Patent ID: 8454923

Claim:
A method of extracting carbon nanotubes, comprising: providing a carbon nanotube material comprising carbon nanotubes, carbon nanoparticles, and carboxylated carbon; agitating the carbon nanotube material to yield a well-dispersed mixture of the carbon nanotubes, the carbon nanoparticles, and the carboxylated carbon; standing the well-dispersed mixture for a period of 12 to 36 hours in an elongate vessel having a lower end and an upper end, the well-dispersed mixture being substantially unagitated so as to induce the formation of a heterogeneous mixture wherein at least a portion of the carbon nanoparticles settle to the lower end by force of gravity; removing a dispersion comprising at least a portion of the carbon nanotubes and carboxylated carbon disposed at or near the upper end; adjusting the pH of the dispersion; and separating at least some of the carbon nanotubes from at least some of the carboxylated carbon in the dispersion.