Pesticide sustained release preparation and preparation method thereof

Abstract

The invention discloses a pesticide sustained-release preparation and a preparation method thereof, and belongs to the technical field of pesticide sustained-release preparations, water is subjected to ultrasonic treatment, protective gas is introduced, lauryl sodium sulfate is added and dissolved, then two soluble metal salts are added, the pH value is adjusted to 9.5-11.5 for a reaction, the two soluble metal salts are converted into layered double hydroxides, and the layered double hydroxides are subjected to ultrasonic treatment to obtain the pesticide sustained-release preparation. Meanwhile, sodium dodecyl sulfate is intercalated into the layered double hydroxide, and organic layered double hydroxide, namely organic LDHs, is obtained; and dispersing the organic layered double hydroxide in a biopesticide to obtain the pesticide sustained release preparation. The lauryl sodium sulfate is intercalated into the organic LDHs, and a hydrophobic phase is constructed between layers of the organic LDHs, so that the adsorption capacity of hydrophobic pesticide is remarkably increased, the permeability of the organic LDHs is remarkably reduced through intercalation of the lauryl sodium sulfate, and the release rate of biological pesticide is effectively slowed down.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide sustained-release agents, and in particular to a pesticide sustained-release preparation and a preparation method thereof. Background Art

[0002] Pesticides can play a significant protective role on crops. Reasonable application of pesticides can effectively reduce the threat of pests such as insects, mites, nematodes, pathogens, weeds and rats to crop yields. However, pesticides generally have problems such as reduced efficacy, increased dosage, residues and environmental risks in actual agricultural applications, which not only increases the cost of agricultural production, but also poses a serious threat to human health and natural ecosystems. Sustained-release preparations can continuously release active drug molecules in a specific medium for a long time, with the advantages of labor saving, cost saving, long-term effect and low toxicity, and are currently a hot topic in pesticide formulation research.

[0003] Layered double hydroxides (LDHs) are hydroxides composed of two or more metal elements with a hydrotalcite layered crystal structure. Since being first discovered by Hochstetter in 1842, LDHs have been widely used in the preparation and research of polar anionic pesticide slow-release agents due to their unique layered structure, large interlayer space and high anion exchange capacity. Meng Zilin, Kovanda, Li Yan and other scholars used LDHs as a slow-release matrix to prepare a series of pesticide slow-release preparations with good slow-release performance. First, LDHs were synthesized by hydrothermal method, and then the pesticide 2,4-D was exchanged to the LDHs interlayer by ion exchange method to prepare a pesticide slow-release agent, and the electrostatic interaction between the sheet and 2,4-D was used to achieve the slow-release effect.

[0004] However, since polar anionic pesticides are mainly adsorbed between LDHs layers through electrostatic effects, the magnitude of the electrostatic attraction is relatively fixed. Therefore, the release performance of LDHs-based sustained-release matrices is relatively simple. In addition, a considerable portion of existing pesticides are hydrophobic non-ionic drugs, which have a low affinity with LDHs and are difficult to enter the hydrophilic interlayer region through ion exchange, which severely limits their drug loading capacity and drug loading range. Summary of the invention

[0005] The present invention provides a pesticide sustained-release preparation and a preparation method and application thereof, which effectively solve the technical problems that the release performance of the existing layered double hydroxide-based sustained-release substrate is relatively simple, the hydrophobic non-ionic drug has low affinity with the layered double hydroxide-based sustained-release substrate, and it is difficult for the drug to enter the hydrophilic interlayer region through ion exchange, thereby reducing the drug loading and limiting the types of drug loading, and at the same time provides a pesticide sustained-release preparation with high drug loading and controllable sustained-release performance.

[0006] The first object of the present invention is to provide a method for preparing a pesticide sustained-release formulation, comprising the following steps:

[0007] Water is ultrasonicated and a protective gas is introduced, sodium dodecyl sulfate is added and dissolved, two soluble metal salts are added, the pH value is adjusted to 9.5-11.5, and the two soluble metal salts are reacted to convert them into layered double hydroxides, and sodium dodecyl sulfate is intercalated into the layered double hydroxide to obtain an organic layered double hydroxide.

