JP2010125400A - Purifying agent for soil and underground water contaminated by organic halogen compound and method of manufacturing this purifying agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purifying agent which is composed mainly of iron dust and can certainly purify soil and/or underground water contaminated by an organic halogen compound at a low cost, as well as a method of manufacturing the purifying agent. <P>SOLUTION: The purifying agent comprises mixing iron dust, metal powder with stainless steel present at least, on the surface and nickel salt, and purifies the soil and/or the underground water contaminated by the organic halogen compound. In addition, the metal powder is steel powder which is generated when an austenite-based stainless steel is shot-blasted using a steel grain shot. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a purifying agent that rapidly decomposes soil and / or groundwater contaminated with an organic halogen compound and a method for producing the same.

Organohalogen compounds have been widely used in the semiconductor manufacturing industry, metal processing industry, cleaning industry, etc. as degreasing solvents with excellent dissolving power, but contamination of soil and groundwater by organohalogen compounds after use has become serious. Yes.
Methods for detoxifying organohalogen compounds include removing contaminated soil from its original location, treating soil in situ or groundwater in which organochlorine compounds are dissolved, decomposing organohalogen compounds, and contaminated soil A method for purifying groundwater flowing out from contaminated soil in the surrounding area has been proposed.

  Among these methods, the method of purifying contaminated soil in-situ involves biodegrading with anaerobic microorganisms, bringing iron powder into contact with moisture, and reducing organic halogen compounds with hydrogen generated when iron powder is oxidized. Then, there is a method of decomposition (hereinafter referred to as iron powder method). Among these methods, the iron powder method is currently becoming mainstream because it has excellent reliability of effects and is suitable for treating a large amount of contaminated soil such as a factory site.

As a technique related to such an iron powder method, for example, Patent Document 1 discloses a technique for decomposing an organic halogen compound to purify the soil by adding and mixing iron powder to soil contaminated with an organic halogen compound. Are listed.
Patent Document 2 describes a technique of adding an additive containing an acid in order to enhance the decomposition effect of iron powder.
Furthermore, Patent Document 3 describes a technique for significantly reducing the time required for detoxifying an organic halogen compound by using a purification agent obtained by adding a water-soluble metal salt to iron powder and / or iron oxide powder. Yes.
Furthermore, Patent Document 4 discloses that shot blast dust that collects dust generated when a steel shot is struck to the surface of a steel material and is cleaned has high resolution with respect to an organic halogen compound including metallic iron. As an invention based on this finding, an organohalogen compound decomposing agent having a nickel content of 0.1% by mass or more and the remaining main components being metallic iron and iron oxide is disclosed.
Japanese Patent Application Laid-Open No. 11-235577 JP 2003-326243 A JP 2005-113112 A JP-A-2005-118755

However, as in Patent Document 1, when purifying soil contaminated with an organic halogen compound by adding and mixing iron powder, the composition, particle size, or specific surface area is intended to stabilize the performance as a purifying agent. It seems that it is necessary to use special iron powder (manufactured iron powder) for powder metallurgy adjusted for the above, but if this is attempted, the performance will be stable, but the cost will increase due to the high cost.
Moreover, when using the iron powder which added the acid like patent document 2, although the resolution | decomposability with respect to an organic halogen compound improves by addition of an acid, there exists a concern about the fall of the soil after mixing an iron powder, and groundwater, May adversely affect the surrounding ecosystem.
Furthermore, in the case of the purifier which added the water-soluble metal salt to the iron powder and / or iron oxide powder of patent document 3, the average primary particle diameter of iron powder and / or iron oxide powder shall be 0.05-1 micrometer. This is presumed to be because the detoxifying effect of the organic halogen compound does not appear if the iron powder and / or iron oxide powder and the water-soluble metal salt are not uniformly dispersed when the cleaning agent is made into a slurry state. Is done. Furthermore, since it is mainly composed of fine iron powder and / or iron oxide powder of 0.05 to 1 μm, its production, storage, transportation, etc. are expensive, and it is difficult to say that it is inexpensive.

