CN110681687A - Neutral soil heavy metal cleaning agent and cleaning method thereof - Google Patents

Abstract

The invention discloses a neutral soil heavy metal cleaning agent, which comprises: 1 molar unit of aqueous solvent; a solute dissolved in the water solvent, wherein the solute is at least one salt compound, and 0.01-1.8 mol of solute is dissolved in 1 mol of water solvent, so that when the solute dissolved in the water solvent contacts polluted soil containing heavy metals, the heavy metals can be separated from the polluted soil. The invention also discloses a cleaning method by using the neutral soil heavy metal cleaning agent.

Description

A kind of neutral soil heavy metal cleaning agent and cleaning method thereof

technical field

The invention relates to a neutral soil heavy metal cleaning agent, and furthermore, the invention also relates to a cleaning method using the neutral soil heavy metal cleaning agent.

Background technique

Pollutants produced by human activities and industrialization not only affect the balance of the natural environment, but also indirectly affect the health of humans and natural organisms. Soil pollution not only destroys the health of natural organisms, but also further reduces the growth and health of crops, especially human health. For soil pollution, it can be divided into two categories: organic and heavy metals. For organic pollution, whether it is pesticides or oil pollution, it can be effectively removed by enzymes, microorganisms, or combined with surfactants. However, for the pollution of heavy metals in soil, although many researchers have proposed many treatment technologies, they all have relative shortcomings.

The common solidification method (Solidificaiton) is to solidify the contaminated soil through a solidifying agent, thereby limiting the movement and diffusion of pollutants. You can choose to remove the fixed soil solidified material to landfill, or directly solidify it on site; the disadvantage is that the waste is disposed of in the form of solidified material, which not only takes up space, but the occupied space can no longer be used for farming or natural use. Environmental reuse. As for the commonly known stabilization method (Stabilization), it uses chemical agents to chemically treat the harmful components in the soil or waste to make them harmless or unable to release them. Expensive and still has the risk of recontamination.

Similarly, there is also a method called vitrification, which is a method that can be selectively heated through high temperature. Because the resistance of the soil contaminated by metal is low, after a large amount of electric energy is introduced, it will be converted into high temperature, so that the For misplanted vitrification in soil, in addition to no need to add curing agent, the volume and surface area of soil solidified material formed by vitrification method are smaller, which can also reduce the possibility of pollutant release, and can be treated to more than 20 feet underground of deep contaminated soil. But again, treated soil, due to the presence of a large amount of solidified matter, is not easily re-cultivated or reused as a natural environment.

In addition, there are technologies for separation, concentration and decontamination, such as separation of mercury by thermal desorption; or decontamination by SoilWashing or pickling. In this part, clean water and organic solvents need to be selected according to the composition of pollutants. or acid cleaning of contaminated soil. For example, lead can be washed with clean water and separated by gravity, but on the one hand, this method requires repeated washing and consumes a lot of water, which relatively limits the types of pollutants that can be treated and the amount of soil that can be treated, but the advantage is that The treated soil can be backfilled and reused smoothly; the type, composition and particle size of the soil will also affect the effect of leaching. Even if the leached soil can be backfilled to its original location, sludge containing a high proportion of heavy metals needs to be further treated or discarded depending on its nature. Moreover, most of the methods of gravity leaching alone are only suitable for heavy metals with larger molecular weights, which also becomes a limitation of leaching technology.

Similar to the leaching technology, there is also an acid (alkali) washing method. The main difference is that the acid washing method uses an aqueous solution such as dilute hydrochloric acid, phosphoric acid, and acetic acid as a cleaning agent to separate heavy metals. In contrast, acid (alkaline) washing technology can separate heavy metals with smaller molecular weight in soil better than leaching, and can achieve the effect of removing about 50% as described in the aforementioned Chinese mainland patent. However, on the one hand, pickling needs to go through multiple cleaning cycles, which will generate a lot of waste liquid. According to Chinese patent CN103357655A, the soil:water ratio of pickling technology is 1:15; in other words, 100 tons of pickling should be used to clean 10 tons of soil. After the separation step, the implementation of the pickling technology will also process the sludge together with the pickling aqueous solution, and a large amount of heat energy will be generated in the process.

