阅读说明：本技术 一种重金属捕集剂及其制备方法和应用 (Heavy metal trapping agent and preparation method and application thereof ) 是由 白鑫 黄晶晶 乔爱滋 李宝佳 付东康 吴绍祖 于 2021-08-24 设计创作，主要内容包括：本发明属于污水处理技术领域,提供了本发明提供了一种重金属捕集剂及其制备方法和应用。本发明提供的重金属捕集剂具有式I所示结构,式I中,n＝1、2、3；R-(1)为直链烷烃或支链烷烃；所述直链烷烃为甲基、乙基、丙基、丁基、戊基或辛基；所述支链烷烃为异丁基、异戊基或或异辛基。对于本发明提供的重金属捕集剂而言,从分子构型上来讲,R-(1)的分子链越长,数目越多,电荷分布越均匀,化学稳定性越好；具体为,伯胺上的H活泼性高于仲胺,伯胺也更易和酸性物质发生反应,叔胺上的H都被取代,在酸性物质(溶液)中可以较稳定的存在。因此,式I所示结构的重金属捕收剂具有耐酸特性。(The invention belongs to the technical field of sewage treatment, and provides a heavy metal trapping agent, and a preparation method and application thereof. The heavy metal trapping agent has a structure shown in a formula I, wherein n is 1, 2 and 3; r 1 Is straight-chain alkane or branched-chain alkane; the straight-chain alkane is methyl, ethyl, propyl, butyl, pentyl or octyl; the branched alkane is isobutyl, isoamyl or isooctyl. For the heavy metal trapping agent provided by the invention, in terms of molecular configuration, R 1 The longer the molecular chain, the more the number, the more uniform the charge distribution, the better the chemical stability; specifically, the reactivity of H on primary amine is higher than that of secondary amine, the primary amine is more likely to react with acidic substances, and H on tertiary amine is replaced and can exist in acidic substances (solution) more stably. Thus, formula IThe heavy metal collecting agent with the structure has acid resistance.)

1. A heavy metal trapping agent, characterized by having a structure represented by formula I:

in formula I, n is 1, 2 and 3;

R₁is straight-chain alkane or branched-chain alkane;

the straight-chain alkane is methyl, ethyl, propyl, butyl, pentyl or octyl;

the branched alkane is isobutyl, isoamyl or isooctyl.

2. The method for preparing the heavy metal trapping agent according to claim 1, comprising the steps of:

mixing carbon disulfide and dialkyl amine, and carrying out addition reaction to obtain mercapto dithiocarbamic acid; the dialkyl amine is dimethyl amine, diethyl amine, di-n-propyl amine, di-n-butyl amine, di-n-pentyl amine, di-n-octyl amine, diisobutyl amine, diisopentyl amine, or diisooctyl amine;

mixing the sulfenyl dithiocarbamic acid and dichloroalkane to carry out substitution reaction to obtain the heavy metal trapping agent; the dichloralkane is dichloromethane, dichloroethane or dichloropropane.

3. The production method according to claim 2, wherein the carbon disulfide and the dialkylamine are mixed by adding the carbon disulfide dropwise to the dialkylamine with stirring; the dropping speed is 5-25 mL/min, and the dropping temperature is-5-15 ℃.

4. The process according to claim 2, wherein the molar ratio of dialkylamine, carbon disulfide and dichloralkane is 1: (1.5-4): (1-1.5).

5. The preparation method according to claim 2 or 4, wherein the temperature of the addition reaction is 50-80 ℃ and the time is 2-6 h.

6. The preparation method according to claim 2 or 4, wherein the temperature of the substitution reaction is 40-60 ℃ and the time is 1-5 h.

7. Use of the heavy metal collector of claim 1 in the field of heavy metal removal.

8. The use according to claim 7, wherein R in formula I₁When the alkane is straight-chain alkane, the method comprises the following steps:

and sequentially adding the heavy metal trapping agent and anionic polyacrylamide into the acidic wastewater for flocculation.

9. The use according to claim 7, wherein R in formula I₁When the branched alkane is used, the method comprises the following steps:

and sequentially adding a protective agent, the heavy metal trapping agent and anionic polyacrylamide into the acidic wastewater for flocculation.

