A kind of passivation method of heavy metal polluted farmland soil
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A technology for contaminated soil and heavy metals, applied in the restoration of contaminated soil, etc., can solve the problems of excessive, difficult to distinguish the actual action and interaction of passivators, and difficult to further improve the removal effect of heavy metals
Active Publication Date: 2020-12-08
CHINESE ACAD OF ENVIRONMENTAL PLANNING
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[0006] Chinese invention patents CN201711464010, CN201610596960, CN201710178365, CN201810365538, CN201610079842 and many other existing technologies disclose the method of soil passivation and the passivating agent used in the method, which is mainly by mixing different types of passivating agents with soil to It reacts with heavy metals to passivate them, but the principle of removing heavy metals is different for each type of passivating agent, it is difficult to distinguish the actual effect and interaction of each passivating agent, and it is difficult to further improve the removal effect of heavy metals
Moreover, in the prior art, many actions such as adsorption and chemical actions are carried out simultaneously, which may have restrictive effects between different actions.
Chinese invention patent CN201710902422 discloses a technical solution to remove heavy metals in the soil by first adding an adsorbent and then adding a chemical reaction reagent. However, the heavy metals may be partially excessive in the soil if the heavy metals are adsorbed first, which may have an adverse effect on further improving soil passivation.
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Embodiment 1
[0029] 1) Add 4g of ferric oxide, 2g of calcium carbonate, and 2g of calcium hydroxyphosphate into 1kg of heavy metal-contaminated soil, stir evenly, and let stand for 20 minutes;
[0030] 2) Add 5 g of plant ash and 10 g of calcium-based bentonite to the mixture obtained in step 1), stir evenly, and let stand for 20 minutes;
[0031] 3) Spray tap water into the mixture obtained in step 2), adjust the water content by weight to 30%, stir evenly, and let it stand for 3 days for maintenance.
Embodiment 2
[0033] 1) Add 3g of ferric oxide, 3.5g of calcium carbonate and 1.5g of calcium hydroxyphosphate into 1kg of heavy metal-contaminated soil, stir evenly, and let stand for 30 minutes;
[0034]2) Add 2 g of plant ash and 13 g of calcium-based bentonite to the mixture obtained in step 1), stir evenly, and let stand for 10 minutes for curing;
[0035] 3) Spray tap water into the mixture obtained in step 2), adjust the water content by weight to 30%, stir evenly, and let it stand for 3 days for curing.
Embodiment 3
[0037] 1) Add 4.5g of ferric oxide, 1g of calcium carbonate and 2.5g of calcium hydroxyphosphate into 1kg of heavy metal-contaminated soil, stir evenly, and let stand for 10 minutes;
[0038] 2) Add 9g of plant ash and 6g of calcium-based bentonite to the mixture obtained in step 1), stir evenly, and let it stand for curing for 30 minutes;
[0039] 3) Spray tap water into the mixture obtained in step 2), adjust the water content by weight to 30%, stir evenly, and let it stand for 3 days for curing.
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Abstract
The invention relates to a passivation method for heavy metal-contaminated farmland soil, which comprises the following steps: 1) adding a passivator that mainly plays a role in chemical reaction into the heavy metal-contaminated soil, stirring evenly, and standing for maintenance; Adding a passivating agent mainly for adsorption to the obtained mixture, stirring evenly, and standing for curing; 3) adding water to the mixture obtained in step 2), adjusting the weight moisture content to 20%-40%, and standing for curing. The present invention combines ferric oxide, calcium carbonate, hydroxycalcium phosphate, plant ash, and bentonite and uses them step by step to give full play to the advantages of chemical complexation, precipitation, and physical adsorption of heavy metal pollutants of different passivation materials. Combined together, an economical, efficient, green, and environmentally friendly heavy metal passivation agent and its restoration method have been established, effectively realizing the effective restoration of heavy metal-contaminated farmland.
Description
technical field [0001] The invention belongs to the field of soil remediation in the technical field of environmental engineering, and in particular relates to a passivation method for farmland soil polluted by heavy metals. Background technique [0002] Soil heavy metal pollution has become one of the main environmental pollution problems in my country. With the continuous and rapid development of industries involving heavy metals such as mining, metal smelting, chemical industry, and battery manufacturing, the discharge of heavy metal pollutants has also increased year by year. In addition, the problems of excessive discharge of pollutants by some illegal enterprises have made my country's heavy metal pollution a high incidence. situation. The area of cultivated land polluted by heavy metals in different degrees in my country is close to 10 million hm 2 , Every year due to heavy metal pollution, grain production is reduced by more than 10 million tons, and grains pollut...
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