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

Abstract

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.