What's more unfavorable, the soil after pickling method has residual acidity and must go through post-treatment steps such as neutralization/stabilization before backfilling. In addition, because the original characteristics of the soil are severely damaged after cleaning with aqueous solutions such as acid and alkali, even if the soil is backfilled, natural organisms and microorganisms will still have adaptation problems. In addition, whether it is acid-washed or post-treated waste liquid, it needs to be treated separately before it can be safely discarded; at the same time, this technology will also cause greater safety hazards to the operating environment and personnel.

In short, among the existing heavy metal-contaminated soil treatment technologies, the solidification/stabilization method and vitrification method will occupy the treatment space or be forced to abandon land reuse; on the other hand, the existing cleaning technology or pickling technology, although it can The use of soil backfilling, on the one hand, there is still room for improvement in the efficiency of removing heavy metal pollution, and the washing process is complicated, especially the production of a large amount of waste liquid and sludge, and the pickling process also destroys the natural utilization capacity of the soil. Room for improvement.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, according to the embodiments of the present invention, it is desirable to provide a neutral soil heavy metal cleaning agent, aiming to achieve the following purposes: (1) remove heavy metals through neutral salt compounds, and reduce the pollution to soil. (2) Removal of heavy metals through neutral salt compounds as solutes, reducing possible safety hazards to the application environment and personnel during the application process; (3) Through neutral salt compounds As solutes, these compounds can achieve better removal efficiency than pickling, and are not limited to heavy metals with high molecular weight.

According to an embodiment of the present invention, also hope to provide a kind of soil cleaning method utilizing neutral soil heavy metal cleaning agent, aim to achieve the following purpose: (1) pass through choline salicylate as the solute, reach simultaneously in the cleaning process Increase soil nutrition and the effect of anti-inflammatory ingredients in future crops, which is more helpful for future planting or cultivation; (2) Use neutral salt compounds as solutes to clean soil contaminated with heavy metals, which can simplify the process and simplify Subsequent treatment of waste liquid can greatly reduce the cost of decontamination; (3) By using neutral salt compounds as solutes, the aqueous solution after application can be recycled and reused instead of being treated as waste liquid, which greatly reduces the cost of subsequent treatment; (4) ) Through neutral salt compounds as solutes, less cleaning agent can be used than acid (alkali) washing, so as to achieve the purpose of environmental protection and reducing the cost of cleaning agents.

According to an embodiment, a neutral soil heavy metal cleaning agent provided by the present invention comprises:

1 mole unit of water solvent;

The solute dissolved in the aforementioned water solvent, the aforementioned solute is at least one salt compound, and 0.01-1.8 moles of solute are dissolved in 1 mole unit of the water solvent, so that when the solute dissolved in the water solvent contacts the contaminated soil containing heavy metals, Can separate heavy metals from contaminated soil.

According to an embodiment, a soil cleaning method using a neutral soil heavy metal cleaning agent provided by the present invention comprises the following steps:

(a) Provide 1 unit weight of contaminated soil;

(b) providing 2 to 15 units by weight of a neutral soil heavy metal cleaning agent mixed with the aforementioned contaminated soil for at least 30 minutes, wherein the aforementioned neutral soil heavy metal cleaning agent comprises:

1 mole unit of water solvent;

The solute dissolved in the aforementioned water solvent, the aforementioned solute is at least one salt compound, and 0.01-1.8 moles of solute are dissolved in 1 mole unit of the water solvent, so that: when the solute dissolved in the water solvent contacts the contaminated soil containing heavy metals , which can separate heavy metals from contaminated soil to produce contaminated parts;

(c) filtering out the aforementioned neutral soil heavy metal cleaning agent and the aforementioned contaminated part.

