• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.163-166
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• 2000

The purpose of this study is to evaluate substrate interactions of BTEX for multicomponent. Although BTEX compounds have similar chemical structures, biodegradation of individual BTEX is different with the present of certain BTEX compounds. The biodegradation rate is order to Benzene=Toluene>Ethylbenzene> m, p-Xylene>o-Xylene. Xylenes is stimulated when benzene or toluene is present. Especially o-xylene Inhibit other BTEX compounds.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.5
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• pp.545-552
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• 2000

Eight aromatic hydrocarbons were quantified in a newly constructed building before occupancy during the period of November 1997 to January 1998. Air samples were collected in 6 L stainless steel canisters for 8 hours based on working hour. It was found that the measured total concentration of aromatic hydrocarbons decreases rapidly with time up to a steady-state value. However, the fractions for each aromatic hydrocarbon were greatly changed with time. The concentration ratios of indoor to outdoor for aromatic hydrocarbons are greater than 1 during early period of the measurement, and the ratios decrease with time. The concentrations of toluene, m+p-xylene, ethylbenzene, and o-xylene are much higher than those of styrene, 1, 2, 4-trimethylbenzene, and 1, 3, 5-f trimethylbenzene in indoor air. The concentration fractions of m+p-xylene, ethylbenzed, and o-xylene in indoor air are about twice as hight as those in outdoor air measured during the similar period. It was concluded that the aromatic hydrocarbons were emitted from building materials, paints, and adhesives in an-built building.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.1
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• pp.25-29
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• 2000

The present study evaluated the body burden of aromatic VOCs in roadside and underground storekeepers. The Method Detection Limit(MDL) of the analytical system ranged from 0.2 to 0.4$\mu\textrm{g}$/m3 for the target VOCs. The recovery of the sampling system for the compounds was above 80%. For all the target compounds, the breath concentrations of the smokes were similar to or slightly higher than those of the nonsmokers for both the roadside and underground storekeepers. For Ethylbenzene, p-Xylene, and o-Xylene, the breath concentrations of the underground storekeepers were somewhat higher than those of the roadside storekeepers. In contrast, the breath m-xylene concentration of underground storekeepers was similar to that of roadside storekeepers. For both the roadside and underground storekeepers, the breath concentrations prior to and after work were not significantly different.

• Journal of Life Science
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• v.9 no.6
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• pp.715-721
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• 1999

The biodegradative potentialities of a toluene-tolerant Pseudomonas sp. BCNU 154, isolated from waste water, were investigated. Among 16 aromatic substrates tested, cumene, cyclohexane, ethylbenzene, p-xylene, m-xyene, toluene and diphenylether were metabolized. Pseudomonas sp. BCNU 154 degraded aerobically toluene, ethylbenzene, p-xylene and cumene. With toluene competitive degradation occurred after 12 hours, but with p-xylene and cumene, and with ethylbenzene, 90 and 75% degradation occurred after 12 hours of incubation, respectively.

• Journal of Microbiology
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• v.38 no.1
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• pp.31-35
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• 2000

A suitable packing material for biofiltration of monoaromatic solvent vapors was selected among various types of packing materials such as peat, bark chips, vermiculite, and Hydroballs. A previously isolated strain, Pseudomonas pseudoalcaligenes BTXO2, which could utilize toluene, m-and p-xylene as carbon and energy sources was used as a biofilter inoculum. Four glass biofilters (6 cm dia. x 60 cm) were individually packed with each of the packing materials and solvent vapors were passed through the columns. During three weeks of peat biofilter operation, average removal efficiencies of toluene, m-and p-xylene were 90.4%, 95.3%, and 82.1%, respectively. With the other packings, the efficiencies were in the range of 10.1 to 58.6％ which were significantly lower than those of the peat biofilter. The peat biofilter was continually operated for approximately nine months and the biofilter sustained its degradation activity during the operation period with minimal maintenance. At steady state, average removal rates of toluene, m- and p-xylene vapors were estimated as 14.2, 5.5, and 8.1 g m$\^$-3/ packing h$\^$-1/, respectively.

