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        검색결과 338

        141.
        2015.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbonate-type organic electrolytes were prepared using propylene carbonate (PC) and dimethyl carbonate (DMC) as a solvent, quaternary ammonium salts, and by adding different contents of 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMImBF4). Cyclic voltammetry and linear sweep voltammetry were performed to analyze conducting behaviors. The surface characterizations were analyzed by scanning electron microscopy method and X-ray photoelectron spectroscopy. From the experimental results, increasing the EMImBF4 content increased the ionic conductivity and reduced bulk resistance and interfacial resistance. In particular, after adding 15 vol% EMImBF4 in 0.2 M SBPBF4 PC/DMC electrolyte, the organic electrolyte showed superior capacitance and interfacial resistance. However, when EMImBF4 content exceeded 15 vol%, the capacitance was saturated and the voltage range decreased.
        4,000원
        142.
        2015.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        High crystallinity coke-based activated carbon (hc-AC) is prepared using a potassium hydroxide solution to adsorb carbon dioxide (CO2). The CO2 adsorption characteristics of the prepared hc-AC are investigated at different temperatures. The X-ray diffraction patterns indicate that pitch-based cokes prepared under high temperature and pressure have a high crystal structure. The textural properties of hc-AC indicate that it consists mainly of slit-like pores. Compared to other textural forms of AC that have higher pore volumes, this slit-poreshaped hc-AC exhibits higher CO2 adsorption due to the similar shape between its pores and CO2 molecules. Additionally, in these high-crystallinity cokes, the main factor affecting CO2 adsorption at lower temperature is the pore structure, whereas the presence of oxygen functional groups on the surface has a greater impact on CO2 adsorption at higher temperature.
        4,000원
        143.
        2014.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to prepare high-quality activated carbons (ACs), coal tar pitch (CTP), and mixtures of CTP and petroleum pitch (PP) were activated with KOH. The ACs prepared by activation of CTP in the range of 700~1000℃ for 1~5 h had very porous textures with large specific surface areas of 2470~3081 m2/g. The optimal activation conditions of CTP were determined as CTP/KOH ratio of 1:4, activation temperature of 900℃, and activation time of 3 h. The obtained AC showed the highest micro-pore volume, and pretty high specific surface area and meso-pore volume. The micro-pore volumes and specific areas of activated mixtures of CTP and PP were similar to each other but the meso-pore volume could be increased. In order to change the degree of crystallinity of precursors before KOH activation process, the CTPs were carbonized in the range of 500~900℃. As the carbonization temperature increased, the specific surface area and pore volume of the activated ACs with the same activation conditions for CTP decreased dramatically. It was demonstrated that the increased pore size distribution of AC electrodes in the range of 1 to 2 nm plays an important role in the performance of electric double-layer capacitor.
        4,000원
        144.
        2014.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The adsorption of volatile organic compounds (VOCs) was carried out using an activated carbon fiber (ACF) filter in an automobile. The adsorption capacities of formaldehyde, toluene, and benzene on an ACF filter were far better than those of a polypropylene (PP) mat filter and combined (PP+activated carbon) mat filter by batch adsorption in a gas bag. In a continuous flow of air containing toluene vapor through an ACF packed bed, the breakpoint time was very long, the length of the unused bed was short, and sharp "S" -type breakthrough curve was plotted soon after breakpoint, showing a narrow mass transfer zone of toluene on the ACF. The adsorption amount of toluene on the ACF filter was proportional to the specific surface area of the ACF; however, the development of mesopores 2-5 nm in size on the ACF was very effective with regard to the adsorption of toluene. The ACF air clarifier filter is strongly recommended to remove VOCs in newly produced automobiles.
        4,000원
        145.
