Preparation method of chelated medium trace elements

Abstract

The invention discloses a preparation method of chelated medium trace elements. People gradually know that medium trace elements play a very important role in growth and development of plants, but most medium trace elements can be combined with carbonate ions in soil to form indissolvable substances which are difficult to absorb and utilize by the plants when inorganic salt is directly applied. The chelated medium trace elements have the advantages that the chelated medium trace elements can stably exist in the soil in an ion form for a long time, are relatively high in solubility, are more easily absorbed and utilized by plants and the like. The defects of the macroelement compound fertilizer in use and the conventional medium trace element compound fertilizer are analyzed. The invention introduces a chelated medium trace element production technology, researches the influence of different chelating agents on the physical and chemical properties of medium trace element chelation, has a very wide application prospect, and provides data guidance for practical industrial production of chelated medium trace elements.

Description

Technical Field

[0001] The present invention relates to the technical field of chelating agents, and particularly to a preparation method for chelating medium and trace elements. Background Art

[0002] As is well known, nitrogen, phosphorus, and potassium play an indispensable role in the growth process of plants, providing the nutrients required for plants to complete various life activities, which are also the main elements of our chemical fertilizers. However, medium and trace elements such as Ca, Mg, S, Cu, Zn, Mn, Mo, Fe, B, Cl, etc. also participate in various life activities of plants, are essential nutrient elements for plants, and play a crucial role in the process of plants completing various life activities. During the growth process of plants, the amount of these medium and trace elements required by plants is much lower than that of nitrogen, phosphorus, and potassium. However, if one or several of these elements are lacking, crops may exhibit results such as retarded growth and development, yellowing of leaves, reduced yield, easy fruit drop, and even withering and death.

[0003] With the progress made in world agricultural technology in practice, the application of chelated fertilizers has attracted more and more attention. Due to its good water solubility, stable existence in the form of ions for a long time on the leaf surface or in the soil, being more conducive to plant absorption, remaining stable under different pH conditions, and having no toxic side effects, it is favored by people, and well solves various problems faced by inorganic salt fertilizers. Medium and trace element chelated fertilizers are prepared by reacting an organic chelating agent with medium and trace elements such as calcium, magnesium, iron, zinc, copper, etc. at a certain pH condition in a certain proportion, so that metal ions and organic chelates form a cyclic coordination compound, which is convenient for plant absorption and utilization. Moreover, the ion group formed by organic cations and the chelating agent is negatively charged and will not be fixed by the soil, and can continuously and effectively provide nutrients for crops. Therefore, applying chelated medium and trace element compound fertilizers can effectively improve the utilization rate of fertilizers by crops, ensure the nutrients required for crop growth while reducing the application of chemical fertilizers, and thus achieve the purpose of reducing fertilizer use and increasing efficiency.

[0004] Metal atoms or ions react with ligands containing two or more coordinating atoms to form a complex with a cyclic structure, and this complex is called a chelate. The ligand substance that can form a chelate is called a chelating agent, also known as a complexing agent. Due to the ring formation of the chelating agent, the chelate is more stable than non-chelated coordination compounds with similar composition and structure. However, for crop absorption, the selection of the chelating agent is also very important. It is not ideal if the stability of the chelate is too high or too low. If the stability is too high, it is not conducive to crop absorption, which in turn affects the absorption of metal ions by crops; if the stability is too low, the metal ions will be released before being absorbed by the crops. Therefore, the selection of the chelating agent is particularly important. Therefore, it is an urgent problem to be solved in the present invention to develop a preparation method of chelated medium and trace elements that is resistant to acids and alkalis and can stably exist in the air for a long time. Summary of the Invention

[0005] The purpose of the invention is to provide a preparation method of chelated medium and trace elements, aiming to solve the problems existing in the background technology.

[0006] In order to achieve the above technical purpose, the present invention mainly adopts the following technical solutions: In the first aspect, the present invention selects some chelating agents, and the chelating agents are citric acid, sodium tartrate and disodium ethylenediaminetetraacetate (EDTA-2Na).

[0007] In the second aspect, the present invention provides a preparation method of chelated medium and trace elements as described in the first aspect, which is obtained by uniformly mixing the chelating agent and the selected metal salt in a certain proportion under a certain pH condition.

[0008] In the third aspect, the present invention provides a preparation method of chelated medium and trace elements as described in the second aspect, which can be applied to some crops in the case of "element deficiency" and can be applied to liquid fertilizer products.

[0009] Compared with the prior art, the present invention has the following advantages: 1. For the preparation method of chelated medium and trace elements of the present invention, experimental results show that the stability of the chelated medium and trace elements in the solution has been significantly improved and can still stably exist under specific conditions.

