• 제목/요약/키워드: bio-electrochemical process

검색결과 25건 처리시간 0.019초

Electrochemical Capacitance of Activated Carbons Regenerated using Thermal and Chemical Activation

  • Park, Jung Eun;Lee, Gi Bbum;Hwang, Sang Youp
    • Journal of Electrochemical Science and Technology
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    • 제12권3호
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    • pp.339-345
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    • 2021
  • Spent activated carbons (SACs) collected from a water treatment plant were regenerated and then adopted as electrochemical material in capacitors. The SACs used in this study were regenerated via two steps, namely thermal and chemical activation. However, during the activation process, the adsorbates were converted into ashes, which caused pore blockage and decreased specific surface area. The regenerated SACs were washed with acid solutions with different levels of acidity (strong: HCl, mild: H3PO4, and weak: H2O2) to remove the ashes. The regenerated SACs washed with HCl exhibited the highest specific surface area, although their capacitance was not the highest. Conversely, the specific surface area of regenerated SACs washed using H3PO4 was slightly lower than that of HCl, but exhibited higher capacitance and electrochemical stability. Although the strong acid removed the generated ashes in the pores efficiently, it could adversely affect their structural stability, which would lead to lower capacitance.

전극을 전자공여체로 이용한 생물전기화학공정에서의 염소화페놀의 탈염소화 (Reductive Dechlorination of Chlorinated Phenols in Bio-electrochemical Process using an Electrode as Electron Donor)

  • 전현희;박대원
    • KSBB Journal
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    • 제22권3호
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    • pp.134-138
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    • 2007
  • 미생물이 환원된 전극을 전자공여체로 이용하고, 염소화페놀을 전자수용체로 이용하는 새로운 혐기성 호흡의 생물전기화학공정을 통해 2,6-DCP을 탈염소시킬 수 있는지를 조사하였다. 이를 위해 전류의 유무에 따른 농도변이와 전극 표면을 주사전자현미경으로 관찰한 결과, 전류가 흐르는 경우에만 염소화페놀이 완전히 제거됨을 보였으며, 전극표면에 생물막이 형성된 것을 통해서 전극이 전자공여체 역할을 함으로서 탈염소시킬 수 있음을 증명하였다. 또한, 본 연구의 생물전기화학공정을 통해서 고농도의 염소화페놀 적용도 가능한지를 조사하고 Monod식을 이용하여 최대 탈염소화 속도를 산정하였는데 본 실험의 최대초기농도인 $457mg/{\ell}$까지 분해가 가능하였으며, 최대탈염소화 속도는 $5.95mg/{\ell}$-h($cm^2$ (electrode surface area))이었다.

알루미늄 박판의 다단 전해식각 공정을 이용한 3 차원 마이크로 구조물의 제작 (Three-Dimensional Microstructures Fabricated by Multi-Step Electrochemical Aluminum-Foil Etching)

  • 김윤지;윤세찬;한원;조영호;박호준;장병규;오용수
    • 대한기계학회논문집A
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    • 제34권12호
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    • pp.1805-1810
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    • 2010
  • 본 논문에서는 알루미늄 박판의 다단 전해식각을 공정을 이용한 3 차원 마이크로 구조물 제작방법을 제안한다. 본 공정은 기존 전해가공 공정들에 비해 3 차원 구조물의 대량생산이 용이하며, 기존 3 차원 마이크로 금속 구조물의 제작을 위한 다단 도금방법에 비해 간단하고, 경제적일 뿐만 아니라, 성형된 금속 박판을 이용하므로 구조물의 물성이 안정적이다. 본 논문에서는 단일 전해식각 공정을 통한 2 차원 외팔보 열과 다단 전해식각 공정을 통한 3 차원 마이크로 구조물의 제작을 수행하였다. 단일 전해식각 공정에서 평균 수직방향 식각률 $1.50{\pm}0.10 {\mu}m/min$ 와 평균 수평방향 식각률 $0.77{\pm}0.03 {\mu}m/min$을 얻었으며, 이를 이용한 3 차원 마이크로 구조물을 제작한 결과, 수직방향으로 $15.5{\pm}5.8 %$, 수평방향으로 $3.3{\pm}0.9 %$의 제작오차와 $37.4{\pm}9.6 nm$의 표면조도를 보였다.

