CN105936824A - Soil heavy metal activator and preparation method and application thereof - Google Patents

Abstract

The invention discloses a soil heavy metal activator as well as its preparation method and application. The soil heavy metal activator includes active components, and the molecular structure of the active components contains at least one amidoxime group and one amino group, or at least contains one amidoxime group and one amine group. The preparation method of the soil heavy metal activator: heating hydroxylamine hydrochloride to 60°C~85°C with one or more compounds containing cyano and amino groups or containing cyano and amine groups in the presence of sodium carbonate and alkali , react at constant temperature for 3-5 hours, cool to room temperature, and adjust the pH to 6-8 to obtain the heavy metal activator. The soil heavy metal activator is added to the heavy metal polluted soil at a ratio of 0.1 to 20‰ of the mass ratio of the active ingredient to the soil, so as to achieve the purpose of activating the heavy metal in the soil. The invention can efficiently activate pollution factors such as copper, lead, zinc, cadmium, nickel, mercury and the like in soil, has good activation effect, and has no secondary environmental risk.

Description

A kind of soil heavy metal activator and its preparation method and application

technical field

The invention belongs to the field of soil heavy metal pollution control, and in particular relates to a soil heavy metal activator and an application method thereof.

Background technique

Soil is a complex multiphase dynamic open system, mainly including solid phase, liquid phase, gas phase and biological phase. Soil ecological function is the embodiment of the dynamic process in which substances are interconnected and mutually restricted in the multiphase system of soil. A large amount of clay minerals and organic matter contained in the solid phase of the soil can effectively absorb various pollution factors (such as: heavy metals) entering into it, and then accumulate in the soil. When the accumulation exceeds a certain amount, the output of the soil system Will directly or indirectly endanger human health, that is, soil pollution.

The overall situation of my country's soil environment is not optimistic, and the prevention of heavy metal pollution cannot be ignored. The Ministry of Environmental Protection and the Ministry of Land and Resources jointly released the "National Soil Pollution Survey Bulletin" on April 17, 2014. The survey results show that the overall situation of the national soil environment is not optimistic. The over-standard rate is as high as 19.4%. According to the statistics of the Ministry of Agriculture, as many as 1.2×107 tons of grain are polluted by heavy metals nationwide every year, and the reduction in grain production due to heavy metal pollution is as high as 107 tons, with a total economic loss of at least 20 billion yuan; Reports on lead incidents and cadmium rice incidents. As "rice bags" and "vegetable baskets", farmland pollution has affected social and economic development, and has attracted the attention of the country and the general public. The prevention and control of soil heavy metal pollution cannot be ignored, and the country attaches great importance to the prevention and control of soil heavy metal pollution.

Researchers at home and abroad have developed a large number of soil heavy metal pollution control technologies, and the research results can be summarized into three types of control strategies: passivation, dilution and purification.

The soil passivation control strategy is mainly to reduce the activity of heavy metals by adding modifiers such as lime, phosphate, sulfur-containing chemicals, and organic matter to the soil, and reduce the activity of heavy metals through the combination of modifiers and heavy metal elements, so as to reduce the environmental risk of heavy metals. After the treatment of soil passivation strategy treatment technology, since the heavy metal pollution factors are still in the soil environment, under the action of soil moisture, heat, gas, pH, redox potential, microorganisms, etc., there is an environmental risk of further activation of the heavy metal pollution factors; another On the one hand, due to the addition of chemical agents to the soil, it may have an impact on the physical and chemical properties and ecological functionality of the soil.

The soil dilution control strategy is mainly to reduce the concentration of heavy metal pollution in the soil through engineering measures such as alien soil and deep plowing, so as to reduce the environmental risk of heavy metals. This strategy is only applicable to the treatment of light pollution above 30cm above the surface. The above soil governance does not have competitive significance.

The soil purification strategy is mainly to reduce the total amount of heavy metals in the soil by extracting the heavy metal pollution factors in the soil. This strategy takes the elimination of the heavy metal pollution factors in the soil as the ultimate goal and is the most thorough treatment technology. The hyperaccumulator plant extraction technology in this strategy is highly praised by researchers at home and abroad.

