• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.243-248
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• 2005

Membrane pervaporation processes could have advantages over distillation for separation of water/organics mixtures: a low energy demand and the ability to separate azeotropic mixtures or isomers. Zeolite membranes might show better thermal, mechanical and chemical stabilities than polymer membranes. Water could be effectively separated from water/organic mixtures using the NaA zeolite membrane because of its high hydrophilicity. In this study, water was separated by pervaporation using the NaA zeolite membrane from water/ethanol mixtures. As a mole fraction of ethanol increased, the total permeation flux and the water flux decreased while the separation factor increased, reached a maximum point, and decreased. As an experimental temperature increased, the total permeation flux increased while the separation factor increased at the lower mole fraction of ethanol than 0.8 and it decreased at the higher mole fraction of ethanol than 0.8. The total permeation flux and the separation factor could be maintained constant during the long term experiment longer than 160 hours. It was found that the NaA zeolite membrane synthesized in our study showed better performance on water/ethanol separation than that of a distillation process or PVA polymeric pervaporation membranes.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.160-165
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• 2007

The synthesis and the characterization of Low Silica X (LSX) zeolite for nitrogen adsorption have been studied. The performance of LSX zeolite for nitrogen adsorption was compared to that of the commercial zeolite. The $Na_2O/(Na_2O+K_2O)$ ratio in the gel and the crystallization time were fixed as the synthetic factor. The LSX zeolite was formed at the $Na_2O/(Na_2O+K_2O)$ ratio of 0.75. The formation of LSX zeolite was confirmed by XRD and SEM. The Si/Al ratio was investigated by using XRF and FT-IR. The synthesized LSX zeolite showed a lower Si/Al ratio than the NaY and NaX zeolites although they have a same faujasite structure. The Si/Al ratio of the LSX zeolite converged close to 1. 1A (Li, Na, K) and 2A (Mg, Ca, Ba) group elements were ion-exchanged to the LSX zeolite. As the charge density of cation rises, the amount of nitrogen adsorbed increased. $Li^+$ ion-exchanged LSX zeolite showed the highest nitrogen adsorption weight. When the Li/Al ratio was over 0.65, nitrogen adsorption increased remarkably. $Li^+$ ions located on the supercage (site III, III') in the LSX zeolite played a role as nitrogen adsorption sites. When the $Ca^{2+}$ ions were added to the LiLSX zeolite by ion-exchange method, the performance for nitrogen adsorption increased more. The performance for the nitrogen adsorption was the highest at the Ca/Al ratio of 0.26. Nitrogen adsorption capacity of LiCaLSX (Ca/Al=0.26) zeolite was superior to the commercial NaX zeolite.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.273-278
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• 2007

The honeycomb adsorbents and adsorption process for carbon dioxide removal from fuel gas were investigated. Zeolite paper was made with Na-X zeolite powder and ceramic fiber as raw materials. $Li^+$, $Ca^{2+}$ or $K^+$ ion exchanges for Na-X zeolite and additional Na-X coating were performed on zeolite paper for increasing the carbon dioxide adsorption capacity, after that the adsorption characteristics of the samples were analyzed. Among the ion exchanged samples, $Li^+$ ion exchanged zeolite paper was most promising but its carbon dioxide adsorption capacity was less than expected for process application. However, additional Na-X coating was found to be an effective method for increasing the carbon dioxide adsorption capacity of the zeolite paper for process application. The carbon dioxide breakthrough test of the honeycomb adsorbent prepared with the zeolite paper was studied, and fuel gas treatment capacity was calculated when the honeycomb adsorbent was used in the rotary adsorption process.

• Journal of the Korean Ceramic Society
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• v.43 no.1 s.284
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• pp.1-3
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• 2006

Well-shaped NaA zeolite cubic crystals of a large size of $5-7{\mu}m$ were synthesized by a hydrothermal method in a mother solution having a $3.55Na_2O:Al_2O_3:1.6SiO_2:593\~2000H_2O$ composition. Thermal treatment of NaA zeolite crystals resulted in the formation of a crystalline phase of $NaAlSiO_4-Camegeite$ between 800 and $900^{\circ}C$. Even at $1000^{\circ}C,\;NaAlSiO_4$ phase was found as a major product. Environmental Scanning Electron Microscopy (ESEM), High Resolution Transmission Electron Microscopy (HRTEM), X-Ray powder Diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, and DTA/TGA and BET analyses were used to characterize the initial materials and the obtained products after various heat treatments.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2003.10a
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• pp.122-128
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• 2003

To develop a Mg-Zeolite for simultaneous recovery of the N and the P from sewage water, the natural zeolite was treated with 20% $MgCl_2$ solution by changing the pH the temperature and the treating time of the solution. And the contents of Ca Fe Na K Mg of Mg-Zeolite were analyzed by ICP. The optimum treatment condition for Mg-Zeolite was induced to pH 7.0 $50^{\circ}C$ in 20% $MgCl_2$ solution and for 80min treatment. And the Na and the K ions in natural zeolite are significant factors for Mg exchange in the zeolite.

