Heavy metal chelating flocculant with double chelating groups as well as preparation method and application of heavy metal chelating flocculant

Abstract

The invention discloses a heavy metal chelating flocculant with double chelating groups as well as a preparation method and application of the heavy metal chelating flocculant. The preparation method comprises the following steps: firstly, carrying out nucleophilic addition reaction on polyethylene polyamine and carbon disulfide in the presence of alkali, introducing-CSS <-> into a non-terminal position of a polyethylene polyamine molecule, and then carrying out electrophilic substitution reaction on the polyethylene polyamine molecule and haloacetate under a strong alkaline condition to introduce acetic acid groups into two ends of the molecule, so that the molecule has two strong chelating groups, namely-CSS <-> and-N (CH2COO-) 2. The two chelating groups in the molecule can complement each other and have a synergistic effect, so that the chelating binding capacity and the flocculation precipitation performance of various heavy metal ions are remarkably improved, and efficient removal of various heavy metals is realized in one step. The defects that a common chelating agent is single in functional group, low in chelating capacity for some ions, not wide in applicable object range and the like are overcome; the preparation process is simple, mild in reaction condition, easy to operate and control, environment-friendly in technological process and easy to realize industrial production.

Description

Technical Field

[0001] The invention relates to the field of heavy metal wastewater treatment and heavy metal fixation in incineration fly ash, and in particular to a heavy metal chelating flocculant with double chelating groups, and a preparation method and application thereof. Background Art

[0002] Heavy metals are elements with atomic weights between 63.5 and 200.6 and specific gravity greater than 5.0 (Srivastava, NK, Majumder, CB, 2008. Novel biofiltration methods for the treatment of heavy metals from industrial wastewater. J. Hazard. Mater. 151, 1-8.). Among them, Zn, Cu, Mo, Cr, Co, Fe, etc. are essential trace elements for the human body, while most of them are non-essential elements for the human body, which are harmful to the human body. Even if they are essential heavy metal elements for the human body, exceeding a certain amount will also cause harm to the human body. With the rapid development of industrial and agricultural production, the number of industries involving heavy metals is increasing, especially the development of industries such as mineral mining, smelting, electrolysis, and electroplating, and the number of heavy metals discharged into the environment is increasing. Due to the non-biodegradability of heavy metals, trace amounts can produce significant biological toxicity, carcinogenicity, teratogenicity, mutagenicity, and the characteristics of concealment and persistence, it has posed a serious threat to the ecological environment and human health. The development of new and efficient methods for the prevention and control of heavy metal pollution is of great significance to the protection of the ecological environment and the protection of human life.

[0003] Heavy metal wastewater is an important source of heavy metal pollution and a major form of migration and transformation. At present, many methods have been developed for the treatment of heavy metal wastewater, such as chemical precipitation, adsorption, biological method, ion exchange, electrochemical method, membrane filtration and chelate precipitation (flocculation) method. However, these treatment methods all have certain disadvantages. For example, although the ion exchange method has high material regeneration and metal selectivity, and can exchange anions and cations from the solution medium, it cannot be exchanged in concentrated metal solutions. The treatment process is too dependent on the pH value. The ion exchange resin has low strength, is not resistant to high temperatures, and is easily oxidized and fails. It needs to be regenerated frequently and has high operating costs. The membrane filtration method cannot directly filter heavy metal wastewater and needs to be supplemented by micelle enhancement or polymer enhancement to increase the particle size of heavy metal pollutant particles. The membrane device investment is large, and there is an insurmountable membrane pollution problem, which makes it difficult to promote and apply. The electrochemical method is selective for metals, has poor adaptability, and is greatly affected by the solution pH and current density. The treatment cost is high. The cost is relatively high; although the adsorption method has strong adaptability and is particularly suitable for deep treatment of wastewater, the use of natural adsorption materials has low adsorption capacity and difficulty in elution and regeneration, resulting in a large amount of solid hazardous waste that is difficult to dispose of; and although synthetic adsorption materials can overcome some of the defects of natural adsorption materials, they are often prepared at high costs, resulting in high treatment costs, and there are also problems such as elution regeneration and eluent treatment; although the traditional chemical precipitation method is simple to operate, the consumption of chemical precipitants is large, it is difficult to meet the standards for treated water, and a large amount of heavy metal-containing precipitates are produced, becoming solid hazardous waste that is difficult to dispose of; because heavy metals are toxic to microorganisms, the use of biological methods lacks universality, there are still many unresolved problems, and the scope of application is limited. Compared with the above methods, the chelating precipitation (flocculation) method uses chelating agents or chelating flocculants to "bind" heavy metal ions from water and separate them from the water body by precipitation or flocculation. It has high removal efficiency for heavy metal ions, a small amount of precipitates, and is easy to post-process and recycle and utilize heavy metals, and is suitable for large-scale heavy metal wastewater treatment. The key lies in the performance of the chelating agent or chelating flocculant used. The developed chelating agents or chelating flocculants, such as dithiocarbamate (DTC), TMT, sodium thiocarbamate, N,N'-dithiopiperazine carboxylate, etc., all have a single chelating group and weak chelating and binding ability for some heavy metal ions, resulting in poor removal effect for some heavy metal ions. Therefore, when treating complex wastewater containing multiple heavy metal ions, a considerable number of heavy metal ions often fail to meet the standards. － )2] can form two stable The five-membered ring has a strong chelating ability for most metal ions. － A considerable part of the chelates formed by )2 and metal ions are water-soluble and difficult to separate from water; while aminodithiocarboxylic acid (—CSS －The chelate formed by the chelation of heavy metal ions is insoluble in water and can be easily separated from water in the form of precipitation. － and—N(CH2COO － )2 are combined into the same chelating agent molecule to form a heavy metal chelating flocculant with double chelating groups. The strong chelating ability of the two groups can be used to remove most heavy metals (including -CSS － The chelate is not strong) and is precipitated and separated from the water by forming an aminodithiocarboxylic acid chelate that is insoluble in water, thereby greatly improving the removal efficiency of heavy metals in wastewater, achieving efficient removal of multiple heavy metal ions in one step, improving the removal effect of complex heavy metal wastewater, simplifying the treatment process, and reducing treatment costs.

