Preparation method of ecological spray-seeding material based on KOH-urea-steam explosion cooperative treatment
By using KOH-urea synergistic treatment and steam explosion technology, the problems of insufficient fiber decomposition and environmental pollution in existing technologies have been solved, realizing the efficient preparation of ecological hydroseeding materials, improving the water absorption and nitrogen supply of the materials, and improving the hydroseeding effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-04
- Publication Date
- 2026-03-17
AI Technical Summary
In existing technologies, the steam explosion treatment of agricultural waste fiber materials suffers from problems such as insufficient fiber decomposition, poor film-forming performance, low nitrogen content, and serious environmental pollution, making it difficult to meet the high-efficiency preparation requirements of ecological spraying materials.
A KOH-urea synergistic treatment method was adopted, in which cotton stalk fibers were pretreated by the synergistic effect of low concentration KOH and urea, followed by steam explosion to form a porous structure, and urea was introduced into the fibers as a slow-release nitrogen source to improve the water retention and ecological applicability of the hydroseeding material.
It significantly improves fiber decomposition efficiency, enhances the water absorption and suspension properties of hydroseeding materials, reduces energy consumption and environmental impact, provides nitrogen needed for plant growth, and improves the uniformity and turf establishment rate of hydroseeding materials.
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Figure CN121673104A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ecological restoration materials and comprehensive utilization of biomass resources, specifically to a method for preparing ecological hydroseeding materials based on the synergistic treatment of KOH-urea-steam explosion. Background Technology
[0002] With the rapid development of ecological restoration and slope greening projects, hydroseeding technology (also known as water-based hydroseeding or hydro-planting) has been widely applied in highway slopes, mine revegetation, reservoir slope protection, and desertification control due to its advantages such as simple construction, uniform coverage, and rapid turf formation. One of the key materials for hydroseeding is the hydroseeding substrate, whose main function is to provide a suitable germination environment for grass seeds, possessing certain water retention, air permeability, binding properties, and slow nutrient release capabilities.
[0003] Currently, commonly used hydroseeding substrates mainly include the following categories: Wood fiber substrates: made from wood pulp, sawdust, or papermaking waste pulp, the fibers are soft and have good suspension properties, but the raw material cost is high, and the production process consumes a large amount of energy and chemicals; Grass fiber or straw substrates: made from crushed straw, rice straw, and other agricultural by-products, after crushing, pulping, or chemical treatment. Although the raw material sources are wide, the fiber structure is dense and has poor hydrophilicity, making it difficult to form a stable hydroseeding system; Recycled pulp materials: made from recycled waste paper pulp or printing paper fibers, but there are environmental risks such as complex composition, heavy metals, or ink residues. In recent years, in order to improve the resource utilization rate of agricultural waste, researchers have tried to use agricultural by-products such as straw, corn cobs, and cotton stalks as raw materials to prepare biodegradable ecological hydroseeding substrates through physical or chemical methods.
[0004] Steam explosion technology, as a green and efficient physical decomposition method, can cause plant fibers to burst structurally through the instantaneous release of high-temperature, high-pressure steam, thereby forming a porous, loose microfiber structure. However, the use of steam explosion alone in existing technologies has the following shortcomings: First, the fertilizer composition of agricultural waste is incomplete, requiring the addition of nitrogen fertilizer and other trace element fertilizers during hydroseeding; second, its film-forming performance is not very good, and the interweaving strength of the fibers is insufficient, making it inadequate to withstand the strong winds in areas with high winds in Northwest China. Existing methods struggle to balance the mechanical strength, water absorption and swelling properties, and ecological adaptability of the fibers, resulting in unsatisfactory coverage performance and plant germination rates of the hydroseeding materials.
