• Title/Summary/Keyword: redox system

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Removal of Organic Matter and Nitrogen from River Water in a Model System of Floodplain Filtration (홍수터 여과 모형을 이용한 하천수중의 유기물과 질소 제거)

  • Ha, Hyun-Soo;Kim, Sang-Tae;Kim, Seung-Hyun;Jeong, Byeong-Ryong;Lee, Young-Deuk;Eum, Jin-Sup;Ji, Seung-Hwan;Chung, Jong-Bae
    • Applied Biological Chemistry
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    • v.45 no.2
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    • pp.84-91
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    • 2002
  • If contaminated river water is sprayed over the floodplain, organic matter and nitrogen would be removed by microbial processes in the rhizosphere of vegetation during the filtration through soil. In this study we tested the organic matter and nitrogen removal from contaminated river water by the floodplain filtration. Model system of floodplain was constructed using a PVC pipe (15 cm i.d. ${\times}$ 150 cm L) which was packed with a loamy sand soil collected from a floodplain in Nakdong river. The model system was instrumented with soil solution samplers and gas samplers. A river water collected from Omogcheon in Kyongsan was sprayed from top of the model system at three different rates. The concentration of organic matter, DO, $NO_3^-$, $NO_2^-$, $NH_4^+$, $N_2$ and $N_2O$, and redox potential were measured as a function of soil depth for 24 days after the system reached a steady state. When river water was sprayed at the rates of 40.8 and 68.0 $l/m^2/day$, a significant reductive condition for denitrification was developed at below 5-cm depth of the soil. When the water reached at 90-cm depth of the soil, COD and concentration of inorganic nitrogen were lowered, on an average, from 18.7 to 5 mg/l and from 2.7 to 0.4 mg/l, respectively. $N_2$ comprised most of the N gas evolved from denitrification and $N_2O$ concentrations emitted at the surface of soil were less than 1 {\mu}l/l. The effective removal of organic matter and nitrogen by the filtration in the model system of floodplain demonstrates that the native floodplains, which include rhizosphere of vegetation at the top soil, could be more effective in the treatment of contaminated river waters and other industrial waste waters containing high concentration of organic matter and nitrogen.

Effects of La Addition and Preparation Methods on Catalytic Activities for Methane Partial Oxidation Catalysts (메탄 부분산화반응 촉매에 La 첨가 및 제조방법에 따른 촉매활성에 미치는 영향)

  • Cheon, Han-Jin;Shin, Ki-Seok;Ahn, Sung-Hwan;Yoon, Cheol-Hun;Hahm, Hyun-Sik
    • Journal of the Korean Institute of Gas
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    • v.14 no.2
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    • pp.7-14
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    • 2010
  • Synthesis gas was produced by the partial oxidation of methane. For the preparation of catalysts, Ni, known to be active in this reaction and cheap, was used as the active component and $CeO_2$, having high oxygen storage capability and high redox ability, was used as the support. The catalysts were prepared by the impregnation and urea methods. The catalyst prepared by the urea method showed about 11 times higher surface area and finer particle size than that prepared by the impregnation method. The catalysts prepared by the urea method showed higher methane conversion and synthesis gas selectivity than that prepared by the impregnation method. In this reaction, carbon deposition is a problem to be solved, so La was added to the catalyst system to reduce the carbon deposition. TGA analysis results showed that there was 2% carbon deposition with La-added catalysts and 16% with La-free catalysts. It was found that the addition of La decreases the amount of carbon deposition and prevents catalyst deactivation.

Decomposition of Methanol-Water on $M^{II}$/ Cu / ZnO system ($M^{II}$/ Cu / ZnO 계에서의 메탄올-물의 반응)

