A method for treating heavy metal industrial wastewater including chemical precipitation.

Abstract

This invention discloses a method for treating heavy metal industrial wastewater including chemical precipitation, comprising the following steps: adding ferrous sulfate to the heavy metal-containing industrial wastewater to chemically treat the heavy metal ions in the wastewater; then adding a reagent to the obtained supernatant to adjust the pH to 9-10; adding a flocculant; stirring and filtering to obtain a filtrate; adding a composite adsorbent to the filtrate; stirring and filtering; wherein the composite adsorbent is a mixture of activated carbon, modified carbon nanotubes, and diatomaceous earth. The heavy metal industrial wastewater treatment method including chemical precipitation proposed in this invention is simple in process and effective for Cu... 2+ Ni 2+ Pb 2+ It has the ability to remove various metal ions, with a high removal rate and stable removal effect.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for treating heavy metal industrial wastewater that includes chemical precipitation. Background Technology

[0002] Industrial wastewater refers to wastewater and waste liquid discharged during industrial processes. It contains industrial raw materials, intermediate products, by-products, and pollutants generated during production, and is a significant cause of environmental pollution. Industrial wastewater containing heavy metals can cause severe damage to the surrounding soil environment, affect vegetation and animal growth, and endanger human water sources. Therefore, effectively removing heavy metals from wastewater is of great importance for protecting aquatic environments and human health.

[0003] Currently, commonly used technologies for treating industrial wastewater containing heavy metals include chemical precipitation, oxidation-reduction, solvent extraction, ion exchange, adsorption, membrane separation, phytoremediation, bioflocculation, and bioadsorption. However, these current treatment processes suffer from drawbacks such as unsatisfactory and unstable treatment effects when dealing with wastewater containing heavy metals. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, this invention proposes a method for treating heavy metal industrial wastewater that includes chemical precipitation. The process is simple and effective for Cu... 2+ Ni 2+ Pb 2+ It has the ability to remove various metal ions, with a high removal rate and stable removal effect.

[0005] This invention proposes a method for treating heavy metal industrial wastewater using chemical precipitation, comprising the following steps:

[0006] S1. Add ferrous sulfate to the industrial wastewater containing heavy metals to chemically treat the heavy metal ions in the wastewater. Then, add a reagent to the obtained supernatant to adjust the pH value to 9-10, add a flocculant, stir, and filter to obtain the filtrate.

[0007] S2. Add the composite adsorbent to the filtrate, stir, and then filter; wherein the composite adsorbent is a mixture of activated carbon, modified carbon nanotubes, and diatomaceous earth.

[0008] Preferably, in S1, the stirring time is 35-50 minutes.

[0009] Preferably, in S1, the weight of the flocculant is 0.08-0.11% of the weight of the industrial wastewater containing heavy metals.

[0010] Preferably, the flocculant is one or a mixture of polyacrylamide, polyferric sulfate, and polyethyleneimine.

[0011] Preferably, in S2, the stirring time is 55-70 min.

[0012] Preferably, in S2, the weight of the composite adsorbent is 0.15-0.28% of the weight of the heavy metal-containing industrial wastewater in S1.

[0013] Preferably, in S2, the weight ratio of activated carbon, modified carbon nanotubes, and diatomaceous earth is 7-12:1-5:2-6.

[0014] Preferably, the diatomite is 3-mercaptopropyltrimethoxysilane modified diatomite.

[0015] Preferably, in step S2, the preparation process of the modified carbon nanotubes includes the following steps: mixing silane coupling agent KH-560 with toluene, adding carboxylated carbon nanotubes and triethylamine under stirring, heating to 105-120℃ under nitrogen protection and stirring for 9-13 hours, filtering, washing, and drying to obtain grafted modified carbon nanotubes; adding 9-decen-1-amine to dimethylformamide, adding grafted modified carbon nanotubes, and heating under nitrogen protection. The mixture was stirred at 70-80℃ for 5-10 hours. After washing and drying the product, amine-modified carbon nanotubes were obtained. The amine-modified carbon nanotubes were added to ethyl acetate, along with 1,4-diamino-2,5-divinylbenzene and 5-thiol-1,2,4-triazol-3-allylthiourea. After stirring until homogeneous, nitrogen gas was introduced, and azobisisobutyronitrile was added. Under nitrogen protection, the mixture was heated to 70-75℃ and reacted for 20-30 hours. After post-treatment, the modified carbon nanotubes were obtained.

