JP4258622B2 - Purification agent for soil and groundwater contaminated with organic halogen compounds, its production method, and purification method for soil and groundwater contaminated with organic halogen compounds - Google Patents

Description

【０１３４】
浄化剤：実施例１〜５、参考例１〜２、比較例１〜２；
ゲータイト粒子の種類、加熱脱水、加熱還元の温度、分散の方法等を種々変化させた以外は前記発明の実施の形態と同様にして浄化剤を得た。
【０１３５】
このときの製造条件を表２〜３に、得られた浄化剤の諸特性を表４〜５に示す。
【０１３６】
比較例１は還元鉄粉、比較例２は電解鉄粉である。
【０１３７】
【表２】

【０１３８】
【表３】

【０１３９】
【表４】

【０１４０】
【表５】

【０１４１】
＜汚染土壌・汚染地下水の浄化処理＞
実施例６〜１０、参考例３〜４、比較例３〜４；
浄化剤の種類を種々変化させた以外は、前記発明の実施の形態と同様にして汚染土壌又は汚染地下水の処理を行った。
【０１４２】
このときの処理条件及び測定結果を表６に示す。
【０１４３】
【表６】

【０１４４】
＜有機ハロゲン化合物及び重金属等の有害物質で汚染された土壌の鉄複合粒子による浄化処理＞
あらかじめ湿った砂質土壌２０ｇ（目開き２ｍｍ篩い下）にトリクロロエチレン１．０μｌを添加し、トリクロロエチレンで汚染された土壌を作製した。褐色バイアル瓶５０ｍｌ（実容積６８ｍｌ）に実施の形態の浄化剤を鉄複合粒子として１ｇとなる量の浄化剤とイオン交換水２７ｍｌを注入し、次いで、前記汚染土壌を注入し、さらにカドミウム、鉛、砒素、セレン及びシアンを各１０ｐｐｍとなるように１０００ｐｐｍ標準液（関東化学（株）製）より各０．３ｍｌ注入し、六価クロムを５０ｐｐｍとなるように１０００ｐｐｍ標準液（関東化学（株）製）より１．５ｍｌ注入し、全量で１００ｐｐｍになるように合計３．０ｍｌ注入した。直ぐにフッ素樹脂ライナー付きゴム栓で蓋をし、その上からアルミシールで強固に締め付けた。前記バイアル瓶をペイントコンディショナー（レッドデビル社製）で３時間振とうした後、前記バイアル瓶のヘッドスペースのガスをシリンジで５０μｌ分取し、前記方法を用いてトリクロロエチレン残存量を測定した。その後更に１３時間振とう（合計１６時間）した後、０．４５μｍメンブランフィルターを使用して固液分離した。
【０１４５】
次いで、測定に必要な量の固形分（５０ｇ）及び濾液（３００ｍｌ）が得られるまで、同様の処理を行った。濾液はそのまま環境庁告示第１０号「地下水の水質汚濁に係る環境基準について」に基づき、固形分については４０℃で３時間、大気中で乾燥し試料を得て、環境庁告示第４６号「土壌の汚染に係る環境基準について」に基づき分析した。その結果、溶液中のカドミウム０．００１ｍｇ／ｌ未満、鉛０．００５ｍｇ／ｌ未満、六価クロム０．０４ｍｇ／ｌ未満、砒素０．００１ｍｇ／ｌ未満、セレン０．００２ｍｇ／ｌ未満、シアンは未検出であり、固体からの溶出量はカドミウム０．００１ｍｇ／ｌ未満、鉛０．００５ｍｇ／ｌ未満、六価クロム０．０４ｍｇ／ｌ未満、砒素０．００１ｍｇ／ｌ未満、セレン０．００２ｍｇ／ｌ未満、シアンは未検出であった。
【０１４６】
＜有機ハロゲン化合物の浄化処理結果＞
前記評価方法によれば、前記鉄複合粒子を用いた場合の土壌中のトリクロロエチレンの残存率は２．３％であった。
【０１４７】
＜有機ハロゲン化合物、重金属等の有害物質で汚染された地下水の鉄複合粒子による浄化処理＞
褐色バイアル瓶５０ｍｌ（実容積６８ｍｌ）に、実施の形態の浄化剤を鉄複合粒子として１ｇとなる量の浄化剤と２７．０ｍｌのイオン交換水、トリクロロエチレン１．０μｌを注入し、さらにカドミウム、鉛、砒素、セレン及びシアンを各１０ｐｐｍとなるように１０００ｐｐｍ標準液（関東化学（株）製）より各０．３ｍｌ注入し、六価クロムを５０ｐｐｍとなるように１０００ｐｐｍ標準液（関東化学（株）製）より１．５ｍｌ注入し、全量で１００ｐｐｍになるように合計３．０ｍｌ注入した。直ぐにフッ素樹脂ライナー付きゴム栓で蓋をし、その上からアルミシールで強固に締め付けた。前記バイアル瓶をペイントコンディショナー（レッドデビル社製）で３時間振とうした後、トリクロロエチレン残存量を前記バイアル瓶のヘッドスペースのガスをシリンジで５０μｌ分取し、前記方法を用いて測定した。その後、更に１３時間振とう（合計１６時間）した後、０．４５μｍメンブランフィルターを使用して固液分離した。
【０１４８】
次いで、測定に必要な量の固形分及び濾液が得られるまで、同様の処理を行った。濾液はそのまま環境庁告示第１０号「地下水の水質汚濁に係る環境基準について」に基づき、固形分については４０℃で３時間、大気中で乾燥し試料を得て、環境庁告示第４６号「土壌の汚染に係る環境基準について」に基づき分析した。その結果、溶液中のカドミウム０．００１ｍｇ／ｌ未満、鉛０．００５ｍｇ／ｌ未満、六価クロム０．０４ｍｇ／ｌ未満、砒素０．００１ｍｇ／ｌ未満、セレン０．００２ｍｇ／ｌ未満、シアンは未検出であり、固体からの溶出量はカドミウム０．００１ｍｇ／ｌ未満、鉛０．００５ｍｇ／ｌ未満、六価クロム０．０４ｍｇ／ｌ未満、砒素０．００１ｍｇ／ｌ未満、セレン０．００２ｍｇ／ｌ未満、シアンは未検出であった。
【０１４９】
＜有機ハロゲン化合物の浄化処理結果＞
前記評価方法によれば、前記鉄複合粒子を用いた場合の地下水中のトリクロロエチレンの残存率は２．４％であった。
【０１５０】
【発明の効果】
本発明に係る浄化剤は、有機ハロゲン化合物を効率よく分解できるので、有機ハロゲン化合物によって汚染された土壌・地下水の浄化剤として好適である。
【図面の簡単な説明】
【図１】 発明の実施の形態で得られた浄化剤に含有される鉄複合粒子の粒度分布を示すグラフである。
【図２】 発明の実施の形態で得られた浄化剤に含有される鉄複合粒子の走査型電子顕微鏡写真である（３０，０００倍）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,1,1-trichloroethane, 1,1,2, contained in soil or groundwater. -Aliphatic organic halogen compounds such as trichloroethane, trichlorethylene, tetrachloroethylene, 1,3-dichloropropene or dioxins, aromatic organic halogen compounds such as PCB, or the above organic halogen compounds and cadmium, lead, hexavalent chromium, arsenic, selenium, It is an object of the present invention to provide a cleaning agent capable of efficiently, continuously and economically decomposing pollutants made of heavy metals such as cyan.
[0002]
[Prior art]
Aliphatic organic halogen compounds such as trichlorethylene and tetrachloroethylene are widely used for cleaning in semiconductor factories and for degreasing metalworking metals.
[0003]
Dioxins, which are aromatic organic halogen compounds that are extremely toxic to the human body, even in trace amounts, are contained in exhaust gas, fly ash, and main ash generated from incinerators that incinerate municipal waste and industrial waste. It is included. Dioxins are a general term for compounds in which hydrogen is substituted with chlorine, such as dibenzo-p-dioxin and dibenzofuran. Exhaust gas and fly ash stay around the waste incinerator and dioxins remain in the surrounding soil.
[0004]
In addition, PCB (polychlorinated biphenyl) is chemically and thermally stable, has excellent electrical insulation properties, and has been frequently used as an insulating oil, plasticizer, and heat medium for transformers and capacitors, but is harmful. Therefore, production and use are prohibited. However, an effective processing method for PCBs used in the past has not been established, and most of them are stored without being processed.
[0005]
Since aliphatic organohalogen compounds and aromatic organohalogen compounds are difficult to decompose and are carcinogenic or highly toxic, contamination by soil and groundwater organohalogen compounds has become a serious environmental problem. .
[0006]
That is, when the organic halogen compound is discharged, the organic halogen compound is hardly decomposable, so it accumulates in the discharged soil and becomes contaminated with the organic halogen compound, and the groundwater is also contaminated with the organic halogen compound. Will be. Furthermore, since groundwater spreads also in surrounding areas other than contaminated soil, the contamination by organic halogen compounds becomes a problem in a wide area.
[0007]
Since soil cannot be reused or redeveloped in soil contaminated with organohalogen compounds, various technical means have been proposed as purification methods for soil and groundwater contaminated with organohalogen compounds. Since organic halogen compounds are hardly decomposable, and a large amount of soil and groundwater are to be treated, an efficient and economical purification technology has not yet been sufficiently established.
[0008]
As a purification method for soil contaminated with organohalogen compounds, a purification method using various catalysts, a suction removal method using the volatility of organohalogen compounds, and heat that is detoxified by excavating the soil and heat treatment Degradation methods, methods using microorganisms, and the like are known. Further, as a method for purifying groundwater contaminated with organic halogen compounds, a method for extracting contaminated groundwater from the soil to render it harmless, a method for removing organic halogen compounds by pumping groundwater, and the like are known.
[0009]
Of the technical means proposed as a purification method for soil and groundwater contaminated with organohalogen compounds, soil and groundwater contaminated with organohalogen compounds and decontamination using iron-based particles are mixed and made harmless. As technical means to do so, each technical means disclosed in Patent Documents 1 to 13 has been proposed.
[0010]
[Patent Document 1]
JP-A-10-71386
[Patent Document 2]
Japanese Patent Application Laid-Open No. 11-235577
[Patent Document 3]
Japanese Patent Laid-Open No. 11-253908
[Patent Document 4]
JP 2000-5740 A
[Patent Document 5]
JP 2000-225385 A
[Patent Document 6]
JP 2000-237768 A
[Patent Document 7]
JP 2000-334063 A
[Patent Document 8]
JP 2001-38341 A
[Patent Document 9]
JP 2001-113261 A
[Patent Document 10]
JP 2001-198567 A
[Patent Document 11]
JP 2002-161263 A
[Patent Document 12]
JP 2002-210452 A
[Patent Document 13]
JP 2002-317202 A
[0011]
[Problems to be solved by the invention]
However, in the aforementioned Patent Document 1, after boring holes are drilled in the contaminated soil, compressed air and iron powder are blown into the boring holes to form an iron powder dispersion layer containing iron powder and contact with groundwater. Although technology for detoxifying harmful substances in soil and groundwater is disclosed, detailed characteristics and amount of iron powder used are not described, and it can reduce organic halogen compounds sufficiently It's hard to say.
[0012]
In addition, Patent Document 2 discloses a technique for detoxifying organic halogen compounds in soil by adding and mixing iron powder containing 0.1% by weight or more of carbon to the soil. Although the specific surface area and particle size are described, since the particle size is large, it cannot be said that the organic halogen compound can be sufficiently reduced.
[0013]
