CO₂ Activation of Wollastonite Cementitious Material Based on the Mineralization-Desorption of Potassium Glycine Absorbent

This study presents a new CCUS method, which uses potassium glycine (KG) solution to capture CO2 derived from industrial flue gases and sequesters the CO2 in wollastonite by mineralization-desorption, thus achieving the cyclic regeneration of the KG absorbent and the activation of wollastonite. The results confirm the favorable absorption capacity and desorption efficiency of this method, with the CO2 cyclic capacity of the KG absorbent up to 0.47 mol/mol. The presence of CO2-rich KG significantly improved the activity of carbonated wollastonite, resulting in decreased critical and median pore diameters and a 25–30% increase in the compressive strength of cement paste. Two mechanisms were proposed to explain this phenomenon: the metastable amorphous calcium carbonate and vaterite in KG-carbonated wollastonite enhance the microstructure of the cement matrix by dissolution–recrystallization and the carbamate in CO2-rich KG solution participates in the precipitation of calcite, forming the inorganic–organic composites with higher thermal stability and better mechanical performance.