PURIFICATION OF SINGLE-WALL CARBON NANOTUBES BY ULTRASONICALLY ASSISTED FILTRATION

An efficient method for purification of single-wall carbon nanotubes ( SWNT) synthesized by the laser-vaporization process has been developed . Amorphous and crystalline carbon impurities and metal particles are removed from SWNT samples by ultrasonically-assisted microfiltration. Sample sonication during the filtration prevents filter contamination and provides for a fine nanotube-nanoparticle suspension throughout th e purification process. The process generates SWNT material with purit y of more than 90% and yields of 30-70%, depending on the quality of t he starting material. Nanotubes in purified samples are shorter than i n pristine samples due to some sonication-induced nanotube cutting. Na notube bundles in purified samples are also substantially thicker due to spontaneous nanotube alignment. (C) 1998 Elsevier Science B.V.