• 공업화학
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• 제34권2호
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• pp.175-179
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• 2023

본 연구에서는 음극 활물질로 폴리옥소메탈에이트(polyoxometalate, POM)인 포스포몰리브 산(phosphomolybdic acid)와 양극 활물질로 페로시아나이드(ferrocyanide)를 지지 전해질인 수산화나트륨 수용액을 이용하여 산화환원 흐름 전지(redox flow battery, RFB)를 구성하였다. 다양한 농도의 수산화나트륨 수용액(1.0 M, 1.2 M, 1.4 M, 1.5 M, 1.6 M)을 이용하여 배터리의 성능테스트를 진행하였으며, 각 물질에 대한 전기화학적 특성과 안정성에 대해 연구하였다. 지지 전해질의 농도는 음극 활물질인 포스포몰리브 산에 영향을 주며 최적 값이 존재하고 농도가 증가할수록 전해질 저항이 줄어들게 되며 1.5 M에서 가장 줄어드는 현상을 확인하였고 1.6 M로 농도가 증가할 시 전해질 저항이 다시 증가한다는 것을 확인하였다. 전해질 저항의 감소는 전체 에너지 효율에도 영향을 주어 농도가 증가됨에 따라 효율은 증가하며 1.5 M에서 가장 좋은 배터리 성능을 보인다는 것을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.189-193
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• 2001

The irreversible capacities caused by the reduction of solvent on the surface of a negative electrode (KMFC:Kawasaki Mesophase Fine Carbon) were examined during the initial cycle in ethylene carbonate (EC)-diethyl carbonate (DEC) electrolyte solut ions at various concentrations of LiPF6. Chronopotentiograms, linear sweep voltammograms, and impedance spectra clearly showed differences in irreversible capacity and that those differences are related to the concentration of electrolyte during the initial charge. These differences were caused by the amount of solvent decomposition as a function of the concentration of LiPF6 electrolytic salt. The data are discussed with reference to the concentration of electrolytic salt and the properties of passivation film formed by solvent decomposition.

• 전기화학회지
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• 제2권3호
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• pp.163-170
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• 1999

AFC 단전지에서 운전조건의 영향은 이제까지 자세히 연구된 바 없다. 본 연구에서는 초기 전해질 농도와 가스 운전압력의 영향을 살펴보기 위하여 1차원 등온 모델을 이용해 전산모사를 수행하였다. 결과에 의하면, base-case에서 최적 전해질 농도는 $3.0\~3.5M$사이에 있는 것으로 발견되었다. 전해질 농도에 따른 전지 성능의 변화는 주로 양쪽 전극의 전하전달 저항과 용해된 기체의 헨리상수 및 액상확산이 원인인 것으로 밝혀졌다. 또한, 운전 압력의 증가는 반응속도와 가스의 용해도를 증가시켰으며, 이것으로 인해 전지 성능이 상당히 향상되는 것으로 조사되었다

• 열처리공학회지
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• 제25권5호
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• pp.227-232
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• 2012

Magnesium alloy have good physical properties such as good castability, good vibration absorption, high strength/weight ratios. Despite the desirable properties, the poor resistance of Mg alloy impedes their use in many various applications. Therefore, magnesium alloy require surface treatment to improve hardness, corrosion and wear resistance. Plasma Electrolytic Oxidation (PEO) is one the surface treatment methods to form oxide layer on Mg alloy in alkali electrolyte. In comparison with Anodizing, there is environmental process having higher hardness and faster deposition rate. In this study, the characteristics of oxide film were examined after coating the AZ31 Mg alloy through the PEO process. We changed concentration of sodium aluminate into $K_2ZrF_6$, KF base electrolyte. The morphologies of the coating layer were characterized by using scanning electron microscopy (SEM). Corrosion resistance also investigated by potentiodynamic polarization analysis. As a result, propertiy of oxide layer were changed by concentration of sodium aluminate. Increasing with concentration of sodium aluminate in electrolyte, the oxidation layer was denser and the pore size was smaller on the surface.

