JP2008142693A - Iron powder for organic chlorinated compound decomposition, its manufacturing method, and detoxifying treatment method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of being required for an iron powder for decomposition having a high decomposition performance of organic chlorinated compounds in a solid such as in soil and also having a low Ni content. <P>SOLUTION: The iron powder for decomposition of the organic chlorinated compounds comprising less than 40 wt.% of a particle size of less than 53 μm, 0.1 to 0.5 wt.% of the amount of Ni and 0.005 to 5 wt.% of the amount of carbon is used. It is particularly preferable that Ni, carbon and iron are partially alloyed. When the iron powder for decomposition and an Ni-free iron powder are mixed and used, the total Ni content can be reduced without a reduction in decomposition performance of organic chlorinated compounds. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a detoxifying agent for an object to be treated such as soil, industrial waste, sludge, sludge, drainage, groundwater, etc. contaminated with an organic chlorinated product, and a detoxifying treatment method using the same.

  In recent years, environmental pollution problems due to organic halogen compounds such as TCE (trichloroethylene), PCE (tetrachloroethylene), dichloromethane, PCB (polychlorinated biphenyl) and dioxins have become a major problem, soil contaminated by these organic halogen compounds, Treatment agents for detoxification of drainage, groundwater, etc. and treatment methods thereof are being studied.

  For example, a technique for reducing and dechlorinating contaminated waste water and water with Fe powder, Ni or Cu chemical plating Fe powder has been reported (for example, Non-Patent Document 1). However, it is necessary to remove dissolved oxygen from contaminated wastewater and irrigation water in order to suppress the deterioration of performance over time of these treatment agents themselves, and the effect can be obtained unless the range of nickel plating amount showing activity is large. I couldn't.

  In the case of treatment methods for contaminated soil, sludge, sludge, etc., particularly as a chemical treatment, a method of adding and treating an iron-based treatment agent containing carbon to a limited range of contaminated soil (for example, Patent Document 1), or Fe A treatment method (for example, Patent Documents 2 and 3) using a metal-based treatment agent in which Ni, Cu, and carbon are combined has been reported. However, the resolution was still not sufficient.

  In addition, decomposition of organochlorine compounds, which are metal processing agents combining Fe and different elements, has been reported (for example, Patent Documents 4 and 5). However, a highly active iron powder having a large proportion of fine particles of 50 μm or less by a strong pulverization technique has a problem in safety such as ignition. Furthermore, although fine iron powder has high performance in aqueous solution, it is difficult to uniformly mix with solid materials such as soil, and sufficient characteristics are not exhibited.

So far, organochlorine compound-decomposed iron powder containing Ni or carbon has been known, but the degradation rate is slow for solids such as soil (solid-liquid mixed system), and it is difficult to decompose even in aqueous solution. However, it is necessary to increase the Ni content in order to achieve sufficient performance. (Patent Documents 6 to 12)
Sakizaki et al., Industrial Water, VOL391, (1991), 29. Japanese Patent Laid-Open No. 11-235577 JP 2000-5740 A JP2002-20806 JP 2003-80220 A JP2003-136051A JP 2003-105313 A JP 2004-577881 A JP 2004-305235 A JP 2004-305792 A JP 2005-95750 A JP 2005-34696 A JP 2005-118755 A

  As an agent for detoxifying soil, industrial waste, sludge, sludge, drainage, groundwater, etc. contaminated with organic halogen compounds, iron-based decomposing agents containing different elements such as Ni and carbon are known. There has been a demand for an iron-based decomposition agent that can decompose and purify organic chlorine compounds at high speed. With conventional agents with increased activity by increasing the number of fine particles, when used for solids such as soil (solid-liquid mixed system), sufficient decomposition characteristics cannot be obtained, and there is a risk such as ignitability. It was.

  Furthermore, in the conventional Ni-containing iron powder for decomposition, it is necessary to increase the Ni content in order to increase the resolution. Accordingly, there has been a demand for iron powder for decomposition that has a high purification performance especially for soil-like solids and that has a low Ni content.