[0008] The two soluble metal salts are two divalent metal salts, two trivalent metal salts, or one divalent metal salt and one trivalent metal salt.

[0009] The organic layered double hydroxide is dispersed in the biological pesticide, and the biological pesticide is adsorbed on the organic layered double hydroxide to obtain a pesticide slow-release preparation.

[0010] As a preferred embodiment, the usage ratio of the sodium dodecyl sulfate to the two soluble metal salts is 1.5-12 g: 0.005-0.04 mol.

[0011] As a preferred embodiment, the mass ratio of the organic layered double hydroxide to the biopesticide is 1:0.04-0.24.

[0012] As a preferred embodiment, the soluble metal salt is selected from any two of magnesium nitrate, aluminum nitrate, zinc nitrate, calcium chloride, nickel nitrate and iron nitrate.

[0013] As a preferred embodiment, the biological pesticide is a hydrophobic pesticide.

[0014] As a preferred embodiment, the hydrophobic pesticide is pretilachlor, acetochlor, carbaryl or emamectin benzoate.

[0015] As a preferred embodiment, the reaction time is 3 to 4 hours.

[0016] As a preferred embodiment, NaOH solution is used to adjust the pH value to 9.5-11.5.

[0017] The second object of the present invention is to provide a pesticide sustained-release preparation obtained by the above preparation method.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a method for preparing a pesticide slow-release preparation, firstly ultrasonicating water and introducing a protective gas, adding sodium dodecyl sulfate to dissolve, then adding two soluble metal salts, adjusting the pH value to 9.5-11.5 for reaction, converting the two soluble metal salts into layered double hydroxides, and simultaneously intercalating sodium dodecyl sulfate into the layered double hydroxides to obtain organic layered double hydroxides, i.e., organic LDHs; and dispersing the organic layered double hydroxides into biological pesticides to obtain a pesticide slow-release preparation. The present invention intercalates sodium dodecyl sulfate into organic LDHs, and by constructing a hydrophobic phase between the organic LDHs layers, not only the adsorption amount of the hydrophobic pesticide is significantly increased, but also the permeability of the organic LDHs is significantly reduced by the intercalation of sodium dodecyl sulfate, thereby effectively slowing down the release rate of the biological pesticide.

[0020] The present invention further optimizes the controlled-release effect of the biopesticide by studying the relationship between the organic LDHs loading and the drug release rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the preparation process and performance exploration process of the pesticide sustained-release preparation of Example 1 of the present invention.

[0022] Figure 2 The XRD diffraction patterns of the layered double hydroxides (LDHs) of Comparative Example 1 and the organic layered double hydroxides (organic LDHs) of Examples 1 to 4 of the present invention are shown in FIG. 0.5 -LDHs is Example 1, SDS 1 -LDHs is Example 2, SDS 2 -LDHs is Example 3, SDS 4 -LDHs is Example 4.

[0023] Figure 3 The sodium dodecyl sulfate used in the present invention, the LDHs of comparative example 1 and the organic LDHs of examples 1 to 4 have infrared absorption spectra, wherein SDS 0.5 -LDHs is Example 1, SDS 1 -LDHs is Example 2, SDS 2 -LDHs is Example 3, SDS 4 -LDHs is Example 4.

[0024] Figure 4 The electron microscope images of the LDHs of comparative example 1 of the present invention and the organic LDHs of examples 1 to 4, wherein (a) is the LDHs, and (b) is the SDS of example 1. 0.5 -LDHs, (c) Figure is SDS of Example 2 1 -LDHs, (d) Figure is the SDS of Example 3 2-LDHs, (e) Figure is SDS of Example 4 4 -LDHs.

