• Bulletin of the Korean Chemical Society
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• 제16권5호
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• pp.458-461
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• 1995

The influence of adding counter-ion such as Na+ on the dimerization of the two sulphonated azo dyes, C.I. Acid Red 14 and C.I. Acid Red 17 in aqueous media has been studied spectrophotometrically. The observed hypochromic effect on increasing the amount of salt has been described. The dye concentration range where the dimerization equilibrium is applicable was chosen. No metachromatic behaviour was observed on changing the dye concentration and the amount of salt. This behaviour was attributed to the ability of the counter-ion to disrupt the structure of water as well as reducing the electrostatic repulsion forces between dye anions which will lead to the increase of aggregation tendency of the dye species.

• 대한화학회지
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• 제43권2호
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• pp.199-205
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• 1999

PAN-PVDF-PEGME 블랜드(blend)계의 고분자전해질을 만들어 전기화학적인 특성을 조사하였으며 PEGME의 첨가에 따른 물성변화를 측정하였다. PEGME가 첨가되면서 PVDF의 결정성은 감소하고, 이온 전도도는 대부분 $∼10^{-3}S/cm$의 이온전도도를 나타내므로 고분자전해질로 사용이 가능하다. 또한 이온전도도의 온도의존성으로부터 PEGME의 첨가양이 증가할수록 효과적으로 높은 이온전도도를 갖는 통로가 생겨 이온전도도가 증가하는 것으로 예상할 수 있다. SPE 2(10 wt% PEGME)에서 가장 큰 양이온 수율을 나타내고 있으며 PEGME의 양이 증가할 수록 감소하는 것을 알 수 있다. PEGME를 첨가하지 않은 SPE 1(PAN-PVDF계) 고분자전해질의 전기화학적으로 안정한 영역은 ∼4.3 V인 반면에 PEGME를 첨가한 SPE 2-4(PAN-PVDF-PEGME계) 고분자전해질은 ∼4.6 V까지 전기화학적으로 안정한 것을 알 수 있다. 또한 이 고분자전해질을 사용하여 전지를 구성하여 충방전 성능을 비교하여 보면 PEGME를 첨가함에 따라 방전 용량이 증가함을 알 수 있다. 즉 PEGME를 첨가함에 따라 이온전도도가 증대되며, 전기화학적으로 안정한 영역이 넓어질뿐만 아니라 전지구성시 방전 성능도 향상됨을 알 수 있다.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3553-3558
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• 2014

The reduced graphene oxide(rGO)/aluminum phosphate($AlPO_4$)-coated $LiMn_{1.5}Ni_{0.5}O_4$ (LMNO) cathode material has been developed by hydroxide precursor method for LMNO and by a facile solution based process for the coating with GO/$AlPO_4$ on the surface of LMNO, followed by annealing process. The amount of $AlPO_4$ has been varied from 0.5 wt % to 1.0 wt %, while the amount of rGO is maintained at 1.0 wt %. The samples have been characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The rGO/$AlPO_4$-coated LMNO electrodes exhibit better cyclic performance compared to that of pristine LMNO electrode. Specifically, rGO(1%)/$AlPO_4$(0.5%)- and rGO(1%)/$AlPO_4$(1%)-coated electrodes deliver a discharge capacity of, respectively, $123mAhg^{-1}$ and $122mAhg^{-1}$ at C/6 rate, with a capacity retention of, respectively, 96% and 98% at 100 cycles. Furthermore, the surface-modified LMNO electrodes demonstrate higher-rate capability. The rGO(1%)/$AlPO_4$(0.5%)-coated LMNO electrode shows the highest rate performance demonstrating a capacity retention of 91% at 10 C rate. The enhanced electrochemical performance can be attributed to (1) the suppression of the direct contact of electrode surface with the electrolyte, resulting in side reactions with the electrolyte due to the high cut-off voltage, and (2) smaller surface resistance and charge transfer resistance, which is confirmed by total polarization resistance and electrochemical impedance spectroscopy.