[0004] Summary of the invention

[0005] In view of the technical problem that the above-mentioned complex heavy metal wastewater is difficult to treat, the present invention provides a heavy metal chelating flocculant having a double chelating group, and a preparation method and application thereof.

[0006] The heavy metal chelate flocculant with double chelate groups provided by the present invention has a main component structure as shown in formula (I):

[0007]

[0008] In formula (I), 1≤x≤3, 1≤y≤x, and x and y are both integers; when y<x, x － y N atoms are connected to H atoms; M is Na or K;

[0009] The molecules of the above main ingredients have both - CSS － and—N(CH2COO － )2 Two strong chelating groups can complement each other, have strong chelating binding ability for most heavy metal ions in water, and have good flocculation and sedimentation performance, are safe and non-toxic, and have a wide range of applications, especially for complex wastewater containing multiple heavy metal ions. It can achieve efficient removal of multiple heavy metal ions in one step. The preparation method is simple, the operation and control are easy, the yield is high, and there is basically no three wastes discharged during the process, which is easy to popularize and promote and realize industrialization.

[0010] The preparation method of the heavy metal chelate flocculant having double chelate groups comprises the following steps:

[0011] (1) polyethylene polyamine and distilled water are added to a reactor at a volume ratio of 1:4-5 to prepare a solution with a mass fraction of 15.00%-19.20%, and then a base is added at a ratio of (n-2) times the amount of polyethylene polyamine to the amount of base of 1:0.6-1.2, wherein n represents the number of N atoms in the polyethylene polyamine molecule, and stirred at room temperature for 0.5-1h;

[0012] (2) Add carbon disulfide at a ratio of (n-2) times the amount of polyethylene polyamine to the amount of carbon disulfide of 1:0.33-1.05, wherein n represents the number of nitrogen atoms in the polyethylene polyamine molecule, and stir the mixture at room temperature for 3-4 hours until the bottom oil droplets disappear, then heat the mixture to 50-60°C for 0.5-1 hour, and then cool the mixture to room temperature to obtain solution A;

[0013] (3) According to the molar ratio of halogenated acetate to polyethylene polyamine being 4.0 to 4.2:1, halogenated acetate is weighed and added into a reactor, and distilled water is added to prepare a solution with a mass fraction of 30% to 35%, thereby obtaining solution B;

[0014] (4) adding the solution A obtained in step (2) to the solution B obtained in step (3) and mixing them thoroughly; then weighing a base according to the molar ratio of the base to the polyethylene polyamine of 4 to 4.2:1, adding distilled water to prepare a solution with a mass fraction of 30% to 35%, and slowly adding the base in three batches, each batch being added until the pH value of the solution drops to 9 to 11 before adding the next batch, and continuing to react at room temperature for 4 to 6 hours after the addition is completed, and then heating to 50 to 60° C. and continuing to react for 0.5 to 1 hour, and cooling to room temperature to obtain a heavy metal chelating flocculant having a double chelating group.

[0015] Furthermore, the polyethylene polyamine is any one of diethylene triamine, triethylene tetraamine or tetraethylene pentamine, preferably tetraethylene pentamine.

[0016] Furthermore, in steps (1) and (4), the base is NaOH or KOH, preferably NaOH.

[0017] Furthermore, in step (3), the halogenated acetate is any one of sodium chloroacetate or sodium bromoacetate, preferably sodium chloroacetate.

