Morphological and Thermal Properties of CaCO3 Nanopowders Synthesized by Reverse Microemulsion Technique

As an important inorganic material, calcium carbonate (CaCO3) has been widely used as fillers in paper making, plastics, rubbers and coating due to its low price and abundant availability. Nanoparticles of calcium carbonate enhance their properties manifold. This article presents reverse micro-emulsion method for the synthesis of calcium carbonate nanoparticles (nano-calcite). A reverse micro-emulsion system of Surfactants (Span 80 & Tween 80)/Toluene/water was selected for this study due to its wide stable-region. CaCO3 particles synthesised were surface modified by stearic acid. The effect of different concentrations of surfactants (span-80/tween-80) on the synthesis of nano-CaCO3 was investigated. The material was characterized by SEM, TEM, X-ray diffraction (XRD) and TGA/DTA techniques. X-ray diffraction patterns (XRD) confirmed cubic structure of nano-CaCO3 showing characteristic reflection of calcite phase. The size of the nano-particles was determined by TEM as well as XRD data for various concentrations of surfactants. The results showed that the size of the nano-particles was influenced by the concentration of the surfactants in the micro-emulsion system. TGA results demonstrated that decreasing the size of nano-particles resulted in the weight loss: these thermal decompositions may be attributed to calcite.