Preparation method of nano-selenium fertilizer

Abstract

The preparation method comprises the following steps: S1, raw material preparation: selecting sodium selenite as a selenium source, and preparing konjac glucomannan and vitamin C as reducing agents at the same time; the molar ratio of the selected sodium selenite to the selected konjac glucomannan to the selected vitamin C is 1: (0.5-2): (2-5); s2, solution preparation: dissolving sodium selenite in deionized water to prepare a sodium selenite solution with the concentration of 0.1-0.5 mol / L; according to the preparation method of the nano-selenium fertilizer, through the nano-selenium fertilizer prepared through the steps S1 to S6, the particle size of nano-selenium particles can be distributed between 30 nm and 80 nm, so that the nano-selenium fertilizer has good dispersity and stability and is conveniently and efficiently applied to agricultural production, and the effect of improving the selenium absorption and utilization efficiency of crops is achieved; and the preparation method is simple and easy to implement, low in cost, green and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizer processing, and in particular to a method for preparing nano-selenium fertilizer. Background Art

[0002] Selenium fertilizer is a fertilizer that can increase the selenium content in agricultural products. It can promote crop growth, increase crop yield and disease resistance. The main working principle of selenium fertilizer is to enrich selenium in the edible parts of crops through root absorption or foliar spraying, thereby achieving the goal of selenium-enriched agricultural products. According to different fertilization methods, selenium fertilizer can be divided into basal selenium-enriched fertilizer and foliar selenium-enriched fertilizer. Basal selenium-enriched fertilizer increases the selenium content in plants by increasing the selenium content in the soil, while foliar selenium-enriched fertilizer increases the selenium content in plants by supplementing selenium to the leaves.

[0003] Selenium itself is a trace element necessary for the growth of plants and animals, and plays an important role in improving crop resistance and improving the quality of agricultural products. Nano-selenium has unique advantages in the agricultural field due to its small particle size, large specific surface area, high biological activity and low toxicity. However, existing methods for preparing nano-selenium often have problems such as complex processes, high costs, easy introduction of impurities during the preparation process, or being environmentally unfriendly, which limits the large-scale production and application of nano-selenium fertilizers; that is, it is difficult to ensure the dispersion and stability of the particle size of nano-selenium particles, which is not conducive to improving the efficiency of crops' absorption and utilization of selenium, and is not conducive to improving the quality of agricultural products. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing a nano-selenium fertilizer, which solves the problems raised in the above background technology.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing nano-selenium fertilizer comprises the following steps: S1: Raw material preparation: Sodium selenite is selected as a selenium source, and konjac glucomannan and vitamin C are prepared as reducing agents; the molar ratio of sodium selenite, konjac glucomannan and vitamin C is selected to be 1: (0.5-2): (2-5); S2: Solution preparation: Sodium selenite is dissolved in deionized water to prepare a sodium selenite solution with a concentration of 0.1-0.5 mol / L, and then konjac glucomannan is slowly added to an appropriate amount of deionized water, and stirred continuously for 0-60 minutes in a water bath at 60-80°C until it is completely dissolved to prepare a konjac glucomannan solution with a concentration of 0.5%-2% (mass volume ratio), and vitamin C is dissolved in deionized water to prepare a vitamin C solution with a concentration of 0.2-1 mol / L; S3: Reaction system construction and reaction: Under stirring conditions, the sodium selenite solution is slowly added dropwise to the konjac glucomannan solution. After the addition is completed, stirring is continued for 10-20 minutes to mix the solution evenly. Then the vitamin C solution is added dropwise to the above mixed solution. The reaction system is reacted at room temperature (2-25°C). Stirring is continued during the reaction process. The reaction time is 1-3 hours. S4: Aging treatment: After the reaction is completed, the obtained reaction solution is aged at room temperature for 2-48 hours to further mature and stabilize the nano-selenium particles; S5: Centrifugation: The aged solution is centrifuged at a speed of 8000-12000 rpm for 10-20 minutes, and then the precipitate is collected; S6: Drying treatment: Dry the washed precipitate in a vacuum drying oven at a drying temperature of 40-60°C for 12-24 hours to obtain nano-selenium powder. Mix the nano-selenium powder with an appropriate amount of an inert carrier (such as light calcium carbonate, diatomaceous earth, etc.) at a mass ratio of 1:(5-10) to obtain a finished nano-selenium fertilizer.

