A heavy metal contaminated soil remediation agent and preparation method thereof

Abstract

The present invention relates to the field of soil treatment agents, and in particular to a heavy metal contaminated soil remediation agent and a preparation method thereof. The heavy metal contaminated soil remediation agent, in parts by mass, comprises the following raw materials: 40-60 parts of biochar, 15-25 parts of filler powder, 10-20 parts of phosphates, 3-8 parts of microbial agents, 5-10 parts of mineral clay, 10-15 parts of modification aids, 3-8 parts of humic acids, and 3-5 parts of inorganic metal salts. The remediation agent prepared by the present invention not only has excellent soil heavy metal contamination remediation effects, but also maintains good stability in the long term and will not release heavy metals into the environment over time. Secondly, it can further enhance the soil improvement ability and water retention effect, thereby achieving soil conditioning applications.

Description

Technical Field

[0001] The present invention relates to the field of soil treatment agents, and in particular to a heavy metal contaminated soil remediation treatment agent and a preparation method thereof. Background Art

[0002] With the acceleration of industrialization and urbanization, heavy metal contamination of soil has become a serious environmental problem. Heavy metals in soil, such as lead, cadmium, mercury, and chromium, are not only difficult to degrade but also accumulate through the food chain, ultimately impacting human health and ecosystem stability. Therefore, the development of highly effective remediation agents for heavy metal-contaminated soil is crucial for environmental protection and public health.

[0003] Currently, the main remediation methods for heavy metal-contaminated soil include physical remediation, chemical remediation, and biological remediation. Among these, stabilization / solidification technology within chemical remediation is widely used due to its ease of operation and relatively low cost. This technology primarily involves adding specific chemical agents, such as lime, zeolite, phosphates, and organic materials, to contaminated soil to convert heavy metals into insoluble compounds or precipitates, thereby reducing their mobility and bioavailability in the environment. Furthermore, some studies have explored the use of biochar as a remediation material, which not only improves soil structure and fertility but also enhances the soil's ability to adsorb heavy metals.

[0004] However, existing heavy metal contaminated soil remediation agents and methods have several shortcomings. For example, some remediation agents are simply mixed with different ingredients before use, lacking a scientific and reasonable formula design, resulting in unstable remediation effects; poor long-term effectiveness. Some remediation agents can effectively fix heavy metals in the short term, but have poor long-term stability. Over time, the fixed heavy metals may be released back into the environment; soil improvement performance is low, and they cannot effectively improve soil capacity while treating heavy metal pollution.

[0005] Therefore, in order to effectively solve the above problems, the present invention provides a heavy metal contaminated soil remediation agent and a preparation method thereof. The remediation agent prepared by the present invention not only has excellent soil heavy metal pollution remediation effect, but also can maintain good stability in a long-term state and will not release heavy metals into the environment again over time. Secondly, it can further improve the ability to improve the soil and improve the water retention effect, thereby realizing soil conditioning applications. Summary of the Invention

[0006] In order to solve the above problems, the first aspect of the present invention provides a heavy metal contaminated soil remediation agent, which comprises the following raw materials, in parts by mass: 40-60 parts of biochar, 15-25 parts of filler powder, 10-20 parts of phosphates, 3-8 parts of microbial agents, 5-10 parts of mineral clay, 10-15 parts of modification additives, 3-8 parts of humic acids, and 3-5 parts of inorganic metal salts.

[0007] As a preferred solution, the mass ratio of the biochar, filler powder and phosphates is (45-55): (18-22): (12-16).

[0008] As a preferred solution, the mass ratio of the biochar, filler powder and phosphates is (48-52): (18-20): (14-16).

[0009] As a preferred solution, the biochar is at least one of rice husk biochar, corn straw biochar, sawdust biochar, bamboo biochar and coconut shell biochar.

[0010] As a preferred solution, the biochar is rice husk biochar or coconut shell biochar.

[0011] As a preferred solution, the biochar is rice husk biochar.

[0012] As a preferred solution, the filler powder is at least one of limestone powder, magnesite powder and dolomite powder.

[0013] As a preferred solution, the filling powder is limestone powder.

[0014] As a preferred solution, the average particle size of the filling powder is 0.05 to 0.15 μm.

