An arginine-based dithiocarbamate chelating agent, its preparation method and application

Abstract

This invention discloses an arginine-based dithiocarbamate chelating agent, its preparation method, and its application. First, arginine is reacted with a base to break the internal salt bond of arginine, and then, under the action of a strong base, the amino group in the molecule loses its hydrogen atom. + This forms an ammonia anion; then, under strongly alkaline conditions, it undergoes a nucleophilic addition reaction with carbon disulfide to generate an arginine-based dithiocarbamate chelating agent. The product of this invention possesses both —CSS － and —COO － This invention utilizes two types of coordinating groups, which, through synergistic effects, significantly enhance the chelation and removal efficiency of heavy metal ions in wastewater. It is suitable for treating various types of heavy metal wastewater and fixing heavy metals in incineration fly ash, especially for removing heavy metal ions from industrial wastewater and domestic sewage, particularly complex wastewater containing multiple heavy metal ions. The preparation process is simple, the reaction conditions are mild, the operation and control are convenient, no waste is generated, investment is low, and it is easy to achieve industrial-scale production.

Description

Technical Field

[0001] This invention relates to the fields of heavy metal wastewater treatment and incineration fly ash immobilization, specifically to an arginine-based dithiocarbamate chelating agent, its preparation method, and its application. Background Technology

[0002] The rapid development of industrial and agricultural production, particularly in sectors such as mineral mining, smelting, surface finishing, and electronics, has resulted in large quantities of heavy metals entering water bodies, soil, and the atmosphere in various forms. Due to their high toxicity and non-biodegradability, heavy metals released into the environment affect the growth of plants and animals and can ultimately enter the human body through the food chain, accumulating and causing cumulative poisoning. Therefore, if heavy metal pollution generated during production processes is not effectively treated, it will inevitably cause serious harm to the ecological environment and human health, resulting in significant economic losses and hindering sustainable economic and social development. Heavy metal wastewater is the main form of heavy metal discharge and migration; effective treatment of heavy metal wastewater is a crucial aspect of heavy metal pollution prevention and control. With the development of industrial production, the mining, smelting, and processing technologies for heavy metal minerals are becoming increasingly complex, with more additives used, leading to increasingly complex compositions of discharged heavy metal wastewater and greater difficulty in treatment. Therefore, the effective treatment of heavy metal wastewater has become a pressing issue and challenge in the global environmental protection field.

[0003] Currently, the main methods for treating heavy metal wastewater include physical, chemical, physicochemical, and biological methods. Commonly used specific methods include chemical precipitation, oxidation-reduction, ion exchange, electrolysis, adsorption, reverse osmosis, electrodialysis, and chelation precipitation (flocculation). While these methods have some practical applications, they generally suffer from complex processes, demanding conditions, limited treatment efficiency, and high costs. In comparison, chelation precipitation (flocculation) offers advantages such as simple processing, lower cost, higher treatment efficiency, and suitability for treating complex heavy metal wastewater. It is suitable for large-scale heavy metal wastewater treatment and is a method with significant application value and potential. However, the key lies in the performance of the chelating precipitant (flocculator) used. Extensive research and practice have demonstrated that aminodithiocarbamate (-CSS)... － ) is a strong chelating group that can form stable, water-insoluble, disulfide-coordinated four-membered rings (—CSS) with most heavy metal ions. － )2M, which is easily separated from water by precipitation. Furthermore, the carboxyl group (—COO) －Amino (-NH2) and imino (-NH-) groups also have a certain coordination effect on heavy metal ions, which can fix heavy metal ions onto chelating agent molecules through coordination. Commonly used amino dithiocarbamate chelating agents, such as sodium thimerosilicate, ethyl thiocyanate, and N,N'-didithiopiperazine carboxylate, all have single chelating groups, resulting in limited chelating and binding capacity for some heavy metal ions. Therefore, incorporating multiple chelating (coordination) groups into the same chelating agent molecule is expected to leverage their respective strengths and compensate for their weaknesses, synergistically improving the chelating and binding capacity and removal efficiency of heavy metal ions in wastewater.

