Modeling Closed Equilibrium Systems of H2O-Dissolved CO2-Solid CaCO3

Toomas Tenno; Kalev Uiga; Alexsey Mashirin; Ivar Zekker; Ergo Rikmann

doi:10.1021/acs.jpca.7b00237

Modeling Closed Equilibrium Systems of H₂O-Dissolved CO₂-Solid CaCO₃

J Phys Chem A. 2017 Apr 27;121(16):3094-3100. doi: 10.1021/acs.jpca.7b00237. Epub 2017 Apr 12.

Authors

Toomas Tenno¹, Kalev Uiga¹, Alexsey Mashirin¹, Ivar Zekker¹, Ergo Rikmann¹

Affiliation

¹ Institute of Chemistry, University of Tartu , 14a Ravila St., Tartu 50411, Estonia.

PMID: 28281760
DOI: 10.1021/acs.jpca.7b00237

Abstract

In many places in the world, including North Estonia, the bedrock is limestone, which consists mainly of CaCO₃. Equilibrium processes in water involving dissolved CO₂ and solid CaCO₃ play a vital role in many biological and technological systems. The solubility of CaCO₃ in water is relatively low. Depending on the concentration of dissolved CO₂, the solubility of CaCO₃ changes, which determines several important ground- and wastewater parameters, for example, Ca²⁺ concentration and pH. The distribution of ions and molecules in the closed system solid H₂O-dissolved CO₂-solid CaCO₃ is described in terms of a structural scheme. Mathematical models were developed for the calculation of pH and concentrations of ions and molecules (Ca²⁺, CO₃^2-, HCO₃^-, H₂CO₃, CO₂, H⁺, and OH^-) in the closed equilibrium system at different initial concentrations of CO₂ in the water phase using an iteration method. The developed models were then experimentally validated.