• Title/Summary/Keyword: 염소계화합물

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Production of Ethylbenzene from 4-Vinylcyclohexene (4-비닐시클로헥센을 이용한 에틸벤젠의 제조)

  • Joo, Young J.;Won, Jeong-Im;Kim, Chang-Min;Park, Kwang-Chun;Lee, Sang-Ok;Kim, Hong-Seok
    • Applied Chemistry for Engineering
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    • v.7 no.2
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    • pp.326-333
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    • 1996
  • Dehydrogenation of 4-vinylcyclohexene(4-VCH) to ethylbenzene is elucidated via catalytic transfer hydrogenation with the heterogeneous catalyst of Pd/C. Hydrogen-donor solvent is ethanol or water. Oxidizers of the catalytic dehydrogenation reaction are mono- or dinitro compounds, $H_2O_2$, NaClOn (n=1~4), or oxygen at $70{\sim}110^{\circ}C$. The ratio of 4-VCH/Nitro compounds is 1:0.02 to 1:0.5 and 4-VCH vs. $H_2O_2$ or NaClOn (n=1~4) is 1:0.1 to 1:3.

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Application of PAC-Membrane System for Treating Groundwater Contaminated with Chlorinated Organic Compounds (유기염소화합물로 오염된 지하수를 처리하기 위한 PAC-막분리 공정의 적용)

  • Lim, Joong-Kun;Kang, Min-Su;Kang, Lim-Seok
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.8
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    • pp.892-899
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    • 2005
  • Groundwater is naturally of excellent microbiological qualify and generally of adequate quality for drinking water use. However, recently, the impact of urbanization and intensification of agricultural production have led to serious deterioration in groundwater quality. The representative SOCs used in this study were trichloroethylene (TCE) and tetrachloroethylene (PCE). Powdered activated carbon (PAC) is widely used for SOCs removal. The overall goal of this study was to demonstrate the feasibility of using a hybrid use of PAC-UF and PAC-MF processes for treating groundwater contaminated with TCE and PCE. The results show that the flux decline rate was lower for the PAC-UF or PAC-MF process than for UF or MF only process. Therefore, applying PAC before UF or MF membrane filtration showed not only enhancing the removal of TCE and PCE, but also reducing membrane fouling.

Reductive Degradation Kinetics and Pathways of Chlorophenolic Organic Pollutants by Nickel-Coated Zero Valent Iron (니켈로 코팅된 영가금속을 이용한 염소계 페놀화합물의 반응경로 및 반응율 평가)

  • Shin, Seung-Chul;Kim, Young-Hun;Ko, Seok-Oh
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.5
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    • pp.487-493
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    • 2006
  • Reductive dechlorination of chlorophenols by nickel coated iron was investigated to understand the feasibility of using Ni/Fe for the in situ remediation of contaminated groundwater. Zero Valent Iron(ZVI) was amended with Ni(II) ions to form bimetal(Ni/Fe). Dechlorination of five chlorophenol compounds and formation of intermediates were examined using Ni/Fe. Rate constant for each reaction pathway was quantified by the numerical integration of a series of differential rate equation. Experimental results showed that the sequence of hydrodechlorination rate constant was in the order of 2-CP>4-CP>2,4-DCP>2,4,6-TCP>2,6-DCP. The hydrodechlorination pathways for the conversion of each chlorophenol compound involves a full dechlorination to phenol via both concerted and stepwise mechanisms. Reaction pathways and corresponding kinetic rate constants were suggested based on the experiments and numerical simulations.

Reductive degradation of Chlorinated compounds by using Iron Minerals (철 광물에 의한 염소계 유기화합물의 환원적분해)

  • Kim, Sung-Kuk;Park, Sang-Won
    • Journal of Soil and Groundwater Environment
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    • v.9 no.2
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    • pp.11-19
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    • 2004
  • Chlorinated and nitroaromatic compounds are non-degradable substances that are extremely toxic and are known to be carcinogens and mutation causing agents. Moreover, the half-lives of substances such as carbon tetrachloride, hexachloroethane and nitroaromatic compounds are several decades. In this study, the optimal conditions to detoxify chlorinated compounds by the reductive degradation were investigated. The following results were obtained in the reductive degradation of CCl$_4$, C$_2$Cl$\_$6/, C$_2$HCl$\_$5/, C$_2$Cl$_4$, and C$_2$HCl$\_$5/ by using Fe, FeS and FeS$_2$ as mediators. CCl$_4$ was reduced to CH$_2$Cl$_3$ and CH$_2$Cl$_2$in anaerobic conditions when FeS was used as a mediator. While the reduction of CCl$_4$ to CHCl$_3$ was rapidly proceeded, the reduction of CHCl$_3$ to CH$_2$Cl$_2$ was occurred slowly. Further reduction to CH$_3$Cl was not observed. Unlike CCl$_4$, C$_2$Cl$\_$6/ was degraded to C$_2$HCl$\_$5/, C$_2$Cl$_4$. C$_2$HCl$_3$ and cis-1,2-C$_2$H$_2$Cl$_2$ by complicated pathways such as hydrogenolysis, dehalo-elimination and dehydrohalogenation. A small amount of C$_2$HCl$\_$5/ was detected only in the early stages of the reduction. However, majority of the C$_2$Cl$\_$6/ was reduced to C$_2$Cl$_4$. cis-1,2-C$_2$H$_2$C1$_2$ was the only product among other possible isomers.

