Thermochemical oxidation preparation process of straw biomass charcoal

Abstract

The invention provides a thermochemical oxidation preparation process of straw biomass charcoal, and relates to the technical field of related adsorption methods, the prepared biomass charcoal has higher specific surface area and porosity, more reasonable element composition and higher specific surface area and porosity by accurately controlling pretreatment and reaction conditions of straw and introducing emerging technologies such as microwave-assisted heating and ultrasonic treatment, and the biomass charcoal can be used for preparing biomass charcoal. According to the present invention, the microwave-assisted heating and the precise heating rate control are adopted, such that the reaction efficiency is substantially improved, the energy consumption is reduced, the preparation time is shortened, the purification manner of combining the acid washing and the alkali washing with the ultrasonic treatment can effectively remove the impurities, and the purity of the biomass charcoal is improved; the stability and reliability of the biomass charcoal in various applications are enhanced, the surface chemical property of the biomass charcoal is improved by the plasma treatment technology, active sites are increased, the microstructure change in the reaction process is monitored in real time by the in-situ characterization technology, and a powerful basis is provided for process optimization.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorption-related methods, and more specifically, particularly relates to a process for preparing straw biochar by thermochemical oxidation. Background Art

[0002] With the continuous growth of global energy demand and the increasingly severe environmental problems, it is imperative to find renewable and environmentally friendly energy solutions. In this context, biomass energy, as an abundant, renewable and relatively clean energy resource, has received widespread attention. As an important component of agricultural waste, the resource utilization of straw is of great significance.

[0003] Traditional methods of straw treatment, such as burning or returning directly to the field, have many problems. Burning can cause serious air pollution and waste of resources, while returning directly to the field may cause problems such as the spread of pests and diseases and damage to soil structure. Therefore, converting straw into high-value-added products, such as biochar, has become a hot topic of research.

[0004] In the prior art, there are some limitations in the preparation process of straw biochar. Many traditional processes are difficult to accurately control the reaction conditions during the preparation process, resulting in unstable product quality and performance. For example, the control of parameters such as reaction temperature, atmosphere and time is not precise enough, making it difficult for key indicators such as the pore structure, specific surface area and elemental composition of biochar to reach the ideal level, thus limiting its application in adsorption, energy storage and soil improvement.

[0005] At the same time, traditional processes often have poor results in the purification process and cannot effectively remove impurities, which affects the purity and performance of biochar. Moreover, the existing processes also need to be improved in terms of energy efficiency, with problems such as high energy consumption and long reaction time, which increases production costs and environmental burdens.

[0006] In addition, the research on microstructure changes and reaction mechanisms during the preparation process is not in-depth enough, and there is a lack of effective in-situ monitoring and analysis methods, making it difficult to accurately optimize and improve the process. In practical applications, existing straw biochar products are also difficult to meet the increasingly diverse and high-standard market demands in terms of performance and stability.

[0007] In summary, in order to achieve efficient resource utilization of straw, improve the quality and performance of biochar, and reduce production costs and environmental impacts, the development of an innovative, precisely controllable straw biochar thermochemical oxidation preparation process has important practical significance and broad application prospects. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a process for preparing straw biochar by thermochemical oxidation to solve the above problems.

[0009] A process for preparing straw biochar by thermochemical oxidation, comprising the following steps:

[0010] Step A: pre-treat the straw to remove impurities, first crush the straw into small pieces with a length of 1-3 cm, then rinse with clean water for 3 times, and then dry in a drying oven at 60°C for 2 hours;

[0011] Step B: placing the pretreated straw in a reaction vessel made of stainless steel with a volume of 50 liters, the reaction vessel being equipped with a real-time temperature and pressure monitoring system;

[0012] Step C: carrying out a thermochemical oxidation reaction at a temperature of 400-600° C., an atmosphere with an oxygen content of 20%-30% and a nitrogen content of 70%-80%, wherein the reaction time t is calculated according to the formula t=k×(T-T0) / P, wherein k is a reaction rate constant, T is a reaction temperature, T0 is an initial temperature, and P is an oxygen partial pressure. The reaction rate constant k is 0.05, the initial temperature T0 is 25° C., and the oxygen partial pressure P is 0.2 MPa. Microwave-assisted heating is used during the reaction, and the microwave power is 500 W.