  In addition, shot blast dust that collects dust generated when a steel shot described in Patent Document 4 is struck on the surface of a stainless steel material and cleaned is excellent in resolution against organic halogen compounds, but the area of contaminated soil is Considering that a large amount of a purifying agent is required, there is a problem that the amount of generated shot blast dust is small and it is difficult to secure a sufficient amount as a purifying agent.

  The present invention has been made to solve such a problem, and a purification agent mainly composed of iron powder capable of reliably and inexpensively purifying soil and / or groundwater contaminated with an organic halogen compound and a method for producing the same. The purpose is to provide.

The inventor has intensively studied for a purifying agent that has a purifying ability equivalent to that of steel powder generated when stainless steel is shot with a steel shot, and can be manufactured in a large amount at a low cost.
The inventor pays attention to the fact that the amount of nickel contained in the steel powder generated when hitting stainless steel containing nickel typified by austenitic stainless steel with steel shot, We thought that by mixing water, nickel was adhered to the surface of the iron powder electrochemically to produce a purifier. However, the mixture of iron powder, nickel salt and water has a higher resolution with respect to organic halogen than the iron powder alone, but no significant effect was obtained.

Therefore, the inventor further studied and tried to add steel powder generated when striking various stainless steels with steel shots when mixing iron powder, nickel salt and water. It has been found that the resolution to halogen is greatly improved.
This is because the action of the stainless steel present in the steel powder promotes the electrochemical bonding of the ionized nickel to the iron powder, and the nickel salt partially adheres to the surface of the iron powder effectively. It is presumed that a steel powder corresponding to the steel powder generated when the above-described nickel-containing stainless steel is shot with a steel shot is generated.
Further, as the steel powder, by using the steel powder generated when shot blasting austenitic stainless steel with steel shot, nickel nickel chloride is effectively attached to the iron powder and the organic steel powder has It was also possible to use the resolution for halogens, and in the dual sense, it was also found that a purifier having an excellent resolution for organic halogens could be obtained.
The present invention is based on such knowledge, and specifically has the following configuration.

(1) The purification agent for soil and / or groundwater contaminated with an organic halogen compound according to the present invention comprises iron powder, metal powder having stainless steel at least on the surface, and a nickel salt. It is what.

(2) Further, in the above (1), the metal powder is steel powder generated when austenitic stainless steel is shot blasted by steel shot.

(3) Further, in the above (2), the addition amount of the metal powder is 5% by mass or more with respect to the purifier to be produced.

(4) Further, in any of the above (1) to (3), the nickel salt is nickel chloride.

(5) Further, in the above (4), the addition amount of nickel chloride is 0.3% by mass or more with respect to the purifier to be produced.

(6) The method for producing a soil and / or groundwater purification agent contaminated with an organic halogen compound according to the present invention comprises a first step of mixing iron powder, a nickel salt and water, and a mixture produced in the first step. And at least a second step of mixing metal powder having stainless steel on the surface and iron powder.

(7) Moreover, in the thing as described in said (6), in a 1st process, 150 mass parts or more of iron powder and 500 mass parts or less of water are mixed with respect to 100 mass parts of nickel salts, To do.

(8) Further, in the above (6) or (7), the metal powder is a steel powder generated when shot blasting austenitic stainless steel, the nickel salt is nickel chloride, and the metal powder The amount of the additive is 5% by mass or more with respect to the produced purifier, and the amount of nickel chloride added is 0.3% by mass or more with respect to the produced purifier.

  INDUSTRIAL APPLICABILITY According to the present invention, it is a purification agent that can reliably and rapidly decompose and remove organic halogen compounds from soil and / or groundwater contaminated with organic halogen compounds, and can be manufactured at a low cost. It is.

