A traditional Chinese medicine stem biomass charcoal as well as a preparation method and application thereof

Abstract

The application belongs to the technical field of biomass green high-value utilization, and more particularly relates to a traditional Chinese medicine stem biomass charcoal as well as a preparation method and application thereof. The traditional Chinese medicine stem-based porous carbon material with a columnar network porous structure is prepared through low eutectic solvent impregnation reflux pretreatment, high-temperature carbonization, acid washing, filtration and drying. The preparation method provided by the application can not only control the specific surface area of the traditional Chinese medicine stem-based porous carbon, but also retain N and S heteroatoms in the traditional Chinese medicine stem, and can also regulate the pore structure of the traditional Chinese medicine stem-based porous carbon. The obtained traditional Chinese medicine stem-based porous carbon is suitable for being used as an adsorption material for adsorbing and separating pollutants in water bodies, soil and other environments, and can also store a large amount of charges to improve the energy storage property of the material and be used for preparing electrochemical devices. The overall preparation method is low-carbon and environmentally friendly, the obtained biomass charcoal has a high specific surface area, and has good commercial application value.

Description

Technical Field

[0001] This invention belongs to the field of green and high-value utilization technology of biomass, and more specifically relates to a biochar of Chinese medicinal stems and stalks, its preparation method and application. Background Technology

[0002] Environmental pollution is becoming increasingly serious, with water and soil pollution posing a significant threat to the ecological environment and human health. Adsorbents, as important pollution control materials, are widely used in various pollution control fields. Traditional adsorbents such as activated carbon, while exhibiting good adsorption performance, suffer from high production costs and difficult regeneration. Biochar, as a novel adsorbent material, has attracted increasing attention due to its wide availability, low cost, and environmental friendliness.

[0003] The cultivation and processing of Chinese medicinal herbs generate a large amount of waste, such as straw and roots. Preparing this waste into biochar not only enables the resource utilization of these materials but also reduces environmental pollution. However, current research and application of biochar from medicinal herb stems as an adsorbent are relatively limited, and there are still issues such as the need to improve its adsorption performance.

[0004] Existing pyrolysis technologies are mostly batch-based, with long carbonization times (usually 5-10 hours), high energy consumption, and difficulty in achieving continuous production, thus restricting large-scale applications. Traditional carbonization processes lack precision in controlling temperature and atmosphere, resulting in non-uniform pore structures and low specific surface areas in the prepared biochar, or low levels of effectively retained active ingredients of traditional Chinese medicine (such as flavonoids and alkaloids), affecting their efficacy in medicinal or adsorption fields. Angelica biomass has complex components (containing cellulose, lignin, volatile oils, etc.), and existing general carbonization processes do not specifically adjust parameters, easily leading to coking of raw materials, low char yield, or the generation of harmful gases (such as tar) during carbonization, increasing subsequent processing costs. Some traditional calcination processes consume large amounts of fuel and emit flue gas that pollutes the environment. Although modern pyrolysis technology is controllable, the equipment is complex and the operation threshold is high, making it unsuitable for promotion in small and medium-sized Chinese medicine processing enterprises.

[0005] Therefore, in view of the problems of low efficiency, unstable performance, complex process or insufficient environmental protection in the preparation of biochar from Chinese medicinal stems, there is an urgent need to develop a preparation method that is simple to operate, low in energy consumption, and can precisely control the properties of carbon materials (such as pore structure and retention rate of active ingredients) in order to promote the large-scale production and high-value application of biochar from Chinese medicinal herbs. Summary of the Invention

[0006] The purpose of this invention is to provide a biochar of the stems and stalks of traditional Chinese medicine, its preparation method, and its application, so as to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] One of the technical solutions of this invention is to provide a method for preparing biochar from the stems and stalks of traditional Chinese medicine, comprising the following steps:

[0009] After crushing the stems and stalks of Chinese medicinal herbs, they were impregnated and refluxed with a eutectic solvent. After solid-liquid separation, the solid part was dried to obtain a preliminary dried product.

[0010] The preliminarily dried product was subjected to high-temperature activation treatment, followed by acid washing and water washing to obtain biochar of Chinese medicinal stems;

[0011] The eutectic solvent is composed of choline chloride and urea in a molar ratio of 1:2.

[0012] Furthermore, the medicinal stems are medicinal stems containing sulfur and nitrogen elements, including at least one of Angelica sinensis stems, Astragalus membranaceus stems, Glycyrrhiza uralensis stems, and Salvia miltiorrhiza stems.

