• Title/Summary/Keyword: Oxidizing gas

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A Study on the Detection Behavior of Chlorine Dioxide on Metal Oxide Sensors (금속산화물센서의 이산화염소 가스에 대한 감지거동에 관한 연구)

  • Yu, Joon-Boo;Byun, Hyung-Gi
    • Journal of Sensor Science and Technology
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    • v.29 no.3
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    • pp.211-214
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    • 2020
  • Chlorine dioxide is very effective gas for sterilization or disinfection (in manufacturing), and does not produce harmful by-products after use. However, if its concentration exceeds 10 %, it become explosive and cannot be compressed or stored. Therefore, it is necessary to measure its concentration. In this study, the concentration of chlorine dioxide with a high oxidizing strength was measured using a metal oxide sensor. The sensor was a commercially available TGS series from Figaro. The sensitivity of the sensor was inversely proportional to a low concentration of chlorine dioxide gas below 6 ppm and returned to the initial resistance at about 6 ppm. When the gas concentration reached multiples of 10 ppm, resistance of the sensor increased to several megaohms.

Effects of Plant and Soil Amendment on Remediation Performance and Methane Mitigation in Petroleum-Contaminated Soil

  • Seo, Yoonjoo;Cho, Kyung-Suk
    • Journal of Microbiology and Biotechnology
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    • v.31 no.1
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    • pp.104-114
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    • 2021
  • Petroleum-contaminated soil is considered among the most important potential anthropogenic atmospheric methane sources. Additionally, various rhizoremediation factors can affect methane emissions by altering soil ecosystem carbon cycles. Nonetheless, greenhouse gas emissions from soil have not been given due importance as a potentially relevant parameter in rhizoremediation techniques. Therefore, in this study we sought to investigate the effects of different plant and soil amendments on both remediation efficiencies and methane emission characteristics in diesel-contaminated soil. An indoor pot experiment consisting of three plant treatments (control, maize, tall fescue) and two soil amendments (chemical nutrient, compost) was performed for 95 days. Total petroleum hydrocarbon (TPH) removal efficiency, dehydrogenase activity, and alkB (i.e., an alkane compound-degrading enzyme) gene abundance were the highest in the tall fescue and maize soil system amended with compost. Compost addition enhanced both the overall remediation efficiencies, as well as pmoA (i.e., a methane-oxidizing enzyme) gene abundance in soils. Moreover, the potential methane emission of diesel-contaminated soil was relatively low when maize was introduced to the soil system. After microbial community analysis, various TPH-degrading microorganisms (Nocardioides, Marinobacter, Immitisolibacter, Acinetobacter, Kocuria, Mycobacterium, Pseudomonas, Alcanivorax) and methane-oxidizing microorganisms (Methylocapsa, Methylosarcina) were observed in the rhizosphere soil. The effects of major rhizoremediation factors on soil remediation efficiency and greenhouse gas emissions discussed herein are expected to contribute to the development of sustainable biological remediation technologies in response to global climate change.

A study on production of dry oxidant by decomposition of H2O2 on K-Mn/Fe2O3 catalyst and NO oxidation process according to simulated flue gas flow (K-Mn/Fe2O3 촉매 상 H2O2 분해에 의한 건식산화제 생성 및 모사 배가스 유량에 따른 NO 산화공정)

  • Choi, Hee Young;Shin, Woo Jin;Jang, Jung Hee;Han, Gi Bo
    • Journal of the Korean Applied Science and Technology
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    • v.34 no.2
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    • pp.367-375
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    • 2017
  • In this study, NO oxidation process was studied to increase the NO treatment efficiency of pollutant present in exhaust gas. $H_2O_2$ catalytic cracking was introduced as a method of producing dry oxidizing agents with strong oxidizing power. The $K-Mn/Fe_2O_3$ heterogeneous catalysts applicable to the $H_2O_2$ decomposition process were prepared and their physico-chemical properties were investigated. The prepared dry oxidant was applied to the NO oxidation process to treat the simulated exhaust gas containing NO, NO conversion rates close to 100% were confirmed at various flow rates (5, 10, 20 L/min) of the simulated flue gas.

