Slow-release and controlled-release nanopesticide, preparation method and application

Abstract

The present invention provides a slow-release and controlled-release nanopesticide, a preparation method, and an application thereof. The slow-release and controlled-release nanopesticide is an aqueous suspension using water as a solvent, the aqueous suspension comprising micro-nano hydroxyapatite, a copper pesticide, and chitosan. The copper pesticide is adsorbed on the micro-nano hydroxyapatite, and the chitosan is at least partially coated on the surface of the copper pesticide. The mass ratio of the micro-nano hydroxyapatite, the copper pesticide, and the chitosan is (50-100):(50-100):1. The retention capacity of the nanopesticide in the soil is improved, the slow-release time is prolonged, and the risk of loss due to leaching with rainwater is reduced, thereby improving the utilization rate of the pesticide in a green and environmentally friendly manner. In addition, it can also release phosphorus, which promotes crop growth, for a long period of time, reducing the application and waste of phosphate fertilizers, and presents great opportunities and prospects as a multifunctional nanocarrier in the process of crop cultivation.

Description

Technical Field

[0001] The present invention relates to the field of nanopesticides, and in particular to slow-release and controlled-release nanopesticides, preparation methods and applications. Background Art

[0002] The use of pesticides is crucial to agricultural production. However, with the long-term application of pesticides and the development of agriculture, most pesticides currently on the market suffer from low efficacy, poor stability of active ingredients, and easy loss with rainwater. This leads to the use of large quantities of pesticides to achieve the desired control effects, causing environmental pollution and endangering food security. Therefore, improving pesticide utilization, enhancing pesticide efficacy, and reducing active ingredient loss are of great significance to agricultural production and public safety.

[0003] Due to the importance of nitrogen and phosphorus to plant growth, phosphate fertilizer is crucial for crop production. However, traditional phosphate fertilizer usage in farmland is high and inefficient. Excessive phosphate fertilizer use in farmland leads to a gradual accumulation of phosphorus in the environment. Controlling the phosphorus content of agricultural fertilizers can alleviate phosphorus stress in the environment to a certain extent, effectively reducing phosphorus inputs and contributing to environmental phosphorus control. The key to controlling phosphorus in farmland lies in improving its utilization efficiency and reducing phosphorus loss. Therefore, the development of nano-phosphate fertilizers, with reduced usage and rational planning, offers new avenues for phosphorus control in farmland.

[0004] Listed as one of the "Top Ten Emerging Chemical Technologies That Will Change the World," nanopesticides utilize nanopesticide preparation technology to stabilize the active ingredients in a nanoscale dispersion within the formulation and / or dispersion system. The stability and controlled release of nanopesticides can increase the utilization of active ingredients, thereby reducing pesticide usage. This helps mitigate the burden of agricultural chemicals on farmland and the environmental risks and impacts of pesticide residues.

[0005] Slow-release and controlled-release nanopesticides mainly rely on the adsorption and desorption of active ingredients on nanocarriers. The commonly used carriers currently studied are mainly silica, metal skeletons, graphene oxide, clay mineral materials, etc., but most of them have the defects of high cost and only slow-release and controlled-release effects, which are single effects. Summary of the Invention

[0006] The main purpose of the present invention is to provide a slow-release and controlled-release nanopesticide, a preparation method and an application thereof, so as to solve the technical problems of the existing slow-release and controlled-release nanopesticides, such as high cost and relatively simple effect.

[0007] To achieve the above objectives, the present invention provides a sustained-release, controlled-release nanopesticide. The sustained-release, controlled-release nanopesticide is an aqueous suspension containing micro-nano hydroxyapatite, a copper pesticide, and chitosan. The copper pesticide is adsorbed on the micro-nano hydroxyapatite, and the chitosan at least partially coats the surface of the copper pesticide.

[0008] The mass ratio of the micro-nano hydroxyapatite, the copper pesticide and the chitosan is (50-100):(50-100):1. Every 100 ml of the aqueous suspension contains 0.5-1 g of micro-nano hydroxyapatite.

[0009] According to an embodiment of the present application, the particle size of the micro-nano hydroxyapatite ranges from 20 nanometers to 80 micrometers.

