• Journal of Korean Society for Atmospheric Environment
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• v.18 no.1
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• pp.51-58
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• 2002

Destruction process of toluene using a wire-cylindrical BBD (Dielectric Barrier Discharge) reactor packed with catalysts was investigated to characterize the synergetic effects of non-thermal plasma and catalyst process. The catalysts used in the present study were ${\gamma}$-Al$_2$BO$_3$ and Pt/${\gamma}$-Al$_2$O$_3$. Under the numerous test conditions, specific energy density (SED (J/L)) and the conversion of toluene, defined as (1 -[C$_{f}$]/[C$_{i}$]), were measured. The test results showed that toluene decomposition efficiency followed the pseudo-first order in the case of plasma only process. The pseudo-first order process, however, was modified to pseudo-zeroth order reaction in the case of catalyst-assisted plasma process. This modification of the reaction order was verified based on a simple kinetic model proposed in the present study. Owing to the modification of reaction order, which resulted from the catalytic process, the specific energy to achieve the high removal efficiencies, i.e. 80~90%, was reduced significantly.y.y.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.2
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• pp.149-159
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• 2002

The objective of this study was to evaluate the formation characteristics of CBs and CPs from TCE, aliphatic compound. The experiment was carried out in a fixed reactor during 30 min under the oxidation condition at the range of temperature, 300~$700^{\circ}C$. MSWI fly ash was used as catalyst in this study. Total amount of CBs formed greater magnitude than that of CPs overall range of reaction temperature. It is proposed that the formation of CPs was caused from hydroxylation of CBs. According to increasing temperature to $600^{\circ}C$, the yield of CBs and CPs increased but significantly decreased at $700^{\circ}C$. It is suggested that decomposition rate was faster than formation rate at the high temperature. In the homologue distribution of CBs, DCBs were major products at 30$0^{\circ}C$ and the amount of higher chlorinated compound increased to $600^{\circ}C$. Because they were formed by chlorination of lower chlorinated compounds. In case of CPs, the amount of DCPs was 90% of total amounts in both thermal formation and catalytic reaction. On the other hand it was clearly observed that the chlorination rate in catalytic reaction was higher than in thermal formation with TCE only.

• Asian Journal of Atmospheric Environment
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• v.4 no.2
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• pp.106-114
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• 2010

By the application of novel double detector system of micro-PIXE that can detect light elements (Z<14), we made an attempt to provide a thorough discussion on the aging processes of Asian dust (hereafter called "AD") particle by reaction with sea-slat. The elemental spectra and maps obtained from the microbeam radiation of micro-PIXE to individual AD particles were useful for fractionating AD particles into both internally and externally mixed particles. A spatial distribution of elements in a minute domain of single particle obtained by scanning the microbeam irradiation enabled us not only to estimate the chemical mixing state of individual AD particles but also to presume their aging processes in both ambient air and cloud. By calculating the normalized micro-PIXE net count of elements, it was possible to classify individual AD particles into three distinct groups (i.e., (1) Aging type 1: AD particle coated by the gaseous Cl evaporated by the reaction between artificial acids and sea salt; (2) Aging type 2: AD particle mixed with sea salt but no additional reaction with artificial acids; and (3) Non-aged type) A relatively high transformation rate (63.3-75.9%) was shown in large particles (greater than $5.1\;{\mu}m$ in diameter).

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.3
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• pp.247-256
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• 2000

Basic characteristics of non-thermal plasma process to remove C2H4 and NO have been experimentally investigated with a packed-bed type reactor and an ac power supply. The performance of the non-thermal plasma generated by ac power supply was compared with that of a wire-plate type reactor equipped with a pulsed power supply. The result shows that the non-thermal plasma can be effectively generated with an AC power supply that can be easily fabricated with conventional techniques. In order to understand the basic reaction mechanisms of the non-thermal plasma process, parametric tests for different carrier gases(air and nitrogen) and for different reaction pathways have been performed. The test results show that O3 generated by non-thermal plasma plays an dominant role to oxidize C2H4 and NO over N and O radicals when these pollutant gases are carried by dry air under room temperature condition. Experimental observations, however, indicate that N and O radicals can significantly affect on the removal process of the pollutant gases under certain conditions.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.4
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• pp.319-325
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• 1997

The catalytic decomposition of CFC-113(1,1,2-trichloro-1,2,2-trifluoroethane) was studied over an activated carbon catalyst in a fixed-bed reactor at the temperature from 300 to 600$^\circ$C, the space velocity (SV) of 1800 $\sim 14400h^{-1}$ and the mole ratio(decomposition agent/CFC-113) of 0.25 $\sim$ 5. In the absence of a decomposition agent, the decomposition efficiency of CFC-113 was low but when a decomposition agent was added to the gas stream, it was dramatically increased with the increase of temperature. In particular, in the presence of n-hexane as the decomposition agent it showed a high decomposition efficiency compared with benzene at 400$^\circ$C. It was found that the decomposition activity of CFC-113 was very sensitive to reaction temperature. Thus it is expected that to raise the reaction temperature is more effective than to increase the residence time and the amount of decomposition agent. Over the activated carbon catalyst more than 99% decomposition was achieved at the reaction temperature of 600$^\circ$C, SV of 7200$h^{-1}$, the mole ration $(C_6H_{14}/CFC-113)$ of 1 in this study.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.131-140
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• 2005

