• 청정기술
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• 제24권1호
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• pp.35-40
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• 2018

$N_2O$ 촉매 분해 반응을 위한 $Co_3O_4$ 촉매는 공침법을 이용하여 제조하였으며, 조촉매로서 Ce 및 Zr의 양을 (Ce 또는 Zr)/Co = 0.05의 몰비로 고정하여 제조하였다. 또한 K가 촉매에 미치는 영향을 조사하기 위해 1 wt%의 $K_2CO_3$를 함침하여 촉매를 제조하였다. 제조된 촉매의 특성은 BET, SEM, XRD, $H_2-TPR$, XPS를 통해 분석하였다. $Co_3O_4$ 촉매는 스피넬 결정상을 나타냈으며, 조촉매의 첨가는 입자 크기와 결정 크기를 감소시켜 비표면적을 증가시키는 것으로 나타났다. K의 도핑은 촉매 활성 물질인 Co의 활성 종인 $Co^{2+}$의 농도를 증가시켜 촉매 활성을 향상시키는 것으로 확인되었다. $N_2O$ 분해 반응 테스트는 $GHSV=45,000h^{-1}$, $250{\sim}375^{\circ}C$에서 수행되었으며 $Co_3O_4$ 촉매에 조촉매를 첨가하였을 때도 반응성이 증가하였지만, K를 함침하면 활성이 더욱 크게 증가하는 것으로 나타났다. K의 도핑이 활성 종인 $Co^{2+}$의 농도를 증가시키며, 환원온도를 낮춰 주어 활성에 큰 영향을 주는 것으로 확인하였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.318-321
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• 2003

This study explored the feasibility of applying Electrokinetic-Fenton process(EK-Fenton process) to remediation of contaminant sorbed on the soil possessed low-permeability. The addition of 0.01 N H$_2$SO$_4$ in the anode reservoir for the $H_2O$$_2$stabilization improved the stabilization of $H_2O$$_2$and the treatment effect of phenanthrene across the entire soil specimen. The use of $H_2O$$_2$and dilute acid as anode purging solution is a promising method treating of HOCs in low-permeability subsurface environments.

• 공업화학
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• 제32권6호
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• pp.599-606
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• 2021

본 연구는 질소산화물 제거를 위하여 암모니아를 환원제로 사용하는 선택적 촉매 환원법에 있어 지지체에 셀레늄을 첨가하여 300 ℃ 이하에서 V₂O₅/WO₃/TiO₂의 반응 활성을 증진시키기 위한 실험 및 반응특성 연구를 수행하였다. 졸-겔법으로 Se-TiO₂ 및 TiO₂를 합성하였으며, 이를 지지체로 하여 V₂O₅/WO₃/TiO₂ 및 V₂O₅/WO₃/Se-TiO₂ 촉매를 제조하여 상용 촉매와 반응 활성을 비교하였다. 실험 결과, 졸-겔법으로 합성한 TiO₂를 사용한 촉매의 탈질 효율이 상용 TiO₂를 사용하여 제조한 촉매보다 낮은 결과를 보였으나 셀레늄을 첨가함에 따라 탈질 효율이 증진되었다. 따라서 BET, XRD, Raman, H₂-TPR 및 FT-IR분석을 통하여 셀레늄의 첨가가 촉매의 구조에 미치는 영향을 분석하였으며 셀레늄 첨가에 의한 비표면적의 증가와 단량체 및 복합체 바나듐 종의 형성이 반응 특성에 미치는 영향을 확인하였다.

• 한국식품저장유통학회지
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• 제10권3호
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• pp.421-426
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• 2003

