CN102217595B - Phytocide granule and preparation method of granule - Google Patents

Abstract

The invention discloses a phytocide granule and a preparation method of the granule. The preparation method is characterized by including the steps of respectively adding phytocide and bentonite in carboxymethyl chitosan solution, uniformly mixing, dropping the mixed solution in cross-linking agent solution, heating to finish surface cross-linking to obtain solid particles and drying the solid particles to obtain the granular preparation of phytocide. In application, the granule can delay the release of phytocide, reduce drug consumption, prolong action time, improve utilization rate of phytocide and control the pollution of phytocide to the environment.

Description

A kind of herbicide granule and preparation method thereof

Technical field:

The invention relates to a herbicide granule and a preparation method thereof, in particular to a herbicide granule with bentonite and carboxymethyl chitosan as carriers and a preparation method thereof.

Background technique:

There are many weeds in my country's farmland, and the efficiency of manual weeding is low and the cost is high, which leads to the continuous expansion of the area where chemical weeding technology is used. However, the existing herbicides are mainly in conventional formulations such as emulsifiable concentrates. After being applied to plants or soil, most of the active ingredients of herbicides will be lost with the surface runoff, or leached with the vertical movement of soil moisture, and enter the surface or groundwater system. It reduces the utilization efficiency of herbicides, and on the other hand, it brings serious environmental pollution problems. The use of slow-release technology can reasonably adjust the release rate of herbicide active ingredients according to the requirements of control objectives, so as to improve the efficacy and prolong the duration of efficacy. Secondly, by controlling the release of herbicides, the migration of herbicides in the environment can be reduced and pollution can be controlled from the source.

At present, herbicide slow-release technology can be divided into two categories: physical slow-release and chemical slow-release. The former mainly relies on the physical combination between the carrier and the active ingredients of the herbicide, and the herbicide activity is basically not affected by the carrier, and the slow-release dosage form is relatively easy to process and develops rapidly (Wang Baoqing et al., Applied Chemical Industry, 2005, 34: 519–523) . Among the physical sustained-release technologies, there are mainly microcapsule entrapment technology and adsorption material loading technology. In the microcapsule technology, the original drug is first dispersed into fine droplets, and then wrapped with polyurethane, urea-formaldehyde resin and other polymer compounds to form a capsule structure containing active ingredients in the membrane. When used, the active ingredients diffuse outward through the membrane wall. To achieve the purpose of slow release. However, the production technology of microcapsules is high, the molding process is complicated, and the capsule wall is easily broken, which affects the sustained-release effect. The herbicide sustained-release preparation is prepared by using the adsorption material as a carrier, which has the advantages of simple process and low cost. Among them, clay materials are rich in resources, low in price, large in specific surface area, and easy to modify, thereby preparing modified clays with good adsorption properties for herbicides and used as herbicide formulation carriers (Y El-Nahhal et al., Pestic Sci, 1999, 55: 857–864). However, the clay-based carrier itself has a low loading capacity of the herbicide, and the mass content of the herbicide is usually below 4%, and the slow-release effect becomes significantly worse after the drug loading increases. Therefore, it is necessary to develop new herbicide preparations with high drug loading and good sustained-release effect based on the existing technology.

Invention content:

The purpose of the first aspect of the present invention is to provide a kind of herbicide granule with bentonite and carboxymethyl chitosan as the carrier. Application of the present invention can delay the release of herbicide, reduce application amount, prolong action time, and improve weed control. Herbicide utilization rate, control herbicide pollution to the environment.

In order to achieve the above object, the technical scheme that the present invention takes is:

A herbicide granule, which is characterized in that: the herbicide and bentonite are respectively added to the carboxymethyl chitosan solution, mixed evenly, the above mixed solution is dropped into the cross-linking agent solution, and the surface cross-linking is completed by heating to obtain a solid Granules, the solid granules are dried to obtain herbicide granules.

Further restrictions are:

The herbicides refer to various natural or synthetic chemicals used in agricultural production for the purpose of eliminating weeds and protecting the normal growth of crops.

The bentonite refers to layered clay minerals with montmorillonite as the main component, including modified bentonite prepared for improving the adsorption performance of herbicides. The exchangeable cations between the bentonite layers are calcium ions or sodium ions, and the modified bentonite refers to the product obtained by ion exchange reaction between bentonite and metal cations, inorganic acid hydrogen ions, cationic surfactants, etc. by using the prior art.

The carboxymethyl chitosan refers to the water-soluble derivative obtained after the amino group and the hydroxyl group on the chitosan molecular structure are substituted by carboxymethyl groups, and its degree of substitution is between 0.3 and 0.99, which can be obtained by purchasing existing products on the market Or obtain by using existing preparation methods.

The cross-linking agent is a water-soluble salt compound of a multivalent metal cation such as calcium ion, or a polyaldehyde compound such as glutaraldehyde, or a mixture of the above two cross-linking agents in a certain proportion and form. The crosslinking agent participates in the preparation method of the present invention in the form of aqueous solution.

