Anisotropic dissolution at the CaCO3(10(1)over-bar4)-water interface

On the basis of the framework of the terrace-ledge-kink model of dissolution, the site-specific dissolution kinetics at the CaCO3(10(1) over bar 4)-water interface have been investigated using atomic force microscopy. The experiment was carried out in a solution cell where the ''real-time'' dissolution kinetics were examined under different flow and temperature conditions. Results show that dissolution proceeds via the creation of pits and the retreat of steps on the surface. In the surface-reaction controlled regime, retreat of steps was found to be anisotropic with two different velocities. From the temperature dependence of the two step velocities, the effective activation energies of dissolution associated with different kink sites were obtained. The study not only provides valuable information on the relationship between the atomic and the site-specific reactivity of the surfaces, but also quantitatively demonstrates the morphological variation of the CaCO3(10(1) over bar 4) surface resulting from dissolution.