In addition, Patent Document 3 described above describes a technique for making PCBs harmless by mixing powdered metal with PCB and heating the kneaded material in a uniform mixed state to form metal chlorides. In the examples, heating at 250 ° C. or higher is necessary, which is not economical.
[0014]
In addition, Patent Document 4 discloses a technique for detoxifying organohalogen compounds in soil using iron powder containing copper. However, since it takes a long time to decompose the organohalogen compounds, it is efficient. It is difficult to say that organic halogen compounds can be rendered harmless.
[0015]
Patent Document 5 described above describes a technique for reductively dehalogenating a halogenated hydrocarbon by a chemical reaction with a reducing metal in the presence of a hydrogen-donating compound, but promotes the dehalogenation reaction. The amine to be produced is essential, and it is difficult to say that the decomposition reaction with the reducing metal is sufficient.
[0016]
In addition, Patent Document 6 discloses a technique for bringing an organic halogen compound and an iron-based metal into contact with each other. However, it is a fibrous iron-based metal having a large fiber diameter, and sufficient aromatic organic halogen compounds are used. It is hard to say that it can be reduced.
[0017]
Patent Document 7 discloses a technique for detoxifying dioxins by bringing dioxins into contact with an acidic aqueous hydrochloric acid solution containing mill scale generated from a hot-rolled steel sheet manufacturing process at a steel mill at a temperature lower than 100 ° C. However, an aqueous hydrochloric acid solution that promotes detoxification is essential, and it is difficult to say that the decomposition reaction of the mill scale itself is sufficient.
[0018]
Moreover, although the above-mentioned patent document 8 discloses a soil purifier composed of an aqueous suspension containing iron particles having an average particle diameter of 1 to 500 μm, the particle size is large and the organic halogen compound is sufficiently decomposed. It becomes difficult.
[0019]
In addition, Patent Document 9 discloses a method for detoxifying dioxins by contacting dioxin-contaminated soil with an acidic aqueous hydrochloric acid solution containing an iron compound. However, an acidic aqueous hydrochloric acid solution that promotes detoxification is essential. It is difficult to say that the decomposition reaction of the iron compound itself is sufficient.
[0020]
In addition, the above-mentioned Patent Document 10 discloses a technique using an aqueous suspension containing spherical iron particles having an average particle diameter of less than 10 μm. The aqueous suspension containing spherical iron particles is used for steelmaking. This is a water suspension obtained by collecting and removing the exhaust gas generated during refining from an oxygen blown furnace, and has a wide particle size distribution of iron particles and a non-uniform rate of penetration into contaminated soil. Therefore, it is difficult to say that the organic halogen compounds can be sufficiently reduced.
[0021]
In addition, the aforementioned Patent Document 11 describes an iron powder for decomposing an organic halogen compound in which a metal selected from nickel, copper, cobalt and molybdenum adheres to the surface and the surface other than the adhered metal is covered with an iron oxide film. However, it uses iron powder obtained by mill scale and iron atomized from molten steel, and it is estimated that the specific surface area of iron powder is low and the particle size is large, and organic halogen compounds are sufficiently reduced. It's hard to say that you can.
[0022]
In addition, in the above-mentioned Patent Document 12, it is described that iron powder containing S is used for purification treatment of soil / groundwater contaminated with an organic halogen compound, but the particle size is large and the organic halogen compound is sufficient. It is hard to say that it can be reduced.
[0023]
In addition, in the aforementioned Patent Document 13, it is described that the iron composite particle powder containing magnetite is used for purification treatment of soil / groundwater contaminated with an organic halogen compound, but does not contain S, It is difficult to say that organic halogen compounds can be sufficiently reduced.
[0024]
Therefore, the present invention provides an efficient, sustainable, and economical method for harmful substances composed of organic halogen compounds or organic halogen compounds and heavy metals such as cadmium, lead, hexavalent chromium, arsenic, selenium, and cyanide contained in soil and groundwater. It is a technical problem to provide a purification method using a purification agent that can be treated in an effective manner.
[0025]
[Means for Solving the Problems]
The technical problem can be achieved by the present invention as follows.
[0026]
That is, the present inventionα-Fe and Fe ₃ O ₄ Consisting ofAn aqueous suspension containing iron composite particles as an active ingredient, wherein the particle shape of the primary particles of the iron composite particles is rice-grained, the average major axis diameter is 0.05 to 0.50 μm, and the axial ratio Is more than 1.0 and not more than 2.0, the α-Fe content is 30 to 99% by weight, the particle size distribution of the secondary particles of the iron composite particles is a single peak, and the median diameter (D₅₀: The particle diameter at which the cumulative ratio with respect to the particle diameter is 50% when the total volume of the iron composite particles is 100% is 0.5 to 5.0 μm, and D₉₀/ D₁₀A purification agent for soil and groundwater contaminated with an organic halogen compound, wherein the ratio is 1.0 to 5.0 (Invention 1).
[0027]
The present invention also provides α-Fe and Fe₃O₄An aqueous suspension containing iron composite particles consisting of: as an active ingredient, wherein the primary particles of the iron composite particles have a rice grain shape and an average major axis diameter of 0.05 to 0.50 μm. The axial ratio exceeds 1.0 and is 2.0 or less, and the diffraction intensity D of the (110) plane of α-Fe in the X-ray diffraction spectrum of the iron composite particle powder₁₁₀And magnetite (311) plane diffraction intensity D₃₁₁Intensity ratio (D₁₁₀/ (D₁₁₀+ D₃₁₁)) Is 0.20 to 0.98, the particle size distribution of the secondary particles of the iron composite particles is a single peak, and the median diameter (D₅₀: The particle diameter at which the cumulative ratio with respect to the particle diameter is 50% when the total volume of the iron composite particles is 100% is 0.5 to 5.0 μm, and D₉₀/ D₁₀A purification agent for soil and groundwater contaminated with an organic halogen compound, wherein the ratio is 1.0 to 5.0 (Invention 2).
[0028]
Moreover, the present invention has a specific gravity of 1.2 to 1.4 and a concentration of 20 to 40% by weight, soil and groundwater contaminated with the organic halogen compound of the present invention 1 or 2 (Invention 3).
[0029]
In the present invention, the iron composite particles contained in the soil / groundwater purification agent contaminated with the organic halogen compound have a saturation magnetization value of 90 to 190 Am.²/ Kg with a BET specific surface area of 5 to 60 m²Soil / groundwater contaminated with the organic halogen compound according to any one of the present invention 1 to 3, wherein the crystallite size of the (110) plane of α-Fe is 200 to 500 mm It is a purification agent (Invention 4).
[0030]
The present invention also relates to a goethite particle powder having an average major axis diameter of 0.05 to 0.50 μm or a hematite particle powder obtained by heating and dehydrating the goethite particle powder in a temperature range of 250 to 350 ° C. in a temperature range of 350 to 600 ° C. After heating and reducing to iron particle powder, after cooling, the iron particle powder is taken out in water without forming a surface oxide film in the gas phase, and a surface oxide film is formed on the particle surface of the iron particle powder in water. To obtain a water suspension containing iron composite particles, and then wet pulverizing with a disperser or a stirrer, soil / groundwater contaminated with any of the organic halogen compounds of the present invention 1 to 4 It is a manufacturing method of this purification agent (this invention 5).
