JP2013208527A - Iron composite particle powder for purifying soil, ground water, and waste water, purifying agent including the iron composite particle powder, and method for purifying soil, ground water, and waste water contaminated by organic halogen compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purifying agent capable of efficiently, sustainably, and economically decomposing/insolubilizing aliphatic organic halogen compounds, aromatic organohalogen compounds, and heavy metal such as cadmium, lead, chromium, arsenic, selenium, cyanide, etc., included in soil, ground water, and waste water.SOLUTION: Iron composite particle powder is made of α-Fe and magnetite used for purification of soil, ground water, and waste water contaminated by organic halogen compounds. In a X-ray diffraction spectrum of the iron composite particle powder, intensity ratio ( D/(D+D)) between diffraction intensity Dof an α-Fe surface (110) and diffraction intensity Dof a magnetite surface (311) is 0.30-0.95, an Al content is 0.10-1.50 wt.%, an S content is 3,500-7,000 ppm, and the content of Ni and/or Cu is 0.1-3.0 wt.%.

Description

  The present invention relates to dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,1,1-trichloroethane, 1, 1 contained in soil, groundwater and wastewater. Aliphatic organic halogen compounds such as 2-trichloroethane, trichloroethylene, tetrachloroethylene and 1,3-dichloropropene, aromatic organic halogen compounds such as dioxins and PCB, heavy metals such as cadmium, lead, chromium, arsenic, selenium and cyanide The present invention provides a cleaning agent that can be decomposed and insolubilized efficiently, continuously and economically.

  Aliphatic organic halogen compounds such as trichlorethylene and tetrachloroethylene are widely used for cleaning in semiconductor factories and for degreasing metalworking metals.

  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.

  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.

  Organohalogen compounds such as aliphatic organohalogen compounds and aromatic organohalogen compounds are difficult to decompose and are also carcinogenic or highly toxic. It is a problem.

  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.

  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.

  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.

  Of the technical means proposed as a purification method for soil, groundwater and wastewater contaminated with organic halogen compounds, mixed contact of soil, groundwater and wastewater contaminated with organic halogen compounds and a purification agent using iron-based particles Technical means for making them harmless have been proposed (Patent Documents 1 to 10).

JP 2000-5740 A JP 2002-161263 A JP 2003-105313 A Japanese Patent Laid-Open No. 2003-136051 JP 2004-83860 A JP 2006-326561 A JP 2010-194450 A JP 2010-194451 A JP 2011-26524 A JP2011-46985A

  A purification agent capable of efficiently and economically decomposing organohalogen compounds contained in soil, groundwater or wastewater is currently most demanded, but has not yet been obtained.

  That is, the above-mentioned patent document 1 discloses a technique for detoxifying organic halogen compounds in soil using iron powder containing copper. However, since it takes a long time to decompose organic halogen compounds, it is efficient. It is difficult to say that organic halogen compounds can be rendered harmless.

  In addition, the aforementioned Patent Document 2 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, the iron powder obtained by mill scale and the iron powder obtained by water atomization of the molten steel are used. From the specific surface area of the iron powder described, the particle size of the iron powder seems to be large. It is difficult to say that the compound can be sufficiently reduced.

  Further, in the aforementioned Patent Document 3, an organic halogen compound detoxifying treatment agent comprising graphite and Fe—Ni, having a graphite content of 1 to 20% by weight and an Ni content of 0.1 to 15% by weight. Although it is described, it seems that the particle size is large, and it cannot be said that the organic halogen compound can be sufficiently reduced.

  Further, in the aforementioned Patent Document 4, metal powder for decomposing organohalogen compounds comprising nickel-adhered iron particles in which a phase containing iron as a main component is a base metal phase and a phase containing nickel as a main component is an adhering metal phase. However, it is difficult to say that the particle size is as large as 1 to 500 μm and the organic halogen compound can be sufficiently reduced.

  In addition, in the above-mentioned Patent Document 5, it is described that the iron composite particle powder composed of α-Fe and magnetite is used for soil / groundwater contaminated with an organic halogen compound, but a small amount of it is described. It was still not enough to efficiently decompose in a short time with the added amount.

  Further, in the above-mentioned Patent Document 6, iron-based particles for purification are described in which Ni fine particles having an average particle diameter of 1 to 50 nm are attached to the surface of iron powder containing iron as a main component. It is difficult to say that the average particle diameter is as large as 65 μm and the organic halogen compound can be sufficiently reduced.

  In addition, in the above-mentioned Patent Document 7, an organic powder that mixes iron powder and nickel sulfate and / or nickel chloride of less than 0.1% by weight with respect to the iron powder is mixed with soil, drainage, or groundwater contaminated with an organic halide. A method for purifying halides is described, and the above-mentioned Patent Document 8 describes a partial alloy powder having a partial alloy phase of iron and nickel inside and / or on the surface of iron powder, and 0. An organic halide purification method is described in which less than 1% by weight of nickel sulfate and / or nickel chloride is mixed with soil, drainage or groundwater contaminated with organic halides. However, the particle diameters of the iron powder and the partial alloy powder are relatively large, and it cannot be said that the organic halogen compound can be sufficiently reduced with a small addition amount.

  In addition, Patent Document 9 described above discloses a decomposition material for an organic halogen compound made of iron powder whose surface is coated with a noble metal such as nickel. However, the iron powder has a large particle size and a small amount of addition. Therefore, it is difficult to say that the organic halogen compound can be sufficiently reduced.

  Further, in Patent Document 10 mentioned above, an organic halogen composed of iron powder in which nickel is precipitated on the surface by pulverizing or strongly stirring iron powder and a water-soluble nickel aqueous solution, and nickel is partially alloyed with iron. Although a chemical decomposition treatment agent is described, it is difficult to say that an organic halogen compound can be sufficiently reduced with a small amount of iron powder having a large iron powder particle size.

  Then, this invention makes it a technical subject to provide the iron composite particle powder which can process the organic halogen compound contained in soil, groundwater, and wastewater efficiently and economically, and the purification method using the same.

The technical problem can be achieved by the present invention as follows.
That is, the present invention is an iron composite particle powder composed of α-Fe and magnetite used for purification treatment of soil, groundwater, and wastewater contaminated with an organic halogen compound, and in the X-ray diffraction spectrum of the iron composite particle powder, α intensity ratio between the diffraction intensity _{D 311} of diffraction intensity _{D 110} and magnetite (311) plane of the (110) plane of _{-Fe (D 110 / (D 311} + D 110)) is 0.30 to 0.95, The Al content is 0.10 to 1.50% by weight, the S content is 3500 to 7000 ppm, and the Ni and / or Cu content is 0.1 to 3.0% by weight. This is an iron composite particle powder for purification treatment of soil, groundwater, and wastewater (Invention 1).

  Further, the present invention provides the iron composite particle powder for purification treatment of soil, groundwater and wastewater according to the present invention 1, wherein Ni and / or Cu in the iron composite particle powder is coated and supported in a metal state near the particle surface. (Invention 2).

