Preparation method of high-performance starch-based water and fertilizer saving material

Abstract

The application provides a preparation method of a high-performance starch-based water-and-fertilizer-saving material, which comprises the following steps: adding plant starch with a certain mass into a prepared strong alkali solution under stirring, and then reacting at a certain temperature to obtain an alkaline liquid mixture; then adding inorganic porous material with a certain mass into the alkaline liquid mixture and stirring; finally, mixing organic amide, humic acid, organic acid and metal inorganic salt initiator according to a certain proportion, and then adding into the alkaline liquid mixture for continuous reaction at a certain temperature; and taking out the mixture after reaction, drying, and obtaining the high-performance starch-based water-and-fertilizer-saving material.

Description

Technical Field

[0001] This invention belongs to the field of new chemical materials technology, specifically relating to a method for preparing a high-performance water-saving and fertilizer-saving material. Background Technology

[0002] It is generally believed that inorganic fertilizers are easily absorbed by crops, but also easily lost. In traditional methods, increasing fertilizer application is a key way to achieve high yields, but the large-scale input of fertilizers has led to a series of problems, including decreased fertilizer utilization, reduced economic benefits, increased environmental pollution, and ecological degradation. At the same time, unreasonable application methods further encourage farmers to increase fertilizer input, resulting in excessive nitrogen loss in the soil, with a utilization rate of only 30-40%, compared to 60-70% in developed countries. The fertilizer's effectiveness lasts only about 50 days, causing a serious waste of fertilizer resources. On the other hand, large amounts of fertilizer are carried away by rainwater, causing soil erosion. Furthermore, rainwater contains large amounts of nitrogen, phosphorus, and potassium, which, whether entering groundwater systems or surface water bodies, will cause eutrophication, reducing oxygen content in the water, severely polluting water sources, and leading to serious ecological and environmental incidents.

[0003] Research on controlled / slow-release fertilizers began earlier in foreign countries, primarily in developed nations such as the United States, the United Kingdom, France, Japan, Canada, Israel, Germany, and the Netherlands. The United States developed sulfur-coated urea (SCU) in the 1960s. However, even with the use of sealants and other materials, the sulfur film inevitably suffered defects and damage during manufacturing and use, making it susceptible to microbial decomposition and preventing the release of nutrients as intended. In the 1980s, an organic polymer was added to the surface of the sulfur coating, improving the stability of the controlled-release performance of sulfur-coated urea. In 1964, the United States developed and first industrialized resin-coated controlled / slow-release fertilizers using thermosetting resins as coatings. Subsequently, many countries, including Germany, Canada, and Japan, developed fertilizers using different polymers as coating materials. Japan's research on controlled / slow-release fertilizers began in the 1960s, and its research and application are currently among the world's leading. Japan combines the low water permeability of polyolefin films with the high water permeability of ethylene-ethyl acetate copolymers, achieving control over the release rate by adjusting their ratio. In 1994, Japan developed a process for spray coating using a suspension of polyethylene, polyethylene oxide, nonylphenyl ether and talc. This process can also be used to spray solutions containing corn starch and perchlorate as coatings.

[0004] my country is a major fertilizer user, but research on controlled / slow-release fertilizers started relatively late. In the early 1970s, the Nanjing Institute of Soil Science and the Nanjing Chemical Research Institute of the Chinese Academy of Sciences collaborated to develop coated ammonium bicarbonate with excellent release characteristics, achieving a nitrogen utilization rate of 74% in rice. The Beijing Academy of Agricultural and Forestry Sciences achieved linear and S-shaped release characteristics while improving the biodegradability of the coating. The Institute of Applied Ecology of the Chinese Academy of Sciences achieved good results by adding urease inhibitors and nitrification inhibitors to delay fertilizer release. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a high-performance starch-based water-saving and fertilizer-saving material. This material can simultaneously adsorb fertilizer and moisture from the surrounding soil, migrating it to the vicinity of plant roots, effectively creating a miniature water and fertilizer reservoir. This significantly reduces soil fertilizer loss while greatly enhancing the soil's drought resistance, which is of great importance for afforestation and crop cultivation in arid regions of my country. Furthermore, this water-saving and fertilizer-saving material is biodegradable and does not cause secondary pollution to soil structure or the environment.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this invention includes the following steps: First, a certain mass of plant starch is added to a prepared strong alkaline solution under stirring conditions. After reacting at a certain temperature, an alkaline liquid mixture is obtained. Then, a certain mass of inorganic porous material is added to the alkaline liquid mixture and stirred. Finally, an organic amide, humic acid, organic acid, and metal inorganic salt initiator are mixed in a certain proportion and added to the alkaline liquid mixture, and the reaction continues at a certain temperature. The reacted mixture is then removed, dried, and a high-performance starch-based water-saving and fertilizer-saving material is obtained.

