Water retention type sustained and controlled release fertilizer and preparation method thereof

Abstract

The invention discloses a water-retaining controlled-release fertilizer and a preparation method thereof, and relates to the technical field of controlled-release fertilizers. According to the invention, the attapulgite is modified by a phosphoric acid solution, so that the surface of the attapulgite has acidic groups, and the groups can be adsorbed with positive ions in the fertilizer, so that nutrients are adsorbed and fixed on the surface of the attapulgite, and the speed of releasing the fertilizer nutrients into a soil solution is delayed; meanwhile, the modified attapulgite and some nutritional ingredients in the fertilizer can form indissolvable compounds, so that the nutrients are slowly released along with gradual dissolution of the compounds, and the fertilizer efficiency of the fertilizer is prolonged; when the modified attapulgite encounters water, the entering speed of water can be effectively slowed down, dissolution of nutrients in fertilizer particles is controlled, and then the slow and controlled release effect is achieved; and the modified attapulgite can regulate the pH value of the soil, so that the soil environment is more suitable for plant growth and slow release of fertilizer nutrients.

Description

Technical Field

[0001] The invention relates to the technical field of slow-release fertilizers, in particular to a water-retaining slow-release fertilizer and a preparation method thereof. Background Art

[0002] The Chinese patent with publication number CN105237285A discloses a chemically polymerized high water-retaining slow-release fertilizer, which is prepared by chemical polymerization from raw materials such as attapulgite, phosphated polyvinyl alcohol, diatomaceous earth, gelatinized starch, water-soluble ethylene-based unsaturated monomers, water-soluble free radical polymerization initiators, composite crosslinking agents, and fertilizers. The product has the functions of slow-release of fertilizers, water-retaining and water-releasing, and improving soil, which effectively improves the utilization rate of fertilizers, reduces fertilizer loss and insufficient crop supply caused by one-time fertilization, effectively maintains soil moisture, improves soil structure, and enhances soil permeability; the slow-release carrier uses a mixture of attapulgite, phosphated polyvinyl alcohol, diatomaceous earth, and gelatinized starch, and uses a composite crosslinking agent to significantly improve the water-retaining effect of the product; the production cost is low, the environment is environmentally friendly, and it is convenient for large-scale promotion and application. However, the water-retaining performance of the fertilizer prepared by the above-mentioned prior art scheme and the slow-release performance of nutrients need to be further improved; for this reason, the present invention provides a water-retaining slow-release fertilizer and a preparation method thereof to solve the above problems. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a water-retaining slow-release fertilizer and a preparation method thereof, which solves the problems mentioned in the above background technology.

[0004] To achieve the above objectives, the present invention is implemented through the following technical scheme: a water-retaining slow-release fertilizer, comprising the following components in parts by weight: 60-80 parts of fertilizer, 5-8 parts of modified attapulgite, 6-10 parts of modified biochar, 2-3.5 parts of activated starch, 3.5-5 parts of polyvinyl alcohol, and 160-200 parts of deionized water.

[0005] A method for preparing a water-retaining slow-release fertilizer comprises the following steps: Step 1, heat the deionized water bath to 50-55°C, slowly add polyvinyl alcohol under stirring, then raise the temperature to 95-100°C, continue stirring until the polyvinyl alcohol is completely dissolved, keep the temperature for 50-60 minutes, place at room temperature and cool down to 50-60°C to obtain a film-forming agent; Step 2: Add modified attapulgite and activated starch to the fertilizer, heat it to 60-65°C, pour it into a disc granulator, and use a high-pressure spray pot to spray a film-forming agent at a temperature of 50-60°C; Step 3: After the surface of the fertilizer is moistened, the modified biochar is added until all the biochar is added and densely wrapped on the fertilizer to form a biochar coating; Step 4: After the coating is completed, spread the fertilizer on the tray and air-dry it at 35-40℃ for 20-24h to obtain a water-retaining slow-release fertilizer. Preferably, in step 2, the disc inclination angle is set to 40° and the rotation speed is set to 30-40 r / min.

[0006] Preferably, the fertilizer is selected from one or more of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, compound fertilizer, trace element fertilizer, organic fertilizer, organic compound fertilizer, and biological fertilizer.