[0006] Preferably, in step S1, the purity of the selected sodium selenite is not less than 98%.

[0007] Preferably, in step S1, the molecular weight of the selected konjac glucomannan should be in the range of 500,000-2,000,000 Daltons, and the konjac glucomannan can also be replaced by other natural polysaccharides.

[0008] Preferably, in step S3, during the reaction process of 1-3 hours, the color of the solution gradually changes from colorless to orange-red, indicating that nano-selenium begins to be generated and gradually aggregates.

[0009] Preferably, in step S5, the precipitation is washed 2-3 times with anhydrous ethanol and deionized water respectively to remove unreacted impurities and by-products.

[0010] Preferably, the specific execution time of the drying process in step S6 depends on the setting of the drying temperature. Within the set threshold range, if the drying temperature is set higher, the drying time is correspondingly shortened, that is, within the preset threshold range, the drying temperature and the drying time are inversely proportional.

[0011] Preferably, the method further comprises the following specific steps: S201: Accurately weigh 1.25g sodium selenite (purity 99%) and dissolve it in 25ml deionized water to prepare a 0.2mol / L sodium selenite solution. S202: Take 1 g of konjac glucomannan and dissolve it in 200 ml of deionized water under stirring at 70° C. in a water bath for 40 minutes to prepare a 0.5% konjac glucomannan solution; S203: Weigh 1.76 g of vitamin C and dissolve it in 10 ml of deionized water to prepare a 1 mol / L vitamin C solution; S204: slowly adding the sodium selenite solution dropwise to the konjac glucomannan solution, stirring for 15 minutes, then adding the vitamin C solution dropwise, and reacting at room temperature for 2 hours; S205: After the reaction is completed, the mixture is allowed to stand for 36 hours, and then centrifuged at 10,000 rpm for 15 minutes to collect the precipitate. The precipitate is washed with anhydrous ethanol and deionized water three times each; S206: Dry the washed precipitate in a vacuum drying oven at 50° C. for 18 hours to obtain nano-selenium powder, and then take 1 g of the nano-selenium powder and mix it evenly with 6 g of light calcium carbonate to obtain a nano-selenium fertilizer.

[0012] Preferably, the method further comprises the following specific steps: S301: dissolve 2.5 g of sodium selenite in 50 ml of deionized water to prepare a 0.1 mol / L sodium selenite solution; S302: dissolving 2 g of konjac glucomannan in 400 ml of deionized water in a 60° C. water bath with stirring for 60 minutes to prepare a 0.5% konjac glucomannan solution; S303: dissolving 3.52 g of vitamin C in 20 ml of deionized water to prepare a 0.5 mol / L vitamin C solution; S304: adding the sodium selenite solution dropwise to the konjac glucomannan solution and stirring for 10 minutes, then adding the vitamin C solution and reacting at room temperature for 3 hours; S305: aging for 48 hours, centrifuging at 8000 rpm for 20 minutes, and washing the precipitate twice with anhydrous ethanol and deionized water; S306: vacuum drying at 40° C. for 24 hours to obtain nano-selenium powder, and mixing it with 8 g of diatomaceous earth to prepare nano-selenium fertilizer.

[0013] Preferably, the method further comprises the following specific steps: S401: Dissolve 0.625 g of sodium selenite in 12.5 ml of deionized water to obtain a 0.5 mol / L solution; S402: Dissolve 0.5 g of konjac glucomannan in 100 ml of deionized water in a water bath at 80°C for 30 minutes to obtain a 0.5% solution; S403: Dissolve 0.88 g of vitamin C in 5 ml of deionized water to prepare a 0.2 mol / L solution; S404: mixing the sodium selenite solution and the konjac glucomannan solution and stirring for 20 minutes, then adding the vitamin C solution and reacting for 1 hour; S405: Aging for 24 hours, centrifuging at 12000 rpm for 10 minutes, washing the precipitate 3 times, and vacuum drying at 60° C. for 12 hours to obtain nano-selenium powder, which is mixed with 5 g of light calcium carbonate to form a nano-selenium fertilizer.