  Further, the present invention is the iron composite particle powder for purification treatment of soil / groundwater / waste water according to the present invention 1 or 2 having an average particle size of 0.05 to 0.50 μm (present invention 3).

  Further, the present invention provides a soil, groundwater, wastewater purifier comprising a water suspension containing the iron composite particle powder for purification treatment of soil, groundwater, wastewater according to any one of the present invention 1 to 3 as an active ingredient. (Invention 4).

  Further, the present invention is a kind selected from iron composite particle powder for purification treatment of soil, groundwater, wastewater according to any one of the present inventions 1 to 3, and polyacrylic acid, polymaleic acid, polyaspartic acid or a salt thereof. It is a purification agent for soil, groundwater and wastewater comprising a water suspension containing the above additives as active ingredients (Invention 5).

  In addition, the present invention provides an iron composite particle powder for purification treatment of soil, groundwater, wastewater according to any one of the present invention 1 to 3, or a soil, groundwater, wastewater purifier, and an organic halogen compound according to the present invention 4 or 5. This is a method for purifying soil, groundwater and wastewater mixed with soil, groundwater and wastewater contaminated with (Invention 6).

  Further, the present invention is a soil characterized by directly injecting the soil, groundwater, or waste water purifier according to the present invention 4 or 5 into the soil or groundwater contaminated with an organic halogen compound in situ. A method for purifying groundwater and wastewater (present invention 7).

  The iron composite particle powder for purification treatment according to the present invention can decompose organic halogen compounds efficiently and economically and is therefore suitable as a purification agent for soil and groundwater contaminated with organic halogen compounds.

  The configuration of the present invention will be described in detail as follows.

  First, the iron composite particle powder for purification treatment of soil, groundwater and wastewater according to the first to third aspects of the present invention (hereinafter referred to as “iron composite particle powder for purification treatment”) will be described.

The constituent phase of the iron composite particle powder for purification treatment contains an Fe ₃ O ₄ phase together with the α-Fe phase. In the X-ray diffraction spectrum of the iron composite particle powder, the content of Fe ₃ O ₄ is the diffraction intensity D ₁₁₀ of the (110) plane of α-Fe and the diffraction intensity D ₃₁₁ of the (311) plane of Fe ₃ O ₄ . The intensity ratio (D ₁₁₀ / (D ₃₁₁ + D ₁₁₀ )) is 0.30 to 0.95. When the strength ratio immediately after production is less than 0.30, the α-Fe phase existing ratio is low, so the purification performance of the organic halogen compound is not sufficient, and it is difficult to easily obtain the intended effect of the present invention. . When the strength ratio exceeds 0.95, the abundance ratio of the α-Fe phase is sufficient, but the abundance ratio of the Fe ₃ O ₄ phase produced in the present invention is lowered, and the catalyst activity is prematurely deteriorated and sustained. Therefore, the intended effect of the present invention cannot be obtained. Preferably it is 0.32-0.95. Fe ₃ O ₄ is preferably present on the particle surface of the iron composite particle powder for purification treatment.

  The S content of the iron composite particle powder for purification treatment according to the present invention is 3500 to 7000 ppm. When the S content is less than 3500 ppm, the purification performance of the organic halogen compound is not sufficient, and the intended effect of the present invention cannot be obtained. When it exceeds 7000 ppm, there is a purification performance of the organic halogen compound, but even if it is contained in a large amount, the effect is saturated and it is not economical. Preferably it is 3800-7000 ppm, More preferably, it is 3800-6500 ppm.

The Al content of the iron composite particle powder for purification treatment according to the present invention is 0.10 to 1.50% by weight. When the Al content is less than 0.10% by weight, it tends to be a hard granulated product due to volume shrinkage of the granulated product, and therefore labor is required when performing wet grinding. When the amount exceeds 1.50% by weight, the reduction reaction proceeds slowly and requires a long time for the reduction reaction. In addition, the crystal growth cannot be sufficiently performed, the α-Fe phase becomes unstable, and a thick oxide film is formed on the particle surface, and the phase change from the Fe ₃ O ₄ phase to the α-Fe phase during the heating reduction occurs. Since it is insufficient, it becomes difficult to increase the abundance ratio of the α-Fe phase, and the intended effect of the present invention cannot be obtained. Preferably it is 0.20 to 1.20% by weight.

  The Ni and / or Cu content of the iron composite particle powder for purification treatment according to the present invention is 0.1 to 3.0% by weight. When the Ni and / or Cu content is less than 0.10% by weight, the purification activity of the organic halogen compound is low, and the amount of the iron composite particle powder for purification treatment added to the organic halogen compound needs to be excessively large. is there. When it exceeds 3.0% by weight, although the purification activity of the organic halogen compound is high, the α-Fe phase in the iron composite particles for purification treatment is largely consumed for hydrogen generation by reaction with water, and the purification performance Sustainability of is likely to deteriorate. Preferably it is 0.5 to 2.0% by weight.

  Ni and / or Cu in the iron composite particle powder for purification treatment according to the present invention is coated and supported in the vicinity of the particle surface in a metal state, thereby improving the purification activity for the organic halogen compound. Furthermore, it is preferable that Ni and / or Cu in the present invention exist in the form of particles on the particle surface of the iron composite particles.

  The particle shape of the iron composite particle powder for purification treatment according to the present invention is preferably granular. In the present invention, the spindle-shaped or needle-shaped goethite particle powder or hematite particles are subjected to heat reduction treatment as they are, so that when undergoing crystal transformation to the α-Fe phase, the particle shape collapses and undergoes an isotropic growth process, so that the granular shape 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.

The average particle 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 particle size 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 abundance ratio of the α-Fe phase. The effect is not obtained. If it exceeds 0.50 μm immediately after production, the abundance ratio of the α-Fe phase can be increased, but the abundance ratio of the Fe ₃ O ₄ phase is relatively lowered, leading to early deterioration of catalytic activity and deterioration of maintainability. For this reason, the object of the present invention cannot be easily solved. More preferably, it is 0.05-0.30 micrometer.

The crystallite size (α-Fe (110) plane) of the iron composite particle powder for purification treatment according to the present invention is preferably 200 to 400 mm. If it is less than 200%, it is difficult to increase the abundance ratio of the α-Fe phase, and it becomes difficult to obtain the intended effect of the present invention. If it exceeds 400%, the abundance ratio of the α-Fe phase can be increased, but it is difficult to maintain the abundance ratio of the Fe ₃ O ₄ phase produced in the present invention to such an extent that the intended effect of the present invention can be obtained. It becomes. More preferably, it is 200-350cm.

The BET specific surface area value of the iron composite particle powder for purification treatment according to the present invention is preferably 5 to 60 m ² / g. When it is less than 5 m ² / g, the contact area is small, and the catalytic activity is hardly exhibited. When it exceeds 60 m ² / g, it is difficult to increase the abundance ratio of the α-Fe phase, and it becomes difficult to obtain the intended effect of the present invention. More preferably, it is 7-55 m < ² > / g.

