Passivating agent for weakly acidic cadmium contaminated soil and application thereof

A technology of cadmium-contaminated soil and passivating agent, which is applied in the restoration, application, soil conditioning materials and other directions of polluted soil, can solve the problem of increasing cadmium content, difficult to guarantee the long-term effectiveness of passivating agent, and invariable change of extractable cadmium content. Obvious and other problems to achieve the effect of improving stability and satisfying efficient and fast repair

Active Publication Date: 2016-05-04

NANJING UNIV

4 Cites 29 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0004] At present, there have been a large number of research results on the fixation and stabilization of heavy metal cadmium-contaminated soil, but there is almost no long-term effective passivation method for weakly acidic heavy metal cadmium-contaminated soil.

Meng Lingyang studied the effects of three materials, peat, activated carbon and weathered coal, on the occurrence and bioavailability of heavy metal cadmium in the heavy metal cadmium-contaminated soil (pH=5.5) through greenhouse pot experiments and soil culture experiments, and explored its role as heavy metal cadmium. Feasibility of remediation agents for contaminated soil. The results of the study showed that the three organic carbon materials all reduced the soil pH value. After adding different inert organic carbon remediation agents to heavy metal cadmium contaminated soil, the content of extractable cadmium in the soil did not change significantly. Restorative agents instead increased the cadmium content in crops (“Effects of different inert organic carbon materials on soil cadmium occurrence and bioavailability”, Meng Lingyang et al., Journal of Agricultural and Environmental Sciences, 2011); Dai Yunchao studied through soil culture experiments The difference in the effect of adding different amendments on soil cadmium pollution with different properties in China shows that organic matter such as chicken manure can passivate...

Abstract

The invention discloses a passivating agent for weakly acidic cadmium contaminated soil and application thereof. The passivating agent is compounded and mixed from modified biological carbon, and mineral materials including calcium oxide, a calcium magnesium phosphate fertilizer and a silicon fertilizer beneficial to the soil. The passivating agent is applied to the surface of the weakly acidic cadmium contaminated farmland soil, and the application amount of passivating agent is controlled at more than 1.5 wt% of the soil; and then soil and passivating agent rotary tillage is carried out on a plough layer 20cm above the land surface, and the maximum field water holding capacity is maintained at more than 70% stably for more than ten days to complete the in situ remediation of the weakly acidic cadmium contaminated soil. The passivating agent can effectively reduce the content of available cadmium in soil, restore agricultural function of the polluted land, and ensure food security; the passivating agent contains a lot of organic matters and other nutrients, can provide abundant nutrition for the growth of crops, and has the advantages of environment-friendliness, high repair rate, long-term stability, and high application value.

Application Domain

Other chemical processesContaminated soil reclamation +3

Technology Topic

Contaminated soilsEnvironmental chemistry +16

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Examples

Experimental program(7)

Example Embodiment

[0040] Example 1 Preparation of passivating agent ND-1

[0041] (1) Take 100g of straw biochar prepared at 300°C, grind and crush, and pass through an 80-mesh nylon sieve;

[0042] (2) Soak the biochar in a mixed solution of 1mol/L sodium sulfide and 10% sulfuric acid for 3 hours, and the mass ratio of biochar to the mixed solution is 1:3;

[0043] (3) Put the above-mentioned mixed system after soaking in an ultrasonic cleaning machine, ultrasonic reaction for 20min, ultrasonic power is 400W; then place the reaction system in a microwave chemical reactor for microwave reaction for 10min, microwave power 600W;

[0044] (4) Separate the biological carbon from the mixed solution by suction filtration in the mixed system completed by the microwave reaction, wash the biological carbon to neutrality with deionized water, and dry it in an oven at 70°C to obtain modified carbon;

[0045] (5) Mix the purchased calcium oxide, fly ash, calcium-magnesium phosphate fertilizer, and beneficial soil silicon fertilizer in a certain proportion to obtain a composite material rich in calcium, magnesium, and silicon, so that the composite material is calculated by mass percentage. 30%, magnesium oxide 5%, silicon oxide 15%, the balance is fly ash and other mineral materials;

[0046] (6) Mix the modified biochar obtained in step (4) with the composite material (5) at a ratio of 1:1 to obtain a passivating agent. The passivating agent obtained in this example is self-named ND-1.

Example Embodiment

[0047] Example 2 Preparation of passivating agent ND-2

[0048] (1) Take 100g of straw biochar with a preparation temperature of 400℃, grind and crush, and pass through a 100-mesh nylon sieve:

[0049] (2) Soak the biochar in a mixed solution of 1mol/L sodium sulfide and 10% sulfuric acid for 4 hours, and the mass ratio of biochar to the mixed solution is 1:4;

[0050] (3) Put the immersed mixed system in an ultrasonic cleaning machine, ultrasonic reaction for 25min, ultrasonic power is 600W; then place the reaction system in a microwave chemical reactor for microwave reaction for 15min, microwave power 800W;

[0051] (4) Separate the biochar from the mixed solution by suction filtration in the mixed system after the microwave reaction, wash the biochar to neutrality with deionized water, and dry it in an oven at 70°C to obtain the modified biochar;

[0052] (5) Mix the purchased calcium oxide, fly ash, calcium-magnesium phosphate fertilizer, and beneficial soil silicon fertilizer in a certain proportion to obtain a composite material rich in calcium, magnesium, and silicon, so that the composite material is calculated by mass percentage. Accounted for 35%, magnesium oxide accounted for 8%, silicon oxide accounted for 20%, the balance is fly ash and other mineral materials;

[0053] (6) Mix the modified biochar obtained in step (4) with the composite material (5) in a ratio of 1:2 to obtain a passivating agent. The passivating agent obtained in this example is self-named ND-2.

Example Embodiment

[0054] Example 3 Preparation of passivating agent ND-3

[0055] (1) Take 100g of straw biochar whose preparation temperature is about 500℃, grind and crush it, and pass it through a 100-mesh nylon screen;

[0056] (2) Soak the biochar in a mixed solution of 1mol/L sodium sulfide and 10% sulfuric acid for 5 hours, and the mass ratio of the biochar to the mixed solution is 1:5;

[0057] (3) Put the above-mentioned mixed system in an ultrasonic cleaning machine, ultrasonic reaction for 30 minutes, the ultrasonic power is 800W; then place the reaction system in a microwave chemical reactor for microwave reaction for 20 minutes, the microwave power is 1000W;

[0058] (4) Separate the biochar from the mixed solution by suction filtration in the mixed system after the microwave reaction, wash the biochar to neutrality with deionized water, and dry it in an oven at 70°C to obtain the modified biochar;

[0059] (5) Mix the purchased calcium oxide, fly ash, calcium-magnesium phosphate fertilizer, and beneficial soil silicon fertilizer in a certain proportion to obtain a composite material rich in calcium, magnesium, and silicon, so that the composite material is calculated by mass percentage. 40%, 10% magnesium oxide, 25% silicon oxide, and the balance is fly ash and other mineral materials;

[0060] (6) Mix the modified biochar obtained in step (4) with the composite material (5) in a ratio of 1:3 to obtain a passivating agent. The passivating agent obtained in this example is self-named ND-3.

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Classification and recommendation of technical efficacy words

Improve stability

Agent delivering system comprised of microparticle and biodegradable gel with an improved releasing profile and methods of use thereof

InactiveUS6287588B1increase stabilityimprove stability

Owner:BTG INT LTD

Passivating agent for weakly acidic cadmium contaminated soil and application thereof

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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