  As a result of intensive studies on the decomposition and purification of organochlorine compounds in the soil, the present inventors have found that coarse iron powder, in particular, a particle size of 53 μm (280 mesh under) is less than 40% by weight, and the Ni content is higher than before. We have found iron powder for decomposition that is excellent in degradability of organochlorine compounds, especially in soil treatment.

  The iron powder for decomposing organochlorine compounds of the present invention has a high resolution of hardly decomposable PCE, and exhibits a high resolution of organochlorine compounds even when used in combination with iron powder not containing Ni or iron oxide. It has been found that the amount can be reduced.

  Hereinafter, the present invention will be described in detail.

  The organochlorine compound decomposing iron powder of the present invention (hereinafter referred to as “decomposing iron powder”) is mainly composed of coarse particles having a particle size of less than 53 μm and less than 40% by weight. Conventional iron powder for decomposition has a large amount of active fine particles, and even a large amount of coarse particles is less than 53 μm and is about 50% by weight. Some iron powders exhibit high performance in solutions such as wastewater, but when used for solids such as soil, performance was not achieved.

  The particle size of the conventional iron powder for decomposition is 50% by weight or more when the particle size is less than 53 μm, which corresponds to the second class of hazardous materials, and there is a risk such as ignitability. The iron powder for decomposition of the present invention has a particle size of 53 μm or more and less than 40% by weight and less than the regulation value, and does not fall under the category of hazardous materials.

  The iron powder for decomposition of the present invention decomposes an organic chlorine compound at a high speed in the coarse particle distribution as described above, and the Ni amount is 0.1 to 0.5% by weight and the carbon amount is 0.005 to 5. % By weight. The iron powder for decomposition of organochlorine compounds is thought to contribute to the decomposition performance by local batteries formed by iron and dissimilar metals present on the surface of the iron. In terms of the effective surface area of the powder, it is considered that the performance is particularly excellent within the composition range of the present invention, and an excellent macro structure of a local battery can be formed.

  When the iron content for decomposition of the present invention alone is less than 0.1% by weight of Ni, the resolution is lowered, and when it exceeds 0.5% by weight, partial alloying becomes difficult and the local battery action is lowered. When the carbon content is less than 0.005% by weight, the resolution is low and it is difficult to obtain, and even if it exceeds 5% by weight, no improvement in decomposition performance is observed.

  In the iron powder for decomposition of the present invention, Ni and iron are preferably partially alloyed. A state where Ni is simply scattered on the iron powder (non-alloyed) is not preferable because the local battery action is weak. By partial alloying, the local battery action effect is increased and stability is exhibited. On the other hand, when completely alloyed, an effective local battery is not formed, and it is difficult to obtain the effects of the present invention. Also, partial alloying is effective from the viewpoint of separation of iron and Ni to suppress reduction in reduction action.

  As the existence site of the partial alloy of Fe and Ni, it is preferable that the alloy part does not occupy the entire surface of the iron particles, and that the Ni site and the alloying site exist on the surface of the iron powder. If the alloy covers the entire surface of the iron powder, the local battery action hardly occurs and the organic chlorinated product does not easily decompose. For partial alloying, the alloy layer (Ni diffusion layer) can be confirmed using EPMA (electron beam microanalyzer) or TEM (transmission electron microscope).

  The carbon of the iron powder for decomposition of the present invention desirably has a single carbon part and an alloy part of iron and carbon like Ni. In general, pure iron, steel, cast iron, pig iron, or the like can be used as the iron powder, but an iron portion existing in the iron powder and an iron-carbon alloy portion such as cementite can also act as active sites.

The powder shape of the iron powder for decomposition is not particularly limited, and includes a spherical shape, a dendritic shape, a piece shape, a needle shape, a square shape, a laminated shape, a rod shape, a plate shape, a sponge shape, and the like. Moreover, when the specific surface area of the iron powder for decomposition is 0.05 m ² / g or more, preferably 0.2 to 10 m ² / g, the decomposition reaction rate and the contact probability can be improved, which is effective in using coarse particles. Yes, difficult-to-decompose Cis-DCE, MC, and PCE can be decomposed in a shorter time.