The saturation magnetization value of the iron composite particle powder for purification treatment according to the present invention is preferably 85 to 155 Am ² / kg (85 to 155 emu / g). When the saturation magnetization value of the iron composite particle powder for purification treatment immediately after production is less than 85 Am ² / kg, the abundance ratio of the α-Fe phase is low, and the object of the present invention is easily solved. I can't. When it exceeds 155 Am ² / kg, the abundance ratio of the α-Fe phase can be increased, but the abundance ratio of the Fe ₃ O ₄ phase obtained by the present invention should be maintained to such an extent that the intended effect of the present invention can be obtained. It becomes difficult. As a result, the abundance ratio of the Fe ₃ O ₄ phase is relatively low, leading to early deterioration of catalyst activity and a decrease in maintainability. Therefore, the object of the present invention cannot be easily solved. More preferably, it is 90-155 Am < ² > / kg (90-155 emu / g).

  The Fe content of the iron composite particle powder for purification treatment according to the present invention is preferably 75% by weight or more based on the total particle powder. When the Fe content immediately after the production is less than 75% by weight, the catalytic activity is lowered, so that it is difficult to easily obtain the intended effect of the present invention. More preferably, it is 75 to 98% by weight, and still more preferably 75 to 90% by weight.

  The iron composite particle powder for purification treatment according to the present invention is composed of Pb, Cd, As, Hg, Sn, Sb, Ba, Zn, Cr, Nb, Co, Bi, and other toxic metals other than Fe, Ni, and Cu. It is preferable not to contain as much as possible.

  The iron composite particle powder for purification treatment may be in the form of a granulated product.

  Next, the purification agent (hereinafter referred to as “purifying agent”) of soil, groundwater and wastewater contaminated with the organic halogen compound according to the present invention 4 or 5 will be described.

The purification agent according to the present invention 4 or 5 is a water suspension containing the iron composite particle powder for purification treatment according to any one of the present invention 1 to 3 as an active ingredient, and the water of the iron composite particle powder for purification treatment The content in the suspension can be appropriately selected within the range of 10 to 40% by weight, and more preferably 10 to 30 parts by weight. When the amount exceeds 40% by weight, the viscosity of the cleaning agent increases, so that the mechanical load during stirring is difficult to be transmitted, and it is difficult to uniformly mix, so it is difficult to adjust the concentration.

  In the cleaning agent according to the fifth aspect of the present invention, by containing one or more dispersants selected from polyacrylic acid or a salt thereof, polyaspartic acid or a salt thereof, and polymaleic acid or a salt thereof, the purification agent is remarkably compared with the conventional one. It can improve the permeability to soil. Maleic acid or its salt is also biodegradable, but especially polyaspartic acid or its salt is very good in biodegradability and causes biodegradation by microorganisms after injection into soil / groundwater. Since it is hardly recognized that it accumulates in the environment, it is more suitable as a dispersant for the cleaning agent for in-situ purification treatment.

  The specific gravity of the purifier according to the present invention is preferably 1.2 to 1.4. If it is less than 1.2, solid content is small and not economical considering the transport of the cleaning agent and the amount added to the soil. In the case of exceeding 1.4, considering the primary particle size and secondary particle size of the present invention, the cleaning agent thickens, and it is difficult to produce it industrially.

  Next, a method for producing iron composite particle powder for purification treatment of soil, groundwater, and wastewater contaminated with an organic halogen compound according to the present invention will be described.

  The iron composite particle powder for purification treatment according to the present invention is produced by producing goethite particles according to a conventional method, heating to make hematite particles as necessary, and then heating and reducing the goethite particles or the hematite particles to obtain an iron particle powder. Then, the iron particle powder is taken out in water by forming a surface oxide film on the surface of the iron particle powder in the gas phase, or the iron particle powder is taken out in water and put on the particle surface of the iron particle powder in water. An aqueous suspension containing iron composite particles composed of α-Fe and magnetite is formed by forming a surface oxide film, and then Ni and / or Cu metal is supported on the particle surface of the iron composite particles in the aqueous suspension. -After coating, it can be obtained by filtration, washing with water and drying.

  The aqueous suspension containing iron composite particles composed of α-Fe and magnetite in the present invention has an average major axis diameter of 0.05 to 0.50 μm and an Al content of 0.06 to 1.00% by weight. The S content is from 2200 to 5500 ppm, and the average major axis diameter is from 0.05 to 0.50 μm, the Al content is from 0.07 to 1.13 wt%, and the S content is 2400-8000 ppm hematite particle powder is heated and reduced in the temperature range of 350-600 ° C. to form iron particle powder, and then the iron particle powder is coated with a surface oxide film on the surface of the iron particle powder in the gas phase. It can be obtained by forming and taking out in water, or taking out the iron particle powder into water and forming a surface oxide film on the particle surface of the iron particle powder in water.

  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.

  In addition, in order to obtain the iron composite particle powder for purification processing with a small impurity content, it is preferable to use a high-purity one that reduces impurities such as heavy metals as the aqueous solution containing the ferrous salt.

  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. Pickling of scrap iron and scrap iron with a lot of metal impurities other than iron, steel plates with plating treatment, phosphate treatment and chromic acid treatment to improve corrosion resistance, and steel plates with anti-rust oil applied When the liquid is used, impurities remain in the iron composite particle powder, and there is a possibility that it may elute into the soil or groundwater to be purified. 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 hydroxides 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.

The average major axis diameter of the goethite particle powder is 0.05 to 0.50 μm, and the S content is 2500 to 5500 ppm. The particle shape may be either spindle-shaped or needle-shaped. Axial ratio is preferably from 4 to 30, more preferably from 5 to 25, BET specific surface area is preferably 20 to 200 m ² / g, more preferably 25~180m ² / g.

  In the present invention, it is important that the goethite particles contain Al or the goethite particles are coated with Al. The hardness of the granulated product can be controlled by suppressing the volume shrinkage of the granulated product by containing or coating Al. Therefore, the labor for wet pulverization can be reduced. Further, the size of the primary particles can be relatively reduced, the specific surface area is also relatively increased, and the performance is improved.

  The Al content or the Al coating amount of the goethite particle powder is preferably 0.06 to 1.00% by weight.

  The goethite particle powder is preferably granulated according to a conventional method. By granulating, a fixed bed type reduction furnace can be used, and even when iron composite particles are used, it is possible to maintain the shape of the granulated product as it is depending on the reducing conditions. Is preferred.

  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.

  The hematite particle powder in the present invention uses goethite particles having a high S content in advance, or in the case of goethite particles having a low S content, by adding sulfuric acid to an aqueous suspension of the hematite particle powder, The S content of the hematite particle powder is controlled.

  The average major axis diameter of the hematite particle powder is 0.05 to 0.50 μm, and the S content is 2400 to 8000 ppm. The Al content or the Al coating amount of the hematite particle powder is preferably 0.07 to 1.13% by weight.

  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.