[Embodiment 1]
The purifying agent according to the present invention is a mixture of iron powder, metal powder having stainless steel at least on the surface (hereinafter sometimes simply referred to as “metal powder”), and nickel salt, and is contaminated with an organic halogen compound. It is a purification agent for purifying soil and / or groundwater. And a purification effect is exhibited by substituting a halogen atom of an organic halogen compound for a hydrogen atom via a purification agent.

<Iron powder>
As the iron powder used for this purifier, normal iron powder, reduced iron powder, and electrolytic iron powder can be used, but iron powder whose iron powder surface is not covered with an oxide film is preferable. However, when the iron powder surface is covered with an oxide film, it can be used by removing the oxide film on the surface with an acidic solution.
Further, the iron powder particle size is preferably less than 500 μm from the specific surface area and the characteristics of the equipment used for mixing. This is because, when the particle size is 500 μm or more, the specific surface area of the iron powder is reduced, so that the reactivity is remarkably deteriorated. This is because wear occurs.

<Metal powder>
The metal powder needs to have stainless steel on the surface. Here, the stainless steel is preferably stainless steel containing nickel. The metal powder having stainless steel on the surface is not particularly limited, but is preferably inexpensive and easily available. For example, shot blast dust obtained by striking various stainless steels with steel shots is preferable. Among them, shot blast dust generated by striking steel shots on austenitic stainless steel, which is representative of nickel-containing stainless steel, has an excellent organohalogen compound resolution. preferable.

In order to investigate what kind of stainless steel shot blast dust is suitable for the cleaning agent of the present invention, the following experiment was conducted.
Reduced iron powder with an average particle size of 100μm: 89.5% by mass, nickel chloride: 0.5% by mass, 10% of shot blast dust with an average particle size of 80μm generated by striking various stainless steels with 105μm sieve 1.5 g of a purification agent produced by adding 30% and mixing for 30 minutes was added to 30 mL of groundwater contaminated with tetrachloroethylene, and the concentration of tetrachlorethylene after 24 hours of stationary storage was measured.

FIG. 1 is a graph showing measurement data of this experiment, in which the vertical axis represents the tetrachlorethylene concentration (mg / L) and the horizontal axis lists various stainless steels.
As shown in FIG. 1, the purification agent using shot blast dust generated by hitting steel shots on austenitic stainless steel rather than ferritic stainless steel, martensitic stainless steel, and nickel alloy. It was confirmed that the resolution was the best.

In addition, the following experiment was conducted in order to confirm how much the amount of shot blast dust added by hitting an iron material to austenitic stainless steel should be increased.
Shot blast generated by striking iron on austenitic stainless steel with nickel chloride: 0.5% by mass and various added amounts of average particle size of 80μm for 100g of soil contaminated with tetrachlorethylene (water content 23% by weight) Tetrachlorethylene concentration after 7 days after adding 10 g of purified material 5 g obtained by mixing dust and reduced iron powder having an average particle size of 100 μm for 30 minutes and 10 g of distilled water was measured.
FIG. 2 is a graph showing the results of this experiment, where the vertical axis represents the tetrachlorethylene concentration (mg / L) and the horizontal axis represents the shot blast dust addition amount (Wt%).

As shown in FIG. 2, it was confirmed that excellent decomposition performance was exhibited by mixing 5% by mass or more of shot blast dust. Therefore, the amount of shot blast dust added is preferably 5% by mass or more.
Note that when shot blast dust was less than 5% by mass, the resolution could not be sufficiently exhibited. If less than 5% by mass, shot blast dust and reduced iron powder were not mixed uniformly, and the electrochemistry of individual iron powder particles It is presumed that this was because sufficient effects of promoting nickel adhesion were not obtained.