At present, the research frontier of hyperaccumulator plant extraction technology is chelation-induced hyperaccumulator plant extraction technology. This technology applies soil heavy metal activator to the hyperaccumulator plant planting area in the stable growth period, and the activator will bind to the solid phase of the soil. The heavy metal pollution factors are extracted to the soil liquid phase to promote the enrichment and extraction of heavy metal elements by hyperaccumulator plants. Commonly used soil heavy metal activators include aminocarboxylic acid-based EDTA, NTA, EDDA, EGTA, DTPA, PDTA, EDDS, etc., and carboxylic acid-based low-molecular-weight water-soluble chelating agents such as oxalic acid, citric acid, malic acid, and succinic acid. The above-mentioned amino carboxylic acid type and carboxylic acid type activators belong to hard bases in Lewis soft and hard acid base theory. However, the soil contains a large amount of hard acid ions such as calcium, magnesium, aluminum, iron, etc. According to the soft and hard acid-base theory of "hard against hard, soft against soft", the above-mentioned activator containing carboxylic acid will first desorb calcium, Hard acid ions such as magnesium, aluminum, iron, etc., and then desorb soft acid ions such as copper, lead, zinc, cadmium, nickel, mercury in the soil; and the concentration of hard acid ions such as calcium, magnesium, aluminum, iron in the soil may exceed Copper, lead, zinc, cadmium, nickel, mercury and other soft acid ions hundreds or even thousands of times. It can be seen that although the above-mentioned soil heavy metal activators based on amino carboxylic acid type and carboxylic acid type can broadly activate most of the metal elements in the soil, their activation efficiency for heavy metal pollution factors must be low.

In addition, the degradation characteristics of soil heavy metal activators are also important considerations. A large number of studies have shown that activators such as EDTA, NTA, EDDA, EGTA, DTPA, PDTA, and EDDS based on aminocarboxylic acids have high activation efficiency, but are difficult to degrade; Low-molecular water-soluble chelating agents such as oxalic acid, citric acid, malic acid, and succinic acid of carboxylic acids are easy to degrade, but their activation efficiency is low.

It can be seen that it is of great significance to develop soil heavy metal activators with high activation efficiency and easy degradation.

Contents of the invention

One of the purposes of the present invention is to provide a high activation efficiency and easy to degrade soil heavy metal activator; the second purpose of the present invention is to provide a preparation method of a high activation efficiency and easy to degrade soil heavy metal activator. The third object of the present invention is to provide a kind of application of soil heavy metal activator. The present invention proposes the following technical solutions for the above purpose:

A soil heavy metal activator comprises active components, the molecular structure of which contains at least one amidoxime group and one amino group, or at least contains one amidoxime group and one amine group.

In some preferred embodiments, the components of the soil heavy metal activator may also include: hydroxylamine compound, sodium carbonate, an organic compound containing both cyano and amino groups or cyano and amine groups in the molecular structure, and water.

The preparation method of the soil heavy metal activator is as follows: in the presence of sodium carbonate and alkali, hydroxylamine hydrochloride and one or more compounds containing cyano and amino or cyano and amine are heated to 60 ° C ~ 85 °C, react at constant temperature for 3-5 hours, cool to room temperature, and adjust the pH to 6-8 to obtain the soil heavy metal activator.

In some preferred embodiments, the compound containing cyano group and amino group or containing cyano group and amine group includes but not limited to cyanamide, dicyandiamide; aminoacetonitrile, iminodiacetonitrile; 3-aminopropionitrile, bis (2-cyanoethyl)amine, tris(2-cyanoethyl)amine; tetrakis(2-cyanoethyl)ethylenediamine and other ethylenediamines containing amino groups or amino compounds; ethylenediamines containing hydroxyl and containing Amines or amino compounds; ethylenediamines containing halogens and containing amines or amino compounds; tetrakis(2-cyanoethyl)propylenediamine and other propylenediamines containing amines or amino compounds; propylenediamines containing hydroxyl and Amino groups or amino compounds; Propylenediamines contain halogens and contain amine groups or amino compounds.

