Method for preparing humus through subcritical hydrolysis of waste mushroom sticks and application

Abstract

The invention relates to the technical field of waste recycling, and particularly discloses a method for preparing humus by subcritical hydrolysis of waste mushroom sticks, which comprises the following steps: adding mushroom stick powder into alkali liquor or acid liquor, adding H2O2 and FeSO4, adding ethylenediamine tetraacetic acid under an alkaline condition, and uniformly stirring to form a mixture; transferring the mixture into a high-pressure reaction kettle, reacting for a period of time at normal temperature, and then carrying out subcritical hydrothermal reaction to obtain a product 1; continuing to decay the product 1 and then carrying out suction filtration and solid-liquid separation to obtain a humus-containing liquid product. According to the method, the waste mushroom sticks are subjected to subcritical hydrolysis treatment to prepare the humus, the hydrolysis efficiency of the mushroom sticks is remarkably improved, and the hydrolysis rate reaches 80% or above. In addition, the temperature of the whole hydrothermal reaction is lower than that of a traditional pyrolysis or chemical oxidation process, energy consumption is greatly reduced, meanwhile, damage of high-temperature treatment to the humic acid structure is avoided, and the functionality of the product is effectively protected.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste recycling, and particularly relates to a method and application for preparing humus by subcritical hydrolysis of waste mushroom sticks. Background Art

[0002] Humus is an important class of organic matter widely present in nature, mainly formed by the decomposition of animal and plant residues through microbial action and geochemical processes. It plays a key role in soil, being the main component of soil organic matter, and also has important effects in maintaining soil fertility, improving soil structure, and remediating polluted soil. The functional group structures such as carboxyl, hydroxyl, and phenolic groups in humus endow it with excellent heavy metal complexation ability, organic pollutant adsorption performance, and electron transfer characteristics. These characteristics enable humus to exhibit great application potential in environmental governance, agricultural fertilizer development, chemical production, and the medical field.

[0003] Subcritical hydrolysis technology is a method for efficiently converting organic matter under mild conditions, especially suitable for treating complex biomass. This technology utilizes the unique properties of water under high temperature and high pressure (between 100°C and 374°C, with pressure below the critical pressure of water), enabling it to have both the dissolving ability of liquid water and the permeability similar to steam. This characteristic allows water in the subcritical state to effectively break the chemical bonds in biomass, such as cellulose, hemicellulose, and lignin, and convert them into small molecule organic substances or monomers, such as sugars, phenols, and organic acids. Compared with traditional hydrolysis methods, subcritical hydrolysis has the advantages of short reaction time, high efficiency, and the need not to add a large amount of catalysts or chemical reagents, so it has received extensive attention in the field of waste recycling.

[0004] Mushroom sticks are the main waste generated during the cultivation of edible mushrooms, mainly composed of agricultural and forestry wastes (such as straw, wood chips, bran, etc.). With the rapid development of the edible mushroom industry, the annual output of mushroom sticks has been increasing year by year, becoming a large amount of agricultural waste with a wide distribution. According to statistics, the annual output of mushroom sticks in China can reach tens of millions of tons. Due to its rich organic substances such as cellulose, hemicellulose, and lignin, mushroom sticks have high potential for resource utilization. However, at present, the treatment methods of mushroom sticks still mainly include direct disposal, incineration, or simple composting, which not only cause waste of resources but also may lead to environmental pollution problems, such as soil acidification and water eutrophication. In recent years, with the enhancement of environmental awareness and the development of technology, the resource utilization of mushroom sticks has gradually attracted attention, including ways such as preparing biological fertilizers, feeds, bioenergy, and high-value-added chemicals.

[0005] A Chinese patent with the publication number CN108329487A discloses a method for extracting humic acid from straw. It uses sepiolite powder or a combination of sepiolite powder and bone meal as a straw accelerating decay agent and selects EM bacteria agent for inoculation and cultivation. This method is complex in operation, takes a long time, and there are also some problems in the production and preservation of EM bacteria.

