A method for removing heavy metal ions and organic matter complex pollution in soil by using complexing agent to assist manganese dioxide to activate sulfite

Abstract

The present application relates to a kind of method for removing heavy metal ion and organic compound pollution in soil by using complexing agent assisted manganese dioxide activation sulfite.The method of the present application specifically provides a kind of mixture of complexing agent, sulfite and MnO2;The mixture is fully infiltrated and mixed with contaminated soil to react, finally realizes the removal of heavy metal ion and organic compound in soil.The present application uses humic acid as complexing agent to assist manganese dioxide activation sodium sulfite, a kind of method for adsorbing heavy metal ion in soil and synchronously removing organic compound.The used complexing agent humic acid can enhance soil fertility, improve soil structure, improve soil water retention and drought resistance, promote plant growth and development.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil remediation, and particularly relates to a method for removing heavy metal ions and organic compound pollution in soil by using complexing agent assisted manganese dioxide activated sulfite. BACKGROUND

[0002] The environmental quality and safety of soil and groundwater are of great importance to the sustainable development of agriculture, society and economy, and human health. With the rapid advancement of urbanization and industrialization, the problem of soil heavy metal and organic pollution caused by human activities is becoming increasingly serious. Heavy metals not only have strong migration, but also have extremely high toxicity, and are difficult to degrade once they enter the environment. In addition to heavy metal pollution, organic pollutants are also an important form of soil pollution. Although the concentration of organic matter in water is relatively low, they are easy to accumulate in biological bodies, have significant toxic side effects, and have potential risks of carcinogenesis and teratogenesis.

[0003] At present, the main methods for removing heavy metals in soil include washing remediation, phytoremediation and microbial remediation. Although washing remediation is effective, the remediation cost is usually high, and it may cause significant disturbance to the basic properties of soil and affect its normal function. Phytoremediation has problems such as long time, low removal efficiency and unstable heavy metal enrichment ability, and only a few specific plants have strong heavy metal enrichment ability, and plants in different regions also have obvious differences in physiological characteristics. In terms of microbial remediation, the species composition may be affected by environmental factors, which may affect the remediation effect, and has high requirements for environmental conditions, and needs to be pretreated for difficult-to-degrade or toxic compounds. The soil remediation technology of organic contaminated sites can be divided into physical remediation, chemical remediation and biological remediation according to the operation principle. Physical remediation requires high soil property requirements, has limited application range and long remediation period; in chemical remediation, common oxidation technologies such as ozone oxidation method not only have high energy consumption and low ozone utilization rate, but also may produce by-products such as bromate. And Fenton oxidation method is limited by narrow pH range, and ferrous ions are easy to precipitate. Biological remediation technology also has defects such as high environmental condition requirement, applicability to low concentration pollution and long remediation period.

[0004] In order to realize the remediation of heavy metal and organic compound combined pollution soil, the present application provides a method for simultaneously removing manganese and organic pollutants in manganese-containing soil by using complexing agent and sulfite. SUMMARY

[0005] To solve the technical problem that the content of manganese and organic pollutants in soil exceeds the standard in the prior art, the application provides a method for removing heavy metal ion and organic compound pollution in soil by using a complexing agent to assist manganese dioxide in activating sulfite.

[0006] The application aims to provide a method for removing heavy metal ion and organic compound pollution in soil by using a complexing agent to assist manganese dioxide in activating sulfite, which comprises the following steps:

[0007] A mixture of a complexing agent, sulfite and MnO2 is provided.

[0008] The mixture is fully mixed with contaminated soil to react, and finally the heavy metal ion and organic compound are removed.

[0009] In some embodiments of the application, the complexing agent is selected from humic acid. The humic acid is derived from grass carbon, lignite and weathered coal, etc. The application uses the humic acid to react with manganese dioxide to form a complex, thereby promoting the autocatalytic oxidation of sulfite.

