Morphological control of calcium carbonate crystals by polyvinylpyrrolidone and sodium dodecyl benzene sulfonate

The crystallization of calcium carbonate was conducted by the reaction of sodium carbonate with calcium chloride in the presence of polyvinylpyrrolidone (PVP), sodium dodecylbenzene sulfonate (SDBS), or the mixture of PVP and SDBS, respectively. The morphology and polymorphism of these CaCO3 crystals were characterized with scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The results showed that the organic additives and their self-assemblies turn out to be important factors to affect the crystallization habit of CaCO3. In particular, the controlling effect on the morphology depends upon not only the total concentration of PVP and SDBS, but also the relative concentration ratio of PVP to SDBS.