• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.616-620
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• 2001

The objectives of this study are to investigate the suitability of various coal fly ashes and incineration ashes for zeolite synthesis. Zeolite P and hydroxysodalite are produced from coal fly ash and paper sludge incineration ash. When soluble and acid-soluble materials in incineration fly ash are removed by the water washing or acid washing before hydrothermal synthesis, hydroxysodalite can be produced. The factors to make solid-liquid separation difficult are the calcium component and the unburned carbon in ash.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.575-584
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• 1999

Through alkaline hydrothermal activation processes, zeolite minerals were synthesized from fly ashes produced at Youngwol and Boryoung power plants. The syntheses were performed in a closed teflon vessel with a teflon-coated magnetic bar for continuous stirring during the reaction periods. The experiments were caeeied out at three different reaction temperatures ($100^{\circ}C$,$200^{\circ}C$, and $250^{\circ}C$), with varying NaOH concentations (0.5~8N) and reaction time (24 to 288 hours). Mineralogical characterization of the reaction products indicated that Na-p1, analcime, and hydroxysodalite were dominant zeolites formed from the both fly ashes at the given experimental conditions, The highest amount of zoelites produced from the Youngwol and Boryoung fly ash were:60 and 45wt%for Na-P1, 70 and 45wt% for analicime, 50 and 40wt% for hydroxysodalite, respectively. A small amount of zeolite A was present in NaP-dominant dample is about 250 meq/100g. This suggests the possibility of its utilization as an ion-absorbent.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.73-79
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• 2000

Highly porous amorphous silica obtained from a serpentine mineral by hydrochloric acid treatment was used to produce a zeolite A through the hydrothermal reaction under atmospheric pressure. An optimum synthesis condition of the zeolite A was achieved at $80^{\circ}C$ for two hours with a mole ratio of $Na_2O/SiO_2$1.5. Additionally, it was found that a hydroxysodalite zeolite was formed under the experimental conditions over the reaction temperature of $80^{\circ}C$ and the reaction time of 120 minutes even though the crystallization of zeolite proceeds rapidly as the reaction temperature and the alkalinity becomes higher.

• Journal of the Korean Ceramic Society
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• v.20 no.3
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• pp.255-259
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• 1983

Am(rphous aluminosilicate zeolite A and hydroxysodalite were obtained by reaction of Hadong kaolin(halloysite) with IN sodium hydroxide solntion in the temperature range of 60 to 10$0^{\circ}C$ For determination of the mechanism of the reaction Various possible mechanisms were compared with the experimental results. It was observed that the reaction mechamism of zeolite A synthesis from Hadong kaolin was first order consecu-tive reaction as follows : halloysitelongrightarrowamorphous aluminosilicatelongrightarrowzeolite Alongrightarrowhydroxysodalite

• Journal of the Korean Applied Science and Technology
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• v.32 no.2
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• pp.240-247
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• 2015

Zeolite A was prepared from coal fly ash upon NaOH fusion treatment, followed by hydrothermal treatment. The effects of treatment conditions such as NaOH/ash ratio, fusion temperature, the amount of sodium aluminate added, hydrothermal treatment temperature and time on the type and the crystallinity of zeolites were investigated. The optimal NaOH/ash weight ratio and fusion temperature to produce high crystalline zeolite A were 1.2 and $550^{\circ}C$, respectively. The dissolution of $Si^{4+}$ and $Al^{3+}$ from the fused fly ash was not affected by stirring time. The type of synthetic zeolites was found to be dependent on the amount of sodium aluminate added. The low amount of sodium aluminate favored zeolite X, while a single phase zeolite A was produced by increasing the amount sodium aluminate. Zeolite A was transformed into hydroxysodalite with increasing hydrothermal treatment time and temperature. A high crystalline zeolite A could be obtained by decreasing the temperature increasing time up to the reaction temperature.

