Enhanced mineral carbonation on surface functionalized MgO as a proxy for mine tailings

Abstract

The escalating demands of industrialization and development underscore the necessity for an efficient and scalable carbon capture and storage (CCS) methodology. Mineral carbonation of MgO presents itself as a promising solution due to its considerable theoretical capacity for CO₂ adsorption. However, the sluggish kinetics of the carbonation process pose a significant challenge. Consequently, a comprehensive understanding of the structural and chemical alterations occurring during carbonation is imperative for material design. In this study, we conduct a thorough structural and chemical investigation of the MgO (sourced from different mine tailings) carbonation process using electron microscopic techniques. Our findings demonstrate that treating MgO with polar solvents enhances its degree of carbonation significantly, offering a promising avenue for improvement. Moreover, we observe a particle size dependency in MgO carbonation and note that the inclusion of additional materials, such as Si-based compounds, further accelerates the carbonation. Density functional theory (DFT) calculations provide insight into surface functionalization as a result of solvent treatment and its mechanistic effect on the origin of the enhanced carbonation of polar solvent-treated MgO, revealing a stronger interaction between CO₂ and the treated MgO (100) surface as compared to the non-polar solvent treated surfaces. These discoveries showcase an alternative approach for enhancing MgO carbonation, thereby offering a potential method for sequestering atmospheric CO₂ more effectively using mine waste rich in MgO.