[0007] Furthermore, the above preparation process includes: first, adding 5-50g of plant starch to 50-500g of a 10-30% (w / w) strong alkaline solution under stirring, and reacting at 20-100℃ for 5-100min to obtain an alkaline liquid mixture; then, adding 5-50g of inorganic porous material to the alkaline liquid mixture and stirring for 1-10min; finally, mixing 10-100g of organic amide, humic acid, organic acid, and initiator in a certain proportion and adding them to the alkaline liquid mixture, and continuing the reaction at 20-100℃ for 1-100min. The reacted mixture is then removed, dried, and dehydrated to obtain a high-performance starch-based water-saving and fertilizer-saving material.

[0008] The plant starch is one of corn, wheat, potato, glutinous rice, or sweet potato starch.

[0009] The strong alkaline solution is an aqueous solution of potassium hydroxide.

[0010] The inorganic porous material is one of kaolin, attapulgite, diatomaceous earth, bentonite, and clay.

[0011] The organic amide is one of acrylamide, polyacrylamide, N,N-methylenebisacrylamide, and caprolactam.

[0012] The organic acid is one of acetic acid, acrylic acid, oxalic acid, and citric acid.

[0013] The initiator is one of hydrogen peroxide, sodium peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, and potassium permanganate.

[0014] The mass ratio of the organic amide, humic acid, organic acid, and initiator is 0.05-1:1-50:60-98:0.01-1.

[0015] The water absorption performance of a synthesized high-performance starch-based water-saving and fertilizer-saving material was tested using the method for determining the water absorption (salt water) ratio in the People's Republic of China agricultural industry standard "Water-retaining Agents for Agriculture and Forestry" (NY 886-2010).

[0016] Based on existing research, this invention further adjusts and controls the preparation process of highly absorbent water-saving and fertilizer-saving materials. By screening raw materials, changing preparation steps and methods, optimizing temperature, raw material ratio, and the time progression of each step, a biodegradable starch-based water-saving and fertilizer-saving material has been successfully prepared. The use of plant starch and inorganic porous materials improves the water absorption and retention effect of the material and also increases the natural degradation rate, avoiding damage to soil structure and thus reducing the difficulty of promoting and applying the material. At the same time, the entire preparation process is simple, and the raw materials are mainly low-cost plant starch and inorganic porous materials. It has the advantages of simple operation, easy control, low cost, and high yield, and is particularly suitable for the promotion and use of water-saving and fertilizer-saving materials in agricultural production. Detailed Implementation

[0017] The present invention will be further illustrated below with specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Process conditions or procedures not mentioned in the embodiments and comparative examples are performed according to conventional process conditions or parameters.

[0018] Example 1

[0019] First, 5g of corn starch was added to 50g of a 10% potassium hydroxide solution under stirring and reacted at 20°C for 100min to obtain an alkaline liquid mixture. Then, 5g of kaolin was added to the alkaline liquid mixture and stirred for 10min. Finally, 10g of acrylamide, humic acid, acetic acid, and ammonium persulfate were mixed in a mass ratio of 0.99:1:98:0.01 and added to the alkaline liquid mixture, and the reaction was continued at 20°C for 100min. The reacted mixture was then removed, dried, and dehydrated to obtain a high-performance starch-based water-saving and fertilizer-saving material.

