• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.85-88
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• 2008

We calculated the electronic structures of substituted cobalt nitrides, that is $FeCo_3N$ and $NiCo_3Ni$, by using the all electron fullpotential linearized augmented plane-wave (FLAPW) energy band method, and investigated the influence on the magnetic properties of $Co_4N$ due to the substitution of Co atom located at corner sites by iron and nickel atoms. We found that the magnetic moments of CoII atoms located at the face-center positions in these compounds are almost same to that of $Co_4N$. The magnetic moments of Fe and Ni atoms in $FeCo_3N$ and $NiCo_3Ni$ are 3.086 and $0.795\;{\mu}_B$, and they have the localized nature of magnetism.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.421-426
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• 1994

This study was carried out to investigate the effect of $CaCO_3$ on the Chungkookjang Meju fermentation. B. subtilis was cultured on the Meju added 0, 0.01, 0.1, 1% $CaCO_3$, respectively, and the chemical composition, protease activity, amino acid and vitamin B complex were examined with fermentation time. The inner temperature of the $CaCO_3$ treatments during fermentation was increased as compared with the control group. Titratable acidity in Meju decreased as $CaCO_3$ concentration increased. And protease activity and amino-nitrogen content were however high in same order. The content of amino acid was on the increase in every treatments, it made no difference between $CaCO_3$, treatments and the control. Vitamin B complex content in the $CaCO_3$ treatments was increased than in the control. The 0.01% added treatment showed the highest amount of vitamin B complex content in all the treatments.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.1
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• pp.41-52
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• 2021

NiO and Co3O4-doped porous La(CoNi)O3 perovskite oxides were prepared from excess Ni addition by a hydrothermal method using porous silica template, and characterized as bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for Zn-air rechargeable batteries in alkaline solution. Excess Ni induced to form NiO and Co3O4 in La(CoNi)O3 particles. The NiO and Co3O4-doped porous La(CoNi)O3 showed high specific surface area, up to nine times of conventionally synthesized perovskite oxide, and abundant pore volume with similar structure. Extra added Ni was partially substituted for Co as B site of ABO3 perovskite structure and formed to NiO and Co3O4 which was highly dispersed in particles. Excess Ni in La(CoNi)O3 catalysts increased OER performance (259 mA/㎠ at 2.4 V) in alkaline solution, although the activities (211 mA/㎠ at 0.5 V) for ORR were not changed with the content of excess Ni. La(CoNi)O3 with excess Ni showed very stable cyclability and low capacity fading rate (0.38 & 0.07 ㎶/hour for ORR & OER) until 300 hours (~70 cycles) but more excess content of Ni in La(CoNi)O3 gave negative effect to cyclability.

• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.168-172
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• 2006

Potentiometric $CO_{2}$ sensors were fabricated using a NASICON ($Na_{1+x}Zr_{2}Si_{X}P_{3-X}O_{12}$, 1.8 < x < 2.4) thick film and auxiliary layers. The powder of a precursor of NASICON with high purity was synthesized by a sol-gel method. By using the NASICON paste, an electrolyte was prepared on the alumina substrate by screen printing and then sintered at $1000^{\circ}C$ for 4 h. A series of $Na_{2}CO_{3}-CaCO_{3}$ auxiliary phases were deposited on the Pt sensing electrode. The electromotive force (emf) values were linearly dependent on the logarithm of $CO_{2}$ concentration in the range between 1,000 and 10,000 ppm. The device attached with $Na_{2}CO_{3}-CaCO_{3}$ (1:2 in mol.%) showed good sensing properties in the low temperatures.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.520-527
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• 1988

The crystal structures of $Co^{2+}\;and\;Ag^+\;exchanged\;zeolite\; A,\; Ag_6Co_3$-A(a = 12.131(5)$\AA$) and $Ag_3Co_{4.5}$-A(a = 12.145(1)$\AA$), have been determined by single crystal X-ray diffraction techniques. Both structures were solved and refined in the cubic space group Pm3m at 21(1)$^{\circ}C$. Full-matrix leastsquares refinement converged to the final error indices of R1 = 0.045 and R2 = 0.041 for $Ag_3Co_{4.5}-A,\; and\; R1 = 0.066\; and\; R2 = 0.076\; for\; Ag_6Co_3$-A using the 258 and 189 reflections, respectively, for which I > 3$\sigma$(I). Both structures indicate that CO(Ⅱ)ions are coordinated by three framework oxygens; the Co(II) to O(3) distances are 2.118(4)$\AA$ for $Ag_3Co_{4.5}$-A and 2.106(1)$\AA$ for $Ag_6Co_3-A$, respectively. In each structure, the angle substended at Co(II), O(3)-Co(II)-O(3) is ca 120°, close to the idealized trigonalplanar value. $Co^{2+}$ ions prefer to 6-ring sites and $Ag^+$ ions prefer to 8-ring site when total number of cations is more than 8. The crystals of hydrated and dehydrated $Ag_{12-2x}Co_x-A (x > 4.5)$ had no crystalline diffraction pattern, indicating the apparent exchange limit of $Co^{2+}\; into\; Ag_{12}-A\; is\; 4.5 Co^{2+}$ ions per unit cell. $Co^{2+}$ ions hydrolyze $H_2O$ molecules and $H_3O^+$ concentraction is accumulating. These $H_3O^+$ ions destroy the zeolite structures.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.606-612
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• 2022

