A passivator for repairing mercury-polluted soil, its preparation method and application

Abstract

The present invention belongs to the technical field of contaminated soil remediation, and particularly relates to a passivator for remediating mercury-contaminated soil, a preparation method thereof, and an application. In the present invention, organic sulfur TMT-15 is an environment-friendly heavy metal complexing agent, which is stable and will not cause secondary pollution to the soil. In particular, it reacts with mercury to form a stable complex. Non-metallic minerals such as diatomite have an adsorption property for heavy metals. By loading organic sulfur TMT-15 onto the non-metallic mineral material, the two act synergistically to improve the passivation rate of mercury-contaminated soil. Moreover, the adsorption property on the surface of the non-metallic mineral firmly adsorbs the Hg-TMT complex onto the surface of the non-metallic mineral, prolonging the passivation time of mercury-contaminated soil and solving the problem of short effective passivation time of heavy metal-contaminated soil in the current market.

Description

Technical Field

[0001] The present invention belongs to the technical field of contaminated soil remediation, and in particular relates to a passivating agent for remediating mercury-contaminated soil, and a preparation method and application thereof. Background Art

[0002] With the rapid development of contemporary society and the continuous advancement and innovation of science and technology, environmental pollution has become increasingly serious, threatening the sustainable development of human society to varying degrees. This is particularly true of pollution caused by industrialization and urbanization, with heavy metal pollution being a prominent example. This alters soil composition, making it difficult to effectively control in the short term and severely disrupting the balance of ecosystems. Mercury, a major component of soil pollution and a primary pollutant to control, is highly mobile, persistent, and bioaccumulates, resulting in significant toxic and side effects, making its control challenging. If mercury in soil is not promptly and effectively treated, it can enter the human body and pose a threat to human health.

[0003] Existing methods for remediating mercury contamination in soil primarily rely on physical and chemical methods such as soil leaching, landfilling, and thermal volatilization. While these methods have some removal effectiveness, they are unsuitable for large-scale application to mercury-contaminated soils due to their complex operational processes, high costs, and significant disturbance to the soil's physical and chemical properties. Furthermore, they often damage soil structure, leading to decreased soil biological activity and degradation of soil fertility. Therefore, passivation and stabilization remediation technology has become a viable option. Passivation and stabilization remediation technology is an effective soil remediation technique that modifies the form of heavy metals in the soil by adding remediation agents, reducing their mobility and bioavailability. The key to this technology is the identification and preparation of inexpensive and efficient remediation materials. Although some literature and patents have published / disclosed remediation materials for mercury contamination, such as bentonite, lime, and apatite, the remediation effects of existing remediation materials remain unsatisfactory, as the surface geochemical behavior of Hg is far more complex than that of other heavy metals. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a passivating agent for repairing mercury-contaminated soil, a preparation method thereof, and an application thereof. The passivating agent for repairing mercury-contaminated soil provided by the present invention has a good passivation effect on mercury pollution in the soil and a long effective passivation time.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a passivating agent for repairing mercury-contaminated soil, comprising a non-metallic mineral material and organic sulfur TMT-15 loaded on the surface and pores of the non-metallic mineral material;

[0007] The non-metallic mineral material includes one or more of diatomaceous earth, zeolite, bentonite and sepiolite.

[0008] Preferably, the mass of the organic sulfur TMT-15 is 5-20% of the mass of the non-metallic mineral material.

[0009] Preferably, the particle size of the passivator is ≤74 μm.

[0010] The present invention also provides a preparation method of the passivator described in the above technical solution, comprising the following steps:

[0011] Mix the non-metallic mineral material and an aqueous solution of organic sulfur TMT-15, and sequentially perform loading, drying, and pulverization to obtain the passivator.

[0012] Preferably, the temperature of the loading is 20-30 °C.

[0013] Preferably, the temperature of the drying is 50-100 °C.

[0014] The present invention also provides an application of the passivator described in the above technical solution or the passivator prepared by the preparation method described in the above technical solution in repairing mercury-contaminated soil.

[0015] The present invention also provides a method for repairing mercury-contaminated soil, comprising the following steps:

[0016] Apply the passivator to the mercury-contaminated soil and perform curing;

[0017] The passivator is the passivator described in the above technical solution or the passivator prepared by the preparation method described in the above technical solution.

[0018] Preferably, the mass of the passivator is 0.2-2% of the dry weight of the mercury-contaminated soil; the total mercury content in the mercury-contaminated soil is 1.8-200 mg / kg.

[0019] Preferably, the curing time is 5-15 d.