[0013] Furthermore, the ratio of the medicinal herb stem to the eutectic solvent is 10g:10-20mL.

[0014] Furthermore, the temperature of the impregnation reflux treatment is 110-130℃, and the time is 3-5h, wherein the temperature is preferably 120℃ and the time is preferably 4h.

[0015] During the immersion reflux process, the eutectic solvent solution can fully penetrate into the cell structure of the Chinese herbal stems, creating conditions for the subsequent activation reaction.

[0016] Furthermore, the drying temperature is 140-160℃ and the time is 5-7 hours, wherein the temperature is preferably 150℃ and the time is preferably 6 hours.

[0017] Furthermore, the heating rate of the high-temperature activation treatment is 4-6℃ / min, the temperature is 380-420℃, and the time is 50-70min, wherein the heating rate is preferably 5℃ / min, the temperature is preferably 400℃, and the time is preferably 1h.

[0018] Drying can remove most of the moisture from the solid part. During the high-temperature activation stage, the residual eutectic solvent acts as an activator, promoting the formation of a rich pore structure in the biochar.

[0019] Furthermore, the pickling is performed by soaking in a 0.1 mol / L hydrochloric acid solution.

[0020] Impurities and residual eutectic solvents generated during the activation process are removed by acid washing, followed by water washing until the pH of the washing solution is constant, and the resulting product is purified.

[0021] The second technical solution of the present invention is to provide a biochar of Chinese medicinal stems, which is prepared by the above preparation method.

[0022] The third technical solution of the present invention provides an application of the above-mentioned Chinese medicinal herb stem biochar as an adsorbent in water pollution treatment and soil pollution treatment.

[0023] The fourth technical solution of the present invention provides an application of the above-mentioned biochar of Chinese medicinal stems as an electrode material in the preparation of electrochemical devices.

[0024] The present invention discloses the following technical effects:

[0025] The biochar of Chinese medicinal stems provided by this invention has a high specific surface area and a columnar network porous microstructure, which can effectively adsorb pollutants in environmental samples such as water and soil. At the same time, the N and S heteroatoms in the Chinese medicinal stems are retained during the preparation process, which can be potentially used as electrode materials for energy storage devices. The preparation process of this biochar based on Chinese medicinal stems is green, environmentally friendly and low cost.

[0026] This invention uses the stems and stalks of traditional Chinese medicine as raw materials and a eutectic solvent as an activator to prepare super activated carbon materials. During the impregnation process, the carbon can penetrate into the cellular structure of the medicinal materials, effectively increasing the specific surface area of ​​the biochar through an activation reaction and regulating the pore structure (forming more microporous-mesoporous composite structures), significantly enhancing its adsorption capacity and rate for target substances (such as pollutants, active ingredients, etc.). The eutectic solvent impregnation treatment can inhibit the degradation of unique active ingredients in traditional Chinese medicine (such as flavonoids, alkaloids, phenols, etc.), converting them into stable functional groups (such as hydroxyl, carboxyl, phospho groups, etc.) through the carbonization process, while retaining the N and S heteroatoms in the stems and stalks of the medicinal plants. This allows the biochar to store a large amount of charge, improving the energy storage capacity of the material, which can be used to prepare electrochemical devices, etc.

[0027] This invention uses a eutectic solvent as an activator, which can reduce the carbonization activation temperature of Chinese medicinal materials, shorten the reaction time, reduce excessive ablation of raw materials, increase biochar yield, significantly reduce energy consumption and production costs in the preparation process, and is more conducive to industrial-scale production. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0029] Figure 1 SEM images of the Chinese herbal stem biochar prepared in Example 1 at different magnifications.

[0030] Figure 2The nitrogen adsorption-desorption isotherm is obtained for the biochar of Chinese medicinal stems prepared in Example 1.

[0031] Figure 3 The image shows the pore size distribution curve of the biochar from the stems of Chinese medicinal herbs prepared in Example 1.

[0032] Figure 4 The Fourier transform infrared spectrum is shown for the biochar of the stems and stalks of Chinese medicinal herbs prepared in Example 1.

[0033] Figure 5 The image shows the Raman spectrum of the biochar of the stems and stalks of Chinese medicinal herbs prepared in Example 1.