[0031]
Further, the present invention provides a soil / groundwater purification agent contaminated with the organic halogen compound according to any one of the first to fourth aspects of the present invention and soil contaminated with the organic halogen compound or groundwater contaminated with the organic halogen compound. A method for purifying soil / groundwater contaminated with an organic halogen compound, characterized by mixing contact (present invention 6).
[0032]
Further, the present invention relates to soil or organic halogen compounds contaminated with contaminants comprising soil and groundwater purifiers, organic halogen compounds and heavy metals contaminated with the organic halogen compounds of any one of the present inventions 1 to 4. A method for purifying soil / groundwater contaminated with an organic halogen compound, wherein the groundwater contaminated with a contaminant made of heavy metal is mixed and contacted (Invention 7).
[0033]
The configuration of the present invention will be described in detail as follows.
[0034]
First, the soil / groundwater purification agent (hereinafter referred to as “purification agent”) contaminated with the organic halogen compounds according to the present invention 1 to 4 will be described.
[0035]
The particle shape of the primary particles of the iron composite particles in the present invention is rice. In the present invention, the spindle-shaped or needle-shaped goethite particle powder or hematite particle is subjected to heat reduction treatment as it is, and therefore when undergoing crystal transformation to the α-Fe phase, the particle shape collapses and undergoes an isotropic growth process. It becomes. On the other hand, if the particle size is the same in the spherical shape, the BET specific surface area is decreased and the catalytic activity is decreased.
[0036]
The average major axis diameter of the iron composite particle powder for purification treatment according to the present invention is preferably 0.05 to 0.50 μm. When the average major axis diameter is less than 0.05 μm, since the α-Fe phase is unstable, a thick oxide film is formed on the surface, making it difficult to increase the α-Fe content. It is difficult to obtain the effect. If it exceeds 0.50 μm, the α-Fe content can be increased, but the BET specific surface area becomes small, making it difficult to obtain the intended effect of the present invention. More preferably, it is 0.05-0.30 micrometer.
[0037]
The axial ratio of primary particles of the iron composite particle powder in the present invention is more than 1.0 and 2.0 or less. When the axial ratio is 1.0, spherical particles and the same particle size are not preferable because the BET specific surface area is small and the catalytic activity is low. If it exceeds 2.0, the BET specific surface area becomes large, the α-Fe phase becomes unstable, and a thick oxide film tends to be formed on the surface, making it difficult to increase the α-Fe content. It is difficult to obtain the effect. Preferably it is 1.2-1.8.
[0038]
When the particle size distribution of the iron composite particles constituting the purifier according to the present invention is measured with a laser diffractometer, the particle size distribution of secondary particles of the iron composite particles has a single peak. When it has a plurality of peaks, the permeation rate into the contaminated soil is not uniform, and it takes a long time for purification, and the intended effect of the present invention cannot be obtained.
[0039]
The median diameter (D) of secondary particles of iron composite particles constituting the purifier according to the present invention₅₀: The particle diameter at which the cumulative ratio with respect to the particle diameter is 50% when the total volume of the iron composite particles is 100% is 0.5 to 5.0 μm. Secondary particle median diameter (D₅₀) Is better, but the primary particles are fine particles and contain α-Fe. Therefore, magnetic agglomeration is likely to occur, and it is industrially difficult to make it less than 0.5 μm. When it exceeds 5.0 μm, the penetration into the contaminated soil is delayed and it is difficult to purify in a short time, and the intended effect of the present invention cannot be obtained. Preferably it is 0.5-3.5 micrometers.
[0040]
D of secondary particles of iron composite particles in the cleaning agent according to the present invention₉₀(Particle diameter at which the cumulative ratio with respect to the particle diameter is 90% when the total volume of the iron composite particles is 100%) and D₁₀Ratio D with (particle diameter at which the cumulative ratio with respect to the particle diameter is 10% when the total volume of the iron composite particles is 100%)₉₀/ D₁₀Is 1.0-5.0. The smaller the distribution width, the more uniform the permeation rate into the contaminated soil and the uniform purification rate, but 1.0 is the limit industrially. If it exceeds 5.0, the rate of penetration into the contaminated soil will be uneven and the purification performance will be delayed, and it will take a long time for the purification, so the intended effect of the present invention cannot be obtained.
Preferably it is 1.0-3.5.
[0041]
Distribution width (D of secondary particles of iron composite particles in the purifier according to the present invention (D₈₄-D₁₆) (D₈₄: The particle diameter at which the cumulative ratio when the total volume of iron composite particles is 100% and the cumulative ratio with respect to the particle diameter is found is 84%, D₁₆: The particle diameter at which the cumulative ratio with respect to the particle diameter is 16% when the total volume of the iron composite particles is 100% is preferably 0.5 to 5.0 μm. The smaller the distribution width, the more uniform the permeation rate into the contaminated soil and the uniform purification rate, but 0.5 is the limit for industrial use. If it exceeds 5.0, the rate of penetration into the contaminated soil will be uneven and the purification performance will be delayed, and it will take a long time for the purification, so the intended effect of the present invention cannot be obtained. Preferably it is 0.5-3.5 micrometers.
[0042]
The iron composite particles in the present invention have an α-Fe content of 30 to 99% by weight. When the α-Fe content is less than 30% by weight, the purification performance of the organic halogen compound is not sufficient, and the intended effect of the present invention cannot be obtained. When the α-Fe content exceeds 99% by weight, the particle size is extremely large or the BET specific surface area is extremely small and stable in the air. It will be extremely inferior. Preferably it is 40 to 99% by weight.
[0043]
The constituent phases of the iron composite particles are Fe-phase and Fe-phase.₃O₄Preferably it contains a phase. Fe₃O₄It becomes possible to maintain catalyst activity for a long time by containing. α-Fe and Fe₃O₄Is the diffraction intensity D of the (110) plane of α-Fe in the X-ray diffraction spectrum of the iron composite particle powder.₁₁₀And Fe₃O₄Diffraction intensity D of (311) plane of₃₁₁Intensity ratio (D₁₁₀/ (D₃₁₁+ D₁₁₀)) Is preferably 0.20 to 0.98, more preferably 0.30 to 0.98. Fe₃O₄Is preferably present on the particle surface of the iron composite particle powder.
[0044]
The crystallite size (α-Fe (110) plane) of the iron composite particles in the present invention is preferably 200 to 400 mm. If it is less than 200%, the BET specific surface area is large but the α-Fe phase is unstable, so that a thick oxide film is formed on the surface, making it difficult to increase the α-Fe content. It becomes difficult to obtain an effect. If it exceeds 400%, the α-Fe content can be increased, but the BET specific surface area becomes small, making it difficult to obtain the intended effect of the present invention. More preferably, it is 200-350cm.
