• 공업화학
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• 제19권1호
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• pp.31-36
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• 2008

혐기성소화가스(ADG)를 원료로 수소를 제조하여 연료전지에 활용할 경우 ADG에 포함된 황화합물이 개질기의 촉매와 연료전지의 전극에 독으로 작용하므로 금속이온이 담지된 활성탄을 이용하여 황화합물을 제거하였다. 수분과 산소농도에 따라 고정층 흡착량이 변화하였으며, 산소 0.2 vol%, RH 90% 이상일 때 가장 높은 흡착량을 나타내었다. 본 연구에서는 KI 첨착한 활성탄에서 황화합물의 흡착특성을 고정층에서 동특성 실험을 통해 관찰하고 그 결과를 기준으로 흡착탑을 설계 제작 현장실험을 실시하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권3호
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• pp.58-64
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• 2013

This study proposed a low temperature hydrothermal carbonization to treat and recycle sewage sludge and determined the optimal conditions for the biochar production. The physical and chemical properties of biochar were analyzed and its sorption capacity for heavy metals was evaluated. To produce biochar, 50 g of sewage sludge was heated at 220, 230, and $240^{\circ}C$ for 1, 2, 3, 5, 8, and 10 hours in a reactor. The optimal conditions to produce biochar was $230^{\circ}C$ and 8 hours. Sorption capacity tests were conducted for arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn) and nickel (Ni). Among them, lead was shown the highest heavy metal adsorption efficiency of biochar, followed by copper, cadmium, zinc, and nickel, but arsenic was hardly adsorbed overall.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.966-978
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• 1993

A power operated 90.5 hp electric motor) grain flour separator was designed and developed for separation of grain (wheat, corn, chickpea and soybean) flour into various fractions based on the size of the particles of the product. The separator agitating mechanism, feed control, cylindrical separator unit and an eccentric mechanism. The machine was tested for wheat ( variety ; Sujata) flour separation into four fractions, viz ; semolina, Gr-I and II, flour (coarse) and white (fine) flour. Wheat samples (6.8% m.c., db) were first pearled by CIAE pearler for 15.8% bran removal . The pearled wheat grains were then milled for semolina by a burre mill. The product and machine characteristics were determined at different capacities varying from 24 kg/h to 143 kg/h. It was found that 76 kg/h capacity gave reasonably best results in terms of purity and recovery of semolina vis-a-vis the market product. The energy requirement of the machine at no-load was found to be 230 W and at load c nditions, it varied between 36.3-6.4 KJ per kg of fead seperation. The macine could be used by small flour millers small/medium size traders and retailers and other processors for making available various flour products of different particle size in the market for ready use of the consumers.

• Structural Engineering and Mechanics
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• 제61권6호
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• pp.755-763
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• 2017

In this study, the susceptibility of different symmetric steel buildings with dual frame system to Progressive Collapse (PC) was assessed. Some ten-story dual frame systems with different type of braced frames (concentrically and eccentrically braced frames) were considered. In addition, numbers and locations of braced bays were investigated (two and three braced bays in exterior frames) to quantitatively find out its effect on PC resistance. An Alternate Path Method (APM) with a linear static analysis was carried out based on General Services Administration (GSA 2003) guidelines. Maximum Demand Capacity Ratio (DCR) for the elements (beams and columns) with highest DCRs ($DCR_{moment}$ and $DCR_{shear}$) is given in tables. The results showed that the three braced bays with concentric braced frames especially X-braced and inverted V-braced frame systems had a lower susceptibility and greater resistance to PC. Also, the results represented that the beams were more critical than columns against PC after the removal of column.

• 한국환경과학회지
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• 제29권8호
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• pp.827-835
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• 2020

Zeolite material having XRD peaks of Na-A zeolite in the 2θ range of 7.18 to 34.18 can be synthesized from the waste catalyst using a fusion/hydrothermal method. The adsorption rate of Mn ions by a commercial Na-A zeolite and the synthesized zeolitic material increased as the adsorption temperature increased in the range of 10 ~ 40℃. The adsorption of Mn ion were very rapid in the first 30 min and then reached to the equilibrium state after approximately 60 min. The adsorption kinetics of Mn ions by the commercial Na-A zeolite and the zeolitic material were found to be well fitted to the pseudo-2^nd order kinetic model. Equilibrium data by the commercial Na-A zeolite and the zeolitic material fit the Langmuir, Koble-Corrigan, and Redlich-Peterson isotherm models well rather than Freundlich isotherm model. The removal capacity of the Mn ions by the commercial Na-A zeolite and the zeolitic material obtained from the Langmuir model was 135.2 mg/g and 128.9 mg/g at 30℃, respectively. The adsorption capacity of Mn ions by the synthesized zeolitic material was almost similar to that of commercial Na-A zeolite. The synthesized zeolitic material could be applied as an economically feasible commercial adsorbent.

