• Clean Technology
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• v.29 no.3
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• pp.217-226
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• 2023

The amount of hydrogen adsorbed in arrays of single walled carbon nanotubes (SWNTs) was studied as a function of nanotube diameter and distance between the nearest-neighbor nanotubes on square arrangements using a grand canonical Monte Carlo simulation. The influence of the geometry of a triangle array with the same diameters and distances was also studied. Hydrogen-carbon and hydrogen-hydrogen interactions were modeled with Lennard-Jones potentials for short range interactions and electrostatic interactions were added for hydrogen-hydrogen pairs to consider quantum contributions at low temperatures. At 194.5 K, Type I isotherms for large-diameter SWNTs and Type IV isotherms without hysteresis between adsorption and desorption processes for wider tube separations were observed. At 200 bars, the gravimetric hydrogen storage capacity of the SWNTs was reached or exceeded the US Department of Energy (DOE) target, but the volumetric capacity was about 70% of the DOE target. At 77 K, a two-step adsorption was observed, corresponding to a monolayer formation step followed by a condensation step. Hydrogen was adsorbed first to the inner surface of the nanotubes, then to the outer surface, intratubular space and the interstitial channels between the nanotube bundles. The simulation indicated that SWNTs of various diameters and distances in a wide range of configurations exceeded the DOE gravimetric and volumetric targets at under 1 bar.

• Membrane Journal
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• v.28 no.4
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• pp.221-232
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• 2018

The silica containing carbon ($C-SiO_2$) membranes were fabricated using poly(imide siloxane)(Si-PI) and polyvinylpyrrolidone (PVP) blended polymer. The characteristics of porous carbon structures prepared by the pyrolysis of polymer blends were related with the micro-phase separation behaviors of the two polymers. The glass transition temperatures ($T_g$) of the mixed polymer blends of Si-PI and PVP were observed with a single $T_g$ using differential scanning calorimetry. Furthermore, the nitrogen adsorption isotherms of the $C-SiO_2$ membranes were investigated to define the characteristics of porous carbon structures. The $C-SiO_2$ membranes derived from Si-PI/PVP showed the type IV isotherm and possessed the hysteresis loop, which was associated with the mesoporous carbon structures. For the molecular sieving probe, the $C-SiO_2$ membranes were prepared with the ratio of Si-PI/PVP and the pyrolysis conditions, such as the pyrolysis temperature and the isothermal times. Consequently, the $C-SiO_2$ membranes prepared by the pyrolysis of Si-PI/PVP at $550^{\circ}C$ with the isothermal time of 120 min showed the $O_2$ permeability of 820 Barrer ($1{\times}10^{-10}cm^3(STP)cm/cm^2{\cdot}s{\cdot}cmHg$) and $O_2/N_2$ selectivity of 14.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.691-698
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• 2016

This study was carried out to investigate the characterization of iron oxide nanotubes (INTs) by anodization method and applied adsorption isotherms and kinetic models for phosphate adsorption. SEM analysis was conducted to examine the INTs surface formation. Further XRD and XPS analysis were performed to observe the crystal structure of INTs before and after phosphate adsorption. AFM analysis was conducted to determine of Fe foil surface before and after anodization. Phosphate stock solution for adsorption experiment was prepared by $KH_2PO_4$. The batch experiment was conducted using 20 ml phosphate stock solution and $40cm^3$ of INTs in 50 ml conical tube. Adsorption isotherms were applied Langmuir and Freundlich models for adsorption equilibrium test of INTs. Pseudo first order and pseudo second order models were applied for interpretation of adsorption rate by reaction time. The determination coefficient ($R^2$) values of Langmuir and Freundlich models were 0.9157 and 0.8876 respectively.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.371-379
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• 2005

Adsorption equilibria of the gases $H_2$, $CH_4$, and $C_2H_4$ and their binary mixtures on activated carbon (Calgon co.) have been measured by static volumetric method in the pressure range of 0 to 18 atm at temperatures of 293.15, 303.15, and 313.15 K. From the parameters obtained from single component adsorption isotherm, multi-component adsorption equilibria could be predicted and compared with experimental data. The binary experimental data were applied to four models : extended Langmuir, extended Langmuir-Freundlich, Ideal Adsorbed Solution theory (IAST), and Vacancy Solution Model (VSM). The models were found to describe the experimental data with a reasonable accuracy. Extended L-F model predicts equilibria of mixture better than any other model.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.386-389
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• 2008