        2014.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A hierarchical pore structured novolac-type phenol based-activated carbon with micropores and mesopores was fabricated. Physical activation using a sacrificialsilicon dioxide (SiO2) template and chemical activation using potassium hydroxide (KOH) were employed to pre-pare these materials. The morphology of the well-developed pore structure was character-ized using field-emissionscanning electron microscopy. The novolac-type phenol-based activated carbon retained hierarchical pores (micropores and mesopores); it exhibited high Brunauer-Emmett-Teller specificsurface areas and hierarchical pore size distributions. The hierarchical pore novolac-type phenol-based activated carbon was used as an electrode in electric double-layer capacitors, and the specificcapacitance and the retained capacitance ratio were measured. The specificcapacitances and the retained capacitance ratio were en-hanced, depending on the SiO2 concentration in the material. This result is attributed to the hierarchical pore structure of the novolac-type phenol-based activated carbon.
        4,000원
        146.
        2014.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study reports on the influenceof N-butyl-N-methylpyrrolidinium tetrafluoroborat (PYR14BF4) ionic liquid additive on the conducting and interfacial properties of organic solvent based electrolytes against a carbon electrode. We used the mixture of ethylene carbonate/dimethoxyethane (1:1) as an organic solvent electrolyte and tetraethylammo-nium tetrafluoroborate(TEABF4) as a common salt. Using the PYR14BF ionic liquid as additive produced higher ionic conductivity in the electrolyte and lower interface resis-tance between carbon and electrolyte, resulting in improved capacitance. The chemical and electrochemical stability of the electrolyte was measured by ionic conductivity me-ter and linear sweep voltammetry. The electrochemical analysis between electrolyte and carbon electrode was examined by cyclic voltammetry and electrochemical impedance spectroscopy.
        4,000원
        147.
        2014.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Commercial activated-carbon used as the electrode material of an electric double-layer capacitor (EDLC) was posttreated with various acids and alkalis to increase its capacitance. The carbon samples prepared were then heat-treated in order to control the amount of acidic functional groups formed by the acid treatments. Coin-type EDLC cells with two symmetric carbon electrodes were assembled using the prepared carbon materials and an organic electrolyte. The electrochemical performance of the EDLC was measured by galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. Among the various activated carbons, the carbon electrodes (CSsb800) prepared by the treatments of coconutshell-based carbon activated with NaOH and H3BO5, and then heat treated at 800˚C under a flow of nitrogen gas, showed relatively good electrochemical performance. Although the specific-surface-area of the carbon-electrode material (1,096m2/g) was less than that of pristine activated-carbon (1,122m2/g), the meso-pore volume increased after the combined chemical and heat treatments. The specific capacitance of the EDLC increased from 59.6 to 74.8 F/g (26%) after those post treatments. The equivalent series resistance of EDLC using CSsb800 as electrode was much lower than that of EDLC using pristine activated carbon. Therefore, CSsb800 exhibited superior electrochemical performance at high scan rates due to its low internal resistance.
        4,000원
        148.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the changes in collection efficiencies due to the time changes of activated carbons were ascertained, and in order to identify the magnitude of adsorption, the before-use and after-use iodine adsorption values were analyzed. In addition, as a result of examining the characteristics of continuous process and non-continuous process and as a result of investigating whether the emission standards would be maintained, the continuous process and printing facilities were seen as not being able to maintain the emission standards. Also were found, in the case of non-continuous process,–taking into consideration the special nature of the job –for 4Ø palletized charcoal, a collection efficiency near 50% was shown even after 96 hours. Also, when the inlet concentration was about 300ppm, it is thought that the emission standards would be maintained if the activated carbons are replaced within at least 96 hours in the case of 4Ø palletized charcoal and the use was deemed pointless in the case of carbon. The results of this study are expected to provide assistance in selecting replacement periods for activated carbons and in selecting absorbents at the project sites, and are expected to be of significant help in the selection of precipitators that can collect total hydrocarbons for compliance of the emission standards.