도체표면에서 분리한 E. coli O157;H7 CDF1, A. sobria CDF3, S. aureus CDF2의 성장을 억제하기 위한 방안을 검토하였다. E. coli O157:H7 CDF1와 A. sobria CDF3는 NaCl 4% 이상 농도에서 성장이 억제된 반면 lactic acid 0.1%는 성장에 영향을 미치지 않았다. S. aureus CDF2은 NaCl 농도 4%에 의해 성장이 뚜렷하게 억제되지 않았으나 lactic acid 0.1% 첨가에 의해 뚜렷히 억제되었다. E. coli O157:H7 CDF1은 분쇄육에서 4$^{\circ}C$와 1$0^{\circ}C$에서 10일간 저장하는 동안 저장온도별 약 1 log 차이를 나타내었고,1. sobria CDF3의 성장은 저장온도에 따른 차이는 나타나지 않았다. 6$0^{\circ}C$에서 10분 열처리 후 E. coli O157:H7 CDF1, A. sobria CDF3가 거의 사멸하였으나 S. aureu CDF2는 대조구에 비해 1 log cycle 이하의 감소현상을 나타내었다. 감잎, 뽕잎, 녹차, 우롱차의 추출물중 E. coli O157:H7 CDF1, A. sobria CDF3와 S. auren CDF2에 대한 항균활성을 나타낸 우롱차 추출물 0.1%와 0.3% 첨가에 의해 표. coli O157:H7 CDF1는 성장 억제되지 않았으나 0.5% 첨가구의 경우 약 2 log 감소하였다. A. sobria CDF3와 S. aureus CDF2는 추출물 0.1%와 0.3% 첨가에 의해 성장이 억제되었으며 0.5%첨가에 의해 배양 12 시간이후 생균수는 검출되지 않았다. 우롱차 추출물을 분쇄육에 0.3%와 0.5%를 첨가하여 2$0^{\circ}C$에서 24시간 저장한 결과는 E. coli O157:H7 CDF1, A. sobria CDF3와 S. aureus CDF2은 우롱차 추출물을 0.5%첨가한 경우 성장이 억제되는 경향을 나타내었다.

• 한국세라믹학회지
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• 제27권1호
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• pp.55-61
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• 1990

Effect of Al2O3 addition on the mechanical properties and microstructure of Ce-TZP were studied. 12, 14, 16Ce-TZP containing 0-40wt% Al2O3 were prepared by sintering at 155$0^{\circ}C$ for 2h. in air. Density, linear shrinkage, bending strength, Vickers hardness, microstructuer and the amount of stress induced phase transformation were examined. Vickers hardness increased linearly with increasing amounts of Al2O3. The amount of transformation and fracture toughness decreased linearly with increasing amount of Al2O3. Linear shrinkage and relative density decreased with increasing Al2O3 content in all composition of Ce-TZP. Grain growth of Ce-TZP was inhibited by Al2O3 dispersion and fracture mode of Ce-TZP/Al2O3 composites transformed from intergranular to transgranular fracture as the amount of Al2O3 increased. TEM observation revealed that Al2O3 particles were located mainly at grain boundaries of ZrO2.

• 한국세라믹학회지
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• 제42권5호
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• pp.319-325
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• 2005

[ $LiNiO_2$ ] was synthesized by the solid-state method after mixing $LiOH{\cdot}H_2O$ and $Ni(OH)_2$ with SPEX mill. The optimum condition for the synthesis of $LiNiO_2$ was the calcination at $750^{\circ}C$ for 30h in $O_2$ stream after milling for 1 h. The $LiNiO_2$ synthesized under this condition showed relatively large value of $I_{003}/I_{104}$ and relatively small value of R-factor. When $LiNiO_2$ was cycled in 2.7$\~$4.15 V at 0.1C-rate, the first discharge capacity was not very large (145.8 mAh/g) but it showed good cycling performance. When $LiNiO_2$ was cycled in 2.7$\~$4.2 V at 0.1C-rate, the first discharge capacity was large but ,it showed poor cycling performance probably because of the transition of H2 hexagonal structure to H3 hexagonal structure. In addition, when $LiNiO_2$ was cycled in 1.0$\~$4.8 V at 1/24C- rate, the first discharge capacity was very large (257.7 mAh/g) and the discharge capacity increased with the number of cycles.

• 한국환경과학회지
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• 제31권8호
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• pp.677-689
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• 2022

In order to photocatalytically treat organic matter (COD_Cr) and chromaticity effectively, chemical coagulation and sedimentation processes were employed as a pretreatment of the leachate produced from landfill in Jeju Island. This was performed using FeCl₃·6H₂O as a coagulant. For the treated leachate, UV/TiO₂ and UV/TiO₂/H₂O₂ systems were investigated, using 4 types of UV lamps, including an ozone lamp (24 W), TiO₂ as a photocatalyst, and/or H₂O₂ as an initiator or inhibitor for photocatalytic degradation. In the chemical coagulation and sedimentation process using FeCl₃·6H₂O, optimum removal was achieved with an initial pH of 6, and a coagulant dosage of 2.0 g/L, culminating in the removal of 40% COD_Cr and 81% chromaticity. For the UV/TiO₂ system utilizing an ozone lamp and 3 g/L of TiO₂, the optimum condition was obtained at pH 5. However, the treated COD_Cr and chromaticity did not meet the emission standards (COD_Cr: 400 mg/L, chromaticity: 200 degrees) in a clean area. However, for a UV/TiO₂/H₂O₂ system using 1.54 g/L of H₂O₂ in addition to the above optimum UV/TiO₂ system, the results were 395 mg/L and 160 degrees, respectively, which were within the emission standard limits. The effect of the UV lamp on the removal of COD_Cr, and chromaticity of the leachate decreased in the order of ozone (24 W) lamp > 254 nm (24 W) lamp > ozone (14 W) lamp > 254 nm (14 W) lamp. Only COD_Cr and chromaticity treated with the ozone (24 W) lamp met the emission standards.

