Specific surface area and particle size of calcium carbonate precipitated by carbon dioxide microbubbles

Previously, it was found that precipitating CaCO3 through the carbonation route by bubbling carbon dioxide using a microbubble generator (MBG), as opposed to a conventional bubble generator, reduces the acquisition time. However, the physical properties of the precipitated CaCO3 (polymorph:calcite) using MBG have not been clarified. The physical properties of CaCO3 determine its usefulness in diverse fields. Therefore, this study investigated the specific surface area and size of primary and secondary calcite particles obtained using MBG. These properties were found to be affected by the Ca(OH)2 concentration, CO2 injection rate, and electrolyte dose in the suspension supplying the calcium ions. Comparison with control experiments using a conventional bubble generator showed that the particles obtained using MBG are smaller and have a greater specific surface area. The fine calcite particles with large specific surface area obtained by the additive-less precipitation using MBG are expected to be applied to the removal of acidic gas, such as sulfur dioxide, and as a paper making filler. The low cost and high CO2 consumption efficiency afforded by the MBG also make it promising for carbon capture and utilization.

► Calcite is precipitated via the carbonation route using a microbubble generator. ► Calcite particles with large specific surface area and small size are obtained. ► The proposed method is applicable for carbon capture and utilization (CCU). ► The precipitated calcite particles would be economically profitable. ► Their quality will be sufficient for acidic gas removal and paper making filler.