The above-mentioned cyano group and amino group or cyano group and amine group compound react with hydroxylamine hydrochloride under alkaline conditions to generate the active ingredient of the soil heavy metal activator. The formula is expressed as follows:

In a preferred embodiment, the cyano- and amino-containing or cyano- and amine-containing compound is cyanamide, and the equation of reacting with hydroxylamine hydrochloride to generate the main active ingredient is as follows:

In a preferred embodiment, the cyano- and amino-containing or cyano- and amine-containing compounds are monoamido cyanide compounds, and the reaction equation with hydroxylamine hydrochloride is as follows:

Ra, Rb, and Rc can be a carbon chain group containing 1 to 3 carbon atoms, a halogen, a hydroxyl group, or a carbon chain group containing 1 to 3 carbon atoms containing a halogen or a hydroxyl group. When Ra, Rb, and Rc When it is a halogen or hydroxyl group, there is no cyano group behind the group, but Ra, Rb, and Rc cannot all be halogen or hydroxyl at the same time, at least one group must be connected to the cyano group to ensure the presence of the cyano group; d is 1 or 2 Or 3, depending on the number of cyano groups in the monoamine cyanide compound.

In a preferred embodiment, the cyano- and amino-containing or cyano- and amine-containing compound is a diaminocyano compound,

The reaction equation with hydroxylamine hydrochloride is as follows:

Rm can be a carbon chain group containing 1 to 3 carbon atoms or a carbon chain group containing 1 to 3 carbon atoms containing halogen and hydroxyl; Rg, Rh, Ri, and Rj can be 1 to 3 carbon chain groups respectively. Atomic carbon chain groups, halogens, hydroxyl groups, or carbon chain groups with 1 to 3 carbon atoms containing halogens and hydroxyl groups; when Rg, Rh, Ri, and Rj are halogen or hydroxyl groups, there is no The cyano group is connected, but Rg, Rh, Ri, and Rj cannot be halogens or hydroxyl groups at the same time. At least one group must be connected to the cyano group to ensure the presence of the cyano group; k is 1 or 2 or 3 or 4, depending on the diamine cyanide Depends on the number of cyano groups in the base compound.

In a preferred embodiment, the cyano- and amino-containing or cyano- and amine-containing compounds are polyamine cyanide compounds, and the reaction equation with hydroxylamine hydrochloride is as follows:

Re, Rf can be the carbon chain group that contains 1～3 carbon atoms respectively, or the carbon chain group that contains halogen, hydroxyl 1～3 carbon atoms; Rg, Rh, Ri, Rj can be the group that contains 1 respectively A carbon chain group of ~3 carbon atoms, a halogen, a hydroxyl group, or a carbon chain group of 1 to 3 carbon atoms containing a halogen or a hydroxyl group, but Rg, Rh, Ri, and Rj cannot be all halogens or hydroxyl groups at the same time, at least There needs to be a group connected to the cyano group to ensure the presence of the cyano group; k is 1 or 2 or 3 or 4, depending on the number of cyano groups in the polyamine cyano compound.

Show in some preferred embodiments, the preparation method of described soil heavy metal activator can also be:

1) dissolving lime nitrogen powder in hydroxylamine hydrochloride solution, sealing and stirring for a certain period of time;

2) Heat to 60°C~85°C, stir and react at constant temperature for 3~5 hours, then cool to room temperature;

3) Pass in carbon dioxide, adjust the pH to 6-8, filter out the filter residue, and the obtained solution is the soil heavy metal activator.

The 1) is specifically: the lime nitrogen powder is dissolved in a hydroxylamine hydrochloride solution with a mass fraction of 0.1% to 98%, and the active ingredient molar ratio of the lime nitrogen powder to the hydroxylamine hydrochloride solution is 1:2 to 2:1, Closed and stirred for 10-20min.

In the above preparation method reaction process, the equation is represented by the following formula:

The overall reaction can be expressed as:

In all above embodiments, the application of described soil heavy metal activator in activating soil heavy metal elements is as follows:

The soil heavy metal activator can be applied to the activation of soil heavy metal elements, and the soil heavy metal elements include copper, lead, zinc, cadmium, nickel, mercury, arsenic, antimony, chromium, iron, manganese, gold, silver, platinum, thallium , one or more of uranium and rare earth elements.

In above all embodiments, the using method of described soil heavy metal activator aspect soil heavy metal activation is:

1) The soil heavy metal activator is added to the heavy metal polluted soil at a ratio of active ingredient to soil mass ratio of 0.1 to 20‰, so as to achieve the purpose of soil heavy metal activation.

2) The soil heavy metal activator can be applied to hyperaccumulative plants in a stable growth period or soil buried with hyperaccumulative materials. After activating soil heavy metals, the removal of heavy metals can be achieved through the extraction of hyperaccumulative plants and hyperaccumulative materials. The purpose of soil heavy metals.

