Preparation method and application of polygonum multiflorum biochar

Abstract

The invention relates to a preparation method and application of polygonum multiflorum biochar. The preparation method comprises the following steps: washing polygonum multiflorum root blocks, slicing, drying and crushing into powder; putting the powder into a reaction kettle, adding water and a catalyst, and carbonizing to obtain carbonized primary pulp; and filtering the primary pulp, washing with water to be clear after acid pickling, drying a filter cake, crushing, and sieving with a 200-mesh sieve to obtain the product. The polygonum multiflorum biochar prepared by the method disclosed by the invention can be used as a preparation raw material to be applied to cosmetics, especially eyebrow pencils and eyebrow dye cream. According to the preparation method, a hydrothermal carbonization process is adopted, and functional components are reserved while low-temperature carbonization is performed. Raw material treatment stipulates the powder particle size range to increase the specific surface area and facilitate uniform reaction; a good reaction environment is created by reasonably controlling the mass ratio of polygonum multiflorum powder to water to the catalyst; a proper catalyst is selected to promote reaction; proper carbonization temperature and time are set, eyebrow nourishing substances are reserved, a multi-stage pore structure is formed through accurate control, and adsorption and functional component load release capacity is enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of biochar preparation, and in particular to a method for preparing Polygonum multiflorum biochar and its application. Background Art

[0002] Polygonum multiflorum is a tuberous root from the Polygonaceae family, known for its benefits of nourishing essence and blood, detoxifying, preventing malaria, and promoting bowel movements. Its chemical composition is primarily composed of anthraquinone compounds, with chrysophanol and emodin as core components. It also contains active substances such as lecithin and crude fat. Due to its medicinal properties, Polygonum multiflorum has been developed into a variety of medicinal foods and health products in the dietary therapy field. In the cosmetics industry, it is widely used in the formulation of hair care, hair nourishment, and hair growth products.

[0003] In traditional Chinese medicine processing, calcination is a typical method for preparing Polygonum multiflorum. This process involves placing the cleaned or cut herbs in a smokeless furnace or refractory container, calcining them at high temperatures until they appear charred black on the outside and burnt yellow on the inside, creating their characteristic "charred outside, yellow inside" appearance. This treatment carbonizes the herbs' surface while preserving their characteristic aroma and some of their active ingredients.

[0004] The preparation of Polygonum multiflorum biochar follows a similar principle: using Polygonum multiflorum as the raw material, it is carbonized in a high-temperature, oxygen-deficient environment, achieving partial carbonization by controlling the degree of pyrolysis. This process creates a dense carbon structure in the outer layer while retaining some of the original active ingredients in the inner layer, ultimately producing Polygonum multiflorum biochar that combines the properties of a carbon material with pharmaceutical activity.

[0005] The current mainstream method for preparing biochar is high-temperature calcination. Although this method can achieve a high degree of carbonization, due to the severe pyrolysis conditions, it is easy to cause a large amount of decomposition of the active ingredients in the raw materials, making it difficult to balance the degree of carbonization and the retention of medicinal efficacy. Summary of the Invention

[0006] In order to solve the above-mentioned problems, the present application provides a preparation method of Polygonum multiflorum biochar and its application, aiming to ensure that the Polygonum multiflorum biochar obtained by this preparation process can retain certain efficacy while carbonizing, thereby meeting the special needs of the cosmetics field, especially eyebrow pencils, eyebrow tints and other eyebrow makeup products for functional carbon materials.

[0007] In the first aspect, the present application provides a method for preparing Polygonum multiflorum biochar using the following technical solutions: A method for preparing Polygonum multiflorum biochar comprises the following steps: S1. Wash and slice the root of Polygonum multiflorum, dry it, and then grind it into powder; S2, placing the powder obtained in S1 into a reactor, adding water and a catalyst for carbonization to obtain a carbonized slurry; S3. Filter the raw pulp, wash with water after acid washing until it is clear, dry the filter cake and crush it, and pass it through a 200-mesh sieve to obtain Polygonum multiflorum biochar.

[0008] By adopting the above technical solution, partial carbonization of Polygonum multiflorum is achieved under low temperature conditions, so that it has both the characteristics of biochar and the efficacy of Polygonum multiflorum. The obtained Polygonum multiflorum charcoal powder has a smooth and soft surface without any granularity, and also retains the unique smell and efficacy of traditional Chinese medicine. It can meet the special needs of the cosmetics field, especially eyebrow pencils, eyebrow tints and other eyebrow makeup products for functional carbon materials.

