Metal organic framework, nano-herbicide and preparation method thereof

Abstract

The application provides a metal organic framework material, a nano herbicide and a preparation method thereof, and belongs to the technical field of pesticides. The nano herbicide is obtained by loading pesticide raw materials under the action of a loaded solvent. The nano herbicide provided by the application has a dispersion scale of nanometer level, reaches 100-200 nm, and has good controlled release performance. By using the small scale effect, the absorption and transmission performance of the herbicide in the target crop can be improved, and the inhibition effect of the herbicide on weed growth is enhanced. Meanwhile, the dispersibility of the pesticide can be improved, the deposition rate of the pesticide on the leaves of the target crop is improved, the off-target or loss of the pesticide caused by the too large particle size is avoided, and thus the effective utilization rate of the pesticide is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pesticides, in particular to a metal-organic framework material, a nano-herbicide and a preparation method thereof. BACKGROUND

[0002] In agricultural production, chemical weeding is an economical and effective method of weeding, which has been widely adopted. Herbicides are a class of agricultural chemicals that have the most active research and the most rapid development. At present, the herbicide preparation products used in China mainly include emulsifiable concentrate, suspension concentrate, emulsion in water (emulsifiable concentrate), microemulsion, wettable powder and water dispersible granule, etc. However, these preparation products have limitations such as a large amount of organic solvent used, dust drift, poor dispersibility, etc., resulting in a low effective utilization rate of herbicides.

[0003] Patent CN114437365B discloses a pesticide nano-drug-loaded particle framework material obtained by using trivalent iron as a metal node and modifying the surface thereof with an amino group, and loading imidacloprid, tebuconazole, thifluzamide and other insecticides or fungicides. However, the loaded substances are all insecticides, and there is a lack of metal-organic framework materials for effectively loading herbicides in the prior art. SUMMARY

[0004] Therefore, the present application aims to provide a metal-organic framework material, a nano-herbicide and a preparation method thereof. The nano-herbicide prepared from the metal-organic framework material has a particle size of 100-200 nm, has good controlled release performance, has a strong inhibitory effect on weed growth, and has a high effective utilization rate.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A preparation method of a metal-organic framework material, comprising the following steps:

[0007] Mixing a soluble zinc salt with a first solvent to obtain a zinc salt solution;

[0008] Mixing 2-methylimidazole with a second solvent to obtain a 2-methylimidazole solution;

[0009] Under stirring, dropping the 2-methylimidazole solution into the zinc salt solution to perform a coordination bonding reaction to obtain a reaction liquid;

[0010] Centrifuging the reaction liquid, and sequentially washing and drying the obtained precipitate to obtain a metal-organic framework.

[0011] Preferably, the soluble zinc salt comprises at least one of zinc nitrate, zinc sulfate and zinc acetate; the first solvent comprises methanol, ethanol or water; and the second solvent is consistent with the first solvent.

[0012] Preferably, the mass fraction of zinc element in the zinc salt solution is 1-1.5%; and the mass fraction of 2-methylimidazole in the 2-methylimidazole solution is 10-20%.

[0013] Preferably, the volume ratio of the 2-methylimidazole solution to the zinc salt solution is 1:1.

[0014] The application further provides a metal organic framework material prepared by the above preparation method, wherein the metal organic framework material is composed of a crystal with a regular hexahedron structure, and the particle size of the crystal is 100-200 nm.

[0015] The application further provides a nano herbicide, which comprises the metal organic framework material and a herbicide active ingredient, wherein the herbicide active ingredient is loaded on the metal organic framework material, the drug loading rate of the metal organic framework material is 5-60%, and the particle size of the herbicide is 100-200 nm.

[0016] Preferably, the herbicide active ingredient comprises at least one of 2,4-D, mesotrione and cyhalofop-butyl.

[0017] The application further provides a preparation method of the above herbicide, which comprises the following steps.

[0018] Mixing the herbicide active ingredient, the metal organic framework material and a loading solvent to obtain a mixture;

[0019] Stirring and centrifuging the mixture in sequence to obtain a precipitate;

[0020] Drying the precipitate to obtain a nano herbicide.

[0021] Preferably, the mass ratio of the herbicide active ingredient to the metal organic framework material is (0.5-3):1.

[0022] Preferably, the loading solvent comprises methanol, acetonitrile, acetone or dichloromethane.