[0020] Example 2

[0021] 50g of wheat starch was added to 500g of a 30% sodium hydroxide solution under stirring and reacted at 100℃ for 5 minutes to obtain an alkaline liquid mixture. Then, 50g of diatomaceous earth was added to the alkaline liquid mixture and stirred for 1 minute. Finally, 100g of polyacrylamide, humic acid, citric acid, and hydrogen peroxide were mixed in a mass ratio of 0.05:10:89:0.95 and added to the alkaline liquid mixture, and the reaction was continued at 100℃ for 1 minute. The reacted mixture was removed, dried, and dehydrated to obtain a high-performance starch-based water-saving and fertilizer-saving material.

[0022] Example 3

[0023] 20g of sweet potato starch was added to 100g of a 20% sodium hydroxide solution under stirring and reacted at 50°C for 40min to obtain an alkaline liquid mixture. Then, 200g of clay was added to the alkaline liquid mixture and stirred for 50min. Finally, 50g of N,N-methylenebisacrylamide, humic acid, acrylic acid, and sodium persulfate were mixed in a mass ratio of 1:38:60:1 and added to the alkaline liquid mixture. The reaction was continued at 50°C for another 50min. The resulting mixture was removed, dried, and dehydrated to obtain a high-performance starch-based water-saving and fertilizer-saving material.

[0024] Example 4

[0025] 40g of glutinous rice starch was added to 400g of a 25% potassium hydroxide solution under stirring and reacted at 80°C for 80min to obtain an alkaline liquid mixture. Then, 40g of bentonite was added to the alkaline liquid mixture and stirred for 8min. Finally, 80g of caprolactam, humic acid, acrylic acid, and potassium persulfate were mixed in a mass ratio of 0.5:34:65:0.5 and added to the alkaline liquid mixture, and the reaction was continued at 80°C for 80min. The reacted mixture was removed, dried, and dehydrated to obtain a high-performance starch-based water-saving and fertilizer-saving material.

[0026] Example 5

[0027] 10g of potato starch was added to 100g of a 15% (w / w) strong alkaline solution under stirring and reacted at 40°C for 20min to obtain an alkaline liquid mixture. Then, 10g of inorganic porous material was added to the alkaline liquid mixture and stirred for 4min. Finally, 20g of polyacrylamide, humic acid, oxalic acid, and potassium permanganate were mixed in a mass ratio of 0.8:30:68.2:1 and added to the alkaline liquid mixture, and the reaction was continued at 40°C for 30min. The reacted mixture was removed, dried, and dehydrated to obtain a high-performance starch-based water-saving and fertilizer-saving material.

[0028] Comparative Example 1

[0029] Purchase a commercially available mainstream brand A baby diaper, disassemble it to obtain 1g of its absorbent material, and test its absorbency using the same method employed in this invention.

[0030] Comparative Example 2

[0031] Purchase a commercially available mainstream brand of baby diapers (brand B), disassemble it to obtain 1g of its absorbent material, and test its absorbency using the same method employed in this invention.

[0032] The water absorption performance of the high-performance starch-based water-saving and fertilizer-saving material obtained in the above embodiments and comparative examples was evaluated according to the method in "Agricultural and Forestry Water Retention Agents" (NY 886-2010). The specific method is as follows:

[0033] Weigh 1g of sample (accurate to 0.01g) and place it in a 2000ml beaker. Add 1000ml of water, stir for 5 minutes, and let stand for 30 minutes to allow the sample to fully absorb water and swell. Transfer the gel-like sample to a standard test sieve of known mass and filter naturally for 10 minutes. Tilt the sieve and filter for another 10 minutes. Weigh the sieve and the gel-like sample. For determining the salt absorption ratio, replace the water in the above test method with a 0.9% NaCl solution.

[0034] The water (salt water) absorption ratio υ is expressed in (g / g) and is calculated using the following formula:

[0035] υ=(m1-m2) / m

[0036] in:

[0037] m1 — The mass of the sample after absorbing water (salt water), in grams;

[0038] m2 — Mass of the blank test, in grams;

[0039] m — the mass of the sample, in grams.

