RU2278868C1 - Method for preparing concentrated iron chelate solution and iron chelate - Google Patents

Abstract

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing metal complex compounds, in particular, to iron complex (chelate) as its concentrated solution. Method is carried out by interaction of iron salt in an aqueous medium with a chelate-forming agent wherein N,N,N',N'-ethylenediaminetetraacetic acid is used as a chelating agent and citric acid that are added simultaneously or successively. The process is carried out at temperature 70-90°C and in the process of mixing iron salt or after mixing with chelate-forming agent an aqueous solution of ammonia or ammonium citrate is added for providing pH value of the end product 2.0-2.3. The complex-forming agent can comprise succinic acid additionally. Method provides preparing iron chelate as a concentrated solution with the content of iron 60-100 g/l. Invention can be used in agriculture for root and leaf feeding of plants.

EFFECT: improved preparing method.

4 cl, 6 ex

Description

The invention relates to the production of metal complex compounds with complexones (metal complexonates), and specifically to the production of iron complexonate (chelate) in the form of a concentrated solution, widely used in agriculture for root and foliar nutrition (top dressing) of plants, as a supplier of trace elements in plant life and animals.

Thus, the invention, in particular, relates to the production of an iron microelement solution intended, in particular, for root and foliar nutrition (top dressing) of plants, as well as to compensate for the lack of iron in the life of plants and animals, humans in case of its manifestation. Iron chelate is applied alone or mixed with macro-fertilizers if used in agriculture.

The need, for example, of plants in iron is several times higher than in other trace elements, therefore it is necessary to additionally feed (supplement) with iron preparations and, accordingly, prepare a separate preparation containing only iron.

Known methods for producing iron preparations by dissolving its inorganic salts, in particular sulfates, in water, including the introduction of hot sulfuric acid into hot water, followed by the addition of iron sulfate.

The disadvantage of this method is the rather low solubility of iron sulfate even under such conditions, which leads to a low content of trace iron in the finished solution (low concentration), and also the iron is still in inorganic form. This means that the trace element is not fully absorbed by plants, i.e. has a low quality, and on the other hand, such a solution cannot be mixed with a solution of macro elements for simultaneous nutrition of plants, because in this case, sparingly soluble compounds (inorganic iron phosphates) are formed which precipitate and make feeding difficult (Recommendations on the use of fertilizers for obtaining planned high-quality crop yields of vegetable crops on artificial substrates in sheltered soil. M., 1991, Soyuzselkhozkhimiya, TsINAO , p. 11, 12).

There are practically no analogue methods for producing chelated iron in the form of a dissolved concentrate. In an industrially developed method for producing iron chelate in the form of a solution of Fe-EDTA (Fe salt and ethylenediaminetetraacetic acid), the Fe content is only 2-3% (or 20-30 g / l), which reduces the profitability of its transportation over even not very long distances from -for a large water content (Overview "The use of complexones in agriculture." M., 1984, NIITEKHIM, p.2-3, 6-12).

From SU 1611901 A1, 07/07/1990, a method for producing complexonates (chelates) of Fe, Mn, Zn and Mo, used to feed a tea plant, is known. Chelates are obtained by reacting carbonates of the corresponding metals or carbonate ores with the products of oxidation of molasses or with the oxidized syrup of the hydrolyzate of plant materials. The resulting metal chelates (in the form of mixtures of metal chelates) are mixed with clinoptilolite-containing tuff and used in the form of such a composition. However, according to the known invention, iron chelates are obtained in a mixture with chelates of other metals in the form of granular mass.

From RU 2059647, 05/10/1996, a method is known for producing iron complexonate - a complex of ascorbic acid with ferric chloride by reacting ascorbic acid with sodium carbonate and ferric chloride in a water medium at a molar ratio of 9:38:18, respectively. The product is obtained in the form of a crystalline powder, which is intended for use in medicine as a substance having cardioprotective properties.

A process is known from RU 2073005 for producing a chelate compound of a metal selected from the group Cd, Cr, Fe, Bi, Mn, Zn, Sn by reacting a chelating compound of a certain formula, for example 1-oxa-4,7,10-triazacyclodecane-N, N ′ , N ″ - triacetic acid (or its salt) with a metal oxide or metal salt in the presence, if necessary, of an alkali metal hydroxide. The resulting metal chelates are used as contrast agents for in vivo or in vitro diagnostics either in preparations or as a medicine for radiotherapy.

From RU 2179162, C1, 02/10/2002 a method for producing metal complexonates (chelates) used to obtain solutions containing microelements ("Microvit") is known, which includes two-stage chelation of inorganic metal salts using a combination of two complexones in an acidic environment: with citric acid, serving as an acidifying agent; as well as a secondary ligand in complexation involving HEDP (hydroxyethylidene diphosphonic acid). OEDP is a complexing agent active in an acidic environment.

One of the main factors affecting complexation is the pH of the solution: depending on the metal ions, the pH varies between 1.5-2.3 or 2.4-3.5.