[0014] Compared with the prior art, the beneficial effects of the present invention are: the preparation method of the nano-selenium fertilizer can make the particle size distribution of the nano-selenium particles between 30-80nm, so that it has good dispersibility and stability, is convenient for efficient application in agricultural production, and achieves the effect of improving the absorption and utilization efficiency of crops for selenium elements, greatly improving the quality of agricultural products, and the preparation method is simple, easy, low-cost, and green and environmentally friendly. DETAILED DESCRIPTION

[0015] The technical solution of the present invention will be clearly and completely described below through embodiments.

[0016] Embodiment 1: A method for preparing nano-selenium fertilizer, comprising the following steps: S1: Raw material preparation: Sodium selenite is selected as a selenium source, and konjac glucomannan and vitamin C are prepared as reducing agents; the molar ratio of sodium selenite, konjac glucomannan and vitamin C is selected to be 1: (0.5-2): (2-5); S2: Solution preparation: Sodium selenite is dissolved in deionized water to prepare a sodium selenite solution with a concentration of 0.1-0.5 mol / L, and then konjac glucomannan is slowly added to an appropriate amount of deionized water, and stirred continuously for 0-60 minutes in a water bath at 60-80°C until it is completely dissolved to prepare a konjac glucomannan solution with a concentration of 0.5%-2% (mass volume ratio), and vitamin C is dissolved in deionized water to prepare a vitamin C solution with a concentration of 0.2-1 mol / L; S3: Reaction system construction and reaction: Under stirring conditions, the sodium selenite solution is slowly added dropwise to the konjac glucomannan solution. After the addition is completed, stirring is continued for 10-20 minutes to mix the solution evenly. Then the vitamin C solution is added dropwise to the above mixed solution. The reaction system is reacted at room temperature (2-25°C). Stirring is continued during the reaction process. The reaction time is 1-3 hours. S4: Aging treatment: After the reaction is completed, the obtained reaction solution is aged at room temperature for 2-48 hours to further mature and stabilize the nano-selenium particles; S5: Centrifugation: The aged solution is centrifuged at a speed of 8000-12000 rpm for 10-20 minutes, and then the precipitate is collected; S6: Drying treatment: Dry the washed precipitate in a vacuum drying oven at a drying temperature of 40-60°C for 12-24 hours to obtain nano-selenium powder. Mix the nano-selenium powder with an appropriate amount of an inert carrier (such as light calcium carbonate, diatomaceous earth, etc.) at a mass ratio of 1:(5-10) to obtain a finished nano-selenium fertilizer.

[0017] In the present invention, in step S1, the purity of the selected sodium selenite is not less than 98%.

[0018] In the present invention, in step S1, the molecular weight of the selected konjac glucomannan should be in the range of 500,000-2,000,000 Daltons, and the konjac glucomannan can also be replaced by other natural polysaccharides.

[0019] In the present invention, in step S3, during the reaction process of 1-3 hours, the color of the solution gradually changes from colorless to orange-red, indicating that nano-selenium begins to be generated and gradually aggregates.

[0020] In the present invention, in step S5, the precipitation is washed 2-3 times with anhydrous ethanol and deionized water respectively to remove unreacted impurities and by-products.

[0021] In the present invention, the specific execution time of the drying process in step S6 depends on the setting of the drying temperature. Within the set threshold range, if the drying temperature is set higher, the drying time is correspondingly shortened, that is, within the preset threshold range, the drying temperature and the drying time are inversely proportional.

[0022] The present invention also includes the following specific steps: S201: Accurately weigh 1.25g sodium selenite (purity 99%) and dissolve it in 25ml deionized water to prepare a 0.2mol / L sodium selenite solution. S202: Take 1 g of konjac glucomannan and dissolve it in 200 ml of deionized water under stirring at 70° C. in a water bath for 40 minutes to prepare a 0.5% konjac glucomannan solution; S203: Weigh 1.76 g of vitamin C and dissolve it in 10 ml of deionized water to prepare a 1 mol / L vitamin C solution; S204: slowly adding the sodium selenite solution dropwise to the konjac glucomannan solution, stirring for 15 minutes, then adding the vitamin C solution dropwise, and reacting at room temperature for 2 hours; S205: After the reaction is completed, the mixture is allowed to stand for 36 hours, and then centrifuged at 10,000 rpm for 15 minutes to collect the precipitate. The precipitate is washed with anhydrous ethanol and deionized water three times each; S206: Dry the washed precipitate in a vacuum drying oven at 50° C. for 18 hours to obtain nano-selenium powder, and then take 1 g of the nano-selenium powder and mix it evenly with 6 g of light calcium carbonate to obtain a nano-selenium fertilizer.

