• 한국전기화학회:학술대회논문집
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• 2005.07a
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• pp.63-66
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• 2005

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.191-192
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• 2008

본 연구에서는 침수식물이 습지의 생지화학적 환경에 미치는 영향을 조사하고자 하였다. 침수식물이 없는 대조군보다 침수식물이 밀생한 습지반응조에서 수체내 용존산소의 농도 변화와 pH가 크게 나타나, 침수식물이 습지에서 수체와 저질의 산화-환원조건을 변화시켜, 질산화나 탈질과 관련된 습지의 생지화학적 반응에 영향을 줄 수 있음을 보여주었다.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.537-541
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• 2010

Pt-Sn with various ratios was supported on carbon black after pretreatment in an acidic solution by a reduction method. The Pt/Sn ratio was controlled by varying the concentration of each component in the solution, and the influence of the composition on the electrocatalytic activities was investigated. The crystallinity of the synthesized materials was investigated by XRD (X-ray Diffraction), and the oxidation states of both the platinum and tin were determined by XPS (X-ray Photoelectron Spectroscopy). SEM (Scanning Electron Microscopy)-EDS (Energy Dispersive Spectroscopy) was utilized to examine the morphology and composition of the synthesized electrode, and the particle size of the Pt-Sn was analyzed by TEM (Transmission Electron Microscopy). The electrocatalytic activity for oxygen reduction was evaluated in a 0.5 M $H_2SO_4$ solution using a rotating disk electrode system. The activity and stability were found to be strongly dependent on the electrode composition (Pt/Sn ratio). The catalytic activity and stability for methanol oxidation were also measured using cyclic voltammetry (CV) in a mixture of 0.5 M $H_2SO_4$ and 0.5 M $CH_3OH$ aqueous solution. The addition of proper amount of Sn was found to significantly improve both catalytic activity and stability for methanol oxidation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.33-39
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• 2010

The electrolytic reduction of a spent oxide fuel involves a liberation of the oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. Accordingly, it is essential to choose the optimum material for the processing equipment that handles the high molten salt. In this study, hot corrosion studies were performed on bare as well as coated superalloy specimens after exposure to lithium molten salt at $675^{\circ}C$ for 216 h under an oxidizing atmosphere. The IN713LC superalloy specimens were sprayed with an aluminized NiCrAlY bond coat and then with an $Y_2O_3$ top coat. The bare superalloy reveals an obvious weight loss due to spalling of the scale by the rapid scale growth and thermal stress. The chemical and thermal stability of the top coat has been found to be beneficial for increasing to the corrosion resistance of the structural materials for handling high temperature lithium molten salts.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1125-1131
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• 1996

Ca or Sr-doped $PrMnO_3$ were prepared for cathode material of solid oxide fuel cell. The characteristics such as the electrical conductivity and the cathodic overpotential were investigated as to doping contents. Also the reactivity with yttria stabilized zirconia of electrolyte, and the thermal expansion coefficient were studied. The prepared perovskite powder had the mean particle size of $2{\sim}5{\mu}m$, and the particle size and the surface area was out of relation to the doping content. When Ca doping amount of electrode material was 30mol%, the electrical conductivity was the highest value of $266S{\cdot}cm^{-1}$ at $1000^{\circ}C$, and also the polarization characteristics showed the best property. The reactivity between YSZ and Ca-doped $PrMnO_3$ at $1200^{\circ}C$ for 100hours was lower than that between YSZ and Sr-doped $PrMnO_3$. The thermal expansion coefficient of $Pr_{0.7}Ca_{0.3}MnO_3$ was $1.19{\times}10^{-5}K^{-1}$ in the temperature range of $300{\sim}1000^{\circ}C$, and this value was similar to that of YSZ, $1.15{\times}10^{-5}K^{-1}$.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.145-153
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• 2005

I reviewed an ecological and environmental significance of microbial carbon respiration coupled to dis-similatory reduction of fe(III) to Fe(II) which is one of the major processes controlling mineralization of organic matter and behavior of metals and nutrients in various anaerobic environments. Relative significance of Fe(III) reduction in the mineralization of organic matter in diverse marine environments appeared to be extremely variable, ranging from negligible up to $100\%$. Cenerally, Fe(III) reduction dominated anaerobic car-bon mineralization when concentrations of reactive Fe(III) were higher, indicating that availability of reactive Fe(III) was a major factor determining the relative significance of Fe(III) reduction in anaerobic carbon mineralization. In anaerobic coastal sediments where $O_2$ supply is limited, tidal flushing, bioturbation and vegetation were most likely responsible for regulating the availability of Fe(III) for Fe(III) reducing bacteria (FeRB). Capabilities of FeRB in mineralization of organic matter and conversion of metals implied that FeRB may function as a useful eco-technological tool for the bioremediation of anoxic coastal environments contaminated by toxic organic and metal pollutants.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.751-755
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• 2005