        4,000원
        149.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, activated carbon nanofiber(ACNF) electrodes with high double-layer capaci-tance and good rate capability were prepared from polyacrylonitrile nanofibersby optimiz-ing the carbonization temperature prior to H2O activation. The morphology of the ACNFs was observed by scanning electron microscopy. The elemental composition was determined by analysis of X-ray photoelectron spectroscopy. N2-adsorption-isotherm characteristics at 77 K were confirmedby Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. ACNFs processed at different carbonization temperatures were applied as electrodes for electrical double-layer capacitors. The experimental results showed that the surface mor-phology of the CNFs was not significantlychanged after the carbonization process, although their diameters gradually decreased with increasing carbonization temperature. It was found that the carbon content in the CNFs could easily be tailored by controlling the carbonization temperature. The specificcapacitance of the prepared ACNFs was enhanced by increasing the carbonization temperature.
        4,000원
        150.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The widespread occurrence of dissolved endocrine disrupting compounds(EDCs) and pharmaceutical active compounds(PhACs) in water sources is of concern due to their adverse effects. To remove these chemicals, adsorption of EDCs/PhACs on granular activated carbon(GAC) was investigated, and bisphenol A, carbamazepine, diclofenac, ibuprofen, and sulfamethoxazole were selected as commonly occurring EDCs/PhACs in the aquatic environment. Various adsorption isotherms were applied to evaluate compatability with each adsorption in the condition of single-solute. Removal difference between individual and competitive adsorption were investigated from the physicochemical properties of each adsorbate. Hydrophobicity interaction was the main adsorption mechanism in the single-solute adsorption with order of maximum adsorption capacity as bisphenol A ≻ carbamazepine ≻ sulfamethoxazole ≻ diclofenac ≻ ibuprofen, while both hydrophobicity and molecular size play significant roles in competitive adsorption. Adsorption kinetic was also controled by hydrophobicity of each adsorbate resulting in higher hydrophobicity allowed faster adsorption on available adsorption site on GAC. EDCs/PhACs adsorption on GAC was determined as an endothermic reaction resulting in better adsorption at higher temperature (40 ◦C) than lower temperature (10 ◦C#x25E6;C).
        4,600원
        151.
        2014.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Activated carbon nanofibers(ACNF) were prepared from polyacrylonitrile (PAN)-based nanofibersusing CO2 activation methods with varying activation process times. The surface and structural characteristics of the ACNF were observed by scanning electron microscopy and X-ray diffraction, respectively. N2 adsorption isotherm characteristics at 77 K were con-firmedby Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. As experimental results, many holes or cavernous structures were found on the fibersurfaces after the CO2 activation as confirmedby scanning electron microscopy analysis. Specificsurface areas and pore volumes of the prepared ACNFs were enhanced within a range of 10 to 30 min of acti-vation times. Performance of the porous PAN-based nanofibersas an electrode for electrical double layer capacitors was evaluated in terms of the activation conditions.
        4,000원
        152.
        2014.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, synthetic viscose rayon fabric has been used for preparing activated carbon fabric (ACF), impregnated with different concentrations of H3PO4. The effect of H3PO4 im-pregnation on the weight yield, surface area, pore volume, chemical composition and mor-phology of ACF were studied. Experimental results revealed that both Brunauer-Emmett-Teller surface area and micropore volume increased with increasing H3PO4 concentration; however, the weight yield and microporosity (%) decreased. It was observed that samples impregnated at 70°C (AC-70) give higher yield and higher microporosity as compared to 30°C (AC-30). The average pore size of the ACF also gradually increases from 18.2 to 19 and 16.7 to 20.4 Å for 30°C and 70°C, respectively. The pore size distribution of ACF was also studied. It is also concluded that the finalACF strength is dependent on the concentra-tion of impregnant.