[0023] Beneficial technical effects:

[0024] The application provides a metal organic framework material, which can load a pesticide active ingredient under the action of a loading solvent to obtain a nano herbicide. The nano herbicide provided by the application has a dispersion scale of nanometer level, reaches 100-200 nm, and has good controlled release performance; the small scale effect can improve the absorption and transmission performance of the herbicide in the target crop, enhance the inhibition of the herbicide on the growth of weeds, improve the dispersibility of the pesticide, and increase the deposition rate of the pesticide on the leaves of the target crop, so that the off-target or loss of the pesticide due to the large particle size is avoided, and the effective utilization rate of the pesticide is improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Scanning electron microscope image of the 2,4-D nano-herbicide prepared in Example 1;

[0026] Figure 2 Scanning electron microscope image of the 2,4-D nano-herbicide prepared in Example 2;

[0027] Figure 3 Scanning electron microscope image of the 2,4-D nano-herbicide prepared in Example 3;

[0028] Figure 4 Scanning electron microscope image of the 2,4-D nano-herbicide prepared in Example 4;

[0029] Figure 5 Cumulative release rate of 2,4-D nano-herbicide and 2,4-D technical material in Example 5. DETAILED DESCRIPTION

[0030] The application provides a preparation method of a metal organic framework material, comprising the following steps:

[0031] Mixing a soluble zinc salt with a first solvent to obtain a zinc salt solution;

[0032] Mixing 2-methyl imidazole with a second solvent to obtain a 2-methyl imidazole solution;

[0033] Under stirring, drop the 2-methyl imidazole solution into the zinc salt solution to perform a coordination bonding reaction, to obtain a reaction liquid;

[0034] Centrifuging the reaction liquid, and sequentially washing and drying the obtained precipitate, to obtain the metal organic framework.

[0035] The application mixes a soluble zinc salt with a first solvent to obtain a zinc salt solution.

[0036] In the application, the soluble zinc salt preferably comprises at least one of zinc nitrate, zinc sulfate and zinc acetate, and more preferably is zinc nitrate; the first solvent preferably is methanol, ethanol or water, and more preferably is methanol; the mass fraction of zinc element in the zinc salt solution is preferably 1-1.5%, and more preferably is 1.2-1.3%; the mixing preferably adopts ultrasonic mixing, and the application does not have special limitation on the specific method of ultrasonic mixing, and the soluble zinc salt can be dissolved.

[0037] The application mixes 2-methyl imidazole with a second solvent to obtain a 2-methyl imidazole solution.

[0038] In the present application, the second solvent is preferably consistent with the first solvent; the mass fraction of 2-methylimidazole in the 2-methylimidazole solution is preferably 10-20%, more preferably 12-15%; the mixing is preferably ultrasonic mixing, and the present application does not have special limitations on the specific method of ultrasonic mixing, which can only dissolve the soluble zinc salt.

[0039] After obtaining the zinc salt solution and the 2-methylimidazole solution, the present application drops the 2-methylimidazole solution into the zinc salt solution under stirring to perform a coordination bonding reaction, thereby obtaining a reaction liquid.

[0040] In the present application, the volume ratio of the 2-methylimidazole solution to the zinc salt solution is preferably 1:1, the stirring rate is preferably 800-1200 r / min, the stirring time is preferably 4-10 h, and the stirring method is preferably magnetic stirring; the dropping is preferably dropwise adding.

[0041] After obtaining the reaction liquid, the present application performs centrifugation on the reaction liquid, and sequentially performs washing and drying on the obtained precipitate, thereby obtaining a metal organic framework.

[0042] In the present application, the centrifugation rate is preferably 5000-10000 rpm, more preferably 8000-9000 rpm; the centrifugation time is preferably 3-10 min, more preferably 5-8 min; the washing is preferably sequentially using methanol and water, the number of times of the methanol and water washing is independently preferably 1-5 times, more preferably 2-3 times; the drying temperature is preferably 60-80℃, more preferably 70-75℃; and the drying time is preferably 6-24 h, more preferably 10-20 h, most preferably 15 h.

[0043] The present application also provides a metal organic framework material prepared by the above preparation method.

[0044] In the present application, the metal organic framework material is a crystal composition with a regular hexahedron structure, and the particle size of the crystal is preferably 100-200 nm, more preferably 110-130 nm.

