• Journal of Korean Society for Atmospheric Environment
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• v.33 no.2
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• pp.87-96
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• 2017

In this study, 4 gases containing typical chlorinated volatile organic compounds (VOCs) were treated by ultraviolet (UV) irradiation. The typical chlorinated VOCs are dichloromethane (DCM), trichloromethane (TCM), carbon tetrachloride (CTC) and trichloroethylene (TCE). The removal efficiency (RE) and the products of chlorinated VOCs by UV irradiation are investigated. At this time, 2 types of background gas (air and nitrogen) were used to figure out the RE by photooxidation and photolysis. The specification of UV-lamp used in this study was low-pressure mercury lamp emitting wavelength of 185~254 nm. The experimental conditions were set as initial VOC concentration of $180{\pm}10ppm$, empty bed retention time (EBRT) of 53 s, temperature of $23{\pm}2^{\circ}C$ and relative humidity of $65{\pm}5%$. In the photolysis condition with nitrogen ($N_2$) as background gas, the averaged RE of the 4 types of chlorinated VOCs was about 24% higher than that with photooxidation; and the REs of VOCs except CTC were confirmed as >99%. The composition of off-gases after UV photooxidation in air was investigated and several intermediates from DCM, TCM and TCE were detected by GC/MS. Among them, phosgene which is a toxics was detected as an intermediate of TCM. In addition, the concentration of carbon dioxide ($CO_2$) in the off-gases was measured to calculate the mineralization rate (MR). With the photooxidation, TCE showed the highest RE (>99%) while MR was the lowest (17%); and the MR of DCM was the highest (86%). In addition, particulate matters (PM) in the off-gases was also detected and high concentrated $PM_{10}$ ($21,580{\mu}g{\cdot}m^{-3}$) and $PM_{2.5}$ ($6,346{\mu}g{\cdot}m^{-3}$) were detected in TCE off-gas. More than 99% of the chlorinated VOCs could be removed using UV254-185 nm lamp, while it is necessary to conduct further studies on the production and treatment of secondary pollutants.

• The Journal of Engineering Geology
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• v.13 no.4
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• pp.389-404
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• 2003

VOCs were detected in the 21 groundwaters out of 37 groundwaters sampled from around the Hanam Industrial Complex and the Gwangju stream. Ten components of chlorinated aliphatic hydrocarbons of VOCs were detected in the 18 groundwater samples. Among them, total trihalomethanes (TTHM) concentration is in the range of $0.1~36.2{\;}\mu\textrm{g}/L$, CECs concentration is $2.3~190{\;}\mu\textrm{g}/L$, and chlorinated solvents concentration containing PCE, TCE, etc. is $0.1~124.2{\;}\mu\textrm{g}/L$ respectively. Ten components of the aromatic hydrocarbons of VOCs were detected in the 5 groundwater samples, but their concentration are less than $1{\;}\mu\textrm{g}/L$. Detection frequency and concentration of the chlorinated aliphatic hydrocarbons components from the groundwaters in the Hanam Industrial Complex are higher than those of nearby downtown Gwangju stream. VOCs components except for TCE are lower than the MCL of USGS drinking water standard. TCE concentration of the 2 groundwater samples is over MCL, whose concentrations are 5 and 25 times higher than MCL, respectively. TCE is detected from the H8 and H10 groundwater samples and CFCs is detected H8 and H11 groundwater samples in the Hanam Industrial Complex. TTHM in study area is estimated from leakage of the main waters or sewage waters. Because most of the studied groundwater is under an aerobic condition, aromatic hydrocarbons are well degraded. But chlorinated aliphatic hydrocarbons are degraded very slowly.

• Environmental Engineering Research
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• v.17 no.2
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• pp.103-110
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• 2012

This study was performed mainly to examine whether a city with a metal industrial presence presents different characteristics in ambient volatile organic compound (VOC) concentrations compared to residential (RES) and commercial/residential combined (CRC) areas of another city by using long-term monitoring data (from January 2006 to February 2009). For most target VOCs, ambient concentrations in the metal-industrialized city were lower than for the RES and CRC areas. Aromatic compounds were the predominant VOC groups for the metal industry city as well as for other land uses. The ambient concentrations of aromatic VOCs were higher in the winter and spring seasons than in the summer and fall seasons, whereas those of chlorinated VOCs did not show any distinctive variations. In addition, higher concentrations were observed during daytime hours. The correlations between the ambient target compounds were statistically significant, except for the correlation between benzene and ozone.