  In the present invention, other additives may be included to such an extent that the effect is not impaired. The additive is not particularly limited, and examples thereof include an antioxidant, a reaction accelerator, a dispersant, a pH adjuster, and a deoxygenating agent. Sodium sulfite, ferrous sulfate, iron sulfide, ascorbic acid and the like as the antioxidant, sodium chloride and sodium sulfate as the reaction accelerator, activated carbon, alumina, zeolite, silica gel, silica-alumina, Examples include iron powder.

  In the present invention, iron powder for decomposition mixed with iron powder not containing Ni and / or iron oxide (hereinafter referred to as “mixed iron powder”) may be used. Even with such a mixed iron powder, the resolution of the organic chlorinated product is not reduced, and the total amount of Ni put into the soil can be further reduced.

  As a mixing ratio of the iron powder for decomposition in the mixed iron powder of the present invention and iron powder not containing Ni and / or iron oxide, the ratio of the iron powder for decomposition is preferably 30% by weight or more. If the iron powder for decomposition is less than 30% by weight, the resolution tends to decrease.

  The iron oxide used in the present invention is not particularly limited, and ferrous oxide, ferric oxide, magnetite, verdolite, and more specifically, iron iron and iron minerals that are generally easily available are used.

  If the amount of iron powder put into the soil is too small, uniform mixing and uniform contact with the soil becomes difficult, and the resolution of the organochlorine compound decreases. The resolution of the iron powder for decomposition of the present invention tends to decrease as the addition amount decreases. However, when the iron powder for decomposition of the present invention is used in the form of mixed iron powder, high decomposition performance is exhibited even though the amount of iron powder for decomposition added to the soil per unit weight is small.

  The reason why the mixed iron powder containing low-resolution iron powder and / or iron oxide containing the organic chlorine compound not containing Ni exhibits the same decomposition performance as in the case of the iron powder for decomposition is not clear, The surface of iron powder and / or iron oxide not containing Ni is decomposed with high resolution by forming a network in soil or aqueous solution by contacting iron powder and / or iron oxide not containing Ni with the iron powder for use. It is considered that the same battery action as that of iron powder is developed.

  The total Ni content of the mixed iron powder of the present invention is preferably 0.03% by weight to 0.5% by weight, more preferably 0.03% by weight to less than 0.1% by weight. .

  The particle size of the mixed iron powder of the present invention is not particularly limited, but for the same reason as the iron powder for decomposition, it is preferable that the total particle size is less than 53 μm and less than 40% by weight.

  The iron powder for decomposition or mixed iron powder of the present invention (hereinafter also referred to as “treatment agent”) has a higher resolution of organic chlorinated products in soil than conventional products, and trichloroethylene (TCE) is used at room temperature. When 1 wt% of the treatment agent is added to and mixed with soil of 10 ppm and moisture of 20 wt% or more, the decomposition rate constant of trichlorethylene up to the environmental standard (0.03 ppm) is 0.32 / day or more, especially 0.35 / day. It is preferable that it is not less than days, more preferably not less than 0.8 / day.

  It is well known that organic chlorinated substances are more easily decomposed when there is more water in the soil, but if the moisture in the soil is 10% by weight or more, especially 15% or more, the decomposition performance of the treatment agent is sufficient. Degradation rate is saturated. The degradation rate constants of the present invention are those obtained when 1% by weight of a treatment agent is added at room temperature in soil having a water content of 20% by weight or more where the degradation performance is sufficiently exhibited.

  The relationship of decomposition speed is generally expressed by the following speed equation.

ln (C ₁ / C ₀ ) = − k · t
C ₁ : Achievable concentration of trichloroethylene (ppm)
C ₀ : Initial concentration (ppm) of trichloroethylene
k: Rate constant (/ day or / hour)
t: Time (day or time)
In the decomposition of organic chlorides in soil, the degradation rate constant is 0.32 / day, 0.35 / day, 0.8 / day, for example, soil contaminated with 10 ppm trichlorethylene is the environmental standard (0.03 ppm) It takes 18 days, 17 days and 7 days, respectively, to clean up.

  The upper limit of the decomposition rate constant of the treatment agent of the present invention is not limited, but the decomposition rate constant is preferably 2 or less because it is dangerous if the activity is too high and decomposition gas is generated at once. A degradation rate constant of 2 corresponds to about 3 days as the number of days required for degradation to the environmental standard.