[0016] Preferably, in the preparation process of modified carbon nanotubes, the mass-volume ratio of silane coupling agent KH-560, toluene, carboxylated carbon nanotubes, and triethylamine is 4-6 ml: 50-60 ml: 3-5 g: 0.13-0.18 ml.

[0017] Preferably, in the preparation of modified carbon nanotubes, the mass-to-volume ratio of 9-decen-1-amine, dimethylformamide, and grafted modified carbon nanotubes is 5.5-9g: 75-100ml: 6-13g.

[0018] Preferably, in the preparation of modified carbon nanotubes, the weight-to-volume ratio of amine-modified carbon nanotubes, ethyl acetate, 1,4-diamino-2,5-divinylbenzene, 5-thiol-1,2,4-triazol-3-allylthiourea, and azobisisobutyronitrile is 1.5-3g:100ml:6-8.9g:4-9g:0.2-0.31g.

[0019] Preferably, the 5-thiol-1,2,4-triazole-3-allylthiourea described in this invention can be prepared by the following process: dioxane and allyl isothiocyanate are mixed, 3-amino-1,2,4-triazole-5-thiol is added and stirred evenly, heated to 55-60°C and stirred for 5-7 hours, after which the reaction is completed, cooled to room temperature, vacuum concentrated, evaporated, and separated by silica gel column chromatography.

[0020] Preferably, in the preparation process of modified carbon nanotubes, the washing process may include sequential washing with toluene, acetone, water, and acetone.

[0021] Preferably, in the preparation process of modified carbon nanotubes, the washing process may include sequential water washing and alcohol washing.

[0022] Preferably, in the preparation process of modified carbon nanotubes, the post-treatment may include the following steps: cooling the reaction product to room temperature, filtering, washing the obtained solid with ethanol, and vacuum drying.

[0023] Preferably, in S1, the weight of ferrous sulfate added per liter of heavy metal-containing industrial wastewater can be 50-100 mg.

[0024] Preferably, in S1, the agent can be sodium hydroxide.

[0025] The present invention describes a method for treating heavy metal industrial wastewater using chemical precipitation. This method involves adding ferrous sulfate to the wastewater to chemically treat heavy metal ions, then adjusting the pH to 9-10 by adding a reagent to the resulting supernatant, adding a flocculant, and finally adding a specific adsorbent for adsorption. This synergistic effect of chemical precipitation, flocculation, and adsorption is achieved, resulting in the removal of various heavy metal ions with high removal rates and stable effects. In a preferred embodiment, during the preparation of modified carbon nanotubes, carboxylated carbon nanotubes are first modified using silane coupling agent KH-560. By controlling the reaction conditions, the silane coupling agent KH-560 interacts with the carboxylated carbon nanotubes, introducing epoxy groups onto the surface of the carbon nanotubes to obtain grafted modified carbon nanotubes. Subsequently, 9-decen-1-amine and the grafted modified carbon nanotubes are used... Using rice nanotubes as raw materials, and controlling the reaction conditions, the amino group in 9-decen-1-amine reacted with the epoxy group on the surface of the grafted modified carbon nanotubes, introducing 9-decen-1-amine onto the surface of the carbon nanotubes, resulting in amine-modified carbon nanotubes with double bonds on the surface. Subsequently, using amine-modified carbon nanotubes, 1,4-diamino-2,5-divinylbenzene, and 5-thiol-1,2,4-triazol-3-allylthiourea as raw materials, and controlling the reaction conditions, the three reacted and bonded together under the action of azobisisobutyronitrile (AIBN), yielding the modified carbon nanotubes. These modified carbon nanotubes exhibit altered surface properties, good stability, large specific surface area and pore capacity, and contain multiple functional groups and numerous adsorption sites. The adsorbent obtained by mixing with activated carbon and diatomaceous earth exhibits excellent adsorption of various heavy metal ions such as copper, nickel, lead, and manganese, with fast adsorption rate, high adsorption efficiency, and stable adsorption effect. Detailed Implementation

[0026] The technical solution of the present invention will now be described in detail through specific embodiments.

