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A fixative for repairing lead and cadmium polluted soil and its preparation and application method

A technology of cadmium-contaminated soil and its application method, which is applied in the field of soil lead-cadmium fixative and its preparation and application in soil remediation, can solve the problems of soil acidification, secondary pollution, etc., and achieve low cost, unbreakable, high mechanical properties Improved effect

Active Publication Date: 2017-11-17
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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  • A fixative for repairing lead and cadmium polluted soil and its preparation and application method
  • A fixative for repairing lead and cadmium polluted soil and its preparation and application method
  • A fixative for repairing lead and cadmium polluted soil and its preparation and application method

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Comparison scheme
Effect test

Embodiment 1

[0038] Example 1 Preparation of fixative of the present invention:

[0039] (1) Heating polyvinyl alcohol in water to not less than 80°C, stirring and dissolving;

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

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

[0042] (4) evenly and slowly sprinkle sodium alginate powder 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, and adjust the pH value with sodium hydroxide to 6.5-7.0 to make a cross-linking solution;

[0044] (6) drop the solution described in step (4) into the cross-linking solution described in step (5), and let 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 test soil was air-dried after removing the gravel and broken roots, mixed well by quarter method, and crushed through a 20-mesh nylon sieve. The soil pH was 3.9, and the water-soluble, available, and total Cd and Pb contents in the soil were shown in Table 1.

[0057] Table 1 Basic properties of the tested soils

[0058]

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

Embodiment 3

[0061] The test soil was taken from a paddy field in the suburbs of Changsha, Hunan Province. 20 mg / kg of cadmium was added to the paddy soil, and the experiment was carried out after curing for one month. The available lead and cadmium contents of the soil were 3475.89mg / kg and 15mg / kg respectively, the water-soluble lead and cadmium contents were 710mg / kg and 10mg / kg respectively, and the pH value was 5.3.

[0062] Add 20ml of water to 10g of soil, soak it for 48 hours, add the fixative in proportions of 0.5%, 1%, 2%, 3%, and 4% of the soil mass, shake it for 2 hours, and mix it up. DTPA-leached lead and cadmium content. When the ratio of fixative to soil is 4%, the fixation rate of cadmium reaches 39.01%, and the fixation rate of lead is 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 restoration, and relates to a soil lead-cadmium fixative and its preparation and application in soil restoration. Background technique [0002] my country is rich in mineral resources, and the mining of metal minerals has caused serious pollution to the soil in some areas. Due to the pollution of the land, the content of heavy metals in rice in many areas is seriously exceeding the standard. Among them, cadmium and lead have been widely concerned by the society. [0003] Soil remediation is a technical measure to restore the normal function of polluted soil, which refers to the use of physical, chemical and biological methods to transfer, absorb, degrade and transform pollutants in soil to reduce their concentration to acceptable levels, or to reduce toxic pollutants. Harmful pollutants are converted into harmless substances. The research on the remediation technology of polluted soil has become the focus of ...

Claims

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Application Information

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Patent Type & Authority Patents(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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