• Title/Summary/Keyword: 환원반응

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The Electrocatalytic Reduction of Oxygen by Bis-Cobalt Phenylporphyrins in Various pH Solutions (여러 가지 pH 수용액에서 Bis-Cobalt Phenylporphyrin 유도체들에 의한 산소의 전극 촉매적 환원)

  • Yong-Kook Choi;Ki-Hyung Chjo;Jong-Ki Park
    • Journal of the Korean Chemical Society
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    • v.37 no.8
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    • pp.735-743
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    • 1993
  • The electrocatalytic reduction of oxygen is investigated by cyclic voltammetry and chronoamperometry at glassy carbon electrode and carbon microelectrode coated with a variety of cobalt phenylprophyrins in various pH solutions. Oxygen reduction catalyzed by the monomeric porphyrin Co(Ⅱ)-TPP mainly occurs through the 2e$^-$ reduction pathway resulting in the formation of hydrogen peroxide whereas electrocatalytic process carried out 4e$^-$ reduction pathway of oxygen to H$_2$O at the electrodes coated with cofacial bis-cobalt phenylporphyrins in acidic solution. The electrocatalytic reduction of oxygen is irreversible and diffusion controlled. The reduction potentials of oxygen in various pH solutions have a straight line from pH 4 to pH 13, but level off in strong acidic solution. The reduction potentials of oxygen shift to positive potential more 400 mV at the electrode coated with monomer Co-TPP compound than bare glassy carbon electrode while 750 mV at the electrode coated with dimer Co-TPP compound.

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Electrochemical Studies of Light Lantanide Complexes (Part 1) (가벼운 란탄족 원소 착물의 전기화학적 연구 (제 1 보))

  • Kang Sam-Woo;Park Chong-Min;Chang Choo-Hawn;Do Lee-Mi;Suh Moo-Yul
    • Journal of the Korean Chemical Society
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    • v.37 no.1
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    • pp.83-91
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    • 1993
  • The eletrochemical behavior of light lanthanide complexes has been investigated by several electrochemical techniques in alkaline solutions. The composition of the complexes was determined by spectrophotometric method to be 1 : 1 and reduction mechanism was two steps 1 electron transfer reaction. The half wave potential of first peak depended on pH and cathodic current showed remarkably adsorptive properties. The results of DC and CV investigation demonstrated the quise-reversible nature of the electron transfer. The anion radical formed after first one electron reduction process, dimerizes to form dimer. The apparent irreversible behavior of the second wave is a result of the existence of a fast protonation following the second electron transfer. An exhaustive electrolysis was carried out at controlled potential of -1.80 V, deep blue color of the solution became progressively weaker, and then the solution became colorless solution. The final product of an exhaustive electrolysis is electro-inactive. The appearance of four steps may be explained by the fact the reduction of Ln-OCP elucidated ECEC mechanism.

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Durability Extension of Fe(0) Column with Shewanella Algae BrY on TCE Treatment (Shewanella algae BrY를 이용한 영가철 칼럼의 TCE 처리 수명연장)

  • Chae, Heehun;Bae, Yeunook;Park, Jae-Woo
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.2
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    • pp.41-48
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    • 2007
  • Zevo-valent iron (ZVI) has been widely used in permeable reactive barriers for reducing organic contaminants, such as trichloroethylene (TCE). The rapid reaction time, however, leads to decrease in reactivity and availability of ZVI. Shewanella algae BrY, a strain of dissimilatory iron reducing bacteria, can reduce the oxidized Fe (III) to Fe (II) and reduced Fe (II) can be reused to reduce the contaminant. The effect of Shewanella algae BrY on the reduction of the oxidized ZVI column and further TCE removal in the contaminated groundwater were studied at different flow rates and TCE input concentrations in this study. High input concentration of TCE and flow rate increase the amount of input contaminant and make to lower the effect of reduction by Shewanella algae BrY. Specially, the fast flow rate inhibits the direct contact and implantation on the surface of iron. The reduction of oxidized iron reactive barrier by Shewanella algae BrY can decrease the decreation of duration of PRBs by the precipitation of oxidized iron produced by dechlorination of TCE.

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Decomposition of Carbon Dioxide Using Sr Ferrites with Various Compositions (다양한 조성의 Sr 페라이트를 이용한 CO2분해 반응 특성)

  • 신현창;최정철;정광덕;최승철
    • Journal of the Korean Ceramic Society
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    • v.40 no.2
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    • pp.191-197
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    • 2003
  • Sr ferrites with various compositions were applied to the decomposition of $CO_2$ to mitigate the greenhouse effect. In the reduction reaction of Sr ferrites up to 80$0^{\circ}C$, starting temperature was lower with increasing of Sr content in Sr ferrite. However, the reactivity was higher with decreasing Sr content. In the $CO_2$ decomposition reaction with reduced Sr ferrites, the amount of CO and C were depended on the ratio of Sr and Fe in Sr ferrite. With increasing Sr content. larger amount of C were deposited on the surface of ferrite. Therefore, in order to apply Sr ferrites for the decomposition of $CO_2$, it is necessary to control the ratio of Sr and Fe according to the conditions used.