[0010] 2. The preparation method of chelated medium and trace elements of the present invention increases the effective medium and trace element concentration in the soil, which has a positive and profound impact on various life activities of crops.

[0011] 3. The preparation method of chelated medium and trace elements of the present invention has easy-to-control production conditions and low energy consumption, and is convenient for popularization in actual production.

[0012] 4. It provides a new measure to respond to the country's "reducing fertilizer application and increasing efficiency". Detailed Embodiments

[0013] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The reagents not specifically described in detail in the present application are all conventional reagents and can be obtained from commercial channels; the methods not specifically described in detail are all conventional experimental methods and can be learned from the prior art.

[0014] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence, nor do they play a substantial limiting role on the subsequent technical features. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those described. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0015] The present invention will be further described in detail below through specific examples.

[0016] Example 1 Preparation of chelated calcium.

[0017] Weigh equimolar amounts of chelating agents respectively, dissolve them in water, adjust the pH to 6.0 - 8.0, add equimolar amounts of anhydrous calcium chloride, and stir and mix evenly to obtain chelated calcium.

[0018] Example 2 Preparation of chelated magnesium.

[0019] Weigh equimolar amounts of chelating agents respectively, dissolve them in water, adjust the pH to 6.0 - 8.0, add equimolar amounts of magnesium sulfate heptahydrate, and stir and mix evenly to obtain chelated magnesium.

[0020] Example 3 Preparation of chelated copper.

[0021] Weigh equimolar amounts of chelating agents respectively, dissolve them in water, adjust the pH to 6.0 - 8.0, add equimolar amounts of copper sulfate pentahydrate, and stir and mix evenly to obtain chelated copper.

[0022] Example 4 Preparation of chelated zinc.

[0023] Weigh out equimolar amounts of the chelating agent respectively, dissolve it in water, adjust the pH to 6.0 - 8.0, add equimolar amounts of zinc sulfate monohydrate, and stir to mix evenly to obtain chelated zinc.

[0024] Example 5 Preparation of chelated manganese.

[0025] Weigh out equimolar amounts of the chelating agent respectively, dissolve it in water, adjust the pH to 6.0 - 8.0, add equimolar amounts of manganese sulfate monohydrate, and stir to mix evenly to obtain chelated manganese.

[0026] Example 6 Preparation of chelated ferrous.

[0027] Weigh out equimolar amounts of the chelating agent respectively, dissolve it in water, adjust the pH to 6.0 - 8.0, add equimolar amounts of ferrous sulfate heptahydrate, and stir to mix evenly to obtain chelated ferrous.

[0028] Test example I. Experimental part 1. Materials Chelating agent A, citric acid monohydrate; chelating agent B, potassium sodium tartrate; chelating agent C, disodium ethylenediaminetetraacetate (EDTA - 2Na). Anhydrous calcium chloride, magnesium sulfate heptahydrate, copper sulfate pentahydrate, ferrous sulfate heptahydrate, zinc sulfate monohydrate, manganese sulfate monohydrate, ascorbic acid, sodium carbonate decahydrate, ammonia water, anhydrous ethanol.

[0029] 2. Instruments The main instruments used in the experiment are magnetic heating stirrer, electronic balance, rotary evaporator, vacuum drying oven, ultrasonic instrument.

[0030] 3. Experimental method (1) Weigh out a certain amount of chelating agent A, citric acid monohydrate, into a beaker, add water until it is just completely dissolved, adjust the pH value of the system with ammonia water, add a certain amount of anhydrous calcium chloride, magnesium sulfate heptahydrate, copper sulfate pentahydrate, ferrous sulfate heptahydrate, zinc sulfate monohydrate, manganese sulfate monohydrate respectively. After the solids are completely dissolved using the ultrasonic instrument, after a period of time, obtain the mother liquor containing the chelation product. If a solution is needed for use, no subsequent operation is required. Concentrate a certain amount of the mother liquor to a saturated solution through a rotary evaporator, add anhydrous ethanol according to a certain volume ratio, a large amount of precipitation will occur. After standing for a period of time, filter it with a suction flask, wash the precipitate several times with anhydrous ethanol, transfer the precipitate into a beaker and place it in a vacuum drying oven at 50 °C for 12 h. After the solid cools, grind it into powder to obtain different metal chelates chelated by citric acid.

