• Title/Summary/Keyword: o-xylene

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Substrate Utilization Patterns During BTEX Biodegradation by an o-Xylene-Degrading Bacterium Ralstonia sp. PHS1

  • Lee, Sung-Kuk;Lee, Sun-Bok
    • Journal of Microbiology and Biotechnology
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    • v.12 no.6
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    • pp.909-915
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    • 2002
  • The biodegradation of BTEX components (benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene) individually and in mixtures was investigated using the o-xylene-degrading thermo-tolerant bacterium Ralsronia sp. strain PHS1 , which utilizes benzene, toluene, ethylbenzene, or o-xylene as its sole carbon source. The results showed that as a single substrate for growth, benzene was superior to both toluene and ethylbenzene. While growth inhibition was severe at higher o-xylene concentrations, no inhibition was observed (up to 100 mg $l^-1$) with ethylbenzene. In mixtures of BTEX compounds, the PHS1 culture was shown to degrade all six BTEX components and the degradation rates were in the order of benzene, toluene, o-xylene, ethylbenzene, and m- and p-xylene. m-Xylene and p-xylene were found to be co-metabolized by this microorganism in the presence of the growth-supporting BTEX compounds. In binary mixtures containing the growth substrates (benzene, toluene, ethylbenzene. and o-xylene), PHS1 degraded each BTEX compound faster when it was alone than when it was a component of a BTEX mixture, although the degree of inhibition varied according to the substrates in the mixtures. p-Xylene was shown to be the most potent inhibitor of BTEX biodegradation in binary mixtures. On the other hand, the degradation rates of the non-growth substrates (m-xylene and p-xylene) were significantly enhanced by the addition of growth substrates. The substrate utilization patterns between PHS1 and other microorganisms were also examined.

The Investigation of Biodegradation Characteristics of Xylene by Soil Inhabited Microorganisms (토양 서식 미생물을 이용한 자일렌(xylene) 분해특성 조사)

  • Choi, Phil-Kweon;Heo, Pyeung;Lee, Sang-Seob
    • Journal of Korean Society of Environmental Engineers
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    • v.35 no.6
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    • pp.389-393
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    • 2013
  • The purpose of this study is to investigate the biodegradation characteristics of the xylene by BTEX-degrading bacteria, Pseudomonas putida BJ10, isolated from oil-contaminated soil and bio-degradation pathway of the xylene. The removal efficiencies of o, m, p-xylene in mineral salts medium (MSM) by P. putida BJ10 were 94, 90 and 98%, respectively for 24 hours. It shows clear difference compared with the control groups which were below 3%. The removal efficiencies of BTEX by P. putida BJ10 in gasoline-contaminated soil were 66% for 9 days. They were clearly distinguished from the control groups (control and sterilized soil) which were 32 and 8%. 3-methylcatechol and o-toluic acid were detected after 6 and 24 hours during the o-xylene biodegradation pathway. Therefore, we confirmed o-toluic acid as the final metabolite. And intermediate-products were somewhat different with previously published studies of the transformation pathway from o-xylene to 3-methylcatechol.

Biodegradation of BTEX (benzene, toluene, ethylbenzene, xylene isomers) from organic solvent tolerant bacterium, Pseudomonas savastanoi BCNU 106

  • Kim, Jong-Su;Park, Hyeong-Cheol;Jo, Su-Dong;Kim, Gi-Uk;Bae, Yun-Wi;Mun, Ja-Yeong;Jeong, Yeong-Gi;Ju, U-Hong
    • 한국생물공학회:학술대회논문집
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    • 2003.04a
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    • pp.386-389
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    • 2003
  • Organic solvent tolerance bacteria, Pseudomonas savastanoi BCNU 106 could utilize a high contentration of benzene, toluene, ethylbenzene, xylene isomers (BTEX) as a sole carbon source. It was founded that strain BCNU 106 transformed o-xylene to 2-methylbenzyl alcohol, 2-methylbenzoic acid through direct oxygenation of methyl residue on GC-MS analysis.

