• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.289-296
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• 2001

The effects of HRT and effluent time on removals of pollutants in the electrochemical pilot were investigated. COD removal after 8 hour electrochemical reaction time in HRT 30 and 60 minutes were higher than that of 15 minute HRT. Turbidity removal was 90% or greater regardless of conditions during effluent time. Removals of T-N and T-P during effluent time in HRT 30 and 60 minutes were $71{\sim}74%$ and $85{\sim}98%$, respectively. To evaluate the combination of activated sludge process and continuous electrochemical as pretreatment, the removal efficiencies of pollutants was investigated. In two treatment processes of a single activated sludge system and a electrolysis pilot plus activated sludge systems, SVI and MLSS during effluent time were kept with $82{\sim}112$ and $1,230{\sim}1,750$ mg/L, respectively. COD removal was approximately 90% at early effluent time for both treatment systems, but COD removal in a single activated sludge was slightly decreased as effluent time went by, compared with the single activated sludge COD removal was slightly increased in the early stage of the electrolysis plus activated sludge system. Turbidity removal during effluent time was higher than 95% for both treatment systems. T-N removals during effluent time in a single activated sludge system and a electrolysis pilot plus activated sludge systems were $62{\sim}74%$ and $72{\sim}86%$, respectively. T-P removal in a electrolysis pilot plus activated sludge systems was increased by 9% at early effluent time and 15% after 72 hours of effluent time in compared with a single activated sludge system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.246-247
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• 2005

본 연구에서는 활성탄소의 표면 작용기와 전해액, 결합제의 분해반응을 줄여서 내구성을 향상시키기 위해 $H_2$ 기체의 Spill-Over 현상을 이용하여 활성탄소 표면의 작용기를 치환시킨 시료를 사용하여 전극을 구성하였다. $H_2$기체로 활성탄소를 700$^{\circ}C$에서 열처리한 결과, 원소 분석기 (Elemental Analyzer)를 이용한 원소 분석 시에 산소의 비율이 1.4%로 활성탄소의 2.44%에 비해 감소함을 알 수 있었고, Carbon의 비율이 700$^{\circ}C$에서 94.3%로 증가함을 알 수 있었다. 또한, 활성탄소를 사용한 전극을 1.2M TEABF$_4$/Acetonitrile 전해액을 사용하여 커패시터를 구성 했을 때, 1kHz의 AC저항은 700$^{\circ}C$에서 열처리한 활성탄소가 0.58\Omega$로 활성탄소의 1.300에 비해 양호한 전기화학 특성을 나타내었다.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.201-207
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• 2013

In this study, the surface of a phenol based activated carbon (AC) used as an electrode in an electric double layer capacitor was modified via boric acid treatment for the capacitance investigation. The effect of boric acid treatment on electrochemical performance was also investigated. The AC surface functional groups ratio of quinone-like (O=C) which is electrochemical active functional groups was increased after the boric acid treatment. And, boric acid treated AC showed an increase in the specific surface area, total pore volume, and micropore volume. In case of optimum boric acid treated AC, its specific capacitance increased by 20% in comparison to that of untreated AC. These results demonstrate that a boric acid treated carbon surface-based electric double layer capacitor electrode effectively enhances specific capacitance.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.426-433
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• 2023

Capacitor performance was considered using coffee grounds-based activated carbon produced through oil extraction and KOH activation to increase the utilization of boiwaste. Oil extraction from coffee grounds was performed by solvent extraction using n-Hexane and isopropyl alcohol solvents. The AC_CG-Hexane/IPA produced by KOH activation after oil extraction increased the specific surface area by up to 16% and the average pore size by up to 2.54 nm compared to AC_CG produced only by KOH activation without oil extraction. In addition, the pyrrolic/pyridinic N functional group of the prepared activated carbon increased with the extraction of oil from coffee grounds. In the cyclic voltage-current method measurement experiment, the specific capacitance of AC_CG-Hexane/IPA at a voltage scanning speed of 10 mV/s is 133 F/g, which is 33% improved compared to the amorphous capacity of AC_CG (100 F/g). The results show improved electrochemical properties by improving the size and specific surface area of the mesopores of activated carbon by removing components from coffee grounds oil and synergistic effects by increasing electrical conductivity with pyrrolic/pyridinic N functional groups. In this study, the recycling method and application of coffee grounds, a bio-waste, is presented, and it is considered to be one of the efficient methods that can be utilized as an electrode material for high-performance supercapacitors.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.129-137
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• 2013

From the cooked-rice as a raw material, activated carbons throughout a hydrothermal synthesis and vacuum soak of KOH for chemical activation were obtained. Activated carbon electrodes for electric double layer supercapacitors were prepared and electrochemical characteristics were examined. Including the specific surface area by BET method and pore size distribution by NLDFT method, physical properties of activated carbons were investigated by means of SEM, EDS, XRD, and TG analyses. Cycle voltammetry and AC-impedance measurements were conducted to confirm the electrochemical characteristics for the electrodes. From hydrothermal synthesis, $5{\sim}7{\mu}m$ diameters of spherical carbons were obtained. After the activation at $800^{\circ}C$, it was notable for the activated carbon to be the specific surface $1631.8cm^2/g$, pore size distribution in 0.9~2.1 nm, and micro-pore volume $0.6154cm^3/g$. As electrochemical characteristics of the activated carbon electrode in 6M KOH electrolyte, it was confirmed that the specific capacitances of 236, 194, and 137 F/g at the scan rate of 5, 100, and 500 mV/s respectively were exhibited and 91.2% of initial capacitance after 100,000 cycles at 200 mV/s was maintained.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.467-472
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• 2017

