• Title/Summary/Keyword: Anode Oxidation

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Influence of Temperature on the Electrolytic Oxidation of Sulphate Solutions by Electro-deposited Lead Peroxide Anode (전착과산화납양극에 의한 황산염. 전해산화시의 전해온도의 영향)

  • Chong Woo Nam;Hak Joon Kim
    • Journal of the Korean Chemical Society
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    • v.15 no.5
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    • pp.223-228
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    • 1971
  • In the electrolytic preparation of persulphate from sulphate solution, the current efficiency decrease with temperature increase at the platinum anode. But in case of electrodeposited lead peroxide anode, the current efficiency increase with temperature of the solution. The reason seems to be that the ozone formation is faster in platinum anode than in lead peroxide as temperature increase.

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A Study on the Oxidation Characteristics of p-Cresol on Pt Anode (백금전극(白金電極)에 의한 파라크레졸의 양극전해(陽極電解) 산화특성(酸化特性))

  • Kim, Hong-Soo;Nam, Jeong-Woo
    • Journal of the Korean Applied Science and Technology
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    • v.7 no.2
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    • pp.47-53
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    • 1990
  • The electrochemical oxidation behavior of p-cresol on platinum anode had been investigated by cyclic voltammetric method for the variation of concentration, scan rate of potential, temperature and pH of electrolyte. The oxidation potential of p-cresol was dependent on the electrolyte until the pH=11.5, but in basic solution over its, it was held at o.40V(vs. SCE). A diffusion was rate determining step of oxidation as irreversible reaction by the transfer atone electron. The current of peak was proportional to concentration of p-cresol until the 0.1N and optimum concentration was found to be about 0.1N. The activation energy was calculated for 5.8kcal/mol from the plot of log $I_l$ vs. 1/T.

A study on the oxidation characteristics of phenol on Pt anode (백금전극을 이용한 페놀의 산화특성에 관한 연구)

  • Kim, Hong-Soo;Nam, Jeong-Woo;Nam, Ki-Dae
    • Applied Chemistry for Engineering
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    • v.1 no.1
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    • pp.44-51
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    • 1990
  • The electrochemical oxidation behavior of phenol on platinum anode had been investigated by cyclic voltammetric method. The initial oxidation potential of phenol was dependent on the pH in acid solution. But in basic solution, it was held 033-0.40V(vs. S.C.E.). The peak current was proportional to the concentration of phenol and the optimum concentration was found to be about 0.1N. The oxidation reaction of phenol was found to be irreversible and controlled by diffusion.

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Optimum dimensionally stable anode with volatilization and electrochemical advanced oxidation for volatile organic compounds treatment (전극의 부반응 기포발생에 따른 휘발특성과 전기화학고도산화능을 동시에 고려한 휘발성 유기화합물 처리용 최적 불용성전극 개발)

  • Cho, Wan-Cheol;Poo, Kyung-Min;Lee, Ji-Eun;Kim, Tae-Nam;Chae, Kyu-Jung
    • Journal of Korean Society of Water and Wastewater
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    • v.33 no.1
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    • pp.31-41
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    • 2019
  • Volatile organic compounds(VOCs) are toxic carcinogenic compounds found in wastewater. VOCs require rapid removal because they are easily volatilized during wastewater treatment. Electrochemical advanced oxidation processes(EAOPs) are considered efficient for VOC removal, based on their fast and versatile anodic electrochemical oxidation of pollutants. Many studies have reported the efficiency of removal of various types of pollutants using different anodes, but few studies have examined volatilization of VOCs during EAOPs. This study examined the removal efficiency for VOCs (chloroform, benzene, trichloroethylene and toluene) by oxidization and volatilization under a static stirred, aerated condition and an EAOP to compare the volatility of each compound. The removal efficiency of the optimum anode was determined by comparing the smallest volatilization ratio and the largest oxidization ratio for four different dimensionally stable anodes(DSA): Pt/Ti, $IrO_2/Ti$, $IrO_2/Ti$, and $IrO_2-Ru-Pd/Ti$. EAOP was operated under same current density ($25mA/cm^2$) and electrolyte concentration (0.05 M, as NaCl). The high volatility of the VOCs resulted in removal of more than 90% within 30 min under aerated conditions. For EAOP, the $IrO_2-Ru/Ti$ anode exhibited the highest VOC removal efficiency, at over 98% in 1 h, and the lowest VOC volatilization (less than 5%). Chloroform was the most recalcitrant VOC due to its high volatility and chemical stability, but it was oxidized 99.2% by $IrO_2-Ru/Ti$, 90.2% by $IrO_2-Ru-Pd/Ti$, 78% by $IrO_2/Ti$, and 75.4% by Pt/Ti anodes The oxidation and volatilization ratios of the VOCs indicate that the $IrO_2-Ru/Ti$ anode has superior electrochemical properties for VOC treatment due to its rapid oxidation process and its prevention of bubbling and volatilization of VOCs.