[0020] The present invention provides a passivator for repairing mercury - contaminated soil, which comprises a non - metallic mineral material and organic sulfur TMT - 15 loaded on the surface and pores of the non - metallic mineral material; the non - metallic mineral material comprises one or more of diatomite, zeolite, bentonite and sepiolite. In the present invention, organic sulfur TMT - 15 is an environment - friendly heavy - metal complexing agent, which is stable and will not cause secondary pollution to the soil. Especially, it reacts with mercury to form a stable complex. Non - metallic minerals such as diatomite have adsorption properties for heavy metals. Loading organic sulfur TMT - 15 onto the non - metallic mineral material, the two act synergistically to improve the passivation rate of mercury - contaminated soil. Moreover, the adsorption property of the non - metallic mineral firmly adsorbs the Hg - TMT complex onto the surface and pores of the non - metallic mineral, prolonging the passivation time of mercury - contaminated soil and solving the problem of short effective passivation time of heavy - metal - contaminated soil in the current market. Detailed implementation mode

[0021] The present invention provides a passivator for repairing mercury - contaminated soil, which comprises a non - metallic mineral material and organic sulfur TMT - 15 loaded on the surface and pores of the non - metallic mineral material;

[0022] The non - metallic mineral material comprises one or more of diatomite, zeolite, bentonite and sepiolite.

[0023] Unless otherwise specified, the present invention has no special requirements for the sources of the raw materials used, and commercially available products well - known to those skilled in the art can be used.

[0024] The passivator for repairing mercury - contaminated soil provided by the present invention comprises a non - metallic mineral material.

[0025] In the present invention, the non - metallic mineral material comprises one or more of diatomite, zeolite, bentonite and sepiolite, and is preferably diatomite.

[0026] In the present invention, the particle size of the non - metallic mineral material is preferably 200 - 400 mesh, more preferably 250 - 325 mesh; the specific surface area of the non - metallic mineral material is preferably 10 - 100 m 2 / g, more preferably 50 - 65 m 2 / g; the porosity of the non - metallic mineral material is preferably 80 - 95%, more preferably 90 - 92%.

[0027] The passivator for repairing mercury - contaminated soil provided by the present invention comprises organic sulfur TMT - 15 loaded on the surface and pores of the non - metallic mineral material.

[0028] In the present invention, the mass of the organic sulfur TMT - 15 is preferably 5 - 20% of the mass of the non - metallic mineral material, more preferably 10 - 20%.

[0029] In the present invention, the source of the organic sulfur TMT-15 is Shandong Laide Water Treatment Technology Company.

[0030] In the present invention, the particle size of the passivator is preferably ≤74 μm, more preferably ≤45 μm.

[0031] In the present invention, the organic sulfur TMT-15 is an environment-friendly heavy metal complexing agent, which is stable and will not cause secondary pollution to the soil. Especially, it reacts with mercury to form a stable complex. Non-metallic minerals such as diatomite have adsorption properties for heavy metals. Loading the organic sulfur TMT-15 onto the non-metallic mineral materials, the two act synergistically to improve the passivation rate of mercury-contaminated soil. And the adsorption property of the non-metallic mineral firmly adsorbs the Hg-TMT complex onto the surface and pores of the non-metallic mineral, prolonging the passivation time of mercury-contaminated soil and solving the problem of short effective passivation time of heavy metal-contaminated soil in the current market.

[0032] The present invention also provides a preparation method of the passivator described in the above technical solution, including the following steps:

[0033] Mix the non-metallic mineral material and an aqueous solution of organic sulfur TMT-15, and successively carry out loading, drying and grinding to obtain the passivator.

[0034] In the present invention, the non-metallic mineral material and an aqueous solution of organic sulfur TMT-15 are mixed to obtain a mixed solution.

[0035] In the present invention, the preparation method of the aqueous solution of the organic sulfur TMT-15 is preferably: mix the organic sulfur TMT-15 and water, and stir evenly.

[0036] In the present invention, the mixing of the non-metallic mineral material and the aqueous solution of the organic sulfur TMT-15 is preferably to add the non-metallic mineral material to the aqueous solution of the organic sulfur TMT-15 and stir evenly. In the present invention, the concentration of the aqueous solution of the organic sulfur TMT-15 is preferably 0.025 - 0.1 g / mL, more preferably 0.05 - 0.1 g / mL.

[0037] After obtaining the mixed solution, the present invention carries out loading on the mixed solution.

[0038] In the present invention, the temperature of the loading is preferably 20 - 30 °C, more preferably 25 °C; the time of the loading is preferably 12 - 48 h, more preferably 24 h.

[0039] After the loading, the present invention dries the loaded mixed solution.

