Heavy metal capturing agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a heavy metal capturing agent and a preparation method and application thereof. The heavy metal capturing agent provided by the invention comprises a compound with a structure as shown in a formula (I) and ferrous sulfide, and in the formula (I), R1 is C1-C6 alkylene. The heavy metal capturing agent is formed by using a compound of double-active sulfur atoms and acrylamide groups with strong chelating property and ferrous sulfide, heavy metals are chelated by using the double-active sulfur atoms, and the chelated heavy metals are flocculated by using good flocculability of the acrylamide groups; meanwhile, ferrous sulfide is oxidized in water to form ferric hydroxide with a coagulation effect, heavy metal is further flocculated and settled, the settling rate and removal efficiency of the heavy metal are improved, meanwhile, hydroxyl free radicals generated by the ferrous sulfide can degrade organic complexing ligands, the complexing property of wastewater is reduced, and the heavy metal removal efficiency is improved. The complexing agent is prevented from being continuously complexed with subsequent heavy metal.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a heavy metal capture agent and a preparation method and application thereof. Background Art

[0002] Heavy metals exist in water mainly in the form of ions and complexes. Ionic heavy metals can be effectively removed by adding alkali precipitation. However, in recent years, with the continuous advancement of surface treatment technology, the rapid development of the electroplating industry has led to the discharge of a large amount of wastewater containing heavy metals. Since the composition of electroplating wastewater pollutants is very complex, containing organic complexing agents such as ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEA), tartaric acid and citric acid, heavy metal ions such as copper, nickel, and chromium in the wastewater accept electron pairs from the functional groups (such as carboxyl, amino, phenolic hydroxyl and thiol) in the complexing agent, and form a strong bond with the complexing agent to form a stable complex state. Due to the stable structure of complexed heavy metals, it is difficult to remove complexed heavy metals. At present, the methods for treating complexed heavy metal wastewater include advanced oxidation, chemical precipitation, ion exchange and chelation, but the above methods are not ideal for heavy metal removal.

[0003] The prior art provides a heavy metal capture agent that produces a strong chelation effect with heavy metal ions, which can generate a stable chelate precipitate with heavy metals and effectively separate heavy metals from the complex, but the following problems still exist:

[0004] (1) For wastewater with strong chelating properties, excessive amounts of reagents need to be added to remove heavy metals from the wastewater. This cannot avoid the problem of heavy metal capture agent residues, causing the heavy metal capture agent to bring secondary pollution, leading to environmental problems such as increased total nitrogen and TOC in the effluent.

[0005] (2) Heavy metal capture agents achieve the removal of complexed heavy metals by chelation precipitation, but the complexing agents in the wastewater still exist stably in the water, and the treated wastewater still has strong complexing properties, which will cause problems such as secondary complexed heavy metals, thereby increasing the difficulty of operation and management.

[0006] (3) After the heavy metal scavenger chelates the metal, the resulting flocs have poor sedimentation properties and the mud-water separation effect is poor, resulting in a low heavy metal removal rate. Summary of the invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the defect of low removal rate of heavy metals by heavy metal capture agents in the prior art, thereby providing a heavy metal capture agent and a preparation method and application thereof.

[0008] Another technical problem to be solved by the present invention is to overcome the problem that the heavy metal capture agent in the prior art cannot degrade the organic complexing agent in water, resulting in the complexing agent in water still having a complexing effect on the heavy metal, thereby causing the secondary complexation of the heavy metal, thereby providing a heavy metal capture agent and its preparation method and application.

[0009] The present invention also solves the problem of excessive dosage of heavy metal removal agent in wastewater in the prior art, resulting in agent residue and secondary pollution, thereby providing a heavy metal capture agent and its preparation method and application, reducing agent residue and secondary pollution.

[0010] In one aspect, the present invention provides a heavy metal capture agent, comprising a compound of the structure shown in formula (I) and ferrous sulfide.

[0011]

[0012] Wherein, R1 is a C1-C6 alkylene group.

[0013] In some embodiments, the R1 is at least one of methylene or ethylene.

[0014] Exemplarily, the structure represented by formula (I) is any one of the structures represented by formula (II) or formula (III),

[0015]

[0016] On the other hand, the present invention provides a method for preparing the heavy metal capture agent, comprising the following steps:

[0017] In the presence of an inert gas, at a first temperature, N-hydroxyalkyl acrylamide solution, carbon disulfide, metal sulfide and ferrous salt are mixed and reacted for a first time to obtain a heavy metal capture agent.

