• Title, Summary, Keyword: Methane

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Dissolved Methane Measurements in Seawater and Sediment Porewater Using Membrane Inlet Mass Spectrometer (MIMS) System (Membrane Inlet Mass Spectrometer (MIMS) 시스템을 이용한 해수 및 퇴적물 공극수내 용존 메탄의 측정)

  • An, Soon-Mo;Kwon, Ji-Nam;Lim, Jea-Hyun;Park, Yun-Jung;Kang, Dong-Jin
    • The Sea
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    • v.12 no.3
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    • pp.244-250
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    • 2007
  • Membrane inlet mass spectrometer (MIMS) has been used to accurately quantify dissolved gases in liquid samples. In this study, the MIMS system was applied to measure dissolved methane in seawater and sediment porewater. To evaluate the accuracy of the measurement, liquid samples saturated with different methane partial pressure were prepared and the methane concentrations were quantified with the MIMS system. The measured values correspond well with the expected values calculated from solubility constants. The standard error of the measurements were $0.13{\sim}0.9%$ of the mean values. The distribution of dissolved methane concentration in seawater of the South Sea of Korea revealed that the physical parameters primarily control the methane concentration in sea water. The MIMS system was effective to resolve the small dissolved methane difference among water masses. The probe type inlet in MIMS system was proven to be effective to measure porewater methane concentration.

Seasonal Variation of Dissolved Methane Concentration and Flux in the Nakdong Estuary (낙동강 하구의 용존 메탄 분포와 메탄 플럭스의 계절변화)

  • RYU, JEHEE;AN, SOONMO
    • The Sea
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    • v.21 no.3
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    • pp.91-102
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    • 2016
  • The spatio-temporal variations of the dissolved methane concentration were investigated and the methane budget was estimated in the Nakdong Estuary in January, September, and November of 2014. Dissolved methane showed seasonal variation (21~874 nM) with high concentration in summer due to enhanced temperature and fresh water discharge. Decreasing trends of dissolved methane from the river to the estuary were consistent in all seasons showing the main source of the estuarine methane is river discharge. However, the decreasing trends were modified seasonally due to the local sources such as organic-rich sediments in intertidal zone or near the estuarine barrage. Dissolved methane concentration in the Nakdong Estuary was high, compared to other estuaries probably due to the well developed wetland in Nakdong-river system and stagnation effect from barrages and dams. Dominant sink for the Nakdong estuarine methane was outflux into the atmosphere. Relatively long residence time (produced by barrier island and estuarine dam) in the estuary might provide the enough time for the outgassing.

Comparison of In vivo and In vitro Techniques for Methane Production from Ruminant Diets

  • Bhatta, Raghavendra;Tajima, K.;Takusari, N.;Higuchi, K.;Enishi, O.;Kurihara, M.
    • Asian-Australasian Journal of Animal Sciences
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    • v.20 no.7
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    • pp.1049-1056
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    • 2007
  • This study was conducted to compare the methane ($CH_4$) production estimated by in vivo (sulfur hexafluoride tracer technique ($SF_6$)) with that of two in vitro rumen simulation (RUSITEC) and gas production (IVGPT)) techniques. Four adult dry Holstein cows, aged $7.4{\pm}3.0$ years and weighing $697{\pm}70$ kg, were used for measuring methane production from five diets by the $SF_6$ technique. The experimental diets were alfalfa hay ($D_1$), corn silage + soybean meal (SBM) (910: 90, $D_2$), Italian rye grass hay +SBM (920: 80, $D_3$), rice straw +SBM (910: 90, $D_4$) and Sudan grass hay +SBM (920: 80, $D_5$). Each diet was individually fed to all 4 cows and 5 feeding studies of 17 d each were conducted to measure the methane production. In the RUSITEC, methane production was measured from triplicate vessels for each diet .In vitro gas production was measured for each of the diets in triplicate syringes. The gas produced after 24 and 48 h was recorded and gas samples were collected in vacuum vials and the methane production was calculated after correction for standard temperature and pressure (STP). Compared to the $SF_6$ technique, estimates of methane production using the RUSITEC were lower for all diets. Methane production estimated from 24 h in vitro gas production was higher (p<0.001) on $D_1$ as compared to that measured by $SF_6$, whereas on $D_2$ to $D_5$ it was lower. Compared to $SF_6$, methane production estimated from 48 h in vitro gas production was higher on all diets. However, methane estimated from the mean of the two measurement intervals (24+48 h/2) in IVGPT was very close to that of $SF_6$ (correlation 0.98), except on $D_1$. The results of our study confirmed that IVGPT is reflective of in vivo conditions, so that it could be used to generate a database on methane production potential of various ruminant diets and to examine strategies to modify methane emissions by ruminants.

