Characterization of CaCO3 Nanoparticles Synthesized by Reverse Microemulsion Technique in Different Concentrations of Surfactants

Calcium carbonate nano-particles were synthesized by a reverse micro-emulsion method at room temperature with Tween® 80 and Span® 80 as co-surfactants. The nano-particles synthesized were surface modified by stearic acid. An important operating variable in the Span 80-Tween 80/toluene/water reverse micro-emulsion system, the ?-value (water/surfactant molar ratio) was investigated. The material was characterized by SEM, TEM, X-Ray Diffraction (XRD), FT-IR, UV-VIS and TGA/DTA techniques. 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. The XRD analysis at room temperature showed single phase formation of calcite. FT-IR confirmed the formation of calcite with characteristic absorption bands observed at 712, 881 and 1460 cm-1, corresponding to ?4, ?2, and ?3 modes of CO3-2 absorption bands of calcite. The results of the UV-VIS spectrophotometric analysis indicated that the calcite (CaCO3) is an indirect gap material [(5.60 eV (30 wt.% surfactant), 5.40 eV (36 wt.% surfactant) and 5.36 eV (42 wt.% surfactant)] at room temperature.