TRANSFORMATION OF ZEOLITE NaY SYNTHESIZED FROM RICE HUSK SILICA TO NaP DURING HYDROTHERMAL SYNTHESIS
Keywords:
Zeolite synthesis, NaP, NaY, rice husk silica, crystallization time, aging time, hydrothermalAbstract
Rice husk silica powder with approximately 98% purity was used as a silica source for zeolite syntheses.This study investigated the transformation of zeolite NaY to zeolite NaP during hydrothermal synthesisat 100°C by fixing the ratio of SiO2, Al2O3, and Na2O at 10:1:4.6, the optimum ratio for NaY synthesis.The studied parameters included aging time (1, 2, and 3 days) and crystallization time (1, 2, 3, 4, and 5days). The transformation was observed by powder X-ray diffraction. The aging time did not havemuch effect on the transformation because when the crystallization time was fixed at 1 day, the synthesiswith 1-day aging produced pure phase NaY and that with 2 and 3 days produced only a small amountof NaP. In contrast, changes of the crystallization time, with a fixed aging time at 1 day, caused asignificant transformation. The transformation of NaY to NaP was observed in the synthesis withcrystallization of 2 days and the amount of NaP increased with the crystallization time. The NaY phasewas not observed after a crystallization time of 4 days and NaP with a cleaner phase was obtained aftercrystallization of 5 days. Consequently, the synthesis condition with an aging time of 1 day andcrystallization time of 5 days was the optimum condition for the transformation. Scanning electronmicrographs at this optimum condition showed a narrow size distribution in the range of 7 - 14 μm.
References
Albert, B.R., Cheetham, A.K., Stuart, J.A., andAdams, C.J. (1998). Investigation on Pzeolites:Synthesis, characterization andstructure of highly crystalline low-silicaNaP. Micropor. Mesopor. Mater., 21:133-142.
Flanigen, E.M., Khatami, H., and Szymanski,H.A. (1971). Molecular sieve zeolites.Adv. Chem. Ser., 101:201-228.
Huang, S., Jing, S., Wang, J., Wang, Z., and Jin,Y. (2001). White silica obtained from ricehusk in fluidized propellant bed. PowderTechnol., 117:232-238.
JCPDS/International Centre for DiffractionData. (1979). Powder Diffraction FileInorganics Phases: Alphabetical Index,Inorganics Phases, Swarthmore, Pennsylvania,p. 954-955.
Khemthong, P., Prayoonpokarach, S., andWittayakun, J. (2007). Synthesis andcharacterization of zeolite LSX fromrice husk silica. Suranaree J. Sci. Technol.,12(4):367-379.
Murayama, N., Yamamoto, H., and Shibata, J.(2002). Mechanism of zeolite synthesisfrom fly ash by alkali hydrothermal reaction.Int. J. Miner. Process., 64:1-17.
Nery, J.G., Mascarenhas, Y.P., and Cheetham,A.K. (2003). A study of highly crystalline,low-silica, fully hydrated zeolite P ionexchanged with (Mn2+, Cd2+, Pb2+, Sr2+,Ba2+) cations. Micropor. Mesopor. Mater.,57:229-248.
Sang, S., Liu, Z., Tian, P., Liu, Z., Qu, L., andZhang, Y. (2006). Synthesis of smallcrystals zeolite NaY. Mater. Lett., 60:1,131-1,133.
Sathupunya, M., Gularib, E., and Wongkasemjit,S. (2002). ANA and GIS zeolite synthesisdirectly from alumatrane and silatrane bysol-gel process and microwave technique.J. Eur. Ceram. Soc., 22:2,305–2,314.
Wittayakun, J., Khemthong, P., and Prayoonpokarach,S., (2008). Synthesis andcharacterization of zeolite NaY fromrice husk silica, Korean J. Chem. Eng.,25(4):861-864.
Zubowa, H.L., Kosslick, H., Muller, D., Richter,M., Wilde, L., and Fricke, R. (2008). Characterizationof phase-pure zeolite NaPfrom MCM-22-type gel compositionsunder microwave radiation. Micropor.Mesopor. Mater., 109:542-548.