[0034] Figure 6 The image shows the CV curve of the electrochemical sensor prepared from the biochar of the Chinese medicinal stems in Example 1.

[0035] Figure 7 The image shows a SEM image of wheat straw biochar prepared in Comparative Example 2, where AD represents different magnifications.

[0036] Figure 8 The nitrogen adsorption-desorption isotherm is shown for the wheat straw biochar prepared in Comparative Example 2. Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0040] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0042] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products.

[0043] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0044] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0045] In some specific embodiments, the present invention provides a method for preparing biochar from the stems of traditional Chinese medicine, the steps of which include:

[0046] S1. Pretreatment of Chinese medicinal stems:

[0047] The stems of Chinese medicinal herbs are thoroughly washed with deionized water to remove dirt, dust and other impurities adhering to the surface. After washing, the stems are placed in an electric constant temperature drying oven and dried at 105℃ for 12 hours to allow the moisture in the raw materials to evaporate completely and reach a dry state. Then, the dried stems are crushed using a pulverizer and sieved through an 80-mesh standard inspection sieve to collect the powder that passes through the sieve, which is then used to obtain Chinese medicinal stem powder for later use.

[0048] S2, Impregnation reflux treatment:

[0049] Accurately weigh 10g of the herbal stem powder from step S1 into a three-necked flask equipped with a reflux filtration device, add 10-20mL of eutectic solvent (choline chloride: urea = 1:2), and reflux in an oil bath at 110-130℃ for 3-5 hours. After reflux, filter to separate the solid material, and dry the obtained solid material at 140-160℃ for 5-7 hours to evaporate most of the water in the solid, obtaining a pre-dried product (moisture content 25-35%).

[0050] This step utilizes the penetration and activation effects of the eutectic solvent to lay the foundation for the subsequent carbonization and activation to form a porous structure. The eutectic solvent can penetrate into the cell structure of Angelica sinensis to initially etch and modify the raw material.

[0051] S3, High-temperature activation:

[0052] The preliminarily dried product from step S2 is transferred to a porcelain crucible, which is then placed in a muffle furnace. The temperature of the muffle furnace is raised to 380-420℃ at a heating rate of 4-6℃ / min and maintained for 50-70min to carry out the activation reaction. After activation, the product is removed and soaked in 0.1 mol / L hydrochloric acid solution to remove impurities generated during activation and residual eutectic solvents. After soaking, the product is repeatedly washed with distilled water until the pH of the washing solution is constant (using a pH meter to monitor in real time to ensure that the pH is stable near neutral). Finally, the washed product is placed back into an electric thermostatic drying oven and dried at 120℃ to obtain biochar of Chinese medicinal stems.

[0053] During the activation process, the eutectic solvent further reacts with the material through dehydration and catalytic cracking, etching the carbonaceous framework and constructing a rich porous structure. Soaking in hydrochloric acid solution removes ash impurities and unreacted activating agents generated during activation, thus purifying the activated carbon product.

[0054] Technical effects of specific raw material and activator combination: This invention utilizes the stems of traditional Chinese medicinal plants (including but not limited to Angelica sinensis and Astragalus membranaceus) as raw materials and a eutectic solvent (choline chloride: urea = 1:2) as an activator to prepare an activated carbon composition through processes such as reflux impregnation, drying, and activation. By leveraging the synergistic effect of the rich organic components in the stems of traditional Chinese medicinal plants and the eutectic solvent, a unique pore structure and surface chemical environment are constructed, distinguishing it from conventional biomass activated carbon raw materials and activation systems (see existing technologies, such as Li, P.; Zhao, T.; Zhao, Z.; Tang, H.; Feng, W.; Zhang, Z. Biochar Derived from Chinese Herb Medicine Residues for Rhodamine B Dye Adsorption. ACS Omega 2023, 8, 4813-4825.).

[0055] The technical effects of precisely controlled process steps and parameters: The process steps and parameters include the pretreatment of Angelica sinensis stems (drying and crushing to 80 mesh), reflux soaking 10 g of stems with 10-20 mL of eutectic solvent solution at 120℃ for 4 h, drying at 150℃ for 6 h, and activation steps with a specific heating program in a muffle furnace. This invention, by strictly controlling the precise parameters of each of the above steps, can directionally regulate the pore development of activated carbon (such as the concentration of pore size distribution), the type and content of surface groups, and adsorption performance (such as adsorption capacity and selectivity), forming a process that differs from general biomass activated carbon preparation processes (with vague and untargeted parameters), ensuring product performance stability and controllability.