[0015] As a preferred solution, the phosphate is at least one of superphosphate, monoammonium phosphate, diammonium phosphate and calcium magnesium phosphate.

[0016] As a preferred solution, the phosphate is superphosphate or calcium magnesium phosphate.

[0017] As a preferred solution, the phosphate is superphosphate.

[0018] As a preferred solution, the microbial agent is an EM composite agent.

[0019] As a preferred solution, the mineral clay is at least one of montmorillonite, kaolin, illite, bentonite, chlorite and sepiolite.

[0020] As a preferred solution, the mineral clay is a combination of montmorillonite and kaolin.

[0021] As a preferred solution, the mass ratio of montmorillonite to kaolin is (4-5): (1-1.5).

[0022] As a preferred solution, the modification aid is a modified adhesive.

[0023] As a preferred solution, the preparation method of the modified adhesive specifically includes the following steps: S1: adding amylose and 2-acrylamido-2-methylpropanesulfonic acid to deionized water and mixing evenly, then adding nitrous acid, and stirring at 0-5°C for 40-80 minutes; S2: after evacuating to a vacuum, adding methacrylic acid, N-vinyl pyrrolidone and acrylamide to the S1 mixture, then adding ammonia water to adjust the pH to 6.5-7, and adding potassium persulfate; S3: stirring and keeping warm at 70-80°C and 60-80 rpm for 4-5 hours. After the reaction is completed, naturally cooling to 40-45°C and keeping warm for 2-3 hours. After the insulation is completed, naturally cooling to room temperature and storing overnight. The product is obtained after completion.

[0024] As a preferred solution, the amylose content is ≥75%.

[0025] As a preferred solution, the mass ratio of the amylose, 2-acrylamido-2-methylpropanesulfonic acid, methacrylic acid, N-vinyl pyrrolidone and acrylamide is (3-4): (0.6-1): (1-2): (0.1-0.5): (23-28).

[0026] As a preferred solution, the mass ratio of the amylose, 2-acrylamido-2-methylpropanesulfonic acid, methacrylic acid, N-vinyl pyrrolidone and acrylamide is (3.2-3.5): (0.7-0.8): (1.2-1.5): (0.2-0.3): (24-26).

[0027] As a preferred solution, the humic acid is at least one of humic acid, sodium humate, potassium humate, ammonium humate and humic acid.

[0028] As a preferred solution, the humic acid is ammonium humate.

[0029] As a preferred solution, the inorganic metal salt is at least one of aluminum sulfate, ferrous sulfate, potassium aluminum sulfate, and calcium chloride.

[0030] As a preferred solution, the inorganic metal salt is a combination of potassium aluminum sulfate and calcium chloride.

[0031] As a preferred solution, the mass ratio of potassium aluminum sulfate to calcium chloride is (1.6-2):(7-8).

[0032] As a preferred solution, the mass ratio of the filler powder, mineral clay and modification additive is (18-22): (6-8): (12-15).

[0033] As a preferred solution, the mass ratio of the filler powder, mineral clay and modification additive is (18-20): (6-7): (13-14).

[0034] The second aspect of the present invention provides a preparation method of the above-mentioned heavy metal contaminated soil remediation agent, which specifically includes the following steps: S1: adding biochar to a container and pyrolyzing it at 450-650°C for 3-4 hours, then mixing the filler powder with the biochar, stirring at a low speed of 30-40 rpm to avoid dust, and obtaining a solid mixture; S2: adding the microbial agent to the solid mixture under sterile conditions, and then gently stirring to ensure uniform distribution, the stirring temperature is 20-25°C, and the humidity is 40-60%; S3: adding the remaining materials and mixing evenly, and placing them in a sealed container for 24-30 hours. After completion, packaging is completed.

[0035] The present invention has the beneficial effects:

[0036] 1. The heavy metal contaminated soil remediation agent provided in the present invention not only has excellent soil heavy metal pollution remediation effect, but also can maintain good stability in the long term and will not release heavy metals into the environment again over time, thereby extending the shelf life of soil heavy metal pollution treatment, reducing the probability of secondary remediation treatment, and significantly reducing soil remediation costs.

[0037] 2. The heavy metal contaminated soil remediation agent provided in the present invention can further enhance the soil improvement ability and improve the water retention effect. During long-term use, it can improve the soil water retention effect, thereby achieving the functional combination of heavy metal pollution and soil conditioning.