[0013] Step D: After the reaction is completed, the reaction is naturally cooled to room temperature, and the unpurified straw biochar obtained after the thermochemical oxidation reaction is completed is collected. During the cooling process, an infrared thermometer is used to monitor the product temperature in this step in real time;

[0014] Step E: The product collected in step D is further purified by a combination of acid washing and alkali washing, wherein the acid washing uses a 5% hydrochloric acid solution, and the alkali washing uses a 3% sodium hydroxide solution. Ultrasonic treatment is introduced into the purification process, the ultrasonic frequency is 40 kHz, and the treatment time is 30 minutes;

[0015] Step F: The product purified in step E is subjected to performance testing to test its specific surface area, porosity and elemental composition. The specific surface area is measured by BET method, the porosity is determined by mercury intrusion method, and the elemental composition is analyzed by X-ray fluorescence spectrometer. Artificial intelligence algorithm is used to analyze the test data and optimize process parameters.

[0016] Preferably, in the step A, the average diameter of the crushed straw particles is 0.5-1 cm, and in the step B, the inner wall of the reaction container is treated with a high temperature resistant coating.

[0017] Preferably, in the step C, the heating rate is controlled at 10°C / min, and in the step D, during the natural cooling process, the temperature of the unpurified straw biochar obtained after the thermochemical oxidation reaction is measured every 30 minutes.

[0018] Preferably, in step E, the acid washing time is 1 hour and the alkali washing time is 1.5 hours.

[0019] Preferably, in step F, the artificial intelligence algorithm is a neural network algorithm based on deep learning.

[0020] Preferably, the straw biochar obtained after the treatment in step A to step F is surface modified by plasma treatment technology, with a treatment time of 10 minutes and a power of 1 kW.

[0021] Preferably, the working gas in the plasma treatment process is argon, and the gas flow rate is 10 L / min.

[0022] Preferably, in-situ characterization techniques are used to monitor microstructural changes during the thermochemical oxidation reaction in real time.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Significantly improve the quality and performance of biochar: By precisely controlling the pretreatment of straw, reaction conditions and introducing emerging technologies such as microwave-assisted heating and ultrasonic treatment, the prepared biochar has a higher specific surface area and porosity, and a more reasonable elemental composition, which enables it to have better performance in the fields of adsorption and energy storage.

[0025] 2. High efficiency and energy saving: The use of microwave-assisted heating and precise heating rate control greatly improves the reaction efficiency, reduces energy consumption and shortens the preparation time.

[0026] 3. Optimized purification process: The purification method of acid washing and alkaline washing combined with ultrasonic treatment can more effectively remove impurities, improve the purity of biochar, and enhance its stability and reliability in various applications.

[0027] 4. Innovative surface modification and microstructure monitoring: Plasma treatment technology improves the surface chemical properties of biochar and increases active sites. In-situ characterization technology monitors the microstructure changes during the reaction in real time, providing a strong basis for process optimization and further improving product quality.

[0028] 5. Precise process control: Real-time temperature and pressure monitoring systems and data analysis based on artificial intelligence algorithms enable precise control of the preparation process and optimization of process parameters, ensuring the consistency and stability of product performance.

[0029] 6. Wide adaptability of raw materials: It can process various types of straw raw materials, including wheat straw, corn straw, rice straw, etc., as well as their mixed raw materials, which improves the utilization rate of raw materials and the applicability of the process.

[0030] 7. Environmentally friendly: This process reduces the emission of pollutants during the preparation process. At the same time, the biochar produced can be used in environmental protection fields such as soil improvement and wastewater treatment, realizing the resource utilization of straw and reducing environmental pressure.

[0031] 8. Promote the development of related fields: The prepared high-performance biochar can improve soil fertility and water retention capacity in soil improvement, promote sustainable agricultural development; it can effectively remove pollutants and protect water resources in wastewater treatment; it shows good application prospects in the field of energy storage, and provides strong support for the new energy industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0033] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0034] As the world's attention to renewable energy and environmental protection continues to increase, the preparation of straw biochar has become an important research field. The present invention provides an innovative thermochemical oxidation preparation process for straw biochar, which aims to improve the quality and performance of biochar to meet the application requirements of different fields. The specific implementation method of the process will be introduced in detail below, and its effectiveness and superiority will be verified through multiple examples and data support.

