JP4258623B2 - Iron composite particle powder for purification treatment of soil and groundwater contaminated with organic halogen compounds, its production method, purification agent containing the iron composite particle powder, its production method and purification treatment of soil and groundwater contaminated with organic halogen compounds Method - Google Patents

Description

【０１３４】
鉄複合粒子粉末又は浄化剤：実施例１〜５；
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に、得られた鉄複合粒子粉末又は浄化剤の諸特性を表３に示す。また、得られた鉄複合粒子粉末又は浄化剤の溶出試験結果を表４に示す。
【０１３６】
【表２】

【０１３７】
【表３】

【０１３８】
【表４】

【０１３９】
＜汚染土壌・汚染地下水の浄化処理＞
実施例６〜１０；
鉄複合粒子粉末又は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。
【０１４０】
このときの処理条件及び測定結果を表５に示す。
【０１４１】
【表５】

【０１４２】
＜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）にトリクロロベンゼン１．０μｌを添加し、トリクロロベンゼ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処理用鉄複合粒子１ｇ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。
【０１４３】
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。
【０１４４】
＜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ベンゼンの残存率は１９．２％であった。
【０１４５】
＜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、実施の形態の浄化処理用鉄複合粒子１ｇと２７．０ｍｌのイオン交換水、トリクロロベンゼン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、トリクロロベンゼ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。
【０１４６】
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。
【０１４７】
＜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ベンゼンの残存率は１９．９％であった。
【０１４８】
【発明の効果】
本発明に係る鉄複合粒子粉末又は浄化剤は、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。また、浄化剤に有害な重金属、その他の元素が含まれないので、上記土壌・地下水を浄化する際に有害な重金属、その他の元素にて土壌・地下水を汚染するものではなく環境に与える影響を低減することができる。[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, trichloroethylene, tetrachloroethylene, 1,3-dichloropropene or dioxins, aromatic halogen compounds such as PCB, or the above organic halogen compounds and cadmium, lead, hexavalent chromium, arsenic, selenium, cyanide The present invention provides a purifying agent that can efficiently and continuously purify pollutants made of heavy metals such as and reduce the load on the environment as much as possible.
[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. Many technical means have been proposed. In particular, it is known to decompose and remove organic halogen compounds using iron-based particles such as mill scale, granular iron and spongy iron powder in steel production (Patent Documents). 1-7).
[0010]
Here, a general method for manufacturing steel will be described.
[0011]
Steel production includes an indirect iron manufacturing method in which iron ore is reduced to molten pig iron, which is oxidized and refined into steel, and a direct iron manufacturing method in which iron ore is converted into steel without going through pig iron.
[0012]
In the indirect iron making method, the raw materials for the iron making process (reducing iron ore to pig iron) are iron ore and limestone (CaCO₃), Coke, and hematite, the main component of iron ore, is mainly Fe₂O₃Magnetite is mainly Fe₃O₄These are SiO₂, Al₂O₃It contains gangue with the main component. These raw materials are put into a blast furnace, and coke is burned with heated hot air to produce high-temperature CO and N₂Generate mixed gas and reduce iron ore. The iron produced by the reduction is solid, but as it descends in the blast furnace, it absorbs C, melts as pig iron and further absorbs C, Si, Mn, etc., and has a final composition. The composition of pig iron is usually 3.0 to 4.5% for C, 0.2 to 2.5% for Si, 0.02 to 0.5% for Mn, and 0.01 to P for P 0.5% and S is 0.01 to 0.5%. On the other hand, the gangue in the ore and the ash in the coke combine with limestone to form molten slag, which is separated by specific gravity difference. Then, the molten pig iron processing is performed as needed.
[0013]
In the molten pig iron treatment, desulfurization, dephosphorization, and desiliconization are performed. CaO, CaF2, CaCl are used as desulfurization fluxes.₂For example, mill scale, iron ore, etc. are used as a dephosphorization flux, and iron oxide, manganese ore, etc. are used as a desilicater.
[0014]
The untreated molten pig iron or the pig iron after the molten pig iron treatment is subjected to oxidative refining in a steel making furnace using pure oxygen (steel making process). Most of the steelmaking furnaces are compound converters, and the raw materials are molten pig iron, scrap, lime and fluorite as flux, and manganese ore as required. When pure oxygen is supplied, SiO₂, FeO, CaO, CaF₂Etc. are generated and become slag. Subsequently, C is oxidized to CO and decarburized. After that, secondary scouring is performed as necessary, and in most cases, the slab, bloom, billet and the like are cast by a continuous casting method.
[0015]
On the other hand, in the direct reduction method, iron ore, a reducing agent, and a fossilizing agent are used as raw materials, and solid or granular iron and spongy iron are used without passing through pig iron in a crude iron production furnace using fuel or electric heat. . Thereafter, the solid iron is melted in an electric furnace, and the subsequent steps are the same as in the indirect reduction method.
