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

Area of Science:

• Geochemistry
• Environmental Science
• Water Chemistry

Background:

• Limestone bedrock, primarily calcium carbonate (CaCO3), is prevalent globally, influencing water chemistry.
• Equilibrium processes involving dissolved carbon dioxide (CO2) and CaCO3 are crucial in biological and technological systems.
• CaCO3 solubility is low but significantly influenced by dissolved CO2 levels, impacting water parameters.

Purpose of the Study:

• To develop mathematical models for calculating pH and ion concentrations in a CaCO3-water-CO2 system.
• To describe the distribution of ions and molecules within this closed equilibrium system.
• To validate the developed models through experimental testing.

Main Methods:

• Development of mathematical models using an iteration method.
• Description of ion and molecule distribution using a structural scheme.
• Experimental validation of the developed mathematical models.

Main Results:

• Models accurately calculate pH and concentrations of various ions and molecules (Ca2+, CO32-, HCO3-, H2CO3, CO2, H+, OH-) in equilibrium.
• The models demonstrate the impact of varying initial CO2 concentrations on water chemistry.
• Experimental validation confirmed the predictive accuracy of the developed models.

Conclusions:

• The study provides a robust mathematical framework for understanding CaCO3 solubility and its impact on water chemistry.
• The developed models are valuable tools for predicting ground- and wastewater parameters.
• This research contributes to the understanding of geochemical processes in carbonate-rich environments.