Laboratory Experiments Based on CO₂ Microbubble Sequestration

Characteristics of CO₂ Dissolution by CO₂ Microbubbles

Abstract

Laboratory experiments were conducted to investigate the behavior of CO₂ microbubbles (MBs) and the process of CO₂ dissolution under atmospheric pressure by injecting CO₂ MBs into deionized water and groundwater. The number of CO₂ MBs increased dramatically after starting the CO₂ MB generator, thereby increasing the concentration of dissolved CO₂. The concentration of dissolved CO₂ induced by CO₂ MB injection increased approximately four times more rapidly than when CO₂ was bubbled. The concentration quickly reached a maximum value which coincides with the theoretical saturation concentration of CO_2(aq) solution. Larger CO₂ bubbles were injected after the CO_2(aq) solution became saturated. The increase in the concentration of dissolved CO₂ was accompanied by reductions in both the pH and the density of (CO₃)^2—. In addition, the high concentration of the CO_2(aq) solution was maintained for a relatively long time.
These experimental results will assist in developing a practical system for CO₂ MB injection, which is a method developed in Japan for geologically storing CO₂.