[0018] Furthermore, in step (4), the slow addition time is 30 to 60 minutes.

[0019] Furthermore, the polyethylene polyamine, alkali, carbon disulfide and halogenated acetate are all products with purity above industrial grade and are used without further purification.

[0020] Furthermore, in steps (1) and (3), the reactor is equipped with a mechanical stirrer, a dropping funnel and a reflux condenser.

[0021] The above-mentioned chelating flocculant is applied to the treatment of various heavy metal wastewaters or heavy metals in incineration fly ash, and has excellent treatment effect.

[0022] The present invention relates to a method for preparing a heavy metal chelating flocculant having a double chelating group. The method firstly allows polyethylene polyamine and carbon disulfide to undergo a nucleophilic addition reaction in the presence of a base, and then reacts the CSS － It is introduced into the non-terminal position of the polyethylene polyamine molecule, and then reacts with the halogenated acetate under strong alkaline conditions to undergo electrophilic substitution reaction to convert the acetic acid group (—CH2COO － ) are introduced into both ends of the molecule to form two groups—N(CH2COO － )2, so that the molecule has both - CSS － and—N(CH2COO － )2 Two strong chelating groups. The present invention can achieve -CSS － and—N(CH2COO － )2 The two chelating groups complement each other and work synergistically to significantly improve the chelating binding ability and flocculation precipitation performance of various heavy metal ions in water, achieving efficient removal of various heavy metals in one step.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The product of the present invention also contains CSS － and—N(CH2COO － )2 Two strong chelating groups, both of which can complement each other, -N(CH2COO － )2 can form stable chelates with most heavy metal ions, which can overcome -CSS － For some ions (such as Ca 2+ Mg 2+ The chelating capacity of CSS － It can also solve -N(CH2COO － )2 can form soluble chelates with some heavy metal ions and cannot be separated from water. The synergistic effect of the two can improve the chelating binding ability and flocculation sedimentation performance of heavy metals in water, and achieve efficient removal of multiple heavy metal ions in water in one step.

[0025] (2) The method of the present invention first introduces CSS into polyethylene polyamine － , making full use of the nucleophilic addition reaction to preferentially occur at the secondary amine position of the polyamine, so that -CSS － It preferentially occupies the secondary amine position, thereby promoting the introduction of -CH2COO in the later stage through steric hindrance.－ It can only enter the terminal position, effectively realizing the effective regulation of the product structure and achieving the successful preparation of the target product.

[0026] (3) The product of the present invention is safe and non-toxic, and can react rapidly with most heavy metal ions in wastewater at room temperature to generate stable water-insoluble chelates, and has a wide range of applications. Since -N(CH2COO-)2 has a strong chelating ability, it can capture heavy metal ions from most heavy metal chelates that are slightly weaker than its chelating ability. Therefore, it is suitable not only for free heavy metal ions, but also for heavy metal ions in complex states; it 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, and can achieve efficient removal of a variety of heavy metal ions in one step.

[0027] (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 and filtered without the need for complicated equipment and processes.

[0028] (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.

[0029] 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

[0030] Figure 1 The figure is a process flow chart of the preparation method of the present invention.

[0031] Figure 2 This is the infrared spectrum of the heavy metal chelating flocculant (the sample of Example 7) which is a product of the present invention and has dual chelating groups.

[0032] Figure 3 This is a diagram showing the chelating flocculation mechanism of the product of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0034] Examples 1 to 11 are methods for preparing the heavy metal chelating flocculant having dual chelating groups, and Examples 12 to 16 are application examples of the product of the present invention.

[0035] Example 1

[0036] (1) 10.9 mL of 99.00% diethylenetriamine and 43.6 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 19.08% was prepared. Then, 4.58 g of 96.00% solid NaOH was added and stirred at room temperature for 0.5 h.

[0037] (2) 6.2 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 3 h until the bottom oil droplets disappeared, and then the temperature was raised to 50° C. for 1 h, and then the temperature was lowered to room temperature;

[0038] (3) 47.54 g of 98.00% sodium chloroacetate was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and 107.8 mL of distilled water was added to prepare a 30.00% solution;

[0039] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 16.67 g of solid NaOH with a mass fraction of 96.00%, adding 36.7 mL of distilled water to dissolve it into a solution with a mass fraction of 30.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 30 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 4 h, then heat it to 60 ° C and continue to react for 0.5 h, cool it to room temperature, and obtain 239.2 mL of orange-red liquid, which is a heavy metal chelating flocculant with dual chelating groups.

[0040] Example 2

[0041] (1) 10.9 mL of 99.00% diethylenetriamine and 54.5 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 15.87% was prepared. Then, 5.42 g of 96.00% solid NaOH was added and stirred at room temperature for 1 h.

