Green nanocomposite of silica-supported CaO: synthesis by sol-gel method and characterization

The sol-gel method offers several advantages over other techniques for synthesizing nanocomposites, including simplicity, cost-effectiveness, and low processing temperatures. In this study, a silica-supported CaO nanocomposite was synthesized using eggshells as the calcium source and rice husk ash as the silica support via the sol-gel method. The green silica-supported CaO nanocomposite was characterized using various techniques, including BET surface area and porosity analysis, FTIR for functional groups identification, XRD for crystallinity and crystallite size determination, SEM and TEM for surface morphology examination, as well as TGA for thermal stability assessment. The XRD and the FTIR analysis clearly demonstrated the successful synthesis of the silica-supported CaO nanocomposite. The silica-supported CaO composite had a crystalline structure combination of 55.45 % silica and 20.46 % CaO, as well as exhibited the stretching vibrations of Si-O-Si, Ca-O, Si-O-Ca, and Si-O functional groups and a bending vibration of Si-O functional group. The SEM and the TEM images revealed that the composite particles were irregularly shaped and evenly distributed compared to green-silica (G-silica) and green-CaO (G-CaO). The particle size of the composite was distributed in the range of 0.1–100 nm, with a more uniform distribution compared to G-silica (dominant in the range of 80.1–100 nm) and G-CaO (dominant in the range of 0.1–20 nm). TGA results showed that the thermal stability of the silica-supported CaO composite was enhanced by silica support compared to G-CaO. These findings demonstrate that CaO derived from eggshells and silica from rice husk ash are promising materials for the fabrication of multifunctional silica-supported CaO nanocomposite