<Nickel salt>
In order to confirm what kind of nickel salt should be used for improving the resolution of the purifier, the following experiment was conducted.
Reduced iron powder with an average particle size of 100 μm: 89.5% by mass, shot blast dust with an average particle size of 80 μm generated by striking iron on austenitic stainless steel: 10% by mass, and various metal salts: 0.5% by mass Was added to 30 mL of groundwater contaminated with tetrachloroethylene, and the concentration of tetrachloroethylene after 24 hours of stationary storage was measured.

FIG. 3 is a graph showing measurement data of this experiment. The vertical axis represents the tetrachlorethylene concentration (mg / L), and the horizontal axis represents various nickel salts.
As shown in FIG. 3, it was confirmed that in the nickel salt, nickel chloride protrudes and has excellent resolution.

In addition, the following experiment was conducted in order to investigate the relationship between the resolution for tetrachlorethylene and the nickel chloride addition rate.
Shot blast dust generated by striking iron on austenitic stainless steel with an average particle size of 80μm: 10% by mass, various addition amounts of nickel chloride, reduced iron powder with an average particle size of 100μm mixed for 30 minutes 5 g of the purification material and 10 g of distilled water were added to and mixed with 100 g of soil contaminated with tetrachlorethylene (water content: 23 mass%), and the tetrachloroethylene concentration after 7 days was measured.

FIG. 4 is a graph in which the measurement results are arranged. The vertical axis represents the tetrachlorethylene concentration (mg / L), and the horizontal axis represents the nickel chloride addition rate (mass%).
As shown in FIG. 4, it can be seen that excellent resolution can be obtained when the amount of nickel chloride added is 0.3% by mass or more, preferably 0.4% by mass or more and 2.0% by mass or less, with respect to the purifier to be produced.
This is because when 0.3% by mass or less, electrochemical nickel adhesion to individual iron powder particles is insufficient, and when 2.0% by mass or more, oxidation of iron powder proceeds due to high reactivity. However, it is presumed that most of the surface of the iron powder is covered with an oxide film due to the bond with oxygen in the soil before the decomposition of tetrachloroethylene is performed, and the resolution is lowered.

[Embodiment 2]
In general, a cleaning agent mainly composed of iron powder for decomposing organic halogen compounds is made into a slurry by adding water, and then mechanically agitated with the soil contaminated with organic halogen compounds, or jet The method of injecting into the soil by spraying is performed.
Even in the cleaning agent of the present invention, it is possible to mix iron powder, metal powder having at least stainless steel on the surface, nickel salt, and water into a slurry state at the contaminated site.
However, when the particle sizes of iron powder and metal powder are greatly different, it is difficult to uniformly disperse iron powder particles and metal powder particles in the slurry by stirring with a stirrer or forced circulation with pumps. When uniform dispersion is not possible, the metal powder does not exist in the vicinity of the iron powder, and the function of electrochemically attaching nickel in the metal powder to the iron powder cannot be fully exhibited, and nickel partially adheres to the iron powder. There is a possibility that the developed state cannot be sufficiently formed.

Therefore, rather than mixing at the contaminated site as described above to form a slurry, iron powder, metal powder having stainless steel at least on the surface, nickel salt, and water are mixed in advance. It is better to manufacture a cleaning agent in which nickel is electrochemically partially adhered to the surface, and to put the cleaning agent in a slurry state at the contaminated site.
However, as described above, the optimum addition amount of nickel salt is as small as 2% by mass or less with respect to the produced purification agent, so it is difficult to uniformly disperse iron powder, metal powder, and nickel salt. In order to disperse uniformly, an expensive mixing device and a long mixing operation are required.
Also, when water is added during mixing to uniformly disperse the nickel salt, a certain amount of water is required as the amount of water to be added, and it is necessary to dry after mixing, which increases manufacturing costs. Will also be invited.

  Therefore, as a result of intensive studies on a method for producing a purifier that is inexpensive and can reduce the production time, the inventors first mixed nickel salt, iron powder, and water (first step), The inventors have found a method in which the mixing step is divided into two steps, such as mixing metal powder and iron powder (second step).