[0042] (2) 6.5 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 4 h until the bottom oil droplets disappeared, and then the mixture was heated to 60° C. for 0.5 h, and then cooled to room temperature;

[0043] (3) 49.92 g of sodium chloroacetate 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 89.9 mL of distilled water was added to prepare a solution with a mass fraction of 35.00%;

[0044] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 17.50 g of solid NaOH with a mass fraction of 96.00%, adding 30.5 mL of distilled water to dissolve it into a solution with a mass fraction of 35.00%, transferring it to a dropping funnel and adding it in 3 batches, each adding time is 30 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 4 h, then heat it to 60 ° C and continue to react for 0.5 h, cool it to room temperature, and obtain 223.7 mL of reddish brown liquid, which is a heavy metal chelating flocculant with dual chelating groups.

[0045] Example 3

[0046] (1) 16.2 mL of 95.00% triethylenetetramine and 64.8 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 18.73% was prepared. Then, 5.00 g of 96.00% solid NaOH was added and stirred at room temperature for 1 h.

[0047] (2) 6.5 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 3.5 h until the bottom oil droplets disappeared, and then the temperature was raised to 55° C. for 0.75 h, and then the temperature was lowered to room temperature;

[0048] (3) 48.14 g of 98.00% sodium chloroacetate was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and 110.1 mL of distilled water was added to prepare a 30.00% solution;

[0049] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 17.08 g of solid NaOH with a mass fraction of 96.00%, adding 36.3 mL of distilled water to dissolve it into a solution with a mass fraction of 32.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 40 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 4.5 h, then heat it to 55 ° C and continue to react for 0.75 h, cool it to room temperature, and obtain 252.4 mL of orange-red liquid, that is, a heavy metal chelating flocculant with dual chelating groups.

[0050] Example 4

[0051] (1) 16.2 mL of 95.00% triethylenetetramine and 64.8 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 17.02% was prepared. Then, 9.17 g of 96.00% solid NaOH was added and stirred at room temperature for 0.75 h.

[0052] (2) 13.6 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 4 h until the bottom oil droplets disappeared, and then the temperature was raised to 60° C. for 1 h, and then the temperature was lowered to room temperature;

[0053] (3) 49.92 g of sodium chloroacetate 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 90.9 mL of distilled water was added to prepare a solution with a mass fraction of 35.00%;

[0054] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 17.50 g of solid NaOH with a mass fraction of 96.00%, adding 38.5 mL of distilled water to dissolve it into a solution with a mass fraction of 30.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 60 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 6 h, then heat it to 50 ° C and continue to react for 1 h, cool it to room temperature, and obtain 249.4 mL of orange-red liquid, which is a heavy metal chelating flocculant with dual chelating groups.

[0055] Example 5

[0056] (1) 16.2 mL of 95.00% triethylenetetramine and 81.0 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 15.60% was prepared. Then, 7.50 g of 96.00% solid NaOH was added and stirred at room temperature for 1 h.

[0057] (2) 9.7 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 3 h until the bottom oil droplets disappeared, and then the temperature was raised to 55° C. for 1 h, and then the temperature was lowered to room temperature;

[0058] (3) 48.73 g of 98.00% sodium chloroacetate was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and 110.5 mL of distilled water was added to prepare a 30.00% solution;

[0059] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 16.67 g of solid NaOH with a mass fraction of 96.00%, adding 33.3 mL of distilled water to dissolve it into a solution with a mass fraction of 32.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 50 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 5.5 h, then heat it to 60° C. and continue to react for 0.75 h, cool it to room temperature, and obtain 264.8 mL of a reddish-brown liquid, which is a heavy metal chelating flocculant with a double chelating group.

[0060] Example 6

[0061] (1) 20.0 mL of 95.00% tetraethylenepentamine and 80.0 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 18.97% was prepared. Then, 5.42 g of 96.00% solid NaOH was added and stirred at room temperature for 1 h.

[0062] (2) 6.5 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 3 h until the bottom oil droplets disappeared, and then the temperature was raised to 50° C. for 1 h, and then the temperature was lowered to room temperature;

[0063] (3) 47.54 g of 98.00% sodium chloroacetate was added to a 500 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, and 107.8 mL of distilled water was added to prepare a 30.00% solution;

[0064] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 17.08 g of solid NaOH with a mass fraction of 96.00%, adding 37.6 mL of distilled water to dissolve it into a solution with a mass fraction of 30.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 40 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 6 h, then heat it to 50 ° C and continue to react for 1 h, cool it to room temperature, and obtain 263.8 mL of orange-red liquid, which is a heavy metal chelating flocculant with dual chelating groups.

