Optimization of CO2 sequestration in alkaline industrial Residues: The enhancement mechanism of saline soil

The global climate crisis is escalating, with climate change caused by the greenhouse effect posing a common challenge for the sustainable development of the environment and economy worldwide. Utilizing alkaline industrial residues for CO2 capture and storage is considered a viable technology. In China, soil salinization is a serious and widespread issue. Saline-alkali soils, characterized by high levels of soluble salts and alkalinity, have the potential to enhance the efficiency of carbonation in alkaline industrial residues. This study conducted carbonation experiments on fly ash, steel slag, and carbide slag. The primary carbonation pathways and reaction mechanisms of these materials were investigated. The particle size, mineralogy, and morphology of the resulting carbonation products were characterized, and the impact of different carbonation pathways on carbonation efficiency and storage capacity was evaluated. Finally, the study, for the first time, analyzed the enhancing mechanism of saline-alkali soil as an additive in the carbonation reaction. The research results indicate that carbonation reaction will change the particle size composition of the material, and the reaction rate of steel slag is lower than that of fly ash and carbide slag. Saline-alkali soil plays a facilitating role in CO2 storage, and it can improve carbonation efficiency of different materials by 4.17% −34.94%, which can effectively reduce the cost of the additive.