[0004] Content of the invention

[0005] To address the technical problem that the aforementioned amino dithiocarbamate chelating agents have a single chelating group and limited chelating and binding ability for some heavy metal ions, this invention provides an arginine-based dithiocarbamate chelating agent, its preparation method, and its application.

[0006] The arginine-based dithiocarbamate chelating agent provided by this invention has the main component structure shown in formula (Ⅰ):

[0007]

[0008] In formula (I), M is Na or K; x = 0 or 1, when x = 0, the N atom is connected to the H atom;

[0009] The above-mentioned main components are based on arginine, with 1-2 aminodithiocarboxylic acid groups (-CSS) grafted onto it. － ), the molecule contains both -CSS － and —COO － Two types of coordinating groups.

[0010] Furthermore, the auxiliary components of the chelating agent are xanthic acid and a base. The two coordination groups complement each other and work synergistically to enhance the binding ability of heavy metal ions in wastewater, and form stable flocculation precipitates that separate from the water, greatly improving the treatment effect of heavy metal wastewater.

[0011] The preparation method of the above-mentioned arginine dithiocarbamate chelating agent includes the following steps:

[0012] (1) Arginine, alkali and distilled water are added to the reactor at a mass ratio of 1:0.51-1.35:10-15. After stirring and dissolving, alkali is added. After the alkali dissolves, stirring is continued for 1-1.5 hours to break the internal salt bond in the molecule and make the amino group dehydrogenated and ionized.

[0013] (2) Add carbon disulfide slowly dropwise at a mass ratio of carbon disulfide to arginine of 0.44 to 0.92:1. After the addition is complete, continue the reaction at room temperature for 4 to 6 hours.

[0014] (3) Heat to 55-65℃ and continue the reaction for 1-1.5h until the oil droplets completely disappear. Cool to room temperature to obtain an orange-red or red liquid, which is the product arginine dithiocarbamate chelating agent.

[0015] Furthermore, in step (1), the arginine is a product with a purity of industrial grade or higher.

[0016] Furthermore, in step (1), the alkali is NaOH or KOH, and the NaOH or KOH is a product with a purity of industrial grade or higher.

[0017] Furthermore, in step (1), the reactors are equipped with mechanical stirrers, dripping funnels, and reflux condensers.

[0018] Furthermore, in step (2), the carbon disulfide is a product with a purity of industrial grade or higher.

[0019] Furthermore, in step (2), the slow addition of carbon disulfide takes 40 to 60 minutes.

[0020] The above-mentioned chelating agents are applied to the treatment of heavy metals in various types of heavy metal wastewater or incineration fly ash, and the treatment effect is excellent.

[0021] This invention relates to a method for preparing an arginine-based dithiocarbamate chelating agent. First, arginine is reacted with a base to break the internal salt bond of arginine, and then, under the action of a strong base, the amino group in the molecule loses its hydrogen atom. + The formation of ammonia anions (ammonia ionization) allows for effective nucleophilic addition of these anions to the partially positively charged carbon atoms of carbon disulfide upon its addition, resulting in the formation of arginine-based dithiocarbamate chelating agents. This invention fully utilizes the amino and carboxyl groups of the arginine molecule and their structural characteristics, by attaching a -CSS group to the amino group... － The group enables the prepared product to possess both -CSS properties. － and —COO － Two coordinating groups, through their synergistic effect, significantly improve the chelation and removal efficiency of heavy metal ions in wastewater.

[0022] The advantages of this invention compared to the prior art are as follows:

[0023] (1) The product of this invention uses arginine molecules as the basic backbone, making full use of the functional groups and structural characteristics of arginine molecules, so that it has both -CSS － and —COO － Two strong coordinating groups; -CSS in the molecule － It can form stable and water-insoluble disulfide-coordinated four-membered rings (-CSS) with most heavy metal ions. － )2M chelates bind heavy metal ions together, in the -COO－ With the assistance and synergistic effect of [unclear], the ability to fix heavy metals in wastewater is improved, and through the -CSS [unclear] from different molecules － It chelates with the same heavy metal ion to form macromolecules, causing the micro-flocs to gradually grow into large flocs and separate from the water body, thereby improving the treatment efficiency of heavy metal wastewater and overcoming the shortcomings of commonly used aminodithiocarbamate chelating agents, which have insufficient chelating and binding ability for some heavy metal ions due to the single chelating group.