[0006] A Chinese patent with the publication number CN111621033A discloses a method for extracting humic acid from lavender distillation waste residue. It adopts an alkali dissolution - acid precipitation process to obtain high - quality humic acid from lavender distillation waste residue. Using this method to extract humic acid has a long high - temperature reaction time of 10h and a low extraction efficiency. Summary of the Invention

[0007] In view of the above - mentioned prior art, the present invention provides a method for preparing humus by sub - critical hydrolysis of waste mushroom sticks to achieve the purpose of resource utilization of mushroom sticks. To achieve the above purpose, the technical solution adopted by the present invention is to provide a method for preparing humus by sub - critical hydrolysis of waste mushroom sticks, including the following steps:

[0008] S1: Crush the mushroom sticks to a particle size within a certain range to obtain mushroom stick powder;

[0009] S2: Add the mushroom stick powder obtained in step S1 to an alkali solution or an acid solution, add H2O2 and FeSO4, and add ethylenediaminetetraacetic acid under alkaline conditions, and stir evenly to form a mixture; the solid - liquid ratio of the mushroom stick powder to the alkali solution is 1g:6 - 12ml or the solid - liquid ratio of the mushroom stick powder to the acid solution is 1g:6 - 12ml; the added volume of H2O2 is 1 - 10% of the volume of the alkali solution or the acid solution;

[0010] S3: Transfer the mixture obtained in step S2 to a high - pressure reaction kettle respectively, carry out a normal - temperature reaction for a period of time and then carry out a sub - critical hydrothermal reaction; the normal - temperature reaction time is 30 - 60min, the temperature of the sub - critical hydrolysis reaction is 150 - 300°C, and the time is 30 - 240min. After the reaction is completed, product 1 is obtained;

[0011] S4: Filter the product 1 obtained in step S3, separate the solid and liquid, collect the solid and the liquid, and obtain a humus - containing liquid product A and a solid product B respectively;

[0012] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven to obtain a solid powder. Calculate the hydrolysis conversion rate according to the following formula (1) based on the mass of the obtained hydrolyzed solid product:

[0013] Y S =(1 - M S / M L )×100%(1)

[0014] where M S : represents the mass of the solid product after the reaction, unit: g

[0015] M L : represents the mass of the mushroom stick powder added before the reaction, unit: g.

[0016] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, in the step S1, the particle size of the mushroom stick powder is 10 mesh to 50 mesh.

[0017] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the alkali solution is potassium hydroxide solution, sodium hydroxide solution or ammonia water solution.

[0018] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the acid solution is phosphoric acid solution or hydrochloric acid solution.

[0019] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the pH value of the alkali solution is 9 to 13.

[0020] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the pH value of the acid solution is 1 to 5.

[0021] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the solid-liquid ratio of the mushroom stick powder to the alkali solution is 1 g: 8 to 12 ml; the solid-liquid ratio of the mushroom stick powder to the acid solution is 1 g: 10 to 12 ml.

[0022] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the volume of H2O2 added is 5 to 10% of the solution volume, and the molar ratio of FeSO4 to H2O2 is 1:1.

[0023] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the molar ratio of ethylenediaminetetraacetic acid to FeSO4 is 1:1. Adding ethylenediaminetetraacetic acid can improve the hydrolysis efficiency of mushroom sticks.

[0024] Preferably, in the method for preparing humus by subcritical hydrolysis of waste mushroom sticks, the reaction time at room temperature in the step S3 is 30 - 60 min, the temperature of the subcritical water hydrolysis reaction is 150 - 300 °C, and the time is 30 - 240 min; further preferably, the temperature of the subcritical hydrolysis reaction is 200 - 300 °C, and the reaction time is 90 - 150 min.

[0025] Preferably, in the method for preparing humus from waste mushroom sticks by subcritical hydrolysis, the suction filtration time is 30-60 min, and in step S5, the drying time is 12-48 h, preferably 24-48 h.

