Magnetic control attapulgite-based pesticide and preparation method thereof

Abstract

The invention provides a magnetic control attapulgite-based pesticide and a preparation method thereof. The preparation method comprises the following steps: S1, preparing Fe3O4-coated attapulgite by adopting a coprecipitation method; s2, loading the pesticide imidacloprid by taking the Fe3O4-coated attapulgite as a carrier to obtain pesticide-loaded attapulgite; and S3, coating the attapulgite loaded with the pesticide by using PVP (Polyvinyl Pyrrolidone) to obtain the magnetic control attapulgite-based pesticide. Fe3O4 in the pesticide can vibrate under different electromagnetic fields (VEFs) to promote release of the pesticide, so that the obtained pesticide has good alternating magnetic field response controlled release performance.

Description

Technical Field

[0001] The present invention relates to the technical field of agriculture, and particularly relates to a magnetically controlled attapulgite-based pesticide and a preparation method thereof. Background Art

[0002] Pesticides can effectively prevent and control diseases, insects and weeds in agricultural production, and play an important role in improving the quality and yield of food. However, traditional pesticides are easily affected by environmental factors during spraying, resulting in behaviors such as volatilization, degradation and runoff, and thus are lost into the atmosphere, water body and soil environment. This not only causes pesticide pollution, but also ultimately endangers people's physical health through the enrichment effect of the food chain. At the same time, China has timely put forward the plan to achieve zero growth in pesticide use to conform to the development of modern society.

[0003] Compared with traditional pesticides, controlled-release pesticides (CRPs) have become a huge development trend due to their advantages such as small loss, high utilization efficiency and little environmental impact. So far, a large number of CRPs responsive to pH, ionic strength, light and temperature have been developed, such as calcium alginate, chitosan, CuS, biochar, etc. [Xiang, Y.; Lu, X.; Yue, J.; Zhang, Y.; Sun, X.; Zhang, G.; Cai, D.; Wu, Z. Stimuli-responsive hydrogel as carrier for controlling the release and leaching behavior of hydrophilic pesticide. Sci. Total Environ. 2020, 722, No. 137811; Xiang, Y.; Zhang, G.; Chi, Y.; Cai, D.; Wu, Z. Fabrication of a controllable nanopesticide system with magnetic collectability. Chem. Eng. J. 2017, 328, 320 - 330; Zhang, H.; Zhu, C.; Chen, Y.; Gao, H. Growth of Fe 3 O 4Nanorod Arrays on Graphene Sheets for Application in Electromagnetic Absorption Fields. ChemPhysChem 2014, 15, 2261 - 2266.]. However, these systems have some limitations in practical applications: (1) pH and ionic strength response systems may affect non-target organisms due to the addition of bases, ions, or acids; (2) photo-thermal response systems have high energy consumption and complex technological processes. Therefore, it is necessary to develop a simple CRP with good environmental compatibility. Magnetic response controlled release platforms have been widely studied for electromagnetic adsorption, biosensors, magnetic resonance imaging (MRI), etc. due to their ease of use and good biocompatibility [Zhou, Z.; Zhang, Y.; Guo, M.; Huang, K.; Xu, W. Ultrasensitive magnetic DNAzyme-copper nanoclusters fluorescent biosensor with triple amplification for the visual detection of E. coli O157:H7. Biosens. Bioelectron. 2020, 167, No. 112475; Chao, Y.; Chen, G.; Liang, C.; Xu, J.; Dong, Z.; Han, X.; Wang, C.; Liu, Z. Iron Nanoparticles for Low-Power Local Magnetic Hyperthermia in Combination with Immune Checkpoint Blockade for Systemic Antitumor Therapy. Nano Lett. 2019, 19, 4287 - 4296.]. Recent studies have shown that nanocomposites of mesoporous silica-modified iron oxide combined with poly(n-isopropylacrylamide) (PNIPAm) collapse due to the heat mediation of iron oxide under the action of an alternating magnetic field (AMF), resulting in drug release. In addition, under the action of a magnetic field, magnetic MSN / graphene quantum dots exhibit thermal release at high temperatures, which is beneficial to the release of doxorubicin [Wang, Y.; Kohane, D. S. External triggering and triggered targeting strategies for drug delivery. Nat. Rev. Mater. 2017, 2, No. 17020.].Mai et al. reported the use of a photoinduced copper-mediated radical polymerization method to obtain thermoresponsive iron oxide nanocubes, which would be beneficial for heat-mediated chemotherapy [Mai, B.T.; Balakrishnan, P.B.; Barthel, M.J.; Piccardi, F.; Niculaes, D.; Marinaro, F.; Fernandes, S.; Curcio, A.; Kakwere, H.; Autret, G.; Cingolani, R.; Gazeau, F.; Pellegrino, T. Thermoresponsive iron oxide nanocubes for an effective clinical translation of magnetic hyperthermia and heat-mediated chemotherapy. ACS Appl. Mater. Interfaces 2019, 11, 5727-5739.].

