ANISOTROPIC DISSOLUTION AT THE CACO3(10(1)OVER-BAR4)-WATER INTERFACE

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