[0026] On the other hand, the present invention also provides an application of the humus prepared by the method for preparing humus from waste mushroom sticks by subcritical hydrolysis as described above in foliar fertilizer.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The present invention uses mushroom sticks as raw materials to prepare humic acid. Mushroom sticks are common agricultural wastes, which are rich in sources and low in price. By converting them into humic acid with high added value, not only the raw material cost is reduced, but also the waste treatment problem is solved, realizing the double benefits of economy and environmental protection.

[0029] 2. The present invention conducts subcritical hydrolysis treatment on waste mushroom sticks to prepare humus. By combining the subcritical hydrolysis technology, the hydroxyl radicals (·OH) generated by the reaction of H2O2 and FeSO4, and the strong oxidation effect of the oxygen generated by the thermal decomposition of H2O2 at high temperature, the hydrolysis efficiency of mushroom sticks is significantly improved, and the hydrolysis rate reaches more than 80%. In addition, the whole hydrothermal reaction temperature is lower than that of traditional pyrolysis or chemical oxidation processes, greatly reducing the energy consumption, and at the same time avoiding the damage to the structure of humic acid caused by high-temperature treatment, effectively protecting the functionality of the product.

[0030] 3. In the subcritical water medium, the hydrolysis reaction of mushroom sticks is more uniform, the molecular structure of the generated humic acid is more complete, the retention rate of functional groups (such as carboxyl groups, phenolic hydroxyl groups, etc.) is high, and the performance in soil improvement and fertilizer efficiency enhancement is more excellent. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a Fourier infrared spectrum comparison diagram of mushroom stick raw materials and solid products after subcritical acid hydrolysis (Example 4) and alkali hydrolysis (Example 1);

[0033] Figure 2 It is a UV spectrum comparison diagram of liquid products after mushroom sticks are subjected to subcritical acid hydrolysis (Example 4) and alkali hydrolysis (Example 1);

[0034] Figure 3Scanning electron microscope comparison diagrams of the mushroom stick raw material and the solid product after subcritical alkaline hydrolysis (Example 1): (a) mushroom stick raw material; (b) alkaline hydrolysis (Example 1). Specific embodiments

[0035] The following describes the specific embodiments of the present invention in detail with reference to the examples. The following describes the specific embodiments of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through the market or prepared by existing methods.

[0036] The hydrolysis rate of humic acid in the following examples is positively correlated with its extraction rate. The higher the hydrolysis rate, the higher the extraction rate of humic acid.

[0037] I. Embodiments for the extraction of humus

[0038] Example 1

[0039] A method for preparing humus by subcritical alkaline hydrolysis of waste mushroom sticks, comprising the following steps:

[0040] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 50 mesh;

[0041] S2: Take 20.00 g of the mushroom stick powder obtained in step S1 and add it to 200 mL of potassium hydroxide solution with a pH value of 13. Add H2O2 and FeSO4. The dosage of H2O2 is 5% of the volume of the potassium hydroxide solution, and add ethylenediaminetetraacetic acid. The molar ratio of FeSO4, H2O2, and ethylenediaminetetraacetic acid is 1:1:1, and stir evenly to form a mixture;

[0042] S3: Transfer the mixture obtained in step S2 to a high-pressure reaction kettle, react at room temperature for 30 min, and then carry out subcritical hydrolysis reaction at a temperature of 260 °C for 90 min. After the reaction is completed, obtain product 1;

[0043] S4: Filter the product 1 obtained in step S3 for 30 min to separate the solid and liquid, and obtain the humus-containing liquid product A and the solid product B respectively.

[0044] Wash the solid product B obtained in step S4 with clear water and dry it in a vacuum drying oven for 24 h to obtain 3.21 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom sticks is 84%.

[0045] Y S = (1 - M S / M L ) × 100% (1)

[0046] Where M S : represents the mass of the solid product after the reaction, unit: g

[0047] M L : represents the mass of the mushroom stick powder added before the reaction, unit: g.