[0004] As the most widely used inorganic nanomaterial in the field of polymer-based nanocomposites, clay has the advantages of high porosity and large specific surface area. Attapulgite (ATP) is a natural hydrated aluminum magnesium silicate with a unique fibrous structure. In addition, ATP has the advantages of low cost, large reserves, environmental friendliness, etc., and is widely used in research fields such as water treatment, pigments, sensors, and carriers.

[0005] The Chinese patent application document with the publication number CN106268812A discloses a nano-magnetic environmental remediation material of iron tetroxide loaded on attapulgite for removing organic pollutants and its preparation method. Based on the fact that attapulgite has a huge specific surface area and excellent adsorption properties, and has a strong degradation and removal ability for organic pollutants and heavy metals, attapulgite is combined with a material with catalase activity, which can further improve the catalytic ability of the heterogeneous Fenton reaction. Since Fe 3 O 4 has magnetic properties, loading it on attapulgite can prepare a new type of environmental remediation material that is easy to recycle and reusable for removing organic pollutants in the environment, but it does not disclose its use in the field of pesticide slow release. 3 O 4 Summary of the Invention

[0006] The technical problem to be solved by the present invention is how to prepare a slow-release pesticide.

[0007] The present invention solves the above technical problem by the following technical means:

[0008] ​A preparation method of a magnetically controlled attapulgite-based pesticide, comprising the following steps:

[0009] S1. Prepare Fe 3 O 4 -coated attapulgite;

[0010] S2. Use the Fe 3 O 4 -coated attapulgite as a carrier to load the pesticide imidacloprid to obtain attapulgite loaded with the pesticide;

[0011] S3. Use PVP to coat the attapulgite loaded with the pesticide to obtain the magnetically controlled attapulgite-based pesticide.

[0012] Preferably, in S1, the raw materials for coprecipitation include ferric salts and ferrous salts; the molar ratio of Fe 3+ and Fe 2+ in the ferric salts and ferrous salts is 2:1.

[0013] Preferably, the ferric salt is ferric chloride and the ferrous salt is ferrous sulfate.

[0014] Beneficial effects: During the coprecipitation process, the binder PEG is added, which will make the magnetite adhere more evenly to the attapulgite.

[0015] Preferably, S1 specifically includes the following steps: Under a nitrogen atmosphere, uniformly mix the attapulgite aqueous solution with PEG, add the ferric salt and then heat and stir, add the ferrous salt and stir, then add ammonia water, stir and react, cool to room temperature, separate with a magnet and then wash, and dry to obtain Fe 3 O 4 -coated attapulgite.

[0016] Preferably, the dosage ratio of the attapulgite, ferric salt, and ferrous salt is 0.1 g: 0.4 mmol: 0.2 mmol; the dosage ratio of the attapulgite and PEG is 0.1 g: 100 - 500 μL.

[0017] Preferably, the dosage ratio of the attapulgite and PEG is 0.1 g: 500 μL.

[0018] Preferably, the dosage ratio of the attapulgite and ammonia water is 0.1 g: 4 - 8 mL.