The herbicide granule with bentonite and carboxymethyl chitosan as the carrier of the present invention uses the water solubility of carboxymethyl chitosan to prepare a mixed solution capable of wrapping the herbicide; utilizes the rapid crosslinking of carboxymethyl chitosan Reaction to prepare shaped granule preparations; using cross-linked carboxymethyl chitosan to wrap and bentonite adsorption to increase the drug loading of the preparation and prolong the release time of herbicides; Sustained-release effects of carboxylic acid-containing herbicides.

Another object of the present invention is to provide a preparation method of the above-mentioned herbicide granules, comprising the following steps: preparing an aqueous solution with a carboxymethyl chitosan content of 0.5% to 10% (mass percentage, the same below), and mixing bentonite Add herbicide, stir and mix evenly, wherein the mass ratio of bentonite to carboxymethyl chitosan is 0.2~5:1, and the mass ratio of herbicide to carboxymethyl chitosan is 0.1~2:1 . The obtained mixed liquid is dropped into the cross-linking agent solution, heated and cross-linked for 1-9 minutes to obtain solid particles, and dried to obtain herbicide granules.

The beneficial effects of the present invention are: (1) the release time of the herbicide can be extended to more than 300 hours, thereby prolonging the effective period, reducing the frequency and dosage of repeated application of the herbicide, which is beneficial to control the problem of pesticide pollution; (2) Formed granules can be obtained, which improves the convenience and safety of herbicide use; (3) Compared with simple bentonite loading, it increases the drug loading of herbicide and prolongs the release time of herbicide.

Description of drawings:

Fig. 1 is the release rate curve figure of the herbicide prepared by the embodiment of the present invention 1～3;

Fig. 2 is a graph showing the release rate of herbicides prepared in Comparative Examples 1-3 of the present invention.

Detailed ways:

Example 1:

Add 5 g of carboxymethyl chitosan into 100 g of water, stir until it is completely dissolved, then add 3 g of bentonite, 2 g of herbicide 2,4-D-butyl (2,4-dichlorophenoxybutyl acetate) , stir thoroughly to form a homogeneous suspension. Prepare 1000 mL of calcium chloride (cross-linking agent) aqueous solution with a mass concentration of 6%, add the above suspension into the cross-linking agent solution dropwise with a peristaltic pump, and react at 60°C for 5 minutes to obtain a granular product. Filter out and then dry at 70°C for 2 h to obtain herbicide granules with an average particle size of about 0.8 mm. After extraction and analysis, the mass content of 2,4-D butyl ester in the preparation was 18.2%, and the loading rate of 2,4-D butyl ester was 91.0%.

The herbicide preparation prepared above was subjected to a release experiment, and 100 mg of the preparation sample was put into 1000 mL of water. After a certain interval, water samples were taken to analyze the quality of the herbicide in it, and the release rate of the herbicide at different times was calculated (i.e., released into the water). The mass of herbicide accounts for the percentage of the original mass in the preparation), and the results are shown in Figure 1. As a herbicide analysis method, a well-known chromatographic method in the technical field of pesticide analysis can be used.

Example 2:

Take 4.5 g of bentonite, perform ion exchange reaction with 10 mL of sulfuric acid aqueous solution with a mass concentration of 20%, centrifuge to separate the solid, and dry to obtain 4.0 g of acid-activated bentonite.

Add the above-mentioned acid-activated bentonite to 100 g of carboxymethyl chitosan aqueous solution (the mass content of carboxymethyl chitosan is 3%), stir evenly, add 3 g of herbicide metolachlor, fully stir and mix until uniform suspension. Then use a peristaltic pump to drop into the cross-linking agent solution as described in Example 1, react at 60°C for 3 minutes to obtain a granular product, then dry at 70°C for 2 h to obtain an average particle diameter of about 0.9 mm The herbicide preparation, wherein the mass content of metolachlor is 26.5% after extraction and analysis, and the entrapment rate of metolachlor is 88.3%. Take 70 mg of the preparation sample, adopt the method described in Example 1 to carry out the release experiment, and obtain the release rate of the herbicide at different times, the results are shown in Figure 1.

Example 3:

3 g of bentonite was taken, and after ion exchange reaction with 30 mL of cetyldimethylammonium chloride aqueous solution with a mass concentration of 2%, the solid was separated by centrifugation, and 3.1 g of organically modified bentonite was obtained by drying.

Prepare 100 g of carboxymethyl chitosan aqueous solution with a mass content of 4%, add the above-mentioned organically modified bentonite and 4 g of the herbicide alachlor in sequence, and stir thoroughly to form a uniform suspension. Prepare 500 mL of calcium chloride aqueous solution and glutaraldehyde aqueous solution with a mass concentration of 10%, respectively, and use them as cross-linking agents after mixing evenly. Add the above suspension into the crosslinking agent solution dropwise with a peristaltic pump, react at 50°C for 3 minutes to obtain a granular product, filter the particles, and then dry at 70°C for 2 hours to obtain an average particle size of about 1.0 mm herbicide granules. After extraction and analysis, the mass content of alachlor in the preparation was 33.8%, and the loading rate of alachlor was 93.9%. Take 55 mg of the preparation sample, and use the method described in Example 1 to carry out the release experiment to obtain the release rate of the herbicide at different times. The results are shown in Figure 1.