[0024] (2) The method of the present invention first uses a strong alkali to break down the internal salt of arginine, and then, under strong alkali conditions, fully removes H from the amino group in the molecule. + The formation of ammonia anions (ammonia ionization) provides sufficient conditions for further nucleophilic attack on the partially positively charged C atoms on carbon disulfide, effectively ensuring the smooth progress of the nucleophilic addition reaction and ensuring the successful synthesis of the product of this invention.

[0025] (3) The product of this invention can react rapidly with most heavy metal ions in wastewater at room temperature to form stable, water-insoluble chelates, thus having a wide range of applications. Due to —CSS － It possesses strong chelating ability, capable of extracting heavy metal ions from most heavy metal complexes that are slightly weaker than itself. Therefore, it is suitable not only for removing free heavy metal ions but also for removing heavy metal ions in complexed states. The product of this invention can chelate with multiple heavy metal ions in water, making it particularly suitable for treating complex wastewater containing multiple heavy metal ions, achieving highly efficient removal of multiple heavy metal ions in one step.

[0026] (4) The product of this invention is simple to use for treating heavy metal wastewater. It only requires adding a certain amount of the product of this invention to the heavy metal wastewater and stirring it thoroughly to quickly generate insoluble flocs, which can be separated by sedimentation or filtration. No complicated equipment or procedures are required.

[0027] (5) The preparation method of the present invention is simple, the reaction conditions are mild, the operation is easy to control, no "three wastes" are generated, the required equipment is conventional equipment, it is easy to realize industrial production, and it has broad application prospects.

[0028] This invention is suitable for the treatment of various heavy metal wastewaters and the fixation of heavy metals in incineration fly ash, and is especially suitable for removing heavy metal ions from industrial wastewater and domestic sewage, particularly complex wastewater containing multiple heavy metal ions. Attached Figure Description

[0029] Figure 1 This is a flowchart of the preparation method of the present invention.

[0030] Figure 2 The infrared spectrum of the arginine dithiocarbamate chelating agent (sample of Example 4) is shown.

[0031] Figure 3 This is a diagram illustrating the chelation and flocculation mechanism of the product of this invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto.

[0033] Examples 1-7 illustrate the preparation method of the arginine dithiocarbamate chelating agent of the present invention, and Examples 8-11 illustrate the application examples of the product of the present invention.

[0034] Example 1

[0035] (1) Take 17.78g of 98.00% arginine and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Then add 177.8mL of distilled water and stir to dissolve. Then add 9.07g of 96.00% NaOH, dissolve and continue stirring for 1h.

[0036] (2) Take 6.2 mL of carbon disulfide with a mass fraction of 99.00% and add it dropwise to the solution obtained in step (1). The addition is completed within 40 min, and the reaction continues at room temperature for 4 h.

[0037] (3) Heat to 55℃ and continue the reaction for 1.5h until the oil droplets completely disappear. Cool to room temperature to obtain 194.8mL of red liquid, which is the arginine dithiocarbamate chelating agent.

[0038] Example 2

[0039] (1) Take 17.78g of 98.00% arginine and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Then add 213.4mL of distilled water and stir to dissolve. Then add 11.56g of 96.00% NaOH and stir for 1.25h after dissolving.

[0040] (2) Take 9.1 mL of carbon disulfide with a mass fraction of 99.00% and add it dropwise to the solution obtained in step (1). The addition is completed within 50 min, and the reaction continues at room temperature for 5 h.

[0041] (3) Heat to 60℃ and continue the reaction for 1.25h until the oil droplets completely disappear. Cool to room temperature to obtain 235.3mL of red liquid, which is the arginine dithiocarbamate chelating agent.