[0040] The arithmetic mean of the parallel measurements is taken as the measurement result, and the result is retained to one decimal place.

[0041] The evaluation results are as follows:

[0042] Example 1: Sample mass 0.98g, water absorption ratio 174.5g / g, salt water (0.9% NaCl) absorption ratio 28.5g / g.

[0043] Example 2: Sample mass 1.03g, water absorption ratio 153.8g / g, salt water (0.9% NaCl) absorption ratio 33.9g / g.

[0044] Example 3: Sample mass 0.99g, water absorption ratio 204.4g / g, salt water (0.9% NaCl) absorption ratio 44.7g / g.

[0045] Example 4: Sample mass 1.02g, water absorption ratio 251.6g / g, salt water (0.9% NaCl) absorption ratio 46.3g / g.

[0046] Example 5: Sample mass 1.01g, water absorption ratio 227.4g / g, salt water (0.9% NaCl) absorption ratio 40.8g / g.

[0047] Comparative Example 1: Sample mass 0.96g, water absorption ratio 201.3g / g, salt water (0.9% NaCl) absorption ratio 48.3g / g.

[0048] Comparative Example 2: Sample mass 1.01g, water absorption ratio 217.3g / g, salt water (0.9% NaCl) absorption ratio 44.6g / g.

[0049] The results show that the high-performance starch-based water-saving and fertilizer-saving material prepared using some embodiments of the present invention has water absorption performance comparable to that of the water-absorbing materials in two mainstream brands of baby diapers on the market. Furthermore, the starch-based water-saving and fertilizer-saving material prepared using the method of the present invention has the characteristics of being biodegradable and low-cost due to the addition of plant starch and inorganic porous materials, giving it a significant advantage in agricultural applications.

Claims

1. A method for preparing a high-performance starch-based water-saving and fertilizer-saving material, comprising the following steps: First, 5-50g of plant starch is added to 50-500g of a 10-30% (w / w) strong alkaline solution under stirring conditions and reacted at 20-100℃ for 5-100min to obtain an alkaline liquid mixture. Then, 5-50g of inorganic porous material is added to the alkaline liquid mixture and stirred for 1-10min. Finally, 10-100g of organic amide, humic acid, organic acid, and initiator are mixed in a certain proportion and added to the alkaline liquid mixture, and the reaction is continued at 20-100℃ for 1-100min. The reacted mixture is then removed, dried, and dehydrated to obtain a high-performance starch-based water-saving and fertilizer-saving material.

2. The method for preparing a high-performance starch-based water-saving and fertilizer-saving material according to claim 1, characterized in that, The plant starch is one of corn, wheat, potato, glutinous rice, or sweet potato starch.

3. The method for preparing a high-performance starch-based water-saving and fertilizer-saving material according to claim 1, characterized in that, The strong alkaline solution is an aqueous solution of potassium hydroxide.

4. The method for preparing a high-performance starch-based water-saving and fertilizer-saving material according to claim 1, characterized in that, The inorganic porous material is one of kaolin, attapulgite, diatomaceous earth, bentonite, and clay.

5. The method for preparing a high-performance starch-based water-saving and fertilizer-saving material according to claim 1, characterized in that, The organic amide is one of acrylamide, polyacrylamide, N,N-methylenebisacrylamide, and caprolactam.

6. The method for preparing a high-performance starch-based water-saving and fertilizer-saving material according to claim 1, characterized in that, The organic acid is one of acetic acid, acrylic acid, oxalic acid, and citric acid.

7. The method for preparing a high-performance starch-based water-saving and fertilizer-saving material according to claim 1, characterized in that, The initiator is one of hydrogen peroxide, peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, and potassium permanganate.

8. The method for preparing a high-performance starch-based water-saving and fertilizer-saving material according to claim 1, characterized in that, The mass ratio of the organic amide, humic acid, organic acid, and initiator is 0.05-1:1-50:60-98:0.01-1.