Liquid hollow nano-acidic silicon fertilizer and preparation method thereof

Abstract

The application discloses a kind of liquid hollow nano acidic silicon fertilizer and preparation method thereof, belong to agricultural fertilizer technical field, with alkaline silicon as silicon source, by phytase catalysis, acidification directional pore-forming, nutrient element synergistic integration etc. Core process, preparation obtains acidic liquid hollow nano silicon fertilizer;Finished product per liter silicon content ≥169g, rich in phytase, plant source small molecule peptide and silicon, nitrogen, phosphorus, potassium multiple nutrient ingredients, compared with traditional alkaline silicon fertilizer, the product of the application has the advantages of strong compounding compatibility, high crop absorption efficiency, and is not prone to nutrient antagonism in acidic and alkaline soil, suitable for quality improvement and yield increase and stress resistance improvement of various crops, the process of the application is green and environmentally friendly, low in cost, suitable for industrial large-scale production, solves the technical pain points of poor solubility, nutrient antagonism and single function of traditional silicon fertilizer.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology. Specifically, it relates to a liquid hollow nano-acidic silicon fertilizer and its preparation method, which is particularly suitable for grain crops and fruit and vegetable crops such as rice, wheat, tomatoes, and cucumbers, and can be applied to different types of soil, including acidic and alkaline soils. Background Technology

[0002] Silicon is a beneficial element for crop growth and development, enhancing cell wall strength and stress resistance, while also improving soil structure. Traditional silicon fertilizers are mostly solid silicates or alkaline liquid silicon fertilizers, which have many technical defects: First, they have poor solubility and low crop absorption efficiency; second, they have poor compatibility and are prone to precipitation when mixed with acidic fertilizers; third, they are prone to antagonism, easily combining with iron and aluminum ions in acidic soils and calcium and magnesium ions in alkaline soils, leading to the inactivation of silicon fixation; fourth, they are nutrient-limited, only providing silicon and failing to meet the comprehensive needs of crops for nitrogen, phosphorus, and potassium.

[0003] Phytate hydrolysis technology is mainly used in agriculture for dephosphorization and quality improvement of feed, but it has not been widely applied to the preparation of silicon fertilizer. Utilizing the selective etching effect of phytate hydrolysis to prepare hollow nanostructured acidic silicon fertilizer can significantly improve the bioavailability of silicon. At the same time, by integrating enzymes, peptides, and nitrogen, phosphorus, and potassium nutrients, it can solve the problems of nutrient antagonism and single function in traditional silicon fertilizers. Therefore, developing a phytate hydrolysis method to prepare high-silicon-content, multifunctional, and antagonistic liquid hollow nano acidic silicon fertilizer is of great significance for promoting the upgrading of the silicon fertilizer industry. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a liquid hollow nano acidic silicon fertilizer and its preparation method, which has the advantages of solubility, compatibility, non-antagonism and rich nutrients.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing liquid hollow nano-acidic silicon fertilizer by enzymatic hydrolysis of plant acid includes the following steps: Step 1: Pretreatment of alkaline silicon raw materials: Select industrial-grade liquid sodium silicate with a modulus of 3.1~3.4 as alkaline silicon source, add deionized water to prepare an alkaline silicon solution with a mass concentration of 25%~35%, heat to 40℃~50℃, stir until completely dissolved, filter through a 5μm filter membrane to remove impurities, and obtain pretreated silicon solution; Step 2: Perform phytic acid enzymatic hydrolysis activation reaction: Add 5%~8% phytic acid and 0.2%~0.5% phytase with an enzyme activity ≥5000U / g to the pretreated silica liquid, purge with nitrogen to protect enzyme activity, control the temperature at 40℃~50℃ and the stirring speed at 200r / min~300r / min, and carry out the enzymatic hydrolysis reaction for 2h~4h; Step 3: Acidification and Hollow Nanostructure Oriented Molding: Acidification and Hollow Nanostructure Oriented Molding are performed on the enzymatic hydrolysis mixture at a concentration of 0.5 mg / L. 3 / h~1.0m 3 Acidification is achieved by introducing carbon dioxide gas at a rate of / h, while simultaneously adding 1%~2% by mass of plant-derived small molecule peptides with a molecular weight ≤1000Da. The pH of the system is adjusted to 2~4, and the temperature is maintained at 50℃~60℃ for stirring and reaction for 3h~5h. Step 4: Synergistic integration of nitrogen, phosphorus and potassium nutrients: Add urea, potassium dihydrogen phosphate and potassium sulfate to the initial silicon fertilizer solution, and control the mass ratio of nitrogen (N): phosphorus (P2O5): potassium (K2O) in the final product to 2:1:3. Stir and mix for 1 to 2 hours to stabilize the enzymes, peptides and silicon with nitrogen, phosphorus and potassium and avoid nutrient antagonism. Step 5: Purification and Concentration: The reaction solution is sequentially filtered through a plate and frame filter press, and ultrafiltration membranes with a filtration pressure of 0.3 MPa to 0.5 MPa and a molecular weight cutoff of 1000 Da to 3000 Da are used to remove insoluble impurities and free salt ions. Then, the solution is concentrated using a multi-effect falling film evaporator at a vacuum of 0.07 MPa to 0.08 MPa and a temperature of 50°C to 60°C, controlling the liquid density to 1.2 g / cm³. 3 ~1.3g / cm 3 The resulting liquid hollow nano-acidic silicon fertilizer was obtained. Step 6: Testing: The finished product contains ≥169g of silicon per liter, has a pH value of 2~4, and has nano-silicon particle size of 50nm~100nm. It is rich in phytase, small molecule peptides, and silicon, nitrogen, phosphorus, and potassium elements.

