A dimeric polyethylene polyamine-based bis-chelating group heavy metal chelating flocculant, a preparation method and application thereof

Abstract

This invention discloses a dimerized polyethylene polyamine-based double-chelating heavy metal chelating flocculant, its preparation method, and its application. First, polyethylene polyamine is copolymerized with epichlorohydrin in the presence of NaOH to form a dimer. Then, it undergoes a nucleophilic addition reaction with carbon disulfide in the presence of an alkaline environment to form a -CSS... － The acetate groups are introduced into the non-terminal positions of the dimeric polyethylene polyamine molecular chain; then, under strongly alkaline conditions, an electrophilic substitution reaction occurs with sodium haloacetate to introduce acetate groups into both ends of the molecular chain, forming a compound with -N(CH2COO) groups at both ends of a relatively long molecular chain. － )2 groups, with multiple —CSS connected in the middle － The structure of the functional groups. The product molecules of this invention have superior molecular chain length and chelating group distribution, enhancing their chelation and binding ability for heavy metal ions. The resulting flocs are dense and coarse, exhibiting excellent sedimentation and separation performance. This invention features a simple process, mild reaction conditions, and easy operation and control, making it readily suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the fields of heavy metal wastewater treatment and heavy metal stabilization in incineration fly ash, specifically to a dimeric polyethylene polyamine dichelate heavy metal chelating flocculant, its preparation method, and its application. Background Technology

[0002] Heavy metals or metalloids such as Hg, Pb, Cu, Cd, Cr, Zn, Mn, Ni, Co, Ag, Fe, and As, with the exception of a few essential trace elements like Zn, Cu, Mo, Cr, Co, and Fe, are mostly non-essential for the human body. Even essential trace elements can have serious toxic effects on the human body if exceeded in excess. Because heavy metals are non-biodegradable, produce significant toxicity even in trace amounts, and are cumulative, they easily enter the human body through the food chain, not only damaging the ecological environment but also posing a serious threat to human life. With the rapid development of industries such as electroplating, metallurgy, mineral mining, and battery manufacturing, wastewater containing large amounts of heavy metal ions or compounds is discharged into soil and water bodies, harming the growth and reproduction of aquatic organisms and plants, severely damaging the ecological environment, and posing a serious threat to human drinking water and other water uses. Therefore, the effective treatment of heavy metal wastewater has become a pressing global problem that needs to be solved in the field of environmental protection.

[0003] Heavy metals are non-biodegradable; their pollution and hazards can only be eliminated by altering their mode of existence and form. Developed treatment methods include chemical precipitation, ion exchange, flotation, adsorption, electrochemical methods, chelation flocculation (precipitation), and biological methods. Ion exchange utilizes ion exchange resins to replace heavy metal ions in solution, but its treatment efficiency is low, its applicability is limited, and it easily generates high-concentration elution wastewater that is difficult to treat, causing secondary pollution. In flotation, surfactants are used to bind heavy metal ions; although it has a large treatment capacity and fast operation, the effluent has high salinity, and scum is difficult to control. Adsorption methods, while using widely available materials and achieving relatively thorough heavy metal removal, suffer from the small adsorption capacity of natural adsorbents, difficulties in elution and regeneration, and the generation of large amounts of difficult-to-dispose-of solid hazardous waste. Synthetic adsorbents, on the other hand, suffer from high manufacturing costs and difficulties in elution, regeneration, and post-treatment. Electrochemical methods have limitations in their selectivity for heavy metal ions, limited applicability, high operational control requirements, and high cost. Phytoremediation, a biological approach, is often used to control heavy metals in soil but is unsuitable for the accumulation and removal of heavy metals in water. Furthermore, this method only transfers heavy metals, not removes them from the environment. Traditional chemical precipitation methods consume large amounts of chemicals and easily generate large quantities of hazardous waste that is difficult to dispose of. Compared to these methods, chelation flocculation (precipitation) utilizes chelating flocculants to bind heavy metal ions in water through chelation and then separates them from the water through flocculation (precipitation), achieving highly efficient removal of heavy metals from water, significantly reducing the amount of heavy metal-containing waste generated, and the generated waste is easily further separated, recycled, and converted. Therefore, it is suitable for large-scale treatment of various heavy metal wastewaters.