  • Young-Sook Lee;Chong-Soo Han;Min-Soo Cho;Kae-Soo Rhee
    • Journal of the Korean Chemical Society
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    • v.32 no.1
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    • pp.22-29
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    • 1988
  • The reaction of methanol-water mixture to $CO_2$ and $H_2$ on alkaline earth metal-copper-zinc oxide has been studied in the temperature range of 150 ${\sim}\;300^{\circ}C$. Generally the addition of the alkaline earth metal to Cu/ZnO resulted in an enhancement of selectivity for $CO_2$ formation and a reduction of catalytic activity. Measurable activities were found from 150$^{\circ}C$, 200$^{\circ}C$, and 250$^{\circ}C$ on Mg/Cu/ZnO, Ca/Cu/ZnO, and Ba/Cu/ZnO respectively. However, the highest selectivity for $CO_2$ formation was observed in Ba/Cu/ZnO catalyst at 250$^{\circ}C$. The effect of alkaline earth metal or ZnO on the reactivity was investigated using temperature programmed desorption of $CO_2$ or temperature programmed reduction with $H_2$ over catalysts respectively. It was found that $CO_2$ interacts more strongly in the sequence of MgO < CaO < BaO and ZnO decereases the reduction temperature of CuO. From the results, it was suggested that ZnO activates $H_2$ in the redox process of Cu component and alkaline earth metals adsorbs $CO_2$ in the catalytic process.

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Fortified Antioxidative Potential by Chrysoeriol through the Regulation of the Nrf2/MAPK-mediated HO-1 Signaling Pathway in RAW 264.7 Cells (생쥐 대식세포에서 HO-1 발현 유도를 통한 chrysoeriol의 항산화 효과)

  • Park, Chung Mu
    • Journal of Life Science
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    • v.28 no.1
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    • pp.43-49
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    • 2018
  • Chrysoeriol is a widespread flavone, and it is usually found in alfalfa, which has been used as a traditional medicine to treat dyspepsia, asthma, and urinary system disorders. Recently, analysis has been conducted on the anti-inflammatory activity of chrysoeriol, but information on its antioxidative capacity is limited. In this study, the antioxidative potential of chrysoeriol against oxidative damage and its molecular mechanisms were evaluated by analysis of the cell viability, reactive oxygen species (ROS) formation, and Western blots in the RAW 264.7 cell line. Chrysoeriol significantly scavenged lipopolysaccharide (LPS)-induced intracellular ROS formation in a dose-dependent manner, without any cytotoxicity. Heme oxygenase-1 (HO-1), a phase II enzyme that exerts antioxidative activity, was also potently induced by chrysoeriol treatment, which corresponded to the translocation of nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) into the nucleus. Moreover, mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) were analyzed due to their important role in maintaining cellular redox homeostasis against oxidative stress. As a result, chrysoeriol-induced HO-1 upregulation was mediated by extracellular signal - regulated kinase (ERK), c-Jun $NH_2$-terminal kinase (JNK), and p38 phosphorylation. To identify the antioxidative potential exerted by HO-1, tert-butyl hydroperoxide (t-BHP)-induced oxidative damage was applied and mitigated by chrysoeriol treatment, which was confirmed by the HO-1 selective inhibitor and inducer, respectively. Consequently, chrysoeriol strongly strengthened the HO-1-mediated antioxidative potential through the regulation of the Nrf2/MAPK signaling pathways.

Effect of Selenium on the Thyroid gland Antioxidative Metabolisms in Rat Model by Ionizing Radiation (셀레늄이 전리방사선에 의한 힌쥐 모델에서의 갑상선 항산화계에 미치는 영향)

  • Choi, Hyung-Seok;Choi, Jun-Hyeok;Jung, Do-Young;Kim, Jang-Oh;Shin, Ji-Hye;Min, Byung-In
    • Journal of radiological science and technology
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    • v.40 no.1
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    • pp.135-142
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    • 2017
  • Selenium (Se), which is natural materials existing was known as an important component of selenoprotein, one of the important proteins responsible for the redox pump of a living body. Selenium was orally administered to Rat and irradiated with 10 Gy of radiation. Then, the thyroid gland was used as a target organ for 1 day, 7 days and 21 days to investigate the radiation protection effect of selenium (Se) through changes of blood components, thyroid hormones (T3, T4), antioxidant enzyme (GPx) activity and thyroid tissue changes. As a result, there was a significant protective effect of hematopoietic immune system(hemoglobin concentration, neutrophil, platelet)(p<0.05). The activity of Glutathione Peroxidase (GPx), the antioxidant enzyme, and the activity of the target organ, thyroid hormone (T3, T4), also showed significant activity changes (p<0.05). In the observation of tissue changes, it was confirmed that there was a protective effect of thyroid cell damage which caused the cell necrosis by radiation treatment. Therefore, it is considered that selenium(Se) can be utilized as a radiation defense agent by inducing immunogenic activity effect of a living body.

