• Journal of Energy Engineering
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• v.23 no.4
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• pp.160-168
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• 2014

In the present study, water vapor adsorption was evaluated at 298.15K for 9 different zeolites having LTA, FAU, CHA, and RHO frameworks, and then effect of framework type, Si/Al molar ratio, and alkali ion type on water up-take was investigated. Zeolites showed water up-takes which were increased in an order of $RHO<CHA{\approx}LTA<FAU$ frameworks. NaY zeolite having FAU framework showed a water up-take of 406 mg/g at p/po=0.5. The up-take was a little larger than that of 13X zeolite with the same framework. Among LTA zeolites, Ca-type 5A zeolite showed the highest water adsorption (282 mg/g at p/po=0.5) which could be explained by the large pore volume. Both CHA zeolite with a Si/Al molar ratio of 2.35 and RHO zeolite with a Si/Al molar ratio of 3.56 showed considerable water up-takes, even though the Si/Al molar ratio was much larger than that of LTA zeolite. In the present study, it is announced that in addition to FAU and LTA zeolites, CHA and RHO zeolites can be a promising dehumidification adsorbent.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.203-207
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• 2013

Zeolites with different structures were synthesized from the hydrothermal synthesis condition employing simple structure directing agent (SDA) containing piperidine moiety. The gel containing $1.0SiO_2$:0.9SDA:$0.062NaAlO_2$:0.217NaOH:$20H_2O$ was subject to hydrothermal synthesis at 413~453 K for 7 days. FER type zeolite was obtained at 433 K when piperidine was employed as SDA, whereas TON and MFI type zeolites were also obtained at 433 K when 2,6-dimethylpiperidine and 2,2,6,6-tetramethylpiperidine were used, respectively. Further increase of hydrothermal synthesis temperature to 453 K resulted in the formation of TON type zeolite when 2-mtheylpiperidine was used. The structural analysis of powder X ray diffraction pattern over FER type zeolite suggested that the SDA, piperidine interacted intimately with the zeolite where it located close to the framework.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.330-335
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• 2008

Water vapor adsorption kinetics of 3 different types of chitosan-based films, i.e., control chitosan, chitosan/montmorillionite (Na-MMT), and chitosan/silver-zeolite (Ag-Ion) nanocomposite films, were investigated at temperature range of $10-40^{\circ}C$. In all the films, water vapor is initially adsorbed rapidly and then it comes slowly to reach equilibrium condition. Reasonably good straight lines were obtained with plotting of 1/($m-m_0$) vs. l/t. It was found that water vapor adsorption kinetics of chitosan-based films was accurately described by a simple empirical model and the rate constant of the model followed temperature dependence according to Arrhenius equation. Arrhenius kinetic parameters ($E_a$ and $k_o$) for water vapor adsorption by chitosan-based films showed a kinetic compensation effect between the parameters with the isokinetic temperature of 315.52 K.

• Journal of the Mineralogical Society of Korea
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• v.21 no.3
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• pp.307-312
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• 2008

Rietveld analysis using synchrotron X-ray powder diffraction data collected at 15 K reveals that CFC-13 ($CF_{3}Cl;$ chlorotrifluoromethane) sorbed on Na,K-LSX binds through fluorine to sodium ions around the single 6-ring aperture in the supcrgage.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1814-1818
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• 2003

$Li^+$ and $H^+$ co-exchanged LSXs (Li-H-LSX) with various ratios of $Li^+$ and $H^+$ were prepared, and those adsorption characteristics of nitrogen and oxygen were compared with Li-Na-LSX and Li-Ca-LSX. Li-H-LSX showed higher nitrogen capacity and selectivity than that of Li-Na-LSX in the wide range of Li-exchanged ratio. The nitrogen capacity of Li-Ca-LSX was slightly higher than that of fully Li- or Ca-exchanged LSX (Li- LSX or Ca-LSX). However, Li-Ca-LSX showed low nitrogen/oxygen adsorption selectivity until the Li content reached about 80%, which was a tendency near that of Ca-LSX.

