Publication details

Interaction of Freshly Precipitated Silica Gel with Aqueous Silicic Acid Solutions under Ambient and Near Neutral pH-conditions: A Detailed Analysis of Linear Rate Law



Year of publication 2008
Type Article in Periodical
Magazine / Source Aquatic Geochemistry
MU Faculty or unit

Faculty of Science

Field Geochemistry
Keywords Dissolution; Growth; Dynamics; Error; Experiment; Flux; Model; Reversibility; Silica gel
Description Interaction of freshly precipitated silica gel with aqueous solutions was studied at laboratory batch experiments under ambient and near neutral pH-conditions. The overall process showed excellent reversibility: gel growth could be considered as an opposite process to dissolution and a linear rate law could be applied to experimental data. Depending on the used rate law form, the resulting rate constants were sensitive to errors in parameters/variables such as gel surface area, equilibrium constants, Si-fluxes, and reaction quotients. The application of an Integrated Exponential Model appeared to be the best approach for dissolution data evaluation. In contrast, a Differential Model gave best results for growth data modeling. An universal value of activation energy for growth of any silica polymorph is not consistent with the value for silica gel growth, which questions the hypothesis about one unique activated complex controlling the silica polymorph growth.
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