When the heating reduction temperature is less than 350 ° C., the reduction reaction proceeds slowly and takes a long time for the reduction reaction. Moreover, although the BET specific surface area can be increased, crystal growth cannot be sufficiently performed, the α-Fe phase becomes unstable, and a thick oxide film is formed on the particle surface, or from the Fe ₃ O ₄ phase. Since the phase change to the α-Fe phase is insufficient, the abundance ratio of the α-Fe phase cannot be increased. 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.

  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.

The iron particle powder after the heat reduction is cooled, and then the iron particle powder is formed with a surface oxide film of Fe ₃ O _{4 in} the gas phase and taken out in water, or taken out into water and put on the particle surface of the iron particle powder. A surface oxide film is formed.

  The method of forming the surface oxide film is a method in which the atmosphere after reduction is once replaced with an inert gas, and then the oxygen content in the inert gas is gradually increased to air, and oxygen and water vapor are mixed. It can be taken out into the air by a method of gradually oxidizing using gas. In addition, the formation temperature of the surface oxide film in the gas phase is preferably 150 ° C. or lower, and is preferably cooled to 100 ° C. or lower when taken out in water.

On the other hand, when taking out in water, without forming an oxide film in a gaseous phase, it is preferable to cool to 100 degrees C or less. After heat reduction, when taken directly into water without forming a surface oxide film in the gas phase, water is decomposed by the catalytic activity of α-Fe to generate hydrogen and oxygen, and α is generated by the generated oxygen. It is presumed that -Fe is oxidized and an oxide film composed of Fe ₃ O ₄ is formed on the particle surface.

  In addition, although the atmosphere at the time of cooling after heat reduction may be either nitrogen or hydrogen, it is preferable to finally switch to nitrogen.

  Next, the obtained aqueous suspension of iron composite particle powder made of α-Fe and magnetite is pulverized and dispersed using a wet pulverizer.

  As a pulverizer used for wet pulverization, when media 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.

  The iron particle concentration in the suspension during wet pulverization is preferably 20 to 40% by weight. 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.

  The iron composite particles for purification treatment according to the present invention are obtained by supporting and coating Ni and / or Cu metal on the surface of the iron composite particles composed of α-Fe and magnetite after pulverization, filtering, washing with water and drying. A particle powder is obtained.

  As a method for supporting and coating Ni and / or Cu metal on the surface of iron composite particles composed of α-Fe and magnetite, Ni metal salt and / or Cu metal is added to an aqueous suspension containing the iron composite particles. Examples include a method in which an aqueous solution of salt is added and mixed, and substitution plating is performed on Fe0 or Fe2 + and metal ions on the surface of the iron composite particles.

  As the Ni and / or Cu metal salt, nitrates, acetates, chlorides and the like can be used.

  The drying atmosphere after filtration and washing with water can be selected as appropriate, such as nitrogen, air, or vacuum, but the temperature is preferably 100 ° C. or lower.

  Next, a method for producing a purification agent for soil, groundwater and wastewater according to the present invention will be described.

  The method for producing a purification agent for soil, groundwater, and wastewater according to the present invention is the method for producing the iron composite particle powder for purification treatment, wherein Ni and / or Cu is formed on the particle surface of the iron composite particles comprising the α-Fe and magnetite. What was washed and washed by decantation after supporting / coating the metal is used as a purification agent consisting of an aqueous suspension containing the iron composite particle powder for purification treatment as it is.

  In the present invention, after producing an aqueous suspension containing iron composite particles composed of α-Fe and magnetite in advance according to the production method, the suspension is applied to a construction site where the soil / groundwater is purified. The iron composite particles can be supported and coated with Ni and / or Cu metal according to the method described above with respect to the aqueous suspension containing the iron composite particles composed of α-Fe and magnetite at the construction site.

  The cleaning agent according to the present invention may contain one or more dispersants selected from polyacrylic acid or a salt thereof, polyaspartic acid or a salt thereof and polymaleic acid or a salt thereof, if necessary. Is water-soluble, it can be added as a powder or aqueous solution to an aqueous suspension containing the iron composite particle powder for purification treatment and stirred and mixed.

  Examples of the polymaleic acid include maleic anhydride, a polymer of maleic acid or a maleic anhydride, and a copolymer of maleic acid and another monomer (for example, an olefin / maleic acid copolymer). Polymerate salts such as sodium salts of polymers can also be used. As the polymaleic acid, for example, a polymer produced by a manufacturer such as Nippon Oil & Fat Co., Ltd. or BASF Japan Co., Ltd. can be used.

  Next, the purification method for soil, groundwater, and wastewater contaminated with the organic halogen compound according to the present invention 6 or 7 will be described.

  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. In the present invention, any method can be used, but the in-situ decomposition method is preferred.

  In the in-situ decomposition method, a method is adopted in which the iron composite particle powder for purification treatment or the purification agent is directly permeated or introduced into the basement through a borehole using a gas such as high-pressure air, 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.

  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.

  The purification method for wastewater contaminated with an organic halogen compound relates to a chemical treatment method for detoxifying heavy metals, organic halogen compounds and the like in organic wastewater and inorganic wastewater.

  As a chemical treatment method of wastewater, after receiving the wastewater in a storage tank, spraying the iron composite particle powder or purification agent for purification treatment, and then stirring and mixing so that the iron composite particle powder or purification agent for purification treatment is uniform , Use a method of standing or stirring, a method of packing and purifying iron composite particle powder for purification or a molded product thereof in a column in a circulation / filtration system pipe of a waste water tank, and continuously passing water through the column. Can do.

  The purification agent according to the present invention is preferably diluted so that the solid content concentration of the iron composite particles is 0.01 to 20% by weight when used for the purification treatment of soil and groundwater. In the present invention, sodium hydrogen carbonate, sodium sulfate, sodium carbonate, sodium sulfite, sodium hydrogen sulfite and the like may be added to the diluted purification agent in order to improve the permeability to soil.

  The addition amount of the purifying agent according to the present invention can be appropriately selected according to the concentration of the organic halogen compound in the soil, groundwater and wastewater, but is included in the soil when the organic halogen compound in the soil is targeted. The number of moles of α-Fe phase in the solid composite iron composite particle powder is preferably 1.5 times to 500 equivalents, more preferably 4 times to 200 times, relative to the number of moles of the organic chlorine compound. Double equivalent. When the amount is less than 1.5 times equivalent, the intended effect of the present invention cannot be obtained sufficiently. If it exceeds 500 times equivalent, the purification effect is improved but it is not economical. In addition, in the case of soil, it is preferable to inject so that the gap in the soil is replaced with a diluted cleaning agent, but the solid content concentration of the iron composite particle powder for purification treatment in the diluted cleaning agent at that time Is preferably 0.2 to 10 g / l, more preferably 0.3 to 5.0 g / l. When it is less than 0.2 g / l, the surface of the iron composite particles for purification treatment does not reach a reduced state capable of purifying the organic halogen compound due to the influence of dissolved oxygen in the diluted purification agent. If it exceeds 10 g / l, the purification effect is improved, but it is not economical.

