Effective Separation of Carbon Nanotubes and Metal Particles from Pristine Raw Soot by Ultracentrifugation

A quick and effective method for the separation of single-wall carbon nanotubes (SWCNTs) from impurity particles has been demonstrated. High-purity SWCNTs and impurities, such as metal particles and amorphous carbons, were separated by ultracentrifugation from raw soot containing SWCNTs. The purity of each component was evaluated by scanning electron microscopy, thermogravimetric analysis, and Raman spectroscopy. The advantage of this method is that the impurity particles can be collected as residual soot in the ultracentrifugation process without any loss, while the impurity particles are more or less chemically modified or disappeared in previous purification protocols. The present technique can provide suitable samples for the research of both SWCNTs and impurity particles, particularly for nano-risk assessment.