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Research Article
ScienceAsia 32 (2006): 013-016 |doi: 10.2306/scienceasia1513-1874.2006.32.013
Phase Diagram of Zeolite Synthesized from
Perlite and Rice Husk Ash
Paisan Kongkachuichay* and Pataraporn Lohsoontorn
ABSTRACT: This research aimed to synthesize zeolites from perlite obtained from Lopburi Province, Thailand,
and from rice husk ash, under hydrothermal condition. The experiments were carried out in an autoclave
with SiO2/Al2O3 molar ratios of 1 to 40, NaOH concentrations of 1 to 4 N, and starting pressure of 1 atm. The
rice husk ash and AlCl3.6H2O were used to adjust the SiO2/Al2O3 molar ratio. The autoclave was heated with
the rate of 1.5 oC/min to the set points of 140 and 170 oC at which it was kept isothermally for 2 h. The results
showed that the products detected were analcime, Na-P1, and sodalite octahydrate. However, at very low
SiO2/Al2O3 ratio and NaOH concentration, no zeolite could be formed at 140 oC. The analcime could be
formed at almost all conditions, except at low concentration of NaOH and the SiO2/Al2O3 ratio below 25.
Furthermore, the Na-P1 could be detected in every area except at high concentration of NaOH and high
SiO2/Al2O3 ratio at which only analcime and sodalite octahydrate were found. The sodalite octahydrate was
formed preferably at high concentration of NaOH and high ratio of SiO2/Al2O3. At temperature of 170 oC,
the formation of analcime was enhanced, while the others seemed to be unaffected. Finally, phase diagrams
of detected zeolites were constructed.
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Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, 50 Paholyothin Road,
Jatujak, Bangkok, 10900, Thailand.
* Corresponding author, E-mail: fengpsk@ku.ac.th
Received 9 May 2005,
Accepted 20 Jul 2005
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