3) For multiple applications, the application interval of the soil heavy metal activator is once every 5 days to 30 days.

The soil heavy metal activator of the present invention activates the soil heavy metal mechanism: in the main active component structure of the soil heavy metal activator, the amidoxime group, amino group or amino group is used as a soft base to coordinate with the soft acid heavy metal element, and the number of amino groups or amino groups is relatively important The soft alkalinity of the active ingredient has a regulating effect. The more amino groups or amino groups, the higher the soft alkalinity of the main active ingredient, and the metal elements with higher soft acid performance, such as: cadmium and mercury, the higher the selectivity and stable complexation The higher the resistance, the higher the performance of hard acid metal elements, such as: the lower the selectivity of calcium and magnesium, and the lower the complexation stability; the soft alkalinity of active ingredients is different with different amino groups or the number of amino groups, and the coordination and complexation of heavy metal elements Stability and selectivity are different.

The amidoxime group, amino group or amino group in the main active ingredient of the soil heavy metal activator of the present invention are easily oxidized and degraded, so it is best to prepare and use it immediately and take maintenance measures. The incompletely reacted cyano group and amino group or amine group raw material, hydroxylamine and sodium carbonate that may be contained in the activator of the present invention are all harmless to the soil system, and compounds such as cyano group such as cyanamide and dicyandiamide itself have a large number of applications One of the pesticides and fertilizers.

In all the above embodiments, the soil heavy metal activator is further crystallized and purified to obtain the active ingredient of the heavy metal activator, which can be used in metal ore leaching and mining, selective masking of metal elements, and selective washing and removal of metal elements. application.

Various chemical reagent raw materials and instruments described in the present invention are all commercially available, and those skilled in the art can purchase and use them conveniently.

The present invention at least reaches the following all beneficial effects:

1) The present invention proposes a novel soil heavy metal activator containing amidoxime group and amino group or containing amidoxime group and amino group, which can effectively activate soft acids such as copper, lead, zinc, cadmium, nickel, mercury in soil 2) The activator of the present invention does not enrich hard acid ions such as calcium, magnesium, aluminum, iron, etc. with high content in the soil; 3) The amine group or amino group and amidoxime in the activator structure The base is easily degraded into soil nitrogen, which can promote plant growth and has no secondary environmental risks; 4) The soil heavy metal activator described in this case can be further crystallized and purified to obtain the active ingredient of the heavy metal activator, which can be extracted from metal ore Applications in mining, selective masking of metal elements, and selective washing and removal of metal elements.

detailed description

The technical solutions of the present invention will be further elaborated below in conjunction with specific embodiments. The schemes described in the examples are only used to better illustrate the present invention, rather than limiting the protection scope of the present invention.

Embodiment one

A kind of soil heavy metal activator, the preparation method of described soil heavy metal activator is:

1) dissolving lime nitrogen powder in hydroxylamine hydrochloride solution, sealing and stirring;

2) Heat to 60°C~85°C, stir and react at constant temperature for 3~5 hours, then cool to room temperature;

3) Pass in carbon dioxide, adjust the pH to 6-8, filter out the filter residue, and the obtained solution is the soil heavy metal activator.

Step 1) specifically: dissolving the lime nitrogen powder in 20% hydroxylamine hydrochloride solution, 80 g of the lime nitrogen powder and 400 g of the hydroxylamine hydrochloride solution, closed and stirred for 15 minutes;

Step 2) specifically: heating to 70°C, stirring and reacting at constant temperature for 5 hours, and cooling to room temperature;

Step 3) Specifically: inject carbon dioxide into the solution, adjust the pH to 7~8, filter out the filter residue, and the obtained solution is activator 1# containing 15% of the main active ingredient.

Embodiment two

A kind of soil heavy metal activator, the preparation method of described soil heavy metal activator is:

1) 70 g of analytically pure hydroxylamine hydrochloride was dissolved in 100 mL of water, 200 g of analytically pure sodium carbonate decahydrate was added, and stirred to dissolve;

2) Add 100mL of 50% cyanamide solution into the above system, and stir well in a closed manner;

3) Heat to 80°C, stir and react at constant temperature for 4 hours, and cool to room temperature to obtain activator 2# containing 10% of the main active ingredient.