[0005] Existing technologies involve pretreating crop straw with alkaline solutions (such as NaOH solution) followed by steam explosion to prepare hydroseeding fiber materials. While this approach improves fiber dispersibility to some extent, it still suffers from the following problems: pretreatment with a single alkaline solution is insufficient for lignin swelling, resulting in relatively coarse and stiff fibers after explosion; the process is energy-intensive, requires large amounts of alkali, and generates significant amounts of highly alkaline wastewater, making treatment difficult and imposing a heavy environmental burden. Furthermore, the addition of NaOH may harm soils that are already saline-alkali. Additionally, the material has a low nitrogen content, lacking the nitrogen nutrients necessary for plant growth; and the water retention and slow-release properties of the products after explosion are limited. Therefore, existing technologies still lack a modification process that can efficiently decompose cotton stalk fibers while improving the material's ecological suitability and water retention performance. Summary of the Invention
[0006] Technical Problem: To address the aforementioned issues, this invention provides a method for preparing ecological hydroseeding materials based on the synergistic treatment of KOH, urea, and steam explosion, achieving the following technical objectives: Improving fiber destructive efficiency: Through the synergistic effect of the alkaline expansion of KOH and the destructive effect of urea on fiber hydrogen bonds, lignin and hemicellulose in cotton stalks are partially dissolved, significantly improving the reaction efficiency and destructive degree of steam explosion. Improving the structure and performance of the hydroseeding material: The fiber material treated by this invention has a loose and porous structure with good water absorption and suspension properties, enabling the formation of a stable slurry during hydroseeding, thus improving the uniformity of hydroseeding and the turf establishment rate. Introducing a nitrogen source and enhancing ecological function: Urea is partially bound or adsorbed into the fibers during pretreatment, providing a slow-release nitrogen source for the material and improving early nutrient supply to vegetation. Reducing energy consumption and environmental burden: This invention uses a low-concentration KOH and urea synergistic effect, which can significantly reduce alkali usage and wastewater pollution, while shortening the steam explosion time and reducing energy consumption, making the process more environmentally friendly. Promoting the high-value utilization of agricultural waste, using crop straw such as cotton stalks as raw materials to replace wood pulp-based sprayed fibers, achieves resource recycling and cost reduction, and has significant economic and ecological benefits.
[0007] Technical solution: To solve the above technical problems, the technical solution adopted in the embodiments of the present invention is as follows:
[0008] 1) Preparation: Crush or chop the raw materials to a particle size of 2-8cm to ensure full penetration of the medicinal solution;
[0009] 2) KOH + Urea Synergistic Impregnation Reaction: In a corrosion-resistant container, first prepare a liquid with a solid-liquid ratio of 1:1, add 1-4% KOH (preferably 3%) of the oven-dried raw material, and then add 3-6 wt% urea (preferably 6 wt%) to the solution. Then add the cut raw material to the mixed solution, stir thoroughly to ensure complete impregnation, and let it stand at room temperature (20℃±5℃) for 4-24 hours. Urea acts as a cellulose hydrogen bond disruptor and nitrogen source in the reaction. This process achieves a synergistic effect of alkaline swelling and urea hydrogen bond breaking, loosening the lignin-cellulose structure and improving the efficiency of the subsequent steam explosion reaction.
[0010] 3) Steam Explosion Expansion: The pre-impregnated material is loaded into a steam explosion device via a belt conveyor. Saturated steam at 0.6–1.2 MPa is rapidly introduced, and the pressure is maintained for 2–8 minutes before being instantaneously released, causing the material to explode and expand. Through this instantaneous pressure release, the internal pressure of the cotton stalk fibers changes drastically, causing the cell walls to rupture and form a porous structure. The exploded material has a rough surface, increased porosity, and a significantly higher specific surface area.
[0011] 4) Fiber decomposition: Use a decomposition machine or disc mill to disperse the cotton stalks after steam explosion into fiber bundles with a moisture content of 30-50%;
[0012] 5) Preparation of ecological hydroseeding substrate mixture: Steam-exploded fibers are mixed with grass seeds, fertilizer, binder, water-retaining agent, and water according to the hydroseeding requirements to prepare hydroseeding slurry. The resulting hydroseeding substrate has good dispersibility, suspension, and water retention capacity, and can evenly cover the slope, providing a good environment for plant germination and establishment.
