• Journal of Environmental Health Sciences
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• v.35 no.4
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• pp.295-303
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• 2009

A simulated wastewater containing the dye Rhodamine B (RhB) was electrolytically treated using a three-dimensional electrode reactor equipped with granular activated carbon (GAC) as particle electrode. The effect of type of packing material (GAC, ACF, Nonwoven fabric fiber coated with activated carbon), amounts of GAC packing (25-100 g), current (0.5-3 A) and electrolyte concentration (0.5-3 g/l) was evaluated. Experimental results showed that performance for RhB decolorization of the 3 three-dimensional electrodes lie in: GAC > Nonwoven fabric fiber > ACF. When considered RhB decolorization, oxidants concentration and electric power, optimum GAC dosage was 50 g. Generated concentration of 3 oxidants ($ClO_2$, free Cl, $H_2O_2$) was increased with increase of applied current, however optimum current for RhB degradation was 2.5 A. The oxidants concentration was increased with increase of NaCl concentration and optimum NaCl dosage for RhB degradation was 1.5 g/l.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.47-51
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• 2005

The bioelectrochemical reduction of nitrate in the presence of various mediators including methyl viologen and azure A was studied using a 3-electrode voltammetric system. The catalytic potential for the reduction of the mediators was observed in the reactor, which for methyl viologen and azure A were -0.74 V and -0.32 V, respectively, with respect to the potential of Ag/AgCl reference electrode. This potential was then applied to a working electrode to reduce each mediator for enzymatic nitrate reduction. Nitrite, the product of the reaction, was measured to observe the enzymatic nitrate reduction in the reaction media. Methyl viologen was observed as the most efficient mediator among those tested, while azure A showed the highest electron efficiency at the intrinsic reduction potential when the mediated enzyme reactions were carried out with the freely solubilized mediator. The electron transfer of azure A with respect to time was due to the adhesion of azure A to the hydrophilic surface during the reduction. In addition, the use of the adsorbed mediator on conductive activated carbon was proposed to inhibit the change in the electron transfer rate during the reaction by maintaining a constant mediator concentration and active surface area of the electrode. Azure A showed better than nitrite formation than methyl viologen when used with activated carbon.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.335-338
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• 2000

Carbon is an attractive candidate for use in eletrochemical supercapacitors that depend on charge storage in the electrode/electrolyte international double layer. Property of an electrical double layer capacitor depend both on the technique used to prepare the electrode and on the current collector structure. The study is to research that V$_2$O$_{5}$-flyash-AC composite electrode for supercapacitor. The discharge capacitance of V$_2$O$_{5}$-flyash-AC(70wt%) in 1st and 50th cycle was 18.6F/g and 15.13F/g at current density of 0.5mA/cm$^2$. The discharge process of V$_2$O$_{5}$-flyash (3 : 97)-AC composite electrode is larger than that others.thers.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.178-182
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• 2007

Non-aqueous supercapacitors by using activated C and $LiMn_2O_4$ as an active material in a positive electrode were prepared and characterized. From the cyclic voltammetry and AC impedance analysis, the capacitive effect by electric double layer of activated carbon and the faradic effect by intercalation/deintercalation of $Li^+$ ion were observed. Increasing the ratio of $LiMn_2O_4$, specific capacitances and energy densities of supercapacitor were increased. At the ratio of 0.86:0.14 ($LiMn_2O_4:C$), the maximum specific capacitance of 17.51 Wh/L and energy density of 23.83 F/cc were obtained, which were more than twice of those for a conventional electric double layer capacitor. Even after 1,000 charge/discharge cycle, the supercapacitor by using the electrode containing 14% of activated carbon and 86% of $LiMn_2O_4$ showed 60% better specific capacitance and energy density than that by using the electrode containing 100% activated carbon.