[0027] Example 1

[0028] This invention proposes a method for treating heavy metal industrial wastewater using chemical precipitation, comprising the following steps:

[0029] S1. Ferrous sulfate is added to the industrial wastewater containing heavy metals to chemically treat the heavy metal ions in the wastewater. Then, a reagent is added to the obtained supernatant to adjust the pH value to 9. Polyacrylamide is added, wherein the weight of the polyacrylamide is 0.11% of the weight of the industrial wastewater containing heavy metals. After stirring for 35 minutes, the mixture is filtered to obtain the filtrate.

[0030] S2. Add the composite adsorbent to the filtrate, stir for 60 minutes, and then filter. The weight of the composite adsorbent is 0.21% of the weight of the heavy metal-containing industrial wastewater in S1. The composite adsorbent is composed of activated carbon, modified carbon nanotubes, and diatomaceous earth, with a weight ratio of 7:5:4. The diatomaceous earth is 3-mercaptopropyltrimethoxysilane-modified diatomaceous earth. The preparation process of the modified carbon nanotubes includes the following... Steps: Silane coupling agent KH-560 was mixed with toluene. Carboxylated carbon nanotubes and triethylamine were added under stirring. The mass-to-volume ratio of silane coupling agent KH-560, toluene, carboxylated carbon nanotubes, and triethylamine was 4 ml:60 ml:3 g:0.18 ml. The mixture was heated to 110 °C and stirred for 13 h under nitrogen protection. After filtration, washing, and drying, grafted modified carbon nanotubes were obtained. 9-Decan-1-amine was added to dimethylformyl... Grafted modified carbon nanotubes were added to an amine, wherein the mass-to-volume ratio of 9-decen-1-amine, dimethylformamide, and grafted modified carbon nanotubes was 5.5 g:75 ml:8 g. The mixture was heated to 70 °C and stirred for 10 h under nitrogen protection. The product was washed and dried to obtain amine-modified carbon nanotubes. The amine-modified carbon nanotubes were then added to ethyl acetate, along with 1,4-diamino-2,5-divinylbenzene and 5-thiol-1,2,4-triazole-3- Allyl thiourea was stirred until homogeneous, and nitrogen gas was introduced. Azobisisobutyronitrile was then added. The weight-to-volume ratio of amine-modified carbon nanotubes, ethyl acetate, 1,4-diamino-2,5-divinylbenzene, 5-thiol-1,2,4-triazol-3-allyl thiourea, and azobisisobutyronitrile was 1.5 g: 100 ml: 8.9 g: 4 g: 0.31 g. The mixture was heated to 72 °C and reacted for 28 h under nitrogen protection. After post-treatment, the modified carbon nanotubes were obtained.

[0031] Example 2

[0032] This invention proposes a method for treating heavy metal industrial wastewater using chemical precipitation, comprising the following steps:

[0033] S1. Ferrous sulfate is added to the industrial wastewater containing heavy metals to chemically treat the heavy metal ions in the wastewater. Then, a reagent is added to the obtained supernatant to adjust the pH value to 10. Polyferric sulfate flocculant is added, and the mixture is stirred for 50 minutes and then filtered to obtain the filtrate. The weight of the polyferric sulfate flocculant is 0.08% of the weight of the industrial wastewater containing heavy metals.

[0034] S2. Add the composite adsorbent to the filtrate, stir for 55 minutes, and then filter. The weight of the composite adsorbent is 0.28% of the weight of the heavy metal-containing industrial wastewater in S1. The composite adsorbent is composed of activated carbon, modified carbon nanotubes, and diatomaceous earth, and the weight ratio of activated carbon, modified carbon nanotubes, and diatomaceous earth is 12:1:2.