  The decomposition rate constant of the treatment agent of the present invention is excellent in the decomposition performance of organic chlorinated products in an aqueous solution. In particular, the decomposition rate constant of tetrachloroethylene up to the environmental standard (0.01 ppm) in the case of adding 1 wt% of a treatment agent at room temperature to an aqueous solution containing 10 ppm of hardly decomposable tetrachloroethylene (PCE) is 0.9. / Day or more, particularly 1.1 or more is preferable. For the reasons described above, the upper limit is still 2 / day or less.

  It is well known that degradation increases as the amount of treatment agent added to the soil is increased. Except when the amount of the treatment agent added to the soil is extremely small or too large, the range between the amount of addition and the decomposition rate constant is generally below in the range of 0.5 to 3% by weight usually used. The correlation according to the empirical formula is obtained. Therefore, it is also possible to compare the performance between the treatment agents evaluated under different conditions from the decomposition rate constant calculated from the test results of different addition amounts.

ka = kb (a / b) ^1/2
ka: Rate constant when a decomposing agent is added to a contaminant by a weight% kb: Rate constant when a decomposing agent is added by b weight% in the contaminant Next, a method for producing iron powder for decomposition will be described.

  In the present invention, the above-mentioned iron, Ni, and carbon are adjusted within the scope of the present invention, and these raw materials are mechanically pulverized to partially alloy Ni and carbon with iron mainly on the particle surface.

  As a pulverization method, a batch type or continuous type pulverizer of a vibration mill can be used, particularly among general ball mills, but those having high mechanical strength to the extent that raw materials are alloyed can be used. preferable.

  On the other hand, the pulverization needs to be performed under the condition that the partial alloying proceeds as long as the obtained iron powder for decomposition satisfies the particle size of the present invention. For example, for a 1 part by weight of a mixture of iron powder, Ni powder, and carbon powder, a grinding media such as a steel ball can be charged 2 to 10 times, and the frequency can be 600 to 2000 vpm.

  When both Ni and carbon are more than 0.1% by weight, the processing time is preferably less than 5 hours, whereas either Ni or carbon content is more than 0.1% by weight, especially 0.05% by weight. When the amount is small, the processing time is preferably 5 to 10 hours.

  Conventionally, it has been known that as the partial alloying of Ni becomes longer, the alloying proceeds too much (that is, the alloy is not a partial alloy), and the decomposition performance decreases. In the present invention, it has been found that the processing conditions for high performance are completely different depending on the amount of Ni and the amount of carbon. Conventionally, when the content of Ni or carbon is small, it has been thought that the processing time should be short so that alloying does not proceed too much, but especially when there is little Ni or carbon alloyed within the composition range of the present invention Has found that the activity is improved within the above-mentioned processing time.

  The mixed iron powder of the present invention can be produced by uniformly mixing the iron powder for decomposition obtained by the above-described method and iron powder / Ni containing no Ni.

  A mixing method is not particularly limited, and a V-type mixer, a screw-type mixer, a ball mill, a vibration mill, or the like can be used. If the mixing is not uniform, the performance of the mixed iron powder is not sufficiently exhibited. Therefore, it is preferable to uniformly mix the iron powder for decomposition and the iron powder / or iron oxide not containing Ni.

  Next, an organic halide detoxification method using the treating agent (decomposing iron powder or mixed iron powder) of the present invention will be described.

  As the detoxification treatment method of the present invention, 1) the treatment agent of the present invention is added to excavated soil, and a continuous and uniform mixing treatment is performed using a drum scrubber, a reforming mixer, a vibration mixer, a kneader, or the like. Method, refilling after batch mixing with vibration mixer, backhoe, etc. 2) In-situ treatment method in which vertical or horizontal well is dug in contaminated soil and treatment agent is injected with high-pressure air or high-pressure water, 3) Treatment In-situ treatment method in which slurry is added to the soil together with an agent and, if necessary, a dispersant, a reaction accelerator, a pH adjuster, etc. 4) A purification wall containing a treatment agent around contaminated groundwater is formed and purified. Method 5) There is a purification pit method in which a layer of treatment agent is provided in a portion lower than the contaminated groundwater position.