[0007] Preferably, the preparation method of the modified attapulgite is: adding 320mL of 6mol / L phosphoric acid solution to 60-75g of attapulgite, heating in a water bath for 2h and then filtering, washing the filter cake 4-6 times with distilled water, adding 320mL of distilled water during immersion, shaking on a shaker for 5-10min, placing in a drying oven at 100-105°C to dry, and then grinding through a 100-120 mesh sieve to obtain modified attapulgite.

[0008] Preferably, the preparation method of the modified biochar is: (1) Cut 70-80 parts of straw into 1.5-2 cm pieces, wash them and dry them in a drying oven at 65-70°C for 20-24 hours; (2) Crush the dried straw and pass it through a 60-80 mesh sieve; (3) Add 6-10 parts of bentonite, then add 400 mL of deionized water, and stir at 700-750 r / min for 40-45 minutes; (4) drying, crushing, and sieving through a 60-80 mesh sieve in sequence; (5) placing in a tubular furnace for pyrolysis, wherein the N2 flow rate is 25-30 mL / min, the heating rate is 8-10 °C / min, and after heating to 550-600 °C, the temperature is kept for 1.8-2 h; (6) Cool the mixture and sieve it through a 15-20 mesh sieve to obtain the modified organism.

[0009] Preferably, the straw is selected from one or more of wheat straw, corn straw, rice straw and cotton straw.

[0010] Preferably, the preparation method of the activated starch is: Ⅰ. Put 100-120g of cassava starch with a water content of 12% into a grinding tube, add 280-300mL of zirconium oxide balls, activate them for 15-25 minutes, and then take out the zirconium oxide balls; Ⅱ. Add 10 mol / L sodium hydroxide solution to 40-50 g of 50% citric acid solution, adjust the pH to 3.0-3.5, and then dilute the solution to 25%-30%, which is called solution 1. III. Pour the cassava starch treated in Ⅰ into solution 1, mix well, and let stand at room temperature for 10-12 hours; IV. Place in a drying oven at 40-45°C and dry until the moisture content is 5-10% and then take out; V. Grind and sieve, first use deionized water to filter and wash 3-4 times, then use anhydrous ethanol to wash 1-2 times, and then place in a drying oven at 45-50°C to dry, so as to obtain activated starch.

[0011] The present invention provides a water-retaining slow-release fertilizer and a preparation method thereof. Compared with the prior art, the fertilizer has the following beneficial effects: (1) In the present invention, the phosphoric acid solution attapulgite is modified so that the surface of the attapulgite has acidic groups, which can adsorb cations in the fertilizer, so that the nutrients are adsorbed and fixed on the surface of the attapulgite, thereby delaying the release rate of fertilizer nutrients into the soil solution; at the same time, the modified attapulgite can also form an insoluble complex with some nutrients in the fertilizer, so that the nutrients are slowly released as the complex gradually dissolves, thereby prolonging the fertilizer effect; when the modified attapulgite meets water, it can effectively slow down the entry rate of water, control the dissolution of nutrients inside the fertilizer particles, and thus play a role in slow release; and the modified attapulgite can adjust the soil pH, making the soil environment more suitable for plant growth and slow release of fertilizer nutrients; the modified attapulgite can make soil particles better agglomerate, increase the porosity of the soil, improve the air permeability and water permeability of the soil, facilitate the storage and penetration of water in the soil, and improve the water retention performance of the soil.

[0012] (1) In the present invention, bentonite is conducive to the formation of an ideal pore structure of biochar during pyrolysis, thereby jointly adsorbing more nutrients and water, making it difficult for nutrients in the fertilizer to be lost, effectively controlling the release rate of the fertilizer, and extending the slow-release period of the fertilizer; and biochar can adjust the pH value of the soil to prevent excessive loss of nutrients due to changes in soil pH. Bentonite can enhance the fertilizer retention capacity of the soil and ensure that the fertilizer can continuously and stably provide nutrients to plants; the composite of bentonite and biochar can enhance the water retention capacity of the soil and slowly release the absorbed water to provide a continuous water supply for plants.

