Silica gels from aqueous silicate solutions: combined 29Si NMR and small-ange X-ray scattering spectroscopic study

P.W.J.G. Wijnen, T.P.M. Beelen, R.A. Santen, van

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Abstract

The use of modern spectroscopic techniques in the study of the formation of aqueous silica gels is described. The oligomerization process of monomeric silicic acid was studied by silicon-29 NMR spectroscopy; at high pH values cyclic trimeric silicate species were favored compared to the linear structure. Aggregation of primary silica particles of molecular size (<1 nm) was studied by analysis of small-angle x-ray scattering patterns. All systems studies (pH 4.0) indicate reaction-limited aggregation. Polyvalent cations influence the rate of aggregate formation in a negative way: aluminum at low concentrations (1 mol%) significantly inhibits aggregation. A new model for the aging process that proposes that monomeric silicic acid is transported (via solution) from the periphery of the aggregate into the core of the solution is given.

Original languageEnglish
Title of host publicationColloidal Silica
Subtitle of host publicationfundamentals and applications
EditorsH.E. Bergna, W.O. Roberts
Place of PublicationBoca Raton
PublisherCRC Press
Chapter45
Pages597-604
Number of pages8
ISBN (Electronic)9781420028706
ISBN (Print)9780824709679
Publication statusPublished - 2005

Publication series

NameSurfactant science series
Volume131

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  • Cite this

    Wijnen, P. W. J. G., Beelen, T. P. M., & Santen, van, R. A. (2005). Silica gels from aqueous silicate solutions: combined 29Si NMR and small-ange X-ray scattering spectroscopic study. In H. E. Bergna, & W. O. Roberts (Eds.), Colloidal Silica: fundamentals and applications (pp. 597-604). (Surfactant science series; Vol. 131). CRC Press.