[0035] The diatomite is 3-mercaptopropyltrimethoxysilane modified diatomite;

[0036] The preparation process of the modified carbon nanotubes includes the following steps: Silane coupling agent KH-560 is mixed with toluene, and carboxylated carbon nanotubes and triethylamine are added under stirring. The mixture is heated to 120°C and stirred for 9 hours under nitrogen protection. After filtration, washing, and drying, grafted modified carbon nanotubes are obtained. 9-Decane-1-amine is added to dimethylformamide, and grafted modified carbon nanotubes are added. The mixture is heated to 77°C and stirred for 6 hours under nitrogen protection. The product is washed and dried to obtain amine-modified carbon nanotubes. The amine-modified carbon nanotubes are added to ethyl acetate, and 1,4-diamino-2,5-divinylbenzene and 5-thiol-1,2,4-triazol-3-allylthiourea are added. After stirring until homogeneous, nitrogen gas is introduced. Azobisisobutyronitrile (AIBN) was added, and the mixture was heated to 74°C and reacted for 23 hours under nitrogen protection. After post-treatment, the modified carbon nanotubes were obtained. During the preparation process, the mass-to-volume ratio of silane coupling agent KH-560, toluene, carboxylated carbon nanotubes, and triethylamine was 6 ml:50 ml:5 g:0.13 ml; the mass-to-volume ratio of 9-decen-1-amine, dimethylformamide, and grafted modified carbon nanotubes was 7 g:100 ml:13 g; and the weight-to-volume ratio of amine-modified carbon nanotubes, ethyl acetate, 1,4-diamino-2,5-divinylbenzene, 5-thiol-1,2,4-triazol-3-allylthiourea, and AIBN was 3 g:100 ml:6 g:9 g:0.2 g.

[0037] Example 3

[0038] This invention proposes a method for treating heavy metal industrial wastewater using chemical precipitation, comprising the following steps:

[0039] S1. Ferrous sulfate is added to the industrial wastewater containing heavy metals to chemically treat the heavy metal ions in the wastewater. Then, a reagent is added to the obtained supernatant to adjust the pH value to 9, a flocculant is added, and the mixture is stirred for 38 minutes and then filtered to obtain the filtrate. The weight of the flocculant is 0.1% of the weight of the industrial wastewater containing heavy metals. The flocculant is a mixture of polyacrylamide and polyferric sulfate in a weight ratio of 1:1.

[0040] S2. Add the composite adsorbent to the filtrate, stir for 70 minutes, and then filter. The weight of the composite adsorbent is 0.15% of the weight of the heavy metal-containing industrial wastewater in S1. The composite adsorbent is composed of activated carbon, modified carbon nanotubes, and diatomaceous earth, and the weight ratio of activated carbon, modified carbon nanotubes, and diatomaceous earth is 8:3:6.

[0041] The diatomite is 3-mercaptopropyltrimethoxysilane modified diatomite;

[0042] The preparation process of the modified carbon nanotubes includes the following steps: silane coupling agent KH-560 is mixed with toluene, carboxylated carbon nanotubes and triethylamine are added under stirring, and the mixture is heated to 118°C and stirred for 10 hours under nitrogen protection. After filtration, washing, and drying, grafted modified carbon nanotubes are obtained. 9-decen-1-amine is added to dimethylformamide, grafted modified carbon nanotubes are added, and the mixture is heated to 80°C and stirred for 5 hours under nitrogen protection. The product is washed and dried to obtain amine-modified carbon nanotubes. Amine-modified carbon nanotubes are added to ethyl acetate, 1,4-diamino-2,5-divinylbenzene and 5-thiol-1,2,4-triazol-3-allylthiourea are added, the mixture is stirred evenly, nitrogen is introduced, azobisisobutyronitrile is added, and the mixture is heated to 70°C and reacted for 30 hours under nitrogen protection. After post-treatment, the modified carbon nanotubes are obtained.