        4,000원
        153.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Potassium hydroxide-activated carbons (CK21, CK11, and CK12) were prepared from pis-tachio nutshells. Physicochemical properties of activated carbons were characterized by TGA, pHpzc, Fourier transform infrared spectroscopy, scanning electron microscopy, and N2-adsorption at -196°C. The examinations showed that activated carbons have high sur-face area ranging between 695-1218 m2/g, total pore volume ranging between 0.527-0.772 mL/g, and a pore radius around 1.4 nm. The presence of acidic and basic surface C-O groups was confirmed.Batch adsorption experiments were carried out to study the effects of adsorbent dosage, temperature, initial concentration of adsorbate, and contact time on deltamethrin adsorption by activated carbons. The kinetic studies showed that the adsorp-tion data followed a pseudo-second order kinetic model. The Langmuir model showed a maximum adsorption capacity of 162.6 mg/g at 35°C on CK12. Thermodynamic studies indicated that adsorption was spontaneous and increased with temperature, suggesting an endothermic process.
        4,000원
        154.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study blast furnace slag, an industrial byproduct, was used with an activating chemicals, Ca(OH)2 and Na2SiO3 for carbon capture and sequestration as well as strength development. METHODS: This paper presents the optimized mixing design of Carbon-Capturing and Sequestering Activated Blast-Furnace Slag Mortar. Design of experiments in order to the optimized mixing design was applied and commercial program (MINITAB) was used. Statistical analysis was used to Box-Behnken (B-B) method in response surface analysis. RESULTS : The influencing factors of experimental are water ratio, Chemical admixture ratio and Curing temperature. In the results of response surface analysis, to obtain goal performance, the optimized mixing design for Carbon-Capturing and Sequestering Activated Blast- Furnace Slag Mortar were water ratio 40%, Chemical admixture ratio 58.78% and Curing temperature of 60℃. CONCLUSIONS: Compared with previous studies of this experiment is to some extent the optimal combination is expected to be reliable.
        4,000원
        155.
        2013.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Activated carbon (AC) was synthesized from rice husks using the chemical activation method with KOH, NaOH, a combination of (NaOH + Na2CO3), and a combination of (KOH + K2CO3) as the chemical activating reagents. The activated carbon with the highest surface area (around 2000m2/g) and high porosity, which allows the absorption of a large number of ions, was applied as electrode material in electric double layer capacitors (EDLCs). The AC for EDLC electrodes is required to have a high surface area and an optimal pore size distribution; these are important to attain high specific capacitance of the EDLC electrodes. The electrodes were fabricated by compounding the rice husk activated carbons with super-P and mixed with polyvinylidene difluoride (PVDF) at a weight ratio of 83:10:7. AC electrodes and nickel foams were assembled with potassium hydroxide (KOH) solution as the electrolyte. Electrochemical measurements were carried out with a three electrode cell using 6 M KOH as electrolyte and Hg/HgO as the reference electrode. The specific capacitance strongly depends on the pore structure; the highest specific capacitance was 179 F/g, obtained for the AC with the highest specific surface area. Additionally, different activation times, levels of heating, and chemical reagents were used to compare and determine the optimal parameters for obtaining high surface area of the activated carbon.
        4,000원
        156.
        2013.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        황화수소 등 유황계 악취물질은 매우 낮은 최소감지농도를 갖고 있기 때문에 악취를 제거하기 위해서는 출구에서 악취가 검출되지 않는 적정 부하량에 대해 검토가 이루어져야 한다. 본 연구에서는 활성탄을 가공하여 제작한 습윤 상태의 활성탄소섬유를 이용하여 현장조건과 유사하게 황화합물악취 H2S 10 ppm, MT 3 ppm, DMS 1.5 ppm 3성분의 혼합가스에 대해 약 130일 동안 제거실험을 수행하였다. 그 결과, H2S는 유입부하량을 0.78 g-H2S / kg ACF·d 이하로 설정하여 운전하는 것이 필요하며, MT는 불완전산화 부산물인 DMDS가 출구에서 검출되어 악취를 유발하므로 안정적인 운전을 위해서는 유입부하량을 0.27 g-MT / kg ACF·d 이하로 설정하여 운전하는 것이 필요한 것으로 나타났다. DMS는 유입부하량의 변화에 관계없이 거의 제거되지 않는 것으로 나타났다.