[0038] 3. The present invention provides a heavy metal contaminated soil remediation agent, in which the added modified adhesive can form a molecular network system of a certain degree and strength in the system. The existence of this system can serve as an excellent carrier to promote the treatment effect of the remediation agent on heavy metals, and it can swell by attracting water, thereby achieving a wrapping effect on the contents of the system during long-term use, thereby greatly slowing down the phenomenon of heavy metal re-release, and its water-attracting effect can help improve the absorption and retention of water in the soil, thereby enhancing the water retention effect of the soil. DETAILED DESCRIPTION

[0039] The following text further describes and illustrates the technical solutions described in the above summary of the present invention through specific implementation schemes. The following examples are merely practical examples used to illustrate and explain the technical solutions described in this specification and should not limit the scope of the claims to be protected by this invention. All technical products based on the technical solutions described in this summary of the present invention are intended to be covered by the scope of protection of this invention.

[0040] In the following examples, unless otherwise specified, the raw materials are all commercially available products or can be prepared by methods well known to those skilled in the art.

[0041] Example 1

[0042] Example 1 The first aspect provides a heavy metal contaminated soil remediation agent, which comprises the following raw materials, in parts by mass: 52.5 parts of biochar, 18.8 parts of filler powder, 14.6 parts of phosphates, 4.5 parts of microbial agents, 6.8 parts of mineral clay, 13.6 parts of modification additives, 5.8 parts of humic acids, and 4.5 parts of inorganic metal salts.

[0043] The biochar was rice husk biochar, which was purchased from Henan Lize Environmental Protection Technology Co., Ltd. in China and was a 20 mm grade product.

[0044] The filling powder is limestone powder with an average particle size of 0.1 μm.

[0045] The phosphate is superphosphate.

[0046] The microbial agent is an EM compound microbial agent, which was purchased from Henan Jiufeng Water Treatment Co., Ltd. in China.

[0047] The mineral clay is a combination of montmorillonite and kaolin, with a mass ratio of 4.3:1.2.

[0048] The modification auxiliary agent is a modified adhesive; the preparation method of the modified adhesive specifically includes the following steps, calculated by mass: S1: adding 3.6 parts of amylose and 0.75 parts of 2-acrylamido-2-methylpropanesulfonic acid to 200 parts of deionized water and mixing evenly, then adding 0.5 parts of nitrous acid, and stirring at 0-5°C for 60 minutes; S2: after evacuating to vacuum, adding 1.3 parts of methacrylic acid, 0.26 parts of N-vinyl pyrrolidone and 25.5 parts of acrylamide to the S1 mixture, then adding ammonia water to adjust the pH to 6.5, and adding 0.16 parts of potassium persulfate; S3: stirring and keeping warm at 75°C and 60 rpm for 4.5 hours, after the reaction is completed, naturally cooling to 40°C and keeping warm for 3 hours, and after the insulation is completed, naturally cooling to room temperature and storing overnight, and the product is obtained after completion.

[0049] The amylose had an amylose content of ≥75% and was purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd., China.

[0050] The humic acid is ammonium humate; the inorganic metal salt is a combination of potassium aluminum sulfate and calcium chloride, and the mass ratio of the two is 1.8:7.2.

[0051] The second aspect of this embodiment provides a preparation method of the above-mentioned heavy metal contaminated soil remediation agent, which specifically includes the following steps: S1: adding biochar to a container and pyrolyzing it at 500°C for 4 hours, then mixing the filler powder with the biochar, stirring at a low speed of 40 rpm to avoid dust, and obtaining a solid mixture; S2: adding the microbial agent to the solid mixture under sterile conditions, and then gently stirring to ensure uniform distribution, the stirring temperature is 24°C, and the humidity is 55%; S3: adding the remaining materials and mixing them evenly, and then placing them in a sealed container for 30 hours. After completion, packaging is completed.

[0052] Example 2

[0053] The specific implementation of this embodiment is basically the same as that of Example 1, except that: the raw materials of the heavy metal contaminated soil remediation agent, in parts by mass, are: 46.2 parts of biochar, 21.8 parts of filler powder, 12 parts of phosphates, 4.5 parts of microbial agents, 8 parts of mineral clay, 14.6 parts of modification additives, 4.8 parts of humic acids, and 5 parts of inorganic metal salts.

