Synthesis of Carbon Nanostructures and CaCO₃ Nanoparticles by Arc Discharge in Mineral Water

The synthesis of multi-walled carbon nanotubes MWCNTs, carbon nanoshells, carbon nanoonions (CNOs), different types of carbon nanostructures and CaCO3 nanoparticles were performed using an arc-discharge method in mineral water. The structures of the synthesized nanostructures were visualized by scanning electron microscopy and transmission electron microscopy (TEM). Furthermore, ultraviolet-visible spectroscopy and thermo-gravimetric analysis (TGA) were used to determine the optical and thermal properties of the synthesized nanostructures. The TEM observations revealed that as-synthesized MWCNTs and CNOs have nominal diameters in the range of 10-20 nm and 30-50 nm, respectively. The CaCO3 nanoparticles were directly synthesized using arc discharge due to the presence of Ca minerals in the mineral water. The production rate of synthesized MWCNTs decreased when the arc current increased above 50 A, and the production rate of different nanoparticles increased with increasing arc current. The thermal-oxidative stability of the carbon nanostructures using TGA was explored separately under argon and oxygen atmospheres.