Enhancing sustainable utilization of iron-based alkaline solid wastes for carbon mineralization: Insights into CO2 transport and adsorption dynamics

Iron-based alkaline solid wastes provide substrates for carbon mineralization, addressing global warming. However, the mechanisms of CO₂ transport and adsorption within their porous structures are not fully understood. Using advanced grand canonical Monte Carlo (GCMC) methods, this study explores CO₂ transport and adsorption in iron-based alkaline wastes under different humidity conditions. The results show that FeO and Fe₂O₃ reduce the CO₂ adsorption capacity in calcium hydroxide (CH) nanopores, a key component of these wastes. The presence of iron-based solids causes inhomogeneous porewater distribution, diminishing CO₂ dissolution and adsorption on the gas-liquid interface. By analyzing adsorption energy and CO₂ diffusion coefficients, we found that iron-based porous systems have lower CO₂ transport efficiency and storage capacity, highlighting their limited carbonation potential. The weak CO₂-surface interactions in these wastes are identified as the primary challenge to improving carbon mineralization. These findings provide crucial insights for enhancing the sustainable use of iron-based alkaline wastes.