[0054] Comparative Example 1

[0055] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the raw materials of the heavy metal contaminated soil remediation agent, in parts by mass, are: 52.5 parts of biochar, 18.8 parts of filler powder, 14.6 parts of phosphates, 4.5 parts of microbial agents, 6.8 parts of mineral clay, 5.5 parts of modification additives, 5.8 parts of humic acids, and 4.5 parts of inorganic metal salts.

[0056] Comparative Example 2

[0057] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the heavy metal contaminated soil remediation treatment agent, in parts by mass, the raw materials are: 52.5 parts of biochar, 18.8 parts of filler powder, 14.6 parts of phosphates, 4.5 parts of microbial agents, 6.8 parts of mineral clay, 26.8 parts of modification additives, 5.8 parts of humic acids, and 4.5 parts of inorganic metal salts.

[0058] Comparative Example 3

[0059] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified adhesive specifically includes the following steps, calculated in parts by mass: S1: adding 5.5 parts of amylose and 0.15 parts of 2-acrylamido-2-methylpropanesulfonic acid to 200 parts of deionized water and mixing evenly, then adding 0.5 parts of nitrous acid, and stirring at 0-5°C for 60 minutes; S2: after evacuating to a vacuum, adding 1.3 parts of methacrylic acid, 0.26 parts of N-vinyl pyrrolidone and 25.5 parts of acrylamide to the S1 mixture, then adding ammonia water to adjust the pH to 6.5, and adding 0.16 parts of potassium persulfate; S3: stirring and keeping warm at 75°C and 60 rpm for 4.5 hours, after the reaction is completed, naturally cooling to 40°C and keeping warm for 3 hours, and then naturally cooling to room temperature after the insulation is completed, and storing overnight, and the product is obtained after completion.

[0060] Comparative Example 4

[0061] The specific implementation of this comparative example is basically the same as that of Example 1, except that: the preparation method of the modified adhesive specifically includes the following steps, calculated in parts by mass: S1: adding 3.6 parts of amylose and 0.75 parts of 2-acrylamido-2-methylpropanesulfonic acid to 200 parts of deionized water and mixing evenly, then adding 0.5 parts of nitrous acid, and stirring at 0-5°C for 60 minutes; S2: after evacuating to a vacuum, adding 4.5 parts of methacrylic acid, 0.1 parts of N-vinyl pyrrolidone and 15.6 parts of acrylamide to the S1 mixture, then adding ammonia water to adjust the pH to 6.5, and adding 0.16 parts of potassium persulfate; S3: stirring and keeping warm at 75°C and 60 rpm for 4.5 hours, after the reaction is completed, naturally cooling to 40°C and keeping warm for 3 hours, and then naturally cooling to room temperature after the insulation is completed, and storing overnight, and the product is obtained after completion.

[0062] Comparative Example 5

[0063] The specific implementation of this comparative example is basically the same as that of Example 1, except that the filler powder is limestone powder with an average particle size of 0.5 μm.

[0064] Comparative Example 6

[0065] The specific implementation of this comparative example is basically the same as that of Example 1, except that the mineral clay is a combination of montmorillonite and kaolin, and the mass ratio of the two is 9:1.

[0066] Performance evaluation

[0067] Water retention effect test: A cabbage planting plot in Shouguang City, Shandong Province was divided into 8 2-mu areas. Each of the 8 plots was plowed 35 cm, and the soil remediation treatment agents prepared in the above embodiments and comparative examples were applied at a rate of 60 kg / hectare. The soil was then plowed and buried for mixing. After 14 days, the water retention rate of the soil was tested. The measured soil water retention rate values ​​were averaged over 10 tests and recorded in Table 1.

[0068] Heavy metal treatment effect: The soil remediation treatment agent prepared in the embodiment and the comparative example was applied to heavy metal contaminated soil at a spreading rate of 60 kg / hectare. After spreading, a small amount of water was sprayed on the surface. Before treatment, the pH of the soil was 6.4, and the contents of Pb, Cd, and Cr were 817 mg / kg, 7.1 mg / kg, and 1010 mg / kg, respectively. After 14 days, the removal rate of the corresponding heavy metals was detected, and the test values ​​were recorded in Table 1 as the average of 10 tests.

