Rhymic acid-based nano-pesticide and preparation method thereof

Abstract

The invention discloses a preparation method of a ulmic acid-based nano pesticide, which comprises the following steps: (1) dissolving pesticide active ingredients in an alkaline solution to obtain a mixed solution A; (2) dissolving the ulmic acid in the mixed solution A, and continuing to supplement the sodium hydroxide solution if the ulmic acid is not dissolved; performing ultrasonic treatment for 10 to 20 minutes to obtain a mixed solution B; (3) adding a rotor into the mixed solution B, adjusting the rotating speed to 500-800rpm, dropwise adding 0.1-0.5 M of HCl into the beaker at a constant speed of 1-5mL / min for 20-60 minutes until the pH value of the solution is less than 2.0, and continuously reacting for 20-60 minutes; and (4) continuing to add a stabilizer trimethyl octadecyl ammonium bromide to enable the content of the stabilizer to be 0.5-1.5%, and continuously reacting for 0.5-2 hours to obtain the ulmic acid based nano pesticide. The ulmic acid in the ulmic acid-based nano pesticide has the effect of controlling release of active ingredients of the pesticide, the half-life period of soil can be prolonged, and the effect of the active ingredients of the pesticide is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticide preparation processing and preparation, and in particular relates to a humic acid-based nano pesticide and a preparation method thereof. Background Art

[0002] Nanopesticides use functional materials and nanotechnology to make the active ingredients of pesticides exist stably in a nanoscale dispersed state in the formulation and dispersion system, and can exert application performance different from conventional formulations when used. The development of nanopesticides can help achieve "safe, economical, and environmentally friendly" agricultural production, achieve "zero growth" in pesticide use and green prevention and control, and has been listed as the first of the "Top Ten Chemical Innovations that Will Change the World in the Future".

[0003] Humic acid is the most widely existing organic matter in nature. Its structure contains a large number of hydroxyl, carboxyl, aldehyde, and carbonyl groups. It can be tightly combined with iron ions through complexation and chelation, and has the potential to prepare pesticide microcapsule materials. However, humic acid in nature is generally mixed with soil and is difficult to purify. Palmitic acid is a brown organic mixture separated from humic acid by its solubility in alkali, ethanol, methanol, and acetone. The molecular weight is between 1000 and 10000 Daltons. Its macromolecular structure is the same as that of humic acid. It is an aromatic macromolecular organic weak acid that contains hydrophobic aromatic rings, aliphatic rings, and alkyl bridge bonds, as well as abundant hydrophilic carboxyl, hydroxyl, carbonyl, quinone, methoxy and other oxygen-containing functional groups, showing good surface activity; and has good exchange, adsorption, and complexation effects with metal ions; the palmitic acid macromolecule also contains a certain number of active groups; because of its physical and chemical structure, surface polarity and activity that are very close to graphene oxide, it can also be regarded as a natural graphene oxide.

[0004] The application of nanotechnology in the preparation of herbicides is undoubtedly still a challenging innovation field in my country. The research enthusiasm is continuing to rise. The ideal goal is to create new agents that are efficient, safe, low-residue and highly degradable. Summary of the invention

[0005] The purpose of the present invention is to provide a palmitic acid-based nanopesticide and a preparation method thereof in view of the deficiencies in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing a palmitic acid-based nanopesticide comprises the following steps:

[0008] S1 dissolves the active ingredient of the pesticide in an alkaline solution to obtain a mixed solution A;

[0009] S2 dissolves the palmitic acid in the mixed solution A. If it does not dissolve, continue to add sodium hydroxide solution; ultrasonicate for 10-20 minutes to obtain a mixed solution B;

[0010] S3: Add a rotor to the mixed solution B, adjust the speed to 500-800 rpm, and uniformly add 0.1-0.5 M HCl to the beaker at a rate of 1-5 mL / min for 20-60 min until the pH of the solution is less than 2.0, and continue the reaction for 20-60 min;

[0011] S4 continues to add stabilizer to make the content of stabilizer 0.5-1.5%, and continues the reaction for 0.5-2h to obtain palmitic acid-based nano pesticide.