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Synthesis of o-Xylene-Organosilicon Hybrid Polymer and Its Optical Properties

  • Choi, Jin-Kyu;Jeong, Hyun-Dam
    • Bulletin of the Korean Chemical Society
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    • v.34 no.2
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    • pp.515-518
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    • 2013
  • We present synthesis of a new kind of organic-inorganic hybrid polymer, poly xylene-hexamethyltrisiloxane hybrid (PXS) by a new synthetic way from o-xylene and 1,1,3,3,5,5-hexamethyltrisiloxane. The merged molecular structure of the two monomeric components for the PXS polymer was confirmed by $^{13}C$- and $^1H$-NMR, and FT-IR. Its optical absorption and emission properties were investigated by UV-vis absorption and photoluminescence (PL) spectroscopy. The PXS exhibits absorption at 265 nm which is the same with the o-xylene but tailing up to nearly 400 nm, which is maybe related the polymeric structure of the PXS. For the PL investigation, the PXS shows red-shift of the peak from 288 nm (o-xylene) to 372 nm in the case of excitation at 265 nm, at which both PXS and o-xylene have sufficiently high absorption for excitation. When 325-nm laser is used for excitation, the PXS shows a broader peak at 395 nm compared to the excitation at 265 nm and the o-xylene shows no luminescence probably due to the lack of absorption at 325 nm.

Study on the Flash Point and Spontaneous Ignition Determination of 2-Propanol and O-xylene Mixtures (2-프로판올과 O-xylene 혼합물질의 인화점과 자연발화 측정에 관한 연구)

  • Kim, Tae-Young;Mok, Yeon-Su;Choi, Jae-Wook
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2011.11a
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    • pp.360-363
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    • 2011
  • 본 연구는 2-Propanol과 O-xylene의 혼합물의 인화점과 자연발화에 관한 연구이다. 인화점의 경우 2-Propanol과 O-xylene의 혼합비를 변화하여 측정하였으며, 2-Propanol은 $12^{\circ}C$를 구하였고, O-xylene는 $32^{\circ}C$를 구하였다. 자연발화의 경우 2-Propanol과 O-xylene의 농도를 변화시켜 혼합한 시료를 만들어 최저발화온도와 순간발화온도를 측정하였다.

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Xylene Sensor Using Cr-doped Cr-Co3O4 Nanoparticles Prepared by Flame Spray Pyrolysis (화염 분무 열분해법으로 합성된 Cr-Co3O4 나노입자 자일렌 가스센서)

  • Jeong, Seong-Yong;Jo, Young-Moo;Kang, Yun Chan;Lee, Jong-Heun
    • Journal of Sensor Science and Technology
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    • v.29 no.2
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    • pp.112-117
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    • 2020
  • Xylene is a hazardous volatile organic compound that should be precisely measured to monitor indoor air quality. However, the selective and sensitive detection of ppm-level xylene using oxide-semiconductor gas sensors remains a challenge. In this study, pure and Cr-doped Co3O4 nanoparticles (NPs) were prepared using flame spray pyrolysis, and their gas-sensing characteristics to 5-ppm xylene at 250 ℃ were investigated. The 4 at% Cr-doped Co3O4 NPs exhibited a high gas response to 5-ppm xylene (resistance ratio to gas and air = 39.1) and negligible cross-responses to other representative and ubiquitous indoor pollutants such as ethanol, benzene, formaldehyde, carbon monoxide, and ammonia. In this paper, the enhancement of the gas response and selectivity of Co3O4 NPs to xylene by Cr doping was discussed in relation to the catalytic promotion of the gas-sensing reaction. This sensor can be used to monitor indoor xylene.

Photocatalysis of o-, m- and p-Xylene Using Element-Enhanced Visible-Light Driven Titanium Dioxide

  • Kim, Jong-Tae;Kim, Mo-Keun;Jo, Wan-Kuen
    • Journal of Environmental Science International
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    • v.17 no.11
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    • pp.1195-1201
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    • 2008
  • Enhancing with non-metallic elemental nitrogen(N) is one of several methods that have been proposed to modify the electronic properties of bulk titanium dioxide($TiO_2$), in order to make $TiO_2$ effective under visible-light irradiation. Accordingly, current study evaluated the feasibility of applying visible-light-induced $TiO_2$ enhanced with N element to cleanse aromatic compounds, focusing on xylene isomers at indoor air quality(IAQ) levels. The N-enhanced $TiO_2$ was prepared by applying two popular processes, and they were coated by applying two well-known methods. For three o-, m-, and p-xylene, the two coating methods exhibited different photocatalytic oxidation(PCO) efficiencies. Similarly, the two N-doping processes showed different PCO efficiencies. For all three stream flow rates(SFRs), the degradation efficiencies were similar between o-xylene and m,p-xylene. The degradation efficiencies of all target compounds increased as the SFR decreased. The degradation efficiencies determined via a PCO system with N-enhanced visible-light induced $TiO_2$ was somewhat lower than that with ultraviolet(UV)-light induced unmodified $TiO_2$, which was reported by previous studies. Nevertheless, it is noteworthy that PCO efficiencies increased up to 94% for o-xylene and 97% for the m,p-xylene under lower SFR(0.5 L $min^{-1}$). Consequently, it is suggested that with appropriate SFR conditions, the visible-light-assisted photocatalytic systems could also become important tools for improving IAQ.

