The power of the microwave heating in step (3) is 1200 W, and the microwave heating time is 60 s.

[0169] The oxalate in step (3) is sodium oxalate.

[0170] Comparative Example 2

[0171] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0172] Wheat straw biochar 96%;

[0173] Fulvic acid 3%;

[0174] Polyglutamic acid 0.5%;

[0175] Glycine 0.15%;

[0176] Leucine 0.15%;

[0177] Proline 0.07%;

[0178] Tyrosine 0.07%;

[0179] Phenylalanine 0.06%.

[0180] The method for preparing wheat straw biochar comprises the following steps:

[0181] (1) Pretreatment of wheat straw: The wheat straw was crushed and passed through a 40-mesh sieve, then water was added and stirred, and then the mixture was allowed to stand, filtered, and dried to obtain wheat straw powder. The wheat straw powder was then mixed with a 6% ammonium bicarbonate solution at a ratio of 1 g:2 mL, and treated with micro-oxygen at room temperature for 7 days to obtain micro-fermented wheat straw powder.

[0182] (2) Pyrolysis of wheat straw powder: Pyrolyze the wheat straw powder obtained in step (1) at 600° C. for 2 h to obtain wheat straw biomass charcoal powder;

[0183] (3) Microwave treatment of wheat straw biomass charcoal powder: The wheat straw biomass charcoal powder obtained in step (2) and oxalate with a mass concentration of 8% are mixed at a ratio of 1 g:0.6 mL, and the mixture is heated by microwave and dried to obtain the wheat straw biomass charcoal.

[0184] The pH value range of the ammonium bicarbonate solution in step (1) is 7.5.

[0185] In step (2), the oxygen content in the pyrolysis environment of the wheat straw powder is ≤100 ppm.

[0186] The power of the microwave heating in step (3) is 1200 W, and the microwave heating time is 60 s.

[0187] The oxalate in step (3) is sodium oxalate.

[0188] Comparative Example 3

[0189] A carbon-based soil conditioner, comprising the following components by weight percentage:

[0190] Corn cob biochar 96%;

[0191] Fulvic acid 3%;

[0192] Polyglutamic acid 0.5%;

[0193] Glycine 0.15%;

[0194] Leucine 0.15%;

[0195] Proline 0.07%;

[0196] Tyrosine 0.07%;

[0197] Phenylalanine 0.06%.

[0198] The method for preparing corncob biochar comprises the following steps:

[0199] (1) Corn cob pretreatment: The corn cob is crushed and passed through a 40-mesh sieve, then water is added and stirred, and then the mixture is allowed to stand, filtered, and dried to obtain corn cob powder. The corn cob powder is then mixed with a 6% ammonium bicarbonate solution at a ratio of 1 g:2 mL, and treated with micro-oxygen at room temperature for 7 days to obtain micro-fermented corn cob powder.

[0200] (2) Pyrolysis of corn cob powder: Pyrolyze the corn cob powder obtained in step (1) at 600° C. for 2 h to obtain corn cob biomass charcoal powder;

[0201] (3) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (2) and oxalate with a mass concentration of 8% are mixed at a ratio of 1 g:0.6 mL, and microwave heating is used to obtain the corn cob biomass charcoal after drying.

[0202] The pH value range of the ammonium bicarbonate solution in step (1) is 7.5.

[0203] In step (2), the corncob powder pyrolysis environment has an oxygen content of ≤100 ppm.

[0204] The power of the microwave heating in step (3) is 1200 W, and the microwave heating time is 60 s.

[0205] The oxalate in step (3) is ammonium oxalate.

[0206] Test Example 1

[0207] Adsorption performance test

[0208] Configure standard wastewater for testing: BOD content 100mg / L, Cr6+ content 0.2mg / L.

[0209] At room temperature, 0.5 g of the biochar prepared in the embodiment and the comparative example was added to 1 L of the test standard wastewater, stirred at 400 r / min for 60 min, left to stand for 60 min, and filtered through a membrane to obtain purified water. The BOD content and Cr content of the purified water were determined. 6+ content and calculate the removal rate.

