A HEDP-chelated zinc soluble with potassium dihydrogen phosphate and its preparation method

Abstract

This invention discloses a HEDP-chelated zinc compound that is compatible with potassium dihydrogen phosphate and its preparation method. This application utilizes a two-step method to prepare HEDP-chelated zinc. In the first step, ammonium carbonate is added before the reaction of HEDP with the zinc-containing compound. This avoids the problem of large-scale precipitation caused by direct reaction between HEDP and the zinc-containing compound, thus optimizing the process and reducing reaction time. In the second step, after the zinc-containing compound has reacted completely, the organic amine triethanolamine, preferably, is added to react with HEDP to form a multi-ligand chelate with zinc ions, enhancing the chelation strength. This two-step method for preparing HEDP-chelated zinc combines inorganic ammonia with an organic amine. On the one hand, it avoids the difficulty of stirring caused by the large-scale precipitation of HEDP zinc into a gel state during conventional HEDP-chelated zinc production. On the other hand, it significantly enhances the chelation strength for zinc ions and improves the compatibility of the product with potassium dihydrogen phosphate.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically, to a HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate and its preparation method. Background Technology

[0002] HEDP-chelated zinc is a white crystalline or crystalline powder, hygroscopic, readily soluble in water, and compatible with potassium dihydrogen phosphate. As a novel and highly efficient organic chelating agent, HEDP can form stable complexes with metal ions in aqueous solutions, solving problems such as precipitation or oxidation of trace elements when combined with other ions, and low absorption efficiency.

[0003] The patent "A Method for Synthesizing HEDP Chelate Salts" (Patent No. CN 106927878 A) describes a method for synthesizing HEDP chelate salts. This method involves the high-temperature complexation of HEDP with compounds of iron, zinc, copper, manganese, calcium, magnesium, and molybdenum in ammonia, sodium hydroxide, or potassium hydroxide solutions. However, in this method, the direct reaction of zinc-containing compounds with HEDP results in the precipitation of large quantities, increasing the viscosity of the system and hindering rapid reaction. Furthermore, HEDP sodium zinc and HEDP potassium zinc are not compatible with potassium dihydrogen phosphate, and HEDP ammonium zinc (ammonia) requires heating and concentration, which is not only energy-intensive but also affects the compatibility of the product with potassium dihydrogen phosphate.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate and its preparation method.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides a method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate, comprising:

[0008] In the presence of a neutralizing agent, HEDP is reacted with a zinc-containing compound in a solution system to obtain a primary reaction solution.

[0009] The initial reaction solution was subjected to a final reaction with a chelating agent to obtain a final reaction solution containing HEDP chelated zinc.

[0010] The neutralizing agent is ammonium carbonate, and the chelating agent is triethanolamine. In an optional embodiment, the mass ratio of HEDP, water, and ammonium carbonate in the initial reaction is 10:5-10:2-4.

[0011] In an optional embodiment, the mass ratio of the zinc compound to HEDP in the initial reaction is 2-4:10.

[0012] In an optional embodiment, in the final reaction, the mass ratio of triethanolamine to HEDP is 2-3:10.

[0013] In an optional embodiment, the initial reaction temperature is 18-25°C, and the reaction continues until the solution is clear.

[0014] And / or, the final reaction temperature is 18-25°C, and the reaction continues until the solution is clear.

[0015] In an optional embodiment, the reaction time of the initial reaction is 20-40 minutes;

[0016] And / or, the reaction time of the final reaction is 20-40 min.

[0017] In an optional embodiment, the final reaction solution is spray-dried at 90-100°C to obtain HEDP chelated zinc powder.

[0018] In an optional embodiment, the zinc-containing compound is zinc oxide, and the mass ratio of zinc oxide to HEDP is 2-2.5:10.

[0019] Secondly, the present invention provides an HEDP chelated zinc prepared by any one of the foregoing embodiments, wherein the HEDP chelated zinc is a white powder with a zinc content of 16.0% or more.

[0020] In an optional embodiment, the mixed solution obtained by dissolving 1g of HEDP chelated zinc and 5g of potassium dihydrogen phosphate in 100ml of water can remain clear for more than 3 days.

[0021] In an optional embodiment, the aqueous solution of HEDP chelated zinc at a concentration of 1 wt% has a pH of 7.0-9.0.