10. Use according to claim 9,

the protective agent is potassium persulfate; r in the heavy metal trapping agent₁Selectively removing Hg in the acidic wastewater for isobutyl, n-2²⁺；

The protective agent is potassium tetrathionate; r in the heavy metal trapping agent₁Is isooctyl, n is 2, selectively removing Cd in the acidic wastewater²⁺；

The protective agent is potassium thiosulfate; r in the heavy metal trapping agent₁Is isoamyl, n is 3, selectively removes Pb in the acid wastewater²⁺；

The protective agent is sodium persulfate; r in the heavy metal trapping agent₁Is isoamyl, n is 2, and Mn in the acidic wastewater is selectively removed²⁺；

The protective agent is sodium thiosulfate; r in the heavy metal trapping agent₁Is isobutyl, n is 3, selectively removes Cu in the acid wastewater²⁺；

The protective agent is magnesium thiosulfate; r in the heavy metal trapping agent₁Is isooctyl, n is 3, selectively removes As in the acid wastewater³⁺。

Technical Field

The invention relates to the technical field of sewage treatment, in particular to a heavy metal trapping agent and a preparation method and application thereof.

Background

Heavy metal ions (metalloid ions) are not negligible polluting the ecosystems due to their biotoxicity, accumulation of non-metabolizable, non-degradable, etc. The heavy metal pollution treatment method in the water body comprises the following steps: chemical, physicochemical, and biochemical methods. The chemical treatment is a method for removing heavy metal ions by chemical reaction, and includes ferrite coprecipitation, neutralization precipitation, chemical reduction, sulfide precipitation, electrochemical reduction, heavy metal collector, and the like. The classical heavy metal wastewater treatment method usually adopts a chemical precipitation method, for example, acidic wastewater containing heavy metal ions of certain delafossite is treated by a limestone-sodium sulfide-lime milk treatment system to recover metal sulfides, but the chemical precipitation process has poor selectivity to heavy metals and low metal sulfide taste, and in order to avoid hydrogen sulfide generation, the chemical precipitation method is carried out under an alkaline condition, a large amount of solid hazardous waste is generated by lime neutralization of acidic wastewater, the treatment process is complicated, and the wastewater treatment cost is high.

The heavy metal collector method can utilize the heavy metal collector to be capable of reacting with Cu in the wastewater²⁺、Cd²⁺、Hg²⁺、Pb²⁺、Mn²⁺、Ni²⁺、Zn²⁺、Cr³⁺And various heavy metal ions are chelated, so that insoluble flocculent precipitate with low water content and easy filtering removal is quickly generated, and the advantage of removing the heavy metal ions in the wastewater is further realized, thereby being widely concerned. Compared with the traditional chemical precipitation method, the method is heavyThe advantages of the metal trapping agent are that: the treatment method is simple (can be directly put into the original chemical precipitation device), the cost is low, and the treatment method is not influenced by the coexistence of other heavy metal salts and complex salts (such as EDTA and NH) in the wastewater₃Citric acid, etc.), less solid waste, no secondary pollution, etc. In the prior art, the commonly used heavy metal trapping agents mainly comprise xanthate heavy metal trapping agents, thiol heavy metal trapping agents and dimercapto heavy metal trapping agents. However, the heavy metal trapping agent is easily decomposed in a strong acid environment to generate H₂S, the toxic gas further causes the heavy metal trapping agent to lose the chelation, and heavy metal ions have secondary dissolution risk.

Disclosure of Invention

In view of the above, the present invention aims to provide a heavy metal trapping agent, a preparation method and an application thereof. The heavy metal trapping agent provided by the invention cannot be decomposed under an acidic condition.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a heavy metal trapping agent, which has a structure shown in a formula I:

in formula I, n is 1, 2 and 3;

R₁is straight-chain alkane or branched-chain alkane;

the straight-chain alkane is methyl, ethyl, propyl, butyl, pentyl or octyl;

the branched alkane is isobutyl, isoamyl or isooctyl.

The invention also provides a preparation method of the heavy metal trapping agent in the technical scheme, which comprises the following steps:

mixing carbon disulfide and dialkyl amine, and carrying out addition reaction to obtain mercapto dithiocarbamic acid; the dialkyl amine is dimethyl amine, diethyl amine, di-n-propyl amine, di-n-butyl amine, di-n-pentyl amine, di-n-octyl amine, diisobutyl amine, diisopentyl amine, or diisooctyl amine;

mixing the sulfenyl dithiocarbamic acid and dichloroalkane to carry out substitution reaction to obtain the heavy metal trapping agent; the dichloralkane is dichloromethane, dichloroethane or dichloropropane.

Preferably, the carbon disulfide and the dialkyl amine are mixed in a manner that the carbon disulfide is dropwise added into the dialkyl amine and stirred; the dropping speed is 5-25 mL/min, and the dropping temperature is-5-15 ℃.

Preferably, the molar ratio of dialkylamine, carbon disulfide and dichloroalkane is 1: (1.5-4): (1-1.5).

