Kinetics of Mineral Dissolution and Growth as Reciprocal Microscopic Surface Processes Across Chemical Driving Force

Abstract

With the introduction of nanoscale in situ imaging technologies, a new understanding of the microscopic processes that underlie widely used empirical ‘rate laws’ is emerging. This review summarizes recent findings that the kinetics of mineral dissolution can be explained by equivalent, but inverse, microscopic processes that have been used to describe growth. Like growth, dissolution occurs by multiple microscopic processes — each with an empirical and mechanism‐based rate law and a unique dependency upon chemical driving force. As undersaturation departs from equilibrium, dissolution rates are first dominated by the process of step propagation, followed by generation of steps at dislocation sources, and then by nucleation of vacancy islands. Interplays between step edge energy, temperature and other parameters determine if/when minerals express all of these processes across driving force. Net rates that are measured from reactor studies to give power law dependencies upon driving force describe the sum of these processes. Central to understanding these relations is the pivotal roles of process‐specific energy barriers to reactions at different surface structures and defects of minerals and materials.