[0045] The present application also provides a nano herbicide, which comprises the metal organic framework material and a herbicide raw material, the herbicide raw material is loaded on the metal framework material, the drug loading rate of the metal organic framework material is 5-60%, and the particle size of the herbicide is 100-200 nm.

[0046] In the present application, the drug loading rate of the metal organic framework material is preferably 40-60%, more preferably 45-55%; the particle size of the herbicide is preferably 120-180 nm, more preferably 130-140 nm.

[0047] In the present application, the herbicide raw drug preferably includes at least one of 2,4-D, mesotrione and cyhalofop-butyl, more preferably 2,4-D.

[0048] The present application also provides a preparation method of the above-mentioned herbicide, comprising the following steps:

[0049] Mixing the herbicide raw drug, the metal organic framework material and the loading solvent to obtain a mixture;

[0050] Stirring and centrifuging the mixture in sequence to obtain a precipitate;

[0051] Drying the precipitate to obtain a nano-herbicide.

[0052] The present application mixes the herbicide raw drug, the metal organic framework material and the loading solvent to obtain a mixture.

[0053] In the present application, the mass ratio of the herbicide raw drug and the metal organic framework material is preferably (0.5-3):1, more preferably (1-2):1.

[0054] In the present application, the loading solvent preferably includes methanol, acetonitrile, acetone or dichloromethane; further, when the raw drug is 2,4-D, the loading solvent is preferably methanol; when the raw drug is mesotrione, the loading solvent is preferably acetonitrile.

[0055] In the present application, the mass concentration of the herbicide raw drug in the mixture is preferably 15-90 g / L, more preferably 30-80 g / L, most preferably 50-70 g / L.

[0056] The present application preferably mixes the herbicide raw drug and the metal organic framework material first and then mixes with the loading solvent. The present application does not have special limitation on the mixing method, which can only mix the raw materials uniformly.

[0057] After obtaining the mixture, the present application stirs and centrifuges the mixture in sequence to obtain a precipitate;

[0058] In the present application, the stirring time is preferably 4-12 h, more preferably 6-8 h; the centrifugation rate is preferably 8000-15000 rpm, more preferably 10000-13000 rpm; the centrifugation time is preferably 3-10 min, more preferably 5-7 min.

[0059] After obtaining the precipitated product, the present application dries the precipitate to obtain a nano-herbicide.

[0060] In the present application, the drying temperature is preferably 60-80°C, more preferably 70-75°C; the drying time is preferably 4-12h, more preferably 8-10h.

[0061] In order to better understand the present application, the following examples further illustrate the content of the present application, but the content of the present application is not limited to the following examples.

[0062] In the following examples, the raw materials and reagents involved include:

[0063] 2-methylimidazole: Mcclin, content: 98%, M813135-500g Lot: C13436475.

[0064] Zinc nitrate hydrate: aladdin, content 98%, Z190758-500g Lot: E1828053.

[0065] Methanol: Tianjin Zhiyuan Chemical Reagent Co., Ltd., content 99.5%, production batch number: 20220101508.

[0066] Example 1

[0067] 1) Take 378.8mg of zinc nitrate, add 11.214g of methanol, and ultrasonically dissolve to obtain a zinc nitrate solution

[0068] 2) Take 1.9704g of 2-methylimidazole, add 11.214g of methanol, and ultrasonically dissolve to obtain a 2-methylimidazole solution;

[0069] 3) Under the magnetic stirring at a stirring rate of 1200r / min, the 2-methylimidazole solution is added dropwise into the zinc nitrate solution, and stirred for 10h to obtain a reaction solution;

[0070] 4) The reaction solution is centrifuged at a centrifugal rate of 10000rpm for 5min, the precipitate is collected, the precipitate is washed with methanol and ultrapure water for 3 times respectively, dried in an oven at 60°C for 12h, ground into a solid powder with a mortar, and a metal-organic framework material is formed;

[0071] 5) Take 100mg of the metal-organic framework material and 100mg of 2,4-D technical material, place them in a 10mL centrifuge tube, add 5mL of methanol as a loading solvent, seal the centrifuge tube, stir at a stirring rate of 1200r / min at room temperature for 8h, centrifuge at a centrifugal rate of 10000rpm for 10min, discard the supernatant, collect the precipitate, and dry in an oven at 60°C to obtain a 2,4-D nano-herbicide.

