• Journal of Soil and Groundwater Environment
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• v.15 no.4
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• pp.39-45
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• 2010

In order to treat paddy soils contaminated by Pb, Cd, and As near the abandoned mine, $H_2PO_4$ was used for stabilization of Pb ($PO_4$/Pb mole ratio of 2/1). In addition, $CaCO_3$ and $FeSO_4$ were used as stabilizers for treating Cd and As (2% w/w), respectively. Leaching tests were conducted with artificial rain in the column to assess the heavy metal stabilization efficiency. The mass of heavy metals in the effluents passed through the columns were analyzed. The remaining heavy metals in the soils were also analyzed as Korean soil standard method, phytoavailability test and sequential extraction test. Lead in the effluent was not detected when $H_2PO_4$ was used as a stabilizer. This result suggests that $H_2PO_4$ is efficient for Pb stabilization. In addition results of sequential extraction scheme suggest that heavy metals are present as residual forms which is not easily extracted.

• Journal of Magnetics
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• v.11 no.3
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• pp.126-129
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• 2006

The phosphate coating on the $(Fe_{0.97}Cr_{0.03})_{76}(Si_{0.5}B_{0.5})_{22}C_2$ amorphous powders with an average size of 10 ${\mu}m$ in diameter has been carried out in aqueous 1.0-2.0 wt% $H_3PO_4$ solutions, and the consolidation behavior and magnetic properties of their compressed powder cores has been investigated. The phosphate coating could provide efficient electrical insulation between amorphous powders and improved consolidation ability at room temperature. Especially when the powders were treated in more concentrated phosphoric acid solution, enhanced phosphate covering and higher frequency/dc-bias stability were achieved. The powder cores phosphate-coated in 2.0 wt% $H_3PO_4$ solution exhibited constant permeability of 21 up to 10 MHz, 110 of the quality factor at 0.9 MHz, 610 mW/cm3 core loss at 100 kHz/0.1 T and 89 of percent permeability at 100 kHz.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.341-353
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• 2000

The purpose of this study is to investigate the characteristics of pollutants overflow on storm events and the first flush analysis in industrial complex. Eight sub-basins in the Chongju industrial complex were selected for sampling and study with different characteristics during the period from June 1997 to August 1998. Water quality parameters of stormwater runoff such as $BOD_5$, COD, SS, TKN, $NO_3-N$, $PO_4-P$, TP, n-Hexane extracts, Cr, Cu, Pb and Fe were analyzed. During the storm events, measured concentration ranges of $BOD_5$, COD, SS, $NO_3-N$, TKN, $PO_4-P$, TP, r-Hexane extracts, Cr, Cu, Pb and Fe were 2~324 mg/L, 5~810 mg/L, 1~1,110 mg/L, 0.01~10.89 mg/L, 0.1~59.8 mg/L, 0.08~7.02 mg/L, 0.1~7.8 mg/L, 0.1~1,723.6 mg/L, 0.001~0.363 mg/L, 0.001~0.488 mg/L, 0.001~1.28 mg/L, and 0.26~18.91 mg/L, respectively in the industrial complex watersheds. And a quantitative of first flush has been presented. First flush occurs more frequently as the ratio of impervious area increases.

• Clean Technology
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• v.30 no.2
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• pp.105-112
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• 2024

Globally, the demand for electric vehicles has surged due to greenhouse gas regulations related to climate change, leading to an increase in the production of used batteries as a consequence of the battery life issue. This study aims to selectively leach and recover valuable metal lithium from the cathode material of spent LFP (LiFePO₄) batteries among lithium-ion batteries. Generally, the use of inorganic acids results in the emission of toxic gases or the generation of large quantities of wastewater, causing environmental issues. To address this, research is being conducted to leach lithium using organic acids and other leaching agents. In this study, selective leaching was performed using the organic acid methane sulfonic acid (MSA, CH₃SO₃H). Experiments were conducted to determine the optimal conditions for selectively leaching lithium by varying the MSA concentration, pulp density, and hydrogen peroxide dosage. The results of this study showed that lithium was leached at approximately 100%, while iron and phosphorus components were leached at about 1%, verifying the leaching efficiency and the leaching rates of the main components under different variables.