Embodiment Three

A kind of soil heavy metal activator, the preparation method of described soil heavy metal activator is:

1) Take 70g of analytically pure hydroxylamine hydrochloride and dissolve it in 100mL of water, add 200g of analytically pure sodium carbonate decahydrate, and stir to dissolve;

2) Take 68 g of analytically pure tetrakis (2-cyanoethyl) ethylenediamine, add it to the above system, and stir evenly in an airtight manner;

3) Heat to 80°C, stir and react at constant temperature for 4 hours, and cool to room temperature to obtain activator 3# containing 23% of the main active ingredient.

Embodiment four

By the obtained soil heavy metal activator of above embodiment one～three, carry out following soil activation test:

1) Dilute 5mL of 1#, 2#, and 3# activators prepared in the above examples to 100mL, that is, the concentrations of each activator are: activator 1# 7.5‰, activator 2# 5‰, activator 3 #11.5‰.

2) Take 1Kg of the same batch of soil and divide it into 10 parts, each sample soil weighs 100g, and each activator activates three samples.

3) Add 100mL of activator to 100g of soil sample, stir well, soak at room temperature for 1 day, the amount of activator added is equivalent to 7.5‰, 5‰ and 11.5‰ of the soil weight.

4) Take about 5g of soil for each soil sample, put it in a 20mL centrifuge bottle, add ultrapure water, stir well, centrifuge at 20,000 rpm, pour off the supernatant, repeat the centrifugal extraction operation of the soil sample 3 times, and finally test the soil for heavy metals content.

Average the heavy metal test results of three activated samples of each activator, as shown in the following table:

Table 1 Activation effect of heavy metals in farmland soil (unit: mg/kg):

The results show that the activator has a good coordination and complexation effect on metal ions with strong soft acidity such as mercury and cadmium, which is significantly higher than that of copper, lead and zinc. In addition, the concentration gradient effect of the activator is also quite significant.

Embodiment five

With prepared heavy metal activator 2# in the above embodiment 2, carry out following activation experiment:

1) Get 20kg of polluted soil with an average cadmium content of 3.84mg/kg, pack five soil pots on average, transplant 3 grain amaranths with a height of 15cm in each soil pot, grow steadily for 30 days, and prepare with the above-mentioned embodiment 2 respectively The 2# dilution of the activator carried out the chelation-induced plant extraction test;

2) Configure the activator 2# to the concentration of 0.5‰, 1.0‰, 2.0‰, 2.5‰, and the activating dose of each concentration is 1000mL, and apply them evenly into the soil pots numbered ②, ③, ④, ⑤, and the numbers are ① The soil basin was used as a control sample, and 100mL of tap water was added. The amount of activator added is equivalent to 0.125‰, 0.25‰, 0.5‰ and 0.625‰ of the soil weight;

3) Carry out indoor cultivation for 20 days. During this period, 300mL of tap water was poured into each soil basin every morning, and the water leaked from the bottom hole of each soil basin to the chassis was poured again according to the water volume in the next watering;

4) The soil pots were sampled in the afternoon of the 2nd day, the 5th day, the 10th day, the 15th day and the 20th day respectively. 5g of soil samples were taken from each soil pot; 3 leaves were taken from each seed amaranth plant in each soil pot, a total of 9 leaves. Put the soil sample into a 20mL centrifuge bottle, add ultrapure water, stir well, centrifuge at 20,000 rpm, repeat the centrifugation and extraction operation of the soil sample 3 times, collect the centrifuged supernatant for 3 times, and test the cadmium content and total organic nitrogen in the supernatant content. The cadmium content index in the supernatant was converted into the soil activation state content index, and the total organic nitrogen was used as the soil activator degradation index. Nine leaf samples from each soil pot were analyzed for cadmium content, which was used as an indicator of cadmium enrichment in grain amaranth in the pot.

The test results are as follows:

Table 2 Effects of activators on the extraction of cadmium from grain amaranth (unit: mg/kg):

The results of this example show that the activator effectively activates the cadmium element in the soil, and at the same time promotes the absorption of the cadmium element by the grain amaranth. During the 20-day indoor cultivation process, the grain amaranth grows well; the trend of the total dissolved organic nitrogen content in the soil changes It shows that the activator can be basically degraded in the soil in about 10 days.