[0004] The key to chelation flocculation (precipitation) lies in the performance of the chelating agent or chelating flocculant. Currently, the heavy metal treatment agents that have been developed and widely used mainly fall into two categories: organosulfur compounds and dithiocarbamates (DTCs). The most representative organosulfur compound is sodium trithiotriazine (TMT), a heavy metal ion trapping agent; DTC chelating agents mainly include HMP-2000, sodium fumarate, ethyl thiocyanate, ethylenediamine heavy metal chelating agent (CN101857296B), N,N'-didithiopiperazine carbamate, and high molecular weight heavy metal ion trapping and precipitating agents (DTCR). These products all have a single chelating group; for example, the chelating group of TMT is -SH(Na), while the chelating group of DTCs is a single dithiocarbamate group (-CSS). －Therefore, DTCs have weak chelating and binding abilities for some heavy metal ions; for example, they are not very effective in treating wastewater containing heavy metals such as Cr, Zn, and Ni. They are also less effective in treating complex or compound pollutants containing multiple heavy metal ions or heavy metals coexisting with organic and inorganic matter, and it is difficult to achieve effective removal of multiple heavy metal ions in one step. Ethylenediaminetetraacetic acid (EDTA) is a widely used strong chelating agent that can form stable chelates with most metal ions, mainly due to the presence of a -N(CH2COO) ion. － )2. Chelating groups can form two stable chelates with most metal ions. Five-membered ring. Therefore, introducing —N(CH2COO) into the chelating agent molecule. － The -N(CH2COO) group will inevitably enhance the chelation and binding ability of heavy metal ions. － A significant portion of the chelates formed by 2 and metal ions are water-soluble and difficult to separate from water; while —CSS － The chelates formed by chelation with heavy metal ions are insoluble in water and easily separated from water as precipitates. Therefore, -CSS － and —N(CH2COO) － If 2 is combined with the same chelating agent molecule, it can be chelated through —N(CH2COO) － )2 will be with —CSS － Heavy metal ions with weak chelation are firmly bound and bind through -CSS － The insoluble dithiocarbamate chelates formed precipitate and separate from the water. The two components complement each other, synergistically improving the removal efficiency of heavy metals from wastewater, achieving efficient removal of multiple heavy metal ions in one step. Research and practice have shown that appropriately increasing the molecular (chain) size of the chelating agent—that is, having more chelating groups in one chelating agent molecule—can bind more heavy metal ions. This facilitates aggregation and floc formation under the action of the molecular chain, resulting in larger and more compact flocs, which are beneficial for sedimentation separation and floc dewatering, and facilitate subsequent treatment. However, when the molecular chain reaches a certain length, steric hindrance can cause a significant portion of the chelating groups to be "suspended" due to spatial mismatch. This results in the formed micro-flocs carrying too much of the same charge (usually negative), which is detrimental to floc growth. Therefore, while considering the chelating groups, the molecular size must also be taken into account. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a dimeric polyethylene polyamine-based double chelating group heavy metal chelating flocculant, its preparation method, and its application.

[0006] The heavy metal chelating flocculant with dimeric polyethylene polyamine dual chelating groups provided by this invention is characterized by having both -CSS and other molecular properties. － and —N(CH2COO)－ Two strong chelating groups complement each other, exhibiting a strong chelating and binding ability for the vast majority of heavy metal ions in water. They also possess relatively long molecular chains containing numerous strong chelating groups, which can aggregate the formed chelates through molecular chain linkages to form micro-flocculations, thereby promoting floc formation and growth. Therefore, it possesses both strong chelating and binding ability for the vast majority of heavy metals and excellent flocculation and sedimentation performance, enabling efficient removal of multiple heavy metal ions in one step, thus broadening its application range. The structure of its main components is shown in formula (Ⅰ).

[0007]

[0008] In equation (I), 2 ≤ x ≤ 4, 1 ≤ y ≤ x, and x and y are both integers; when y < x, there are x - y N-connected H atoms. The molecule simultaneously contains -CSS － and —N(CH2COO) － )2 Two strong chelating groups; the auxiliary components are xanthic acid and

[0009] NaOH appears as a reddish-brown or brownish-red viscous liquid.

[0010] The preparation method of the above-mentioned dimeric polyethylene polyamine double chelating group heavy metal chelating flocculant includes the following steps:

[0011] (1) Add polyethylene polyamine to the reactor at a molar ratio of 2:1 to 1.05, and slowly add epichlorohydrin dropwise at room temperature for 1 to 1.5 hours; then add an amount of alkali or alkaline salt solution equal to the amount of epichlorohydrin dropwise and continue the reaction for 1 to 2 hours.

[0012] (2) Dilute with 5 to 6 times the volume of the reaction mixture in step (1) with distilled water, and then add NaOH at a ratio of (n-1) times the amount of polyethylene polyamine to the amount of NaOH of 1:0.55 to 1.2, where n represents the number of N atoms in the polyethylene polyamine molecule. Stir at room temperature for 0.5 to 1 h.

[0013] (3) Add carbon disulfide at a ratio of (n-1) times the amount of polyethylene polyamine to the amount of carbon disulfide of 1:0.25-1.05, where n represents the number of N atoms in the polyethylene polyamine molecule. Stir the reaction at room temperature for 3.5-5 hours until the bottom oil droplets disappear. Then heat the mixture to 50-60℃ and react for 1-1.5 hours. Then cool the mixture to room temperature to obtain solution A.

[0014] (4) According to the molar ratio of sodium haloacetate to polyethylene polyamine of 2.05 to 2.1:1, weigh sodium haloacetate and add it to the reactor, add distilled water to prepare a solution with a mass fraction of 30% to 35%, and obtain solution B;

[0015] (5) Add solution A obtained in step (3) to solution B obtained in step (4) and mix thoroughly; then weigh the alkali or alkaline salt according to the molar ratio of alkali or alkaline salt to polyethylene polyamine of 2 to 2.1:1, add distilled water to prepare a solution with a mass fraction of 20% to 30%, add it slowly in three batches, and wait until the pH value of the solution drops to 9 to 11 before adding the next batch. After adding all the batches, continue to react at room temperature for 4 to 6 hours, then raise the temperature to 50 to 60°C and continue to react for 1 to 1.5 hours. Cool to room temperature to obtain the dimeric polyethylene polyamine-based double chelate group heavy metal chelate flocculant.

[0016] Further, in step (1), the polyethylene polyamine is any one of diethylenetriamine, triethylenetetramine, or tetraethylenepentamine, preferably triethylenetetramine.

[0017] Furthermore, in steps (1) and (5), the alkali or alkaline salt is either NaOH or Na2CO3, preferably NaOH.

[0018] Furthermore, in step (3), the haloacetate is either sodium chloroacetate or sodium bromoacetate, preferably sodium chloroacetate.

