Degradable water-retaining agent, vegetation substrate doped with degradable water-retaining agent and preparation method of vegetation substrate

Abstract

The invention provides a degradable water-retaining agent, a vegetation substrate doped with the degradable water-retaining agent and a preparation method of the vegetation substrate, and the preparation method comprises the following steps: preparing the degradable water-retaining agent by utilizing a monomer, a cross-linking agent, an initiator, water and NaOH; and preparing the vegetation substrate by using an adhesive, a pH regulator, a reinforcing agent, a soil regulator, a fertilizer, the degradable water-retaining agent, soil, plant fibers and water. According to the invention, a certain amount of acidic ardealite is added on the basis of a conventional cement planting substrate to reduce alkalinity, and meanwhile, the water-retaining agent which can be degraded under the alkaline action is used, so that the water-retaining agent can continuously release water for a long time, and favorable conditions are provided for plant growth.

Description

Technical Field

[0001] This invention relates to the field of ecological restoration technology, specifically to a biodegradable water-retaining agent, a plant substrate with the biodegradable water-retaining agent added, and a preparation method thereof. Technical Background Construction projects often result in exposed slopes, which not only damage existing vegetation but may also lead to geological disasters. The industry commonly uses hydroseeding to restore and protect slopes. Hydroseeding technology uses water as a carrier to prepare a planting substrate by mixing plant seeds, soil, adhesives, water-retaining agents, and nutrients. This substrate is then mixed, stirred, and sprayed onto the desired planting area using a hydroseeding machine, thus forming an ecological vegetation greening technology.

[0002] The key technology to be solved in topsoil spraying is resistance to rainwater erosion, and the adhesive plays a crucial role in this. Commonly used adhesives are formed by polyacrylamide (a method for ecological restoration of mine slopes, CN117772769A), cement (a method for shallow reinforcement and ecological restoration of coal gangue slopes, CN113412696A), nanomaterials (a spray-mixed vegetation substrate with added nanomaterials and its preparation method, CN119790938A), etc., either alone or in combination.

[0003] Cement-based vegetation substrates have high alkalinity, which is not conducive to plant growth and requires dealkalization treatment.

[0004] Cement hydration and water evaporation can cause water loss from the plant substrate, thus requiring water-retaining agents to replenish moisture for plant growth. However, conventional water-retaining agents are prone to failing to retain water in the early stages and failing to release water in the later stages. Summary of the Invention

[0005] This invention addresses the shortcomings of existing plant substrates by providing a biodegradable water-retaining agent, a plant substrate with the biodegradable water-retaining agent, and a method for preparing the same. This solves the problem that conventional water-retaining agents often fail to retain water in the early stages and fail to release water in the later stages.

[0006] According to one aspect of the present invention, a method for preparing a plant substrate doped with a biodegradable water-retaining agent is provided. The method comprises: preparing a biodegradable water-retaining agent using monomers, a crosslinking agent, an initiator, water, and NaOH; and preparing a plant substrate using an adhesive, a pH adjuster, a reinforcing agent, a soil conditioner, fertilizer, the biodegradable water-retaining agent, soil, plant fiber, and water. The monomers, by weight, comprise sulfonic acid monomers and ester monomers, with the sulfonic acid monomers used in an amount of 10-22 parts and the ester monomers used in an amount of 8-20 parts. The initiator is one of potassium persulfate and ammonium persulfate, used in an amount of 0.03-0.06 parts. The crosslinking agent is polyethylene glycol diisocyanate. The following components are used: acrylate (0.1-0.3 parts); water (65-70 parts); NaOH (0-4.25 parts); biodegradable water-retaining agent (0.04-0.1 parts); low-alkali sulfoaluminate cement (6-8 parts); phosphogypsum (pH 2.1-3); hydroxyl acrylic emulsion (45%-50% solids, 2-4% hydroxyl content, 0.3-1 parts); soil conditioner (0.2-0.5 parts); fertilizer (0.1-0.2 parts); and plant fiber (5-8 parts).

[0007] Optionally, the sulfonate monomer may be one or both of 2-acrylamido-2-methylpropanesulfonic acid and sodium styrenesulfonate.

