Calcium carbonate (CaCO3) is among the most abundant mineral in sediments and biomaterials, and greatly influences the efficiency of many engineered systems. Various additives have been found to achieve elegant control of the size, morphology, and function of CaCO3. Often the role of an additive in one specific CaCO3 formation stage is highly emphasized while its roles in all stages including nucleation, growth, and Ostwald ripening are not elucidated. In particular, their roles in each stage are not clearly differentiated. Here, we used in situ X-ray scattering techniques to delineate sulfate’s impacts on the nucleation stage, growth stage, and Ostwald ripening stage of heterogeneously formed CaCO3 on quartz at different saturations (3.3 – 4.6) and sulfate concentrations (1 – 10 mM). In the nucleation stage, we quantified the changes in interfacial energy and bulk energy and found that both contribute significantly to decrease nucleation rates. Next, we found that the incorporated and adsorbed sulfate can promote the growth and passivate the small nuclei surface dissolution, inhibiting Ostwald ripening. Importantly, although sulfate inhibited nucleation and Ostwald ripening, it promoted growth. Our work highlights the importance of separately evaluating an additive’s effect on each CaCO3 formation stage. Furthermore, our results provide insights into additive-controlled CaCO3 formation, biomineral formation, and scaling control.

Roles of sulfate in the nucleation, growth, and Ostwald ripening of CaCO3 on quartz

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.