[0043] In the preparation of modified carbon nanotubes, the ratio of silane coupling agent KH-560, toluene, carboxylated carbon nanotubes, and triethylamine is 5ml:55ml:3.2g:0.14ml; the ratio of 9-decen-1-amine, dimethylformamide, and grafted modified carbon nanotubes is 9g:80ml:6g; and the ratio of amine-modified carbon nanotubes, ethyl acetate, 1,4-diamino-2,5-divinylbenzene, 5-thiol-1,2,4-triazol-3-allylthiourea, and azobisisobutyronitrile is 2g:100ml:8g:5g:0.3g.

[0044] Example 4

[0045] This invention proposes a method for treating heavy metal industrial wastewater using chemical precipitation, comprising the following steps:

[0046] S1. Ferrous sulfate is added to the industrial wastewater containing heavy metals to chemically treat the heavy metal ions in the wastewater. Then, a reagent is added to the obtained supernatant to adjust the pH value to 9, and flocculant polyacrylamide is added. After stirring for 40 minutes, the mixture is filtered to obtain the filtrate. The weight of the flocculant polyacrylamide is 0.09% of the weight of the industrial wastewater containing heavy metals.

[0047] S2. Add composite adsorbent to the filtrate, stir for 60 minutes, and then filter.

[0048] The weight of the composite adsorbent is 0.22% of the weight of the heavy metal-containing industrial wastewater in S1.

[0049] The composite adsorbent is composed of activated carbon, modified carbon nanotubes and diatomaceous earth, and the weight ratio of activated carbon, modified carbon nanotubes and diatomaceous earth is 11:4:3.

[0050] The diatomite is 3-mercaptopropyltrimethoxysilane modified diatomite;

[0051] The preparation process of the modified carbon nanotubes includes the following steps: silane coupling agent KH-560 is mixed with toluene, carboxylated carbon nanotubes and triethylamine are added under stirring, and the mixture is heated to 110°C and stirred for 11 hours under nitrogen protection. After filtration, washing, and drying, grafted modified carbon nanotubes are obtained. 9-decen-1-amine is added to dimethylformamide, grafted modified carbon nanotubes are added, and the mixture is heated to 76°C and stirred for 7.5 hours under nitrogen protection. The product is washed and dried to obtain amine-modified carbon nanotubes. Amine-modified carbon nanotubes are added to ethyl acetate, 1,4-diamino-2,5-divinylbenzene and 5-thiol-1,2,4-triazol-3-allylthiourea are added, the mixture is stirred evenly, nitrogen is introduced, azobisisobutyronitrile is added, and the mixture is heated to 75°C and reacted for 20 hours under nitrogen protection. After post-treatment, the modified carbon nanotubes are obtained.

[0052] In the preparation of modified carbon nanotubes, the mass-to-volume ratio of silane coupling agent KH-560, toluene, carboxylated carbon nanotubes, and triethylamine was 4.5 ml: 57 ml: 4 g: 0.15 ml; the mass-to-volume ratio of 9-decen-1-amine, dimethylformamide, and grafted modified carbon nanotubes was 7 g: 85 ml: 11 g; and the mass-to-volume ratio of amine-modified carbon nanotubes, ethyl acetate, 1,4-diamino-2,5-divinylbenzene, 5-thiol-1,2,4-triazol-3-allylthiourea, and azobisisobutyronitrile was 2.7 g: 100 ml: 7 g: 8 g: 0.27 g.

[0053] Example 5

[0054] This invention proposes a method for treating heavy metal industrial wastewater using chemical precipitation, comprising the following steps:

[0055] S1. Ferrous sulfate is added to the industrial wastewater containing heavy metals to chemically treat the heavy metal ions in the wastewater. Then, a reagent is added to the obtained supernatant to adjust the pH value to 10, a flocculant is added, and the mixture is stirred for 43 minutes and then filtered to obtain the filtrate. The weight of the flocculant is 0.09% of the weight of the industrial wastewater containing heavy metals. The flocculant is polyacrylamide.

