On the carbonation of brucite: Effects of Mg-acetate on the precipitation of hydrated magnesium carbonates in aqueous environment

The role of organic ligands on the formation of hydrated magnesium carbonates (HMCs) has been remaining unclear. This work reports insights into the effects of Mg-acetate on the carbonation of brucite including the kinetics of reaction, the precipitation of different HMCs, and reaction mechanisms. We found that the organic ligand increases the kinetics of brucite's carbonation and alter the formation and conversion of HMCs. A relatively unknown phase (i.e., giorgiosite) precipitates in the presence of Mg-acetate with nanowire morphology. With the presence of acetate ligand, nucleation sites formed after the breakdown of Mg-acetate complexes and be replaced by the Mg–CO₃ bonds. These sites act as a sink for Mg²⁺ to grow crystals and prevent the passivation layer of HMCs on brucite's surface. Findings reported here can enable an approach to steer pore solution chemistry in the HMC-based binder for better reaction degree, durability, and mechanical properties.