Influence of Nanobubbles on the Early Stages of Calcium Carbonate Formation

The mineralization process of calcium carbonate (CaCO3) is essential in both environmental and industrial applications, since it is a ubiquitous biomineral and a primary component of scale deposits in hard water systems. In this study, we examine the influence of charged nanobubbles, generated through vortexing ionic solutions (bi-/carbonate buffer at pH 10) with rotating nonmagnetic and magnetic impeller, on the formation of amorphous CaCO3 (ACC). Multi-angle light scattering and zeta potential nanoparticle tracking analysis show that alternating magnetic fields influence the size and charge of nanobubbles created by shear forces in vortexing. The altered nanobubble populations delay the formation of solid ACC by inhibiting the aggregation and coalescence of dense liquid calcium carbonate. We propose colloidal stabilization of the dense liquid intermediate by the nanobubbles along the pathway to solidification. Our findings suggest that magnetically manipulating nanobubble populations is a novel approach to controlling mineral scaling and designing advanced materials. This work highlights the potential role of nanobubbles in affecting mineral formation processes and provides new insights into mineralization control through physical treatment methods.