Enhanced heavy metal immobilization in cementitious materials through CO2 mineralization: A kinetic analysis and physicochemical evolution

The leaching of heavy metals (HMs) from industrial solid waste during its treatment and utilization has garnered extensive attention within the scientific community. The incorporation of cementitious materials to both consume waste and immobilize HMs within the construction sector is a promising strategy. Traditional suppression techniques, employing additives, incur higher costs and may adversely affect the mechanical performance of cement. This research introduces a CO2 mineralization technology synergistically enhancing the immobilization of HMs, which inhibiting the leaching channels in cement-based materials and strengthening the chemical chelation of HMs, thereby suppressing their leaching. The results indicated that the cementitious materials, with a carbonation rate of 10 %-12 %, demonstrated enhanced physical adsorption and chemical chelation capabilities, achieving a 98 % reduction in Pb leaching and a decrease of over 50 % for Mn. Conversely, the post-mineralization reduction in free Ca2+ ions adversely affected the immobilization of soluble HMs like Cr (VI). Overall, this study aimed to enhance the efficacy of current methods for utilizing solid waste and sequestrating HMs whilst simultaneously pioneering innovative concepts for the mineralization application of cementbased materials.