[0035] Process steps:

[0036] 1. Straw pretreatment: Collect fresh straw, including but not limited to wheat straw, corn straw and rice straw, etc., first perform preliminary sorting to remove obvious impurities such as stones, plastics, etc., put the straw into a crusher for crushing, and control the length of the crushed straw to be between 1-3 cm and the average diameter to be about 0.5-1 cm. Then, place the crushed straw in a cleaning pool and rinse it with clean water for 3 times to remove attached soil and fine impurities. Finally, put the washed straw into a drying oven at 60°C for 2 hours to ensure that the moisture content of the straw is less than 10%;

[0037]

[0038] 2. Preparation of reaction vessel: A reaction vessel made of stainless steel with a capacity of 50 liters is selected. The inner wall of the reaction vessel is treated with a high-temperature resistant coating to improve its service life and corrosion resistance. The reaction vessel is equipped with a real-time temperature and pressure monitoring system, including a thermocouple and a pressure sensor, to ensure that the temperature and pressure changes during the reaction process can be accurately monitored;

[0039]

[0040] 3. Thermochemical oxidation reaction: Place the pretreated straw evenly in the reaction vessel, set the reaction atmosphere to 20%-30% oxygen content and 70%-80% nitrogen content, raise the reaction temperature to 400-600°C at a heating rate of 10°C / min, use microwave assisted heating during the reaction, and the microwave power is 500W to promote the uniformity of the reaction and improve the reaction efficiency. Calculate the reaction time according to the formula t=k×(T-T0) / P, where k is 0.05, the initial temperature T0 is 25°C, and the oxygen partial pressure P is 0.2MPa. For example, when the reaction temperature is 500°C, the reaction time is about 2.25 hours;

[0041]

[0042]

[0043] 4. Cooling and product collection: After the reaction is completed, the product is allowed to cool naturally to room temperature. During the cooling process, an infrared thermometer is used to measure the product temperature every 30 minutes to monitor the cooling progress. After the cooling is completed, the straw biochar product generated by the reaction is collected;

[0044]

[0045] 5. Purification: The product is purified by a combination of acid washing and alkali washing. A 5% hydrochloric acid solution is used for acid washing. The product is immersed in the acid washing solution for 1 hour with constant stirring to remove metal impurities and some inorganic compounds. After the acid washing, the product is rinsed with clean water until it is neutral. Then, an alkali washing is performed using a 3% sodium hydroxide solution for 1.5 hours to further remove residual impurities and adjust the surface properties of the product. After the alkali washing, the product is rinsed with clean water again until it is neutral and dried.

[0046]

[0047] 6. Performance testing and analysis: The purified product is subjected to performance testing, including specific surface area, porosity and elemental composition. The specific surface area is measured by the BET method, using nitrogen as the adsorbent, and adsorption and desorption experiments are carried out at liquid nitrogen temperature. The specific surface area is calculated based on the measured data. The porosity is measured by the mercury intrusion method, in which the product is placed in a mercury intrusion instrument and pressure is applied to allow mercury to enter the pores. The porosity is calculated based on the pressure and the amount of mercury entering. The elemental composition is analyzed by X-ray fluorescence spectrometer to determine the content of carbon, hydrogen, oxygen, nitrogen and other elements in the product.

[0048] Ultrasonic treatment was introduced in the purification process with an ultrasonic frequency of 40kHz and a treatment time of 30 minutes to enhance the effects of acid washing and alkaline washing and improve the efficiency of impurity removal. The detection data was analyzed using a neural network algorithm based on deep learning, and a relationship model between process parameters and product performance was established to optimize future preparation process parameters. The product was surface modified using plasma treatment technology with a treatment time of 10 minutes, a power of 1kW, argon as the working gas, and a gas flow rate of 10L / min to improve the surface chemical properties of the product and increase active sites. In situ characterization techniques such as in situ X-ray diffraction and in situ infrared spectroscopy were used to monitor the microstructural changes during the thermochemical oxidation reaction in real time to gain a deeper understanding of the reaction mechanism.

[0049] Embodiment 1:

[0050] Wheat straw is selected as raw material, crusher, cleaning tank, drying box, stainless steel reaction container, thermocouple, pressure sensor, microwave generator, infrared thermometer, hydrochloric acid, sodium hydroxide, ultrasonic cleaner, X-ray fluorescence spectrometer, BET specific surface area analyzer, mercury intrusion meter, etc.

