Formation of Amorphous Calcium Carbonate and Its Transformation Mechanism to Crystalline CaCO3 in Laminar Microfluidics

Abstract

For traditional experimental methods, the dynamic formation and transformation of amorphous calcium carbonate (ACC) are hard to be captured due to its metastability and ease of transforming rapidly to the more stable phase. The emergence of microfluidic technology provides an effective approach on that issue, thus attracting widespread researchers interest in crystallization research. In this study, based on laminar microfluidics, we demonstrate a microfluidic approach toward the study of the formation and transformation of ACC. Through the control of velocity and concentration of CaCl2 and Na2CO3, the crystallization process was observed on chip under the microscope. We show by in situ confocal Micro Raman spectroscopy and theoretical calculation based on fluid dynamics simulation that the phase transformation pathways are different under the different supersaturation level in laminar microfluidics. ACC doesn't always appear in the crystallization process, when the supersaturation above the critical supe...