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Chemical leaching restoring method for soil polluted by heavy metals

A technology of contaminated soil and chemical leaching, which is applied in the field of chemical remediation of heavy metal-contaminated soil, can solve the problems of long cycle time, bacteria culture and difficulty in universal application, and achieve the effect of reducing heavy metals, reducing the number of residues, and high remediation efficiency

Active Publication Date: 2012-06-20
CENT SOUTH UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Heavy metal hyperaccumulation phytoremediation is suitable for large-scale contaminated soil remediation, and the cycle is long. Microbial remediation is often used in combination with other remediation technologies to achieve the purpose of remediation, but the cultivation and universality of bacteria are a major difficulty

Method used

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  • Chemical leaching restoring method for soil polluted by heavy metals
  • Chemical leaching restoring method for soil polluted by heavy metals
  • Chemical leaching restoring method for soil polluted by heavy metals

Examples

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Effect test

Embodiment 1

[0034]Example 1: Soil column leaching repairs cadmium lead polluted calcareous soil

[0035] Polluted soil in Dongdagou, Baiyin City, Gansu, was excavated and broken down to clods smaller than 2cm. Take 1 kg of crushed soil and put it into a plexiglass soil column with a diameter of 8 cm and a height of 30 cm, and the soil height is 20 cm. The bottom of the soil column is a plexiglass plate with a slope of 5 degrees and small holes to facilitate the drainage of seepage. Use a peristaltic pump with a flow rate of 100ml / h to pump 2L of Na with a concentration of 0.04mol / l 2 The EDTA solution was slowly rinsed from the top, and the filtrate was collected from the bottom of the soil column, and the contents of Cd and Pb in the filtrate were measured. The collected filtrate was washed with Ca(OH) 2 Adjust the pH to 10.0, then add solid Na according to 11 times the moles of Cd and Pb 2 S·9H 2 O, after standing for 40min, add PAM (0.3% polyacrylamide) at 6ml / l, stir, and filter....

Embodiment 2

[0040] Example 2: Field heap leaching repairs cadmium lead polluted calcareous soil

[0041] The polluted soil in Dongdagou, Baiyin City, Gansu Province was broken into clods less than 2cm by excavation and rotary tillage. The crushed soil was built into a mound of 12.5 tons (6×8×0.2m), and plastic was laid under the mound to prevent leakage. The flow rate is 1.5m 3 / h acid-resistant pump extracts Na with a concentration of 0.04mol / l 2 EDTA solution is slowly rinsed from the top, and the amount of rinse agent is 25M 3 . The filtrate was collected from the bottom of the mound, and the content of Cd and Pb in the eluate was determined. Filtrate with Ca(OH) 2 Adjust the pH to 10.0, then add solid Na according to 11 times the total moles of Cd and Pb 2 S·9H 2 O, after standing for 40min, add PAM (3% polyacrylamide) at 6ml / l and stir to clarify. The supernatant continued to wash the soil through the peristaltic pump, and the above steps were repeated for 3 times to wash the...

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Abstract

The invention discloses a chemical leaching restoring method for soil polluted by heavy metals. Na2EDTA solution is utilized to perform leaching to the soil polluted by the heavy metals, available cadmium and lead in the soil are effectively removed, Na2S.9H2O is utilized to precipitate the heavy metals in filtrate, Na2EDTA is released again, and repeated recycling of the Na2EDTA solution is achieved. After recycling, the Na2EDTA solution carries out leaching to the soil polluted by the heavy metals, the removing rate of available Cd in the polluted soil reaches 81.6-81.8%, and the removing rate of available Pb reaches 55.9-60.1%. The chemical leaching restoring method for the soil polluted by the heavy metals overcomes the shortcomings that an existing method for the Na2EDTA solution to perform leaching to the soil polluted by the heavy metals causes chemical cost to be large, generated filtrate is much, and the follow-up treatment is troublesome. Simultaneously, the chemical leaching restoring method for the soil polluted by the heavy metals has the advantages of being simple in process, becoming effective quickly, enabling a leaching agent to be reused, and enabling the heavy metals to be effectively eliminated.

Description

technical field [0001] The invention relates to the field of chemical restoration of soil polluted by heavy metals, in particular to a method for chemical leaching restoration of cadmium and lead compound polluted soil. Background technique [0002] Soil heavy metal pollution has threatened the ecological environment, food safety and sustainable agricultural development. Every year, 12 million tons of grains are polluted by heavy metals nationwide, causing direct economic losses of more than 20 billion yuan. Due to the long-term, hidden and irreversible characteristics of heavy metal pollution in soil, it is difficult to control once it is polluted. In addition, heavy metals are easy to accumulate in crops and enter the human body through the food chain, causing various diseases and ultimately endangering human health. [0003] Cadmium (Cd) is an element that is harmful to the environment. It is collectively called "five poisons" together with lead (Pb), chromium (Cr), mer...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/08
Inventor 杨志辉柴立元王庆伟闵小波张淑娟李倩袁平夫
Owner CENT SOUTH UNIV
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