[0013] (2) In the present invention, citric acid is used to loosen the structure of cassava starch and increase its specific surface area, thereby improving the adsorption capacity of fertilizer nutrients and water, making nutrients more easily attached to starch, enhancing the water retention capacity of fertilizer and achieving the effect of slow release; and the activated cassava starch interacts with citric acid to form a gel-like network structure after contacting water, which can effectively wrap fertilizer nutrients and water, slow down the release rate of nutrients and the evaporation and loss of water, prolong the fertilizer effect period, and enable the fertilizer to remain moist in the soil for a long time; at the same time, citric acid can adjust the pH of the soil, making the soil environment more suitable for plant growth and the slow release of fertilizer nutrients, and its decomposition products can provide a carbon source for soil microorganisms, promote the activity of microorganisms, and thus improve the soil structure and fertility, which is conducive to the slow release fertilizer to better play its role. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The SEM images of starch before and after activation provided by the present invention; Figure 2 The SEM images of the attapulgite soil provided by the present invention before and after modification; Figure 3 The SEM images of the biochar provided by the present invention before and after modification; Figure 4 A comparison chart of the sustained-release performance test provided by the present invention; Figure 5 This is a comparison chart of the water retention performance test provided by the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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 are within the scope of protection of the present invention.

[0016] Example 1 A method for preparing a water-retaining slow-release fertilizer comprises the following steps: Step 1, heat 160g of deionized water to 50°C in a water bath, slowly add 3.5g of polyvinyl alcohol under stirring, then heat to 95°C, continue stirring until the polyvinyl alcohol is completely dissolved, keep warm for 50 minutes, place at room temperature and cool to 50°C to obtain a film-forming agent; Step 2: Add 5 g of modified attapulgite and 2 g of activated starch to 60 g of nitrogen fertilizer, heat to 60° C., pour into a disc granulator, and use a high-pressure spray pot to spray a film-forming agent at a temperature of 50° C.; The preparation method of modified attapulgite is as follows: add 320 mL of 6 mol / L phosphoric acid solution to 60 g of attapulgite, heat in a water bath for 2 h, filter, wash the filter cake 4 times with distilled water, add 320 mL of distilled water during washing, shake on a shaker for 5 min, dry in a drying oven at 100 ° C, and then grind through a 100 mesh sieve to obtain modified attapulgite; The preparation method of activated starch is as follows: 100g of cassava starch with a water content of 12% is put into a grinding tube, 280mL of zirconium oxide balls are added, and the activation treatment is carried out for 15min, and then the zirconium oxide balls are taken out; 10mol / L sodium hydroxide solution is added dropwise to 40g of citric acid solution with a concentration of 50%, and after adjusting the pH to 3.0, the solution concentration is diluted to 25%, which is recorded as solution one; the treated cassava starch is poured into solution one, mixed, and allowed to stand at room temperature for 10h; it is placed in a drying oven at 40°C and dried until the moisture content is 5% and then taken out; it is crushed and sieved, firstly filtered and washed 3 times with deionized water, then washed once with anhydrous ethanol, and then placed in a drying oven at 45°C to obtain activated starch; Step 3: After the surface of the fertilizer is moistened, add 6 g of modified biochar until all the biochar is added and densely wrapped on the fertilizer to form a biochar coating; The preparation method of modified biochar is as follows: 70g of wheat straw is cut into 1.5cm crumbs, washed and placed in a drying oven at 65°C for 20h; the dried straw is crushed and passed through a 60-mesh sieve; 6g of bentonite is added, and then 400mL of deionized water is added, and stirred at a speed of 700r / min for 40min; drying, crushing and passing through a 60-mesh sieve are performed in sequence; placing in a tubular furnace for pyrolysis, wherein the N2 flow rate is 25mL / min, the heating rate is 8°C / min, and after heating to 550°C, the temperature is kept for 1.8h; cooling and taking out and passing through a 15-mesh sieve to obtain modified biochar; Step 4: After coating, spread the fertilizer flat on a tray and air-dry it at 35°C for 20 hours to obtain a water-retaining slow-release fertilizer.

