THESIS - ROC CH ... - FINAL - resubmission.pdf - University of Guelph

process as described. However, it must be noted that the removal may not be complete with the
presence of lignin still detectable at 2920 cm -1 for the SMF samples. Lignin also has the
aromatic C=C stretch from aromatic rings which typically yields two peaks near 1513 and 1433
cm -1 (Sun et al. 2005). Although these peaks were not prominent in the initial SF, the small peak
at 1514 cm -1 could further support the presence of lignin in SMF samples. For SNF specimens,
the absence of these frequencies reflects the lack of lignin content. Upon further investigation,
SNF may contain pectin and hemicellulose residues. In pectic polysaccharides, the region
between 1140 to 1000 cm -1 relates to the stretching vibrations of C-OH side groups and the C-
O-C glycosidic bond (Monsoor 2005). Characteristic peaks can be found near 1100 and 1017
cm -1 from the abundant homogalacturonan content present in pectin (Kacurakova et al. 2000).
SNF specimens had similar peaks at 1093 and 1010 cm -1 which may signify the presence of
homogalacturonan. Another pectic polysaccharide, rhamnogalacturonan, has been reported to
peak near the wavenumbers of 1043 and 1070 cm -1 (Kacurakova et al. 2000). Hemicellulose
content such as xylan and galactan have also been reported to peak near 1047 and 1078 cm -1
(Kacurakova et al. 2000). Similar peaks at 1047 and 1072 cm -1 can be observed in SNF
specimens elucidating the presence of pectin and hemicellulose residues. Since SNF was
released from the main SMF mass after acid hydrolysis, the presence of pectin and
hemicelluloses can be expected as the acid hydrolysis step was meant to solubilize these
compounds (Wang and Sain 2007b). This suggests that SNF fibers observed may be highly
associated forms of cellulose with hemicellulose and pectic residues. This may explain for the
unusual gelling behaviour seen previously with ultrasonication that does not occur with typical
gels.
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