Soil heavy metal eluting agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of heavy metal soil remediation, and particularly discloses a soil heavy metal eluting agent and a preparation method and application thereof. The heavy metal soil eluting agent provided by the invention is prepared from the following components in parts by weight: 10 to 20 parts of maleic anhydride-itaconic acid copolymer, 10 to 15 parts of levulinic acid, 10 to 25 parts of heavy metal chelating agent, 0.2 to 3 parts of polyacrylamide, 0.1 to 2 parts of dispersing agent, 0.5 to 2 parts of penetrating agent and 50 to 80 parts of deionized water, wherein the heavy metal chelating agent is selected from one or more of aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and a carboxylate-sulfonate-acrylate terpolymer; the invention further provides a preparation method and application of the heavy metal soil eluting agent. The heavy metal soil eluting agent provided by the invention can be used for chelating and eluting heavy metal cations such as cadmium, chromium and lead in soil, so that remediation of the heavy metal soil is realized.

Description

Technical Field

[0001] The present application relates to the technical field of heavy metal soil remediation, and specifically to a soil heavy metal eluting agent and a preparation method and application thereof. Background Art

[0002] Excessive heavy metal content in soil has become a global environmental problem, especially in the agricultural field, which has seriously affected the yield and quality of crops, and thus threatened food safety and human health. The main reasons for excessive heavy metal content in farmland soil include soil acidification caused by long-term unreasonable fertilization, and exogenous heavy metal pollution caused by unreasonable resource development and industrial activities. These heavy metals will not only reduce soil productivity, but may also accumulate through the food chain, ultimately causing serious harm to human health. Therefore, it is particularly important to find effective methods for removing heavy metals from soil.

[0003] At present, one of the important methods for the treatment of heavy metal pollution in soil is leaching, that is, by injecting or infiltrating the leaching liquid into the soil, allowing it to flow through the soil layer to be treated, so as to dissolve, desorb, reverse complex and transfer the heavy metals in the soil solid phase from the soil to the soil liquid phase, and finally treat and reuse the soil liquid phase. However, the leaching efficiency of heavy metal leaching agents currently on the market is greatly affected by factors such as soil type, heavy metal type, and soil pH, making it difficult to achieve broad spectrum and high efficiency, so it cannot be promoted and used on a large scale; in addition, some leaching agents on the market may also cause secondary pollution to the soil.

[0004] Therefore, developing an efficient, economical, environmentally friendly, and broad-spectrum soil heavy metal eluting agent is of great significance for heavy metal soil treatment. Summary of the invention

[0005] In order to achieve efficient and large-scale treatment of heavy metal soil, the present application provides a soil heavy metal eluting agent and a preparation method and application thereof.

[0006] In the first aspect, the present application provides a soil heavy metal eluting agent, which adopts the following technical solution: A soil heavy metal eluting agent comprises the following components in parts by weight: 10-20 parts of maleic anhydride-itaconic acid copolymer, 10-15 parts of levulinic acid, 10-25 parts of heavy metal chelating agent, 0.2-3 parts of polyacrylamide, 0.1-2 parts of dispersant, 0.5-2 parts of penetrant and 50-80 parts of deionized water.

[0007] The present application provides an efficient soil heavy metal eluting agent, in which the levulinic acid in the eluting agent, as a low molecular weight organic acid, can quickly resolve carbonate-bound and iron-manganese oxide-form heavy metals in the soil into ionic and exchangeable states in a relatively short period of time, thereby facilitating chelation and elution. Maleic anhydride-itaconic acid copolymer contains abundant active functional groups such as peptide bonds, carboxyl groups and hydroxyl groups, which can effectively convert heavy metals in the form of iron-manganese oxides in the soil into exchangeable and ionic states, further enhancing the solubility and mobility of heavy metals; in addition, the carboxyl groups contained in the copolymer can efficiently chelate heavy metal cations such as cadmium, chromium, and lead, while releasing phosphate ions, activating the phosphate fertilizer fixed in the soil, and improving soil structure and fertility. Heavy metal chelators have a wide range of chelating abilities and stability for a variety of heavy metal ions such as cadmium, chromium, and lead, and can maintain excellent chelating effects even when the soil pH changes greatly. The addition of polyacrylamide can not only enhance the permeability of the eluent, but also synergize with the precipitated calcium and magnesium ions in the process of precipitating heavy metal ions, jointly promote the formation of soil aggregates, improve the structural stability and permeability of the soil, and further improve the leaching efficiency. In summary, the soil heavy metal eluent provided in this application can show superior performance in many aspects, and its leaching efficiency is not easily affected by factors such as soil type, heavy metal type, and soil pH. It can achieve efficient and large-scale management of heavy metal soils and has broad application prospects.

