Efficient metal chelating agent as well as preparation method and application thereof

Abstract

The invention relates to the field of chelating agent preparation, in particular to an efficient metal chelating agent and a preparation method and application thereof. The preparation method comprises the following preparation steps: (1) dissolving dibutanol amine in absolute ethyl alcohol, adding carbon disulfide, reacting for 5-8 hours at 0-5 DEG C in a nitrogen atmosphere, adjusting the pH to be neutral by using a sodium hydroxide aqueous solution, and performing rotary evaporation to obtain sodium bis (4-hydroxybutyl) dithiocarbamate; and (2) adding 4-[bis (beta-chloroethyl) amino] benzaldehyde, the bis (4-hydroxybutyl) sodium dithiocarbamate obtained in the step (1) and a catalyst into absolute ethyl alcohol, heating and refluxing, reducing pressure to remove absolute ethyl alcohol, adding the obtained solid into pure water, stirring, extracting, combining organic phases, drying moisture in the organic phases, concentrating, standing for 10-20 hours, and separating to obtain the metal chelating agent. The prepared metal chelating agent has good dispersity and solubility in various solvents, and a stable metal chelate is formed through coordination chelation of active functional groups and heavy metal ions.

Description

Technical Field

[0001] The invention belongs to the field of chelating agent preparation, and in particular relates to a high-efficiency metal chelating agent and a preparation method and application thereof. Background Art

[0002] High-purity metal salt solutions are widely used in functional thin films, integrated circuit conductors, magnetic sensors, magnetic recording sputtering targets, high-purity reagents and standard sample configurations due to their special structure and properties. Especially in the production process of sputtering targets, the purity of metal salt solutions is required to be extremely high. For example, in the traditional production process of nickel chloride solution, extraction and sodium sulfide precipitation are generally used to remove copper. Although the copper removal effect is obvious, the compound formed by the extractant and copper is unstable, which will cause an increase in the number of extraction stages and the stability of the extraction system cannot be guaranteed.

[0003] Metal chelating agents can encapsulate metal ions into the chelating agent through the strong binding effect between chelating agent molecules and metal ions, turning them into stable compounds with larger molecular weight, thereby preventing metal ions from taking effect. They can be used in detoxification, printing and dyeing, scale prevention, extraction, etc. At present, the commonly used metal extractants in the preparation of high-purity metal salt solutions are P2O4, amine extractants, Lix984, etc. Patent CN 113981219 A discloses a method for separating nickel and cobalt in nickel chloride solution using amine extractants, comprising the following steps: acidification step: adding an organic phase composed of amine extractants, isooctyl alcohol and sulfonated kerosene and hydrochloric acid to the acidification section; extraction step: adding nickel chloride solution to the extraction section; nickel washing step: adding nickel washing acid to the nickel washing section to wash nickel; cobalt washing step: adding cobalt washing acid to the cobalt washing section to wash cobalt. Patent CN 114085993 A discloses a method for separating calcium, magnesium and manganese from nickel chloride solution by extraction, wherein the saponification step includes simultaneously inputting the organic phase composed of P2O4 extractant and sulfonated kerosene and sodium hydroxide solution into the saponification section for continuous countercurrent extraction, and the organic phase after saponification is transported into the extraction section for extraction, washing nickel and cobalt, and washing impurities to obtain nickel chloride solution. However, the extraction sections used in the above two patents are 8 and 10 respectively, and the number of extraction stages is relatively large. In addition, the different types of metal chelators available on the market have different selectivities, and the chelates formed with different metal ions are not stable enough, which will also increase the number of extraction stages.

[0004] Based on the problems existing in the prior art, a high-performance metal chelating agent is developed to have high selectivity for the target metal and form a stable chelate to reduce the number of extraction stages, save manpower and cost, which is of great significance to industrial production. Summary of the invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a high-efficiency metal chelator and a preparation method and application thereof. The prepared metal chelator has good dispersibility and solubility in a variety of solvents. It can react rapidly to form insoluble and stable coordination chelates through coordination chelation of nitrogen atoms, oxygen atoms and sulfur atoms with heavy metal ions. It can be used alone or in combination with other substances, and has good application prospects in adsorption fields such as sewage treatment, water quality testing, and solution purification.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention provides a method for preparing a high-efficiency metal chelating agent, comprising the following preparation steps:

[0008] (1) dissolving dibutanolamine in anhydrous ethanol, adding carbon disulfide, reacting for 5-8 hours at 0-5° C. in a nitrogen atmosphere, adjusting the pH to neutral with an aqueous sodium hydroxide solution, and rotary evaporating to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0009] (2) Add 4-[bis(β-chloroethyl)amino]benzaldehyde, sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and a catalyst to anhydrous ethanol, heat to reflux, remove the anhydrous ethanol under reduced pressure, add the obtained solid to pure water and stir, extract and combine the organic phases, dry the water in the organic phases, concentrate, let stand for 10-20 hours, separate, and obtain a metal chelating agent.