[0210] The BOD content test adopts the "GB / T 7488-87 Water Quality Five-Day Biochemical Oxygen Demand (BOD5) Dilution and Inoculation Method".

[0211] Cr 6+ The content test adopts "GB / T 7467-87 Water Quality Determination of Hexavalent Chromium-Diphenylcarbazide Spectrophotometric Method".

[0212] Table 1: Adsorption performance test results

[0213]

[0214]

[0215] It can be seen from Table 1 that the corn cob biochar prepared in Example 1 of the present invention has the best adsorption performance and the highest removal rate of organic matter and metal ions, which indicates that it can more efficiently adsorb heavy metals and organic pollutants in the soil and reduce their toxic effects on plants.

[0216] The adsorption capacity of corn cob biochar obtained by anaerobic pyrolysis in Example 2 is significantly lower than that in Example 1. In Example 4, corn cob powder is not treated with ammonium bicarbonate solution, and corn cob biochar obtained by anaerobic pyrolysis is significantly lower than that in Example 1. In Example 6, corn cob powder is not treated with ammonium bicarbonate solution, and its performance is significantly lower than that in Example 1, which indicates that the micro-fermentation of corn cob powder treated with ammonium bicarbonate before anaerobic pyrolysis is beneficial to improve the adsorption capacity of corn cob biochar. The present invention believes that this is because ammonium bicarbonate can effectively destroy the structure of corn cobs, so that it can be more fully carbonized under anaerobic conditions, and ammonium bicarbonate decomposes at high temperature, which can form a large number of voids in the corn cob biochar, and improve the specific surface area of ​​the obtained corn cob biochar, which is beneficial to improve the adsorption capacity of corn cob biochar.

[0217] Compared with Example 1, Example 3 did not perform microwave treatment on corn cob biochar, and its adsorption capacity decreased significantly. Compared with Example 1, Example 5 did not add sodium oxalate during the microwave treatment process, and its adsorption performance also decreased compared with Example 1. This shows that microwave treatment of carbonized corn cob powder can effectively improve its adsorption performance. In addition, the addition of sodium oxalate helps to microwave the corn cob biochar, and the combination of the two can better improve the adsorption capacity of corn cob biochar. The present invention believes that this is because microwave treatment can promote the pyrolysis and carbonization process of biochar, making the pore structure of biochar more developed and the surface area increased. This increases the surface area of ​​biochar in contact with the adsorbent and improves the adsorption efficiency. In an aerobic environment, microwave treatment can also increase the active functional groups on the surface of biochar, such as hydroxyl (-OH), carboxyl (-COOH), etc. These functional groups have good affinity for adsorbing certain substances, thereby enhancing the adsorption capacity. Adding sodium oxalate can promote chemical changes in biochar during microwave treatment and increase its surface ion exchange capacity. The ions in sodium oxalate can react chemically with the functional groups on the surface of biochar, changing the surface charge properties and enhancing the adsorption capacity of biochar for ionic substances.

[0218] Comparative Example 1 and Comparative Example 2 replace corn cobs with corn stalks and wheat straws, respectively, and the adsorption capacity of the biochar obtained is slightly lower than that of Example 1, which indicates that corn cobs are more suitable for the biochar preparation method of the present invention. This method believes that corn stalks, wheat straws and corn cobs may differ in the content and structure of components such as cellulose, hemicellulose and lignin, which have an important influence on the formation and properties of biochar, and different compositions and structures may result in different adsorption properties of biochar. The adsorption capacity of biochar is related to its pore structure. The pore structure of biochar prepared from different raw materials may be different, including pore size, distribution, and chemical properties of the pore wall. The structure of corn stalks and wheat straws may cause the pore structure of biochar to be different from that of corn cobs, thereby affecting its adsorption capacity.

[0219] Comparative Example 3 uses ammonium oxalate to replace the sodium oxalate treatment agent in microwave heating, and the adsorption capacity of the corn cob biochar obtained is also slightly lower than that of Example 1, which shows that sodium oxalate is better than ammonium oxalate in the method of microwave treatment of biochar. The present invention believes that this is because ammonium oxalate contains amino ions, which may affect the reaction with the carbon surface. Sodium oxalate does not contain amino ions, so it may be easier to react in some cases.

