IMIS - Marine Onderzoeksgroepen

CO₂ mineralization which involves the reaction of CO₂ with alkaline earth metal cations to form carbonates, is a promising pathway that could be crucial for combating global warming via long-term CO₂ utilization and storage. However, due to the large abundance of natural calcium carbonate (CaCO₃) and advanced milling techniques, micron-ranged CaCO₃ is conventionally produced via the top-down method because it is more economically attractive than mineralization or precipitation unless particles with functional properties are generated so that a higher product value is achieved. In this study, inspired by the natural formation of nacre, which is produced naturally via controlled crystallization (using environmental CO₂) in the marine environment, we produce CaCO₃ particles with different morphologies via single-step CO₂ capture and mineralization. We used a gas diffuser reaction setup to bubble CO₂ in liquid media containing CO₂ absorption promotor, water-soluble polymer, and surfactant as crystal growth modifiers, and Ca²⁺ to form functional CaCO₃. First, different inorganic and organic CO₂ absorption promoters and their combinations were investigated for their effectiveness on Ca²⁺ conversion to CaCO₃. Ca²⁺ conversion and pH of the reaction system with various concentrations of CO₂ absorption promoters were monitored every 5 min. Second, the effect of the polymer combined with different concentrations of surfactant on CaCO₃ properties was studied. It was found that the combination of triethanolamine and ammonium hydroxide as absorption promotors results in 53.2% Ca²⁺ conversion into stable CaCO₃ particles within 5 min of CO₂ bubbling. Absorption promotors themselves could not regulate the particle shape; however, with increasing concentrations, smaller particles agglomerated to form bigger rhombohedral particles. Polymer and surfactant-mediated mineralization of CO₂ produces spherical and hollow, stable calcite particles that could serve as dies, heavy metal adsorbents, supports to catalysts, functional composite fillers, etc.