  The amount of treatment agent to be added varies depending on the contamination concentration of the object to be purified, but the treatment agent of the present invention is very highly active. It can be purified to below the environmental standard value corresponding to chlorinated substances. When using the treatment agent of the present invention, considering its decomposition activity and economy, it is 0.1 to 10% by weight with respect to an object to be treated such as wet soil or groundwater, and 1 to 1 in particular when considering homogeneous mixing. It is preferably 3% by weight.

  The treatment agent of the present invention exhibits high decomposition performance (decomposition rate) not only for solids such as soil but also for groundwater and wastewater containing organic chlorine compounds.

  The treatment agent (decomposition iron powder or mixed iron powder) of the present invention has a particle size of 53 μm (280 mesh under) less than 40% by weight and is not dangerous for ignition, and reacts with solids such as soil (solid-liquid mixture). In addition, the local battery is effectively formed with a low Ni content, and the decomposition rate of the organochlorine compound in the soil is faster than before, so that the contamination can be purified in a short period of time.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited by these.

Examples 1-5 and Comparative Examples 1-4
An evaluation test of a detoxifying agent in a contaminated soil containing an organic chlorine compound was conducted.

  In Examples 1-2, reduced iron powder (carbon content 0.05%) is used as raw iron powder for decomposition iron powder, in Examples 3-5, cast iron powder (carbon content 3-5%), and Comparative Examples 1, 3 4 used reduced iron powder (carbon content 0.8%), and Comparative Example 2 used pure iron powder (carbon content 0.01%). Carbonyl nickel (purity 99%, particle size 4-7 μm) was used as the raw material Ni powder.

  As pulverization conditions for the iron powder for decomposition, Examples 1 to 5 and Comparative Examples 1 to 4 were mixed with a predetermined amount of Fe powder and Ni powder containing a predetermined amount of carbon, and a vibration mill (manufactured by Chuo Kako Co., Ltd., (Trade name V-MILL, BM-3, 1200 vpm, 6.6 L pot) was used under the conditions of 6 times charge ratio and vibration frequency of 600 vpm with respect to 1 part by weight of the mixture. The nitrogen gas flow rate during processing was 40 ml / min. All processing times were 2 hours.

10 kg of TCE-contaminated soil (water content: 33% by weight), internal standard benzene dissolved in methanol, and 10 g of treatment agent (1% by weight of soil) were added, and mixed homogeneously for 1 minute with a vibration mixer. Processed. As reaction conditions, about 30 g of treated soil was sealed in a 125 ml vial, reacted at 20 ° C. in a stationary state, the gas layer was periodically analyzed by gas chromatography, and the change with time in the TCE concentration was investigated. The water used for adjusting the water content in the soil was not subjected to de-dissolved oxygen treatment and pH adjustment.

  Next, Table 1 shows the composition, particle size, and decomposition rate constant of the iron powder for decomposition used this time.

  From Examples 1 to 5, by adding 1% by weight of iron powder for decomposition into TCE-contaminated soil and mixing it, the TCE concentration was less than 0.03 ppm in the environmental standard in 6 to 11 days. Moreover, ethylene was the main component of the decomposition product, and no organic chlorine-based compound as an environmental standard item was produced.

  Comparative Example 1 did not contain Ni and did not fall below the environmental standard even after 4 months. Comparative Example 2 was an iron agent with a small amount of carbon in the iron powder and took 23 days for decomposition when the treatment time was 2 hours. The comparative agent 3 is an agent in which Ni is excessively contained, but the effect of resolution does not appear remarkably, and it took 21 days for purification. In Comparative Example 4, the amount of Ni and the amount of carbon are within the range of the iron powder for decomposition of the present invention, but the particle size is 280 mesh under (53 μm), 65%, which is a very fine iron powder. The decomposition days were 19 days, and it was considered that the mixing was not successful because the iron powder was fine.

  In the iron powder for decomposition | disassembly of Examples 1-5 of this invention, the capability to decompose | disassemble other VOCs including TCE in soil is remarkable, and a legal regulation value can be cleared in a short time.

  When 2% by weight of the iron powder for decomposition of Example 5 was added to the same soil under the same conditions, the environmental standard was reached in about 2.7 days.