• Asian Journal of Atmospheric Environment
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• v.4 no.1
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• pp.42-54
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• 2010

Automobile emissions have caused a major hydrocarbon pollution problem in the ambient air of many cities around the world. This study was conducted to measure the pollution status of volatile organic compounds (VOCs) in some urban residential areas in Seoul, Korea. A total of 20 VOCs (11 aromatic and 9 chlorinated species) were identified at 4 urban residential sites in Seoul, Korea from February 2009 to July 2009. Comparison of total VOC (TVOC) concentration data indicated the dominance of the aromatic species with the maximum (72.2 ppbC) at Jong Ro (JR) and the minimum at Yang Jae (33.4 ppbC). The peak concentration of TVOC occurred during spring at all sites with an exception at Gang Seo (GS), where it was recorded during winter. The distribution of individual VOCs at the study sites was characterized by high toluene concentration. A strong correlation of benzene was also observed with other VOCs and criteria pollutants at all sites (except YJ). The overall results of this study suggest that vehicular emissions have greatly contributed to the increase in VOC pollution at all the study sites.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.61-61
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• 1995

Volatile organic compounds(VOCs) are of concern for their potential chronic toxicity, their suspected role in the formation of smog, and their suspected role in destruction of stratospheric ozone. Present study evaluated the exposures to selected VOCs in three microenvironments: 2 chlorinated and 5 aromatic VOCs in the indoor and outdoor air, and 5 aromatic VOCs in the breathing zone air of gas-service station attendants. With permissible Quality Assurance and Quality Control performances VOC concentrations were measured 1) to be higher in indoor air than in outdoor air, 2) to be higher in two Taegu residential areas than in a residential area of Hayang, and 3) to be higher in the nighttime than in the daytime. Among five aromatics, Benzene and Toluene were two most highly measured VOCs in breathing zone air of service station attendants. Based on the sum of VOC concentrations, the VOC exposure during refueling was estimated to be about 10% of indoor and outdoor exposures. For Benzene only, the exposure during refueling was estimated to cause about 52% of indoor and outdoor exposure. The time used to calculate the exposures was 2 minutes for refueling and 24 hours for indoor and outdoor exposures.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.447-459
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• 1995

Volatile organic compounds(VOCs) are of concern for their potential chronic toxicity, their suspected role in the formation of smog, and their suspected role in destruction of stratospheric ozone. Present study evaluated the exposures to selected VOCs in three microenvironments: 2 chlorinated and 5 aromatic VOCs in the indoor and outdoor air, and 5 aromatic VOCs in the breathing zone air of gas-service station attendants. With permissible Quality Assurance and Quality Control performances VOC concentrations were measured 1) to be higher in indoor air than in outdoor air, 2) to be higher in two Taegu residential areas than in a residential area of Hayang, and 3) to be higher in the nighttime than in the daytime. Among five aromatics, Benzene and Toluene were two most highly measured VOCs in breathing zone air of service station attendants. Based on the sum of VOC concentrations, the VOC exposure during refueling was estimated to be about 10% of indoor and outdoor exposures. For Benzene only, the exposure during refueling was estimated to cause about 52% of indoor and outdoor exposure. The time used to calculate the exposures was 2 minutes for refueling and 24 hours for indoor and outdoor exposures.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.57-65
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• 2005

To investigate the characteristics of the volatile organic compounds (VOCs) concentration in the groundwater around Ulsan, Korea, 168 groundwaters, 12 stream waters, and 6 sewage waters were analyzed for 61 VOCs. Results showed that VOCs were not detected in stream waters and total VOCs concentration in 5 sewage waters was in the range of ND-22.3 ${\mu}$g/L. In 78 groundwater samples more than one VOCs were detected and VOCs concentration of the samples ranged from 0.1 ${\mu}$g/L to 387.1 ${\mu}$g/L. However, VOCs concentration of 66 samples out of 78 samples showed less than 10 ${\mu}$g/L and that of only 6 samples exceeded Korea drinking water limit (KDWL). 42 VOCs detected from the 168 groundwaters were 14 aromatic hydrocarbons out of 25, 27 chlorinated aliphatic hydrocarbons out of 35, and methyl tert-butyl ether (MTBE). Detection rate of each VOCs in the groundwaters was as follows: chloroform in 43 samples (25.6%), methylene chloride in 36 samples (21.4%), TCE in 26 samples (15.5%), 1,1-dichloroethane in 19 samples (1.3%), PCE in 16 samples (9.5%), cis-1,2-DCE in 15 samples (8.9%), and toluene in 14 samples (8.3%). Even though VOCs concentration in the groundwaters of the study area is still low, the city is expanding and the drinking water limit is becoming strict, and therefore continuous monitoring is necessary.