[0018] In the present invention, the structural formula of N-hydroxyalkyl acrylamide is shown in formula (IV),

[0019]

[0020] In formula (IV), R2 is a C1-C6 alkylene group, preferably a methylene group or an ethylene group.

[0021] For example, taking N-hydroxymethyl acrylamide as an example, the reaction formula of N-hydroxymethyl acrylamide, carbon disulfide and ferrous salt is shown in formula (V),

[0022]

[0023] In some embodiments, the molar ratio of N-hydroxyalkyl acrylamide, carbon disulfide and ferrous salt in the N-hydroxyalkyl acrylamide solution is 1:(2-3):(1-1.8),

[0024] The molar ratio of the metal sulfide to the ferrous salt is 1:(1-1.3).

[0025] In some embodiments, the ferrous salt includes at least one of ferrous sulfate, ferrous nitrate, and ferrous chloride.

[0026] In some embodiments, the metal sulfide includes at least one of sodium sulfide and potassium sulfide.

[0027] In order to make carbon disulfide, ferrous salt and N-hydroxyalkyl acrylamide fully react, carbon disulfide and ferrous salt are dropped into N-hydroxyalkyl acrylamide solution respectively, wherein the dropping rate of carbon disulfide is 200-600 μL / min, the dropping rate of ferrous salt solution is 800-1000 μL / min, and the total dropping time of carbon disulfide and ferrous salt is 1-3h.

[0028] Furthermore, in order to avoid the volatilization of carbon disulfide and improve the reaction efficiency, in an embodiment of the present invention, the first temperature is less than or equal to 50° C., preferably 20-45° C.; and the first time is 1-3 hours.

[0029] In some of the embodiments, the method for preparing the N-hydroxyalkyl acrylamide solution is to mix an aqueous acrylamide solution, an inhibitor and a hydroxyalkylating agent at a second temperature under alkaline conditions to obtain N-hydroxyalkyl acrylamide.

[0030] In some embodiments, the concentration of the acrylamide aqueous solution is 50-100 g / L.

[0031] In some embodiments, the amount of the polymerization inhibitor added is 100-200 ppm based on the mass of acrylamide.

[0032] In some embodiments, the molar ratio of acrylamide to hydroxyalkyl reagent is 1:(0.8-1.4).

[0033] In some embodiments, the inhibitor includes at least one of N-nitrosodiphenylamine, phenothiazine, hydroquinone, and p-hydroxyanisole.

[0034] Preferably, the polymerization inhibitor includes any two of N-nitrosodiphenylamine, phenothiazine, hydroquinone, and p-hydroxyanisole.

[0035] It should be noted that the inhibitor does not react with the raw materials in the reaction system and will not affect the formation of the heavy metal adsorbent if it remains in the reaction system.

[0036] In some embodiments, the hydroxyalkyl reagent includes a C1-C6 hydroxyalkyl reagent.

[0037] Preferably, the hydroxyalkyl reagent is at least one of formaldehyde or ethylene oxide.

[0038] In some embodiments, the hydroxyalkyl reagent is used in the preparation of N-hydroxyalkyl acrylamide in the form of a solution, wherein the hydroxyalkyl reagent in the aqueous solution is 30-40 wt %.

[0039] In some of the embodiments, the pH value of the reaction solution in the preparation method of N-hydroxyalkyl acrylamide is 9-11.

[0040] In some embodiments, the second temperature is 20-70°C. In order to avoid polycondensation of the hydroxyalkyl reagent, in the embodiments of the present invention, the second temperature is preferably 40-50°C.

[0041] In some of the embodiments, the acrylamide aqueous solution, the polymerization inhibitor and the hydroxyalkyl reagent are mixed under stirring, the stirring rate is 300-500 rpm, and the stirring time is 1-2 hours.

[0042] The heavy metal capture agent provided by the present invention or the heavy metal capture agent prepared by the preparation method of the heavy metal capture agent can be applied to wastewater treatment. The heavy metal capture agent provided by the present invention can chelate the insoluble floccules in the wastewater and settle them. When there are organic matters such as colloids in the wastewater, the separation efficiency of organic matters in the wastewater can also be improved by applying an external magnetic field.

