Chelating agent containing hydroxyaminocarboxylic acid, preparation method therefor, and use thereof

Abstract

The present invention belongs to the technical field of the preparation of chelating agents and provides a chelating agent containing a hydroxyaminocarboxylic acid, a preparation method therefor, and a use thereof. In the present invention, an epoxysuccinic acid and a metal salt of an iminodiacetic acid are synthesized on the basis of a technique such as a plurality of steps of Michael addition reaction or cyclization, and the epoxysuccinic acid and the metal salt of the iminodiacetic acid then undergo an addition reaction to obtain a chelating agent containing a hydroxyaminocarboxylic acid. The chelating agent containing the hydroxyaminocarboxylic acid has good chelating performance, relatively good chelating performance on calcium, magnesium, iron, copper, or other metals, and a wide application range. The chelating agent containing the hydroxyaminocarboxylic acid has very high solubility in both a high-concentration alkali aqueous solution and a high-concentration acid aqueous solution and has excellent stability during storage. The chelating agent containing the hydroxyaminocarboxylic acid has mild reaction conditions, basically no waste during production, and a good industrial application value and social value.

Description

A chelating agent containing hydroxyaminocarboxylic acid, and its preparation method and application Technical Field

[0001] The invention belongs to the technical field of chelating agent preparation, and particularly relates to a chelating agent containing hydroxyaminocarboxylic acid, a preparation method and application thereof. Background Art

[0002] At present, common chelating agents mainly include phosphates, hydroxycarboxylic acids, aminocarboxylic acids and carboxylic acid-containing polymers. Among them, phosphate chelating agents such as sodium tripolyphosphate (STPP) have good chelating effects, but the phosphorus contained therein can cause great pollution to the environment. Hydroxycarboxylic acid chelating agents mainly include sodium gluconate, sodium citrate, etc., but due to their poor chelating performance for general metal ions, they have low cost performance. Acrylic polymers are a kind of high molecular weight chelating agents. Although they also have thickening and flocculation effects in addition to having chelating ability, acrylic polymers will settle in water after chelation, and they have the disadvantage of being difficult to be biodegradable. Aminocarboxylic acid chelating agents mainly include ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), iminodisuccinic acid (IDS), glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), etc. However, EDTA is not easily biodegradable (OECD), NTA is potentially carcinogenic, IDS has low metal chelating performance, and the raw materials in the production process of GLDA and MGDA are highly toxic and require high equipment. Industrialization is difficult, production costs are high, and product prices are expensive, making it difficult to widely use them in industrial production.

[0003] Therefore, it is necessary to develop a chelating agent that is non-toxic, phosphorus-free, low in chlorine, has strong chelating ability, good degradability and low cost.

[0004] Summary of the Invention

[0005] In response to the deficiencies in the prior art, the present invention provides a chelating agent containing hydroxyaminocarboxylic acid, a preparation method thereof, and an application thereof. The present invention synthesizes epoxysuccinic acid and a metal diacetate containing an imino group based on a multi-step Michael addition reaction, a cyclization reaction, and other techniques, and then performs an addition reaction between the epoxysuccinic acid and the metal diacetate containing an imino group, thereby obtaining the chelating agent containing hydroxyaminocarboxylic acid. The chelating agent containing hydroxyaminocarboxylic acid has good chelating properties, and has good chelating properties for calcium, magnesium, iron, copper, or other metals, and has a wide range of applications. The chelating agent containing hydroxyaminocarboxylic acid has high solubility in both high-concentration alkaline aqueous solutions and acidic aqueous solutions, and has excellent storage stability. The chelating agent containing hydroxyaminocarboxylic acid has mild reaction conditions, and substantially no waste is generated during production, thereby having good industrial application value and social value.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] The present invention first provides a chelating agent containing hydroxyaminocarboxylic acid, wherein the molecular formula of the chelating agent is C9H9NNa4O9, and the structural formula thereof is:

[0008] The present invention also provides a method for preparing the above-mentioned chelating agent containing hydroxyaminocarboxylic acid, which specifically comprises the following steps:

[0009] (1) maleic anhydride is dissolved in deionized water, and then a NaOH solution is added to obtain a mixed solution, the pH value of the mixed solution is adjusted, and then the mixture is heated and stirred to react to obtain solution A;

[0010] (2) Sodium tungstate is added to solution A and stirred for reaction, and then a hydrogen peroxide solution and NaOH are added to adjust the pH value of the mixture, and then the temperature is raised to react to obtain solution B;

[0011] (3) Glycine is dissolved in deionized water, and then NaOH solution is added thereto for the first time and stirred to mix evenly, followed by adding acrylonitrile, and then reacting at a certain temperature for 1. After the reaction is completed, NaOH solution is added for the second time and the temperature is raised for reaction 2. After the reaction is completed, solution C is obtained;

[0012] Solution B is added dropwise to solution C, and then heated for reaction 3. After the reaction is completed, the temperature is lowered to obtain the chelating agent containing hydroxyaminocarboxylic acid.

[0013] Preferably, in step (1), when preparing solution A, the mass ratio of maleic anhydride, deionized water and NaOH solution is 190-220 g:190-220 g:190-220 g;

[0014] The temperature of the NaOH solution does not exceed 45° C. when it is added, and the mass concentration of the NaOH solution is 35-50 wt %;

[0015] The pH value of the system is adjusted to 6.0-6.5;

[0016] The conditions for the heating and stirring reaction are heating to 45-65° C. and stirring the reaction for 15 minutes.

[0017] Preferably, in step (2), when preparing solution B, the ratio of sodium tungstate, hydrogen peroxide solution, NaOH and maleic anhydride in step (1) is 12-18 g: 320-380 g: 100-145 g: 180-200 g;

[0018] The stirring reaction condition is stirring for 45 to 60 minutes;

[0019] The mass concentration of the NaOH solution is 35-50 wt%; the mass concentration of the hydrogen peroxide solution is 25-35 wt%;

[0020] The pH value of the system is adjusted to 6.0-6.5;

[0021] The temperature-raising reaction is carried out by heating the temperature to 25-40° C. and stirring the reaction for 1-5 hours.

[0022] Preferably, in step (3), when preparing the solution C, the mass ratio of glycine, deionized water, the first added NaOH solution, acrylonitrile and the second added NaOH solution is 130-170 g: 70-130 g: 150-170 g: 120-135 g: 150-165 g;

[0023] The reaction conditions of the reaction 1 are 50-70° C. for 1-5 hours;

[0024] The temperature reaction 2 is carried out at 90°C for 2 to 4 hours.

[0025] The mass concentration of the NaOH solution added twice is 35-50 wt %.

[0026] Preferably, in step (3), the reaction 3 is carried out at 70-80° C. for 3 h.

[0027] The invention also discloses the application of the chelating agent containing hydroxyaminocarboxylic acid in chelating heavy metal ions.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention has developed a non-toxic, phosphorus-free, low-chloride chelating agent with strong chelating ability, excellent degradability, and low cost. The chelating agent is a polyhydroxyaminocarboxylic acid chelating agent with a molecular formula of C9H9NNa4O9. The chelating agent structure of the present invention contains multiple hydroxyl, amino, and carboxylate chelating groups. Unlike traditional chelating agents, the chelating agent has higher dispersibility, higher chelating strength, and higher electrostatic repulsion. It can quickly form water-soluble complexes with ions of calcium, magnesium, iron, lead, copper, and manganese, and has particularly strong complexing ability with high-valent chromogenic metals. It is widely used in consumer detergents, cosmetics, industrial cleaning agents, printing and dyeing auxiliaries, dyeing and finishing processes, the textile industry, the papermaking industry, photosensitive materials, the ceramic industry, the electroplating industry, and the extraction of heavy metal pollutants in soil. It can also be used as a scale inhibitor and dispersant in traditional industrial circulating water.

[0030] The chelating agent containing hydroxyaminocarboxylic acid of the present invention can be used in the field of cosmetics. By forming stable water-soluble complex molecules with heavy metal ions, the oxidative effect of heavy metal ions on unsaturated fatty acids in cosmetics is reduced, the risk of adverse skin reactions is reduced, and the quality stability of cosmetics is improved. The antibacterial effect helps to ensure the quality of cosmetics during the long-term use of cosmetics by end customers.