[0040] In the present invention, the drying temperature is preferably 50 - 100 °C, more preferably 60 - 70 °C; the drying time is preferably 2 - 24 h, more preferably 10 - 12 h; the drying equipment is preferably an oven.

[0041] After drying, the present invention pulverizes the obtained substance.

[0042] After pulverizing, the present invention preferably further includes: screening the obtained pulverized powder, and the fraction passing through the sieve is the passivator.

[0043] In the present invention, the aperture of the sieve mesh used for screening is preferably 200 mesh.

[0044] The present invention also provides the application of the passivator described in the above technical solution or the passivator prepared by the preparation method described in the above technical solution in the repair of mercury - contaminated soil.

[0045] In the present invention, the total mercury content in the mercury - contaminated soil is preferably 1.8 - 200 mg / kg, more preferably 1.8 - 100 mg / kg; the content of available mercury in the mercury - contaminated soil is preferably 1 - 150 mg / kg, more preferably 1 - 80 mg / kg.

[0046] The present invention also provides a method for repairing mercury - contaminated soil, comprising the following steps:

[0047] Applying the passivator to the mercury - contaminated soil and carrying out curing;

[0048] The passivator is the passivator described in the above technical solution or the passivator prepared by the preparation method described in the above technical solution.

[0049] In the present invention, the mass of the passivator is preferably 0.2 - 2% of the dry weight of the mercury - contaminated soil, more preferably 0.5 - 1.5%.

[0050] In the present invention, the curing time is preferably 5 - 15 d, more preferably 7 d; the curing is preferably carried out under room - temperature conditions; the moisture content of the mercury - contaminated soil during the curing process is preferably 20 - 50%, more preferably 25 - 30%.

[0051] Next, the technical solutions in the present invention will be clearly and completely described in combination with the examples in the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0052] Example 1

[0053] Absorb 0.5 g of the organic sulfur TMT-15 solution into a beaker, add it to 20 mL of water, stir evenly, add 10 g of diatomaceous earth, stir evenly, cover the lid, place it in an oven and load it at 30 °C for 24 h, then dry it at 60 °C for 12 h, and then pulverize it and pass it through a 200-mesh sieve to obtain a passivator.

[0054] Example 2

[0055] Absorb 1 g of the organic sulfur TMT-15 solution into a beaker, add it to 20 mL of water, stir evenly, add 10 g of diatomaceous earth, stir evenly, cover the lid, place it in an oven and load it at 30 °C for 24 h, then dry it at 60 °C for 12 h, and then pulverize it and pass it through a 200-mesh sieve to obtain a passivator.

[0056] Example 3

[0057] Absorb 2 g of the organic sulfur TMT-15 solution into a beaker, add it to 20 mL of water, stir evenly, add 10 g of diatomaceous earth, stir evenly, cover the lid, place it in an oven and load it at 30 °C for 24 h, then dry it at 60 °C for 12 h, and then pulverize it and pass it through a 200-mesh sieve to obtain a passivator.

[0058] Example 4

[0059] Absorb 2 g of the organic sulfur TMT-15 solution into a beaker, add it to 20 mL of water, stir evenly, add 10 g of zeolite, stir evenly, cover the lid, place it in an oven and load it at 30 °C for 24 h, then dry it at 60 °C for 12 h, and then pulverize it and pass it through a 200-mesh sieve to obtain a passivator.

[0060] Example 5

[0061] Absorb 2 g of the organic sulfur TMT-15 solution into a beaker, add it to 20 mL of water, stir evenly, add 10 g of bentonite, stir evenly, cover the lid, place it in an oven and load it at 30 °C for 24 h, then dry it at 60 °C for 12 h, and then pulverize it and pass it through a 200-mesh sieve to obtain a passivator.

[0062] Example 6

[0063] Absorb 1 g of the organic sulfur TMT-15 solution into a beaker, add it to 20 mL of water, stir evenly, add 10 g of sepiolite, stir evenly, cover the lid, place it in an oven and load it at 30 °C for 24 h, then dry it at 60 °C for 12 h, and then pulverize it and pass it through a 200-mesh sieve to obtain a passivator.

[0064] Comparative Example 1

[0065] Use diatomaceous earth alone.

[0066] Comparative Example 2

[0067] Using zeolite alone.

[0068] Comparative Example 3

[0069] Using bentonite alone.

[0070] Comparative Example 4

[0071] Using sepiolite alone.

[0072] Comparative Example 5

[0073] Using organic sulfur TMT-15 alone.

[0074] Comparative Example 6

[0075] Using unloaded organic sulfur TMT-15 and diatomite.