[0042] Example 3

[0043] (1) Take 17.78g of 98.00% arginine and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Then add 266.7mL of distilled water and stir to dissolve. Then add 13.34g of 96.00% NaOH and stir for 1.25h after dissolving.

[0044] (2) Take 10.5 mL of carbon disulfide with a mass fraction of 99.00% and add it dropwise to the solution obtained in step (1). The addition is completed within 50 min, and the reaction continues at room temperature for 6 h.

[0045] (3) Heat to 65℃ and continue the reaction for 1 hour until the oil droplets completely disappear. Cool to room temperature to obtain 293.3 mL of red liquid, which is the arginine dithiocarbamate chelating agent.

[0046] Example 4

[0047] (1) Take 17.78g of arginine with a mass fraction of 98.00% and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Then add 177.8mL of distilled water and stir to dissolve. Then add 15.11g of NaOH with a mass fraction of 96.00% and continue stirring for 1.5h after dissolving.

[0048] (2) Take 12.5 mL of carbon disulfide with a mass fraction of 99.00% and add it dropwise to the solution obtained in step (1). The addition is completed within 60 min, and the reaction continues at room temperature for 6 h.

[0049] (3) Heat to 60℃ and continue the reaction for 1.5h until the oil droplets completely disappear. Cool to room temperature to obtain 203.8mL of orange-red liquid, which is the arginine dithiocarbamate chelating agent.

[0050] Example 5

[0051] (1) Take 17.78g of 98.00% arginine and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Then add 195.6mL of distilled water and stir to dissolve. Then add 15.78g of 96.00% NaOH, dissolve and continue stirring for 1.5h.

[0052] (2) Take 15.5 mL of 99.00% carbon disulfide and add it dropwise to the solution obtained in step (1). The addition is completed within 60 min, and the reaction continues at room temperature for 6 h.

[0053] (3) Heat to 65℃ and continue the reaction for 1.5h until the oil droplets completely disappear. Cool to room temperature to obtain 223.6mL of orange-red liquid, which is the arginine dithiocarbamate chelating agent.

[0054] Example 6

[0055] (1) Take 17.78g of 98.00% arginine and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Then add 213.4mL of distilled water and stir to dissolve. Then add 19.56g of 85.00% KOH, dissolve and continue stirring for 1h.

[0056] (2) Take 9.3 mL of carbon disulfide with a mass fraction of 99.00% and add it dropwise to the solution obtained in step (1). The addition is completed within 50 min, and the reaction continues at room temperature for 6 h.

[0057] (3) Heat to 60℃ and continue the reaction for 1.5h until the oil droplets completely disappear. Cool to room temperature to obtain 232.1mL of orange-red liquid, which is the arginine dithiocarbamate chelating agent.

[0058] Example 7

[0059] (1) Take 17.78g of 98.00% arginine and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Then add 231.1mL of distilled water and stir to dissolve. Then add 24.00g of 85.00% KOH, dissolve and continue stirring for 1.5h.

[0060] (2) Take 12.5 mL of carbon disulfide with a mass fraction of 99.00% and add it dropwise to the solution obtained in step (1). The addition is completed within 50 min, and the reaction continues at room temperature for 6 h.

[0061] (3) Heat to 65°C and continue the reaction for 1 hour until the oil droplets completely disappear. Cool to room temperature to obtain 255.3 mL of orange-reddish-brown liquid, which is the arginine dithiocarbamate chelating agent.