[0010] In some embodiments, the molar ratio of dibutanolamine to carbon disulfide is 1:(1-1.2).

[0011] Preferably, the molar ratio of dibutanolamine to carbon disulfide is 1:1.1.

[0012] In some embodiments, the molar ratio of 4-[bis(β-chloroethyl)amino]benzaldehyde to sodium di(4-hydroxybutyl)dithiocarbamate in step (2) is 1:(2-2.5).

[0013] Preferably, in step (2), the molar ratio of 4-[bis(β-chloroethyl)amino]benzaldehyde to sodium di(4-hydroxybutyl)dithiocarbamate is 1:2.35.

[0014] In some embodiments, the catalyst is one or more of potassium iodide, potassium bromide, and potassium chloride.

[0015] In some embodiments, the amount of the catalyst used is 1-1.5% of the total molar amount of 4-[bis(β-chloroethyl)amino]benzaldehyde and sodium bis(4-hydroxybutyl)dithiocarbamate.

[0016] Preferably, the catalyst is potassium iodide, and the amount of the catalyst used is 1.25% of the total molar amount of 4-[bis(β-chloroethyl)amino]benzaldehyde and sodium di(4-hydroxybutyl)dithiocarbamate.

[0017] In some embodiments, the heating reflux temperature is 85-95° C. and the time is 20-30 h.

[0018] Preferably, the heating reflux temperature is 90° C. and the time is 25 h.

[0019] In some embodiments, the extraction agent used in the extraction is dichloromethane and / or chloroform.

[0020] The second aspect of the present invention provides a metal chelating agent prepared by the above-mentioned preparation method, and its structural formula is:

[0021]

[0022] In some embodiments, the yield of the metal chelator is ≥ 70.8%.

[0023] The third aspect of the present invention provides the use of the above-mentioned metal chelating agent in the field of adsorption.

[0024] The metal chelating agent in the present invention has good chelating ability, can be used alone or in combination with other substances, and has good application prospects in adsorption fields such as sewage treatment, water quality testing, solution purification, etc.

[0025] The invention controls conditions to make dibutanolamine and carbon disulfide react chemically, uses sodium hydroxide to adjust pH, generates sodium di(4-hydroxybutyl)dithiocarbamate, and then makes sodium di(4-hydroxybutyl)dithiocarbamate react chemically with the generated 4-[bis(β-chloroethyl)amino]benzaldehyde to generate a novel metal chelating agent. The metal chelating agent has good dispersibility and solubility in various solvents, and coordinates and chelates with heavy metal ions through nitrogen atoms, oxygen atoms and sulfur atoms to form a stable metal chelate.

[0026] In the present invention, the hydroxybutyl in di(4-hydroxybutyl) sodium dithiocarbamate is introduced into 4-[bis(β-chloroethyl)amino]benzaldehyde, and on the one hand, the hydroxyl group itself has a certain chelating ability, which can improve the performance of the metal chelator to a certain extent; on the other hand, the hydroxybutyl group can also improve the stability of the chelator and the metal complex. This may be due to the introduction of the hydroxybutyl group can improve the electron density on the surface of the chelator molecule, and enhance the bonding strength between atoms in the chelator molecule, and the hydroxybutyl group in the chelator is symmetrically distributed, the symmetry of the chelator molecule is higher, and it is easier to combine with metal ions to form a symmetrical chelate ring, thereby improving the stability of the chelate. In addition, the -N(C6H4)CHO in the structure can also provide an electronic force for the CS bond, thereby improving its coordination ability with metal ions. The symmetrically distributed hydroxybutyl structure in the chelating agent molecule will not be restricted by the position of electrons, which will increase the electron cloud density of the dithioamino active functional group and improve the electron donation capacity of the sulfur atom. The lone pair of electrons on the sulfur atom will form a coordination bond with the metal ion to form a highly stable metal chelate.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The invention controls conditions to make sodium di(4-hydroxybutyl)dithiocarbamate and 4-[bis(β-chloroethyl)amino]benzaldehyde react chemically to generate a novel metal chelating agent, which has good dispersibility and solubility in various solvents, and forms a stable metal chelate by coordination and chelation with heavy metal ions through active atoms such as nitrogen atoms, oxygen atoms, and sulfur atoms. The invention has simple operation steps, and the prepared metal chelating agent has good application prospects in the field of adsorption. DETAILED DESCRIPTION

[0029] Now describe in detail various exemplary embodiments of the present invention, this detailed description should not be considered as limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing a particular embodiment, and are not used to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the range.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. Various modifications and variations may be made to the specific embodiments of the present invention specification without departing from the scope or spirit of the present invention, which will be apparent to those skilled in the art. Other embodiments obtained from the present invention specification will be apparent to the technician. The present application specification and examples are exemplary only.

