• Journal of ILASS-Korea
• /
• v.23 no.4
• /
• pp.185-191
• /
• 2018

Benzene, toluene, ethylbenzene and xylene (BTEX) were well known as ozone precursors from photochemical reactions and contribute to the formation of photochemical smog which pose health hazards. Also, some of these compounds directly affect the human health due to their toxicity such as benzene. In this study, BTEX ratios and correlation of $C_2$-benzenes (xylenes, ethylbenzene) in vehicle exhaust from recreational vehicle (RV) and multi-purpose vehicle (MPV) were characterized using a chassis dynamometer. VOCs were collected by tedlar bag and a GC/MS system was used for their quantification. Among all of the BTEX, toluene has the highest concentration(more than 30% in composition of BTEX). The average ratio of toluene to benzene emissions (T/B ratio=2.2) was found in vehicle exhaust. The average m,p-xylene/ethylbenzene and m,p-xylene/o-xylene ratios were 1.0 and 3.0 respectively. As a result, it showed a good correlation between the $C_2$-benzenes ($R^2=0.98{\sim}0.99$). In the future, it can be used as a marker for effect evaluation to atmospheric environment by vehicle exhaust.

• Analytical Science and Technology
• /
• v.23 no.5
• /
• pp.465-476
• /
• 2010

In this study, a number of volatile organic compounds (VOCs) including benzene, toluene, p-xylene, styrene, and methyl ethyl ketone were analyzed from samples collected in ambient air and under the field conditions. These samples were analyzed independently by two different set-ups for VOC analyses, i.e., between [1] gas chromatography/flame ionization detector with tube sampling - (F-T system) and [2] gas chromatography/mass spectrometer with bag sampling (M-B system). The analytical results derived by both systems showed fairly similar patterns in relative sense but with moderately large differences in absolute sense. The results of M-B system were high relative to F-T system with the F-T/M-B ratio below 1. If the relative biases of the two measurement techniques are derived in terms of percent difference (PD) in concentration values, the results were generally above 35% on average. A student t-test was applied to investigate the statistical significance of those differences between the systems. The results of both analytical systems were different at 95% confidence level for toluene, p-xylene, styrene, and methyl ethyl ketone (P < 0.043). However, F-T and M-B systems showed strong correlations for toluene and p-xylene. The observed bias is explained in large part by such factors as the differences in standard phases used for each system and the chemical loss inside the bag sampler.

• Journal of Korean Society for Atmospheric Environment
• /
• v.27 no.5
• /
• pp.558-568
• /
• 2011

Hazardous volatile organic compounds (HVOCs) have been increasingly getting concern in urban air chemistry due to photochemical smog as well as its toxicity or potential hazards. In this study, we investigated their concentrations and the properties in tunnel, urban roadside and residential area. As a result, among 36HVOCs measured in this study, BTEX (benzene, toluene, ethylbenzene, xylene) and dichlorodifluoromethane, 1,2,4-trimethylbenzene, trichlorofluoromethane were detected above the concentration of $1{\mu}g/m^3$ in every sampling site and the most abundant compound was toluene. The other compounds were detected at trace level or below the detection limit. In addition, we found that three CFCs (chlorofluorocarbons), such as CFC-12, CFC-11, CFC-113, were persistently detected because of the emission in the past. Toluene to benzene ratio (T/B) at tunnel and roadside were calculated to be 4.3~5.3 and at residential area 15.4, suggesting that the residential area had several emission sources other than car exhaust. The ratio of X/E (m,p-xylene to ethylbenzene) ratio was calculated to be 1.8~2.1 at tunnel, 1.7 at roadside and 1.2 at residential area, which means this ratio reflected well the relative photochemical reactivity between these compounds. Good correlation between m,p-xylene and ethylbenzene ($r^2$ > 0.85) were shown in every study sites. This indicated that correlation between $C_2$-alkylbenzenes were not severely affected by 3-way catalytic converter. In this study, it was demonstrated that the concentration of benzene was very low, compared with national air quality standard (annual average of $5{\mu}g/m^3$). Its concentration were $2.52{\mu}g/m^3$ in roadside and $1.34{\mu}g/m^3$ in residential area. We thought this was the result of persistent policy implementation including the reduction of benzene content in gasoline enforced on January 1, 2009.

