US Patent 8128901 - Purification of CNTs with liquid bromine

http://www.freepatentsonline.com/8128901.html

This patent from William Marsh Rice University teaches a method to purify single walled carbon nanotubes without significantly damaging the nanotubes. Claim 1 reads:

1. A method of removing metal impurities from carbon nanotubes comprising:

treating carbon nanotubes with distilled anhydrous liquid bromine in a substantially oxygen- and water-free atmosphere; and

removing the distilled anhydrous liquid bromine from the carbon nanotubes.