[0023] Embodiment 2: The difference in this embodiment is that it also includes the following specific steps: S301: dissolve 2.5 g of sodium selenite in 50 ml of deionized water to prepare a 0.1 mol / L sodium selenite solution; S302: dissolving 2 g of konjac glucomannan in 400 ml of deionized water in a 60° C. water bath with stirring for 60 minutes to prepare a 0.5% konjac glucomannan solution; S303: dissolving 3.52 g of vitamin C in 20 ml of deionized water to prepare a 0.5 mol / L vitamin C solution; S304: adding the sodium selenite solution dropwise to the konjac glucomannan solution and stirring for 10 minutes, then adding the vitamin C solution and reacting at room temperature for 3 hours; S305: aging for 48 hours, centrifuging at 8000 rpm for 20 minutes, and washing the precipitate twice with anhydrous ethanol and deionized water; S306: Drying in vacuum at 40°C for 24 hours to obtain nano-selenium powder, and mixing with 8g of diatomaceous earth to prepare nano-selenium fertilizer Embodiment 3: The difference in this embodiment is that it also includes the following specific steps: S401: Dissolve 0.625 g of sodium selenite in 12.5 ml of deionized water to obtain a 0.5 mol / L solution; S402: Dissolve 0.5 g of konjac glucomannan in 100 ml of deionized water in a water bath at 80°C for 30 minutes to obtain a 0.5% solution; S403: Dissolve 0.88 g of vitamin C in 5 ml of deionized water to prepare a 0.2 mol / L solution; S404: mixing the sodium selenite solution and the konjac glucomannan solution and stirring for 20 minutes, then adding the vitamin C solution and reacting for 1 hour; S405: Aging for 24 hours, centrifuging at 12000 rpm for 10 minutes, washing the precipitate 3 times, and vacuum drying at 60° C. for 12 hours to obtain nano-selenium powder, which is mixed with 5 g of light calcium carbonate to form a nano-selenium fertilizer.

[0024] The nano-selenium fertilizer prepared by the above embodiment has a particle size distribution of nano-selenium particles between 30-80 nm, has good dispersibility and stability, and can be effectively applied to agricultural production to improve the absorption and utilization efficiency of crops for selenium and improve the quality of agricultural products.

[0025] In practical applications, the application amount and method of nano-selenium fertilizer can be adjusted according to the needs of different crops for selenium. For example, for vegetable crops, 1-2 kg of nano-selenium fertilizer can be applied per mu; for grain crops, 0.5-1 kg per mu; it can be applied by base fertilizer, topdressing or foliar spraying to achieve the best fertilization effect.

[0026] 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 method for preparing nano-selenium fertilizer, characterized in that: The following steps are involved: S1: Raw material preparation: Sodium selenite is selected as a selenium source, and konjac glucomannan and vitamin C are prepared as reducing agents; the molar ratio of sodium selenite, konjac glucomannan and vitamin C is selected to be 1: (0.5-2): (2-5); S2: Solution preparation: Sodium selenite is dissolved in deionized water to prepare a sodium selenite solution with a concentration of 0.1-0.5 mol / L, and then konjac glucomannan is slowly added to an appropriate amount of deionized water, and stirred continuously for 0-60 minutes in a water bath at 60-80°C until it is completely dissolved to prepare a konjac glucomannan solution with a concentration of 0.5%-2% (mass volume ratio), and vitamin C is dissolved in deionized water to prepare a vitamin C solution with a concentration of 0.2-1 mol / L; S3: Reaction system construction and reaction: Under stirring conditions, the sodium selenite solution is slowly added dropwise to the konjac glucomannan solution. After the addition is completed, stirring is continued for 10-20 minutes to mix the solution evenly. Then, the vitamin C solution is added dropwise to the mixed solution. The reaction system is reacted at room temperature. Stirring is continued during the reaction process. The reaction time is 1-3 hours. S4: Aging treatment: After the reaction is completed, the obtained reaction solution is aged at room temperature for 2-48 hours to further mature and stabilize the nano-selenium particles; S5: Centrifugation: The aged solution is centrifuged at a speed of 8000-12000 rpm for 10-20 minutes, and then the precipitate is collected; S6: Drying treatment: Dry the washed precipitate in a vacuum drying oven at a drying temperature of 40-60°C for 12-24 hours to obtain nano-selenium powder. Mix the nano-selenium powder with an appropriate amount of inert carrier in a mass ratio of 1:(5-10) to obtain a finished nano-selenium fertilizer.

2. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: In step S1, the purity of the selected sodium selenite is not less than 98%.

3. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: In step S1, the molecular weight of the selected konjac glucomannan should be in the range of 500,000-2,000,000 Daltons, and the konjac glucomannan can also be replaced by other natural polysaccharides.

4. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: In step S3, during the reaction process of 1-3 hours, the color of the solution gradually changes from colorless to orange-red, indicating that nano-selenium begins to be generated and gradually aggregates.

5. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: In the step S5, the precipitation is washed 2-3 times with anhydrous ethanol and deionized water respectively to remove unreacted impurities and by-products.

6. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: The specific execution time of the drying process in step S6 depends on the setting of the drying temperature. Within the set threshold range, if the drying temperature is set higher, the drying time is correspondingly shortened, that is, within the preset threshold range, the drying temperature and the drying time are inversely proportional.

7. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: The following specific steps are also included: S201: Accurately weigh 1.25g sodium selenite (purity 99%) and dissolve it in 25ml deionized water to prepare a 0.2mol / L sodium selenite solution. S202: Take 1 g of konjac glucomannan and dissolve it in 200 ml of deionized water under stirring at 70° C. in a water bath for 40 minutes to prepare a 0.5% konjac glucomannan solution; S203: Weigh 1.76 g of vitamin C and dissolve it in 10 ml of deionized water to prepare a 1 mol / L vitamin C solution; S204: slowly adding the sodium selenite solution dropwise to the konjac glucomannan solution, stirring for 15 minutes, then adding the vitamin C solution dropwise, and reacting at room temperature for 2 hours; S205: After the reaction is completed, the mixture is allowed to stand for 36 hours, and then centrifuged at 10,000 rpm for 15 minutes to collect the precipitate. The precipitate is washed with anhydrous ethanol and deionized water three times each; S206: Dry the washed precipitate in a vacuum drying oven at 50° C. for 18 hours to obtain nano-selenium powder, and then take 1 g of the nano-selenium powder and mix it evenly with 6 g of light calcium carbonate to obtain a nano-selenium fertilizer.

8. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: The following specific steps are also included: S301: dissolve 2.5 g of sodium selenite in 50 ml of deionized water to prepare a 0.1 mol / L sodium selenite solution; S302: dissolving 2 g of konjac glucomannan in 400 ml of deionized water in a 60° C. water bath with stirring for 60 minutes to prepare a 0.5% konjac glucomannan solution; S303: dissolving 3.52 g of vitamin C in 20 ml of deionized water to prepare a 0.5 mol / L vitamin C solution; S304: adding the sodium selenite solution dropwise to the konjac glucomannan solution and stirring for 10 minutes, then adding the vitamin C solution and reacting at room temperature for 3 hours; S305: aging for 48 hours, centrifuging at 8000 rpm for 20 minutes, and washing the precipitate twice with anhydrous ethanol and deionized water; S306: vacuum drying at 40° C. for 24 hours to obtain nano-selenium powder, and mixing it with 8 g of diatomaceous earth to prepare nano-selenium fertilizer.

9. The method for preparing a nano-selenium fertilizer according to claim 1, characterized in that: The following specific steps are also included: S401: Dissolve 0.625 g of sodium selenite in 12.5 ml of deionized water to obtain a 0.5 mol / L solution; S402: Dissolve 0.5 g of konjac glucomannan in 100 ml of deionized water in a water bath at 80°C for 30 minutes to obtain a 0.5% solution; S403: Dissolve 0.88 g of vitamin C in 5 ml of deionized water to prepare a 0.2 mol / L solution; S404: mixing the sodium selenite solution and the konjac glucomannan solution and stirring for 20 minutes, then adding the vitamin C solution and reacting for 1 hour; S405: Aging for 24 hours, centrifuging at 12000 rpm for 10 minutes, washing the precipitate 3 times, and vacuum drying at 60° C. for 12 hours to obtain nano-selenium powder, which is mixed with 5 g of light calcium carbonate to form a nano-selenium fertilizer.