Heavy metal stabilizing material in polluted soil as well as preparation method and application of heavy metal stabilizing material

Abstract

The invention belongs to the technical field of soil treatment, and discloses a heavy metal stabilizing material in contaminated soil and a preparation method and application thereof.The stabilizing material is specifically particles formed by modifying ferrous sulfide through calcium alginate in a coated mode, the hydration particle size of the stabilizing material is 0.2-21 micrometers, the mass ratio of calcium alginate to ferrous sulfide is 0.4: 1-2.3: 1, and the stabilizing material is prepared through a hydrothermal method. And the thickness of the calcium alginate wrapping layer is 0.05 to 10.5 [mu] m. The detailed structure and composition in the heavy metal stabilizing material, the corresponding preparation method, the application method and the like are improved, calcium alginate with a specific proportion and a specific coating layer thickness is used for coating and modifying ferrous sulfide, and the particle size distribution of whole particles is controlled; and cationic heavy metals such as unstable lead, zinc, cadmium and copper and anionic heavy metals such as arsenic in the soil can be converted to a stable state, so that the mobility and environmental risk of the heavy metals such as lead, zinc, cadmium, copper and arsenic in the soil are effectively reduced.

Description

technical field [0001] The invention belongs to the technical field of soil treatment, in particular to the technical field of remediation of heavy metal-contaminated soil, and more specifically relates to a heavy metal stabilization material in polluted soil and its preparation method and application, which can be used as a soil remediation agent. Background technique [0002] With the development of industrialization in my country, industrial activities such as mining and metal smelting have released a large amount of heavy metals such as lead, zinc, cadmium, and copper into the soil, resulting in serious pollution of heavy metals in industrial sites. The occurrence form of heavy metals in soil is the main factor affecting their mobility and environmental risk. Heavy metals in exchangeable and carbonate-bound states are easily released into interstitial water under the action of rainwater, plant roots and microorganisms. Migration by surface runoff or underground seepage h...

AI Technical Summary

Problems solved by technology

[0005] Stabilizers / stabilizing materials can inhibit the oxidation of ferrous sulfide by physically isolating oxidative species. For example, in the article Wu J. et al, 2018, by using calcium alginate gel to encapsulate ferrous sulfide, it effectively inhibits the oxidation of ferrous sulfide by oxygen. Oxidation, but this technology drops sodium alginate-sodium sulfide mixed solution into calcium chloride-ferrous sulfide solution, and the size of the synthesized gel particles is controlled by the size of the sodium alginate-sodium sulfide mixed solution droplet, with a larger diameter , about 1.3mm, which is not conducive to its migration in the soil medium, the mass transfer efficiency is poor, the average thickness of the calcium alginate coating is about 163μm, the oxidation process of ferrous sulfide is completely inhibited, and it is difficult to produce H through air oxidation and hydrolysis. + Realize the activation process and further transformation of heavy metals in the soil; 4 ), aminotrimethylene phosphonate (ATMP), ethylenediaminetetramethylene phosphonate (EDTMP), hydroxymethylene phosphonate (HEDP) and other dissolved organic matter on the surface of ferrous sulfide particles , modify the surface properties of ferrous sulfide, and improve the steric resistance and electrostatic repulsion of ferrous sulfide while ensuring the nanometer size of ferrous sulfide, so as to ensure the mass transfer rate of ferrous sulfide in soil, but the organic matter Molecular surface adsorption can not effectively reduce the oxidation rate of ferrous sulfide, and realize the balance of the reaction rate of heavy metals in ferrous sulfide oxidative release acid activation soil and ferrous sulfide stabilized activated heavy metals, resulting in the rate of activated heavy metals being higher than the stable generation of metal sulfides Stabilize the rate of heavy metals, resulting in low form conversion efficiency of heavy metals and low effective utilization of ferrous sulfide

[0006] Chinese patent CN109365514A discloses a ferrous sulfide particle suspension combined with sodium phosphate, sodium chloride and calcium carbonate to stabilize lead in soil repair method, although it also discloses that ferrous sulfide can stabilize lead in soil and convert it into sulfide to reduce its leaching Toxic approach, but there is still S in ferrous sulfide - Easy to be oxidized by oxygen and manganese oxides, resulting in low utilization rate and other problems

[0007] Chinese patent CN108641726A discloses a remediation method for stabilizing soil arsenic and cadmium with organic sulfur chelating agent, soluble ferric salt / ferrous salt, and calcium-based materials, although it also discloses a method for reducing the leaching toxicity of heavy metals by coordinating S elements with heavy metals , but there are still unstable organic ligands, and there is a risk of releasing heavy metals after being decomposed by plants and microorganisms

[0008] Chinese patent CN108726822A discloses a method for stabilizing heavy metals such as Cd, Cu and Zn in sediments with sulfur-containing compound inorganic materials, alkaline substances, clay minerals and ferrous sulfate, although it also discloses that the pH of sediments is increased and metal sulfides are formed A method to reduce the toxicity of heavy metal leaching, but after the addition of alkaline materials, the pH of the sediment environment is high, and the content of activated heavy metals is low, so only a small part of the unstable heavy metals can be converted into a stable state, and the pH of the sediment is buffered to neutral / In the acidic process, there are problems such as the re-release of heavy metals

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