• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.649-654
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• 2017

An activated carbon was prepared from waste citrus peel produced in large amounts in Jeju Island, Korea, using KOH activation and its characteristics was examined. Under the condition of the KOH ratio between 100 and 300%, activation temperature from 400 to $900^{\circ}C$ and activation time from 0.5 to 1.5 h, the iodine adsorptivity of the activated carbon prepared increased but the yield decreased with respect to the increase of each conditions. The iodine adsorptivity and yield of the activated carbon prepared at the activation time of more than 1.5 h were similar to those of using 1.5 h. In addition, as the KOH ratio increased, the specific surface area and pore volume of the activated carbon increased, but the pore diameter decreased. The activated carbon has an average pore diameter of $20{\sim}25{\AA}$. Also, the activated carbon prepared at 300% KOH and $900^{\circ}C$ for 1.5 h has the highest specific surface area of $1,527m^2/g$ and iodine adsorptivity of 1,246 mg/g.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.280-285
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• 2006

Adsorption characteristics of $H_{2}S$ on KOH impregnated activated carbon were evaluated using dynamic adsorption method in a fixed bed. The pore properties, including BET's specific surface area, pore volume, pore size distribution, and mean pore diameter of these KOH impregnated activated carbons, were characterized from $N_{2}$ adsorption/desorption isotherms. Adsorption equilibrium data were correlated with Langmuir and Freundlich isotherms. The adsorption of $H_{2}S$ onto the KOH impregnated activated carbon is better fitted by the Langmuir isotherm. An increase in the content of oxygen affects the performance of KOH impregnated activated carbon to the greatest extent.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.521-523
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• 2009

본 연구에서는 식물성유지와 메탄올로부터 전이에스테르화 반응에 의해 바이오디젤 제조에 사용되는 비균질촉매로 사용하기 위하여 NaX 제올라이트 촉매에 염기도를 향상시키기 위하여 KOH를 담지하여 담지량에 따른 바이오디젤 제조특성을 조사해보았다. KOH 담지량을 10wt% - 70wt%로 달리하여 Incipient wetness 방법으로 담지한후 $500^{\circ}C$에서 소성하여 촉매를 제조하고, 제조된 KOH의 담지량이 다른 KOH/NaX 제올라이트 촉매는 SEM, XRD, BET등을 통해 촉매특성을 평가하였고, 생성된 지방산 메틸에스테르는 가스크로마토그래피로 순도를 측정하였다. NaX 제올라이트 촉매에 KOH 담지량이 높은 경우와 촉매량이 많은 경우 바이오디젤제조에 유리하였고, 특히 반응시간과 반응온도는 $120^{\circ}C$, 2시간동안 반응한 경우 가장 좋은 지방산 메틸에스테르의 수율을 얻을 수 있었다.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.286-293
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• 1998

Two methods were used to enhance the adsorption capacity of activated carbons. One is to impregnate activated carbons with chemical compounds which have a good affinity for $CO_2$. The other is to activate by heat-treating after impregnation with KOH on activated carbons(AC). The chemical compounds impregnated on AC were alkali metal, alkaline earth metal, and transition metal chlorides. The adsorption capacity of $CO_2$ on AC impregnated with these metals was less than that of pure AC. These compounds have not the chemical affinity for $CO_2$ and obstruct the micropore of AC. The experiment of breakthrough for $CO_2$ on AC impregnated with KOH showed the increase of the adsorbed amount of $CO_2$ in influent gases containing water vapor. This means that KOH adsorbes $CO_2$ gas. However, the adsorbents impregnated with KOH had not the reproducibility because of the production of $K_2CO_3$ by the reaction of KOH with $CO_2$. The amount of $CO_2$ adsorbed on the heat-treated AC at $800^{\circ}C$ increased with the amount of impregnation. The adsorption capacity of $CO_2$ was the largest when the ratio of weight of KOH to AC equal to 4. The isosteric heat of adsorption was calculated by the equation of Clausius-Clapeyron form adsorption capacity data of $CO_2$ for the temperature change. In addition, the characteristics of $CO_2$ breakthrough curve were surveyed for the change of flow rate and concentration.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.205-212
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• 2016

This research investigates the influence of ground granulated blast furnace slag (GGBFS) composition on the alkali-activated slag cement (AASC). Aluminum oxide ($Al_2O_3$) was added to GGBFS binder between 2% and 16% by weight. The alkaline activators KOH (potassium hydroxide) was used and the water to binder ratio of 0.50. The strength development results indicate that increasing the amount of $Al_2O_3$ enhanced hydration. The 2M KOH + 16% $Al_2O_3$ and 4M KOH + 16% $Al_2O_3$ specimens had the highest strength, with an average of 30.8 MPa and 45.2 MPa, after curing for 28days. The strength at 28days of 2M KOH + 16% $Al_2O_3$ was 46% higher than that of 2M KOH (without $Al_2O_3$). Also, the strength at 28days of 4M KOH + 16% $Al_2O_3$ was 44% higher than that of 4M KOH (without $Al_2O_3$). Increase the $Al_2O_3$ contents of the binder results in the strength development at all curing ages. The incorporation of AASC tended to increases the ultrasonic pulse velocity (UPV) due to the similar effects of strength, but increasing the amount of $Al_2O_3$ adversely decreases the water absorption and porosity. Higher addition of $Al_2O_3$ in the specimens increases the Al/Ca and Al/Si in the hydrated products. SEM and EDX analyses show that the formation of much denser microstructures with $Al_2O_3$ addition.