[0016]
In any of the above methods, the iron compound produced in the steel production process contains a large number of various impurities derived from the raw materials and additives, and is particularly noticeable in the steel production process by the direct reduction method. When detoxifying soil / groundwater contaminated with organohalogen compounds with a cleaning agent composed of iron-based particles, especially iron-based particles such as mill scale, granular iron and spongy iron powder in steel production Should be used for the purpose of purifying organic halogen compounds in soil and groundwater.
[0017]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 11-235577
[Patent Document 2]
JP 2000-5740 A
[Patent Document 3]
JP 2000-334063 A
[Patent Document 4]
JP 2001-198567 A
[Patent Document 5]
JP 2002-161263 A
[Patent Document 6]
JP 2002-210452 A
[Patent Document 7]
JP 2002-317202 A
[0018]
[Problems to be solved by the invention]
In the above-mentioned Patent Document 1, iron powder containing 0.1% by weight or more of carbon obtained by reduction refining, sintering, pulverization, and sieving using spongy ore reduced iron powder as a raw material is added to the soil. The technology to detoxify organic halogen compounds in soil by mixing is disclosed, but the raw material is derived from iron ore, and there is a large amount of impurities contained in most ordinary steel components and ordinary cast iron components It is difficult to say that it has high purification performance for organic halogen compounds.
[0019]
Moreover, although the above-mentioned patent document 2 discloses a technique for detoxifying organic halogen compounds in soil using copper-containing iron powder, spongy ore reduced iron powder is used in the same manner as the above-mentioned iron powder. Iron powder obtained by reduction, refining, sintering, crushing, and sieving operations is used as a raw material. Since the raw material is derived from iron ore, it is included in most ordinary steel components and ordinary cast iron components. It is estimated that there are a large amount of impurities and the like, and it is difficult to say that they have a high purification performance for organic halogen compounds.
[0020]
Patent Document 3 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, it is estimated that impurities such as Mn, Si, Cr, Al, P, and Ca are contained in the mill scale itself from several hundred ppm to several thousand ppm, and it is said that the mill scale has a high purification performance for organic halogen compounds. hard.
[0021]
Further, the above-mentioned Patent Document 4 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 C Water suspension obtained by collecting and removing the gas contained in the exhaust gas generated during refining from an oxygen blow furnace for steelmaking that blows oxygen into pig iron containing impurities such as Si, P, etc. The resulting spherical iron particles are presumed to contain impurities such as C, Si, and P as oxides, and it is difficult to say that they have high purification performance for organic halogen compounds.
[0022]
In addition, the aforementioned Patent Document 5 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, iron powder obtained by finishing reduction treatment of sponge iron powder obtained by reducing the mill scale resulting from the manufacturing process of hot rolled steel sheets at steelworks with coke in a hydrogen stream or water atomized molten steel. Since iron powder is used, it is estimated that impurities derived from mill scale and molten steel are usually contained, and it is difficult to say that it has high purification performance for organic halogen compounds.
[0023]
Further, in the above-mentioned Patent Document 6, 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.
[0024]
In addition, in the aforementioned Patent Document 7, 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.
[0025]
Accordingly, the present invention provides an organic halogen compound or an organic halogen compound contained in soil / groundwater and a pollutant composed of heavy metals such as cadmium, lead, hexavalent chromium, arsenic, selenium, and cyanide in an efficient and sustainable manner. It is a technical problem to provide a purification method using a purification agent that can be processed in an effective manner, and to obtain a purification agent that reduces the elution of impurities and reduces the load on the environment.
[0026]
[Means for Solving the Problems]
The technical problem can be achieved by the present invention as follows.
[0027]
That is, the present inventionα-Fe and Fe ₃ O ₄ Consisting ofThe cadmium elution amount of the iron composite particle powder is 0.01 mg / l or less, the elution amount of all cyan is not detected, the elution amount of lead is 0.01 mg / l or less, and the hexavalent chromium elution amount is 0.05 mg / l. The arsenic elution amount is 0.01 mg / l or less, the total mercury elution amount is 0.0005 mg / l or less, the selenium elution amount is 0.01 mg / l or less, and the fluorine elution amount is 0.8 mg / l or less. The elution amount of boron is 1 mg / l or less, and the α-Fe content is 30 to 99% by weight.The saturation magnetization value is 60 to 200 Am ² / Kg with a BET specific surface area of 5 to 60 m ² / G, crystallite size D ₁₁₀ Is 200 to 500 mm, and the average particle size is 0.05 to 0.50 μmAn iron composite particle powder for purification treatment of soil and groundwater contaminated with an organic halogen compound (Invention 1).
