• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1765-1775
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• 2000

The removal of radioactive organic iodide generated from high temperature process in nuclear facility was generally performed by silver ion-exchanged synthetic zeolite (AgX). The purpose of this study is to obtain fundamental data for the substitution of natural zeolite(NZ) in stead of synthetic zeolite as supporter for the removal of methyl iodide in high temperature conditions. Therefore, NZ was modified with NaCl, $NaNO_3$ solution, and the analysis of the physical or surface characteristics through XRD, SEM-EDAX, and BET analysis was performed. In order to obtain the optimal surface-modification condition of NZ, adsorption capacities at $150^{\circ}C$ on surface-modified silver ion-exchanged NZ prepared with the variation of solution concentration were evaluated. The optimal condition of surface modification is that concentration of $NaNO_3$ and $AgNO_3$ are 1N and 1.2N, respectively(namely Ag-SMNZ). The adsorption isotherm of methyl iodide on Ag-SMNZ in a range of $100^{\circ}C$ to $300^{\circ}C$ was obtained, which is similar to that of 13X, and the maximum adsorption amount of Ag-SMNZ reached approximately 50% that of AgX. It would be evaluated that the adsorption capacity at $150{\sim}200^{\circ}C$ is relatively higher than other temperature, and the chemisorption between silver and iodide is attributed to a strong binding even after desorption test.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.371-376
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• 1999

A large NaX type zeolite crystal of a uniform particle size of 20$\mu\textrm{m}$ are grown with various {{{{{H}_{2}O}}}} content by hydrothermal reaction and added seed crystal (2~3$\mu\textrm{m}$) to reactant solution as a function of different adding seed levels from 3 to 15%. The result that increased purity of NaX zeolite above 95% and homogeneity of crystal size by increasing adding seed levels, also decreased crystallization time. It was explained that adding seed to synthesis solution leaded out increase of surface area for physical contact reaction and directed growth of seed crystal, so more rapid consumption of reaction gel as increase seeding levels.

• Journal of the Korean Geophysical Society
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• v.4 no.4
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• pp.251-256
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• 2001

Korean natura1 zeolite with fe1dspar and illite as impurities was purified by an air c1assification method. X-ray powder diffraction ana1yses showed that the air c1assification effectively separated zeolite and impurities, and reduce the amount of impurity of the natura1 zeolite. The zeolite with air c1assification was treated with 1N NaOH solutions at temperatures at 100, 150, 200 ℃ for 17hours. The obtained hydrotherma1 treatment of phase change to philli1site and ana1cime from mordenite and clinopti10lite.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.6
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• pp.238-244
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• 2007

Nano-sized ZnO crystals were successfully incorporated using ion exchange method in TMA-A zeolite synthesized by the hydrothermal method. The optimal composition for the synthesis of TMA-A zeolite was resulted in a solution of $Al(i-pro)_3$:2.2 TEOS:2.4 TMAOH:0.3 NaOH:200 $H_2O$. 0.3g of TMA-A zeolite and 5mol of $ZnCl_2$ solution were employed for the preparation of ZnO incorporated TMA-A zeolite. The ZnO incorporated TMA-A zeolite precursors, prepared from the process of mixing, stirring, centrifugal separation and drying, were calcined at temperatures from 400 to $600^{\circ}C$ for 3 h. The crystallization process of ZnO incorporated TMA-A zeolite was analyzed by X-ray diffraction (XRD). The Brunaur-Emett-Teller (BET) surface area of the ZnO incorporated TMA-A zeolite was measured. Subsequently, the morphology and the particle size depending on the temperature and time were observed using scanning electron microscopy(SEM), transmission electron microscopy(TEM) and particle size analyzer.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.59.2-59.2
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.88.2-88
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.129.2-129
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• 2003

• Bulletin of the Korean Chemical Society
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• v.5 no.4
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• pp.135-140
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• 1984