[0045]
The BET specific surface area value of the iron composite particle powder in the present invention is 5 to 60 m.²/ G is preferred. 5m²When it is less than / g, the contact area becomes small and the catalytic activity is hardly exhibited. 60m²When the amount exceeds / g, since the α-Fe phase is unstable, a thick oxide film is formed on the surface, making it difficult to increase the α-Fe content, and obtaining the intended effect of the present invention. It becomes difficult. More preferably 7-55m²/ G.
[0046]
The saturation magnetization value of the iron composite particle powder in the present invention is 90 to 190 Am.²/ Kg (90-190 emu / g) is preferred. 90 Am²If it is less than / kg, the α-Fe content is low and the catalytic activity is lowered, which is not preferable. 190Am²When the amount exceeds / kg, although the α-Fe content is high, the BET specific surface area tends to be low and the catalytic activity is lowered. More preferably 95-190 Am²/ Kg (95-190 emu / g).
[0047]
The iron composite particle powder in the present invention preferably contains a trace amount of S, and the S content is preferably 500 to 10,000 ppm, more preferably 1000 to 5000 ppm.
[0048]
The iron composite particle powder in the present invention does not contain as much as possible since metal elements other than Fe such as Pb, Cd, As, Hg, Sn, Sb, Ba, Zn, Cr, Nb, Co, and Bi are toxic metals. In particular, it is preferable that Pb, Cd, As, and Hg are not substantially contained.
[0049]
The specific gravity of the purifier according to the present invention is preferably 1.2 to 1.4. If less than 1.2, considering the transport amount of the cleaning agent and the amount added to the soil, etc., the solid content is low and not economical, and if it exceeds 1.4, the purification is performed considering the primary particle size and the secondary particle size of the present invention. The agent thickens and is difficult to manufacture industrially.
[0050]
The concentration of the iron composite particles in the cleaning agent according to the present invention is preferably 20 to 40% by weight. If it is less than 20% by weight, it is not economical because the solid content is small and the amount of addition to the soil or the like is considered, and if it exceeds 40% by weight, it is purified considering the primary particle size and the secondary particle size of the present invention. The agent thickens and is difficult to manufacture industrially.
[0051]
Next, the manufacturing method of the purifier which concerns on this invention 5 is described.
[0052]
The goethite particle powder is obtained by reacting ferrous salt with one or more selected from alkali hydroxide, alkali carbonate or ammonia according to a conventional method, such as iron hydroxide or iron carbonate. This can be obtained by ventilating an oxygen-containing gas such as air into a suspension containing the ferrous iron-containing precipitate.
[0053]
The average major axis diameter of the goethite particle powder is 0.05 to 0.50 μm, the particle shape is preferably spindle or needle shape, the axial ratio is preferably 4 to 30, more preferably 5 to 25, and the BET ratio. Surface area is 20-200m²/ G is preferable, more preferably 25 to 180 m.²/ G.
[0054]
Also, in order to maintain the α-Fe content in the iron composite particles at a high rate and destroy the shape and grow the crystals in a granular form, the goethite particle powder may not be subjected to surface treatment such as sintering prevention treatment. preferable.
[0055]
The goethite particle powder is preferably granulated according to a conventional method. By granulating, a fixed bed type reduction furnace can be used.
[0056]
The obtained goethite particle powder is preferably a hematite particle powder that has been heat-dehydrated in a temperature range of 250 to 350 ° C.
[0057]
The average major axis diameter of the hematite particle powder is 0.05 to 0.50 μm, and the particle shape may be either a spindle shape or a needle shape.
[0058]
The goethite particle powder or the hematite particle powder is heated and reduced in a temperature range of 350 to 600 ° C. to obtain iron particle (α-Fe) powder.
[0059]
When the heating reduction temperature is less than 350 ° C., the reduction reaction proceeds slowly and takes a long time for the reduction reaction. Further, although the BET specific surface area can be increased, the crystal growth cannot be sufficiently performed, the α-Fe phase becomes unstable, and a thick oxide film is formed on the particle surface, so that the α-Fe content is increased. Can not do it. When the temperature exceeds 600 ° C., the reduction reaction proceeds rapidly, the sintering between the particles and the particles is excessively promoted, the particle diameter is increased, and the BET specific surface area is also decreased.
[0060]
In addition, although hydrogen gas, nitrogen gas, etc. can utilize the atmosphere at the time of temperature increase of a reductive reaction, hydrogen gas is preferable industrially.
[0061]
After the heat-reduced iron particle powder is cooled, the iron particle powder is taken out in water without forming a surface oxide film in the gas phase, and a surface oxide film is formed on the particle surface of the iron particle powder in water.
[0062]
The atmosphere during cooling may be either nitrogen or hydrogen, but is preferably switched to nitrogen finally. Moreover, when taking out in water, it is preferable to be cooled to 100 degrees C or less.
[0063]
By the heat reduction treatment, the entire particles become iron particles composed of an α-Fe phase, and when taken out into water, the water is decomposed by the catalytic activity of α-Fe and separated into hydrogen and oxygen. Is oxidized and Fe on the particle surface₃O₄It is estimated that an oxide film consisting of
[0064]
The iron particle powder after heat reduction is cooled and then taken out into water. After forming a surface oxide film on the particle surface of the iron particle powder in water, the iron composite particles are wet-pulverized.
[0065]
In consideration of the agglomeration state, properties (high activity), size, ability of the pulverizer (product particle size, pulverization amount) and final form of the iron composite particles, the pulverization is preferably wet pulverization.
[0066]
As a pulverizer used in the present invention, when a medium is used, a container driven type such as a rolling mill (pot mill, tube mill, conical mill) or vibration mill (fine vibration mill), tower type (tower mill), stirring tank type ( Medium stirring types such as an attritor), a distribution pipe type (sand grind mill), and an annular type (annular mill) can be used. When the medium is not used, a shear / friction type such as a container rotation type (Ang mill) or a wet high-speed rotation type (colloid mill, homomixer, line mixer) can be used.
[0067]
In general, the pulverization is performed by roughly pulverizing a raw material of 25 mm or less into powder and roughly divided into coarse pulverization, fine pulverization, and fine pulverization processes. It is generally said that coarse pulverization is pulverization from 5 mm to 20 mesh, fine pulverization is such that particles of 200 mesh or less are about 90%, and fine pulverization is such that particles of 325 mesh or less are about 90%. There are also ultra-fine pulverizers that can pulverize to a few microns. In the present invention, the iron composite particles are preferably subjected to three pulverization states of coarse pulverization, fine pulverization, and fine pulverization.
[0068]