[0022] The present invention has the following beneficial effects:

[0023] This invention discloses a HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate and its preparation method. This application utilizes a two-step method to prepare HEDP-chelated zinc. In the first step, ammonium carbonate is added before HEDP reacts with the zinc-containing compound, which avoids the problem of large amounts of precipitation that would occur when HEDP reacts directly with the zinc-containing compound, thus optimizing the process and reducing the reaction time. In the second step, after the zinc-containing compound has reacted completely, triethanolamine, an organic amine, is particularly preferred. It works together with HEDP to form a multi-ligand chelate with zinc ions, thereby enhancing the chelation strength.

[0024] The neutralizing agent in this scheme is ammonium carbonate, and the chelating agent is triethanolamine. The HEDP chelated zinc prepared by the two-step method combines inorganic ammonia and organic amine. On the one hand, it avoids the difficulty of stirring caused by the large amount of HEDP zinc precipitating into a gel state during the conventional production of HEDP chelated zinc. On the other hand, it can significantly enhance the chelation strength of zinc ions and improve the compatibility of the product with potassium dihydrogen phosphate. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0026] In a first aspect, the present invention provides a method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate, comprising:

[0027] In the presence of a neutralizing agent, HEDP is reacted with a zinc-containing compound in a solution system to obtain a primary reaction solution.

[0028] The initial reaction solution was subjected to a final reaction with a chelating agent to obtain a final reaction solution containing HEDP chelated zinc.

[0029] The neutralizing agent is ammonium carbonate, and the chelating agent is triethanolamine. Adding ammonium carbonate before the reaction of HEDP with the zinc-containing compound avoids the problem of excessive precipitation resulting from the direct reaction of HEDP with the zinc-containing compound, thus optimizing the process and reducing reaction time.

[0030] After the zinc-containing compound has reacted completely, the organic amine triethanolamine is particularly preferred. Together with HEDP, it forms a multi-ligand chelate with zinc ions, which enhances the chelation strength and improves the compatibility of the product with potassium dihydrogen phosphate.

[0031] This embodiment utilizes a two-step method to add ammonium carbonate and triethanolamine, combining inorganic ammonia with organic amine. On the one hand, this avoids the difficulty of stirring caused by the large amount of HEDP zinc precipitating into a gel state during the conventional production of HEDP chelated zinc. On the other hand, it can significantly enhance the chelation strength of zinc ions and improve the compatibility of the product with potassium dihydrogen phosphate.

[0032] In an optional embodiment, the mass ratio of HEDP, water, and ammonium carbonate in the initial reaction is 10:5-10:2-4.

[0033] Water can be used as a solvent to allow the reactants to react fully, but too much water will hinder the subsequent spray drying process, so it should not be used in excess.

[0034] In an optional embodiment, the mass ratio of the zinc compound to HEDP in the initial reaction is 2-4:10.

[0035] In an optional embodiment, in the final reaction, the mass ratio of triethanolamine to HEDP is 2-3:10, which enhances the chelation strength of zinc ions and improves the compatibility of the product with potassium dihydrogen phosphate.

[0036] In an optional embodiment, the initial reaction temperature is 18-25°C, and the reaction continues until the solution is clear.

[0037] And / or, the final reaction temperature is 18-25°C, and the reaction continues until the solution is clear.

[0038] The method for preparing HEDP chelated zinc in this application is mild, and the reaction can occur at room temperature without heating or pressurization. It has low energy consumption, which helps to reduce production costs and has good prospects for industrial application.

[0039] In an optional embodiment, the reaction time of the initial reaction is 20-40 minutes;

[0040] And / or, the reaction time of the final reaction is 20-40 min.

[0041] In an optional embodiment, the final reaction solution is spray-dried at 90-100°C to obtain HEDP chelated zinc powder.

[0042] In an optional embodiment, the zinc-containing compound is zinc oxide, and the mass ratio of zinc oxide to HEDP is 2-2.5:10. Compared with other zinc-containing compounds such as zinc carbonate, zinc oxide has a lower raw material cost, is relatively easy to purify, and is easier to obtain a product with relatively few impurities.

[0043] Secondly, the present invention provides an HEDP chelated zinc prepared by any one of the foregoing embodiments, wherein the HEDP chelated zinc is a white powder with a zinc content of 16% or more.

[0044] In an optional embodiment, the mixed solution obtained by dissolving 1g of HEDP chelated zinc and 5g of potassium dihydrogen phosphate in 100ml of water can remain clear for more than 3 days, indicating that the HEDP chelated zinc and potassium dihydrogen phosphate obtained in this application have good compatibility, which is beneficial to their widespread application in the field of fertilizers.

[0045] In an optional embodiment, the aqueous solution of HEDP chelated zinc at a concentration of 1 wt% has a pH of 7.0-9.0.

