The removal of CO2 from the earth’s atmosphere is a key strategy for the mitigation of global warming, with the sequestration of CO2 from seawater, which contains CO2 at 150 times its concentration in air, providing a promising alternative to traditional air-capture based approaches. While proposed designs generally rely on the mineralization of CO2 into carbonate, knowledge of the fundamental molecular processes involved in such an approach is limited. We carry out multi-level quantum mechanical simulations, harnessing both ab-initio correlated electronic structure theory, as well as density functional theory molecular dynamics simulations to elucidate the mineralization pathways of carbonates with Mg2+ and Ca2+ cations. Investigation of the dehydration dynamics of the two metal cations in aqueous solution shows significant differences in their coordination behavior and reveals that it may be modulated by the concentration of hydroxide. Further simulations are performed in the presence of carbonate anions to elucidate the dynamics of CO32- coordination to Mg2+ and Ca2+. Insight from these studies may aid in assessing the viability of carbonate formation for CO2 sequestration and provides valuable understanding for the design of large-scale mineralization facilities.

Understanding the dynamics of Mg and Ca carbonate formation in aqueous solution from multi-level electronic structure simulations

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