For coarse pulverization, a low-speed rotation type, medium-speed rotation type, high-speed rotation shear type, high-low-speed rotation combination stirrer, etc., which is inserted into a stirring tank equipped with a baffle and stirred can be used. Considering the collection, a medium to high-speed rotating stirrer at 1000 to 6000 rpm is preferable. The blade shape of the stirrer includes a disk turbine, a fan turbine, an arrow blade turbine, a propeller type, and the like, but a disk turbine with an edge is preferable, for example, a homodisper manufactured by Tokushu Kika Kogyo.
[0069]
A batch type apparatus or a continuous type apparatus can be used for fine pulverization or fine pulverization, but a continuous type is preferred industrially. When using media, a ball mill, tower mill, sand grind mill, attritor or the like can be used, and when no media is used, a homomixer, a line mixer or the like can be used.
[0070]
For fine pulverization, it is possible to use a multi-stage combination of a rotor and a stator in which a plurality of slits are provided on the outer periphery and the shaft fixing surface portion is provided with cutter teeth, and the peripheral speed of the rotor is 30 m / s. A continuous shearing disperser such as the above-mentioned medialess line mixer, for example, a homomic line mill manufactured by Tokushu Kika Kogyo is particularly preferable.
[0071]
Fine pulverization (finish pulverization) is performed by inserting a medium of φ1 to φ3 into a cylindrical vessel at a filling rate of 70 to 80%, and rotating by attaching a plurality of discs to a rotating shaft installed in the center of the vessel. Thus, a media-type disperser such as a sand grind mill in which a rapid swirling action occurs in the media and the processed material passes from the bottom to the top of the media can be used. For example, a sand grinder manufactured by IMEX is particularly preferable.
[0072]
In the wet pulverization of the present invention, the crack growth of particles is prevented and recombination is suppressed, or the particles are aggregated to become granular and difficult to be pulverized, or the pulverization force is weakened by adhering to a ball or a mill. In order to suppress, a grinding aid may be added as appropriate. Grinding aids include solids and liquids. Examples of solids include stearates, colloidal silica, colloidal carbon, etc., and liquids include triethanolamine and alkyl sulfonate.
[0073]
The concentration of the suspension during wet pulverization is preferably 20 to 40% by weight of iron composite particles. When the amount is less than 20% by weight, stress such as shearing is hardly applied during pulverization, and a predetermined pulverized particle size cannot be obtained or it takes a long time, and the media necessary for pulverization is significantly worn. If it exceeds 40% by weight, the aqueous suspension will thicken, and the mechanical load is large, making it difficult to produce industrially.
[0074]
Next, a method for purifying soil and groundwater contaminated with an organic halogen compound according to the sixth aspect of the present invention will be described.
[0075]
In general, purification of soil and groundwater contaminated with organic halogen compounds is generally performed by in-situ decomposition methods that decompose the contained pollutants directly in the ground, and raw materials that decompose excavated or extracted soil and groundwater. There is a position extraction method, and any method can be used in the present invention.
[0076]
In the in-situ decomposition method, a method is adopted in which the purifying agent is introduced into the basement through infiltration or a borehole as it is using high pressure air, a gas such as nitrogen or water as a medium. In particular, since the purification agent of the present invention is an aqueous suspension, it can be used as it is or diluted as necessary.
[0077]
In the in-situ extraction method, the excavated soil and the cleaning agent may be mixed and stirred using a sand mill, a Henschel mixer, a concrete mixer, a nauter mixer, a uniaxial or biaxial kneader mixer, or the like.
[0078]
The amount of the purification agent can be selected as appropriate according to the degree of contamination of the organic halogen compounds in the soil and groundwater, but when contaminated soil is the target, it is usually converted to solid content with respect to 100 parts by weight of the soil. Is preferably 0.1 to 30 parts by weight, and more preferably 0.2 to 20 parts by weight. When the amount is less than 0.1 parts by weight, the intended effect of the present invention cannot be obtained sufficiently. If it exceeds 30 parts by weight, the purification effect is improved, but it is not economical. When contaminated groundwater is targeted, it is preferably added in an amount of 0.1 to 30 parts by weight, more preferably 0.2 to 20 parts by weight in terms of solid content with respect to 100 parts by weight of groundwater. Moreover, you may dilute and use the purification | cleaning agent which concerns on this invention so that it may become the said addition amount.
[0079]
When the purification agent of the present invention is used, in the evaluation method described later, the residual ratio of the aliphatic organic halogen compound in the contaminated soil can be 8% or less, preferably 0.1 to 5.0%. The residual rate of the aliphatic organic halogen compound in the contaminated groundwater can be 8% or less, preferably 0.1 to 5.0%. Further, the residual rate of aromatic organic halogen compounds in the contaminated soil can be 30% or less, preferably 25% or less, and the residual rate of aromatic organic halogen compounds in the contaminated groundwater is 30% or less, preferably 25 % Or less.
[0080]
Next, a method for purifying soil and groundwater containing contaminants composed of organic halogen compounds and heavy metals according to the seventh aspect of the present invention will be described.
[0081]
In the present invention, contaminants made of heavy metals such as cadmium, lead, hexavalent chromium, arsenic, selenium, and cyan can be insolubilized simultaneously with the organic halogen compound.
[0082]
The amount of the purification agent (in terms of solid content) is the same as described above.
[0083]
DETAILED DESCRIPTION OF THE INVENTION
A typical embodiment of the present invention is as follows.
[0084]
The average major axis diameter and axial ratio of the goethite particle powder and the hematite particle powder were measured with a transmission electron micrograph. The average major axis diameter and axial ratio of the iron composite particle powder were measured using a scanning electron micrograph.
[0085]
The particle size distribution of the iron composite particle powder was measured using a laser scattering / diffraction method “NIKISO MICROTRAC HRA MODEL 9320-X100” (manufactured by Nikkiso Co., Ltd.). The dispersion solvent was ethanol, the dispersant was organosilane, and the dispersion was performed for 1 minute with an ultrasonic disperser.
[0086]
The S content of each particle powder was measured using “Carbon Sulfur Analyzer: EMIA-2200” (manufactured by HORIBA).
[0087]
The crystalline phase of each particle powder was identified by measuring in the range of 10 to 90 ° with the X-ray diffractometer.
[0088]
The α-Fe content of the iron composite particle powder was measured in advance by measuring the X-ray diffraction of a mixed powder composed of iron and magnetite in various mixing ratios (α-Fe was taken out into water and transformed). 110) Diffraction intensity D of the surface₁₁₀Diffraction intensity D of (311) plane of magnetite₃₁₁It was calculated by creating a relational expression between the mixing ratio and the mixing ratio and using it as a calibration curve. The relational expression which is a calibration curve is as follows.
[0089]
α-Fe content = −51.387X²+ 151.88X
X: Strength ratio (D₁₁₀/ (D₁₁₀+ D₃₁₁))
[0090]
The crystallite size of the (110) plane of α-Fe of the iron composite particle powder is the crystal grain size measured by the X-ray diffraction method, and the thickness of the crystal grain in the direction perpendicular to the crystal plane of each grain. This is a value calculated from the diffraction peak curve for each crystal plane using the following Scherrer equation.