Protective Effect of Ferments of Hot-water Extract Mixture from Rhodiola sachalinensis and Red Ginseng on Oxidative Stress-induced C2C12 Myoblast (C2C12 근육세포의 산화적 손상에 대한 홍경천-홍삼 추출물 혼합액 발효물의 보호효과)

  • Yoon, Bo-Ra;Kim, Young-Hyun;Lee, Jong-Seok;Hong, Hee-Do;Rhee, Young-Kyoung;Cho, Chang-Won;Kim, Young-Chan;Lee, Ok-Hwan
    • The Korean Journal of Food And Nutrition
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    • v.26 no.3
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    • pp.485-491
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    • 2013
  • Rhodiola spp. and red ginseng have been used for food and medicinal applications in disease chemoprevention in many Asian countries. Increased oxidative stress by reactive oxygen species (ROS) has been proposed to be a major cause of muscle fatigue. The present study was designed to investigate the protective effects of a fermented hot-water extract mixture from Rhodiola sachalinensis and red ginseng (MFR) on cell damage and the antioxidant enzyme system in $H_2O_2$-induced oxidative stress in skeletal muscle cells. C2C12 myoblasts were treated with various concentrations of NFR (non-fermented Rhodiola sachalinensis extract), FR (fermented hot-water extract from Rhodiola sachalinensis) and MFR for up to 5 days after the standard induction of differentiation, followed by semi-quantitative RT-PCR. MFR treatment dose-dependently protected oxidative damage of C2C12 cells. The treatment with MFR also enhanced mRNA expressions of MyoD, Cu/Zn SOD, Mn-SOD and GPX up to 16%. These results indicate that MFR exerts an anti-oxidative effect through a mechanism (s) that may involve the up-regulation of antioxidant enzymes, which may be important for the cellular redox environment in muscle cells.

Extraction Behaviour of Np with DEHPA from the Low Nitric Acid Solution Containing Hydrogen Peroxide (과산화수소가 함유된 저산도 질산용액에서 DEHPA 추출제에 의한 Np의 추출거동)

  • Lee, E.H.;Yang, H.B.;Kim, K.K.;Lim, J.K.;Yoo, J.H.
    • Applied Chemistry for Engineering
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    • v.7 no.4
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    • pp.707-714
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    • 1996
  • Extraction behaviour of Np with DEHPA(di-(2-ethyhexyl)Phosphoric acid) from the low nitric acid solution(below 1M $HNO_3$) containing $H_2O_2$ as a reducing agent was studied at a batch system in order to establish the conditions of extraction and stripping and to enhance the extraction rate. As results, it was confirmed that the Np was mainly the pentavalent oxidation state in the low nitric acid solution. The extraction yield of Np was increased with increasing the concentration of DEHPA and $H_2O_2$ and decreased more rapidly with the increase of $HNO_3$ concentration. It was also found that the Np could be extracted into DEHPA even without the addiction any redox agents, although the extraction yield is rather low as about 70%. The extraction rate was proportional to the 0.516 power of $H_2O_2$ concentration and inversely proportional to 0.483 power of $HNO_3$ concentration as follows. $d[Np(V)]/dt=-1.391{\times}10^{-2}[H_2O_2]^{0.516}[HNO_3]^{-0.483}[Np(V)]$ Regardless of the $H_2O_2$, the Np extracted in the organic phase was effectively stripped to the aqueous phase with $H_2C_2O_4$. The Np could be stripped more than 92 % with 0.5M $H_2C_2O_4$.

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The Effect of Phases of Starting Materials on the Grain Size at High Pressure: the Comparison of Grain Size in the Samples Using Glass and Nano Powder as Starting Materials (고압환경에서의 결정 크기에 원시료의 상이 미치는 영향: 비정질 시료와 나노파우더를 이용한 시료의 결정 크기 비교)