Hereinafter, the manufacturing method of the purification | cleaning agent which concerns on embodiment of this invention is demonstrated in detail.
FIG. 5 is a process diagram showing an embodiment of the purification agent production method according to the present invention. In the figure, 1 shows the 1st process which mixes iron powder, nickel salt, and water, 2 shows the 2nd process which mixes the intermediate goods manufactured at the 1st process, iron powder, and metal powder.

<First step>
The first step is a step of mixing an iron powder, a nickel salt, and water to produce an intermediate product for uniformly dispersing the iron powder and metal powder added in the second step.
By going through the process of manufacturing the intermediate product, the nickel product, the appropriate amount of iron powder, and the intermediate product in which the nickel salt is uniformly dispersed by mixing water is used to purify the final product in the second process. This is because the weight ratio of the intermediate product with respect to the agent is increased and the mixing property with the iron powder and the metal powder is improved, so that the nickel salt can be uniformly dispersed in the cleaning agent.

  In addition, by setting the weight ratio of the intermediate product to 5% by mass or more with respect to the final manufactured purification agent, it can be easily and uniformly mixed with a cheaper device, and the addition of the nickel salt as described above When the amount is 2% by mass or less, the iron powder added in the first step is preferably made 150% by mass or more of the nickel salt.

In the first step, the iron powder is used instead of the metal powder for mixing with the nickel salt for the following reason.
When nickel salt and metal powder are mixed in the first step, for example, shot blast dust obtained by striking iron material against austenitic stainless steel as metal powder, and when this and nickel salt are mixed, shot blast dust The nickel salt nickel is locally concentrated on the metal contained in the metal due to the electrochemical action, and the nickel salt nickel may not adhere to the iron powder electrochemically in the second step. It is.

In the first step, it is better to add water in order to achieve further uniform dispersion of the nickel salt. Even if water is added, in the second step, the added water acts as a reducing agent in the second step, electrochemically due to reaction heat generated when nickel partially adheres to the surface of the iron powder, Drying can be performed without heating from the outside, and a dried cleaning agent can be obtained without a separate drying step.
Therefore, the amount of water to be added may be an amount added to achieve uniform dispersion of the nickel salt and promote the electrochemical reaction in the second step.

The inventor conducted the following experiment in order to investigate the optimum amount of added water.
Iron powder with an average particle size of 180μm: 4.5% by mass, nickel chloride: 0.5% by mass with the prescribed distilled water and mixing for 5 minutes, then reduced iron powder with an average particle size of 180μm: 85% by mass, iron on austenitic stainless steel Shot blast dust with an average particle size of 80μm generated by striking 5g: 5g of cleaning agent mixed with 10% by mass and mixed for 5 minutes was sampled and 10g of distilled water was added to form a slurry, contaminated with tetrachlorethylene Soil (moisture content 23 mass%): Tetrachlorethylene concentration 7 days after mixing with 100 g was measured.

FIG. 6 is a graph showing the measurement results. The vertical axis represents the tetrachlorethylene concentration (mg / L), and the horizontal axis represents the amount of water added (wt /%).
As can be seen from FIG. 6, when the amount is less than 20% by mass, the dispersion of the organic halogen compound is low because the dispersion is insufficient. When the amount exceeds 500% by mass, the cleaning agent after completion of the mixing in the second step is not dried ( A black circle indicates that it is not dried.) A drying process is required again.
Therefore, the amount of water added is preferably 20% by mass or more and 500% by mass or less.

<Second step>
The second step is a step of mixing the intermediate product manufactured in the first step, iron powder, and metal powder.
In addition, when the intermediate product manufactured at the 1st process has dried before the 2nd process, it is preferable to add an appropriate amount of water at the 2nd process.
In addition, in the cleaning agent produced in the second step, when secondary lumps are generated by drying due to reaction heat during the production of the cleaning agent, the cleaning agent may be crushed in a subsequent step (see FIG. 1). Crushing step 3).