• Carbon letters
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• v.20
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• pp.76-80
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• 2016

• Journal of the Korean Electrochemical Society
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• v.6 no.3
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• pp.174-177
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• 2003

Electric double-layer capacitors based on charge storage at the interface between a high surface area activated carbon electrode and an electrolyte solution are characterized by their long cycle-life and high power density in comparison with batteries. However, energy density of electric double-layer capacitors obtained at present is about 6 Wh/kg at a power density of 500W/kg which is smaller as compared with that of batteries and limits the wide spread use of the capacitors. Therefore, a new capacitor that shows larger energy density than that of electric double-layer capacitors is proposed. The new capacitor is the hybrid capacitor consisting of activated carbon cathode, carbonaceous anode and an organic electrolyte. Maximum voltage applicable to the cell is over 4.2V that is larger than that of the electric double-layer capacitor. As a result, discharged energy density on the basis of stacked volume of electrode, current collector and separator is more than 18Wh/l at a power density of 500W/l.

• 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.

• Journal of Electrochemical Science and Technology
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• v.3 no.2
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• pp.72-79
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• 2012

$Li_2MnSiO_4$ was synthesized using the solid-state method under an Ar atmosphere at three different calcination temperatures (900, 950, and $1000^{\circ}C$). The optimization of the carbon coating was also carried out using various molar concentrations of adipic acid as the carbon source. The XRD pattern confirmed that the resulting $Li_2MnSiO_4$ particles exhibited an orthorhombic structure with a $Pmn2_1$ space group. Cyclic voltammetry was utilized to investigate the capacitive behavior of $Li_2MnSiO_4$ along with activated carbon (AC) in a hybrid supercapacitor with a two-electrode cell configuration. The $Li_2MnSiO_4$/AC cell exhibited a high discharge capacitance and energy density of $43.2Fg^{-1}$ and $54Whkg^{-1}$, respectively, at $1.0mAcm^{-2}$. The $Li_2MnSiO_4$/AC hybrid supercapacitor exhibited an excellent cycling stability over 1000 measured cycles with coulombic efficiency over > 99 %. Electrochemical impedance spectroscopy was conducted to corroborate the results that were obtained and described.

• Membrane Journal
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• v.28 no.4
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• pp.271-278
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• 2018

In this study, the carbon electrodes using activated carbon fibers (ACFs) were prepared for the capacitive deionization process. The Polyvinylidene fluoride (PVDF) was used as the binder and the mixed ACFs with proper solvent was cast on the commercial graphite sheets to prepare the carbon electrodes. At this moment, the different particle sizes of ACFs were applied and the mixing ratio of solvent, PVDF and ACFs, 80 : 2 : 18 and 80 : 5 : 15, were used for the electrode preparation. Then their salt removal efficiencies were characterized under the various operating conditions, adsorption potential and time, desorption potential and time, concentration of feed NaCl solution and flow rate as well. Typically, the salt removal efficiency of 53.6% were obtained at the particle size below $32{\mu}m$, mixing ratio 80 : 2 : 18, adsorption 1.2 V and 3 min, desorption -0.1V and 1 min, and 15 mL/min flow rate of NaCl 100 mg/L.

• Elastomers and Composites
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• v.47 no.4
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• pp.292-296
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• 2012

An electric double-layer capacitor (ELDC) of activated carbon electrode is prepared using a proton-conducting hydrogel polymer electrolyte, which is composed of poly(vinyl alcohol), silicotungstic acid, $H_3PO_4$, and deionized water. A solid film by evaporating the hydrogel polymer electrolyte is also prepared for comparison. The hydrogel polymer electrolyte also acts as a separator with the thickness of about $80{\mu}m$ and the room-temperature ionic conductivity of $10^{-2}S\;cm^{-1}$. The EDLC containing the symmetric electrodes of activated carbon shows the specific capacitance of $58F\;g^{-1}$ at $100mV\;s^{-1}$ with a good cycle life, implying that the hydrogel polymer electrolyte is very promising for use in EDLCs.