A new route to synthesize calcium carbonate microspheres from phosphogypsum

Abstract

In this work, monodisperse spherical vaterite calcium carbonate (CaCO3) was synthesized at room temperature and atmospheric pressure through a simple and efficient ‘phase transfer-precipitation’ route using phosphogypsum (PG) as raw material, sodium gluconate(SG) as phase transfer agent and CO2 as precipitator. CaCO3 samples were characterized by Field-emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD), and Dynamic light scattering (DLS). The composition of the as-obtained sample was almost monodisperse spherical vaterite CaCO3 by adjusting the concentration of SG and other operational conditions. The effects of SG and STP on the formation of CaCO3 microspheres were investigated. The results indicated that the existence of SG inhibited the nucleation and growth of calcite but promoted the formation of vaterite. The effects between SG and Ca2+ played a key role in the formation process of monodisperse spherical vaterite CaCO3. The existence of STP can effectively control the further growth and enhance the uniformity of the particle size of CaCO3 microspheres. These studies are promising for the industrial preparation and further commercial applications of monodisperse spherical vaterite CaCO3.