[0010] According to an embodiment of the present application, the mass ratio of the micro-nano hydroxyapatite, the copper preparation pesticide and the chitosan is (50-100):(50-100):1.

[0011] According to an embodiment of the present application, the copper preparation pesticide is at least one of Bordeaux mixture, copper hydroxide pesticide preparation, and thiophanate-methyl preparation.

[0012] The present application also provides a method for preparing the above-mentioned slow-release and controlled-release nanopesticide, comprising the following steps:

[0013] Dissolve chitosan in acetic acid solution and stir at 30-40° C. to obtain a chitosan solution.

[0014] The copper preparation pesticide is added dropwise into the micro-nano hydroxyapatite suspension, and mixed to obtain a mixed liquid.

[0015] The chitosan solution is added dropwise to the mixed liquid and reacted for 1 hour to obtain the slow-release and controlled-release nanopesticide.

[0016] The mass ratio of the micro-nano hydroxyapatite, the copper pesticide and the chitosan is (50-100):(50-100):1. Every 100 ml of the sustained-release and controlled-release nanopesticide contains 0.5-1 g of micro-nano hydroxyapatite.

[0017] According to an embodiment of the present application, the concentration of the acetic acid solution is 2 mol / L.

[0018] According to an embodiment of the present application, the method for preparing the micro-nano hydroxyapatite suspension includes:

[0019] 0.5-1g of micro-nano hydroxyapatite is mixed with 75mL of water, and stirred for 30min-1h at room temperature and a stirring speed of 300-500r / min to prepare a micro-nano hydroxyapatite suspension.

[0020] According to an embodiment of the present application, the step of adding the copper pesticide to the micro-nano hydroxyapatite suspension and mixing the mixture comprises:

[0021] The copper pesticide is added dropwise to the micro-nano hydroxyapatite suspension at a rate of 2 mL / min. After all the addition is completed, magnetic stirring is performed for 30 min to 1 h.

[0022] According to an embodiment of the present application, in the step of adding the chitosan solution dropwise to the mixed liquid and reacting for 1 hour, the dropping speed is 1 mL / min and the reaction time is 1 hour.

[0023] Application of the above-mentioned slow-release and controlled-release nanopesticide or the slow-release and controlled-release nanopesticide obtained by the above-mentioned preparation method in agricultural production.

[0024] In the aforementioned slow-release and controlled-release nanopesticide, micro-nano hydroxyapatite and a copper pesticide are integrated. The copper pesticide is fixed to the micro-nano hydroxyapatite surface through adsorption and chelation by various groups, thus forming a nanopesticide. A chitosan-based slow-release coating then utilizes hydrogen bonding and electrostatic interactions between the chitosan and the pesticide to achieve slow release and dissolution of the copper. This improves the nanopesticide's retention in the soil, prolongs its slow release time, and reduces the risk of leaching with rainwater, thereby increasing pesticide utilization in a green and environmentally friendly manner. Furthermore, the nanopesticide can release phosphorus, which promotes crop growth, over a long period of time, reducing the application and waste of phosphate fertilizers. This nanopesticide presents significant opportunities and prospects as a multifunctional nanocarrier in crop cultivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0026] Figure 1 Transmission electron micrographs of the micro-nano hydroxyapatite and the sustained-release and controlled-release nanopesticide in Example 1, wherein (A) is a TEM image of 60-nm rod-shaped hydroxyapatite, and (B) is a TEM image of 60-nHAP-nCu in Example 1;

[0027] Figure 2This is a comparison of the copper release curves over time in suspensions of nano-copper nanopesticides (nHAP-nCu) of different sizes in Example 5;

[0028] Figure 3 This is a comparison of the copper release curves over time in suspensions of inorganic copper nanopesticides (nHAP-ICu) of different sizes in Example 6;

[0029] Figure 4 This is a comparison of the copper release curves over time in suspensions of thiophanate-copper nanopesticide (nHAP-OCu) of different sizes in Example 7;

[0030] Figure 5 This is a schematic diagram of a cross-section of a soil column suitable for evaluating the copper sustained-release performance of a novel copper nanopesticide during the leaching process proposed by the present invention in Example 8;

[0031] Figure 6 This is a bar graph of the copper content in the upper layer of the soil column after the leaching experiment in Example 8;

[0032] Figure 7 This is a bar graph of the copper content in the lower layer of the soil column after the leaching experiment in Example 8.