[0019] Preferably, in S2, mix the Fe 3 O 4 -coated attapulgite, the pesticide imidacloprid, and a solvent, and treat in a shaker to obtain attapulgite loaded with the pesticide.

[0020] Preferably, in S2, the Fe 3 O4 The mass ratio of the coated attapulgite to the pesticide imidacloprid is 5 - 8:8.

[0021] Preferably, in S2, the Fe 3 O 4 The mass ratio of the coated attapulgite to the pesticide imidacloprid is 5:8.

[0022] Preferably, in S3, the attapulgite loaded with pesticide and the PVP solution are mixed and then treated in a shaker for coating to obtain the magnetically controlled attapulgite-based pesticide.

[0023] Preferably, in S3, the mass ratio of the attapulgite loaded with pesticide to PVP is 1:2.

[0024] The present invention also provides a magnetically controlled attapulgite-based pesticide, which is prepared by using the preparation method of the magnetically controlled attapulgite-based pesticide.

[0025] The pesticide of the present invention is a simple, stable and highly biosafe alternating magnetic field-responsive controlled-release pesticide. The Fe 3 O 4 can vibrate under different VEFs to promote the release of the pesticide. It can reduce the harm of imidacloprid pesticide to human health and the ecosystem caused by improper spraying and leaching. At the same time, the selected materials have high biosafety and are not likely to have a negative impact on crop growth, showing potential practical application value.

[0026] The drug loading capacity of the controlled-release system of the present invention for the pesticide is 16%. Compared with traditional pesticides, this pesticide shows higher leaf adhesion and can be reused at least three times. In addition, the carrier has no toxic effect on non-target crops and animals in the environment and has good biosafety.

[0027] The pesticide of the present invention has the advantages of ① simple process, ② high stability, ③ high biosafety, etc. Compared with traditional pesticides, it can significantly improve the adhesion ability to leaves, providing a new way to reduce pesticide loss and improve pesticide utilization efficiency. It has high industrialization prospects and also has practical reference value for the future development of green agriculture.

[0028] The present invention is based on the research and development of a new pesticide formulation, that is, an environment-responsive controlled-release pesticide, which stimulates the release of the pesticide active ingredient in the carrier through environmental factors related to the occurrence of pests, diseases and weeds to transfer to the target surface and maintain a predetermined concentration level within a specific time period, realizing the precise targeted release of the pesticide, thereby improving the utilization efficiency of the pesticide and reducing environmental pollution. This system has good practical value in the sustainable control of pests and green agriculture.

[0029] This method synthesizes attapulgite (ATP) and Fe by a simple co-precipitation method3 O 4 The magnetic nanocomposite (ATP@Fe 3 O 4 ) composed of attapulgite and iron oxide was synthesized. Using the non-ionic surfactant polyethylene glycol (PEG), one-dimensional magnetic nanorods with attapulgite as the core and Fe 3 O 4 as a uniform shell were fabricated. The ATP@Fe 3 O 4 nanocomposite was used as a carrier for imidacloprid (IM) pesticide, and then coated with PVP to obtain a magnetically controlled nano-pesticide. The Fe 3 O 4 in the magnetic nanoparticles can vibrate under different electromagnetic fields (VEFs) to promote the release of the pesticide. Therefore, by designing the frequency and voltage, the resulting pesticide can have good alternating magnetic field (AFM) response-controlled release performance. After release, the presence of Fe 3 O 4 nanoparticles is beneficial for collecting the pesticide from water and can be reused at least three times. From the perspective of biosafety, ATP@Fe 3 O 4 has good biocompatibility and has little impact on zebrafish in the absence of VEFs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Scanning electron microscopy images of attapulgite ATP (A) and magnetic attapulgite ATP@Fe 3 O 4 (B) in Example 1 of the present invention, and transmission electron microscopy image of AFe@IM@PVP (C);

[0031] Figure 2 Infrared spectra of attapulgite ATP (a) and magnetic attapulgite ATP@Fe 3 O 4 (b) and AFe@IM@PVP (c) in Example 1 of the present invention;

