Dissolution of CO₂ From CO₂ Drops in Simulating Experiments of CO₂ Ocean Storage

The dissolution of Carbon Dioxide (CO₂) from CO₂ drops covered with CO₂ hydrate films under the conditions simulating the deep-sea environment was investigated with a large high-pressure tank. The lowering of pH due to CO₂ dissolution was measured for two temperature regions. In the same temperature region, pH lowering at higher position above the bottom of the tank was much smaller than that at lower position. It implies that while the dissolved CO₂ is diffused through water in the tank, the difference in CO₂ concentration occurs between both measuring points. On the other hand, pH lowering in the lower temperatures was smaller than that in the higher temperatures at the same measuring point. The difference in pH change between both temperature regions agreed with the temperature dependency in the solubility of CO₂ hydrate and the dissolution rate of a CO₂ droplet with a CO₂ hydrate film.