본 연구에서는 쌀겨를 이용하여 메조포러스 실리카를 제조하였다. 제조된 메조포러스 실리카는 X-선 회절 패턴, TEM, FT-IR, 질소흡착등온선 측정을 통하여 SBA-15 특성과 동일하게 나타났으며, 결과적으로 메조포러스 실리카 물성에 가장 큰 영향을 나타내는 것은 반응온도, 시간이며, 쌀겨회재의 규소 용출은 소성온도가 낮을수록 증가하며 규소원에 따라 각기 다른 특성을 나타냄을 합성된 메조포러스 실리카의 물리화학적 특성으로부터 알 수 있었다.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1016-1021
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• 1999

In this study activated carbon fibers were prepared from PAN-based carbon fibers by physical activation with steam or carbon dioxide. The variations in specific surface area amount of iodine adsorption and pore size distribution of the activated carbon fibers after the activation process were discussed. in steam activation BET surface area of about 1019 m2/g was obtained after 77% burn-off while carbn dioxide activation produced ACF with 694m2/g of BET surface area after 52% burn-off. However carbon dioxide activation produced at a similar degree of activation higher micropore volume(0.37 cc/g) and amount of iodine adsorption (1589mg/g) than steam activation. Nitrogen adsorption isotherms for (PAN based activated carbon fibers that prepared by physical activation were of type I in the Brunauer-Deming-Deming-Teller classification

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.614-619
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• 2005

The activated carbon fibers of different surface area and pore structures were modified by carbon deposition from the pyrolysis of benzene, in an attempt to obtain carbon molecular sieves of high adsorption capacity and selectivity for the separation of $CO_2/CH_4$ gas mixtures. The ACFs molecular sieves prepared from different temperature and time were tested by the static adsorption of $CO_2$ and $CH_4$ gas, and their pore structures were characterized by the $N_2$ adsorption isotherms. We are able to prepare ACF molecular sieve with good selectivity for $CO_2/CH_4$ separation and showing acceptable adsorption capacities from the change of porosity by carbon deposition of pyrolyzed benzene.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1029-1038
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• 2008

Transition-metal-oxide-incorporated hydrotalcites were prepared by hydrothermal reaction of their synthetic mixtures containing precursors of transition metal oxides and their properties of nitrogen dioxide adsorption was investigated. The dispersion of transition metal oxides on the hydrotalcites and the amount and the state of nitrogen dioxide adsorbed on them were examined by using XRD, SEM, XPS, nitrogen adsorption, a gravimetric adsorption system, FT-IR spectroscopy and temperature programmed desorption techniques. Transition metal oxides were mainly incorporated on their surface and the incorporation of iron and nickel oxides to the hydrotalcites increased their adsorption amounts of nitrogen dioxide. The dispersion of iron oxide on the hydrotalcites was effective in increasing the amount of nitrogen dioxide adsorption, while too much amount of iron oxide incorporation reduced the amount of nitrogen dioxide adsorption due to masking of surface basic sites by agglomerated iron oxide. Although the incorporation of iron oxide to the hydrotalcites lowered the adsorption strength of nitrogen dioxide, the incorporation of it with a proper amount enhanced the amount of nitrogen dioxide adsorption and the stability against the hydrothermal treatment.

• Analytical Science and Technology
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• v.13 no.1
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• pp.89-95
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• 2000

Three grades of activated carbon fibers (ACFs) were prepared from various precursors of plantic, synthetic, and mixed fabrics of viscose rayon and cotton. The ACFs an exhibited type I isotherms on the adsorption of nitrogen or argon. Micropore analysis revealed that the ACFs have uniform micropore size distribution in which their peak diameters were in the range of $5.6{\pm}0.3{\AA}$. The BET surface area of ACFs up to $1600m^2g^{-1}$ was proportional to the adsorption capacity of iodine. The BET values of the ACFs prepared were proportional to the burn-off degree of the products.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.231-234
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• 2001

We performed a basic experiment for rapid. on-line, real-time measurement of HBsAg by using a BIACORE biosensor, a chip-based sensor utilizing surface plasmon resonance technology to quantify the recognition and interaction of biomolecules. We immobilized an a -HBsAg antibody on a CM5 chip surface which was activated by N-hydroxysuccinimide for amine coupling with HBsAg, and measured the mass increase from the coupling. This study showed the potential of this biosensor-based method as a rapid, multi-sample, on-line assay. Once properly validated, it can serve as a more powerful method for HBsAg quantification.