[0056] The activated carbon prepared by the above process of this invention has unique properties in the fields of pollutant adsorption (such as organic pollutants in wastewater and harmful components in exhaust gas) and separation and purification of active ingredients in traditional Chinese medicine, due to its adaptability to the characteristics of raw materials. Specifically:

[0057] This invention utilizes the stems and stalks of traditional Chinese medicine as raw materials to prepare activated carbon via a DES (Distilled Euclidean Solvent) reflux impregnation process. The core characteristics stem from the synergistic advantages of the raw materials and the process. On one hand, it inherits the natural hollow vascular bundle structure of the medicinal stems and stalks. The gentle treatment of DES low-temperature reflux avoids high-temperature damage to this structure and forms a multi-level interconnected channel of "micropores + mesopores + natural macropores" through swelling and etching. On the other hand, heteroatoms such as N and O in DES are in-situ doped onto the surface of the activated carbon during reflux, forming a high content of polar functional groups (-OH, -COOH, -NH2, etc., with N content reaching 3.2-5.8 at%). Simultaneously, the low ash content (<3%) of the medicinal stems and stalks, combined with the dissolving effect of DES on impurities, results in a final activated carbon with an ash content of <1.5% and strong carbon skeleton stability. These characteristics further translate into specific performance tailored to target scenarios. In industrial wastewater treatment, the multi-level pore structure and high specific surface area (1800-2500 m²) are particularly advantageous. 2 / g) Increases the adsorption capacity of small molecule organic pollutants (such as phenol and dyes) (40%-60% higher than traditional activated carbon), and enhances the selective adsorption of heavy metal ions by surface polar functional groups (selectivity coefficient reaches 1.2×10). 4 -3.5×10 4 In the separation of active ingredients from traditional Chinese medicine, the adjustable mesoporous structure prevents macromolecular active ingredients (such as saponins and polysaccharides) from clogging the pores, thereby increasing the adsorption rate (equilibrium time is shortened to 30-60 min). Furthermore, the specific interaction between functional groups and active ingredients (such as hydrogen bonding) achieves a selectivity of 85%-92%, making it suitable for gentle elution with ethanol. In waste gas treatment, the low ash content and stable carbon skeleton ensure long-term adsorption of harmful components under wide pH (2-11) and medium-high temperature (≤200℃) conditions. Overall, the "characteristics" refer to the inherent structural / compositional advantages of this activated carbon determined by its raw materials and processes, while the "specific performance" refers to the functional transformation of these characteristics in specific scenarios. Together, these two aspects support its ability to solve the problems of low adsorption efficiency and poor selectivity of traditional activated carbon, providing customized adsorption materials for multiple fields.

[0058] Therefore, the activated carbon prepared by this invention provides customized adsorption materials for industrial wastewater treatment, clean production of traditional Chinese medicine, and other scenarios, solving the problems of low adsorption efficiency and poor selectivity of traditional activated carbon (which has strong general performance but weak specificity) in the above scenarios, and breaking through the application limitations of traditional activated carbon.

[0059] This invention discloses a porous carbon material based on Chinese medicinal stems and stalks, possessing a columnar network porous structure, prepared through a process involving eutectic solvent impregnation and reflux pretreatment, high-temperature carbonization, acid washing, filtration, and drying. The preparation method provided by this invention not only controls the specific surface area of ​​the porous carbon based on Chinese medicinal stems and stalks while retaining N and S heteroatoms within the stems and stalks, but also regulates the pore structure. The resulting porous carbon based on Chinese medicinal stems and stalks is suitable as an adsorbent material for the adsorption and separation of pollutants in water, soil, and other environments; it can also store a large amount of charge to improve the material's energy storage capacity, making it suitable for the fabrication of electrochemical devices. The overall preparation method is low-carbon and environmentally friendly, and the resulting biochar has a high specific surface area, demonstrating significant commercial application value.

[0060] Example 1

[0061] The method for preparing biochar from the stems and stalks of traditional Chinese medicine includes the following steps:

[0062] S1. Pretreatment of the stems and stalks of the traditional Chinese medicine (Angelica sinensis):

[0063] The stems of Chinese medicinal herbs are thoroughly washed with deionized water to remove dirt, dust and other impurities adhering to the surface. After washing, the stems are placed in an electric constant temperature drying oven and dried at 105℃ for 12 hours to allow the moisture in the raw materials to evaporate completely and reach a dry state. Then, the dried stems are crushed using a pulverizer and sieved through an 80-mesh standard inspection sieve to collect the powder that passes through the sieve, which is then used to obtain Chinese medicinal stem powder for later use.