• Toxicological Research
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• v.12 no.1
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• pp.9-15
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• 1996

We studied the effects of a single, combined and mixed exposure of benzene, toluene and xylene on the activities of rat liver microsomal AHH, ADH and ALDH, and the excretion of their metabolites in urine. The AHH activities of the rats treated in combination and mixture were slightly higher and/or similar to those rats treated with single solvent, while the reverse effects were observed for ADH and ALDH. Similar effects were observed when the metabolites were examined in urine (p < 0.01). These results suggest that each solvent might interJkre the induction and action of ADH and ALDH, and decrease the excretion of their metabolites into urine.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.625-628
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• 1991

Using uniform flat plate-like samples of ZSM-5 zeolites, diffusion coefficients were measured volumetrically for the diffusion of xylene, ethyltoluene and diethylbenzene by direct measurement of sorption rate. Toluene disproportionation over H(100)-, K(72)-and Cs(82)-ZSM-5 at 773 K and toluene methylation, toluene ethylation and ethylbenzene ethylation over Cs(75)-ZSM-5 at 623 K were carried out. The selective formation of para xylene during the toluene disproportionation, presumably due to the increased tortuosity over Cs-ZSM-5, could be explained by smaller diffusion coefficient in Cs-ZSM-5 than in K-and H-ZSM-5. The para selectivity increased in the order; toluene methylation < toluene ethylation < ethylbenzene ethylation. As the chain length of the alkyl substituent in dialkylbenzenes is increased, the para selectivity of the products was improved. It may be attributed to the differences in the ratios of diffusion coefficient of para products to that of ortho ones. Diffusion coefficient of m-xylene was about 1 order of magnitude smaller than that of o-xylene.

• Proceedings of the Korean Environmental Health Society Conference
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• 2001.04a
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• pp.119-119
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• 2001

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.417-423
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• 2010

In this study, an effective method to prepare granular binderless ZSM-5 which is as efficient p-xylene separatory adsorbent was explored. Colloidal silica sol 30 wt% solution as an inorganic binder and microcrystalline cellulose as an organic additive were added to ZSM-5 powder ($SiO_2/Al_2O_3$ = 50). Adsorbent with enough strength (0.721 kgf), high crystallinity (94.6%) and high BET specific surface area ($379.2m^2$/g) was obtained by calcination, binderless treatment, ${NH_4}^+$ ion exchange, and activation after spherical granulation process. A batch type adsorption experiment was proceeded with solutions comprising 3 xylene isomers by 1 : 1 : 1 weight ratio to evaluate adsorption characteristics of prepared absorbent. As a result, the obtained binderless ZSM-5 granule showed a higher selective adsorption performance for para-xylene than that of commercial adsorbent.

• Journal of Preventive Medicine and Public Health
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• v.37 no.4
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• pp.321-328
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• 2004

Objectives : The purpose of this study was to investigate the effect of genetic polymorphism of cytochrome P450 2E1 (CYP2E1) and aldehyde dehydrogenase 2 (ALDH2) on the xylene metabolism. Methods : Among 247 workers, 116 were occupationally exposed to xylene and 131 were not. Workers exposed to xylene had different work such as spray, touch-up, mix & assist, and pre-treat. Questionnaire variables were age, sex, use of personal protective equipment, smoking, previous night's drinking and work duration. The urinary methylhippuric acid was measured in the urine collected in the afternoon and corrected by urinary creatinine concentration. The genotypes of CYP2E1 and ALDH2 were investigated by using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) methods with DNA extracted from venous blood. Results : 1. The urinary concentrations of o-, m-, and p-methylhippuric acid and total methylhippuric acid in the exposed group were significantly higher than those in the non-exposed group (p<0.001). 2. In multiple regression analysis, the urinary methylhippuric acid concentration was significantly influenced by exposure grade (Job-exposure matrixes), smoking, drug use and kind of protective equipment (p<0.1). 3. Genetic polymorphism of CYP2E1 and ALDH2 did not affect urinary methylhippuric acid level in the exposed group (p>0.05). Conclusions : Exposure grade, smoking, drug use and kind of protective equipment affected urinary methylhippuric acid level, whereas genetic polymorphism of CYP2E1 and ALDH2 did not. However, further investigation for the effect of genetic polymorphism on the metabolism of xylene with a larger sample size is needed.