Interfacial equilibrium and mass transfer from liquid CO2 disks through hydrate films

Dissolution behavior of CO2 in water is a key factor in the ocean sequestration of CO2 in deep sea. Studies have been reported on the mass transfer of CO2 into water through interfacial hydrate layer in convective conditions. Coupled with convective flows, such studies provide limited information on the mass transfer resistance at the interface. In the present study, liquid CO2 was injected into stagnant water to form disks at the center of a disk-like void in a deep sea condition (278 K, 20.0 MPa) and the decreasing radii of disks were photographed with a digital camera. The radius change of the CO2 disk was compared with moving boundary numerical solutions for diffusive dissolutions. The water side of the interfacial hydrate layer was found in equilibrium with aqueous phase and the slower dissolution in hydrate forming conditions is due to the decreased solubility. These findings are in accordance with previous studies in convective conditions.