[0028]
In the present invention, the cadmium elution amount of the iron composite particle powder composed of α-Fe and magnetite is 0.01 mg / l or less, the elution amount of all cyan is not detected, and the elution amount of lead is 0.01 mg / l. 1 or less, hexavalent chromium elution amount 0.05 mg / l or less, arsenic elution amount 0.01 mg / l or less, total mercury elution amount 0.0005 mg / l or less, selenium elution amount 0.01 mg / l 1 or less, fluorine elution amount is 0.8 mg / l or less, boron elution amount is 1 mg / l or less, and diffraction intensity D of (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/ (D₃₁₁+ D₁₁₀)) Is 0.20 to 0.98The saturation magnetization value is 60 to 200 Am ² / Kg with a BET specific surface area of 5 to 60 m ² / G, crystallite size D ₁₁₀ Is 200 to 500 mm, and the average particle size is 0.05 to 0.50 μmAn iron composite particle powder for purification treatment of soil and groundwater contaminated with an organic halogen compound (Invention 2).
[0030]
The present invention also includes the present invention 1.Or 2A soil or groundwater purification agent contaminated with an organic halogen compound comprising an aqueous suspension containing, as an active ingredient, iron composite particle powder for purification treatment of soil and groundwater contaminated with other organic halogen compounds (the present invention)3).
[0031]
In the present invention, after purifying an aqueous solution containing a ferrous salt, an aqueous alkali hydroxide solution or an aqueous alkali carbonate solution is added to the aqueous solution to oxidize the suspension containing the ferrous iron-containing precipitate. The goethite particle powder having an average major axis diameter of 0.05 to 0.50 μm obtained by the above or the 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. And after cooling, the iron particle powder is taken out in water without forming a surface oxide film in the gas phase, and then the surface oxide film is formed on the particle surface of the iron particle powder in water. The present invention 1 is characterized by drying.Or 2Is a method for producing iron composite particle powder for purification treatment of soil and groundwater contaminated with other organic halogen compounds (the present invention).4).
[0032]
In the present invention, after purifying an aqueous solution containing a ferrous salt, an aqueous alkali hydroxide solution or an aqueous alkali carbonate solution is added to the aqueous solution to oxidize the suspension containing the ferrous iron-containing precipitate. The goethite particle powder having an average major axis diameter of 0.05 to 0.50 μm obtained by the above or the 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. After cooling, the iron particle powder is taken out in water without forming a surface oxide film in the gas phase, and an iron composite is formed by forming a surface oxide film on the particle surface of the iron particle powder in water. The present invention is characterized in that an aqueous suspension containing particle powder is obtained.3This is a method for producing a purification agent for soil and groundwater contaminated with other organic halogen compounds (the present invention).5).
[0033]
The present invention also includes the present invention 1.Or 2Organic halogen compounds characterized by mixing and contacting iron composite particle powder for purification treatment of soil and groundwater contaminated with other organic halogen compounds and soil contaminated with organic halogen compounds or groundwater contaminated with organic halogen compounds Is a method for purifying soil and groundwater contaminated with water (this invention6).
[0034]
The present invention also provides3Soil contaminated with organic halogenated compounds and soil contaminated with organic halogenated compounds mixed with soil contaminated with organic halogenated compounds or groundwater contaminated with organic halogenated compounds -It is a method for purifying groundwater (the present invention7).
[0035]
The present invention also includes the present invention 1.Or 2Soil / groundwater purification iron composite particles contaminated with organic halogen compounds and soil contaminated with organic halogen compounds and heavy metal contaminants or groundwater contaminated with organic halogen compounds and heavy metal contaminants A method for purifying soil and groundwater contaminated with an organic halogen compound, characterized by mixing contact (the present invention)8)
[0036]
The present invention also provides3Mixing contact between soil and groundwater purification agents contaminated with organic halogen compounds and soil contaminated with organic halogen compounds and heavy metal contaminants or groundwater contaminated with organic halogen compounds and heavy metal contaminants A method for purifying soil and groundwater contaminated with an organic halogen compound (this invention)9).
[0037]
The configuration of the present invention will be described in detail as follows.
[0038]
First, the present invention 1Or 2An iron composite particle powder for soil / groundwater purification treatment (hereinafter referred to as “iron composite particle powder”) contaminated with organic halogen compounds is described.
