• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.144-149
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• 1999

The two distinct adsorption sites and transition between the under and over-potentially deposited hydrogen (UPD H and OPD H) on the polycrystalline iridium (poly-Ir) surface in the 0.2 M LiOH electrolyte have been studied using the phase-shift method. At the forward and backward scans, the UPD H peak occurs on the cyclic voltam-mogram. The transition region on the phase-shift profile or the Langmuir adsorption isotherm occurs at ca. -0.80 to -0.95 V vs. SCE. At the transition region (-0.80 to -0.95 V vs. SCE), the equilibrium constant (K) for H adsorption transits from $7.9\times10^{-2}\;to\;1.5\times10^{-4}$ and vice versa. Similarly, the standard free energy $({\Delta}G_{ads})$ of H adsorption transits from 6.3 to 21.8kJ/mol and vice versa. The UPD H and OPD H on the poly-Ir surface act as two distinguishable electroadsorbed H species. Both the UPD H peak and the transition region are attributed to the two distinct adsorption sites of the UPD H and OPD H on the poly-Ir surface.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1192-1197
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• 2006

Adsorbability of ionic and nonionic pharmaceuticals was studied using granular activated carbon(GAC). In a batch adsorption test of muticomponent solution, 500 mg/L of GAC dose removed all target compounds between 94 and 98% at initial concentration of 10 ${\mu}g/L$. Adsorption of ionic pharmaceuticals increased as pH was lowered toward to pKa, however adsorption capacity of nonionic pharmaceuticals showed insignificant variation with the changing pH. The enhanced adsorption capacity of ionic pharmaceuticals at lower pH was attributed to the corresponding increase in the molecular form of ionic pharmaceuticals with carboxylic group at low pH. In addition, decrease of pH increased hydrogen ion concentration in the bulk solution and the protons bound to the available sites on the carbon enhanced the removal of the ionic pharmaceuticals from solution. After 40 days of continuous operation, GAC column showed the removal of target compounds were removed by $93{\sim}99%$ at 15 min of EBCT mainly due to adsorption mechanism of GAC. At shorter EBCT than 15 min, breakthrough of CA, IBP and GFZ occurred earlier than the other ionic and nonionic pharmaceuticals. effect of EBCT on adsorption of nonionic pharmaceuticals was greater than ionic ones. This study showed that persitent pharmaceuticals found in drinking water treatment could be effectively controlled by adsorption in GAC process.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.160-166
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• 2019

In this study, oxygen functional groups were introduced on activated carbon fibers (ACFs) by oxygen plasma treatment to improve the adsorption performance on an acetic acid which is a sick house syndrome induced gas. The active species was generated more as the flow rate of the oxygen gas increased during the plasma treatment. For this reason, the specific surface area (SSA) of the ACFs decreased with much more physical and chemical etching. In particular, the SSA of the sample (A-O60) injected with an oxygen gas flow rate of 60 sccm was reduced to about $1.198m^2/g$, which was about 6.95% lower than that of the untreated samples. On the other hand, the oxygen content introduced into the surface of ACFs increased up to 35.87%. Also, the adsorption performance on the acetic acid gas of the oxygen plasma-treated ACFs was improved by up to 43% compared to that of using the untreated ACFs. It is attributed to the formation of the hydrogen bonding due to the dipole moments between acetic acid molecules and oxygen functional groups such as O=C-O introduced by the oxygen plasma treatment.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1814-1822
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• 2013

By using density functional theory calculations, we have performed a systemic study on the electronic structures and topological properties of interactions between N-butylpyridinium nitrate ($[BPY]^+[NO_3]^-$) and thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), naphthalene (NAP). The most stable structure of $[BPY]^+[NO_3]^-$ ion pair indicates that hydrogen bonding interactions between oxygen atoms on $[NO_3]^-$ anion and C2-H2 on pyridinium ring play a dominating role in the formation of ion pair. The occurrence of hydrogen bonding, ${\pi}{\cdots}$H-C, and ${\pi}{\cdots}{\pi}$ interactions between $[BPY]^+[NO_3]^-$ and TS, BT, DBT, NAP has been corroborated at the molecular level. But hydrogen bonding and ${\pi}{\cdots}{\pi}$ interactions between $[BPY]^+[NO_3]^-$ and NAP are weak in terms of structural properties and NBO, AIM analyses. DBT is prior to adsorption on N-butylpyridinium nitrate ionic liquid.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.57-63
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• 2011