[0025] Figure 5 The water contact angles of the LDHs and organic LDHs of Example 1 of the present invention, wherein (a) is the LDHs of Comparative Example 1, and (b) is the SDS of Example 1. 0.5 -LDHs, (c) Figure is SDS of Example 2 1 -LDHs, (d) Figure is the SDS of Example 3 2 -LDHs, (e) Figure is SDS of Example 4 4 -LDHs.

[0026] Figure 6 is the adsorption isotherm of pretilachlor on LDHs and organic LDHs of the present invention, wherein LDHs is Comparative Example 1, SDS 0.5 -LDHs is Example 1, SDS 1 -LDHs is Example 2, SDS 2 -LDHs is Example 3, SDS 4 -LDHs is Example 4.

[0027] Figure 7 The release kinetic curve of pretilachlor from LDHs and organic LDHs of the present invention is shown in FIG. 1 , wherein LDHs is Comparative Example 1, and SDS 0.5 -LDHs is Example 1, SDS 1 -LDHs is Example 2, SDS 2 -LDHs is Example 3, SDS 4 -LDHs is Example 4. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention. The following test methods and detection methods, unless otherwise specified, are conventional methods; the reagents and raw materials, unless otherwise specified, are commercially available.

[0029] In view of the above-mentioned technical problems mentioned in the background of the present invention: first, polar anionic pesticides are mainly adsorbed between organic layered double hydroxide (LDHs) sheets through electrostatic action, and the magnitude of electrostatic attraction is relatively fixed, so the release performance of LDHs-based sustained-release substrates is relatively simple; second, hydrophobic non-ionic drugs in existing pesticides have low affinity with LDHs and are difficult to enter the hydrophilic interlayer region through ion exchange, which seriously limits their drug loading and drug loading range. Based on the above technical problems, the present invention provides a pesticide sustained-release preparation and a preparation method thereof.

[0030] The technical contents of the present invention are analyzed and explained in detail below.

[0031] The present invention provides a method for preparing a pesticide sustained-release preparation, comprising the following steps:

[0032] Distilled water is ultrasonicated and nitrogen is introduced, sodium dodecyl sulfate is added and dissolved, two soluble metal salts are added, and the pH value is adjusted to 9.5-11.5 with NaOH solution. The reaction is carried out for 3-4 hours to convert the two soluble metal salts into layered double hydroxides. At the same time, sodium dodecyl sulfate is intercalated into the layered double hydroxide to obtain organic layered double hydroxides, which are recorded as organic LDHs.

[0033] The organic layered double hydroxide is dispersed in the biological pesticide to obtain a pesticide slow-release preparation.

[0034] In the above technical scheme, sodium dodecyl sulfate is intercalated into organic layered double hydroxides. By constructing a hydrophobic phase between the organic LDHs layers, not only the adsorption amount of hydrophobic pesticides is increased, but also the permeability of organic LDHs is significantly reduced by the intercalation of sodium dodecyl sulfate, thereby effectively slowing down the release rate of biological pesticides.

[0035] For pH values ​​of 9.5 to 11.5, if the pH value is less than 9.5 or greater than 11.5, the organic LDHs cannot be synthesized or the crystal structure is very poor and incomplete, which in turn leads to a decrease in drug loading and poor sustained-release performance.

[0036] In order to form a stable layered structure and perform organic modification, the two soluble metal salts are two divalent metal salts, two trivalent metal salts, or one divalent metal salt and one trivalent metal salt. The divalent metals and trivalent metals in organic LDHs are arranged in a certain proportion. The presence of trivalent metals will cause the layer plates to generate positive charges, which are balanced by interlayer anions, thereby forming a stable layered structure. At the same time, the combination of divalent and trivalent metal ions gives organic LDHs unique chemical properties. This combination makes LDHs have good ion exchange properties, and the interlayer anions can be exchanged with external anions, which facilitates organic modification.