Anaerobic Fermentation of Woody Biomass Treated by Various Methods

  • Nakamura, Yoshitoshi;Mtui, Godliving
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.8 no.3
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    • pp.179-182
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    • 2003
  • Anaerobic fermentation was attempted to produce methane from the wood chip (Eucalyptus globulus). By the pretreatment of the wood chip using hot water with high temperature, NaOH, and steam explosion, the production of methane gas was enhanced. The pretreatment using Steam explosion resulted in more amount of methane gas produced than the treatment using either hot water or 1% (w/w) NaOH with high temperature, and the steam explosion at a steam pressure of 25 atm and a steaming time of 3 min was the most effective for the methane production. The amount of methane gas produced depended on the ratio of weight of Klason lignin, a high molecular weight lignin, in the treated wood chip.

Spectrophotometric Determination of Isonicotinic Acid Hydrazide Sodium Methane Sulfonate (Isonicotinic Acid Hydrazide Sodium Methane Sulfonate의 분광광도정량법(分光光度定量法)(제1보)(第1報))

  • Park, Yonng-Ju;Lee, Bung-Chan;Suh, Jnng-Jin;Kim, Sun-Nyu
    • Journal of Pharmaceutical Investigation
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    • v.2 no.1
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    • pp.14-17
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    • 1972
  • Spectrophotometric determination of isonicotinic acid hydrazide sodium methane sulfonate was examined and a new method has been established. Isonicotinic acid hydrazide sodium methane sulfonate reacts with acetylacetone solution (NASH Reagent) to produce a yellow dye, which exhibits absorption maximum at about $412\;m{\mu}$. Limits of masurement of isonicotinic acid hydrazide sodium methane sulfonate was $20-100{\mu}g/ml$. By this method isonicotinic acid hydrazide methane sulfonate can be determined in the presence of isonicotinic acid hydrazide.

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Partial Oxidation of Methane over Ni/SiO2

  • Roh, Hyun-Seog;Dong, Wen-Sheng;Jun, Ki-Won;Liu, Zhong-Wen;Park, Sang-Eon;Oh, Young-Sam
    • Bulletin of the Korean Chemical Society
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    • v.23 no.5
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    • pp.669-673
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    • 2002
  • Ni catalyst (Ni: 15 wt%) supported on precalcined SiO2 has been investigated in reforming reactions of methane to synthesis gas. The catalyst exhibited fairly good activity and stability in partial oxidation of methane (POM), whereas it deactivated in steam reforming of methane (SRM). Pulse reaction results of CH4, O2, and CH4/O2 revealed that Ni/SiO2 has high capability to dissociate methane. The results also revealed that both CH4 and O2 are activated on the surface of metallic Ni, and then surface carbon species react with adsorbed oxygen to produce CO and CO2 depending on the bond strength of the oxygen species on the catalyst surface.

