DTC heavy metal trapping agent as well as preparation method and application thereof

Abstract

The invention relates to a new material and an application technology thereof, in particular to a DTC heavy metal trapping agent and a preparation method and application thereof.The preparation method of the DTC heavy metal trapping agent comprises the following steps that 1, small molecule amine reacts with carbon disulfide under the condition that the pH ranges from 10 to 14, and a small molecule amine dithiocarbamate precursor is prepared; and step 2, enabling the micromolecular amine dithiocarbamate precursor prepared in the step 1 to react with triton X-100, so as to prepare micromolecular amine dithiocarbamate, namely the heavy metal trapping agent. The DTC heavy metal trapping agent can quickly react with thallium ions in water under the complex high-salt condition to generate a heavy metal chelate which is of a regular tetrahedral structure, small in spatial tension and high in stability, so that a large number of heavy metal ions such as Tl < + > can be trapped by adding a small amount of the metal trapping agent; therefore, effective treatment of the thallium-containing wastewater and up-to-standard discharge of the wastewater are realized.

Description

Technical Field

[0001] The present application relates to new materials and their applications, and specifically to a DTC heavy metal scavenger and its preparation method and application. Background Art

[0002] The conventional heavy metal emission problem in the steel industry has received certain attention and has been improved in the early period. However, with the further development of mining, ore dressing, smelting and other processes affiliated with the steel industry, low-concentration heavy metal emission pollution in the steel industry, represented by thallium (Tl), is bringing tremendous pressure to the environment in recent years.

[0003] At present, most of the heavy metal treatment methods in my country are chemical precipitation methods, but the chemical precipitation method has the following disadvantages: (1) Most industrial heavy metal wastewater is acidic, and the neutralization precipitation method requires the addition of a large amount of alkali solution, a large number of reagent preparation and dosing equipment, large infrastructure investment, a lot of sludge, difficult dehydration, and easy to cause secondary pollution; (2) The use of sulfide precipitation method will cause residual sulfur ions in the water, resulting in an increase in the COD content of the wastewater, and when the pH is lowered, toxic hydrogen sulfide gas will be produced; (3) The disadvantage of the flocculation precipitation method for treating heavy metal wastewater is that its removal effect is limited, and a single method is difficult to make the effluent meet the discharge standards.

[0004] Heavy metal chelation is an emerging heavy metal treatment method in recent years. It mainly utilizes the selective binding of specific functional groups in the molecular structure of the chelating agent to heavy metal ions to generate stable and water-insoluble metal chelates, and separates them from the original solvent or complex state. It has become one of the emerging heavy metal pollution control methods because of its good removal effect, renewable metal resources, and strong anti-interference ability.

[0005] However, the steel industry produces mostly industrial wastewater containing many types of heavy metal elements, complex composition, high salinity, and difficult to treat with conventional technologies. The heavy metal scavengers used in the existing heavy metal chelation method are no longer applicable. Summary of the invention

[0006] In order to solve at least one technical problem existing in the prior art, the present application provides a DTC heavy metal scavenger and a preparation method thereof and an application thereof in treating low-concentration heavy metal pollution.

[0007] In a first aspect, the present application provides a method for preparing a DTC heavy metal scavenger, comprising the following steps: Step 1: reacting a small molecule amine with carbon disulfide at pH 10 to 14 to obtain a small molecule amine dithiocarbamate precursor; Step 2: react the small molecule amine dithiocarbamate precursor prepared in step 1 with Triton X-100 to prepare a small molecule amine dithiocarbamate, i.e., a heavy metal scavenger.

[0008] Preferably, the step 1 comprises: Step 1.1, adding small molecule amines, sodium carbonate and anhydrous ethanol into a reaction vessel, mixing, and stirring in an ice-water bath for 1 to 3 hours; Step 1.2, adding carbon disulfide to the reaction system and stirring for 1 to 2 hours; Step 1.3: After step 1.2, the reaction container is heated to 40-50 degrees Celsius and stirred for 2-4 hours, and then washed and filtered to obtain a small molecule amine dithiocarbamate precursor.

[0009] Preferably, the small molecule amine is selected from one or more combinations of the following substances: ethylenediamine, 1,6-hexanediamine, urea, diethylenetriamine, and triethylenetetramine.

[0010] Preferably, the small molecule amine is a mixture of other amines, 1,6-hexanediamine and urea in a mass ratio of 4 to 10: 2: 2; the other amines refer to ethylenediamine, diethylenetriamine or triethylenetetramine.

[0011] Preferably, the small molecule amine is a mixture of triethylenetetramine, 1,6-hexanediamine and urea in a mass ratio of 9.7:2:2.

