Laboratory experiments were conducted to investigate the behavior of CO
2 microbubbles (MBs) and the process of CO
2 dissolution under atmospheric pressure by injecting CO
2 MBs into deionized water and groundwater. The number of CO
2 MBs increased dramatically after starting the CO
2 MB generator, thereby increasing the concentration of dissolved CO
2. The concentration of dissolved CO
2 induced by CO
2 MB injection increased approximately four times more rapidly than when CO
2 was bubbled. The concentration quickly reached a maximum value which coincides with the theoretical saturation concentration of CO
2(aq) solution. Larger CO
2 bubbles were injected after the CO
2(aq) solution became saturated. The increase in the concentration of dissolved CO
2 was accompanied by reductions in both the pH and the density of (CO
3)
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 CO
2 MB injection, which is a method developed in Japan for geologically storing CO
2.
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