  • Eun Jeong Kim;Alessio Zandona;Takehiko Hiraga;Sanae Koizumi;Nobuyoshi Miyajima;Tomoo Katsura;Byung-Dal So
    • Korean Journal of Mineralogy and Petrology
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    • v.36 no.3
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    • pp.213-220
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    • 2023
  • In this study, we report the effect of starting materials on the grain size in a multi-component system at high pressure experiments. We used two different starting materials, glass and nano powders, to synthesize bridgmanite in the reduced conditions in the presence of calcium-ferrite-phase MgAl2O4 to compared the grain size of synthesized samples. After synthesizing the sample at 40 GPa, 2000 K for 20 hrs, the sample from glass showed the grain size of 50-200 nm whereas the one from nano powders has ~500 nm of grains. This difference may come from 1) the temperature of 2000 K which is low enough for glass starting materials to make more crystal nucleis than to grow crystal size or 2) the possible difference in the redox state of starting materials. It is suggested that the using of nano powders is better to synthesize bigger grains in high pressure experiments with multi-component systems rather than using glass starting materials.

Synthesis and Properties of Ionic Polyacetylene Composite from the In-situ Quaternization Polymerization of 2-Ethynylpyridine Using Iron (III) Chloride (염화 철(III)을 이용한 2-에티닐피리딘의 in-situ4차염화중합을 통한 이온형 폴리아세틸렌 복합체의 합성과 특성)

  • Taehyoung Kim;Sung-Ho Jin;Jongwook Park;Yeong-Soon Gal
    • Applied Chemistry for Engineering
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    • v.35 no.4
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    • pp.296-302
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    • 2024
  • An ionic conjugated polymer-iron (III) chloride composite was prepared via in-situ quaternization polymerization of 2-ethynylpyridine (2EP) using iron (III) chloride. Various instrumental methods revealed that the chemical structure of the resulting conjugated polymer (P2EP)-iron (III) chloride composite has the conjugated backbone system having the designed pyridinium ferric chloride complexes. The polymerization mechanism was assumed to be that the activated triple bond of 2-ethynylpyridinium salt, formed at the first reaction step, is easily susceptible to the step-wise polymerization, followed by the same propagation step that contains the propagating macroanion and monomeric 2-ethynylpyridinium salts. The electro-optical and electrochemical properties of the P2EP-FeCl3 composite were studied. In the UV-visible spectra of P2EP-FeCl3 composite, the absorption maximum values were 480 nm and 533 nm, and the PL maximum value was 598 nm. The cyclic voltammograms of the P2EP-FeCl3 composite exhibited irreversible electrochemical behavior between the oxidation and reduction peaks. The kinetics of the redox process of composites were found to be very close to a diffusion-controlled process from the plot of the oxidation current density versus the scan rate.

Advanced Treatment of Sewage and Wastewater Using an Integrated Membrane Separation by Porous Electrode-typed Electrolysis (분리막/다공 전극형 전기분해 조합공정을 이용한 하.폐수의 고도처리)

  • Choi, Yong-Jin;Lee, Kwang-Hyun
    • Membrane Journal
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    • v.22 no.2
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    • pp.95-103
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    • 2012
  • To treat nitrate and non-biodegradable organics effectively in sewage, industrial wastewater and livestock wastewater, the activated sludge process integrated by a membrane separation and a porous electrode- electrolysis was proposed and its efficiency was investigated. The proposed system was consisted of 3 processes; activated sludge, membrane filtration and electrolysis. In the study, the membrane filtration played a role in reducing the load of the electrolysis to operate the proposed process stably. The electrolysis consisted of a porous electrode to increase the efficiency due to the extension of the specific surface area. Additionally, redox reaction in the electrolysis was induced by decomposing influent water as current was applied. As a result, hydrogen free radicals and oxygen radicals as intermediates were produced and they acted as oxidants to play a role in decomposing non-degradable organics. It was environmentally-friendly process because intermediates produced by porous electrode were used to treat waste matters without supplying external reagent. Experimental data showed that the proposed process was more excellent than activated sludge process. SS removal efficiencies of the proposed process, membrane filtration and activated sludge process were about 100%, about 100% and about 90%, respectively. COD removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 92%, about 84% and about 78%, respectively. T-N removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 88%, about 67%, and about 58%, respectively. The SS data showed that SS was efficiently removed in the single of the membrane filtration. The COD/T-N data showed that COD/T-N of membrane hybrid process was treated by removing a little soluble organics and SS, and that COD/T-N of electrolysis hybrid process was treated by oxidize organics with high removal rate.