[0010] In some embodiments of the application, the sulfite is selected from one or more of sodium sulfite, potassium sulfite, sodium bisulfite and potassium bisulfite.

[0011] In some embodiments of the application, the concentration of MnO2 is 50 μM-2 mM, and the molar ratio of MnO2 to the complexing agent is (1:2)-(1:10).

[0012] In some embodiments of the application, the concentration of MnO2 is 50 μM-2 mM, and the molar ratio of MnO2 to the sulfite is (1:2)-(1:20).

[0013] In some embodiments of the application, the concentration of MnO2 is 50 μM-2 mM, and the molar ratio of MnO2 to the complexing agent to the sulfite is 1:(2-5):(2-20).

[0014] In some embodiments of the application, the pH of the contaminated soil is 5-7.

[0015] In some embodiments of the application, the content of organic compound in the contaminated soil is 100 μg / kg-200 μg / kg.

[0016] In some embodiments of the application, the content of heavy metal ion in the contaminated soil is 0.1 mg / kg-1 mg / kg.

[0017] In some embodiments of the present invention, the organic compound includes polycyclic aromatic hydrocarbons and organochlorine pesticides. These include one or more of the following: chlorophenol, naphthalene, acenaphthene, phenanthrene, anthracene, fluoranthene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, pyrene, benzo[a]pyrene, dibenzo[a]anthracene, ind[a]pyrene, benzo[a]perylene, DDT (dichlorophenoxyacetic acid), and DHC (dichlorophenoxyacetic acid).

[0018] In some embodiments of the present invention, the reaction time is 15 to 30 minutes;

[0019] The heavy metals include one or more of Ti(I), Pb(II), Cd(II), As(III), and Sb(III).

[0020] The principle of this invention is as follows: Humic acid is a large-molecule organic substance widely found in nature and is also an important component of soil. Using humic acid as a complexing agent has environmental advantages. The humic acid complexing agent is mixed with sulfite and manganese dioxide in a specific ratio and then injected into the contaminated soil to be treated. The complexing agent reacts with manganese dioxide to form a complex, thereby promoting the autocatalytic oxidation of sulfite. During this process, HSO3- is oxidized to SO3. ·- Then SO3 ·- Further conversion into SO5 ·- Ultimately, it is converted into HSO5. - Simultaneously, the Mn(IV)-complexing agent is reduced to form the Mn(III)-complex. HSO5 - It can oxidize Mn(III)-complexing agents to Mn(V)-complexing agents. Mn(V) can rapidly oxidize and decompose organic matter, and itself is converted into MnO2. As the reaction proceeds, MnO2 gradually aggregates into particles, generating residual MnO2 solid. The MnO2 generated in the reaction has a stronger ability to adsorb heavy metal ions, and can adsorb heavy metal ions in the soil, thereby achieving the simultaneous removal of heavy metal ions and organic pollutants from the soil.

[0021] The technical solution of the present invention has the following advantages compared with the prior art:

[0022] This invention injects a mixture of complexing agent, MnO2, and sulfite into the soil, which can oxidize and decompose organic matter in the soil and generate MnO2 with a stronger adsorption capacity for heavy metal ions. The generated MnO2 is a commonly used adsorbent material in soil remediation and can adsorb and remove heavy metal ions such as Ti(I), Pb(II), Cd(II), As(III), and Sb(III).

[0023] The application is suitable for soil conditions with pH of 5-7, and the method is simple, the used pesticide is green and environment-friendly, the used humic acid complexing agent can enhance soil fertility, improve soil structure, improve soil water retention and drought resistance, and promote plant growth and development. DETAILED DESCRIPTION

[0024] The application will be further described in conjunction with specific examples so that those skilled in the art can better understand the application and implement it, but the examples are not limiting to the application.

[0025] Example 1

[0026] The example provides a method for removing Cd(II) and organic matter complex contaminated soil by using complexing agent assisted manganese dioxide activated sulfite, and specifically as follows.