[0039]
In the iron composite particle powder according to the present invention, the cadmium elution amount is 0.01 mg / l or less, the elution amount of all cyan is not detected, the lead elution amount is 0.01 mg / l or less, and the hexavalent chromium elution amount is 0. .05 mg / l or less, arsenic elution amount is 0.01 mg / l or less, total mercury elution amount is 0.0005 mg / l or less, selenium elution amount is 0.01 mg / l or less, and fluorine elution amount is 0.00. 8 mg / l or less, and boron elution amount is 1 mg / l or less. When the elution amount of each element exceeds the above range, it is difficult to say that the organic halogen compound has a high purification performance, and the iron composite particle powder contains a large amount of harmful elements. When purifying soil / groundwater contaminated with a compound, there is a risk of contaminating the soil / groundwater with the harmful elements.
[0040]
The α-Fe content of the iron composite particle powder according to the present invention is 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, and the catalytic activity is remarkably deteriorated. Preferably it is 35-99 weight%, More preferably, it is 40-99 weight%.
[0041]
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.
[0042]
The average particle diameter of the iron composite particle powder according to the present invention is preferably 0.05 to 0.50 μm. When the average particle diameter is less than 0.05 μm, 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 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.
[0043]
The crystallite size (α-Fe (110) plane) of the iron composite particles according to the present invention is preferably 200 to 500 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. When it exceeds 500%, the α-Fe content can be increased, but the BET specific surface area becomes small, and it becomes difficult to obtain the intended effect of the present invention. More preferably, it is 200-350cm.
[0044]
The BET specific surface area value of the iron composite particle powder according to 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.
[0045]
The saturation magnetization value of the iron composite particle powder in the present invention is 60 to 200 Am.²/ Kg (60 to 200 emu / g) is preferable. 60 Am²If it is less than / kg, the α-Fe content is low and the catalytic activity is lowered, which is not preferable. 200 Am²When 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 90-190Am²/ Kg (90-190 emu / g), even more preferably 95-190 Am²/ Kg (95-190 emu / g).
[0046]
The iron composite particle powder according to 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. The method of containing a trace amount of S may be any of the method of controlling the degree of cleaning when the goethite particles are washed and the method of leaving the hematite particles by stirring and adding sulfuric acid or the like.
[0047]
The iron composite particle powder for purification treatment may be in the form of a granulated product.
[0048]
Next, the present invention3The soil and groundwater purification agents (hereinafter referred to as “purification agents”) contaminated with organic halogen compounds are described.
[0049]
The purifier is the present invention 1.Or 2Is an aqueous suspension containing the iron composite particle powder for purification treatment as an active ingredient, and the content of the iron composite particle powder for purification treatment in the aqueous suspension is in the range of 0.5 to 50 parts by weight. It can be selected appropriately.
[0050]
Next, a method for producing the iron composite particle powder according to the present invention will be described.
[0051]
The goethite particle powder is obtained by reacting, for example, an aqueous solution containing a ferrous salt with one or more selected from alkali hydroxide, alkali carbonate or ammonia according to a conventional method. It can be obtained by ventilating an oxygen-containing gas such as air through a suspension containing a ferrous iron-containing precipitate such as iron carbonate. The aqueous solution containing ferrous salt needs to reduce impurities such as heavy metals and have high purity.
[0052]
In order to reduce the amount of impurities in the aqueous solution containing the ferrous salt, for example, the steel sheet is pickled with sulfuric acid, and impurities that have precipitated on the surface layer of the steel sheet and dissolved and removed rust preventive oil are removed. There is a method using an aqueous ferrous salt solution obtained by dissolving a steel sheet with a small amount of iron. Non-iron scrap metal and scrap iron, steel plates that have been subjected to plating treatment, phosphate treatment and chromic acid treatment to improve corrosion resistance, steel plates to which antirust oil has been applied, etc. When the pickling solution is used, impurities remain in the iron composite particle powder and may be eluted into the soil or groundwater to be purified, which is not preferable. Also, alkali such as alkali hydroxide is added to the ferrous sulfate solution by-produced from the titanium oxide production process, etc., and titanium and other impurities are insolubilized as hydroxide by pH adjustment to remove precipitates and ultrafiltration There is a method to use it. It is preferable to use a steel plate with few impurities dissolved in sulfuric acid, and it is further preferable to remove impurities by pH adjustment. Either method has no industrial problems and is economically advantageous.
[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 cooling the iron particle powder after heat reduction, 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 surface of the iron particle powder in water, Then it is dried.
[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]
Next, the present invention5The method for producing a purification agent for soil and groundwater contaminated with organic halogen compounds according to the present invention4The iron particle powder after the heat reduction in is cooled and then taken out into water and used as a purification agent consisting of an aqueous suspension containing the iron composite particle powder as it is.
[0065]
In the cleaning agent of the present invention, it is preferable to pulverize and disperse the secondary aggregates of the iron composite particle powder.
[0066]
Next, the present invention6This section describes the purification method for soil and groundwater contaminated with organic halogen compounds.
[0067]
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.
