Method for preparing humic acid by using biomass
By roasting and hydrothermal treatment of biomass raw materials, combined with acid treatment, the problem of low efficiency in humic acid preparation in existing technologies has been solved, realizing efficient and economical humic acid preparation and agricultural application.
Patent Information
- Application Number
- CN202511711806.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-20
- Publication Date
- 2026-01-09
AI Technical Summary
In existing technologies, the preparation of humic acid by microbial and hydrothermal methods suffers from problems such as low reaction rate, low yield, long cycle and high energy consumption, which makes it difficult to meet market demand. Moreover, coal resources are non-renewable, which restricts the industrial application of biomass resources.
Semi-coke is produced by roasting biomass raw materials, which is then reacted hydrothermally with sodium hydroxide solution. Subsequently, it is mixed with acid and separated into solid and liquid components to obtain humic acid. The molecular weight and solubility of the product are optimized by controlling the reaction conditions.
It achieves efficient and economical production of humic acid from biomass resources, with increased yield, suitable for promoting germination and improving fertilizer utilization in agriculture, and the raw materials are renewable.
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Figure CN121293529A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of comprehensive utilization of biomass resources, and particularly relates to a method for preparing humic acid from biomass. BACKGROUND
[0002] Humic acid is a kind of high-molecular organic substance in nature, which has no specific structure and chemical configuration, and is mainly derived from the sediments after the decomposition of soil, water and plant bodies by microorganisms. Due to the different geographical environment, climate and biological environment during the formation of humic acid, the structure of humic acid is complex and diverse. Each structural unit of humic acid mainly includes aromatic ring and active functional groups, and the active functional groups include phenolic hydroxyl, alcoholic hydroxyl, carboxyl, carbonyl, quinone, enol and amino groups. The above active functional groups enable humic acid to interact with most organic and inorganic substances, and experiments have proved that humic acid has good physiological activity and complexing, absorption and exchange functions. Due to the structural characteristics of humic acid molecules, humic acid has special properties such as colloidal property, weak acidity, hydrophilicity, photochemical activity and oxidation and reduction, and has broad application prospects in industry, agriculture, medicine and composite materials.
[0003] At present, commercial humic acid is mainly derived from peat, lignite and weathered coal and other coal resources, but lignite, weathered coal and the like belong to non-renewable resources, and the extraction of humic acid from coal resources cannot meet the current market demand, so the development and application of high-quality humic acid have become the focus of attention.
[0004] At present, the methods for artificially synthesizing humic acid mainly include microbial method and hydrothermal method. The microbial method is to convert and synthesize humic acid from biomass raw materials under the action of microorganisms, but has problems such as low reaction rate, low yield, long cycle and the like; the simple one-step hydrothermal method for preparing humic acid from biomass cannot obtain ideal yield. Methods such as first acid hydrothermal treatment and then alkaline hydrothermal treatment of biomass, first composting and then alkaline hydrothermal treatment, alkaline hydrothermal treatment and then composting and the like are used to improve the yield of artificial humification of biomass. Among them, in 2023, for the first time, two-step hydrothermal method was used to convert waste biomass into artificial humus, and the yield of humic acid was 28.28wt%, which was the highest value in similar studies found in the literature at that time. However, it should be noted that acid hot liquid requires a large amount of energy input, and the amount of acid and alkali is large, which seriously restricts the industrialization of preparation of humic acid from biomass resources. Therefore, it is necessary to seek an efficient and economical pretreatment method for biomass.
[0005] In view of this, the present application is proposed. SUMMARY
[0006] The purpose of the present application is to provide a method for preparing humic acid from biomass.
[0007] To achieve the above purpose, the present application adopts the following technical solution: A method for preparing humic acid using biomass, comprising: carrying out a torrefaction reaction on the biomass raw material to obtain semi-coke; mixing the semi-coke with an aqueous sodium hydroxide solution to carry out a hydrothermal reaction, and then carrying out a first solid-liquid separation to obtain a liquid phase product; mixing the liquid phase product with an acid, and after treatment, carrying out a second solid-liquid separation to obtain humic acid.
[0008] Preferably, the temperature of the torrefaction reaction is 200-500℃, and the temperature rising rate is 5-20℃ / min.
[0009] Preferably, the temperature of the hydrothermal reaction is 120-200℃, and the time is 0.5-6h.
[0010] Preferably, the concentration of the aqueous sodium hydroxide solution is 1-6mol / L.