[0031] The chelating agent containing hydroxyaminocarboxylic acid of the present invention can be used in the field of papermaking. It combines with metal ions to form a chelate with a stable ring structure, which can not only inhibit the catalytic decomposition of hydrogen peroxide by metal ions and improve the efficiency of hydrogen peroxide bleaching, but also prevent metal ions from being absorbed by pulp, avoid the formation of colored compounds and metal ion lignin complexes, and improve the whiteness of the finished paper.

[0032] The chelating agent containing hydroxyaminocarboxylic acid of the present invention can be used in the field of printing and dyeing applications, and has a wide range of applications in printing and dyeing water treatment, desizing, scouring, bleaching, dyeing, soaping and other processes. In addition, the high dispersion, complexation and electrostatic repulsion of the chelating agent containing hydroxyaminocarboxylic acid can help dissolve the dye and increase its diffusion rate, so that the dye can be fully and evenly diffused in the dyeing solution in a shorter time, thereby dyeing the fiber. During the dyeing process, the Ca in the dye bath 2+ Mg 2+ 、Cu 2+ 、Fe 3+ 、Mn 2+ The presence of metal ions such as chelating agents will denature the dye and affect the dyeing performance. The addition of chelating agents can prevent their effect, complex some metal ions and impurities in the dye solution to form stable complexes, thereby reducing the association of dyes and avoiding the occurrence of defects such as color spots, and indirectly playing a role in level dyeing.

[0033] The hydroxyaminocarboxylic acid chelating agent of the present invention has high solubility in both high-concentration alkaline aqueous solutions and acidic aqueous solutions and excellent storage stability. The hydroxyaminocarboxylic acid chelating agent has mild reaction conditions and basically no waste is generated during production, thus having great industrial application value and social value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a spectrum of chloride ion detection in a chelating agent containing hydroxyaminocarboxylic acid.

[0035] Figure 2 shows the solubility of hydroxyaminocarboxylic acid chelating agents in concentrated sodium hydroxide solution.

[0036] Figure 3 shows the solubility of hydroxyaminocarboxylic acid chelating agents in water.

[0037] FIG4 is a graph showing the thermal stability of EDTA (a) and a chelating agent containing hydroxyl aminocarboxylic acid (b).

[0038] FIG5 is a graph showing the chelating capacity of hydroxyaminocarboxylic acid-containing chelating agents.

[0039] FIG6 is a graph showing the bleaching ability of hydroxyaminocarboxylic acid-containing chelating agents.

[0040] FIG7 is a diagram showing the stability test of a chelating agent containing hydroxyaminocarboxylic acid. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the accompanying drawings and specific examples, but the scope of protection of the present invention is not limited thereto. In the following examples, the synthesis route of the chelating agent containing hydroxyaminocarboxylic acid is shown below.

[0042] The chelating agents described in Example 4, except for the hydroxyaminocarboxylic acid-containing chelating agent of the present invention, can all be purchased.

[0043] Example 1:

[0044] (1) 196 g of maleic anhydride was added to 200 g of deionized water and hydrolyzed at 25° C. for 1 h to obtain a mixed solution. Then, 200 g of a 50 wt % NaOH solution was added at a temperature not exceeding 45° C., and the pH value of the reaction system was adjusted to 6.0-6.5. The mixture was then heated to 55° C. and stirred for 15 min to obtain a solution A.

[0045] (2) 14 g of sodium tungstate was added to solution A and stirred for 45 min. Then, 360 g of 30 wt% hydrogen peroxide solution was added dropwise over 90 min. At the same time, 120 g of 50 wt% NaOH was added to the system to adjust the pH to 6.0-7.5. The temperature was then raised to 65° C. and stirred for 3 h to obtain solution B.

[0046] (3) To another 1 L reactor, 150 g of glycine, 100 g of deionized water, and 160 g of 50 wt% NaOH were added, stirred, and dissolved. Then, 125 g of acrylonitrile was added and the liquid temperature was about 60° C. for 3 h. Then, 160 g of 50 wt% NaOH was added and the temperature was raised to about 100° C. for 3 h to obtain Solution C.