[0031] (2)Weigh a certain amount of chelating agent B, potassium sodium tartrate, into a beaker and add water until it is just completely dissolved. Weigh a certain amount of anhydrous calcium chloride, magnesium sulfate heptahydrate, copper sulfate pentahydrate, ferrous sulfate heptahydrate, zinc sulfate monohydrate, and manganese sulfate monohydrate into a beaker. After the solids are completely dissolved using an ultrasonic instrument, add them to the above solution of chelating agent B respectively, and a large amount of precipitate is produced. Transfer the precipitate to a beaker and dry it in a vacuum drying oven at 50 °C for 12 h. After the solid cools, grind it into powder to obtain different metal chelates chelated by tartaric acid.

[0032] (3)The experimental method of chelating agent C is the same as that of chelating agent B.

[0033] II. Results and Analysis 1. Evaluation of the chelating effects of different chelating agents on different metal ions According to the chelating solutions obtained in Examples 1 - 6, stir them evenly. Take 1 mL of the mother liquor and dilute it with water to 10 mL. The results are shown in Table 1. It can be seen from Table 1 that to make calcium exist in the form of ions in the soil, chelating agent EDTA-2Na should be used; for manganese to exist in the form of ions, sodium tartrate cannot be used; while for magnesium, copper, iron, and zinc, all three chelating agents can achieve the solubility of the chelates.

[0034] 2. Evaluation of the chelation rationalization properties of different chelating agents on different metal elements To verify whether the metal ions in the obtained solution form complexes with the chelating agent, we use 0.1 mol / L sodium carbonate solution to simulate the anion environment in the soil. Drop the sodium carbonate solution into the above soluble experimental group solutions respectively, and set the unchelated inorganic salts as the control group. Among them, the mass of the inorganic salts in the control group is 20 mg each, and 1 mL of water is added. The results are shown in Table 2. It can be seen from Table 2 that when the sodium carbonate solution is dropped into the soluble experimental group, there is no obvious change in the solution; while in the blank group, precipitation occurs after adding the sodium carbonate solution. This shows that a coordination reaction occurs between the metal ions and the chelating agent, which hinders the combination of metal ions with carbonate ions and makes them exist in the form of ions in the solution.

[0035] 3. Thermal stability test of chelated medium and trace elements To explore the stability of chelated medium and trace elements at different temperatures, take 10 mL of EDTA-calcium and other citric acid chelates respectively, dilute them with water to 50 mL, add 1 g of sodium carbonate decahydrate solid respectively. After complete dissolution, carry out water bath heating at different temperatures. The results are shown in Table 3. It can be seen from Table 3 that when the temperature of ferrous citrate chelate exceeds 60 o °C, precipitation occurs, indicating that its coordination bond is broken and ferrous ions are released, and ferrous ions combine with carbonate ions to form precipitation; while when the temperature is lower than 50 oC. The metal ions and chelating agents are combined through coordination bonds and can exist stably in a sodium carbonate solution. When sodium carbonate is added to a solution of magnesium citrate, copper citrate, zinc citrate, manganese citrate, and EDTA-calcium and heated to 70 o C, no precipitate is formed, indicating good thermal stability.

[0036] In summary, the test results show that different chelated medium and trace elements are prepared by a simple method, and it is experimentally verified that they can exist stably in a Na2CO3 solution and are very stable within a relatively wide temperature range, providing the possibility for the application of chelated medium and trace elements. The use of medium and trace element chelating agents can effectively improve the utilization rate of metal elements in fertilizers and the absorption rate of fertilizers by crops, meeting the current requirements of "high yield, high quality, and green" in Chinese agriculture; for enterprises, on the premise of ensuring crop yield and quality, it reduces input costs and realizes "reducing fertilizer use and increasing efficiency", providing theoretical support for the popularization and application of this technology.

[0037] As described above, the above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application.

