• Journal of the Mineralogical Society of Korea
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• v.19 no.1 s.47
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• pp.7-14
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• 2006

Melting slag generated from the lots of municipal incineration ash, which causes the one of big urban problems in modern industrial society, was used as starting material for the hydrothermal synthesis of zeolite. P-type zeolite has been successfully synthesized by the combined process of both 'hydrogelation' and 'clay conversion' method. Commercial sodium silicate was used as Si source, and $NaAlO_2$ was prepared by the reaction in a $Na_{2}O/Al_{2}O_{3}$ molar ratio of 1.2. The optimum conditions for zeolite synthesis was found to be the $SiO_{2}/Al_{2}O_{3}$ ratio in the 3.2 and 4.2 range, the $H_{2}O/Na_{2}O$ ratio in the 70.7 and 80.0 range, and more than 15-hour reaction time at $80^{\circ}C$, In the synthesized zeolite, inhomogeneous melting slag particles were disappeared and homogeneous P-type zeolite crystal was grown. The cation exchange capacity of the synthesized zeolite was determined to be approx. 240 cmol/kg.

• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.301-310
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• 2006

Smectites were synthesized from Na-P type and Na-A type zeolites by the hydrothermal synthetic method, and their physicochemical properties were studied. The optimal synthetic conditions for producing smectite were $290^{\circ}C$, 72 hr and $75{\sim}100kgf/cm^2$ in autogenous pressure. pHs of initial reaction solutions for the synthesis of smectites from Na-P type and Na-A type zeolite s were pH 6 and pH 10, respectively. The synthetic smectite was confirmed as $12{\AA}$-beidellite by a series of analysis such as X-ray diffraction analysis with random and oriented mounts, ethylene glycol treatment, and Greene-Kelly test, and their several physicochemical properties were studied.

• Resources Recycling
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• v.17 no.4
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• pp.57-65
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• 2008

The behavior of Na-A type zeolite formed in hydrothermal synthesis of melting slag from municipal incineration ash has been investigated with varying synthesis time and $SiO_2/Al_2O_3$ ratio. Sodium silicate and sodium aluminate feed was found to initially form nuclei of Na-A type zeolite in the behavioral study of the reaction products with different synthesis times. As the synthesis time increased, the nuclei have grown to Na-A type zeolite crystals by reacting with $SiO_2$ and $Al_2O_3$ dissolved from the melting slag. The hydrothermal synthesis was completed in 10 hr in the $SiO_2/Al_2O_3$ ratio of 1.38 and after that time, the Na-A type zeolite formed was dissolved and transformed into hydroxysodalite. Only Na-A type zeolite was formed in the $SiO_2/Al_2O_3$ ratio ranging 0.80 to 1.96, whereas Na-P type zeolite as well as Na-A type was formed in the $SiO_2/Al2O_3$ ratio of 2.54.

• Proceedings of the Petrological Society of Korea Conference
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• 2006.05a
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• pp.12-14
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• 2006

• Membrane Journal
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• v.9 no.2
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• pp.97-106
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• 1999

A and 2SM-5 type zeoli tic crystal films were synthesized on porous supports from the reaction mixture of 1.9 ${SiO}_2$1.5 $Na_20-Al_2O_3-40$ $H_20$ and $Si0_2$-0.l3 $Na_2O$-52 $H_20$-O.l2 TPAOH composition, respectively. The zeolite films were characterized by XRD and SEM. The 2SM -5 crystals grown on the porous matrix were very closely bound together. It was so difficult to obtain the perfectly intergrown crystals in the case of A-type zeolite and this crystal was transformed into P-type zeolite membrane with a prolonged reaction time. The densely intergrown A type zeolite crystal membrane could be also synthesized by the hydrothermal treatment at 100$^{\cirt}C$ after pressing the reaction mixture without addition of water. The pervaporation performance of the synthesized porous inorganic membranes was investigated for alcohol and water mixtures. A-type zeolite membrane crystallized as a thin film showed the selective \'Jermeability of water from the mixtures through the molecular sieving activity of micropores.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.223-229
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• 2007

The mechanism of hydrothermally synthesizing Na-A zeolite from siliceous mudstone at a $Na_2O/SiO_2$ ratio of 0.6, a $SiO_2/Al_2O_3$ 2.0 and a $H_2O/Na_2O$ 119 has been observed by IR, DTA, XRD and SEM. This mudstone is a tertiary periodic sedimentary rock and widely spreads around the Pohang area. In the early hydrothermal synthesis at $80^{\circ}C$ in an autoclave, sodium silicate and sodium aluminate were found to be preferentially reacted to generate Na-A type zeolite. Gibbsite and bayerite were also formed due to the presence of extra aluminum oxide in the feedstock. As reaction time in-creased up to 50 h, residual sodium aluminatewas reacted with siliceous mudstone, causing the Na-A zeolite crystal to grow and the hydroxylsodalite to generate. Therefore, in the $14{\sim}50\;h$ synthetic time, Na-A zeolite and hydroxylsodalite were formed. Also, if reaction time passed over 50 h, a part of the Na-A zeolite was finally redissolved and reacted with hydroxylsodalite to synthesize Na-P zeolite, generating porous surface of Na-A zeolite and disappearing hydroxylsodalite.