The reduction of vacuum-dehydrated $Na_xAg_{12-x}-A, 0 {\le} x {\le} 9.2$, and its reoxidation by O$_2$, have been studied by X-ray powder diffraction. Also, the structure of $Na_6Na_6-A$ treated with hydrogen at room temperature has been studied by single crystal methods in the cubic space group Pm3m at $24{\circ}C (a = 12.221(2) {\AA})$. The diffraction pattern of dehydrated Ag$_{12}$-A reduced by H$_2$ contains only the (111) and (200) reflections of silver metal, indicationg that the zeolite structure has been lost, but the zeolite's diffraction pattern and structural integrity can be fully restored by oxidation with O$_2$ at 100 or 200${\circ}C$. In contrast, the structures of $Na_xAg_{12-x}-A$, x = 4.5 and 9.2, were not destroyed by treatment with hydrogen. Dehydrated Na$_6Ag_6$-A treated with 50 Torr of hydrogen gas at 24${\circ}C$ for 30 minutes has $6\; Na^+\;and\;1.27\;Ag^+$ ions at 6-ring sites. These $Ag^+ ions are associated with 2.54 Ag${\circ}$ atoms to form 1.27 $Ag_3^+$ clusters per unit cell. Also found were 0.7 $Ag_3^{2+}$ clusters per unit cell near the 8-rings. The structure was refined to the final error indices R$_1$ = 0.134 and R$_2$ (weighted) = 0.147, using 168 independent reflections for which $I_0 >3{\sigma}(I_0)$.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.95-106
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• 1998

To reduce the environmental contamination and to utilize fly ash massively produced from the coal power plant every year, we synthesized the artificial zeolite using fly ash treated with alkaline, and then analyzed the mineralogical and morphological properties by X-ray, IR, and SEM. The amount of $NH_4{^+}$, $K^+$, and $H_2PO_4{^-}$ adsorbed by the fly ash and the artificial zeolite were determined with reaction time, amount of adsorbate used, ion concentrations. The results obtained from the pot experiments packed with the top soil, amended with granulated artificial zeolite which was made by treatment of 4% polyvinylalcohol, showed that CEC of the artificial zeolite was $257.7cmol^+kg^{-1}$, that was almost 36 times greater than that of fly ash. The ratio of $SiO_2/Al_2O_3$ decreased but the amount of Na increased. The physico-chemical properties analyzed by X-ray, IT, and SEM represented that the artificial zeolite synthesized had a similar morphological structure to that of the natural zeolite. The structures of the artificial zeolite had a significantly enlarged surface having a lot of pores, while the fly ash looked like spherical smooth shape with having not pores on the surface. Thus, the artificial zeolite was successfully synthesized. The results of adsorption isotherms of fly ash and artificial zeolite showed that the amount of $NH_4{^+}$, $K^+$, and $H_2PO_4{^-}$ adsorbed increased as the equilibrium concentration increased, while $NH_4{^+}$ was strongly adsorbed on the surface of fly ash and artificial zeolite than that of $K^+$. The most distinctive growth of Chinese cabbage was found from the top soil(NPK + soils + 20% of granulated artificial zeolite + 5% of compost). Therefore, we concluded that one of the most effective methods to effectively recycle a fly ash was to make the artificial zeolite as we did in this experiment.

• Journal of the Korean Chemical Society
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• v.23 no.6
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• pp.374-384
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• 1979

Hydration scheme and hydration energy are determined in ${\alpha}$ cage of zeolite NaA. The selectivity between Na(1) and Na(2) is determined from energy calculation. The waters in ${\alpha}$ cage form a distorted dodecahedral cage. The average binding energies of water(1), water(2) and water(3) are -29.847, -25.344 and -15.888 kcal/mole respectively. The positions of oxygens of hydrated waters are in good agreement with the X-ray data. The heat of immersion curve is also obtained. This result is in good agreement with the differential heat of sorption curve obtained from differential thermal analysis. It is concluded that theoretical method provides considerable uses in the determination and understanding of the hydration and interaction energy of zeolites sorbate binding.