[0065] Example 7

[0066] (1) 20.0 mL of 95.00% tetraethylenepentamine and 100.0 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 15.81% was prepared. Then, 10.00 g of 96.00% solid NaOH was added and stirred at room temperature for 1 h.

[0067] (2) 13.0 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 4 h until the bottom oil droplets disappeared, and then the temperature was raised to 55° C. for 1 h, and then the temperature was lowered to room temperature;

[0068] (3) 48.73 g of sodium chloroacetate 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 100.5 mL of distilled water was added to prepare a solution with a mass fraction of 32.00%;

[0069] (4) Add the solution obtained in step (2) to the solution obtained in step (3) and mix thoroughly; weigh 17.50 g of solid NaOH with a mass fraction of 96.00%, add 30.5 mL of distilled water to dissolve it into a solution with a mass fraction of 35.00%, transfer it to a dropping funnel and add it in 3 batches, each adding time is 60 min, and the next batch is added when the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 6 h, then heat it to 60 ° C and continue to react for 1 h, cool it to room temperature, and obtain 276.9 mL of reddish brown liquid, that is, a heavy metal chelating flocculant with dual chelating groups, recorded as IDA-TEPA-DTC.

[0070] Tetraethylenepentamine (TEPA) was used as a raw material, and the tetraethylenepentamine grafted dithiocarboxylic acid chelating agent was prepared according to the same proportions and preparation conditions as steps (1) to (2) of this embodiment, and was recorded as TEPA-DTC.

[0071] Example 8

[0072] (1) Take 20.0 mL of 95.00% tetraethylene pentamine and 90.0 mL of distilled water and add them to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stir and dissolve to prepare a solution with a mass fraction of 17.24%, then add 13.75 g of 96.00% solid NaOH and stir at room temperature for 1 h;

[0073] (2) 19.5 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 4 h until the bottom oil droplets disappeared, and then the temperature was raised to 60° C. for 1 h, and then the temperature was lowered to room temperature;

[0074] (3) 49.92 g of sodium chloroacetate 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 89.0 mL of distilled water was added to prepare a solution with a mass fraction of 35.00%;

[0075] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 17.50 g of solid NaOH with a mass fraction of 96.00%, adding 35.0 mL of distilled water to dissolve it into a solution with a mass fraction of 32.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 60 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 6 h, then heat it to 60 ° C and continue to react for 1 h, cool it to room temperature, and obtain 275.9 mL of reddish brown liquid, which is a heavy metal chelating flocculant with dual chelating groups.

[0076] Example 9

[0077] (1) 20.0 mL of 95.00% tetraethylenepentamine and 100.0 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 15.81% was prepared. Then, 14.52 g of 85.00% solid KOH was added and stirred at room temperature for 0.75 h.

[0078] (2) 13.0 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 4 h until the bottom oil droplets disappeared, and then the temperature was raised to 60° C. for 1 h, and then the temperature was lowered to room temperature;

[0079] (3) 67.33 g of sodium bromoacetate 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 152.6 mL of distilled water was added to prepare a solution with a mass fraction of 30.00%;

[0080] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 27.06 g of solid KOH with a mass fraction of 85.00%, adding 49.6 mL of distilled water to dissolve it into a solution with a mass fraction of 30.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 60 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 5.5 h, then heat it to 55 ° C and continue to react for 1 h, cool it to room temperature, and obtain 366.6 mL of orange-red liquid, that is, a heavy metal chelating flocculant with dual chelating groups.

[0081] Example 10

[0082] (1) 20.0 mL of 95.00% tetraethylenepentamine and 100.0 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 15.81% was prepared. Then, 10.89 g of 85.00% solid KOH was added and stirred at room temperature for 1 h.

[0083] (2) 9.7 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 3.5 h until the bottom oil droplets disappeared, and then the temperature was raised to 60° C. for 0.75 h, and then the temperature was lowered to room temperature;

[0084] (3) 66.51 g of sodium bromoacetate 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 119.7 mL of distilled water was added to prepare a solution with a mass fraction of 35.00%;

[0085] (4) adding the solution obtained in step (2) to the solution obtained in step (3) and mixing thoroughly; weighing 27.72 g of solid KOH with a mass fraction of 85.00%, adding 39.6 mL of distilled water to dissolve it into a solution with a mass fraction of 35.00%, transferring it to a dropping funnel and adding it in three batches, each adding time is 50 min, and adding the next batch after the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 6 h, then heat it to 50 ° C and continue to react for 1 h, cool it to room temperature, and obtain 319.7 mL of orange-red liquid, which is a heavy metal chelating flocculant with dual chelating groups.

[0086] Embodiment 11

[0087] (1) 20.0 mL of 95.00% tetraethylene pentamine and 90 mL of distilled water were added to a 250 mL three-necked flask equipped with a mechanical stirrer, a dropping funnel and a reflux condenser, stirred to dissolve, and a solution with a mass fraction of 17.24% was prepared. Then, 10.00 g of 96.00% solid NaOH was added and stirred at room temperature for 1 h.