• 한국의류학회지
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• 제28권6호
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• pp.854-861
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• 2004

To estimate dispersion stability of particles in anionic and nonionic surfactant mixed solution, suspending power was examined as functions of duration time of suspension, ionic and nonionic surfactant mixed ratio, surfactant concentration, kinds of electrolyte, ionic strength and mole numbers of oxyethylene additions to nonionic surfactant using $\alpha$-Fe$_2$O$_3$ particle as the model of particulate soil. The suspending power of anionic and nonionic surfactant mixed solution was relatively higher than that of anionic and nonionic surfactant single solution regardless of solution concentration. The suspending power was gradually decreased with increasing duration time of suspension. In the absence of electrolyte, the effect of surfactant concentration on suspending power was small but in solution with electrolyte, suspending power was lowest at 1 ％ surfactant concentration. With 1${\times}$10$^{-3}$ ionic strength and polyanionic electrolyte in solution, the suspending power was high but effects of oxyethylene mole number to nonionic surfactant on suspending power was small. Generally the suspending power was gradually increased with decreasing the particle size. Hence the suspending power was inversely related to the particle size.

• 대한치과보철학회지
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• 제38권2호
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• pp.178-190
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• 2000

The purpose of this study was to evaluate the surface roughness of Ni-Cr-Be alloy($Verabond^{(R)}$, Aalba Dent Inc., USA) according to electrolyte concentration and etching time. Total of 150 metal specimens ($12{\times}10{\times}1.5mm$) composed of 5 polisded specimens, 5 sandblasted specimens, 140 etched specimens were prepared. Etched groups were divided into 28 groups by the $HClO_4$ concentrations(10, 30, 50, 70%) and etching times(15, 30, 60, 120, 180, 240, 300 seconds). The mean surface roughness(Ra) and the etching depth were measured with Optical 3-dimensional surface roughness measuring machine(Accura 1500M, Intek Engineering Co., Korea) and observed under SEM. The results obtaind were as follows: 1. Surface roughness(Ra) and etching depth were affected by the order of etching time, electrolyte concentration, and their interaction(P<0.05). 2. Surface roughness(Ra) and etching depth were increased with etching time in 10%, 30% electrolyte concentrations, but they had no significant difference with etching time in 70% (P<0.05). 3. Surface roughness(Ra) and etching depth decreased in the order of 30, 10, 50, 70% electrolyte concentrations from 120 seconds etching time(P<0.05). 4. The remarkable morphologic changes in etched surface were observed along the grain boundaries in 15, 30 seconds of 10%, 30% concentrations and the morphologic changes could be denoted in the grains themselves as well as along the boundaries with the lapse of time. Even though the noticeable morphologic changes also took place in etched surface with 50% concentration, the degree of changes were less than that of changes with 10%, 30%. However, there were little morphologic changes with 70% concentration regardless of etching time. 5. Surface roughness(Ra) of sandblasting group with $50{\mu}m\;Al_2O_3$ had no significant difference with 30%-30 seconds etched group(P<0.05).

• Journal of Electrochemical Science and Technology
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• 제13권4호
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• pp.424-430
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• 2022

In the study, Ni²⁺ (nickel) removal from synthetically prepared wastewater by electrocoagulation method, which is one of the electrochemical treatment processes, was investigated and parameters such as current density, pH, mixing speed, initial Ni²⁺ concentration, supporting electrolyte type and concentration were determined to determine Ni²⁺ removal efficiencies effects were studied. Experiment conditions during 30 minutes of electrolysis; the current density was determined as 0.95 mA/cm², the initial pH of the wastewater was 6, the mixing speed was 150 rpm, and the initial nickel concentration was 250 mg/L. The Ni²⁺ removal efficiency was obtained as 75.99% under the determined experimental conditions, while the energy consumption was calculated as 3.15 kW-h/m³. In the experiments, it was observed that the type and concentration of the supporting electrolyte did not have a significant effect on the Ni²⁺ removal efficiency. In the trials where the effect of the support electrolyte concentration was examined, the Ni²⁺ removal efficiency was 75.99% in the wastewater environment without the supporting electrolyte, while the Ni²⁺ removal efficiency was 81.55% when 7.5 mmol/L NaCl was used after the 30-minute reaction, and the energy consumption was 2.15 kW-h/m³ obtained as. As a result of the studies, it was concluded that the electrocoagulation process can be applied in the treatment of wastewater containing Ni²⁺.

