Farmland polluted soil heavy-metal passivating agent as well as preparation and application methods thereof

Abstract

The invention discloses a farmland polluted soil heavy-metal passivating agent as well as preparation and application methods thereof. The farmland polluted soil heavy-metal passivating agent is prepared from the following components: 20 percent to 40 percent of calcium oxide, 3 percent to 10 percent of sulfide, 3 percent to 15 percent of ferrite, 5 percent to 10 percent of plant ash, 5 percent to 10 percent of volcanic rock, 10 percent to 30 percent of natural silicate clay mineral and 15 percent to 30 percent of nano hydroxyapatite. The preparation method comprises the following steps: (1) weighing the natural silicate clay mineral in percentage by mass and crushing; carrying out ball milling and sieving until the fineness is 60 to 100 meshes to obtain powder for later use; (2) mixing nitrate and hydroxy acid according to the ratio of 1 to 1; after reacting, filtering; washing with de-ionized water and precipitating to obtain the nano hydroxyapatite; (3) weighing the calcium oxide, the sulfide and the ferrite in percentage by mass and uniformly mixing the calcium oxide, the sulfide and the ferrite with the natural silicate clay mineral and the nano hydroxyapatite and drying a mixture to obtain the farmland polluted soil heavy-metal passivating agent. The heavy-metal passivating agent disclosed by the invention has the advantages of short treatment time, rapid effect, strong repairing capability and easiness of obtaining the raw materials and is suitable for popularization.

Description

technical field [0001] The invention belongs to the technical field of remediation of heavy metal-contaminated soil, and in particular relates to a method for preparing and using a heavy metal passivator for farmland polluted soil. Background technique [0002] Due to atmospheric deposition, sewage irrigation, and excessive use of fertilizers, pollutants containing heavy metals enter farmland through various channels, resulting in increasingly serious heavy metal pollution in farmland soil. Because heavy metals cannot be degraded by microorganisms, it is difficult to eliminate them. When they accumulate in the soil to a certain extent, they will cause toxicity to the soil-plant system, resulting in degradation of soil quality, reduction of crop yield and quality, and deterioration of the hydrological environment. The phenomenon of level amplification will endanger human health. In southern China, acid rain can increase the leaching of heavy metals from the soil and increase...

AI Technical Summary

Problems solved by technology

Physical remediation can efficiently remove heavy metals, but it is not suitable for large-scale soil pollution remediation due to the large amount of work and high cost

Chemical remediation includes chemical leaching and chemical performance improvement, etc. The chemical leaching process is complicated, seriously damages the soil structure and physical and chemical properties, and is prone to secondary pollution; while chemical performance improvement mainly adds organic matter and passivating agents to the soil. Reducing the bioavailability of heavy metals, this method is economical and easy to operate, and has been widely used at present, but the stability of the treatment effect and the problems of secondary pollution have not been effectively resolved

Bioremediation mainly includes phytoremediation and microbial remediation, etc. The effect of bioremediation is stable, reliable, and free of secondary pollution, but the general remediation period is long, the efficiency is low, and it is not suitable for heavily polluted soils.

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