[0033] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0036] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of these features.

[0037] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] The present invention provides a sustained-release and controlled-release nanopesticide. The sustained-release and controlled-release nanopesticide is an aqueous suspension using water as a solvent. The aqueous suspension includes micro-nano hydroxyapatite, a copper pesticide, and chitosan. The copper pesticide is adsorbed on the micro-nano hydroxyapatite, and the chitosan at least partially coats the surface of the copper pesticide.

[0039] The mass ratio of the micro-nano hydroxyapatite, the copper pesticide and the chitosan is (50-100):(50-100):(1). Each milliliter of the aqueous suspension contains 0.005 g of micro-nano hydroxyapatite.

[0040] The main raw materials of the sustained-release and controlled-release nanopesticide of the present application include micro-nano hydroxyapatite, copper preparation pesticide and chitosan.

[0041] Micro-nano hydroxyapatite acts as a pesticide carrier, adsorbing the copper pesticide onto the micro-nano hydroxyapatite through adsorption and chelation within the micro-nano hydroxyapatite suspension. The chitosan-formed sustained-release coating fully or partially encapsulates the copper pesticide through hydrogen bonding and electrostatic interactions between the chitosan and the copper pesticide, achieving sustained release and dissolution of the copper.

[0042] Micro-nano hydroxyapatite is used as raw material, which has low cost, large storage capacity, and is environmentally friendly. It can release phosphorus for a long time, which promotes the growth of crops, reduce the application and waste of phosphorus fertilizers, and shows great opportunities and prospects as a multifunctional nanocarrier in the process of crop cultivation.

[0043] Furthermore, applicable micro-nano hydroxyapatite has a wide range of particle sizes. In some embodiments, the particle size of the micro-nano hydroxyapatite ranges from 20 nanometers to 80 micrometers. For example, the micro-nano hydroxyapatite includes particle shapes and needle-shaped hydroxyapatite with sizes of 20 nanometers, 60 nanometers, and 80 micrometers.

[0044] The migration behaviors of sustained-release and controlled-release nanopesticides prepared from micro-nano hydroxyapatite with different particle sizes in soil are significantly different.

[0045] Copper pesticides are a broad-spectrum antimicrobial pesticide primarily used to combat bacterial and fungal plant diseases. Compared to other antimicrobial pesticides, copper pesticides not only damage bacterial cells with copper ions but also enhance their antimicrobial properties by promoting plant growth and strengthening their disease resistance. Furthermore, compared to other organic antimicrobial pesticides, copper pesticides are less harmful to humans and are classified as low-toxic pesticides.

[0046] Therefore, the slow-release controlled-release nanopesticide of the present application, because of selecting copper preparation pesticide as pesticide, in addition to having the long-acting, slow-release effect that general slow-release pesticide has, due to the slow release of copper ions, the concentration of copper ions is at a more reasonable level, so that plant growth can be better promoted and the ability of plants to resist diseases is enhanced. Exemplarily, compared with directly applying copper preparation pesticides of equal concentrations, the slow-release controlled-release nanopesticide of the present application reduces the free copper concentration directly in contact with the plant when applied in the rhizosphere of the plant, thereby helping plant growth. That is, the slow-release controlled-release nanopesticide of the present application has both alleviated the plant toxicity caused by excessive copper stress, and its long-term performance in the soil is conducive to killing a variety of pathogenic bacteria.

[0047] In some embodiments, the copper pesticide is at least one of Bordeaux mixture, copper hydroxide pesticide preparation, and thiophanate-methyl preparation.

[0048] Bordeaux mixture, copper hydroxide pesticide preparations, and thiophanate-methyl preparations are copper-based antimicrobial pesticides and are commercially available. These include Bordeaux mixture developed by US-based Sannong Co., Ltd., Cosmetol (the active ingredient of which is copper hydroxide) developed by DuPont, and thiophanate-methyl preparations developed by Zhejiang Longwan Chemical Co., Ltd. In actual use, they are primarily used to combat bacterial plant diseases. The sustained-release preparation process employed in this patent enhances their long-term effectiveness and helps plant growth.