A Study on Applicability of Hydrofluoroethers as CFC-Alternative Cleaning Agents (CFC 대체 산업세정제로의 HFEs의 적용가능성 연구)

  • Min, Hye-Jin;Shin, Jin-Ho;Bae, Jae-Heum;Kim, Hong-Gon;Lee, Hyun-Joo
    • Clean Technology
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    • v.14 no.3
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    • pp.184-192
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    • 2008
  • Fluoride-type cleaning agents such as 2,2,2-trifluoroethanol (TFEA) and hydrofluoroethers (HFEs) do not destroy ozone in the stratosphere and have low global warming potential compared to hydrofluorocarbons(HFCs) and hydrochlorofluorocarbons (HCFCs). Especially, HFEs which have no flash point are paid attention as next generation type of cleaning agents for chlorofluorocarbons (CFCs) since they are safe in handling and have excellent penetration ability compared to hydrocarbon cleaning agents with low flash point. Here, the physical properties and cleaning abilities of fluoride-type cleaning agents such as TFEA, HFE-7100, HFE-7200, HFE-476mec, HFE-449mec-f, AE-3000 and AE-3100E and silicide-type cleaning agents such as trifluoroetoxytrimethylsilane (TFES) and hexamethyldisilazane (HMDS) were measured and compared with those of ozone destruction substances such as CFC-113 and 1,1,1-trichloroethane. They were also compared with toxic methylene chloride (MC) and isopropyl alcohol (IPA) which are now being used as an alternative cleaning agents. As a result, TFEA and HFEs had lower cleaning ability for removal of various soils compared to chloride-type cleaning agents, but they showed excellent cleaning ability fur fluoride-type soils. TFES and HMDS also showed excellent cleaning ability for silicide-type soils.

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Quenching Curves for VOCs in the Analysis of Groundwater $^{14}C$ using Liquid Scintillation Counter (액체섬광계수기를 이용한 지하수의 $^{14}C$ 측정에서 휘발성유기화합물(VOC)에 대한 소광곡선)

  • Lee, Kil-Yong;Cho, Soo-Young;Yoon, Yoon-Yeol;Ko, Kyung-Seok;Kim, Yong-Je
    • Journal of Soil and Groundwater Environment
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    • v.12 no.6
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    • pp.53-59
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    • 2007
  • Optimal quenching curves have been studied for the accurate analysis of $^{14}C$ in groundwater polluted by reducing efficiency of volatile organic compounds (VOCs) in liquid scintillation counter (LSC). The quenching parameters (SQP(E)) were measured for ten VOCs such as benzene, toluene, ethylbenzene, o-(m-,p-)xylene, trichloroethylene (TCE), tetrachloroethylene(PCE), carbon tetrachloride and chloroform. The quenching curves were plotted using $^{14}C$ standard solution and chloroform as a quenching agent. Optimal plotting conditions were determined for standard solution, LSC measuring time and the concentration of chloroform. The quenching effects of chlorinated organic compounds such as TCE, PCE, carbon tetrachloride and chloroform were greater than those of BTEX (benzene, toluene, ethylbenzene and xylene). Optimum measuring time was 100 minutes far 7,000 dpm/mL standard solution. A few mL of chloroform should be added for good quenching curves. These quenching curves have good correlation coefficients (> 0.99) and the curves could be applied to accurate analysis of $^{14}C$ in groundwater and tap water.

Biological Treatment of Wastewater Containing Chlorinated Phenols by a Mixed Culture (복합미생물제재를 이용한 염소화 페놀계 폐수의 생물학적 처리)