[0013] The raw materials in step 1) include one or more of the following: cotton stalks, crop straw, bamboo, broadleaf wood, and coniferous wood.
[0014] In step 2), the mass ratio of KOH to urea is 1:3, preferably 1:6; the urea is selected from one or more of urea, uric acid, and ammonium carbonate; the cotton stalk raw material is air-dried to a moisture content of 10-15%.
[0015] In step 5), the grass seeds are selected from one or more of the Poaceae, Leguminosae, and Cyperaceae families, with a particle size of 0.5-2 mm; the fertilizer is selected from one or more of controlled-release fertilizer and water-soluble fertilizer; the binder is selected from one or more of polyethylene glycol, polyvinyl alcohol, and polyacrylic acid; the water-retaining agent is selected from one or more of polyethylene glycol and polyvinylpyrrolidone; and the water is drinking water or purified water.
[0016] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial effects:
[0017] By leveraging the synergistic effect of KOH and urea, the lignin and hemicellulose in cotton stalks were synergistically destroyed, significantly improving the steam explosion decomposition efficiency and overcoming the shortcomings of insufficient fiber separation in existing technologies, resulting in a porous and loosely structured ecological hydroseeding substrate.
[0018] This invention employs a highly efficient decomposition technology at low alkali concentrations, which effectively reduces energy consumption, decreases the amount of chemicals used, and avoids environmental pollution under high temperature and high pressure conditions, thus meeting the requirements of green environmental protection.
[0019] Through the synergistic effect of urea in the fiber, a slow-release nitrogen source is formed, which increases the nitrogen content of the material, promotes the early growth of vegetation, and improves the ecological environment.
[0020] The ecological hydroseeding substrate prepared by this invention has excellent water retention properties, with a water absorption rate increased by 30-50%, which significantly improves the water retention of hydroseeding materials and solves the problem of poor water retention of hydroseeding materials in the prior art.
[0021] The porous structure and surface roughness formed by pretreatment improve the suspension stability and spraying uniformity of the material, overcoming the shortcomings of unstable pulp quality in traditional processes. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the overall process of the preparation method of the present invention.
[0023] Figure 2 Comparison of steam explosion effects. Figure a shows the control group; Figure b shows the control group. Figure 1 Example.
[0024] Figure 3 Comparison of effects before and after hydroseeding. Figure a shows the saline-alkali land before hydroseeding, where no grass grows; Figure b shows the vegetation growing well two months after hydroseeding using the hydroseeding material prepared in one example. Detailed Implementation
[0025] Example 1:
[0026] This invention provides a method for preparing ecological hydroseeding materials based on the synergistic treatment of KOH-urea-steam explosion, the specific steps of which are as follows:
[0027] Step 1, Raw material pretreatment: Chop the cotton stalk raw material into particles of 4-8cm using a shredder, and air dry it to a moisture content of 12%.
[0028] Step 2, KOH + urea synergistic impregnation reaction: In a corrosion-resistant stainless steel container, add 1000mL of deionized water, take 3% (10g) of oven-dried KOH, stir evenly, then add 6% (30g) of urea, continue stirring, and when the temperature of the solution drops to 20℃, add the chopped cotton stalks to the container and soak for 4 hours.
[0029] Step 3, Steam Explosion Expansion: The pre-impregnated material is loaded into a vertical cylindrical steam explosion device (120mm inner diameter, 400mm height) using a belt conveyor with a fine mesh. Saturated steam at 1.2MPa is rapidly introduced, and after holding the pressure for 2 minutes, the pressure is released instantaneously through an automatic valve. During the explosion process, the steam temperature is controlled at around 130℃.