[0062] Infrared spectroscopy analysis was performed on the arginine dithiocarbamate chelating agents obtained in Examples 1 to 7, and the results were basically consistent. The infrared spectral analysis results of the chelating agent obtained in Example 4 are as follows: Figure 2 As shown. Figure 2 The absorption peaks in the infrared spectrum can be assigned as follows: 3377.23 cm⁻¹ -1 These are the stretching vibration peaks of -OH and -NH in the water content of the sample; at 2965.02 and 2868.07 cm⁻¹. -1 The weak peaks at these locations are the asymmetric and symmetric stretching vibration peaks of -CH2-, corresponding to 1342.70 and 1313.29 cm⁻¹. -1 Its bending vibration peak appears at 2069.27 cm. -1 The weak peaks are the angular vibrational peaks of thioamide NC=S; 1655.10 and 1473.83 cm⁻¹.-1 The peaks represent the asymmetric and symmetric bending vibrations of -NH, with the corresponding water bending vibration peaks at 1655–1588 cm⁻¹. -1 The strong peaks obscure the view; 1588.58 and 1402.48 cm. -1 The peaks at 1451.65 cm⁻¹ represent the asymmetric and symmetric stretching vibrations of the carboxylate group, respectively. -1 It is an aminodithiocarboxylic acid group (N-CSS) - The stretching vibration absorption peak of CN in ) is 1199.51 cm⁻¹. -1 These are the stretching vibration peaks of CO in the molecule; 1147.92 and 914.57 cm⁻¹. -1 For -CSS - The stretching vibration peaks of C=S and CS were observed. Elemental analysis of the above samples showed that the S content was 34.11%, converted to -CSS... － Each chelating agent molecule contains an average of 1.97 -CSS ions. － The above results indicate that arginine-based dithiocarbamate chelating agents have been successfully synthesized.

[0063] Example 8

[0064] This embodiment demonstrates the treatment effect of the sample from Example 4 on heavy metal wastewater. The sample obtained in Example 4 (denoted as ARG-DTC, —CSS) was used for the treatment. － Using 5.361 mmol / g of Pb and commercially available DTCR as chelating agents, 100 mg / L solutions containing Pb were prepared. 2+ Cd 2+ Cr 3+ Cu 2+ Ni 2+ Mn 2+ and Zn 2+ Simulated heavy metal water samples were used. Flocculation test conditions: 500 mL of simulated heavy metal water samples were taken, and the pH value was adjusted to approximately 6.0. Chelating agents were added to the MY3000-6G intelligent color screen coagulation test stirrer (Wuhan Meiyu Instrument Co., Ltd.). The mixture was stirred rapidly at 220 r / min for 5 min, then at 100 r / min for 10 min, followed by slow stirring at 60 r / min for 15 min. After standing for 20 min, the clear liquid at 2 cm below the surface was measured using an AA-7000 atomic absorption spectrophotometer (Shimadzu Corporation, Japan). The treatment results are shown in Table 1.

[0065] Table 1. Removal effect of the product of this invention on free heavy metal ions

[0066]

[0067]

[0068] As can be seen from Table 1, under optimal conditions, the product ARG-DTC of this invention is significantly more effective than the commercially available comparative sample sodium fumarate in treating free Pb. 2+ Cd 2+ Cr 3+ Cu 2+ Ni 2+ Mn 2+ and Zn 2+ Plasma removal is highly effective, with residual ion concentrations far below the Class I standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996), and requiring a smaller dosage. This is because ARG-DTC contains one -COO ion. — And 2 — CSS — DTCR only has CSS — The two groups in ARG-DTC work synergistically to enhance the removal effect of heavy metal ions.

[0069] Example 9

[0070] Using ARG-DTC obtained in Example 4 as a chelating agent, the wastewater from a certain electroplating plant was used as the treatment target. The pollutant indicators of the wastewater are shown in Table 2. It contains phosphorus and cyanide compounds and is grayish-white and turbid.

[0071] The product ARG-DTC obtained in Example 4, commercially available heavy metal chelating agents sodium thimerosal and TMT-18 were used as reagents. 200 mL of wastewater sample was taken, and the pH was first adjusted to approximately 6 with lime slurry. Then, it was placed on a MY3000-6G intelligent color screen coagulation test stirrer (Wuhan Meiyu Instrument Co., Ltd.), and certain amounts of chelating agents such as ARG-DTC, sodium thimerosal, and TMT-18 were added. The stoichiometric ratio of ARG-DTC to sodium thimerosal (i.e., the ratio of ARG-DTC to sodium thimerosal in either ARG-DTC or sodium thimerosal) was determined. － CSS － The molar ratios of the chelating agent to heavy metal ions were 1.75:1 and 2.30:1, respectively, and the molar ratio of TMT-18 to metal ions was 1:2. The chelating agent was added with stirring at 250 rpm for 5 min; then stirred at 100 rpm for 20 min (adding an appropriate amount of polyacrylamide PAM after 10 min of stirring), followed by stirring at 60 rpm for 15 min, and allowed to stand for 20 min. Samples were taken for analysis, and the endpoint pH value and the concentration of heavy metal ions in the treated water were tested. The results are listed in Table 2.