[0048] Quantitatively detect the liquid reaction product in S4, and the detection results are shown in Table 1.

[0049] Table 1 Component contents of the mushroom stick hydrolysate in Example 1

[0050]

[0051] Example 2

[0052] A method for preparing humus by subcritical alkali hydrolysis of waste mushroom sticks, comprising the following steps:

[0053] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 25 mesh;

[0054] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 160 mL of potassium hydroxide solution with a pH value of 13, add H2O2 and FeSO4, the dosage of H2O2 is 3% of the volume of the potassium hydroxide solution, and add ethylenediaminetetraacetic acid. The molar ratio of FeSO4, H2O2 and ethylenediaminetetraacetic acid is 1:1:1, and stir evenly to form a mixture;

[0055] S3: Transfer the mixture obtained in step S2 to a high-pressure reaction kettle, react at room temperature for 40 min, and then carry out subcritical hydrolysis reaction at a temperature of 240 °C for 120 min to obtain product 1 after the reaction is completed;

[0056] S4: Filter the product 1 obtained in step S3 for 45 min to separate the solid and liquid, and obtain a humus-containing liquid product A and a solid product B respectively.

[0057] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 36 h to obtain 3.36 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom sticks is 83%.

[0058] Table 2 Component contents of the mushroom stick hydrolysate in Example 2

[0059]

[0060] Example 3

[0061] A method for preparing humus from subcritical alkaline hydrolysis of waste mushroom sticks, comprising the following steps:

[0062] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 20 mesh;

[0063] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 240 mL of potassium hydroxide solution with a pH of 13. Add H2O2 and FeSO4. The dosage of H2O2 is 10% of the solution volume, and add ethylenediaminetetraacetic acid. The molar ratio of FeSO4, H2O2 and ethylenediaminetetraacetic acid is 1:1:1, and stir evenly to form a mixture;

[0064] S3: Transfer the mixture obtained in step S2 to a high-pressure reactor, react at room temperature for 60 min, and then carry out subcritical hydrolysis reaction at a temperature of 280 °C for 150 min. After the reaction is completed, product 1 is obtained;

[0065] S4: Filter the product 1 obtained in step S3 for 60 min, separate the solid and liquid to obtain a humus-containing liquid product A and a solid product B respectively.

[0066] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 48 h to obtain 2.87 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom sticks is 86%.

[0067] Table 3 Component contents of the mushroom stick hydrolysis solution in Example 3

[0068]

[0069] Example 4

[0070] A method for preparing humus from subcritical acid hydrolysis of waste mushroom sticks, comprising the following steps:

[0071] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 30 mesh;

[0072] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 200 mL of phosphoric acid solution with a pH of 1. Add H2O2 and FeSO4. The dosage of H2O2 is 2% of the solution volume, and the molar ratio of FeSO4 to H2O2 is 1:1, and stir evenly to form a mixture;

[0073] S3: Transfer the mixture obtained in step S2 to an autoclave, react at room temperature for 40 min, then carry out a subcritical hydrolysis reaction at a temperature of 200 °C for 120 min. After the reaction is completed, product 1 is obtained.

[0074] S4: Filter the product 1 obtained in step S3 for 40 min to separate the solid and liquid, and obtain a humus-containing liquid product A and a solid product B respectively.

[0075] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 4.08 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 80%.

[0076] Table 4 Component contents of the mushroom stick hydrolysis solution in Example 4

[0077]

[0078] Example 5

[0079] A method for preparing humus by subcritical alkali hydrolysis of waste mushroom sticks, comprising the following steps:

[0080] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 40 mesh.

[0081] S2: Take 20.00 g of the mushroom stick powder obtained in step S1 and add it to 300 mL of sodium hydroxide solution with a pH value of 13. Add H2O2 and FeSO4. The dosage of H2O2 is 6% of the solution volume, and add ethylenediaminetetraacetic acid. The molar ratio of FeSO4, H2O2 and ethylenediaminetetraacetic acid is 1:1:1. Stir evenly to form a mixture.