• Journal of Environmental Science International
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• v.12 no.12
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• pp.1321-1327
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• 2003

Two different kinds of cases, with and without addition of noncrystalline silica to the Hadong kaolin were studied to obtain useful information on the synthesis of zeolite. The research was carried out to investigate the formation area and the crystalized degree of zeolite according to a synthetic time, the water content of raw material mixture, KOH concentration, and stirring intensity. In the case of without addition of noncrystalline silica to the Hadong kaolin and the low concentration range of KOH, the structure of the kaolin was not changed. However, when the mole ratio of K2O/SiO$_2$ in natural kaolin was increased, Linde-L zeolite and unknown structure of kaolins, U-1 and U-2 were produced. While in the high concentration range of KOH, the unknown structure of kaolins, U-6 and U-2, were produced and the production rate of U-6 was increased with the increased of K2O/SiO$_2$ mole ratio. In the case of with addition of noncrystalline silica to the Hadong kaolin and treatment with KOH hydrothermal processing, ZSM-5, ZSM-35, and Linde-L zeolites and the mixture of unknown structure of zeolites, U-1, U-2, U-3, and U-4, were obtained. Both cases demonstrated that the synthesis of zeolite from the Hadong kaolin was highly influenced by KOH concentration of raw material mixture.

• Elastomers and Composites
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• v.14 no.4
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• pp.231-252
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• 1979

Polymerization of 2-pyrrolidone was carried out through anionic mechanism using $SO_2/KOH$ as catalyst. The effects of KOH concentration, $SO_2/KOH$ mole ratio and temperature on polymerization were investigated. The conversion and viscosity of polymers were measured at various polymerization conditions. It was observed that as the concentration of KOH was increased, equilibrium conversion was also increased. It was, however, found that after the concentration of KOH was reached above 8 mole percent, the equilibrium conversion was decreased. The highest rate of polymerization and maximum conversion were obtained when $SO_2/KOH$ mole ratio was around 0.5. It was also found that the rate of polymerization and the equilibrium conversion were higher at $50^{\circ}C$. than at $30^{\circ}C$. but the viscosity of polymer solution at $50^{\circ}C$. was not so high as expected. The rate constant, $K_p$ of polymerization, was determined by least square method: the value of $K_p$ was observed as 16 liter/mole hour at $50^{\circ}C$. and 2.6 liter/mole hour at $30^{\circ}C$., respectively. The mechanism of polymerization was also discussed.

• Journal of the Korean Chemical Society
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• v.21 no.2
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• pp.132-138
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• 1977

Anionic polymerization of ${\varepsilon}$-caprolactam via $SO_2$/KOH catalysis was attempted in order to find an optimal reaction condition and physical properties of the polymers. The yield of conversion was relatively low at low temperature and high at high temperature between $150^{\circ}C\;to\;180^{\circ}C$ regardless of $SO_2$/KOH mole ratio in polymerization of ${\varepsilon}$-caprolactam.The inherent viscosity of nylon 6 obtained via $SO_2$/KOH catalysis was 1.2∼2.7. The kinetic equation for the $SO_2$/KOH catalyzed polymerization has been derived and experimentally verified.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.299.2-299.2
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• 2013

We investigated the potassium remaining on a crystalline silicon solar cell after potassium hydroxide (KOH) etching and its effect on the lifetime of the solar cell. KOH etching is generally used to remove the saw damage caused by cutting a Si ingot; it can also be used to etch the rear side of a textured crystalline silicon solar cell before atomic layer-deposited Al2O3 growth. However, the potassium remaining after KOH etching is known to be detrimental to the efficiency of Si solar cells. In this study, we etched a crystalline silicon solar cell in three ways in order to determine the effect of the potassium remnant on the efficiency of Si solar cells. After KOH etching, KOH and tetramethylammonium hydroxide (TMAH) were used to etch the rear side of a crystalline silicon solar cell. To passivate the rear side, an Al2O3 layer was deposited by atomic layer deposition (ALD). After ALD Al2O3 growth on the KOH-etched Si surface, we measured the lifetime of the solar cell by quasi steady-state photoconductance (QSSPC, Sinton WCT-120) to analyze how effectively the Al2O3 layer passivated the interface of the Al2O3 layer and the Si surface. Secondary ion mass spectroscopy (SIMS) was also used to measure how much potassium remained on the surface of the Si wafer and at the interface of the Al2O3 layer and the Si surface after KOH etching and wet cleaning.

• Polymer(Korea)
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• v.36 no.3
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• pp.321-325
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• 2012

In this work, we prepared the activated graphite nanofibers (A-GNFs) via chemical activation with KOH/GNFs ratios in a range of 0 to 5. The effect of KOH activation was studied in the surface and pore properties of the samples for electrochemical performance. The surface properties of A-GNFs were characterized by XRD and SEM measurements. The textural properties of the A-GNFs were investigated by $N_2$/77 K adsorption isotherms using Brunauer-Emmett-Teller (BET) equation. Their electrochemical behaviors were investigated by cyclic voltammetry and galvanostatic charge-discharge performance. From the results, electrochemical performances of the A-GNFs were improved with increasing the ratio of KOH reagent. It was found that specific surface area and total pore volume of the A-GNFs were increased by KOH activation.