STRUCTURAL INVESTIGATION OF SILICATE SPECIES IN ALKALINE AQUEOUS SOLUTIONS USING RAMAN SPECTROSCOPY
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Date
1984
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Ohio State University
Abstract
This study is part of an overall effort to understand the relationship between the silicate species that exist in alkaline medium. Raman spectroscopy provides a convenient and nondestructive method to study these systems without perturbing the equilibrium. The vibrational assignment of the bands to specific structures is the major challenge and will be discussed in the talk.
Description
We find that at large hydroxide ion concentrations (6 M), only the monomeric silicate species $Si(OH)_{2}O_{2}^{-2}$ exist in solution. As the hydroxide ion concentration is lowered, the monomeric species $Si (OH)_{3}O^{-}$, the dimeric species $Si_{2}O_{7}^{-6}$, and the cyclic trimeric and tetrameric species are formed. These species condense into large polymeric rings and at low hydroxide ion concentration (0.05 M), colloidal silica particles are present in solution. The Raman spectra of these colloidal particles are very similar to that of solid vitneous silica. These results and the vibrational assignments of the silica Raman bands based on the solution species will be presented.
Author Institution: Department of Chemistry, The Ohio State University
Author Institution: Department of Chemistry, The Ohio State University