Experimental Evaluation of CO2 Sequestration Through Carbonation of Magnesium- and Calcium-Rich Minerals

Summary Mineral carbonation offers a stable, safe, and potentially scalable solution for long-term carbon storage. In this study, we introduce an integrated experimental methodology to investigate the carbon uptake behavior of four abundant minerals—olivine, dolomite, gypsum, and magnetite—under atmospheric pressure. These minerals, selected for their magnesium-, calcium-, and iron-bearing compositions, were exposed to carbon dioxide (CO2) under varied heating rates and end temperatures to evaluate their suitability for surface-level carbon capture applications. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that olivine and dolomite exhibited significant carbon uptake, while gypsum and magnetite showed poorer reactivity under the tested conditions. Carbonation behavior was found to be highly dependent not only on mineral type but also on the thermal exposure profile. Dolomite performed best at moderate heating rates and lower end temperatures (100°C), whereas olivine required higher end temperatures (200°C) and slower heating rates to achieve maximum uptake. These optimal temperatures (100–200°C) match those of many industrial emission sources, confirming the practical relevance of this approach. In the presence of an aqueous phase, particularly brine with high ionic strength, carbon uptake significantly increased up to 14.84 ± 4.7 mg for dolomite and 7.70 ± 1.53 mg for olivine per 100 mg of sample. Scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS) (SEM-EDS) analysis revealed that carbonation altered the minerals‘ surface morphology and surface void space in opposing ways: Olivine developed increased surface void space, while dolomite underwent surface compaction. A strong correlation was established between carbon uptake and void space change. Fourier transform infrared (FTIR) spectroscopy analysis confirmed surface-level carbon uptake, with diagnostic peaks near 2350 cm-1 observed in both minerals under optimal conditions. Naturally occurring minerals can rapidly capture CO2 under ambient pressure and at moderate temperatures. Therefore, we also present a concept for using powdered minerals in modular filter units at emission sources such as vehicle exhausts and industrial chimneys. This approach captures CO2 at the point of release, avoiding post-capture separation and transport. The mineral-specific structural responses to carbonation increased void space in olivine and compaction in dolomite and helped resolve conflicting reports in the literature. These results provide a basis for developing decentralized and low-energy carbon capture technologies.