Magnetitc separation of Fe catalyst from single-walled carbon nanotubes in an aqueous surfactant solution

We report ail efficient technique to separate ferromagnetic catalyst particles from art aqueous surfactant Solution of single-walled carbon nanotubes (SWNTs) by the use of a 1.3 T permanent magnet. High resolution transmission electron microscopy (HRTEM) demonstrates that SWNTs are coated with a surfactant layer that stabilises the aqueous dispersions of SWNTs. The residual quantities of Fe catalyst (similar to 3%) can be effectively removed from a colloid solution of SWNTs in a magnetic field while absorbance spectra of the initial and purified solutions show that the nanotube diameter distribution remains unchanged. (c) 2005 Elsevier Ltd. All rights reserved.