[0088] (2) 13.6 mL of 99.00% carbon disulfide was slowly added to the solution of step (1), and the mixture was stirred at room temperature for 3 h until the bottom oil droplets disappeared, and then the temperature was raised to 60° C. for 1 h, and then the temperature was lowered to room temperature;

[0089] (3) 67.33 g of sodium bromoacetate 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 138.9 mL of distilled water was added to prepare a solution with a mass fraction of 32.00%;

[0090] (4) Add the solution obtained in step (2) to the solution obtained in step (3) and mix thoroughly; weigh 16.67 g of solid NaOH with a mass fraction of 96.00%, add 36.7 mL of distilled water to dissolve it into a solution with a mass fraction of 30.00%, transfer it to a dropping funnel and add it in 3 batches, each adding time is 60 min, and the next batch is added when the pH value of the reaction liquid drops to about 10. After the addition is completed, continue to react at room temperature for 6 h, then heat it to 60 ° C and continue to react for 1 h, cool it to room temperature, and obtain 325 mL of reddish brown liquid, which is a heavy metal chelating flocculant with dual chelating groups.

[0091] The infrared spectroscopy analysis of the chelating flocculants obtained in Examples 1 to 11 showed basically the same results. The infrared spectroscopy analysis results of the chelating flocculants obtained in Example 7 are as follows: Figure 2 shown. Figure 2 The absorption peaks in the infrared spectrum can be attributed as follows: 3263.68cm -1 The stretching vibration peaks of -OH and -NH of water in the sample; at 2927.29 and 2808.67 cm -1 The asymmetric and symmetric stretching vibration peaks of -CH2- appear at 1346.92 cm -1 Its bending vibration peak appears at 1670.24cm -1 The strong peak and 1406.94cm -1 The slightly weaker peaks are the asymmetric stretching and symmetric stretching vibration peaks of carboxylate groups; 1610.11cm -1 is the absorption peak of bound water molecules; 1474.41cm -1 N-CSS - ) CN stretching vibration absorption peaks; 1291.21, 1201.85 and 1127.21 cm -1 The stretching vibration peaks of CO and CN in the molecule; 1016.73 and 964.92 cm -1 for-css - The stretching vibration peak of C=S and CS in the middle; 859.97cm -1 It can be attributed to the deformation vibration peak of -CSS-. The elemental analysis of the above samples showed that the S content was 18.02% and the O content was 17.99%, which was converted into -CSS- and -CH2COO-. On average, each chelating flocculant molecule was connected with 1.98 -CSS- and 3.97 -CH2COO-. The above results show that the heavy metal chelating flocculant with dual chelating groups has been successfully synthesized.

[0092] Example 12

[0093] This example shows the treatment effect of the sample in Example 7 on heavy metal wastewater.

[0094] IDA-TEPA-DTC (—CSS — The content of -N(CH2COOH)2 is 2.810mmol / g, and -N(CH2COOH)2 is 2.811mmol / g) and TEPA-DTC (-CSS — The content of 5.166mmol / g) was used as a chelating agent, and 100mg / L Cr 3+ , Pb 2+ 、Cd 2+ 、Ni 2+ , Mn 2+ , Cu 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 4.5-7, add reagents on the MY3000-6G intelligent color screen coagulation test stirring instrument (Wuhan Meiyu Instrument Co., Ltd.), stir quickly at 200-250r / min for 5min, stir at 100-110r / min for 10min, and then stir slowly at 50-60r / min for 7min, let it stand for 20min, take the clear liquid 2cm below the liquid surface and measure it on the AA-7000 atomic absorption spectrophotometer (Japan, Shimadzu Corporation), and the treatment effect is shown in Table 1.

[0095] Table 1 Removal effect of the product of the present invention on free heavy metal ions

[0096]

[0097] It can be seen from Table 1 that under the optimal conditions, the product IDA-TEPA-DTC of the present invention has a higher free Cr than the comparative sample TEPA-DTC. 3+ , Pb 2+ 、Cd 2+ 、Ni 2+ , Mn 2+ , Cu 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 even Pb 2+ 、Cd 2+ and Cu 2+ Completely remove.

[0098] Embodiment 13

[0099] This example shows the sedimentation rate of flocs produced by heavy metal chelation in wastewater treated with the product IDA-TEPA-DTC of the present invention.