[0011] Preferably, the solid-liquid ratio of the semi-coke to the aqueous sodium hydroxide solution is 1g:20-60mL.
[0012] Preferably, the acid comprises hydrochloric acid, and the concentration of the hydrochloric acid is 1-6mol / L.
[0013] Preferably, after the acid is mixed with the liquid phase product, the pH of the system is 0-1.
[0014] Preferably, the biomass raw material comprises crop straw and / or forest processing waste.
[0015] Preferably, the particle size of the biomass raw material is less than or equal to 20 mesh.
[0016] The small molecular weight can promote the characteristics of seed germination, promote the absorption of fertilizers and improve the yield of crops.
[0017] The beneficial effects of the present application are: The method for preparing humic acid by using biomass provided in the application first performs a thermal cracking reaction on the biomass raw material, breaks the chemical bonds with low bond energy such as carboxyl, hydroxyl and methoxyl on the lignin by heating to generate a large number of free radicals, and then performs a hydrothermal reaction to generate a series of secondary reactions such as aldehyde-phenol condensation with the semi-coke after the above baking, to generate complex reaction products, but the overall reaction direction is dehydration, deoxygenation and aromatization, to achieve the purpose of improving the proportion of polycyclic and heterocyclic aromatic hydrocarbons, which is suitable for the conversion of biomass to humic acid. At this time, in addition to the above chemical reactions of biomass, the other two components in biomass, cellulose and hemicellulose, mainly undergo glycosidic bond breaking, dehydration and aromatic ring formation, etc. After completing the first step of thermal cracking, the generated semi-coke still needs to go through an oxidative cracking step to further oxidize and break some unsaturated bonds, alkyl groups, etc., to re-generate hydrophilic groups such as carboxyl groups so that they can be dissolved. Finally, neutralization and extraction are performed with acid to separate the humic acid product from the cellulose and hemicellulose residues. By adjusting the reaction conditions of the oxidative cracking step, the molecular weight and water solubility of the product can be controlled to produce humic acid that is insoluble in acid and water but soluble in alkali, or fulvic acid that is soluble in acid, water and alkali. Controlling the molecular weight to be below 130 kDa is conducive to obtaining humic acid products that are more easily absorbed by plants and have better agricultural application effects.
[0018] The main components of humic acid are derived from plant biomolecules such as lignin, lipids, tannins, and carbohydrates. Biomass is mainly composed of cellulose (40%-50%), hemicellulose (25%-35%), and lignin (15%-20%), and these components can be biochemically converted into humic acid. The raw materials for bio-humic acid are abundant, mainly including agricultural products and renewable industrial raw material waste, including crop straw, sawdust, animal manure, papermaking waste liquid, etc. Using abundant biological waste to produce humic acid is a new green economic approach to humic acid production, and is also a promising method for biomass value-added, which is expected to become a major source of humic acid in the future.
[0019] The method provided in the application has a simple preparation process and low cost, and the obtained biomass humic acid can promote germination, growth and improve the utilization rate of mineral fertilizers. BRIEF DESCRIPTION OF DRAWINGS
[0020] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.
[0021] Figure 1 The process flow diagram of the method for preparing humic acid by using biomass provided for the embodiments; Figure 2 The actual picture of the substance obtained by acid precipitation of the acid in Example 1; Figure 3 The results of water-cultured corn of humic acid obtained by acid precipitation of the acid in Example 1; Figure 4 The graph of the relationship between temperature and humic acid yield in Example 1. DETAILED DESCRIPTION
[0022] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.
[0023] Example 1 As shown in the following table, the present embodiment provides a method for preparing humic acid using biomass, comprising the following steps: Figure 1 100g of cotton stalks are crushed, dried and divided, 10g of the cotton stalks are placed in a tube furnace, the temperature of the tube furnace is controlled at 200℃, the heating rate is 20℃ / min, after 90min of reaction, the product semi-coke is obtained after cooling to room temperature, which is 8.6g. 1g of the semi-coke is mixed with 40ml of 1mol / L sodium hydroxide solution, and placed in a hydrothermal reaction kettle for hydrothermal reaction. The temperature of the hydrothermal reaction is 180℃, and the duration of the hydrothermal reaction is 4h, to obtain a hydrothermal product. The hydrothermal product is subjected to solid-liquid separation to obtain a hydrothermal liquid and a hydrothermal carbon, 6mol / L hydrochloric acid is added to the hydrothermal liquid, and the pH is adjusted to 0-1. The hydrothermal liquid after acid precipitation is subjected to solid-liquid separation to obtain a black precipitate product, humic acid 0.24g.