  In addition, the amount of the purification agent added to the groundwater and wastewater is α- in the solid composite iron composite particle powder for purification of solids relative to the number of moles of chlorine in the organic chlorine compound contained in the groundwater and wastewater. The number of moles of Fe phase is preferably 1.5 to 500 equivalents, more preferably 4 to 200 equivalents. When the amount is less than 1.5 times equivalent, the intended effect of the present invention cannot be obtained sufficiently. If it exceeds 500 times equivalent, the purification effect is improved but it is not economical. Moreover, it is preferable to add so that the solid content density | concentration of the iron composite particle powder for purification processing in groundwater and wastewater may be 0.2-10 g / l, More preferably, it is 0.3-5.0 g / l. When it is less than 0.2 g / l, the surface of the iron composite particles for purification treatment does not reach a reduced state capable of purifying the organic halogen compound due to the influence of dissolved oxygen in the diluted purification agent. If it exceeds 10 g / l, the purification effect is improved, but it is not economical.

  In the present invention, the iron composite particle powder may be mixed into a slurry by mixing the iron composite particles and water immediately before the purification treatment, and the iron composite particles may be dispersed at the site of the purification treatment. An aqueous solution of Ni metal salt and / or Cu metal salt is added to and mixed with an aqueous suspension containing iron composite particles to obtain a slurry containing iron composite particles supporting Ni and / or Cu on the particle surface. Can do.

  In the present invention, at the site of the purification treatment, the iron composite particle powder is pulverized and slurried immediately before the purification treatment, so that the oxidation reaction between water and the iron composite particles during storage / storage and transportation to the purification site. Therefore, the deterioration of the properties of the iron composite particles is suppressed, and the permeability into the soil is further improved while maintaining the fine particles. And since it can be conveyed in the state of iron composite particle powder, a capacity | capacitance can be made small with respect to the case where it is made into a slurry, a storage place can also be made small, and a conveyance cost can also be reduced.

  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.

  As a pulverizer used in the present invention, in the case of using a medium, 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.

  Preferably, it is a device in which a plurality of slits are inserted in the outer periphery and a rotor and a stator in which shaft teeth are provided with cutter teeth are combined in a multistage manner, and the peripheral speed of the rotor is 10 m / s or more and is a mediumless line. A continuous shearing disperser such as a mixer can be used. For example, a foam-less mixer manufactured by Miki Co., Ltd. is particularly preferable.

  Moreover, preferably, 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, It is possible to use a media type dispersing machine such as a sand grind mill in which a rapid swirling action occurs in the medium, and a processed material passes through the medium from the bottom to the top. For example, an AD mill manufactured by Asada Iron Works is particularly preferable.

  Preferably, the inside of the short cylindrical pulverizing section is composed of a stirring rotor and a separator on the outer periphery, and the inside is filled with a medium of φ0.3 to φ1.0. A media-type disperser that can obtain uniform crushing and dispersion with a strong shearing force can be used. For example, SC-MILL manufactured by Nippon Coke Kogyo Co., Ltd. is particularly preferable.

  The concentration of the aqueous 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.

<Action>
The important point in the present invention is that the organic compound in the soil, groundwater and wastewater can be decomposed efficiently and economically by using the iron composite particle powder for purification treatment or the purification agent according to the present invention. is there.

  The present inventor has not yet clarified the reason why organic halogen compounds in soil, groundwater, and wastewater can be effectively decomposed, but estimates as follows.

That is, the decomposition mechanism of the organic halogen compound by the purification-treated iron composite particles according to the present invention is based on the analysis result of the reaction product, and the S surface of the particle shell layer (Fe ₃ O ₄ phase) becomes the active point. It is thought that the organic halogen compound such as trichlorethylene is adsorbed on the surface and the electrons generated by the reaction between the core layer (α-Fe phase) and water are supplied to promote dechlorination of the organic halogen compound. In this case, the presence of Ni and / or Cu, which are noble metals than iron, seems to promote the reaction between the α-Fe phase and water catalytically. In the reaction, electrons are supplied to S via Ni and / or Cu to thiolate, adsorb an organic halogen compound on the S surface, and then pass through intermediates such as ethanethiol and diethyl sulfide. It seems to dechlorinate.

  As described above, when a specific amount of S and Ni and / or Cu is contained in the iron composite particles for purification treatment, the synergistic effect significantly increases the decomposition performance with respect to the organic halogen compound, and it is extremely useful for soil, groundwater and wastewater. Decomposition reaction can occur even if a small amount is added. That is, in the case of conventional iron-based particles, a large excess amount of iron-based particles of several g / l or more must be added to groundwater and wastewater containing an organic halogen compound even if the concentration is low. In this case, a reducing atmosphere sufficient to cause the decomposition reaction could not be formed. On the other hand, when the iron composite particle powder for purification treatment according to the present invention is used, a sufficient reducing atmosphere can be formed with an addition amount of 0.2 g / l or more, and the organic halogen compound can be decomposed.

  In the present invention, the decomposition performance of the organic halogen compound can be improved by adding a specific amount of Al compound to the iron composite particle powder for purification treatment. The reason for this is not yet clear, but by containing Al, the primary particles can be made finer, and the strength of the aggregates of the iron composite particle powder becomes smaller than before, so wet grinding. Therefore, it is possible to pulverize more finely than when pulverizing in the same manner. As a result, the present inventor presumes that the iron composite particles can sufficiently exhibit the decomposition activity for the organic halogen compounds inherent in the iron composite particles because they can easily penetrate and disperse in soil or groundwater. .

  As described above, since the catalytic activity effect is high, it is possible to perform purification treatment efficiently and economically in a short period of time, and is particularly suitable for the purification of soil and groundwater contaminated with a high concentration of organic halogen compounds. .

  A typical embodiment of the present invention is as follows.

  The average major axis diameter and axial ratio of the goethite particle powder were measured with a transmission electron micrograph. The average particle diameter of the hematite particle powder and the iron composite particle powder was measured using a scanning electron micrograph.

  The Fe amount and the Al amount of the iron composite particle powder for purification treatment were measured using an “inductively coupled plasma emission spectroscopic analyzer SPS4000” (manufactured by Seiko Electronics Co., Ltd.).

  The S content of each particle powder was measured using “Carbon Sulfur Analyzer: EMIA-2200” (manufactured by HORIBA).

  The crystalline phase of each particle powder was identified by measuring in the range of 10 to 90 ° by X-ray diffraction.

As described above, the peak intensity ratio of the iron composite particle powder for purification treatment was determined by measuring the diffraction intensity D ₁₁₀ of the (110) plane of α-Fe and the diffraction intensity D ₃₁₁ of the (311) plane of magnetite from the result of X-ray diffraction. and _to determine the _{D 110 / (D 311 + D} 110) as the intensity ratio.

  The crystallite size (α-Fe (110) plane) of the iron composite particle powder for purification treatment is the size of the crystal particle measured by the X-ray diffraction method in the direction perpendicular to the crystal plane of each particle. It represents the thickness of the crystal grain, and is a value calculated from the diffraction peak curve for each crystal plane using the following Scherrer equation.

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).

  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.).

  The saturation magnetization value of the iron composite particle powder for purification treatment 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). .

