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Purification of Single-Wall Carbon Nanotubes by Controlling the Adsorbability onto Agarose Gels Using Deoxycholate
journal contribution
posted on 2012-05-03, 00:00 authored by Atsushi Hirano, Takeshi Tanaka, Yasuko Urabe, Hiromichi KatauraOne of the key challenges to the industrialization of
single-wall
carbon nanotubes (SWCNTs) is the commercial-scale production of highly
purified SWCNTs separated into metallic and semiconducting species.
In the present study, the purification of SWCNTs, i.e., the removal
of amorphous carbon or bundled SWCNTs, was performed by quantifying
and controlling their adsorbability onto agarose gel. The quantification
of the adsorbability was achieved by assuming the Langmuir isotherm,
and control over the adsorbability was exerted using 0.05–1%
sodium deoxycholate (DOC). The results show that the adsorbability
depends on the concentration of DOC. At a low DOC concentration (approximately
0.05%), impurities such as amorphous carbon or bundled SWCNTs were
preferentially adsorbed onto the gels, whereas, at an intermediate
DOC concentration (ca. 0.25%), high-purity SWCNTs were mainly adsorbed
onto the gels. Thus, the impurities, which are difficult to remove
by conventional methods, could be separated from unpurified SWCNTs
by controlling the adsorbability, leading to the extraction of high-purity
SWCNTs. In the purification, diameter-selective separation of SWCNTs
was also observed. The purification method using a gel column can
be conducted simply and continuously, so that it can be applied for
the high-throughput production of high-purity SWCNTs.