[0006] A liquid hollow nano-acidic silicon fertilizer, wherein the silicon fertilizer is a clear and transparent acidic liquid, and the nano-silicon has a hollow porous structure.

[0007] The technical solution of the present invention achieves the following beneficial technical effects: 1. Excellent product performance: The finished product contains ≥169g of silicon per liter, has a hollow nanostructure, a large specific surface area, and improves crop absorption efficiency by more than 30% compared with traditional alkaline silicon fertilizer; it is rich in enzymes, peptides, and nitrogen, phosphorus and potassium elements, achieving "one fertilizer for multiple benefits"; 2. Strong resistance to antagonism: Through peptide complexation, it is not easily fixed by soil ions in acidic or alkaline soils, resulting in stable nutrient utilization. 3. Good compatibility: The acidic system can be directly mixed with most acidic and neutral fertilizers without the need for additional pH adjustment, reducing application costs; 4. Green and economical process: Using inexpensive industrial-grade liquid sodium silicate as raw material and carbon dioxide acidification, it eliminates the need for complex desalination processes and is suitable for large-scale industrial production. Attached Figure Description

[0008] none Detailed Implementation

[0009] Hollow nanostructure formation mechanism: Phytic acid chelates with metal ions in alkaline silicon. Phytase catalyzes the hydrolysis of phytic acid to produce active phosphate groups. These groups undergo coordination reactions with silicon-oxygen tetrahedra to form unstable coordination intermediates. When carbon dioxide is introduced for acidification, the intermediates undergo selective etching. Combined with the steric hindrance effect of plant-derived small molecule peptides, silicon-oxygen tetrahedra are induced to assemble into hollow nanostructures. The hollow structure has a large specific surface area, which can significantly improve the adsorption and absorption efficiency of crop roots.

[0010] Nutrient antagonism mechanism: Through the complexation of peptides with silicon, nitrogen, phosphorus and potassium, a stable nutrient complex is formed, which avoids silicon from combining with iron and aluminum ions in acidic soil and with calcium and magnesium ions in alkaline soil; at the same time, the acidic system and soil pH form a buffer, reducing the fixation effect of soil ions on silicon fertilizer.

[0011] Compound compatibility mechanism: The finished product is an acidic liquid that does not contain free strong alkaline ions. It can be directly compounded with acidic and neutral fertilizers without producing precipitation, thus solving the problem of limited compounding of traditional alkaline silicon fertilizers.

[0012] Example 1: Liquid hollow nano acidic silicon fertilizer specifically for grain crops.

[0013] 1. Raw material pretreatment: Select industrial-grade liquid sodium silicate with a modulus of 3.2, add deionized water to prepare a 30% mass concentration alkaline silicon solution, heat to 45℃ and stir to dissolve, filter through a 5μm filter membrane to obtain pretreated silicon solution.

[0014] 2. Enzymatic activation: Add 6% phytic acid and 0.3% Aspergillus niger phytase (enzyme activity 5000 U / g) to the pretreated silica liquid, purge with nitrogen for protection, stir at 45℃ and 250 r / min for 3 h to obtain the enzymatic hydrolysate.

