Band position (cm−1) | Bands assigned and Functional group | References of the FT-IR bands | Wavenumber (cm−1)/absorptions | ||
Sample S1 | Sample S2 | Sample S3 | |||
3200 - 3460 cm−1 | O-H stretching in carbohydrate and lignin | ( | 3419/62.41 | 3409/63.15 | 3408/60.15 |
3527/67.42 | 3527/65.54 | ||||
2842 - 2935 cm−1 | C-H stretching (methyl and methylene groups) | ( | 2937/85.34 | 2895/94.38 | 2938/90.97 |
1731 - 1739 cm−1 | C=O stretching (unconjugated ketones) in hemicellulose | ( | 1727/84.02 | - | 1732/87.46 |
1640 cm−1 | Absorbed water | ( | 1645/79.18 | 1637/74.41 | 1647/73.54 |
1625/74.51 | 1636/72.89 | ||||
1624/72.43 | |||||
1595 cm−1 | Aromatic skeletal, C=O stretch in lignin | ( | 1592/84.11 | 1595/86.84 | 1594/87.92 |
1506 - 1515 cm−1 | C=C stretching, Aromatic ring (lignin) | ( | 1511/78.06 | 1508/89.24 | 1507/89.56 |
1460 cm−1 | C-H asymmetric deformations in -CH3 and -CH2- | ( | 1461/78.27 | 1461/82.35 | - |
1425 cm−1 | CH2 bending cellulose | ( | 1426/77.13 | 1420/83.32 | 1418/78.53 |
1375 cm−1 | CH bending in cellulose | ( | 1373/76.37 | 1384/79.7 | 1384/53.62 |
1335 cm−1 | OH (plane bending in cellulose ‘amorphous’) | ( | - | - | 1336/78.67 |
1316 cm−1 | CH2 wagging (crystalline cellulose) | ( | 1318/76.94 | 1320/79.76 | 1320/79.90 |
1269 cm−1 | guaiacyl ring, C-O in lignin | ( | 1269/72.91 | 1269/81.77 | - |
1235 cm−1 | Acetyl and carboxyl vibrations and C=O stretching in Xylan and lignin | ( | 1233/74.14 | - | - |
1159 cm−1 | C–O–C asymmetric stretching vibrations (Carbohydrate) | ( | 1159/69.09 | - | - |
897 cm−1 | C-H deformation in cellulose | ( | 896/80.09 | 895/85.46 | 863/89.65 |
806 cm−1 | Aromatic C-H (out of planedeformations) in lignin | ( | 806/81.23 | 807/84.77 | 808/87.07 |