• Title, Summary, Keyword: Isoprene

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Influence of Isoprene Emissions on Ozone Concentrations in the Greater Busan Area during a High Ozone Episode in 2006 (2006년 오존 고농도 사례 시 부산권 지역 isoprene 배출이 오존 농도에 미치는 영향 분석)

  • Kim, Yoo-Keun;Jo, Young-Soon;Song, Sang-Keun;Kang, Yoon-Hee;Oh, In-Bo
    • Journal of Environmental Science International
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    • v.19 no.7
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    • pp.829-841
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    • 2010
  • The estimation of a biogenic volatile organic compound (BVOC, especially isoprene) and the influence of isoprene emissions on ozone concentrations in the Greater Busan Area (GBA) were carried out based on a numerical modeling approach during a high ozone episode. The BVOC emissions were estimated using a biogenic emission information system (BEIS v3.14) with vegetation data provided by the forest geographical information system (FGIS), land use data provided by the environmental geographical information system (EGIS), and meteorological data simulated by the MM5. Ozone simulation was performed by two sets of simulation scenarios: (1) without (CASE1) and (2) with isoprene emissions (CASE2). The isoprene emission (82 ton $day^{-1}$) in the GBA was estimated to be the most dominant BVOC followed by methanol (56) and carbon monoxide (28). Largest impacts of isoprene emissions on the ozone concentrations (CASE2-CASE1) were predicted to be about 4 ppb in inland locations where a high isoprene was emitted and to be about 2 ppb in the downwind and/or convergence regions of wind due to both the photochemical reaction of ozone precursors (e.g., high isoprene emissions) and meteorological conditions (e.g., local transport).

A Study on Emission Rate of BVOCs from Broad-leaved Trees at Jeju Island (제주지역에 분포하는 활엽수의 BVOCs 배출특성)

  • Kim, Hyeong-Cheol;Lee, Ki-Ho
    • Journal of Environmental Science International
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    • v.21 no.6
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    • pp.713-724
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    • 2012
  • Emission rates of biogenic hydrocarbon emitted from broad-leaved trees grown at Jeju Island were estimated using a dynamic enclosure method. Leaf temperature, PAR and relative humidity were monitored during the sampling time. The emission rates of isoprene and monoterpene were measured for five plants(Carpinus laxiflora, Quercus serrata, Styrax japonicus, Quercus acutissima, Quercus crispula) during the sampling period at the Halla mountain sites. Among five tree species, the highest isoprene emission rate of 10.60 ${\mu}g\;gdw^{-1}hr^{-1}$ was observed for Quercus serrata. The seasonal emission rates were the highest during summer and the emission of isoprene was highly affected by light and temperature variations. The highest emission rate of isoprene was occurred between 13:00 and 14:00, but isoprene was not emitted in nighttime because of the absence of light.

Production of Bio-Based Isoprene by the Mevalonate Pathway Cassette in Ralstonia eutropha

  • Lee, Hyeok-Won;Park, Jung-Ho;Lee, Hee-Seok;Choi, Wonho;Seo, Sung-Hwa;Anggraini, Irika Devi;Choi, Eui-Sung;Lee, Hong-Weon
    • Journal of Microbiology and Biotechnology
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    • v.29 no.10
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    • pp.1656-1664
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    • 2019
  • Isoprene has the potential to replace some petroleum-based chemicals and can be produced through biological systems using renewable carbon sources. Ralstonia eutropha can produce value-added compounds, including intracellular polyhydroxyalkanoate (PHA) through fatty acid and lipid metabolism. In the present study, we engineered strains of R. eutropha H16 and examined the strains for isoprene production. We optimized codons of all the genes involved in isoprene synthesis by the mevalonate pathway and manipulated the promoter regions using pLac and pJ5 elements. Our results showed that isoprene productivity was higher using the J5 promoter ($1.9{\pm}0.24{\mu}g/l$) than when using the lac promoter ($1.5{\pm}0.2{\mu}g/l$). Additionally, the use of three J5 promoters was more efficient ($3.8{\pm}0.18{\mu}g/l$) for isoprene production than a one-promoter system, and could be scaled up to a 5-L batch-cultivation from a T-flask culture. Although the isoprene yield obtained in our study was insufficient to meet industrial demands, our study, for the first time, shows that R. eutropha can be modified for efficient isoprene production and lays the foundation for further optimization of the fermentation process.

