Table 1 Assignments of FTIR peaks in lignin and lignocellulose samples

3318

Stretching vibration of hydroxyl group of hydrogen bond

1734

C=O stretching of unconjugated ketone, carbonyls, and ester groups

1640, 1633

C=C stretching vibration peak in benzene ring

1510

Ring stretching vibration peak of benzene ring

1420

Deformation peak of C–H within vibration plane of aromatic ring skeleton

1267

The C–O stretching of G type lignin

1250

C–O stretching vibration in phenolic hydroxyl group

1240

Stretching vibrations of the in hemicellulose acetyl esters

1106

Carbonyl stretching vibrational peaks linked to lignin and aromatic rings

1030

C–O stretching in cellulose and hemicellulose

896

C–O–C stretching at β-glucosidic linkages in cellulose and hemicellulose