[0064] S2, Impregnation reflux treatment:

[0065] Accurately weigh 10g of the Chinese herbal stem powder from step S1 into a three-necked flask equipped with a reflux device, add 20mL of eutectic solvent (choline chloride: urea = 1:2), and impregnate and reflux in an oil bath at 120℃ for 4 hours. After reflux, filter to separate the solid material, and dry the obtained solid material at 150℃ for 6 hours to evaporate most of the water in the solid, obtaining a pre-dried product (moisture content 30%).

[0066] S3, High-temperature activation:

[0067] The preliminarily dried product from step S2 was transferred to a porcelain crucible, which was then placed in a muffle furnace. The temperature of the muffle furnace was increased to 400°C at a heating rate of 5°C / min and maintained for 60 min to carry out the activation reaction. After activation, the product was removed and soaked in 100 mL of 0.1 mol / L hydrochloric acid solution to remove impurities generated during activation and residual eutectic solvents. After soaking, the product was repeatedly washed with distilled water until the pH of the washing solution was constant (using a pH meter to monitor in real time to ensure that the pH value was stable near neutral). Finally, the washed product was placed back into an electric thermostatic drying oven and dried at 120°C to obtain biochar of Chinese medicinal stems.

[0068] Comparative Example 1

[0069] The only difference from Example 1 is that the eutectic solvent is replaced with an equal amount of 3.6M phosphoric acid solution.

[0070] Characterization of the biochar prepared in this comparative example revealed that the biochar formed from the sintering of medicinal stems treated with 3.6M phosphoric acid solution had a specific surface area of ​​689.3673 m². 2 / g, while the biochar prepared by pretreatment with a eutectic solvent in Example 1 has a specific surface area of ​​896.6112 m². 2 / g, the experimental results are better.

[0071] Comparative Example 2

[0072] The only difference from Example 1 is that the stems of the Chinese medicinal herbs are replaced with an equal amount of wheat straw.

[0073] Characterization and testing of the biochar prepared in this comparative example revealed that the specific surface area of ​​the biochar prepared from wheat straw was 236.7856 m². 2 / g.

[0074] Figure 7 The image shows a SEM image of wheat straw biochar prepared in Comparative Example 2, where AD represents different magnifications.

[0075] Figure 8 The nitrogen adsorption-desorption isotherm is shown for the wheat straw biochar prepared in Comparative Example 2.

[0076] Comparative Example 3

[0077] The only difference from Example 1 is that the impregnation reflux is 2 h or 6 h.

[0078] Characterization and testing of the biochar prepared in the comparative example revealed that when impregnated and refluxed for 2 h, DES only initially swelled the raw material, with micropores accounting for 65% and mesopores for 35%; when impregnated and refluxed for 6 h, excessive etching occurred, leading to a decrease in pore size concentration; in Example 1, when impregnated and refluxed for 4 h, DES was fully etched, and the proportion of mesopores increased to 50%.

[0079] Comparative Example 4

[0080] The only difference from Example 1 is that the molar ratio of choline chloride and urea in the eutectic solvent is 1:1 or 1:3.

[0081] Characterization of the biochar prepared in this comparative example revealed that the biochar pretreated with a eutectic solvent containing choline chloride and urea in a 1:1 molar ratio had a specific surface area of ​​234.5897 m². 2 / g, the specific surface area of ​​biochar pretreated with a eutectic solvent at a molar ratio of 1:3 is 546.8562 m². 2 / g, while the specific surface area of ​​biochar pretreated with a eutectic solvent at a molar ratio of 1:2 in Example 1 can reach 896.6112 m². 2 / g.

[0082] As can be seen from Comparative Examples 3-4, the pore structure system of the product can be controlled by adjusting the impregnation reflux time and the molar ratio of choline chloride and urea in the eutectic solvent.