Preferably, the temperature of the addition reaction is 50-80 ℃ and the time is 2-6 h.

Preferably, the temperature of the substitution reaction is 40-60 ℃ and the time is 1-5 h.

The invention also provides application of the heavy metal trapping agent in the technical scheme in the field of heavy metal removal.

Preferably, R in formula I₁When the alkane is straight-chain alkane, the method comprises the following steps:

and sequentially adding the heavy metal trapping agent and anionic polyacrylamide into the acidic wastewater for flocculation.

Preferably, R in formula I₁When the branched alkane is used, the method comprises the following steps:

and sequentially adding a protective agent, the heavy metal trapping agent and anionic polyacrylamide into the acidic wastewater for flocculation.

Preferably, the first and second electrodes are formed of a metal,

the protective agent is potassium persulfate; r in the heavy metal trapping agent₁Selectively removing Hg in the acidic wastewater for isobutyl, n-2²⁺；

The protective agent is potassium tetrathionate; r in the heavy metal trapping agent₁Is isooctyl, n is 2, selectively removing Cd in the acidic wastewater²⁺；

The protective agent is potassium thiosulfate; r in the heavy metal trapping agent₁Is isoamyl, n is 3, selectively removes Pb in the acid wastewater²⁺；

The protective agent is sodium persulfate; r in the heavy metal trapping agent₁Is isoamyl, n is 2, and Mn in the acidic wastewater is selectively removed²⁺；

The protective agent is sodium thiosulfate; r in the heavy metal trapping agent₁Is isobutyl, n is 3, selectively removes Cu in the acid wastewater²⁺；

The protective agent is magnesium thiosulfate; r in the heavy metal trapping agent₁Is isooctyl, n is 3, selectively removes As in the acid wastewater³⁺。

The invention provides a heavy metal trapping agent, which has a structure shown in a formula I:

in the present invention, in formula I, n is 1, 2, 3;

R₁is straight-chain alkane or branched-chain alkane; the straight-chain alkane is methyl, ethyl, propyl, butyl, pentyl or octyl; the branched alkane is isobutyl, isoamyl or isooctyl.

For the heavy metal trapping agent provided by the invention, in terms of molecular configuration, R₁The longer the molecular chain, the more the number, the more uniform the charge distribution, the better the chemical stability; specifically, the reactivity of H on primary amine is higher than that of secondary amine, the primary amine is more likely to react with acidic substances, and H on tertiary amine is replaced and can exist in acidic substances (solution) more stably. Therefore, the heavy metal collector with the structure shown in the formula I has acid resistance. If under extreme conditions of strong acidity (such as 50% by mass of aqueous sulfuric acid), it is necessary to select the long-chain substituent (R)₁) The heavy metal trapping agent of (1); under the water quality condition with weak acidity (such as 5 percent of sulfuric acid aqueous solution) the short-chain substituent (R) can be selected₁) The heavy metal trapping agent of (1). The introduction of a protective group-haloalkyl on the dithiocarbamic acid group passivates the active S molecule and protects heavy metal chelate under acidic conditionsAnd (4) the compound acts to inhibit the decomposition of the compound to generate hydrogen sulfide.

The invention also provides application of the heavy metal trapping agent in the technical scheme in the field of heavy metal removal. For wastewater containing various heavy metal ions, if a certain specific metal ion does not need to be recovered, a straight-chain heavy metal collecting agent can be directly added, and a protective agent does not need to be added to chelate all heavy metal ions. If one metal ion is preferentially recovered from a plurality of metal ions, a heavy trapping agent with a specific configuration is required to be matched with a protective agent for use, and selective removal of one heavy metal ion cannot be realized only by a single heavy metal collecting agent regardless of whether the addition amount is regulated; the added protective agent has obvious synergistic effect with the heavy metal trapping agent with a specific configuration.

Drawings

FIG. 1 is an infrared spectrum of chloropropyl diisoamyl dithiocarbamate as a heavy metal trapping agent prepared in example 2.

Detailed Description

The invention provides a heavy metal trapping agent, which has a structure shown in a formula I:

in the present invention, in formula I, n is 1, 2, 3;

R₁is straight-chain alkane or branched-chain alkane; the straight-chain alkane is methyl, ethyl, propyl, butyl, pentyl or octyl; the branched alkane is isobutyl, isoamyl or isooctyl.