[0049] This application uses chitosan as the coating material. Chitosan is not easily soluble in water, making it more stable when used in soil environments. It has also been reported to have antibacterial properties, making it more advantageous for the application of antibacterial nanopesticides. In some related technologies, chitosan solutions are used as the coating material.

[0050] Chitosan, a natural high-molecular-weight polysaccharide extracted from the shells of crustaceans or the cell walls of fungi, is insoluble in water but soluble in weak acids. Compared to sodium alginate, chitosan is more stable in soil environments. Chitosan has also been reported to have certain antibacterial properties, making it advantageous in the preparation of antimicrobial pesticides.

[0051] This application creates a green and friendly dual-effect nanopesticide by constructing micro-nano hydroxyapatite as a pesticide carrier, loading different types of copper-based pesticides. By effectively combining different types of copper-based pesticides with the micro-nano hydroxyapatite carrier and chitosan medium, a new type of green and efficient nanopesticide with the ability to slowly release the nutrients Cu and P is prepared. This controlled-release nanopesticide is capable of simultaneously releasing both copper and phosphorus.

[0052] In the aforementioned slow-release and controlled-release nanopesticide, micro-nano hydroxyapatite and a copper pesticide are integrated. The copper pesticide is fixed to the micro-nano hydroxyapatite surface through adsorption and chelation by various groups, thus forming a nanopesticide. A chitosan-based slow-release coating then utilizes hydrogen bonding and electrostatic interactions between the chitosan and the pesticide to achieve slow release and dissolution of the copper. This improves the nanopesticide's retention in the soil, prolongs its slow release time, and reduces the risk of leaching with rainwater, thereby increasing pesticide utilization in a green and environmentally friendly manner. Furthermore, the nanopesticide can release phosphorus, which promotes crop growth, over a long period of time, reducing the application and waste of phosphate fertilizers. This nanopesticide presents significant opportunities and prospects as a multifunctional nanocarrier in crop cultivation.

[0053] In some embodiments, the mass ratio of the micro-nano hydroxyapatite, the copper pesticide, and the chitosan is 100:100:1.

[0054] Compared with the prior art, the advantages of the present invention are:

[0055] 1. In the above-mentioned slow-release and controlled-release nanopesticides, the copper-prepared pesticide is loaded on micro-nano hydroxyapatite, which has a large loading capacity and a good slow-release effect of copper ions, thereby reducing the damage to crops caused by excessive copper concentration.

[0056] 2. The technical solution provided by the present invention uses hydroxyapatite as raw material, which is low-cost, has a large storage capacity, and is environmentally friendly. It can release phosphorus that promotes crop growth for a long time, reduce the application and waste of phosphorus fertilizers, and show great opportunities and prospects as a multifunctional nanocarrier in the process of crop cultivation.

[0057] 3. In the above-mentioned slow-release and controlled-release nanopesticides, micro-nano hydroxyapatite is loaded with copper-prepared nanopesticides. When the pesticide and the micro-nano hydroxyapatite are fused with each other, the pesticide fixes the copper-prepared pesticide under the adsorption and chelation of various groups on the surface of the micro-nano hydroxyapatite, thereby forming a nanopesticide. Then, a slow-release coating film is formed by chitosan, and the hydrogen bonds, electrostatic interactions and other forces between chitosan and the pesticide are utilized to achieve slow release and dissolution of copper. The retention capacity of the nanopesticide in the soil is improved, the slow release time is extended, and the risk of loss by leaching with rainwater is reduced, thereby improving the utilization rate of the pesticide in a green and environmentally friendly way.

[0058] The present application also provides a method for preparing the above-mentioned slow-release and controlled-release nanopesticide, comprising the following steps:

[0059] S100: dissolving chitosan in acetic acid solution and stirring at 30-40° C. to obtain a chitosan solution.

[0060] The concentration of the chitosan solution is 1 g / L. For example, 0.05 g of chitosan powder is weighed and dissolved in 50 mL of acetic acid solution, and magnetically stirred at 30-40° C. for 2 h to obtain a chitosan solution. In some embodiments, the concentration of the acetic acid solution is 2 mol / L.

[0061] S200: adding the copper pesticide dropwise to the micro-nano hydroxyapatite suspension, mixing the mixture to obtain a mixed liquid.