• Carbon letters
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• 제2권1호
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• pp.15-21
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• 2001

In this work, activated carbon fibers (ACFs) were plated with copper metal using electroless plating method and the effects of surface properties and pore structures on chromium adsorption properties were investigated. Surface properties of ACFs have been characterized using pH and acid/base values. BET data with $N_2$ adsorption were used to obtain the structural parameters of ACFs. The electroless copper plating did significantly lead to a decrease in the surface acidity or to an increase in the surface basicity of ACFs. However, all of the samples possessed a well-developed micropore. The adsorption capacity of Cr(III) for the electroless Cu-plated ACFs was higher than that of the as-received, whereas the adsorption capacity of Cr(VI) for the former was lower than that of the latter. The adsorption rate constants ($K_1$, $K_2$, and $K_3$) were also evaluated from chromium adsorption isotherms. It was found that $K_1$ constant for Cr(III) adsorption depended largely on surface basicity. The increase of Cr(III) adsorption and the decrease of Cr(VI) adsorption were attributed to the formation of metal oxides on ACFs, resulting in increasing the surface basicity.

• 공업화학
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• 제8권4호
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• pp.631-636
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• 1997

흡착제로 널리 쓰이는 다공성탄소의 흡착성능을 증가시키는 연구를 수행하였다. 열처리에 의하여 다공성탄소의 흡착성능을 증가시킨 후, 유해중금속의 일종인 $Cr^{+6}$의 선택적 흡착을 시행하였다. 다공성탄소의 적정 열처리 온도는 $340{\sim}350^{\circ}C$가 가장 적절하였으며, 이때의 평균 비표면적은 Brunauer-Emmett-Teller(BET) 방법에 의해 $1380m^2/g$로 측정되었다. 열처리 과정에서 전체중량의 약 10%의 감소가 있었으나, 비표면적의 증가로 고품질의 흡착제가 되었다. 또한 열처리된 다공성탄소에 의하여 액상에서의 $Cr^{+6}$의 제거가 성공적으로 수행되었다.

• Carbon letters
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• 제13권4호
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• pp.212-220
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• 2012

Orange peel (OP) exhibits a sorption capacity towards anionic dyes such as reactive blue 19 (RB19). Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant was used to modify the surface nature of OP to enhance its adsorption capacity for anionic dyes from an aqueous solution. Four adsorbents were investigated: the OP, sodium hydroxide-treated OP (SOP), CTAB-modified OP and CTAB-modified SOP. The physical and chemical properties of these sorbents were determined using nitrogen adsorption at 77 K and by scanning electron microscope and Fourier transform infrared spectroscopy techniques. The adsorption of the RB19 dye was assessed with these sorbents at different solution pH levels and temperatures. The effect of the contact time was considered to determine the order and rate constants of the adsorption process. The adsorption data were analyzed considering the Freundlich, Langmuir, Elovich and Tempkin models. The adsorption of RB19 by the assessed sorbents is of the chemisorption type following pseudo-first-order kinetics. CTAB modification brought about a significant increase in RB19 adsorption, which was ascribed to the grafting of the sorbent with a cationic surfactant.

• 한국환경과학회지
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• 제23권12호
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• pp.1987-1998
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• 2014

Zeolite was synthesized from power station waste, coal fly ash, as an alternative low-cost adsorbent and investigated for the removal of Sr(II) and Cs(I) ions from single- and binary metal aqueous solutions. In order to investigate the adsorption characteristics, the effects of various operating parameters such as initial concentration of metal ions, contact time, and pH of the solutions were studied in a batch adsorption technique. The Langmuir model better fitted the adsorption isotherm data than the Freundlich model. The pseudo second-order model was found more applicable to describe the kinetics of system. The adsorption capacities of Sr(II) and Cs(I) ions obtained from the Langmuir model were 1.7848 mmol/g and 0.7640 mmol/g, respectively. Although the adsorption capacities of individual Sr(II) and Cs(I) ions was less in the binary-system, the sum of the total adsorption capacity (2.3572 mmol/g) of both ions in the binary-system was higher than the adsorption capacity of individual ion in the single-system. Comparing the homogeneous film diffusion model with the homogeneous particle diffusion model, the adsorption was mainly controlled by the particle diffusion process.

• The Korean Journal of Physiology and Pharmacology
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• 제7권3호
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• pp.187-191
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• 2003

$Na^+/H^+$ exchanger (NHE) has a critical role in regulation of intracellular pH (pHi) in the renal proximal tubular cells. It has recently been shown that dopamine inhibits NHE in the renal proximal tubules. Nevertheless, there is a dearth of information on the effects of long-term (chronic) dopamine treatment on NHE activities. This study was performed to elucidate the pHi regulatory mechanisms during the chronic dopamine treatments in renal proximal tubular OK cells. The resting pHi was greatly decreased by chronic dopamine treatments. The initial rate and the amplitude of intracellular acidification by isosmotical $Na^+$ removal from the bath medium in chronically dopamine-treated cells were much smaller than those in control. Although it seemed to be attenuated in $Na^+$-dependent pH regulation system, $Na^+$-dependent pHi recovery by NHE after intracelluar acid loading in the dopamine-treated groups was not significantly different from the control. The result is interpreted to be due to the balance between the stimulation effects of lower pHi on the NHE activity and counterbalance by dopamine. Our data strongly suggested that chronic dopamine treatment increased intrinsic intracellular buffer capacity, since higher buffer capacity was induced by lower resting pHi and this effect could attenuate pHi changes under extracellular $Na^+$-free conditions in chronically dopamine-treated cells. Our study also demonstrated that intracellular acidification induced by chronic dopamine treatments was not mediated by changes in NHE activity.