Synthesis of needle-like aragonite using carbonation method: A review

Abstract

The environmental problems caused by CO₂ emissions endanger human lives. Under these circumstances, carbon dioxide capture, utilization, and storage (CCUS) is likely to reduce CO₂ gas emissions with economic advantages. An application of CCUS is the reinforcement of mechanically weak bio-based composite plastics. Needle-like calcium carbonate crystals can potentially reinforce weak plastics. Moreover, the synthesis of calcium carbonate via carbonation can reduce CO₂ emissions. Here, we review the development of synthetic methods for needle-like aragonite (which is a polymorph of calcium carbonate crystals) using a gaseous CO₂ for further development of efficient synthetic conditions and precise control of morphology. Various factors influencing the synthesis of aragonite have been discussed. These include the temperature; degree of supersaturation of CaCO₃; pH; additives; and external stimuli such as high gravity, sound waves, and microbubbles. The estimated elastic moduli of aragonite were anisotropic depending on the crystal direction. This indicated the importance of controlling the long-axis direction of aragonite as a novel reinforcement material.