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Fixing agent for repairing lead-cadmium contaminated soil and preparation and application methods thereof

A technology for cadmium-contaminated soil and a fixative, applied in the field of soil remediation, can solve problems such as soil acidification, secondary pollution, etc., and achieve the effects of low cost, unbreakable, and improved mechanical properties

Active Publication Date: 2015-04-22
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The research on the remediation technology of polluted soil has become the focus of environmental protection engineering science and technology research. At present, the commonly used remediation methods of contaminated soil include soil rinsing technology, electric remediation technology, electrothermal remediation technology, and soil stabilization technology. The remediation agent precipitates and adsorbs heavy metals to reduce the biologically available state of heavy metals in the soil, but this method is likely to cause secondary pollution
[0004] Experiments have found that phosphate has a good precipitation effect on lead and cadmium, but the addition of a large amount of phosphate can easily cause eutrophication of the water body and acidification of the soil

Method used

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  • Fixing agent for repairing lead-cadmium contaminated soil and preparation and application methods thereof
  • Fixing agent for repairing lead-cadmium contaminated soil and preparation and application methods thereof
  • Fixing agent for repairing lead-cadmium contaminated soil and preparation and application methods thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Embodiment 1 prepares fixing agent of the present invention:

[0039] (1) Heat polyvinyl alcohol in water to not lower than 80°C, stir and dissolve;

[0040] (2) Sprinkle calcium dihydrogen phosphate powder into the solution described in step (1), and stir well;

[0041] (3) Sodium bicarbonate is added in the solution described in step (2);

[0042] (4) Sprinkle the sodium alginate powder evenly and slowly into the solution described in step (3), continue heating and stirring, keep the temperature above 80°C, and cool the mixture after stirring for 10 minutes;

[0043] (5) Prepare a certain amount of saturated boric acid solution, add a certain amount of calcium chloride powder, adjust the pH value to 6.5-7.0 with sodium hydroxide, and make a cross-linking liquid;

[0044] (6) drop the solution described in step (4) into the cross-linking solution described in step (5), and let it stand for 12-24h to form pellets;

[0045] (7) Rinse the pellets described in step (6) ...

Embodiment 2

[0056] The test soil was taken from the paddy soil around a lead-zinc tailings pond in Hunan. The soil for testing was air-dried naturally after removal of gravel and broken roots, mixed in quarters, and crushed through a 20-mesh nylon sieve. The pH value of the soil is 3.9, and the contents of water-soluble, available and total Cd and Pb in the soil are shown in Table 1.

[0057] Table 1 Basic properties of the tested soil

[0058]

[0059] Add 0.2g of fixative into 5g of soil, stir evenly, add 5ml of water, fix for a week, use 25ml DTPA to extract the effective state of lead and cadmium in the soil, the fixing rate of the effective state of lead reaches 61%, cadmium The fixation rate of the water-soluble lead and cadmium in the soil is extracted with 50ml of deionized water, the fixation rate of the water-soluble lead is 90%, and the cadmium is 85%.

Embodiment 3

[0061] The soil for testing was taken from the paddy field in the suburbs of Changsha City, Hunan Province. 20 mg / kg of cadmium was added to the paddy soil, and the test was carried out after one month of maturation. The effective lead and cadmium contents of the soil are 3475.89mg / kg and 15mg / kg respectively, the water soluble lead and cadmium contents are 710mg / kg and 10mg / kg respectively, and the pH value is 5.3.

[0062] Add 20ml of water to 10g of soil, soak for 48 hours, add fixative according to the ratio of 0.5%, 1%, 2%, 3%, and 4% of the soil mass, shake for 2 hours and mix well, and after fixing for 7 days, measure the water-soluble state of the soil and DTPA leached state lead and cadmium content. When the fixing agent and soil ratio were 4%, the fixing rate of cadmium reached 39.01%, and the fixing rate of lead was 38.31% (see figure 1 ).

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Abstract

The invention discloses a fixing agent for repairing lead-cadmium contaminated soil and preparation and application methods thereof. The preparation method of the fixing agent comprises the following steps: 1) dissolving polyvinyl alcohol in water by heating; 2) pouring calcium dihydrogen phosphate into a solution; 3) adding sodium bicarbonate; 4) adding sodium alginate and carrying out magnetic stirring; and 5) dropping the above solution with a syringe into a saturated boric acid and calcium chloride cross-linked fluid so as to prepare the fixing agent. The fixing agent is applied to lead-cadmium contaminated soil. By the use of the fixing agent, fixed rate of available lead and fixed rate of available cadmium respectively reach 61% and 38%.

Description

technical field [0001] The invention belongs to the field of soil remediation, and relates to a lead and cadmium fixative for soil, its preparation and application in soil remediation. Background technique [0002] my country is rich in mineral resources. The mining of metal minerals has caused serious pollution to the soil in some areas. Due to the pollution of the land, the heavy metal content in rice in many areas has exceeded the standard seriously. Among them, cadmium and lead have received widespread attention from the society. [0003] Soil remediation is a technical measure to restore polluted soil to normal functions. It refers to the use of physical, chemical and biological methods to transfer, absorb, degrade and transform pollutants in the soil, reduce its concentration to an acceptable level, or reduce the toxic Harmful pollutants are converted into harmless substances. The research on the remediation technology of polluted soil has become the focus of environm...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K17/40B09C1/08C09K101/00
CPCB09C1/08C09K17/40C09K2101/00
Inventor 杨志辉柴立元姚文斌王云燕梁丽芬肖睿洋杨卫春
Owner CENT SOUTH UNIV
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