Those skilled in the art should know that the purpose of the disclosed embodiments of the present invention is to help further understanding of the present invention, and the description is more specific and detailed, but should not be construed as limiting the patent scope of the present invention. However, those skilled in the art can understand that without departing from the spirit and scope of the present invention and the appended claims, several modifications and improvements can be made, and various replacements and modifications are possible, and these all belong to this invention. protection scope of the invention. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the protection scope of the present invention is subject to the scope defined in the claims.

Claims (9)

1. a soil heavy metal activator, is characterized in that: comprise active component, contain an amidoxime group and an amino group at least in the molecular structure of described active component, or contain at least an amidoxime group and an amine group . 2. a kind of soil heavy metal activator according to claim 1, is characterized in that: the composition of described soil heavy metal activator can also comprise: hydroxylamine compound, sodium carbonate, molecular structure containing cyano group and amino group or containing cyano group simultaneously and amine-based organic compounds, water. 3. a kind of soil heavy metal activator according to claim 1, is characterized in that: the preparation method of described soil heavy metal activator is: under the condition that sodium carbonate and alkali exist with hydroxylammonium hydrochloride, with one or more cyanogen-containing Heating to 60°C~85°C, reacting at constant temperature for 3~5 hours, cooling to room temperature, and adjusting the pH to 6~8, the soil heavy metal activator can be obtained. 4. A kind of soil heavy metal activator as claimed in claim 2 or 3, is characterized in that: the compound containing cyano group and amino group or containing cyano group and amine group includes but not limited to cyanamide, dicyandiamide; Acetonitrile, iminodiacetonitrile; 3-aminopropionitrile, bis(2-cyanoethyl)amine, tris(2-cyanoethyl)amine; tetrakis(2-cyanoethyl)ethylenediamine and other ethylenediamines containing Amino or amino compounds; ethylenediamines containing hydroxyl and containing amino or amino compounds; ethylenediamine containing halogen and containing amino or amino compounds; tetrakis(2-cyanoethyl)propylenediamine and other propylenediamines Amino groups or amino compounds; Propylenediamines contain hydroxyl groups and amino groups or amino compounds; Propylenediamines contain halogens and contain amino groups or amino compounds. 5. soil heavy metal activator as claimed in claim 1, is characterized in that: the preparation method of described soil heavy metal activator can also be: 1) Dissolve lime nitrogen powder in hydroxylamine hydrochloride solution, seal and stir for a certain period of time; 2) Heat to 60°C~85°C, stir and react at constant temperature for 3~5 hours, then cool to room temperature; 3) Introduce carbon dioxide, adjust the pH to 6~8, filter out the filter residue, and the obtained solution is the soil heavy metal activator. 6. according to the preparation method of the described soil heavy metal activator of claim 5, it is characterized in that: described 1) be specifically: be that the mass fraction of lime nitrogen powder is dissolved in the hydroxylamine hydrochloride solution of 0.1%～98%, described lime The active ingredient molar ratio of nitrogen powder to hydroxylamine hydrochloride solution is 1:2~2:1, and the mixture is closed and stirred for 10-20 minutes. 7. The application of the soil heavy metal activator according to any one of claims 1-3 or 5-6 in activating soil heavy metal elements, said heavy metal elements comprising copper, lead, zinc, cadmium, nickel, mercury, arsenic, One or more of antimony, chromium, iron, manganese, gold, silver, platinum, thallium, uranium and rare earth elements. 8. according to any one of claim 1-3 or 5-6 described soil heavy metal activator, its using method aspect soil heavy metal activation is: 1) adding the soil heavy metal activator to the heavy metal-contaminated soil at a ratio of 0.1 to 20‰ of the active ingredient to the soil mass ratio, to achieve the purpose of soil heavy metal activation; 2) The soil heavy metal activator can be applied to hyperaccumulative plants in a stable growth period or soil buried with hyperaccumulative materials. After activating soil heavy metals, the removal of heavy metals can be achieved through the extraction of hyperaccumulative plants and hyperaccumulative materials. The purpose of soil heavy metals; 3) For multiple applications, the application interval of the soil heavy metal activator is once every 5 days to 30 days. 9. According to any one of claim 1-3 or 5-6, the soil heavy metal activator obtains the active component of the heavy metal activator through further crystallization and purification, and the active component is extracted and selected in metal ore extraction, metal element selective masking , The application of selective washing and removal of metal elements.