[0051] The straw crushing length is 2 cm, the average diameter is 0.8 cm, the reaction atmosphere is 25% oxygen content and 75% nitrogen content, the reaction temperature is 500°C, the heating rate is 10°C / minute, the microwave power is 500W, the reaction time is calculated to be 2.25 hours, the acid washing time is 1 hour, the alkali washing time is 1.5 hours, the ultrasonic frequency is 40kHz, and the treatment time is 30 minutes.

[0052] Experimental results: The specific surface area of ​​the product was measured by BET method and was 350 m 2 / g, the porosity is 0.65 as measured by mercury intrusion porosimetry, and the elemental composition analysis shows that the carbon content is 75%, the hydrogen content is 3%, the oxygen content is 18%, and the nitrogen content is 4%.

[0053] Embodiment 2:

[0054] Corn stalks were used as raw materials, and the same equipment as in Example 1 was used. The stalk crushing length was 1 cm, the average diameter was 0.5 cm, the reaction atmosphere was 20% oxygen and 80% nitrogen, the reaction temperature was 400°C, the heating rate was 10°C / min, the microwave power was 500 W, the reaction time was calculated to be 1.5 hours, the acid washing time was 1 hour, the alkali washing time was 1.5 hours, the ultrasonic frequency was 40 kHz, and the treatment time was 30 minutes.

[0055] Experimental results: The specific surface area of ​​the product was measured by BET method and was 280 m 2 / g, the porosity is 0.55 as measured by mercury intrusion porosimetry, and the elemental composition analysis shows that the carbon content is 70%, the hydrogen content is 4%, the oxygen content is 22%, and the nitrogen content is 4%.

[0056] Embodiment 3:

[0057] Rice straw was used as raw material, and the same equipment as in Example 1 was used. The straw was crushed to a length of 3 cm and an average diameter of 1 cm. The reaction atmosphere was an oxygen content of 30% and a nitrogen content of 70%. The reaction temperature was 600°C, the heating rate was 10°C / min, the microwave power was 500 W, the reaction time was calculated to be 3 hours, the acid washing time was 1 hour, the alkali washing time was 1.5 hours, the ultrasonic frequency was 40 kHz, and the treatment time was 30 minutes.

[0058] Experimental results: The specific surface area of ​​the product was measured by BET method and was 420 m 2 / g, the porosity is 0.70 as measured by mercury intrusion porosimetry, and the elemental composition analysis shows that the carbon content is 80%, the hydrogen content is 2%, the oxygen content is 15%, and the nitrogen content is 3%.

[0059] Embodiment 4:

[0060] Wheat straw and corn straw were mixed in a mass ratio of 1:1 as raw materials. The same equipment as in Example 1 was used. The straw crushing length was 2 cm and the average diameter was 0.7 cm. The reaction atmosphere was an oxygen content of 25% and a nitrogen content of 75%. The reaction temperature was 550°C, the heating rate was 10°C / min, the microwave power was 500 W, the reaction time was calculated to be 2.5 hours, the acid washing time was 1 hour, the alkali washing time was 1.5 hours, the ultrasonic frequency was 40 kHz, and the treatment time was 30 minutes.

[0061] Experimental results: The specific surface area of ​​the product was measured by BET method and was 380 m 2 / g, the porosity is 0.68 as measured by mercury intrusion porosimetry, and the elemental composition analysis shows that the carbon content is 78%, the hydrogen content is 3%, the oxygen content is 16%, and the nitrogen content is 3%.

[0062] Embodiment 5:

[0063] Corn straw and rice straw were mixed in a mass ratio of 1:1 as raw materials. The same equipment as in Example 1 was used. The straw crushing length was 2.5 cm and the average diameter was 0.9 cm. The reaction atmosphere was an oxygen content of 28% and a nitrogen content of 72%. The reaction temperature was 520°C, the heating rate was 10°C / min, the microwave power was 500 W, the reaction time was calculated to be 2 hours, the acid washing time was 1 hour, the alkali washing time was 1.5 hours, the ultrasonic frequency was 40 kHz, and the treatment time was 30 minutes.

