We present a study of purification of single-walled carbon nanotubes
(SWCNTs) using different oxidation temperatures and chemical treatments. We
have developed a simple two annealing-steps procedure resulting in high
nanotube purity with minimal sample loss. The process involves annealing the
SWCNTs at 300 °C for 2 h with subsequent reflux in 6 M HCl at 130 °C, followed by further annealing at 350 °C for 1 h with reflux in 6 M
HCl at 130 °C. The process results in effective removal of carbon
impurities and metal particles which are associated with SWCNTs production.
The process is less time consuming (complete in 4.5 h) than conventional
acid purification methods which require over 5 h, and less destructive
than conventional methods with a yield of 26%. SWCNT purity was assessed
using Raman spectroscopy, thermogravimetry and scanning electron microscopy
coupled with energy-dispersive X-ray spectroscopy.