[0091]
Crystallite size = Kλ / βcosθ
Where β = half-value width (in radians) of the true diffraction peak corrected for machine width due to the device.
K = Scherrer constant (= 0.9).
λ = wavelength of X-ray (Cu Kα ray 0.1542 nm).
θ = Diffraction angle (corresponding to the diffraction peak of each crystal plane).
[0092]
Of the metal elements other than iron present in each particle powder, “Frame atomic absorption photometer AA-6500S” (manufactured by Shimadzu Corporation) is used for Pb and Cd, and “Hydrogen compound generation atomic absorption photometer HVG-” is used for As. 1 ”(manufactured by Shimadzu Corporation) was measured for Hg using“ reduction vaporization atomic absorption photometer MVU-1A ”(manufactured by Shimadzu Corporation).
[0093]
The specific surface area of each particle powder was represented by a value measured by BET method using “Monosorb MS-11” (manufactured by Kantachrome Co., Ltd.).
[0094]
The saturation magnetization value of the iron composite particle powder was measured using an “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Industry Co., Ltd.) with an external magnetic field of 795.8 kA / m (10 kOe).
[0095]
<Preparation of calibration curve for soil: Determination of aliphatic organic halogen compounds>
The concentration of the organic halogen compound was prepared in advance according to the following procedure, and the concentration was calculated based on the obtained calibration curve.
Trichlorethylene (TCE: C₂HCl₃): Molecular weight 131.39
Reagent grade (99.5%), density (20 ° C.) 1.461 to 1.469 g / ml
[0096]
Trichlorethylene was made into three levels of 0.05 μl, 0.1 μl and 1.0 μl, 30 ml of ion-exchanged water was added to 50 ml of brown vial (actual volume 68 ml), and 20 g of sandy soil (under 2 mm mesh sieve) was sealed. Next, each level of trichlorethylene is injected, immediately covered with a rubber stopper with a fluororesin liner, and firmly tightened with an aluminum seal from above. 50 μl of the gas in the headspace of the vial is taken with a syringe, and trichlorethylene is measured using “GC-MS-QP5050” (manufactured by Shimadzu Corporation). Assuming that trichlorethylene is not decomposed at all, the relationship between the amount added and the peak area is determined. The column at this time is a capillary column (DB-1: manufactured by J & W Scientific, liquid phase: dimethylpolysiloxane), He gas (143 l / min) is used as a carrier gas, and the temperature is maintained at 40 ° C. for 2 minutes. The gas is analyzed by raising the temperature to 250 ° C at a rate of ° C / min.
[0097]
<Sample preparation for measuring aliphatic organic halogen compounds>
1.0 g of trichlorethylene was added to 20 g of pre-moist sandy soil (under 2 mm mesh sieve) to prepare soil contaminated with trichlorethylene. Into a 50 ml brown vial (actual volume 68 ml), an amount of 1 g of the cleaning agent as iron composite particle powder and an amount of ion-exchanged water of 30.0 ml together with the water content in the cleaning agent are injected, Next, the contaminated soil is poured, immediately covered with a rubber stopper with a fluororesin liner, and firmly tightened with an aluminum seal from above. The vial is shaken with a paint conditioner (Red Devil) for 3 hours.
[0098]
<Evaluation method of aliphatic organic halogen compound>
The residual amount of trichlorethylene is measured using the above-mentioned “GC-MS-QP5050” (manufactured by Shimadzu Corporation) by taking 50 μl of the headspace gas of the vial bottle with a syringe.
[0099]
<Preparation of calibration curve for groundwater: Determination of aliphatic organic halogen compounds>
A groundwater calibration curve was prepared in the same manner as in <Preparation of soil calibration curve: Determination of aliphatic organic halogen compound> except that sandy soil was not added.
[0100]
<Sample preparation>
50 ml of the brown vial (actual volume: 68 ml) was injected with an amount of 1 g of the cleaning agent as iron composite particle powder and an amount of ion-exchanged water of 30.0 ml together with the water content in the cleaning agent, Next, 1 μl of trichlorethylene is injected, immediately covered with a rubber stopper with a fluororesin liner, and firmly tightened with an aluminum seal from above. The vial is shaken with a paint conditioner (Red Devil) for 3 hours.
[0101]
<Evaluation method>
The residual amount of trichlorethylene was measured in the same manner as in the above <Evaluation method of aliphatic organic halogen compound>.
[0102]
<Preparation of soil calibration curve: Determination of aromatic organic halogen compounds>
Trichlorobenzene (TCB: C₆H₃Cl₃): Molecular weight 181.45
Reagent grade (99.0% or more), density (20 ° C.) 1.46 g / ml
[0103]
Trichlorobenzene was made into three levels of 0.05 μl, 0.1 μl and 1.0 μl, 30 ml of ion-exchanged water was added to 50 ml of brown vial (actual volume 68 ml), and 20 g of sandy soil (under 2 mm mesh sieve) Seal, then inject each level of trichlorobenzene, immediately cover with a rubber stopper with a fluororesin liner, and tighten firmly with an aluminum seal from above. The vial is then shaken with a paint conditioner (Red Devil) for 10 hours. Thereafter, 10 ml of n-hexane was added, dispersed with an ultrasonic disperser for 20 minutes, separated with a centrifugal separator at 8000 rpm for 5 minutes, and 1.0 μl was taken from the upper hexane layer with a syringe, and “GC-MS-QP5050” was collected. ”(Manufactured by Shimadzu Corporation) is used to measure trichlorobenzene. Assuming that trichlorobenzene is not decomposed at all, the relationship between the amount added and the peak area is determined. The column at this time is a capillary column (DB-1: manufactured by J & W Scientific, liquid phase: dimethylpolysiloxane), He gas (143 l / min) is used as a carrier gas, and the temperature is maintained at 40 ° C. for 2 minutes. The gas is analyzed by raising the temperature to 250 ° C at a rate of ° C / min.
[0104]
<Sample preparation for measuring aromatic organic halogen compounds>
1.0 g of trichlorobenzene was added to 20 g of wet sandy soil in advance (under 2 mm mesh sieve) to prepare soil contaminated with trichlorobenzene. 50 ml of brown vials (actual volume 68 ml) were injected with an amount of 1 g of the detergent as iron composite particle powder and an amount of ion-exchanged water of 30.0 ml in combination with the water content in the detergent, The contaminated soil is poured, immediately covered with a rubber stopper with a fluororesin liner, and firmly tightened with an aluminum seal from above. The vial is shaken with a paint conditioner (Red Devil) for 10 hours. Thereafter, 10 ml of n-hexane is added, dispersed for 20 minutes with an ultrasonic disperser, and separated with 8000 rpm for 5 minutes with a centrifuge.
[0105]
<Evaluation method of aromatic organic halogen compound>
The residual amount of trichlorobenzene is measured by using the above-mentioned “GC-MS-QP5050” (manufactured by Shimadzu Corporation) by separating 1.0 μl from the centrifuged n-hexane layer with a syringe.
[0106]
<Preparation of groundwater calibration curve: Determination of aromatic organic halogen compounds>
A groundwater calibration curve was prepared in the same manner as described above in <Preparation of soil calibration curve: Determination of aromatic organic halogen compound> except that sandy soil was not added.
[0107]
<Sample preparation>
50 ml of the brown vial (actual volume: 68 ml) was injected with an amount of 1 g of the cleaning agent as iron composite particle powder and an amount of ion-exchanged water of 30.0 ml together with the water content in the cleaning agent, Next, 1 μl of trichlorobenzene is injected, immediately covered with a rubber stopper with a fluororesin liner, and firmly tightened with an aluminum seal from above. The vial is shaken with a paint conditioner (Red Devil) for 10 hours. Thereafter, 10 ml of n-hexane is added, dispersed for 20 minutes with an ultrasonic disperser, and separated with a centrifuge at 8000 rpm for 5 minutes.
