Table 4.
Characteristic frequencies and band intensities from the FTIR spectra of the treated and untreated pinewood powder.
| Frequency (cm−1) | Functional group/band assignment | Untreated powder | 1 h treated | 3 h treated | 15 h treated | Reference |
|---|---|---|---|---|---|---|
| 3352 (3447) (no band) |
–OH stretching intramolecular hydrogen bonds Cellulose I (3352), cellulose II (3447) Xylan |
0.26 (0.18) |
0.26 (0.22) |
0.25 (0.22) |
0.26 (0.24) |
[12] [12] [13] |
|
| ||||||
| 1732 | C–O stretching of acetyl or carboxylic acid Hemicellulose and lignin (1730) | 0.07 |
0.04 |
0.03 |
0.00 |
[6] |
|
| ||||||
| 1600 | C=C Lignin | 0.07 | 0.07 | 0.06 | 0.05 | [6, 14] |
|
| ||||||
| 1508 | C–C stretching of the aromatic ring, lignin (1510) | 0.12 | 0.12 | 0.10 | 0.07 | [6] |
|
| ||||||
| 1452 | –OH in plane bending Cellulose I (1455), cellulose II (1470) Asymmetric bending in C–H3 (1465) lignin –C–H deformation Xylan (1461) |
0.11 |
0.11 |
0.11 |
0.11 |
[12] [6] [13] |
|
| ||||||
| 1421 | C–H2 symmetric bending Cellulose II (1419), cellulose I (1431) Weak C–O stretching (1420), aromatic C=C stretch (1433) Lignin (1423), Xylan (1420) [13] |
0.14 |
0.14 |
0.13 |
0.13 |
[15] [13] [13] [13] |
|
| ||||||
| 1263 | Vibration of guaiacyl rings (1270) | 0.20 | 0.18 | 0.16 | 0.12 | [14] |
|
| ||||||
| 1230 | C–O stretching in lignin and hemicel. (1235) | 0.15 | 0.12 | 0.10 | 0.07 | [16] |
|
| ||||||
| 1101 | Ring asymmetric stretching Cellulose I (1111) Cellulose II (1007) |
0.46 |
0.44 |
0.44 |
0.49 |
[12] |
|
| ||||||
| 898 | Asym., out of phase ring stretching Cellulose I (893) Cellulose II, Amorphous Cellulose (895) Xylan (899) |
0.13 |
0.12 |
0.12 |
0.12 |
[15] [15] [13] |