Table 2.
FTIR vibrational modes assigned to various functional groups in general biochar32.
| Wave numbers (cm−1) | Functional groups |
|---|---|
| 3600–3200 | O–H |
| 1630–1650 | Carboxylate anion |
| 1650–1780 | Carbonyl/carboxyl functional group |
| 2800–3000 | C–H stretching band appears |
| 3000–2840 | Waxes and oils |
| 3500–2800 | Stretching of O–H and C–H give vibrational modes |
| 1800–1500 | Presence of functional group and carbonyl group due to interference of C–H bending |
| 1650–1780 | Carbonyl/carboxyl functional group due to strong band around |
| 1630–1650 | Carboxylate anion |
| ~ 1600 | Carboxylate anion frequency shift due to H– bonding |
| 3200–3500 | Multitude of O–H stretching frequencies in cellulose |
| 2500–2600 | Thiols correspondence to S–H stretching |
| 600–800 | Characteristic range of sulphides, S–H stretching vibration |
| 1000–1300 | Range of sulphoxides due to S=O stretching |
| 1100–1300 | Sulfones ranges |