[0009] Furthermore, the powder in S1 has a pulverized particle size of 80-120 mesh.

[0010] By adopting the above technical solution, the Polygonum multiflorum powder within this particle size range has a larger specific surface area and can fully contact with water and catalyst during the hydrothermal carbonization process, making the carbonization reaction more uniform and thorough, which is conducive to the precise control of part of the carbonization process, thereby better retaining the effective ingredients of Polygonum multiflorum and obtaining biochar with more stable performance.

[0011] Furthermore, the mass ratio of the Polygonum multiflorum powder to water in S2 is 1:2-10 kg / kg.

[0012] By adopting the above technical solution, within this mass ratio range, an appropriate amount of water provides a good mass transfer environment for the carbonization reaction. Water, as a solvent and reaction medium, can accelerate the diffusion rate of the catalyst in the Polygonum multiflorum powder, allowing the reaction to start quickly and proceed efficiently. When the mass ratio is too low, the reaction system is too viscous, mass transfer is hindered, and the reaction rate slows down; when the mass ratio is too high, although the mass transfer conditions are better, the reactant concentration will be diluted, which is also not conducive to the efficient progress of the reaction. Therefore, this mass ratio range can balance mass transfer and reactant concentration, improving the overall efficiency of the carbonization reaction.

[0013] Furthermore, the mass ratio of the Polygonum multiflorum powder to the catalyst in S2 is 1:0.01-0.1 kg / kg.

[0014] By employing this technical solution, the catalyst can be evenly dispersed within the Polygonum multiflorum powder system at an appropriate concentration within this mass ratio range. Within this range, the catalyst can fully exert its catalytic activity, effectively reducing the activation energy of the hydrothermal carbonization reaction, accelerating the reaction process, and more fully converting the macromolecular organic matter in the Polygonum multiflorum into biochar with a specific structure.

[0015] Furthermore, the catalyst in S2 is selected from at least one of potassium hydroxide, sodium hydroxide, ferric chloride, phosphoric acid, aluminum chloride, and zinc chloride.

[0016] By adopting the above technical solutions, these catalysts can promote the hydrothermal carbonization reaction of Polygonum multiflorum from different mechanisms. Potassium hydroxide and sodium hydroxide, as alkaline catalysts, can provide abundant hydroxide ions to destroy the chemical bonds of organic matter in Polygonum multiflorum, accelerate its decomposition and rearrangement, and form biochar with rich pore structure, which is beneficial to improving the adsorption performance of biochar. Metal salt catalysts such as ferric chloride, aluminum chloride and zinc chloride, whose metal ions have strong polarization ability, can activate the chemical bonds in Polygonum multiflorum molecules, reduce the reaction activation energy, and make the carbonization reaction proceed rapidly under relatively mild conditions. At the same time, it helps to regulate the pore size and distribution of biochar and enhance its adsorption selectivity for specific substances. Phosphoric acid, as an acidic catalyst, can promote the hydrolysis and dehydration reactions of components such as cellulose and hemicellulose in Polygonum multiflorum, forming more aromatic structures, thereby improving the stability and thermal stability of biochar.

[0017] Furthermore, the carbonization temperature in S2 is 150-300° C., and the carbonization time is 1-8 hours.

[0018] By adopting the above technical solution, the bioactive components in Polygonum multiflorum can be retained to a certain extent at this temperature. Polyphenols, flavonoids and other substances with eyebrow nourishing effects are relatively stable within this temperature range and can be partially retained in the biochar during the carbonization process. This makes the prepared Polygonum multiflorum biochar not only have adsorption properties, but also have the unique effect of nourishing eyebrows, meeting the demand for functional raw materials in eyebrow makeup products. At the same time, the appropriate carbonization time allows for precise control of the biochar's pore structure. Within this timeframe, the biochar's pores gradually form and develop, forming a hierarchical pore structure dominated by micropores and mesopores. This hierarchical pore structure not only provides a large specific surface area, enhancing the biochar's adsorption capacity for pigments, oils, and other substances in cosmetics, but also facilitates the loading and release of active ingredients, allowing products like eyebrow pencils and eyebrow tints to better adhere to eyebrows, maintain color, and provide continuous nourishment and care.

[0019] Furthermore, the pickling in S3 uses dilute hydrochloric acid with a concentration of 1-3%.

