Passivator for remediation of farmland soil subjected to combined pollution of heavy metals, and preparation method and use method of passivator

Abstract

The invention relates to a passivator for remediation of farmland soil subjected to combined pollution of heavy metals such as cadmium, chromium, copper and nickel, and a preparation method and a use method of the passivator. The passivator is prepared from a passivator A and a passivator B, wherein the passivator A is prepared from montmorillonite, kieselguhr, sepiolite, illite and ferrous sulfate; the passivator B is prepared from periclase, calcite, calcium magnesium phosphate fertilizer, plant ash and calcium hydroxide; the passivator is suitable for the farmland soil subjected to the combined pollution of the cadmium, the chromium, the copper and the nickel, and is prepared from the multiple different porous absorption materials with specific contents and a passivation material; the components of the passivator have complementary advantages, and the principles such as absorption and stabilization are combined; the combination forms of the heavy metals are effectively enhanced by ion exchange, complexing, chelating and adsorption methods, and the combination forms are converted into more stable strong organic binding states and residue states, so that the effective state contents of the heavy metals in the farmland soil are effectively reduced, and the passivation effect is long-acting and stable; therefore, the passivator has a great repair effect for the farmland soil subjected to combined pollution of the cadmium, the chromium, the copper and the nickel.

Description

technical field [0001] The invention relates to the field of farmland soil treatment of heavy metal compound pollution, in particular to a passivator for repairing heavy metal compound pollution of farmland soil, a preparation method and a use method thereof. Background technique [0002] The development of mineral resources is conducive to the development of the local economy, regardless of environmental and ecological benefits, rough mining will inevitably cause long-term soil, water, and air pollution; The mining area has become a source of pollution left over from history, polluting the local ecological environment and human health for a long time. [0003] Soil is the foundation of human production and life. The production of industrial, mining and smelting plants and the dumping of waste will inevitably pollute the surrounding soil, and agricultural production activities on the polluted soil will inevitably cause food safety problems; with the "National Soil Pollution ...

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Problems solved by technology

[0005] Existing many patents have disclosed the method of soil pollution control: for example, Chinese invention patent application CN 102559198 A discloses that low-grade phosphate rock powder is used as the main raw material, and ammonium oxalate is mixed as a raw material to make a passivator, which is used for passivating copper, Lead and cadmium compound polluted farmland, although the process is simple and the cost is low, but this phosphate passivator may weakly reduce the pH value of the soil, resulting in an increase in the content of some ionic heavy metals; and the phosphate passivator The passivation effect on polluted soil is closely related to the type of heavy metal, soil properties, water content and remediation time. For example, if phosphate passivator is applied in red soil, the effective state of copper will be significantly reduced, but not in yellow soil. effect; it may be related to the variable charge of red soil containing more clay minerals and iron-aluminum oxides, while the rich organic matter and cation exchange capacity in yellow soil make the soil itself absorb more copper, resulting in the addition of phosphate to copper. The adsorption did not increase significantly

[0006] Chinese invention patent application CN 105950154 A discloses a passivator made of biochar, red mud, and ammonium phosphate in a certain proportion, which is used for remediation of cadmium and lead compound polluted soil. Charcoal needs to be prepared under the condition of high temperature and hypoxia at 350 degrees Celsius, the process is complicated, the cost is high, and it is difficult to widely promote

[0007] Chinese invention patent application (CN 105542775 A) discloses a passivator prepared from modified bio-carbon and compound materials rich in calcium, magnesium, silicon and other elements, which also has the disadvantages of complicated process and high cost

[0008] Some researchers have explored new materials for remediation of heavy metal-contaminated soils. For example, after using natural clay as a template to synthesize nanomaterials, using the unique structural properties of clay, the synthesized nanomaterials have the characteristics of small size and strong reactivity. With a special surface structure and particle size, it has a better repair effect at a lower application rate, but the cost of obtaining this nanomaterial is relatively high, and it is unrealistic to use it for large-scale promotion

[0009] Although there are many studies on passivators, there is no research on the remediation of cadmium, chromium (with hexavalent chromium), copper, and nickel compound polluted farmland around abandoned mines.

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