• 한국결정성장학회지
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• 제8권1호
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• pp.138-144
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• 1998

에탄올을 용매로 사용한 철질산염(Fe$(MO_3)_3{\cdot}9H_2O$) 용액의 가용매분해 및 중합반응을 거친후 $350^{\circ}C$의 온도로 열처리를 하여 0.5$\alpha$m이하의 크기를 갖는 $\alpha$-$Fe_2O_3$ 미분말을 합성하였다. 반응시간에 따른 pH 변화와 적외선 분광 분석을 통해 용액내의 반응을 규명하였으며, 열분석(DSC), X-선 회절분석 및 적외선 분광(FT-IR) 분석을 통해 $\alpha$-$Fe_2O_3$가 형성되는 분해과정에 대해 분석하였다. 또한 반응온도와 철질산염의 농도를 변화시켜 각각 $\alpha$-$Fe_2O_3$분말의 입자크기에 미치는 영향을 조사하였다.

• Corrosion Science and Technology
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• 제5권6호
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• pp.206-212
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• 2006

The effects of sub-ppm levels of $H_2S$ and the adsorbed water on the atmospheric corrosion of silver were studied with In situ weight balance to study the effect of the adsorbed water on the kinetic behavior and to determine the rate-controlling step, with XPS to analyze the tarnish film, and with calculation of phase equilibrium to predict the stable solid phase, the concentrations of dissolved species ($Ag^-$, $H^+$, $S^{2-}$, $HS^-$) and the equilibrium potentials ($E_{Ag^+/Ag}$, $E_{H^+/H_2}$, $E_{O_2/O^{2-}$). The results of weight measurements showed that oxygen was required for the sulfidation of silver in 100 ppb $H_2S$ and humidified environments enhanced the tarnished rate and oxidizing power. In addition, the rate determining step for tarnishing silver was shown to be changed to transport though the tarnish film.

• Bulletin of the Korean Chemical Society
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• 제21권11호
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• pp.1125-1132
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• 2000

The pH effect of the precursor solution on the preparation of $LiCoO_2$ by a solution phase reaction containing malonic acid was carried out. Layered $LiCoO_2$ powders were obtained with the precursors prepared at the different pHs (4, 7, and 9) and heat-treated at $700^{\circ}C(LiCoO_2-700)$ or $850^{\circ}C(LiCoO_2-850)$ in air. pHs of the media for precursor synthesis affects the charge/discharge and electrochemical properties of the $LiCoO_2electrodes.$ Upon irrespective of pH of the precursor media, X-ray diffraction spectra recorded for $LiCoO_2-850$ powder showed higher peak intensity ratio of I(003)/I(104) than that of $LiCoO_2-700$, since the better crystallization of the former crystallized better. However, $LiCoO_2$ synthesized at pH 4 displayed an abnormal higher intensity ratio of I(003)/I(104) than those synthesized at pH 7 and 9. The surface morphology of the $LiCoO_2-850$ powders was rougher and more irregular than that of $LiCoO_2-700$ made from the precursor synthesized at pH 7 and 9. The $LiCoO_2electrodes$ prepared with the precursors synthesized at pH 7 and 9 showed a better electrochemical and charge/discharge characteristics. From the AC impedance spectroscopic experiments for the electrode made from the precursor prepared in pH 7, the chemical diffusivity of Li ions (DLi+) in $Li0.58CoO_2determined$ was 2.7 ${\times}$10-8 $cm^2s-1$. A cell composed of the $LiCoO_2-700$ cathode prepared in pH 7 with Lithium metal anode reveals an initial discharge specific capacity of 119.8 mAhg-1 at a current density of 10.0 mAg-1 between 3.5 V and 4.3 V. The full-cell composed with $LiCoO_2-700$ cathode prepared in pH 7 and the Mesocarbon Pitch-based Carbon Fiber (MPCF) anode separated by a Cellgard 2400 membrane showed a good cycleability. In addition, it was operated over 100 charge/discharge cycles and displayed an average reversible capacity of nearly 130 mAhg-1.