• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.160-161
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• 2006

Seasonal changes have been recognized in particle characteristics and forming characteristics of iron powder with insulated coating for a compacted magnetic core because of its high hygroscopicity, due to its phosphate coating and resin binder additives. For this reason, particle characteristics and molding characteristics of the powder with diverse water absorbtivity have been studied. The result shows that the higher the volume of absorbed water, the worse the fluidity becomes, resulting in the reduction in both springback during the molding process and expansion reduction after the heat treatment. The requirement on dimension accuracy for the finished product can be satisfied with an additional drying process on the material powder, which contributes to maintain its water volume constant.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.236-236
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• 2003

Anaerobic Fe(III)-reducing bacteria are known to be able to reduce crystalline and amorphous Fe(III) oxides. Anaerobic Fe(III)-reducing bacterial reduction can induce several kinds of secondary minerals (Fe(II) containing minerals) such as magnetite, siderite, vivianite [($Fe_{3}(PO_{4}{\cdot}2H_{2}O$], and iron sulfide (FeS) according to variety of geochemical and biological conditions. (omitted)

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.118-121
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• 2002

The kinetics and stoichiometry of the reduction of hexavalent chromium (Cr(Ⅵ)) with ferrous iron (Fe(II)) were examined in systems with and without aquifer solids. Cr(Ⅵ) reduction was rapid in the absence of solids, but demonstrated slower and more complex kinetics in the presence of aquifer solids. The aquifer solids removed Fe(II) from solution and a portion of the reducing capacity of Fe(II) was transferred to the aquifer solids. The solid phases were then able to continue to remove Cr(Ⅵ). This suggests in-situ treatment of Cr(Ⅵ) by Fe(II) injection would be feasible in the aquifer environment. In general, re-oxidation of reduced chromium by molecular oxygen was not observed in our systems over time periods of nearly one year.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.49-52
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• 2007

We investigated hydrogen storage and production properties using redox system of iron oxide($Fe_{3}O_{4}$ + $4H_{2}$ ${\leftrightarrows}$ 3Fe + $4H_{2}O$) modified with rhodium, ceria and zirconia under atmospheric pressure. Reduction of iron oxide with hydrogen(hydrogen storage) and re-oxidation of reduced iron oxide with steam(hydrogen evolution) was carried out using a temperature programmed reaction(TPR) technique. On the temperature programmed studies, the effects of amounts of cerium and zirconium on the re-oxidation rate of partial reduced iron oxides were increased with increasing metal additives amount, but the rhodium amount showed little effect on the re-oxidation rate. On the thermal studies, the re-oxidation rates were enhanced with increasing temperature(300 $^{\circ}C$ < 350 $^{\circ}C$).

• Journal of the Korean Ceramic Society
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• v.23 no.2
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• pp.31-37
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• 1986

The effect of dehydration temperature on the reduction process of silica-coated hematite was invest-igated The particle shape and magnetic properties of the products reduced from hematite at various conditions and the oxidation resistance of silica-coated iron powder were examined. It was revealed that single phase iron powder obtained over 45$0^{\circ}C$ had good magnetic properties. The iron powder manufactured between 45$0^{\circ}C$ and 50$0^{\circ}C$ displayed the maximum coercive force as a result of maintaining its acicular shaped. However the coercive force of iron powder reduced over 50$0^{\circ}C$ was decreased. The oxidation resistance of silica-coated iron powder in air was very good up to 11$0^{\circ}C$ and for 12 days.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.67-70
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• 2002

Remediation of groundwater contaminated with chlorinated organics, nitro aromatics, and heavy metals using zero valent iron (ZVI) filings has paid considerable attention in recent years. When the contaminants of high concentration leaked abundantly in subsurface environment, permeable reactive barrier technology using iron filing is taken a long time for the remediation of contaminated groundwater, The problem of contaminant shock is able to be solved using surfactant (hexadecyltrimethylammonium, HDTMA) modified bentonite (SMB) as immobilizing material. Therefore, the purpose of this research was to develop the combined remediation technology using conventional permeable reactive and immobilizing barrier for the enhanced decontamination of chlorinated compounds. Four column experiments were conducted to assess the performance of the mixed reactive materials with Ottawa sand, iron filing, and HDTMA-bentonite for trichloroethylene (TCE) removal under controlled groundwater flow conditions. TCE reduction rates with sand/iron filing/HDTMA-bentonite were highest among four column due to dechlorination of TCE by iron filing and sorption of TCE by SMB.