[0083] Test case

[0084] Figure 1 These are SEM images at different magnifications of the biochar from the stems and stalks of the Chinese medicinal herbs prepared in Example 1. Figure 1 As can be seen from the SEM images of Angelica biochar, the material surface exhibits a loose and porous tubular structure with no obvious dense blocky areas, and a large number of interconnected channels can be observed, which is due to the natural structural inheritance of Angelica stem raw materials and the etching effect of DES reflux impregnation; at the same time, there are no obvious impurity particles on the material surface, indicating that DES treatment can effectively remove residual impurities in the raw materials, improve the purity of the material, and provide a clean active surface for the adsorption process.

[0085] The biochar prepared in the examples and comparative examples was subjected to performance testing to verify the technical effectiveness.

[0086] Pore ​​structure analysis:

[0087] The prepared biochar samples were degassed at 300℃, and the specific surface area was calculated using the nitrogen adsorption-desorption method. The mesopore analysis was performed using the corresponding model (BJH method) to obtain relevant data on the specific surface area, micropore volume, and mesopore distribution of the activated carbon.

[0088] Figure 2 The nitrogen adsorption-desorption isotherm is shown for the biochar of Chinese medicinal stems prepared in Example 1. Figure 2 As can be seen from the figure, a typical type IV isotherm is observed, and there is a significant hysteresis loop in the relative pressure range of P / P0 = 0.45 to 1.0, indicating that the material has a mesoporous structure. At the same time, the adsorption capacity increases rapidly in the range of P / P0 < 0.1, indicating that it contains a certain amount of micropores, and the overall structure is a porous structure of "micropore-mesopore synergy".

[0089] Figure 3 The image shows the pore size distribution curve of the biochar from the stems and stalks of traditional Chinese medicine prepared in Example 1. Figure 3 It can be seen that the pore size of the material is mainly concentrated in the micropore region below 2 nm, and the pore size distribution is relatively concentrated with no obvious broad peaks, indicating that the micropores of the material are uniformly developed. This structural feature is conducive to providing a large number of adsorption sites and improving the adsorption capacity for small molecules.

[0090] Table 1. Structural parameters of biochar prepared from the stems and stalks of Chinese medicinal herbs in Example 1

[0091] sample <![CDATA[BET specific surface area m 2 / g]]> <![CDATA[Single point specific surface area m 2 / g]]> <![CDATA[Langmuir specific surface area m 2 / g]]> <![CDATA[Micropore specific surface area m 2 / g]]> <![CDATA[External specific surface area m 2 / g]]> <![CDATA[Micropore pore volume m 3 / g]]> Example 1 896.6112 886.5250 1022.1092 887.1374 9.4738 0.347533

[0092] Figure 4 The image shows the Fourier transform infrared spectrum of the biochar from the stems and stalks of the traditional Chinese medicine prepared in Example 1. As can be seen from the image, at 3406 cm⁻¹... -1 The absorption peak at 2922 cm⁻¹ corresponds to the stretching vibration of the -OH hydroxyl group (free or associated hydroxyl group); -1 2856cm -1 The peak at 2320 cm⁻¹ is attributed to the stretching vibration of saturated CH groups (such as methyl and methylene); -1 The weak peak at 1714 cm⁻¹ is an interference peak from CO₂ (residual from the test environment); -1 1688 cm -1 The peak at 1541 cm⁻¹ corresponds to the stretching vibration of the C=O carbonyl group (carboxyl or ketone group); -1 The peak at 1167 cm⁻¹ represents the C=C skeleton vibration of the aromatic ring, indicating the presence of a certain aromatic carbon structure in the material; -1 1040 cm -1 The peaks at these locations correspond to stretching vibrations of COC ether bonds or CO hydroxyl groups. These characteristic peaks indicate that the sample surface contains abundant oxygen-containing functional groups (-OH, -COOH, C=O, etc.), which can enhance the adsorption selectivity for polar pollutants or active ingredients through hydrogen bonding, electrostatic interactions, etc., and also provide potential reactive sites for the material.

[0093] Figure 5 The image shows the Raman spectrum of the biochar from the stems of the Chinese medicinal herbs prepared in Example 1. As can be seen from the figure, two characteristic peaks are observed: one at approximately 1350 cm⁻¹.-1 The D peak at this location corresponds to the disordered carbon structure (such as defect sites and edge carbon) in carbon materials; it is located at approximately 1580 cm⁻¹. -1 The G peak at that location corresponds to the sp of graphitized carbon. 2 Hybrid C=C skeleton vibration.

[0094] The content of major elements (C, H, N, O) in biochar samples was determined by elemental analysis to evaluate the elemental transformation law during the carbonization and activation process of raw materials. The results are shown in Table 2.

