Dettori Riccardo, Donadio Davide
Department of Chemistry, University of California Davis, One Shields Avenue, Davis, California 95616, USA.
Phys Chem Chem Phys. 2020 May 21;22(19):10717-10725. doi: 10.1039/c9cp06904f. Epub 2020 Feb 27.
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 COvs. HCOvs. CO.
我们研究了压力、温度和酸度对富含水的含碳流体组成的影响，这些流体所处的热力学条件与地球深部地壳和上地幔相对应。我们的第一性原理分子动力学模拟为二氧化碳、碳酸氢根和碳酸根离子的水合壳，以及在水溶液中将这些碳物种相互转化的酸碱反应途径提供了机理洞察。在1000K及更高的温度下，我们的模拟能够对这些酸碱反应的化学平衡进行采样，从而使我们能够估计稀释的二氧化碳和（bi）碳酸根离子的化学组成随酸度和热力学条件的变化情况。我们发现，特别是在最高温度下，溶液的酸度对于确定CO与HCO与CO的稳定性域至关重要。
