Utilization of Plastic Wastes for Synthesis of Carbon Microspheres and Their Use as a Template for Nanocrystalline Copper(II) Oxide Hollow Spheres

The metal- and solvent-free single-step approach for the synthesis of carbon microspheres using various municipal plastic wastes at 700 °C under autogenic pressure is reported. The obtained carbon spheres have been characterized with different microscopic and spectroscopic techniques. The microscopic analysis showed formation of carbon microspheres having diameters of 1–8 μm. Among the different types of plastic wastes studied, only polyethylene, polypropylene, and polyacrylate could be converted into carbon spheres with 100% purity, whereas carbon particles with irregular shapes were also observed in the cases of other plastic wastes. The absence of catalyst makes the carbon spheres free from metal impurities and avoids the further purification process. The synthesis of carbon spheres from plastic wastes proceeds with the formation of aromatic hydrocarbons. The nanocrystalline CuO hollow spheres with a wall thickness of ∼130 nm have been prepared using plastic waste-derived carbon spheres as the template material under ultrasonic treatment.