[0082] S3: Transfer the mixture obtained in step S2 to an autoclave, react at room temperature for 30 min, then carry out a subcritical hydrolysis reaction at a temperature of 220 °C for 150 min. After the reaction is completed, product 1 is obtained.

[0083] S4: Filter the product 1 obtained in step S3 for 60 min to separate the solid and liquid, and obtain a humus-containing liquid product A and a solid product B respectively.

[0084] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 48 h to obtain 3.78 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 81%.

[0085] Table 5 Component contents of the mushroom stick hydrolysis solution in Example 5

[0086]

[0087] Example 6

[0088] A method for preparing humus from subcritical alkali-hydrolyzed waste mushroom sticks, comprising the following steps:

[0089] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 50 mesh;

[0090] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 200 mL of ammonia water with a pH value of 13. Add H2O2 and FeSO4. The dosage of H2O2 is 4% of the solution volume, and add ethylenediaminetetraacetic acid. The molar ratio of FeSO4, H2O2 to ethylenediaminetetraacetic acid is 1:1:1, and stir evenly to form a mixture;

[0091] S3: Transfer the mixture obtained in step S2 to a high-pressure reactor, react at room temperature for 40 min, and then carry out subcritical hydrolysis reaction at a temperature of 260 °C for 120 min. After the reaction is completed, product 1 is obtained;

[0092] S4: Filter the product 1 obtained in step S3 for 45 min, separate the solid and liquid, and obtain a humus-containing liquid product A and a solid product B respectively.

[0093] Wash the solid product B obtained in step S4 with clear water and dry it in a vacuum drying oven for 24 h to obtain 3.53 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom sticks is 82%.

[0094] Table 6 Component contents of the mushroom stick hydrolysis solution in Example 6

[0095]

[0096] Example 7

[0097] A method for preparing humus from subcritical acid-hydrolyzed waste mushroom sticks, comprising the following steps:

[0098] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 30 mesh;

[0099] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 200 mL of hydrochloric acid solution with a pH value of 1. Add H2O2 and FeSO4. The dosage of H2O2 is 7% of the solution volume, and the molar ratio of FeSO4 to H2O2 is 1:1, and stir evenly to form a mixture;

[0100] S3: Transfer the mixture obtained in step S2 to an autoclave, react at room temperature for 60 min, and then carry out a subcritical hydrolysis reaction at a temperature of 280 °C for 120 min. After the reaction is completed, product 1 is obtained;

[0101] S4: Filter the product 1 obtained in step S3 for 60 min to separate the solid and liquid, and obtain the humus-containing liquid product A and the solid product B respectively.

[0102] S5: Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 3.96 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 80%.

[0103] Table 7 Component contents of the mushroom stick hydrolysis solution in Example 7

[0104]

[0105] Comparative Example 1

[0106] A method for preparing humus from water-impregnated waste mushroom sticks, comprising the following steps:

[0107] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 50 mesh;

[0108] S2: Take 20.00 g of the mushroom stick powder obtained in step S1 and add it to 200 mL of deionized water, stir evenly to form a mixture, and form a mixture with a solid-liquid ratio of 1 g:10 ml of mushroom stick powder to deionized water;

[0109] S3: Immerse the mixture for 5 days. During the immersion process, stir with a glass rod every 12 h to ensure uniform reaction of each component of the mixture. After the reaction is completed, product 1 is obtained;

[0110] S4: Filter the product 1 obtained in step S3 for 45 min to separate the solid and liquid, and obtain the humus-containing liquid product A and the solid product B respectively.

[0111] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 18.25 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 9%.

