• 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.

• Resources Recycling
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• v.17 no.5
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• pp.66-75
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• 2008

Using a pinus koraiensis and pinus rigida which are normally being discarded in South Korea, the optimal condition of producing charcoals has been studied to develop activated carbons which can be recycled as a higher value-added product. A study on manufacture of activated carbons from a discarded timber consists of two processes, the production process of charcoals from a discarded timber by low temperature pyrolysis process and the production process of activated carbons from the charcoals by chemical activation reaction. This study deals with the production process of charcoals from a discarded timber by low temperature pyrolysis process. As a results of experiment, it was investigated that charcoals produced through drying at $150^{\circ}C$ for 6hr and pyrolysis process at $500^{\circ}C$ for 1hr had the highest values in physical properties such as iodine number and BET surface area. Furthermore, through observing SEM images, the maximum development of porosity had been founded in this condition. It was confirmed that values of physical properties on using a pinus koraiensis are superior to the ones when using a pinus rigida. When charcoals were produced from a pinus koraiensis in this condition, BET surface area was approx. $640m^2/g$.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.425-431
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• 2005

New type of supercapacitor using high surface area activated carbons mixed with high conductivity polypyrrole (Ppy) has been prepared in order to achieve low impedance and high energy density. Mixed carbons of BP-20 and MSP-20 were used as the active electrode material, and polypyrrole doped with 2-naphthalenesulfonic acid (2-NSA) and carbon black (Super P) as conducting agents were added to activated carbons in order to enhance good electric conductivity. Electrodes prepared with the activated electrode materials and the conducting agents were added to a solution of organic binder [P(VdF-co-HFP) / NMP]. The ratio of optimum electrode composition was 78 : 17 : 5 wt.％ of (MSP20 : BP-20=1 : 1), (Super P : Ppy=10 : 7) and P(VdF-co-HFP) respectively. The performance of unit cell with addition of 7 wt％ Ppy have shown specific capacitance of 28.02 F/g, DC-ESR of $1.34{\Omega}$, AC-ESR of $0.36{\Omega}$, specific energy of 19.87 Wh/kg and specific power of 9.77 kW/kg. With addition of Ppy, quick charge-discharge of unit cell was possible because of low ESR, low charge transfer resistance and quick reaction rate. And good stability up to 500 chargedischarge cycles were retained about 80％ of their original capacity. It was concluded that the specific capacitance originated highly from compound phenomena of the pseudocapacitance by oxidation-reduction of polypyrrole and the nonfaradaic capacitance by adsorption-desorption of activated carbons.

• Korean Journal of Materials Research
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• v.31 no.5
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• pp.264-271
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• 2021

Porous carbons have been widely used as electrode material for supercapacitors. However, commercial porous carbons, such as activated carbons, have low electrochemical performance. Nitrogen-doping is one of the most promising strategies to improve electrochemical performance of porous carbons. In this study, nitrogen self-doped porous carbon (NPC) is prepared from melamine foam by carbonization to improve the supercapacitive performance. The prepared NPC is characterized in terms of the chemical structures and elements, morphology, pore structures, and electrochemical performance. The results of the N₂ physisorption measurement, X-ray diffraction, and Raman analyses reveal that the prepared NPC has bimodal pore structures and pseudo-graphite structures with nitrogen functionality. The NPC-based electrode exhibits a gravimetric capacitance of 153 F g^-1 at 1 A g^-1, a rate capability of 73.2 % at 10 A g^-1, and an outstanding cycling ability of 97.85 % after 10,000 cycles at 10 A g^-1. Thus, the NPC prepared in this study can be applied as electrode material for high-performance supercapacitors.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.277-285
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• 2007

The adsorption characteristics of multi-component solvent vapors including poorly-adsorbable chemicals such as toluene-xylene-MEK and toluene-MEK-IPA on the activated carbonaceous adsorbents were investigated in a stainless steel fixed bed of 10.2 cm ID and 50 cm in height in order to identify those carbons for eliminating and recovering solvent vapors from industrial emission sources. The used activated carbonaceous adsorbents were pelletized commercial activated carbons and activated carbon fiber. Breakthrough curves and adsorption capacity at atmospheric pressures were obtained. It has been found that non-polar and larger molecules have been adsorbed better than polar and smaller molecules. In special, alcohols and ketones were poorly adsorbed caused by competitive adsorbability in multi-component mixture system. However, it could be overcome by profitable employment of organization of cooperative system which was composed of different porosity activated carbonaceous adsorbents appropriately.