[0032] Figure 3 Digital photos of the survival rate of zebrafish in Example 1 of the present invention; among them, the concentrations of AFe@PVP from left to right in the figure are 0, 20, 40, 80, 160 μg / mL;

[0033] Figure 4 Plant height of soybean seedlings treated with AFe@IM@PVP for 15 days in Example 1 of the present invention;

[0034] Figure 5 Contact angles of AFe@IM@PVP under different leaves in Example 1 of the present invention; where a. H 2O, b.IM, c.AFe@IM@PVP;

[0035] Figure 6 Experimental diagram for the reuse of AFe@IM@PVP;

[0036] Figure 7 Effect diagram of the control of pests by AFe@IM@PVP prepared in Example 1 under an alternating magnetic field;

[0037] Figure 8 Magnetron technology diagram in an actual application scenario. Detailed implementation manners

[0038] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] The test materials and reagents used in the following embodiments can be obtained from commercial channels without special instructions.

[0040] For those not specifying specific technologies or conditions in the embodiments, they can all be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications.

[0041] Example 1

[0042] A preparation method of a magnetron attapulgite-based pesticide, comprising:

[0043] 1) Preparation of ATP@Fe 3 O 4 : First, dissolve 0.1 g of ATP in 100 mL of an aqueous solution. The scanning electron micrograph of the used ATP is as shown in Figure A in Figure 1 . Then add a PEG (500 μL) solution and stir evenly. Add 0.4 mmol of FeCl 3 ·6H 2 O, heat to 60 °C, stir at 400 rpm for 30 min, and then add 0.2 mmol of FeSO 4 ·7H 2 O (maintaining the molar ratio of Fe 3+ and Fe 2+ at 2:1), stir for 5 min and then inject 8 mL of NH 3 ·H 2O, stir for 20 min. The whole synthesis process is carried out under a gentle nitrogen stream. After the reaction is completed, the mixture is cooled to room temperature, separated by a magnet, washed 3 times alternately with ethanol / water, and dried in a vacuum drying oven at 60 °C to obtain ATP@Fe 3 O 4 , and its scanning electron micrograph is as shown in Figure 1 Figure B therein; It can be seen from Figure B that magnetite is evenly anchored on attapulgite.

[0044] 2) Preparation of AFe@IM@PVP: Add ATP@Fe 3 O 4 (50 mg) and IM (80 mg) into 20 mL of deionized water, and treat in a shaker at 120 rpm for 24 h. The obtained mixture is centrifuged (12 000 rpm) for 5 minutes, washed with water, and dried at 60 °C to obtain AFe@IM. Add 50 mg of AFe@IM into 20 mL of PVP (5 mg / mL) solution, treat in a shaker at 100 rpm for 15 min, then centrifuge (10 000 rpm, 5 min), and dry (60 °C) to obtain the magnetically controlled attapulgite-based pesticide AFe@IM@PVP, and its transmission electron micrograph is as shown in Figure 1 Figure C. The infrared spectrum is as shown in Figure 2 , proving that ATP@Fe 3 O 4 successfully loaded with the drug IM. The drug loading amount is measured to be 16% by using an ultraviolet spectrophotometer.

[0045] Pest control experiment: Study the control effect of AFe@IM@PVP on the 3rd instar diamondback moth. First, place a filter paper in a petri dish with a diameter of 10 cm, place fresh Chinese cabbage leaves on the filter paper, and spray the suspension aqueous solution containing IM (5 mg, 5 mL) or AFe@IM@PVP (32 mg (the content of IM in 32 mg is 5 mg), 5 mL) on the fresh Chinese cabbage leaves. Place the above system under VEFs of 40 V and 1 Hz for 24 h. Subsequently, place the 3rd instar larvae of diamondback moth (n = 12) on each Chinese cabbage leaf, and count the number of deaths at different time intervals to determine the mortality rate. In addition, a control experiment was also carried out on the 3rd instar larvae of diamondback moth with 5.0 mL of aqueous solution. All experiments were carried out in triplicate, and the results are as shown in Figure 7 , and the lethal rate of AFe@IM@PVP to diamondback moth within 24 h is 83.3%.