[0020] By adopting the above technical solution, within this concentration range, the hydrogen ions in the dilute hydrochloric acid have appropriate activity and concentration, and can chemically react with impurities such as metal oxides and alkaline substances remaining on the surface and in the pores of the biochar. For metal oxides such as iron, calcium, and magnesium that may be introduced during the carbonization process, the dilute hydrochloric acid can react with them to form water-soluble metal chlorides, thereby completely separating these impurities from the biochar through subsequent water washing steps.

[0021] In the second aspect, the application of a Polygonum multiflorum biochar provided in this application adopts the following technical solution: The application of the Polygonum multiflorum biochar prepared by the above-mentioned preparation method of Polygonum multiflorum biochar in cosmetics includes eyebrow pencils and eyebrow tints.

[0022] By adopting the above technical solution, the Polygonum multiflorum biochar can significantly improve the product efficacy of eyebrow pencils and eyebrow tints. Polygonum multiflorum itself is rich in various ingredients beneficial to hair, such as polyphenols and flavonoids. The biochar obtained through a specific preparation method not only retains these nourishing ingredients but also forms a rich pore structure. When the Polygonum multiflorum biochar is added to the eyebrow pencil, its porous structure can absorb oil and dirt around the eyebrows, keeping the eyebrows fresh and clean, and providing a good foundation for even coloring of the eyebrow pencil. At the same time, the nourishing ingredients contained in biochar can be gradually released during the coloring process, penetrate into the inside of the eyebrows, nourish the hair follicles, promote the growth of eyebrows, and make eyebrows thicker and healthier. For eyebrow dyeing cream, the adsorption properties of Polygonum multiflorum biochar help to better fix the dye, prolong the durability of the eyebrow dyeing effect, reduce fading and smudging, and its nourishing effect can improve the texture of the eyebrows, make the eyebrows softer and more shiny, and enhance the beauty of the overall makeup.

[0023] In summary, this application has the following beneficial effects: 1. The method for preparing Polygonum multiflorum biochar provided in this application, by adopting a hydrothermal carbonization process, realizes the carbonization of Polygonum multiflorum at low temperature while retaining its effective ingredients. From the perspective of raw material processing, the powder particle size range is specified to increase the specific surface area, which is conducive to a uniform and thorough reaction; the mass ratio of Polygonum multiflorum powder to water and catalyst is reasonably controlled to provide a good environment for the reaction and ensure that the catalyst can fully play its role; the appropriate type of catalyst is selected to promote the hydrothermal carbonization reaction from different mechanisms; the appropriate carbonization temperature and time are set, which not only retains the polyphenols, flavonoids and other substances with the effect of nourishing eyebrows, but also accurately The pore structure of the biochar is controlled, forming a multi-level pore structure dominated by micropores and mesopores, which enhances its adsorption performance and ability to release the active ingredients. 2. During the preparation process, the present application uses dilute hydrochloric acid at a concentration of 1-3% for acid washing. At this concentration, the hydrogen ion activity and concentration are suitable, and it can react with impurities such as metal oxides and alkaline substances remaining on the surface and in the pores of the biochar to form water-soluble metal chlorides. Subsequent water washing then completely separates the impurities, effectively removing impurities and improving the purity of the biochar, providing quality assurance for subsequent use in cosmetics. 3. The Polygonum multiflorum biochar produced by this preparation method can be used in eyebrow makeup products such as eyebrow pencils and eyebrow tints, which can significantly improve the product efficacy. In eyebrow pencils, its porous structure can absorb oil and dirt around the eyebrows, creating conditions for uniform coloring. At the same time, the nourishing ingredients can penetrate and nourish the hair follicles, promoting eyebrow growth. In eyebrow tints, the adsorption properties help fix the dye, prolong the durability of the eyebrow dyeing effect, reduce fading and smudging, and the nourishing effect can improve the texture of the eyebrows, making them soft and shiny. This meets the special needs of the cosmetics field, especially eyebrow makeup products, for functional carbon materials. DETAILED DESCRIPTION

[0024] To more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments. It should be understood that the embodiments described are only a portion of the present invention, not all of the embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0025] The purpose of the present invention is illustrated by the following examples. The components of the composition are illustrated in parts by weight as a general standard. Unless otherwise specified, for the sake of simplicity, the "parts" described in the examples of the present invention have the same meaning as parts by weight.

[0026] Unless otherwise specified, all reagents and instruments used were commercially available.