[0064] The comparison of the above five embodiments is as follows:

[0065]

[0066] Experimental results: The specific surface area of ​​the product was measured by BET method and was 320 m 2 / g, the porosity is 0.60 as measured by mercury intrusion porosimetry, and the elemental composition analysis shows that the carbon content is 72%, the hydrogen content is 4%, the oxygen content is 20%, and the nitrogen content is 4%.

[0067] By analyzing and verifying the data of the above multiple embodiments, the following conclusions can be drawn:

[0068] 1. The type and mixing ratio of straw raw materials have a certain influence on the performance of the product. Generally speaking, the specific surface area and porosity of biochar prepared from wheat straw and rice straw alone are relatively high, while the elemental composition of biochar prepared from corn straw alone is relatively stable;

[0069] 2. Reaction temperature is one of the key factors affecting the performance of biochar. With the increase of reaction temperature, the specific surface area and porosity of biochar show an upward trend, but too high temperature may cause partial carbon loss, thus affecting the carbon content;

[0070] 3. The oxygen content in the reaction atmosphere also has a significant effect on the reaction rate and product performance. Properly increasing the oxygen content can promote the oxidation reaction and improve the pore structure and surface activity of biochar, but too high an oxygen content may lead to excessive combustion and reduce the yield and quality of biochar;

[0071] 4. The application of emerging technologies such as microwave-assisted heating and ultrasonic treatment has significantly improved the reaction efficiency and purification effect, further improving the performance of biochar;

[0072] 5. The time and concentration of pickling and alkali washing play an important role in removing impurities and adjusting element composition. Too long or too short treatment time and too high or too low concentration may affect the quality of the final product.

[0073] By precisely controlling the pretreatment and reaction conditions of the straw and introducing emerging technologies such as microwave-assisted heating and ultrasonic treatment, the prepared biochar has a higher specific surface area and porosity, and a more reasonable elemental composition, which enables it to have better performance in the fields of adsorption and energy storage. The use of microwave-assisted heating and precise heating rate control greatly improves the reaction efficiency, reduces energy consumption, and shortens the preparation time. The purification method of acid washing and alkali washing combined with ultrasonic treatment can more effectively remove impurities, improve the purity of biochar, and enhance its stability and reliability in various applications.

[0074] Plasma treatment technology improves the surface chemical properties of biochar and increases active sites. In-situ characterization technology monitors the microstructural changes during the reaction in real time, providing a strong basis for process optimization and further improving product quality. The real-time temperature and pressure monitoring system and data analysis based on artificial intelligence algorithms achieve precise control of the preparation process and optimization of process parameters, ensuring the consistency and stability of product performance. It can process various types of straw raw materials, including wheat straw, corn straw, rice straw, etc., as well as their mixed raw materials, improving the utilization rate of raw materials and the applicability of the process. The process reduces the emission of pollutants during the preparation process. At the same time, the biochar produced can be used in environmental protection fields such as soil improvement and wastewater treatment, realizing the resource utilization of straw and reducing environmental pressure. The prepared high-performance biochar can improve soil fertility and water retention capacity in soil improvement, promote sustainable agricultural development, effectively remove pollutants in wastewater treatment, protect water resources, and show good application prospects in the field of energy storage, providing strong support for the new energy industry.

[0075] In the above specific embodiments, it is worth mentioning that the biochar obtained by the thermochemical oxidation preparation process of the straw biochar of the present invention shows an excellent effect in improving soil acidification.

[0076] When this biochar is applied to acidified soil, its rich pore structure can increase soil aeration and water retention. Good aeration helps the activity of microorganisms in the soil, promotes the decomposition of organic matter in the soil and the release of nutrients. At the same time, excellent water retention can reduce water loss and improve the soil's ability to resist drought conditions. The following is the data on the effect of different biochar addition amounts on soil aeration and water retention:

[0077]

[0078]

[0079] The alkaline substances in biochar, such as carbonates and oxides, can neutralize the acidic substances in the soil, thereby effectively increasing the pH value of the soil. Experimental data show that applying an appropriate amount of biochar prepared by this process can increase the pH value of acidified soil by 0.5-1 unit, significantly improving the acidification of the soil. The following is the change data of soil pH value under different addition amounts:

[0080]

[0081] In addition, the rich functional groups on the surface of biochar can adsorb heavy metal ions in the soil, reduce their activity and mobility in the soil, and reduce toxicity to plants. At the same time, it can also increase the soil cation exchange capacity, improve the soil's adsorption and retention capacity for nutrient ions, prevent nutrient leaching, and provide a more stable and sufficient nutrient supply for plant growth. The following is the data on the effect of biochar on soil heavy metal adsorption and cation exchange capacity:

[0082]

[0083] After long-term field test observations, the growth of crops in the acidified soil improved by biochar prepared by this process has been significantly improved. The root system of crops is more developed, the plants are stronger, the yield has increased by 15%-20%, and the quality of agricultural products has also been improved. This not only brings direct economic benefits to agricultural production, but also provides strong support for sustainable agricultural development.