[0037] It should be noted that the dosage ratio of sodium dodecyl sulfate to the two soluble metal salts is 1.5-12 g: 0.005-0.04 mol. Too low a dosage of sodium dodecyl sulfate will result in poor hydrophobicity of organic LDHs, low drug loading, and poor sustained-release performance; and continuing to increase the dosage of sodium dodecyl sulfate, exceeding the dosage value specified herein, even if the drug loading and sustained-release performance of the pesticide sustained-release preparation are not greatly affected, the excessive use of sodium dodecyl sulfate will cause unnecessary waste.

[0038] In order to balance the drug loading and drug efficacy of the organic layered double hydroxide, the dosage ratio of the organic layered double hydroxide to the biopesticide is 1:0.04-0.24. Considering the pesticide efficacy and the maximum drug loading of organic LDHs, too much organic LDHs will lead to too little drug loading and reduce the efficacy.

[0039] It should be noted that the biological pesticide is a hydrophobic pesticide, and the hydrophobic pesticide is pretilachlor, acetochlor, carbaryl or emamectin benzoate.

[0040] The technical effects of the present invention are described below in conjunction with specific embodiments.

[0041] Example 1

[0042] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0043] S1, measure 300mL of distilled water and put it into a three-necked bottle. After ultrasonication for 20min, nitrogen is passed under the liquid surface for 10min, and then 1.5g of sodium dodecyl sulfate is added respectively. After stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate are added respectively. The pH is adjusted to 10 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution is centrifuged, and the substrate is dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0044] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0045] Example 2

[0046] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0047] S1, 300mL of distilled water was measured and put into a three-necked flask, and nitrogen was passed under the liquid surface for 10min after ultrasonic treatment for 20min, and then 3g of sodium dodecyl sulfate was added respectively, and after stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate were added respectively, and the pH was adjusted to 10 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution was centrifuged, and the substrate was dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0048] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0049] Example 3

[0050] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0051] S1, measure 300mL of distilled water and put it into a three-necked bottle. After ultrasonication for 20min, nitrogen is passed under the liquid surface for 10min, and then 6g of sodium dodecyl sulfate is added respectively. After stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate are added respectively. The pH is adjusted to 10 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution is centrifuged, and the substrate is dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0052] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0053] Example 4

[0054] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0055] S1, measure 300mL of distilled water and put it into a three-necked bottle. After ultrasonication for 20min, nitrogen is passed under the liquid surface for 10min, and then 12g of sodium dodecyl sulfate is added respectively. After stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate are added respectively. The pH is adjusted to 10 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution is centrifuged, and the substrate is dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0056] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0057] Example 5

[0058] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0059] S1, measure 300mL of distilled water and put it into a three-necked bottle. After ultrasonication for 20min, nitrogen is passed under the liquid surface for 10min, and then 6g of sodium dodecyl sulfate is added respectively. After stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate are added respectively. The pH is adjusted to 10 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution is centrifuged, and the substrate is dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0060] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of a 10 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0061] Example 6

[0062] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0063] S1, measure 300mL of distilled water and put it into a three-necked bottle. After ultrasonication for 20min, nitrogen is passed under the liquid surface for 10min, and then 6g of sodium dodecyl sulfate is added respectively. After stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate are added respectively. The pH is adjusted to 10 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution is centrifuged, and the substrate is dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0064] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of a 30 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0065] Example 7

[0066] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0067] S1, 300mL of distilled water was measured and put into a three-necked flask, and nitrogen was passed under the liquid surface for 10min after ultrasonic treatment for 20min, and then 6g of sodium dodecyl sulfate was added respectively, and stirred until completely dissolved, and then 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate were added respectively, and the pH was adjusted to 11 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution was centrifuged, and the substrate was dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0068] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0069] Example 8

