Table 2.
Infrared spectrum analysis of cotton stalk lignin after degradation.
| Peak/cm−1 | Functional group stretching | Ai / A1504 | ||
|---|---|---|---|---|
| ck | 30 day | 60 day | ||
| 3,429 | Stretching in hydroxyl groups | 1.43 | 1.03 | 0.91 |
| 2,925 | C-H stretching in methyl and methyene groups | 1.1 | 0.84 | 1.07 |
| 1720 | C=O stretching in unconjugated ketone | 0.93 | 2.03 | 1.07 |
| 1,595 | Aromatic skeletal vibrations plus C=O stretching | 1.05 | 0.96 | 0.96 |
| 1,504 | Aromatic skeletal vibrations | 0.99 | 1 | 1 |
| 1,462 | C-H deformation in methyl | 1.04 | 1 | 0.97 |
| 1,422 | Aromatic skeletal combined with C-H in-plane stretching | 0.98 | 0.99 | |
| 1,409 | Aromatic skeletal combined with C-H in-plane stretching | 0.97 | 1.1 | |
| 1,330 | Condensation of guaiacyl unit and syringyl unit, syringyl unit, and CH2 bending stretching | 0.97 | 0.97 | 1.01 |
| 1,263 | G ring plus C=O stretching | 1.05 | 1.96 | 0.99 |
| 1,226 | Aromatic C-O stretching (S units) | 1.04 | 1.21 | 0.98 |
| 1,126 | Aromatic C-H in plane deformations | 1.13 | 1.62 | 0.9 |
| 1,029 | Aromatic C-H in-plane deformation plus C-O deform. In primary alcohols plus C=O stretching | 1.02 | 1.02 | 0.85 |
| A1263/A1226 | 1 | 1.62 | 1.01 | |