• Journal of environmental and Sanitary engineering
• /
• v.17 no.2
• /
• pp.63-70
• /
• 2002

We investigated the concentration degree of VOCs for ambient air in the air environment control area of Kyonggi-do in 2001. The VOCs showing higher concentration were in the ascending order of Toluene > n-Butane > 1-Butene > Benzene > n-Hexane. The concentration distribution ratio mentioned above showed almost same pattern in each city. The relative concentration ratio of Benzene, Toluene, Ethylbenzene, Xylenes which are aromatic VOCs were 1 : 6.3 : 0.6 : 1.6. It was similar to the pattern in 1999 but different from the pattern in 2000. In the aspect of seasons, the highest B.T.E.X concentration was indicated in fall and in the aspect of areas, the higher concentration showed in the ascending order of Buchon > Ansan > Kwangmyong > Shihung > Sungnam. The average concentration of target VOCs for ambient air in the air environment control area of Kyonggi-do showed lower concentration than the metropolis of Seoul but higher concentration than Kwang-ju city and Dae-gu city. The amount of total VOCs was increasing, comparing with it last year and the more increasing tendency is anticipated so that it will need to establish the proper regulative criteria.

• Tribology and Lubricants
• /
• v.33 no.6
• /
• pp.263-268
• /
• 2017

The significance of maintaining the soil environment is gradually increasing owing to soil and underground water contamination by petroleum leak accidents. However, the purification of soil is an expensive and more time-consuming process than the purification of contaminated water and air. Moreover, determining the source and people responsible for soil pollution gets often embroiled in legal conflicts, further delaying the cleanup process of the contaminate site. Generally, TPH (total petroleum hydrocarbon) pattern analysis is used to determine the petroleum species and polluter responsible for soil contamination. However, this process has limited application for petroleum products with a similar TPH pattern. In this study, we analyze the TPH pattern and specific sectional ratio (${\sim}C_{10}$, $C_{10}-C_{12}$, $C_{12}-C_{36}$, and $C_{36}{\sim}$) of various domestic petroleum products to identify the petroleum product responsible for soil contamination. Also, we perform BTEX (benzene, toluene, ethyl benzene, xylene) quantitative analysis and determine B:T:E:X ratio using GC-MS. The results show that gasoline grade 1 and 2 have a similar TPH pattern but different BTEX values and ratios. This means that BTEX analysis can be used as a new method to purify soil pollution. This complementary TPH and BTEX method proposed in this study can be used to identify the petroleum species and polluters present in the contaminated soil.

• Journal of Environmental Science International
• /
• v.16 no.4
• /
• pp.415-423
• /
• 2007

This study assessed the characteristic of BTEX (Benzene, Toluene, Ethylbenzene, Xylene) concentration ratios of industrial emission sources and the neighborhoods of industrial area, fuel such as gasoline, light oil, LPG, and similar gasoline, and ambient air in Daegu. The BTEX in aromatic compounds was the most abundant VOC in Daegu. The BTEX ratios were (0.2:2.6:1.0:1.8) for the neighborhoods of industrial area, (2.6:11.3:1.0:1.2) for residential area, (2.2:11.0:1.0:1.6) for commercial area, (1.0:14.9:1.0:1.3) for industrial area, and (0.2:2.6:1.0:1.8) for the neighborhoods of industrial area. Average BTEX ratios in Daegu were B/T ratio (0.1), B/EB ratio (1.5), B/X ratio (1.1), T/EB ratio (12.6), T/X ratio (10), EB/X ratio (0.7), Expecially, B/T ratio in Daegu was similar as the other cities, Bangkok, Manila, and Hongkong. Comparing other cities with B/T ratio, the main sources of VOC were vehicular exhaust and emission of industrial facilities. Furthermore, BTEX correlation were evaluated at the emission sources and regional areas. Results showed that correlation coefficient values of emission sources, fuels and neighborhood of industry were significant magnitude above 0.65(p<0.01). Also, there showed highly significant correlations among BTEX. Calculated correlation coefficients of ambient air sampling sites were $0.61{\sim}0.954$ for commercial /residential area and $0.613{\sim}0.998$ for industrial area. However, they showed different correlation between commercial/residental area and industrial area. It implied that the emission sources were different from each area.

• Applied Chemistry for Engineering
• /
• v.8 no.6
• /
• pp.967-972
• /
• 1997

Recovery of aromatics in extract phase which was obtained by batch equilibrium extraction between light cycle oil(LCO) and dimethylsulfoxide(DMSO) solution as solvent was investigated by re-extraction. To select the most suitable re-extraction solvent for recovery of aromatics in extract phase, distribution equilibrium was measured between extract phase and solvents. The solvents used were benzene(B), toluene(T), m-Xylene(mX), n-hexane(Hx) and n-hexane(Hx) and n-Octane(Ot). From the distribution coefficients and yields of aromatics, Hx seemed to be the most suitable. Furthermore, effects of operation parameters for re-extraction of aromatics in the extract phase were studied by batch equilibrium re-extracion with Hx as solvent. Yields of aromatics were found to increase with increasing solvent/feed (extract phase) mass ratio(S/F), while distribution coefficients of aromatics were fixed irrespective of S/F used. Operating temperature did not affect distribution coefficients and yields of aromatics. Distibution coefficients and yields of naphthalene group(carbon numer : 10~12) increased with increasing cabon number. Mass transfer rates of aromatics were also measured with a batch stirred vessel.