This drug is a complex of chelated metals (trace elements) in their optimal combination (except iron) with the addition of nitrogen and potassium-containing components - the main nutrients. This combination is very effective in leaf nutrition of plants.

However, iron is required by plants several times more than it is contained in Mikrovit, so it must be additionally added separately from other trace elements. It is not possible to prepare a fully balanced combination of all trace elements, including iron, according to this scheme, since Fe is an antagonist with copper and other components.

As a result of the implementation of the method according to this known invention receive a nutrient solution (concentrate of trace elements) containing, g / l: Fe - 30, Mn - 30, B - 11, Zn - 8, Cu - 8, Co - 3, Mo - 5, Mg - 20, the nutrient value of the solution is 1.35-1.45 g / cm ³ , pH 2.7-3.

From SU 492060, 08/09/1976 a method for producing metal complexonates (in particular iron) is known - a metal chelate of an ethylenediaminetetraacetic acid derivative of a certain structural formula (the derivative is obtained by reacting ethylenediaminetetraacetic acid anhydride with amine R-NH ₂ , where R is the phenyl or naphthyl residue). Chelates are obtained by reacting the aforementioned derivative with a compound of a heavy metal, for example, iron chloride, in the presence of water or alkanols, and alkali metal or ammonium hydroxides.

Get, for example, iron chelates with an iron content in concentrations of 0.3-10 mg of iron per 1 l; pH support 7.5-8. Depending on the addition of a solid or liquid carrier, (products) are obtained in the form of solid preparations, in the form of concentrates of metal chelates dispersible in water, a wettable powder; in the form of liquid preparations - solutions in suitable organic solvents, water. Solutions contain active principles (metal chelates) at a concentration of 1-20%. In this known manner, iron chelates with a high iron content are not obtained.

The closest in technical essence and the achieved result is a known method for producing a solution of iron chelate with a content in the final solution of iron up to 3-5%.

A known method for producing a solution of iron chelate of polyaminodisuccinic acid, comprising adding an alkali metal salt (sodium or potassium) of polyaminodisuccinic acid to an aqueous solution of iron salt (iron nitrate, ferric chloride, ferric sulfate, ferric acetate), under conditions of obtaining a stable solution: process temperature 5- 100 ° C; the molar ratio of ligand to iron in the final product is from 1.05: 1 to 1.3: 1; the pH of the alkali metal solution and polyaminodisuccinic acid is 8-14; the pH of the iron salt solution is 0-4; The pH of the final product is 3-8. The resulting iron chelate can be used in agriculture, but is mainly intended for use in the photographic industry (US 5717123, 02/10/1998).

The technical task of the claimed invention is to obtain a highly concentrated solution of iron chelate with a high content of iron in solution.

The stated technical problem is achieved by the fact that in the method for producing a concentrated solution of iron chelate by interaction when mixed in an aqueous medium iron salts with a complexing agent when heated, a concentrated aqueous solution of iron chelate with an iron content of 60-100 g / l is obtained, N is used as a complexing agent, N, N ¹ , N ¹ - ethylenediaminetetraacetic acid and citric acid, which are administered simultaneously or sequentially; the process is carried out at 70-90 ° C, when mixing an aqueous solution of an iron salt in an aqueous medium with a complexing agent, or after mixing, an aqueous solution of ammonia or ammonium citrate is introduced into the reaction solution to obtain a final product with a pH of 2.0-2.3. As the iron salt, iron sulfate, iron nitrate, iron chloride, iron acetate are used in the form of aqueous solutions or in dry form. When implementing the method, the complexing agent may additionally contain succinic acid from 20 to 50 g / L.

The object of the invention is also an iron chelate in the form of a concentrated aqueous solution with an iron content of 60-100 g / l, obtained by the above method.

So, the problem to which the present invention is directed is a method of creating a separate highly concentrated solution of iron in chelated form for additional plant nutrition that prevents chlorosis, and increasing the concentration of iron in the solution compared, in particular, with Microvit.

The method is as follows. For example, citric acid is added to hot water and an ammonia solution is added until a pH of 1.5-2.5 is obtained. After that, an iron salt is introduced, for example, iron sulfate having the highest affinity for citric acid under such conditions, stirring is carried out until the iron salt is completely dissolved. Then add the second complexone - EDTA to obtain a mixed ligand iron complexonate. Stirring is continued for 2-3 hours to form a stable compound.

The temperature of dissolution of the iron salt and the formation of chelates is maintained in the range of 70-90 ° C. Its decrease leads to a slowdown in the reaction of interaction of the ingredients, and an increase of over 90 ° C is undesirable, since it will lead to the removal (evaporation) of ammonia and water and a decrease in the pH value below the optimal level.

In addition to ammonia, ammonium citrate can be used as an ammonium-containing component, which in the required amount acts as an alkalizing agent, and also is a complexing agent ligand - citric acid, while the dosage of citric acid is reduced.

