Arginine dithioformate chelating agent as well as preparation method and application thereof

Abstract

The invention discloses an arginine-based dithioformate chelating agent as well as a preparation method and application thereof. The method comprises the following steps: reacting arginine with alkali to break an inner salt bond of the arginine, and removing H < + > from amino groups in molecules under the action of the alkali to form negative ions of ammonia; and then carrying out nucleophilic addition reaction on the arginine dithioformate and carbon disulfide under a strong alkaline condition to generate the arginine dithioformate chelating agent. The product has two coordination groups of-CSS <-> and-COO <->, and the chelating removal efficiency of heavy metal ions in wastewater is remarkably improved through the synergistic effect of the two groups; the method is suitable for treating various heavy metal wastewater and fixing heavy metals in incineration fly ash, and is particularly suitable for removing heavy metal ions in industrial wastewater and domestic sewage, especially complex wastewater containing various heavy metal ions. The method is simple in preparation process, mild in reaction condition, simple and convenient to operate and control, free of three wastes, low in investment and easy to realize industrial production.

Description

Technical Field

[0001] The invention relates to the field of heavy metal wastewater treatment and incineration fly ash immobilization, and in particular to an arginine-based dithioformate chelating agent and a preparation method and application thereof. Background Art

[0002] With the rapid development of industrial and agricultural production, especially mineral mining, smelting, surface finishing, and the electronics industry, a large amount of heavy metals have entered water bodies, soil, and the atmosphere in different forms. Due to the high toxicity and non-biodegradability of heavy metals, heavy metals discharged into the environment affect the growth of plants and animals, and can eventually enter the human body through the food chain and accumulate in the body, causing cumulative poisoning. Therefore, if the heavy metal pollution generated in the production process cannot be effectively treated, it will inevitably cause serious harm to the ecological environment and people's health, and cause serious economic losses, restricting the sustainable development of the economy and society. Heavy metal wastewater is the main form of heavy metal discharge and migration and transformation. Effective treatment of heavy metal wastewater is an important aspect of preventing and controlling heavy metal pollution. With the development of industrial production, the mining, smelting, and processing of heavy metal minerals have become increasingly complex, and the number of additives has increased, resulting in increasingly complex components of heavy metal wastewater discharged, making it more difficult to treat. Therefore, the effective treatment of heavy metal wastewater has become a hot spot and difficulty that needs to be urgently addressed in the global environmental protection field.

[0003] At present, the main methods for treating heavy metal wastewater include physical methods, chemical methods, physical and chemical methods, and biological methods. Commonly used specific treatment methods include chemical precipitation, oxidation-reduction method, ion exchange method, electrolysis method, adsorption method, reverse osmosis method, electrodialysis method, and chelating precipitation (flocculation) method. These methods have certain applications in practice, but they generally have problems such as complex process, harsh conditions, limited treatment efficiency, and high cost. In comparison, the chelating precipitation (flocculation) method has the advantages of simple treatment process, low cost, high treatment efficiency, and suitability for the treatment of heavy metal wastewater with complex components. It is suitable for the treatment of large-scale heavy metal wastewater and is a heavy metal wastewater treatment method with great promotion and application value and prospects. But the key lies in the performance of the chelating precipitation (flocculant) used. A large number of studies and practices have shown that aminodithiocarbamate (—CSS － ) is a strong chelating group that can form a stable and insoluble disulfide coordinated four-membered ring (—CSS) with most heavy metal ions. － )2M, it is easy to separate from the water in the form of precipitation. －), amino (—NH2) and imino (—NH—) also have certain coordination effects on heavy metal ions, and can fix heavy metal ions on chelating agent molecules through coordination. Commonly used aminodithiocarboxylate chelating agents, such as sodium thiocarboxylate, ethylthiocyanate, and sodium N,N'-dithiopiperazinecarboxylate, have a single chelating group and limited chelating and binding ability for some heavy metal ions. Therefore, it is expected that the compatibility of multiple chelating (coordination) groups in the same chelating agent molecule can complement each other and synergistically improve the chelating and binding ability and removal efficiency of heavy metal ions in wastewater.