[0069] Table 1 Performance test results

[0070]

[0071]

[0072] It can be seen from the examples and comparative examples of the present invention and the data results in Table 1 that Examples 1 and 2 of the present invention have obvious advantages over Comparative Examples 1 to 6 in terms of water retention effect and heavy metal treatment. This is mainly due to the combined effect of the modified binder added as defined in the present invention and other matching schemes. Comparative Examples 1 to 6 did not adopt the technical solution defined in the present invention, resulting in obvious disadvantages in the above performance tests. This further proves the necessity of the technical solution defined in the present invention for the technical effects of the present invention and solving technical problems.

Claims

1. A heavy metal contaminated soil remediation agent, characterized by: The raw materials are as follows: 40-60 parts of biochar, 15-25 parts of filler powder, 10-20 parts of phosphates, 3-8 parts of microbial agents, 5-10 parts of mineral clay, 10-15 parts of modification additives, 3-8 parts of humic acids, and 3-5 parts of inorganic metal salts. The biochar is at least one of rice husk biochar, corn straw biochar, sawdust biochar, bamboo biochar and coconut shell biochar; The filling powder is at least one of limestone powder, magnesia powder and dolomite powder; The phosphate is at least one of superphosphate, monoammonium phosphate, diammonium phosphate and calcium magnesium phosphate; The modification aid is a modified adhesive, and the preparation method includes: S1: adding amylose and 2-acrylamido-2-methylpropanesulfonic acid to deionized water and mixing evenly, then adding nitrous acid, and stirring at 0-5°C for 40-80 minutes; S2: after evacuating to a vacuum, adding methacrylic acid, N-vinyl pyrrolidone and acrylamide to the S1 mixture, then adding ammonia water to adjust the pH to 6.5-7, and adding potassium persulfate; S3: stirring and keeping warm at 70-80°C and 60-80 rpm for 4-5 hours, after the reaction is completed, naturally cooling to 40-45°C and keeping warm for 2-3 hours, and after the keeping warm is completed, naturally cooling to room temperature and storing overnight, and the product is obtained after completion; The linear content of amylose is ≥75%; The mass ratio of amylose, 2-acrylamido-2-methylpropanesulfonic acid, methacrylic acid, N-vinyl pyrrolidone and acrylamide is (3~4): (0.6~1): (1~2): (0.1~0.5): (23~28); The mass ratio of biochar, filler powder and phosphate is (45~55): (18~22): (12~16); The mass ratio of filler powder, mineral clay and modification additive is (18~22): (6~8): (12~15).

2. The heavy metal contaminated soil remediation agent according to claim 1, characterized in that: The microbial agent is an EM composite agent.

3. The heavy metal contaminated soil remediation agent according to claim 2, characterized in that: The mineral clay is at least one of montmorillonite, kaolin, illite, bentonite, chlorite and sepiolite.

4. The heavy metal contaminated soil remediation agent according to claim 3, characterized in that: The humic acid is at least one of humic acid, sodium humate, potassium humate, ammonium humate and humic acid.

5. The heavy metal contaminated soil remediation agent according to claim 4, characterized in that: The inorganic metal salt is at least one of aluminum sulfate, ferrous sulfate, potassium aluminum sulfate, and calcium chloride.

6. The heavy metal contaminated soil remediation agent according to claim 5, characterized in that: The inorganic metal salt is a combination of potassium aluminum sulfate and calcium chloride.

7. The heavy metal contaminated soil remediation agent according to claim 6, characterized in that: The mass ratio of the potassium aluminum sulfate to calcium chloride is (1.6-2): (7-8).

8. A method for preparing the heavy metal contaminated soil remediation agent according to any one of claims 1 to 7, characterized in that: The specific steps include: S1: Add biochar to the container and pyrolyze it at 450~650℃ for 3~4h. Then mix the filler powder with the biochar and stir at a low speed of 30~40rpm to avoid dust to obtain a solid mixture; S2: Add the microbial agent to the solid mixture under sterile conditions, and then gently stir to ensure uniform distribution. The stirring temperature is 20~25℃ and the humidity is 40~60%; S3: Add the remaining materials and mix evenly. Place in a sealed container for 24~30h. After completion, package it.

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