Examples 6-10 and Comparative Examples 5-7
The evaluation of the iron powder for decomposition of the present invention was similarly performed on the PCE-containing contaminated aqueous solution.

  To a 125 ml vial, 100 ml of 10 ppm PCE aqueous solution, internal standard benzene dissolved in methanol, and 1 g of treating agent (1 wt% of aqueous solution) were added and sealed. The reaction conditions were 20 ° C. and 200 rpm shaking. This aqueous solution was not subjected to de-dissolved oxygen treatment and pH adjustment.

  As a PCE concentration analysis method, the headspace method based on JIS K 0125 (test method for volatile organic compounds in water and wastewater) is used, and the PCE concentration is quantitatively analyzed over time. The PCE concentration is less than the environmental standard value. The number of decomposition days was calculated. These results are shown in Table 2.

  In Examples 6 to 10, the PCE concentration is less than the environmental standard value of 0.01 ppm within 7 days, and the iron powder for decomposition according to the present invention containing the predetermined Ni amount and carbon amount is coarse, but has high resolution. Met.

  Further, in the examples of the present invention, the decomposition products were mainly composed of ethylene, and no organic chlorinated compounds as environmental standard items were generated.

  On the other hand, Comparative Example 5 is an iron powder not containing Ni, and it did not become less than 0.01 ppm of the environmental standard even after 3 months. In addition to ethylene, TCE and cis-DCE listed as environmental standard items were detected in addition to ethylene.

  Comparative Example 6 required 16 days for decomposition with a decomposition agent having a short processing time compared to an agent with less carbon (0.01%).

  In Comparative Example 7, Ni was excessive, and it took 15 days for decomposition, and the performance was not sufficient as compared with the iron powder for decomposition of the present invention.

  Therefore, if the iron powder for decomposition of Examples 6 to 10 is used, the ability to decompose organic chlorinated compounds including PCE, which has many cases in contaminated groundwater, is remarkable, and the legal regulation value must be cleared within a short period of time. Can do.

Example 11
Iron powder not containing Ni (described as cast iron powder: 3% carbon content) was mixed with the iron powder for decomposition in Example 5 (denoted as Example 5 iron powder in FIG. 1) for 0.5 hour using a V-type mixer ball mill. Then, mixed iron powders with different mixing ratios were synthesized.

  To a 125 ml vial, 100 ml of 10 ppm TCE aqueous solution, internal standard benzene dissolved in methanol, and 1 g of treating agent (1 wt% of aqueous solution) were added and sealed. The reaction conditions were 20 ° C. and 200 rpm shaking. This aqueous solution was not subjected to de-dissolved oxygen treatment and pH adjustment.

  As a method for analyzing the TCE concentration, a headspace method based on JIS K 0125 (Test method for volatile organic compounds in water and wastewater) is used, and the TCE concentration is quantitatively analyzed over time. The TCE concentration is less than the environmental standard value. The number of decomposition days was calculated. These results are shown in FIG.

  In the mixed iron powder having the iron powder for decomposition of 30% by weight or more, the decomposition performance comparable to that of the iron powder for decomposition of 100% was exhibited. The Ni content of the mixed iron powder in this case was 0.033% by weight.

Example 12
In the same manner as in Example 11, iron powder not containing Ni (described as cast iron powder: 3% carbon content) was added to the iron powder for decomposition in Example 5 (indicated as Example 5 iron powder in FIG. 1) with a V-type mixer ball mill. The mixed iron powder was mixed for 0.5 hour and the mixing ratio was changed.

  1kg of 10ppm TCE contaminated soil (water content 33% by weight), internal standard benzene dissolved in methanol, and 10g of treatment agent (1% by weight of soil) are put in, and it is mixed homogeneously for 1 minute with a vibratory mixer. Processed. As reaction conditions, about 30 g of treated soil was sealed in a 125 ml vial, reacted at 20 ° C. in a stationary state, the gas layer was periodically analyzed by gas chromatography, and the change with time in the TCE concentration was investigated. The water used for adjusting the water content in the soil was not subjected to de-dissolved oxygen treatment and pH adjustment. The results are shown in FIG.