[0024] The actual picture of the substance obtained by acid precipitation, Figure 2 The comparison chart of the water-cultured corn of humic acid obtained in Example 1 and the blank sample, which can be seen that it has a great promoting effect on the roots of corn. Figure 3 Example 2
[0025] The present embodiment provides a method for preparing humic acid using biomass, comprising the following steps: The present embodiment provides a method for preparing humic acid using biomass, comprising the following steps: 100g cotton stalks were broken, dried, and fractionated, and 10g of the cotton stalks were placed in a tube furnace, the temperature of the tube furnace was controlled at 250℃, the heating rate was 15℃ / min, and after 90min of reaction, the product semi-coke was obtained after cooling to room temperature. The semi-coke was mixed with 40ml of 1mol / L sodium hydroxide solution, and placed in a hydrothermal reactor for hydrothermal reaction. The temperature of the hydrothermal reaction was 180℃, and the hydrothermal reaction time was 4h, to obtain a hydrothermal product. The hydrothermal product was subjected to solid-liquid separation, to obtain a hydrothermal liquid and a hydrothermal carbon. 6mol / L hydrochloric acid was added to the hydrothermal liquid, and the pH was adjusted to 0-1. The acid precipitate was subjected to solid-liquid separation, to obtain a black precipitate product, humic acid, 0.5g.
[0026] Example 3 The present example provides a method for preparing humic acid using biomass, comprising the following steps: 100g cotton stalks were broken, dried, and fractionated, and 10g of the cotton stalks were placed in a tube furnace, the temperature of the tube furnace was controlled at 300℃, the heating rate was 5℃ / min, and after 60min of reaction, the product semi-coke was obtained after cooling to room temperature. The semi-coke was mixed with 40ml of 1mol / L sodium hydroxide solution, and placed in a hydrothermal reactor for hydrothermal reaction. The temperature of the hydrothermal reaction was 180℃, and the hydrothermal reaction time was 4h, to obtain a hydrothermal product. The hydrothermal product was subjected to solid-liquid separation, to obtain a hydrothermal liquid and a hydrothermal carbon. 6mol / L hydrochloric acid was added to the hydrothermal liquid, and the pH was adjusted to 0-1. The acid precipitate was subjected to solid-liquid separation, to obtain a black precipitate product, humic acid, 0.57g.
[0027] Example 4 The present example provides a method for preparing humic acid using biomass, comprising the following steps: 100g cotton stalks were broken, dried, and fractionated, and 10g of the cotton stalks were placed in a tube furnace, the temperature of the tube furnace was controlled at 350℃, the heating rate was 15℃ / min, and after 45min of reaction, the product semi-coke was obtained after cooling to room temperature. The semi-coke was mixed with 40ml of 1mol / L sodium hydroxide solution, and placed in a hydrothermal reactor for hydrothermal reaction. The temperature of the hydrothermal reaction was 180℃, and the hydrothermal reaction time was 4h, to obtain a hydrothermal product. The hydrothermal product was subjected to solid-liquid separation, to obtain a hydrothermal liquid and a hydrothermal carbon. 6mol / L hydrochloric acid was added to the hydrothermal liquid, and the pH was adjusted to 0-1. The acid precipitate was subjected to solid-liquid separation, to obtain a black precipitate product, humic acid, 0.15g.
[0028] Example 5 The present example provides a method for preparing humic acid using biomass, comprising the following steps: The 100 g cotton stalks were broken, dried, and sieved into 20-40 mesh. 10 g of the cotton stalks were placed in a tube furnace, the temperature of which was controlled at 400°C, and the heating rate was 20°C / min. After 60 min of reaction, the product semi-coke was obtained after cooling to room temperature. The semi-coke was mixed with 40 ml of 1 mol / L sodium hydroxide solution, and placed in a hydrothermal reactor for hydrothermal reaction. The temperature of the hydrothermal reaction was 180°C, and the reaction time was 4 h. The hydrothermal product was obtained. The hydrothermal product was subjected to solid-liquid separation to obtain a hydrothermal liquid and a hydrothermal carbon. 6 mol / L hydrochloric acid was added to the hydrothermal liquid, and the pH was adjusted to 0-1. The acid precipitate was subjected to solid-liquid separation to obtain a black precipitate product, humic acid, 0.46 g.