Compared with the prior art, the neutral soil heavy metal cleaning agent provided by the present invention and the soil cleaning method using the neutral soil heavy metal cleaning agent can not only simplify the process and reduce the application cost by using the neutral salt compound as the solute, and Reduce waste liquid and achieve better removal efficiency than acid (alkaline) washing technology, which can reduce the burden or safety hazards caused by cleaning to the environment and related operators, and can also increase soil nutrients to help planting and cultivation. At the same time, the water solution after application can be recycled and reused, which further achieves the purpose of environmental protection and cost reduction. Of course, the so-called neutral salt compounds as the solute here are not limited to the need to be combined into a single compound before dissolving in water, but also include an aqueous solution of an acidic compound and an aqueous solution of an alkaline compound, and the two add to each other. The neutral soil heavy metal cleaning agent is only formed after.

Description of drawings

FIG. 1 is a flow chart of the steps of the first preferred embodiment of the present invention (for explaining the preparation and cleaning method of the neutral soil heavy metal cleaning agent in this embodiment).

FIG. 2 is a schematic view of the operation of the embodiment of FIG. 1 .

3 is a flow chart of the steps of the second preferred embodiment of the present invention (for explaining the neutral soil heavy metal cleaning agent in this embodiment, and its preparation, cleaning and recovery methods).

FIG. 4 is an operation schematic diagram of the embodiment of FIG. 3 .

FIG. 5 is a schematic diagram of the operation of recovering the neutral heavy metal cleaning agent in the embodiment of FIG. 3 .

Among them: 21 is water pipe; 22, 42, 54 are neutral soil heavy metal cleaning agent; 23, 43 are polluted soil; 24 is drip tank; 25 is receiving bucket; 26 is aqueous solution mixed with heavy metal ions; 41 is supernatant 52 is an anode electrode; 53 is a cathode electrode; 55 is an electroplating tank; 91, 92, and 93 are the steps of the first embodiment; ', 94' are the steps of the second embodiment.

Detailed ways

The foregoing and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the drawings; in addition, in each embodiment, similar components will be represented by similar label representation.

first preferred embodiment

The first preferred embodiment of the present invention, as shown in FIG. 1 and FIG. 2 , is an aqueous solution using choline salicylate as a solute and a cleaning method thereof. In the present embodiment, choline salicylate in the proportion of 1 mol of water solvent in the formula of the release example and 1.8 mol of above is used as the salt compound. When choline salicylate is dissolved in water solvent to form an aqueous solution, its pH value is between pH 6.0-6.5, so it can be used as a neutral soil heavy metal cleaning agent.

However, if one or more of 1,3-dimethylimidazolium iodide, 1,1-dimethylpiperidine, tetramethylamine cation or tetramethyl phosphate are used as positive ions to correspond to the following negative ions: [AlCl ₄ ] ^- , [FeCl ₄ ] ^- , [AlBr] ^- , [FeBr] ^- , [CuBr] ^- , [ZnBr] ^- , [Al ₂ Cl ₇ ] ^- , [Al ₃ Cl ₁₀ ] ^- , [Al ] (Et)Cl ₃ ] ^- , [Al(OCH ₂ CF ₃ ) ₄ ] ^- , Cl ^- , Br ^- , I ^- , [N ₃ ] ^- , [SCN] ^- , [OCN] ^- , [N(CN) ₂ ] ^- , [C(CN) ₃ ] ^- , [B(CN) ₄ ] ^- , [BF ₄ ] ^- , [B(oxalato) ₂ ] ^- , [B(C ₆ H ₄ 4-CF ₃ ) ₄ ] ^- , [PF ₆ ] ^- , [P(C ₂ F ₅ ) ₃ F ₃ ] ^- , [SbF ₆ ] ^- , [NO ₃ ] ^- , [NO ₂ ] ^- , [ROSO ₃ ] ^- , [(RO ) ₂ PO ₂ ] ^- , [MeCO ₂ ] ^- , [CF ₃ CO ₂ ] ^- , [lactate] ^- , [amino acidate] ^- , [p-MeC6H4SO3] ^- , [CF ₃ SO ₃ ] ^- , [(CF ₃ SO ₂ ) ₂ N] ^- , Na ₂ EDTA, Na ₄ IDS, sodium salicylate, sodium gluconate, sodium oxalate, sodium citrate and sodium aminotriacetate, the formed salt compounds are dissolved in water solvent to make The neutral soil heavy metal cleaning agent does not affect the purpose of the present invention.