<Evaluation of purification treatment of simulated groundwater and wastewater trichlorethylene>
<Making calibration curves for simulated groundwater and wastewater: Determination of trichlorethylene>
The concentration of trichlorethylene was prepared in advance according to the following procedure, and the concentration was calculated based on the obtained calibration curve.
Trichlorethylene (TCE: C ₂ HCl ₃ ): molecular weight 131.39
Reagent grade (99.5%), density (20 ° C.) 1.461 to 1.469 g / ml
Trichlorethylene is made into three levels of 0.05 μl, 0.1 μl and 1.0 μl, 30 ml of ion-exchanged water is added to 50 ml of a brown vial (actual volume 68 ml), then each amount of trichlorethylene is injected, and immediately a fluororesin liner Cover with a rubber stopper and tighten it with an aluminum seal. After leaving the vial at 20 ° C. for 20 minutes, 50 μl of the headspace gas 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.

<Sample preparation>
Put 0.075g or 0.15g of purification iron composite particles or a purification agent (equivalent to 0.075g or 0.15g of purification iron composite particles) into 50ml brown vial (actual volume 68ml), and add ion exchange water. Inject to 30 ml together with the amount of water in the cleaning agent, then add 1 μl of trichlorethylene, immediately cover with a rubber stopper with a fluororesin liner, and tightly fasten with an aluminum seal from above, and let it stand for reaction .

<Evaluation method>
The vial is left at 24 ° C. The remaining amount of trichlorethylene was allowed to stand at 20 ° C. for 20 minutes, and then 50 μl of gas was collected from the headspace with a syringe. The residual concentration of trichlorethylene in a predetermined time was measured using the “GC-MS-QP5050” (manufactured by Shimadzu Corporation) by batch method up to 500 hours for gas separation.

From the obtained residual concentration, an apparent reaction rate constant kobs was calculated based on the following formula.
ln (C / Co) = − k · t
Co: Initial concentration of trichlorethylene C: Residual concentration of trichlorethylene k: Apparent reaction rate constant (h ⁻¹ )
t: Time (h)

<Manufacture of iron composite particle powder 1 for purification treatment and purification agent 1>
Into a reaction vessel maintained in a non-oxidizing atmosphere by flowing N ₂ gas at a rate of 3.4 cm per second, 704 l of a 1.16 mol / l Na ₂ CO ₃ aqueous solution was added, and then Fe ²⁺ 1.35 mol / l. 296 l of ferrous sulfate aqueous solution containing l was added and mixed (the amount of Na ₂ CO ₃ corresponds to 2.0 times equivalent to Fe), and FeCO ₃ was produced at a temperature of 47 ° C.

In an aqueous solution containing FeCO ₃ obtained here, subsequently, while blowing _{N 2} gas at a rate per second 3.4cm, it was held 70 minutes at temperature 47 ° C., in an aqueous solution containing the FeCO _3, temperature 47 ° C. At 2.8 cm, air of 2.8 cm / second was aerated for 5.0 hours to generate goethite particles. The pH during air ventilation was 8.5 to 9.5.

To the suspension containing the goethite particles obtained here, 20 l of an aqueous solution of Al sulfate containing Al ³⁺ 0.3 mol / l was added, stirred well, then washed with a filter press, and the resulting press cake was compressed with a compression molding machine. It was extruded using a molding plate having a pore diameter of 4 mm and dried at 120 ° C. to obtain a granulated product of goethite particles.

The goethite particles contained in the granulated product thus obtained were 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. The BET specific surface area was 85 m ² / g, the Al content was 0.13% by weight, and the S content was 400 ppm.

  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 10 ml / kg and stirred. Thereafter, it was dehydrated into 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.

  The hematite particle powder constituting the granulated product obtained here was a spindle-shaped particle having an average major axis diameter of 0.24 μm and an axial ratio (major axis diameter / minor axis diameter) of 10.7. The S content was 3300 ppm.

1 kg of the granulated product of the hematite particle powder was introduced into a fixed bed reducing apparatus, and reduced to 450 ° C. for 180 minutes until it was completely α-Fe while aerated with H ₂ gas. Next, after switching to N ₂ gas and allowing it to cool to room temperature, 3 l of ion-exchanged water was directly introduced into the reduction furnace and taken out as it was as an aqueous suspension containing iron particle powder.

  The aqueous suspension was put into a continuous shearing disperser, a foam-less mixer (manufactured by Miki Co., Ltd.), dispersed at a peripheral speed of 21 m / s for 46 minutes, and an aqueous suspension 3 having a solid concentration of 21% by weight. .8 kg was obtained.

  This aqueous suspension was transferred to a stainless steel beaker equipped with a baffle, and 680 ml of a 0.1 mol / l nickel sulfate aqueous solution was added under blade stirring, and further stirred and mixed for 30 minutes, and then the supernatant liquid was transferred by decantation. It was washed with water until the degree became 100 μS / cm or less to obtain 3.2 kg of a purification agent having a solid content concentration of 25 wt% (referred to as purification agent 1).

  The iron composite particles contained in the resulting cleaning agent 1 were observed with a scanning electron microscope (30000 times). As a result, the primary particles had a rice grain shape and an average major axis diameter of 0.09 μm. The axial ratio was 1.4.

  Subsequently, it filtered, and it dried in air | atmosphere at 35 degreeC for 3 hours, and obtained the iron composite particle powder 1 for a purification process.

The obtained iron composite particle powder 1 is mainly composed of α-Fe, has a saturation magnetization value of 132 Am ² / kg (132 emu / g), a BET specific surface area of 27 m ² / g, a crystallite size of 295 mm, and an Fe content of The content was 82.9% by weight, the Al content was 0.22% by weight, the S content was 4000 ppm, and the Ni content was 0.5% by weight. As a result of X-ray diffraction, the intensity ratio D ₁₁₀ / (D ₁₁₀ + D ₃₁₁ ) between D _{110 of} α-Fe and D _{311 of} Fe ₃ O ₄ was 0.84.

<Evaluation results of purification treatment of simulated groundwater and wastewater trichlorethylene>
According to the evaluation method, the apparent reaction rate constant in the purification of trichlorethylene when 0.075 g (0.25 g / l) of the cleaning agent 1 was added was 0.020 h ⁻¹ .

<Manufacture of iron composite particle powder 2 for purification treatment and purification agent 2>
Into a reaction vessel maintained in a non-oxidizing atmosphere by flowing N ₂ gas at a rate of 3.4 cm per second, 704 l of a 1.16 mol / l Na ₂ CO ₃ aqueous solution was added, and then Fe ²⁺ 1.35 mol / l. 296 l of ferrous sulfate aqueous solution containing l was added and mixed (the amount of Na ₂ CO ₃ corresponds to 2.0 times equivalent to Fe), and FeCO ₃ was produced at a temperature of 47 ° C.

In an aqueous solution containing FeCO ₃ obtained here, subsequently, while blowing _{N 2} gas at a rate per second 3.4cm, it was held 70 minutes at temperature 47 ° C., in an aqueous solution containing the FeCO _3, temperature 47 ° C. At 2.8 cm, air of 2.8 cm / second was aerated for 5.0 hours to generate goethite particles. The pH during air ventilation was 8.5 to 9.5.