[0112] Comparative Example 2

[0113] A method for preparing humus by subcritical hydrolysis of waste mushroom sticks, comprising the following steps:

[0114] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 10 mesh;

[0115] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 200 mL of deionized water, stir evenly to form a mixture, forming a mixture with a solid-liquid ratio of 1 g:10 ml of mushroom stick powder to deionized water;

[0116] S3: Transfer the mixture obtained in step S2 to a high-pressure reactor, carry out subcritical hydrolysis reaction at a temperature of 200 °C, the reaction time is 120 min, and product 1 is obtained after the reaction;

[0117] S4: Filter the product 1 obtained in step S3 for 30 min, separate the solid and liquid, and obtain the humus-containing liquid product A and the solid product B respectively.

[0118] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 16.73 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 16%.

[0119] Comparative Example 3

[0120] A method for preparing humus by alkali impregnation of waste mushroom sticks, comprising the following steps:

[0121] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 20 mesh;

[0122] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 240 mL of potassium hydroxide solution with a pH value of 13, stir evenly to form a mixture, forming a mixture with a solid-liquid ratio of 1 g:12 ml of mushroom stick powder to deionized water;

[0123] S3: Immerse the mixture for 5 days. During the immersion process, stir with a glass rod every 12 h to ensure uniform reaction of each component of the mixture, and product 1 is obtained after the reaction;

[0124] S4: Filter the product 1 obtained in step S3 for 30 min, separate the solid and liquid, and obtain the humus-containing liquid product A and the solid product B respectively.

[0125] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 17.16 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 14%.

[0126] Comparative Example 4

[0127] A method for preparing humus by acid impregnation of waste mushroom sticks, comprising the following steps:

[0128] Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 10 mesh;

[0129] S2: Add 20.00 g of the mushroom stick powder from step S1 to 200 mL of phosphoric acid solution with a pH value of 1, stir evenly to form a mixture, and form a mixture with a solid-liquid ratio of 1 g:10 mL of mushroom stick powder to phosphoric acid solution;

[0130] S3: Immerse the mixture for 5 days. During the immersion process, stir with a glass rod every 12 h to ensure uniform reaction of each component of the mixture, and obtain Product 1 after the reaction is completed;

[0131] S4: Perform suction filtration on Product 1 obtained in step S3 for 40 min to separate solid and liquid, and obtain humus-containing liquid product A and solid product B respectively.

[0132] S5: Wash the solid product B obtained in S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 17.53 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 12%.

[0133] Comparative Example 5

[0134] A method for preparing humus by subcritical alkali hydrolysis of waste mushroom sticks, comprising the following steps:

[0135] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 50 mesh;

[0136] S2: Add 20.00 g of the mushroom stick powder from step S1 to 200 mL of potassium hydroxide solution with a pH value of 13, stir evenly to form a mixture;

[0137] S3: Transfer the mixture obtained in step S2 to a high-pressure reactor, carry out hydrothermal reaction at a temperature of 260 °C for 90 min, and obtain Product 1 after the reaction is completed;

[0138] S4: Perform suction filtration on Product 1 obtained in step S3 for 30 min to separate solid and liquid, and obtain humus-containing liquid product A and solid product B respectively.

[0139] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 9.58 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 52%.

[0140] Comparative Example 6

[0141] A method for preparing humus by subcritical alkali hydrolysis of waste mushroom sticks, comprising the following steps:

[0142] S1: Crush and sieve 20 g of mushroom sticks to obtain mushroom stick powder with a particle size of 50 mesh;

[0143] S2: Take 20.00 g of the mushroom stick powder from step S1 and add it to 200 mL of potassium hydroxide solution with a pH of 13. Add H2O2 and FeSO4. The dosage of H2O2 is 5% of the solution volume, and the molar ratio of FeSO4 to H2O2 is 1:1. Stir evenly to form a mixture.

[0144] S3: Transfer the mixture obtained in step S2 to a high-pressure reactor. After reacting at room temperature for 60 min, carry out a hydrothermal reaction at a temperature of 260 °C for 90 min. After the reaction is completed, product 1 is obtained.