Alkaline electrolytes consisting of 6 M KOH and polymer (PEO, PVA, and PAAK) are coated on PAN nonwoven fabrics as a separator, and the electrochemical properties of the activated carbon supercapacitor adopting them are investigated in terms of redox behavior, specific capacitance, and interfacial impedance. Although the interaction between polymer and KOH are comparatively inactive in PEO and PVA, PAAK (3 wt.%)-KOH forms a hydrogel phase by active interactions between $COO^-K^+$ in side-chain of PAAK and $K^+OH^-$ from alkaline electrolyte solution, improving ionic conduction of electrolytes and the electrochemical properties of the supercapacitor. As a result, the activated supercapacitor adopting the PAAK-KOH shows the superior specific capacitance of $46.8Fg^{-1}$ at $100mVs^{-1}$.

• Journal of the Korean Electrochemical Society
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• v.10 no.3
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• pp.169-174
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• 2007

MWNT/DAAQ(1,5-diaminoanthraquinone) composites were prepared by chemical polymerization of DAAQ onto MWNT and their capacitance was evaluated by means of cyclic voltammetry in 1M $H_2SO_4$ electrolyte. The performances of such cells have been compared with pure MWNT and DAAQ based electrodes. The SEM image shows that DAAQ was coated onto MWNT during polymerization and thermal stability from th TG analysis. The highest specific capacitance values of 97F/g were observed with AC-MWNT/DAAQ composite electrode. And MWNT/DAAQ based composite electrode also showed relatively good electrochemical behaviors better than MWNT electrode in sulfuric acid electrolyte.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.405-410
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• 2011

High-performance of an electric double layer capacitance (EDLC) electrode was prepared by the amino-fluorination of activated carbon by using $NF_3$ gas. The pore structure and surface chemistry were investigated based on the specific capacitance of EDLC. The amino-fluorination of activated carbon introduced functional groups of nitrogen and fluorine which are beneficial for the specific capacitance of EDLC without the change of pore structures. The E-NF100AC electrode, which has nitrogen and fluorine functional groups less than 1 at%, showed the highly improved specific capacitance of 528 (${\pm}9$) F/g at 2 mV/s showing 122% improved value when comparing with that of non-functionalized E-RAC electrodes. Whereas, the E-NF200AC electrode, which has nitrogen and fluorine functional groups over 1 at%, showed the decreased specific capacitance because of perfluorinated introduction. So, it is concluded that the proper contents of nitrogen and fluorine groups improved the specific capacitance of EDLC.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.190-190
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• 2013

여러 화합물 반도체 중 $Sb_2Te_3$, $Bi_2Te_3$, 그리고 $Bi_2Se_3$과 같은 $A_2B_3$형 화합물은 열전소자에 적용가능성이 좋아서 광범위하게 연구되고 있다. $A_2B_3$형 화합물 중 특히 $Bi_2Te_3$는 단독 또는 다른 원소와 합금하여 태양전지, 열전소자, 그리고 상-변환 소자 등으로 이용된다. $Bi_2Te_3$ 박막을 형성하는 여러 방법 중에 전기화학적인 전착법은 박막의 조성 및 두께 제어가 용이하고 비용적 측면이나 형성속도 측면에서도 타 방법에 비하여 유리하기 때문에 주목을 많이 받고 있다. 하지만 전기화학적인 전착법에 의해 얻어진 박막은 점 결함, 높은 내부에너지와 결정성이 낮다는 단점이 있다. 본 연구에서는 도금층의 결정성 향상을 위하여 계면 활성제인 CTAB를 첨가하여 $Bi_2Te_3$ 박막을 형성하였다. $Bi_2Te_3$ 박막에 미치는 계면 활성제의 영향을 알아보기 위하여 결정성 및 전기, 열전 특성을 분석하였다. 또한, 도금된 박막을 다양한 온도에서 열처리 하여 열처리가 $Bi_2Te_3$ 박막의 전기 및 열전 특성에 미치는 영향을 알아보았다.

• Journal of the Korean Electrochemical Society
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• v.16 no.2
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• pp.74-80
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• 2013

We investigate the formation of nanoporous gold (NPG) surfaces by anodization in three carboxylic acid (formic acid, acetic acid, and propionic acid) solutions and the electrochemical oxidation of glucose at NPG surfaces. Among three carboxylic acids, formic acid provided the most efficient conditions for NPG formation towards glucose oxidation. The optimized conditions during anodization in formic acid for glucose oxidation were 5.0 V of applied potential and 4 hour of reaction time. Electrocatalytic activities for glucose oxidation at NPG surfaces prepared by anodization in carboxylic acids were examined under the absence and presence of chloride ions, which were compared to those observed at NPG prepared in oxalic acid solutions. The application NPG prepared by optimized anodization conditions in formic acid to the amperometric detection of glucose was demonstrated.