[0047] Solution B was added dropwise to solution C. After the addition of solution B was completed, the temperature was controlled at 70-80°C for 3 h and then cooled to obtain N-(2-carboxyethyl)-N-(carboxymethyl)-3-hydroxy-aspartic acid sodium salt (1:4) with a yield of 98.33%.

[0048] This example investigated the chloride ion content of a hydroxyaminocarboxylic acid chelating agent, and the results are shown in Figure 1. As can be seen from Figure 1, the hydroxyaminocarboxylic acid chelating agent product is low in chloride (20-150 ppm) or close to the chlorine-free standard. It can be used in cleaning large power plant boilers, large stainless steel equipment in petrochemical systems, and industrial circulating water treatment systems without chloride ion or at low chloride ion levels, without causing corrosion to the equipment, thereby extending the service life of the equipment and protecting the normal and effective operation of the system.

[0049] This example also examined the solubility of hydroxyaminocarboxylic acid chelating agents in concentrated sodium hydroxide solution, and the results are shown in Figure 2. As can be seen from Figure 2, under the same high pH environment, the solubility of hydroxyaminocarboxylic acid chelating agents is far stronger than that of tetrasodium EDTA and trisodium MGDA. This demonstrates that hydroxyaminocarboxylic acid chelating agents can not only replace EDTA in extremely high alkaline environments, but also require a smaller addition amount. Therefore, hydroxyaminocarboxylic acid chelating agents can be used as the optimal chelating agent for compounding and preparing cost-effective cleaning agents.

[0050] This example also examined the solubility of the hydroxyaminocarboxylic acid chelating agent in water at 25°C, and the results are shown in Figure 3. As can be seen from Figure 3, the solubility of the hydroxyaminocarboxylic acid chelating agent is much stronger than that of tetrasodium EDTA, disodium EDTA, and trisodium MGDA, indicating that in a highly concentrated environment, the hydroxyaminocarboxylic acid chelating agent can not only replace EDTA and MGDA, but also be added in a smaller amount.

[0051] Example 2:

[0052] (1) 232 g of maleic acid was added to 200 g of deionized water and hydrolyzed at 45° C. for 1 h to obtain a mixed solution. 220 g of a 50 wt % NaOH solution was then added at a temperature not exceeding 50° C. The pH of the reaction system was adjusted to 5.0-6.5. The mixture was then heated to 55° C. and stirred for 15 min to obtain a solution A.

[0053] (2) Add 16 g of sodium tungstate to solution A and stir for 45 min. Then, add 450 g of 30 wt% hydrogen peroxide solution dropwise over 90 min. At the same time, add 180 g of 50 wt% NaOH to the system to adjust the pH to 6.0-7.0. Then, heat to 65°C and stir for 3 h to obtain solution B.

[0054] (3) To another 1 L reactor, 150 g of glycine, 100 g of deionized water, and 160 g of 50 wt% NaOH were added, stirred, and dissolved. Then, 125 g of acrylonitrile was added and the liquid temperature was about 60° C. for 5 h. Then, 160 g of 50 wt% NaOH was added and the temperature was raised to about 100° C. for 5 h to obtain Solution C.

[0055] Solution B was added dropwise to solution C. After the addition of solution B was completed, the temperature was controlled at 70-80°C for 5 h and then cooled to obtain N-(2-carboxyethyl)-N-(carboxymethyl)-3-hydroxy-aspartic acid sodium salt (1:4) with a yield of 96.63%.

[0056] This example investigated the thermal stability of a chelating agent containing hydroxyaminocarboxylic acid, and the results are shown in Figure 4. As can be seen from Figure 4, the chelating agent containing hydroxyaminocarboxylic acid has a stronger temperature resistance than EDTA. Under high temperature conditions, especially within 250-350°C, EDTA is almost unusable, but the chelating agent containing hydroxyaminocarboxylic acid can still be used. The residual rate of EDTA is about 28%, and the residual rate of the chelating agent containing hydroxyaminocarboxylic acid is about 50%.

