Environmental Engineering Reference
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resins such as polyvinyl acetate (PVA), polyamide (PA), and polycarbonate (PC),
but it has rarely been applied to thermosetting resins, except for cyanate ester.
Control of viscosity within a narrow range suitable for spinning is often tricky and
resin-specific. By comparison with cyanate ester, thermosetting epoxy generally
has a smaller range of spinning conditions due to its higher reactivity. However,
use of thermo set resins as the matrix for fiber spinning offers advantages of lower
viscosity and reaction with functional groups on the nanotubes [72].
Although, several reports demonstrated that CNTs have good adsorption ca-
pacities for dyes due to their hollow and layered nanosized structures, which in
turn have a large specific surface area, but their high cost restricts their use from
industrial application. Furthermore, separation of CNTs from aqueous solution
is very difficult because of its smaller size and high aggregation property. The
problem of cost and separation of CNTs from aqueous medium can be overcome
by making composites of CNTs with polymers, metal oxide, carbon etc. Such
materials act as a stable matrix to the CNTs. Recently the CNTs have been used as
a promising nanofiller for the preparation of CNT based nanocomposites because
of their excellent improved adsorption, mechanical, electrical and thermal proper-
ties. CNT based composites are expected to be excellent adsorbent because CNTs
provide not only the additional active sites but also larger surface area, which in
turn makes them good adsorbents compared to their parent materials [72].
FIGURE 1.1
Different adsorption sites in a homogeneous bundle of SWCNTs with tube
diameter D: (1) intratubular, (2) interstitial channel, (3) external groove, and (4) exposed
surface of peripheral tube. Sites 1 and 2 comprise the internal porous volume of the bundle,
whereas sites 3 and 4 are both located on the external surface of the bundle.
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