In this embodiment, step 91 provides 1 weight unit of contaminated soil from soil 23 contaminated by zinc (Zn) and copper (Cu) in a total of 10 kilograms; step 92 provides 2 weight units corresponding to 1 at a water pipe 21 10 kilograms of polluted soil is 20 kilograms of neutral soil heavy metal cleaning agent 22, and both are placed in a drip groove 24, which is far less than the cleaning agent consumption of the pickling technology recorded in Chinese patent CN103357655A; then, step 92 is with In the continuous stirring mode, the above-mentioned contaminated soil 23 is mixed with the neutral soil heavy metal cleaning agent 22 corresponding to 2 weight units, and the mixing mode is continuous stirring for 30 minutes. Of course, those skilled in the art can easily understand that mixing is a part of mixing if the mixing is carried out in a drum type or if it is left to stand after stirring.

When the polluted soil 23 is mixed with the neutral soil heavy metal cleaning agent 22 , the positive ions in the neutral soil heavy metal cleaning agent will replace the zinc ions and copper ions in the polluted soil, thereby removing the zinc ions and copper ions from the polluted soil 23 . The separated zinc ions and copper ions will enter the aqueous solution of the neutral soil heavy metal cleaning agent to become a polluted aqueous solution.

Finally, in step 93, the aqueous solution 26 mixed with heavy metal ions is received by the lower receiving bucket 25 by means of a screen, and the cleaned soil can be backfilled to the original polluted farmland and used for farming or planting, The effect of cleaning the soil is achieved; thus, the subsequent neutralization/stabilization procedure in the pickling technology is omitted, and the neutral soil heavy metal cleaning agent remains neutral after cleaning, and the entire operation process will not cause environmental damage and operators. burden. Of course, those skilled in the art can easily understand that the effect of the present invention will not be affected if the neutral soil heavy metal cleaning agent and the above-mentioned contaminated parts are filtered out by means of extraction or dumping.

Compared with the original zinc ion content, the soil cleaned by this example is reduced from 1344ppm to 589ppm, wherein the ratio of the heavy metal zinc ions separated from the soil is used as the removal efficiency, and the experimental test reaches about 56%. In addition, the neutral soil heavy metal cleaning agent was tested in experiments. Compared with the original copper ion content, the neutral soil heavy metal cleaning agent was reduced from 1959ppm to 762ppm, and the removal efficiency after cleaning can reach about 61%. It is also higher than the removal efficiency of the pickling technology recorded in Chinese patent CN103357655A.