The Measurement and Estimation of Lower Flash Point for o-Xylene+n-Pentanol and m-Xylene+n-Hexanol Systems Using Tag Open-Cup Tester (Tag 개방식 장치를 이용한 o-Xylene+n-Pentanol 계와 m-Xylene+n-Hexanol 계의 하부인화점 측정 및 예측)

  • Ha, Dong-Myeong;Lee, Sung-Jin;Jeong, Kee-Sin
    • Journal of the Korean Institute of Gas
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    • v.14 no.5
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    • pp.19-25
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    • 2010
  • The flash points for the systems, o-xylene+n-pentanol and m-xylene+n-hexanol, were measured by using Tag open-cup tester(ASTM D1310-86). The experimental data were compared with the values calculated by the Raoult's law and the optimization method using van Laar and Wilson equations. The calculated values based on the optimization method were found to be better than those based on the Raoult's law. The predictive curve of the flash point prediction model based on the van Laar equation described the experimentally-derived data more effectively than was the case when the prediction model was based upon the Wilson equation.

Measurements of Indoor and Outdoor Volatile Organic Compounds(VOCs) Concentrations in Ambient Air (실내외 공기중 휘발성 유기화학물질(VOCs)의 농도조사에 관한 연구)

  • 신혜수;김윤신;허귀석
    • Journal of Korean Society for Atmospheric Environment
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    • v.9 no.4
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    • pp.310-319
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    • 1993
  • A pilot study was conducted in order to investigate the concentrations of indoor and outdoor VOCs (Volatile Organic Compounds) at ten homes and four building offices in Seoul during March-April, 1993. The five components of VOCs(Benzene, Toluene, Ethylbenzene, o-Xylene, m/p-Xylene) were collected using charcoal tube and were analysed using Gas Chromatography(GC) with a Flame Ionization Detector(FID). The mean concentations of indoor VOCs were shown as Benzene of 38.9 .mu.g/m$^{3}$. Toluene of 165.0 .mu.g/m$^{3}$, Ethylbenzene of 21.7 .mu.g/m$^{3}$, o-Xylene of 11.6 .mu.g/m$^{3}$ and m/p-Xylene of 29.3 .mu.g/m$^{3}$, but those corresponding that indoor levels of VOCs were higher than corresponding outdoor levels. The ratio of indoor and outdoor VOCs were higher than corresponding outdoor levels. The ratio of indoor and outdoor VOCs concentrations was 0.99 for Benzene, 1.23 for Toluene, 5.86 for Ethylbenzene, 5.23 for o-Xylene, 2.41 for m/p-Xylene in homes, while 2.02 for Benzene, 1.15 for Toulene, 0.96 for Ethylbenzene, 1.41 for o-Xylene, 1.38 for m/p-Xylene in offices, respectively. The mean concentrations of VOCs in homes were higher than those levels in offices, while the mean concentration of VOCs during active hour of occupants in a day were higher 1-3 times than the levels during non-active hour. Comparing VOCs levels by building's age, the mean concentrations of Benzene, o-Xylene and m/p-Xylene were higher in new building than old building, but the mean concentrations of Toluene and Etylbenzene in new building were lower than old building. The mean concentrations in all components of VOCs in smoking area were higher than non-smoking area. These results suggested that the VOC levels were affected by various indoor characteristics and behavioral activity of occupants.

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The Measurement of Flash Point for Unflammable-Flammable Binary Mixtures(CCl4+o-Xylene and CCl4+p-Xylene) Using Open Cup Tester (개방식 장치를 이용한 난연성-가연성 이성분계 혼합물(CCl4+o-Xylene and CCl4+p-Xylene)의 인화점 측정)

  • Kim, Chang-Seob;Lee, Sungjin;Ha, Dong-Myeong
    • Journal of Energy Engineering
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    • v.24 no.4
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    • pp.18-23
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    • 2015
  • The flash point is used to categorize inflammable liquids according to their relative flammability. The flash point is important for the safe handling, storage, and transportation of inflammable liquids. The flash point temperature of two binary liquid mixtures($CCl_4+o-xylene$ and $CCl_4+p-xylene$) has been measured for the entire concentration range using Tag open cup tester. The flash point temperature was estimated using Raoult's law, UNIQUAC model and empirical equation. The experimentally derived flash point was also compared with the predicted flash point. The empirical equation is able to estimate the flash point fairly well for $CCl_4+o-xylene$ and $CCl_4+p-xylene$ mixture.