[0043] The technical solution of the present invention has the following advantages:

[0044] 1. A heavy metal scavenger provided by the present invention comprises a compound having a structure shown in formula (I) and ferrous sulfide, wherein R1 in formula (I) is an alkylene group of C1-C6. The present invention utilizes a compound having a strong chelating property of a double active sulfur atom and an acrylamide group to form a heavy metal scavenger with ferrous sulfide, utilizes the double active sulfur atom to chelate heavy metals, utilizes the good flocculation property of the acrylamide group to flocculate the chelated heavy metals, and simultaneously utilizes the prepared ferrous sulfide to be oxidized in water to form ferric hydroxide with a coagulation effect, further flocculates and precipitates heavy metals, thereby improving the sedimentation rate and removal efficiency of heavy metals. At the same time, the hydroxyl radicals with strong oxidizing properties generated by ferrous sulfide in water degrade organic complexing ligands, reduce the complexing property of wastewater, and avoid continuous complexing of the complexing agent with subsequent heavy metals. The heavy metal scavenger provided by the present invention can reduce the content of complexed heavy metals from two aspects: precipitation of heavy metals and degradation of complexes.

[0045] 2. The heavy metal capture agent provided by the present invention has low molecular weight, high utilization rate, low residue, and excellent effect in removing complexed heavy metals. Compared with the common multi-branched polymer heavy metal capture agents on the market, the heavy metal capture agent provided by the present invention has low sludge production and low sludge disposal cost. At the same time, it can degrade the concentration of organic matter such as organic complexing agents in wastewater, reduce the complexing property of wastewater, reduce the difficulty of back-end processing, and facilitate on-site back-end operation management.

[0046] 3. The present invention provides a method for preparing the above-mentioned heavy metal scavenger, in the presence of an inert gas, at a first temperature, after mixing N-hydroxyalkyl acrylamide solution, carbon disulfide, metal sulfide and ferrous salt, reacting for a first time, to obtain a heavy metal scavenger. The preparation method provided by the present invention has simple process steps and short synthesis time. In particular, since ferrous sulfide has the property of being easily oxidized, the oxidized ferrous sulfide on the market cannot participate in the removal of heavy metals in water. Therefore, the present application uses metal sulfide and ferrous salt to prepare ferrous sulfide, and forms a compound having a structure shown in formula (I) with N-hydroxyalkyl acrylamide and carbon disulfide to form a scavenger to effectively remove heavy metals in water.

[0047] 4. The present invention provides a method for preparing a heavy metal scavenger, wherein the preparation method of N-hydroxyalkyl acrylamide comprises mixing an aqueous acrylamide solution, a polymerization inhibitor and a hydroxyalkylating agent at a second temperature under alkaline conditions to obtain N-hydroxyalkyl acrylamide. The present invention uses acrylamide and a hydroxyalkylating agent as raw materials to prepare N-hydroxyalkyl acrylamide, and the N-hydroxyalkyl acrylamide prepared in an on-the-spot preparation manner has high solubility and high reaction efficiency with carbon disulfide and ferrous salt.

[0048] 5. A method for preparing a heavy metal scavenger provided by the present invention, wherein the inhibitor comprises any two of N-nitrosodiphenylamine, phenothiazine, hydroquinone, and p-hydroxyanisole. The present invention selects two inhibitors to prepare N-hydroxyalkyl acrylamide, which has a better inhibition effect, reduces by-products, and improves the yield of N-hydroxyalkyl acrylamide.

[0049] 6. The heavy metal capture agent provided by the present invention or the heavy metal capture agent prepared by the preparation method of the heavy metal capture agent can be used in wastewater treatment, with high heavy metal removal efficiency, no residual agent, and no increase in total nitrogen or total organic carbon content, effectively avoiding the problem of secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 This is the infrared spectrum of the organic compound in the heavy metal scavenger of Example 1 of the present invention. DETAILED DESCRIPTION

[0052] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0053] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0054] Example 1

[0055] This embodiment provides a method for preparing a heavy metal capture agent, and the specific steps and parameters are as follows:

[0056] (1) 7 g of acrylamide was weighed into a reactor, and 100 mL of deionized water was added. The stirring speed was controlled at 400 rpm. 100 ppm of N-nitrosodiphenylamine (compared to the mass of acrylamide), 50 ppm of phenothiazine (compared to the mass of acrylamide), and 10 mL of a formaldehyde solution with a formaldehyde concentration of 30 wt % were added in sequence. The reaction pH was adjusted to 10 with 10 wt % of sodium hydroxide. The temperature of the entire reaction system was controlled at 50° C. and the reaction was carried out for 1.5 h to prepare N-hydroxymethyl acrylamide.