• Korean Journal of Veterinary Research
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• v.24 no.1
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• pp.24-30
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• 1984

The protective effects of high levels of dietary iron, copper, zinc or protein on lead toxicity were studied In chicks. Growth retardation, reduction of feed intake, anemia and accumulation of lead in the bone and kidney were observed in chicks fed a diet containing 500mg lead as chloride per kg of feed for 42 days. Early changes due to ingested lead were inhibition of red blood cell ${\delta}$-aminolevulinic acid dehydrase at all doses and no effect of iron, copper, zinc or protein addition were observed. Tibia lead accumulation was reduced in chicks receiving additional dietary iron or zinc compared to the lead only group but increased in chicks given supplementary protein. Decreased body weight gain was overcome by supplementary zinc or protein in chicks fed lead but not by supplementary iron. Overall the results of this study show that lead poisoning can be partly reduced by providing supplementary iron, zinc or protein, but the interaction of these element remained to be elucidated.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.81-84
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• 1999

The aqueous geochemical characteristics of Cr(III) and Cr(Ⅵ) in environmental systems are very different from one another: Cr(Ⅵ) is highly soluble, mobile and toxic relative to Cr(III) Reduction of Cr(Ⅵ) to Cr(III) are beneficial in aquatic systems because of the transformation of a highly mobile and toxic species to one having a low solubility in water, thus simultaneously decreasing chromium mobility and toxicity. Fe(II) species are excellent reductants for transforming Cr(Ⅵ) to Cr(III), and in addition, keeping Cr(III) concentrations below the drinking water standard of 52 ppb at pH values between 5 and 11. Investigations of the effects of NOM on Cr(Ⅵ) reduction are for examining the feasibility of using ferrous iron to reduce hexavalent chromium in subsurface environments. Experiments in the presence of soils, however, showed that the solid phase consumes some of the reducing capacity of Fe(II) and makes the overall reduction kinetics slower. The soil components bring about consumption of the ferrous iron reductant. Particular attention is devoted to the complexation of Fe(II) by NOM and the subsequent effect on Cr(Ⅵ) reduction. Cr(Ⅵ) reduction rate by Fe(II) was affected by the presence of NOM (humic acid), The effects of humic acid was different from the solution pH values and the concentration of humic acid. It was probably due to the reactions between humic acid and Cr(Ⅵ), humic acid and Fe(II), and between Cr(Ⅵ) and Fe(II), at each pH.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.217-224
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• 2011

Removal of dissolved selenium by D. michiganensis, a iron-reducing bacterium, and effects of dissolved metal elements such as iron, sulfate, and copper were investigated. Selenide that was reduced from selenite (2 mM) by D. michiganensis was gradually removed from the aqueous medium. As the reduced selenide was combined with aqueous iron, it was precipitated as a nanoparticulate iron-selenide. Sulfate and copper negatively affected the microbial selenite reduction, and the copper was especially toxic to the bacterium, inhibiting a microbial removal of dissolved selenite. These results show that it should be carefully biotreated for a selenium-contaminated site considering in situ sulfate or copper distribution and concentration. Consequently, the formation of iron-selenide by bacteria will be an important measure for preventing a long-distance migration of selenium in the subsurface environments.

• Analytical Science and Technology
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• v.23 no.6
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• pp.560-565
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• 2010

Perchlorate ion ($ClO_4^-$) has been widely used as oxidizing agent in military weapon system such as rocket and missile fuel propellant. So it has been challenging to remove the pollutant of perchlorate ion. nanoscale zero valence iron (nZVI) particles are widely employing reduction catalyst for decomposition of perchlorate ion. nZVI particles has increasingly been utilized in groundwater purification and waste water treatment. But it have strong tendency of aggregation, rapid sedimentation and limited mobility. In this study, we focused on reduction of perchlorate ion using nZVI particles immobilized in alginate polymer bead for stabilization. The stabilized nZVI particles displayed much greater surface area, and much faster reaction rates of reduction of perchlorate ion. In this study, an efficient way to immobilize nZVI particles in a support material, alginate bead, was developed by using $Ca^{2+}$ as the cross-linking cations. The efficiency and reusability of the immobilized Fe-alginate beads on the reduction of perchlorate was tested at various temperature conditions.