In the present invention, the structural formula of the heavy metal trapping agent is specifically preferably:

the invention also provides a preparation method of the heavy metal trapping agent in the technical scheme, which comprises the following steps:

mixing carbon disulfide and dialkyl amine, and carrying out addition reaction to obtain mercapto dithiocarbamic acid;

and mixing the sulfhydrylation dithiocarbamic acid and dichloroalkane for substitution reaction to obtain the heavy metal trapping agent.

In the present invention, the raw materials are preferably those commercially available, unless otherwise specified.

In the invention, carbon disulfide and dialkyl amine are mixed for addition reaction to obtain the mercapto-dithio-carbamic acid.

In the present invention, the dialkylamine is dimethylamine, diethylamine, di-n-propylamine, di-n-butylamine, di-n-pentylamine, di-n-octylamine, diisobutylamine, diisopentylamine, or diisooctylamine.

In the present invention, the manner of mixing the carbon disulfide and the dialkylamine includes: carbon disulfide was added dropwise to the dialkylamine and mixed with stirring. In the invention, the dropping speed of the carbon disulfide is preferably 5-25 mL/min, more preferably 10-20 mL/min, and even more preferably 15 mL/min. In the invention, the dripping temperature is preferably-5-15 ℃, more preferably-5-10 ℃, and even more preferably 0 ℃. In the present invention, the temperature for stirring and mixing is preferably the same as the temperature for dropping according to the above technical scheme, and is not described herein again. In the present invention, the time for stirring and mixing is preferably 1 h; the stirring and mixing time is preferably counted after the completion of the dropwise addition.

In the present invention, the molar ratio of the dialkylamine to the carbon disulfide is preferably 1: (1.5-4), more preferably 1: (2 to 3.5), more preferably 1: (2.5-3).

In the invention, the temperature of the addition reaction is preferably 50-80 ℃, and more preferably 50-65 ℃; the time is preferably 2-6 h.

After the sulfenyl dithiocarbamic acid is obtained, the sulfenyl dithiocarbamic acid and dichloroalkane are mixed for substitution reaction to obtain the heavy metal trapping agent.

In the present invention, the dichloralkane is dichloromethane, dichloroethane or dichloropropane.

In the present invention, the molar ratio of the dialkylamine to the dichloralkane is preferably 1: (1 to 1.5), more preferably 1: (1 to 1.2), more preferably 1: 1.

in the present invention, the manner of mixing the mercaptodithiocarbamic acid and the dichloroalkane includes: the dichloroalkane is added dropwise to the mercaptolated dithiocarbamic acid and stirred and mixed. In the present invention, the dropping rate of the dichloroalkane is preferably 5 to 25mL/min, more preferably 10 to 20mL/min, and still more preferably 15 mL/min. In the invention, the dripping temperature is preferably-5-15 ℃, more preferably-5-10 ℃, and even more preferably 0 ℃. In the present invention, the temperature for stirring and mixing is preferably the same as the temperature for dropping according to the above technical scheme, and is not described herein again. In the present invention, the time for stirring and mixing is preferably 1 h; the stirring and mixing time is preferably counted after the completion of the dropwise addition.

In the invention, the temperature of the substitution reaction is preferably 40-60 ℃, more preferably 15-55 ℃, and more preferably 50 ℃; the time is preferably 1 to 5 hours, and more preferably 2 to 4 hours.

After the substitution reaction, the method preferably further comprises post-treatment, wherein the post-treatment preferably comprises distilling the obtained substitution reaction feed liquid to obtain a crude product; and (3) carrying out alkali washing, water washing, recrystallization and solid-liquid separation on the crude product, and drying the obtained solid to obtain the heavy metal trapping agent.

In the present invention, the distillation means preferably includes atmospheric distillation, vacuum distillation or rotary evaporation; the present invention does not specifically limit the distillation parameters, as long as the organic solvent in the substitution reaction feed liquid can be removed.

In the present invention, the alkali washing agent is preferably an inorganic alkali solution; the mass concentration of the inorganic alkali solution is preferably 5-20%; the inorganic base in the inorganic base solution is preferably potassium hydroxide or sodium hydroxide. In the present invention, the number of the alkali washing is preferably 2 to 5, and more preferably 3. In the present invention, the caustic wash is capable of neutralizing residual carbon disulfide in the crude product after the distillation operation.

In the present invention, the washing agent is preferably deionized water; the number of washing with water is not particularly limited as long as the washing with water is neutral.

In the present invention, the recrystallization reagent is preferably a mixed solution of isopropanol and ethanol; the volume ratio of the isopropanol to the ethanol in the mixed solution of the isopropanol and the ethanol is preferably 1: (2-5).

In the present invention, the solid-liquid separation is preferably performed by filtration.