[0017] Example 2 A method for preparing a water-retaining slow-release fertilizer comprises the following steps: Step 1, heat 180g of deionized water to 53°C in a water bath, slowly add 4g of polyvinyl alcohol under stirring, then raise the temperature to 97°C, continue stirring until the polyvinyl alcohol is completely dissolved, keep the temperature for 55 minutes, place at room temperature and cool down to 55°C to obtain a film-forming agent; Step 2: Add 6.5 g of modified attapulgite and 3 g of activated starch to 70 g of phosphate fertilizer, heat to 65° C., pour into a disc granulator, and use a high-pressure spray pot to spray a film-forming agent at a temperature of 55° C.; The preparation method of modified attapulgite is as follows: add 320 mL of 6 mol / L phosphoric acid solution to 65 g of attapulgite, heat in a water bath for 2 h, filter, wash the filter cake 5 times with distilled water, add 320 mL of distilled water during immersion, shake on a shaker for 8 min, dry in a drying oven at 103 ° C, and then grind through a 110 mesh sieve to obtain modified attapulgite; The preparation method of activated starch is as follows: 110g of cassava starch with a water content of 12% is put into a grinding tube, 290mL of zirconium oxide balls are added, and the zirconia balls are activated for 20min, and then the zirconium oxide balls are taken out; 10mol / L sodium hydroxide solution is added dropwise to 45g of citric acid solution with a concentration of 50%, and after adjusting the pH to 3.2, the solution concentration is diluted to 28%, which is recorded as solution one; the treated cassava starch is poured into solution one, mixed, and allowed to stand at room temperature for 11h; it is placed in a drying oven at 43°C and dried until the moisture content is 8% and then taken out; it is crushed and sieved, firstly filtered and washed with deionized water for 4 times, then washed with anhydrous ethanol for 2 times, and then placed in a drying oven at 48°C to obtain activated starch; Step 3: After the surface of the fertilizer is moistened, add 8 g of modified biochar until all the biochar is added and densely wrapped on the fertilizer to form a biochar coating; The preparation method of modified biochar is as follows: 75g corn stalks are cut into 2cm pieces, washed and placed in a drying oven at 67°C for 22h; the dried stalks are crushed and passed through a 70-mesh sieve; 8g bentonite is added, and then 400mL deionized water is added, and stirred at a speed of 730r / min for 42min; drying, crushing, and passing through a 70-mesh sieve are performed in sequence; pyrolysis is performed in a tubular furnace, wherein the N2 flow rate is 28mL / min, the heating rate is 9°C / min, and after heating to 560°C, the temperature is kept for 1.92h; cooling is performed, and the stalks are taken out and passed through an 18-mesh sieve to obtain modified biochar; Step 4: After coating, spread the fertilizer flat on a tray and air-dry it at 38°C for 22 hours to obtain a water-retaining slow-release fertilizer.

