Systems and methods for the extraction of carbon nanotubes (CNTs) by continuous and/or batch processing are disclosed. Generally, a carbon nanotube material including carbon nanotubes (CNTs), carbon nanoparticles (CNPs), and carboxylated carbon (CC) is provided and agitated to produce a well-dispersed mixture. The well-dispersed mixture can be allowed to stand in a vessel having a lower end and an upper end. In some cases, the CNPs settle at the lower end. In some cases, at least some of the CNTs and CC are disposed at the upper end and can be removed in a dispersion, which can be pH adjusted and/or filtered to extract the CNTs from the CC.