[0012] Preferably, as a preferred embodiment, the pesticide active ingredient in step S1 is a herbicide.

[0013] Preferably, as a preferred embodiment, the stabilizer is trimethyloctadecylammonium bromide.

[0014] Preferably, as a better embodiment, the active ingredient of the pesticide in step S1 is clofopyralid.

[0015] Preferably, as a preferred embodiment, the pH of the alkaline aqueous solution in step S1 is greater than 10, and the alkaline aqueous solution can be obtained by adjusting the pH using sodium hydroxide or potassium hydroxide, but cannot be obtained by adjusting the pH using calcium hydroxide.

[0016] Preferably, as a better embodiment, the mass ratio of palmitic acid to the active ingredient of the pesticide in step S2 is 3-10:1.

[0017] Preferably, as a preferred embodiment, the preparation method of the palmitic acid is: the biomass material is subjected to alkaline solution pyrolysis using 0.5 mol / L sodium hydroxide, and then the palmitic acid with a molecular weight of 4000-8000 Daltons is separated and collected through a dialysis bag of 4000-8000 Daltons.

[0018] Preferably, as a preferred embodiment, the biomass material is selected from one or more of agricultural and forestry wastes and livestock and poultry manure, and more preferably, the biomass material is pig manure.

[0019] Preferably, as a preferred embodiment, the molecular weight of the palmitic acid is 4000-8000.

[0020] Another object of the present invention is to provide a nanopesticide prepared by the above preparation method.

[0021] Another object of the present invention is to provide an application of the nanopesticide, wherein the nanopesticide is used as a herbicide spray to prolong the soil half-life and improve the efficacy.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The palmitic acid in the palmitic acid-based nano pesticide of the present invention has the function of controlling the release of active ingredients of the pesticide, can prolong the half-life in the soil, and improve the effect of the active ingredients of the pesticide. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The SEM image of the palmitic acid-based nanopesticide prepared in Example 1 is shown. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. The following specific implementation methods further describe the present invention.

[0026] Unless otherwise specified, the chemical substances of the present invention can be purchased from the market.

[0027] 1. Embodiment 1

[0028] A method for preparing a palmitic acid-based nanopesticide comprises the following steps:

[0029] S1 dissolving fluroxypyraclostrobin in an alkaline aqueous solution with a pH value greater than 10 to obtain a mixed solution A;

[0030] S2: using 0.5 mol / L sodium hydroxide to perform alkaline pyrolysis on corn stalks, and then separating and collecting palmitic acid with a molecular weight of 4000-8000 Daltons through a 4000-8000 Dalton dialysis bag; dissolving the palmitic acid with a molecular weight of 4000-8000 Daltons in a mixed solution A, and ultrasonicating for 10-20 minutes to obtain a mixed solution B; the mass of the palmitic acid is 5 times the mass of clofopyralid in step S1.

[0031] S3: Add a rotor to the mixed solution B, adjust the speed to 600 rpm, and uniformly add 0.25 M HCl to the beaker at a rate of 5 mL / min for 60 min until the pH of the solution is less than 2.0. Continue the reaction for 60 min.

[0032] S4 continues to add the stabilizer trimethyloctadecylammonium bromide to make the content of the stabilizer 1.0%, and continues the reaction for 1.0h to obtain the palmitic acid-based nanopesticide.