Second Preferred Embodiment

The second preferred embodiment of the present invention uses choline chloride as a positive ion, corresponding to the following negative ions: [AlCl ₄ ] ^- , [FeCl ₄ ] ^- , [AlBr] ^- , [FeBr] ^- , [CuBr] ^- , [ZnBr] ^- , [Al ₂ Cl ₇ ] ^- , [Al ₃ Cl ₁₀ ] ^- , [Al(Et)Cl ₃ ] ^- , [Al(OCH ₂ CF ₃ ) ₄ ] ^- , Cl ^- , Br ^- , I ^- , [N ₃ ] ^- , [SCN] ^- , [OCN] ^- , [N(CN) ₂ ] ^- , [C(CN) ₃ ] ^- , [B(CN) ₄ ] ^- , [BF ₄ ] ^- , [B(oxalato) ₂ ] ^- , [B(C ₆ H ₄ 4-CF ₃ ) ₄ ] ^- , [PF ₆ ] ^- , [P(C ₂ F ₅ ) ₃ F ₃ ] ^- , [SbF ₆ ] ^- , [NO ₃ ] ^- , [NO ₂ ] ^- , [ROSO ₃ ] ^- , [(RO) ₂ PO ₂ ] ^- , [MeCO ₂ ] ^- , [CF ₃ CO ₂ ] ^- , [lactate] ^- , [amino acidate] ^- , [p-MeC6H4SO3] ^- , [CF ₃ SO ₃ ] ^- , [(CF ₃ SO ₂ ) ₂ N] ^- , Na ₂ EDTA, Na ₄ IDS, sodium salicylate, sodium gluconate, Sodium oxalate, sodium citrate and sodium aminotriacetate, the formed salt compound is 0.01 mole, corresponding to the aqueous solution formed by being dissolved in 1 mole of water solvent, as the neutral soil metal cleaning agent in this embodiment, its acid The base number is between 6.0 and 6.5.

Please refer to FIG. 3 and FIG. 4 together. In this embodiment, 10 kg of contaminated soil containing 2013 ppm copper metal and 1276 ppm zinc metal is provided in step 91 ′, and then in step 921 ′, sieve holes with different apertures are passed through The equipment removes impurities from the soil; however, those skilled in the art can easily know that the method can remove the soil including larger particles, dead branches, leaves, other types of waste, etc., such as removing the soil by sorting All the impurities can be applied to the present invention without affecting its implementation; the contaminated soil after removing the impurities can be more thoroughly mixed with the neutral soil heavy metal cleaning agent.

Subsequently, step 92' corresponds to providing 2 times the weight unit of neutral soil heavy metal cleaning agent, a total of 30 kilograms of neutral soil heavy metal cleaning agent 42, and mixed with the contaminated soil 43 in the bucket 44 for at least 2 hours, including static precipitation. 30 minutes; then, step 93 ′ is carried out to extract the supernatant aqueous solution 41 after filtering and stirring with sunlight exposure, which contains neutral soil heavy metal cleaning agent 42 and heavy metal pollutants mainly composed of copper ions. Further, because in the present embodiment, the cationic choline chloride used in the neutral soil heavy metal cleaning agent 42 is the precursor for the biosynthesis of vitamin B, therefore, after cleaning, when the positive ions replace the positively charged Heavy metal ions will also increase the nutrient content of the soil, which will also help the growth of plants and microorganisms that will be planted or cultivated in the future.

According to experimental tests, the copper content of the contaminated soil after cleaning is 750 ppm and the zinc content is 673 ppm, and the removal efficiency is about 56% and 48%, respectively. In addition, copper ions are lighter heavy metal ions than lead ions, and are also heavy metal pollution that cannot be removed by the leaching process; It also does not affect the concept of the present invention. In particular, although this embodiment is shown as stirring and standing in a mixing tank, in actual operation, it can even be operated on-site in a polluted field, that is, as long as a piece of regional soil is dug on site, Pour the neutral soil heavy metal cleaning agent locally, and after stirring evenly for a sufficient time, let it stand and take out the supernatant aqueous solution 41, which can be exposed to the sun to complete all the steps of removing heavy metal ion pollution and achieve the effect of soil purification.