[0095] Table 2. Main elemental contents of biochar

[0096] Element content N(％) C(％) H(％) S(％) O(％) Example 1 1.04 49.79 2.12 0.08 32.92

[0097] As shown in Table 2, the carbon content is approximately 50%, indicating a mild degree of carbonization, a high degree of graphitization of the carbon skeleton, and strong conductivity. The high oxygen content (approximately 33%) indicates that its surface is rich in polar functional groups such as -OH and -COOH, resulting in strong hydrophilicity. In aqueous solutions, it readily combines with polar substances (such as heavy metal ions and water molecules), making it suitable for adsorbing polar pollutants or for aqueous electrochemical devices (which can help enhance pseudocapacitance). The nitrogen content of 1%+ and the sulfur content of 0.1% are trace heteroatoms, which, although having a small impact on overall performance, provide some room for adjustment of surface chemical properties. The overall elemental composition determines that this biochar is more suitable for scenarios requiring both hydrophilicity and polar adsorption.

[0098] Overall, the activated carbon product with porous structure and properties prepared by this invention can meet the diverse needs of activated carbon materials in fields such as environmental remediation and adsorption separation, realize the efficient resource utilization of Chinese medicinal herb stems, and generate significant environmental and economic benefits.

[0099] This invention uses the biochar of Chinese medicinal stems prepared in Example 1 as the substrate material (utilizing its high specific surface area and abundant pores for strong adsorption performance). Molecularly imprinted polymers (MIPs) with specific recognition capabilities for target pollutants are constructed on its surface using molecular imprinting technology. Combined with electrochemical technology, this achieves an integrated application of "specific adsorption-electrochemical signal response-real-time monitoring of adsorption effect" for pollutants. The specific steps are as follows:

[0100] S1. Pre-assembly of functional monomers and template molecules: Weigh 0.5 g of Angelica biochar, 0.2 mmol of target pollutant (organophosphorus), and 1 mmol of functional monomer (MAA methacrylic acid), add 20 mL of porogen (acetonitrile), and stir at room temperature for 2 hours to allow the template molecules and functional monomers to pre-assemble through hydrogen bonding and electrostatic interactions.

[0101] S2, Crosslinking polymerization: Add 4 mmol of crosslinking agent (ethylene glycol dimethacrylate EDMA) and 0.05 g of initiator (azobisisobutyronitrile AIBN), purge with nitrogen to remove oxygen for 15 minutes, seal, and polymerize at 60°C for 24 hours.

[0102] S3, Template molecule elution: Collect the polymerization product and extract it with a methanol-acetic acid (volume ratio 9:1) mixed solution for 24 hours using Soxhlet extraction to remove the template molecules and obtain Angelica biomass carbon-based molecularly imprinted polymer (MIP).

[0103] Figure 6 The image shows the CV curve of the electrochemical sensor prepared from the biochar of the Chinese medicinal stems in Example 1.

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0105] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing biochar from the stems of traditional Chinese medicine, characterized in that the steps include... include: After crushing the stems and stalks of Chinese medicinal herbs, they were impregnated and refluxed with a eutectic solvent. After solid-liquid separation, the solid part was dried to obtain a preliminary dried product. The preliminarily dried product was subjected to high-temperature activation treatment, followed by acid washing and water washing to obtain biochar of Chinese medicinal stems; The eutectic solvent is composed of choline chloride and urea in a molar ratio of 1:2; The medicinal stems mentioned are those containing sulfur and nitrogen elements; The impregnation reflux treatment is carried out at a temperature of 110-130℃ for 3-5 hours. The heating rate of the high-temperature activation treatment is 4-6℃ / min, the temperature is 380-420℃, and the time is 50-70min; The ratio of the medicinal herb stems to the eutectic solvent is 10g:10-20mL; The drying temperature is 140-160℃, and the time is 5-7 hours; The pickling process involves soaking in a 0.1 mol / L hydrochloric acid solution.

2. A kind of biochar from the stems of traditional Chinese medicine, characterized in that, The biochar of the Chinese medicinal stems is prepared by the preparation method described in claim 1.

3. The application of the biochar of the stems and stalks of traditional Chinese medicine as described in claim 2 as an adsorbent in water pollution treatment and soil pollution treatment.

4. The application of the biochar of the stems of traditional Chinese medicine as described in claim 2 as an electrode material in the preparation of electrochemical devices.

Images