The method is illustrated by the following non-limiting examples.

Example 1. In 500 ml of hot water add (1.3 mol) 250 g of citric acid, then 80 ml of ammonia solution (25%) is stirred constantly, the temperature is kept at 90 ° C, the pH of the solution is 2.0-2.3 . Then add 500 g of FeSO ₄ · 7H ₂ O (1.8 mol), mix until the salt is completely dissolved, then add 100 g (0.3 mol) of EDTA. The mixing process is continued for 3 hours, which is necessary to complete complexation in solution. The result is a mixed ligand iron chelate containing (1.8 mol) 100 g / l Fe, density 1290 g / l. In the final product, the molar ratio of iron, citric acid and EDTA is defined as

Fe: [citric acid + EDTA] = 1.1: 1

The initial molar ratio of salt of iron: [citric acid + EDTA] = 1.4: 1 (l.c. - citric acid).

Example 2. The process is carried out as shown in example 1, but the dosage of the components is as follows:

- citric acid - 190 g (1.0 mol)

- ammonia solution (25%) - 55 ml

- EDTA - 70 g (0.2 mol)

- FeSO ₄ · 7H ₂ O - 350 g (1.25 mol)

An iron chelate solution is obtained containing 70 g / l Fe with a density of 1240 g / l.

In the final product, the ratio is defined as

Fe: [citric acid + EDTA] = 1.05: 1

The original molar ratio:

iron salt: [citric acid + EDTA] = 1.4: 1.

Example 3. A complexing agent is added to 500 ml of hot water: 140 g of citric acid (0.7 mol) and 40 g (0.1 mol) of EDTA, stirred and then 300 g of iron sulfate (FeSO ₄ · 7H ₂ O) is added, constantly stirred, the temperature is maintained at 75 ° C; The pH of the solution is 2.1.

Next, an aqueous solution of ammonia (25%) or ammonium citrate is added to the resulting solution in an amount necessary to adjust the pH of the final solution of iron chelate.

An iron chelate solution is obtained containing 60 g / l of iron, density 1220 g / l (1.0 mol). The molar ratio is determined final (in the product):

Fe: [lk + EDTA] = 1.0: 0.8 [mol] = 1.25: 1;

Initial - iron salt: [l.k. + EDTA] = 300 g: 180 g = 1.6: 1.

Example 4. The process is carried out similarly as in examples 1 or 3, but part of citric acid (LK) is replaced with succinic acid (Y.K.), i.e. use citric acid in an amount of 150 g / l (0.8 mol) and succinic acid in an amount of 30 g / l (0.25 mol), the ratio between them is 3.2: 1 (in moles).

Get a solution of iron chelate containing 80 g / l (1.4 mol) of iron, the density of the solution is 1275 g / cm ³ . Final product attitude

Fe: [lk + i.k. + EDTA] = 1.4: 1.15 = 1.2: 1.

The initial molar ratio is

iron salt: [lk + i.k. + EDTA] = 400 g: 230 g = 1.7: 1.

Obtained by the claimed method, the iron chelate is used as fertilizing (nutrition) of plants. The following is a specific example showing its use in this capacity. This drug is named Ferovit.

Application

Spraying plants in the morning or evening hours with an aqueous solution of Ferovit in a ratio of 1.5 ml per 1 liter of water.

Prophylactically with an interval of 10-14 days. To eliminate chlorosis 3-4 times a week.

Example 5. Regular spraying of plants with a working solution of Ferovit (1.5 ml per 1 liter of water) 2-3 times in the spring. For complete wetting of the leaves of plants, the flow rate of the solution is 1 liter per 5-7 m ² planting. Chlorosis of leaves is completely absent, there is a powerful flowering and fruiting of the berry.

Example 6. When the first signs of chlorosis on the tomato (pale green tops) appear, it is necessary to spray the plants with Ferovit solution (1.5 ml per 1 liter of water) every other day for a week. By the end of the week, chlorosis is completely eliminated.

In 1 liter = 113 mg of Fe / 1 liter of working solution.

Claims (4)

1. The method of obtaining a concentrated solution of iron chelate by interaction when mixed in an aqueous medium with an iron salt with a complexing agent when heated, characterized in that a concentrated aqueous solution of iron chelate with an iron content of 60-100 g / l is obtained, N, N are used as complexing agent , N ', N'-ethylenediaminetetraacetic acid and citric acid, which are introduced simultaneously or sequentially, the process is carried out at 70-90 ° C, during mixing or after mixing the iron salt with complexing a entom added an aqueous solution of ammonia or ammonium citrate to achieve a final product pH of 2.0-2.3. 2. The method according to claim 1, characterized in that the iron salt is iron nitrate, ferrous sulfate, ferric acetate. 3. The method according to claim 1 or 2, characterized in that the complexing agent further comprises succinic acid. 4. Iron chelate in the form of a concentrated aqueous solution with an iron content of 60-100 g / l, obtained by the method according to one of claims 1 to 3.