Method for rapidly removing and recycling hexavalent chromium from chromium-contaminated soil

A technology of chromium-contaminated soil and hexavalent chromium, applied in the field of environmental pollution restoration, can solve the problems of long time consumption, long time consumption of chemical cleaning, and small biomass

Inactive Publication Date: 2013-05-29
INST OF URBAN ENVIRONMENT CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these repair techniques and methods have their own shortcomings.
The cost of immobilization / stabilization method is high, and the treatment effect is not good; the chemical reduction method is easy to cause secondary pollution of the soil, and how to remove Cr(VI) in the soil is the difficulty of this technology; the chemical cleaning method takes a long time And it is only suitable for soil with a large permeability coefficient (such as sandy soil, etc.), and it is easy to cause secondary pollution of the soil when the cleaning solution is introduced; electrodynamic restoration has achieved good results in the treatment of Cr (VI) pollution, but electrodynamic restoration has achieved good results. Restoration consumes energy, which increases the repair cost, and with time, the repair efficiency decreases rapidly while the energy consumption increases sharply; phytoremediation is an emerging repair technology, but there are few Cr(VI) super-accumulating plants found so far, and most of them grow Slow, small biomass, often time-consuming and slow to take effect; microbial remediation is considered to be a promising remediation technology, soil microorganisms mainly directly reduce Cr(VI) to Cr(III) through metabolic processes, but microbial remediation It is greatly affected by various environmental factors, and when the content of Cr(VI) in the soil is high, it cannot play a good role
Most of the above restoration technologies reduce the toxicity of chromium by changing its chemical properties, and the converted Cr(III) also has a certain degree of toxicity

Method used

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  • Method for rapidly removing and recycling hexavalent chromium from chromium-contaminated soil
  • Method for rapidly removing and recycling hexavalent chromium from chromium-contaminated soil
  • Method for rapidly removing and recycling hexavalent chromium from chromium-contaminated soil

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Example 1: The soil is neutral paddy soil in Xiamen, and chromium is added to the soil in the form of potassium dichromate. The initial concentration of hexavalent chromium is 1000 mg / Kg, and the maximum water content of the soil is kept at 30%. After two months of equilibrium, the concentration of hexavalent chromium in the soil is It is 560 mg / Kg. The carbon material is an inexpensive carbon felt in the industry. Set a carbon felt with a thickness of 0.217 cm and a circle with a diameter of 2.330 cm, soak it in water to make it reach the maximum water content. The carbon felt taken out was buried in the above-mentioned hexavalent chromium-balanced soil, and the thickness of the soil above and below the carbon felt was set to be 1 cm. After putting the carbon felt into the soil for 2 hours, the removal effect of the carbon felt on the soil hexavalent chromium basically reached a balance, and the removal rate was about 25% ( figure 1 ). The removal rate increased s...

Embodiment 2

[0018] Example 2: The operation was as in Example 1, except that different initial chromium concentrations were set. After two months of equilibrium, the hexavalent chromium concentrations in the soil were 25, 135, 375, 560, 578, 1200, and 1472 mg / Kg, respectively. After putting carbon felt into the soil for 24 hours, except that the removal rate of hexavalent chromium in the soil with 25 mg / Kg hexavalent chromium reached 40%, the removal rate of hexavalent chromium in other chromium pollution remained at 30%. %about( figure 2 ). It shows that carbon felt can be applied to the removal of hexavalent chromium in soil with a wide range of chromium pollution levels.

Embodiment 3

[0019] Example 3: The operation was the same as in Example 1, except that the same treatment of chromium-contaminated soil was added several times with carbon felt to remove hexavalent chromium from the soil. With the addition of carbon felt, the concentration of hexavalent chromium in the soil decreased significantly. After 11 additions of carbon felt, the concentration of hexavalent chromium in the chromium-contaminated soil decreased from the initial 560 mg / Kg to 12 mg / Kg ( image 3 ).

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Abstract

The invention discloses a method for rapidly removing and recycling hexavalent chromium from chromium-contaminated soil. According to the method, an industrial low-cost high-temperature burned carbon material is used. the method comprises the following operation processes of: burying the carbon material with the maximum moisture content in the chromium-contaminated soil with the maximum moisture content; taking out the carbon material after 24 hours, placing in water and carrying out ultrasound elution for 1 hour for recycling the hexavalent chromium; continuously placing the eluted carbon material in the chromium-contaminated soil with the maximum moisture content to remove the hexavalent chromium; repeating the process; and gradually removing the hexavalent chromium out of the soil with addition of the carbon material, wherein the hexavalent chromium is transferred to a simple water system, thus the purpose of recycling the hexavalent chromium is fulfilled. Relative to hexavalent chromium in the complex soil system, hexavalent chromium in the water system is easier to remove. Aiming at shortcomings of a conventional chromium-contaminated soil remediation method and technology, the method for removing and recycling the hexavalent chromium from the chromium-contaminated soil, which is provided by the invention, is simple to operate, quick and effective, low in operation cost and pollution-free.

Description

technical field [0001] The invention relates to a method for quickly removing and recovering hexavalent chromium in chromium-contaminated soil, which removes, transfers and recycles hexavalent chromium in chromium-contaminated soil, and belongs to the field of environmental pollution restoration. Background technique [0002] Soil pollution has become a serious environmental pollution problem, especially heavy metal pollution in soil is difficult to remove, and it is an important factor that endangers human health today. At present, the research on soil heavy metal pollution control and remediation is the focus and hotspot of environmental pollution control research. Heavy metals cannot be biodegraded, and are difficult to eliminate after entering the soil. Their existing forms and valence states are different under different conditions, and their activity and toxicity are also different. Among the many heavy metal elements that pollute the soil environment, chromium (Cr) i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/00
Inventor 王超曹昌丽赵峰
Owner INST OF URBAN ENVIRONMENT CHINESE ACAD OF SCI
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