Isoprene/n-pentane separation using facilitated transport membranes with SPEEK-AgNO3 (SPEEK-AgNO3로 이루어진 촉진 수송 분리 막을 사용한 isoprene/n-pentane 혼합물 분리)

  • Choi, Hyun Woo;Kim, Dong Bum;Kim, Hoon Sik;Lee, Chang Ha;Choi, Dae Ki
    • Clean Technology
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    • v.10 no.3
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    • pp.169-176
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    • 2004
  • Sulfonated ionomer membranes, sulfonated poly(ether ether)ketone (SPEEK)-$AgNO_3$, were prepared and tested for separation of the isoprene/n-pentane mixtures. The facilitated transport membranes showed good selectivity and permeance of isoprene over n-pentane and long-term stability. Depending on various reaction conditions, the degree of sulfonation (DS) of SPEEK was measured by 1H NMR spectroscopy and the performance of the membranes was affected by the DS of SPEEK as a whole. As the DS of SPEEK was increased, the selectivity of isoprene over n-pentane increased and eventually reached a maximum selectivity of 850 ~ 900 and the stability of that was continued more than 100 h.

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Study on the Polymerization Characteristics of Isoprene through Nitroxide Mediated Controlled/"living" Radical Polymerization Techniques (Nitroxide 매개 리빙라디칼 중합법에 의한 isoprene의 중합특성에 관한 연구)

  • Hong, Sung-Chul
    • Elastomers and Composites
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    • v.44 no.1
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    • pp.55-62
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    • 2009
  • In this study, investigation on the polymerization characteristics of isoprene through nitroxide mediated controlled/"living" radical polymerization techniques was attempted. In the presence of acetol, linear increase of isoprene conversion with time and low polydispersities of the resulting polymers ($M_w/M_n$ < 1.5) were observed, which suggest successful controlled/"living" radical polymerization of isoprene. The microstructure of the resulting polyisoprene was composed of $\sim$ 22% of 3, 4, $\sim$30% of 1, 4-cis and $\sim$ 48% of 1, 4-trans. The optimum polymerization temperature was 145 $^{circ}C$, below which no significant polymerization behavior was observed. Non-cyclic nitroxide, such as di-tert-butyl nitroxide (DTBN) could not mediate the polymerization, whereas cyclic nitroxides (2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (TEMPO) and 4-oxo-2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (oxoTEMPO)) were successfully employed for the polymerization. However, isoprene dimerization reaction through Diels-Alder process was also observed at the given polymerization condition, which afforded a significant amount of limonene. Isoprene thermal autoinitiation was also possible, which was, however, considered to be not significant under the given polymerization condition.

Preparation and characterization of the primary gas standards for isoprene (아이소프렌 일차표준가스의 제조 및 특성 평가)

  • Kim, Taesu;Kang, Chul-Ho;Kim, Yong Doo;Lee, Seungho;Kim, Dalho
    • Analytical Science and Technology
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    • v.27 no.6
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    • pp.357-363
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    • 2014
  • Isoprene is a one of the biogenic volatile organic compounds (BVOCs) and it is known as a source of the tropospheric ozone and formaldehyde. In addition, isoprene is a trace component of the exhaled breath and it is a potential biomarker for the diagnosis of diseases such as lung cancer. In these regards, isoprene gas standards are required for the accurate measurement of isoprene in air samples. To establish a standard for isoprene gas, gravimetric preparation and characterization of primary gas standards were studied. The primary gas standards were produced independently in 4 aluminum cylinders and concentrations were examined by GC-FID. As a result, the uncertainty of the gravimetric preparations including purity of the raw material was 0.01% and reproducibility of the preparation of independent 4 cylinders was 0.08%. The primary gas standards for isoprene showed 14 months of long-term stability. The relative expended uncertainty of 2.8% (95% of confidence level, k=1.96) was assigned to the certified value of 10 ${\mu}mol$/mol level of isoprene based on the quantitative evaluation of the purity, weighing, reproducibility, adsorption and long-term stability.

A Comparison Study on Isoprene Emission Rates from White Oak (갈참나무로부터 발생되는 이소프렌의 배출속도 비교 연구)

  • Son, Youn-Suk;Kim, Jo-Chun;Kim, Ki-Joon;Lim, Yong-Jae;SunWoo, Young;Hong, Ji-Hyung
    • Journal of Korean Society for Atmospheric Environment
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    • v.22 no.6
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    • pp.791-798
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    • 2006
  • In order to investigate the NVOC (Natural Volatile Organic Compound) emissions from White Oak, the emission rates of isoprene were measured according to season, weather conditions, and the age of the tree. The analysis of seasonal emission rates showed that the emission rates were the highest during summer followed by spring and fall. The emission rates during summer were found to be nearly 8 times greater than those during fall. In addition, it was observed that the emission rates of isoprene depends on PAR and temperature. Moreover, the effect of age on the emission rates was studied, and the White Oak in the age range of $21{\sim}30$ had higher emission rates than that in the range of $41{\sim}50$. Accordingly, the current result indicates that the isoprene emissions are affected by both meteorological parameter and the age of a tree.