[0100] The sample IDA-TEPA-DTC (CSS — The content of -N(CH2COOH)2 is 2.810mmol / g, -N(CH2COOH)2 is 2.811mmol / g) is a chelating agent, TEPA-DTC (-CSS — The content of Cd was 5.166mmol / g) as the control sample, and 100mg / L of 2+ The simulated wastewater was used as the test object. The test was first conducted according to the dosage of the reagent and the flocculation conditions of Example 12. After the stirring was stopped, the test solution was quickly transferred into a 500 mL graduated cylinder, the timing was started, and the descending height of the clear and turbid interface at different times was recorded. The results are shown in Table 2.

[0101] Table 2 IDA-TEPA-DTC chelated Cd 2+ The sedimentation rate of the generated flocs

[0102]

[0103] From the results in Table 2, it can be seen that the product IDA-TEPA-DTC of the present invention can treat Cd-containing 2+ The flocs generated by wastewater settle significantly faster than those generated by TEPA-DTC, and the height of the clear liquid after standing for 30 minutes is greater than that of the clear liquid treated with TEPA-DTC. During the experiment, it can be observed that the flocs generated by IDA-TEPA-DTC are coarser and denser than those generated by TEPA-DTC, and the clear liquid has lower turbidity and is clearer. Therefore, the flocs generated by IDA-TEPA-DTC have better flocculation and sedimentation performance.

[0104] Embodiment 14

[0105] Thiourea-Cd was prepared with deionized water at a molar ratio of 1:1 and a concentration of 50 mg / L. 2+ , citric acid-Cd 2+ , thiourea-Ni 2+ and citric acid-Ni 2+To simulate the complexed heavy metal wastewater sample, the sample obtained in Example 7, commercially available DTCR and sodium thiamethoxam were used as chelating agents, respectively. On the MY3000-6G intelligent color screen coagulation test stirring instrument (Wuhan Meiyu Instrument Co., Ltd.), the reagent was added, and the mixture was stirred quickly at 200 r / min for 5 min, stirred at 100 r / min for 20 min, polyacrylamide (PAM) was added as a coagulant, and then slowly stirred at 60 r / min for 25 min, and allowed to stand for 30 min. The clear liquid 2 cm below the liquid surface was measured on an AA-7000 atomic absorption spectrophotometer (Shimadzu Corporation, Japan), and the turbidity was measured at WZS － The results were shown in Table 3.

[0106] Table 3 Removal effect of the product of the present invention on complexed heavy metal ions

[0107]

[0108]

[0109] Note: The dosage is in the medicine － CSS － The molar ratio of the ion, the concentration unit is mg / L, and the turbidity unit is NTU.

[0110] As can be seen from Table 3, the product of the present invention has a good effect on the complexation of Cu 2+ 、Ni 2+ The removal effect is significantly better than that of commercially available DTCR and sodium thiram.

[0111] Embodiment 15

[0112] The IDA-TEPA-DTC obtained in Example 7 was used as a chelating agent to treat the comprehensive wastewater of a certain electroplating plant. The pollutant indicators of the comprehensive wastewater were: pH value of 1.29, turbidity of 320.5 NTU, Cu 2+ The concentration is 105.12 mg / L, Ni 2+ The concentration was 25.59 mg / L, the total Cr concentration was 29.27 mg / L, and the Zn 2+ The concentration is 434.6 mg / L, Co 2+ The concentration is 10.59 mg / L, Fe 3+ The concentration is 160.54 mg / L, it contains phosphorus compounds and is dark gray and turbid.

[0113] The product IDA-TEPA-DTC obtained in Example 7, commercially available heavy metal scavengers sodium fumei and TMT-18 were used as reagents respectively. 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 IDA-TEPA-DTC, sodium fumei and TMT-18 chelating agents respectively. The amount of chelating agent added is 1.2 times the stoichiometric ratio, wherein the stoichiometric ratio of IDA-TEPA-DTC and sodium fumei (i.e., the ratio of IDA-TEPA-DTC or sodium fumei in － CSS － The molar ratio of TMT-18 to heavy metal ions was 1.55:1 and 2.25:1 respectively, and the stoichiometric ratio of TMT-18 was 2:3. The chelating agent was added under stirring at 200 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. 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 4.

[0114] Table 4 Removal effect of the product of the present invention on comprehensive wastewater from electroplating plants

[0115]

[0116]

[0117] The results in Table 4 show that the product IDA-TEPA-DTC of the present invention has obvious treatment effect on this comprehensive electroplating wastewater due to the common heavy metal scavengers sodium thimerosal 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).

[0118] Example 16

[0119] The product IDA-TEPA-DTC obtained in Example 7, commercially available heavy metal scavengers sodium thiamethoxam and TMT － 18 is a heavy metal stabilizer for incineration fly ash, all of which are 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 5.

[0120] Table 5 Effects of the products of the present invention and commercially available stabilizers on incineration fly ash treatment

[0121]

[0122] As can be seen from Table 5, the dosage of the product IDA-TEPA-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.