Comparative Example 1:

Add 8 g of bentonite and 2 g of herbicide 2,4-D butyl ester into 100 g of water, stir well and mix well. Because bentonite cannot undergo cross-linking reaction, the suspension was centrifuged to separate the solid matter, and then dried at 70 °C for 2 h to obtain a powdered herbicide preparation. After extraction and analysis, the mass content of 2,4-D butyl ester in the preparation was 7.8%, and the loading rate was 39.0%. Take 200 mg of this powdery preparation, adopt the method described in Example 1 to carry out the release experiment, and obtain the release rate of the herbicide at different times, the results are shown in Figure 2.

Comparative example 2:

Add 7 g of acid-activated bentonite and 3 g of herbicide metolachlor into 100 g of water, stir well and mix well. The resulting suspension was centrifuged to separate the solid matter, and then dried at 70 °C for 2 h to obtain a powdered herbicide formulation. After extraction and analysis, the mass content of metolachlor in the preparation was 10.1%, and the entrapment rate was 33.6%. Get 150 mg of powdery preparation, adopt the method described in Example 1 to carry out release experiment, obtain the release rate of herbicide under different time, the results are shown in Figure 2.

Comparative example 3:

Add 7.1 g of organically modified bentonite and 4 g of herbicide alachlor into 100 g of water, stir well and mix evenly. The resulting suspension was centrifuged to separate the solid matter, and then dried at 70 °C for 2 h to obtain a powdered herbicide formulation. After extraction and analysis, the mass content of alachlor in the preparation was 14.9%, and the entrapment rate was 41.3%. Take 100 mg of powdery preparation, adopt the method described in Example 1 to carry out release experiment, obtain the release rate of herbicide under different time, the results are shown in Figure 2.

Effect comparison:

Can find out in conjunction with Fig. 1, Fig. 2, the present invention adopts the herbicide granule with bentonite and carboxymethyl chitosan as carrier; Utilize the encapsulation of cross-linked carboxymethyl chitosan and the adsorption of bentonite to improve the drug loading of preparation amount, prolong the release time of herbicides; use the amino cationic characteristics of carboxymethyl chitosan to strengthen the slow-release effect on herbicides containing carboxylic acids; thus the release time of herbicides can be extended to more than 300 hours, improving The duration of effect is improved, the number of times and the amount of repeated application of herbicides are reduced, which is beneficial to control the problem of pesticide pollution; while the traditional simple bentonite load, its release time is only about 70 hours. Therefore, compared with the prior art, the present invention has The drug loading capacity of the herbicide is increased, and the release time of the herbicide is prolonged.

Claims (3)

1. A herbicide granule, characterized in that: 5 g of carboxymethyl chitosan is added to 100 g of water, stirred until it is completely dissolved, then 3 g of bentonite, 2 g of herbicide 2,4-D butyl ester are added , fully stirred and mixed into a uniform suspension, prepared 1000 mL of calcium chloride aqueous solution with a mass concentration of 6%, added the above suspension into the calcium chloride aqueous solution with a peristaltic pump, and reacted at 60°C for 5 minutes to obtain granular product, the particles were filtered out, and then dried at 70°C for 2 h to obtain a herbicide granule preparation with an average particle size of about 0.8 mm. 2. a herbicide granule, is characterized in that: get bentonite 4.5 g, after carrying out ion exchange reaction with 10 mL mass concentration of 20% sulfuric acid aqueous solution, centrifuge and separate solid matter, obtain acid-activated bentonite 4.0 g through drying, Add the above-mentioned acid-activated bentonite into 100 g of carboxymethyl chitosan aqueous solution, the mass content of carboxymethyl chitosan is 3%, after stirring evenly, add 3 g of herbicide metolachlor, fully stir and mix to form a uniform suspension solution, prepare 1000 mL of calcium chloride aqueous solution with a mass concentration of 6%, drop the above suspension into the calcium chloride aqueous solution with a peristaltic pump, react at 60°C for 3 minutes to obtain a granular product, and then Dry for 2 h to obtain a herbicide formulation with an average particle size of about 0.9 mm. 3. a herbicide granule, is characterized in that: get bentonite 3 g, after carrying out ion exchange reaction with 30 mL mass concentration of 2% hexadecyl dimethyl ammonium chloride aqueous solution, centrifugal separation solid matter, After drying, 3.1 g of organically modified bentonite was obtained; 100 g of carboxymethyl chitosan aqueous solution with a mass content of 4% was prepared, and the above-mentioned organically modified bentonite and herbicide alachlor 4 g were added in sequence, and fully stirred and mixed to form a uniform suspension , respectively prepare 500 mL of calcium chloride aqueous solution and glutaraldehyde aqueous solution with a mass concentration of 10%, and use it as a crosslinking agent after mixing evenly. The above suspension is added dropwise to the crosslinking agent solution with a peristaltic pump. After reacting at low temperature for 3 minutes, a granular product was obtained. The particles were filtered out, and then dried at 70°C for 2 hours to obtain a herbicide granule formulation with an average particle size of about 1.0 mm.

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