• Journal of Environmental Science International
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• v.20 no.10
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• pp.1337-1345
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• 2011

The removal performances of divalent heavy metal ions ($Pb^{2+}$, $Cu^{2+}$, $Cd^{2+}$, $Sr^{2+}$ and $Mn^{2+}$) were studied using the Na-P1 zeolite synthesized from Jeju scoria in the batch and continuous fixed column reactor. The uptakes of heavy metal ions by synthetic Na-P1 zeolite decreased in the order of $Pb^{2+}$ > $Cu2^{2+}$ > $Cd^{2+}$ > $Sr^{2+}$ > $Mn^{2+}$ based on the selectivity of each ion to ionic exchange site of Na-P1 zeolite for single and mixed solutions in batch or continuous fixed column reactor. For mixed solution, each heavy metal ion uptake was lower than that in single solution, and especially the uptake for $Mn^{2+}$ decreased greatly. In batch reactor, the uptakes of heavy metal ions by synthetic Na-P1 zeolite were described by Freundlich or Langmuir equation, but they followed the former better than the latter. In continuous fixed column reactor, the maximum ion exchange capacity obtained for each of heavy metal ions, was about 90----- of that in batch reactor. The uptakes of heavy metal ions by synthetic Na-P1 zeolite increased with the increase of initial heavy metal concentration and solution pH, and the decrease of the amount and particle size of synthetic zeolite.

• Journal of the Korean Ceramic Society
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• v.18 no.2
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• pp.91-98
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• 1981

Synthetic zeolite A was prerared from domestic Hadong kaolin with sodium hydroxide solution and their ion exchange isotherms of $K^+$, $NH^{4+}$, $Li^+$ and $Ag^+$ ion were presented. The optimum reaction conditions for synthetic zeolite A from calcinated kaolin were 2 fold excess of 2N sodium hydroxide solution, 10$0^{\circ}C$ and 8 hours. It was observed that before the crystallization of zeolite A the samples reacted with sodium hydroxide solution had rather higher ion exchange capacities than zeolite A. The $K^+$-$Na^+$ and $Ag^+$$Na^+$ ion exchange isotherms were signoidal. The initial selectivity series was in the order $Ag^+$$K^+$>$Na^+$>$NH_4$>$Li^+$. Between approximately 33 and 67% replacement of soium ions the selectivity series became $Na^>$ and above 67% became $Ag^+$>$K^+$. Evidence were also presented to demonstrate that 8 out of 12 sodium ions per pseudo unit cell were not easily replaceable by lithium ions and 4 out of 12 not easily replaceable by ammonium ions.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1651-1660
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• 2013

The adsorption of lithium ion onto zeolite was investigated depending on contact time, initial concentration, cation forms, pH, and adsorption isotherms by employing batch adsorption experiment. The zeolite was converted into different forms such $K^+$, $Na^+$, $Mg^{2+}$, $Ca^{2+}$, and $Al^{3+}$. The zeolite had the higher adsorption capacity of lithium ion in $K^+$ form followed by $Na^+$, $Ca^{2+}$, $Mg^{2+}$, and $Al^{3+}$ forms, which was in accordance with their elctronegativities. The lithium ion adsorption was explained using the Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms and kinetic models. Adsorption rate of lithium ion by zeolite modified in $K^+$ form was controlled by pseudo-second-order and particle diffusion kinetic models. The maximum adsorption capacity obtained from Langmuir isotherm was 17.0 mg/g for zeolite modified in $K^+$ form. The solution pH influenced significantly the lithium ions adsorption capacity and best results were obtained at pH 5-10.

• Journal of the Korean Chemical Society
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• v.21 no.2
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• pp.89-93
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• 1977

Faujasite type zeolite synthesized from kaolin minerals was cation-exchanged and the catalytic activities of $1-Butene{\rightarrow}2-butene$ took place readily even on zeolites having no strong acid sites. The order of activity for isobutene formation was La > H > Zn > Na-faujasite, La-faujasite showing much higher activity. The same trend was observed for propylene formation except that both La-and H-faujasite showed comparable activity. The results seem to indicate that the activities for 1-buten cracking and isomerization on zeolite are directly related to the strength and concentration of the acid sites on zeolites.

• Membrane and Water Treatment
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• v.8 no.5
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• pp.437-448
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• 2017

A high quality Na-X zeolite membrane was synthesized on a seeded ${\alpha}-alumina$ disc by the secondary growth method. Structural characterization was done by X-ray spectroscopy, FT-IR spectroscopy, SEM and AFM imaging. The performance evaluation of the membrane was firstly tested in separation of glucose/water solutions by pervaporation process. There was obtained a separation factor $182.7{\pm}8.8$, while the flux through the membrane was $3.6{\pm}0.3kg\;m^{-2}\;h^{-1}$. The zeolite membrane was then used for desalination of aqueous solutions consisting of $Na^+$, $Ca^{2+}$, $Cs^+$ and $Sr^{2+}$ because of the importance of these ions in water and wastewater treatments. The effects of some parameters such as temperature and solution concentration on the desalination process were studied for investigating of diffusion/adsorption mechanism in membrane separation. Finally, high water fluxes ranged from 2 up to $9kg\;m^{-2}\;h^{-1}$ were obtained and the rejection factors were resulted more than 95% for $Na^+$ and $Ca^{2+}$ and near to 99% for $Cs^+$ and $Sr^{2+}$. Based on the results, fluxes were significantly improved due to convenient passage of water molecules from large pores of NaX, while the fouling was declining dramatically. Based on the results, NaX zeolite can efficiently use for the removal of different cations from wastewaters.