• Membrane Journal
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• v.11 no.1
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• pp.50-59
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• 2001

Influence of concentration polarization has been investigated on the vapor permeation of VOCs/$N_2$ mixture. Po]y(dimethylsiloxane)(PD,vIS) membrane which had a good affinit~, toward VOCs was emploj,'c'Cl in this study. The chlorinated hydmcarbons which were part of homologous series of chrolomelhane and chrolocthane were used as organic vapor. The vapor permeation experiments were calTied out at various VOCs feed concentrations. operating temperatures and feed flow rates. With decreasing feed flow rate. the membrane perfonnance, that is. penneation rate and selectivity were reduced in the permeation of VOCs/$N_2$ mixture. Especially the reducing of the membrane performance was founel to be more significant when the condensibility of voe was greater. voe content in the feed mixture was higher or operating temperature was lower. These observations were discussed in terms of the influence of con-centration polarizalion on the permeation of VOCSINl mixture through the PDMS membrane.

• Membrane Journal
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• v.11 no.2
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• pp.74-82
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• 2001

By using a phenomenological approach, model equations incorporating the resistance-in¬series concept were established to evaluate quantitatively concentration polarization in the boundary layer in feed adjacent to the membrane surface in the vapor permeation and separation of volatile organic compounds (VOCS)/$N_2$ mixture through po]y(dimethylsiloxane) (PDMS) membrane. The vapor permeations of various VOCS/$N_2$ mixtures through PDMS membrane were carried out at various feed flow rates. Chlorinated hydrocarbons, such as, methylene chloride, chlorofonn, 1,2-clichloroethane and 1,1,2-trichloroethane were used as organic vapor. By fitting the model equations to the experimental penneation data. the model parameters were detennined. respectively. Both the mass transfer coefficient of VOC across tbe boundary layer and concentration polarization modulus as a measure of the extent of concentration polarization were eitimated Quantitatively by the mooe1 equations with the determined model parameters. From the analysis on the detennined model parameters, the boundary layer resistance due to the concentration polarization of VOCs component was found to be more significant when the condensability of voe was greater. This study seeks to emphasize the importance of the boundary resistance on the vapor penneation of the vapor/gas mixtures with high permeability and high selectivity towards the minor component VOC.

• Economic and Environmental Geology
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• v.37 no.6 s.169
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• pp.613-629
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• 2004

Contamination of groundwater by volatile organic compounds (VOCs) was investigated for 168 groundwater wells in Ulsan area to study the natural attenuation of organic compounds in the aquifers. As groundwater contamination by VOCs is closely related to land use, 168 groundwater samples were classified into 4 different groups; agricultural, forestry, industrial, and residential & business. From analysis 65 out of 168 groundwater samples contained more than one VOC. Analysis of samples were performed fir 36 halogenated aliphatic hydrocarbons and 25 petroleum hydrocarbons set up by NAWQA of US geological survey. Twelve petroleum hydrocarbons were detected in 26 groundwater wells, but their concentrations were less than 1.5 g/L except for MTBE. Twenty three chlorinated aliphatic hydrocarbons, composed of 11 methanes, 6 ethanes and 6 ethenes, were detected in 63 groundwater samples. The range of methanes concentration was $ND\~330\;/gL,\;ethanes\;ND\~84\;gL$, and PCE and their derivatives $ND\~62\;g/L$. As the study area was comprised of the aerobic/denitrification zones and $Fe^{+3}$ redox condition, most of petroleum hydrocarbons were degraded well, while halogenated hydrocarbons were slowly biodegradation.