[0019] Further, in step (1), the epichlorohydrin is added slowly at a rate of 1 to 2 drops / min; in step (5), the alkali or alkaline salt is added slowly over a time of 40 to 60 minutes.

[0020] Furthermore, the polyethylene polyamine, epichlorohydrin, alkali or alkaline salt, carbon disulfide, and sodium haloacetate mentioned are all products of industrial grade or higher purity, and no further purification is required before use.

[0021] Furthermore, in steps (1) and (4), the reactors are equipped with mechanical stirring, a dripping funnel, and a reflux condenser.

[0022] The above-mentioned chelating flocculant is applied to the treatment of heavy metals in various types of heavy metal wastewater or incineration fly ash, and the treatment effect is excellent.

[0023] This invention relates to a method for preparing a heavy metal chelating flocculant with a dimeric polyethylene polyamine-based double chelating group. First, a polyethylene polyamine is copolymerized with epichlorohydrin under the assistance of NaOH to form a dimer, doubling the molecular chain length. Then, it undergoes a nucleophilic addition reaction with carbon disulfide in the presence of an alkaline environment, preferentially adding -CSS groups. －The acetate group (—CH2COO) is introduced into the non-terminal position of the dimeric polyethylene polyamine molecular chain and then undergoes an electrophilic substitution reaction with sodium haloacetate under strongly alkaline conditions to transform the acetate group. － The addition of N(CH2COO) groups to both ends of the molecular chain forms two sets of strong chelating groups. － )2, forming a compound with -N(CH2COO) at both ends of a relatively long molecular chain. － )2 groups, multiple —CSS linked in the middle of the molecular chain － The structure of the chelating groups. This invention overcomes the shortcomings of common chelating agents, which have single chelating groups and poor chelation binding ability for some heavy metals. It also makes the product molecules have better molecular chain length and chelating group distribution, which significantly improves the chelation binding ability for most heavy metal ions. This is conducive to promoting the formation and growth of micro-flocs, making the flocs dense and coarse, improving sedimentation and separation performance, and facilitating the post-processing and recycling of sludge.

[0024] The advantages of this invention compared to the prior art are as follows:

[0025] (1) This invention extends the molecular chain to twice its original length by copolymerizing polyethylene polyamine with epichlorohydrin, giving the product molecule a better molecular chain length. This overcomes the disadvantage that chelating agents, due to their short molecular chains and few chelating groups, cannot chelate multiple heavy metal ions through the same molecular chain and form larger micro-flocs through the linkage of their molecular chains, or the disadvantage that due to their long molecular chains, they cannot extend in aqueous solution, making it difficult for some chelating groups to chelate and bind heavy metal ions. This allows the chelating groups in the chelating agent to be fully utilized, reducing the excessive negative charge on the micro-flocs formed due to the failure to chelate heavy metal ions, thus facilitating the further growth of micro-flocs; by utilizing the nucleophilic addition reaction, which preferentially occurs at the secondary amine position of the polyamine, -CSS － The group is introduced into the secondary amine position of the polyamine to ensure the introduction of —CH2COO in the subsequent stage. － It can only enter the terminal positions of the dimeric polyethylene polyamine molecular chain, thereby achieving effective regulation and optimization of the molecular structure.

[0026] (2) The product of this invention has both a suitable molecular chain length and the properties of -CSS － and —N(CH2COO) － )2 Two strong chelating groups, possessing a large number of chelating functional groups and an optimized group distribution, overcome the shortcomings of common chelating agents with single functional groups and weak chelating and binding ability for some heavy metal ions; among them, —CSS － and —N(CH2COO) －)2 can leverage the strengths of both products to synergistically enhance the chelation and binding capacity for the vast majority of heavy metal ions. Furthermore, through the linkage of molecular chains, it effectively promotes the formation and growth of micro-flocculations, significantly improving their flocculation and sedimentation performance, thus achieving highly efficient removal of multiple heavy metal ions from water in one step. Therefore, it effectively broadens the product's applicability.

[0027] (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. The —N(CH2COO) group in the product molecule... － The α2 group can extract heavy metal ions from most heavy metal chelates that are slightly weaker than itself, enabling the product of this invention to effectively treat not only free heavy metal wastewater but also most complexed heavy metal wastewater. Because the product of this invention can form stable chelates with the vast majority of heavy metal ions in water, it can achieve highly efficient removal of multiple heavy metal ions in one step, especially exhibiting excellent treatment effects on complex wastewater containing multiple heavy metal ions and composite heavy metal wastewater composed of heavy metals, organic pollutants, or multiple inorganic ions.

[0028] (4) When the product of this invention is used in actual wastewater treatment, a certain amount of the product of this invention is added to the heavy metal wastewater and stirred thoroughly to quickly generate insoluble flocs, which can be separated by sedimentation and filtration. No complicated equipment and procedures are required. Therefore, the treatment process is simple and conducive to promotion and application.

[0029] (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.

[0030] This invention is suitable for the treatment of various heavy metal wastewaters and the fixation of heavy metals in incineration fly ash. It has excellent treatment effects, especially for complex wastewater containing multiple heavy metal ions and complex heavy metal wastewater composed of heavy metals, organic pollutants, or multiple inorganic ions. Attached Figure Description

[0031] Figure 1 This is a flowchart of the preparation method of the present invention.

[0032] Figure 2 The infrared spectrum of the heavy metal chelating flocculant (sample of Example 5) of the present invention is shown.