The drying is not particularly limited in the present invention as long as the solid can be dried to a constant weight.

In the invention, the reaction formula for preparing the heavy metal trapping agent by using carbon disulfide, dialkyl amine and dichloroalkane as raw materials is shown as a formula II:

the invention also provides application of the heavy metal trapping agent in the technical scheme in the field of heavy metal removal.

In the present invention, the heavy metal preferably comprises Hg²⁺、Cd²⁺、Pb²⁺、Mn²⁺、Cu²⁺Or As³⁺。

In the invention, R in the formula I₁In the case of linear alkanes, the application preferably comprises the following steps:

and sequentially adding the heavy metal trapping agent and anionic polyacrylamide into the acidic wastewater for flocculation.

In the invention, the ratio of the molar weight of the heavy metal trapping agent to the total molar weight of heavy metal ions in the wastewater is preferably (2.5-7): 1. in the present invention, the mass concentration of the anionic polyacrylamide in the wastewater is preferably 1 to 5%.

In the invention, after the heavy metal trapping agent is added, stirring is preferably carried out for 5-60 min at normal temperature, and in the invention, the flocculation temperature is preferably room temperature, namely, neither extra heating nor extra cooling is needed; the flocculation is preferably carried out under standing conditions, and the flocculation time is preferably 30 min.

In the present invention, R in formula I₁In the case of straight-chain alkanes, a plurality of heavy metals can be removed simultaneously. In the present invention, the plurality of heavy metals include Hg²⁺、Cd²⁺、Pb²⁺、Mn²⁺、Cu²⁺And As³⁺

In the invention, R in the formula I₁In the case of branched alkanes, the application preferably comprises the following steps:

and sequentially adding a protective agent, the heavy metal trapping agent and anionic polyacrylamide into the acidic wastewater for flocculation.

In the present invention, the protecting agent preferably includes thiosulfate, tetrathionate or persulfate. In the present invention, the thiosulfate preferably includes potassium thiosulfate, sodium thiosulfate or magnesium thiosulfate. In the present invention, the tetrathionate preferably includes potassium tetrathionate or sodium tetrathionate. In the present invention, the persulfate preferably includes sodium persulfate, potassium persulfate, or ammonium persulfate.

In the invention, the molar ratio of the protective agent to the heavy metal ions to be removed in the wastewater is preferably (1-3): 1.

in the invention, the ratio of the molar weight of the heavy metal trapping agent to the total molar weight of the heavy metal ions to be removed in the wastewater is preferably (2.5-7): 1. in the present invention, the mass concentration of the anionic polyacrylamide in the acidic wastewater is preferably 1 to 5%.

In the invention, the principle of removing heavy metals by the heavy metal trapping agent is as follows: the heavy metal trapping agent and the heavy metal generate a chelating reaction to form a heavy metal trapping agent-heavy metal chelate shown in a formula III:

in the formula III, M is Hg²⁺、Cd²⁺、Pb²⁺、Mn²⁺、Cu²⁺Or As³⁺。

In the invention, R in the formula I₁When the heavy metal ions are branched alkanes, different heavy metal ions can be selectively removed by adjusting different branched alkane structures and protective agents, and the specific steps are as follows:

removal of Hg²⁺The method specifically comprises the following steps: adding a protective agent into acidic wastewater containing various heavy metal ions, and stirring at normal temperature for 3-10 min; adding the branched-chain heavy metal trapping agent, stirring at normal temperature for 10-20 min, adding PAM, flocculating, standing for 30min, filtering, and precipitating to obtain a mercury ion chelate of the branched-chain heavy metal trapping agent; the protective agent and heavy metal ions Hg to be removed in the wastewater²⁺The molar ratio of (1) to (1.5): 1; the branched-chain heavy metal trapping agent and heavy metal ions Hg to be removed in the wastewater²⁺The molar ratio of (2.5-4.0): 1; the mass concentration of PAM in the acidic wastewater is preferably 1-5 per mill; the protective agent is preferably potassium persulfate; r in the branched heavy metal trapping agent₁Preferably isobutyl, n ═ 2, and the chemical structure is as follows:

removal of Cd²⁺: the method specifically comprises the following steps: adding a protective agent into acidic wastewater containing various heavy metal ions, and stirring at normal temperature for 6-15 min; adding the branched-chain heavy metal trapping agent, stirring at normal temperature for 30-60 min, adding PAM, flocculating, standing for 30min, filtering, and precipitating to obtain the cadmium ion chelate of the branched-chain heavy metal trapping agent; the protective agent and heavy metal ions Cd to be removed in the acidic wastewater²⁺The molar ratio of (1.5-3.0): 1; the branched-chain heavy metal trapping agent and heavy metal ions Cd to be removed in the acidic wastewater²⁺The molar ratio of (a) to (b) is preferably (3.0 to 5.5): 1; the PAM has good quality in acid wastewaterThe amount concentration is preferably 1-5 per mill; the protective agent is preferably potassium tetrathionate; r in the branched heavy metal trapping agent₁Preferably isooctyl, n ═ 2, the chemical formula is preferably as follows:

removal of Pb²⁺: the method specifically comprises the following steps: adding a protective agent into acidic wastewater containing various heavy metal ions, and stirring at normal temperature for 10-20 min; adding the branched-chain heavy metal trapping agent, stirring at normal temperature for 30-60 min, adding PAM, flocculating, standing for 30min, filtering, and precipitating to obtain a lead ion chelate of the branched-chain heavy metal trapping agent; the protective agent and heavy metal ions Pb to be removed in the acidic wastewater²⁺The molar ratio of (1.5-2.5): 1: the branched-chain heavy metal trapping agent and heavy metal ions Pb to be removed from the acidic wastewater²⁺The molar ratio of (a) to (b) is preferably (4.0 to 7.0): 1; the mass concentration of the PAM in the acidic wastewater is preferably 1-5 per mill; the protective agent is preferably potassium thiosulfate; r in the heavy metal trapping agent₁Preferably isoamyl, n ═ 3, the chemical formula is as follows:

removal of Mn²⁺: the method specifically comprises the following steps: adding a protective agent into acidic wastewater containing various heavy metal ions, and stirring at normal temperature for 3-15 min; adding a branched-chain heavy metal trapping agent, stirring at normal temperature for 25-50 min, adding PAM, flocculating, standing for 30min, filtering, and precipitating to obtain a manganese ion chelate of the heavy metal trapping agent; the protective agent and heavy metal ions Mn to be removed in the acidic wastewater²⁺The molar ratio of (a) to (b) is preferably (1.0 to 3.0): 1; the branched-chain heavy metal trapping agent and heavy metal ions Mn to be removed in the acidic wastewater²⁺The molar ratio of (2.5-4.5): 1; the mass concentration of PAM in the acidic wastewater is preferably 1-5 per mill; the protective agent is preferably sodium persulfate; the heavy goldR in the trapping agent₁Preferably isoamyl, n ═ 2, the chemical formula is as follows:

removal of Cu²⁺: the method specifically comprises the following steps: adding a protective agent into acidic wastewater containing various heavy metal ions, and stirring at normal temperature for 15-20 min; adding the branched-chain heavy metal trapping agent, stirring at normal temperature for 40-60 min, adding a PAM solution, flocculating, standing for 30min, filtering, and precipitating to obtain a copper ion chelate of the branched-chain heavy metal trapping agent; the protective agent and heavy metal ions Cu to be removed in the acidic wastewater²⁺The molar ratio of (a) to (b) is preferably (1.0 to 3.0): 1; the branched-chain heavy metal trapping agent and heavy metal ions Cu to be removed in the acidic wastewater²⁺The molar ratio of (2.5-6.5): 1; the mass concentration of PAM in the acidic wastewater is preferably 1-5 per mill; the protective agent is preferably sodium thiosulfate; r in the heavy metal trapping agent₁Preferably isobutyl, n ═ 3, and the chemical formula is as follows:

removal of As³⁺: the method specifically comprises the following steps: adding a protective agent into acidic wastewater containing various heavy metal ions, and stirring at normal temperature for 15-20 min; adding the branched-chain heavy metal trapping agent, stirring at normal temperature for 25-60 min, adding PAM, flocculating, standing for 30min, filtering, and precipitating to obtain an arsenic ion chelate of the branched-chain heavy metal trapping agent; the protective agent and heavy metal ions As removed from the acidic wastewater³⁺The molar ratio of (1.5-2.0): 1; the branched-chain heavy metal trapping agent and heavy metal ions As removed from the wastewater³⁺The molar ratio of (2.5-6.5): 1; the mass concentration of PAM in the acidic wastewater is preferably 1-5 per mill; the protective agent is preferably magnesium thiosulfate; r in the removed heavy metal ions₁Preferably isooctyl, n ═ 3, the chemical formula is as follows:

the heavy metal trapping agent provided by the present invention, the preparation method and the application thereof are described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.

