?HYDROTHERMAL CRYSTALLIZATION AND CRYSTAL GROWTH OF a-Si02 FROM RICE HUSK SILICA ASH IN ALKALINE SOLUTIONS

Authors

  • SA EL Korashy Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia, Egypt

Keywords:

Rice husk silica, a-Si02, Silicalite, Crystal growth, Hydrothermal, Microstructure.

Abstract

White pure and active amorphous silica was prepared from rice husk with 99.96% purity by acid leaching and pyroly-
sis. This silica could be crystallized into prismatic microcrystalline a-Si02 (n-88nm) under hydrothermal conditions
(215 °C::::-20 atm. press.) from alkaline solutions. The maximum yield of a-Si02 was obtained at O. 6 molar ratio of NaOH I Si02 which reduced to O. 2 in the presence of AP+ and lor B3+traces. This is due to the formation of silicalite
crystals (considered to be a polymorph of Si02). It has been found that transition metal cations in the reaction media affects the degree of a-Si02 crystallization in the order: Fe3+> Ni2+> Cr3+> amorphous Si02 > C02+> Cu2+;:' Mn2+> Zn2+> Zr4+> La3+.Both mechanism of a-Si02, silicalite growth and ions incorporation were discussed.

Published

1998-12-21

How to Cite

Korashy, S. E. (1998). ?HYDROTHERMAL CRYSTALLIZATION AND CRYSTAL GROWTH OF a-Si02 FROM RICE HUSK SILICA ASH IN ALKALINE SOLUTIONS. Biological Sciences - PJSIR, 41(6), 312–317. Retrieved from http://v2.pjsir.org/index.php/biological-sciences/article/view/2300

Issue

Vol. 41 No. 6 (1998): Pakistan Journal of Scientific and Industrial Research

Section

Articles