[0004] Summary of the invention

[0005] In view of the technical problem that the aminodithiocarboxylate chelating agents have a single chelating group and limited chelating and binding ability to some heavy metal ions, the present invention provides an arginine dithiocarboxylate chelating agent and a preparation method and application thereof.

[0006] The arginine dithioformate chelating agent provided by the present invention has a main component structure as 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 a H atom;

[0009] The above main component is based on arginine, on which 1 to 2 aminodithiocarboxylic acid groups (—CSS － ), the molecule contains both - CSS － and—COO － Two types of coordination groups.

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

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

[0012] (1) Add arginine and distilled water into a reactor at a mass ratio of arginine, alkali and distilled water of 1:0.51-1.35:10-15, stir and dissolve, then add alkali, and continue stirring for 1-1.5 hours after the alkali is dissolved to break the internal salt bond in the molecule and dehydrogenate the amino group into negative ammonia ion;

[0013] (2) slowly adding carbon disulfide dropwise at a mass ratio of carbon disulfide to arginine of 0.44 to 0.92:1, and continuing the reaction at room temperature for 4 to 6 hours after the addition is complete;

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

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

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

[0017] Furthermore, in step (1), the reactors are equipped with mechanical stirring, a dropping funnel and a reflux condenser.

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

[0019] Furthermore, in step (2), the time for slowly adding carbon disulfide is 40 to 60 minutes.

[0020] The above chelating agent is used to treat various heavy metal wastewaters or heavy metals in incineration fly ash, and the treatment effect is excellent.

[0021] The present invention relates to a method for preparing an arginine-based dithiocarboxylate chelating agent. First, arginine is reacted with a base to break the internal salt bond of arginine, and the amino group in the molecule is dehydrogenated under the action of a strong base. + The negative ions of ammonia are formed (negative ammonium ionization), so that when carbon disulfide is added, it can effectively attack the partially positively charged C atoms of carbon disulfide to produce a nucleophilic addition reaction, thereby generating an arginine dithiocarboxylate chelating agent. The present invention makes full use of the amino and carboxyl groups of the arginine molecule and its structural characteristics, and connects a CSS － The group makes the prepared product have both -CSS － and—COO － The synergistic effect of the two coordination groups significantly improves the chelating removal efficiency of heavy metal ions in wastewater.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The product of the present invention uses arginine molecules as the basic skeleton, making full use of the functional groups and structural characteristics of arginine molecules to make it have both -CSS － and—COO － Two strong coordination groups; CSS in the molecule － It can react with most heavy metal ions to form a stable and water-insoluble disulfide coordinated four-membered ring (—CSS － )2M chelate to bind heavy metal ions, in -COO－ The ability to fix heavy metals in wastewater is improved by the auxiliary synergistic effect of CSS from different molecules. － It chelates with the same heavy metal ions to form macromolecules, allowing the formed microflocs to gradually grow into large flocs and be separated from the water body, thereby improving the treatment efficiency of heavy metal wastewater and overcoming the defect of commonly used aminodithioformate chelating agents that 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 firstly removes the internal salt of arginine by using a strong alkali, and then fully removes the H in the amino group of the molecule under the strong alkaline condition. + The formation of negative ions of ammonia (negative 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 the successful synthesis of the product of the present invention.

[0025] (3) The product of the present invention can react rapidly with most heavy metal ions in wastewater at room temperature to generate stable water-insoluble chelates, which have a wide range of applications. － It has strong chelating ability and can capture heavy metal ions from most heavy metal complexes that are slightly weaker than it. Therefore, it is suitable for removing not only free heavy metal ions but also complexed heavy metal ions. The product of the present invention can chelate with a variety of heavy metal ions in water, and is particularly suitable for the treatment of complex wastewater containing a variety of heavy metal ions, achieving efficient removal of a variety of heavy metal ions in one step.

[0026] (4) The process of using the product of the present invention to treat heavy metal wastewater is simple. It only requires adding a certain amount of the product of the present invention to the heavy metal wastewater and stirring it sufficiently to quickly produce insoluble flocs, which can then be separated by sedimentation or filtration without the need for complicated equipment and processes.