[0012] Preferably, in step 1.1, the mass ratio of small molecule amine, sodium carbonate and anhydrous ethanol is 1:1.2-1.6:6.2-8.2; in step 1.2, the mass ratio of small molecule amine to carbon disulfide is 1:1.5-3.

[0013] Preferably, the step 2 specifically includes: The small molecule amine dithiocarbamate precursor obtained in step 1 and Triton X-100 are added into a reaction container at a mass ratio of 7 to 5: 1 and mixed; stirred at a temperature of 30 to 40 degrees Celsius for 3 to 5 hours, and then the organic solvent is removed to obtain a small molecule amine dithiocarbamate.

[0014] Preferably, the mass ratio of the small molecule amine dithiocarbamate precursor to Triton X-100 is 7:1.6.

[0015] Another aspect of the present invention is to protect a DTC heavy metal scavenger prepared by any of the preparation methods described above.

[0016] In another aspect of the present invention, the use of the above-mentioned DTC heavy metal scavenger in the treatment of thallium-containing heavy metal wastewater is claimed, comprising the following steps: Step 1, using a pH regulator to adjust the pH of the wastewater; Step 2: adding a predetermined amount of the DTC heavy metal scavenger to the wastewater after pH adjustment, and stirring for a predetermined time.

[0017] Preferably, the pH adjuster in step 1 is a combination of one or more of sulfuric acid, liquid alkali, sodium carbonate and lime milk.

[0018] This application has at least the following beneficial technical effects: 1) In the DTC heavy metal scavenger and preparation method thereof of the present application, a small molecule amine such as 1,6-hexanediamine reacts with carbon disulfide to generate a small molecule amine dithiocarbamate precursor, and Triton X-100 is added to obtain a heavy metal scavenger with high chelating and capturing ability; the scavenger can react rapidly with thallium ions in water under complex high-salt conditions to generate a heavy metal chelate with a regular tetrahedral structure, small spatial tension and strong stability. The heavy metal chelate has a better effect of chelating and capturing Tl+ in water and has more superior performance. A small amount of heavy metal scavenger can capture a large amount of heavy metal ions such as Tl+, thereby achieving effective treatment of thallium-containing wastewater and ultimately achieving standard discharge of wastewater; 2) The DTC heavy metal scavenger of the present application has strong anti-interference ability and is suitable for a variety of occasions, and has a good effect even in the complex high-salt thallium-containing heavy metal wastewater in the steel industry; 3) In the preparation method of the DTC heavy metal scavenger of the present application, Triton X-100 is used. As a high-quality surfactant, it has emulsifying, dispersing, and solubilizing effects, which helps to disperse organic molecules and change the occurrence form of the dithiocarbamate obtained in the present invention.

[0019] 4) The process of the present invention uses low-cost products without affecting the capture efficiency of the obtained products, thereby greatly reducing the cost of wastewater treatment. DETAILED DESCRIPTION

[0020] The present application is further described below in conjunction with specific examples, and the protection content of the present application is not limited to the following examples. The experimental methods in the following examples that do not specify specific conditions are usually based on conventional conditions. The materials used in the following examples, etc., can be obtained from commercial channels unless otherwise specified. The experimental methods in the examples are conventional methods unless otherwise specified; the percentages in the examples are weight percentages unless otherwise specified.

[0021] The following will further describe in detail the DTC heavy metal scavenger and its preparation method and application of the present application: Example 1 Preparation of heavy metal scavenger 1: (1) Add 4 parts by weight of ethylenediamine, 2 parts by weight of 1,6-hexanediamine, 2 parts by weight of urea, 3 parts by weight of sodium hydroxide, 1 part by weight of sodium carbonate and 100 parts by weight of anhydrous ethanol into a 250 mL three-necked flask, stir for 2 h in an ice-water bath, then add 6 parts by weight of carbon disulfide and stir for 1.5 h; heat to 45°C in a water bath, stir and react for 3 h, wash and filter to obtain a hexamethylenediamine dithiocarbamate precursor, denoted as a.

[0022] (2) Add 7 parts of the above product a and 1.6 parts of Triton X-100 into a 250 mL three-necked flask, heat to 35°C in a water bath, stir and react for 4 hours, and distill to remove the organic solvent to obtain the product hexamethylenediamine dithiocarbamate, which is recorded as collector 1.

[0023] Example 2 Preparation of heavy metal scavenger 2: (1) Add 6.86 parts by weight of diethylenetriamine, 2 parts of 1,6-hexanediamine, 2 parts of urea, 3 parts of liquid alkali, 1 part of sodium carbonate and 100 parts of anhydrous ethanol into a 250 mL three-necked flask, stir for 2 h in an ice-water bath, then add 6 parts of carbon disulfide and stir for 1.5 h; heat to 45°C in a water bath, stir and react for 3 h, wash and filter to obtain a hexamethylenediamine dithiocarbamate precursor, denoted as a.