• Journal of the Korean Chemical Society
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• v.16 no.4
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• pp.241-248
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• 1972

The adsorption of Methylene Blue on Yeong-Il bentonite which was treated by aqueous NaOH, $Na_2SO_4 or NaHSO_4 solution respectively, varying concentrations, temperature and time, was studied. In case of treatment with NaHSO_4 solution, slight improvement of the adsorption of Methylene Blue on bentonite was observed. With Na_2SO_4$ solution, the best results obtained when bentonite was treated with 1 N of the solution for 2hr at $100^{\circ}C$, and the adsorption capacity of the product was 3 times better than that of original bentonite. At the higher concentration and the higher temperature than above, faujasite was formed. With NaOH solution, the best condition was in 1N solution for 1hr at $100^{\circ}C$ and the adsorption capacity of the product was 3.3 times better than that of original bentonite. At the higher concentration of the treating agent and at the higher temperature than above, hydroxysodalite was formed.

• Journal of the Mineralogical Society of Korea
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• v.13 no.4
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• pp.171-185
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• 2000

Siliceous mudstones are embedded on a large scale in the Tertiary formations of Pohang area. Some useful zeolites such as NsP, (Na, TMA)P, analcime and hydroxysodalite were synthesized from the siliceous mudstones by treating with the variety of solution, i.e ., NaOH, NaOH+NaCl, NaOH, NaOH+$NaAlO_2$and NaOH+TMAOH at the low-temperature hydrothermal system ranging 60~12$0^{\circ}C$. Major precursor of zeolites is found as opal-CT in the zeolite-forming reaction. Smectite, which is included in considerable amounts in the mudstone, appears to play a major role of Al-source in the zeolite synthesis. In comparison, chalcedonic quartz and mica are rather insoluble in alkaline solution, and thus, these are observed as major impurities in the reaction products. An addition of $NaAlO_2$to NaOH solution is effective for eliminating these impurities in the reaction procedure, through these are partly dissolved when elevating the reaction temperature, concentration, and time. Phase change from NaP to hydroxysodalite takes place at the NaOH concentrations of 3.0~4.0 M, and the reaction is not sensitive to the temperature shift. NaP is more stable at lower NaOH concentration and higher activity of $Na_{+}$ whereas analcime is sensitive to the temperature change and stable at higher than $100^{\circ}C$ and 2.0~4.0 M in NaOH concentration. For the pure NaP synthesis without any other products, the treatment of mudstones with 1:1 solution of NaOH and $NaAlO _2$ turns out to be quite effective. NaP was successfully synthesized together with analcime at $100^{\circ}C$ as well as lower concentrations of NaOH+NaCl solution. In addition, the organic type, (Na, TMA)P was formed together with smectite in the 1:1 solution of NaOH and TMAOH.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.319-320
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• 2009

The alkali activation products of slag, fly ash C and fly ash F were investigated using compressive strength test and synchrotron x-ray diffraction. We propose that the predominantly amorphous geopolymer formed under ambient conditions is a disordered form of one of the ABC-6 group of zeolites, which includes poly-types such as hydroxycancrinite, hydroxysodalite, chabazite, levyne or fransinite.

• Journal of environmental and Sanitary engineering
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• v.12 no.1
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• pp.49-58
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• 1997

A study on the synthesis of zeolite from bituminous coal ESP fly ash as a raw material, which was emitted from the power plant, was carried out to reduce environmental problems and reuse of the industrial wastes. Bituminous coal fly ash was used as the source of silica and alumina. Zeolite was synthesized by hydrothermal reaction in aqueous NaOH solution with sodium aluminate as additive. The objective of this study is to elucidate the effect of several experimental variables on the synthesis of zeolite. The effects of preroasting temperature, mixing speed, leaching alkalinity, and molar ratio of Na$_{2}$O/SiO$_{2}$ and SiO$_{2}$/Al$_{2}$O of the products were investigated. The synthesized zeolite was proved to be NaA, which is known as 4A type, by comparing with SEM images, and X-ray diffraction analysis. And also we know that the transformation of zeolite A take places into other types of zeolites, i.e. Hydroxysodalite, zeolite P, with the variation of leaching alkalinity.

• 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.