• Membrane and Water Treatment
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• v.7 no.6
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• pp.521-537
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• 2016

Laboratory-scale experiments were carried out to investigate the adsorption equilibrium, the adsorption kinetics and facilitated transport of two cationic dyes (Methylene Blue (MB) and Rhodamine B (RB)) on Polymer Inclusion Membrane (D2EHPA-PIM). Different adsorption isotherms (Freundlich, Langmuir and Temkin models) as well as kinetics models indicated that the adsorption process is spontaneous and exothermic. Under the optimal conditions, the adsorption removal efficiencies reach about 93% and 97% for MB and RB respectively. Different extraction values by D2EHPA-PIM were obtained for the two cationic dyes: MB is weakly extracted at pH 2.0 (E% = 18.7%) whilst E% = 82.4% was observed for RB at the same pH. This difference was exploited in a mixture containg both the 2 cationic dyes for the selective extraction of RB at pH 2. Desorption of both dyes was achieved from the membrane by using acidic aqueous solutions and desorption ratio up to 90% was obtained. The formulas of the extracted complexes by the PIMs were, determined by the method of slopes. The dyes transport was elucidated using mass transfer analysis where in it found relatively high values of the initial flux ($J_0$) as 41.57 and $18.74{\mu}mol.m^2.s^{-1}$ for MB and RB respectively.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.88-95
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• 2013

This study attempts to capture the low level carbon dioxide from indoor spaces using a granular activated carbon (WSC-470) which was modified with primary monoethanolamine. Adsorption capacity of the prepared adsorbents was evaluated for pure $CO_2$ flow and 3000 ppm as a function of MEA concentration and solvents such as distilled water, ethanol and methanol. The AC based adsorbents then were characterized in terms of pore structure by BET and chemical functionalities by XPS. While high concentration of MEA reduced specific surface area, porosity and micro pores, nitrogen content which can enhance the surface basicity was increased. The maximum adsorption capacity decreased comparing to the initial AC pellets, whilst the potential of selective adsorption amount at low level $CO_2$ was increased at 45% (0.73 mmol/g).

• Journal of the Korean Ceramic Society
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• v.55 no.3
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• pp.261-266
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• 2018

Hollow or bumpy ZnO structures with micrometer-size features have been investigated as photocatalysts for water purification due to their high surface area available for reaction with harmful organic molecules and relatively large size for easy separation after finishing the photocatalytic reaction. In this study, selective synthesis of ZnO hollow or crumpled microspheres was performed using a simple and versatile ultrasonic spray pyrolysis process with various zinc precursors. The morphologies, phases, specific surface areas, and optical properties of the microspheres were characterized using X-ray diffraction, scanning electronic microscopy, nitrogen adsorption-desorption isotherms, and UV-vis spectroscopy. In addition, the mechanism underlying the formation of different morphologies and their photocatalytic activities were systematically investigated.

• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.1-8
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• 2001

선택적 가스분리를 위한 분자체탄소(Molecular Sieve Carbon: MSC)로서의 활용을 위해 제조된 활성탄소섬유의 흡착능과 분자체 특성이 다양한 분자크기를 갖는 가스 흡착실험을 통해 조사되었다. 각 활성화 조건별 세공크기분포와 세공발달 전개과정을 유추함으로서, 세공크기분포의 조절이 가능하게 되었으며 활성탄소섬유의 분자체 탄소로서 활용을 용이하게 할 수 있었다. 800, 85$0^{\circ}C$의 온도로 수증기에 의해 활성화한 활성탄소섬유의 경우 burn-off가 각각 50, 40% 정도를 가진 활성탄소섬유가 비교적 작은 분자크기(0.3~0.4nm)의 흡착질에 대한 분자체 특성을 나타냈다. 또한, 다양한 분자크기의 흡착질을 포함하는 혼합가스의 유속과 흡착온도의 조절로서 원하는 흡착질의 선택적 분리를 위해 활성탄소섬유가 갖는 분자체 특성 향상을 보였다.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.416-422
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• 1993

In order to prepare high performance polymeric membrane, the crosslinked chitosan(C. Chitosan)membrane was prepared, the transport and the selective separation of the metal ions through the membrane were investigated. It was observed that the transport rates of the metal ions through the membrane increased according to the decreasing of the initial pH in downstream solution. Proton pump mechanism for this transport phenomenon was suggested. The transport selectivity is dependent on the selective adsorption resulting from the complex formation of chitosan with each metal ion. The separatin factor(${\alpha}_{Cu}{^{2+}}$) for the membrane was 9.5.

• Analytical Science and Technology
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• v.8 no.4
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• pp.529-534
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• 1995

The metal ion selective resins were prepared by surface template polymerization using monooleyl phosphoric acid (1), oleyl methyl phosphoric acid (2) or oleyl ethyl phosphoric acid (3) as an amphiphilic host surfactant. The $Cu^{2+}$-imprinted resins prepared in the presence of $Cu^{2+}$ adsorbed $Cu^{2+}$ much more effectively than did their reference resins. On the other hand, the $Cu^{2+}$-imprinted resins showed much less binding ability to $Zn^{2+}$. The template-dependent selectivity should be ascribed to a favorable placement of the surface-anchored metallophilic groups for multidentate coordination to specific metal ion.