[0072] About 0.015 g of the nano-herbicide sample was weighed into a 25 ml volumetric flask, dissolved in methanol, and allowed to release the herbicide after ultrasonic treatment for 4 h, and then diluted to the mark with methanol. The mass concentration of the herbicide in the methanol solution was determined by high performance liquid chromatography (HPLC).

[0073] The HPLC detection conditions were as follows: ZORBAX SB-C18 stainless steel chromatographic column (4.6 mm x 250 mm, 5 μm), mobile phase V(methanol):V(0.1% phosphoric acid water)=70:30, flow rate 1.0 mL / min, detection wavelength 225 nm, injection volume 10 μL, and column temperature 25 °C.

[0074] The content of the raw material drug in 0.015 g of the herbicide was 0.006756 g by the above method detection method, and the drug loading rate was 45.01% calculated according to the following formula:

[0075] Drug loading rate (%)=(mass of herbicide active ingredient in nano-herbicide / total mass of nano-herbicide)*100%

[0076] As shown in Table 1, the size of the 2,4-D nano-herbicide prepared in Example 1 was about 100-150 nm. Figure 1

[0077] Example 2

[0078] 1) 378.8 mg of zinc nitrate was weighed, added to 11.214 g of methanol, and ultrasonically dissolved to obtain a zinc nitrate solution;

[0079] 2) 1.3136 g of 2-methylimidazole was weighed, added to 11.214 g of methanol, and ultrasonically dissolved to obtain a 2-methylimidazole solution;

[0080] 3) The 2-methylimidazole solution was added dropwise to the zinc nitrate solution under magnetic stirring at a stirring rate of 1200 r / min, and stirred for 10 h to obtain a reaction solution;

[0081] 4) The reaction solution was centrifuged at 10000 rpm for 5 min, and the precipitate was collected. The precipitate was washed with methanol and ultrapure water three times, and dried in an oven at 60 °C for 12 h. After grinding, a metal-organic framework material was obtained.

[0082] 5) 100 mg of the metal-organic framework material and 100 mg of 2,4-D technical material were placed in a 10 mL centrifuge tube, 5 mL of methanol was added as a loading solvent, the centrifuge tube was sealed, and stirred at 1200 r / min at room temperature for 8 h. The supernatant was discarded after centrifugation at 10000 rpm for 10 min, and the precipitate was collected and dried in an oven at 60 °C to obtain a 2,4-D nano-herbicide. The drug loading rate was 50.67% measured according to the method of Example 1.​

[0083] As shown in Figure 2 Example 2, the 2,4-D nano-herbicide prepared has a size of about 150-200 nm.

[0084] Example 3

[0085] 1) 378.8 mg of zinc nitrate was weighed and added to 11.214 g of methanol, and ultrasonic dissolution was performed to obtain a zinc nitrate solution;

[0086] 2) 1.642 g of 2-methylimidazole was weighed and added to 11.214 g of methanol, and ultrasonic dissolution was performed to obtain a 2-methylimidazole solution;

[0087] 3) The 2-methylimidazole solution was added dropwise to the zinc nitrate solution under magnetic stirring at a stirring rate of 1200 r / min, and stirring was performed for 10 h to obtain a reaction solution;

[0088] 4) The reaction solution was centrifuged at a centrifugal rate of 10000 rpm for 5 min, the precipitate was collected, the precipitate was washed with methanol and ultrapure water three times, and drying was performed in an oven at 60°C for 12 h, and after grinding, a metal-organic framework material was obtained.

[0089] 5) 100 mg of the metal-organic framework material and 100 mg of 2,4-D technical material were placed in a 10 mL centrifuge tube, 5 mL of methanol was added as a loading solvent, the centrifuge tube was sealed, and stirring was performed at a stirring rate of 1200 r / min at room temperature for 8 h. Centrifugation was performed at 10000 rpm for 10 min, the supernatant was discarded, and the precipitate was collected and dried in an oven at 60°C to obtain 2,4-D nano-herbicide, and the drug loading rate was 46.77% as measured according to the method of Example 1.

[0090] As shown in Figure 4 , the 2,4-D nano-herbicide prepared by the method of the application has a size of about 120-200 nm.