[0018] Example 3 A method for preparing a water-retaining slow-release fertilizer comprises the following steps: Step 1, heat 200g of deionized water to 55°C in a water bath, slowly add 5g of polyvinyl alcohol under stirring, then heat to 100°C, continue stirring until the polyvinyl alcohol is completely dissolved, keep warm for 60 minutes, place at room temperature and cool to 60°C to obtain a film-forming agent; Step 2: Add 8 g of modified attapulgite and 3.5 g of activated starch to 80 g of potash fertilizer, heat to 65° C., pour into a disc granulator, and use a high-pressure spray pot to spray a film-forming agent at a temperature of 60° C.; The preparation method of modified attapulgite is as follows: add 320 mL of 6 mol / L phosphoric acid solution to 75 g of attapulgite, heat in a water bath for 2 h, filter, wash the filter cake 6 times with distilled water, add 320 mL of distilled water during immersion, shake on a shaker for 10 min, dry in a drying oven at 105 ° C, and then grind through a 120 mesh sieve to obtain modified attapulgite; The preparation method of activated starch is as follows: 120g of cassava starch with a water content of 12% is put into a grinding tube, 300mL of zirconium oxide balls are added, and the zirconia balls are activated for 25min, and then the zirconium oxide balls are taken out; 10mol / L sodium hydroxide solution is added dropwise to 50g of citric acid solution with a concentration of 50%, and after adjusting the pH to 3.5, the solution concentration is diluted to 30%, which is recorded as solution one; the treated cassava starch is poured into solution one, mixed, and allowed to stand at room temperature for 12h; it is placed in a drying oven at 45°C and dried until the moisture content is 10% and then taken out; it is crushed and sieved, firstly filtered and washed with deionized water for 4 times, then washed with anhydrous ethanol for 2 times, and then placed in a drying oven at 50°C to dry, so as to obtain activated starch; Step 3: After the surface of the fertilizer is moistened, add 10 g of modified biochar until all the biochar is added and densely wrapped on the fertilizer to form a biochar coating; The preparation method of modified biochar is as follows: 80g of cotton straw is cut into 2cm pieces, washed and placed in a drying oven at 70℃ for 24h; the dried straw is crushed and passed through an 80-mesh sieve; 10g of bentonite is added, and then 400mL of deionized water is added, and stirred at a speed of 750r / min for 45min; drying, crushing and passing through an 80-mesh sieve are performed in sequence; the modified biochar is placed in a tubular furnace for pyrolysis, wherein the N2 flow rate is 30mL / min, the heating rate is 10℃ / min, and after heating to 600℃, it is kept warm for 2h; cooled and taken out and passed through a 20-mesh sieve to obtain the modified biochar; Step 4: After coating, spread the fertilizer flat on a tray and air-dry it at 40°C for 24 hours to obtain a water-retaining slow-release fertilizer.

[0019] Comparative Example 1 Compared with the embodiment, the difference is that the modified attapulgite in embodiment 1 is replaced by attapulgite.

[0020] Comparative Example 2 Compared with the example, the difference is that the modified biochar in Example 1 is replaced by crushed and sieved wheat straw.

[0021] Comparative Example 3 Compared with the embodiment, the difference is that the activated starch in embodiment 1 is replaced by tapioca starch.

[0022] like Figure 1As shown, the cassava starch particles are mostly spherical or hemispherical, with a smooth surface and no obvious cracks. After activation treatment, the particle surface is damaged and the surface structure is irregular, making it easier for the reaction reagents to penetrate into the interior of the particles for esterification reaction.

[0023] like Figure 2 As shown in the figure, before modification, the attapulgite was an elliptical crystal with coarse aggregates and a very dense microstructure. After modification, the structure of the attapulgite showed varying degrees of breakage and circular collapse, and there were a large number of gaps and cracks. The aggregates were also dissociated to form a loosely interlaced, finer lamellar crystal bundle aggregate structure, which was beneficial to the storage and release of nitrogen, phosphorus and potassium nutrients.

[0024] like Figure 3 As shown, compared with the biochar before modification, pores are generated on the surface of the modified biochar, thereby enhancing the adsorption and storage capacity of gases, liquids and other substances.

[0025] Sustained release performance test: Tested in accordance with GB / T23348-2009; the results are as follows Figure 4 shown.

[0026] Water retention performance test: First, the slow-release fertilizer was mixed with the sieved sandy soil, then placed in a PVC tube (20x5cm) and weighed (marked as M0). Secondly, the PVC tube sample with mixed soil and fertilizer was slowly saturated with tap water from the top of the tube until water seeped out from the bottom. It was then left to stand for 24 hours until no excess water seeped out from the bottom. The PVC tube was weighed again (marked as M1). At the same time, each treated PVC tube was weighed for 15 consecutive days, and each day was weighed and marked as M. j ; The results are as follows Figure 5 As shown; the calculation formula for soil water retention capacity (WR%) is: .

[0027] like Figure 4 and Figure 5 As shown, the slow-release performance and water-retention performance of the fertilizers prepared in Examples 1-3 are significantly improved compared with those in Comparative Examples 1-3.

[0028] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0029] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A water-retaining slow-release fertilizer, characterized in that: The invention comprises the following components in parts by weight: 60-80 parts of fertilizer, 5-8 parts of modified attapulgite, 6-10 parts of modified biochar, 2-3.5 parts of activated starch, 3.5-5 parts of polyvinyl alcohol and 160-200 parts of deionized water.