[0057] This example also examined the chelating ability of hydroxyaminocarboxylic acid-containing chelating agents, and the results are shown in Figure 5. As can be seen from Figure 5, the ability of hydroxyaminocarboxylic acid-containing chelating agents to chelate calcium, magnesium, and copper ions is stronger than that of EDTA, but only the ability to chelate iron ions is lower than that of EDTA. Comprehensively evaluating the ability to chelate the above four metals, hydroxyaminocarboxylic acid-containing chelating agents are superior to EDTA and are ideal chelating agents that can replace EDTA. In addition, considering the shortcomings of GLDA and MGDA in the production process, such as high raw material toxicity, high equipment requirements, high industrialization difficulty, high production costs, and high product prices, the hydroxyaminocarboxylic acid-containing chelating agents can replace other biodegradable chelating agents such as EDTA, DPTA, and NTA, which are difficult to biodegrade and complex to produce and expensive.

[0058] Example 3:

[0059] (1) 232 g of maleic acid was added to 200 g of deionized water and hydrolyzed at 45° C. for 1 h to obtain a mixed solution. 280 g of a 50 wt % KOH solution was then added at a temperature not exceeding 50° C. The pH of the reaction system was adjusted to 5.0-6.5. The mixture was then heated to 55° C. and stirred for 15 min to obtain a solution A.

[0060] (2) Add 15 g of sodium tungstate to solution A and stir for 45 min. Then, add 450 g of 30 wt% hydrogen peroxide solution dropwise over 90 min. At the same time, add 168 g of 50 wt% KOH to the system to adjust the pH to 6.0-7.0. Then, heat to 60-65°C and stir for 3 h to obtain solution B.

[0061] (3) To another 1 L reactor, 150 g of glycine, 100 g of deionized water, and 370 g of 30 wt% KOH were added, stirred, and dissolved. Then, 125 g of acrylonitrile was added and the liquid temperature was about 60° C. for 3 h. Then, 370 g of 30 wt% KOH was added and the temperature was raised to about 100° C. for 3 h to obtain Solution C.

[0062] Solution B was added dropwise to solution C. After the addition of solution B was completed, the temperature was controlled at 70-80°C for 3 h and then cooled to obtain N-(2-carboxyethyl)-N-(carboxymethyl)-3-hydroxy-aspartic acid potassium salt (1:4) with a yield of 99.15%.

[0063] Example 4:

[0064] This example uses 100% eucalyptus pulp as the raw material and bleaching the pulp with EDTA, PP0124-2 (commercially available), and the aforementioned hydroxylaminocarboxylic acid chelating agent (referred to as New Formula-2) to examine the bleaching ability of the hydroxylaminocarboxylic acid chelating agent. The test concentration is 25%; the test environment is 100°C, kept warm for 90 minutes, and kneaded evenly every 30 minutes. The test method and dosage are as follows: caustic soda and hydrogen peroxide are added at 100% effective content, and other chemicals are added based on the finished product, with the added amount being based on the absolute dry weight per ton of pulp.

[0065] Figure 6 shows the chelating capacity of hydroxyaminocarboxylic acid chelating agents. As can be seen from the figure, the best bleaching effect is achieved with the formulation containing hydroxyaminocarboxylic acid chelating agents, followed by EDTA. The hydroxyaminocarboxylic acid chelating agent is 4% more effective than EDTA and 12.2% more effective than the blank. Therefore, based on the experimental results, hydroxyaminocarboxylic acid chelating agents can replace EDTA, and the formulation can replace commercially available products.

[0066] The present invention also uses EDTA and other chelating agents in the prior art, such as acetic acid, benzoic acid, AP8101 (commercially available) and PP0124-2 (commercially available) to investigate the stability of the hydroxyaminocarboxylic acid chelating agent of the present invention. The specific investigation steps are as follows:

[0067] The same dosage of EDTA, the hydroxyaminocarboxylic acid chelating agent of the present invention, AP8101 (commercially available), acetic acid, different batches of hydroxyaminocarboxylic acid chelating agent, benzoic acid, ethylenediamine, and PP0124-2 (commercially available) were recorded as Recipes 1-8. Using 100% eucalyptus pulp as the raw material, the bleaching ability of Recipes 1-8 was investigated, thereby demonstrating the stability of each chelating agent. The test concentration was 25% bleached pulp; the test environment was 100°C, kept warm for 90 minutes, and kneaded evenly every 30 minutes; the test method and dosage were: caustic soda and hydrogen peroxide were added at 100% effective content, and other chemicals were added according to the finished product, with the added amount being based on the absolute dry weight per ton of pulp.