[0057] (2) The reactor of step (1) was sealed, and nitrogen was continuously introduced into the reactor for protection. 15 mL of carbon disulfide was added dropwise into the reactor at a flow rate of 200 μL / min using a microinjector, and 55 mL of a 50 wt% aqueous solution of ferrous sulfate heptahydrate and 12 mL of a 50% sodium sulfide were added dropwise into the reactor at a flow rate of 800 μL / min. The reaction temperature was controlled within 50° C. After the addition, the reaction was continued to stir for 2 h to obtain a light green liquid, which was a heavy metal scavenger.

[0058] The heavy metal scavenger prepared in this example was tested by infrared spectroscopy. Figure 1 , among which, 1900-1650cm -1 Characteristic peaks appear in the range of -C=O-; 1690-1500cm -1 Characteristic peaks appear in the range of -C=C-; 1100-1000cm -1 Characteristic peaks appear in the range of 700-600cm -1 A characteristic peak appears within the range, indicating the presence of -CS- on the surface.

[0059] Example 2

[0060] This embodiment provides a method for preparing a heavy metal capture agent, and the specific steps and parameters are as follows:

[0061] (1) 7 g of acrylamide was weighed into a reactor, and 100 mL of deionized water was added. The stirring speed was controlled at 500 rpm. 100 ppm of hydroquinone (compared to the mass of acrylamide), 100 ppm of phenothiazine (compared to the mass of acrylamide), and 10 mL of a formaldehyde solution with a formaldehyde concentration of 37 wt % were added in sequence. The reaction pH was adjusted to 11 with 10 wt % of sodium hydroxide. The temperature of the entire reaction system was controlled at 20° C. to prepare N-hydroxymethyl acrylamide.

[0062] (2) The reactor of step (1) was sealed, and nitrogen was continuously introduced into the reactor for protection. 15 mL of carbon disulfide was added dropwise into the reactor at a flow rate of 200 μL / min using a microinjector. 100 mL of 50% ferrous sulfate heptahydrate aqueous solution and 22 mL of 50% sodium sulfide were added dropwise into the reactor at a flow rate of 1500 μL / min. The reaction temperature was controlled within 50°C. After the addition was completed, the reaction was continued to stir for 1 hour to obtain a light green liquid, which was a heavy metal capture agent.

[0063] Example 3

[0064] This embodiment provides a method for preparing a heavy metal capture agent, and the specific steps and parameters are as follows:

[0065] (1) 7 g of acrylamide was weighed into a reactor, and 100 mL of deionized water was added, the stirring speed was controlled to 300 rpm, 50 ppm of p-hydroxyanisole (compared to the mass of acrylamide), 50 ppm of N-nitrosodiphenylamine (compared to the mass of acrylamide), and 10 mL of a formaldehyde solution with a formaldehyde concentration of 40 wt % were added in sequence, the reaction pH was adjusted to 9 with 10 wt % of sodium hydroxide, the temperature of the entire reaction system was controlled at 70° C., and the reaction was carried out for 1 h to prepare N-hydroxymethyl acrylamide.

[0066] (2) The reactor of step (1) is sealed, and nitrogen is continuously introduced therein for protection. Carbon disulfide is added dropwise into the reactor at a flow rate of 200 μL / min using a microinjector. 36 mL of a 50% aqueous solution of ferrous nitrate and 50% potassium sulfide are added dropwise into the reactor at a flow rate of 1000 μL / min, wherein the molar ratio of N-hydroxymethyl acrylamide, carbon disulfide and ferrous nitrate is 1:3:1, and the molar ratio of potassium sulfide and ferrous nitrate is 1:1.3. After the reaction temperature is controlled to be within 50°C, the reaction is stirred for 3 hours to obtain a light green liquid, which is a heavy metal capture agent.

[0067] Example 4

[0068] This embodiment provides a method for preparing a heavy metal capture agent, and the specific steps and parameters are as follows:

[0069] (1) 7 g of acrylamide was weighed into a reactor, and 100 mL of deionized water was added. The stirring speed was controlled at 400 rpm. 100 ppm of N-nitrosodiphenylamine (compared to the mass of acrylamide), 50 ppm of phenothiazine (compared to the mass of acrylamide), and 14 mL of a formaldehyde solution with a formaldehyde concentration of 35 wt % were added in sequence. The reaction pH was adjusted to 10 with 10 wt % of sodium hydroxide. The temperature of the entire reaction system was controlled at 50° C. and the reaction was carried out for 1.5 h to prepare N-hydroxymethyl acrylamide.