Relatively high indoor CO₂ concentration (>1,000 ppm) has a negative impact on human health. In this work, indoor CO₂ adsorbent was developed by impregnating KOH or K₂CO₃ on commercial activated carbon, named as KOH/AC and K₂CO₃/AC. Commercial activated carbon (AC) showed relatively high BET surface area (929 m²/g) whereas KOH/AC and K₂CO₃/AC presented lower BET surface area of 13.6 m²/g and 289 m²/g. Two experimental methods of TGA (2,000 ppmCO₂, weight basis) and chamber test (initial concentration: 2,000 ppmCO₂, CO₂ IR analyzer) were used to investigate the adsorption capacity. KOH/AC and K₂CO₃/AC exhibited similar adsorption capacities (145~150 mg_CO2/g), higher than K₂CO₃/Al+Si supports adsorbent (84.1 mg_CO2/g_sample). Similarly, chamber test also showed similar trend. Both KOH/AC and K₂CO₃/AC represented higher adsorption capacities (KOH/AC: 93.5 mg_CO2/g K₂CO₃/AC: 94.5 mg_CO2/g_sample) K₂CO₃/Al+Si supports. This is due to the KOH or K₂CO₃ impregnation increased alkaline active sites (chemical adsorption), which is beneficial for CO₂ adsorption. In addition, the regeneration test results showed both K-based adsorbents pose a good regeneration and reusability. Finally, the current study suggested that both KOH/AC and K₂CO₃/AC have a great potential to be used as CO₂ adsorbent for indoor CO₂ adsorption.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.230-236
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• 2021

Ionic conduction mechanism of Mg-Al layered double hydroxides (LDHs) intercalated with CO₃^2- (Mg-Al CO₃^2- LDH) was studied. The electromotive force for the water vapor concentration cell using Mg-Al CO₃^2- LDH as electrolyte showed water vapor partial pressure dependence and obeyed the Nernst equation, indicating that the hydroxide ion transport number of Mg-Al CO₃^2- LDH is almost unity. The ionic conductivity of Mg(OH)₂, MgCO₃ and Al₂(CO₃)₃ was also examined. Only Al₂(CO₃)₃ showed high hydroxide ion conductivity of the order of 10^-4 S cm^-1 under 80% relative humidity, suggesting that Al₂(CO₃)₃ is an ion conducting material and related to the generation of carrier by interaction with water. To discuss the ionic conduction mechanism, Mg-Al CO₃^2- LDH having deuterium water as interlayer water (Mg-Al CO₃^2- LDH(D₂O)) was prepared. After the adsorbed water molecules on the surface of Mg-Al CO₃^2- LDH(D₂O) were removed by drying, DC polarization test for dried Mg-Al CO₃^2- LDH(D₂O) was examined. The absorbance attributed to O-D-stretching band for Mg-Al CO₃^2- LDH(D₂O) powder at around the positively charged electrode is larger than that before polarization, indicating that the interlayer in Mg-Al CO₃^2- LDH is a hydroxide ion conduction channel.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.177.1-177.1
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• 2011

온실가스 감축에 대응하기 위해서 CCS기술이 지구온난화 문제를 해결하는 중요한 기술로 부각되고 있다. $CO_2$ 포집기술 중 습식법에는 대표적으로 아민, 암모니아, $K_2CO_3$와 같은 흡수제를 이용한 연구가 진행되고 있다. 본 연구에서는 $CO_2$ 포집기술 중 하나인 $K_2CO_3$ 수용액을 이용하여 Bench급 $CO_2$ 포집설비에 대한 성능을 파악하기 위한 일환으로 15% $CO_2$를 공급하여 $CO_2$ 포집 안정화 시험을 진행하였다. 압력변화 및 단수 변화를 하여 실험을 진행하였고, 흡수탑 후단의 $CO_2$ 농도를 측정하여 $CO_2$ 포집 성능을 파악하였다.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.3
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• pp.185-191
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• 2014

In this paper, absorption and reaction characteristics of low $CO_2$ and alkanolamines were investigated. As MEA concentrations increase 1, 2 and 3 wt%, $CO_2$ loadings decrease 0.34 mol-$CO_2/mol$-absorbent, 0.32 mol-$CO_2/mol$-absorbent and 0.3 mol-$CO_2/mol$-absorbent, respectively. Also, $CO_2$ loadings decrease from 0.32 mol-$CO_2/mol$-absorbent, 0.30 mol-$CO_2/mol$-absorbent and 0.28 mol-$CO_2/mol$-absorbent as AMP concentrations increase 1, 2 and 3 wt%. Experimental results with blending solutions show that $CO_2$ loading was the highest, 0.52 mol-$CO_2/mol$-absorbent, when 0.5 wt% MEA and 0.5 wt% AMP were blended.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.602-606
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• 2009

The absorption capacity and initial absorption rate in 5 %, 10%, 15 % and 20% $Na_{2}CO_{3}$ under the constant temperature at $40^{\circ}C$ and the initial absorption rate in mixture of different alkaline salts such as $KHCO_3$, $CaCO_3$ and $K_{2}CO_{3}$ were measured using batch type stirred cell contractor. 10% $Na_{2}CO_{3}$ showed the highest absorption capacity and $Na_{2}CO_{3}$ and $K_{2}CO_{3}$ showed the somewhat increased absorption capacity and initial absorption rate respectively. Further more, we have studied the effect of adding Pz and Pp to $Na_{2}CO_{3}$. The result showed that absorption rate of $CO_2$ was increased by adding these additives.