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Exploring the Influence of Reaction Parameters on the Preparation of Calcium Carbonate by Spontaneous Precipitation

Different polymorph and morphology of CaCO3 powder are prepared by spontaneous precipitation method in the presence of sodium citrate and NaOH at ambient temperature. The influence of spontaneous precipitation reaction parameters such as aging time, pH value, the concentration of complexing agent sodium citrate on the crystal phase, particle size and morphology of the precipitated calcium carbonate is studied in this paper. The prepared samples are characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The results show that the aging time, the pH of the solution and the concentration of sodium citrate turned out to be important for the morphologies and crystal phase of CaCO3. Increasing the aging time, the content of vaterite decreases slightly, whereas the opposite effect is observed for increasing pH. When pH value is 13, pure calcite irregular nanoparticles can be prepared. In the presence of sodium citrate, the content of vaterite increases as the increasing of sodium citrate. When the concentration of sodium citrate is increased to 0.1 m, uniform vaterite microsphere with 5 µm size can be obtained.