[0008] Optionally, the ester monomer may be one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0009] Optionally, the steps for preparing the biodegradable water-retaining agent may include: dissolving sulfonic acid monomers in water at room temperature, neutralizing the monomers to pH neutral using NaOH, adding ester monomers, initiators, and crosslinking agents dissolved in water, purging with nitrogen to remove oxygen, heating to 50-55℃ for 2-3 hours, continuing to heat to 60-65℃ and maintaining the temperature, drying the prepared hydrogel in an oven at 100-105℃ for 18-24 hours, pulverizing and sieving it into 100-150 mesh powder to obtain the water-degradable water-retaining agent.

[0010] Optionally, the pH value of the low-alkali sulfoaluminate cement can be 10.8 to 11.1.

[0011] Optionally, the step of preparing the plant substrate may include: mixing the adhesive, pH adjuster, reinforcing agent, soil conditioner, fertilizer, and biodegradable water-retaining agent evenly, adding 48-52 parts of water, 100 parts of soil, and hydroxyl acrylic emulsion, stirring evenly, adding plant fiber, and preparing a plant substrate with biodegradable water-retaining agent.

[0012] Optionally, the soil conditioner may be humic acid, the fertilizer may be one or more of potassium sulfate, potassium dihydrogen phosphate and potassium chloride, and the plant fiber may be rice straw fiber with a length of 0.5 to 1 cm.

[0013] Another aspect of the present invention provides a plant substrate doped with a biodegradable water-retaining agent, the plant substrate being prepared by the preparation method described above.

[0014] Another aspect of the present invention provides a biodegradable water-retaining agent, characterized in that the raw materials of the biodegradable water-retaining agent include monomers, crosslinking agents, initiators, water, and NaOH, wherein, by weight, the monomers include sulfonic acid monomers and ester monomers, with the amount of sulfonic acid monomers being 10-22 parts and the amount of ester monomers being 8-20 parts; the initiator is one of potassium persulfate and ammonium persulfate, with an amount of 0.03-0.06 parts; the crosslinking agent is polyethylene glycol diacrylate, with an amount of 0.1-0.3 parts; the amount of water is 65-70 parts; and the amount of NaOH is 0-4.25 parts.

[0015] Compared with existing technologies, the beneficial effects of this invention are as follows: 1) Low-alkali sulfoaluminate cement is used as a binder, while phosphogypsum and humic acid are used to adjust the pH of the plant substrate. Hydroxy acrylic emulsion is added to reduce the adverse effects of phosphogypsum and humic acid on strength. This improves the germination rate of plants while ensuring the strength and rain erosion resistance of the plant substrate. 2) A biodegradable water-retaining agent is used, which can better regulate water release and allow plants to survive longer in drought conditions. Attached Figure Description

[0016] Figure 1 A flowchart illustrating a method for preparing a plant-based substrate doped with a biodegradable water-retaining agent according to an embodiment of the present invention is shown.

[0017] Figure 2 This shows the growth of ryegrass in Example 2 and Comparative Example 2. Among them, Figure 2 Figure a shows the growth of ryegrass in Comparative Example 2 without the addition of phosphogypsum and humic acid. Figure 2 b represents the growth of ryegrass mixed with phosphogypsum and humic acid in Example 2.

[0018] Figure 3 The diagrams showing the growth of ryegrass in Comparative Example 1 and Example 1 are compared. Figure 3 a is a schematic diagram showing the growth of ryegrass when a conventional water-retaining agent was added to Example 1. Figure 3 b is a schematic diagram showing the growth of ryegrass when a biodegradable water-retaining agent is added in Example 1.

[0019] Figure 4This is a diagram showing the results of a rain erosion resistance test on the vegetation substrate of Example 2. Detailed Implementation

[0020] The present invention will be further described below with reference to embodiments.

[0021] After extensive observation and reflection, the applicant discovered that the water release patterns of cross-linked sodium polyacrylate or polyacrylamide water-retaining agents in related technologies do not match the plant growth cycle. The root cause of the problem lies in the fact that, with cement hydration, a large number of metal ions (such as Ca) are generated in the pores of the substrate. 2+ Fe 3+ In related technologies, water-retaining agents (containing carboxylic acid groups) undergo a dual dehydration effect under the action of high-valence metal ions: on the one hand, the ions chelate with the carboxylic acid, reducing the ionic strength of the main chain and shielding the charge, causing the polymer network to shrink and dehydrate; on the other hand, the ions cause an imbalance in internal and external osmotic pressure, driving water outward. Under the synergistic effect of chelation shrinkage and osmotic pressure imbalance, the water-retaining agent rapidly loses water. However, limited by its stable cross-linked structure, dehydration stops once osmotic pressure equilibrium is reached, and it cannot continue to release water during subsequent droughts. As a result, when the substrate has sufficient moisture, the water-retaining agent rapidly releases free water, which easily evaporates, leading to water waste; while when there is a real water shortage, the water release is insufficient, which is detrimental to plant growth. In other words, conventional water-retaining agents "cannot stabilize water" in the early stages and "cannot release water" in the later stages.