Identification of Gas Mixture with the MEMS Sensor Arrays by a Pattern Recognition

  • Bum-Joon Kim;Jung-Sik Kim
    • Korean Journal of Materials Research
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    • v.34 no.5
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    • pp.235-241
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    • 2024
  • Gas identification techniques using pattern recognition methods were developed from four micro-electronic gas sensors for noxious gas mixture analysis. The target gases for the air quality monitoring inside vehicles were two exhaust gases, carbon monoxide (CO) and nitrogen oxides (NOx), and two odor gases, ammonia (NH3) and formaldehyde (HCHO). Four MEMS gas sensors with sensing materials of Pd-SnO2 for CO, In2O3 for NOX, Ru-WO3 for NH3, and hybridized SnO2-ZnO material for HCHO were fabricated. In six binary mixed gas systems with oxidizing and reducing gases, the gas sensing behaviors and the sensor responses of these methods were examined for the discrimination of gas species. The gas sensitivity data was extracted and their patterns were determined using principal component analysis (PCA) techniques. The PCA plot results showed good separation among the mixed gas systems, suggesting that the gas mixture tests for noxious gases and their mixtures could be well classified and discriminated changes.

Flame characteristics of direct fired burner in fuel-air mixing conditions (열처리로 직화버너에서 연료-공기 혼합에 따른 화염 영향)

  • Lee, Cheolwoo;Kim, Youngho;Kim, Insu;Hong, Junggoo
    • 한국연소학회:학술대회논문집
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    • 2014.11a
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    • pp.285-288
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    • 2014
  • Experiments have been performed for the burners used in the non-oxidizing direct fired furnaces for the cold rolled plate to investigate the effect of fuel/air mixing patterns of the burner nozzle on flame shape, temperature and combustion gas concentration. CFD simulation has also been performed to investigate the mixing state of air-fuel for a nozzle mixing burner and a partially pre-mixing burner. A partially pre-mixing burner showed that flame temperature increased up to $26^{\circ}C$ on average compared than that of the nozzle mixing. It also showed that the mixing distance is important at the partially pre-mixing burner. Test results for a partially pre-mixing burner showed that the residual oxygen concentration and the volume ratio of $CO/CO_2$ of the flame were applicable to be used in field furnaces.

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Characteristics of Ambient Gas for Bi-Superconductor Thin Films Growth (Bi 초전도 박막 성장을 위한 분위기가스의 특성)

  • Lim, Jung-Kwan;Park, Yong-Pil;Jang, Kyung-Uk;Lee, Hee-Kab
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.587-588
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    • 2005
  • Ozone is useful oxidizing gas for the fabrication of BSCCO thin films. In order to obtain high quality oxide BSCCO thin films, higher ozone concentration is necessary. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In this paper oxidation property was evaluated relation between oxide gas pressure and inverse temperature(CuO reaction). The obtained condition was formulated by the fabrication of Cu metal thin film by co-deposition using the Ion Beam Sputtering method. Because the CuO phase peak appeared at the XRD evaluation of the CuO thin film using ozone gas, this study has succeeded in the fabrication of the CuO phase at $825^{\circ}C$.

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Development of High Sensitive Integrated Dual Sensor to Detect Harmful Exhaust Gas and Odor for the Automotive (악취분별능력을 가진 자동차용 고기능 듀얼타입 집적형 유해가스 유입차단센서 개발)