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

[0028] The invention is suitable for treating various heavy metal wastewaters and fixing heavy metals in incineration fly ash, and is particularly suitable for removing heavy metal ions in industrial wastewater and domestic sewage, especially complex wastewater containing multiple heavy metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a process flow chart of the preparation method of the present invention.

[0030] Figure 2 This is the infrared spectrum of the product of the present invention, the arginine dithioformate chelating agent (the sample of Example 4).

[0031] Figure 3 This is a diagram showing the chelating flocculation mechanism of the product of the present invention. DETAILED DESCRIPTION

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

[0033] Examples 1 to 7 are preparation methods of the arginine dithiocarboxylate chelating agent of the present invention, and Examples 8 to 11 are application examples of the product of the present invention.

[0034] Example 1

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

[0036] (2) adding 6.2 mL of 99.00% carbon disulfide dropwise to the solution obtained in step (1) within 40 min, and continuing the reaction at room temperature for 4 h;

[0037] (3) The temperature was raised to 55°C and the reaction was continued for 1.5 h until the oil droplets disappeared completely. The mixture was cooled to room temperature to obtain 194.8 mL of a red liquid, i.e., an arginine dithiocarboxylate chelating agent.

[0038] Example 2

[0039] (1) 17.78 g of arginine (mass fraction 98.00%) was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and then 213.4 mL of distilled water was added and stirred to dissolve; then 11.56 g of NaOH (mass fraction 96.00%) was added and stirred for 1.25 h after dissolution;

[0040] (2) adding 9.1 mL of 99.00% carbon disulfide dropwise to the solution obtained in step (1) within 50 min, and continuing the reaction at room temperature for 5 h;

[0041] (3) The temperature was raised to 60°C and the reaction was continued for 1.25 h until the oil droplets disappeared completely. The mixture was cooled to room temperature to obtain 235.3 mL of red liquid, i.e., arginine dithiocarboxylate chelating agent.

[0042] Example 3

[0043] (1) 17.78 g of arginine (98.00%) was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and then 266.7 mL of distilled water was added and stirred to dissolve; then 13.34 g of NaOH (96.00%) was added and stirred for 1.25 h after dissolution;

[0044] (2) adding 10.5 mL of 99.00% carbon disulfide dropwise to the solution obtained in step (1) within 50 min, and continuing the reaction at room temperature for 6 h;

[0045] (3) The temperature was raised to 65°C and the reaction was continued for 1 hour until the oil droplets disappeared completely. The mixture was cooled to room temperature to obtain 293.3 mL of red liquid, i.e., arginine dithiocarboxylate chelating agent.

[0046] Example 4

[0047] (1) 17.78 g of arginine (mass fraction 98.00%) was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and then 177.8 mL of distilled water was added and stirred to dissolve; then 15.11 g of NaOH (mass fraction 96.00%) was added and stirred for 1.5 h after dissolution;

[0048] (2) adding 12.5 mL of 99.00% carbon disulfide dropwise to the solution obtained in step (1) within 60 min, and continuing the reaction at room temperature for 6 h;

[0049] (3) The temperature was raised to 60°C and the reaction was continued for 1.5 h until the oil droplets disappeared completely. The mixture was cooled to room temperature to obtain 203.8 mL of an orange-red liquid, i.e., an arginine dithiocarboxylate chelating agent.

[0050] Example 5

[0051] (1) 17.78 g of arginine (mass fraction 98.00%) was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and then 195.6 mL of distilled water was added and stirred to dissolve; then 15.78 g of NaOH (mass fraction 96.00%) was added and stirred for 1.5 h after dissolution;

[0052] (2) adding 15.5 mL of 99.00% carbon disulfide dropwise to the solution obtained in step (1) within 60 min, and continuing the reaction at room temperature for 6 h;

[0053] (3) The temperature was raised to 65°C and the reaction was continued for 1.5 h until the oil droplets disappeared completely. The mixture was cooled to room temperature to obtain 223.6 mL of an orange-red liquid, i.e., an arginine dithiocarboxylate chelating agent.