[0022] An ideal water-retaining agent should be able to "hold water" in the early stages and "release water" effectively in the later stages. In the early stages, the agent should retain as much free water as possible to reduce evaporation, while in the later stages, it should slowly and fully release water for plant growth. When the vegetation substrate is mixed with water, the biodegradable water-retaining agent rapidly absorbs and expands. During the mixing and spraying stage, the substrate is in good plasticity. Within hours after spraying, the ester groups of the hydroxyethyl acrylate or hydroxypropyl acrylate segments in the water-retaining agent will continuously hydrolyze in an alkaline environment to form carboxylic acid groups. This increases the charge density of the main chain, leading to further absorption of free water, reducing evaporation, and simultaneously reducing soil plasticity, enhancing its adhesion to slopes, and also improving its resistance to rain erosion in the early stages of spraying. As the cement hydration process progresses, the alkalinity increases, and the ester groups of the crosslinking agent will slowly hydrolyze, causing the degree of crosslinking of the water-retaining agent to continuously decrease, and water will be continuously released until the water-retaining agent is completely decrosslinked, and the absorbed water is completely released.

[0023] To achieve the above objectives, the present invention provides the following technical solution: Figure 1 A flowchart illustrating a method for preparing a plant-based substrate doped with a biodegradable water-retaining agent according to an embodiment of the present invention is shown.

[0024] like Figure 1As shown in the embodiments, the present invention provides a method for preparing a plant substrate with added biodegradable water-retaining agent, comprising the following: S1: Preparation of biodegradable water-retaining agent, the synthesis principle is shown in the figure:

[0025] In the formula, R1 is the side chain of the sulfonate monomer, R2 is -H or -CH3, R3 is -(CH2)2- or -(CH2)3-, and the molecular weight of PEGDA is 200 to 600.

[0026] The biodegradable water-retaining agent can be prepared from monomers, crosslinking agents, initiators, water and NaOH, and the monomers include sulfonate monomers and ester monomers.

[0027] The sulfonate monomer can be one or both of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and sodium styrene sulfonate. The amount of sulfonate monomer used can be 10 to 22 parts by weight. It should be noted that, unless otherwise specified, the parts used for each component or substance in this invention are all by weight, and will not be repeated below.

[0028] The water content can be 65-70 parts. Too little water can cause the drying process to fail, while too much will affect the subsequent drying efficiency.

[0029] The initiator can be either potassium persulfate or ammonium persulfate, and the amount used can be 0.03 to 0.06 parts.

[0030] The ester monomer can be one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate. The amount of ester monomer used can be 8 to 20 parts.

[0031] The crosslinking agent can be polyethylene glycol diacrylate (PEGDA) with a molecular weight of 200-600. The amount of PEGDA used can be 0.1-0.3 parts.

[0032] The amount of NaOH used can be 0 to 4.25 parts.

[0033] In the embodiments, the preparation steps of the biodegradable water-retaining agent are as follows: Sulfonic acid monomers are dissolved in water at room temperature; the acidity of the monomers is neutralized using NaOH; ester monomers, initiators, and crosslinking agents are added and dissolved in water; nitrogen is purged for oxygen removal for 15–20 minutes; the temperature is raised to 50–55°C and reacted for 2–3 hours; the temperature is further raised to 60–65°C and maintained for 4–5 hours; the prepared hydrogel is placed in an oven at 100–105°C and dried for 18–24 hours; the dried gel is then pulverized and sieved into 100–150 mesh powder, which is the water-retaining agent. Excessive drying temperature or prolonged drying time may lead to ester hydrolysis, affecting the performance of the water-retaining agent.

[0034] S2: Preparation of plant substrate: The plant substrate is composed of adhesive, pH adjuster, enhancer, soil conditioner, fertilizer, biodegradable water-retaining agent, soil, plant fiber and water.

[0035] The binder can be low-alkali sulfoaluminate cement with a pH value of 10.8 to 11.1 and a dosage of 6 to 8 parts.