Hydrogen Production from Methane Reforming Reactions over Ni/MgO Catalyst

  • Wen Sheng Dong;No, Hyeon Seok;Zhong Wen Liu;Jeon, Gi Won;Park, Sang Eon
    • Bulletin of the Korean Chemical Society
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    • v.22 no.12
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    • pp.1323-1327
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    • 2001
  • The catalyst Ni/MgO (Ni : 15 wt%) has been applied to methane reforming reactions, such as steam reforming of methane (SRM), partial oxidation of methane (POM), and oxy-steam reforming of methane (OSRM). It showed high activity and good stability in all the reforming reactions. Especially, it exhibited stable catalytic performance even in stoichiometric SRM (H2O/CH4 = 1). From TPR and H2 pulse chemisorption results, a strong interaction between NiO and MgO results in a high dispersion of Ni crystallite. Pulse reaction results revealed that both CH4 and O2 are activated on the surface of metallic Ni over the catalyst, and then surface carbon species react with adsorbed oxygen to produce CO.

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Improvement of $\lambda$--window Range of the Three-Way Catalyst for Natural Gas Vehicles (천연가스 자동차용 삼원촉매의 $\lambda$-윈도우 영역 개선)

  • 최병철;정필수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.1
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    • pp.92-100
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    • 2000
  • The model gas reaction tests were carried out to investigate the purification characteristics of methane on the exclusive catalyst for NGV. The experiment was conducted with the factors which affect the conversion efficiency of methane, such as Redox ratio, coexistence components of CO, MO, $H_2$O, precious metals and additives. The catalyst loaded with larger amount of pd and with additive La showed lower light-off temperature. In the presence of CO and NO, the conversion efficiency of methane was varied according to the kind of additive loaded. The conversion efficiency of methane was dropped for the catalyst loaded with La under lean air-fuel ratio, while it increased for the one loaded with Ti+Zr for the same condition. It was shown that the water vapor inhibited methane from oxidation by its poisoning on the surface of catalyst.

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Preponderant Occurrence of sl natural methane hydrates: Spectroscopic analysis of crystalline structure transition (sI 천연 메탄하이드레이드의 존재 : 결정구조 변화의 분광학적 분석)

  • Yeon, Sun-Hwa;Seol, Ji-Woong;Lee, Huen
    • 한국신재생에너지학회:학술대회논문집
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    • pp.387-390
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    • 2006
  • We report here that under strong attacksof external $CH_4$ guest molecules the sII and sH methane hydrates are structurally transformed to the crystalline me framework of sI, leading to favorable change of the lattice dimension of the host-guest networks. The High Power Decoupling $^{13}C$ NMR and Raman spectroscopies were used to identify structure transitions of the mixed $CH_4+C_2H_6$ hydrates (sIIl) and hydrocarbons (methylcyclohexane, isopentane) + $CH_4$ hydrates (sH). The resulting spectra indicate that most of the synthesized sII and sH hydrates were transformed to methane hydrate of sl under 110 bar and particularly the coexistence of sl with sII or sH appear according to the surrounding methane-rich gas conditions. The present findings might be expected to Provide rational evidences regarding the preponderant occurrence of naturally-occurring sI methane hydrates in marine sediments.

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Characterization of Methane Oxidation by a Methanotroph Isolated from a Landfill Cover Soil, South Korea

  • Lee, Eun-Hee;Yi, Tae-Woo;Moon, Kyung-Eun;Park, Hyun-Jung;Ryu, Hee-Wook;Cho, Kyung-Suk
    • Journal of Microbiology and Biotechnology
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    • v.21 no.7
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    • pp.753-756
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    • 2011
  • A methane-oxidizing bacterium was isolated from the enriched culture of a landfill cover soil. The closest relative of the isolate, designated M6, is Methylocystis sp. Based on a kinetic analysis, the maximum specific methane oxidation rate and saturation constant were 4.93 mmol gdry cell $weight^{-1}{\cdot}h^{-1}$ and 23${\mu}M$, respectively. This was the first time a kinetic analysis was performed using pure methanotrophic culture. The methane oxidation by M6 was investigated in the presence of aromatic (m- and pxylene and ethylbenzene) or sulfur (hydrogen sulfide, dimethyl sulfide, methanthiol) compounds. The methane oxidation was inhibited by the presence of aromatic or sulfur compounds.