Amine-Assisted Accelerated Mineral Carbonation of Steel Slag for CO ₂ Capture and Sequestration

This study investigates an integrated CO2 capture and mineralization approach using industrial waste and calcium-based precursors. The first strategy involves directly mineralizing CO2 by reacting with alkaline-rich industrial byproducts such as Steel Slag, cement kiln dust, and fly ash. This reaction results in stable carbonate minerals with improved material properties, suitable for blending in cement as a supplemental cementitious material, construction, and soil stabilization. This method not only reduces CO2 emissions but also repurposes industrial waste, contributing to ecoefficient carbon capture and utilization (CCU). The second strategy examines the use of monoethanolamine (MEA) and methyldiethanolamine (MDEA) as CO2 capture agents to expedite the mineralization of calcium oxide (CaO), magnesium oxide (MgO), and other silicate compounds. Bicarbonate ions generated during CO2 absorption enhance carbonate precipitation, with variables such as solvent concentration, temperature, and reaction time affecting the extent of mineralization. Optimal conversion was achieved at 353.0 K with a 30.0 wt % aqueous MDEA solution over half an hour reaction period, yielding mineralization extents of 71.16% for CaO and 99.63% for Slag. X-ray diffraction analysis indicated that calcite was the dominant phase in CaO-based mineralization, while a mixture of calcite, aragonite, and vaterite was observed in Slag-derived products. These results demonstrate the potential of MEA and MDEA in facilitating CO2 capture with inherent aqueous-phase regeneration, presenting a promising approach for sustainable carbon sequestration and industrial waste utilization.