Table 3 Functional groups associated with FTIR spectra of rice straw and its derived biochar.
Rice straw | Rice straw-derived biochar | ||
|---|---|---|---|
Wavenumber (cm− 1) | Functional group | Wavenumber (cm− 1) | Functional group |
3665–3396 | O–H stretching of cellulose or hemicelluloses39 | 3684–3641 | Free O–H stretching of phenolic and alcoholic–OH41 |
3007–2918 | C–H stretching of cellulose39 | 2964–2923 | C–H stretching of cellulose39 |
1730–1632 | Acetyl (C=O) group in hemicellulose or lignin39, C=C stretching of aromatic components 40 | 1749–1691 | Acetyl (C=O) group in hemicellulose or lignin39, C=Cstretching of aromatic components40 |
1493–1426 | C-H deformation of lignin39, C=Cstretching, indicative of lignin and aromatic C41 | 1680–1599 | Aromatic skeleton stretching of lignin39 |
1410–1366 | C-H deformation in various polysaccharides42 | 1570–1440 | C-H deformation of lignin39, C=Cstretching, indicative of lignin and aromatic C41 |
1293–1217 | Guaiacyl lignin43 | 1292–1203 | Guaiacyl lignin43 |
1161–1094 | C–O–C symmetric stretching in ester groups of cellulose and hemicellulose41 | 1180–1102 | C–O–C symmetric stretching in ester groups of cellulose and hemicellulose41 |
931–882 | Aromatic C–H out of plane bending44 | 921–883 | Aromatic C–H out of plane bending44 |
