Method for removing hexavalent chromium from polluted soil

A technology for chromium-contaminated soil and hexavalent chromium, which is applied in the field of removing hexavalent chromium pollution in soil, can solve problems such as inability to reduce hexavalent chromium content, inability to achieve metal chromium transfer and separation, inability to effectively remove secondary pollution, etc., to achieve reduction Effect of hexavalent chromium concentration

Active Publication Date: 2015-01-28
青海省环境科学研究设计院有限公司
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Problems solved by technology

[0004] Patent CN102500612A uses Na 2 EDTA solution washes heavy metal-contaminated soil to effectively remove effective cadmium and lead in the soil; patent CN102247980A uses a mixture of citric acid and pyrolusite as a leaching agent for chromium-contaminated soil, and the weight percentages of citric acid and pyrolusite are 95-99% respectively and 1-5%; CN103521513A uses reducing agent iron powder or sodium metabisulfite to reduce hexavalent chromium to trivalent chromium, but the problem with this method is that although the trivalent chromium can be precipitated by solid alkali at last, this method needs to adopt a specific design equipment, and still can not realize the separation of metal chromium from the solid phase soil to the ...

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  • Method for removing hexavalent chromium from polluted soil
  • Method for removing hexavalent chromium from polluted soil
  • Method for removing hexavalent chromium from polluted soil

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Embodiment 1: the effect of washing hexavalent chromium polluted soil

[0027] 200g of soil was used respectively, and the liquid-solid ratio was 3:1, and the washing experiments were carried out according to 5, 10, 15, 20, and 60 minutes. The specific experimental data are shown in Table 1.

[0028] Table 1 The leaching effect of hexavalent chromium under different washing time

[0029]

[0030] As can be seen from Table 1, most of the hexavalent chromium in the soil can be rapidly dissolved in the liquid phase, and as the washing time prolongs, the rising trend of the concentration of hexavalent chromium in the liquid phase is not significant, so the method washing time of the present invention is controlled at 10-60min is sufficient, preferably 30-60min.

[0031] On the basis of the above, in order to further investigate the distribution of hexavalent chromium in the liquid phase and solid phase in the reaction, the liquid-solid ratios were respectively 3:1, 6:1,...

Embodiment 2

[0034] It can be seen from Table 2 that with the increase of the liquid-solid ratio in the washing process, the concentration of hexavalent chromium in the liquid phase and the solid phase gradually decreased, but when the liquid-solid ratio in the reaction increased to 768:1, the liquid phase Hexavalent chromium in the soil is reduced to 5mg / l. At this time, the concentration of hexavalent chromium in the separated solid phase is still as high as 293.4mg / kg. Only washing with water to remove hexavalent chromium in the soil cannot reach the preset value, and the water consumption is huge. ; Taking water consumption and removal effect into consideration, the ratio of soil to water consumption is 1:3-24, and the unit effect is the largest at the ratio of 1:3. Embodiment 2: the effect of ferrous sulfate washing hexavalent chromium polluted soil

[0035] According to the results of Example 1, the liquid-solid ratio was kept at 3:1, ferrous sulfate was added to carry out reducing w...

Embodiment 3

[0047] Embodiment 3: the addition of quicklime (slaked lime) affects the removal rate of hexavalent chromium in soil

[0048] Quicklime was selected as a regulator to precipitate the reduced trivalent chromium in alkaline conditions. The liquid-solid ratio was selected to be 3:1 in the whole experiment, and the data are shown in Table 6 below.

[0049] Table 6 Experimental data table of the influence of quicklime on the reaction

[0050]

[0051] Keep the amount of ferrous sulfate constant, and add different amounts of quicklime to adjust the pH. From the experimental results, with the increase of the amount of quicklime, the concentration of hexavalent chromium in the liquid phase gradually increases, while the concentration of hexavalent chromium in the solid phase It shows a trend of increasing first and then decreasing, so it can be inferred that quicklime increases the desorption capacity of soil for hexavalent chromium, resulting in an increase in the concentration of...

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Abstract

The invention discloses a method for removing hexavalent chromium from polluted soil. The method comprises the following steps: washing polluted soil in water, stirring, adding ferrous salt to reduce hexavalent chromium into trivalent chromium, and adding an alkaline conditioning agent while the addition of the ferrous salt in order to make the trivalent chromium form chromium hydroxide precipitate, wherein a weight ratio of soil to water to the ferrous salt to the alkaline conditioning agent is 100:300-2400:10-20:1-5, and the stirring reaction time is 10-60min. The method can effectively reduce the content of hexavalent chromium in soil.

Description

technical field [0001] The invention relates to a method for removing hexavalent chromium pollution in soil, belonging to the fields of chemistry and environmental treatment. Background technique [0002] In the past few decades, with the continuous development of industry, soil pollution has become more and more serious. Among them, the pollution of heavy metal chromium has attracted much attention. Hexavalent chromium is the main environmental pollution toxin and has strong oxidative properties. Intestinal ulcers, and even induce cancer. As one of the heavy metal ions, because it cannot be degraded by microorganisms, it accumulates in the soil for a long time and can be bio-accumulated, eventually causing it to seriously endanger human health through the food chain. Therefore, the remediation of heavy metal-contaminated soil is extremely important. How to remove hexavalent chromium pollution in soil has always been the foreword and hot spot in the field of environmental c...

Claims

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Application Information

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IPC IPC(8): B09C1/08
Inventor 翟永洪冯宏昭李忠祁彪王建荣
Owner 青海省环境科学研究设计院有限公司
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