Atmospheric CO₂ Sequestration in Seawater Enhanced by Molluscan Shell Powders

Abstract

Carbon capture, utilization, and storage (CCUS) are widely recognized as a promising technology for mitigating climate change. CO 2 mineralization using Ca-rich fluids and highconcentration CO 2 gas has been studied extensively. However, few studies have reported CO 2 mineralization with atmospheric CO 2 , owing to the difficulty associated with its low concentration. In seawater, the biomineralization process promotes Ca accumulation and CaCO 3 precipitation, assisted by specific organic matter. In this study, we examined the conversion of atmospheric CO 2 into CaCO 3 in seawater using shell powders (Pinctada fucata, Haliotis discus, Crassostrea gigas, Mizuhopecten yessoensis, Turbo sazae, and Saxidomus purpurata). Among the six species, the shell powder of S. purpurata showed the highest rate of CaCO 3 formation and recovery of CaCO 3 . NaClO treatment test revealed that the organic matter in the shells enhanced the CO 2 mineralization. All materials used in this study, including atmospheric CO 2 , seawater, and shells, are economically feasible for large-scale applications. Using shell powder for CO 2 mineralization in seawater embodies an innovative technological advancement to address climate change.

The Future of CO2 Geological Sequestration: An Overview of Mineralization in Aqueous and Supercritical States

“…Conventional chemical mineralization methods for CO 2 sequestration are impeded by thermodynamic constraints and mass transfer limitations, leading to suboptimal sequestration efficiencies . In contrast, biomineralization markedly lowers the activation energy for the reaction via the synergistic effects of proteins within organisms, thus enhancing the mineralization rate . This process is prevalent in nature, as evidenced by molluscs, echinoderms, cnidarians, algae, and the stratigraphic microbiota and archaea in oceans, which transform CO 2 into biominerals.…”