[0054] Example 6

[0055] (1) 17.78 g of arginine with a mass fraction of 98.00% was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and then 213.4 mL of distilled water was added and stirred to dissolve; then 19.56 g of KOH with a mass fraction of 85.00% was added and stirred for 1 h after dissolution;

[0056] (2) adding 9.3 mL of 99.00% carbon disulfide dropwise to the solution obtained in step (1) within 50 min, and continuing the reaction at room temperature for 6 h;

[0057] (3) The temperature was raised to 60°C and the reaction was continued for 1.5 h until the oil droplets disappeared completely. The mixture was cooled to room temperature to obtain 232.1 mL of an orange-red liquid, i.e., an arginine dithiocarboxylate chelating agent.

[0058] Example 7

[0059] (1) 17.78 g of arginine with a mass fraction of 98.00% was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and then 231.1 mL of distilled water was added and stirred to dissolve; then 24.00 g of KOH with a mass fraction of 85.00% was added and stirred for 1.5 h after dissolution;

[0060] (2) adding 12.5 mL of 99.00% carbon disulfide dropwise to the solution obtained in step (1) within 50 min, and continuing the reaction at room temperature for 6 h;

[0061] (3) The temperature was raised to 65°C and the reaction was continued for 1 hour until the oil droplets disappeared completely. The mixture was cooled to room temperature to obtain 255.3 mL of an orange-red-brown liquid, i.e., an arginine dithiocarboxylate chelating agent.

[0062] The infrared spectroscopy analysis of the arginine dithiocarboxylate chelating agents obtained in Examples 1 to 7 showed that the results were basically the same. The infrared spectroscopy analysis results of the chelating agent obtained in Example 4 are as follows: Figure 2 shown. Figure 2 The absorption peaks in the infrared spectrum can be attributed as follows: 3377.23cm -1 The stretching vibration peaks of -OH and -NH of water in the sample; at 2965.02 and 2868.07 cm -1 The weak peaks at 1342.70 and 1313.29 cm-1 are the asymmetric and symmetric stretching vibration peaks of -CH2-. -1 Its bending vibration peak appears at 2069.27cm -1 The weak peaks are the angular vibration peaks of sulfamide NC=S; 1655.10 and 1473.83 cm-1 The asymmetric and symmetric bending vibration peaks of -NH and the corresponding bending vibration peaks of water are 1655-1588cm -1 Covered by the strong peaks of 1588.58 and 1402.48cm -1 The peaks at 1451.65cm are the asymmetric stretching and symmetric stretching vibration peaks of carboxylate groups. -1 N-CSS - ) is the stretching vibration absorption peak of CN; 1199.51cm -1 The stretching vibration peaks of CO in the molecule are 1147.92 and 914.57 cm -1 for-css - The stretching vibration peaks of C=S and CS in the above samples were analyzed. The S content was 34.11%, which is equivalent to CSS － Each chelating agent molecule contains an average of 1.97 CSS － The above results indicate that the arginine dithiocarboxylate chelator has been successfully synthesized.

[0063] Example 8

[0064] This example shows the treatment effect of the sample of Example 4 on heavy metal wastewater. The samples obtained in Example 4 (denoted as ARG-DTC, -CSS － The content of Pb was 5.361mmol / g) and commercially available DTCR were used as chelating agents to prepare 100mg / L 2+ 、Cd 2+ Cr 3+ , Cu 2+ 、Ni 2+ , Mn 2+ and Zn 2+ Simulated heavy metal water samples. Flocculation test conditions: Take 500mL simulated heavy metal water samples respectively, adjust the pH value to about 6.0, add chelating agent on MY3000-6G intelligent color screen coagulation test stirring instrument (Wuhan Meiyu Instrument Co., Ltd.), stir quickly at 220r / min for 5min, stir at 100r / min for 10min, and then stir slowly at 60r / min for 15min, let it stand for 20min, take the clear liquid 2cm below the liquid surface and measure it on AA-7000 atomic absorption spectrophotometer (Japan, Shimadzu Corporation), the treatment effect is shown in Table 1.