[0068]
The in-situ decomposition method employs a method in which the iron composite particle powder for purification treatment or the purification agent is permeated or introduced into the basement through 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.
[0069]
In the in-situ extraction method, the excavated soil and the iron composite particle powder or cleaning agent for purification treatment are mixed using a sand mill, Henschel mixer, concrete mixer, Nauta mixer, uniaxial or biaxial kneader mixer, etc. What is necessary is just to stir. Further, the pumped ground water can be passed through a column or the like filled with the iron composite particle powder for purification treatment.
[0070]
The amount of iron composite particle powder for purification treatment or the amount of purification agent (solid content conversion) can be selected as appropriate according to the degree of contamination of organic halogen compounds in the soil and groundwater. Is preferably 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 soil. 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.
[0071]
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.
[0072]
Next, the present invention8Or the present invention9A method for purifying soil and groundwater contaminated with pollutants composed of organic halogen compounds and heavy metals is described.
[0073]
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.
[0074]
The amount of the iron composite particle powder for purification treatment or the amount of the purification agent (in terms of solid content) is the same as described above.
[0075]
DETAILED DESCRIPTION OF THE INVENTION
A typical embodiment of the present invention is as follows.
[0076]
Each elution amount of cadmium, lead, hexavalent chromium, arsenic, total mercury, selenium, total cyanide, fluorine and boron other than iron present in the iron composite particle powder is 1992 Environment Agency Notification No. 46 “Soil Based on “Environmental Standards Concerning Contamination”, the measurement was performed by the following method.
[0077]
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 particle diameter and axial ratio of the iron composite particle powder were measured using a scanning electron micrograph.
[0078]
The S content of each particle powder was measured using “Carbon Sulfur Analyzer: EMIA-2200” (manufactured by HORIBA).
[0079]
The crystal phase of each particle powder was identified by measuring in the range of 10 to 90 ° with an X-ray diffraction apparatus.
[0080]
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.
[0081]
α-Fe content = −51.387X²+ 151.88X
X: Strength ratio (D₁₁₀/ (D₁₁₀+ D₃₁₁))
[0082]
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.
[0083]
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).
[0084]
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.).
[0085]
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).
[0086]
<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
[0087]
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.
[0088]
<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. Pour 1 g of iron composite particle powder for purification treatment and 30 ml of ion-exchanged water into 50 ml of brown vial (actual volume: 68 ml), then pour the contaminated soil, and immediately cover with a rubber stopper with a fluororesin liner. Tighten firmly with aluminum seal. The vial is shaken with a paint conditioner (Red Devil) for 3 hours.
[0089]
<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.
[0090]
<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.
[0091]
<Sample preparation>
Inject 50 g of a brown vial (actual volume: 68 ml) with 1 g of iron composite particle powder for purification treatment and 30 ml of ion-exchanged water, then inject 1 μl of trichlorethylene, and immediately cover with a rubber stopper with a fluororesin liner. Tighten firmly with an aluminum seal. The vial is shaken with a paint conditioner (Red Devil) for 3 hours.
[0092]
<Evaluation method>
The residual amount of trichlorethylene was measured in the same manner as in the above <Evaluation method of aliphatic organic halogen compound>.
[0093]
<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
[0094]
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.
[0095]
<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. Pour 1 g of iron composite particle powder for purification treatment and 30 ml of ion-exchanged water into 50 ml of brown vial (actual volume: 68 ml), then pour the contaminated soil, and immediately cover with a rubber stopper with a fluororesin liner. Tighten firmly with aluminum seal. 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.
[0096]
<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.
[0097]
<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.
[0098]
<Sample preparation>
Pour 1 g of iron composite particle powder for purification treatment and 30 ml of ion exchange water into 50 ml of brown vial (actual volume 68 ml), then inject 1 μl of trichlorobenzene, and immediately cover with a rubber stopper with a fluororesin liner. Tighten firmly with aluminum seal. 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.
[0099]
<Evaluation method>
The residual amount of trichlorobenzene was measured in the same manner as in the above <Method for evaluating aromatic organic halogen compound>.
[0100]
<Manufacture of ferrous salt aqueous solution>
Steel pieces (choppers, shredders, trimmers, etc.) generated when the pickled steel sheets (those not coated with rust-preventing oils) that have been removed by washing the surface scale of hot-rolled steel sheets with acid are cut by shear cutting. Dissolve with sulfuric acid to obtain a ferrous sulfate aqueous solution.
[0101]
Next, an aqueous NaOH solution is added to the ferrous sulfate aqueous solution, the pH is maintained at 5.0, and heavy metal impurities contained in the steel plate are precipitated as hydroxides. Subsequently, the ferrous sulfate aqueous solution containing the hydroxide was filtered with an ultrafiltration device to separate and remove the heavy metal impurity hydroxide to obtain a high purity ferrous sulfate aqueous solution.