[0033] Figure 3 This is a diagram illustrating the chelation and flocculation mechanism of the product of this invention. Detailed Implementation

[0034] 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.

[0035] Examples 1-12 illustrate the preparation methods of the heavy metal chelating flocculant with dimeric polyethylene polyamine double chelating groups, a product of the present invention. Examples 13-17 illustrate application examples of the product of the present invention.

[0036] Example 1

[0037] (1) Take 13.1 mL of 99.00% diethylenetriamine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 4.8 mL of 98.00% epichlorohydrin at a rate of 2 drops / min. After the addition is complete, react for 1.5 h. Then add 6.0 mL of 30.00% NaOH solution and continue the reaction for 2 h.

[0038] (2) Add 120 mL of distilled water to dilute, then add 6.3 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0039] (3) Take 7.8 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 3.5 h until the bottom oil droplets disappear. Then heat the solution to 60 °C and react for 1 h, and then cool it down to room temperature.

[0040] (4) Take 29.24g of sodium chloroacetate with a mass fraction of 98% and add it to a 500mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. Add 66.3mL of distilled water to prepare a solution with a mass fraction of 30.00%.

[0041] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.00g of solid NaOH with a mass fraction of 96%, add 22.0mL of distilled water to dissolve and prepare a solution with a mass fraction of 30.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 40min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 4h, then raise the temperature to 60℃ and continue to react for 1h. Cool to room temperature to obtain 247.4mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0042] Example 2

[0043] (1) Take 13.1 mL of 99.00% diethylenetriamine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 5.1 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1 h. Then add 7.5 mL of 26.00% NaOH solution and continue the reaction for 1.5 h.

[0044] (2) Add 124 mL of distilled water to dilute, then add 11.00 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0045] (3) Take 15.6 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 5.5 h until the bottom oil droplets disappear. Then heat the solution to 50 °C and react for 1.5 h. Then cool the solution to room temperature.

[0046] (4) Take 29.95g of sodium chloroacetate 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. Add 61.8mL of distilled water to prepare a solution with a mass fraction of 32.00%.

[0047] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.50g of solid NaOH with a mass fraction of 96.00%, add 28.3mL of distilled water to dissolve and prepare a solution with a mass fraction of 26.00%, transfer it into a dropping funnel and add it in 3 batches, each batch for 50min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 5h, then raise the temperature to 55℃ and continue to react for 0.75h. Cool to room temperature to obtain 270.0mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0048] Example 3

[0049] (1) Take 13.1 mL of 99.00% diethylenetriamine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 4.9 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1.25 h. Then add 10.1 mL of 20.00% NaOH solution and continue the reaction for 1.5 h.

[0050] (2) Add 130.0 mL of distilled water to dilute, then add 8.25 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0051] (3) Take 11.7 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 4 h until the bottom oil droplets disappear. Then heat the solution to 52 °C and react for 1.25 h. Then cool the solution to room temperature.

[0052] (4) Take 29.24g of sodium chloroacetate 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. Add 52.6mL of distilled water to prepare a solution with a mass fraction of 32.00%.

[0053] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.25g of solid NaOH with a mass fraction of 96.00%, add 39.0mL of distilled water to dissolve and prepare a solution with a mass fraction of 20.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 60min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 6h, then raise the temperature to 50℃ and continue to react for 1.5h. Cool to room temperature to obtain 278.4mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0054] Example 4

[0055] (1) Take 18.8 mL of 95.00% triethylenetetramine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 4.8 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1 h. Then add 6.0 mL of 30.00% NaOH solution and continue the reaction for 1 h.

[0056] (2) Add 120.0 mL of distilled water to dilute, then add 5.78 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 0.5 h;

[0057] (3) Take 11.7 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 4 h until the bottom oil droplets disappear. Then heat the solution to 52 °C and react for 1.25 h. Then cool the solution to room temperature.

[0058] (4) Take 29.24g of sodium chloroacetate 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. Add 64.3mL of distilled water to prepare a solution with a mass fraction of 30.00%.

[0059] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.30g of solid NaOH with a mass fraction of 96.00%, add 29.3mL of distilled water to dissolve and prepare a solution with a mass fraction of 25.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 40min. Add the next batch after the pH of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 4h, then raise the temperature to 50℃ and continue to react for 1.5h. Cool to room temperature to obtain 263.2mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0060] Example 5

[0061] (1) Take 18.8 mL of 95.00% triethylenetetramine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 4.9 mL of 98.00% epichlorohydrin at a rate of 2 drops / min. After the addition is complete, react for 1.25 h. Then add 10.0 mL of 20.00% NaOH solution and continue the reaction for 1 h.

[0062] (2) Add 125.0 mL of distilled water to dilute, then add 11.00 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0063] (3) Take 15.6 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 3.5 h until the bottom oil droplets disappear. Then heat the solution to 55 °C and react for 1 h, and then cool it down to room temperature.

[0064] (4) Take 30.04g of sodium chloroacetate 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. Add 62.0mL of distilled water to prepare a solution with a mass fraction of 32.00%.

[0065] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.50g of solid NaOH with a mass fraction of 96.00%, add 23.1mL of distilled water to dissolve and prepare a solution with a mass fraction of 30.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 50min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 4h, then raise the temperature to 55℃ and continue to react for 1.25h. Cool to room temperature to obtain 277.6mL of reddish-brown liquid, which is the dimeric polyethylene polyamine dichelate heavy metal chelate flocculant, denoted as IDA-DTETA-DTC.