[0046] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0047] Example 1

[0048] This embodiment provides a method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate. The specific steps are as follows:

[0049] Add 10 parts of HEDP liquid to 5 parts of deionized water and stir until homogeneous. Slowly add 2.5 parts of ammonium carbonate, then slowly add 2.1 parts of zinc oxide to the filtrate. Stir at room temperature for about 30 minutes. After the solution becomes clear, add 2 parts of triethanolamine and stir for about 30 minutes to obtain a clear HEDP chelated zinc liquid. Finally, spray dry at 95°C to obtain a white HEDP chelated zinc powder.

[0050] The zinc content in the HEDP chelated zinc obtained in this embodiment is 16.0%, and the pH value of the 1wt% aqueous solution is 8.86. The mixed solution obtained by dissolving 1g of HEDP chelated zinc and 5g of potassium dihydrogen phosphate in 100ml of water can remain clear for more than 3 days.

[0051] Example 2

[0052] This embodiment provides a method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate. The specific steps are as follows:

[0053] Add 10 parts of HEDP liquid to 5 parts of deionized water and stir well. Slowly add 2.5 parts of ammonium carbonate, then slowly add 2.1 parts of zinc oxide to the filtrate. Stir at room temperature for about 30 minutes to obtain a clear HEDP chelated zinc liquid. Finally, spray dry at 95°C to obtain a white HEDP chelated zinc powder.

[0054] The zinc content in the HEDP chelated zinc obtained in this embodiment is 16.10%, and the pH value of the 1wt% aqueous solution is 8.03. The mixed solution obtained by dissolving 1g of HEDP chelated zinc and 5g of potassium dihydrogen phosphate in 100ml of water can remain clear for 1 day.

[0055] Table 1 Effect of triethanolamine on HEDP chelated zinc content

[0056]

[0057] As shown in Table 1, under the same reaction conditions, the zinc content did not change significantly without the addition of triethanolamine, but the solubility of the product with potassium dihydrogen phosphate was significantly reduced.

[0058] Example 3

[0059] This embodiment provides a method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate. The specific steps are as follows:

[0060] Ten parts of HEDP liquid were added to five parts of deionized water and stirred until homogeneous. Four parts of ammonia were slowly added, followed by two and a half parts of zinc oxide to the filtrate. The mixture was stirred at room temperature for about 30 minutes. After the solution became clear, two parts of triethanolamine were added and stirred for about 30 minutes to obtain a clear HEDP chelated zinc liquid. Due to the large amount of water, the solution was heated and concentrated to a suitable volume. Finally, the solution was spray-dried at 95°C to obtain a white HEDP chelated zinc powder.

[0061] The zinc content in the HEDP chelated zinc obtained in this embodiment is 16.14%, and the pH value of the 1wt% aqueous solution is 8.01. The mixed solution obtained by dissolving 1g of HEDP chelated zinc and 5g of potassium dihydrogen phosphate in 100ml of water can remain clear for 1 day.

[0062] Table 2. Effects of changing the alkali feedstock on HEDP chelated zinc content

[0063]

[0064] Replacing ammonium carbonate with ammonia in HEDP chelated zinc does not significantly change the zinc content, but it significantly reduces the compatibility of the product with potassium dihydrogen phosphate.

[0065] Example 4

[0066] This embodiment provides a method for preparing HEDP-chelated zinc, the specific steps of which are as follows:

[0067] Add 10 parts of HEDP liquid to 5 parts of deionized water and stir until homogeneous. Slowly add 2.5 parts of ammonium carbonate, then slowly add 2.5 parts of zinc oxide to the filtrate. Stir at room temperature for about 30 minutes. After the solution becomes clear, add 2 parts of triethanolamine and stir for about 30 minutes to obtain a clear HEDP chelated zinc liquid. Finally, spray dry at 95°C to obtain a white HEDP chelated zinc powder.

[0068] The zinc content in the HEDP chelated zinc obtained in this embodiment is 19.0%, and the pH value of the 1wt% aqueous solution is 8.86. The mixed solution obtained by dissolving 1g of HEDP chelated zinc and 5g of potassium dihydrogen phosphate in 100ml of water can remain clear for 40 minutes.

[0069] Table 3 Effect of zinc oxide dosage on HEDP chelated zinc content

[0070]

[0071]

[0072] Increasing the amount of zinc oxide significantly increases the zinc content, but the product is not compatible with potassium dihydrogen phosphate.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate. The specific steps are as follows:

[0075] Add 10 parts of HEDP liquid to 5 parts of deionized water and stir well. Then slowly add 2.1 parts of zinc oxide to the filtrate. A large amount of precipitation occurs during the reaction. Add a large amount of deionized water and stir at room temperature for about 1.5 hours. Then add 2 parts of triethanolamine and stir for about 2 hours without clarifying.