[0091] Example 4

[0092] 1) 378.8 mg of zinc nitrate was weighed and added to 11.214 g of methanol, and ultrasonic dissolution was performed to obtain a zinc nitrate solution;

[0093] 2) 2.6272 g of 2-methylimidazole was weighed and added to 11.214 g of methanol, and ultrasonic dissolution was performed to obtain a 2-methylimidazole solution;

[0094] 3) The 2-methylimidazole solution was added dropwise to the zinc nitrate solution under magnetic stirring at a stirring rate of 1200 r / min, and stirring was performed for 10 h to obtain a reaction solution;

[0095] 4) centrifuge the reaction solution at a centrifugal rate of 10000 rpm for 5 min, collect the precipitate, wash the precipitate with methanol and ultrapure water for 3 times respectively, dry in an oven at 60°C for 12 h, and obtain the metal-organic framework material after grinding.

[0096] 5) weigh 100 mg of the metal-organic framework material and 100 mg of 2,4-D technical material into a 10 mL centrifuge tube, add 5 mL of methanol as the loading solvent, seal the centrifuge tube, stir at a stirring rate of 1200 r / min at room temperature for 8 h, centrifuge at a centrifugal rate of 10000 rpm for 10 min, discard the supernatant, collect the precipitate, and dry in an oven at 60°C to obtain 2,4-D nanoweedicide, and the drug loading rate is 50.34% as measured according to the method of Example 1.

[0097] As shown in FIG. 2, the 2,4-D nanoweedicide prepared in Example 2 has a size of about 150-200 nm. Figure 4

[0098] Example 5

[0099] Effect of different types of herbicides on drug loading rate

[0100] Change the type of herbicide in Example 1, and measure the drug loading rate of the product obtained after centrifugation and drying, and the results are shown in Table 1.

[0101] Table 1 Effect of different types of herbicides on drug loading rate of nanoweedicide

[0102] Prodrugs Drug loading Mesotrione 6.94％ 2,4-D 45.01％ Cyhalofop-butyl 15.26％

[0103] As can be seen from Table 1, the drug loading rates of different types of herbicides are different, and mesotrione, 2,4-D, and cyhalofop-butyl have different chemical structures and properties. Among them, 2,4-D has the best drug loading effect, which indicates that the drug loading effect is related to the chemical structure, physicochemical properties, etc. of the herbicide itself.

[0104] Example 6

[0105] Effect of different zinc sources on drug loading rate of nanoweedicide

[0106] Change the type of zinc source in Example 1, and prepare 2,4-D nanoweedicide respectively, and measure the drug loading rate of the product obtained after centrifugation and drying, and the results are shown in Table 2.

[0107] Table 2 Effect of different zinc sources on drug loading rate of 2,4-D nanoweedicide

[0108] Zinc source Drug loading Zinc sulfate 48.58％ Zinc nitrate 45.01％ Zinc acetate 49.38％

[0109] ​The results show that different zinc sources have different drug loading rates for 2,4-D nano-herbicide, but the difference is not significant, among which the drug loading effect of zinc acetate is the best, indicating that zinc sulfate, zinc nitrate and zinc acetate can be used for the preparation of nano-herbicide.

[0110] Example 7

[0111] Effect of different loading solvents on drug loading rate of nano-herbicide

[0112] In Example 1, the type of loading solvent was changed, and nitrosulfuron and 2,4-D were loaded respectively to prepare nitrosulfuron nano-herbicide and 2,4-D nano-herbicide. The drug loading rate of the product obtained after centrifugation and drying was determined, and the results are shown in Table 3.

[0113] Table 3 Effect of different loading solvents on drug loading rate of nano-herbicide

[0114]

[0115] The results show that due to the different solvent properties of different herbicides in the loading solvent, the drug loading rate of nano-herbicide has certain difference with the change of the loading solvent. For nitrosulfuron nano-herbicide, acetonitrile as the loading solvent can obtain the best drug loading rate, and methanol as the loading solvent has the worst drug loading rate. For 2,4-D, methanol as the loading solvent has the highest drug loading rate, and acetone as the loading solvent has the lowest drug loading rate. Therefore, according to the different properties of herbicides, a suitable solvent should be selected as the loading solvent.