CRDS Study of Tropospheric Ozone Production Kinetics : Isoprene Oxidation by Hydroxyl Radical

  • Park, Ji-Ho
    • Journal of Environmental Health Sciences
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    • v.35 no.6
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    • pp.532-537
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    • 2009
  • The tropospheric ozone production mechanism for the gas phase additive oxidation reaction of hydroxyl radical (OH) with isoprene (2-methyl-1,3-butadiene) has been studied using cavity ring-down spectroscopy (CRDS) at total pressure of 50 Torr and 298 K. The applicability of CRDS was confirmed by monitoring the shorter (~4%) ringdown time in the presence of hydroxyl radical than the ring-down time without the photolysis of hydrogen peroxide. The reaction rate constant, $(9.8{\pm}0.1){\times}10^{-11}molecule^{-1}cm^3s^{-1}$, for the addition of OH to isoprene is in good agreement with previous studies. In the presence of $O_2$ and NO, hydroxyl radical cycling has been monitored and the simulation using the recommended elementary reaction rate constants as the basis to OH cycling curve gives reasonable fit to the data.

Promises and Risks of Unsaturated Volatile Organic Compounds: Limonene, Pinene, and Isoprene

  • Jin, Kyong-Suk;Jun, Mi-Ra;Park, Min-Ji;Ok, Seon;Jeong, Jae-Han;Kang, Hye-Sook;Jo, Wan-Keun;Lim, Ho-Jin;Jeong, Woo-Sik
    • Food Science and Biotechnology
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    • v.17 no.3
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    • pp.447-456
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    • 2008
  • Limonene, pinene, and isoprene are abundant and ubiquitous volatile organic compounds (VOCs) which are found in various natural products and also produced from various manufacture processes. Limonene and pinene are major components of food additives and household products for enrichment of good flavors and elimination of malodors, and isoprene is a basal motif of monoterpenes such as limonene and pinene. They have shown many beneficial effects such as chemopreventive, chemotherapeutic, and antioxidant activities. Upon certain conditions, however, adverse effects of these compounds on human health have also been reported. Although they do not seem to have acute and severe toxicity to human, they can easily generate secondary organic aerosols (SOAs) when they react with oxygen and/or ozone, which have shown certain toxic effects on experimental animal models as well as on humans. Numerous household and scented products containing limonene, pinene, and isoprene are widely used in these days. However, biological consequences upon exposure to these products are largely unknown. The aim of this review is to summarize and analyze the current understanding on the biological effects of VOCs, in particular limonene, pinene, and isoprene, as well as their SOAs.

A Study on Processing and Physical Properties of Isoprene Rubber Involving Norbornene Dialkyl Ester (Norbornene Dialkyl Ester가 첨가된 Isoprene Rubber의 가공성 및 물성에 관한 연구)

  • Jeong, Hye-in;Jo, Nam-chol;Woo, Je-Wan
    • Applied Chemistry for Engineering
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    • v.27 no.3
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    • pp.259-264
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    • 2016
  • In this study, we applied six different norbornene dialkyl esters as a plasticizer to an isoprene rubber (IR) and evaluated replaceability of DEHP which is an endocrine disruptor. IR test sheets were prepared by blending IR, norbornene dialkyl ester, vulcanizing agent, etc. and processing properties of the IR were evaluated by measuring Toque, scorch time, cure time and mooney viscosity. Mechanical properties of IR test sheet including hardness, tensile strength, 100% modulus and elongation were also measured and the physical properties of norbornene dialkyl ester applied as a plasticizer were compared to those using DEHN. Both the maximum and minimum toque for the norbornene dialkyl ester as a plasticizer were similar to those of using DEHP. In addition, the scorch and cure time of the former were slightly longer than those of the latter. The mooney viscosity for the case of DEHN was slightly lower than that of the latter. DEHN was also superior to DEHP in terms of processing. The hardness and thermal properties of all IR test sheets were measured to be similar to each other. The linear alkyl chain of norbornene compounds also exhibited good tensile characteristics.