The crystallization behavior of calcium carbonate in ethanol/water solution containing mixed nonionic/anionic surfactants

Crystallization of CaCO3 was performed in an ethanol/water solution containing Pluronic F127 (EO97PO68EO97) and sodium dodecyl sulfate (SDS). The effects of the ethanol/water volume ratio, concentration of surfactants, and aging temperature (30–90 °C) on the morphology and polymorphs of CaCO3 were investigated using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The presence of both F127 and SDS in solution favored the vaterite phase of CaCO3. A binary calcite–vaterite mixture and a ternary calcite–vaterite–aragonite mixture were produced at low (< 60 °C) and high temperatures, respectively. Spherical, plate-like, flower-like, and rod-like crystals were obtained at different ethanol/water volume ratios. Controllable synthesis of nearly pure flower-like vaterite and rod-like aragonite can be realized by adjusting the ethanol/water volume ratio. The formation mechanism of flower-like CaCO3 crystals is discussed.