Precipitation of calcium carbonate by carbon dioxide microbubbles

Effects of CO2 Bubble Size, CO2 Flow Rate and Calcium Source on the Size and Specific Surface Area of CaCO3 Particles

“…The addition of chemicals such as amines [16][17][18] and ammonia [19][20][21] could enhance the solubility of CO2 by forming complexes. Moreover, changes in the physical properties of a gas bubble, such as decreasing the bubble size, could also increase their solubility under given conditions of atmospheric pressure and temperature [3,10,22]. The strong surface tension of MBs described in Equation (1) causes these results.…”

“…where, d is primary particle size, is SSA, and ρ is density of the particles (in this case 2.71 g/cm 3 for calcite of CaCO3). The novelty of this study is that the size of the CaCO3 particles prepared using the MBG were finer and almost identical in size (~2.6 μm and 22 m 2 /g) regardless of the calcium source, whereas the use of an AD produced coarser CaCO3 particles (~8 μm and less than 17 m 2 /g).…”

“…The CO2 MBs were injected into the 1 L of the suspension at the same flow rates used for the CM method. A detailed experimental scheme for this can be found in another report [3]. Table 1 shows the specifications of the calcium supply materials, and Figure 1 indicates the 70,000× SEM images of the raw materials.…”

“…The impact of these qualities of MBs in increasing the concentration of a gas is different from that of ordinary bubbles (as is evident on breathing into water through a straw). We have reported that a microbubble generator (MBG) precipitated smaller calcium carbonate particles faster than an ordinary air diffuser with 3 cm diameter did [3]. Feng et al [4] also obtained smaller CaCO3 particles by reducing the frit pore size used for CO2 bubbling in a Ca(OH)2 suspension: The carbonate mineralization (CM) method is used to fix CO2 as a carbonate mineral (i.e., CaCO3).…”

“…One typical use of MBs is water purification, achieved by increasing the dissolved oxygen concentration in polluted water. As an extension of the use of MBs to a wider range of applications, the recovery of fine particles [2] and the precipitation of CaCO3 using Ca(OH)2 [3] have been reported. This application is apparently related to a physical property of the MBs not found in ordinary bubbles in liquids, namely that the concentration of a specific gas in a liquid remains higher for longer if the gas is contained in MBs.…”