• Clean Technology
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• v.24 no.4
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• pp.287-292
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• 2018

Effect of physical property of activated carbon on its carbon dioxide adsorption was investigated for the effective control of carbon dioxide. Pinewood sawdust and coal were used as raw materials of activated carbon. Specific surface area, micropore volume and mesopore volume of the prepared activated carbons were determined, respectively. The prepared activated carbons were analyzed for their adsorption capacity of carbon dioxide. The adsorption capacity was then presented with respect to the surface area, micropore volume and mesopore volume, respectively. As a result, the specific surface area and micropore volume of both pinewood and coal activated carbon were highly related to its carbon dioxide capacity. Its mesopore volume hardly affected its carbon dioxide capacity. Preparation of activated carbon with high specific surface area and micropore volume was found to be critical to the effective control of carbon dioxide.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.311-312
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• 2003

Activated carbons (ACs) are widely used in adsorption for the removal of gaseous and aqueous pollutants[1]. Although a wide range of carbonaceous materials can be converted into ACs, the coal and lingocellulosic materials are the most commonly used starting materials for the production of commercial ACs. Recently, there are a quite large number of studies regarding the preparation of ACs from various polymeric materials because of high carbon yield and low ash content In this work, ACs are prepared from polystyrene (PS) by chemical activation with potassium hydroxide and the effect of the KOH-to-PS ratio to adsorption of ammonia is investigated. (omitted)

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.173-174
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• 2003

Activated carbons (ACs) are widely used in adsorption for the removal of gaseous and aqueous pollutants[1,2]. The microbicidal property of ACs is also very important, in order to decrease the risk of water and air contamination with microorganisms. For this purpose, ACs have impregnated with silver or with metallic oxides[2]. However, in the case of Ag supported ACs prepared by impregnation, there are some problem, such as, heat-treatment, highly decrease in specific surface area and pore volume by deposited Ag, and rapidly elution of Ag at the initial stage of usage[3]. (omitted)

• Journal of the Korean Electrochemical Society
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• v.17 no.4
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• pp.237-244
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• 2014

We report novel and simple structure of supercapacitors fabricated by using flexible glass fibre separators as templates. This method does not require separate electrodes, binders and high pressure/temperature to build the supercapacitor unit cells as required by the conventional technology. The supercapacitors were fabricated by drop-casting solution mixtures of carbonaceous active materials/gel electrolytes onto two sides of glass fibre separators. Two carbonaceous materials (nanoscaled activated carbons, multi-walled carbon nanotubes) were investigated as electrode materials. The electrochemical measurements reveal that the separatorbased supercapacitors using ACs successfully demonstrated significant mass specific capacitance ($22.3F\;g^{-1}$) and energy density ($9.7Wh\;kg^{-1}$), indicating this method can be useful in fabricating flexible, wearable and stretchable energy storage devices in more straightforward and cost-effective way than current technology.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.312-316
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• 2005

Adsorption characteristics of $CO_2$ on activated carbons were evaluated using dynamic adsorption method in a fixed bed with acid treatment, LiOH impregnation and water vapor supply. Physical and chemical properties of the activated carbons were measured using SEM, EDS, nitrogen adsorption, FTIR and XRD. Nitric acid treatment led to the decrease in BET surface area and the increase in oxygen content of virgin activated carbon, and it produced a new functional group that included nitrogen. For the reduction of BET surface area by LiOH impregnation, the nitric acid treated activated carbon (NAC) was less than the virgin activated carbon (AC). Large particles of LiOH were present on the carbon surface when the content of LiOH was over 2 wt%. The adsorbed amount of $CO_2$ on activated carbon in a fixed bed increased with the acid treatment, LiOH impregnation and water vapor supply. The XRD results indicated that LiOH was converted to $Li_2CO_3$ after the adsorption of $CO_2$ on LiOH precursor.