[0102]
<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 the aqueous ferrous sulfate 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.
[0103]
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.
[0104]
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.
[0105]
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.
[0106]
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.
[0107]
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.
[0108]
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 it was as a water suspension containing 30% by weight of iron particle powder (referred to as a purifier).
[0109]
Subsequently, it filtered, and it dried in air | atmosphere at 40 degreeC for 3 hours, and obtained the iron composite particle powder for a purification process (it is set as the iron composite particle powder for a purification process).
[0110]
As a result of observing with a scanning electron microscope (30000 times), the iron composite particles contained in the obtained purification agent had a primary particle shape of rice grains and an average major axis diameter of 0.13 μm.
[0111]
The obtained iron composite particles are mainly composed of α-Fe and have a saturation magnetization value of 156 Am.²/ Kg (156 emu / g), BET specific surface area 25 m²/ G, crystallite size of 297 kg, S content was 2900 ppm. 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.
[0112]
<Results of dissolution test of iron composite particle powder for purification treatment>
According to the evaluation method, the result of the dissolution test of the iron composite particle powder is that the dissolution amount of cadmium is less than 0.001 mg / l, the dissolution amount of all cyan is not detected, and the dissolution amount of lead is less than 0.001 mg / l. The elution amount of hexavalent chromium is less than 0.01 mg / l, the elution amount of arsenic is less than 0.001 mg / l, the elution amount of total mercury is less than 0.0005 mg / l, and the elution amount of selenium is less than 0.001 mg / l. The elution amount of fluorine is less than 0.5 mg / l and the elution amount of boron is less than 0.1 mg / l, both of which are below the detection limit of the measuring device, and all are below the standard value of the environmental standard. Met.
[0113]
<Results of purification of aliphatic organic halogen compounds>
According to the evaluation method, when the iron composite particle powder was used, the residual rate of trichlorethylene in the soil was 3.8%, and the residual rate of trichlorethylene in the groundwater was 5.0%.
[0114]
<Results of purification treatment of aromatic organic halogen compounds>
According to the evaluation method, when the iron composite particle powder was used, the residual rate of trichlorobenzene in the soil was 18.7%, and the residual rate of trichlorobenzene in the groundwater was 19.5%.
[0115]
<Purification treatment of soil contaminated with aliphatic organohalogen compounds with a purification agent>
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.
[0116]
According to the above <Evaluation Method for Aliphatic Organic Halogen Compound>, the residual ratio of trichlorethylene when the purifier was used was 3.7%.
[0117]
<Purification of groundwater contaminated with aliphatic organohalogen compounds with a purifier>
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.
[0118]
According to the above <Evaluation Method for Aliphatic Organic Halogen Compound>, the residual ratio of trichlorethylene when using the cleaning agent was 4.8%.
[0119]
<Purification treatment of soil contaminated with aromatic organic halogen compounds using a purifier>
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.
[0120]
The residual amount of trichlorobenzene was measured 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. When the cleaning agent was used, the residual ratio of trichlorobenzene was 17.9%.
[0121]
<Purification treatment of groundwater contaminated with aromatic organic halogen compounds with a purifier>
Into 50 ml of brown vial (actual volume 68 ml), an amount of cleaning agent of 1 g as iron composite particle powder and an amount of ion-exchanged water of 30.0 ml in combination with the water content in the cleaning agent are injected, and then Inject 1 μl of trichlorobenzene, immediately cover with a rubber stopper with a fluororesin liner, and tighten firmly 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.
[0122]
According to the above <Method for evaluating aromatic organic halogen compound>, the residual ratio of trichlorobenzene was 18.9%.
[0123]
[Action]
The important point in the present invention is that by using the iron composite particle powder for purification treatment or the purification agent according to the present invention, the organic halogen of the soil / groundwater can be used without contaminating the soil / groundwater with harmful heavy metals and other elements. The compound can be decomposed efficiently, continuously and economically.
[0124]
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.
[0125]
That is, the iron composite particle powder according to the present invention contains α-Fe, has increased the purity of the iron composite particles, and removed the harmful heavy metals and other elements which are catalyst poisons, thereby reducing the reactivity of the iron composite particles. It is presumed that this was due to the fact that the iron composite particles were able to sufficiently exhibit the decomposition activity with respect to the organic halogen compounds originally possessed.
[0126]
Further, in the present invention, the amount of harmful heavy metals such as cadmium, total cyanide, lead, hexavalent chromium, arsenic, total mercury, selenium, fluorine and boron, and other elements are reduced, thereby purifying soil or groundwater. Even if it is released into the environment after treatment, it does not pollute the environment, and the influence on the environment can be reduced as much as possible.
[0127]
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.
