Characterization of CaCO_3 Nanoparticles Synthesized by Reverse Microemulsion Technique in Different Concentrations of Surfactants

摘要

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/tolueneAvater reverse micro-emulsion system, the co-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 v_(4), v_2 and v_3 modes of CO _3~(-2) absorption bands of calcite. The results of the UV-VIS spectrophotometric analysis indicated that thecalcite (CaCO_3) 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.