• Journal of Environmental Science International
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• v.20 no.5
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• pp.667-672
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• 2011

The purpose of this work is to present the experiment results by a dynamic adsorption of water vapor on pelletized zeolites (ADZ300, ADZ400, and ADZ500) in fixed bed. The breakthrough curves of water vapor with several different concentrations and temperature in the range of 25~45 $^{\circ}C$ on zeolite bed were investigated. In the same conditions, the breakthrough time on ADZ400 and ADZ500 were little longer than ADZ300, and the equilibrium adsorption capacity on ADZ500 was highest. The higher the concentration of water vapor was, the faster the breakthrough time was, and the slope of breakthrough curves showed a tendency to increase. The faster the flow rate of water vapor was, the faster the breakthrough time was relatively, but variations between flow rate and breakthrough time did not have a proportional relationship. The breakthrough curve maintained constant gradient in spite of variation of flow rate in the same concentration. The temperature rise in zeolite bed by adsorption heat was occurred in the early stage of adsorption. After water molecule layers were formed on the surface of zeolite, the temperature was slowly cooled by water vapors continuously flowed in as constant temperature. The greater the concentration of water vapor and adsorption temperature were, the temperature difference in zeolite bed was increased.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.240-246
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• 1992

The electronic structure of oxygen atom of cation-exchanged zeolite was investigated by utilizing X-ray photoelectron spectroscopy(XPS). The obtained $O_{1S}$ spectra of $Na^+-$, $Fe^{2+}-$ and $Fe^{3+}-$ exchanged zeolite X and Y were deconvoluted to demonstrate electronic binding energy of framework oxygens. There were 2-3 bands in each spectrum. The characteristics of separated band have been studied in terms of binding energy and relative area of $O_{1S}$ electron with respect to the exchanged cation. Those bands were assigned to the bridged oxygen in framework (band 1), cation bonded oxygen in cationic site (band 2) and oxygen in water coordinated to the cation (band 3) each other. The band 1 occupying the majority area of $O_{1S}$ spectrum was shifted to higher region on binding energy according to the decrease of Al content in zeolite.

• Journal of the Mineralogical Society of Korea
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• v.28 no.4
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• pp.299-308
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• 2015

The six natural zeolites collected in Pohang area, Kyungsangbuk-do, Korea, were characterized by XRD, XRF, DTA, TGA, and CEC analysis. The primary species of these zeolite are modenite, albite, and quarts in Kuryongpo-A (Ku-A), Kuryongpo-B (Ku-B), Kuryongpo-C (Ku-C), Donghae-A (Dh-A), Donghae-B (Dh-B), and Donghae-C (Dh-C) samples. The XRF analysis showed that the six zeolites contain Si, Al, Na, K, Mg, Ca, and Fe. Cation exchange capacity of Kuryongpo-C (Ku-C) zeolite was the highest compared to other zeolites. The capabilities of removing heavy metal ions such as $Pb^{2+}$, $Cd^{2+}$ and $Cu^{2+}$ were compared. The effect of reaction time in removing heavy metal ions was studied. The experimental results showed that the efficiency of removal was low for $Pb^{2+}$, $Cd^{2+}$ and $Cu^{2+}$ ions. These may be caused by the low content of zeolite in the six natural zeolites. This indicates that the adsorption capacity roughly tends to depend on the zeoite contents, ie., the grade of zeolite ore.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.21.2-21.2
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• 2000

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.2
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• pp.133-142
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• 1998

Gas adsorption on adsorbents depends on temperatures and pressures. When these parameters are fixed, the adsorption capability and selectivity can not be changed. If the gas adsorption is controlled by another factor like electromagnetic field, the adsorption and desorption can be managed by much intentional way. The microwave has characteristics to excite particular components such as water without destroying it. In this study, microwave was irradiated to the adsorbent of an NaY zeolite which is almost transparent to microwave. As vapor of 1, 1, 2- trichloro-1, 2, 2-trifluoroethane (CFC-113) and water flowed simultaneously on the zeolite packed in a column at room temperature, only water was adsorbed. The . adsorbed water was removed from the zeolite and then replaced by CFC-113, since the microwave was irradiated. Greater the power of microwave was, more CFC-113 was adsorbed. The water adsorption took place again after a latent period by stopping the microwave irradiation.