[0027] Step 1: A soil sample is provided, the soil contains 0.5 mg / kg of Cd(II) and 150 μg / kg of pentachlorophenol; the concentration of MnO2 in the mixed solution is 200 μM, and the molar ratio of MnO2: humic acid (derived from grass carbon): sodium sulfite is 1:5:10 to determine the dosing amount of humic acid and sulfite, the soil is adjusted to pH 6, and the reaction time after dosing is 20 min.

[0028] Step 2: After the reaction is terminated, 1 gram of the prepared complex contaminated soil sample is weighed into a 100 mL conical flask, and 100 ml of 10 g / L Tween80 leaching agent solution is added for leaching. After leaching, the mixture is centrifuged to obtain the supernatant, and the residual amount of Cd(II) and pentachlorophenol in the supernatant is determined.

[0029] The residual content of Cd(II) is quantitatively determined by ICP-OES, and the content of pentachlorophenol after filtration is quantitatively detected by high performance liquid chromatography device, and the removal rates of Cd(II) and pentachlorophenol are determined by comparison analysis of the original soil.

[0030] The experimental results are shown in Table 1.

[0031] Example 2

[0032] Different from example 1, the soil pH is adjusted to pH 5. The removal rates of Cd(II) and pentachlorophenol after treatment are shown in the following table 1.

[0033] Example 3

[0034] Different from example 1, the soil pH is adjusted to pH 7. The removal rates of Cd(II) and pentachlorophenol after treatment are shown in the following table 1.

[0035] Example 4

[0036] The difference between this example and example 1 is that the reaction time after adding reagents is 15 min. The removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0037] Example 5:

[0038] The difference between this example and example 1 is that the reaction time after adding reagents is 30 min. The removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0039] Example 6:

[0040] The difference between this example and example 1 is that the humic acid complexing agent in this example is derived from lignite, and the removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0041] Example 7:

[0042] The difference between this example and example 1 is that the humic acid complexing agent in this example is derived from weathered coal, and the removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0043] Example 8:

[0044] The difference between this example and example 1 is that the molar ratio of MnO2: complexing agent: sulfite is 1:1:2:10, and the removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0045] Example 9:

[0046] The difference between this example and example 1 is that the molar ratio of MnO2: complexing agent: sulfite is 1:1:10:10, and the removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0047] Example 10:

[0048] The difference between this example and example 1 is that the molar ratio of MnO2: complexing agent: sulfite is 1:1:5:2, and the removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0049] Example 11:

[0050] The difference between this example and example 1 is that the molar ratio of MnO2: complexing agent: sulfite is 1:1:5:5, and the removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0051] Example 12:

[0052] The difference between this example and example 1 is that the molar ratio of MnO2: complexing agent: sulfite is 1:1:5:20, and the removal rates of Cd(II) and pentachlorophenol after treatment are shown in Table 1 below.

[0053] Comparative Example 1:

[0054] Different from example 1, no complexing agent was added in the comparative example, the removal rates of Cd(II) and pentachlorophenol after treatment were shown in Table 1 below.

[0055] Comparative example 2:

[0056] Different from example 1, no sulfite was added in the comparative example, the removal rates of Cd(II) and pentachlorophenol after treatment were shown in Table 1 below.

[0057] Table 1

[0058] Cd(II) removal efficiency (%) Pentachlorophenol removal efficiency (%) Example 1 87.3 93.6 Example 2 80.6 88.3 Example 3 89.5 59.6 Example 4 76.9 89.2 Example 5 89.2 94.3 Example 6 87.5 92.1 Example 7 88.1 94.8 Example 8 81.6 86.1 Example 9 88.2 93.6 Example 10 63.2 70.5 Example 11 80.6 82.1 Example 12 63.9 64.1 Comparative Example 1 8.1 5.7 Comparative Example 2 5.3 4.5

[0059] From examples 1-3, it can be seen that pH will affect the removal rates of Cd(II) and pentachlorophenol in the present application, the removal effect of pentachlorophenol in the present application is better at pH = 6, lower pH will affect the conversion of MnO2 in the reaction system, and inhibit the removal of Cd(II), higher pH will affect the formation and stability of active species in the reaction system, thereby the removal effect of pentachlorophenol is not good. When pH = 6, the treatment effect is best.