[0033] After the palmitic acid-based nanopesticide described in Example 1 is synthesized, the particle morphology of the pesticide is observed by scanning electron microscopy. If spherical particles are present, it means that the synthesis is successful; if spherical particles are not present, it means that the synthesis has failed; the reaction system is subjected to solid-liquid separation, and the concentration of the pesticide in the liquid phase is analyzed by liquid chromatography; the solid phase sample is extracted by acetonitrile (solid-liquid ratio = 1:100) + ultrasonic crushing extraction, and the pesticide is analyzed by liquid chromatography; the loading rate of the pesticide is calculated according to the liquid and solid phase pesticide concentrations. If the loading rate is low, it means that the synthesis has failed. The average particle size of the pesticide is measured by a nanoparticle size Zeta potential analyzer on the synthesized pesticide particle suspension. According to the method for determining the thermal storage stability of pesticides (GBT19136-2021), the changes in the particle size and concentration of the pesticide particles are observed after a 14-day 54-degree thermal storage experiment to determine the stability of the pesticide.

[0034] The herbicide efficacy test adopts field experiment, and the specific scheme is as follows: the test field is fallow before the crop, and the soil is loam; the main broad-leaved weeds in the field are purslane, Amaranthus retroflexus and Amaranthus ferox, and the test adopts the pesticide preparations prepared by Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, and manual weeding (CK1) and blank control (CK2) are used as controls. A total of 7 treatments, 4 repetitions, and random block arrangement of plots. When applying the pesticide, the weeds are in the two to four leaf stage, and the corn is in the four to five leaf stage, and the stems and leaves are evenly sprayed. The base number of weeds is investigated 1 day before the application of the drug, and the number of plants is investigated 14 days after the application of the drug, and the control effect is calculated.

[0035] 2. Comparative Example 1

[0036] A method for preparing a palmitic acid-based nanopesticide comprises the following steps:

[0037] S1 dissolving fluroxypyraclostrobin in an alkaline aqueous solution with a pH value greater than 10 to obtain a mixed solution A;

[0038] S2: using 0.5 mol / L sodium hydroxide to pyrolyze corn stalks, and then separating and collecting palmitic acid with a molecular weight of 1000-3000 Daltons through a dialysis bag of 1000-3000 Daltons. Dissolving the palmitic acid with a molecular weight of 1000-3000 Daltons in mixed solution A, ultrasonicating for 10-20 min, and obtaining mixed solution B; the mass of the palmitic acid is 5 times the mass of clofopyralid in step S1.

[0039] S3: Add a rotor to the mixed solution B, adjust the speed to 600 rpm, and uniformly add 0.25 M HCl to the beaker at a rate of 5 mL / min for 60 min until the pH of the solution is less than 2.0. Continue the reaction for 60 min.

[0040] In step S4, trimethyloctadecylammonium bromide as a stabilizer is continuously added to make the content of the stabilizer 1.0%, and the mass of humic acid is 5 times the mass of clofopyralid in step S1.

[0041] S3: Add a rotor to the mixed solution B, adjust the speed to 600 rpm, and uniformly add 0.25 M HCl to the beaker at a rate of 5 mL / min for 60 min until the pH of the solution is less than 2.0. Continue the reaction for 60 min.

[0042] S4: Continue to add sodium dodecylbenzene sulfonate to make the content of sodium dodecylbenzene sulfonate reach 1.0%, and continue the reaction for 1.0 h to obtain palmitic acid-based nano pesticide.

[0043] The morphology of the pesticide was observed using a scanning electron microscope. The pesticide clofopyralid particles in Example 1 were spherical, with a size of 40-60 nanometers and were evenly dispersed. The above-mentioned nanoparticle synthesis method was reliable.

[0044] Palmitic acid with a molecular weight of 1000-3000 and commercial black humic acid can synthesize larger nanoparticles; as shown in Table 1, further characterization results show that the particle size of nanoparticles synthesized from palmitic acid with a molecular weight of 1000-3000 and commercial black humic acid is significantly increased to 300-500nm and above 1um, and the loading rate of the pesticide clofopyralid is less than 25% (13.2% and 21.4%), while the particle size of nanoparticles synthesized from palmitic acid with a molecular weight of 4000-8000 is 40-60nm, and the pesticide loading rate is 97%.

[0045] The stabilizer trimethyloctadecylammonium bromide in Example 1 was replaced with anionic surfactant sodium dodecylbenzenesulfonate, and the particle size, loading rate and thermal storage stability of clofopyralid were observed. The results are shown in Table 2.

