Effects of cationic surfactant during the precipitation of calcium carbonate nano-particles on their size, morphology, and other characteristics

Microsized calcium carbonates, including precipitated and ground calcium carbonates have been widely used in paper industry. One of the most interesting perspectives to filler technology is the development of nano-sized, high performance, and low cost fillers. However, due to the high cost of nano-sized filler, it is critically important to develop a technique that achieve this perspective. The main goals of this study were to prepare unmodified and CTAB modified nano-calcium carbonate fillers. The effect of CaO concentration, CO₂ flow rate and CTAB surfactant on size and morphology of the prepared CaCO₃ particles were investigated. X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), zeta potential and Fourier transformer infra-red (FT-IR) were used for the characterization of the prepared nano-sized calcium carbonate particles. The results showed that the obtained calcium carbonate was calcite phase. The particle sizes and morphologies of CaCO₃ varied from rhombohedral (15-35nm) to scalenohedral (400nm in diameter and 2μm length) with changing the operating variables, CaO concentration, CO₂ flow rate and surfactants concentration. CTAB neutralized the negative surface charge developed at the CaCO₃ surface and the zeta potential approached to zero. On the other hand, the suggested mechanism of CTAB for synthesis of nano-calcium carbonate was also studied.