  • Chung, Wan-Young;Shim, Chang-Hyun
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.7
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    • pp.616-623
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    • 2007
  • A dual micro gas sensor array was fabricated using nano sized $SnO_2$ thin films which had good sensitivities to CO and combustible gases, or $H_2S$ gas for air quality sensors in automobile. The already existed air quality sensor detects oxidizing gases and reducing gases, the air quality sensor(AQS), located near the fresh air inlet detected the harmful gases, the fresh air inlet door/ventilation flap was closed to reduce the amount of pollution entering the vehicle cabin through HVAC(heating, ventilating, and air conditioning) system. In this study, to make $SnO_2$ thin film AQS sensor, thin tin metal layer between 1000 and $2000{\AA}$ thick was oxidized between 600 and $800^{\circ}C$ by thermal oxidation. The gas sensing layers such as $SnO_2$, $SnO_2$(pt) and $SnO_2$(+CuO) were patterned by metal shadow mask for simple fabrication process on the silicon substrate. The micro gas sensors with $SnO_2$(+Pt) and $SnO_2$(CuO) showed good selectivity to CO gas among reducing gases and good sensitivity to $H_2S$ that is main component of bad odor, separately.

Characterization of CH4-oxidizing and N2O-reducing Bacterial Consortia Enriched from the Rhizospheres of Maize and Tall Fescue (옥수수와 톨페스큐 근권 유래의 메탄 산화 및 아산화질소 환원 세균 컨소시움 특성)

  • Lee, Soojung;Kim, Seoyoung;Kim, Ye Ji;Lee, Yun-Yeong;Cho, Kyung-Suk
    • Microbiology and Biotechnology Letters
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    • v.49 no.2
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    • pp.225-238
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    • 2021
  • CH4-oxidizing and N2O-reducing bacterial consortia were enriched from the rhizosphere soils of maize (Zea mays) and tall fescue (Festuca arundinacea). Illumina MiSeq sequencing analysis was performed to comparatively analyze the bacterial communities of the consortia with those of the rhizosphere soils. Additionally, the effect of root exudate on CH4 oxidation and N2O reduction activities of the microbes was evaluated. Although the inoculum sources varied, the CH4-oxidizing and N2O-reducing consortia derived from maize and tall fescue were similar. The predominant methanotrophs in the CH4-oxidizing consortia were Methylosarcina, Methylococcus, and Methylocystis. Among the N2O-reducing consortia, the representative N2O-reducing bacteria were Cloacibacterium, Azonexus, and Klebsiella. The N2O reduction rate of the N2O-reducing consortium from maize rhizosphere and tall fescue rhizosphere increased by 1.6 and 2.7 times with the addition of maize and tall fescue root exudates, respectively. The CH4 oxidization activity of the CH4-oxidizing consortia did not increase with the addition of root exudates. The CH4-oxidizing and N2O-reducing consortia can be used as promising bioresources to mitigate non-CO2 greenhouse gas emissions during remediation of oil-contaminated soils.

Synthesis and Characterization of Zinc Oxide Nanorods for Nitrogen Dioxide Gas Detection

  • Park, Jong-Hyun;Kim, Hyojin
    • Journal of Surface Science and Engineering
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    • v.54 no.5
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    • pp.260-266
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    • 2021
  • Synthesizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate highly efficient gas sensors by means of possible enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned zinc oxide (ZnO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Zn metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the ZnO nanorods array of the single hexagonal wurtzite crystalline phase. From gas sensing measurements for the nitrogen dioxide (NO2) gas, the vertically aligned ZnO nanorod array is observed to have a highly responsive sensitivity to NO2 gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO2 at 250 ℃ and a low NO2 detection limit of 5 ppm in dry air. These results along with a facile fabrication process demonstrate that the ZnO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO2 gas sensors.

Vertically aligned cupric oxide nanorods for nitrogen monoxide gas detection

  • Jong-Hyun Park;Hyojin Kim
    • Journal of Surface Science and Engineering
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    • v.56 no.4
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    • pp.219-226
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    • 2023
  • Utilizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate relevant gas sensors by means of potential enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned cupric oxide (CuO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a CuO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Cu metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the CuO nanorods array of the single monoclinic tenorite crystalline phase. From gas sensing measurements for the nitrogen monoxide (NO) gas, the vertically aligned CuO nanorod array is observed to have a highly responsive sensitivity to NO gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO at 200 ℃ and a low NO detection limit of 2 ppm in dry air. These results along with a facile fabrication process demonstrate that the CuO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO gas sensors.