[0046] To evaluate the magnetically controlled nano-pesticide prepared by the method of the present invention, its release behavior was studied, the biosafety of the material was detected with zebrafish and soybean seedlings, and its magnetic recovery property and leaf adhesion property were studied.

[0047] 1) IM release rate determination: The release of AFe@IM@PVP (20 mg) in 20 mL of deionized water under square-wave alternating current with different frequencies and voltages was studied. At regular intervals, 1.0 mL of the homogenized suspension was taken as a sample, centrifuged, and analyzed by ultraviolet spectrophotometer. At the same time, the obtained precipitate was resuspended in 1 mL of aqueous solution and reintroduced into the original suspension to ensure consistency. The release results are shown in Tables 1 and 2. As can be seen from Tables 1 and 2, the cumulative release rate of AFe@IM@PVP reached 79% at a voltage of 40 V and a frequency of 1 Hz for 12 h. In an actual scenario, an electromagnet can be used as an electrical appliance like a lamp and controlled in series through a switch. In particular, a circuit containing an electromagnet can be installed in a highly controllable pulley system (such as Figure 8 ). Considering the distribution of magnetic induction intensity and the height of crops, in order to capture the entire crop and maintain control efficiency, the circuit should be placed multiple times at certain positions. Raw materials such as ATP, Fe 3 O 4 etc. have been proven to be inexpensive, and the materials can be simply recycled using magnets. This system has certain practical application value.

[0048] 2) Biosafety experiment: The purchased zebrafish larvae were cultured at room temperature for one week, and the naturally dead zebrafish were removed. Then, 10 zebrafish larvae were placed in a group in 150 mL of AFe@PVP suspension with different doses. After 7 days, the surviving zebrafish were counted to determine their survival rate. As shown in Table 3 and Figure 3 , the survival rate of the 5 groups of zebrafish was 100%.

[0049] In addition, the biosafety of tap water and AFe@IM@PVP suspension on soybeans was also investigated. Soybean seeds were buried in soil 7 cm deep. After the soybean seeds germinated, the AFe@IM@PVP suspension (5.2 mg / mL) and tap water were evenly sprayed on the soybean leaves. Subsequently, the soybeans were placed in an incubator at room temperature with a humidity of 70%. The plant height of the soybeans was measured after 15 days. All the experiments were repeated three times. The results are as Figure 4 shown, and there was no significant difference in plant height between the two groups.

[0050] Among them, the above-mentioned AFe@PVP was prepared by the following process: 50 mg of ATP@Fe 3 O 4 was added to 20 mL of PVP (5 mg / mL) solution, treated in a shaker at 100 rpm for 15 min, then centrifuged (10,000 rpm, 5 min), and dried (60 °C) to obtain AFe@PVP.

[0051] 3) Leaf adhesion: The wetting properties of IM and AFe@IM@PVP (5 mg, 10 mL) on hydrophilic cucumber leaves and hydrophobic cabbage leaves were tested using the contact angle. First, the leaves were carefully rinsed with deionized water. After the leaves were naturally dried, a part of the leaves was cut avoiding the veins and fixed to a glass slide with double-sided tape. IM and AFe@IM@PVP solutions were added dropwise, and the contact angle was measured. During the measurement, damage to the micro-nano structure on the leaf surface was avoided as much as possible. The results are as Figure 5 shown. Compared with the IM group, the contact angle of AFe@IM@PVP decreased significantly.

[0052] 4) Magnetic recovery property: The adsorption stability evaluation of magnetic attapulgite particles was completed by comparing the original drug loading and the drug loading after treatment. For all drug loading experiments, IM (50 mg) was taken in a centrifuge tube and dissolved in 25 mL of deionized water. 50 mg of ATP@Fe 3 O 4 was added, and the mixture was shaken and adsorbed in a shaker at 25 °C. After drying, the drug loading was measured using a UV spectrophotometer. Then, magnetic adsorption recovery was carried out using a magnet. The experimental results are as Figure 6 shown, and it can be reused at least three times.

