Unlocking high carbonation efficiency: Direct CO2 mineralization with fly ash and seawater

Direct CO2 mineralization using fly ash is a promising technology to achieve CO2 sequestration. Seawater's abundance and calcium-rich composition make it an attractive substitute solution for CO2 sequestration. However, there have been limited studies conducted so far, and the mineralization mechanism remains unclear, which has constrained its industrial application potential. Here we utilized low CaO-content fly ash in combination with seawater to perform direct CO2 mineralization under ambient conditions, achieving a remarkable carbonation efficiency of 94.8 %. Upon scrutinizing the carbonate parameter evolution, we identify a crucial pH range (8.2 ∼ 10.4) that enhances calcium elution efficiency, leading to heightened carbonation efficiency. The involvement of Mg(OH)2 within this pH range influences CaCO3 precipitation kinetics and crystalline phase. This innovative approach holds promise for carbon sequestration and presents a valuable contribution to sustainable CO2 utilization strategies.