[0108]
<Evaluation method>
The residual amount of trichlorobenzene was measured in the same manner as in the above <Method for evaluating aromatic organic halogen compound>.
[0109]
Measurement of hazardous substances such as heavy metals in the purification treatment is based on the Environmental Agency Notification No. 46 “Environmental Standards Concerning Soil Contamination” for the solid content of contaminated soil, and the Environmental Agency Notification No. 10 for contaminated groundwater. No. “Environmental standards for groundwater pollution” was analyzed.
[0110]
<Manufacture of purification agent>
N at a rate of 3.4 cm per second₂In a reaction vessel maintained in a non-oxidizing atmosphere by flowing gas, 1.16 mol / l Na₂CO₃After adding 704 l of aqueous solution, Fe²⁺Add 296 l of ferrous sulfate aqueous solution containing 1.35 mol / l and mix (Na₂CO₃The amount corresponds to 2.0 times equivalent to Fe. And FeCO at a temperature of 47 ° C.₃Was generated.
[0111]
The obtained FeCO₃In an aqueous solution containing₂While maintaining gas at a temperature of 47 ° C. for 70 minutes while blowing gas at a rate of 3.4 cm per second, the FeCO₃A goethite particle was produced by aeration of 2.8 cm of air at a temperature of 47 ° C. for 5.0 hours in an aqueous solution containing The pH during air ventilation was 8.5 to 9.5.
[0112]
The suspension containing the goethite particles obtained here was washed with a filter press. At that time, the degree of cleaning was controlled to leave a trace amount of S. The obtained press cake was extrusion molded with a molding plate having a pore diameter of 4 mm using a compression molding machine and dried at 120 ° C. to obtain a granulated product of goethite particles.
[0113]
The goethite particles contained in the granulated product obtained here consist of particles having a spindle shape with an average major axis diameter of 0.30 μm and an axial ratio (major axis diameter / minor axis diameter) of 12.5. However, the dendritic particles were not mixed. BET specific surface area is 85m²/ G, S content was 900 ppm.
[0114]
The granulated product is heated at 330 ° C. to form hematite particles and dry pulverized. Then, it is poured into water and 70% sulfuric acid is added at a rate of 4 ml / kg and stirred. Thereafter, it was dehydrated to form a press cake, extruded using a molding plate having a pore diameter of 3 mm using a compression molding machine, and dried at 120 ° C. to obtain a granulated product of hematite particles.
[0115]
The hematite particle powder constituting the granulated product obtained here consists of particles having a spindle shape with an average major axis diameter of 0.25 μm and an axial ratio (major axis diameter / minor axis diameter) of 10.5, and the particle size is uniform. Dendritic particles were not mixed. The S content was 2100 ppm.
[0116]
100 g of the granulated product of the hematite particle powder is introduced into a fixed bed reducing device, and H₂While the gas was bubbled, the mixture was reduced at 450 ° C. for 180 minutes until it was completely α-Fe. Next, N₂After switching to gas and allowing to cool to room temperature, 160 ml of ion-exchanged water was directly introduced into the reduction furnace and taken out as an aqueous suspension containing 30% by weight of iron particle powder.
[0117]
The aqueous suspension was transferred to a stainless beaker equipped with a baffle, and a T.W. K homodisper type 2.5 (edge turbine blade with a diameter of 40 mmφ, manufactured by Tokushu Kika Kogyo Co., Ltd.) was inserted and stirred at a rotational speed of 3600 rpm for 30 minutes.
[0118]
Next, as a continuous shearing type disperser, a T.I. Dispersion treatment was carried out at a rotation speed of 4000 rpm using a K homomic line mill (PL-SL type, manufactured by Tokushu Kika Kogyo Co., Ltd.).
[0119]
Then, as a media-type disperser, 0.25 l of glass beads having a diameter of 2 mm were filled in a 4-cylinder sand grinder (4TSG- (1 / 8G) type, manufactured by IMEX Co., Ltd.) having a power of 1.5 kW, and the rotational speed was 500 rpm. Dispersed to give a cleaning agent.
[0120]
The specific gravity of the resulting cleaning agent is 1.25, the solid content concentration is 30% by weight, and the particle size distribution of the cleaning agent (water suspension) by the laser diffraction / scattering method is a single peak as shown in FIG. And the median diameter (D₅₀) Is 2.40 μm, D₉₀/ D₁₀Ratio 1.86, distribution width (D₈₄-D₁₆) Was 1.15 μm.
[0121]
The iron composite particles contained in the obtained cleaning agent were observed with a scanning electron microscope (30000 times). As a result, as shown in FIG. 2, the primary particles had a rice grain shape and an average major axis diameter of 0. .13 μm and the axial ratio was 1.6.
[0122]
The iron composite particles obtained here are mainly composed of α-Fe and have a saturation magnetization value of 157 Am.²/ Kg (157 emu / g), BET specific surface area 26 m²/ G, crystallite size was 298 cm. The S content was 2900 ppm, and Cd, Pb, As and Hg were not detected. As a result of X-ray diffraction, α-Fe and Fe₃O₄And were confirmed to exist. The α-Fe content obtained from the calibration curve is 97.9 wt%, and the D₁₁₀(Α-Fe) and D₃₁₁(Fe₃O₄) Strength ratio D₁₁₀/ (D₁₁₀+ D₃₁₁) Was 0.95.
[0123]
<Results of purification of aliphatic organic halogen compounds>
According to the evaluation method, the residual rate of trichlorethylene in the soil when the purifier was used was 3.3%, and the residual rate of trichlorethylene in the groundwater was 4.0%.
[0124]
<Results of purification treatment of aromatic organic halogen compounds>
According to the evaluation method, when the cleaning agent was used, the residual rate of trichlorobenzene in the soil was 17.4%, and the residual rate of trichlorobenzene in the groundwater was 18.7%.
[0125]
[Action]
An important point in the present invention is that the organic halogen compound in soil and groundwater can be decomposed efficiently, continuously and economically by using the purification agent according to the present invention.
[0126]
The present inventor has not yet clarified the reason why organic halogen compounds in soil and groundwater can be effectively decomposed, but has estimated as follows.
[0127]
That is, the purifying agent according to the present invention is an iron composite particle having a narrow particle size distribution by sufficiently pulverizing iron composite particles that are active ingredients in the purifying agent, and can easily penetrate and disperse in soil or groundwater. Therefore, it is presumed that the iron composite particles were able to sufficiently exhibit the decomposition activity with respect to the organic halogen compounds originally possessed.
[0128]
In addition, when there are harmful substances composed of heavy metals such as cadmium, lead, hexavalent chromium, arsenic, selenium, and cyan together with organic halogen compounds, part of the iron composite particles dissolves and dissolved Fe and heavy metals By ferritizing, heavy metals in soil or groundwater can be insolubilized.
[0129]
【Example】
Next, examples and comparative examples of the present invention will be given.
[0130]
Goethite particles
The goethite particles shown in Table 1 were prepared as goethite particles.
[0131]
Goethite particles 2
When washing goethite particles similar to the goethite particles 1 with a filter press, the degree of washing was controlled to leave a trace amount of S. The obtained press cake was extrusion molded with a molding plate having a pore diameter of 4 mm using a compression molding machine and dried at 120 ° C. to obtain a granulated product of goethite particles.
[0132]
The goethite particles contained in the granulated product obtained here consist of particles having a spindle shape with an average major axis diameter of 0.30 μm and an axial ratio (major axis diameter / minor axis diameter) of 12.5. However, the dendritic particles were not mixed. BET specific surface area is 85m²/ G, S content was 1700 ppm.
[0133]
[Table 1]

