Carbon dioxide, bicarbonate and carbonate ions in aqueous solutions under deep Earth conditions. Issue 19 (27th February 2020)

• Record Type: Journal Article
• Authors: Dettori, Riccardo; Donadio, Davide
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 19(2020)
• Page Start: 10717
• Page End: 10725
• Publication Date: 2020-02-27
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c9cp06904f
• Languages: English
• ISSNs: 1463-9076

Abstract

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. 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 CO2 vs. HCO3 − vs. CO3 2− .