Kim S.C.,Mokpo National University |
Kim S.C.,Korea Environmental Industry and Technology Institute KEITI |
Ryu J.Y.,Korea Atomic Energy Research Institute
Environmental Technology | Year: 2011
Catalytic oxidation of volatile organic compounds such as toluene over a range of silver-based catalysts has been carried out to assess their performance. The properties of the catalysts were determined by the Brunauer-Emmett-Teller method, X-ray diffraction, and temperature-programmed reduction. The experimental results revealed that the catalytic activity of an Ag/γ-Al2O3 catalyst is closely related to the silver loading, and the optimum loading for the complete oxidation of toluene was found to be 11 wt%. The addition of copper to the 11 wt% Ag/γ-Al 2O3 catalyst greatly enhanced its catalytic activity, but the addition of cerium or lanthanum inhibited catalytic activity. © 2011 Taylor &Francis.
Song J.-H.,Seoul National University |
Kim D.W.,Korea Environmental Industry and Technology Institute KEITI |
Kim H.,Seoul National University |
Lee D.S.,Seoul National University
Journal of Hazardous Materials | Year: 2014
Maintaining coherence among environmental quality objectives (EQOs) should be an important consideration for the EQOs to be met simultaneously. The objectives of the present work were to demonstrate the need of accurate variability prediction by models and to present considerations in selecting models for testing coherence of the EQOs. SimpleBox and POPsME were chosen as the two different types of models to compare the prediction variability and its influence on the results of coherence test among the maximum permissible concentrations (MPCs) of polycyclic aromatic hydrocarbons (PAHs) in South Korea. False calls by these models on coherence were found to occur often due to inaccurate prediction of variability in the concentration ratio at steady state, strongly suggesting that models for coherence test should be accurate in predicting not only the point value representing the concentration ratio but the variability of the value. It was demonstrated that spatially resolved dynamic models would have an intrinsic advantage over one box steady state models in reducing the rate of false negative call. © 2013 Elsevier B.V.
Lee H.,Yonsei University |
Ryu J.,Korea Atomic Energy Research Institute |
Kim J.,Yonsei University |
Noh Y.,Gwangju Institute of Science and Technology |
Yoon Y.,Korea Environmental Industry and Technology Institute KEITI
Atmospheric Environment | Year: 2011
A measurement method combining multi-axis differential optical absorption spectroscopy (MAX-DOAS) and a transmissometer (TX) is introduced as a means of retrieving surface trace gas mixing ratios in ambient air. The combined measurement method was utilized to derive surface NO2 mixing ratios from 27 March to 11 May 2007 in Seoul, Korea. To convert the differential slant column density (DSCD) to the volume mixing ratio (VMR), the light path length (LPL) along the MAX-DOAS line of sight was derived using the light extinction coefficient and ångstrom exponent data obtained by a TX and sunphotometer, respectively. Temporal variations of the NO2 VMRs at the 0-1km layer obtained from radiative transfer model (RTM) simulations coupled with MAX-DOAS data show similar patterns, but with reduced magnitudes, to the ground level data and those of the combined MAX-DOAS and TX measurements at 0.08km. The NO2 VMRs retrieved by the combined measurement were in agreement with those obtained from the RTM simulations coupled with MAX-DOAS data and the in-situ measurements within 40 and 50%, respectively. The coefficient of determination (R2) of 0.75 was obtained between the combined measurement data sets and those of the RTM simulations coupled with MAX-DOAS data whereas that between the combined measurement data sets and those of the in-situ measurements was 0.53. The coefficient of determination (R2) between the data sets derived from the RTM simulations coupled with MAX-DOAS data and those of the in-situ measurements was 0.67 with the scatter of the correlation within the 50% range. © 2011 Elsevier Ltd.
Hong S.-B.,Korea Polar Research Institute |
Lee K.,Korea Polar Research Institute |
Hur S.-D.,Korea Polar Research Institute |
Hong S.,Inha University |
And 7 more authors.
