A free boundary problem for CaCO3 neutralization of acid waters

In this paper we propose a mathematical model for the reaction kinetics of CaCO3 in an acid solution. In particular we study the system in planar geometry showing that the problem is a free boundary problem with an intrinsic multi-scale structure. We rescale the problem and show how the equations simplify according to the specific scale considered. We also present a result that allows us to calculate the diffusivity coefficient from the experimental measurements of pH.