[0046] According to the method for determining the thermal storage stability of pesticides (GBT19136-2021), after 14 days of thermal storage experiment at 54 degrees, the particle size of the clofopyralid pesticide particles in Example 1 did not change significantly, and remained at 50-70nm, and the active ingredients of the pesticide did not break the capsule and release; while in Comparative Example 4, after the anionic surfactant sodium dodecylbenzene sulfonate was used, the particle size of the clofopyralid pesticide increased by about ten times after 14 days of thermal storage, reaching 500-700nm, and the pesticide loading rate decreased from 90.2% and 95.4% to 83.4% and 75.2%, and the active ingredients of the pesticide also released. The above results show that the nanopesticide in Example 1 has high stability and a reliable synthesis method.

[0047] Table 1 Comparison of particle size and loading rate of pesticides prepared by different treatments

[0048]

[0049] Table 2 Effects of different surfactants on the particle size, loading rate and thermal storage stability of pesticides

[0050]

[0051] 5. Application Examples

[0052] 14 days after the application, all the sensitive weeds, Portulaca oleracea, in the treatment plots of fluroxypyr in Example 1 were 100% dead, and most of Amaranthus retroflexus and Amaranthus ferox were dead (91.8%-100%), and the weeds that did not die were significantly inhibited. The total control effect of fluroxypyr treatment on the number of weeds was 46.4%%-80.3% (Table 4).

[0053] Table 3 Test results of controlling annual purslane, Amaranthus retroflexus and Amaranthus oleraceus in corn fields 14 days after application (%)

[0054] deal with purslane Amaranthus retroflexus Amaranthus Example 1 100％ 95.4％ 100％ Comparative Example 1 74.6％ 65.2％ 80.3％ Comparative Example 2 56.8％ 46.4％ 52.5％ Comparative Example 3 71.2％ 63.3％ 68.1％ CK1 78.5％ 81.2％ 77.9％ CK2 － － －

[0055] Note: The protective efficacy (%) in the above table is the average value of each replicate.

[0056] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A method for preparing a palmitic acid-based nanopesticide, characterized in that: The steps include: S1 dissolves the active ingredient of the pesticide in an alkaline solution to obtain a mixed solution A; S2 dissolves the palmitic acid in the mixed solution A. If it does not dissolve, continue to add sodium hydroxide solution; ultrasonicate for 10-20 minutes to obtain a mixed solution B; S3: Add a rotor to the mixed solution B, adjust the speed to 500-800 rpm, and uniformly add 0.1-0.5 M HCl to the beaker at a rate of 1-5 mL / min for 20-60 min until the pH of the solution is less than 2.0, and continue the reaction for 20-60 min; S4 continues to add the stabilizer trimethyloctadecylammonium bromide to make the content of the stabilizer 0.5-1.5%, and continues the reaction for 0.5-2h to obtain the palmitic acid-based nano pesticide.

2. The method for preparing a palmitic acid-based nanopesticide according to claim 1, characterized in that: The active ingredient of the pesticide in step S1 is a herbicide.

3. The method for preparing a palmitic acid-based nanopesticide according to claim 1, characterized in that: The herbicide is fluroxypyra.

4. The method for preparing a palmitic acid-based nanopesticide according to claim 1, characterized in that: The preparation method of the palmitic acid in S2 is: the biomass material is subjected to alkaline liquid pyrolysis using 0.5 mol / L sodium hydroxide, and then the palmitic acid with a molecular weight of 4000-8000 Daltons is separated and collected through a dialysis bag of 4000-8000 Daltons.

5. The method for preparing a palmitic acid-based nanopesticide according to claim 1, characterized in that: The biomass material is selected from agricultural and forestry wastes and livestock and poultry manure.

6. The nanopesticide prepared according to the method for preparing the palmitic acid-based nanopesticide according to any one of claims 1 to 4.

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