[0070] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0071] S1, measure 300mL of distilled water and put it into a three-necked bottle. After ultrasonication for 20min, nitrogen is passed under the liquid surface for 10min, and then 6g of sodium dodecyl sulfate is added respectively. After stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate are added respectively. The pH is adjusted to 11.5 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution is centrifuged, and the substrate is dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0072] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0073] Example 9

[0074] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0075] S1, measure 300mL of distilled water and put it into a three-necked bottle. After ultrasonication for 20min, nitrogen is passed under the liquid surface for 10min, and then 6g of sodium dodecyl sulfate is added respectively. After stirring until completely dissolved, 11.55g of magnesium nitrate hexahydrate and 5.63g of aluminum nitrate nonahydrate are added respectively. The pH is adjusted to 9.5 with a sodium hydroxide solution with a concentration of 0.5mol / L. After reacting for 4h, the reaction solution is centrifuged, and the substrate is dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain an organic layered double hydroxide, i.e., organic LDHs.

[0076] S2, accurately weigh 25 mg of organic LDHs, add them into 100 mL of 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0077] In order to further illustrate the technical effect of the present invention, the present invention also sets a comparative example, which is as follows:

[0078] Comparative Example 1

[0079] Compared with Example 1, the difference is that sodium lauryl sulfate is not added.

[0080] A method for preparing a pesticide sustained-release preparation comprises the following steps:

[0081] S1, 300 mL of distilled water was measured and put into a three-necked bottle, and nitrogen was passed into the liquid for 10 minutes after ultrasonic treatment for 20 minutes, and 11.55 g of magnesium nitrate hexahydrate and 5.63 g of aluminum nitrate nonahydrate were added respectively, and the pH was adjusted to 10 with a sodium hydroxide solution with a concentration of 0.5 mol / L. After reacting for 4 hours, the reaction solution was centrifuged, and the substrate was dried at 60°C to constant weight, passed through a 100-mesh sieve and stored for later use to obtain layered double hydroxides, i.e., LDHs.

[0082] S2, accurately weigh 25 mg of LDHs, add them into 100 mL of a 60 mg / L pretilachlor solution, place them in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h to obtain a pesticide sustained-release preparation.

[0083] The performance of the organic LDHs and pesticide slow-release preparations prepared in the above examples was tested, and the specific process and results are as follows:

[0084] 1. XRD determination

[0085] The XRD patterns of LDHs and organic LDHs were measured using an X-ray diffractometer. Cu-Ka rays were used for the measurement. The scanning speed is 10° / min, the scanning step is 0.02°, and the scanning range is 2 to 55°. The material bottom surface spacing (d 001 ).

[0086] Table 1 Interlayer distances of LDHs and organic LDHs and symmetric and asymmetric infrared absorption wavenumbers of methylene groups in sodium dodecyl sulfate and organic LDHs

[0087] sample <![CDATA[d 003 / nm]]> <![CDATA[V as (CH 2 ) / cm -1 ]]> <![CDATA[V s (CH 2 ) / cm -1 ]]> SDS 2917 2850 LDHs 0.81 <![CDATA[SDS 0.5 -LDHs]]> 0.83 2924 2855 <![CDATA[SDS 1 -LDHs]]> 2.80 2922 2853 <![CDATA[SDS 2 -LDHs]]> 2.59 2922 2853 <![CDATA[SDS 4 -LDHs]]> 2.72 2921 2852

[0088] Figure 2 The XRD diffraction patterns of LDHs and organic LDHs show that LDHs have diffraction peaks at 11.1°, 21.7° and 34.6°, respectively, which are consistent with the diffraction characteristic peaks of the typical Mg-Al LDHs (003), (006) and (012) crystal planes, indicating that Mg-Al LDHs were successfully prepared in the experiment. And the interlayer distance of LDHs calculated by the Bragg formula is 0.82nm. After modification with sodium dodecyl sulfate, the diffraction angle of the (003) diffraction peak moves to a smaller angle, and the interlayer distance of organic LDHs calculated by the Bragg formula ranges from 0.83 to 2.80nm, as shown in Table 1, indicating that sodium dodecyl sulfate is successfully intercalated into the LDHs interlayer and organic LDHs are successfully prepared.