[0076] Table 4 shows the effect of primary reaction on HEDP chelated zinc.

[0077] serial number Example 1 Comparative Example 1 Is there an initial reaction? have none Whether the reaction is complete and clear yes no

[0078] There was no initial reaction before the addition of zinc oxide, but a large amount of precipitate occurred during the reaction. The reaction did not become clear after the addition of triethanolamine.

[0079] Comparative Example 2

[0080] This comparative example provides a method for preparing HEDP zinc sodium, the specific steps of which are as follows:

[0081] Add 10 parts of HEDP liquid to 5 parts of deionized water and stir until homogeneous. Slowly add 2.8 parts of sodium carbonate, then slowly add 2.1 parts of zinc oxide to the filtrate. Stir at room temperature for about 30 minutes. After the solution becomes clear, add 2 parts of triethanolamine and stir for about 30 minutes to obtain a clear HEDP zinc sodium liquid. Finally, spray dry at 95°C to obtain a white HEDP zinc sodium powder.

[0082] The zinc content in the HEDP zinc sodium obtained in this embodiment is 15.4%, and the pH value of the 1wt% aqueous solution is 8.62. The mixed solution obtained by dissolving 1g of HEDP zinc sodium and 5g of potassium dihydrogen phosphate in 100ml of water is not clear.

[0083] Table 5. Effects of changing the alkali feedstock on zinc content

[0084]

[0085] Using sodium carbonate instead of ammonium carbonate to produce HEDP zinc sodium, the product is not compatible with potassium dihydrogen phosphate.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate. The specific steps are as follows:

[0088] Ten parts of HEDP liquid were added to five parts of deionized water and stirred until homogeneous. Then, 2.5 parts of ammonium carbonate were slowly added, followed by 2.1 parts of zinc oxide to the filtrate. The mixture was stirred at room temperature for about 30 minutes. After the solution became clear, 1.5 parts of ammonia water were added and stirred for about 30 minutes. Due to the large amount of water, the solution was heated and concentrated to a suitable volume to obtain a clear HEDP chelated zinc liquid. Finally, the solution was spray-dried at 95°C to obtain a white HEDP chelated zinc powder.

[0089] The zinc content in the HEDP chelated zinc obtained in this embodiment is 16.09%, and the pH value of the 1wt% aqueous solution is 8.21. The mixed solution obtained by dissolving 1g of HEDP chelated zinc and 5g of potassium dihydrogen phosphate in 100ml of water can remain clear for more than 1 day.

[0090] Table 6. Effect of changing the chelating agent on the content of HEDP chelated zinc

[0091]

[0092]

[0093] Replacing triethanolamine with ammonia in HEDP chelated zinc does not significantly change the zinc content, but it significantly reduces the product's compatibility with potassium dihydrogen phosphate.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing HEDP-chelated zinc that is compatible with potassium dihydrogen phosphate, characterized in that, include: In the presence of a neutralizing agent, HEDP and a zinc-containing compound are initially reacted in a solution system to obtain an initial reaction solution. In the initial reaction, the mass ratio of the zinc-containing compound to HEDP is 2-4:

10. The initial reaction solution was subjected to a final reaction with a chelating agent to obtain a final reaction solution containing HEDP chelated zinc. The neutralizing agent is ammonium carbonate, and the chelating agent is triethanolamine. In the initial reaction, the mass ratio of HEDP, water, and ammonium carbonate is 10:5-10:2-4; in the final reaction, the mass ratio of triethanolamine to HEDP is 2-3:

10. The final reaction solution is spray-dried at 90-100℃ to obtain HEDP chelated zinc powder. The HEDP chelated zinc is a white powder with a zinc content of more than 16.0%. The pH value of the 1wt% aqueous solution of the HEDP chelated zinc is 7.0-9.

0.

2. The method for preparing HEDP-chelated zinc according to claim 1, characterized in that, The initial reaction temperature is 18-25℃, and the reaction continues until the solution becomes clear. And / or, the final reaction temperature is 18-25°C, and the reaction continues until the solution is clear.

3. The method for preparing HEDP-chelated zinc according to claim 2, characterized in that, The reaction time for the initial reaction is 20-40 minutes. And / or, the reaction time of the final reaction is 20-40 min.

4. The method for preparing HEDP-chelated zinc according to claim 1, characterized in that... The zinc-containing compound is zinc oxide, and the mass ratio of zinc oxide to HEDP is 2-2.5:10.

Images