[0068] Figure 7 shows the stability test results of a hydroxyaminocarboxylic acid chelating agent. As can be seen from the figure, the product containing the hydroxyaminocarboxylic acid chelating agent exhibits the best bleaching effect, thus demonstrating that the product containing the hydroxyaminocarboxylic acid chelating agent has better stability. In summary, the hydroxyaminocarboxylic acid chelating agent of the present invention has high solubility in both high-concentration alkaline and acid aqueous solutions and excellent storage stability. The hydroxyaminocarboxylic acid chelating agent has mild reaction conditions, produces virtually no waste during production, and has excellent industrial and social value.

[0069] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A chelating agent containing hydroxyaminocarboxylic acid, characterized in that: The molecular formula of the chelating agent is C9H9NNa4O9, and its structural formula is:

2. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 1, characterized in that: include: (1) dissolving maleic anhydride in deionized water, then adding a NaOH solution to obtain a mixed solution, adjusting the pH value of the mixed solution, and then heating and stirring to react to obtain a solution A; (2) adding sodium tungstate to solution A and stirring for reaction, then adding hydrogen peroxide solution and NaOH, adjusting the pH value of the mixed solution, and then heating the mixture to react, thereby obtaining solution B; (3) Glycine is dissolved in deionized water, and then NaOH solution is added thereto for the first time and stirred to mix evenly, and then acrylonitrile is added, and then reaction 1 is carried out at a certain temperature. After the reaction is completed, NaOH solution is added for the second time and the temperature is increased to react 2. After the reaction is completed, solution C is obtained; Solution B is added dropwise to solution C, and then heated for reaction 3. After the reaction is completed, the temperature is lowered to obtain the chelating agent containing hydroxyaminocarboxylic acid.

3. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 2, characterized in that: In step (1), when the solution A is prepared, the mass ratio of maleic anhydride, deionized water and NaOH solution is 190-220 g: 190-220 g: 190-220 g; The temperature of the NaOH solution does not exceed 45° C. when it is added, and the mass concentration of the NaOH solution is 35-50 wt %.

4. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 2, characterized in that: In step (1), the pH value of the system is adjusted to 6.0-6.5; The conditions for the heating and stirring reaction are heating to 45-65° C. and stirring the reaction for 15 minutes.

5. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 2, characterized in that: In step (2), when preparing solution B, the ratio of sodium tungstate, hydrogen peroxide solution, NaOH and maleic anhydride in step (1) is 12-18 g: 320-380 g: 100-145 g: 180-200 g; The stirring reaction is carried out for 45 to 60 minutes; The mass concentration of the NaOH solution is 35-50 wt %; the mass concentration of the hydrogen peroxide solution is 25-35 wt %.

6. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 2, characterized in that: In step (2), the pH value of the system is adjusted to 6.0-6.5; The temperature-raising reaction is carried out under the conditions of raising the temperature to 25-40° C. and stirring the reaction for 1-5 hours.

7. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 2, characterized in that: In step (3), when the solution C is prepared, the mass ratio of glycine, deionized water, the first added NaOH solution, acrylonitrile and the second added NaOH solution is 130-170g: 70-130g: 150-170g: 120-135g: 150-165g.

8. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 2, characterized in that: In step (3), the reaction 1 is carried out at 50-70° C. for 1-5 h; The temperature reaction 2 is carried out at 90°C for 2 to 4 hours; The mass concentration of the NaOH solution added twice is 35-50wt%.

9. The method for preparing a chelating agent containing hydroxyaminocarboxylic acid according to claim 2, characterized in that: In step (3), the reaction conditions of reaction 3 are 70-80° C. for 3 h.

10. Use of the chelating agent containing hydroxyaminocarboxylic acid according to claim 1 in chelating heavy metal ions.

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