• 한국환경과학회지
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• 제21권1호
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• pp.11-21
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• 2012

This study investigated the characteristics of selected volatile organic compounds(VOCs) in newly-finished residential buildings, before the occupants moved in. This investigation was carried out by measuring the indoor and outdoor concentrations of selected VOCs before the occupants moved in and by utilizing an indoor mass balance model. Among 25 target VOCs, five aromatics(benzene, ethyl benzene, toluene, m,p-xylene, and o-xylene) were detected in all samples of both indoor and outdoor air. Toluene was most abundant VOC in the indoor air of new apartments, with a median value of 168 mg $m^{-3}$. Unlike other VOCs, halogenated compounds would not be significantly emitted from building materials. The indoor air concentrations of all selected VOCs, except for 1,3,5-trimethyl benzene, exhibited significant correlations each other, while for outdoor air concentrations, five aromatics only were significantly correlated between them. The emission rate of toluene was higher for the current study(median value, 76.8 mg $m^{-2}\;h^{-1}$) than for a previous study, while the emission rates of limonene, a-pinene and b-pinene(geometric means of 2.4, 13.8 and 9.6 mg $m^{-2}\;h^{-1}$, respectively) were lower and the emission rates of m,p-xylene and 2-butanone(geometric means of 10.9 and 21.3 mg $m^{-2}\;h^{-1}$, respectively) were similar. Although there were a few exceptions, the emission strengths are likely proportional to indoor temperature, and appear to reversely proportional to air exchange rate.

• 한국환경과학회지
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• 제17권7호
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• pp.767-774
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• 2008

This study was carried out to evaluate the characteristics of atmospheric concentrations of volatile organic compounds(VOCs) and aldehydes for near a large shipyard. Most of the painting work in marine coating is performed indoor and outdoor. Most of the VOCs are emitted to the atmosphere as the paint is applied and cures. The massive scale of a ship makes it difficult to capture the emissions from outdoor painting. The VOCs are an important health and contributors to photochemical smog. The VOCs and aldehydes samples were collected using adsorbent tube and 2,4-DNPH cartridge, and were determined by an automatic thermal desorption coupled with GC/MS and HPLC-UV analysis, respectively. A total of 16 aromatic VOCs and 12 aldehydes of environmental concern were determined. At indoor coating facilities, the most abundant compound among 16 target VOCs appeared to be m,p-xylene, being followed by o-xylene. But most of the aldehydes were extremely lower concentrations. The atmospheric concentration of VOCs, m,p-xylene concentrations were the highest and the mean value were outdoor workshop 11.323 ppb, residental area 5.134 ppb, and green area 2.137 ppb, respectively. However, the most aldehydes were extremely lower concentrations such as formaldehyde, acetaldehyde and non-detection such as iso-valeraldehyde, n-valeraldehyde and o-tolualdehyde.

• 센서학회지
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• 제23권3호
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• pp.211-215
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• 2014

The Pt-, Ni- and Cr-decorated tubular $SnO_2$ nanofibers for gas sensors were prepared by the electrospinning of polyvinylpyrrolidone (PVP) nanofibers containing Pt, Ni, and Cr precursors, the sputtering of $SnO_2$ on the electrospun PVP nanofibers, and the removal of sacrificial PVP parts by heat treatment at $600^{\circ}C$ for 2 h. Pt-decorated tubular $SnO_2$ nanofibers showed high response ($R_a/R_g=210.5$, $R_g$: resistance in gas, $R_a$: resistance in air) to 5 ppm $C_2H_5OH$ at $350^{\circ}C$ with negligible cross-responses to other interference gases (5 ppm trimethylamine, $NH_3$, HCHO, p-xylene, toluene and benzene). Cr-decorated tubular $SnO_2$nanofibers showed the selective detection of p-xylene at $400^{\circ}C$. In contrast, no significant selectivity to a specific gas was found in Ni-decorated tubular $SnO_2$ nanofibers. The selective and sensitive detection of gases using Pt-decorated and Cr-decorated tubular $SnO_2$ nanofibers were discussed in relation to the catalytic promotion of gas sensing reaction.

• Korean Chemical Engineering Research
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• 제51권4호
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• pp.476-481
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• 2013

본 연구에서는 물리적 특성이 유사한 에틸벤젠과 파라자일렌의 혼합물을 분리하고자 MFI형 제올라이트(TS-1, ZSM-5, Silicalite-1) 분리막을 제조하였으며 이를 이용하여 기상에서 분리 실험을 진행하였다. 제올라이트 입자가 코팅된 분리막을 제조함에 있어서 마이크로웨이브 합성 방법을 사용하여 합성 시간을 단축하였으며, 500 nm 내외의 균일한 입자를 튜브타입의 지지체 막에 안착시켜 제올라이트 입자가 $3{\sim}4{\mu}m$ 두께로 치밀하게 코팅된 분리막을 제조하였다. 제조한 분리막으로 에틸벤젠/파라자일렌 혼합물 원료의 혼합비를 변경하여 투과 분리한 결과 에틸벤젠:파라자일렌=5:5 비율에서 가장 높은 분리도를 가짐을 알 수 있었다. 세 종류의 서로 다른 제올라이트 물질(TS-1, ZSM-5, Silicalite-1)을 각각 코팅하여 제조된 분리막을 이용하여 $160{\sim}220^{\circ}C$의 실험온도에서 에틸벤젠/파라자일렌을 투과 실험을 실시한 결과, TS-1 분리막이 $1,666mol/m^{2*}s^*Pa$의 가장 높은 투과 플럭스를, Silicalite-1 분리막이 1.73의 가장 높은 분리도를 $200^{\circ}C$의 온도에서 각각 보임을 확인할 수 있었다.

