A novel route to prepare the metastable vaterite phase of CaCO3 from CaCl2 ethanol solution and Na2CO3 aqueous solution

Abstract

Vaterite, the least stable phase among three anhydrous polymorphs of calcium carbonate (CaCO3), was prepared via the reaction between the ethanol solution of calcium chloride (CaCl2) and the aqueous solution of sodium carbonate (Na2CO3), which is named ethanol-calcium method. The effects of aging times and reaction temperatures on the formation of vaterite were investigated. The polymorphs and morphologies were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, and Fourier transform infrared spectroscopy (FT-IR) was used to verify the existence of vaterite. XRD results indicate that the amount of vaterite decreases from 90.4% to 81.4% as increasing in aging times from 0 min to 42 h and decreases from 85.8% to 70.2% as increasing in reaction temperatures from 0 °C to 60 °C. SEM results show that vaterite and calcite as-prepared are their typical morphologies of spherical and rhombohedral, respectively. This research extends the route to prepare the metastable vaterite and provides new insights into its controllable synthesis.