[0036] The pH adjuster can be phosphogypsum, and the pH can be 2.1 to 3.

[0037] The reinforcing agent can be a hydroxy acrylic emulsion, with a solid content of 45% to 50% and a hydroxyl content of 2% to 4% by mass percentage; the dosage can be 0.3 to 1 part by weight.

[0038] Soil conditioner can be humic acid, a black powder solid produced in Xinjiang Uygur Autonomous Region, and the dosage can be 0.2 to 0.5 parts.

[0039] The fertilizer can be potassium sulfate, potassium dihydrogen phosphate, or potassium chloride, with potassium sulfate being preferred. The dosage can be 0.1 to 0.2 parts.

[0040] The plant fiber can be rice straw fiber, with a length of 0.5 to 1 cm, and the amount used can be 5 to 8 parts.

[0041] The water-retaining agent can be the biodegradable water-retaining agent prepared by S1, and the dosage can be 0.04 to 0.1 parts. If the dosage of the water-retaining agent is too high or too low, it will result in low water retention and less free water released later. If the dosage is too high, it will result in excessive water consumption of the plant substrate and reduce the strength of the substrate.

[0042] The preparation steps for plant substrate can be as follows: Mix the adhesive, pH adjuster, reinforcing agent, soil conditioner, fertilizer, and biodegradable water-retaining agent evenly according to the proportion, then add 48-52 parts of water, 100 parts of soil, and hydroxyl acrylic emulsion, stir evenly, and then add plant fiber.

[0043] Phosphogypsum and humic acid undergo a neutralization reaction in an alkaline environment, lowering the pH of the vegetation substrate. However, both have an adverse effect on the strength of the vegetation substrate. Therefore, a hydroxyl acrylic resin reinforcing agent is introduced to increase the interaction force between cement and soil, improve the strength of the vegetation substrate, and thus enhance its resistance to rainwater erosion.

[0044] In another embodiment, a plant substrate doped with a biodegradable water-retaining agent is also provided, the plant substrate being prepared by the preparation method described above.

[0045] In another embodiment, a biodegradable water-retaining agent is also provided. The raw materials of the biodegradable water-retaining agent include monomers, crosslinking agents, initiators, water, and NaOH. By weight, the monomers include sulfonic acid monomers and ester monomers, with sulfonic acid monomers used in an amount of 10-22 parts and ester monomers used in an amount of 8-20 parts; the initiator is one of potassium persulfate and ammonium persulfate, used in an amount of 0.03-0.06 parts; the crosslinking agent is polyethylene glycol diacrylate, used in an amount of 0.1-0.3 parts; the water content is 65-70 parts; and the NaOH content is 0-4.25 parts.

[0046] The preparation process of the above-mentioned biodegradable water-retaining agent can be the same as or similar to the preparation of the relevant biodegradable water-retaining agent in step S1 of the plant substrate as described above, and will not be repeated here.

[0047] According to embodiments of the present invention, low-alkali sulfoaluminate cement is used as a binder, while phosphogypsum and humic acid are used to adjust the pH of the vegetation substrate. Hydroxy acrylic emulsion is added to reduce the adverse effects of phosphogypsum and humic acid on strength. This ensures the strength and rain erosion resistance of the vegetation substrate while improving the germination rate of the plants. The use of a biodegradable water-retaining agent better regulates water release, allowing the plants to survive longer in drought conditions.

[0048] The method for preparing a plant substrate doped with a biodegradable water-retaining agent according to this disclosure will be described in detail below with specific examples.

[0049] Example 1 S1: Preparation of biodegradable water-retaining agent: Dissolve 10 parts of AMPS in 70 parts of water, add 1.93 parts of NaOH to neutralize pH, add 20 parts of hydroxyethyl acrylate, 0.03 parts of potassium persulfate, and 0.1 parts of crosslinking agent PEGDA (molecular weight 200). After stirring evenly, purge with nitrogen for 15 min to remove oxygen, raise the temperature to 50℃ and react for 2 h, continue to raise the temperature to 60℃ and keep warm for 4 h, place the prepared hydrogel in an oven at 105℃ and dry for 24 h, pulverize and sieve into 100-150 mesh powder, which is the water-retaining agent.

[0050] S2: Preparation of plant substrate: Mix 8 parts of sulfoaluminate cement, 4 parts of phosphogypsum, 0.5 parts of humic acid, and 0.1 parts of potassium sulfate evenly, add 48 parts of water, 100 parts of soil and 0.5 parts of hydroxyl acrylic emulsion, stir evenly, and then add 5 parts of plant fiber to obtain a plant substrate with added biodegradable water-retaining agent.