[0008] Optionally, the soil heavy metal eluting agent comprises the following components in parts by weight: 13-18 parts of maleic anhydride-itaconic acid copolymer, 12-15 parts of levulinic acid, 15-25 parts of heavy metal chelating agent, 0.2-3 parts of polyacrylamide, 0.1-2 parts of dispersant, 0.5-2 parts of penetrant and 50-80 parts of deionized water.

[0009] In the present application, maleic anhydride-itaconic acid copolymer, levulinic acid and heavy metal chelating agent are three main components, and their addition amount has a significant influence on the leaching effect of heavy metals. Through experimental research, it is found that by further controlling the addition amount of the three within the above range, the chelation and leaching efficiency of heavy metals in the obtained soil heavy metal eluting agent is higher.

[0010] In some embodiments, the weight parts of the maleic anhydride-itaconic acid copolymer can be 10-13 parts, 10-15 parts, 10-18 parts, 10-20 parts, 13-15 parts, 13-18 parts, 13-20 parts, 15-18 parts, 15-20 parts or 18-20 parts.

[0011] In a specific embodiment, the weight proportion of the maleic anhydride-itaconic acid copolymer may also be 10 parts, 13 parts, 15 parts, 18 parts or 20 parts.

[0012] In some embodiments, the weight parts of levulinic acid may be 10-12 parts or 12-15 parts.

[0013] In a specific embodiment, the weight parts of levulinic acid can also be 10 parts, 12 parts or 15 parts.

[0014] In some embodiments, the weight parts of the heavy metal chelating agent may be 10-15 parts, 10-20 parts, 10-25 parts, 15-20 parts, 15-25 parts or 20-25 parts.

[0015] In a specific embodiment, the weight portion of the heavy metal chelating agent may also be 10 parts, 15 parts, 20 parts or 25 parts.

[0016] Optionally, the heavy metal chelating agent is selected from one or more of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymers.

[0017] The heavy metal chelators of the present application are all made of environmentally friendly multifunctional biopolymer materials. The above materials can effectively improve the chelation efficiency of heavy metals in the soil, especially have good chelation effects on heavy metals such as cadmium, chromium, and lead. At the same time, these chelators are insensitive to changes in soil pH, have strong adaptability, and can improve the overall effect of soil heavy metal leaching.

[0018] Optionally, the heavy metal chelator is a mixture of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer.

[0019] Optionally, the weight ratio of the aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer is (1.8-2.2):(1.8-2.2):1.

[0020] Through experimental research, the present application found that by further selecting the above-mentioned weight ratio of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer as heavy metal chelating agents, the prepared soil heavy metal eluting agent has higher ion chelating ability and stronger adsorption ability, and the eluting effect on heavy metals in the soil is more significant.

[0021] In some embodiments, the weight ratio of the aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer can be (1.8-2):2:1, (2-2.2):2:1, 2:(1.8-2):1 or 2:(2-2.2):1.

[0022] In a specific embodiment, the weight ratio of the aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer can also be 1:1:1, 3:3:1, 1.8:2:1, 2:2:1, 2.2:2:1, 2:1.8:1 or 2:2.2:1.

[0023] Optionally, the molecular weight of the aspartic acid-glutamic acid polymerized amino acid is 8000-13000Da.