[0030] Step 4, Fiber decomposition: The blasted material is decomposed using a disc mill to disperse the fiber bundles and control the final moisture content to 30%.
[0031] Step 5: Prepare the ecological hydroseeding substrate mixture: Take 100g of steam bursting fiber, mix it with 2g of grass seeds, 1g of controlled-release fertilizer, 2g of polyethylene glycol binder, 1g of polyvinylpyrrolidone water-retaining agent and 100mL of deionized water, stir evenly and make a slurry.
[0032] The resulting hydroseeding substrate exhibits excellent dispersibility and suspension properties. After standing in water for 24 hours, the water loss rate is only 2%, significantly improving the water retention capacity of the hydroseeding material. Testing revealed that the nitrogen content in the substrate is 0.5%, providing an important nitrogen source for plant growth.
[0033] Example 2:
[0034] An eco-friendly hydroseeding material preparation method based on KOH-urea-steam explosion synergistic treatment, the specific steps of which are as follows:
[0035] Step 1, Raw material pretreatment: Chop the corn stalks into particles of 2-5cm using a cutter and dry them in an oven until the moisture content is 14%.
[0036] Step 2, KOH + urea synergistic impregnation reaction: In a stainless steel reactor, add 500mL of deionized water, add 2% (5g) of oven-dried KOH, stir evenly, then add 4% (20g) of uric acid, continue stirring, and when the temperature drops to 18℃, add the chopped raw materials to the reactor and soak for 24 hours.
[0037] Step 3, Steam Explosion Expansion: The pre-impregnated material is loaded into a vertical cylindrical steam explosion device (130mm inner diameter, 350mm height) using a belt conveyor with mesh. Saturated steam at 1.0MPa is rapidly introduced, and after maintaining the pressure for 6 minutes, the pressure is released instantaneously through a solenoid valve. During the explosion process, the steam temperature is controlled at around 140℃.
[0038] Step 4, Fiber decomposition: The blasted material is decomposition machine to disperse the fiber bundles and control the final moisture content to 45%.
[0039] Step 5: Prepare the ecological hydroseeding substrate mixture: Take 150g of steam-exploded fiber, mix it with 3g of leguminous grass seeds, 2g of water-soluble fertilizer, 3g of polyvinyl alcohol binder, 2g of polyethylene glycol water-retaining agent and 150mL of purified water, stir evenly and make into a slurry.
[0040] The resulting hydroseeding substrate exhibits excellent suspension stability, with a water loss rate of only 3% after standing in water for 36 hours, significantly improving the water retention capacity of the hydroseeding material. Testing revealed that the nitrogen content in the substrate was 0.6%, providing an important nitrogen source for plant growth.
[0041] Example 3:
[0042] An eco-friendly hydroseeding material preparation method based on KOH-urea-steam explosion synergistic treatment, the specific steps of which are as follows:
[0043] Step 1, Raw material pretreatment: Chop the peanut shells into 2-3cm particles using a cutter and dry them in an oven until the moisture content is 10%.
[0044] Step 2, KOH + urea synergistic impregnation reaction: In a stainless steel reactor, add 500mL of deionized water, add 4% (5g) of oven-dried KOH, stir evenly, then add 6% (20g) of uric acid, continue stirring, and when the temperature drops to 18℃, add the chopped raw materials to the reactor and soak for 10 hours.
[0045] Step 3, Steam Explosion Expansion: The pre-impregnated material is loaded into a vertical cylindrical steam explosion device (inner diameter 130mm, height 350mm) using a belt conveyor with mesh. Saturated steam at 0.6MPa is rapidly introduced, and after holding the pressure for 8 minutes, the pressure is released instantaneously through a solenoid valve. During the explosion process, the steam temperature is controlled at around 140℃.
[0046] Step 4, Fiber decomposition: The blasted material is decomposition machine to disperse the fiber bundles and control the final moisture content to 50%.