A Unified Potentiostat for Electrochemical Glucose Sensors

  • Sohn, Ki-Sung;Oh, Seok-Jae;Kim, Eui-Jin;Gim, Jeong-Min;Kim, Nam-Soo;Kim, Yeong-Seuk;Kim, Jong-Won
    • Transactions on Electrical and Electronic Materials
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    • 제14권5호
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    • pp.273-277
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    • 2013
  • A unified potentiostat circuit for both $O_2$- and $H_2O_2$- based electrochemical glucose sensors was proposed and its function was verified by circuit simulations and measurement results of a fabricated chip. This circuit consisted of an operational amplifier, a comparator and current mirrors. The proposed circuit was fabricated with a $0.13{\mu}m$ thick oxide CMOS process and an active area of $360{\mu}m{\times}100{\mu}m$. The measurements revealed an input operation range from 0.5 V to 1.6 V in the $H_2O_2$- based bio-sensor and from 1.7 V to 2.6 V in the $O_2$- based bio-sensor with a supply voltage of 3.3 V. The evaluation results showed that the proposed potentiostat circuit is suitable for measuring the electrochemical cell currents of both $O_2$- and $H_2O_2$- based glucose sensors.

Synthesis and Electrochemical Characterization of Reduced Graphene Oxide-Manganese Oxide Nanocomposites

  • Lee, Yu-Ri;Song, Min-Sun;Lee, Kyung-Min;Kim, In-Young;Hwang, Seong-Ju
    • Journal of Electrochemical Science and Technology
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    • 제2권1호
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    • pp.1-7
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    • 2011
  • Nanocomposites of reduced graphene oxide and manganese (II,III) oxide can be synthesized by the freeze-drying process of the mixed colloidal suspension of graphene oxide and manganese oxide, and the subsequent heat-treatment. The calcined reduced graphene oxide-manganese (II,III) oxide nanocomposites are X-ray amorphous, suggesting the formation of homogeneous and disordered mixture without any phase separation. The reduction of graphene oxide to reduced graphene oxide upon the heat-treatment is evidenced by Fourier-transformed infrared spectroscopy. Field emission-scanning electronic microscopy and energy dispersive spectrometry clearly demonstrate the formation of porous structure by the house-of-cards type stacking of reduced graphene oxide nanosheets and the homogeneous distribution of manganese ions in the nanocomposites. According to Mn K-edge X-ray absorption spectroscopy, manganese ions in the calcined nanocomposites are stabilized in octahedral symmetry with mixed Mn oxidation state of Mn(II)/Mn(III). The present reduced graphene oxide-manganese oxide nanocomposites show characteristic pseudocapacitance behavior superior to the pristine manganese oxide, suggesting their applicability as electrode material for supercapacitors.

레이저빔 마킹 조건에 따른 티타늄 표면특성 분석 (Analysis of Titanium Surface Characteristics according to Laser Beam Marking Conditions)

  • 신홍식
    • 융복합기술연구소 논문집
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    • 제3권2호
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    • pp.39-43
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    • 2013
  • Titanium has been used to satisfy various applications such as bio engineering, aerospace, electronics, automobile. Recently, micro fabrication technologies of metals such as titanium have been required to satisfy many conditions in various fields. To satisfy these demands, micro electrochemical process using laser marking can be an alternative method because it is one of the precision machining and efficient process. Micro electrochemical process using laser marking needs to accomplish form of the oxidized recast layer on metal surface by laser marking. The laser beam marking conditions such as average power, pulse repetition rate and marking speed should be properly selected to form oxidized recast layer. So, the characteristics of titanium surface according to laser marking conditions was investigated through SEM(scanning electron microscope), EDS(energy dispersive spectrometer) and surface roughness analysis.

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Electrochemical Study of [Ni63-Se)2μ4-Se)3(dppf)3] Cluster and Its Catalytic Activity towards the Electrochemical Reduction of Carbon Dioxide

  • Park, Deog-Su;Jabbar, Md. Abdul;Park, Hyun;Lee, Hak-Myoung;Shin, Sung-Chul;Shim, Yoon-Bo
    • Bulletin of the Korean Chemical Society
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    • 제28권11호
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    • pp.1996-2002
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    • 2007
  • The redox behavior of a [Ni6(μ3-Se)2(μ4-Se)3(Fe(η 5-C5H4P-Ph2)2)3] (= [Ni-Se-dppf], dppf = 1,1-bis(diphenylphosphino) ferrocene) cluster was studied using platinum (Pt) and glassy carbon electrodes (GCE) in nonaqueous media. The cluster showed electrochemical activity at the potential range between +1.6 and ?1.6 V. In the negative region (0 to ?1.6 V), the cluster exhibited two-step reductions. The first step was one-electron reversible, while the second step was a five-electron quasi-reversible process. On the other hand, in the positive region (0 to +1.6 V), the first step involved one-electron quasi-reversible process. The applicability of the cluster was found towards the electrocatalytic reduction of CO2 and was evaluated by experiments using rotating ring disc electrode (RRDE). RRDE experiments demonstrated that two electrons were involved in the electrocatalytic reduction of CO2 to CO at the Se-Ni-dppf-modified electrode.