[0024] Optionally, the dispersant is NNO, and the penetrant is prepared by using block polyether Y-1, Aeo-9, sodium dodecylbenzene sulfonate and water.

[0025] In this application, NNO has excellent diffusivity and colloid protection properties. On the one hand, it can help heavy metal chelates and heavy metal ions to be evenly dispersed in the eluent; on the other hand, it can reduce the attraction between the chelate and the soil colloid to avoid precipitation or aggregation. The above-mentioned penetrant can make the eluent form a "matrix" water flow pattern in the soil, promote the uniform flow of the eluent, effectively alleviate the problem of soil water repulsion, and thus improve the elution efficiency.

[0026] Optionally, the weight ratio of the block polyether Y-1, Aeo-9, sodium dodecylbenzene sulfonate and water is (3.5-4.5):1:1:(3.5-4.5).

[0027] In a second aspect, the present application provides a method for preparing a soil heavy metal eluting agent.

[0028] A method for preparing a soil heavy metal eluting agent comprises the following steps: adding deionized water into a reaction kettle, heating to 40-50°C, and setting a stirring speed of 60-70rpm; then sequentially adding maleic anhydride-itaconic acid copolymer and levulinic acid, stirring for 5-10min, then adding a heavy metal chelating agent, stirring for 10-15min, then adding a dispersant and a penetrant, stirring for 5-10min, finally adding polyacrylamide, and continuously stirring for 15-20min, stopping stirring and heating, and cooling to obtain the soil heavy metal eluting agent.

[0029] In a second aspect, the present application provides an application of a soil heavy metal eluting agent in heavy metal soil improvement.

[0030] In summary, this application has the following beneficial effects: 1. The present application adopts maleic anhydride-itaconic acid copolymer, levulinic acid and heavy metal chelating agent to prepare a soil heavy metal eluting agent with broad spectrum and high efficiency. The soil heavy metal eluting agent can dissolve, desorb and reverse complex heavy metal ions such as cadmium, iron, chromium, lead and arsenic in the soil in a short time, so as to leach them out of the soil, realize the efficient treatment of heavy metal contaminated soil, and has a good prospect.

[0031] 2. The present application controls the weight proportions of maleic anhydride-itaconic acid copolymer, levulinic acid and heavy metal chelating agent within the following range: 13-18 parts of maleic anhydride-itaconic acid copolymer, 12-15 parts of levulinic acid and 15-25 parts of heavy metal chelating agent, so that the prepared soil heavy metal eluting agent has better use effect and higher removal efficiency of heavy metal ions in soil, and can make the removal rate of Cd ions in heavy metal soil reach more than 77.0%, the removal rate of Cr ions reach more than 70.0%, the removal rate of Pb ions reach more than 81.0%, the removal rate of Cu ions reach more than 84.0%, and the removal rate of Ni ions reach more than 72.0%.

[0032] 3. The present application further selects a mixture of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer as a heavy metal chelating agent, and controls the weight ratio of the three within the range of (1.8-2.2):(1.8-2.2):1. The obtained soil heavy metal eluting agent has a better use effect, and can make the Cd ion removal rate in the heavy metal soil reach more than 85.0%, the Cr ion removal rate reach more than 80.0%, the Pb ion removal rate reach more than 90.0%, the Cu ion removal rate reach more than 90.0%, and the Ni ion removal rate reach more than 80.0%. DETAILED DESCRIPTION

[0033] The present application provides a soil heavy metal eluting agent, comprising the following components in parts by weight: 10-20 parts of maleic anhydride-itaconic acid copolymer, 10-15 parts of levulinic acid, 10-25 parts of heavy metal chelating agent, 0.2-3 parts of polyacrylamide, 0.1-2 parts of dispersant, 0.5-2 parts of penetrant and 50-80 parts of deionized water; further, the soil heavy metal eluting agent comprises the following components in parts by weight: 13-18 parts of maleic anhydride-itaconic acid copolymer, 12-15 parts of levulinic acid, 15-25 parts of heavy metal chelating agent, 0.2-3 parts of polyacrylamide, 0.1-2 parts of dispersant, 0.5-2 parts of penetrant and 50-80 parts of deionized water.