[0053] Example 2

[0054] A preparation method of a magnetically controlled attapulgite-based pesticide, comprising:

[0055] 1) Preparation of ATP@Fe 3 O 4 : First, 0.1 g of ATP was dissolved in 100 mL of aqueous solution, and then a PEG (100 μL) solution was added and stirred evenly. 0.4 mmol of FeCl 3 ·6H 2 O was added, and the mixture was heated to 60 °C and stirred at 400 rpm for 30 min. Then, 0.2 mmol of FeSO 4 ·7H 2 O (maintaining the molar ratio of Fe 3+ and Fe 2+ at 2:1) was added and stirred for 5 min, and then 4 mL of NH 3 ·H 2 O was injected and stirred for 20 min. The whole synthesis process was carried out under a gentle nitrogen flow. After the reaction was completed, the mixture was cooled to room temperature, separated by a magnet, washed 3 times alternately with ethanol / water, and dried in a vacuum drying oven at 60 °C;

[0056] 2) Preparation of AFe@IM@PVP: ATP@Fe 3 O 4(80 mg) and IM (80 mg) were added to 20 mL of deionized water and treated in a shaker at 120 rpm for 24 h. The obtained mixture was centrifuged (12 000 rpm) for 5 minutes, washed with water, and dried at 60 °C to obtain AFe@IM. 50 mg of AFe@IM was added to 20 mL of PVP (5 mg / mL) solution and treated in a shaker at 100 rpm for 15 min, then centrifuged (10 000 rpm, 5 min) and dried (60 °C) to obtain AFe@IM@PVP, and the drug loading was measured to be 13% using a UV spectrophotometer.

[0057] Pest control experiment: To study the control effect of AFe@IM@PVP on the 3rd instar Plutella xylostella. First, a filter paper was placed in a petri dish with a diameter of 10 cm, and fresh Chinese cabbage leaves were placed on the filter paper. The suspension aqueous solution containing AFe@IM@PVP (38 mg (the content of IM in 38 mg is 5 mg), 5 mL) was sprayed on the fresh Chinese cabbage leaves. The above system was placed under VEFs of 40 V and 1 Hz for 24 hours. Subsequently, the 3rd instar larvae of Plutella xylostella (n = 12) were placed on each Chinese cabbage leaf, and the number of deaths at different time intervals was counted to determine the mortality rate. All experiments were carried out in triplicate, and the lethality rate of AFe@IM@PVP to Plutella xylostella within 24 h was 49.7%.

[0058] Comparative Example 1

[0059] 1) Preparation of ATP@Fe 3 O 4 : First, 0.1 g of ATP was dissolved in 100 mL of aqueous solution, and then PEG (500 μL) solution was added and stirred evenly. 0.4 mmol of FeCl 3 ·6H 2 O was added, heated to 60 °C, stirred at 400 rpm for 30 min, and then 0.2 mmol of FeSO 4 ·7H 2 O (maintaining the molar ratio of Fe 3+ and Fe 2+ at 2:1) was added and stirred for 5 min, and then 8 mL of NH 3 ·H 2 O was injected and stirred for 20 min. The whole synthesis process was carried out under a gentle nitrogen stream. After the reaction was completed, the mixture was cooled to room temperature, separated by a magnet, washed alternately with ethanol / water 3 times each, and dried in a vacuum drying oven at 60 °C to obtain ATP@Fe 3 O 4 ;

[0060] 2) Preparation of AFe@IM@PVP: ATP@Fe 3 O 4(50 mg) and IM (80 mg) were added to 20 mL of deionized water and treated in a shaker at 120 rpm for 24 h. The obtained mixture was centrifuged (12 000 rpm) for 5 minutes, washed with water, and dried at 60 °C to obtain AFe@IM. 50 mg of AFe@IM was added to 20 mL of PVP (5 mg / mL) solution and treated in a shaker at 100 rpm for 15 min, then centrifuged (10 000 rpm, 5 min) and dried (60 °C) to obtain AFe@IM@PVP.