[0128]
【Example】
Next, examples of the present invention will be given.
[0129]
Goethite particles
The goethite particles shown in Table 1 were prepared as goethite particles.
[0130]
Goethite particles 2
Adjusting the concentration of the ferrous sulfate aqueous solution purified in the same manner as in the embodiment of the invention, Fe²⁺1.28 l of ferrous sulfate aqueous solution containing 1.50 mol / l and 30.2 l of 0.44N NaOH aqueous solution (Fe in ferrous sulfate aqueous solution)²⁺Is equivalent to 0.35 equivalents. And mixed with Fe (OH) at a pH of 6.7 and a temperature of 38 ° C.₂An aqueous ferrous sulfate solution containing Next, Fe (OH)₂Into the aqueous ferrous sulfate solution containing 130 g of air, 130 l / min of air was passed at a temperature of 40 ° C. for 3.0 hours to generate goethite core particles.
[0131]
5.4N Na was added to the ferrous sulfate aqueous solution containing the goethite core particles (the amount of the goethite core particles was 35 mol% with respect to the generated goethite particles).₂CO₃7.0 l of aqueous solution (Fe in residual ferrous sulfate aqueous solution²⁺This corresponds to 1.5 equivalents. ) And 130 l / min of air at a pH of 9.4 and a temperature of 42 ° C. for 4 hours to produce goethite particles. The suspension containing the obtained goethite particles was washed with a filter press, and the obtained press cake was extruded with a molding plate having a pore diameter of 4 mm using a compression molding machine and dried at 120 ° C. to obtain a goethite particle powder. It was set as the granulated material.
[0132]
The goethite particles contained in the granulated product obtained here consist of needle-shaped particles having an average major axis diameter of 0.33 μm and an axial ratio (major axis diameter / minor axis diameter) of 25.0. However, it was homogeneous and dendritic particles were relatively unmixed. BET specific surface area is 70m²/ G, S content was 1700 ppm.
[0133]
[Table 1]

[0134]
Iron composite particle powder or cleaning agent: Examples 1 to 5;
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]
The production conditions at this time are shown in Table 2, and the characteristics of the obtained iron composite particle powder or the purifier are shown in Table 3. In addition, Table 4 shows the dissolution test results of the obtained iron composite particle powder or the purification agent.
[0136]
[Table 2]

[0137]
[Table 3]

[0138]
[Table 4]

[0139]
<Purification treatment of contaminated soil and contaminated groundwater>
Examples 6-10;
Contaminated soil or contaminated groundwater was treated in the same manner as in the above-described embodiment except that the type of the iron composite particle powder or the purifying agent was variously changed.
[0140]
Table 5 shows the processing conditions and measurement results at this time.
[0141]
[Table 5]

[0142]
<Purification treatment with iron composite particles in soil contaminated with organic halogen compounds and heavy metals and other harmful substances>
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. Inject 50 g of a brown vial (actual volume 68 ml) 1 g of the iron composite particles for purification treatment of the embodiment and 27 ml of ion-exchanged water, then inject the contaminated soil, and add cadmium, lead, arsenic, selenium and cyanide. Inject 0.3 ml each from 1000 ppm standard solution (manufactured by Kanto Chemical Co., Ltd.) to 10 ppm each, and inject 1.5 ml from 1000 ppm standard solution (manufactured by Kanto Chemical Co., Ltd.) to 50 ppm hexavalent chromium. Then, 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.
[0143]
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.
[0144]
<Results of organic halogen compound purification>
According to the evaluation method, the residual rate of trichlorobenzene in the soil when the iron composite particles were used was 19.2%.
[0145]
<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 iron composite particles for purification treatment of the embodiment, 27.0 ml of ion-exchanged water, and 1.0 μl of trichlorobenzene are injected, and further cadmium, lead, arsenic, selenium and cyanide. 0.3 ml each from 1000 ppm standard solution (manufactured by Kanto Chemical Co., Ltd.) so that the concentration is 10 ppm, and 1.5 ml from 1000 ppm standard solution (manufactured by Kanto Chemical Co., Ltd.) so that hexavalent chromium is 50 ppm. 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 trichlorobenzene 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.
[0146]
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.
[0147]
<Results of organic halogen compound purification>
According to the evaluation method, the residual rate of trichlorobenzene in the groundwater when the iron composite particles were used was 19.9%.
[0148]
【The invention's effect】
The iron composite particle powder or purification agent according to the present invention is suitable as a purification agent for soil and groundwater contaminated with organic halogen compounds because it can efficiently decompose organic halogen compounds. In addition, since the decontaminant does not contain harmful heavy metals and other elements, it does not pollute the soil and groundwater with the harmful heavy metals and other elements when purifying the soil and groundwater. Can be reduced.

