Preparation and formation mechanism of calcium carbonate hollow microspheres

Calcium carbonate (CaCO3) hollow microspheres of calcite polymorph were successfully obtained by using so-dium carbonate (Na2CO3) and calcium nitrate (Ca(NO3)(2)) in the presence of poly (acrylic acid) (PAA) and sodium dodecyl sulfonate (SDS). The morphologies and polymorphs of CaCO3 obtained were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), and then the effects of different temperature, PAA and SDS concentration on the morphology and polymorph of CaCO3 were investigated. Finally, the formation mechanism of CaCO3 hollow microspheres was studied carefully by the morphology and polymorph of CaCO3 microspheres in the preparation process. The results showed that the calcite CaCO3 hollow microspheres with the particle diameters of 4-7 mu m could be prepared when the temperature was 80 degrees C PAA (M-w = 8000 g/mol) and SDS concentrations were 0.5 g/L and 10 mM, respectively. Meanwhile, PAA and SDS could affect the aggregation behavior and morphology of CaCO3 in the reaction process, then a novel formation mechanism of the CaCO3 hollow microspheres was proposed in this paper.