To the suspension containing the goethite particles obtained here, 20 l of an aqueous solution of Al sulfate containing Al ³⁺ 0.3 mol / l was added, stirred well, then washed with a filter press, and the resulting press cake was compressed with a compression molding machine. It was extruded using a molding plate having a pore diameter of 4 mm and dried at 120 ° C. to obtain a granulated product of goethite particles.

The goethite particles contained in the granulated product thus obtained were 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. The BET specific surface area was 85 m ² / g, the Al content was 0.13% by weight, and the S content was 400 ppm.

  The granulated product is heated at 330 ° C. to form hematite particles and dry pulverized. Thereafter, it was dehydrated into 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.

  The hematite particle powder constituting the granulated product obtained here was a spindle-shaped particle having an average major axis diameter of 0.24 μm and an axial ratio (major axis diameter / minor axis diameter) of 10.7. The S content was 440 ppm.

1 kg of the granulated product of the hematite particle powder was introduced into a fixed bed reducing apparatus, and reduced to 450 ° C. for 180 minutes until it was completely α-Fe while aerated with H ₂ gas. Next, after switching to N ₂ gas and allowing it to cool to room temperature, 3 l of ion-exchanged water was directly introduced into the reduction furnace and taken out as it was as an aqueous suspension containing iron particle powder.

  The aqueous suspension was put into a continuous shearing disperser, a foam-less mixer (manufactured by Miki Co., Ltd.), dispersed at a peripheral speed of 21 m / s for 46 minutes, and an aqueous suspension 3 having a solid concentration of 21% by weight. .8 kg was obtained.

  This aqueous suspension was transferred to a stainless steel beaker equipped with a baffle, and 680 ml of a 0.1 mol / l nickel sulfate aqueous solution was added under blade stirring, and further stirred and mixed for 30 minutes, and then the supernatant liquid was transferred by decantation. It was washed with water until the degree became 100 μS / cm or less to obtain 3.2 kg of a purification agent having a solid content concentration of 25% by weight (referred to as purification agent 2).

  The iron composite particles contained in the obtained cleaning agent 2 were observed with a scanning electron microscope (30000 times). As a result, the primary particles had a rice grain shape and an average major axis diameter of 0.10 μm. The axial ratio was 1.3.

  Subsequently, it filtered, and it dried in air | atmosphere at 35 degreeC for 3 hours, and obtained the iron composite particle powder 2 for a purification process.

The obtained iron composite particle powder 2 is mainly composed of α-Fe, a saturation magnetization value of 130 Am ² / kg (130 emu / g), a BET specific surface area of 26 m ² / g, a crystallite size of 298Å, and an Fe content of The content was 82.5 wt%, the Al content was 0.22 wt%, the S content was 530 ppm, and the Ni content was 0.5 wt%. As a result of X-ray diffraction, the intensity ratio D ₁₁₀ / (D ₁₁₀ + D ₃₁₁ ) between D _{110 of} α-Fe and D _{311 of} Fe ₃ O ₄ was 0.82.

<Evaluation results of purification treatment of simulated groundwater and wastewater trichlorethylene>
According to the evaluation method, the apparent reaction rate constant in trichlorethylene purification when the purification agent 2 was used was 0.005 h ⁻¹ .

<Manufacture of iron composite particle powder 3 for purification treatment and purification agent 3>
Into a reaction vessel maintained in a non-oxidizing atmosphere by flowing N ₂ gas at a rate of 3.4 cm per second, 704 l of a 1.16 mol / l Na ₂ CO ₃ aqueous solution was added, and then Fe ²⁺ 1.35 mol / l. 296 l of ferrous sulfate aqueous solution containing l was added and mixed (the amount of Na ₂ CO ₃ corresponds to 2.0 times equivalent to Fe), and FeCO ₃ was produced at a temperature of 47 ° C.

In an aqueous solution containing FeCO ₃ obtained here, subsequently, while blowing _{N 2} gas at a rate per second 3.4cm, it was held 70 minutes at temperature 47 ° C., in an aqueous solution containing the FeCO _3, temperature 47 ° C. At 2.8 cm, air of 2.8 cm / second was aerated for 5.0 hours to generate goethite particles. The pH during air ventilation was 8.5 to 9.5.

To the suspension containing the goethite particles obtained here, 20 l of an aqueous solution of Al sulfate containing Al ³⁺ 0.3 mol / l was added, stirred well, then washed with a filter press, and the resulting press cake was compressed with a compression molding machine. It was extruded using a molding plate having a pore diameter of 4 mm and dried at 120 ° C. to obtain a granulated product of goethite particles.

The goethite particles contained in the granulated product thus obtained were 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. The BET specific surface area was 85 m ² / g, the Al content was 0.13% by weight, and the S content was 400 ppm.

  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 10 ml / kg and stirred. Thereafter, it was dehydrated into 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.

  The hematite particle powder constituting the granulated product obtained here was a spindle-shaped particle having an average major axis diameter of 0.24 μm and an axial ratio (major axis diameter / minor axis diameter) of 10.7. The S content was 3300 ppm.

1 kg of the granulated product of the hematite particle powder was introduced into a fixed bed reducing apparatus, and reduced to 450 ° C. for 180 minutes until it was completely α-Fe while aerated with H ₂ gas. Next, after switching to N ₂ gas and allowing it to cool to room temperature, 3 l of ion-exchanged water was directly introduced into the reduction furnace and taken out as it was as an aqueous suspension containing iron particle powder.

  The aqueous suspension was put into a continuous shearing disperser, a foam-less mixer (manufactured by Miki Co., Ltd.), dispersed for 46 minutes at a peripheral speed of 21 m / s, and 3.8 kg of a cleaning agent having a solid content concentration of 21% by weight. (Referred to as purification agent 3).

  The iron composite particles contained in the obtained purification agent 3 were observed with a scanning electron microscope (30000 times). As a result, the primary particles had a rice grain shape and an average major axis diameter of 0.09 μm. The axial ratio was 1.4.

  Subsequently, it filtered, and it dried in air | atmosphere for 3 hours at 35 degreeC, and obtained the iron composite particle powder 3 for a purification process.

The obtained iron composite particle powder 3 is mainly composed of α-Fe, has a saturation magnetization value of 134 Am ² / kg (134 emu / g), a BET specific surface area of 27 m ² / g, a crystallite size of 295 mm, and an Fe content of The content was 83.0 wt%, the Al content was 0.22 wt%, and the S content was 4000 ppm. As a result of X-ray diffraction, the intensity ratio D ₁₁₀ / (D ₁₁₀ + D ₃₁₁ ) between D _{110 of} α-Fe and D _{311 of} Fe ₃ O ₄ was 0.84.

<Evaluation results of purification treatment of simulated groundwater and wastewater trichlorethylene>
According to the evaluation method, the apparent reaction rate constant in the purification of trichlorethylene when 0.075 g (0.25 g / l) of the purification agent 3 was added was 0.001 h ⁻¹ or less.