[0031] The words “include,” “including,” “have,” or “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0032] The catalyst used in the present invention is potassium iodide; the extractant used in Examples 1-9 and Comparative Example 1 is dichloromethane, and the extractant used in Example 10 is ethyl acetate.

[0033] Example 1

[0034] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0035] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1 mol of carbon disulfide, react for 5 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0036] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.2 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 3 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 85° C. for 30 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 10 h and filtered to obtain a metal chelating agent.

[0037] Example 2

[0038] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0039] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.1 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0040] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.235 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 4.19 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0041] Example 3

[0042] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0043] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.2 mol of carbon disulfide, react for 5 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0044] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.25 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 5.25 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 95° C. for 20 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 15 h and filtered to obtain a metal chelating agent.

[0045] Example 4

[0046] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0047] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 0.9 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0048] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.235 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 4.19 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0049] Example 5

[0050] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0051] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.3 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0052] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.235 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 4.19 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0053] Example 6

[0054] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0055] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.1 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0056] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.19 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 3.625 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0057] Example 7

[0058] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0059] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.1 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0060] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.26 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 4.5 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0061] Example 8

[0062] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0063] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.1 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0064] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.235 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 4.19 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 85° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0065] Example 9

[0066] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0067] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.1 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0068] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.235 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 3.02 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0069] Example 10

[0070] A method for preparing a high-efficiency metal chelating agent comprises the following preparation steps:

[0071] (1) Dissolve 1 mol of dibutanolamine in 500 mL of anhydrous ethanol, add 1.1 mol of carbon disulfide, react for 6 h at 0° C. in a nitrogen atmosphere, adjust the pH to neutral with a 2 mol / L sodium hydroxide aqueous solution, and perform rotary evaporation to obtain sodium di(4-hydroxybutyl)dithiocarbamate;

[0072] (2) 0.1 mol of 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.235 mol of sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and 4.19 mmol of catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90° C. for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was then extracted three times with 250 mL of ethyl acetate, the organic phases were combined, 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0073] Comparative Example 1

[0074] A method for preparing a metal chelating agent comprises the following preparation steps:

[0075] 0.1 mol 4-[bis(β-chloroethyl)amino]benzaldehyde, 0.235 mol sodium diethyldithiocarbamate and 4.19 mmol catalyst were added to 500 mL of anhydrous ethanol, and the mixture was heated under reflux at 90°C for 25 h. The anhydrous ethanol was removed under reduced pressure, and the obtained solid was added to 500 mL of pure water and stirred. The mixture was extracted three times with 250 mL of dichloromethane, and the organic phases were combined. 15 g of sodium sulfate was added to dry the water in the organic phase, and the mixture was concentrated to 50 mL. The mixture was allowed to stand for 20 h and filtered to obtain a metal chelating agent.

[0076] Metal Chelating Agent Performance Test

[0077] 1. Determination of metal chelating agent yield

[0078] The metal chelating agent yield obtained in each embodiment and comparative example is calculated according to the following formula: Y=m2 / m1×100%, wherein m1 represents the theoretical yield of the metal chelating agent (unit: g); m2 represents the actual yield of the metal chelating agent (unit: g).

[0079] The specific test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] As shown in Table 1, the yield of the metal chelating agent prepared in Examples 1-3 is relatively high, reaching more than 70.8%, among which the yield of the metal chelating agent in Example 2 is as high as 72.9%; compared with Example 2, in Examples 4 and 5, the amount of carbon disulfide used is changed, which affects the generation and properties of sodium di(4-hydroxybutyl)dithiocarbamate, so that the yield of the metal chelating agent is reduced; in Examples 6 and 7, the amount of sodium di(4-hydroxybutyl)dithiocarbamate used is changed, which is not conducive to the occurrence of the reaction, so that the yield of the metal chelating agent is reduced; in Example 8, the reflux temperature is reduced, the reaction rate is reduced, and the yield of the metal chelating agent is also affected to a certain extent; in Example 9, the amount of the catalyst is changed, the catalytic performance and the reaction rate are reduced, and the yield of the metal chelating agent is also affected; in Example 10, the extractant used is ethyl acetate, and the solubility of the generated metal chelating agent in ethyl acetate is significantly reduced compared with ethylene dichloride, resulting in a high loss, so that the yield of the metal chelating agent is significantly reduced.