[0145] S4: Continue to corrode product 1 obtained in step S3 for 24 h, then carry out suction filtration for 30 min for solid-liquid separation to obtain a humus-containing liquid product A and a solid product B respectively.

[0146] Wash the solid product B obtained in step S4 with clear water and then dry it in a vacuum drying oven for 24 h to obtain 7.24 g of solid powder. According to the hydrolysis conversion rate calculation formula (1), the hydrolysis rate of the mushroom stick is 64%.

[0147] Table 8 Hydrolysis rates of humus in each example

[0148] Example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Hydrolysis rate % 84 83 86 80 81 82 80

[0149] Table 9 Hydrolysis rates of humus in the comparative examples

[0150] Comparative example Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Hydrolysis rate % 9 16 14 12 52 64

[0151] Figure 1 The infrared spectrum shows that the subcritical acid and alkali hydrolysis treatment of the mushroom stick leads to the degradation of the polysaccharide, protein, and lignin structures, producing smaller molecules or monosaccharides. Figure 2 The ultraviolet spectrum shows that the subcritical acid and alkali hydrolysis reaction of the mushroom stick degrades the polysaccharide and lignin in the raw material, and the aromatic compounds in the hydrolysis solution are converted into small molecule elements. Figure 3 The results of the electron microscope images show that the alkali hydrolysis process has a significant erosion effect on the structure of the mushroom stick, destroys the original biological spore structure of the mushroom stick, and at the same time further degrades the macroscopic and microscale of its lignin matrix, resulting in significant changes in the surface morphology and particle distribution of the material.

[0152] II. Test on the use effect of humus

[0153] The test design is as follows: Set up 24 plots, each plot has an area of 18 m 2, a total of 6 treatments were set, with 4 replicates for each treatment, and the average value was taken. Before transplanting, each plot was applied with 0.6 kg of urea + 0.5 kg of diammonium phosphate + 0.7 kg of potassium sulfate, and the soil was treated with 40 g of 50% phoxim emulsifiable concentrate and 40 g of 40% carbendazim wettable powder respectively to prevent seedling diseases and underground pests. Treatment 1: Dilute the humus liquid of Example 1 by 1000 times and spray it once at the initial flowering stage, full flowering stage, and swelling stage of pepper; Treatment 2: Dilute the humus liquid of Example 2 by 1000 times and spray it once at the initial flowering stage, full flowering stage, and swelling stage of pepper; Treatment 3: Dilute the humus liquid of Example 3 by 1000 times and spray it once at the initial flowering stage, full flowering stage, and swelling stage of pepper; Treatment 4: Dilute the humus liquid of Example 4 by 1000 times and spray it once at the initial flowering stage, full flowering stage, and swelling stage of pepper; Control Treatment 1: Dilute the mixture of 2% urea + 0.4% potassium dihydrogen phosphate by 800 times and spray it once at the initial flowering stage, full flowering stage, and swelling stage of pepper;

[0154] Control Treatment 2: Spray clear water for conventional planting;

[0155] At the mature stage, 5 points were sampled diagonally in each plot, 1 plant was investigated at each point, and 10 samples were randomly taken from each plant to measure the fruit length and fruit width.

[0156] Fruits with a fruit length > 10 cm and a width > 5 cm are large fruits,

[0157] Fruits with a fruit length < 10 cm and a width < 5 cm are small fruits.

[0158] Calculation formula for large fruit rate: Large fruit rate (%) = Number of large fruits / Total number of fruits × 100

[0159] Statistical analysis was performed on the growth, large fruit rate, and disease occurrence of peppers in each treatment group, and the results are shown in Table 10.

[0160] Table 10 Experimental results of the application effect of humus

[0161]

[0162]

[0163] As can be seen from the above table, after spraying in Treatments 1 - 4, the growth, large fruit rate, and disease occurrence of peppers were better than those in Control Treatments 1 and 2 after 7 days. In particular, the large fruit rate was 10.8% - 19.1% higher than that in Control Treatment 1 and 32.1% - 40.4% higher than that in Control Treatment 2.