The purifying agent of the present invention exhibits excellent organic halogen resolving power by the interaction of each constituent component constituting the purifying agent. In order to confirm this point, the following experiment was conducted.
As Example 1, 30 mL of groundwater contaminated with trichlorethylene was collected in a 33 mL vial, and reduced iron powder with an average particle size of 100 μm: 89.5 mass%, generated and collected by striking austenitic stainless steel with a steel shot. Shot blast dust having an average particle size of 80 μm: 10% by mass, nickel chloride: 0.5% by mass was added, and 1.5 g of a purification agent mixed for 30 minutes with a portable mixer was added. And the trichlorethylene density | concentration 24 hours after stationary storage was measured.

  As Comparative Example 1, 1.5 g of a purifier containing 100% by mass of reduced iron powder was used, and other conditions were tested in the same manner as in Example 1. That is, Comparative Example 1 is different from Example 1 in that nickel chloride and shot blast dust are not added.

As Comparative Example 2, 1.5 g of a purification agent prepared by adding reduced iron powder with an average particle size of 100 μm: 98.0% by mass, phosphoric anhydride: 2.0% by mass, and mixing for 30 minutes in a portable mixer is used. The test was conducted in the same manner as in 1. That is, Comparative Example 2 is different from Example 1 in that nickel chloride and shot blast dust are not added, but phosphoric anhydride is added.
This Comparative Example 2 corresponds to Patent Document 1.

As Comparative Example 3, 1.5 g of a purifier prepared by adding reduced iron powder with an average particle size of 100 μm: 99.5% by mass, nickel chloride: 0.5% by mass, and mixing for 30 minutes in a portable mixer is used. The test was conducted in the same manner as above. That is, Comparative Example 3 is different from Example 1 in that shot blast dust is not added.
This Comparative Example 3 corresponds to Patent Document 3.

  As Comparative Example 4, reduced iron powder having an average particle size of 100 μm: 89.5% by mass, shot blast dust having an average particle size of 80 μm generated and recovered by striking an austenitic stainless steel: 10% by mass, copper chloride: 0.5 The test was carried out in the same manner as in Example 1 except that 1.5 g of a purifier prepared by adding 30% by mass and mixing with a portable mixer for 30 minutes was used. That is, Comparative Example 4 is different from Example 1 in that copper chloride is added instead of nickel chloride.

As Comparative Example 5, 1.5 g of a purifier composed of 100% by mass of shot blast dust having an average particle size of 80 μm generated and recovered by hitting an austenitic stainless steel with an iron material was used. A test was conducted. That is, Comparative Example 5 is different from Example 1 in that iron powder and nickel chloride are not used.
Comparative Example 5 corresponds to Patent Document 4.
Table 1 shows the components and the proportions of the above-described Examples 1 to 5 and the trichlorethylene concentration after 24 hours of stationary storage as experimental results.

  When the trichlorethylene concentrations in Example 1 and Comparative Example 1 are compared, Example 1 is 0.98 (mg / L), while Comparative Example 1 is 3.28 (mg / L). It can be seen that the halogen resolution is superior to that of Comparative Example 1 using only reduced iron powder.

  When the trichlorethylene concentration in Example 1 and Comparative Example 2 is compared, Example 1 is 0.98 (mg / L), while Comparative Example 2 is 2.53 (mg / L). It can be seen that the halogen resolution is superior to that of Comparative Example 2. This indicates that the addition of nickel chloride and austenitic shot blast dust to the reduced iron powder carried out in Example 1 is more effective for organic halogen resolution than the addition of phosphoric anhydride. ing. This also indicates that the present invention is superior in organic halogen resolution as compared to Patent Document 1.