[0083] Based on the test results of the yield, the metal chelating agents obtained in Example 2 and Comparative Example 1 were selected to test their chelating properties.

[0084] 2. Test of chelating properties of metal chelators

[0085] 1 g of the metal chelating agent in Example 2 and Comparative Example 1 was respectively dissolved in 100 mL of a mixed metal ion solution (including 0.01 mol of copper sulfate pentahydrate, 0.01 mol of lead sulfate and 0.01 mol of nickel sulfate) at pH = 5, and then filtered after standing for 20 min. The metal ion concentration in the solution was tested, and the removal rate was calculated according to the following formula: R = 100% * (C0-C1) / C0, wherein C0 is the concentration of each metal ion in the solution before the test (0.1 mol / L); C1 is the concentration of each metal ion in the solution after the test (unit: mol / L);

[0086] Among them, the copper ion concentration was determined by the sodium diethyldithiocarbamate spectrophotometric method in the national standard GB / T 7474-87; the lead ion concentration was determined by the dithizone spectrophotometric method in the national standard GB / T 7470-87; and the nickel ion concentration was determined by the dimethylglyoxime spectrophotometric method in the national standard GB 11910-89.

[0087] The specific test results are shown in Table 2.

[0088] Table 2

[0089]

[0090] As can be seen from Table 2, the metal chelator prepared in Example 2 can chelate metal ions well, and has a good removal effect on copper ions, lead ions, and nickel ions, but the removal rate of nickel ions is smaller than that of copper ions and lead ions. This may be because when the pH of the solution is 5, the chelation effect of the metal chelator on nickel is weaker than that of copper ions and lead ions; and the removal effect of the metal chelator prepared in Comparative Example 1 on copper ions, lead ions, and nickel ions is significantly reduced. This may be because the chelator in Example 2 has more hydroxyl functional groups and nitrogen and sulfur adsorption active sites, which can chelate with a large number of metal ions and improve the removal rate.

[0091] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present application. Although the present application is disclosed as above in the preferred embodiment, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A method for preparing a highly efficient metal chelating agent, characterized in that: The method comprises the following preparation steps: (1) dissolving dibutanolamine in anhydrous ethanol, adding carbon disulfide, reacting for 5-8 hours at 0-5° C. in a nitrogen atmosphere, adjusting the pH to neutral with an aqueous sodium hydroxide solution, and rotary evaporating to obtain sodium di(4-hydroxybutyl)dithiocarbamate; (2) Add 4-[bis(β-chloroethyl)amino]benzaldehyde, sodium di(4-hydroxybutyl)dithiocarbamate obtained in step (1) and a catalyst to anhydrous ethanol, heat to reflux, remove the anhydrous ethanol under reduced pressure, add the obtained solid to pure water and stir, extract and combine the organic phases, dry the water in the organic phases, concentrate, let stand for 10-20 hours, separate, and obtain a metal chelating agent.

2. The method for preparing a metal chelating agent according to claim 1, characterized in that: The molar ratio of dibutanolamine to carbon disulfide is 1:(1-1.2).

3. The method for preparing a metal chelating agent according to claim 1, characterized in that: In the step (2), the molar ratio of 4-[bis(β-chloroethyl)amino]benzaldehyde to sodium di(4-hydroxybutyl)dithiocarbamate is 1:(2-2.5).

4. The method for preparing a metal chelating agent according to claim 1, characterized in that: The catalyst is one or more of potassium iodide, potassium bromide and potassium chloride.

5. The method for preparing a metal chelating agent according to claim 4, characterized in that: The amount of the catalyst used is 1-1.5% of the total molar amount of 4-[bis(β-chloroethyl)amino]benzaldehyde and sodium di(4-hydroxybutyl)dithiocarbamate.

6. The method for preparing a metal chelating agent according to claim 1, characterized in that: The heating reflux temperature is 85-95° C. and the time is 20-30 h.

7. The method for preparing a metal chelating agent according to claim 1, characterized in that: The extraction agent used in the extraction is dichloromethane and / or chloroform.

8. A metal chelating agent prepared by the preparation method according to any one of claims 1 to 7, characterized in that: Its structural formula is:

9. A metal chelating agent prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The yield of the metal chelating agent is ≥70.8%.

10. Use of the metal chelating agent prepared by the preparation method according to any one of claims 1 to 7 or the metal chelating agent according to claim 8 or 9 in the field of adsorption.

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