[0072] Table 2. Removal effect of the product of this invention on comprehensive wastewater from electroplating plants.

[0073]

[0074] The results in Table 2 show that the product ARG-DTC of this invention has a significantly better treatment effect on this type of comprehensive electroplating wastewater than commercially available heavy metal capture agents such as sodium fumarate and TMT-18. Moreover, it requires less dosage, has lower turbidity in the treated water, and all pollutant indicators are lower than the limits specified in the "Electroplating Pollutant Discharge Standard" (GB21900-2008).

[0075] Example 10

[0076] Using ARG-DTC obtained in Example 4 as a chelating agent, zinc concentrate from a copper foil manufacturing plant was used as the treatment target. Its pollutant indicators are shown in Table 3, containing pyrophosphate and appearing colorless and transparent. ARG-DTC obtained in Example 3, commercially available heavy metal trapping agents sodium thimerosal and TMT-18 were used as reagents. 200 mL of wastewater sample was taken, and the pH was first adjusted to approximately 6.0 with sulfuric acid. Then, it was placed on a MY3000-6G intelligent color screen coagulation test stirrer (Wuhan Meiyu Instrument Co., Ltd.), and certain amounts of ARG-DTC, sodium thimerosal, and TMT-18 were added. The stoichiometric ratio of ARG-DTC to sodium thimerosal (i.e., the ratio of ARG-DTC to sodium thimerosal - CSS) was determined. － The molar ratios of TMT-18 to heavy metal ions were 1.85:1 and 2.1:1, respectively, and the stoichiometric ratio of TMT-18 to metal ions was 1:1.5. The chelating agent was added with stirring at 220 rpm for 5 min; then stirred at 100 rpm for 20 min (adding an appropriate amount of polyacrylamide PAM after 10 min of stirring), followed by stirring at 60 rpm for 20 min, and allowed to stand for 20 min. Samples were taken for analysis to test the concentration of heavy metal ions in the treated water, and the results are listed in Table 3.

[0077] Table 3. Effect of the product of this invention on the removal of zinc concentrate from a copper foil manufacturing plant.

[0078]

[0079] Table 3 shows that the product ARG-DTC of this invention has a significantly better treatment effect on this wastewater than commercially available heavy metal capture agents such as sodium fumarate and TMT-18. It can not only remove Cu... 2+ Zn 2+ Co 2+ All three ions were completely removed, and for Cr 3+ It can also remove pollutants to a low concentration, and all pollutant indicators are lower than the limits specified in the "Electroplating Pollutant Emission Standard" (GB21900-2008).

[0080] Example 11

[0081] The product ARG-DTC obtained in Example 4, commercially available heavy metal trapping agent sodium fumarate, and TMT-18 were used as heavy metal stabilizers in incineration fly ash, and solutions with a mass fraction of 5% were prepared. During the experiment, 250g of fly ash from a waste incineration plant was added to a reaction kneader. Then, stabilizer and water were added at a mass ratio of fly ash: stabilizer: water = 100:1 to 3:20. After thorough stirring and kneading for 20 minutes, the reaction continued for 2 hours. Samples were then taken for leaching experiments according to the method specified in HJ / T300-2007, and the concentration of pollutants in the leachate was determined. The results are shown in Table 4.

[0082] Table 4. Effects of the product of this invention and commercially available stabilizers on the treatment of incineration fly ash.

[0083]

[0084] As can be seen from Table 4, the amount of ARG-DTC, the product of this invention, is less than that of sodium fumarate and TMT-18, and it has a stronger stabilizing effect on metal ions in fly ash. The concentration of metal elements in the leachate of the stabilized fly ash is lower than the limit specified in the "Standard for Pollution Control of Municipal Solid Waste Landfill" (GB16889-2008), and it can be safely landfilled in the landfill.