• 한국재료학회지
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• 제26권6호
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• pp.320-324
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• 2016

Porous SiC beads were prepared by freeze-drying a polycarbosilane (PCS) emulsion. The water-in-oil (w/o) emulsion, which was composed of water, PCS dissolved p-xylene, and sodium xylenesulfonate (SXS) as an emulsifier, was frozen by dropping it onto a liquid $N_2$ bath; this process resulted in 1~2 mm sized beads. Beads were cured at $200^{\circ}C$ for 1 h in air and heat-treated at $800^{\circ}C$ and $1400^{\circ}C$ for 1 h in an Ar gas flow. Two types of pores, lamella-shaped and spherical pores, were observed. Lamellar-shaped pores were found to develop during the freezing of the xylene solvent. Water droplets in the w/o emulsion were changed into spherical pores under freeze-drying. At $1400^{\circ}C$ of heat-treatment, porous SiC was synthesized with a low level of impurities.

• 한국환경과학회지
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• 제14권1호
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• pp.81-89
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• 2005

As a typical example of simultaneous analysis of the odorous compounds, the volatile organic compounds from inventory sources in Seongseo industrial area were concentrated and analyzed with thermal desorber/GC/MSD, and major malodorous compounds were estimated. Odor intensity and odor concentration was analyzed simultaneously During a period from November in 2002 to December in 2003, this study was conducted to evaluate malodor emission characterization in major treatment facilities. The major components were Dimethyl sulfide, Dimethyl disulfide, Methyl mercaptane, Ammonia, Benzene, Toluene, m,p-xylene, o-xylene, Styrene, 1,2,4­T.M.B and 1,3,5-T.M.B. Among the six major inventory sources, the odor unit concentration of Night-soil disposal facilities was the highest, $669\~2344\;ou/m^{3}.$

• 한국대기환경학회지
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• 제23권3호
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• pp.286-296
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• 2007

Ozone creation potentials suited for Seoul metropolitan area was derived by utilizing the PAMS monitoring data and the source inventory. A simple box model with variable height was developed to calculate the incremental reactivity for all the ozone episode days in the year 2003 and 2004. RIR (Relative Incremental Reactivity) was introduced as a measure of contribution to ozone generation in the Seoul metropolitan area. RIR was defined as a function of ratio of VOC to $NO_x$ and therefore it addresses both VOC and $NO_x$ limited regime. For the days that more than 10 monitoring stations out of 27 monitoring station in Seoul recorded the daily maximum ozone concentrations higher than 70 ppb, toluene had the highest RIR value in all the type II and type III PAMS site and m/p-xylene followed with the second highest RIR value. Analyses using MIR (Maximum Incremental Reactivity) and POCP (Photochemical Ozone Creation Potential) instead of RIR also yields dominance of toluene and m/p-xylene in generating ozone concentrations to demonstrate the validity of RIR.

• Korean Chemical Engineering Research
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• 제51권2호
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• pp.233-239
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• 2013

Poly(isobutylene), polystyrene 및 poly(methyl methacrylate)로 코팅된 quartz crystal microbalance(QCM) 시스템을 구성하여, 매우 낮은 압력에서 benzene, toluene, p-xylene의 흡착량을 측정하였다. 모든 흡착실험에서 QCM 시스템의 공진 주파수 변화는 압력의 증가에 비례하였다. 실험결과로부터 각각의 고분자 필름에 대한 흡착물질의 Henry 상수를 구하였으며 고분자 필름과 흡착물질 사이의 최소 흡착 포텐셜 에너지와 비교하였다. 전체적으로 흡착량과 최소 흡착 포텐셜 에너지는 명백한 상관관계가 있었다.

• 센서학회지
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• 제26권3호
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• pp.204-208
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• 2017

Highly uniform and well-dispersed Zeolitic Imidazolate Framework-7 (ZIF-7) particles were prepared by the precipitation of $Zn^{2+}$ using benzimidazole, which were converted into ZnO nanoparticles by heat treatment at $500^{\circ}C$ for 24 h. The ZIF-7 derived ZnO nanoparticles showed abundant mesopores, high surface area, and good dispersion. The gas sensing characteristics toward 5 ppm acetone, ethanol, trimethylamine, ammonia, p-xylene, toluene, benzene, and carbon monoxide and carbon dioxide were investigated at $350-450^{\circ}C$. ZIF-7 derived ZnO nanoparticles exhibited high response to 5 ppm acetone ($R_a/R_g=57.6$; $R_a$: resistance under exposure to the air, Rg: resistance under exposure to the gas) at $450^{\circ}C$ and negligible cross-responses to other interference gases (trimethylamine, ammonia, p-xylene, toluene, benzene, carbon monoxide, carbon dioxide) and relatively low responses to ethanol. ZIF derived synthesis of metal oxide nanoparticles can be used to design high performance acetone sensors.

• 한국안광학회지
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• 제8권2호
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• pp.31-35
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• 2003

몇 가지 합성한 poly(6-dialkylamino-1,3,5-triazine-2,4-dithioxylene) 유도체들은 poly(6-dialkylamino-1,3,5-triazine-2,4-dithiol과 m- 또는 p-dibromide xylene으로부터 $70^{\circ}C$에서 약 24시간 동안 cetyltrimethyl ammo-nium bromide와 중축합반응 시켜서 얻었다. 합성해서 얻은 유도체들의 굴절률이 97~196.6을 보였으며, 물흡광계수는 97~196.6범위에서 나타났다. 따라서 이들 고분자 유도체들이 높은 전자밀도를 가지는 황 원자와 트리아진 고리를 가지므로 인해 복굴절 현상이 없으면서 높은 굴절률을 가진다는 것을 알았다.