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

[0066]

[0067]

[0068] It can be seen from Table 1 that under the optimal conditions, the product ARG-DTC of the present invention is significantly better than the commercially available comparative sample sodium thiamethoxam in terms of free Pb 2+ 、Cd 2+ Cr 3+ , Cu 2+ 、Ni 2+ , Mn 2+ and Zn 2+ The plasma removal effect is good, and the residual ion concentration is far lower than the first-level standard of the "Comprehensive Wastewater Discharge Standard" (GB8978-1996), and the dosage is less. This is because ARG-DTC contains 1-COO — and 2 — CSS — , while DTCR only has -CSS — The two groups in ARG-DTC act synergistically to enhance the removal effect of heavy metal ions.

[0069] Example 9

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

[0071] The product ARG-DTC obtained in Example 4, the commercially available heavy metal scavenger sodium ferram and TMT-18 were used as reagents. Take 200 mL of wastewater sample, adjust the pH to about 6 with lime milk, and then place it on the MY3000-6G intelligent color screen coagulation test stirring instrument (Wuhan Meiyu Instrument Co., Ltd.), and add a certain amount of ARG-DTC, sodium ferram and TMT-18 chelating agents. The stoichiometric ratio of ARG-DTC and sodium ferram (i.e., the ratio of ARG-DTC or sodium ferram to the chelating agent) is 1:1. － CSS － The molar ratio of TMT-18 to heavy metal ions was 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 under stirring at 250 r / min and stirred for 5 min; then stirred at 100 r / min for 20 min (when stirring for 10 min, add appropriate amount of polyacrylamide PAM), and then stirred at 60 r / min for 15 min, and allowed to stand for 20 min, and 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 the present invention on comprehensive wastewater from electroplating plants

[0073]

[0074] The results in Table 2 show that the treatment effect of the product ARG-DTC of the present invention on this comprehensive electroplating wastewater is significantly better than that of the commonly used heavy metal scavengers sodium thiamethoxam and TMT-18 on the market, and the dosage is small, the turbidity of the treated water is low, and the pollutant indicators are all lower than the limit values ​​specified in the "Emission Standard of Pollutants for Electroplating" (GB21900-2008).

[0075] Example 10

[0076] ARG-DTC obtained in Example 4 was used as a chelating agent, and zinc concentrate from a copper foil production plant was treated. Its pollutant indicators are shown in Table 3, which show that it contains pyrophosphate and is colorless and transparent. The product ARG-DTC obtained in Example 3, commercially available heavy metal scavengers sodium formate and TMT-18 were used as reagents, respectively. Take 200 mL of the wastewater sample, first adjust the pH to about 6.0 with sulfuric acid, and then place it on a MY3000-6G intelligent color screen coagulation test stirring instrument (Wuhan Meiyu Instrument Co., Ltd.), and add a certain amount of ARG-DTC, sodium formate and TMT-18 chelating agents, respectively. The stoichiometric ratio of ARG-DTC and sodium formate (i.e., the ratio of ARG-DTC or sodium formate to CSS-1 in ARG-DTC or sodium formate) is 1:1. － The molar ratio of TMT-18 to heavy metal ions) is 1.85:1 and 2.1:1 respectively, and the stoichiometric ratio of TMT-18 is 1:1.5. The chelating agent was added under stirring at 220 r / min and stirred for 5 min; then stirred at 100 r / min for 20 min (adding an appropriate amount of polyacrylamide PAM during stirring for 10 min), and then stirred at 60 r / min for 20 min, and allowed to stand for 20 min, and samples were taken for analysis to test the concentration of heavy metal ions in the treated water. The results are listed in Table 3.

[0077] Table 3 The removal effect of the product of the present invention on zinc concentrated water of a copper foil production plant

[0078]

[0079] The results in Table 3 show that the treatment effect of the product ARG-DTC of the present invention on this kind of wastewater is significantly better than that of the common heavy metal scavengers sodium thiamethoxam and TMT-18 on the market. 2+ 、Zn 2+ 、Co 2+ The three ions are completely removed, and Cr 3+ It can also be removed to a lower concentration, and the pollutant indicators are all lower than the limit values ​​specified in the "Electroplating Pollutant Emission Standard" (GB21900-2008).

