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Composite eluting agent for restoring Cd and Pb contaminated soil and application method thereof

A technology of composite leaching agent and polluted soil, which is applied in the field of compound leaching agent and leaching agent preparation in chemical leaching repair, which can solve the problems of low leaching efficiency and achieve good economic benefits, easy acquisition, and configuration process Simple and convenient effect

Inactive Publication Date: 2017-02-22
BEIJING XINYUAN ENVIRONMENT CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The key to chemical leaching is to find an effective eluent. From the perspective of environmental protection, it is best to use clean water directly as the eluent, but this method is not efficient. In order to improve the elution efficiency of the eluent, the leaching process will Add chemical reagents, surfactants, ion complexing agents, etc.

Method used

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  • Composite eluting agent for restoring Cd and Pb contaminated soil and application method thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Weigh 5.00g of soil contaminated with heavy metals containing Cd and Pb, wherein the concentrations of Cd and Pb are 18.6mg / kg and 549.6mg / kg, respectively. The soil is pretreated before use, and branches, stones, etc. are picked out, ground and passed through a 100-mesh sieve for later use. The eluent is EDTA and citric acid solution, the concentrations of EDTA and citric acid are 0.05mol / L and 0.1mol / L respectively; add 40ml of 1+1 eluent (the ratio of soil to water is 1:8) and centrifuge placed in a shaker at room temperature for 3 h at 250 rpm, centrifuged at 3000 rpm for 20 min, and the supernatant was discarded after solid-liquid separation. Continue to add 40ml eluent (stock solution) to the residual soil, shake for 5 hours, centrifuge at 3000 rpm for 20 minutes, and discard the supernatant after solid-liquid separation. Clean soil can be obtained after the residual soil is washed and shaken with water. The soil after leaching was taken to measure the remaining...

Embodiment 2

[0024] The test uses a mixed eluent of EDTA and humic acid to carry out chemical leaching and remediation of Cd and Pb contaminated soil. The solid-liquid ratio of the process is 1:10, and the shaking time is 3 hours. After the solid-liquid separation, the supernatant is discarded, and the residual soil can be washed and shaken with water to obtain clean soil. The changes of soil heavy metals Cd and Pb before and after leaching are shown in the table below.

[0025]

[0026] It can be seen from the test results that after leaching with the mixed eluent of EDTA and humic acid, the reduction rates of soil Cd are 87.1%, 84.3%, and the reduction rates of soil Pb are 68.5%, 71.9%. After leaching, the content of heavy metals in the soil was greatly reduced.

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Abstract

A composite eluting agent for restoring Cd and Pb contaminated soil and an application method thereof belong to the technical field of soil restoration. The eluting agent is prepared mainly from EDTA (ethylenediaminetetraacetic acid) and an organic acid, wherein the organic acid is from one or any of oxalic acid, lactic acid, citric acid, humic acid, and fulvic acid. The application method of the composite eluting agent comprises the steps of (1) subjecting contaminated soil to simple crushing, and screening to remove large foreign matters and stone; (2) adding an eluting agent to the contaminated soil, keeping soil-water ratio to 1:5 to 1:10, and stirring with the soil for 2-4 h; (3) after solid-liquid separation, treating the eluting agent for recycling, adding the composite eluting agent to the contaminated soil, and stirring again for 3-6 h; (4), carrying out solid-liquid separation, and adding tap water for cleaning and eluting to obtain clean soil. By means of multi-step elution and using composite eluting agents different in concentrations, it is possible to effectively reduce Cd and Pb in soil; the method is a truly practical and economically practical eluting method.

Description

[0001] technology neighborhood [0002] The invention belongs to the technical field of contaminated soil remediation, and in particular relates to preparation and use methods of a leaching agent in chemical leaching remediation. Background technique [0003] Due to the increasing pollution caused by human economic activities, the area of ​​soil pollution in many areas of the world is currently expanding, and the problem of soil pollution by heavy metals is particularly prominent. Irrigation of farmland with sewage containing heavy metals, agricultural utilization of sludge, application of chemical fertilizers and pesticides, and settlement of floating dust in mining areas have caused many soils on the earth to be or will be polluted by heavy metals. Soil heavy metal pollution can lead to serious direct economic losses, degrade food quality, endanger human health, and cause other environmental problems. The research on soil heavy metal pollution and its control methods has be...

Claims

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Application Information

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IPC IPC(8): C09K17/14B09C1/02B09C1/08C09K101/00
CPCC09K17/14B09C1/02B09C1/08C09K2101/00
Inventor 周建强韩君徐愿坚杨立鹏周敏高涛陈卫文何玉龙张如意王蕾凡祖伟
Owner BEIJING XINYUAN ENVIRONMENT CO LTD
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