[0024] (2) Add 7 parts of the above product a and 1.6 parts of Triton X-100 into a 250 mL three-necked flask, heat to 35°C in a water bath, stir and react for 4 hours, and distill to remove the organic solvent to obtain the product hexamethylenediamine dithiocarbamate, which is recorded as collector 2.

[0025] Example 3 Preparation of heavy metal scavenger 3: (1) Add 9.73 parts by weight of triethylenetetramine, 2 parts of 1,6-hexanediamine, 2 parts of urea, 3 parts of liquid alkali, 1 part of sodium carbonate and 100 parts of anhydrous ethanol into a 250 mL three-necked flask, stir for 2 h in an ice-water bath, then add 6 parts of carbon disulfide and stir for 1.5 h; heat to 45°C in a water bath, stir and react for 3 h, wash and filter to obtain a hexamethylenediamine dithiocarbamate precursor, denoted as a.

[0026] (2) Add 7 parts of the above product a and 1.6 parts of Triton X-100 into a 250 mL three-necked flask, heat to 35°C in a water bath, stir and react for 4 h, and distill to remove the organic solvent to obtain the product hexamethylenediamine dithiocarbamate, which is recorded as collector 3.

[0027] Example 4 Preparation of heavy metal collector 4: (1) Add 9.73 parts by weight of triethylenetetramine, 2 parts of 1,6-hexanediamine, 2 parts of urea, 6 parts of liquid alkali, 2 parts of sodium carbonate and 100 parts of anhydrous ethanol into a 250 mL three-necked flask, stir for 2 h in an ice-water bath, then add 6 parts of carbon disulfide and stir for 1.5 h; heat to 45°C in a water bath, stir and react for 3 h, wash and filter to obtain a hexamethylenediamine dithiocarbamate precursor, denoted as a.

[0028] (2) Add 7 parts of the above product a and 1.6 parts of Triton X-100 into a 250 mL three-necked flask, heat to 35°C in a water bath, stir and react for 4 h, and distill to remove the organic solvent to obtain the product hexamethylenediamine dithiocarbamate, which is recorded as collector 4.

[0029] Example 5 Preparation of heavy metal scavenger 5: (1) Add 9.73 parts by weight of triethylenetetramine, 2 parts of 1,6-hexanediamine, 2 parts of urea, 9 parts of liquid alkali, 3 parts of sodium carbonate and 100 parts of anhydrous ethanol into a 250 mL three-necked flask, stir for 2 h in an ice-water bath, then add 6 parts of carbon disulfide and stir for 1.5 h; heat to 45°C in a water bath, stir and react for 3 h, wash and filter to obtain a hexamethylenediamine dithiocarbamate precursor, denoted as a.

[0030] (2) Add 7 parts of the above product a and 1.6 parts of Triton X-100 into a 250 mL three-necked flask, heat to 35°C in a water bath, stir and react for 4 h, and distill to remove the organic solvent to obtain the product hexamethylenediamine dithiocarbamate, which is recorded as collector 5.

[0031] Example 6 Preparation of heavy metal capture agent 6: (1) Add 9.73 parts by weight of triethylenetetramine, 2 parts of 1,6-hexanediamine, 2 parts of urea, 12 parts of liquid alkali, 4 parts of sodium carbonate and 100 parts of anhydrous ethanol into a 250 mL three-necked flask, stir for 2 h in an ice-water bath, then add 6 parts of carbon disulfide and stir for 1.5 h; heat to 45°C in a water bath, stir and react for 3 h, wash and filter to obtain a hexamethylenediamine dithiocarbamate precursor, denoted as a.

[0032] (2) Add 7 parts by weight of the above product a and 1.6 parts of Triton X-100 into a 250 mL three-necked flask, heat to 35°C in a water bath, stir and react for 4 hours, and distill to remove the organic solvent to obtain the product hexamethylenediamine dithiocarbamate, which is recorded as collector 6.

[0033] Application Examples Test reagents: Collectors 1 to 6; Precursor a of the trapping agent 6; Comparative sample 1: 3,6-di-tert-butyl-9H-carbazole-9-carbon disulfate sodium; Comparative sample 2: polyethyleneimine dithiocarbamate (PEI-DTC); Test steps: Weigh 0.05 g of the test agent and add 100 mL of 0.024 mmol / L Tl + In the heavy metal ion solution, and 100 mL of Pb with a concentration of 1mmol / L 2+ 、Ni 2+ 、Cd 2+ , Hg 2+ Cr 3+ The metal ion solution was magnetically stirred for 30 min and filtered to obtain the captured solution.

[0034] Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the metal ion concentration in the solution before and after capture, and the capture efficiency was calculated. The results are shown in Table 1 below.