Finally, step 94' is recovered after extraction; the soil heavy metal cleaning agent containing the contaminated part can be reused after recovery, and the above-mentioned supernatant aqueous solution can be stored in a chemical liquid storage container and used for the second or more times Repeat cleaning. After experimental tests, the recovered soil heavy metal cleaning agent was directly used for the second time to clean copper (Cu) 3477ppm, zinc (Zn) 2023ppm, chromium (Cr) 72ppm and nickel (Ni) 54ppm. After cleaning, the heavy metal content was reduced to copper. (Cu) 1612ppm, zinc (Zn) 1101ppm, (Cr) 41ppm and nickel (Ni) 26ppm; the cleaning efficiency can still reach 54%, 50%, 43%, and 52% removal efficiency, respectively.

As shown in FIG. 5 , the recovered neutral soil heavy metal cleaning agent 54 can be placed in an electroplating tank 55 to recover, for example, the above-mentioned copper ions by electroplating. At this time, the cathode electrode 53 is made of stainless steel, and the anode electrode 52 is made of stainless steel. Taking the platinum titanium mesh as an example, by applying electricity through the DC power supply 51, the copper ions in the neutral soil heavy metal cleaning agent 54 will be electroplated to the cathode electrode 53, and the neutral soil heavy metal cleaning agent 54 can be cleaned and used again. Similarly, those skilled in the art can also easily precipitate heavy metal ions by means of acid-base reaction, etc., without changing the essence of the present invention. Thereby, the neutral soil heavy metal cleaning agent can be reused several times before losing its activity, and the heavy metal ions can be effectively recovered, which also greatly reduces the waste generated by the soil cleaning method of the present invention.

Of course, those skilled in the art can easily understand that the neutral soil heavy metal cleaning agent can also include at least ethylenediaminetetraacetic acid, aminocarboxylate, iminodisuccinic acid, TMDTA, DE, ethylenediaminedisuccinic acid and The chelating agent of at least one diethyltriaminepentaacetic acid is TMDTA. However, those skilled in the art can also easily know that the chelating agent may also act as an anion or cation in the neutral soil heavy metal cleaning agent, which does not affect the essence of the present invention.

In addition, those skilled in the art can easily understand that the neutral cleaning agent referred to in this case can also be formed by combining the acidic salt compound and the basic salt compound to form an aqueous solution without pre-combination, and then mixing together. : A neutral cleaning agent made of oxalic acid as an acidic solute (pH=1) and sodium nitrilotriacetate (Na3NTA) as an alkaline solute (pH=12.5). Concentrations ranged from 1.8 mol to 0.005 mol.

According to the experimental test, the heavy metal content of the contaminated soil before cleaning was copper (Cu) 804ppm, zinc (Zn) 951ppm, chromium (Cr) 432ppm and nickel (Ni) 490ppm. After cleaning with a neutral cleaning agent, the heavy metal content was reduced. To chromium copper (Cu) 353ppm, zinc (Zn) 534ppm, (Cr) 245ppm and nickel (Ni) 283ppm; the cleaning efficiency is 56%, 44%, 42% and 42% respectively, which completely achieves the removal of heavy metals from soil. Effective, and still maintain the neutral pH of the soil, greatly reducing the difficulty of soil cleaning and the cost of cleaning soil.

Claims (9)