[0061] 3) Pest control experiment: To study the control effect of AFe@IM@PVP on the 3rd instar diamondback moth. First, a filter paper was placed in a petri dish with a diameter of 10 cm, and fresh Chinese cabbage leaves were placed on the filter paper. The suspension aqueous solution containing AFe@IM@PVP (32 mg, 5 mL) was sprayed on the fresh Chinese cabbage leaves. Subsequently, the 3rd instar larvae of diamondback moth (n = 12) were placed on each Chinese cabbage leaf, and the number of deaths at different time intervals was counted to determine the mortality rate. All experiments were carried out in triplicate. The lethality rate of AFe@IM@PVP against diamondback moth within 24 h was 33.3%.

[0062] Table 1. Release rate of AFe@IM@PVP at 1.1 Hz frequency under different voltages

[0063]

[0064] Table 2. Release rate of AFe@IM@PVP at 40 V voltage under different frequencies

[0065]

[0066] Table 3. Survival rate of zebrafish under different conditions

[0067]

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a magnetically controlled attapulgite-based pesticide, characterized in that: The following steps are involved: S1. Preparing Fe3O4-coated attapulgite by coprecipitation method; S2, using Fe3O4-coated attapulgite as a carrier to load the pesticide imidacloprid to obtain the pesticide-loaded attapulgite; S3. The attapulgite loaded with pesticide is coated with PVP to obtain the magnetically controlled attapulgite-based pesticide.

2. The method for preparing the magnetically controlled attapulgite-based pesticide according to claim 1, characterized in that: In S1, the raw materials for coprecipitation include ferric iron salt and ferrous iron salt; Fe 3+ and Fe 2+ The molar ratio is 2:

1.

3. The method for preparing the magnetically controlled attapulgite-based pesticide according to claim 2, characterized in that: The trivalent iron salt is ferric chloride, and the divalent iron salt is ferrous sulfate.

4. The method for preparing a magnetically controlled attapulgite-based pesticide according to any one of claims 1 to 3, characterized in that: S1 specifically includes the following steps: mixing the attapulgite aqueous solution and PEG evenly under a nitrogen atmosphere, adding a trivalent iron salt and heating and stirring, adding a divalent iron salt and stirring, and then adding ammonia water, stirring and reacting, cooling to room temperature, separating with a magnet, washing, and drying to obtain Fe3O4-coated attapulgite.

5. The method for preparing the magnetically controlled attapulgite-based pesticide according to claim 4, characterized in that: The dosage ratio of the attapulgite, the trivalent iron salt and the divalent iron salt is 0.1 g: 0.4 mmol: 0.2 mmol; the dosage ratio of the attapulgite and PEG is 0.1 g: 100-500 μL.

6. The method for preparing the magnetically controlled attapulgite-based pesticide according to claim 1, characterized in that: In S2, Fe3O4-coated attapulgite, the pesticide imidacloprid, and a solvent are mixed and treated in a shaking table to obtain the pesticide-loaded attapulgite.

7. The method for preparing the magnetically controlled attapulgite-based pesticide according to claim 1, characterized in that: In S2, the mass ratio of the Fe3O4-coated attapulgite and the pesticide imidacloprid is 5-8:

8.

8. The method for preparing the magnetically controlled attapulgite-based pesticide according to claim 1, characterized in that: In S3, the attapulgite loaded with the pesticide and the PVP solution are mixed and then treated in a shaking table for coating to obtain the magnetically controlled attapulgite-based pesticide.

9. The method for preparing the magnetically controlled attapulgite-based pesticide according to claim 1, characterized in that: In S3, the mass ratio of the pesticide-loaded attapulgite and PVP is 1:

2.

10. A magnetically controlled attapulgite-based pesticide, characterized in that: The pesticide is prepared by the method for preparing the magnetically controlled attapulgite-based pesticide as described in any one of claims 1 to 9.

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