[0134]
Purifier: Examples 1-5, Reference Examples 1-2, Comparative Examples 1-2;
A purifier was obtained in the same manner as in the above embodiment except that the kind of goethite particles, the temperature of heat dehydration, the temperature of heat reduction, the method of dispersion, etc. were variously changed.
[0135]
Manufacturing conditions at this time are shown in Tables 2 to 3, and various characteristics of the obtained purifiers are shown in Tables 4 to 5.
[0136]
Comparative Example 1 is reduced iron powder, and Comparative Example 2 is electrolytic iron powder.
[0137]
[Table 2]

[0138]
[Table 3]

[0139]
[Table 4]

[0140]
[Table 5]

[0141]
<Purification treatment of contaminated soil and contaminated groundwater>
Examples 6 to 10, Reference Examples 3 to 4, Comparative Examples 3 to 4;
Contaminated soil or contaminated groundwater was treated in the same manner as in the above-described embodiment except that the type of the purifying agent was changed variously.
[0142]
Table 6 shows the processing conditions and measurement results at this time.
[0143]
[Table 6]

[0144]
<Purification treatment with iron composite particles in soil contaminated with organic halogen compounds and heavy metals and other harmful substances>
1.0 g of trichlorethylene was added to 20 g of pre-moist sandy soil (under 2 mm mesh sieve) to prepare soil contaminated with trichlorethylene. Into 50 ml of brown vial (actual volume 68 ml), the purification agent of the embodiment as an iron composite particle was injected with 1 g of the purification agent and 27 ml of ion-exchanged water, then the contaminated soil was injected, and cadmium, lead , Arsenic, Selenium, and Cyan are each injected at 0.3 ml from a 1000 ppm standard solution (manufactured by Kanto Chemical Co., Ltd.), and the hexavalent chromium is 50 ppm at 1000 ppm standard solution (Kanto Chemical Co., Ltd.). 1.5 ml was injected from the product, and a total of 3.0 ml was injected so that the total amount was 100 ppm. The lid was immediately covered with a rubber stopper with a fluororesin liner, and the top was firmly tightened with an aluminum seal. The vial was shaken with a paint conditioner (manufactured by Red Devil) for 3 hours, and then 50 μl of the headspace gas of the vial was taken with a syringe, and the residual amount of trichlorethylene was measured using the above method. Thereafter, the mixture was further shaken for 13 hours (16 hours in total) and then separated into solid and liquid using a 0.45 μm membrane filter.
[0145]
Then, the same treatment was performed until a solid content (50 g) and a filtrate (300 ml) required for the measurement were obtained. Based on the Environmental Agency Notification No. 10 “Environmental Standards Concerning Groundwater Water Pollution”, the filtrate was dried in the atmosphere at 40 ° C. for 3 hours to obtain a sample, and the Environmental Agency Notification No. 46 “ The analysis was based on the “environmental standards for soil contamination”. As a result, cadmium in the solution is less than 0.001 mg / l, lead is less than 0.005 mg / l, hexavalent chromium is less than 0.04 mg / l, arsenic is less than 0.001 mg / l, selenium is less than 0.002 mg / l, cyan is Undetected, elution amount from solid was less than 0.001 mg / l cadmium, less than 0.005 mg / l lead, less than 0.04 mg / l hexavalent chromium, less than 0.001 mg / l arsenic, 0.002 mg / selenium Less than l and cyan were not detected.
[0146]
<Results of organic halogen compound purification>
According to the evaluation method, the residual rate of trichlorethylene in the soil when the iron composite particles were used was 2.3%.
[0147]
<Purification treatment with iron composite particles of groundwater contaminated with organic halogen compounds, heavy metals and other harmful substances>
Into 50 ml of brown vial (actual volume 68 ml), 1 g of the purifying agent of the embodiment as iron composite particles, 27.0 ml of ion-exchanged water, and 1.0 μl of trichlorethylene are injected, and cadmium, lead , Arsenic, Selenium, and Cyan are each injected at 0.3 ml from a 1000 ppm standard solution (manufactured by Kanto Chemical Co., Ltd.), and the hexavalent chromium is 50 ppm at 1000 ppm standard solution (Kanto Chemical Co., Ltd.). 1.5 ml was injected from the product, and a total of 3.0 ml was injected so that the total amount was 100 ppm. The lid was immediately covered with a rubber stopper with a fluororesin liner, and the top was firmly tightened with an aluminum seal. The vial was shaken with a paint conditioner (manufactured by Red Devil) for 3 hours, and then the residual amount of trichlorethylene was measured by taking 50 μl of the gas in the headspace of the vial with a syringe and using the above method. Then, after further shaking for 13 hours (16 hours in total), solid-liquid separation was performed using a 0.45 μm membrane filter.
[0148]
Next, the same treatment was performed until a solid content and a filtrate required for measurement were obtained. Based on the Environmental Agency Notification No. 10 “Environmental Standards Concerning Groundwater Water Pollution”, the filtrate was dried in the atmosphere at 40 ° C. for 3 hours to obtain a sample, and the Environmental Agency Notification No. 46 “ The analysis was based on the “environmental standards for soil contamination”. As a result, cadmium in the solution is less than 0.001 mg / l, lead is less than 0.005 mg / l, hexavalent chromium is less than 0.04 mg / l, arsenic is less than 0.001 mg / l, selenium is less than 0.002 mg / l, cyan is Undetected, elution amount from solid was less than 0.001 mg / l cadmium, less than 0.005 mg / l lead, less than 0.04 mg / l hexavalent chromium, less than 0.001 mg / l arsenic, 0.002 mg / selenium Less than l and cyan were not detected.
[0149]
<Results of organic halogen compound purification>
According to the evaluation method, the residual rate of trichlorethylene in the groundwater when the iron composite particles were used was 2.4%.
[0150]
【The invention's effect】
Since the purification agent according to the present invention can decompose organic halogen compounds efficiently, it is suitable as a purification agent for soil and groundwater contaminated with organic halogen compounds.
[Brief description of the drawings]
FIG. 1 is a graph showing the particle size distribution of iron composite particles contained in a cleaning agent obtained in an embodiment of the invention.
FIG. 2 is a scanning electron micrograph (30,000 magnifications) of iron composite particles contained in a cleaning agent obtained in an embodiment of the invention.

Claims (7)

An aqueous suspension containing iron composite particles composed of α-Fe and Fe ₃ O ₄ as active ingredients, wherein the primary particles of the iron composite particles have a rice grain shape and an average major axis diameter of 0. 0.05 to 0.50 μm, the axial ratio exceeds 1.0 and is 2.0 or less, the α-Fe content is 30 to 99% by weight, and the particle size distribution of the secondary particles of the iron composite particles is It is a single peak, and the median diameter (D ₅₀ : the particle diameter at which the cumulative ratio with respect to the particle diameter when the total volume of the iron composite particles is 100% is 50%) is 0.5 to 5.0 μm. A soil / groundwater purification agent contaminated with an organic halogen compound, wherein the D ₉₀ / D ₁₀ ratio is 1.0 to 5.0. An aqueous suspension containing iron composite particles composed of α-Fe and Fe ₃ O ₄ as active ingredients, wherein the primary particles of the iron composite particles have a rice grain shape and an average major axis diameter of 0. an a in the axial ratio of 1.0 to over 2.0 .05～0.50Myuemu, the X-ray diffraction spectrum in alpha-Fe of the iron composite particles (110) plane diffraction intensity _{D 110} and magnetite The intensity ratio (D ₁₁₀ / (D ₁₁₀ + D ₃₁₁ )) with the diffraction intensity D ₃₁₁ of the (311) plane is 0.20 to 0.98, and the particle size distribution of the secondary particles of the iron composite particles is single It is a peak, and the median diameter (D ₅₀ : the particle diameter at which the cumulative ratio with respect to the particle diameter is 50% when the total volume of the iron composite particles is 100%) is 0.5 to 5.0 μm. it _D 90 _{/ D 10} ratio of 1.0 to 5.0 Purifying agent of the soil or ground water contaminated with organohalogen compounds characterized. The specific gravity is 1.2 to 1.4, and the concentration is 20 to 40% by weight. The purifier for soil and groundwater contaminated with an organic halogen compound according to claim 1 or 2. The iron composite particles contained in the soil / groundwater purification agent contaminated with the organic halogen compound have a saturation magnetization value of 90 to 190 Am ² / kg, a BET specific surface area of 5 to 60 m ² / g, α The purifier for soil and groundwater contaminated with an organic halogen compound according to any one of claims 1 to 3, wherein the crystallite size of the (110) plane of -Fe is 200 to 500 mm. A goethite particle powder having an average major axis diameter of 0.05 to 0.50 μm or hematite particle powder obtained by heating and dehydrating the goethite particle powder in a temperature range of 250 to 350 ° C. is heated and reduced in a temperature range of 350 to 600 ° C. It is made into particle powder, and after cooling, the iron particle powder is taken out in water without forming a surface oxide film in the gas phase, and a surface oxide film is formed on the particle surface of the iron particle powder in water to contain iron composite particles A water suspension to be obtained, and then wet pulverized with a disperser or a stirrer, wherein the soil or groundwater purification agent contaminated with an organic halogen compound according to any one of claims 1 to 4 is used. Manufacturing method. The soil / groundwater purification agent contaminated with the organic halogen compound according to any one of claims 1 to 4 and the soil contaminated with the organic halogen compound or the groundwater contaminated with the organic halogen compound are mixed and contacted. A method for purifying soil and groundwater contaminated with an organic halogen compound. The soil contaminated with the soil or groundwater purifier contaminated with the organic halogen compound according to any one of claims 1 to 4, and the soil contaminated with the organic halogen compound and the heavy metal contaminant or the organic halogen compound and the heavy metal contaminant. A method for purifying soil and groundwater containing an organic halogen compound, comprising mixing and contacting groundwater contaminated with a substance.

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