[0062] The copper-prepared pesticide is at least one of Bordeaux mixture, copper hydroxide pesticide preparation, and thiophanate-methyl preparation.

[0063] In some embodiments, the copper hydroxide pesticide formulation is Copper Hydroxide.

[0064] In some embodiments, the thiophanate-methyl formulation is an 80% thiophanate-methyl formulation.

[0065] In some embodiments, the step of adding the copper pesticide to the micro-nano hydroxyapatite suspension and mixing the mixture comprises:

[0066] The copper preparation pesticide is added dropwise to the micro-nano hydroxyapatite suspension at a rate of 20 to 40 drops / min. After all the addition is completed, magnetic stirring is performed for 30 minutes to 1 hour.

[0067] For example, at room temperature, under magnetic stirring at 300-500 r / min, 20 mL of the 3-copper pesticide solution in step 2) is slowly added dropwise to the micro-nano hydroxyapatite solution. After all the addition is completed, magnetic stirring is performed for 30 min to 1 h.

[0068] In some embodiments, the method for preparing the micro-nano hydroxyapatite suspension comprises:

[0069] 0.5-1g of micro-nano hydroxyapatite is mixed with 75mL of water, and stirred at room temperature and a stirring speed of 300-500r / min for 30min-1h to prepare a micro-nano hydroxyapatite suspension.

[0070] S300: Add the chitosan solution dropwise to the mixed liquid and react for 1 hour to obtain the sustained-release controlled-release nanopesticide. The mass ratio of the micro-nano hydroxyapatite, the copper pesticide, and the chitosan is (50-100):(50-100):(50-100). Each 100 ml of the sustained-release controlled-release nanopesticide contains 0.05 g of micro-nano hydroxyapatite.

[0071] In some embodiments, in the step of adding the chitosan solution dropwise to the mixed liquid and reacting for 1 hour, the dropping speed is 20 to 40 drops / min and the reaction time is 1 hour.

[0072] The above-mentioned method for preparing the sustained-release and controlled-release nanopesticide has a simple process, a large loading capacity, and mild conditions. The prepared sustained-release and controlled-release nanopesticide has the same beneficial effects as the above-mentioned sustained-release and controlled-release nanopesticide, and will not be described in detail.

[0073] Application of the above-mentioned slow-release and controlled-release nanopesticide or the slow-release and controlled-release nanopesticide obtained by the above-mentioned preparation method in agricultural production.

[0074] The above-mentioned slow-release and controlled-release nanopesticides can be applied in agricultural production scenarios. This application evaluates the slow-release and regularity of copper and phosphorus during the leaching process of this new nanopesticide in soil application scenarios. Based on the limitations of copper-based pesticides in market applications, this application confirms that the slow-release process of copper in this slow-release and controlled-release nanopesticide is beneficial for reducing plant toxicity caused by excessive copper stress, and its long-term effectiveness in the soil is beneficial for killing a variety of pathogenic bacteria, and its functions are significantly different.

[0075] Example 1:

[0076] The present embodiment provides a method for preparing a nano-hydroxyapatite-loaded copper hydroxide nanopesticide (nHAP-nCu): 0.52 g, 0.51 g, and 0.54 g of micro-nano hydroxyapatite with a size of 20 nm, 60 nm, and 80 μm were placed in a 100 mL conical flask, 75 mL of deionized water was added and mixed, and then magnetically stirred at 400 r / min at room temperature for 2 h to prepare a hydroxyapatite suspension; 0.53 g, 0.51 g, and 0.54 g of the pesticide formulation of Cossaccharide 3,000 were weighed and dissolved in 20 mL of water, and magnetically stirred at 400 r / min at room temperature for 2 h. L was added dropwise to the micro-nano hydroxyapatite suspension to obtain a micro-nano hydroxyapatite-loaded copper hydroxide nanopesticide suspension; then 0.005 g of chitosan powder was weighed and dissolved in 5 mL of acetic acid solution, and magnetically stirred at 35°C for 2 hours to obtain a chitosan solution; under magnetic stirring at 400 r / min, it was added dropwise to the micro-nano hydroxyapatite-loaded copper hydroxide nanopesticide suspension at a speed of 1 mL per minute. After the dropwise addition was completed, stirring was continued at 400 r / min for 1 hour to obtain a new nanopesticide with a total volume of 100 mL that can long-term slow-release copper and phosphorus nutrients (i.e., slow-release nanopesticide nHAP-nCu).