Example 1

25.8g (0.2mol) of di-n-butylamine are added into a three-neck flask, a thermostatic water bath at 5 ℃ is carried out, the reflux is started, and 31.2g of CS₂(0.4mol) is slowly dripped into a three-neck flask through a constant pressure dropping funnel, after the dripping is finished, the mixture is stirred for 1h at the temperature of 5 ℃, the temperature is raised to 65 ℃, the reaction is continued for 3h, then the temperature is lowered to 5 ℃, 20.4g (0.24mol) of dichloromethane is dripped, after the dripping is finished, the mixture is kept at the temperature of 5 ℃, stirred for 1h, and then the mixture is heated to 55 ℃ for reaction for 3 h. After the reaction, decompressing and distilling the dichloromethane and the incompletely reacted CS₂. Stirring and washing with 10 wt% NaOH solution for three times, washing with deionized water for three times, recrystallizing with isopropanol-ethanol (volume ratio of 1: 2), filtering, and drying to obtain the chloro-butyl-dithiocarbamic acid ester. Nuclear magnetic hydrogen spectrum of chloromethyl di-n-butyldithiocarbamate¹H-NMR(CDCl₃)δ(ppm)4.96(s，2H)，2.55(m，4H)，1.41(m，4H)，1.33(m，4H)，0.96(td，6H)。

Certain lead ore mining waste water, pH 1 ~ 2, main heavy metal ion in the waste water: pb²⁺2726mg/L，Cd²⁺497.2mg/L，Hg²⁺172.4mg/L。

Taking 2L of the wastewater, adding 18.9g (0.0672mol) of di-n-butyl dithiocarbamate chloromethyl ester, stirring at normal temperature for 30min, adding 1.0mL of 1wt per thousand PAM flocculating agent, standing for 30min, and filtering. And (3) detecting the concentrations of three heavy metal ions in the supernatant: pb²⁺52.3mg/L, and the removal rate is 98.1 percent; cd [ Cd ]²⁺47.6mg/L, removal rate 90.4%; hg is a mercury vapor²⁺16.8mg/L, and the removal rate is 90.2 percent.

Example 2

47.2g (0.3mol) of diisoamyl amine is added into a three-neck flask, a constant-temperature water bath is carried out at 5 ℃, the reflux is started, and 35.1g of CS₂(0.45mol) by dropping liquid at constant pressureThe funnel is slowly dripped into the three-neck flask, the mixture is stirred in a 5 ℃ constant temperature water bath for 1h after the dripping is finished, the temperature is raised to 75 ℃, the reaction is continued for 4.5h, the temperature is reduced to 0 ℃, 37.2g (0.33mol) of dichloropropane is dripped, the mixture is stirred for 1h after the dripping is finished and maintained at 0 ℃, and the reaction is carried out for 3.5h after the temperature is raised to 55 ℃. After the reaction, decompressing and distilling out the dichloropropane and the incompletely reacted CS₂. Stirring and washing with 10 wt% KOH solution for three times, washing with deionized water for three times, recrystallizing with isopropanol-ethanol (volume ratio is 1: 4), filtering, and drying to obtain the chloropropyl diisoamyl dithiocarbamate.

FIG. 1 is an infrared spectrum of the heavy metal trapping agent, namely, chloropropyl diisoamyl dithiocarbamate, which can be seen from FIG. 1: 3300cm^-1Is sparse radical absorption peak, 3140cm^-1A methyl absorption peak at 1650cm^-1Absorption peak of tertiary amine, 1570cm^-1At 1390cm, an isothiocyanato absorption peak^-1Is a sulfur-carbon bond absorption peak and accords with the infrared absorption peak of the main functional group of the diisoamyl dithio-amino chloropropyl carbamate.

Certain lead smelting wastewater, pH 2 ~ 4, main heavy metal ion in the wastewater: pb²⁺3500mg/L，Cd²⁺721.2mg/L，Hg²⁺66.4mg/L，Cr²⁺69.7mg/L。

Need to recover Pb in wastewater²⁺。

Taking 1L of the wastewater, adding 6.4g of potassium thiosulfate (0.0337mol), stirring at normal temperature for 15min, adding 23.7g (0.0766mol) of diisoamyl dithiocarbamic acid chloropropyl ester, stirring at normal temperature for 45min, adding 1.0mL of 1 wt% PAM flocculant, standing for 30min, and filtering. And (3) detecting the concentrations of three heavy metal ions in the supernatant: pb²⁺42.7mg/L, 98.8% removal; cd [ Cd ]²⁺673.1mg/L, 6.67% removal; hg is a mercury vapor²⁺50.8mg/L, the removal rate is 23.5 percent; cr (chromium) component²⁺56.2mg/L, the removal rate is 19.4%. Drying the precipitate, grinding the precipitate by a ball mill, and measuring the powder Pb by a handheld fluorescence spectrometer²⁺Mass fraction: 95.8 percent.

