A review – Synthesis of carbon nanotubes from plastic wastes

Abstract: A large volume of the waste produced across the world is composed of polymers from plastic wastes such as polyethylene (HDPE or LDPE), polypropylene (PP), and polyethylene terephthalate (PET) amongst others. For years, researchers have been looking for various ways to overcome the problems of such large quantities of waste plastics. On the other hand, carbon nanotubes (CNTs) are materials with extraordinary physical and chemical properties which often have energy- and resource-intensive production processes. In recent years, some researchers have suggested the idea of using plastic polymers as the carbonaceous feed of CNT production. The studies undertaking such a feat are rather scattered. This review paper is the first of its kind reporting, compiling and reviewing these various processes. The production of multi-walled carbon nanotubes (MWCNTs) from plastic polymers is seen to be satisfactorily achievable through a variety of different catalytic and thermal methods in autoclaves, quartz tube reactors, muffle furnaces, fluidized beds, amongst others. Still, much work needs to be done regarding the further investigation of the numerous parameters influencing production yields and qualities. For example, differences in results are seen in varying operating conditions, experimental setups, catalysts, and virgin or waste plastics being used as feeds. The area of producing CNTs from plastic wastes is still very open for further research, and seems as a promising route for both waste reduction, and the synthesis of value-added products such as carbon nanotubes. [Copyright &y& Elsevier]