1. Effects of magnesium ions on near-equilibrium calcite dissolution: Step kinetics and morphology
- Author
-
Xu, Man and Higgins, Steven R.
- Subjects
- *
MAGNESIUM ions , *CALCITE , *MORPHOLOGY , *ANALYTICAL mechanics , *ATOMIC force microscopy , *ANISOTROPY , *SOLUTION (Chemistry) , *GEOCHEMICAL modeling - Abstract
Abstract: Dissolution kinetics at the aqueous solution-calcite interface at 50 °C were investigated using in situ atomic force microscopy (AFM) to reveal the influence of magnesium concentration and solution saturation state on calcite dissolution kinetics and surface morphology. Under near-equilibrium conditions, dissolved displayed negligible inhibitory effects on calcite dissolution even at concentrations of . Upon the introduction of , the solution saturation state with respect to calcite, , acted as a “switch” for magnesium inhibition whereby no significant changes in step kinetics were observed at , whereas a sudden inhibition from was activated at . The presence of the -switch in dissolution kinetics indicates the presence of critical undersaturation in accordance with thermodynamic principles. The etch pits formed in solutions with exhibited a unique distorted rhombic profile, different from those formed in Mg-free solutions and in de-ionized water. Such unique etch pit morphology may be associated with the anisotropy in net detachment rates of counter-propagating kink sites upon the addition of . [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF