Abstract: A method for producing hydrotalcite particles includes dissolving aluminum hydroxide in an alkaline solution to prepare an aluminate solution, causing a reaction of the aluminate solution prepared in the first step with carbon dioxide to precipitate a low-crystallinity aluminum compound, causing a first-order reaction by mixing the low-crystallinity aluminum compound with a magnesium compound to prepare a reactant containing hydrotalcite nuclear particles, and causing a hydrothermal reaction of the reactant to synthesize hydrotalcite particles. The hydrotalcite particles can impart excellent heat resistance, transparency, flowability, and are useful as a resin stabilizer.

Abstract: A method for producing hydrotalcite particles includes dissolving aluminum hydroxide in an alkaline solution to prepare an aluminate solution, causing a reaction of the aluminate solution prepared in the first step with carbon dioxide to precipitate a low-crystallinity aluminum compound, causing a first-order reaction by mixing the low-crystallinity aluminum compound with a magnesium compound to prepare a reactant containing hydrotalcite nuclear particles, and causing a hydrothermal reaction of the reactant to synthesize hydrotalcite particles. The hydrotalcite particles can impart excellent heat resistance, transparency, flowability, and are useful as a resin stabilizer.

Abstract: Iron composite particles for purifying soil or ground water, comprise ?-Fe and magnetite, and having a ratio of a diffraction intensity D110 of (110) plane of ?-Fe to a sum of a diffraction intensity D311 of (311) plane of magnetite and the diffraction intensity D110 (D110/(D311+D110)) of 0.30 to 0.95 as measured from X-ray diffraction spectrum of the iron composite particles, an Al content of 0.10 to 1.50% by weight and an S content of 3500 to 7000 ppm; a process for producing the iron composite particles; a purifying agent containing the iron composite particles; a process for producing the purifying agent; and a method for purifying soil or ground water.

Abstract: Iron composite particles for purifying soil or ground water, comprise ?-Fe and magnetite, and having a ratio of a diffraction intensity D110 of (110) plane of ?-Fe to a sum of a diffraction intensity D311 of (311) plane of magnetite and the diffraction intensity D110 (D110/(D311+D110)) of 0.30 to as measured from X-ray diffraction spectrum of the iron composite particles, an Al content of 0.10 to 1.50% by weight and an S content of 3500 to 7000 ppm; a process for producing the iron composite particles; a purifying agent containing the iron composite particles; a process for producing the purifying agent; and a method for purifying soil or ground water.

Abstract: A purifying agent for purifying soil or ground water which comprises a water suspension containing iron composite particles comprising ?-Fe and magnetite, and having an average particle diameter of 0.05 to 0.50 ?m, an S content of 3500 to 10000 ppm and an Al content of 0.10 to 1.50% by weight, and polyaspartic acid or a salt thereof. The purifying agent is capable of decomposing aliphatic organohalogen compounds or aromatic organohalogen compounds contained in the soil or ground water in an efficient, continuous and economical manner.

Abstract: A purifying agent for purifying soil or ground water which comprises a water suspension containing iron composite particles comprising ?-Fe and magnetite, and having an average particle diameter of 0.05 to 0.50 ?m, an S content of 3500 to 10000 ppm and an Al content of 0.10 to 1.50% by weight, and polyaspartic acid or a salt thereof. The purifying agent is capable of decomposing aliphatic organohalogen compounds or aromatic organohalogen compounds contained in the soil or ground water in an efficient, continuous and economical manner.

Abstract: Iron particles for purifying soil or ground water of the present invention comprise a mixed phase of ?-Fe phase and Fe3O4 phase, and having a BET specific surface area of 5 to 60 m2/g, an Fe content of not less than 75% by weight based on the weight of the iron particles and a sulfur content of not less than 1,000 ppm. The iron particles are capable of decomposing or insolubilizing harmful substances such as organohalogen compounds and/or heavy metals, cyanogen, etc. contained in the soil or ground water in efficient, continuous and economical manners.