[0080] Embodiment 11

[0081] The product ARG-DTC obtained in Example 4, the commercially available heavy metal scavenger sodium fumei and TMT-18 were used as heavy metal stabilizers in incineration fly ash, and all were prepared into a solution with a mass fraction of 5%. During the test, 250g of fly ash from a waste incineration plant was added to a reaction kneader, and then stabilizer and water were added according to the mass ratio of fly ash: stabilizer: water = 100: 1-3: 20, and the mixture was fully stirred and kneaded for reaction for 20 minutes, and then the reaction was continued for 2 hours, and then samples were taken for leaching experiments according to the method specified in HJ / T300-2007, and the pollutant concentration in the leaching solution was determined. The results are shown in Table 4.

[0082] Table 4 Effects of the products of the present invention and commercially available stabilizers on incineration fly ash treatment

[0083]

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

[0085] The results of Examples 8 to 11 show that the product ARG-DTC of the present invention has better removal efficiency for free heavy metal wastewater and complex electroplating wastewater and heavy metal ions in copper foil production wastewater than the comparative samples, and has better chelating and stabilizing effect on incineration fly ash. The reason is that ARG-DTC contains CSS — and—COO — (N—CH—COO — ), which is easy to react with heavy metal ions in water Figure 3 Chelation shown: (1)—CSS — It is easy to chelate with heavy metal ions to form a water-insoluble disulfide coordinated four-membered ring chelate, — Cooperate with -NH- to form a stable The five-membered chelating ring and the two groups work synergistically to improve the chelating binding ability of heavy metal ions; (2) it can be obtained through two CSS from different ARG-DTC molecules. — Group or N—CH—COO — Chelate with the same heavy metal ion to form a water-insoluble disulfide coordinated four-membered ring chelate or two The five-membered chelate ring connects the chelates formed by different molecules and gradually grows to form larger flocs, thereby improving the efficiency of chelating and binding heavy metal ions and the stability of the chelate.

[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 also make various modifications and changes thereto. For example, within the range of the ratios and process conditions given in the present invention, the ratios and process conditions can be combined and changed. Similar changes and modifications belong to the essence of the present invention.

Claims

1. An arginine dithiocarboxylate chelating agent, characterized in that: The structure of its main component is shown in formula (I): In formula (I), M is Na or K; x=0 or 1. When x=0, the N atom is connected to a H atom.

2. The arginine dithioformate chelating agent according to claim 1, characterized in that The chelating agent also includes auxiliary ingredients xanthogenic acid and a base.

3. The method for preparing the arginine dithioformate chelating agent according to claim 1 or 2, characterized in that: The following steps are involved: (1) Add arginine and distilled water into a reactor at a mass ratio of arginine, alkali and distilled water of 1:0.51-1.35:10-15, stir and dissolve, then add alkali, and continue stirring for 1-1.5 hours after the alkali is dissolved to break the internal salt bond in the molecule and dehydrogenate the amino group into negative ammonia ion; (2) slowly adding carbon disulfide dropwise at a mass ratio of carbon disulfide to arginine of 0.44 to 0.92:1, and continuing the reaction at room temperature for 4 to 6 hours after the addition is complete; (3) Raise the temperature to 55-65°C and continue the reaction for 1-1.5 hours until the oil droplets disappear completely. Cool to room temperature to obtain an orange-red or red liquid, which is the product arginine dithiocarboxylate chelating agent.

4. The method for preparing the arginine dithioformate chelating agent according to claim 3, characterized in that: In step (1), the arginine is a product with a purity above industrial grade.

5. The method for preparing the arginine dithioformate chelating agent according to claim 3, characterized in that: In step (1), the base is NaOH or KOH.

6. The method for preparing the arginine dithioformate chelating agent according to claim 5, characterized in that: The NaOH or KOH is a product with purity above industrial grade.

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

8. The method for preparing the arginine dithioformate chelating agent according to claim 3, characterized in that: In step (2), the carbon disulfide is a product with a purity above industrial grade.

9. The method for preparing the arginine dithioformate chelating agent according to claim 3, characterized in that: In step (2), the time for slowly adding carbon disulfide is 40 to 60 minutes.

10. Use of the arginine dithioformate chelating agent obtained by the preparation method according to any one of claims 1 to 2 or any one of claims 3 to 9 in the treatment of heavy metals in heavy metal wastewater or incineration fly ash.

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