Thermochemistry of Silicate Speciation in Aqueous Sodium Silicate Solutions: Ionization and Polymerization of Small Silicate Ion
Abstract
The thermochemistry of simple silicate oligomers in aqueous sodium silicate solutions is rationalized by a model that qualitatively predicts equilibria among monomer, dimer, and trimer silicate structures. Unlike previous models, it incorporates the influence of both silicate bonding and ion-solvent interactions on the stability of the anions. Although semiempirical molecular orbital calculations indicate that silicate bonds become less stable as charge increases, ion-solvent interactions tend to stabilize highly charged and compact silicate oligomers. Furthermore, polymerization is favored by the formation of highly stable water molecules and by a decrease of charge repulsion within the silicate structures. Although MNDO calculations indicate that the linear structures are more stable than the cyclic structures, ion-solvent interactions tend to stabilize the cyclic structures. Polymerization of compact silicate oligomers is also favored by producing more water molecules. Implications are summarized for larger silicate species.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 12, 1993
- Accession Number
- ADA266825
Entities
People
- A. V. Mccormick
- Jeremy Yang
Organizations
- University of Minnesota