[0089] 2. FTIR measurement

[0090] The infrared spectra of LDHs and organic LDHs were measured using a Fourier visible-infrared spectrometer. The scanning range was 4000 cm -1 ~400cm -1 , resolution 4cm -1 .

[0091] Figure 3 The infrared absorption spectra of sodium dodecyl sulfate, LDHs and organic LDHs. After modification with sodium dodecyl sulfate, LDHs has an absorption peak at 2917 cm -1 and 2850cm -1 A new wave number appears at the methylene group (CH 2 ), which indicates that organic LDHs were successfully prepared. And the wave number of the infrared absorption peak of the methylene group shifted significantly with the increase of the modifier loading, as shown in Table 1, which indicates that the arrangement of sodium dodecyl sulfate between the layers changed from a disordered loose conformation to an ordered tightly packed conformation.

[0092] 3. Electron microscopy observation

[0093] LDHs and organic LDHs powders were fixed on metal columns respectively, and the surface was sprayed with gold and then the surface morphology was observed using an electron scanning microscope.

[0094] Figure 4 The electron microscope images of LDHs and organic LDHs, where (a) to (e) are LDHs and SDS, respectively. 0.5 -LDHs, SDS 1 -LDHs, SDS 2 -LDHs, SDS 4 -LDHs. LDHs show a typical dispersed lamellar structure. After modification with sodium dodecyl sulfate, organic LDHs show irregular stacking, and the irregular stacking phenomenon intensifies with the increase of modifier loading, which is related to the physicochemical properties of the modifier and the stacking mode of hydrocarbon chains.

[0095] 4. Contact Angle Measurement

[0096] The LDHs and organic LDHs powders were pressed into sheets, and their water contact angles were measured using a contact angle meter.

[0097] Figure 5 are the water contact angles of LDHs and organic LDHs, where (a) to (e) are the water contact angles of LDHs and SDS, respectively. 0.5 -LDHs, SDS 1 -LDHs, SDS 2 -LDHs, SDS 4-LDHs. The water contact angle of LDHs is 42.5°, showing strong hydrophilicity. After modification with sodium dodecyl sulfate, the water contact angle of organic LDHs increases to 48.3°~78.7°, indicating that its hydrophilicity is significantly weakened and its hydrophobicity is significantly enhanced. When the water contact angle is greater than 90°, the material will show absolute non-wettability. The water contact angles of organic LDHs are all less than 90°, showing appropriate wetting ability, which is conducive to the drug loading and release of organic LDHs in an aqueous environment.

[0098] 5. Adsorption isotherm experiment of pretilachlor on organic LDHs

[0099] Accurately weigh 25 mg of organic LDHs and add them into 100 mL of a 10-60 mg / L pretilachlor solution. Place the mixture in a 30°C water bath with a constant temperature magnetic stirrer and stir for 4 h. Determine the equilibrium concentration of pretilachlor in the solution by HPLC and calculate the adsorption amount.

[0100] Table 2 Fitting parameters of adsorption of pretilachlor on organic LDHs

[0101]

[0102] Figure 6 Figure 2 is the adsorption isotherm of pretilachlor on LDHs and organic LDHs. LDHs showed poor adsorption capacity. After modification with sodium dodecyl sulfate, the adsorption capacity of organic LDHs for pretilachlor was significantly enhanced, and the adsorption capacity increased with the increase of the modifier loading. The experimental data were fitted using the Freundlich and Langmuir kinetic equations. 2 The value is closer to 1, as shown in Table 2. Therefore, the Freundlich kinetic equation can more vividly describe the adsorption of pretilachlor on organic LDHs, which shows that the adsorption of pretilachlor on organic LDHs is multilayer adsorption.

