The development of an aqueous thermodynamic model for polymerized silica species is presented which is valid to high ionic strengths and high dissolved silica concentration (~0.1m) at low temperature (22-25?C). The model is based upon the equations of Pitzer and has been parameterized from solubility, electromotive force (emf), and nuclear magnetic resonance (NMR) data. The description of the silica speciation reactions at high dissolved silica and basic conditions (pH >10) required the inclusion of monomeric, dimeric, trimeric (linear, cyclic and substituted), tetrameric (linear and cyclic) and hexameric (prismatic) species. The standard state equilibrium constants for the formation of these species, as well as the necessary Pitzer ion-interaction parameters to describe the ionic strength dependence of the formation reactions were determined.
Revised: March 2, 2004 |
Published: June 1, 2001
Citation
Felmy A.R., H.M. Cho, J.R. Rustad, and M.J. Mason. 2001.An Aqueous Thermodynamic Model for Polymerized Silica Species to High Ionic Strength.Journal of Solution Chemistry 30, no. 6:509-525.PNNL-SA-34535.