[0077] 60 nanometer rod-shaped hydroxyapatite and the sustained-release nanopesticide prepared from 60 nanometer hydroxyapatite were analyzed by transmission electron microscopy. The results are as follows: Figure 1 As shown, Figure 1 : (A) is a TEM image of 60-nanometer rod-shaped hydroxyapatite, and (B) is a TEM image of the sustained-release nanopesticide 60-nHAP-nCu in Example 1.

[0078] Example 2:

[0079] This embodiment provides a method for preparing a micro-nano hydroxyapatite-loaded copper sulfate nanopesticide (nHAP-ICu): 0.52 g, 0.51 g, and 0.54 g of hydroxyapatite with a size of 20 nm, 60 nm, and 80 μm were placed in a 100 mL conical flask, 75 mL of deionized water was added and mixed, and then magnetically stirred at 400 rpm for 2 h at room temperature to prepare a micro-nano hydroxyapatite suspension; 0.53 g, 0.51 g, and 0.54 g of Bordeaux mixture pesticide preparation were respectively weighed and dissolved in 20 mL of water, and magnetically stirred at 400 rpm at room temperature for 2 h. L was added dropwise to the micro-nano hydroxyapatite suspension to obtain a micro-nano hydroxyapatite-loaded copper sulfate nanopesticide suspension; then 0.005 g of chitosan powder was weighed and dissolved in 5 mL of acetic acid solution, and magnetically stirred at 35°C for 2 hours to obtain a chitosan solution; under magnetic stirring at 400 r / min, it was added dropwise to the micro-nano hydroxyapatite-loaded copper sulfate nanopesticide suspension at a speed of 1 mL per minute. After the addition was completed, stirring was continued at 400 r / min for 1 hour to obtain a new nanopesticide with a total volume of 100 mL that can long-term slow-release copper and phosphorus nutrients (i.e., slow-release nanopesticide nHAP-ICu).

[0080] Example 3:

[0081] This embodiment provides a method for preparing a nano-hydroxyapatite-loaded thiophanate-copper nanopesticide (nHAP-OCu): 0.52 g, 0.51 g, and 0.54 g of hydroxyapatite with a size of 20 nm, 60 nm, and 80 μm were placed in a 100 mL conical flask, 75 mL of deionized water was added and mixed, and then magnetically stirred at 400 rpm for 2 h at room temperature to prepare a micro-nano hydroxyapatite suspension; 2.1 mL, 2.0 mL, and 2.2 mL of the thiophanate-copper pesticide preparation were respectively measured and dissolved in 20 mL of water, and magnetically stirred at 400 rpm at room temperature for 2 h. L was added dropwise to the micro-nano hydroxyapatite suspension to obtain a micro-nano hydroxyapatite-loaded thiophanate-copper nanopesticide suspension; then 0.005 g of chitosan powder was weighed and dissolved in 5 mL of acetic acid solution, and magnetically stirred at 35°C for 2 h to obtain a chitosan solution; under magnetic stirring at 400 r / min, it was added dropwise to the micro-nano hydroxyapatite-loaded thiophanate-copper nanopesticide suspension at a speed of 1 mL per minute. After the addition was completed, stirring was continued at 400 r / min for 1 h to obtain a new nanopesticide with a total volume of 100 mL that can long-term slow-release copper and phosphorus nutrients (i.e., slow-release nanopesticide nHAP-OCu).

[0082] Example 4: Standard solutions with copper concentrations of 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, 10 mg / L, and 20 mg / L were prepared. The absorbance values ​​of the copper solutions at different concentrations were tested using a flame atomic absorption spectrometer. A standard curve was drawn to establish the relationship between the sample absorbance and the copper concentration, and a method for determining the copper concentration of different sample solutions was constructed.

