Modeling Calcite Dissolution in a Rotation Disk Reaction Vessel

Speaker: Camelia Yazdani

The carbonate system is one of the most complex and widely present chemical systems in the nature. The kinetics of calcite dissolution/ precipitation in CO2- water is also a long-standing problem for numerous models and research projects; because of the important role, it plays in so many natural and industrial processes from karst formation to oil sand extraction. In this talk, I will discuss the underlying chemistry of the system and the hydrodynamic condition of the environment; the ultimate goal of this work is to estimate the rate of dissolution as a function of calcium concentration, which depends on the ion composition of bulk solution. The wide variability in the reaction rates over many orders of magnitude allow for modeling the slowly evolving species with a set of convective-reaction-diffusive equations, then equilibrium conditions are used to solve for the fast reacting species. The dissolution surface defines a moving boundary, which is governed by a Stefan condition. Analyzing the effect of changes CO2 partial pressure on the system and dissolution surface reactions leads to identifying regions that are distinct for the dominate existing ion species and are affected by changes in partial pressure, temperature, and initial H+ concentration. The purposed model has the advantage of reproducing the observed behavior as an interconnected system between the dissolving surface and the bulk without the need to introduce additional reactions occurring at the reacting surface.