[0051] Sow ryegrass seeds 2 cm above the surface of the growing substrate and cover with the growing substrate. The sowing density is 0.5 kg / m². 2 .

[0052] Example 2 S1: Preparation of biodegradable water-retaining agent: Dissolve 15 parts of AMPS in 70 parts of water, add 2.9 parts of NaOH to neutralize pH, add 15 parts of hydroxypropyl methacrylate, 0.06 parts of potassium persulfate, and 0.3 parts of crosslinking agent PEGDA (molecular weight 600). After stirring evenly, purge with nitrogen for 15 min to remove oxygen, raise the temperature to 50℃ and react for 2 h, continue to raise the temperature to 60℃ and keep warm for 4 h, place the prepared hydrogel in an oven at 105℃ and dry for 24 h, pulverize and sieve into 100-150 mesh powder, which is the water-retaining agent.

[0053] S2: Preparation of plant substrate: Mix 8 parts of sulfoaluminate cement, 2 parts of phosphogypsum, 0.5 parts of humic acid, and 0.1 parts of potassium sulfate evenly, add 50 parts of water, 100 parts of soil and 0.3 parts of hydroxyl acrylic emulsion, stir evenly, and then add 5 parts of plant fiber to obtain a plant substrate with added biodegradable water-retaining agent.

[0054] Sow ryegrass seeds 2 cm above the surface of the growing substrate and cover with the growing substrate. The sowing density is 0.5 kg / m². 2 .

[0055] Example 3 S1: Preparation of biodegradable water-retaining agent: Dissolve 22 parts of sodium styrene sulfonate in 70 parts of water, add 0 parts of NaOH, add 8 parts of hydroxypropyl acrylate, 0.05 parts of potassium persulfate, and 0.6 parts of crosslinking agent PEGDA (molecular weight 200), stir evenly, purge with nitrogen for 15 min, heat to 50℃ and react for 2 h, continue to heat to 60℃ and keep warm for 4 h, place the prepared hydrogel in an oven at 105℃ and dry for 24 h, pulverize and sieve into 100-150 mesh powder, which is the water-retaining agent.

[0056] S2: Preparation of plant substrate: Mix 8 parts of sulfoaluminate cement, 8 parts of phosphogypsum, 0.2 parts of humic acid and 0.2 parts of potassium sulfate evenly, add 52 parts of water, 100 parts of soil and 1 part of hydroxyl acrylic emulsion, stir evenly and then add 5 parts of plant fiber to obtain a plant substrate with added biodegradable water-retaining agent.

[0057] Sow ryegrass seeds 2 cm above the surface of the growing substrate and cover with the growing substrate. The sowing density is 0.5 kg / m². 2 .

[0058] Example 4 S1: Preparation of biodegradable water-retaining agent: Dissolve 15 parts of sodium styrene sulfonate in 65 parts of water, add 0 parts of NaOH, add 15 parts of hydroxyethyl methacrylate, 0.05 parts of ammonium persulfate, and 0.2 parts of crosslinking agent PEGDA (molecular weight 400), stir evenly, purge with nitrogen for 20 min, heat to 55℃ and react for 2 h, continue to heat to 65℃ and keep warm for 5 h, place the prepared hydrogel in an oven at 105℃ and dry for 24 h, pulverize and sieve into 100-150 mesh powder, which is the water-retaining agent.

[0059] S2: Preparation of plant substrate: Mix 6 parts of sulfoaluminate cement, 2 parts of phosphogypsum, 0.2 parts of humic acid, and 0.1 parts of potassium sulfate evenly, add 52 parts of water, 100 parts of soil and 1 part of hydroxyl acrylic emulsion, stir evenly, and then add 8 parts of plant fiber to obtain a plant substrate with added biodegradable water-retaining agent.

[0060] Sow ryegrass seeds 2 cm above the surface of the growing substrate and cover with the growing substrate. The sowing density is 0.5 kg / m². 2 .

[0061] Comparative Example 1 (Conventional water-retaining agent): S1: Use conventional sodium polyacrylate water-retaining agent.

[0062] S2: Preparation of plant substrate: Same as Example 1.

[0063] Sow ryegrass seeds 2 cm above the surface of the growing substrate and cover with the growing substrate. The sowing density is 0.5 kg / m². 2 .

