Microwave assisted purification of multi-walled carbon nanotubes by potassium permanganate; effect of acid to oxidant molar ratio and treatment time

Carbon nanotubes (CNTs) benefit from excellent electrical and physical properties and they have attracted considerable interest in different applications like sensors and nanocomposites. Synthesized CNTs usually contain carbonaceous or metallic impurities which limit their beneficial properties. In this study, we experimentally investigate the effects of acid to oxidant molar ratio and treatment time on microwave-assisted purification of MWCNTs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm that potassium permanganate (KMnO4) can eliminate impurities such as amorphous carbon and Fe nanoparticles. In addition, an empirical equation for KMnO4 consumption rate is determined based on the results. To sum up, the proposed method can be used as an effective purification route with acceptable removal of impurities.