[0034] Wherein, the heavy metal chelating agent is selected from one or more of aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer. Further, the heavy metal chelating agent is a mixture of aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer; further, the weight ratio of the aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer is (1.8-2.2):(1.8-2.2):1.

[0035] The preparation method of the penetrant is as follows: block polyether Y-1, Aeo-9, sodium dodecylbenzene sulfonate and water are mixed in a weight ratio of 4:1:1:4, and stirred evenly to obtain the penetrant.

[0036] The present application also provides a method for preparing the above-mentioned soil heavy metal eluent, comprising the following steps: adding deionized water into a reactor, heating to 40-50°C, and setting the stirring speed to 60-70rpm; then adding maleic anhydride-itaconic acid copolymer and levulinic acid in sequence, stirring for 5-10 minutes, then adding a heavy metal chelating agent, stirring for 10-15 minutes, then adding a dispersant and a penetrant, stirring for 5-10 minutes, and finally adding polyacrylamide, and continuing stirring for 15-20 minutes, stopping stirring and heating, and cooling to obtain a soil heavy metal eluent.

[0037] In the present application, maleic anhydride-itaconic acid copolymer was purchased from Shandong Xinrun Chemicals Co., Ltd.; the CAS number of levulinic acid is 123-76-2, the molecular weight of aspartic acid-glutamic acid polymerized amino acid is 10000Da, and the molar ratio of aspartic acid to glutamic acid is 1:1; the CAS number of iminodisuccinic acid is 144538-83-0; the carboxylate-sulfonate-acrylate terpolymer was purchased from Shandong Chint New Materials Co., Ltd.; polyacrylamide is cationic polyacrylamide, purchased from Shandong DeLan Chemical; the dispersant is NNO; the raw materials, reagents, solvents, etc. used in the present application can all be obtained commercially.

[0038] The present application is further described in detail below in conjunction with embodiments and performance testing experiments.

[0039] Examples 1-10 Examples 1-10 each provide a soil metal eluting agent.

[0040] The difference between the above embodiments is that the addition amount of each component in the soil metal eluting agent is shown in Table 1 below.

[0041] The preparation method of the soil eluent provided in Examples 1-10 comprises the following steps: adding 55 g of deionized water into a reactor, heating to 45°C, and setting the stirring speed to 65 rpm; then sequentially adding maleic anhydride-itaconic acid copolymer and levulinic acid, stirring for 5 minutes, then adding a heavy metal chelating agent, stirring for 10 minutes, then adding 1 g of a dispersant and 2 g of a penetrant, stirring for 5 minutes, and finally adding 0.5 g of polyacrylamide, and continuing stirring for 15 minutes, stopping stirring and heating, and cooling to obtain a soil heavy metal eluent.

[0042] In the above embodiment, the heavy metal chelating agent is aspartic acid-glutamic acid polymerized amino acid, the dispersant is NNO, and the preparation method of the penetrant is: block polyether Y-1, Aeo-9, sodium dodecylbenzene sulfonate and water are mixed in a weight ratio of 4:1:1:4, and stirred evenly to obtain the penetrant.

[0043] Table 1 Addition amount of some components in the soil washing agent provided in Examples 1-10 Examples 11-18 Examples 11-18 each provide a soil metal eluting agent.

[0044] The difference between the above embodiment and embodiment 3 is that the components and proportions of the heavy metal chelating agent are specifically shown in Table 2 below.

[0045] Table 2 Components and ratios of heavy metal chelating agents in Example 3 and Examples 11-18 Comparative Example 1 Comparative Example 1 provides a soil metal eluting agent.

[0046] The difference between the above embodiment and embodiment 3 is that the added amount of maleic anhydride-itaconic acid copolymer is 0.

[0047] Comparative Example 2 Comparative Example 2 provides a soil metal eluting agent.

[0048] The difference between the above embodiment and embodiment 3 is that the amount of levulinic acid added is 0.

[0049] Comparative Example 3 Comparative Example 3 provides a soil metal eluting agent.

