Producing amorphous calcium carbonate using waste Ca-rich solution generated through the bio-leaching of slag

Abstract

This study presents a new method for treating waste Ca-rich solutions (WCS), from which amorphous calcium carbonate (ACC) nanoparticles, an industrial product in high demand, are produced. The distinctive feature of this method is the use of tannic acid (TA) as a surfactant, employing a CO2 bubbling method under ambient conditions. By modulating the concentration of TA, the morphology and crystallization of the generated CaCO3 nanoparticles can be effectively controlled. Experimental results reveal that with increasing TA dosage, the crystallinity of CaCO3 decreases until an amorphous phase is obtained. The crystallization of ACC in solution was completely inhibited when TA was added at a concentration of more than 1%. Therefore, the proposed method provides a new strategy for the efficient preparation of ACC from WCS.