[0064] Comparative Example 2 (without phosphogypsum, humic acid, or hydroxyl acrylic emulsion): S1: Same as Example 2.

[0065] S2: Preparation of plant substrate: Mix 8 parts of sulfoaluminate cement, 50 parts of water, and 100 parts of soil evenly, then add 5 parts of plant fiber to obtain the plant substrate.

[0066] Sow ryegrass seeds 2 cm above the surface of the growing substrate and cover with the growing substrate. The sowing density is 0.5 kg / m². 2 .

[0067] Comparative Example 3 S1: Same as Example 1.

[0068] S2: Preparation of plant substrate: Hydroxy acrylic emulsion is not used, otherwise the same as in Example 1.

[0069] Sow ryegrass seeds 2 cm above the surface of the growing substrate and cover with the growing substrate. The sowing density is 0.5 kg / m². 2 .

[0070] Performance testing The compressive strength of the plant-based substrate without plant fiber was tested at 7 days and 28 days. The mold size was 40*40*160mm, and the loading speed for the compressive strength test was 2400N / s.

[0071] The pH test of the vegetation substrate was conducted in accordance with "LY-T 1239-1999 Determination of pH value of forest soil".

[0072] Rain erosion resistance test process: The vegetation substrate was molded into a 40cm*50cm test block with a thickness of 3cm, sealed and cured for 7 days, and placed on a 30° slope to simulate rain erosion of the vegetation substrate. After being eroded by 200mm / h of rain for 1 hour, the soil that was washed away was collected, dried and weighed.

[0073] Table 1. Performance of Examples and Comparative Examples

[0074] The comparison between Example 2 and Comparative Example 2 (without phosphogypsum, humic acid, and hydroxyacrylic acid emulsion) shows that the addition of humic acid and phosphogypsum significantly reduced the strength of the plant substrate, decreasing from 0.73 MPa to 0.4 MPa after 28 days. However, the pH value decreased significantly from 10.78 to 9.56, and the germination rate also increased to some extent, from 60% to 73%.

[0075] Figure 2 The growth of ryegrass was compared between Comparative Example 2 and Example 2. Figure 2 The results show that the addition of humic acid and phosphogypsum resulted in denser growth of ryegrass, indicating that humic acid and phosphogypsum can improve the germination rate and growth of ryegrass.

[0076] The performance comparison between Example 1 and Comparative Example 3 shows that hydroxy acrylic emulsion can increase the 28-day compressive strength from 0.22 MPa to 0.29 MPa. At the same time, since hydroxy acrylic resin also contains ester groups, it can react with OH-, which can reduce the pH value to a certain extent, from 9.72 to 9.56.

[0077] The ryegrass was observed to grow in an indoor environment with 60% humidity. To avoid excessive water evaporation due to prolonged placement, it was placed in a standard maintenance room with 95% humidity for 8 hours every 4 days. The ryegrass replenished some of the evaporated water by absorbing moisture.

[0078] Figure 3 The growth of ryegrass was compared between Comparative Example 1 (conventional water-retaining agent) and Example 1 (biodegradable water-retaining agent). Figure 3 As can be seen, after one month using conventional water-retaining agents, the ryegrass showed signs of drying out (e.g. Figure 3 As shown in a), and in the plant substrate of biodegradable water-retaining agent (such as... Figure 3 (As shown in b), the ryegrass is growing well because the biodegradable water-retaining agent continuously releases water to support plant growth.

[0079] Example 2 was tested for its resistance to rain erosion using a simulation device with a simulated rainfall of 200 mm / h and a slope of 30°. Figure 4 As can be seen, after 1 hour of continuous rinsing, the surface of the vegetation substrate did not exhibit any grooves or pits, and the soil loss was 0.07 kg / m³. 2 / h indicates that the plant substrate prepared in the embodiments of the present invention has excellent resistance to rainwater erosion.

[0080] According to the present invention, a plant substrate doped with a degradable water-retaining agent and its preparation method thereof, a certain amount of acidic phosphogypsum is added to a conventional cement plant substrate to reduce alkalinity, and a water-retaining agent that can be degraded under alkaline conditions is used at the same time, so that the water-retaining agent continuously releases water over a long period of time, providing favorable conditions for plant growth.