  • 오희목;이완석;정상욱;박찬선;윤병대;김장억
    • Microbiology and Biotechnology Letters
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    • v.29 no.2
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    • pp.115-121
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    • 2001
  • Biological Treatment of Wastewater Containing Chlorinated Phenols by a Mixed Culture. Lee, Wan-Seok1, Sang-Wook Jung, Chan-Sun Park, Byung-Dae Yoon, Jang-Eok Kim\ and Hee-Mock Oh*. Environmental Bioresources Laboratory, Korea Research Institute of Biosicence and Biotechnology, Taejon, Korea, 1 Department of Agricultural Chemistry, Kyungpool< National University, Taegu, Korea - The biodegradation of chlorinated phenols in an artificial wastewater was investigated using a mixed culture. The mixed culture was composed of 8 microorganisms isolated from the soil contaminated with various chlorinated phenols. Pseudomonas sp. BM as a main constituent of a mixed culture was Gram-negative, catalase- and oxidase-positive, and rod-shaped, and did not grow at 41°C. It degraded 99% of initial 500 mg!1 of pentachlorophenol (PCP) in the minimal salts medium as a sole source of carbon and energy within 3 days. The degradation efficiency of Pseu.domon.as sp. BM was not affected by the other organic carbon and nitrogen compounds. Pseudomonas sp. BM was able to grow in a broad range of pH 5 - 8, and degrade 2,000 mg/1 PCP. In the experiment with an artificial wastewater containing chlorinated phenols, the degradation efficiency of the mixed culture was the range of 73% (2,4-dichlorophenol) -96% (2-chlorophenol) during an incubation of 7 days. In a continuous culture experiment, the degradation efficiency of mixed culture plus activated sludge was about 2 times higher than that of the control containing only activated sludge. These results indicate that it is possible to apply the mixed culture to other wastewaters containing chlorinated phenols. Key words: Biodegradation, chlorinated phenols, pentachlorophenol, Pseudomonas sp. BM

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Evaporation of Volatile Chlorinated Hydrocarbons in Soils (토양의 휘발성 염화 탄화수소 화합물 증발)

  • Lee, Junho;Park, Kapsong
    • Journal of Korean Society on Water Environment
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    • v.24 no.1
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    • pp.78-85
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    • 2008
  • Evaporation of selected toxic volatile chlorinated hydrocarbons was studied in laboratory soil columns. The evaporation values were obtained for the ten volatile chlorinated hydrocarbons at two different temperatures ($12^{\circ}C$ and $21^{\circ}C$) from columns filled with silty clay loam and sandy loam soils. 1,1,1-Trichloroethane, trichloroethylene and chloroform evaporated considerably (36.7~54.6% removal), carbon tetrachloride, 1,2-dichlorobenzene, tetrachloroethylene, 1,3-dichlorobenzene, dichlorobromethane and dibromochloromethane to a lesser extent (15.3~39.3% removal), and bromoform evaporated poorly (<10 percent removal) at both temperature. Volatile chlorinated hydrocarbons concentration did not affect evaporation, no statistically significant difference in evaporation between the soil types was found. However, temperature affected evaporation, the effect of concentration on the evaporation was not conclusive.

Biodegradation of PCBs into Contaminated Dredged Sediments (오염퇴적물에 함유된 PCBs의 생물분해 특성)

  • 안재환;김소정;지재성;배우근;황병기
    • Journal of Soil and Groundwater Environment
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    • v.9 no.2
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    • pp.41-47
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    • 2004
  • This research in the degradation of polychlorinated biphenyls(PCB) has focussed on the use of experimental enrichment cultures to obtain PCB-deading communities and identification of PCB-degrading bacteria accor야ng to pure culture. During 180 days, enrichment culture was performed to obtain PCB-degrading bacteria and initial concentration was injected 1.6 ppm,0.7 ppm, respectively. After 180 days of enrichment culture, PCBs was removed 80-87% and 57-71%. Biodegradation of PCBs was studied according to dominated PCB-degrading bacteria. Biodegraddation of PCBs was 80% in initial concentration of PCBs for 20days, enrichment cultured PCB-degrading bacteria was isolated by pure culture and it was verified to Pseudoxanthomonas sp.

Distribution of PCDDs/PCDFs in the Ambient Air of Seoul (서울시내 환경대기 중 다이옥신 농도 분포 조사)

  • 엄정훈;최용석;유인철;정종흡;윤중섭;김민영
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2003.11a
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    • pp.411-412
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    • 2003
  • 다이옥신은 주로 연소과정에서 소각부산물로 생성되는 염소계 유기화합물로서 이들의 최종 수용체는 토양이나 저질이 되지만 최초 배출형태는 주로 대기오염물의 특성이 있어 호흡에 의한 섭취량을 생각하지 않을 수 없다. 일단 대기환경 중 다이옥신 농토는 1999년부터 환경부와 국립환경연구원에서 전국적으로 조사하여 발표하고 있으나 서울시에 대해서는 단지 2∼3개 지점에 대해서만 조사하는 등 사례가 드물어 서울시내 대기환경관리 정책에 어려움이 있을 것으로 사료되어 이번 조사에서는 현재 서울시 일원의 환경대기 중 다이옥신 농도 현황을 파악하여 이의 관리대책을 위한 자료를 제공하고자 실시하였다. (중략)

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