Shrinkage of liquid CO2 droplets in water

The shrinkage rate of liquid CO2 droplets in water at 3°C was measured by the use of high-pressure vessel placed in a constant-temperature room. The change of the diameter of the droplet was observed at pressures of 28 MPa and 35 MPa using a time-lapse video camera. Bromocresol green was employed as a pH indicator, and was effective in monitoring the profile of carbonic acid distribution. When a droplet of liquid CO2 was injected, CO2 hydrate immediately formed and covered the surface of the droplet. The diameter of the liquid CO2 droplet reduced gradually at a rate of 5.0 × 10−7 m/s. It is predicted, from the viewpoint of ocean CO2 sequestration, that a thin film of hydrate will form at the interface of sea water and liquid CO2, and that the hydrate film will greatly control the dissolution of CO2 into sea water.