[0076] Application Examples 1-6 and Comparative Application Examples 1-6

[0077] Preparation of mercury-contaminated soil: Take 3 g of mercury sulfate, add it to 2 L of water, adjust the solution to acidic with dilute sulfuric acid, stir and heat to dissolve the mercury sulfate, then adjust the pH value of the solution to neutral with dilute sodium hydroxide solution, uniformly add it to 20-25 kg of soil, naturally air-dry and crush it roughly with a jaw crusher 3- to 5 times.

[0078] Table 1 Mercury content in mercury-contaminated soil

[0079] Contaminated soil Total mercury (mg / kg) Available mercury (mg / kg) Mercury-contaminated soil 86.52 74.05

[0080] Respectively take the passivators of Examples 1-6 and the soil remediation agents of Comparative Examples 1-6 (the dosages are shown in Table 2), add them to 50 g of mercury-contaminated soil, stir evenly, add water to moisten, make the water content of the soil 30%, stir evenly again, cover the lid, and cure for 7 d at room temperature to obtain the repaired soil.

[0081] Performance test

[0082] Dry the repaired soil obtained from Application Examples 1-6 and Comparative Application Examples 1-6 in an oven at 80 °C, then measure the available mercury content in the soil and calculate the passivation rate. The passivation rate % = (the available mercury amount in the mercury-contaminated soil without adding the passivator - the available mercury amount in the mercury-contaminated soil after adding the passivator) × 100 / the available mercury amount in the mercury-contaminated soil without adding the passivator. The results are shown in Table 2.

[0083] Method for measuring available mercury:

[0084] Preparation of DTPA extractant:

[0085] (pH 7.30, 0.005 mol / LDTPA, 0.01 mol / LCaCl2, 0.1 mol / LTEA) Weigh 1.967 g of DTPA (analytical grade) and dissolve it in 14.92 g or 13.3 mL of LTEA (analytical grade triethanolamine) and a small amount of water. Dissolve 1.47 g of CaCl2·2H2O in water and transfer both to a 1000 mL volumetric flask. Add water to approximately 950 mL. Adjust the pH to 7.30 using a (1+1) hydrochloric acid solution on a pH meter. Dilute to the mark with water, shake well, and store in a plastic bottle. Place 25.0 g of mercury-contaminated soil in a 250 mL plastic bottle, add 50 mL of DTPA, cap the bottle, and shake at 25°C for 2 h. Filter the clear solution and analyze mercury using ICP-OES.

[0086] Table 2 Passivation rate of repaired soil obtained from application examples 1 to 6 and comparative application examples 1 to 6

[0087]

[0088] As can be seen from Table 2, the non-metallic mineral material passivator loaded with organic sulfur TMT-15 provided by the present invention has a better passivation effect on mercury-contaminated soil than using non-metallic mineral materials, TMT-15 and soil remediation agents on the market alone, and the passivation rate for mercury can reach more than 98%.

[0089] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A passivator for repairing mercury-polluted soil, characterized in that, It consists of a non-metallic mineral material and organic sulfur TMT-15 loaded on the surface and pores of the non-metallic mineral material; the non-metallic mineral material is diatomite, zeolite or sepiolite; The mass of the organic sulfur TMT-15 is 10-20% of the mass of the non-metallic mineral material; The particle size of the non-metallic mineral material is 200 to 400 mesh; the specific surface area of the non-metallic mineral material is 10 to 100 m 2 / g; the porosity of the non-metallic mineral material is 80 to 95%; The particle size of the passivator is ≤74 µm.

2. The preparation method of the passivator according to claim 1, comprising the following steps: Mix the non-metallic mineral material and an aqueous solution of organic sulfur TMT-15, and successively carry out loading, drying and pulverization to obtain the passivator.

3. The preparation method according to claim 2, wherein The temperature of the loading is 20-30 °C.

4. The preparation method according to claim 2, wherein, The temperature of the drying is 50-100 °C.

5. The application of the passivator according to claim 1 or the passivator prepared by the preparation method according to any one of claims 2-4 in the remediation of mercury-contaminated soil.

6. A method for remediating mercury-contaminated soil, comprising the following steps: Apply the passivator to the mercury-contaminated soil and carry out curing; The passivator is the passivator according to claim 1 or the passivator prepared by the preparation method according to any one of claims 2-4.

7. The method according to claim 6, wherein The mass of the passivator is 0.2-2% of the dry weight of the mercury-contaminated soil; the total mercury content in the mercury-contaminated soil is 1.8-200 mg / kg.

8. The method according to claim 6 or 7, characterized in that, The time of the curing is 5-15 d.

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