Issue 19, 2020

Carbon dioxide, bicarbonate and carbonate ions in aqueous solutions under deep Earth conditions

Abstract

We investigate the effect of pressure, temperature and acidity on the composition of water-rich carbon-bearing fluids under thermodynamic conditions that correspond to the Earth's deep crust and upper mantle. Our first-principles molecular dynamics simulations provide mechanistic insight into the hydration shell of carbon dioxide, bicarbonate and carbonate ions, and into the pathways of the acid/base reactions that convert these carbon species into one another in aqueous solutions. At temperatures of 1000 K and higher, our simulations can sample the chemical equilibrium of these acid/base reactions, thus allowing us to estimate the chemical composition of diluted carbon dioxide and (bi)carbonate ions as a function of acidity and thermodynamic conditions. We find that, especially at the highest temperature, the acidity of the solution is essential to determine the stability domain of CO2vs. HCO3−vs. CO32−.

Graphical abstract: Carbon dioxide, bicarbonate and carbonate ions in aqueous solutions under deep Earth conditions

Supplementary files

Article information

Article type
Paper
Submitted
23 dec 2019
Accepted
10 feb 2020
First published
11 feb 2020

Phys. Chem. Chem. Phys., 2020,22, 10717-10725

Carbon dioxide, bicarbonate and carbonate ions in aqueous solutions under deep Earth conditions

R. Dettori and D. Donadio, Phys. Chem. Chem. Phys., 2020, 22, 10717 DOI: 10.1039/C9CP06904F

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