Molecular Dynamics of Carbon Sequestration via Forming CO₂ Hydrate in a Marine Environment

The current situation of global warming requires immediateattentiondue to the excessive accumulation of CO2 in the atmosphere.Given that the hydrate generation process can trap CO2 moleculesin the lattice of water molecules, it could be a promising strategyto store CO2 in the ocean as hydrates. In this paper, moleculardynamics (MD) simulations are used to investigate the behavior ofCO(2) hydrate growth in salt-containing electrolyte solutions,and the mechanism of the effect of thermodynamic conditions and saltions on hydrate growth is explored. The simulation results show thata proper subcooling can promote the hydrate growth process, yet thefluctuation of the hydrate growth rate is still significant in thepresence of salt ions. Higher temperatures and salt ions both inhibitthe formation of hydrogen bonds between water molecules, reducingthe possibility of cage structure formation. Notably, the saline environmentsenhanced the competition for water molecules between hydrate cagesand salt ions, increasing the proportion of empty cages. The selectivityof CO2 molecules to enter different cages is influencedby both the temperature and salt ions; higher temperatures and thepresence of salt ions make it more difficult for CO2 moleculesto enter the smaller 5(12) cages. The results of the studyprovide insights into the mechanism of CO2 hydrate generationin seawater at the microscopic level, guiding the future realizationof CO2 sequestration technology via forming hydrate inmarine environment.