[0066] Using triethylenetetramine (TETA) as raw material, a triethylenetetramine dimer grafted with dithiocarbamate chelating flocculant was prepared according to the proportions and conditions of steps (1) to (3) of this embodiment, and was denoted as DTETA-DTC.

[0067] Example 6

[0068] (1) Take 18.8 mL of 95.00% triethylenetetramine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 5.1 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1.5 h. Then add 7.6 mL of 26.00% NaOH solution and continue the reaction for 1 h.

[0069] (2) Add 126.0 mL of distilled water to dilute, then add 16.50 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 0.75 h;

[0070] (3) Take 23.4 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 5 h until the bottom oil droplets disappear. Then heat the solution to 60 °C and react for 1.5 h. Then cool the solution to room temperature.

[0071] (4) Take 29.76g of sodium chloroacetate 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. Add 53.6mL of distilled water to prepare a solution with a mass fraction of 32.00%.

[0072] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.25g of solid NaOH with a mass fraction of 96.00%, add 22.6mL of distilled water to dissolve and prepare a solution with a mass fraction of 30.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 60min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 6h, then raise the temperature to 60℃ and continue to react for 1.5h. Cool to room temperature to obtain 272.9mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0073] Example 7

[0074] (1) Take 18.8 mL of 95.00% triethylenetetramine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 5.0 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1.5 h. Then add 27.0 mL of 20.00% Na2CO3 solution and continue the reaction for 2 h.

[0075] (2) Add 130.0 mL of distilled water to dilute, then add 12.00 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0076] (3) Take 15.6 mL of carbon disulfide with a mass fraction of 99.000% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 5 h until the bottom oil droplets disappear. Then heat the solution to 60 °C and react for 1 h. Then cool the solution to room temperature.

[0077] (4) Take 40.40g of sodium bromoacetate 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. Add 91.6mL of distilled water to prepare a solution with a mass fraction of 30.00%.

[0078] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 25.69g of solid Na2CO3 with a mass fraction of 99.00%, add 101.5mL of distilled water to dissolve and prepare a solution with a mass fraction of 20.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 60min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 6h, then raise the temperature to 60℃ and continue to react for 1.5h. Cool to room temperature to obtain 401.4mL of orange-red liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0079] Example 8

[0080] (1) Take 18.8 mL of 95.00% triethylenetetramine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 4.8 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1.5 h. Then add 6.1 mL of 30.00% NaOH solution and continue the reaction for 2 h.

[0081] (2) Add 120.0 mL of distilled water to dilute, then add 11.00 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0082] (3) Take 15.6 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 5 h until the bottom oil droplets disappear. Then heat the solution to 55 °C and react for 1.5 h. Then cool the solution to room temperature.

[0083] (4) Take 41.38g of sodium bromoacetate 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. Add 74.5mL of distilled water to prepare a solution with a mass fraction of 35.00%.

[0084] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.50g of solid NaOH with a mass fraction of 96.00%, add 23.1mL of distilled water to dissolve and prepare a solution with a mass fraction of 30.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 60min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 6h, then raise the temperature to 60℃ and continue to react for 1h. Cool to room temperature to obtain 276.8mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelating flocculant.

[0085] Example 9

[0086] (1) Take 24.0 mL of 95.00% tetraethylenepentamine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 4.8 mL of 98.00% epichlorohydrin at a rate of 2 drops / min. After the addition is complete, react for 1 h. Then add 9.9 mL of 20.00% NaOH solution and continue the reaction for 1 h.

[0087] (2) Dilute with 124.0 mL of distilled water, then add 5.78 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 0.5 h;

[0088] (3) Take 7.7 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 3.5 h until the bottom oil droplets disappear. Then heat the solution to 50 °C and react for 1.25 h. Then cool the solution to room temperature.

[0089] (4) Take 29.24g of sodium chloroacetate 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. Add 66.3mL of distilled water to prepare a solution with a mass fraction of 30.00%.

[0090] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.50g of solid NaOH with a mass fraction of 96.00%, add 29.8mL of distilled water to dissolve and prepare a solution with a mass fraction of 25.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 60min. Add the next batch after the pH of the reaction solution drops to about 10. After adding all the batches, continue to react at room temperature for 4.5h, then raise the temperature to 60℃ and continue to react for 1h. Cool to room temperature to obtain 278.0mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0091] Example 10

[0092] (1) Take 24.0 mL of 95.00% tetraethylenepentamine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 5.0 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1.25 h. Then add 7.4 mL of 26.00% NaOH solution and continue the reaction for 1.5 h.

[0093] (2) Add 122.0 mL of distilled water to dilute, then add 10.50 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 0.75 h;

[0094] (3) Take 15.6 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 4.5 h until the bottom oil droplets disappear. Then heat the solution to 55 °C and react for 1.25 h. Then cool the solution to room temperature.

[0095] (4) Take 29.52g of sodium chloroacetate 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. Add 60.9mL of distilled water to prepare a solution with a mass fraction of 32.00%.

[0096] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.35g of solid NaOH with a mass fraction of 96.00%, add 25.1mL of distilled water to dissolve and prepare a solution with a mass fraction of 28.00%, transfer it into a dropping funnel and add it in 3 batches, each batch for 50min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 5h, then raise the temperature to 60℃ and continue to react for 1.25h. Cool to room temperature to obtain 275.8mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0097] Example 11

[0098] (1) Take 24.0 mL of 95.00% tetraethylenepentamine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 5.1 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1.5 h. Then add 6.3 mL of 30.00% NaOH solution and continue the reaction for 1.5 h.