[0027] Performance testing experiment (1) Eyebrow nourishing efficacy test Twenty subjects were selected, and their eyebrows were smeared with eyebrow pencils and eyebrow dye samples containing Polygonum multiflorum biochar prepared in the application examples and the comparative examples, and a control sample without Polygonum multiflorum biochar.

[0028] After 1 and 4 weeks, the surface morphology and scale status of eyebrows were observed to evaluate the nourishing effect of Polygonum multiflorum biochar on eyebrows.

[0029] (2) Long-lasting coloring efficacy test On the artificial skin model, the skin model with the sample applied was rubbed with a certain pressure and frequency using a friction tester, and then the color parameters were measured again using a colorimeter, the color change value was calculated, and the impact of the lasting coloring effect was evaluated.

[0030] Example 1 A method for preparing Polygonum multiflorum biochar comprises the following steps: S1, wash the fresh polygonum multiflorum root block to remove impurities, slice the washed polygonum multiflorum, put it into a drying box for drying and dehydration, put the dried polygonum multiflorum slices into a pulverizer for pulverizing treatment to powder, and obtain polygonum multiflorum powder with a pulverizing particle size of 80-120 mesh; S2, place 120g of the polygonum multiflorum powder in S1 into a high-temperature and high-pressure reaction kettle, add 480g of water and 1.2g of aluminum chloride, set the carbonization temperature to 200℃, and the carbonization reaction time to 4h, and obtain the carbonized raw slurry by cooling; S3, take out the raw slurry in S2 for filtration, first use 1% dilute hydrochloric acid for acid washing, then use clean water for washing until the filtrate is clear, put the filter cake into an oven for drying, put the dried filter cake into a pulverizer for pulverizing, and filter with a 200 mesh screen to obtain polygonum multiflorum biochar.

[0031] Example 2 A preparation method of polygonum multiflorum biochar, comprising the following steps: S1, wash the fresh polygonum multiflorum root block to remove impurities, slice the washed polygonum multiflorum, put it into a drying box for drying and dehydration, put the dried polygonum multiflorum slices into a pulverizer for pulverizing treatment to powder, and obtain polygonum multiflorum powder with a pulverizing particle size of 80-120 mesh; S2, place 120g of the polygonum multiflorum powder in S1 into a high-temperature and high-pressure reaction kettle, add 480g of water and 1.2g of aluminum chloride, set the carbonization temperature to 200℃, and the carbonization reaction time to 4h, and obtain the carbonized raw slurry by cooling; S3, take out the raw slurry in S2 for filtration, first use 1% dilute hydrochloric acid for acid washing, then use clean water for washing until the filtrate is clear, put the filter cake into an oven for drying, put the dried filter cake into a pulverizer for pulverizing, and filter with a 200 mesh screen to obtain polygonum multiflorum biochar.

[0032] Example 3 A preparation method of polygonum multiflorum biochar, comprising the following steps: S1, wash the fresh polygonum multiflorum root block to remove impurities, slice the washed polygonum multiflorum, put it into a drying box for drying and dehydration, put the dried polygonum multiflorum slices into a pulverizer for pulverizing treatment to powder, and obtain polygonum multiflorum powder with a pulverizing particle size of 80-120 mesh; S2, place 120g of the polygonum multiflorum powder in S1 into a high-temperature and high-pressure reaction kettle, add 480g of water and 1.2g of aluminum chloride, set the carbonization temperature to 200℃, and the carbonization reaction time to 4h, and obtain the carbonized raw slurry by cooling; S3. The raw pulp in S2 is taken out and filtered, firstly pickled with 1% dilute hydrochloric acid, then washed with clean water until the filtrate is clear, the filter cake is placed in an oven to dry, the dried filter cake is placed in a grinder to be crushed, and filtered with a 200-mesh sieve to obtain Polygonum multiflorum biochar.

[0033] Example 4 A method for preparing Polygonum multiflorum biochar comprises the following steps: S1, the fresh root of Polygonum multiflorum is cleaned to remove impurities, the cleaned Polygonum multiflorum is sliced, placed in a drying oven for drying and dehydration, the dried Polygonum multiflorum slices are placed in a grinder and pulverized to powder, and the pulverized particle size is 80-120 mesh Polygonum multiflorum powder; S2, placing 120g of Polygonum multiflorum powder in S1 in a high-temperature and high-pressure reactor, adding 600g of water and 2.4g of phosphoric acid, setting the carbonization temperature to 200°C and the carbonization reaction time to 3h, and cooling to obtain a carbonized slurry; S3. The raw pulp in S2 is taken out and filtered, firstly pickled with 1% dilute hydrochloric acid, then washed with clean water until the filtrate is clear, the filter cake is placed in an oven to dry, the dried filter cake is placed in a grinder to be crushed, and filtered with a 200-mesh sieve to obtain Polygonum multiflorum biochar.