• Polymer(Korea)
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• v.33 no.1
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• pp.72-78
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• 2009

In this study, the behaviour of $SO_2$ and $NO_2$ adsorption on aminated ultrafine fibrous PP-g-AAc ion exchanger was investigated, The amount of adsorbed $SO_2$ increased with increasing the initial concentration of $SO_2$. The adsorption breakthrough time in the low concentration of $SO_2$ was faster than high concentration. The adsorption breakthrough occurred within 60 min. Approximately 80% of $SO_2$ was adsorbed below 100 ppm $SO_2$ and 90% of $SO_2$ over 100 ppm $SO_2$ respectively. The selective adsorption rate for $NO_2$ was lower than that of $SO_2$. The adsorption rate for $SO_2$ was decreased with increasing flow rate and that of $NO_2$ was 60%. The breakthrough occurred within 60 min. The adsorption rate for $SO_2$ was 92% in the 250 mL/g water content. Isotherm adsorption model for $SO_2$ was close to the Langmuir rather than Freundlich model.

• Journal of Environmental Science International
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• v.18 no.6
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• pp.645-654
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• 2009

Lab-scale Electrodialysis(ED) system with different membranes combined with before or after pyroma process were carried out to remove nitrate from two pickling acid wastewater containing high concentrations of $NO_3\;^-$(${\approx}$150,000 mg/L) and F($({\approx}$ 160,000 mg/L) and some heavy metals(Fe, Ti, and Cr). The ED system before Pyroma process(Sample A) was not successful in $NO_3\;^-$ removal due to cation membrane fouling by the heavy metals, whereas, in the ED system after Pyroma process(Sample B), about 98% of nitrate was removed because of relatively low $NO_3\;^-$ concentration (about 30,000 mg/L) and no heavy metals. Mono-selective membranes(CIMS/ACS) in ED system have no selectivity for nitrate compared to divalent-selective membranes(CMX/AMX). The operation time for nitrate removal time decreased with increasing the applied voltage from 10V to 15V with no difference in the nitrate removal rate between both voltages. Nitrate adsorption of a strong-base anion exchange resin of $Cl\;^-$ type was also conducted. The Freundlich model($R^2$ > 0.996) was fitted better than Langmuir mode($R^2$ > 0.984) to the adsorption data. The maximum adsorption capacity ($Q^0$) was 492 mg/g for Sample A and 111 mg/g for Sample B due to the difference in initial nitrate concentrations between the two wastewater samples. In the regeneration of ion exchange resins, the nitrate removal rate in the pickling acid wastewater decreased as the adsorption step was repeated because certain amount of adsorbed $NO_3\;^-$ remained in the resins in spite of several desorption steps for regeneration. In conclusion, the optimum system configuration to treat pickling acid wastewater from stainless-steel industry is the multi-processes of the Pyroma-Electrodialysis-Ion exchange.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.337-343
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• 2007

The reforming catalyst and the electrodes in fuel cells can be poisoned by the organic sulfur compound which is added as an odorant for checking out the leakage of natural gas, and that makes a big problem of system degradation. In this study, various adsorbents, such as silica, ${\gamma}$-alumina, activated carbon, HZSM-5, Ultra-stable Y zeolite (USY), and beta zeolite (BEA), were utilized to remove tetra-hydrothiophene (THT) and tert-butylmercaptan (TBM), and to confirm the performance in the adsorption of those odorants by using a continuous adsorptive bed. The effects of Si/Al ratio of zeolites, adsorption temperature and the type of balance gas (methane or He) on the adsorption performance in the packed bed have been investigated. In addition, the competitive adsorption between TBM and THT on the adsorbents was also estimated. The result shows that H-type BEA zeolite exhibited the highest adsorption capacity for TBM and THT odorant, and the higher amount of THT was removed adsorptively on the same adsorbent than TBM. The physical and chemical adsorption of those compounds on acid sites of zeolite were confirmed by temperature programmed desorption (TPD) and infrared spectrum (IR) analyses.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.512-518
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• 2008

The present work studied the selective catalytic reduction (SCR) of NO to $N_2$ by $NH_3$ over $V/TiO_2$ focusing on NOx control for the stationary sources. The SCR process depends mainly on the catalyst performance. The reaction characteristics of SCR with $V/TiO_2$ catalysts were closely examined at low and high temperature. In addition, adsorption and desorption characteristics of the reactants on the catalyst surface were investigated with ammonia. Seven different $TiO_2$ supports containing the same loading of vanadia were packed in a fixed bed reactor respectively. The interaction between $TiO_2$ and vanadia would form various non-stoichiometric vanadium oxides, and showed different reaction activities. There were optimum calcination temperatures for each samples, indicating different reactivity. It was finally found from the $NH_3-TPD$ test that the SCR activity was nothing to do with $NH_3$ adsorption amount.