[0085] The results of Examples 8-11 show that the product ARG-DTC of this invention has superior removal efficiency for heavy metal ions in wastewater containing free heavy metals and complex electroplating and copper foil production wastewater compared to the comparative samples, and exhibits better chelation and stabilization effects on incineration fly ash. This is because ARG-DTC contains -CSS. — and —COO — (N—CH—COO — It readily reacts with heavy metal ions in water, as shown in the attached image. Figure 3 The chelation effect shown: (1) —CSS — It readily chelates with heavy metal ions to form water-insoluble disulfide-coordinated four-membered ring chelates, —COO — It can form a stable atom with heavy metal ions in synergy with -NH-. Five-membered chelating ring, two groups work together to improve the chelation and binding ability of heavy metal ions; (2) can be bound by two -CSS from different ARG-DTC molecules. — Group or N-CH-COO — It chelates with the same heavy metal ion to form one water-insoluble disulfide-coordinated four-membered ring chelate or two... The five-membered chelating ring connects chelates formed by different molecules, allowing them to grow gradually and form larger flocs, thereby improving the efficiency of chelating and binding heavy metal ions and the stability of the chelates.

[0086] The above are merely preferred embodiments of the present invention. Based on the above concept of the present invention, those skilled in the art can make various modifications and variations. For example, within the range of proportions and process conditions given in the present invention, the proportions and process conditions can be combined and varied. Such variations and modifications are all within the scope of the present invention.

Claims

1. An arginine-based dithiocarbamate chelating agent, characterized in that, Its main components have the structure shown in formula (Ⅰ): （Ⅰ）， In equation (I), M is Na or K; x=1.

2. The arginine dithiocarbamate chelating agent according to claim 1, characterized in that, The chelating agent also includes auxiliary components xanthic acid and a base.

3. The method for preparing the arginine dithiocarbamate chelating agent according to claim 1 or 2, characterized in that, Includes the following steps: (1) Arginine, alkali and distilled water are added to the reactor in a mass ratio of 1:0.51~1.35:10~15. After stirring and dissolving, alkali is added. After the alkali dissolves, stirring is continued for 1~1.5h to break the internal salt bond in the molecule and make the amino dehydrogenated and ionized. (2) Add carbon disulfide slowly dropwise at a mass ratio of carbon disulfide to arginine of 0.44 to 0.92:

1. After the addition is complete, continue the reaction at room temperature for 4 to 6 hours. (3) Heat to 55~65℃ and continue the reaction for 1~1.5h until the oil droplets completely disappear. Cool to room temperature to obtain an orange-red or red liquid, which is the product arginine dithiocarbamate chelating agent.

4. The method for preparing the arginine-based dithiocarbamate chelating agent according to claim 3, characterized in that, In step (1), the arginine is a product with a purity of industrial grade or higher.

5. The method for preparing the arginine-based dithiocarbamate chelating agent according to claim 3, characterized in that, In step (1), the alkali is NaOH or KOH.

6. The method for preparing the arginine-based dithiocarbamate chelating agent according to claim 5, characterized in that, The NaOH or KOH is a product of industrial grade or higher purity.

7. The method for preparing the arginine-based dithiocarbamate chelating agent according to claim 3, characterized in that, In step (1), the reactors are equipped with mechanical stirring, a dripping funnel, and a reflux condenser.

8. The method for preparing the arginine-based dithiocarbamate chelating agent according to claim 3, characterized in that, In step (2), the carbon disulfide is a product with a purity of industrial grade or higher.

9. The method for preparing the arginine-based dithiocarbamate chelating agent according to claim 3, characterized in that, In step (2), the slow addition of carbon disulfide takes 40 to 60 minutes.

10. The application of the arginine dithiocarbamate chelating agent according to any one of claims 1 to 2 in the treatment of heavy metals in heavy metal wastewater or incineration fly ash.

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