Abstract: Iron particles for purifying soil or ground water of the present invention comprise a mixed phase of ?-Fe phase and Fe3O4 phase, and having a BET specific surface area of 5 to 60 m2/g, an Fe content of not less than 75% by weight based on the weight of the iron particles and a sulfur content of not less than 1,000 ppm. The iron particles are capable of decomposing or insolubilizing harmful substances such as organohalogen compounds and/or heavy metals, cyanogen, etc. contained in the soil or ground water in efficient, continuous and economical manners.

Abstract: Iron composite particles for purifying soil or ground water, comprise ?-Fe and magnetite, and having a ratio of a diffraction intensity D110 of (110) plane of ?-Fe to a sum of a diffraction intensity D311 of (311) plane of magnetite and the diffraction intensity D110 (D110/(D311+D110)) of 0.30 to 0.95 as measured from X-ray diffraction spectrum of the iron composite particles, an Al content of 0.10 to 1.50% by weight and an S content of 3500 to 7000 ppm; a process for producing the iron composite particles; a purifying agent containing the iron composite particles; a process for producing the purifying agent; and a method for purifying soil or ground water.

Abstract: A purifying agent for purifying soil or ground water which comprises a water suspension containing iron composite particles comprising ?-Fe and magnetite, and having an average particle diameter of 0.05 to 0.50 ?m, an S content of 3500 to 10000 ppm and an Al content of 0.10 to 1.50% by weight, and polyaspartic acid or a salt thereof. The purifying agent is capable of decomposing aliphatic organohalogen compounds or aromatic organohalogen compounds contained in the soil or ground water in an efficient, continuous and economical manner.

Abstract: Iron composite particles for purifying soil or ground water, comprise an iron component, at least one noble metal selected from the group consisting of ruthenium, rhodium and palladium, and carbon or aluminum, and having a noble metal content of 0.01 to 5.00% by weight and a particle diameter of 0.01 to 1.0 ?m. The iron composite particles and the purifying agent according to the present invention are capable of decomposing aliphatic organohalogen compounds such as dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, tetrachloroethylene, 1,3-dichloropropene or the like, and aromatic organohalogen compounds such as dioxins, PCB (polychlorinated biphenyl) or the like, which are contained in soil, ground water or waste water, at ordinary temperature in an efficient and economical manner.

Abstract: A purifying agent for purifying soil or ground water of the present invention comprises a water suspension containing iron composite particles comprising ?-Fe and magnetite, and having an average particle diameter of 0.05 to 0.50 ?m, an S content of 3500 to 10000 ppm and an Al content of 0.10 to 1.50% by weight, and at least one additive selected from the group consisting of polymaleic acid, salts of polymaleic acid, sodium hydrogencarbonate and sodium sulfate. The purifying agent of the present invention is capable of decomposing aliphatic organohalogen compounds or aromatic organohalogen compounds contained in soil or ground water in an efficient, continuous and economical manner.

Abstract: Iron particles for purifying soil or ground water of the present invention comprise a mixed phase of ?-Fe phase and Fe3O4 phase, and having a BET specific surface area of 5 to 60 m2/g, an Fe content of not less than 75% by weight based on the weight of the iron particles and a sulfur content of not less than 1,000 ppm. The iron particles are capable of decomposing or insolubilizing harmful substances such as organohalogen compounds and/or heavy metals, cyanogen, etc. contained in the soil or ground water in efficient, continuous and economical manners.

Abstract: Iron particles for purifying soil or ground water of the present invention comprise a mixed phase of &agr;-Fe phase and Fe3O4 phase, and having a BET specific surface area of 5 to 60 m2/g, an Fe content of not less than 75% by weight based on the weight of the iron particles and a sulfur content of not less than 1,000 ppm. The iron particles are capable of decomposing or insolubilizing harmful substances such as organohalogen compounds and/or heavy metals, cyanogen, etc. contained in the soil or ground water in efficient, continuous and economical manners.