<Production of iron composite particle powder 4 and purification agent 4 for purification treatment>
12.8 l of ferrous sulfate aqueous solution containing Fe ²⁺ 1.50 mol / l and 30.2 l of 0.44N NaOH aqueous solution (corresponding to 0.35 equivalent to Fe ^{2+ in} ferrous sulfate aqueous solution). After mixing, a ferrous sulfate aqueous solution containing Fe (OH) ₂ was produced at pH 6.7 and a temperature of 38 ° C. Next, 130 l of air per minute was passed through a ferrous sulfate aqueous solution containing Fe (OH) ₂ at a temperature of 40 ° C. for 3.0 hours to generate goethite core particles.

The ferrous sulfate aqueous solution containing the goethite core particles (the amount of the goethite core particles corresponds to 35 mol% with respect to the produced goethite particles) was added to 7.0 l of 5.4N Na ₂ CO ₃ aqueous solution (residual ferrous sulfate). 1.5 equivalents of Fe ²⁺ in the aqueous iron solution) was added, and 130 liters of air was aerated for 4 hours at a pH of 9.4 and a temperature of 42 ° C. to produce goethite particle powder. 0.96 l of an aqueous solution of Al sulfate containing Al ³⁺ 0.3 mol / l was added to the suspension containing the goethite particles obtained here, and after sufficient stirring, the mixture was washed with a filter press and the resulting press cake was compressed. Extrusion molding was performed with a molding plate having a hole diameter of 4 mm using a molding machine and dried at 120 ° C. to obtain a granulated product of goethite particles.

The goethite particle powder contained in the granulated product thus obtained was a needle-like particle having an average major axis diameter of 0.33 μm and an axial ratio (major axis diameter / minor axis diameter) of 25.0. The BET specific surface area was 70 m ² / g, the Al content was 0.42% by weight, and the S content was 4000 ppm.

The granulated product was heated at 330 ° C. to obtain a granulated product of hematite particle powder 2. The hematite particle powder 1 constituting the obtained granulated product was a needle-like particle having an average major axis diameter of 0.25 μm and an axial ratio (major axis diameter / minor axis diameter) of 21.4. The S content was 4500 ppm.

1 kg of the granulated product of the hematite particle powder was introduced into a fixed bed reducing apparatus, and reduced to 450 ° C. for 180 minutes until it was completely α-Fe while aerated with H ₂ gas. Next, after switching to N ₂ gas and cooling to room temperature, switching to nitrogen gas and cooling to 90 ° C., then gradually increasing the oxygen partial pressure to form a stable oxide film on the particle surface at the same ratio as air The resulting iron composite particle powder 4 for purification treatment was obtained.

The iron composite particle powder obtained here is mainly composed of α-Fe, has a saturation magnetization value of 155 Am ² / kg (155 emu / g), a BET specific surface area of 20 m ² / g, a crystallite size of 298Å, and an Fe content of 85. 9% by weight, Al content was 0.68% by weight, and S content was 5500 ppm. As a result of X-ray diffraction, it was confirmed that α-Fe and Fe ₃ O ₄ were present. The intensity ratio D ₁₁₀ / (D ₁₁₀ + D ₃₁₁ ) between D ₁₁₀ (α-Fe) and D ₃₁₁ (Fe ₃ O ₄ ) was 0.88.

  1.0 kg of the iron composite particles 4 and 3.1 kg of water are placed in a media type dispersing machine SC-MILL (manufactured by Nippon Coke Co., Ltd.) and dispersed at a peripheral speed of 12 m / s (media φ0.5 zirconia beads) for 5 minutes. Then, an aqueous suspension containing iron composite particles having a solid content concentration of 24.4% by weight was obtained.

  This aqueous suspension was transferred to a stainless beaker equipped with a baffle, and 1 liter of 0.125 mol / l copper sulfate aqueous solution was added under blade stirring, and further stirred and mixed for 30 minutes, and then further 25% aqueous polymaleic acid solution ( By adding 680 g of Polystar OM manufactured by Nippon Oil & Fats Co., Ltd. and stirring with a blade for 10 minutes, a purification agent having a solid content concentration of 17% by weight was made 5.8 kg (referred to as a purification agent 4).

<Evaluation results of purification treatment of simulated groundwater and wastewater trichlorethylene>
According to the evaluation method, the apparent reaction rate constant in the purification of trichlorethylene when 0.075 g (0.25 g / l) of the cleaning agent 4 was added was 0.030 h ⁻¹ .

As described above, in the cleaning agents 1 and 2 using the iron composite particle powder supporting Ni and the cleaning agent 4 using the iron composite particle powder supporting Cu, the reaction rate constant is 0.002 h ⁻¹ or more, It was confirmed that the purification agent 3 that does not carry Ni and Cu is excellent in purification performance.

The iron composite particle powder for purification treatment according to the present invention can decompose organic halogen compounds efficiently and economically and is therefore suitable as a purification agent for soil and groundwater contaminated with organic halogen compounds.

Claims (7)

An iron composite particle powder composed of α-Fe and magnetite used for purification treatment of soil, groundwater, and wastewater contaminated with an organic halogen compound, and α-Fe (110) in the X-ray diffraction spectrum of the iron composite particle powder intensity ratio between the diffraction intensity _{D 311} of diffraction intensity _{D 110} and magnetite (311) plane of the surface _{(D 110 / (D 311 +} D 110)) is from 0.30 to .95, Al content is 0. Soil / groundwater / wastewater characterized by 10 to 1.50% by weight, S content of 3500 to 7000 ppm, and Ni and / or Cu content of 0.1 to 3.0% by weight Iron composite particle powder for purification treatment. 2. The iron composite particle powder for purification treatment of soil, groundwater, and wastewater according to claim 1, wherein Ni and / or Cu in the iron composite particle powder is coated and supported in a metallic state in the vicinity of the particle surface. The iron composite particle powder for purification treatment of soil, groundwater and wastewater according to claim 1 or 2, having an average particle size of 0.05 to 0.50 µm. A soil / groundwater / wastewater purification agent comprising a water suspension containing the iron composite particle powder for purification treatment of soil / groundwater / wastewater according to any one of claims 1 to 3 as an active ingredient. An iron composite particle powder for purification treatment of soil, groundwater and wastewater according to any one of claims 1 to 3, and one or more additives selected from polyacrylic acid, polymaleic acid, polyaspartic acid or salts thereof are effective. A soil, groundwater and wastewater purification agent consisting of a water suspension contained as an ingredient. Iron composite particle powder for purification treatment of soil, groundwater, wastewater according to any one of claims 1 to 3, or soil contaminated with a soil, groundwater, wastewater purification agent and organic halogen compound according to claim 4 or 5. A method for purifying soil, groundwater and wastewater, characterized by mixing and contacting groundwater and wastewater. Purification of soil / groundwater / wastewater characterized in that the soil / groundwater / wastewater purification agent according to claim 4 or 5 is directly injected into soil / groundwater contaminated with an organic halogen compound. Processing method.