2. A method for preparing a water-retaining slow-release fertilizer according to claim 1, characterized in that: The method comprises the following preparation steps: Step 1, heat the deionized water bath to 50-55°C, slowly add polyvinyl alcohol under stirring, then raise the temperature to 95-100°C, continue stirring until the polyvinyl alcohol is completely dissolved, keep the temperature for 50-60 minutes, place at room temperature and cool down to 50-60°C to obtain a film-forming agent; Step 2: Add modified attapulgite and activated starch to the fertilizer, heat it to 60-65°C, pour it into a disc granulator, and use a high-pressure spray pot to spray a film-forming agent at a temperature of 50-60°C; Step 3: After the surface of the fertilizer is moistened, the modified biochar is added until all the biochar is added and densely wrapped on the fertilizer to form a biochar coating; Step 4: After coating, spread the fertilizer flat on a tray and air-dry it at 35-40°C for 20-24 hours to obtain a water-retaining slow-release fertilizer.

3. The method for preparing a water-retaining slow-release fertilizer according to claim 2, characterized in that: In the step 2, the disc tilt angle is set to 40° and the rotation speed is set to 30-40 r / min.

4. The method for preparing a water-retaining slow-release fertilizer according to claim 2, characterized in that: The fertilizer is selected from one or more of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, compound fertilizer, trace element fertilizer, organic fertilizer, organic compound fertilizer, and biological fertilizer.

5. The method for preparing a water-retaining slow-release fertilizer according to claim 2, characterized in that: The preparation method of the modified attapulgite is as follows: 320 mL of 6 mol / L phosphoric acid solution is added to 60-75 g of attapulgite, the mixture is heated in a water bath for 2 hours and then filtered, and the filter cake is washed 4-6 times with distilled water, 320 mL of distilled water is added during the immersion, the mixture is shaken on a shaking table for 5-10 minutes, the mixture is placed in a drying oven at 100-105° C. and dried, and then ground through a 100-120 mesh sieve to obtain the modified attapulgite.

6. The method for preparing a water-retaining slow-release fertilizer according to claim 2, characterized in that: The preparation method of the modified biochar is: (1) Cut 70-80 parts of straw into 1.5-2 cm pieces, wash them and dry them in a drying oven at 65-70°C for 20-24 hours; (2) Crush the dried straw and pass it through a 60-80 mesh sieve; (3) Add 6-10 parts of bentonite, then add 400 mL of deionized water, and stir at 700-750 r / min for 40-45 minutes; (4) drying, crushing, and sieving through a 60-80 mesh sieve in sequence; (5) placing in a tubular furnace for pyrolysis, wherein the N2 flow rate is 25-30 mL / min, the heating rate is 8-10 °C / min, and after heating to 550-600 °C, the temperature is kept for 1.8-2 h; (6) Cool down and take out through a 15-20 mesh sieve to obtain modified biochar.

7. The method for preparing a water-retaining slow-release fertilizer according to claim 6, characterized in that: The straw is selected from one or more of wheat straw, corn straw, rice straw and cotton straw.

8. The method for preparing a water-retaining slow-release fertilizer according to claim 2, characterized in that: The preparation method of the activated starch is: Ⅰ. Put 100-120g of cassava starch with a water content of 12% into a grinding tube, add 280-300mL of zirconium oxide balls, activate them for 15-25 minutes, and then take out the zirconium oxide balls; Ⅱ. Add 10 mol / L sodium hydroxide solution to 40-50 g of 50% citric acid solution, adjust the pH to 3.0-3.5, and then dilute the solution to 25%-30%, which is called solution 1. III. Pour the cassava starch treated in Ⅰ into solution 1, mix well, and let stand at room temperature for 10-12 hours; IV. Place in a drying oven at 40-45°C and dry until the moisture content is 5-10% and then take out; V. Grind and sieve, first use deionized water to filter and wash 3-4 times, then use anhydrous ethanol to wash 1-2 times, and then place in a drying oven at 45-50°C to dry, so as to obtain activated starch.

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