[0099] (2) Add 120.0 mL of distilled water to dilute, then add 16.50 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0100] (3) Take 23.4 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 5 h until the bottom oil droplets disappear. Then heat the solution to 60 °C and react for 1 h. Then cool the solution to room temperature.

[0101] (4) Take 29.33g of sodium chloroacetate 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. Add 52.8mL of distilled water to prepare a solution with a mass fraction of 35.00%.

[0102] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.50g of solid NaOH with a mass fraction of 96.00%, add 23.1mL of distilled water to dissolve and prepare a solution with a mass fraction of 30.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 60min. Add the next batch after the pH value of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 6h, then raise the temperature to 60℃ and continue to react for 1.5h. Cool to room temperature to obtain 275.6mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0103] Example 12

[0104] (1) Take 24.0 mL of 95.00% tetraethylenepentamine and add it to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser. At room temperature, slowly add 4.9 mL of 98.00% epichlorohydrin at a rate of 1 drop / min. After the addition is complete, react for 1.5 h. Then add 10.0 mL of 20.00% NaOH solution and continue the reaction for 1.5 h.

[0105] (2) Add 125.0 mL of distilled water to dilute, then add 22.00 g of solid NaOH with a mass fraction of 96.00%, and stir at room temperature for 1 h;

[0106] (3) Take 31.1 mL of carbon disulfide with a mass fraction of 99.00% and slowly add it dropwise to the solution in step (2). Stir the reaction at room temperature for 5 h until the bottom oil droplets disappear. Then heat the solution to 60 °C and react for 1.5 h. Then cool the solution to room temperature.

[0107] (4) Take 30.04g of sodium chloroacetate 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. Add 38.1mL of distilled water to prepare a solution with a mass fraction of 30.00%.

[0108] (5) Add the solution obtained in step (3) to the solution obtained in step (4) and mix thoroughly; weigh 10.50g of solid NaOH with a mass fraction of 96.00%, add 29.8mL of distilled water to dissolve and prepare a solution with a mass fraction of 25.00%, transfer it into a dropping funnel and add it in 3 batches, each batch taking 60min. Add the next batch after the pH of the reaction solution drops to about 10. After the addition is complete, continue to react at room temperature for 6h, then raise the temperature to 60℃ and continue to react for 1.5h. Cool to room temperature to obtain 310.2mL of reddish-brown liquid, which is the dimeric polyethylene polyamine double chelate group heavy metal chelate flocculant.

[0109] Infrared spectral analysis was performed on the dimeric polyethylene polyamine dual-chelate heavy metal chelating flocculants obtained in Examples 1 to 12, and the results were basically consistent. The infrared spectral analysis results of the dimeric triethylenetetramine dual-chelate heavy metal chelating flocculant (IDA-DTETA-DTC) obtained in Example 5 are as follows: Figure 2 As shown. Figure 2 The absorption peaks in the infrared spectrum can be assigned as follows: 3277.73 cm⁻¹ -1 These are the stretching vibration peaks of -OH and OH in the water, as well as the stretching vibration peak of -NH; at 2905.58 and 2815.26 cm⁻¹. -1 Asymmetric and symmetric stretching vibration peaks of -CH2- appear at 1356.16 cm⁻¹. -1 Its bending vibration peak appears at 1676.88cm. -1 The strong peak and 1414.46m -1 The slightly weaker peaks are the asymmetric and symmetric stretching vibrations of the carboxylate group, respectively; 1620.46 cm⁻¹ -1 The peak represents the bending vibration of bound water molecules and -OH groups; 1465.27 cm⁻¹ -1 It is an aminodithiocarboxylic acid group (N-CSS) - The stretching vibration peaks of CN in the sample are: 1304.39, 1206.08, 1156.30, and 1117.19 cm⁻¹. -1These are the stretching vibration peaks of CO and CN in the molecule; 1052.87 and 925.60 cm⁻¹. -1 For -CSS - The stretching vibration peaks of C=S and CS in the middle; 811.67 cm. -1 It can be categorized as CSS － The deformation vibration peaks were observed. Elemental analysis of the above samples revealed that the S content was 24.03% and the O content was 13.41%, converted to -CSS... － and —CH2COO － Each chelating flocculant molecule contains 3.98 —CSS － and 3.56 —CH2COO － The above results demonstrate that IDA-DTETA-DTC has been successfully synthesized.

[0110] Example 13

[0111] The IDA-DTETA-DTC(—CSS) prepared in Example 5 — The content of 3.747 mmol / g and —N(CH2COOH)2 was 1.676 mmol / g) and DTETA-DTC (—CSS) prepared under the same conditions using triethylenetetramine (TETA) as a raw material were also tested. — The content of Zn was 5.172 mmol / g) as a chelating agent, and 100 mg / L Zn-containing solutions were prepared. 2+ Cr 3 +、Mn 2+ Ni 2+ Pb 2+ and Cu 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. The reagent was added to a 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 7 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.

[0112] Table 1. Removal effect of the product of this invention on free heavy metal ions

[0113]

[0114] As shown in Table 1, under optimal conditions, the product IDA-DTETA-DTC of this invention has a better effect on free Zn than the control sample DTETA-DTC. 2+ Cr 3 +、Mn2+ Ni 2+ Pb 2+ and Cu 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 it can even remove Pb. 2+ and Cu 2+ Completely remove.

[0115] Example 14

[0116] This embodiment illustrates the settling velocity of flocs generated during the treatment of heavy metals in wastewater using the IDA-DTETA-DTC chelation method of the present invention.