[0220] It can be seen from the above test examples that the adsorption performance of the obtained corn cob biochar can be greatly improved by first treating the corn cob powder with micro-fermentation, then performing anaerobic pyrolysis, and finally treating it with sodium oxalate and performing microwave heating, thereby improving the performance of the soil conditioner made from corn cob biochar, and is more conducive to improving the soil's ability to retain water and fertilizer, improving soil aeration and water permeability, regulating soil pH, and reducing the toxicity of heavy metals and organic pollutants in the soil.

Claims

1. A carbon-based soil conditioner, characterized in that: By weight percentage, it includes the following components: Corn cob biochar 85-99%; Fulvic acid 1-5%; Polyglutamic acid 0.1-1.0%; Glycine 0.1-0.3%; Leucine 0.1-0.3%; Proline 0.01-0.14%; Tyrosine 0.01-0.14%; Phenylalanine 0.01-0.11%.

2. The carbon-based soil conditioner according to claim 1, characterized in that: By weight percentage, it includes the following components: Corn cob biochar 90-97%; Fulvic acid 2-4%; Polyglutamic acid 0.3-0.8%; Glycine 0.1-0.2%; Leucine 0.1-0.2%; Proline 0.04-0.10%; Tyrosine 0.04-0.10%; Phenylalanine 0.04-0.08%.

3. The carbon-based soil conditioner according to claim 2, characterized in that: The carbon-based soil conditioner comprises the following components by weight percentage: Corn cob biochar 96%; Fulvic acid 3%; Polyglutamic acid 0.5%; Glycine 0.15%; Leucine 0.15%; Proline 0.07%; Tyrosine 0.07%; Phenylalanine 0.06%.

4. The carbon-based soil conditioner according to claims 1-3, characterized in that: The method for preparing corncob biochar comprises the following steps: (1) corn cob pretreatment: the corn cobs are crushed and sieved, the corn cob powder is mixed with an ammonium bicarbonate solution, and subjected to micro-oxygen treatment to obtain micro-fermented corn cob powder; (2) Pyrolysis of corn cob powder: Pyrolyzing the corn cob powder obtained in step (1) to obtain corn cob biomass charcoal powder; (3) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (2) is mixed with oxalate, heated by microwaves, and dried to obtain the corn cob biomass charcoal.

5. The carbon-based soil conditioner according to claim 4, characterized in that: The method for preparing corncob biochar comprises the following steps: (1) corn cob pretreatment: the corn cob is crushed and passed through a 40-100 mesh sieve, then water is added and stirred evenly, and then the mixture is allowed to stand, filtered, and dried to obtain corn cob powder. The corn cob powder is then mixed with an ammonium bicarbonate solution having a mass concentration of 4% to 10% at a ratio of 1 g: (1-2) mL, and treated with micro-oxygen at room temperature for 5-7 days to obtain micro-fermented corn cob powder; (2) Pyrolysis of corn cob powder: Pyrolyze the corn cob powder obtained in step (1) at 500-700° C. for 1-3 h to obtain corn cob biomass charcoal powder; (3) Microwave treatment of corn cob biomass charcoal powder: The corn cob biomass charcoal powder obtained in step (2) and oxalate with a mass concentration of 5%-10% are mixed at a ratio of 1g:(0.5-1)mL, and microwave heating is used to obtain the corn cob biomass charcoal after drying.

6. The carbon-based soil conditioner according to claim 5, characterized in that: The pH value of the ammonium bicarbonate solution in step (1) is in the range of 7-8.

7. The carbon-based soil conditioner according to claim 5, characterized in that: In step (2), the corncob powder pyrolysis environment has an oxygen content of ≤100 ppm.

8. The carbon-based soil conditioner according to claim 5, characterized in that: The power of the microwave heating in step (3) is 800-1600W, and the microwave heating time is 30-120s.

9. The carbon-based soil conditioner according to claim 5, characterized in that: The oxalate in step (3) is one of sodium oxalate, ammonium oxalate and potassium oxalate.

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