[0083] Example 5:

[0084] The newly prepared copper hydroxide nanopesticide (nHAP-nCu) in Example 1 was allowed to stand for stratification. The supernatant was collected after standing for 0 days, 1 day, 2 days, 5 days, and 10 days. The supernatant was centrifuged at 5000 r / min for 10 minutes. The supernatant was filtered through a 0.45-micron microporous membrane and the absorbance of the samples was measured by flame atomic absorption spectroscopy under a copper lamp light source. The change in copper concentration in the copper hydroxide nanopesticide (nHAP-nCu) suspension over time was calculated based on the standard curve of copper concentration in aqueous solution provided in Example 4. The change in copper ion release over time was compared between the prepared copper hydroxide nanopesticides (nHAP-nCu) of different sizes and the original pesticide (i.e., the control group, ck group). The nanopesticides loaded with the three different sizes of micro-nanohydroxyapatite all released a significant amount of copper ions in the suspension, with a significantly higher release rate than the unloaded pesticide. Among them, the copper release concentration of nanopesticides with a size of 60nm and 80μm is higher, about 700mg / L. The difference in copper release over time of copper hydroxide nanopesticides of different sizes is as follows Figure 2 shown.

[0085] Example 6:

[0086] The newly prepared copper sulfate nanopesticide suspension nHAP-ICu from Example 2 was allowed to stand for stratification. The supernatant was then drawn after standing for 0, 1, 2, 5, and 10 days. The supernatant was then centrifuged at 5000 r / min for 10 min. The absorbance of the supernatant was measured by flame atomic absorption spectrometry under a copper lamp light source. The change in copper concentration over time in the copper sulfate nanopesticide suspension nHAP-ICu was calculated based on the standard curve for copper concentration in aqueous solution provided in Example 4. The change in copper ion release over time in the prepared copper sulfate nanopesticides (nHAP-ICu) of different sizes and Bordeaux mixture pesticides was compared. Calculations revealed that Bordeaux mixture pesticides not loaded with nanocarriers essentially failed to release copper ions in the suspension and required use in conjunction with other agents during actual use to release the bactericidal copper ions. After being loaded with three different sizes of micro-nano hydroxyapatite, the nanopesticides were able to release more copper ions in the suspension. Among them, the copper release effect of the nanopesticide with a size of 60nm was better than that of the nanopesticide with a size of 20nm and 80μm. Figure 3 shown.

[0087] Example 7:

[0088] The newly prepared thiophanate-copper nanopesticide (nHAP-OCu) suspension in Example 3 was allowed to stand for stratification. The supernatant was collected after standing for 0 days, 1 day, 2 days, 5 days, and 10 days. The supernatant was centrifuged at 5000 r / min for 10 minutes. The supernatant was taken and the absorbance of the samples was measured by flame atomic absorption spectrometry under a copper lamp light source. The change in the copper concentration of the thiophanate-copper nanopesticide (nHAP-OCu) and the thiophanate-copper nanopesticide over time was calculated based on the standard curve of copper concentration in aqueous solution provided in Example 4. The change in copper ion release over time in the prepared thiophanate-copper nanopesticides (nHAP-OCu) of different sizes was compared. Calculations show that the copper hydroxide nanopesticide without nanocarrier support can release 300-500 mg / L of copper ions in the suspension, and the copper concentration slowly increases with time. Calculations show that the copper concentration released from the original thiophanate-copper pesticide without micro-nano hydroxyapatite loading first decreases and then increases over time, while the copper concentration released from the three different sizes of thiophanate-copper nanopesticides is significantly lower, indicating that the thiophanate-copper pesticide and the hydroxyapatite nanocarrier are organically chelated under the strong interaction on the surface of the nanopesticide. Figure 4 shown.

[0089] Example 8

[0090] This example provides an application method of copper sulfate nanopesticide loaded on micro-nano hydroxyapatite. The retention and release performance of three types of copper preparation nanopesticide loaded on micro-nano hydroxyapatite prepared in Example 1, Example 2, and Example 3 in soil were compared by leaching experiments. Figure 1 When applied in the soil, a soil column with a height of 10 cm and a cross-section of 5 cm in diameter was used for leaching to test the performance of copper hydroxide nanopesticide in releasing copper in the soil. 5 mL of ultrapure water was dripped onto the soil column every day. After 10 days of leaching, the soil column was divided into 5 cm layers, and the upper and lower layers of the soil column were collected. XRF was used to detect the difference in copper content in the upper and lower layers of the soil. The copper content detected in the upper soil layer is as follows: Figure 6 As shown in Figure 2, the total amount of copper retained by the loaded nanopesticide in the upper soil layer is greater than that of the original pesticide. The copper content detected in the lower soil layer is as follows: Figure 7 As shown, the results show that during the leaching process of 60nm and 80um loaded copper hydroxide nanopesticides, the copper content in the lower layer of soil did not increase, indicating that the use of 60nm and 80um loaded copper preparations to prepare nanopesticides can significantly reduce the risk of copper loss during leaching.