Bulletin of the Korean Chemical Society | Year: 2015
We present a titanium (Ti) melting head divided into three zones as an improved melting system for decontaminating ice-core samples. This system was subjected to performance tests using short ice-core samples (4 × 4 cm2, ∼5 cm long). The procedural blanks (PBs) and detection limits of ionic species, with the exception of NO3-, were comparable with published values, but for elements the experimental procedures should be refined to obtain valid Zn concentrations due to the PB of ∼90.0 ± 16.2 ng/L. The improved melting system efficiently decontaminated the samples, as verified by the concentration profiles of elements and ions in the melted samples from the three melting-head zones. The recovery of trace elements in ice-core samples was ∼70-120% at ∼100 ng/L in artificial ice cores. Because of the memory effects between ice-core samples melted in series, the melting system should be rinsed at least 5-6 times (in a total volume of ∼2.5 mL deionized water) after each melting procedure. Finally, as an application of this technique, trace elements were measured in ice-core samples recovered from the East Rongbuk Glacier, Mount Everest, (28°03'N, 86°960'E, 6518 m a.s.l.), and the concentrations of trace elements following mechanical chiseling and the melting method were compared. © 2015 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
An X.,Gwangju Institute of Science and Technology |
Shin D.,Gwangju Institute of Science and Technology |
Ocon J.D.,Gwangju Institute of Science and Technology |
Lee J.K.,Gwangju Institute of Science and Technology |
And 2 more authors.
Cuihua Xuebao/Chinese Journal of Catalysis | Year: 2014
Non-noble metals such as Fe and Ni have comparable electrocatalytic activity and stability to that of Ir and Ru in an oxygen evolution reaction (OER). In this study, we synthesized carbon nanofibers with embedded FeNi composites (FeNi-CNFs) as OER electrocatalysts by a facile route comprising electrospinning and the pyrolysis of a mixture of metal precursors and a polymer solution. FeNi-CNFs demonstrated catalytic activity and stability that were better than that of 20 wt% Ir on Vulcan carbon black in oxidizing water to produce oxygen in an alkaline media. Physicochemical and electrochemical characterization revealed that Fe and Ni had synergistic roles that enhanced OER activity by the uniform formation and widening of pores in the carbon structure, while the CNF matrix also contributed to the increased stability of the catalyst. © 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.
Lee H.,Yonsei University |
Kim J.,Yonsei University |
Ryu J.,Korea Environmental Industry and Technology Institute KEITI |
Kwon S.,Georgia Institute of Technology |
And 2 more authors.
Journal of the Optical Society of Korea | Year: 2010
A scanning imaging spectrograph system was used in this study to retrieve readings of the 2-D distribution of SO2 and BrO around the crater of the Sakurajima volcano in Japan. The measurement was carried out during the daytime on November 2, 2005. Measurements were made at the surface of the site, located 5 km from the Sakurajima crater. One hundred horizontal scans were performed. Each column scanned by the system consists of 64 vertical pixels in order to retrieve the spatial distributions of BrO and SO2 in the plume in terms of slant column densities (SCDs). Measured spectra were analyzed to identify and quantify SO2 and BrO in the volcanic plume utilizing the plume's specific absorption features in the ultra violet region. Two-dimensional BrO and SO2 distributions in SCD were retrieved horizontally covering the upwind, crater and downwind areas, and vertically, including the plume in the center of the scanned image. Both horizontal and vertical dispersions of SO2 SCD from the crater were successfully measured to be from 1017 to 4.5 × 1018 molecules cm-2. However, BrO was measured below 1015 molecules cm-2, which is considered its background level.
Eom Y.,Yonsei University |
Won J.H.,Yonsei University |
Ryu J.-Y.,Korea Environmental Industry and Technology Institute KEITI |
Lee T.G.,Yonsei University
Korean Journal of Chemical Engineering | Year: 2011
A biosorbent was prepared by drying garlic (Allium sativum L.) under vacuum and tested in its powder form for its mercury adsorption capability in aqueous solution. Results show that garlic powder has a good adsorption capacity for mercury and that the mercury concentration of the solution has a significant impact on the adsorption capacity of the biosorbent. The Langmuir and Freundlich adsorption isotherms were also constructed. The adsorption capacity, qmax, adsorption efficiency, b, and correclation confficient, r2 for the Langmuir model were 0.6497, 0.4903, and 0.9980, respectively. For the Freundlich model, the model parameters, KF, 1/n, and r2 for mercury were 4.1879, 0.3467, and 0.9518, respectively. Langmuir adsorption isotherm was better suited for the adsorption of mercury onto garlic powder, and that the maximum amount of mercury adsorbed (qmax) was 0.6497 mg/g. © 2011 Korean Institute of Chemical Engineers, Seoul, Korea.