Carbon dioxide, included in the flue gas from the combustion of fossil fuel, was known as a representative green house gas and various removal and utilization technologies of it has been studied for the prevention of global warming. This study was performed as an effort to find out a method to reuse carbon dioxide separated from flue gas by magnetite powder. Magnetite powder was synthesized using various oxidizers and alkalinity controlled aqueous solutions of $FeSO_4{\cdot}7H_2O$ and NaOH at 50, 80, 90, $100^{\circ}C$ and analyzed by XRD and SEM. The analysis results showed that magnetite powder synthesized at higher alkalinity and temperature had crystalline spinel and cubic structure. The reduction by hydrogen and the oxidation by carbon dioxide of synthesized powder were studied by TGA. The results showed that magnetite powder synthesized at low alkalinity and temperature was non-cubical amorphous but crystalline and cubical at high alkalinity and temperature. Comparing magnetite powders synthesized using oxidants(air and oxygen) and nitrogen, magnetite powder using more oxygen containing oxidant synthesized more crystalline magnetite powder. The experimental results of redox reaction of the synthesized magnetite powder showed that the reduction by hydrogen and the oxidation by carbon dioxide were seldom observed below $400^{\circ}C$ and observed well at $500^{\circ}C$. Magnetite powder synthesized at $100^{\circ}C$ and alkalinity(molal concentration ratio of $FeSO_4{\cdot}7H_2O$ to NaOH) of 2.0 using $O_2$ showed the highest reduction of 27.15 wt％ and oxidation of 26.73 wt％, especially at reaction temperature of $500^{\circ}C$.

• Clean Technology
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• v.21 no.4
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• pp.248-256
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• 2015

MnO₂ was prepared by a hydrothermal process method in the range of 120-200 ℃ and 0.5-5 h, calcined at 300 ℃ after induction of precipitation using KMnO₄ and MnCl₂･4H₂O, and its catalytic activity was compared for CO oxidation. The catalysts were characterized using by X-ray diffraction, N₂-sorption, scanning electron microscopy, and temperature programmed reduction of H₂ or CO. The crystalline structure of pure α-MnO₂ or hybrid α/β-MnO₂ was controlled by the preparation conditions. The pure α-MnO₂ showed better catalytic activity and thermal stability than hybrid α/β-MnO₂. Especially, α-MnO₂ prepared at 150 ℃ for 1 h has the highest specific surface area 214 m² g^-1, reducibility and labile lattice oxygen species analyzed by H₂, CO-TPR, respectively. It also showed the best CO oxidation activity in both conditions of temperature programmed and isothermal reaction. The results came from the physicochemical properties of catalysts like the crystalline structure, specific surface area, reducibility and lattice oxygen species, and which are correlated with catalytic performance.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.305-311
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• 2007

Based on the cyclic voltammograms, potentiodynamic polarizations, transient and steady state Tafel plots and electrochemical impedence spectroscopy, we proposed the copper redox mechanism of the corrosion and passivation in artificial sea water. The copper redox mechanism showed the dependence of the concentration of oxygen in artificial sea water and electrode potentials.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.99-102
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• 2002

전기분해에 의한 부상현상을 이용하여 토양세정 후 발생되는 유출수 중의 유수를 분리하기 위한 적정 운전조건에 관하여 고찰하였다. 전압에 의한 유수분리 효율을 관찰한 결과, 전기분해 1시간 후 3V의 전압만으로도 88% 정도의 제거율을 나타내었으며 6V 이상의 전압에서는 90% 정도로 거의 비슷한 제거율을 나타내어 대부분의 에멀젼이 분리됨을 확인할 수 있었다. 동일조건에서는 전기분해 시간이 경과될 수록 분리효율이 향상되었으며, 전극 간격이 넓어질수록 같은 효율을 얻기 위해 소요되는 전압의 크기가 커짐을 알 수 있었다. 전기분해 시 양극에서는 OH$^{-}$의 방전으로 발생되는 산소에 의해 산화반응이 일어나며, 음극에서는 H$^{+}$가 방전되어 발생되는 수소에 의해 환원반응이 일어나며 미세한 기포가 형성된다. 유분의 부상분리 현상은 유분의 (-)charge와 전기분해에 의해서 발생되는 양이온의 결합으로 인한 중화반응 및 음극에서 발생되는 미세 수소기포로 인만 부상분리가 대부분을 차지하며, 전압 및 전기분해 시간이 증가하고 전극 간격이 좁을수록 음극에서 발생되는 미세기포의 양이 증가되어 부상효과가 크게 나타나는 것으로 판단된다. 전극 종류는 구리 > 알루미늄 > 철 > 티타늄 순으로 효율을 나타내었으며, 이는 양극으로 사용된 이러한 금속들의 전기전도도 차이에 의해 일어나는 현상으로 판단된다