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Composite chemical leaching method for remediation of heavy metal contaminated soil

A technology of polluted soil and chemical leaching, applied in the restoration of polluted soil, etc., can solve the problems of troublesome follow-up treatment, high cost of chemicals, and large soil damage, etc., and achieve short leaching time, low price, and high restoration efficiency Effect

Active Publication Date: 2013-10-23
NANJING AGRICULTURAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to aim at the above-mentioned deficiency of existing rinsing technology, has overcome the existing method for rinsing heavy metal polluted soil with solutions such as EDTA, organic acid, inorganic acid and inorganic salt alone, cost of medicament is big, produces secondary pollution, and is harmful to For the problem of large soil damage and troublesome follow-up treatment, a chemical leaching method for repairing heavy metal (cadmium, lead) polluted soil is provided

Method used

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  • Composite chemical leaching method for remediation of heavy metal contaminated soil
  • Composite chemical leaching method for remediation of heavy metal contaminated soil
  • Composite chemical leaching method for remediation of heavy metal contaminated soil

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Heavy metal contaminated soil in Zhuzhou, Hunan (Cd content 6.68 mg / kg, Pb content 787.76 mg / kg), the contaminated soil was ground and passed through a 2mm sieve; several parts of soil were weighed, 5 grams each, placed in a centrifuge tube, each Add 10 mL of the composite eluent prepared by ferric chloride and citric acid, the concentrations of ferric chloride and citric acid in each composite eluent are shown in Table 1 and Table 2; place the centrifuge tube in a constant temperature shaker , control the washing temperature at 25°C, and the oscillation rate at 200 rpm. After 24 hours of oscillation washing, take out the centrifuge tube; place it in a centrifuge, centrifuge at a rate of 5000 rpm for 5 minutes, and pour off the composite washing tube. Wash solution; add 10mL of distilled water to the centrifuge tube, rinse at the same temperature, shaking rate and rinse time as above, then centrifuge at 5000 rpm for 5 minutes, pour off the supernatant; use distilled wate...

Embodiment 2

[0036]Heavy metal contaminated soil in Zhuzhou, Hunan (Cd content 6.68 mg / kg, Pb content 787.76 mg / kg), the contaminated soil was ground and passed through a 2mm sieve; several parts of soil were weighed, 5 grams each, placed in a centrifuge tube, each Add 10mL of composite eluent prepared by ferric chloride and citric acid, and the concentrations of ferric chloride and tartaric acid in each composite eluent are shown in Table 3 and Table 4; the centrifuge tube is placed in a constant temperature shaker, Control the rinsing temperature to 25°C, and the oscillation rate to 200 rpm. After 24 hours of oscillating rinsing, take out the centrifuge tube; place it in a centrifuge, centrifuge at 5000 rpm for 5 minutes, and pour off the combined rinsing Then add 10mL of distilled water to the centrifuge tube, the rinsing temperature, shaking rate and rinsing time are the same as above, then centrifuge at 5000 rpm for 5 minutes, pour off the supernatant; use distilled water under the sam...

Embodiment 3

[0043] Heavy metal contaminated soil in Zhuzhou, Hunan (Cd content 6.68 mg / kg, Pb content 787.76 mg / kg), the contaminated soil was ground and passed through a 2mm sieve; several parts of soil were weighed, 5 grams each, placed in a centrifuge tube, each Add the composite eluent 10mL that is prepared by ferric chloride and malic acid, the concentration of ferric chloride and malic acid in every part of composite eluent is as shown in table 5 and table 6; other test methods are the same as embodiment 1, get Repaired soil.

[0044] Table 5 Cd removal rate (%) in the washing process

[0045]

[0046] Table 6 Pb removal rate (%) in the washing process

[0047]

[0048] After chemical leaching, the cadmium content in the soil can be reduced from the original 6.68mg / kg to 1.28mg / kg at most, and the removal rate of cadmium can be as high as 80.81%; the lead content can be reduced from the original 787.76 mg / kg to 353.70mg / kg at most. kg, the removal rate of lead was up to 55.1...

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Abstract

The invention discloses a composite chemical leaching method for remediation of heavy metal contaminated soil. The method includes: leaching heavy metal contaminated soil 1-3 times by a composite leacheate prepared from ferric chloride and an organic acid, then further conducting leaching 1-3 time with distilled water, and finally separating the leacheate from soil. The method provided in the invention has the advantages of good treatment effect, short leaching time, no secondary pollution, simple operation, relative low cost, a highest cadmium removal rate of over 80%, and a highest lead removal rate of over 55%. The iron-containing compound involved in the invention is used as an improver of paddy soil. The residue of ferric chloride has a positive effect on chemical properties of soil, and cannot destroy the soil structure. The used organic acid is easy to degrade, and the degradation product can become nutrients of plants and is environment-friendly. The final leaching by water can reduce the content of metal ions and the leacheate residue in the remedied soil, thus being in favor of later crop tilling.

Description

technical field [0001] The invention relates to soil heavy metal pollution control technology, in particular to a chemical leaching method for repairing heavy metal polluted soil. Background technique [0002] In recent decades, the process of industrialization and urbanization has been accelerating, and the problem of soil pollution has become increasingly prominent. Chemical plants that were originally located in urban areas or suburbs have been relocated one after another. It is an inevitable trend that their legacy land be included in urban construction planning. Industrial production activities lead to the enrichment of high-concentration heavy metals in chemical plant sites, and the diffusion to groundwater and adjacent areas, which is a huge hidden danger to surrounding agricultural production and residents' lives. Heavy metals have the characteristics of long residual time, strong concealment, and high toxicity. They cannot be degraded by microorganisms. Once they en...

Claims

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Application Information

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IPC IPC(8): B09C1/08
Inventor 董长勋李玉姣赵道远吴华卢爱民吴龙华胡鹏杰许海波刘培亚赵婕
Owner NANJING AGRICULTURAL UNIVERSITY
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