  When the trichlorethylene concentration in Example 1 and Comparative Example 3 is compared, Example 1 is 0.98 (mg / L), while Comparative Example 3 is 2.79 (mg / L). It can be seen that the halogen resolution is superior to that of Comparative Example 3. This is because the addition of nickel chloride and austenitic shot blast dust to the reduced iron powder carried out in Example 1 has a higher organic halogen resolution than the addition of only nickel chloride without adding shot blast. Indicates that it is valid. This also indicates that Example 1 is superior in organic halogen resolution as compared with Patent Document 3.

  Comparing the trichlorethylene concentrations in Example 1 and Comparative Example 4, Example 1 was 0.98 (mg / L), while Comparative Example 4 was 3.03 (mg / L). It can be seen that the halogen resolution is superior to that of Comparative Example 4. This is because adding nickel chloride and austenitic shot blast dust to the reduced iron powder used in Example 1 is more effective for organic halogen resolution than adding copper chloride to shot blast. Is shown.

When the trichlorethylene concentration in Example 1 and Comparative Example 5 is compared, Example 1 is 0.98 (mg / L), while Comparative Example 5 is 0.92 (mg / L). Although the organic halogen resolution is superior to that of Example 1, it can be seen that Example 1 and Comparative Example 5 are substantially equivalent in organic halogen resolution.
That is, the comparative example is 100% by mass of austenitic shot blast dust, and it has been conventionally known that this is excellent in organic halogen resolution, but Example 1 is a purifying agent having organic halogen resolution equivalent to this. It was confirmed that there was.

  As described above, by comparing the effect of Example 1 with each comparative example, it is confirmed that Example 1 exhibits excellent organic halogen resolution due to the interaction of each constituent component constituting the purifier. It was.

  The method for producing a purifying agent of the present invention comprises a first step of mixing iron powder, a nickel salt, and water, a mixture produced in the first step, and a metal powder having at least stainless steel on the surface and iron powder. The second step is performed. That is, the purifier is produced through the two steps of the first step and the second step. In the following, an experiment was conducted to confirm the effect of passing through these two steps.

As Example 2, reduced iron powder having an average particle size of 100 μm: 45 g, nickel chloride: 5 g, and distilled water: 20 g were added and mixed for 5 minutes with a portable mixer. Immediately after the mixing is completed, 7g is collected, reduced iron powder with an average particle size of 100μm: 85g, shot blast dust with an average particle size of 80μm generated and recovered by striking an austenitic stainless steel with iron material: 10 g was added and mixed for 5 minutes in a portable mixer. Collect 5g of the cleaning agent after the completion of the second mixing and add 10g of distilled water to form a slurry. Soil contaminated with cis-1,2-dichloroethane (moisture content 28% by mass): 100g Mixed.
After mixing, it was packed in a 100 mL vial and stored stationary. The soil elution value of cis-1,2-dichloroethane after 3 days of stationary storage was measured.

  As Comparative Example 6 with respect to Example 2, reduced iron powder with an average particle size of 100 μm: 89.5% by mass, shot blast dust with an average particle size of 80 μm generated and recovered by striking an austenitic stainless steel: 10% by mass, Soil contaminated with cis-1,2-dichloroethane by adding 10 g of distilled water (10 g) to 5 g of the purification agent mixed with nickel chloride: 0.5% by mass and mixed with a portable mixer for 30 minutes (water content) 28% by mass): Added to 100 g and mixed. The other tests were performed in the same manner as in Example 2. That is, the difference between Example 2 and Comparative Example 6 is that Example 2 undergoes two steps of producing the purifier, the first step and the second step, whereas the comparative example has one step. This is the point of manufacturing the purifier.

Next, as Example 3, the average particle size of the reduced iron powder was changed to 180 μm, and the other experiments were performed in the same manner as in Example 2.
Moreover, as Comparative Example 7 of Example 3, the average particle size of the reduced iron powder was changed to 180 μm, and the other experiments were performed in the same manner as Comparative Example 6.

