US team makes advance for direct air capture

One approach to DAC is to utilise liquid solvents and solid sorbents to chemically absorb CO2 from air streams that can later be processed to desorb and recover CO2.

Recently published research from a team at the US Department of Energy’s Oak Ridge National Laboratory (ORNL) focused on the foundational steps of carbon dioxide sequestration using aqueous glycine, an amino acid with absorbent qualities. By combining a series of advanced computational methods, the scientists investigated less-explored dynamic phenomena in liquid solutions related to the rate at which carbon dioxide can be captured. 

“Chemical reactions in water are complicated, especially when the motion of water molecules plays a big role,” said Santanu Roy, who designed the computational investigation with colleague Vyacheslav Bryantsev. “Understanding these dynamic interactions, known as nonequilibrium solvent effects, is essential to getting the full picture of how reactions work and how fast they happen.”

The researchers found that when examining the rate at which carbon dioxide is absorbed, focusing on the free energy barrier - the energy threshold that must be overcome for a system to transition from one state to another - is an oversimplification and incomplete approach that can lead to an inaccurate understanding of reaction kinetics.