[0050] The difference between the above embodiment and embodiment 3 is that the added amount of heavy metal chelating agent is 0.

[0051] Performance testing The soil metal eluting agents obtained in Examples 1-18 and Comparative Examples 1-3 were used to conduct elution experiments to test their performance. The results are shown in Table 4 below.

[0052] (1) First, a metal ion solution containing Cd, Cr, Pb, Ni and Cu was added to normal soil to prepare a heavy metal contaminated soil with a pH of 7.69 and metal contents as shown in Table 3 below.

[0053] Table 3 Concentrations of metal ions in heavy metal contaminated soil Heavy Metal Type Cd Cr Pb Ni Cu Content (mg / kg) 4.85 134.6 70.31 50.32 356.28 (2) Using the soil metal eluting agents obtained in Examples 1-18 and Comparative Examples 1-3, respectively, eluting experiments were carried out according to the following method to obtain filtrates and soil precipitates; Accurately weigh 5 g of heavy metal contaminated soil into a centrifuge tube, and add a diluted solution of soil heavy metal eluent into the centrifuge tube at a solid-liquid ratio of 1:10 (dilute the soil heavy metal eluent 2 times with deionized water); oscillate the centrifuge tube at 25°C and 150 rpm for 2 h. After the oscillation is completed, centrifuge and filter to obtain the filtrate and precipitate, respectively.

[0054] (3) The heavy metal concentrations in each filtrate were determined using a flame atomic absorption spectrometer, and the removal rates of each heavy metal ion after soil leaching were calculated.

[0055] Table 3 Heavy metal removal rate after soil leaching using soil metal leaching agent The test results of Examples 1-10 and Comparative Examples 1-3 show that after leaching heavy metal contaminated soil using the soil heavy metal leaching agent provided in Examples 1-10 of the present application, the removal rate of Cd ions in the soil is 75.7-78.6%, the removal rate of Cr ions is 68.6-72.5%, the removal rate of Pb ions is 80.8-82.4%, the removal rate of Cu ions is 80.2-86.7%, and the removal rate of Ni ions is 70.4-73.8%. However, after leaching heavy metal contaminated soil using the soil heavy metal leaching agent provided in Comparative Examples 1-3, the removal rate of Cd ions in the soil is only 48.8-54.6%, the removal rate of Cr ions is only 50.8-55.0%, the removal rate of Pb ions is only 65.3-73.4%, the removal rate of Cu ions is only 60.7-65.6%, and the removal rate of Ni ions is only 46.6-49.2%. Therefore, it is explained that the present application uses maleic anhydride-itaconic acid copolymer, levulinic acid and heavy metal chelating agent as the main raw materials of soil heavy metal eluting agent, and the prepared soil heavy metal eluting agent can dissolve, desorb and reverse complex heavy metal ions in the soil in a short time, so that they are eluted from the soil, and the high-efficiency treatment of heavy metal soil is achieved. Further comparison found that after eluting the heavy metal contaminated soil with the soil heavy metal eluting agent prepared in Examples 2-4, 7, and 9-10, the removal rate of Cd ions in the soil was 77.2-78.6% (≥77.0%), the removal rate of Cr ions was 70.3-72.5% (≥70.0%), the removal rate of Pb ions was 81.3-82.4% (≥81.0%), and the removal rate of Cu ions was 84.0-86.7% (≥ 84.0%), and the Ni ion removal rate was 72.5-73.8% (≥72.0%), indicating that the present application further controls the weight parts of maleic anhydride-itaconic acid copolymer, levulinic acid and heavy metal chelating agent within the following range: 13-18 parts of maleic anhydride-itaconic acid copolymer, 12-15 parts of levulinic acid, and 15-25 parts of heavy metal chelating agent. The prepared soil heavy metal eluting agent has better use effect and higher removal efficiency of heavy metal ions in soil.