[0035] Table 1. The capture and removal rates of heavy metals by the present application and the existing methods

[0036] Notes and additional information: Q Tl (%) indicates Tl + The capture and removal rate of other metals is expressed in the same way; Metal ion Tl + The concentration is 0.024 mmol / L, and the corresponding mass concentration is 5 mg / L; Pb 2+ 、Ni 2+ 、Cd 2+ , Hg 2+ Cr 3+ The concentration is 1 mmol / L, and the corresponding mass concentrations are 207 mg / L, 58 mg / L, 112 mg / L, 200 mg / L, and 52 mg / L; Cost: refers to the cost of treating 1 ton of simulated wastewater (metal ion concentration is 1 mmol / L); From the comparison results of the application examples in Table 1 above, it can be seen that from the capture efficiency point of view, the effects of the collectors 3, 4, 5, and 6 of the present invention are close to the heavy metal capture agent polyethyleneimine dithiocarbamate known in the art, but the raw material cost is less than 2% of the comparative sample 2.

[0037] Similarly, collectors 3, 4, and 5 have higher capture efficiency than comparative sample 1, but their costs are only 30-40% of that of comparative sample 1.

[0038] The capture efficiency of collectors 1 and 2 is slightly lower than that of comparative sample 1, but both are above 90%, and are still valuable heavy metal collectors.

[0039] Collectors 3, 4, 5, and 6 are prepared by using a combination of triethylenetetramine, 1,6-hexanediamine, and urea as small molecule amine sources, and their capture efficiencies are significantly higher than those of collectors 1 and 2.

[0040] The capture efficiency of the intermediate product a of the collector 6 is only 70-80% of that of the final product, indicating that in the preparation method provided by the present invention, the emulsification, dispersion, and solubilization effects of Triton X-100 significantly improve the occurrence form of dithiocarbamates and improve the capture efficiency of heavy metals.

[0041] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a DTC heavy metal scavenger, characterized in that: The steps include: Step 1: reacting a small molecule amine with carbon disulfide at pH 10 to 14 to obtain a small molecule amine dithiocarbamate precursor; Step 2: react the small molecule amine dithiocarbamate precursor prepared in step 1 with Triton X-100 to prepare a small molecule amine dithiocarbamate, i.e., a heavy metal scavenger.

2. The preparation method according to claim 1, characterized in that: The step 1 comprises: Step 1.1, adding small molecule amines, sodium carbonate and anhydrous ethanol into a reaction vessel, mixing, and stirring in an ice-water bath for 1 to 3 hours; Step 1.2, adding carbon disulfide to the reaction system and stirring for 1 to 2 hours; Step 1.3: After step 1.2 is completed, the reaction container is heated to 40-50 degrees Celsius and stirred for 2-4 hours, and then washed and filtered to obtain a small molecule amine dithiocarbamate precursor.

3. The preparation method according to claim 1, characterized in that: The small molecule amine is selected from one or more combinations of the following substances: ethylenediamine, 1,6-hexanediamine, urea, diethylenetriamine, and triethylenetetramine.

4. The preparation method according to claim 1, characterized in that: The small molecule amine is a mixture of other amines, 1,6-hexanediamine and urea in a mass ratio of 4 to 10: 2: 2; the other amines refer to ethylenediamine, diethylenetriamine or triethylenetetramine.

5. The preparation method according to claim 1, characterized in that: The small molecule amine is a mixture of triethylenetetramine, 1,6-hexanediamine and urea in a mass ratio of 9.7:2:

2.

6. The preparation method according to claim 2, characterized in that: In the step 1.1, the mass ratio of small molecule amine, sodium carbonate and anhydrous ethanol is 1:1.2-1.6:6.2-8.2; in the step 1.2, the mass ratio of small molecule amine to carbon disulfide is 1:1.5-3.

7. The preparation method according to claim 1, characterized in that: The step 2 specifically includes: The small molecule amine dithiocarbamate precursor obtained in step 1 and Triton X-100 are added into a reaction container at a mass ratio of 7 to 5: 1 and mixed; stirred at a temperature of 30 to 40 degrees Celsius for 3 to 5 hours, and then the organic solvent is removed to obtain a small molecule amine dithiocarbamate.

8. The preparation method according to claim 7, characterized in that: The mass ratio of the small molecule amine dithiocarbamate precursor to Triton X-100 is 7:1.

6.

9. A DTC heavy metal scavenger prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the DTC heavy metal scavenger according to claim 9 in the treatment of thallium-containing heavy metal wastewater, characterized in that: The steps include: Step 1, using a pH regulator to adjust the pH of the wastewater; Step 2: adding a predetermined amount of the DTC heavy metal scavenger to the wastewater after pH adjustment, and stirring for a predetermined time.

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