Pitfalls in the Measurement of the True Dissolution Kinetics of Soft Minerals

The study of dissolution can face pitfalls at all length-scales, other phenomena being able to blur the investigated reaction. We present here two situations where an a posteriori analysis of the experimental results enables recovery of the true dissolution behavior free from external influences. In standard solution chemistry dissolution experiments, the measured dissolution rate is the result of a combination of the reaction kinetics and of mass transport due to the convection of the flowing solvent. We show here how to circumvent this mass transport contribution to recover the true dissolution rate constant. Moreover, in AFM dissolution experiments, the stress applied by the tip to the surface modifies the velocity of the atomic steps, the migration of which is at the origin of dissolution. We show here how to obtain stress-free, true dissolution velocities.