Valorization of Construction and Demolition Wastes via Organic Acid Mediated Calcium Recovery and CO₂ Mineralization with Regenerable Sodium Glycinate Solvent: A Pathway toward Circularity in the Construction Industry

Concrete is an essential material used in construction, and its manufacturing accounts for 8.6% of anthropogenic CO2 emissions. Annually, around 3 Gt of construction and demolition waste is generated on a global scale. Therefore, it is essential to harness construction waste as a resource for coproducing higher-value products for decarbonizing the cement and construction industry while harnessing CO2 emissions and regenerable acids and solvents. In this work, the challenge of recovering calcium and producing solid calcium carbonate from construction and demolition waste (CDW) is addressed by first dissolving CDW using organic acids such as acetic or formic acid followed by using sodium glycinate for capturing and converting CO2 to produce calcium carbonate. The efficacy of using organic acids, such as acetic or formic acid, is contrasted with the use of inorganic acids, such as hydrochloric acid, for CDW dissolution. The results demonstrate that over 90% of calcium is dissolved from CDW into the leachate using organic acids. More than 85% of the dissolved calcium from the purified leachate is recovered as CaCO3 with controlled morphologies using sodium glycinate in batch mode as well as using a continuous vortex-driven Taylor–Couette (TC) reactor. The final solution, rich in glycinate, anions of carboxylic acid, and residual amounts of carbamate, can be separated using commercial anion exchangers, providing a pathway for reuse.