Ni Nanoparticles Supported on MIL-101 as a Potential Catalyst for Urea Oxidation in Direct Urea Fuel Cells

  • Tran, Ngan Thao Quynh;Gil, Hyo Sun;Das, Gautam;Kim, Bo Hyun;Yoon, Hyon Hee
    • Korean Chemical Engineering Research
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    • v.57 no.3
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    • pp.387-391
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    • 2019
  • A highly porous Ni@MIL-101catalyst for urea oxidation was synthesized by anchoring Ni into a Cr-based metal-organic framework, MIL-101, particles. The morphology, structure, and composition of as synthesized Ni@MIL-101 catalysts were characterized by X-Ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electro-catalytic activity of the Ni@MIL-101catalysts towards urea oxidation was investigated using cyclic voltammetry. It was found that the structure of Ni@MIL-101 retained that of the parent MIL-101, featuring a high BET surface area of $916m^2g^{-1}$, and thus excellent electro-catalytic activity for urea oxidation. A $urea/H_2O_2$ fuel cell with Ni@MIL-101 as anode material exhibited an excellent performance with maximum power density of $8.7mWcm^{-2}$ with an open circuit voltage of 0.7 V. Thus, this work shows that the highly porous three-dimensional Ni@MIL-101 catalysts can be used for urea oxidation and as an efficient anode material for urea fuel cells.

Anodic Oxidation of Iodate to Periodate by Lead Peroxide Anode (전착과산화납양극에 의한 옥소산염 전해산화)

  • Chong Woo Nam;Hak Joon Kim
    • Journal of the Korean Chemical Society
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    • v.15 no.6
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    • pp.324-329
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    • 1971
  • In order to evaluate the mechanism of electrolytic oxidation of iodate and to determine the optimum conditions for the electrolysis, studies were made using the cells without diaphragm and the lead peroxide anode. Results are summarized as followings: 1) Current density vs. anode potential curve by lead peroxide electrode had the different limiting current densities from platinum electrode and was more positive than platinum electrode. 2) Additions of potassium bichromate in the electrolyte contribute to maintain high current efficiency. 3) In the acid and alkaline regions, the current efficiencies decreased by reduction of iodate and discharge of hydroxyl ion, so maximum current efficiency was shown at pH 7. 4) Higher current density lowered the current efficiency in the region of 60-80% conversion of iodate. 5) Influence of the conversion on current efficiency in the region of 60-80% conversion of iodate.

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Characteristics of Sr0.92Y0.08TiO3-δ Anode in Humidified MethaneFuel for Intermediate Temperature Solid Oxide Fuel Cells

  • Park, Eun Kyung;Yun, Jeong Woo
    • Journal of Electrochemical Science and Technology
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    • v.7 no.1
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    • pp.33-40
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    • 2016
  • Sr0.92Y0.08TiO3-δ (SYT) was investigated as an alternative anode in humidified CH4 fuel for SOFCs at low temperatures (650 ℃-750 ℃) and compared with the conventional Ni/yttria-stabilized zirconia (Ni/YSZ) anode. The goal of the study was to directly use a hydrocarbon fuel in a SOFC without a reforming process. The cell performance of the SYT anode was relatively low compared with that of the Ni/YSZ anode because of the poor electrochemical catalytic activity of SYT. In the presence of CH4 fuel, however, the cell performance with the SYT anode decreased by 20%, in contrast to the 58% decrease in the case of the Ni/YSZ anode. The severe degradation of cell performance observed with the Ni/YSZ anode was caused by carbon deposition that resulted from methane thermal cracking. Carbon was much less detected in the SYT anode due to the catalytic oxidation. Otherwise, a significant amount of bulk carbon was detected in the Ni/YSZ anode.