Example 3

30.4g (0.3mol) of di-n-propylamine are added into a three-neck flask, a constant-temperature water bath is carried out at the temperature of 5 ℃, the reflux is started, and 46.8g of CS₂(0.6mol) is slowly dripped into a three-neck flask through a constant pressure dropping funnel, stirred in a 5 ℃ constant temperature water bath for 1h after the dripping is finished, heated to 55 ℃, continuously reacted for 2h, then cooled to 0 ℃, added with 33.1g (0.39mol) of dichloromethane, stirred for 1h after the dripping is finished and maintained at 0 ℃, and then heated to 50 ℃ for reaction for 4.0 h. After the reaction, dichloromethane and incompletely reacted CS are distilled off₂. Stirring and washing with 8 wt% NaOH solution for three times, washing with deionized water for three times, recrystallizing with isopropanol-ethanol (volume ratio is 1: 2), filtering, and drying to obtain the chloromethyl di-n-propyl dithiocarbamate. Nuclear magnetic hydrogen spectrum of chloromethyl di-n-propyldithiocarbamate¹H-NMR(CDCl₃)δ(ppm)4.87(s，2H)，2.61(m，4H)，1.45(m，4H)，0.92(td，6H)。

Certain copper arsenic ore mining waste water, pH 1 ~ 3, main heavy metal ion in the waste water: cu²⁺3200 mg/L; metalloid ion As³⁺2400mg/L。

Taking 1L of the wastewater, adding 50.5g (0.224mol) of di-n-propyl dithiocarbamic acid chloromethyl ester, stirring at normal temperature for 25min, adding 1.0mL of 1wt per thousand PAM flocculating agent, standing for 30min, and filtering. And (3) detecting the concentrations of three heavy metal ions in the supernatant: cu²⁺13.2mg/L, removal 99.6%; as³⁺17.6mg/L, and the removal rate is 99.3 percent.

Example 4

Adding 38.8g (0.3mol) of diisobutylamine into a three-neck flask, carrying out constant-temperature water bath at 5 ℃, starting reflux, adding 35.1g of CS₂(0.45mol) is slowly dripped into a three-neck flask through a constant pressure dropping funnel, after the dripping is finished, the mixture is stirred in a 5 ℃ constant temperature water bath for 1h, the temperature is raised to 60 ℃, the reaction is continued for 2.5h, then the temperature is lowered to-5 ℃, 40.6g (0.36mol) of dichloropropane is added, after the dripping is finished, the mixture is kept at-5 ℃ for stirring for 1h, and then the temperature is raised to 50 ℃ for reaction for 4.5 h. After the reaction, decompressing and distilling out the dichloropropane and the incompletely reacted CS₂. Stirring and washing with 10 wt% NaOH solution for three times, washing with deionized water for three times, recrystallizing with isopropanol-ethanol (volume ratio is 1: 2), filtering, and drying to obtain diisobutyl dithiocarbamic acid chloropropyl ester. The diisobutyl dithioamino groupNuclear magnetic hydrogen spectrum of chloropropyl formate¹H-NMR(CDCl₃)δ(ppm)3.38(td，2H)，2.87(td，2H)，2.51(d，4H)2.24(m，2H)，2.07(m，2H)，1.01(dt，12H)。

Certain copper smelting waste water, pH 1 ~ 4, main heavy metal ion in the waste water: cu²⁺2760mg/L，Cd²⁺21.2mg/L，Hg²⁺16.5mg/L，As³⁺1769 mg/L. Need to recycle Cu in the wastewater²⁺。

Taking 1L of the wastewater, adding 11.3g of sodium thiosulfate (0.065mol), stirring at normal temperature for 10min, adding 31.2g (0.11mol) of diisobutyl dithiocarbamic acid chloropropyl ester, stirring at normal temperature for 35min, adding 1.5mL of 1 wt% of PAM flocculant, standing for 30min, and filtering. And (3) detecting the concentrations of three heavy metal ions in the supernatant: cu²⁺5.7mg/L, the removal rate is 99.8 percent; cd [ Cd ]²⁺19.1mg/L, and the removal rate is 9.90 percent; hg is a mercury vapor²⁺13.6mg/L, the removal rate is 17.6 percent; as³⁺1137mg/L, the removal rate is 35.7%. Drying the precipitate, grinding the precipitate by a ball mill, and measuring the Cu powder by a handheld fluorescence spectrometer²⁺Mass fraction: 98.1 percent.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.