[0047] Step 5: Prepare the ecological hydroseeding substrate mixture: Take 150g of steam-exploded fiber, mix it with 3g of leguminous grass seeds, 2g of water-soluble fertilizer, 3g of polyvinyl alcohol binder, 2g of polyacrylic acid water-retaining agent and 150mL of purified water, stir evenly and make a slurry.
[0048] The resulting hydroseeding substrate exhibits excellent suspension stability, with a water loss rate of only 3% after standing in water for 36 hours, significantly improving the water retention capacity of the hydroseeding material. Testing revealed that the nitrogen content in the substrate was 0.6%, providing an important nitrogen source for plant growth.
[0049] Example 4:
[0050] An eco-friendly hydroseeding material preparation method based on KOH-urea-steam explosion synergistic treatment, the specific steps of which are as follows:
[0051] Step 1, Raw material pretreatment: Chop the rapeseed stalks into particles of 4-6cm using a cutter, and dry them in an oven to a moisture content of 8%.
[0052] Step 2, KOH + urea synergistic impregnation reaction: In a stainless steel reactor, add 500mL of deionized water, add 1% (5g) of oven-dried KOH, stir evenly, then add 5% (20g) of uric acid, continue stirring, and when the temperature drops to 15℃, add the chopped raw materials to the reactor and soak for 8 hours.
[0053] Step 3, Steam Explosion Expansion: The pre-impregnated material is loaded into a vertical cylindrical steam explosion device (inner diameter 130mm, height 350mm) using a belt conveyor with mesh. Saturated steam at 0.8MPa is rapidly introduced, and after maintaining the pressure for 6 minutes, the pressure is released instantaneously through a solenoid valve. During the explosion process, the steam temperature is controlled at around 140℃.
[0054] Step 4, Fiber decomposition: The blasted material is decomposition machine to disperse the fiber bundles and control the final moisture content to 40%.
[0055] Step 5: Prepare the ecological hydroseeding substrate mixture: Take 140g of steam-exploded fiber, mix it with 3g of leguminous grass seeds, 2g of water-soluble fertilizer, 3g of polyvinyl alcohol binder, 2g of polyvinylpyrrolidone water-retaining agent and 150mL of purified water, stir evenly and make a slurry.
[0056] The resulting hydroseeding substrate exhibits excellent suspension stability, with a water loss rate of only 2.3% after standing in water for 36 hours, significantly improving the water retention capacity of the hydroseeding material. Testing revealed that the nitrogen content in the substrate was 0.8%, providing an important nitrogen source for plant growth.
[0057] Control group:
[0058] An eco-friendly hydroseeding material preparation method based on KOH-urea-steam explosion synergistic treatment, the specific steps of which are as follows:
[0059] Step 1, Raw material pretreatment: Chop the rapeseed stalks into particles of 4-6cm using a cutter, and dry them in an oven to a moisture content of 8%.
[0060] Step 2, water immersion reaction: Add 500mL of deionized water to a stainless steel reactor and stir. When the temperature drops to 15℃, add the chopped raw materials to the reactor and soak for 8 hours.
[0061] Step 3, Steam Explosion Expansion: The pre-impregnated material is loaded into a vertical cylindrical steam explosion device (inner diameter 130mm, height 350mm) using a belt conveyor with mesh. Saturated steam at 0.8MPa is rapidly introduced, and after maintaining the pressure for 6 minutes, the pressure is released instantaneously through a solenoid valve. During the explosion process, the steam temperature is controlled at around 140℃.
[0062] Step 4, Fiber decomposition: The blasted material is decomposition machine to disperse the fiber bundles and control the final moisture content to 40%.
[0063] Step 5: Prepare the ecological hydroseeding substrate mixture: Take 140g of steam-exploded fiber, mix it with 3g of leguminous grass seeds, 2g of water-soluble fertilizer, 3g of polyvinyl alcohol binder, 2g of polyethylene glycol water-retaining agent and 150mL of purified water, stir evenly and make a slurry.