[0117] Using the sample IDA-DTETA-DTC obtained in Example 5 as the chelating agent and DTETA-DTC as the control sample, a Pb-containing solution of 100 mg / L was used. 2+ Simulated wastewater was used as the test object. The experiment was first conducted according to the reagent addition amount and flocculation conditions in Example 13. After stirring was stopped, the test solution was quickly transferred into a 500mL graduated cylinder, and the timing was started to record the drop height of the clear and turbid interface at different times. The results are shown in Table 2.

[0118] Table 2. IDA-DTETA-DTC chelates of Pb in the product of this invention. 2+ The settling velocity of the generated flocs

[0119]

[0120] As can be seen from the results in Table 2, the product IDA-DTETA-DTC of this invention is treated with Pb-containing materials. 2+ The flocs produced by IDA-DTETA-DTC settled significantly faster than those produced by DTETA-DTC, and after 30 minutes of settling, the height of the clear liquid was greater than that of the DTETA-DTC treated liquid. During the experiment, it was observed that the flocs produced by IDA-DTETA-DTC were larger and denser than those produced by DTETA-DTC, and the clear liquid had lower turbidity and was clearer. Therefore, the flocs produced by IDA-DTETA-DTC exhibit superior flocculation and sedimentation performance.

[0121] Example 15

[0122] Thiourea-Cu solutions with a molar ratio of 1:1 and a concentration of 50 mg / L were prepared using deionized water. 2+ Citric acid-Cu 2+ Thiourea-Pb 2+ and citric acid-Pb 2+Simulated heavy metal complexation wastewater samples were prepared using IDA-DTETA-DTC obtained in Example 5, commercially available DTCR, and sodium thiram as chelating agents. The agents were added to a MY3000-6G intelligent color screen coagulation test stirrer (Wuhan Meiyu Instrument Co., Ltd.), and the mixture was rapidly stirred at 220 rpm for 5 min, then stirred at 100 rpm for 10 min. Polyacrylamide (PAM) was added, and stirring continued for 10 min, followed by slow stirring at 60 rpm for 25 min. After standing for 30 min, the clear liquid at 2 cm below the surface was measured using an AA-7000 atomic absorption spectrophotometer (Shimadzu Corporation, Japan), and the turbidity was measured using a WZS-185 high turbidity meter (Shanghai Precision Scientific Instrument Co., Ltd.). The results are shown in Table 3.

[0123] Table 3. Removal effect of the product of this invention on complexed heavy metal ions

[0124]

[0125] Note: Dosage is in the form of CSS in the medicine. － The molar ratio to ions, the concentration unit is mg / L, and the turbidity unit is NTU.

[0126] As can be seen from Table 3, the product of this invention has a good effect on complexing Cu. 2+ Ni 2+ Its removal effect is significantly better than that of commercially available sodium thiram and DTCR.

[0127] Example 16

[0128] Using IDA-DTETA-DTC obtained in Example 5 as a chelating agent, the wastewater from a copper foil manufacturing plant was used as the treatment target. The pollutant indicators of this wastewater are shown in Table 4, containing pyrophosphate and exhibiting a yellow-green turbidity. IDA-DTETA-DTC, the product obtained in Example 5, commercially available heavy metal trapping agents sodium thimerosal and TMT-18 were used as reagents. A 200mL wastewater sample was taken, and the pH was first adjusted to approximately 6 with lime milk. Then, it was placed on a MY3000-6G intelligent color screen coagulation test stirrer (Wuhan Meiyu Instrument Co., Ltd.), and certain amounts of IDA-DTETA-DTC, sodium thimerosal, and TMT-18 were added. The stoichiometric ratio of IDA-DTETA-DTC to sodium thimerosal (IDA-DTETA-DTC or sodium thimerosal - CSS) was determined. －The molar ratios of TMT-18 to heavy metal ions were 1.5:1 and 2.3:1, 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 determine the concentration of heavy metal ions and COD in the treated water. The results are listed in Table 4.

[0129] Table 4. Removal effect of the product of this invention on the comprehensive wastewater of copper foil manufacturing plants.

[0130]

[0131]

[0132] Table 4 shows that the product IDA-DTETA-DTC of this invention has a significantly better treatment effect on this type of comprehensive copper foil production wastewater than commercially available heavy metal scavengers such as sodium formaldehyde sulfoxylate and TMT-18. It can not only remove Cu... 2+ Zn 2+ Co 2+ Fe 3+ All four ions were completely removed, and for Cr 3+ It also has a high removal rate, with all pollutant indicators below the limits specified in the "Electroplating Pollutant Discharge Standard" (GB21900-2008); in particular, IDA-DTETA-DTC also effectively removes Ca from the wastewater. 2+ and Mg 2+ It also has a significant effect on removing COD from treated water, and the treated water has low turbidity.

[0133] Example 17

[0134] The product IDA-DTETA-DTC obtained in Example 5, 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 5.00% were prepared. During the experiment, 250.00 g 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 5.

[0135] Table 5. Effects of the product of this invention and commercially available stabilizers on the treatment of incineration fly ash.

[0136]

[0137]

[0138] As can be seen from Table 5, the amount of the product IDA-DTETA-DTC 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 GB16889-2008, and it can be safely landfilled in landfills.