[0070] (2) The reactor of step (1) is sealed, and nitrogen is continuously introduced therein for protection. Carbon disulfide is dripped into the reactor at a flow rate of 600 μL / min using a microinjector. A 50% by mass aqueous solution of ferrous chloride and a 50% by mass sodium sulfide are dripped into the reactor at a flow rate of 900 μL / min, wherein the molar ratio of N-hydroxymethyl acrylamide, carbon disulfide and ferrous chloride is 1:3:1, and the molar ratio of sodium sulfide and ferrous chloride is 1:1. The reaction temperature is controlled within 50°C. After the dripping, the reaction is stirred for 3 hours to obtain a light green liquid, which is a heavy metal capture agent.

[0071] Example 5

[0072] This embodiment provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that an equal mass of phenothiazine is used to replace N-nitrosodiphenylamine, that is, the inhibitor is 150 ppm phenothiazine (compared to the mass of acrylamide).

[0073] Example 6

[0074] This embodiment provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that in step (1), the temperature of the entire reaction system is controlled at 40°C.

[0075] Example 7

[0076] This embodiment provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that in step (1), the temperature of the entire reaction system is controlled at 60°C.

[0077] Example 8

[0078] This embodiment provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that in step (2), the reaction temperature is controlled at 20°C.

[0079] Example 9

[0080] This embodiment provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that in step (2), the reaction temperature is controlled at 45°C.

[0081] Example 10

[0082] This embodiment provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that an equal volume of 30 wt % ethylene oxide aqueous solution is used to replace the formaldehyde solution in step (1).

[0083] Embodiment 11

[0084] This embodiment provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that an equal volume of a commercially available N-hydroxymethylacryloyl aqueous solution (with a concentration of 1 mol / L) is used to replace the N-hydroxymethylacryloyl prepared in the reactor in step (2).

[0085] Comparative Example 1

[0086] This comparative example provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those of Example 1, except that step (1) is not included, and an equimolar amount of acrylamide is used to replace N-hydroxymethyl acrylamide in step (2).

[0087] Comparative Example 2

[0088] The present comparative example provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those of Example 1, except that step (2) does not contain ferrous sulfate, that is, (2) the reactor of step (1) is sealed, and nitrogen is continuously introduced therein for protection. 15 mL of carbon disulfide is dripped into the reactor at a flow rate of 200 μL / min using a microinjector, and 12 mL of sodium sulfide with a mass fraction of 50% is dripped into the reactor at a flow rate of 800 μL / min. The reaction temperature is controlled within 50°C. After the dripping, the reaction is continued to be stirred for 2 h to obtain a light green liquid, which is the heavy metal scavenger.

[0089] Comparative Example 3

[0090] The present comparative example provides a method for preparing a heavy metal scavenger. The specific steps and parameters are the same as those in Example 1, except that step (2) does not contain carbon disulfide, that is, (2) the reactor of step (1) is sealed, and nitrogen is continuously introduced therein for protection. 55 mL of a 50 wt% aqueous solution of ferrous sulfate heptahydrate and 12 mL of a 50% sodium sulfide are dripped into the reactor at a flow rate of 800 μL / min using a microinjector, and the reaction temperature is controlled within 50°C. After the dripping, the reaction is continued to be stirred for 2 h to obtain a light green liquid, which is the heavy metal scavenger.

[0091] Experimental example

[0092] The zinc-nickel alloy wastewater from a certain electroplating park in Ningbo was treated as the target. 2+ 、Ni 2+ The concentrations were 453 mg / L and 63.21 mg / L respectively, the total nitrogen concentration was 1392 mg / L, and the TOC concentration was 3240 mg / L.

[0093] Take 100 mL of wastewater sample, add 0.2 mL of heavy metal capture agent, stir at 500 rpm for 30 min, filter with filter paper, collect the filtrate, acidify with nitric acid until the water sample is acidic and clear, and detect Zn in the water sample by ICP-OES. 2+ 、Ni 2+ The total nitrogen (TN) in the water sample was determined by alkaline potassium persulfate ultraviolet spectrophotometry (HJ 636-2012), and the total organic carbon content (TOC) was detected by a total organic carbon analyzer, wherein the heavy metal capture agents were the metal capture agents prepared in Examples 1-11 and Comparative Examples 1-3, respectively.