• 한국의류학회지
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• 제22권8호
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• pp.1132-1140
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• 1998

The adhesion and removal of $\alpha$-Fe2O3 particles on the from PET fabric in NPE solution with different ionic strength were discussed in terms of interaction of surface charge of particle and substrate. The adhesion of $\alpha$-Fe2O3 particles to PET fabric and its removal from PET fabric were carried out by using water bath shaker and Terg-O-Tometer under various solution conditions. The ζ potential of PET fiber and $\alpha$-Fe2O3 particles in the detergent solution were measured by steaming potential and microelectrophoresis methods, respectively. The adhesion and removal amount of $\alpha$-Fe2O3 particles on the from PET fabric increased with increasing time of adhesion and removal, and the rates of adhesion and removal were high at the initial stage of adhesion and removal, and then the rates decreased with passing time. The adhesion and removal amount of $\alpha$-Fe2O3 particles on and from PET fabric increased with increasing pH of solution regardless ionic strength. The tendencies and degree of adhesion and removal were very similar regardless interaction of surface charge of particle and fiber. Therefore, in the presence of a surfactant and electrolyte, the influence of interaction of surface charge of particle and substrate on the detergency of particulate soil was small.

• 한국세라믹학회지
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• 제37권7호
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• pp.705-712
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• 2000

In this study, the dispersion stability of CeO2 based complex oxide was studied, and density, porosity, and microstructure of green body were investigated using colloid surface chemistry to manufacture the Gd2O3 doped CeO2 solid electrolyte in an aqueous system. To prepare the stable slurry for slip casting, the dispersion stability was examined as a function of pH using ESA(electrokinetic sonic anplitude) analysis. The dynamic mobility of particles was enhanced with anionic and cationic dispersant were added the amount of 0.5wt% respectively, but pH value in slurries didn't move to below 6.0 because of the influence of dopants. This phenomenon also appeared in the CeO2-Y2O3 and CeO2-Sm2O3 systems, so it could be inferred that rare earth dopants such as Gd2O3, Sm2O3 and Y2O3 not only have the similar motion with changing pH in an aqueous system but also can be dissolved in the range of pH 6.0∼6.5. In CeO2-Gd2O3 system, when the anionic dispersant was added the amount of 0.5wt% and pH value in slurries was fixed at 9.5, the green body density was 4.07g/㎤, and the relative density of sintered body was 95.2%. It could be inferred from XRD analysis that Gd3+ substituted into Ce4+ site because there was no free Gd2O3 peak.

• Korean Chemical Engineering Research
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• 제59권3호
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• pp.373-378
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• 2021

본 연구는 땀에 존재하는 젖산을 연료로 사용하여 전기를 생산하는 웨어러블 연료전지용 고전력 젖산 산화효소 전극을 개발하는 데 그 목적이 있다. 유연성 있는 탄소종이 기반의 고정화효소 전극을 제작하고 평가하였다. 전해질 내 젖산농도 증가에 따라 젖산 산화효소(lactate oxidase, LOx)의 촉매작용으로 전류생성량이 증가하였다. 금 나노입자가 부착된 탄소종이에 고정화된 LOx가 탄소종이에 부착된 LOx보다 1.5배 많은 전류를 생성하였다. 빌리루빈 산화효소(bilirubin oxidase, BOD)가 고정화된 cathode는 질소로 퍼지(purge)된 전해질보다 산소로 포화된 전해질에서 높은 환원전류를 발생시켰다. 두 전극으로 구성된 연료전지를 제작하여 방전전류 변화에 따른 셀전압을 측정하였다. 방전 전류밀도 값이 66.7 ㎂/cm²에서 셀 전압은 0.5±0.0 V였고, 셀 전력량은 최대치인 33.8±2.5 ㎼/cm²를 나타내었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.75.2-75.2
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• 2010

Polymer electrolyte fuel cells (PEFCs) have received a lot of attention as a power source for both stationary and mobile applications due to their attractive feature. In general, the performance of PEFCs is highly affected by the property of the electrodes. A PEFC electrode essentially consists of a gas diffusion layer and a catalyst layer. The gas difusion layer is highly porous and hydrophobicized with PTFE polymer. The catalyst layer usually contains electrocatalyst, proton conducting polymer, even PTFE as additive. Particularly, the proton conducting ionomer helps to increase the catalytic activity at three-phase boundary and catalyst utilization. Futhermore, it helps to retain moisture, resulting in preventing the electrodes from membrane dehydration. The most widely used proton conducting ionomer is perfluorinated sulfonic acid polymer, namely, Nafion from DuPont due to its high proton conductivity and good mechanical property. However, there are great demands for alternative ionomers based on non-fluorinated materials in terms of high temperature availability, environmental adaptability and production cost. In this study, the electrodes with the various content of the sulfonated poly(ether sulfone) ionomer in the catalyst layer were prepared. In addition, we evaluated electrochemical properties of the prepared electrodes containing the various amount of the ionomers by using the cyclic voltammetry and impedance spectroscopy to find an optimal ionomer composition in the catalyst layer.

