Heavy metal contaminated soil remediation treatment agent and preparation method thereof

Abstract

The invention relates to the field of soil treatment agents, in particular to a heavy metal contaminated soil remediation treatment agent and a preparation method thereof. The heavy metal contaminated soil remediation treatment agent is prepared from the following raw materials in parts by mass: 40-60 parts of biochar, 15-25 parts of filling powder, 10-20 parts of phosphates, 3-8 parts of a microbial agent, 5-10 parts of mineral clay, 10-15 parts of a modification additive, 3-8 parts of humic acids and 3-5 parts of inorganic metal salt. The prepared remediation treatment agent not only can have an excellent soil heavy metal pollution remediation effect, but also can keep good stability in a long-term state, does not release heavy metal into the environment again as time goes on, and can further improve the soil improvement capacity and improve the water retention effect, so that the remediation treatment agent has a good application prospect. Further, the soil conditioning application is realized.

Description

Technical Field

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

[0002] With the acceleration of industrialization and urbanization, heavy metal pollution in 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 affecting human health and the stability of the ecosystem. Therefore, the development of efficient heavy metal contaminated soil remediation agents is crucial for environmental protection and public health.

[0003] At present, the main remediation methods for heavy metal contaminated soil include physical remediation, chemical remediation and biological remediation. Among them, the stabilization / solidification technology in chemical remediation is widely used due to its simple operation and relatively low cost. This technology mainly adds specific chemical agents such as lime, zeolite, phosphate, organic materials, etc. to the contaminated soil to make heavy metals form insoluble compounds or precipitation, thereby reducing their mobility and bioavailability in the environment. In addition, some studies have also explored the use of biochar as a remediation material, which can not only improve soil structure and fertility, but also enhance the soil's ability to adsorb heavy metals.

[0004] However, existing heavy metal contaminated soil remediation treatment 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 small, and soil capacity cannot be effectively improved 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, improve the water retention effect, and then realize the conditioning application of the soil. 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, by weight: 40 to 60 parts of biochar, 15 to 25 parts of filler powder, 10 to 20 parts of phosphates, 3 to 8 parts of microbial agents, 5 to 10 parts of mineral clay, 10 to 15 parts of modification aids, 3 to 8 parts of humic acids, and 3 to 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 filling powder is at least one of limestone powder, magnesia 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 0.05-0.15 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 60-80rpm 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 straight chain content of the straight chain starch 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 aid is (18-22): (6-8): (12-15).

[0033] As a preferred solution, the mass ratio of the filler powder, mineral clay and modification aid 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 treatment agent, which specifically includes the following steps: S1: add biochar into a container and pyrolyze it at 450-650°C for 3-4 hours, then mix the filler powder with the biochar, stir at a low speed of 30-40rpm to avoid dust, and 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°C, and the humidity is 40-60%; S3: add the remaining materials and mix evenly, then place in a sealed container for 24-30 hours, and package after completion.

[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 an 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, thereby extending the shelf life of soil heavy metal pollution treatment, reducing the probability of secondary remediation treatment, and greatly reducing soil treatment costs.

[0037] 2. The heavy metal contaminated soil remediation agent provided in the present invention can further improve the soil improvement ability and water retention effect. It can improve the soil water retention effect during long-term use, 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-drawing 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 technical solutions in the above invention contents of the present invention will be further described and demonstrated in the form of specific implementation schemes below. The following embodiments are only practical examples used to illustrate and explain the contents of the technical solutions in the specification and should not limit the scope of the claims to be protected by the present invention. All technical products based on the technical solutions described in the invention contents of the present invention should be included in the scope to be protected by the present 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, in which the raw materials are, 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, purchased from Henan Li Ze Environmental Protection Technology Co., Ltd., China, with a grade of 20 mm.

[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 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 modified 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 60rpm for 4.5 hours, after the reaction is completed, naturally cooling to 40°C and keeping warm for 3 hours, after the insulation is completed, naturally cooling to room temperature, and storing overnight, the mixture is obtained after completion.