[0034] Comparative Example 1 A method for preparing Polygonum multiflorum biochar is different from that of Example 1 in that the Polygonum multiflorum biochar is prepared by a high-temperature calcination method.

[0035] Application Example 1 A kind of eyebrow pencil, it is made by the following method: Add candelilla wax, carnauba wax, squalane, and jojoba oil to a reactor and heat to 90°C with stirring until completely melted. Slowly add the pre-mixed Polygonum multiflorum carbon powder, black iron oxide, and kaolin prepared in Example 1 and stir at 800 rpm for 30 minutes to ensure uniform dispersion. Cool to 60°C, add the preservative system, stir at low speed for 10 minutes, vacuum degas the mixture to remove bubbles, and further disperse the particles through ultrasonic treatment to improve the uniformity of the refill; The molten material is injected into the eyebrow pencil mold and quickly cooled using a water cooling circulation system, shortening the curing time to 30 minutes. After demoulding, the pen core is placed in a constant temperature and humidity room (25°C, 50% RH) for 24 hours to eliminate internal stress. The pen core is then assembled with the wooden pen holder to obtain the product.

[0036] Application Example 2 An eyebrow pencil is different from the one in application example 1 in that the Polygonum multiflorum charcoal powder is prepared from the one in application example 2.

[0037] Application Example 3 An eyebrow pencil, which is different from the one in Application Example 1 only in that the Polygonum multiflorum charcoal powder is prepared from Example 3.

[0038] Application Example 4 An eyebrow pencil, which is different from the one in Application Example 1 only in that the Polygonum multiflorum charcoal powder is prepared from Example 4.

[0039] Application Example 5 A kind of eyebrow dyeing cream, it is prepared by the following method: Add deionized water, glycerin, and butylene glycol to a reaction kettle, heat to 75°C, and stir until completely dissolved. Slowly sprinkle in Carbopol Ultrez 21 and disperse at high speed for 30 minutes to ensure no lumps. Cool to 50°C, add panthenol, and stir for 10 minutes to obtain the aqueous phase. Silicone oil, squalane, the Polygonum multiflorum carbon powder prepared in Example 1, and black iron oxide were mixed and ground three times using a three-roll mill to obtain an oil phase; Slowly add the oil phase into the water phase and homogenize at 1500 rpm for 15 minutes to form a stable emulsion. Add triethanolamine dropwise to adjust the pH to 6.0. Continue stirring for 5 minutes to allow the film-forming agent to fully swell. Vacuum degas the emulsion to remove bubbles and fill it at 40°C.

[0040] Application Example 6 An eyebrow tinting cream is different from the one in Application Example 5 in that the Polygonum multiflorum charcoal powder is prepared from Example 2.

[0041] Application Example 7 An eyebrow tinting cream is different from the one in Application Example 5 in that the Polygonum multiflorum charcoal powder is prepared from Example 3.

[0042] Application Example 8 An eyebrow tinting cream is different from the one in Application Example 5 in that the Polygonum multiflorum charcoal powder is prepared from that in Application Example 4.

[0043] Comparative Application Example 1 An eyebrow pencil, which is different from the application example 1 only in that the Polygonum multiflorum charcoal powder is prepared from the comparative example 1.

[0044] Application Comparative Example 2 An eyebrow tinting cream is different from the one in Application Example 5 in that the Polygonum multiflorum charcoal powder is prepared from Comparative Example 1.

[0045] The performance test of the samples prepared in the above application examples and application comparative examples was carried out according to the above test methods.

