Temporal evolution of dissolution kinetics of polycrystalline calcite

Abstract

The variability in crystal surface reactivity under identical chemical conditions is responsible for a significant intrinsic reaction rate variation. Such variability is quantified using rate maps of reacting surfaces and rate spectra as a statistical concept. In this study, we exemplify the existence and the temporal variability of multiple dissolution rate contributors that combine to an overall rate of dissolving polycrystalline calcite. At least three different high rate contributors control the overall dissolution rate and show no steady state behavior over a reaction period of 10 hours. We conclude that the data about spatial and temporal rate evolution combined with information about crystal size, orientation, and grain boundaries provide constraints for the prediction of porosity pattern in polycrystalline materials. We discuss the density and distribution of surface kink sites as the critical parameter controlling the observed rate variability. Rate spectra measurements of crystal corner, edge, and face surface portions substantiate this conclusion.