[0056] S2. Add composite adsorbent to the filtrate, stir for 65 minutes, and then filter.

[0057] The composite adsorbent is composed of activated carbon, modified carbon nanotubes and diatomaceous earth, and the weight ratio of activated carbon, modified carbon nanotubes and diatomaceous earth is 9:4:5.

[0058] The weight of the composite adsorbent is 0.23% of the weight of the heavy metal-containing industrial wastewater in S1;

[0059] The diatomite is 3-mercaptopropyltrimethoxysilane modified diatomite;

[0060] The preparation process of the modified carbon nanotubes includes the following steps: silane coupling agent KH-560 is mixed with toluene, carboxylated carbon nanotubes and triethylamine are added under stirring, and the mixture is heated to 108°C and stirred for 12 hours under nitrogen protection. After filtration, washing, and drying, grafted modified carbon nanotubes are obtained. 9-decen-1-amine is added to dimethylformamide, grafted modified carbon nanotubes are added, and the mixture is heated to 77°C and stirred for 6.8 hours under nitrogen protection. The product is washed and dried to obtain amine-modified carbon nanotubes. Amine-modified carbon nanotubes are added to ethyl acetate, 1,4-diamino-2,5-divinylbenzene and 5-thiol-1,2,4-triazol-3-allylthiourea are added, the mixture is stirred evenly, nitrogen is introduced, azobisisobutyronitrile is added, and the mixture is heated to 73°C and reacted for 25 hours under nitrogen protection. After post-treatment, the modified carbon nanotubes are obtained.

[0061] In the preparation of modified carbon nanotubes, the mass-to-volume ratio of silane coupling agent KH-560, toluene, carboxylated carbon nanotubes, and triethylamine was 4.8 ml: 55 ml: 4.3 g: 0.17 ml; the mass-to-volume ratio of 9-decen-1-amine, dimethylformamide, and grafted modified carbon nanotubes was 7 g: 85 ml: 11 g; and the mass-to-volume ratio of amine-modified carbon nanotubes, ethyl acetate, 1,4-diamino-2,5-divinylbenzene, 5-thiol-1,2,4-triazol-3-allylthiourea, and azobisisobutyronitrile was 2 g: 100 ml: 7 g: 6 g: 0.29 g.

[0062] Comparative Example 1

[0063] The only difference from Example 4 is that in S2, the composite adsorbent is a mixture of activated carbon and diatomaceous earth, and does not contain the modified carbon nanotubes of Example 4.

[0064] Comparative Example 2

[0065] The only difference from Example 4 is that in S2, the adsorbent used consists only of modified carbon nanotubes and does not contain activated carbon or diatomaceous earth.

[0066] Comparative Example 3

[0067] The only difference from Example 4 is that in S2, the adsorbent used is a mixture of activated carbon, unmodified carbon nanotubes and diatomaceous earth.

[0068] Comparative Example 4

[0069] The only difference from Example 4 is that in S2, the adsorbent used is a mixture of activated carbon, carboxylated carbon nanotubes and diatomaceous earth.

[0070] Comparative Example 5

[0071] The only difference from Example 4 is that in S2, the preparation process of the modified carbon nanotubes includes the following steps: mixing silane coupling agent KH-560 with toluene, adding carboxylated carbon nanotubes and triethylamine under stirring, heating to 110°C and stirring for 11 hours under nitrogen protection, and then filtering, washing and drying.

[0072] In Examples 1-5 and Comparative Examples 1-5, the wastewater containing lead (65 mg / L), copper (110 mg / L), manganese (51 mg / L), and nickel (70.7 mg / L) was used as the treatment target.

[0073] The effluent treated in Examples 1-5 had lead concentrations ≤0.007 mg / L, copper concentrations ≤0.1 mg / L, manganese concentrations ≤0.036 mg / L, and nickel concentrations ≤0.01 mg / L.

[0074] The effluent from the treatment of Comparative Examples 1-5 had lead concentrations ≥0.029 mg / L, copper concentrations ≥0.37 mg / L, manganese concentrations ≥0.24 mg / L, and nickel concentrations ≥0.036 mg / L.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for treating heavy metal industrial wastewater containing a chemical precipitation method, characterized by, The method comprises the following steps: S1, adding ferrous sulfate into the heavy metal industrial wastewater to perform chemical treatment on the heavy metal ions in the wastewater, then adding a reagent into the obtained supernatant to adjust the pH value to 9-10, adding a flocculant, stirring and filtering to obtain a filtrate; S2, adding a composite adsorbent into the filtrate, stirring and filtering; wherein the composite adsorbent is mixed by activated carbon, modified carbon nanotube and diatomite; In S2, the preparation process of the modified carbon nanotube comprises the following steps: mixing silane coupling agent KH-560 with toluene, adding carboxylated carbon nanotube and triethylamine under stirring, heating to 105-120 DEG C under the protection of nitrogen and stirring for 9-13 h, filtering, washing, drying to obtain grafted modified carbon nanotube; adding 9-decene-1-amine into dimethylformamide, adding grafted modified carbon nanotube, heating to 70-80 DEG C under the protection of nitrogen and stirring for 5-10 h, washing and drying the product to obtain amine modified carbon nanotube; adding amine modified carbon nanotube into ethyl acetate, adding 1,4-diamino-2,5-divinylbenzene and 5-thiol-1,2,4-triazole-3-allyl thiourea, stirring uniformly, introducing nitrogen, adding azobisisobutyronitrile, heating to 70-75 DEG C under the protection of nitrogen and reacting for 20-30 h, and post-treatment to obtain the modified carbon nanotube.

2. The heavy metal industrial wastewater treatment method comprising the chemical precipitation method according to claim 1, characterized by, In S1, the stirring time is 35-50 min.

3. The heavy metal industrial wastewater treatment method comprising the chemical precipitation method according to claim 1, characterized by, In S1, the weight of the flocculant is 0.08-0.11% of the weight of the heavy metal industrial wastewater; and the flocculant is a mixture of one or more of polyacrylamide, polyferric sulfate and polyethyleneimine.

4. The heavy metal industrial wastewater treatment method comprising the chemical precipitation method according to claim 1, characterized by, In S2, the stirring time is 55-70 min.

5. The heavy metal industrial wastewater treatment method comprising the chemical precipitation method according to claim 1, characterized by, In S2, the weight of the composite adsorbent is 0.15-0.28% of the weight of the heavy metal industrial wastewater in S1.

6. The heavy metal industrial wastewater treatment method comprising the chemical precipitation method according to claim 1, characterized by, In S2, the weight ratio of the activated carbon, the modified carbon nanotube and the diatomite is 7-12:1-5:2-6; and the diatomite is 3-mercaptopropyltrimethoxysilane modified diatomite.

7. The heavy metal industrial wastewater treatment method comprising the chemical precipitation method according to claim 6, characterized by, In the preparation process of the modified carbon nanotube, the mass-volume ratio of silane coupling agent KH-560, toluene, carboxylated carbon nanotube and triethylamine is 4-6 ml:50-60 ml:3-5 g:0.13-0.18 ml.

8. The method of treating heavy metal industrial wastewater containing a chemical precipitation process according to claim 7, characterized by, In the preparation process of the modified carbon nanotube, the mass-volume ratio of 9-decene-1-amine, dimethylformamide and grafted modified carbon nanotube is 5.5-9 g:75-100 ml:6-13 g.

9. The heavy metal industrial wastewater treatment method comprising the chemical precipitation method according to claim 7, characterized by, In the preparation process of the modified carbon nanotube, the weight-volume ratio of amine modified carbon nanotube, ethyl acetate, 1,4-diamino-2,5-divinylbenzene, 5-thiol-1,2,4-triazole-3-allyl thiourea and azobisisobutyronitrile is 1.5-3 g:100 ml:6-8.9 g:4-9 g:0.2-0.31 g.