1. a neutral soil heavy metal cleaning agent, is characterized in that, this neutral soil heavy metal cleaning agent comprises: 1 mole unit of water solvent; The solute dissolved in the aforementioned water solvent, the aforementioned solute is at least one salt compound, and 0.01-1.8 moles of the aforementioned solute is dissolved in the aforementioned 1 mole unit of the aforementioned water solvent, so that when the aforementioned solute dissolved in the aqueous solvent contacts the receptor containing heavy metals. When soil is contaminated, heavy metals can be separated from the contaminated soil. 2. The neutral soil heavy metal cleaning agent according to claim 1, wherein the aforementioned salt compound is formed by at least one positive ion corresponding to at least one equivalent negative ion; the aforementioned positive ion is selected from 1,3-dimethyl Imidazolium iodide, 1,1-dimethylpiperidine, tetramethylamine cation and tetramethylphosphate; the aforementioned anions are selected from [AlCl ₄ ] ^- , [FeCl ₄ ] ^- , [AlBr] ^- , [FeBr ] ^- , [CuBr] ^- , [ZnBr] ^- , [Al ₂ Cl ₇ ] ^- , [Al ₃ Cl ₁₀ ] ^- , [Al(Et)Cl ₃ ] ^- , [Al(OCH ₂ CF ₃ ) ₄ ] ^- , Cl ^- , Br ^- , I ^- , [N ₃ ] ^- , [SCN] ^- , [OCN] ^- , [N(CN) ₂ ] ^- , [C(CN) ₃ ] ^- , [B(CN) ₄ ] ^- , [BF ₄ ] ^- , [B(oxalato) ₂ ] ^- , [B(C ₆ H ₄ 4-CF ₃ ) ₄ ] ^- , [PF ₆ ] ^- , [P(C ₂ F ₅ ) ₃ F ₃ ] ^- , [SbF ₆ ] ^- , [NO ₃ ] ^- , [NO ₂ ] ^- , [ROSO ₃ ] ^- , [(RO) ₂ PO ₂ ] ^- , [MeCO ₂ ] ^- , [CF ₃ CO ₂ ] ^- , [lactate] ^- , [amino acidate] ^- , [p-MeC6H4SO3] ^- , [CF ₃ SO ₃ ] ^- , [(CF ₃ SO ₂ ) ₂ N] ^- , Na ₂ EDTA, Na ₄ IDS, saliculus sodium, sodium gluconate, sodium oxalate, sodium citrate and sodium triacetate. 3. The neutral soil heavy metal cleaning agent according to claim 1, further comprising a chelating agent. 4. neutral soil heavy metal cleaning agent as claimed in claim 3 is characterized in that, chelating agent is selected from ethylenediaminetetraacetic acid, aminocarboxylate, iminodisuccinic acid, TMDTA, DE, ethylenediamine disuccinic acid acid and diethyltriaminepentaacetic acid. 5. The neutral soil heavy metal cleaning agent according to claim 2, 3 or 4, wherein the positive ion of the salt compound contains at least choline chloride. 6. a soil cleaning method utilizing neutral soil heavy metal cleaning agent, is characterized in that, comprises the steps: (a) Provide 1 unit weight of contaminated soil; (b) providing 2 to 15 units by weight of a neutral soil heavy metal cleaning agent mixed with the aforementioned contaminated soil for at least 30 minutes, wherein the aforementioned neutral soil heavy metal cleaning agent comprises: 1 mole unit of water solvent; The solute dissolved in the aforementioned water solvent, the aforementioned solute is at least one salt compound, and 0.01-1.8 moles of the aforementioned solute is dissolved in the aforementioned 1 mole unit of the aqueous solvent, so that: when the aforementioned solute dissolved in the aqueous solvent contacts the heavy metal containing When the soil is polluted, it can separate heavy metals from the polluted soil to produce the polluted part; (c) filtering out the aforementioned neutral soil heavy metal cleaning agent and the aforementioned contaminated part. 7. the soil cleaning method of utilizing neutral soil heavy metal cleaning agent as claimed in claim 6, is characterized in that, has step (b-1) between step (a) and step (b): remove in the contaminated soil impurities. 8. the soil cleaning method utilizing neutral soil heavy metal cleaning agent as claimed in claim 6 or 7, is characterized in that, further comprises the steps after step (c): (d) collecting the aforementioned filtered neutral soil heavy metal cleaning agent and the aforementioned contaminated parts; (e) recovering the aforementioned neutral soil heavy metal cleaning agent. 9. the soil cleaning method of utilizing neutral soil heavy metal cleaning agent as claimed in claim 8, is characterized in that, the recovery in step (e) is electroplating recovery, whereby polluted part and neutral soil heavy metal cleaning agent are separated .

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