Influence of NaCl on mineral carbonation of CO ₂ using cement material in aqueous solutions

The carbonation of cement materials in NaCl solution was evaluated at various NaCl concentrations (0-2.0M). Leaching and carbonation tests were conducted on slurry-mixed ordinary Portland cement (OPC) with NaCl solutions at a solid to liquid ratio of 50g/l in a Teflon reactor under ambient temperature and pressure conditions. After 24-h leaching, the pH of the slurry decreased with increasing NaCl concentration, whereas the Ca concentration slightly increased. The C-S-H content in the reacted samples after 24-h leaching increased in the presence of NaCl. After the carbonation tests, the CaCO ₃ content in the reacted samples increased by 7.5-18.4wt%, whereas the C-S-H content decreased by 7.1-33.0wt% in the NaCl solutions. The particle size of the precipitated CaCO ₃ appeared to be decreased as the NaCl concentration was increased to 1M, but increased as the NaCl concentration was further increased to 2M.