[0084] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A process for preparing straw biochar by thermochemical oxidation, characterized in that: The following steps are involved: Step A: pre-treat the straw to remove impurities, first crush the straw into small pieces with a length of 1-3 cm, then rinse with clean water for 3 times, and then dry in a drying oven at 60°C for 2 hours; Step B: placing the pretreated straw in a reaction vessel made of stainless steel with a volume of 50 liters, the reaction vessel being equipped with a real-time temperature and pressure monitoring system; Step C: carrying out a thermochemical oxidation reaction at a temperature of 400-600° C., an atmosphere with an oxygen content of 20%-30% and a nitrogen content of 70%-80%, wherein the reaction time t is calculated according to the formula t=k×(T-T0) / P, wherein k is a reaction rate constant, T is a reaction temperature, T0 is an initial temperature, and P is an oxygen partial pressure. The reaction rate constant k is 0.05, the initial temperature T0 is 25° C., and the oxygen partial pressure P is 0.2 MPa. Microwave-assisted heating is used during the reaction, and the microwave power is 500 W. Step D: After the reaction is completed, the reaction is naturally cooled to room temperature, and the unpurified straw biochar obtained after the thermochemical oxidation reaction is completed is collected. During the cooling process, an infrared thermometer is used to monitor the product temperature in this step in real time; Step E: The product collected in step D is further purified by a combination of acid washing and alkali washing, wherein the acid washing uses a 5% hydrochloric acid solution, and the alkali washing uses a 3% sodium hydroxide solution. Ultrasonic treatment is introduced into the purification process, the ultrasonic frequency is 40 kHz, and the treatment time is 30 minutes; Step F: The product purified in step E is subjected to performance testing to test its specific surface area, porosity and elemental composition. The specific surface area is measured by BET method, the porosity is determined by mercury intrusion method, and the elemental composition is analyzed by X-ray fluorescence spectrometer. Artificial intelligence algorithm is used to analyze the test data and optimize process parameters.

2. The process for preparing straw biochar by thermochemical oxidation according to claim 1, characterized in that: In the step A, the average diameter of the crushed straw particles is 0.5-1 cm.

3. The process for preparing straw biochar by thermochemical oxidation according to claim 1, characterized in that: In the step B, the inner wall of the reaction container is treated with a high temperature resistant coating.

4. The process for preparing straw biochar by thermochemical oxidation according to claim 1, characterized in that: In the step C, the heating rate is controlled at 10° C. / min.

5. The process for preparing straw biochar by thermochemical oxidation according to claim 1, characterized in that: In the step D, during the natural cooling process, the temperature of the unpurified straw biochar obtained after the thermochemical oxidation reaction is measured every 30 minutes.

6. The process for preparing straw biochar by thermochemical oxidation according to claim 1, characterized in that: In the step E, the acid washing time is 1 hour, and the alkali washing time is 1.5 hours.

7. A process for preparing straw biochar by thermochemical oxidation as claimed in claim 1, characterized in that: In step F, the artificial intelligence algorithm is a neural network algorithm based on deep learning.

8. The process for preparing straw biochar by thermochemical oxidation according to claim 1, characterized in that: The straw biochar obtained after the treatment in step A to step F is surface modified by plasma treatment technology, with a treatment time of 10 minutes and a power of 1 kW.

9. A process for preparing straw biochar by thermochemical oxidation as claimed in claim 8, characterized in that: The working gas in the plasma treatment process is argon gas, and the gas flow rate is 10 L / min.

10. The process for preparing straw biochar by thermochemical oxidation according to claim 1, characterized in that: In situ characterization techniques were used to monitor the microstructural changes during the thermochemical oxidation reaction in real time.

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