Electrochemical Reduction of 0,0-Dimethyl-0-(3-Methyl-4-Nitrophenyl)-phosphorothioate(Sumithion®) in Acetonitrile Solution (Acetonitrile 용액중(溶液中)에서 0,0-Dimethyl-0-(3-Methyl-4-Nitrophenyl)-phosphorothioate(Sumithion®)의 전기화학적(電氣化學的) 환원반응(還元反應))

  • Park, Seung Heui;Sung, Nack Do
    • Korean Journal of Agricultural Science
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    • v.11 no.2
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    • pp.315-321
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    • 1984
  • The electrochemical reduction of 0,0-dimethyl-0-(3-methyl-4 -nitrophenyl)-phosphorothioate ($Sumithion^{(R)}$) in acetonitrile solution has been studied by direct current (DC), differential pulse (DP) polarography and cyclic voltammetry methods. The irreversible electron-transfer chemical reaction (EC) mechanism of Sumithion proceeds by six electron-transfer to form radical and reduction of three-step which undergoes single bond of the phosphorus atom & phenoxy group by electron-transfer and protonation cleaved to give p-hydroxyamino-m-cresol and dimethylthiophosphonate as major product.

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Kinetics and Mechanism for Redox Reaction of cis-$[Co(en)_2(N_3)_2]^+$ with Fe(II) in Acidic Solution (산 촉매하에서 cis-$[Co(en)_2(N_3)_2]^+$ 와 Fe(II) 와의 산화-환원반응에 대한 반응속도와 메카니즘)

  • Byung-Kak Park;Kwang-Jin Kim;Joo-Sang Lim
    • Journal of the Korean Chemical Society
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    • v.33 no.3
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    • pp.309-314
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    • 1989
  • A kinetic study was carried out for the redox reaction of cis-$[Co(en)_2(N_3)_2]^+$ with Fe(II) in acidic solution by spectrophotometric methods. This redox reaction system have been found to show a third order for overall reaction as the respective first order with respect to reactant cis-$[Co(en)_2(N_3)_2]^+$, Fe(II), and $H^+$ catalyst. The activation parameters, ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$, were obtained as 14.2Kcal/mol and -16.7 e.u., respectively. On the basis of the kinetic data, we suggest that the redox reaction system proceeds via inner sphere mechanism. The rate equation derived from the proposed mechanism is in agreement with the observed rate equation.

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Thermodynamic Analysis of Silicon Reduction Reaction in Arc Furnace (아크로를 이용한 실리콘 환원 반응의 열역학적 해석)

  • Park, Dongho;Kim, Dae-Suk;Lee, Sang-Wook;Moon, Byoungmoon;Yu, Tae U
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.70.2-70.2
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    • 2010
  • 고순도 금속규소는 반도체, 태양전지 및 규소화 화합물 등의 원료로 사용되어왔으며, 최근 태양전지 시장 확대로 인해 고순도 금속규소의 수요가 증가하고 있다. 그러나 전량 수입 중인 고순도 금속규소의 수급 안정성과 품질 균일성 등이 문제가 되고 있어, 고순도 생산 공정 및 생산 에너지를 절감 공정에 관한 연구 개발이 필요한 실정이다. 이에 본 연구에서는 금속규소의 원료인 규석(SiO2)과 카본(C)의 환원반응을 온도와 압력별로 살펴보고, 평형 상태의 금속규소수율 조건을 알아보았다. 그리고 아크로 내부 위치에 따른 산화/환원 반응식을 고찰하여 주요 반응식의 깁스 자유 에너지를 비교 분석 하였다. 본 해석을 통한 실험용 아크로 제작과 기초실험을 통해 금속 규소 생산 수율 및 순도를 평가하였으며, 생산된 실리콘의 최대 순도는 약 99.8%로 측정되었다.

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Thioredoxin-Mediated Regulation of Protein Synthesis by Redox in Saccharomyces cerevisiae (Saccharomyces cerevisiae에서 산화환원에 의한 In Vitro 단백질합성의 Thioredoxin에 중재된 조절)

  • Choi, Sang-Ki
    • Microbiology and Biotechnology Letters
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    • v.35 no.1
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    • pp.36-40
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    • 2007
  • Redox signaling is one of way to regulate growth and death of cell in response to change of redox of proteins. To search whether translation is regulated by redox, we attempted in vitro translation assay under condition with or without DTT. Interestingly in vitro translation activity was increased up to 40% In the presence of dithiothreitol (DTT). Then we checked whether this positive effect by DTT was further accelerated by addition of thioredoxin (Trx). When a Trx purified from Saccharomyces cerevisiae was added to the in vitro translation extract, we observed a dose-dependent increase in translational activity. These results suggest the possibility of translation factors being redox-regulated via Trx in vivo.

Reduction of Nitrotoluenes and Simultaneous Removal of Hydrogen Sulfide and Nitrotoluenes by Co3+-centered Hematoporphyrin (포피린의 촉매작용에 의한 니트로톨루엔의 환원 및 니트로톨루엔과 황화수소의 동시 제거)

  • Cho, Jeong-Guk;Kang, An-Soo
    • Applied Chemistry for Engineering
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    • v.5 no.1
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    • pp.37-43
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    • 1994
  • Mononitrotoluenes were reduced to aminotoluenes using porphyrin as a catalyst in the presence of several types of reductants including hydrogen sulfide and 1, 4-dithiothreitol(DTT). Intermediates and final products of porphyrin-catalyzed reduction of mononitrotoluenes were identified and a pathway for the reduction of the nitro group to the corresponding amino group was proposed. The optimum pH for the reduction was determined. The catalytic activity of the porphyrin was confirmed by UV/VIS absorption spectra and basic kinetics of porphyrin-catalyzed reduction were studied. Of several types of reductants tested, DTT sodium hydrosulfite, and hydrogen sulfide were seen to give significant reduction of nitrobodies. When hydrogen sulfide was used as a reductant hydrogen sulfide and nitrotoluenes were removed simultaneously.

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