[0056] The test results of Examples 3 and 11-18 show that Examples 12-18 use a mixture of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer as a heavy metal chelating agent, and the prepared soil heavy metal eluting agent has a better eluting effect on heavy metals in the soil; further comparison shows that after eluting heavy metal contaminated soil with the soil heavy metal eluting agent provided by Examples 17-18, the removal rate of Cd ions in the soil is 80.5-82.3%, the removal rate of Cr ions is 75.9-77.1%, and the removal rate of Pb ions is 86.7-87.4%. The Cu ion removal rate is 88.6-89.3%, and the Ni ion removal rate is 76.7-79.4%; after leaching the heavy metal contaminated soil with the soil heavy metal eluting agent prepared in Examples 12-16, the Cd ion removal rate in the soil is 85.9-88.4% (≥85.0%), the Cr ion removal rate is 80.8-82.0% (≥80.0%), the Pb ion removal rate is 91.8-94.6% (≥90.0%), the Cu ion removal rate is 92.5-94.4% (≥90.0%), and the Ni ion removal rate is 81.8-83.7% (≥80.0%). Therefore, it is explained that the present application further controls the weight ratio of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer within the range of (1.8-2.2):(1.8-2.2):1, and the obtained soil heavy metal eluting agent has better use effect and higher removal efficiency of heavy metal ions in the soil.

[0057] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A soil heavy metal eluting agent, characterized in that: The invention comprises the following components in parts by weight: 10-20 parts of maleic anhydride-itaconic acid copolymer, 10-15 parts of levulinic acid, 10-25 parts of heavy metal chelating agent, 0.2-3 parts of polyacrylamide, 0.1-2 parts of dispersant, 0.5-2 parts of penetrant and 50-80 parts of deionized water.

2. The soil heavy metal eluting agent according to claim 1, characterized in that: The soil heavy metal eluting agent comprises the following components in parts by weight: 13-18 parts of maleic anhydride-itaconic acid copolymer, 12-15 parts of levulinic acid, 15-25 parts of heavy metal chelating agent, 0.2-3 parts of polyacrylamide, 0.1-2 parts of dispersant, 0.5-2 parts of penetrant and 50-80 parts of deionized water.

3. The soil heavy metal eluting agent according to claim 1, characterized in that: The heavy metal chelating agent is selected from one or more of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymers.

4. The soil heavy metal eluting agent according to claim 3, characterized in that: The heavy metal chelating agent is a mixture of aspartic acid-glutamic acid polymerized amino acids, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer.

5. The soil heavy metal eluting agent according to claim 3, characterized in that: The weight ratio of the aspartic acid-glutamic acid polymerized amino acid, iminodisuccinic acid and carboxylate-sulfonate-acrylate terpolymer is (1.8-2.2):(1.8-2.2):

1.

6. The soil heavy metal eluting agent according to claim 3, characterized in that: The molecular weight of the aspartic acid-glutamic acid polymerized amino acid is 8000-13000Da.

7. The soil heavy metal eluting agent according to any one of claims 1 to 6, characterized in that: The dispersant is NNO, and the penetrant is prepared by using block polyether Y-1, Aeo-9, sodium dodecylbenzene sulfonate and water.

8. The soil heavy metal eluting agent according to claim 7, characterized in that: The weight ratio of the block polyether Y-1, Aeo-9, sodium dodecylbenzene sulfonate and water is (3.5-4.5):1:1:(3.5-4.5).

9. A method for preparing a soil heavy metal eluting agent as claimed in any one of claims 1 to 8, characterized in that: The method comprises the following steps: adding deionized water into a reaction kettle, heating to 40-50 DEG C, and setting a stirring speed of 60-70 rpm; then sequentially adding maleic anhydride-itaconic acid copolymer and levulinic acid, stirring for 5-10 minutes, then adding a heavy metal chelating agent, stirring for 10-15 minutes, then adding a dispersant and a penetrant, stirring for 5-10 minutes, finally adding polyacrylamide, and continuously stirring for 15-20 minutes, stopping stirring and heating, and cooling to obtain a soil heavy metal eluting agent.

10. Use of the soil heavy metal eluting agent according to any one of claims 1 to 8 in heavy metal soil improvement.

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