Mo,Cu-doped CeO2 as Anode Material of Solid Oxide Fuel Cells (SOFCs) using Syngas as Fuel

  • Diaz-Aburto, Isaac;Hidalgo, Jacqueline;Fuentes-Mendoza, Eliana;Gonzalez-Poggini, Sergio;Estay, Humberto;Colet-Lagrille, Melanie
    • Journal of Electrochemical Science and Technology
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    • v.12 no.2
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    • pp.246-256
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    • 2021
  • Mo,Cu-doped CeO2 (CMCuO) nanopowders were synthesized by the nitrate-fuel combustion method aiming to improve the electrical and electrochemical properties of its Mo-doped CeO2 (CMO) parent by the addition of copper. An electrical conductivity of ca. 1.22·10-2 S cm-1 was measured in air at 800℃ for CMCuO, which is nearly 10 times higher than that reported for CMO. This increase was associated with the inclusion of copper into the crystal lattice of ceria and the presence of Cu and Cu2O as secondary phases in the CMCuO structure, which also could explain the increase in the charge transfer activities of the CMCuO based anode for the hydrogen and carbon monoxide electro-oxidation processes compared to the CMO based anode. A maximum power density of ca. 120 mW cm-2 was measured using a CMCuO based anode in a solid oxide fuel cell (SOFC) with YSZ electrolyte and LSM-YSZ cathode operating at 800℃ with humidified syngas as fuel, which is comparable to the power output reported for other SOFCs with anodes containing copper. An increase in the area specific resistance of the SOFC was observed after ca. 10 hours of operation under cycling open circuit voltage and polarization conditions, which was attributed to the anode delamination caused by the reduction of the Cu2O secondary phase contained in its microstructure. Therefore, the addition of a more electroactive phase for hydrogen oxidation is suggested to confer long-term stability to the CMCuO based anode.

Effects of Electrolyte Concentration and Relative Cathode Electrode Area Sizes in Titania Film Formation by Micro-Arc Oxidation

  • Lee, Yong-K.;Lee, Kang-Soo
    • Corrosion Science and Technology
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    • v.9 no.4
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    • pp.171-174
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    • 2010
  • MAO (micro-arc oxidation) is an eco-friendly convenient and effective technology to deposit high-quality oxide coatings on the surfaces of Ti, Al, Mg and their alloys. The roles of the electrolyte concentration and relative cathode electrode area sizes in the grown oxide film during titanium MAO were investigated. The higher the concentration of the electrolyte, the lower the $R_{total}A$ value. The oxide film produced by the lower concentration of the electrolyte is thinner and less uniform than the film by the higher concentration, which is thick and porous. The cathode area size must be bigger than the anode area size in order to minimize the voltage drop across the cathode. The ratio of the cathode area size to the anode area size must be bigger than 8. Otherwise, the cathode will be another source for voltage drop, which is detrimental to and slows down the oxide growth.

The study on the thickness change of tantalum oxide as voltage drop in electrolyte

  • Hur, Chang-Wu;Lee, Kyu-Chung
    • Journal of information and communication convergence engineering
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    • v.8 no.4
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    • pp.453-456
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    • 2010
  • Tantalum oxide ($Ta_2O_5$) films are of considerable interest for a range of application, including optical waveguide devices, high temperature resistors, and oxygen sensors. In this paper, we establish an anode oxidation process of tantalum thin film. The voltage drop in the electrolyte is affected not in voltage change but in current change. If the voltage drop in the electrolyte is same with cathode oxidation voltage, the current changes logarithmically in proportion to the voltage drop in interface of tantalum oxide and electrolyte. As a result of the measurement on the electrical property of tantalum oxide thin film, when the thickness of the insulator film is $1500{\AA}$, the breakdown voltage is 350volts and dielectric constant is 29.