The peak at
1507 cm-1 attributed to aromatic skeletal vibrations of
lignin [39] disappears completely after chemical purification.
The outstanding peak at 1735 cm-1 also disappears,
which is derived from either the acetyl and uronic ester
groups of the hemicellulose or the ester linkage of the
carboxylic groups of the ferulic and p-coumaric acids of
lignin and/or hemicellulose [40].