Claims (9)

The elution amount of cadmium in the iron composite particle powder composed of α-Fe and Fe ₃ O ₄ is 0.01 mg / l or less, the elution amount of all cyan is not detected, and the elution amount of lead is 0.01 mg / l or less, Hexavalent chromium elution amount 0.05 mg / l or less, arsenic elution amount 0.01 mg / l or less, total mercury elution amount 0.0005 mg / l or less, selenium elution amount 0.01 mg / l or less, elution of fluorine 0.8 mg / l or less, the elution amount of boron is less 1mg / l, α-Fe content of Ri 30 to 99 wt% der, saturation magnetization values at 60~200Am ² / kg There, BET specific surface area of 5~60m ² / g, a crystallite size _{D 110} is 200 to 500 Å, an organic halogen compound having an average particle size and wherein 0.05~0.50μm der Rukoto For purification of contaminated soil and groundwater Composite particles. The cadmium elution amount of the iron composite particle powder composed of α-Fe and magnetite is 0.01 mg / l or less, the elution amount of all cyan is not detected, the elution amount of lead is 0.01 mg / l or less, hexavalent chromium Elution amount 0.05 mg / l or less, Arsenic elution amount 0.01 mg / l or less, Total mercury elution amount 0.0005 mg / l or less, Selenium elution amount 0.01 mg / l or less, Fluorine elution amount 0.8 mg / l or less, the elution amount of boron is or less 1 mg / l, iron in X-ray diffraction spectrum in alpha-Fe composite particles (110) plane of the diffraction intensity _{D 110} and magnetite (311 ) plane intensity ratio of the diffraction intensity _{D 311} of _{(D 110 / (D 311 +} D 110)) is Ri der 0.20 to 0.98, the saturation magnetization value is 60~200Am ² / kg, BET specific surface area 5-60m ² / G, and a crystallite size _{D 110} is 200 to 500 Å, an average particle size for purification treatment of soil or ground water contaminated with organohalogen compounds, wherein 0.05~0.50μm der Rukoto Iron composite particle powder. Purification of soil and groundwater contaminated with an organic halogen compound comprising an aqueous suspension containing, as an active ingredient, iron composite particle powder for purification of soil and groundwater contaminated with the organic halogen compound according to claim 1 or 2. Agent. An average long axis obtained by purifying an aqueous solution containing a ferrous salt and then adding an aqueous alkali hydroxide solution or an aqueous alkali carbonate solution to the aqueous solution to oxidize the suspension containing the ferrous iron-containing precipitate. A goethite particle powder having a 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. is heated and reduced in a temperature range of 350 to 600 ° C. to obtain an iron particle powder. The iron particle powder is taken out in water without forming a surface oxide film in the gas phase after cooling, and then dried after forming a surface oxide film on the particle surface of the iron particle powder in water. A method for producing iron composite particle powder for purification treatment of soil and groundwater contaminated with an organic halogen compound according to claim 1 or 2 . An average long axis obtained by purifying an aqueous solution containing a ferrous salt and then adding an aqueous alkali hydroxide solution or an aqueous alkali carbonate solution to the aqueous solution to oxidize the suspension containing the ferrous iron-containing precipitate. A goethite particle powder having a 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. is heated and reduced in a temperature range of 350 to 600 ° C. to obtain an 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 water containing iron composite particle powder is formed in the surface by forming a surface oxide film on the particle surface of the iron particle powder. The method for producing a purification agent for soil or groundwater contaminated with an organic halogen compound according to claim 3 , wherein a suspension is obtained. Claim 1 or 2 contacting mixing the ground water contaminated with soil or organic halogen compound contaminated with cleaning processing iron composite particles and an organic halogen compound contaminated soil or ground water with organic halogen compounds described in A method for purifying soil and groundwater contaminated with an organic halogen compound. An organic halogen compound characterized by mixing and contacting the soil / groundwater purification agent contaminated with the organic halogen compound according to claim 3 and soil contaminated with the organic halogen compound or groundwater contaminated with the organic halogen compound. Purification method for contaminated soil and groundwater. Soil contaminated with soil or groundwater purification iron composite particle powder contaminated with organohalogen compound according to claim 1 or 2 , soil contaminated with organic halogen compound and heavy metal, or pollutant composed of organic halogen compound and heavy metal A method for purifying soil and groundwater contaminated with an organic halogen compound, comprising mixing and contacting groundwater contaminated with A soil or groundwater purification agent contaminated with an organic halogen compound according to claim 3 and soil contaminated with a contaminant composed of an organic halogen compound and heavy metal or a groundwater contaminated with a contaminant composed of an organic halogen compound and heavy metal. A method for purifying soil and groundwater contaminated with an organic halogen compound, characterized by mixing contact.