[0038] Table 1 Dissolution conditions of different metal chelates Serial number Composition Phenomenon after adding water Serial number Composition Phenomenon after adding water 1 Calcium chloride + Citric acid Insoluble 10 Ferrous sulfate heptahydrate + Citric acid Soluble 2 Calcium chloride + Sodium tartrate Insoluble 11 Ferrous sulfate heptahydrate + Sodium tartrate Soluble 3 Calcium chloride + EDTA-2Na Soluble 12 Ferrous sulfate heptahydrate + EDTA-2Na Soluble 4 Magnesium sulfate heptahydrate + Citric acid Soluble 13 Zinc sulfate monohydrate + Citric acid Soluble 5 Magnesium sulfate heptahydrate + Sodium tartrate Soluble 14 Zinc sulfate monohydrate + Sodium tartrate Soluble 6 Magnesium sulfate heptahydrate + EDTA-2Na Soluble 15 Zinc sulfate monohydrate + EDTA-2Na Soluble 7 Copper sulfate pentahydrate + Citric acid Soluble 16 Manganese sulfate monohydrate + Citric acid Soluble 8 Copper sulfate pentahydrate + Sodium tartrate Soluble 17 Manganese sulfate monohydrate + Sodium tartrate Insoluble 9 Copper sulfate pentahydrate + EDTA-2Na Soluble 18 Manganese sulfate monohydrate + EDTA-2Na Soluble Table 2 Verification of whether chelation occurs for metal ions using a Na2CO3 solution Serial number Composition Phenomenon Serial number Composition Phenomenon Serial number Composition Phenomenon 1 <![CDATA[EDTA-Calcium + Na2CO3]]> No phenomenon 8 <![CDATA[Copper tartrate + Na2CO3]]> No phenomenon 15 <![CDATA[Zinc citrate + Na2CO3]]> No phenomenon 2 <![CDATA[Calcium chloride + Na2CO3]]> Precipitation 9 <![CDATA[EDTA-copper + Na2CO3]]> No phenomenon 16 <![CDATA[Zinc tartrate + Na2CO3]]> No phenomenon 3 <![CDATA[Magnesium citrate + Na2CO3]]> No phenomenon 10 <![CDATA[Copper(II) sulfate pentahydrate + Na2CO3]]> Precipitation 17 <![CDATA[EDTA-Zinc + Na2CO3]]> No phenomenon 4 <![CDATA[Magnesium tartrate + Na2CO3]]> No phenomenon 11 <![CDATA[Ferrous citrate + Na2CO3]]> No phenomenon 18 <![CDATA[Zinc sulfate monohydrate + Na2CO3]]> Precipitation 5 <![CDATA[EDTA-Magnesium + Na2CO3]]> No phenomenon 12 <![CDATA[Ferrous tartrate + Na2CO3]]> No phenomenon 19 <![CDATA[Manganese citrate + Na2CO3]]> No phenomenon 6 <![CDATA[Magnesium sulfate heptahydrate + Na2CO3]]> Precipitation 13 <![CDATA[EDTA-Ferrous + Na2CO3]]> No phenomenon 20 <![CDATA[EDTA-Manganese + Na2CO3]]> No phenomenon 7 <![CDATA[Copper citrate + Na2CO3]]> No phenomenon 14 <![CDATA[Ferrous sulfate heptahydrate + Na2CO3]]> Precipitation 21 <![CDATA[Manganese sulfate monohydrate + Na2CO3]]> Precipitation Table 3 Effects of different temperatures on chelated medium and trace elements RT <![CDATA[30 o C]]> <![CDATA[40 o C]]> <![CDATA[50 o C]]> <![CDATA[60 o C]]> <![CDATA[70 o C]]> <![CDATA[EDTA-calcium + Na2CO3]]> No change No change No change No change No change No change <![CDATA[Magnesium citrate + Na2CO3]]> No change No change No change No change No change No change <![CDATA[Copper citrate + Na2CO3]]> No change No change No change No change No change No change <![CDATA[Ferrous citrate + Na2CO3]]> No change No change No change No change Precipitation Precipitation <![CDATA[Zinc citrate + Na2CO3]]> No change No change No change No change No change No change <![CDATA[Manganese citrate + Na2CO3]]> No change No change No change No change No change No change

Claims

1. A class of highly efficient chelating agents, characterized in that: The chelating agent includes citric acid monohydrate, sodium tartrate, and disodium ethylenediaminetetraacetate (EDTA-2Na).

2. The chelating agent according to claim 1, characterized in that, The metal salts that undergo chelation reactions with it are: anhydrous calcium chloride, magnesium sulfate heptahydrate, copper sulfate pentahydrate, ferrous sulfate heptahydrate, zinc sulfate monohydrate, and manganese sulfate monohydrate.

3. The chelating agent and metal salt according to claims 1-2, characterized in that, Before the two are mixed, the chelating agent should have a pH of 6.0 - 8.

0.

4. The chelation reaction according to claims 1-3, characterized in that: Among the chelating agent and the metal salt, the chelating agent and the metal salt are calculated at a molar ratio of 1:

1.

5. The preparation method of the chelated medium and trace elements according to any one of claims 1-4, characterized in that, The chelating agent and the metal salt are stirred evenly under the corresponding pH conditions to obtain the product.

6. The soluble matter in the chelated medium and trace elements according to claim 5 can be applied to the field of agricultural production, and is characterized in that: The crops lack medium and trace elements.