To investigate secondary carbonaceous species within PM$_{10}$ and PM$_{2.5}$ in Seoul urban Metropolitan Area (SMA), Korea. atmospheric particulate matters samples were collected at two sites of SMA at UOS (The University Of Seoul station) sites and IHU (InHa University of Incheon station) during the period of 4 to 14 January and 12 to 22 May, 11 to 15 August 2004, and their characteristics were qualitatively discussed. during January and May and August of 2004. Daily average mass concentration 0.095 mg/㎥ in PM$_{10}$ and 0.053 mg/㎥ in PM$_{2.5}$ for mass respectively. were observed in SMA. The concentrations of carbonaceous species contributed 18.4% and 16.4% of PM$_{2.5}$ and PM$_{10}$ during the sampling period, respectively, of which OC accounted for 68% and 52% more of the total carbon (TC). OC and EC concentrations and their mass percentages were higher in PM$_{2.5}$ than in PM$_{10}$ which could be attributed to generation process. Organic aerosols would constitute up to 38% of PM$_{2.5}$ based on the evaluation of 1.6 for the ratio of OC to organic particulate. Secondary organic carbon (SOC) were estimated to be more than 13% and up to 68% of total OC based on the minimum OC/EC ratio of 1.06/1.11 using least square method. Comparisons of OC and EC with trace elements. As results of carbonaceous species analysis, the dominant factor in view of fine particle (PM$_{10}$/PM$_{2.5}$) is primary emission source such as mobile, fossil fuel combustion etc. during winter time in SMA. But in summer periods, remarkable fine particle increasing factor was secondary organic carbon dependent to photochemical reaction. reaction.n. reaction.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.429-429
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• 2002

This study examines the influence of long-range transport of dust particles and air pollutants on photochemistry of OH and NO$_3$ at Jeju Island (33.17$^{\circ}$ N, 126.10$^{\circ}$ E) during the Asian dust-storm (ADS) period in April 2001. The atmospheric concentrations of criteria pollutants (O$_3$, NO$_2$, CO) and sulfur species were measured at a ground station on Jeju Island, Korea as part of the ACE-Asia intensive operation. Three ADS events were observed during the periods of 10-12, 13-14, and 25-26 April, respectively. The concentrations of the criteria pollutants (i.e., $O_3$, NO$_2$, and SO$_2$) were not significantly different from those during the non-Asian-dust-storm (NADS) period. Average OH and NO$_3$ levels at Jeju Island during the study period (ADS and NADS) were estimated to be 4-10 $\times$ 10$^{5}$ moleculescm$^{-3}$ and 2-4 pptv, respectively. Two main sources of OH radical were the primary production from the reaction of water vapor ($H_2O$) and O(1D) radicals and the reaction of HO$_2$ with NO. CO was a dominant sink of OH during the ADS period: whereas NO$_2$ was the most important during the NADS period. for NO$_3$ radical, a reaction of NO$_2$ with $O_3$ was the most important atmospheric source; while $N_2$O$_{5}$ uptake on dust particles was the most dominant sink during the ADS period.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.657-661
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• 1989

Symmetrical divinyl ketone or divinyl ${\alpha}$-diketone was synthesized in moderately good yields through palladium catalyzed carbonylative homocoupling reaction of vinylmercuric chlorides with carbon monoxide. In order to find out optimum synthetic reaction conditions, we examined the effect of catalysts, bases, solvents and reaction temperature when (E)-styrylmercuric chloride was used as a typical starting material. The best yield of divinyl ${\alpha}$-diketone was obtained in the reaction using 10 mol% of dichlorobis(triphenyl phosphine)palladium (II) as a catalyst, an equivalent of pyridine as a base, 10 mol% of iodine and acetonitrile at 50${\circ}$C under 10 atmospheric pressure of carbon monoxide. The yield of divinyl ${\alpha}$-diketone was decreased under atmospheric pressure of carbon monoxide.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E3
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• pp.137-148
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• 2003

In this study, we examined the influence of long-range transport of dust particles and air pollutants on the photochemistry of NO$_3$on Jeju Island, Korea (33.17 N, 126.10$^{\circ}$E) during the Asian Dust-Storm (ADS) period of April 2001. Three ADS events were observed during the periods of 10∼12, 13∼14, and 25∼26 April. Average concentration level of nighttime NO$_3$on Jeju Island during the ADS period was estimated to be about 2 x 10$^{8}$ molecules cm$^{-3}$ ( - 9 pptv). Decreases in NO$_3$levels during the ADS period was likely to be determined mainly by the enhancement of the $N_2$O$_{5}$ heterogeneous reaction on dust aerosol surfaces. The reaction of N20s on aerosol surfaces was a more important sink for nighttime N03 during the ADS due to the significant loading of dust particles. The reaction of $N_2$O$_{5}$ with NMHCs and the gas-phase reaction of N20s with water vapor were both significant loss mechanisms during the study period, especially during the NADS. However, dry deposition of these oxidized nitrogen species and a heterogeneous reaction of NO$_3$were of no importance. Short-term observations of $O_3$, NO$_2$, DMS, and SO$_2$in the MBL indicated that concentrations of most of these chemical species were different between the ADS and non - Asian - Dust-Storm (NADS) periods, implying that their levels were affected sensitively by the differences in air mass trajectories.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.1-8
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• 2010

Mild combustion is considered as a promising combustion technology for energy saving and low emission of combustion product gases. In this paper, the controllability of reaction region in mild combustion is examined by using co-axial air nozzle. For this purpose, numerical approach is carried out. Propane is considered for fuel and air is considered for oxidizer and the temperature of air is assumed 900K slightly higher than auto ignition temperature of propane. But unlike main air, the atmospheric condition of co-axial air is considered. Various cases are conducted to verify the characteristics of Co-Axial air burner configuration. The use of coaxial air can affect reaction region. These modification help the mixing between fuel and oxidizer. Then, reaction region is reduced compare to normal burner configuration. The enhancement of main air momentum also affects on temperature uniformity and reaction region. The eddy dissipation concept turbulence/chemistry interaction model is used with two step of global chemical reaction model.