  Table 2 shows the components of Examples 2 and 3 and Comparative Examples 6 and 7 and their proportions, the mixing method, the mixing time, and the cis-1,2-dichloroethane concentration after 3 days of stationary storage as experimental results.

When the mixing time and the cis-1,2-dichloroethane concentration in Example 2 and Comparative Example 6 in Table 2 were compared, the mixing time in Example 2 was 10 minutes and the cis-1,2-dichloroethane concentration was 2.87 (mg / L). On the other hand, the mixing time of Comparative Example 6 is 30 minutes, and the cis-1,2-dichloroethane concentration is 3.14 (mg / L). From this, it can be seen that according to the production method of the present invention, the production time is remarkably shortened and the performance as a purifier is excellent.
In addition, when the mixing time and the cis-1,2-dichloroethane concentration in Example 3 and Comparative Example 7 in Table 2 were compared, the mixing time in Example 3 was 10 minutes and the cis-1,2-dichloroethane concentration was 3.27 mg / mg. In contrast, the mixing time of Comparative Example 7 is 30 minutes and the cis-1,2-dichloroethane concentration is 18.6 (mg / L). From this, according to the production method of the present invention, it was confirmed that the production time is remarkably shortened and the effect of improving the performance as a purification agent is high particularly when the average particle size of the reduced iron powder is large. .

It is a figure which shows the relationship between the kind of shot blast dust at the time of adding various shot blast dust with respect to the groundwater contaminated with tetrachlorethylene, and a purification effect. It is a figure which shows the influence of the shot blast dust addition rate which acts on the resolution | decomposability of tetrachlorethylene with respect to the soil contaminated with tetrachlorethylene. It is a figure which shows the relationship between the kind of nickel salt, and a purification effect at the time of adding various nickel salt with respect to the groundwater contaminated with tetrachlorethylene. It is a figure which shows the influence of the nickel chloride addition rate which acts on the resolution | decomposability of tetrachlorethylene with respect to the soil contaminated with tetrachlorethylene. It is a figure which shows the influence of the water addition rate in the 1st process in one Embodiment of this invention. It is a figure which shows the purification agent manufacturing method which concerns on one Embodiment of this invention.

Explanation of symbols

1 1st process 2 2nd process 3 Crushing process

Claims (8)

A cleaning agent for soil and / or groundwater contaminated with an organic halogen compound, comprising iron powder, metal powder having at least stainless steel on the surface, and nickel salt. The purifier for soil and / or groundwater contaminated with an organic halogen compound according to claim 1, wherein the metal powder is steel powder generated when austenitic stainless steel is shot blasted by steel shot. The purification agent for soil and / or groundwater contaminated with an organic halogen compound according to claim 2, wherein the amount of metal powder added is 5% by mass or more based on the produced purification agent. The purifier for soil and / or groundwater contaminated with an organic halogen compound according to any one of claims 1 to 3, wherein the nickel salt is nickel chloride. The purification agent for soil and / or groundwater contaminated with an organic halogen compound according to claim 4, wherein the amount of nickel chloride added is 0.3% by mass or more based on the produced purification agent. A first step of mixing iron powder, nickel salt, and water; and a second step of mixing the mixture produced in the first step with a metal powder having at least stainless steel on the surface and iron powder. A method for producing a soil and / or groundwater purifier contaminated with a characteristic organic halogen compound. The soil contaminated with the organohalogen compound according to claim 6, wherein in the first step, iron powder of 150 parts by mass or more and water of 500 parts by mass or less are mixed with 100 parts by mass of nickel salt. And / or a method for producing a purification agent for groundwater. The metal powder is a steel powder generated when shot blasting austenitic stainless steel, the nickel salt is nickel chloride, and the added amount of the metal powder is 5% by mass or more with respect to the purifier to be produced. The amount of nickel chloride added is 0.3% by mass or more based on the produced purification agent, and the purification agent for soil and / or groundwater contaminated with an organic halogen compound according to claim 6 or 7 Manufacturing method.

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