Wire-like Bundle Arrays of Copper Hydroxide Prepared by the Electrochemical Anodization of Cu Foil

  • La, Duc-Duong;Park, Sung-Yeol;Choi, Young-Wook;Kim, Yong-Shin
    • Bulletin of the Korean Chemical Society
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    • 제31권8호
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    • pp.2283-2288
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    • 2010
  • Nanostructured copper compounds were grown by electrochemical anodization of copper foil in aqueous NaOH under varying conditions including electrolyte concentration, reaction temperature, current density, and reaction time. Their morphology and atomic composition were investigated by using SEM, TEM, XRD, EDS and XPS. At the conditions ([NaOH] = 1 M, $20^{\circ}C$, $2\;mA\;cm^{-2}$), wire-like orthorhombic $Cu(OH)_2$ nanobundles with an average width of 100 - 300 nm and length of $10\;{\mu}m$ were synthesized with the preferential [100] growth direction. Furthermore, when the concentration decreased to 0.5 M NaOH, the 1D nanobundle structure became narrower and longer without any change in compositions or crystalline structure. Side reaction pathways appeared to compete with the 1D nanostructure formation channels: the formation of CuO nanoleaves at $50^{\circ}C$ via the sequential dehydration of $Cu(OH)_2$, CuO/$Cu_2O$ aggregates in 4 M NaOH, and $Cu_2O$ nanoparticles and CuO nanosheets at lower current density.

An Electrochemical Enzyme Immunochip Based on Capacitance Measurement for the Detection of IgG

  • Yi, Seung-Jae;Choi, Ji-Hye;Kim, Hwa-Jung;Chang, Seung-Cheol;Park, Deog-Su;Kim, Kyung-Chun;Chang, Chulhun L.
    • Bulletin of the Korean Chemical Society
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    • 제32권4호
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    • pp.1298-1302
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    • 2011
  • This study describes the development of an electrochemical array immunochip for the detection of IgG. Interdigitated immunochip platforms were fabricated by sputtering gold on a glass wafer by using MEMS process and then were coated with Eudragit S100, an enteric polymer, forming an insulating layer over the working area of immunochips. The breakdown of the polymer layer was exemplified by the catalytic action of urease which, in the presence of urea, caused an alkaline pH change. This subsequently caused an increase of the double layer capacitance of the underlying electrode. Used in conjunction with a competitive immunoassay format, this allowed the ratio of initial to final electrode capacitance to be directly linked with the concentration of analyte, i.e. IgG. Responses to IgG could be detected at IgG concentration as low as $250\;ngmL^{-1}$ and showed good linearity up to IgG concentration as high as $20\;{\mu}gmL^{-1}$.

Synthesis of Activated Carbon from a Bio Waste (Flower of Shorea Robusta) Using Different Activating Agents and Its Application as Supercapacitor Electrode

  • Ghosh, Souvik;Samanta, Prakas;Murmu, Naresh Chandra;Kim, Nam Hoon;Kuila, Tapas
    • Composites Research
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    • 제35권1호
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    • pp.1-7
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    • 2022
  • The activated carbon is a very good choice for using as supercapacitor electrode materials. Herein, the flower of Shorea robusta, a bio-waste material was successfully used to synthesize the activated carbons for application as supercapacitor electrode materials. The activated carbon was synthesized through chemical activation process followed by thermal treatment at 700℃ in presence of N2 atmosphere using KOH, ZnCl2 and H3PO4 as the activating agents. The physicochemical analyses demonstrate that the obtained activated carbons are graphitic in nature and the degree of disorder of the graphitic carbons is changed with the activating agents. The activated carbon obtained from Shorea robusta flower (ACSF-K) electrode shows the specific capacitance of ~610 F g-1 at 2 A g-1 current density, which is higher than ACSF-Z (560 F g-1) and ACSF-H (470 F g-1) electrode material under the identical current density. The synthesized graphitic carbons also demonstrated good rate capability and high electrochemical stability as supercapacitor electrode.