[0139] The results of Examples 13-17 show that the product of this invention, IDA-DTETA-DTC, has superior removal efficiency for heavy metal ions in free heavy metal wastewater, complexed heavy metal wastewater, and complex actual heavy metal wastewater compared to the comparative samples. The resulting flocs settle faster and effectively immobilize metal ions in incineration fly ash. This is because IDA-DTETA-DTC contains two types of strong chelating groups—CSS. — And —N(CH2COOH)2, as shown in the attached figure Figure 3 The chelation effect is shown. Among them, —CSS — It can form a water-insoluble disulfide-coordinated four-membered ring structure with most heavy metal ions; the —N(CH2COOH)2 group can react with most metal ions, including Ca. 2+ and Mg 2+ Difficult-to-coordinate metal ions can form two stable five-membered rings and bind them to the chelating agent molecule; and through two —CSS rings from different IDA-DTETA-DTC molecules. — The chelating group chelates with the same heavy metal ion, linking different molecules together to form a chelate that gradually grows into larger flocs or aggregates of chelate molecules. This improves the chelation and binding performance of metal ions, enhances the settling performance of the flocs, and increases the stability of the chelate. Through the synergistic effect of two types of strong chelating groups, the chelation and removal efficiency of metal ions in wastewater or the stabilization efficiency of metal ions in fly ash is significantly improved.

[0140] 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. A method for preparing a dimeric polyethylene polyamine-based double-chelating heavy metal chelating flocculant, characterized in that, The structure of the main component of the dimeric polyethylene polyamine double chelating group heavy metal chelating flocculant is shown in formula (Ⅰ): In equation (I), 2≤x≤4, 1≤y≤x, and x and y are both integers; when y<x, there are x-y N-connected H atoms; The preparation method of the aforementioned dimeric polyethylene polyamine dual-chelate heavy metal chelating flocculant includes the following steps: (1) Add polyethylene polyamine to the reactor at a molar ratio of 2:1 to 1.05, and slowly add epichlorohydrin dropwise at room temperature for 1 to 1.5 hours; then add an amount of alkali or alkaline salt solution equal to the amount of epichlorohydrin dropwise and continue the reaction for 1 to 2 hours. (2) Dilute with 5 to 6 times the volume of the reaction mixture in step (1) with distilled water, and then add NaOH at a ratio of (n-1) times the amount of polyethylene polyamine to the amount of NaOH of 1:0.55 to 1.2, where n represents the number of N atoms in the polyethylene polyamine molecule. Stir at room temperature for 0.5 to 1 h. (3) Add carbon disulfide at a ratio of (n-1) times the amount of polyethylene polyamine to the amount of carbon disulfide of 1:0.25-1.05, where n represents the number of N atoms in the polyethylene polyamine molecule. Stir the reaction at room temperature for 3.5-5 hours until the bottom oil droplets disappear. Then heat the reaction to 50-60℃ for 1-1.5 hours and then cool it down to room temperature to obtain solution A. (4) According to the molar ratio of sodium haloacetate to polyethylene polyamine of 2.05 to 2.1:1, weigh sodium haloacetate and add it to the reactor, add distilled water to prepare a solution with a mass fraction of 30% to 35%, and obtain solution B; (5) Add solution A obtained in step (3) to solution B obtained in step (4) and mix thoroughly; then weigh the alkali or alkaline salt according to the molar ratio of alkali or alkaline salt to polyethylene polyamine of 2 to 2.1:1, add distilled water to prepare a solution with a mass fraction of 20% to 30%, add it slowly in three batches, and wait until the pH value of the solution drops to 9 to 11 before adding the next batch. After adding all the batches, continue to react at room temperature for 4 to 6 hours, then raise the temperature to 50 to 60°C and continue to react for 1 to 1.5 hours. Cool to room temperature to obtain the dimeric polyethylene polyamine-based double chelate group heavy metal chelate flocculant.

2. The preparation method according to claim 1, characterized in that, The auxiliary components of the chelating flocculant are xanthic acid and NaOH; the chelating flocculant appears as a reddish-brown or brownish-red viscous liquid.

3. The preparation method according to claim 1, characterized in that, In step (1), the polyethylene polyamine is any one of diethylenetriamine, triethylenetetramine, or tetraethylenepentamine.

4. The preparation method of the dimeric polyethylene polyamine double chelating group heavy metal chelating flocculant according to claim 1, characterized in that, In steps (1) and (5), the alkali or alkaline salt is either NaOH or Na2CO3.

5. The preparation method of the dimeric polyethylene polyamine dual-chelate heavy metal chelating flocculant according to claim 1, characterized in that, In step (3), the haloacetate is either sodium chloroacetate or sodium bromoacetate.

6. The preparation method of the dimeric polyethylene polyamine dual-chelate heavy metal chelating flocculant according to claim 1, characterized in that, In step (1), the epichlorohydrin is added slowly at a rate of 1 to 2 drops / min; in step (5), the alkali or alkaline salt is added slowly over a time of 40 to 60 minutes.

7. The preparation method of the dimeric polyethylene polyamine double chelating group heavy metal chelating flocculant according to claim 1, characterized in that, The polyethylene polyamine, epichlorohydrin, alkali or alkaline salt, carbon disulfide and sodium haloacetate mentioned are all products of industrial grade or higher purity and are not further purified before use.

8. The method for preparing the dimeric polyethylene polyamine dual-chelate heavy metal chelating flocculant according to claim 1, characterized in that, In steps (1) and (4), the reactors are equipped with mechanical stirring, a dripping funnel, and a reflux condenser.

9. The application of the dimeric polyethylene polyamine double chelate heavy metal chelating flocculant obtained by the preparation method according to any one of claims 1 to 8 in the treatment of heavy metals in heavy metal wastewater or incineration fly ash.

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