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Studies of mechanism of silica polymerization reactions in the combination of silica sol and potassium sodium waterglass via isothermal heat conduction microcalorimetry

Studies of mechanism of silica polymerization reactions in the combination of silica sol and... Isothermal heat conduction microcalorimetry was adopted as a novel characterization method to investigate the polymerization processes of silica when the combination of silica sol and potassium sodium silicate was stirred at 25.0, 35.0, and 45.0 °C. Thermodynamic and kinetic parameters were simultaneously obtained. The enthalpy change was greater at each higher temperature. The reaction orders ( m , n ) instantaneously varied, up and down in an alternate manner. At 25.0, 35.0, and 45.0 °C, the rate constants were different; the maximum rate constant occurred at 25.0 °C. These phenomena reflect a two-stage oligomeric mechanism of silica monomers. The measurements of particle size showed the complex chemical composition of aqueous silicates, which can be qualitatively designated by the particle size distribution in two parts. The results further indicate that the colloidal particles in the mixed silica sol and silicates first dissolved. Then the “active” silica in the silicates redeposited to make a distinct particle size distribution influenced by K + and Na + ions as well as by temperature. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Thermal Analysis and Calorimetry Springer Journals

Studies of mechanism of silica polymerization reactions in the combination of silica sol and potassium sodium waterglass via isothermal heat conduction microcalorimetry

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References (39)

Publisher
Springer Journals
Copyright
Copyright © 2010 by Akadémiai Kiadó, Budapest, Hungary
Subject
Chemistry; Measurement Science and Instrumentation; Inorganic Chemistry ; Polymer Sciences ; Analytical Chemistry ; Physical Chemistry
ISSN
1388-6150
eISSN
1572-8943
DOI
10.1007/s10973-010-0697-9
Publisher site
See Article on Publisher Site

Abstract

Isothermal heat conduction microcalorimetry was adopted as a novel characterization method to investigate the polymerization processes of silica when the combination of silica sol and potassium sodium silicate was stirred at 25.0, 35.0, and 45.0 °C. Thermodynamic and kinetic parameters were simultaneously obtained. The enthalpy change was greater at each higher temperature. The reaction orders ( m , n ) instantaneously varied, up and down in an alternate manner. At 25.0, 35.0, and 45.0 °C, the rate constants were different; the maximum rate constant occurred at 25.0 °C. These phenomena reflect a two-stage oligomeric mechanism of silica monomers. The measurements of particle size showed the complex chemical composition of aqueous silicates, which can be qualitatively designated by the particle size distribution in two parts. The results further indicate that the colloidal particles in the mixed silica sol and silicates first dissolved. Then the “active” silica in the silicates redeposited to make a distinct particle size distribution influenced by K + and Na + ions as well as by temperature.

Journal

Journal of Thermal Analysis and CalorimetrySpringer Journals

Published: Sep 1, 2010

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