[0015] 3. Acidification and hollow molding: with a diameter of 0.8m 3 Carbon dioxide was introduced into the enzymatic hydrolysis mixture at a rate of / h, 1.5% soybean peptide was added, the pH was adjusted to 3, and the mixture was stirred at 55℃ for 4h to obtain the initial silicon fertilizer solution.

[0016] 4. Nutritional integration: Add urea, potassium dihydrogen phosphate, and potassium sulfate, and control the N:P2O5:K2O mass ratio to be 2:1:3. Stir the reaction for 1.5 hours.

[0017] 5. Purification and Concentration: After plate and frame filtration and separation by a 2000 Da ultrafiltration membrane, the product is concentrated to a density of 1.25 g / cm³ under a vacuum of 0.075 MPa and at 55 °C. 3 The finished product is obtained.

[0018] 6. Testing: The finished product contains 172g of silicon per liter, has a pH value of 3, and has a nano-silicon particle size of 75nm; when diluted 600 times and sprayed on rice, it increases lodging resistance by 40% and grain plumpness by 15%.

[0019] Example 2: Liquid Hollow Nano Acidic Silicon Fertilizer for Fruit and Vegetable Crops 1. Raw material pretreatment: Select industrial-grade liquid sodium silicate with a modulus of 3.1, add deionized water to prepare an alkaline silicon solution with a mass concentration of 25%, heat to 40℃ and stir to dissolve, filter through a 5μm filter membrane to obtain pretreated silicon solution.

[0020] 2. Enzymatic activation: Add 5% phytic acid and 0.2% Aspergillus niger phytase (enzyme activity 5000 U / g) to the pretreated silica liquid, purge with nitrogen for protection, stir at 40℃ and 200 r / min for 2 h to obtain the enzymatic hydrolysate.

[0021] 3. Acidification and hollow molding: with a diameter of 0.5m 3 Carbon dioxide was introduced into the enzymatic hydrolysis mixture at a rate of / h, 1% corn peptide was added, the pH was adjusted to 2.5, and the mixture was stirred at 50℃ for 3h to obtain the initial silicon fertilizer solution.

[0022] 4. Nutritional integration: Add urea, potassium dihydrogen phosphate, and potassium sulfate, and control the N:P2O5:K2O mass ratio to be 2:1:3. Stir the reaction for 1 hour.

[0023] 5. Purification and Concentration: After plate and frame filtration and separation by a 1000 Da ultrafiltration membrane, the product is concentrated to a density of 1.2 g / cm³ under a vacuum of 0.07 MPa and at 50 °C. 3 The finished product is obtained.

[0024] 6. Testing: The finished product contains 169g of silicon per liter, has a pH value of 2.5, and has nano-silicon particle size of 50nm; when diluted 1200 times for drip irrigation of tomatoes, root vitality is increased by 35% and fruit sugar content is increased by 8%.

[0025] The liquid hollow nano acidic silicon fertilizer prepared by this invention can be widely used in various crops such as grains, fruits and vegetables, and cotton. It can play a good role in different soil types such as acidic red soil and alkaline saline-alkali soil, and has the functions of improving quality and yield as well as soil improvement.

[0026] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for preparing liquid hollow nano-acidic silicon fertilizer by phytic acid enzymatic hydrolysis, characterized in that, Includes the following steps: Step 1: Pretreatment of alkaline silicon raw materials: Select industrial-grade liquid sodium silicate with a modulus of 3.1~3.4 as alkaline silicon source, add deionized water to prepare an alkaline silicon solution with a mass concentration of 25%~35%, heat to 40℃~50℃, stir until completely dissolved, filter through a 5μm filter membrane to remove impurities, and obtain pretreated silicon solution; Step 2: Perform phytic acid enzymatic hydrolysis activation reaction: Add 5%~8% phytic acid and 0.2%~0.5% phytase with an enzyme activity ≥5000U / g to the pretreated silica liquid, purge with nitrogen to protect enzyme activity, control the temperature at 40℃~50℃ and the stirring speed at 200r / min~300r / min, and carry out the enzymatic hydrolysis reaction for 2h~4h; Step 3: Acidification and Hollow Nanostructure Oriented Molding: Acidification and Hollow Nanostructure Oriented Molding are performed on the enzymatic hydrolysis mixture at a concentration of 0.5 mg / L. 3 / h~1.0m 3 Acidification is achieved by introducing carbon dioxide gas at a rate of / h, while simultaneously adding 1%~2% by mass of plant-derived small molecule peptides with a molecular weight ≤1000Da. The pH of the system is adjusted to 2~4, and the temperature is maintained at 50℃~60℃ for stirring and reaction for 3h~5h. Step 4: Synergistic integration of nitrogen, phosphorus and potassium nutrients: Add urea, potassium dihydrogen phosphate and potassium sulfate to the initial silicon fertilizer solution, and control the mass ratio of nitrogen (N): phosphorus (P2O5): potassium (K2O) in the final product to 2:1:

3. Stir and mix for 1 to 2 hours to stabilize the enzymes, peptides and silicon with nitrogen, phosphorus and potassium and avoid nutrient antagonism. Step 5: Purification and Concentration: The reaction solution is sequentially filtered through a plate and frame filter press, and ultrafiltration membranes with a filtration pressure of 0.3 MPa to 0.5 MPa and a molecular weight cutoff of 1000 Da to 3000 Da are used to remove insoluble impurities and free salt ions. Then, the solution is concentrated using a multi-effect falling film evaporator at a vacuum of 0.07 MPa to 0.08 MPa and a temperature of 50°C to 60°C, controlling the liquid density to 1.2 g / cm³. 3 ~1.3g / cm 3 The resulting liquid hollow nano-acidic silicon fertilizer was obtained. Step 6: Testing: The finished product contains ≥169g of silicon per liter, has a pH value of 2~4, and has nano-silicon particle size of 50nm~100nm. It is rich in phytase, small molecule peptides, and silicon, nitrogen, phosphorus, and potassium elements.

2. The method for preparing liquid hollow nano-acidic silicon fertilizer by phytic acid enzymatic hydrolysis according to claim 1, characterized in that, The second step involves a chelation reaction between phytic acid and metal ions in alkaline silicon. Phytase catalyzes the hydrolysis of phytic acid, generating active phosphate groups that coordinate with silicon-oxygen tetrahedra, providing etching sites for hollow structure formation, thus obtaining an enzymatic hydrolysis mixture.

3. The method for preparing liquid hollow nano-acidic silicon fertilizer by phytic acid enzymatic hydrolysis according to claim 2, characterized in that, The third step involves inducing the assembly of silicon-oxygen tetrahedra into hollow nanostructures through the selective etching effect of enzymatic hydrolysis products and the steric hindrance effect of peptides, thereby obtaining the initial silicon fertilizer solution.

4. The method for preparing liquid hollow nano-acidic silicon fertilizer by phytic acid enzymatic hydrolysis according to claim 3, characterized in that, The phytase mentioned in the second step is a microbial phytase produced by Aspergillus niger, with an acid and alkali tolerance range of pH 2.0~6.

0.

5. The method for preparing liquid hollow nano-acidic silicon fertilizer by phytic acid enzymatic hydrolysis according to claim 3, characterized in that, The plant-derived small molecule peptides mentioned in the third step are soybean peptides or corn peptides, which are used to improve the biocompatibility of silicon fertilizer and enhance the stability of hollow nano-silicon structures.

6. The method for preparing liquid hollow nano-acidic silicon fertilizer by phytic acid enzymatic hydrolysis according to claim 3, characterized in that, The ultrafiltration membrane mentioned in step 5 is an acid-resistant organic ceramic composite membrane that can withstand acidic environments with pH 1~5 and has a service life of ≥1000h.

7. A liquid hollow nano-acidic silicon fertilizer, characterized in that, The liquid hollow nano-acidic silicon fertilizer is prepared using the phytic acid enzymatic hydrolysis method according to any one of claims 1-6, wherein the silicon fertilizer is a clear and transparent acidic liquid, and the nano-silicon has a hollow porous structure.

8. The liquid hollow nano-acidic silicon fertilizer according to claim 7, characterized in that, The silicon fertilizer can be used in two ways: first, by foliar spraying after dilution of 500-800 times, to enhance the toughness of crop cell walls and improve resistance to lodging and pests; second, by drip irrigation or fertigation after dilution of 1000-1500 times, to improve soil aggregate structure and promote the synergistic absorption of silicon, nitrogen, phosphorus and potassium by roots.