• 한국의류학회지
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• 제13권3호
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• pp.286-294
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• 1989

This Study has treated the effects of fiber, surfactants, temperature, surfactant concentration, pH, electrolyte, fatty acid contents and mechanical force on the removal of particulate soil from fabric, vacuum cleaner dirt was used as model particulate soil. The fabrics were soiled with mixture of vacuum cleaner dirt and fatty soil, and washed in Terg-O-tometer. The detergency was evaluated by measuring reflectance of a fabric before and after washing. The results were as follows. 1. The fiber type showed a different pattern of soil removal with surfactants. In general, particulate soil removal increased in the following order Acetate>PET. Nylon>Cotton. Particulate soil removal, which is affected by the surfactant type, increased in the following order NPE $(EO)_{10}\leqq$Soap>SLS>DBS>Tween 80. 2. The influence of temperature on the particulate soil removal was very complex because efficiency of removal was varied with surfactant and fiber types. The washing efficiency of NPE $(EO)_{10}$ was highest at around $40^{\circ}C\;and\;60^{\circ}C$ with cotton and PET but the washing efficiency of DBS was the highest at $60^{\circ}C$ with cotton, decreased monotonously with increasing temperature with PET 3. The detergency of particulate soil increased with increasing surfactant concentration at relatively low concentration and then levelled off above some optimum concentration. 4. The removal of particulate soil increased with increasing pH and mechanical force. 5. Effect of electrolyte on the particulate soil removal was depended on the concentration of the surfactant. At low concentration of surfactant, addition of electrolytes improved soil removal but above the some concentration no effect was observed. At high concentration of surfactant, Vie., $0.6\%$ , the maximum washing effect is reached without added electrolyte. These result indicate that added electrolyte only influence the adsorption of surfactant on the soil and fiber 6. Fatty acid content in the soil did not influence on particulate soil removal without regard to surfactants.

• 전기학회논문지P
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• 제64권4호
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• pp.303-307
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• 2015

The effects of additive such as $H_2O_2$ in KOH electrolyte solution for the Aluminum/Air fuel cell were investigated with regard to electric power characteristics. The power generated by a Al/Air fuel cell was controlled by the KOH electrolyte solution and $H_2O_2$ depolarizer. Higher cell power was achieved when higher KOH electrolyte concentration and higher $H_2O_2$ depolarizer amount. The maximum power was increased by the increase amount $H_2O_2$ depolarizer, it was found that $H_2O_2$ depolarizer inhibits the generation of hydrogen and the polarization effect was reduced as a result. Internal resistance analysis was employed to elucidate the maximum power variation. Higher internal resistance created internal potential differences that drive current dissipating energy. In order to improve the output characteristics of the Al/Air fuel cell, it is thought to be desirable to increase the KOH electrolyte concentration and increase the $H_2O_2$ addition amounts.

• 센서학회지
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• 제23권3호
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• pp.170-172
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• 2014

$CO_2$ sensor was used only one solid electrolyte in many cases. To improve the sensing characteristics of $CO_2$ sensors, solid electrolyte $CO_2$ sensor has been developed by bi-electrolyte type sensor using Na-Beta-alumina and YSZ. However, in many further studies, bi-electrolyte type sensor was made by pellet pressed by press machine and additional treatment for formation of interface. In the aspect of mass production, using thick film and additional treatment is not suitable. In this study, $CO_2$ sensor was fabricated by bi-electrolyte structure which was made by an NBA paste layer deposited on YSZ pellet and fired at $1650^{\circ}C$ for 2 hour. The formation of stable interface between YSZ and NBA were confirmed by SEM image. When the type IV electrochemical cell arrangement represented by $CO_2,O_2,Pt{\mid}Li_2CO_3-CaCO_3{\parallel}NBA{\parallel}YSZ{\mid}O_2,Pt$ is used to measure the $CO_2$ concentration in air. This sensor EMF should depend only on the concentration of $CO_2$ by logarithmic. Also, sensor shows $P_{CO_2}$ and EMF relationship like nerstian reaction at a temperature of $450^{\circ}C$.