• 청정기술
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• 제7권3호
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• pp.215-223
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• 2001

A present semiconductor cleaning technology is based upon RCA cleaning technology which consumes vast amounts of chemicals and ultra pure water(UPW) and is the high temperature process. Therefore, this technology gives rise to the many environmental issues, and some alternatives such as electrolyzed water(EW) are being studied. In this work, intentionally contaminated Si wafers were cleaned using the electrolyzed water. The electrolyzed water was generated by an electrolysis system which consists of three anode, cathode, and middle chambers. Oxidative water and reductive water were obtained in anode and cathode chambers, respectively. In case of NH4Cl electrolyte, the oxidation-reduction potential and pH for anode water(AW) and cathode water(CW) were measured to be +1050mV and 4.8, and -750mV and 10.0, respectively. AW and CW were deteriorated after electrolyzed, but maintained their characteristics for more than 40 minutes sufficiently enough for cleaning. Their deterioration was correlated with CO2 concentration changes dissolved from air. Contact angles of UPW, AW, and CW on DHF treated Si wafer surfaces were measured to be $65.9^{\circ}$, $66.5^{\circ}$ and $56.8^{\circ}$, respectively, which characterizes clearly the eletrolyzed water. To analyze the amount of metallic impurities on Si wafer surface, ICP-MS was introduced. It was known that AW was effective for Cu removal, while CW was more effective for Fe removal. To analyze the number of particles on Si wafer surfaces, Tencor 6220 were introduced. The particle distributions after various particle removal processes maintained the same pattern. In this work, RCA consumed about $9{\ell}$ chemicals, while EW did only $400m{\ell}$ HCl electrolyte or $600m{\ell}$ NH4Cl electrolyte. It was hence concluded that EW cleaning technology would be very effective for promoting environment, safety, and health(ESH) issues in the next generation semiconductor manufacturing.

• 전기화학회지
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• 제18권2호
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• pp.51-57
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• 2015

상온 이온성 액체인 propylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMPyr-TFSI)를 리튬이차전지 전해질 용매로 사용 시 PMPyr-TFSI 내 수분 및 브롬 불순물이 전지의 성능에 미치는 영향을 연구하였다. 고전압 양극 물질인 $LiNi_{0.5}Mn_{1.5}O_4$ 스피넬 구조 양극을 이용한 반쪽 전지의 전해질로 PMPyr-TFSI를 사용 하는데 있어, PMPyr-TFSI의 수분 함유량을 각각 12, 77, 1060 ppm으로 제어하고 전압 곡선 개형 및 쿨롱 효율 거동 추적을 통해 PMPyr-TFSI 수분량이 전지 성능에 부정적인 영향을 미치는 것을 구체적으로 확인하였다. 또한, PMPyr-TFSI 전해질 내의 브롬 이온 불순물 양 제어를 통하여, 전지 내에서 브롬 이온 불순물과 관련한 전기화학 부반응을 찾아 내었다. 이들 할로겐 불순물에 의한 초기 전지 쿨롱 효율저하는 눈에 띠었으나, 수명 저하에는 큰 변화가 없음을 확인하였다.

• 한국산학기술학회논문지
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• 제7권4호
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• pp.727-732
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• 2006

본 연구에서는 전해질 성분 및 농도, 이온교환 수지 조성비율을 통해 이온교환 수지탑의 성능을 평가하고, 이온교환 수지에 의한 입자성 물질 제거의 능력과 입자성 물질이 이온교환 특성에 미치는 영향을 조사하였다. 이온교환 수지탑 배열 순서에 따라 파과(돌파)시점이 연장되며, 파과(돌파)순서는 음이온의 경우 $Cl^{-}, 양이온의 경우 $Na^{+} 순 이였으며, 전해질의 농도가 증가할수록 파과시간이 단축되었다. 이온교환 수지의 조성비 변화에서는 양음이온교환 수지 조성비가 1:2의 경우 1:1및 1:3의 경우보다 파과(돌파)시간이 연장되었으며 동일한 전해질 농도에서 입자 농도가 증가하면 20% 미만으로 파과(돌파)시간이 단축되었다. 양이온 교환수지 비율이 높으면 양이온의 파과(돌파)시점이 늦어져 이온교환 수지탑의 수명이 연장되고, 입자성 물질은 전해질 농도와 무관하게 이온교환 수지의 세공을 막아 이온교환 용량을 감소시켜 파과(돌파)시간을 단축시키는 것으로 조사되었다.