[0046] As can be seen from the above table, in terms of the comprehensive performance of eyebrow nourishing effect and long-lasting coloring effect, the application examples have significant advantages. From the perspective of eyebrow nourishing effect, in application examples 1-8, whether it is an eyebrow pencil or an eyebrow dyeing cream sample, when observed in the 1st and 4th weeks, the eyebrow surface morphology remains smooth, and the hair scale state is well closed. This fully demonstrates that the Polygonum multiflorum biochar prepared by Examples 1-4 is added to eyebrow pencils and eyebrow dyeing creams, which has a good nourishing effect on eyebrows, can maintain the healthy state of eyebrows for a long time, and helps to protect the hair scales of eyebrows, keep them closed, and reduce hair damage; in sharp contrast, in application comparative example 1 and application comparative example 2, the eyebrow surface morphology appears rough, has dandruff, etc., and the hair scale state is open or damaged, which shows that comparative example 1 uses the Polygonum multiflorum biochar prepared by high-temperature calcination method, which is less effective in nourishing eyebrows. It may be due to the different preparation methods that the composition or structure of the Polygonum multiflorum biochar changes, thereby losing the nourishing and protective effect on eyebrows. At the same time, when the eyebrows of the blank control (without active ingredients related to Polygonum multiflorum biochar) were observed in the 1st and 4th weeks, the surface morphology was rough and dandruffy, and the hair scales were open, further highlighting the importance of Polygonum multiflorum biochar in nourishing the eyebrows. The nourishing effect of the Polygonum multiflorum biochar in the application example on the eyebrows was significantly better than that without addition.

[0047] In terms of long-lasting coloring, the overall color change evaluation for Examples 1-8 was "Excellent." Although the color change values ​​(ΔL, Δa, Δb*) varied, the absolute values ​​were relatively small. This indicates that the Polygonum multiflorum biochar prepared in Examples 1-4, when added to eyebrow pencils and eyebrow tints, imparts a long-lasting coloring effect. After the friction test, the color change remained within an acceptable range, demonstrating that the Polygonum multiflorum biochar helps improve the coloring stability and durability of the products. The comprehensive evaluation of the color change of comparative example 1 was "medium", and that of comparative example 2 was "good". Compared with the embodiments, the absolute values ​​of the color change values ​​of the comparative examples were larger, indicating that the Polygonum multiflorum biochar prepared in comparative example 1 did not perform as well as the embodiments in terms of long-lasting coloring. This may be because the Polygonum multiflorum biochar prepared by the high-temperature calcination method is not conducive to the stable adhesion of color in terms of composition or structure, resulting in a large color change of the product after friction and poor long-lasting coloring effect.

[0048] In summary, the application examples performed well in both eyebrow nourishing and long-lasting coloring effects, indicating that the Polygonum multiflorum biochar prepared in Examples 1-4 has a good application effect in eyebrow pencils and eyebrow tint products, and can simultaneously meet consumers' needs for eyebrow nourishing and long-lasting coloring.

[0049] The above are all modifications that a person skilled in the art can make to this embodiment as needed after reading this specification, which do not contribute creatively or solutions that obviously constitute technical inspiration. However, as long as they are within the scope of the claims of this application, they should be protected by patent law.

Claims

1. A method for preparing Polygonum multiflorum biochar, characterized in that: The following steps are involved: S1. Wash and slice the root of Polygonum multiflorum, dry it, and then grind it into powder; S2, placing the powder obtained in S1 into a reactor, adding water and a catalyst for carbonization to obtain a carbonized slurry; S3. Filter the raw pulp, wash with water after acid washing until it is clear, dry the filter cake and crush it, and pass it through a 200-mesh sieve to obtain Polygonum multiflorum biochar.

2. The method for preparing Polygonum multiflorum biochar according to claim 1, wherein The powder in S1 has a particle size of 80-120 mesh.

3. The method for preparing Polygonum multiflorum biochar according to claim 1, wherein The mass ratio of the Polygonum multiflorum powder to water in S2 is 1:2-10 kg / kg.

4. The method for preparing Polygonum multiflorum biochar according to claim 1, wherein The mass ratio of the Polygonum multiflorum powder to the catalyst in S2 is 1:0.01-0.1 kg / kg.

5. The method for preparing Polygonum multiflorum biochar according to claim 1, wherein The catalyst in S2 is selected from at least one of potassium hydroxide, sodium hydroxide, ferric chloride, phosphoric acid, aluminum chloride, and zinc chloride.

6. The method for preparing Polygonum multiflorum biochar according to claim 1, wherein: The carbonization temperature in S2 is 150-300° C., and the carbonization time is 1-8 hours.

7. The method for preparing Polygonum multiflorum biochar according to claim 1, wherein: In the pickling step S3, dilute hydrochloric acid with a concentration of 1-3% is used.

8. Use of the Polygonum multiflorum biochar produced by the method for producing Polygonum multiflorum biochar according to any one of claims 1 to 7 in cosmetics.

9. The use according to claim 8, characterized in that The cosmetics include eyebrow pencils and eyebrow tints.

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