[0091] It can be seen that the new nanopesticide of the present invention has been tested and verified for the slow release of copper and phosphorus during soil application. Compared with existing pesticides, the slow release effect of copper is better, with less loss due to water erosion, and it can slowly release phosphorus in the soil, increasing fertilizer efficiency and reducing the risk of nutrient waste, which has more beneficial effects on soil health and crop growth.

[0092] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A sustained-release and controlled-release nanopesticide, characterized in that: The sustained-release and controlled-release nanopesticide is an aqueous suspension with water as a solvent, and the aqueous suspension includes micro-nano hydroxyapatite, a copper pesticide and chitosan; the copper pesticide is adsorbed on the micro-nano hydroxyapatite, and the chitosan is at least partially coated on the surface of the copper pesticide; The mass ratio of the micro-nano hydroxyapatite, the copper pesticide and the chitosan is (50-100):(50-100):1; and every 100 ml of the aqueous suspension contains 0.5-1 g of micro-nano hydroxyapatite.

2. The sustained-release and controlled-release nanopesticide according to claim 1, characterized in that: The particle size of the micro-nano hydroxyapatite ranges from 20 nanometers to 80 micrometers.

3. The sustained-release and controlled-release nanopesticide according to claim 1, characterized in that: The mass ratio of the micro-nano hydroxyapatite, the copper preparation pesticide and the chitosan is 100:100:

1.

4. The sustained-release controlled-release nanopesticide according to any one of claims 1 to 3, characterized in that: The copper preparation pesticide is at least one of Bordeaux mixture, copper hydroxide pesticide preparation, and thiophanate-methyl preparation.

5. A method for preparing the sustained-release and controlled-release nanopesticide according to claim 1, characterized in that: The following steps are involved: Dissolve chitosan in acetic acid solution and stir at 30-40° C. to obtain a chitosan solution; Adding the copper pesticide dropwise into the micro-nano hydroxyapatite suspension and mixing well to obtain a mixed liquid; Adding the chitosan solution dropwise into the mixed liquid and reacting for 1 hour to obtain the slow-release and controlled-release nanopesticide; The mass ratio of the micro-nano hydroxyapatite, the copper preparation pesticide and the chitosan is (50-100):(50-100):1; and every 100 ml of the sustained-release and controlled-release nanopesticide contains 0.5-1 g of micro-nano hydroxyapatite.

6. The preparation method according to claim 5, characterized in that The concentration of the acetic acid solution is 2 mol / L.

7. The preparation method according to claim 5, characterized in that The preparation method of the micro-nano hydroxyapatite suspension comprises: 0.5-1g of micro-nano hydroxyapatite is mixed with 75mL of water, and stirred for 30min-1h at room temperature and a stirring speed of 300-500r / min to prepare a micro-nano hydroxyapatite suspension.

8. The preparation method according to claim 5, characterized in that The step of adding the copper pesticide dropwise to the micro-nano hydroxyapatite suspension and mixing the mixture comprises: The copper preparation pesticide is added dropwise to the micro-nano hydroxyapatite suspension at a rate of 2 mL / min. After all the addition is completed, magnetic stirring is performed for 30 min to 1 h.

9. The preparation method according to any one of claims 5 to 8, characterized in that In the step of adding the chitosan solution dropwise to the mixed liquid and reacting for 1 hour, the dropping speed is 1 mL / min and the reaction time is 1 hour.

10. Use of the sustained-release controlled-release nanopesticide according to any one of claims 1 to 4 or the sustained-release controlled-release nanopesticide obtained by the preparation method according to any one of claims 5 to 9 in agricultural production.

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