[0081] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing a plant-based substrate doped with a biodegradable water-retaining agent, characterized in that, The preparation method includes: A biodegradable water-retaining agent was prepared using monomers, crosslinking agents, initiators, water, and NaOH; and A plant-based substrate is prepared using an adhesive, pH adjuster, reinforcing agent, soil conditioner, fertilizer, the aforementioned biodegradable water-retaining agent, soil, plant fiber, and water; wherein, The monomer comprises sulfonic acid monomers and ester monomers in parts by weight, wherein the amount of sulfonic acid monomers is 10-22 parts and the amount of ester monomers is 8-20 parts; The initiator is one of potassium persulfate and ammonium persulfate, and the dosage is 0.03 to 0.06 parts; The crosslinking agent is polyethylene glycol diacrylate, and the amount used is 0.1 to 0.3 parts; The water consumption accounts for 65-70 parts; The amount of NaOH used is 0 to 4.25 parts; In the step of preparing the plant substrate, the amount of the biodegradable water-retaining agent is 0.04 to 0.1 parts; The adhesive is low-alkali sulfoaluminate cement, and the dosage is 6-8 parts. The pH adjuster is phosphogypsum, with a pH value of 2.1–3; The reinforcing agent is a hydroxyl acrylic emulsion with a solid content of 45% to 50%, a hydroxyl content of 2% to 4%, and a dosage of 0.3 to 1 part. The dosage of the soil conditioner is 0.2 to 0.5 parts; The amount of fertilizer used is 0.1 to 0.2 parts; The amount of plant fiber used is 5 to 8 parts.

2. The method for preparing the plant substrate doped with a biodegradable water-retaining agent according to claim 1, characterized in that, The sulfonate monomer is one or both of 2-acrylamide-2-methylpropanesulfonic acid and sodium styrene sulfonate.

3. The method for preparing the plant substrate doped with a biodegradable water-retaining agent according to claim 1, characterized in that, The ester monomers are one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

4. The method for preparing the plant substrate doped with a biodegradable water-retaining agent according to claim 1, characterized in that, The steps for preparing the biodegradable water-retaining agent include: At room temperature, sulfonic acid monomers are dissolved in water, and the monomers are neutralized to pH neutral using NaOH. Esters, initiators, and crosslinking agents are added and dissolved in water. Nitrogen gas is passed through to remove oxygen, and the temperature is raised to 50-55℃ for 2-3 hours. The temperature is then raised to 60-65℃ and maintained. The prepared hydrogel is placed in an oven at 100-105℃ and dried for 18-24 hours. The hydrogel is then pulverized and sieved into 100-150 mesh powder to obtain a water-degradable water-retaining agent.

5. The method for preparing the plant substrate doped with a biodegradable water-retaining agent according to claim 1, characterized in that, The pH value of the low-alkali sulfoaluminate cement is 10.8 to 11.

1.

6. The method for preparing the plant substrate doped with a biodegradable water-retaining agent according to claim 1, characterized in that, The steps for preparing the plant substrate include: mixing the adhesive, pH adjuster, reinforcing agent, soil conditioner, fertilizer, and biodegradable water-retaining agent evenly, adding 48-52 parts of water, 100 parts of soil, and hydroxyl acrylic emulsion, stirring evenly, adding plant fiber, and preparing a plant substrate with biodegradable water-retaining agent.

7. The method for preparing the plant substrate doped with a biodegradable water-retaining agent according to claim 1, characterized in that, The soil conditioner is humic acid, and the fertilizer is at least one of potassium sulfate, potassium dihydrogen phosphate, and potassium chloride; the plant fiber is rice straw fiber with a length of 0.5 to 1 cm.

8. A plant-based substrate doped with a biodegradable water-retaining agent, characterized in that, The plant substrate is prepared by the preparation method according to any one of claims 1 to 7.

9. A biodegradable water-retaining agent, characterized as follows: The raw materials for the water-retaining and water-reducing agent include monomers, crosslinking agents, initiators, water, and NaOH, wherein, The monomer comprises sulfonic acid monomers and ester monomers in parts by weight, wherein the amount of sulfonic acid monomers is 10-22 parts and the amount of ester monomers is 8-20 parts; The initiator is one of potassium persulfate and ammonium persulfate, and the dosage is 0.03 to 0.06 parts; The crosslinking agent is polyethylene glycol diacrylate, and the amount used is 0.1 to 0.3 parts; The water consumption accounts for 65-70 parts; The amount of NaOH used is 0 to 4.25 parts.

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