[0103] 6. Release kinetics of pretilachlor on organic LDHs

[0104] (1) Preparation of drug-loaded organic LDHs

[0105] Weigh 1 g of organic LDH and disperse it in 2 L of 60 mg / L pretilachlor solution. After stirring for 4 h, filter and dry the sample for later use.

[0106] (2) Drug loading determination

[0107] Accurately weigh 25 mg of drug-loaded organic LDHs and add it to 50 mL of methanol. Ultrasonicate for 10 min, magnetically stir for 20 min, and then make up the volume.

[0108] The experiment was carried out in parallel three times and the drug loading was calculated.

[0109] (3) Release kinetics

[0110] Weigh 25 mg of drug-loaded organic LDHs and put it into 200 mL of deionized water. Stir magnetically at 30°C, take 1 mL of the solution at 15 min, 30 min, 1 h, 2 h, 4 h, 8 h, 12 h, 16 h, 20 h, and 24 h, filter it with a filter head, and determine the concentration of pretilachlor by HPLC to calculate the release rate.

[0111] Table 3 Pretilachlor loading and Rigter-Peppas equation fitting parameters

[0112]

[0113] As shown in Table 3, the drug loading of pretilachlor on organic LDHs increased significantly after modification with sodium dodecyl sulfate. Figure 7 The release kinetics curve of pretilachlor from LDHs and organic LDHs. The intercalation of sodium dodecyl sulfate significantly reduced the release rate of pretilachlor, and with the increase of the modifier loading, the release rate of pretilachlor gradually slowed down. The release kinetics data were fitted using the Rigter-Peppas equation to calculate T 50 value (the time generally used for the release of pretilachlor), the results showed that the T 50 The values ​​were 4.78 to 45.34 times that of LDHs. The fitting parameter n value was less than 0.34, indicating that the release of pretilachlor from organic LDHs followed the Fickian diffusion law.

[0114] In summary, the present invention intercalates sodium dodecyl sulfate into organic LDHs and constructs a hydrophobic phase between the organic LDHs layers, which not only significantly increases the adsorption amount of hydrophobic pesticides, but also significantly reduces the permeability of organic LDHs through the intercalation of sodium dodecyl sulfate, thereby effectively slowing down the release rate of biological pesticides.

[0115] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a pesticide sustained-release preparation, characterized in that: The following steps are involved: Ultrasonicate the water and introduce protective gas, add sodium dodecyl sulfate, dissolve it, add two soluble metal salts, adjust the pH value to 9.5-11.5, react, convert the two soluble metal salts into layered double hydroxides, and insert sodium dodecyl sulfate into the layered double hydroxide to obtain an organic layered double hydroxide; The two soluble metal salts are two divalent metal salts, two trivalent metal salts, or one divalent metal salt and one trivalent metal salt; The organic layered double hydroxide is dispersed in the biological pesticide, and the biological pesticide is adsorbed on the organic layered double hydroxide to obtain a pesticide slow-release preparation.

2. The preparation method according to claim 1, characterized in that: The dosage ratio of the sodium dodecyl sulfate to the two soluble metal salts is 1.5-12 g: 0.005-0.04 mol.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the organic layered double hydroxide to the biological pesticide is 1:0.04-0.

24.

4. The preparation method according to claim 1, characterized in that: The soluble metal salt is selected from any two of magnesium nitrate, aluminum nitrate, zinc nitrate, calcium chloride, nickel nitrate and iron nitrate.

5. The preparation method according to claim 1, characterized in that: The biological pesticide is a hydrophobic pesticide.

6. The preparation method according to claim 5, characterized in that: The hydrophobic pesticide is pretilachlor, acetochlor, carbaryl or emamectin benzoate.

7. The preparation method according to claim 1, characterized in that: The reaction time is 3 to 4 hours.

8. The preparation method according to claim 1, characterized in that: The pH value was adjusted to 9.5-11.5 using NaOH solution.

9. A pesticide sustained-release preparation prepared by the preparation method according to any one of claims 1 to 8.

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