Polymer electrolyte membrane fuel cell (PEMFC) performance degrades when hydrogen sulfide ($H_2S$) is present in the fuel hydrogen gas; this is referred to as $H_2S$ poisoning. This paper reveals $H_2S$ poisoning on PEMFC by measuring electrical performance of single cell FC under various operating conditions. The severity of $H_2S$ poisoning depended on $H_2S$ concentration under best operating conditions($65^{\circ}C$ of cell temperature and 100% of anode humidification). $H_2S$ adsorption occured on the surface of catalyst layer on MEA, but not on the gas diffusion layer(GDL) by analyzing SEM/EDX data. In addition, MEA poisoning by $H_2S$ was cumulative but reversible. After poisoning for less than 150 min, performance of PEMFC was recovered up to 80% by just inert nitrogen gas purging.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.2
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• pp.69-75
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• 1999

The characteristics of $H_2$ gas detection have been investigated using the Pt-MIS capacitor composed of the LPCVD nitride on the oxide. The flat band voltage shift is measured as 0.1 V in 1,000 ppm $H_2$ gas ambient and to be independent of Pt catalyst thickness. It is found that the flatband voltage shift is proportional to the hydrogen concentrations. The response and recovery time of Pt-MIS capacitor are 5 mins and 25 mins respectively. The samples of 30nm thick Pt revealed much higher sensitivity than that of 150nm samples. The samples of 150nm Pt showed that the flatband voltage shift of the device is due to the formation of the dipole layer of the adsorbed hydrogen atoms at the Pt-insulator interface.

• Polymer(Korea)
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• v.37 no.3
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• pp.288-293
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• 2013

A group of molecularly imprinted polymers (MIPs) with specific recognition for chiral (S)-ibuprofen were successfully prepared based on hydrogen bonds, utilizing ${\alpha}$-methacrylic acid as a functional monomer. The IR analysis of MIPs showed that the blue- and red-shifted hydrogen bonds were formed between templates and functional monomers in the process of self-assembly imprinting and re-recognition, respectively. According to UV-Vis analysis, we found that the ratio of host-guest complexes between template molecule and functional monomer was 1:1. The effect of cross-linker's quantity on the polymerization was studied by transmission electron microscope (TEM). The adsorption selectivity experiments indicated that MIPs exhibited higher selectivity to (S)-ibuprofen than those to ketoprofen and (R)-ibuprofen, (S)-ibuprofen's structural analogs.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.1
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• pp.81-95
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• 2003

본 연구는 압력균등화 공정이 추가된 2 컬럼 6 스뎁의 활성탄 PSA공정을 이용하여 비단열, 비등은 조건에서 메탄(80%)과 수소(20%)의 2성분계로부터 수소분리에 관한 연구이다. 공급가스의 압력, 흡착시간, 공급속도와 P/F 비율이 PSA공정에 미치는 영향에 대하여 평가했고 전산모사를 통해 최적조건을 구했다. 전산모사에 의한 최적 조건은 공급속도 17 LPM, 흡착압력 11 atm, P/F 비율이 0.07~0.1로 나타났으며, 이 조건으로부터 순도 99%, 회수율 85% 이상의 수소가스를 얻을 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.2
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• pp.164-170
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• 2007

The Tancheon wastewater treatment plant(WWTP) in Seoul using anaerobic digestion to reduce the outlet sludge produces anaerobic digester gas which contains 65% $CH_4$ and 35% $CO_2$. The gas purification equipment was installed and operated to use Anaerobic Digester Gas(ADG) as a fuel for molten carbonate fuel cell(MCFC). The processes consist of the desulfurizer and the adsorption tower to remove $H_2S$ and siloxane in the gas. The gas purification equipment removed virtually over 95% of $H_2S$ and over 99% of siloxane. Results has demonstrated that the fuel cell can produce electrical output and hot water with negligible air emissions of CO, NOx and $SO_2$. The site provides the first opportunity in Korea for demonstrating Molten carbonate fuel cell(MCFC) which the digester gas was applied to the fuel gas.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.135-143
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• 2016

Biogas is a renewable fuel from anaerobic digestion of organic matters such as sewage sludge, manure and food waste. Raw biogas consists mainly of methane, carbon dioxide, hydrogen sulfide, and water. Biogas may also contain other impurities such as siloxanes, halogenated hydrocarbons, aromatic hydrocarbons. Efficient power technologies such as fuel cell demand ultra-low concentration of containments in the biogas feed, imposing stringent requirements on fuel purification technology. Biogas is upgraded from pressure swing adsorption after biogas purification process which consists of water, $H_2S$ and siloxane removal. A polymer electrolyte membrane fuel cell power plant is designed to operate on reformate produced from upgraded biogas by steam reformer.