[0064] The resulting hydroseeding substrate exhibits excellent suspension stability, with a water loss rate of only 2.3% after standing in water for 36 hours, significantly improving the water retention capacity of the hydroseeding material. Testing revealed that the nitrogen content in the substrate was 0.8%, providing an important nitrogen source for plant growth.
[0065] In addition to potassium hydroxide (KOH), alkaline substances such as sodium hydroxide (NaOH), potassium carbonate (K₂CO₃), and sodium carbonate (Na₂CO₃) can also be used as the main pretreatment agents in this scheme. NaOH has a slightly higher delignification capacity, but the swelling temperature needs to be appropriately lowered to 40–60℃ to avoid fiber carbonization. Weakly alkaline systems such as K₂CO₃ and Na₂CO₃ can achieve similar modification effects under extended treatment times (3–5 hours). This alternative scheme can also achieve alkaline swelling and structural loosening of cotton stalks, providing a good reaction basis for subsequent steam explosion.
[0066] In addition to urea, substances with similar hydrogen bond breaking and nitrogen-releasing effects can also be used in the plan, such as thiourea, bio-amides (such as acetamide), and amino acids (such as glycine). These substances can reduce crystallinity and increase reaction sites by forming hydrogen bond complexes or partially acylation reactions with cellulose molecules. If bio-amino acids are used, the biodegradability and environmental adaptability of the material can also be improved simultaneously.
[0067] The method of this invention is also applicable to other agricultural waste fiber materials, such as rice straw, wheat straw and other crop stalks.
[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the claims and their equivalents.
Claims
1. A method for preparing an ecological spray seeding material based on KOH-urea-steam explosion synergistic treatment, characterized in that, The method comprises the following steps: Step (1), raw material pretreatment: the raw material is crushed or cut into 2-8 cm long segments; Step (2), KOH and urea synergistic impregnation reaction: the pretreated raw material is immersed in a mixed aqueous solution of KOH and urea, and is placed at 20℃±5℃ for 4-24 hours; Step (3), steam explosion puffing: the impregnated material is placed in a steam explosion device, saturated steam with a pressure of 0.6-1.2 MPa is introduced, and after pressure maintaining for 2-8 minutes, instantaneous pressure release is performed for explosion; Step (4), fiber defibration: the steam exploded material is mechanically defibrated to obtain a fiber bundle with a water content of 30%-50%; Step (5), preparation of ecological spray seeding base material: the cotton stalk fiber bundle obtained in step (4) is mixed with grass seeds, fertilizer, adhesive, water retaining agent and water to prepare a spray seeding slurry.
2. The method according to claim 1, wherein the method is characterized by, In step (1), the raw material comprises one or more of cotton stalk, corn stalk, straw, wheat straw, peanut shell and rape stalk.
3. The method according to claim 1, wherein the method is characterized by, In step (2), the solid-liquid mass ratio of the mixed aqueous solution is 1:1; the addition amount of KOH is 1%-4% of the mass of the absolutely dry raw material, and the addition amount of urea is 3%-6% of the total mass of the mixed aqueous solution.
4. The method according to claim 1, wherein the method is characterized by, In step (2), the addition amount of KOH is 3% of the mass of the absolutely dry raw material, and the addition amount of urea is 6% of the total mass of the mixed aqueous solution.
5. The method according to claim 1, wherein the method is characterized by, In step (3), the steam explosion pressure is 0.6-1.2 MPa, and the pressure maintaining time is 2-8 minutes.
6. The method according to claim 1, wherein the method is characterized by, In step (5), the adhesive is selected from one or more of polyethylene glycol, polyvinyl alcohol and polyacrylic acid.
7. The method according to claim 1, wherein the method is characterized by, In step (5), the water retaining agent is selected from one or more of polyethylene glycol and polyvinylpyrrolidone.