[0164] The above is only the preferred embodiment of the present invention, and does not constitute any limitation to the present invention in form and substance. It should be emphasized that for those skilled in the art, without departing from the core idea of the present invention, appropriate improvements and supplements can still be made, and these improvements and supplements should also be covered within the protection scope of the present invention. Those who are familiar with the art can make appropriate adjustments, optimizations and expansions according to the above technical content without departing from the basic principles and scope of the present invention, and these adjustments are regarded as equivalent embodiments of the present invention. At the same time, any equivalent adjustments, optimizations or extensions based on the core technology of the present invention all belong to the scope of the technical solutions of the present invention.

Claims

1. A method for preparing humus from subcritically hydrolyzed waste mushroom sticks, characterized in that, It includes the following steps: S1: Crush the mushroom stick to obtain mushroom stick powder; S2: Add the mushroom stick powder obtained in step S1 to an alkaline solution or an acidic solution, add H2O2 and FeSO4, and add ethylenediaminetetraacetic acid under alkaline conditions, and stir evenly to form a mixture; the solid-liquid ratio of the mushroom stick powder to the alkaline solution is 1g:2 - 15ml or the solid-liquid ratio of the mushroom stick powder to the acidic solution is 1g:4 - 15ml; the addition amount of H2O2 is 1 - 10% of the volume of the alkaline solution or the acidic solution; S3: Transfer the mixture obtained in step S2 to a high-pressure reactor, react at room temperature for a period of time and then carry out a subcritical hydrolysis reaction, and obtain product 1 after the reaction is completed; S4: After the product 1 obtained in step S3 is subjected to suction filtration and solid-liquid separation, a humus-containing liquid product is obtained.

2. The method for preparing humus from subcritical hydrolysis of waste mushroom sticks according to claim 1, characterized in that, In the said step S1, the particle size of the mushroom stick powder is 10 mesh - 50 mesh.

3. The method for preparing humus from subcritical hydrolysis of waste mushroom sticks according to claim 1, characterized in that, The said alkaline solution is potassium hydroxide solution, sodium hydroxide solution or ammonia water solution, and the said acidic solution is phosphoric acid solution or hydrochloric acid solution.

4. The method for preparing humus from subcritical hydrolysis of waste mushroom sticks according to claim 3, characterized in that, The pH value of the said alkaline solution is 9 - 13, and the pH value of the said acidic solution is 1 - 5.

5. The method for preparing humus from subcritical hydrolysis of waste mushroom sticks according to claim 1, wherein The solid-liquid ratio of the said mushroom stick powder to the alkaline solution is 1g:8 - 12ml; the solid-liquid ratio of the said mushroom stick powder to the acidic solution is 1g:10 - 12ml.

6. The method for preparing humus from subcritical hydrolysis of waste mushroom sticks according to claim 1, characterized in that, In the said step S2, the volume of H2O2 added is 5 - 10% of the solution volume, and the molar ratio of FeSO4 to H2O2 is 1:

1.

7. The method for preparing humus by subcritical hydrolysis of waste mushroom sticks according to claim 1, characterized in that The molar ratio of the said ethylenediaminetetraacetic acid to FeSO4 is 1:

1.

8. The method for preparing humus from subcritical hydrolysis of waste mushroom sticks according to claim 1, characterized in that, In the said step S3, the reaction time at room temperature is 30 - 60 min, the temperature of the subcritical hydrolysis reaction is 150 - 300 °C, and the time is 30 - 240 min.

9. The method for preparing humus by subcritical hydrolysis of waste mushroom sticks according to claim 8, characterized in that, In the said step S3, the temperature of the subcritical hydrolysis reaction is 200 - 300 °C, and the reaction time is 90 - 150 min.

10. Application of the humus prepared by the method for preparing humus by subcritical hydrolysis of waste mushroom sticks according to any one of claims 1 - 9 in foliar fertilizer.

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