[0116] Example 8

[0117] Release performance test

[0118] A release medium solution was prepared, in which the volume ratio of ethanol, water and Tween-80 was 60:40:0.1. 25 mg of active ingredient of 2,4-D nano-herbicide and 2,4-D technical material in Example 1 were weighed and respectively placed in a volume of 200 mL release medium solution in a constant temperature shaking reactor, and released at 30±1℃ and 150 rpm shaking. Every certain time, 1 mL was sampled and passed through a 0.22 μm water filter membrane, and the content of 2,4-D was detected by high performance liquid chromatograph. After each sampling, 1 mL of release medium solution was added, and the cumulative release rate was calculated according to the following formula.

[0119]

[0120] In the formula:

[0121] Q - cumulative release rate, expressed in %;

[0122] V0 - total volume of dissolution medium (200 mL);

[0123] C T - the mass concentration of the active ingredient in the dissolution medium at the point of release, in milligrams per milliliter (mg / mL);

[0124] V - the volume of each sample (1 mL);

[0125] W - the total mass of the active ingredient in the system (25 mg).

[0126] Figure 5 The cumulative release rate of 2,4-D nanoscale herbicide and 2,4-D technical material. Under the same release conditions, the cumulative release rate of 2,4-D technical material reached more than 88% after 19 h; while the release of 2,4-D nanoscale herbicide was slower, the cumulative release rate was not more than 20% in the first 5 h, and reached more than 80% after 82 h. The results show that the nanoscale herbicide has a good controlled release effect on the active ingredient.

[0127] Example 9

[0128] Effect on the growth of barnyard grass:

[0129] The 2,4-D nanoscale herbicide in Example 1 was used to treat the roots of barnyard grass seedlings, and the treatment concentrations of 2,4-D active ingredient were 100, 200, and 600 mg / L, respectively. At the same time, 2,4-D technical material of the corresponding concentration and a blank control were carried out. During the treatment process, the evaporation of water was replenished every day to keep the total volume of water unchanged. After 7 days, the samples were collected, and the fresh weight of barnyard grass seedlings was measured. The results are shown in Table 4. Compared with the blank group, the fresh weight of barnyard grass seedlings treated with 2,4-D technical material and 2,4-D nanoscale herbicide decreased, and both had good effects on inhibiting the growth of weeds. After treatment with 2,4-D nanoscale herbicide, the inhibition effect on the growth of barnyard grass was more significant compared with the 2,4-D technical material treatment group, indicating that the nanoscale herbicide can enhance the herbicidal effect of the active ingredient to some extent.

[0130] Table 4 Inhibition of different formulations on the growth of barnyard grass

[0131]

[0132]

[0133] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A nanoherbicide, characterized in that, The metal organic framework material and the herbicide raw material are loaded on the metal organic framework material, the drug loading rate of the metal organic framework material is 27.51-60%, and the particle size of the herbicide is 100-200 nm. The preparation method of the metal organic framework material comprises the following steps: a soluble zinc salt is mixed with a first solvent to obtain a zinc salt solution; 2-methyl imidazole is mixed with a second solvent to obtain a 2-methyl imidazole solution; The 2-methyl imidazole solution is dropped into the zinc salt solution under stirring to perform a coordination bonding reaction, and a reaction liquid is obtained; The reaction liquid is centrifuged, and the obtained precipitate is sequentially washed and dried to obtain a metal organic framework; The soluble zinc salt comprises at least one of zinc nitrate, zinc sulfate and zinc acetate; the first solvent comprises methanol, ethanol or water; and the second solvent is consistent with the first solvent; The mass fraction of zinc in the zinc salt solution is 1-1.5%, and the mass fraction of 2-methyl imidazole in the 2-methyl imidazole solution is 10-20%; The volume ratio of the 2-methyl imidazole solution to the zinc salt solution is 1:1; The metal framework material is composed of a crystal with a regular hexahedron structure, and the particle size of the crystal is 100-200 nm; The preparation method of the herbicide comprises the following steps: The herbicide raw material, the metal organic framework material and a loading solvent are mixed to obtain a mixture; The mixture is sequentially stirred and centrifuged to obtain a precipitate; The precipitate is dried to obtain a nano herbicide; The herbicide raw material is 2,4-D; The mass ratio of the herbicide raw material to the metal organic framework material is (0.5-3):

1.

2. The nano-herbicide according to claim 1, wherein, The loading solvent comprises methanol, ethanol or acetone.

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