  In the mixed iron powder having the iron powder for decomposition of 30% by weight or more, the decomposition performance similar to that of the iron powder for decomposition of 100% was exhibited even in the soil.

Examples 13 and 14
Decomposing iron powder was produced under the same conditions as in Example 1 except that the processing time was 6 hours, Ni 0.3%, and carbon 0.006% under the pulverization conditions of the decomposed iron powder. Table 3 shows the TCE decomposition behavior when 1 wt% is added in a soil containing 10 ppm of trichloroethylene and in an aqueous solution.

  Even when low carbon iron powder was used, a high decomposition rate was obtained.

Example 15
Iron oxide (sand iron) was blended with the partially alloyed iron powder containing 0.3% Ni and 3% carbon to decompose trichlorethylene (TCE) in the aqueous solution.

  Example 1 except that 1 g of a 1: 2 mixture treatment agent for iron powder for decomposition and iron oxide (1% by weight of the aqueous solution, equivalent to 0.33% by weight of the iron powder for decomposition alone) was added to a 10 ppm TCE aqueous solution. In the processing under the conditions (Example 15), the environmental standard was reached in 7 days.

Example 16
When 1 wt% (Example 16) of the same mixed treatment agent as Example 15 was added to 10 ppm TCE-contaminated soil (water content 20 wt%), the environmental standard was reached in 18 days.

  Decomposition per unit weight of iron powder for decomposition that has decomposition activity against TCE even though the amount of decomposed iron powder used is small by mixing with iron oxide, which itself has no resolution. Efficiency has also improved.

TCE decomposition performance in aqueous solution with mixed iron powder of iron powder for decomposition and iron powder not containing Ni. TCE decomposition performance in soil by mixed iron powder of iron powder for decomposition and iron powder not containing Ni.

Claims (13)

An iron powder for decomposing an organic chlorinated compound, comprising a particle size of less than 53 μm, less than 40% by weight, Ni content of 0.1 to 0.5% by weight, and carbon content of 0.005 to 5% by weight. The iron powder for decomposing organic chlorides according to claim 1, wherein Ni is partially alloyed with iron. An iron powder for decomposing an organic chlorinated product, comprising the iron powder for decomposing an organic chlorinated product according to claim 1 and an iron powder not containing Ni. An iron powder for decomposing an organic chlorinated product, comprising the iron powder for decomposing an organic chlorinated product according to claim 1 and iron oxide. The iron powder for organic chlorinated decomposition according to claim 3, comprising 30% by weight or more of the organic chlorinated decomposition iron powder according to claim 1. The iron powder for decomposing an organic chlorinated product according to claims 3 to 5, wherein the Ni content is 0.03% by weight or more and less than 0.5% by weight. The iron content for organic chlorinated decomposition according to claim 3, wherein the Ni content is 0.03% by weight or more and less than 0.1% by weight. The iron powder for decomposing organochlorides according to claims 3 to 7, wherein the particle size is less than 53 µm and less than 40 wt%. In soil containing 10 ppm trichlorethylene and 20% by weight or more of water, the decomposition rate constant until reaching the environmental standard (0.03 ppm) of trichlorethylene is 0.32 / day or more when added and mixed at room temperature and 1% by weight. The iron powder for organic chlorinated decomposition | disassembly of Claims 1-8. 10. A decomposition rate constant for reaching an environmental standard (0.01 ppm) of tetrachlorethylene in an aqueous solution containing 10 ppm of tetrachlorethylene at room temperature and 1 wt% is 0.9 / day or more. Iron powder for decomposing organic chlorides as described in 1. A mixture comprising 100 parts by weight of Fe, 0.1 to 0.5 parts by weight of Ni, and 0.005 to 5 parts by weight of carbon is pulverized to a particle size of less than 53 µm and less than 40% by weight. The manufacturing method of the iron powder for organic chlorinated decomposition | disassembly described in 2. A method for detoxifying an organic chlorinated product, comprising treating the object to be treated contaminated with the organic chlorinated product with the iron powder for decomposing the organic chlorinated product according to claim 1. The processing method according to claim 12, wherein the amount of the iron powder for decomposing the organic chlorinated product is 0.1 to 10% by weight based on the object to be processed.

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