[0029] Example 6 The present example provides a method for preparing humic acid using biomass, comprising the following steps: The 100 g cotton stalks were broken, dried, and sieved into 20-40 mesh. 10 g of the cotton stalks were placed in a tube furnace, the temperature of which was controlled at 500°C, and the heating rate was 20°C / min. After 60 min of reaction, the product semi-coke was obtained after cooling to room temperature. The semi-coke was mixed with 40 ml of 1 mol / L sodium hydroxide solution, and placed in a hydrothermal reactor for hydrothermal reaction. The temperature of the hydrothermal reaction was 180°C, and the reaction time was 1 h. The hydrothermal product was obtained. The hydrothermal product was subjected to solid-liquid separation to obtain a hydrothermal liquid and a hydrothermal carbon. 6 mol / L hydrochloric acid was added to the hydrothermal liquid, and the pH was adjusted to 0-1. The acid precipitate was subjected to solid-liquid separation to obtain a black precipitate product, humic acid, 0.03 g.
[0030] Comparative Example 1 In order to demonstrate the importance of the temperature of the roasting reaction, a roasting temperature control test was performed, and the results are shown in Table 1. Figure 4 As shown in Table 1, as the temperature increased, the weight loss of the material increased, resulting in a decrease in the yield of humic acid. Moreover, a large amount of hydrothermal carbon was produced. Figure 4 Therefore, the roasting temperature should not exceed 500°C, and the optimal temperature is 300°C.
[0031] Comparative Example 2
[0032] Unlike Example 3, no roasting reaction was performed, and the hydrothermal reaction was performed directly.
[0033] 1g of dried cotton stalks were mixed with 40ml of 1mol / L sodium hydroxide solution and placed in a hydrothermal reactor for hydrothermal reaction. The temperature of the hydrothermal reaction was 180℃ and the reaction time was 4h to obtain a hydrothermal product. The hydrothermal product was subjected to solid-liquid separation to obtain a hydrothermal liquid and a hydrothermal carbon. 6mol / L hydrochloric acid was added to the hydrothermal liquid to adjust the pH to 0-1. The acid precipitate of the hydrothermal liquid was subjected to solid-liquid separation to obtain 0.1g of black precipitate product humic acid.
[0034] Comparative Example 3 Unlike Example 3, no hydrothermal reaction was performed.
[0035] No hydrothermal reaction was performed and almost no humic acid was produced.
[0036] Note that the technical features of the above examples can be combined in any way. In order to make the description simple, all possible combinations of the technical features in the above examples are not described, however, as long as the combinations of the technical features do not contradict each other, they should be considered as within the scope of the present disclosure. The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.
Claims
1. A method for preparing humic acid using biomass, characterized in that, include: Semi-charred material is obtained by roasting biomass raw materials; The semi-coke was mixed with an aqueous sodium hydroxide solution and subjected to a hydrothermal reaction, followed by a first solid-liquid separation to obtain a liquid phase product. The liquid product is mixed with acid, and after treatment, a second solid-liquid separation is performed to obtain humic acid.
2. The method for preparing humic acid using biomass according to claim 1, characterized in that, The baking reaction is carried out at a temperature of 200-500℃ and a heating rate of 5-20℃ / min.
3. The method for preparing humic acid using biomass according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 120-200℃ for a duration of 0.5-6 hours.
4. The method for preparing humic acid using biomass according to claim 1, characterized in that, The concentration of the sodium hydroxide aqueous solution is 1-6 mol / L.
5. The method for preparing humic acid using biomass according to claim 4, characterized in that, The solid-liquid ratio of the semi-coke to the sodium hydroxide aqueous solution is 1g:20-60mL.
6. The method for preparing humic acid using biomass according to claim 1, characterized in that, The acid includes hydrochloric acid, and the concentration of the hydrochloric acid is 1-6 mol / L.
7. The method for preparing humic acid using biomass according to claim 1, characterized in that, When the acid is mixed with the liquid product, the pH of the system is 0-1.
8. The method for preparing humic acid using biomass according to claim 1, characterized in that, The biomass raw materials include crop straw and / or forestry processing waste.
9. The method for preparing humic acid using biomass according to claim 8, characterized in that, The biomass raw material has a particle size of less than or equal to 20 mesh.