(128b) Kinetic and Mechanistic Studies of Microbial and Chemical Enhancement of Carbon Mineralization

Carbon mineralization is one of the safest methods of sequestering anthropogenic carbon dioxide. It is based on the exothermic reaction between carbon dioxide and the metal ions present in silicate minerals, such as antigorite, to form geologically and thermodynamically stable mineral carbonates. However, several challenges need to be overcome to successfully deploy this technology. In particular, the acceleration of the extremely slow mineral weathering step along with process optimization is essential to ensure economic feasibility as well as overall sustainability. In this study, the effect of various organic chelating agents on the dissolution rate of antigorite was explored to accelerate the weathering rate. First, the chelating agents were produced via the anaerobic digestion of food waste in a microbial reactor. As these catalysts which are enhancing the carbon storage are derived from a waste stream, their employment in the proposed carbon mineralization technology enhances the overall sustainability of the process. Magnesium extracted from antigorite was then reacted with CO₂ to form precipitated magnesium carbonates to mimic commercially available CaCO₃-based filler materials. The effects of various chelating agents, pH, reaction time, and reaction temperature on the mean particle size, particle size distribution, composition, and particle morphological structures of precipitated magnesium carbonates were also investigated.