[0094] Table 1 Wastewater treatment results

[0095]

[0096] According to Table 1, compared with Comparative Examples 1-3, the heavy metal capture agent provided by the embodiment of the present invention can effectively reduce the concentration of heavy metals in wastewater, has a good heavy metal removal effect, and will not cause an increase in the total nitrogen and total organic carbon content in the wastewater.

[0097] Since the method for detecting the content of complex substances in water samples generally adopts the method of taking treated water samples, adjusting the pH value of the water samples to 4, adding sufficient Ni ions to make the concentration of Ni ions in the water samples 1g / L, and continuously stirring for 1h, the pH value of the water samples is adjusted to 10.5 with lime, and the content of Ni ions is detected to characterize the content of complex substances. As can be seen from the results in Table 1, the heavy metal capture agent provided by the present invention can significantly reduce the content of Ni ions in water samples, which further proves that the heavy metal capture agent provided by the present invention can reduce the content of complex substances in water samples.

[0098] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A heavy metal scavenger, characterized in that: It comprises a compound having a structure shown in formula (I) and ferrous sulfide, Wherein, R1 is a C1-C6 alkylene group.

2. The heavy metal scavenger according to claim 1, characterized in that The R1 is at least one of methylene or ethylene; The molar ratio of the compound having the structure shown in formula (I) to ferrous sulfide is 1:1-1.

8.

3. A method for preparing the heavy metal scavenger according to any one of claims 1 to 2, characterized in that: The following steps are included: In the presence of an inert gas, at a first temperature, N-hydroxyalkyl acrylamide solution, carbon disulfide, metal sulfide and ferrous salt are mixed and reacted for a first time to obtain a heavy metal capture agent.

4. The method for preparing a heavy metal scavenger according to claim 3, characterized in that: The molar ratio of N-hydroxyalkyl acrylamide, carbon disulfide and ferrous salt in the N-hydroxyalkyl acrylamide solution is 1:2-3:1-1.

8. The molar ratio of the metal sulfide to the ferrous salt is 1:1-1.

3.

5. The method for preparing a heavy metal scavenger according to claim 3, characterized in that: The ferrous salt includes at least one of ferrous sulfate, ferrous nitrate and ferrous chloride; and / or, The metal sulfide includes at least one of sodium sulfide and potassium sulfide; and / or, The first temperature is less than or equal to 50° C., preferably 20-45° C.; and / or, The first time is 1-3h.

6. The method for preparing a heavy metal scavenger according to claim 5, characterized in that: The method for preparing the N-hydroxyalkyl acrylamide solution comprises mixing an aqueous acrylamide solution, a polymerization inhibitor and a hydroxyalkylating agent at a second temperature under alkaline conditions to obtain the N-hydroxyalkyl acrylamide solution.

7. The method for preparing a heavy metal scavenger according to claim 6, characterized in that: The concentration of the acrylamide aqueous solution is 50-100 g / L; and / or, The amount of the polymerization inhibitor added is 100-200 ppm based on the mass of acrylamide; and / or, The molar ratio of acrylamide to hydroxyalkyl reagent is 1:0.8-1.4; and / or, The inhibitor comprises at least one of N-nitrosodiphenylamine, phenothiazine, hydroquinone and p-hydroxyanisole; and / or, The hydroxyalkyl reagent includes a C1-C6 hydroxyalkyl reagent.

8. The method for preparing a heavy metal scavenger according to claim 7, characterized in that: The hydroxyalkyl reagent is at least one of formaldehyde or ethylene oxide; and / or, The second temperature is 20-70°C, preferably 40-50°C; and / or, Under stirring, the acrylamide aqueous solution, the polymerization inhibitor and the hydroxyalkyl reagent are mixed at a rate of 300-500 rpm for a time of 1-2 h; and / or, The polymerization inhibitor includes any two of N-nitrosodiphenylamine, phenothiazine, hydroquinone and p-hydroxyanisole.

9. Use of the heavy metal scavenger according to any one of claims 1 to 2 or the heavy metal scavenger prepared by the preparation method of the heavy metal scavenger according to any one of claims 3 to 8 in wastewater treatment.

10. The use according to claim 9, characterized in that: The ratio of the heavy metal capture agent to the wastewater is 1-3:1, and the unit is mL:L.

Images