[0123] The results of Examples 12 to 16 show that the product IDA-TEPA-DTC of the present invention has better removal efficiency for free heavy metal wastewater, complex heavy metal wastewater and heavy metal ions in complex electroplating wastewater than the comparative samples, and the generated flocs settle faster and can effectively fix metal ions in incineration fly ash. The reason is that IDA-TEPA-DTC contains two types of strong chelating groups - CSS — and -N(CH2COOH)2, occurs as Figure 3 Chelation shown: (1)—CSS — It can react with most heavy metal ions to form a water-insoluble disulfide coordinated four-membered ring structure, while the -N(CH2COOH)2 group can react with most metal ions, including Ca 2+ and Mg 2+ (2) through two CSS from different IDA-TEPA-DTC molecules — The groups chelate with the same heavy metal ion to connect the chelates formed by different molecules and gradually grow to form larger flocs or chelate molecular aggregates, thereby improving the performance of chelating and binding metal ions, the sedimentation performance of flocs formed, and the stability of chelates. The two types of strong chelating groups work synergistically to significantly improve the chelation removal efficiency of metal ions in wastewater or the stabilization efficiency of metal ions in fly ash.

[0124] 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. A heavy metal chelating flocculant having a double chelating group, characterized in that: The structure of its main component is shown in formula (I): In formula (I), 1≤x≤3, 1≤y≤x, and x and y are both integers; when y<x, x-y N atoms are connected to H atoms; and M is Na or K.

2. The heavy metal chelate flocculant having a double chelate group according to claim 1, characterized in that: The chelating flocculant further comprises auxiliary components of xanthogenic acid and alkali, and the appearance of the chelating flocculant is orange-red or reddish-brown viscous liquid.

3. The method for preparing the heavy metal chelate flocculant having double chelate groups according to claim 1 or 2, characterized in that: The following steps are involved: (1) polyethylene polyamine and distilled water are added to a reactor at a volume ratio of 1:4-5 to prepare a solution with a mass fraction of 15.00%-19.20%, and then a base is added at a ratio of (n-2) times the amount of polyethylene polyamine to the amount of base of 1:0.6-1.2, wherein n represents the number of N atoms in the polyethylene polyamine molecule, and stirred at room temperature for 0.5-1h; (2) Add carbon disulfide at a ratio of (n-2) times the amount of polyethylene polyamine to the amount of carbon disulfide of 1:0.33-1.05, wherein n represents the number of nitrogen atoms in the polyethylene polyamine molecule, and stir the mixture at room temperature for 3-4 hours until the bottom oil droplets disappear, then heat the mixture to 50-60°C for 0.5-1 hour, and then cool the mixture to room temperature to obtain solution A; (3) According to the molar ratio of halogenated acetate to polyethylene polyamine being 4.0 to 4.2:1, halogenated acetate is weighed and added into a reactor, and distilled water is added to prepare a solution with a mass fraction of 30% to 35%, thereby obtaining solution B; (4) adding the solution A obtained in step (2) to the solution B obtained in step (3) and mixing them thoroughly; then weighing a base according to the molar ratio of the base to the polyethylene polyamine of 4 to 4.2:1, adding distilled water to prepare a solution with a mass fraction of 30% to 35%, and slowly adding the base in three batches, each batch being added until the pH value of the solution drops to 9 to 11 before adding the next batch, and continuing to react at room temperature for 4 to 6 hours after the addition is completed, and then heating to 50 to 60° C. and continuing to react for 0.5 to 1 hour, and cooling to room temperature to obtain a heavy metal chelating flocculant having a double chelating group.

4. The method for preparing a heavy metal chelating flocculant having a double chelating group according to claim 3, characterized in that: In step (1), the polyethylene polyamine is any one of diethylenetriamine, triethylenetetramine or tetraethylenepentamine.

5. The method for preparing a heavy metal chelating flocculant having a double chelating group according to claim 3, characterized in that: In steps (1) and (4), the base is NaOH or KOH.

6. The method for preparing a heavy metal chelating flocculant having a double chelating group according to claim 3, characterized in that: In step (3), the halogenated acetate is any one of sodium chloroacetate or sodium bromoacetate.

7. The method for preparing a heavy metal chelate flocculant having a double chelate group according to claim 3, characterized in that: In step (4), the slow addition time is 30 to 60 minutes.

8. The method for preparing a heavy metal chelating flocculant having a double chelating group according to claim 3, characterized in that: The polyethylene polyamine, alkali, carbon disulfide and halogenated acetate are all products with purity above industrial grade and are used without further purification.

9. The method for preparing a heavy metal chelating flocculant having a double chelating group according to claim 3, characterized in that: In steps (1) and (3), the reactor is equipped with a mechanical stirrer, a dropping funnel and a reflux condenser.

10. Use of the heavy metal chelating flocculant having dual chelating groups 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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