        4,000원
        157.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we present a more electrochemically enhanced electrode using activated carbon (AC)-sulfur (S) composite materials, which have high current density. The morphological and micro-structure properties were investigated by transmission electron microscopy. Quantity of sulfur was measured by thermogravimetric analysis analysis. The electrochemical behaviors were investigated by cyclic voltammetry. As a trapping carbon structure, AC could provide a porous structure for containing sulfur. We were able to confirm that the AC-S composite electrode had superior electrochemical activity.
        4,000원
        158.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Coconut shell 계 상용 활성탄을 후처리하여 EDLC 전극재로 적용하였다. Coconut shell계 활성탄을 별도의 처리없이 EDLC 전극재로 사용하였을 때, 초기 무게용량 및 부피용량은 66 F/g 및 39 F/cc이었고, 100 사이클 충 방전을 반복한 후, 각각 54 F/g 및 32 F/cc로 감소하여 82%의 충 방전효율을 나타내었다. 충 방전 반복에 따른 용량의 감소폭이 크며, CV 특성에서 부반응에 의한 분극현상이 발생하여 전극재로 적합하지 않았다. 상업용 활성탄에 포함된 불순물을 효율적으로 제거하기 위하여 알칼리 및 산 처리를 하였고, 그 후 세공 분포와 표면의 산성 관능기 함량을 제어하기 위하여 질소 분위기에서 열처리하였다. 알칼리 및 질산처리 한 후 800℃에서 열처리한 전극재의 경우, 초기부피용량 44 F/cc, 100사이클 후 42 F/cc로서 실용화 가능한 수준의 높은 부피용량 및 95% 이상의 높은 충 방전 효율을 나타내었다.
        4,000원
        159.
        2013.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : To investigate the fundamental characteristics of blast-furnace slag mortar that was hardened with activating chemicals to capture and sequester carbon dioxide. METHODS : Various mix proportions were considered to find an appropriate stregnth development in regards with various dosages of activating chemicals, calcium hydroxides and sodium silicates, and curing conditions, air-dried, wet and underwater conditions. Flow characteristics was investigated and setting time of the mortar was measured. At different ages of 3, 7 and 28days, strength development was investigated for all the mix variables. At each age, samples were analyzed with XRD. RESULTS : The measured flow values showed the mortar lost its flowability as the activating chemicals amount increased in the scale of mole concentration. The setting time of the mortar was relatively shorter than OPC mortar but the initial curing condition was important, such as temperature. The amount of activating chemicals was found not to be critical in the sense of setting time. The strength increased with the increased amount of chemicals. The XRD analysis results showed that portlandite peaks reduced and clacite increased as the age increased. This may mean the Ca(OH)2 keeps absorbing CO2 in the air during curing period. CONCLUSIONS : The carbon capturing and sequestering activated blast-furnace slag mortar showed successful strength gain to be used for road system materials and its carbon absorbing property was verified though XRD analysis.
        4,000원
        160.
        2013.02 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to get basic data for the application of coagulants for treating an industrial wastewater containing NBD COD. The NBD COD concentration of the target wastewater was calculated to be 61 mg/L, which was about 72% of the first stage treated water, and this shows that there must be advanced wastewater treatment process. When Alum(8%) was injected in raw the water, 150ppm was the best dosage and 41% CODmn removal efficiency was obtained. When Alum(8%) was injected in the discharge water, 150ppm was the best dosage, and 19% CODmn removal efficiency was obtained. When powdered activated carbon was injected, 40ppm was the best dosage, 26% CODmn removal efficiency was obtained. The method of injecting Alum(8%) in the discharge water was suitable, when the effluent exceeds the water quality standard by 20%, and the method of injecting the powdered activated carbon was suitable, when the effluent exceeds the water quality standard by 20~40%.
        4,000원