• Journal of the Mineralogical Society of Korea
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• v.15 no.3
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• pp.231-240
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• 2002

Microbial metal reduction influences the biogeochemical cycles of carbon and metals as well as plays an important role in the bioremediation of metals, radionuclides, and organic contaminants. The use of bacteria to facilitate the production of magnetite nanoparticles and the formation of carbonate minerals may provide new biotechnological processes for material synthesis and carbon sequestration. Metal-reducing bacteria were isolated from a variety of extreme environments, such as deep terrestrial subsurface, deep marine sediments, water near Hydrothemal vents, and alkaline ponds. Metal-reducing bacteria isolated from diverse extreme environments were able to reduce Fe(III), Mn(IV), Cr(VI), Co(III), and U(VI) using short chain fatty acids and/or hydrogen as the electron donors. These bacteria exhibited diverse mineral precipitation capabilities including the formation of magnetite ($Fe_3$$O_4$), siderite ($FeCO_3$), calcite ($CaCO_3$), rhodochrosite ($MnCO_3$), vivianite [$Fe_3$($PO_4$)$_2$ .$8H_2$O], and uraninite ($UO_2$). Geochemical and environmental factors such as atmospheres, chemical milieu, and species of bacteria affected the extent of Fe(III)-reduction as well as the mineralogy and morphology of the crystalline iron mineral phases. Thermophilic bacteria use amorphous Fe(III)-oxyhydroxide plus metals (Co, Cr, Ni) as an electron acceptor and organic carbon as an electron donor to synthesize metal-substituted magnetite. Metal reducing bacteria were capable of $CO_2$conversion Into sparingly soluble carbonate minerals, such as siderite and calcite using amorphous Fe(III)-oxyhydroxide or metal-rich fly ash. These results indicate that microbial Fe(III)-reduction may not only play important roles in iron and carbon biogeochemistry in natural environments, but also be potentially useful f3r the synthesis of submicron-sized ferromagnetic materials.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2698-2700
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• 2010

• Resources Recycling
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• v.19 no.3
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• pp.9-15
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• 2010

Domestic gold mine tailings, generally, contain a lot of non-metallic silica and clay minerals. These minerals can be separated from the tailings by various physical separation methods and used as raw materials for cements and ceramic products. In these physical separation procedures, metallic complex sulfides, in which Au and metallic constituents such as Pb, As and Fe were concentrated, were obtained as a by-product. These metallic constituents should be removed or separated from the by-product to extract Au efficiently. In this work, removal and separation processes of Pb, As, and Fe from the by-product were investigated. Pb was removed to under 3% by using alkaline oxidative leaching at the leaching condition of $120^{\circ}C$, 2M NaOH, 100psi $Po_2$, 250r.p.m., 4 wt.% solid and 30 min. leaching time. The leached residue was roasted and separated magnetically to obtain a non-magnetic product contained <0.2% As, <3% Fe and high concentrated Au more than 8,000 ppm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.244-250
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• 2020

β-Tricalcium phosphate (β-TCP, Ca3(PO4)2) is a kind of biodegradable calcium phosphate ceramics with chemical and mineral compositions similar to those of bone. It is a potential candidate for bone repair surgery. To improve the bioactivity and osteoinductivity of β-TCP, various ions doped calcium phosphate have been studied. Among them, Iron is a trace element and its deficiency in the human body causes various problems. In this study, we investigated the effect of Fe ions on the structural variation, degradation behavior of β-TCP. Fe-doped β-TCP powders were synthesized by the coprecipitation method, and the heat treatment temperature was set at 925 and 1100℃. The structural analysis was carried out by Rietveld refinement using the X-ray diffraction results. Fe ions existed in a different state (Fe2+ or Fe3+) with different heat treatment temperatures, and the substitution sites (Ca-(4) and Ca-(5)) also changed with temperature. The degradation rate was fastest at Fe-doped β-TCP with heated at 1100℃. The cell viability behavior was also enhanced with the substitution of Fe ions. Therefore, the substitution of Fe ion has accelerated the degradation of β-TCP and improved the biocompatibility. It could be more utilized in biomedical devices.

• KSBB Journal
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• v.11 no.5
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• pp.550-556
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• 1996

A complex medium was developed for the production of microbial cellulose by Acetobacter xylinum ATCC 23769. The optimum concentration of each nutrient for the production of microbial cellulose was determined to be 10g peptone, 20g yeast extract, 5g glucose, 1.56g Na2HPO4, 1.8g KH2PO4, 0.05g MgSO4, 0.002g FeCl3, 5g citric acid and 10 mL ethanol per liter. With synergistic effects of citric acid and ethanol, cellulose productivity achieved in developed medium was 0.446 gram of cellulose per gram glucose for static culture, which is much higher than reported values. Cell growth and the cellulose production in the developed medium under static culture was also investigated.

• 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)