[0049] The straight chain content of amylose was ≥75%, and the product of corresponding specifications 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 the present embodiment provides a method for preparing the above-mentioned heavy metal contaminated soil remediation treatment agent, which specifically includes the following steps: S1: adding biochar into 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 40rpm 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 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 method 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 method 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, 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 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 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 60rpm for 4.5h, after the reaction is completed, naturally cooling to 40°C and keeping warm for 3h, and after the insulation is completed, naturally cooling to room temperature and storing overnight, the mixture 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 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 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 60rpm for 4.5h, after the reaction is completed, naturally cooling to 40°C and keeping warm for 3h, and after the insulation is completed, naturally cooling to room temperature and storing overnight, the mixture 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 filling 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: The cabbage planting plots in Shouguang City, Shandong Province were divided into 8 2-mu areas. The 8 plots were plowed 35 cm respectively, and the soil remediation treatment agents prepared in the above embodiments and comparative examples were spread respectively, with an application amount of 60 kg / hectare. After that, the soil was plowed and buried to mix evenly. After keeping it for 14 days, the water retention rate of the soil was tested. The measured soil water retention rate value was taken as the average value of 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 the soil contaminated by heavy metals at a spreading rate of 60 kg / hectare. After the spreading was completed, a small amount of water was sprayed on the surface. Before the treatment, the pH in 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 value was the average value of 10 tests and recorded in Table 1.

[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 adhesive added as specified in the present invention and other matching schemes. Comparative examples 1 to 6 did not adopt the technical scheme specified in the present invention, resulting in obvious disadvantages in the above performance tests, which further proves the necessity of the technical scheme specified in the present invention for the technical effect of the present invention and solving technical problems.

Claims

1. A heavy metal contaminated soil remediation agent, characterized in that: 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 aids, 3-8 parts of humic acid, 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; The preparation method of the modified adhesive specifically comprises 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 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 heat-insulating at 70-80°C and 60-80rpm for 4-5 hours, after the reaction is completed, naturally cooling to 40-45°C and heat-insulating for 2-3 hours, after the heat-insulating is completed, naturally cooling to room temperature, and storing overnight, and the mixture is obtained after completion; The straight chain content of the straight chain starch is ≥75%; The mass ratio of the straight-chain starch, 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).

2. The heavy metal contaminated soil remediation agent according to claim 1, characterized in that: The mass ratio of the biochar, filler powder and phosphates is (45-55):(18-22):(12-16).

3. The heavy metal contaminated soil remediation agent according to claim 2, characterized in that: The mass ratio of the filler powder, mineral clay and modification auxiliary agent is (18-22): (6-8): (12-15).

4. The heavy metal contaminated soil remediation agent according to claim 3, characterized in that: The microbial agent is an EM composite agent.

5. The heavy metal contaminated soil remediation agent according to claim 4, characterized in that: The mineral clay is at least one of montmorillonite, kaolin, illite, bentonite, chlorite and sepiolite.

6. The heavy metal contaminated soil remediation agent according to claim 5, characterized in that: The humic acid is at least one of humic acid, sodium humate, potassium humate, ammonium humate and humic acid.

7. The heavy metal contaminated soil remediation agent according to claim 6, characterized in that: The inorganic metal salt is at least one of aluminum sulfate, ferrous sulfate, potassium aluminum sulfate and calcium chloride.

8. The heavy metal contaminated soil remediation agent according to claim 7, characterized in that: The inorganic metal salt is a combination of potassium aluminum sulfate and calcium chloride.

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

10. A method for preparing a heavy metal contaminated soil remediation agent according to any one of claims 1 to 9, characterized in that: The specific steps include: S1: Add biochar into the container and pyrolyze it at 450-650℃ for 3-4h, then mix the filler powder with the biochar, stir at a low speed of 30-40rpm to avoid dust, and 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, then place in a sealed container for 24-30h. After completion, package it.

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