The shoulder at 1731 cm1 in the spectrum of the bran corresponded
to vibrations of the acetyl and uronic ester groups of
hemicelluloses or to the ester linkage of carboxylic group of the
ferulic and p-coumaric acids of lignin (Cherian et al., 2008). This
peak did not appear in the spectrum of the CT-treated nanofiber,
because the bleaching process removed most of the hemicelluloses
and lignin from the CNFs. Siqueira, Bras, and Dufresne (2010b)
attributed bands near 1730 cm1 to deformation of the C]O
groups of xylan, the main component of hemicelluloses. The
absence of this band in the spectrum of the ET-treated nanofibers
confirmed that xylanase acted on the sample during ET.
Fig. 6 evidences that the bleaching (CT) and alkaline treatment