[0060] From examples 1, 4, 5, it can be seen that the reaction time after adding the reagent will affect the removal effect, when the reaction time is 20 min, not only the removal rate is good, but also the time cost can be saved. If the reaction time is insufficient, the active species cannot effectively remove the organic pollutants, and the conversion rate of MnO2 is low, and the adsorption capacity for Cd(II) is also insufficient.

[0061] From examples 1, 6, 7, it can be seen that the removal effects of pentachlorophenol and Cd(II) by humic acid from different sources are not much different, and each has its own advantages.

[0062] From examples 1, 8-12, it can be seen that the molar ratio of MnO2, complexing agent and sulfite has certain influence on the removal rates of Cd(II) and pentachlorophenol. Among them, the effect of the molar ratio of MnO2, complexing agent and sulfite is 1:5:10 is the best, low concentration of complexing agent will lead to the conversion and stability of active intermediates to decrease, thereby the overall removal rate decreases. Low concentration of sulfite will lead to insufficient HSO5- generation, thereby affecting the subsequent reaction. When the concentration of sulfite is high, the sulfite will participate in the competition of HSO5- and active intermediates, resulting in poor removal effect.

[0063] From examples 1, comparative examples 1-2, it can be seen that without complexing agent, MnO2 cannot effectively activate sulfite to generate HSO5- 5-Therefore, the organic matter cannot be effectively oxidized and decomposed, and MnO2 with stronger metal ion adsorption capacity cannot be generated. In the absence of sulfite, HSO3 cannot be generated, and the subsequent reaction cannot be carried out, so that the synchronous removal of Cd(II) and organic matter cannot be achieved.

[0064] Obviously, the above embodiments are only examples for clearly illustrating, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments do not need to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for removing heavy metal ion and organic matter complex pollution in soil by using complexing agent assisted manganese dioxide activated sulfite, characterized in that, The method comprises the following steps: providing a mixture of a complexing agent, a sulfite and MnO2; mixing the mixture with contaminated soil to react and remove heavy metal ions and organic matter; the complexing agent is selected from humic acid; the complexing agent reacts with MnO2 to form a complex Mn(IV)-complexing agent, thereby promoting the autocatalytic oxidation of the sulfite; In sulfites, HSO3- is oxidized to SO3. ·- Then SO3 ·- Further conversion to SO5 ·- Ultimately, it is converted into HSO5. - ; the Mn(IV)-complexing agent is reduced to form a Mn(III)-complex; HSO5 - The Mn(III)-complexing agent is oxidized to a Mn(V)-complexing agent; the Mn(V) oxidizes and decomposes organic matter and itself is converted to MnO2; as the reaction proceeds, the MnO2 gradually aggregates into particles to form residual state MnO2 solid, and the reaction-generated MnO2 has stronger adsorption capacity for heavy metal ions, thereby adsorbing heavy metal ions in the soil; the heavy metal ions include one or more of Ti(I), Pb(II), Cd(II), As(III) and Sb(III); the molar ratio of MnO2: humic acid: sulfite is 1:5:10; the pH of the contaminated soil is 5-7; the reaction time is 15-30 min.

2. The method of claim 1, wherein, the sulfite is selected from one or more of sodium sulfite, potassium sulfite, sodium bisulfite or potassium bisulfite.

3. The method of claim 1, wherein, the content of organic matter in the contaminated soil is 100-200 μg / kg.

4. The method of claim 1, wherein, the content of heavy metal ions in the contaminated soil is 0.1-1 mg / kg.

5. The method of claim 1, wherein, the organic matter includes polycyclic aromatic hydrocarbons and organochlorine pesticides.